Title of Invention | DEVICE AND PROCESS FOR CLEANING FLUE GAS |
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Abstract | Title : DEVICE AND PROCESS FOR CLEANING HOT FLUE GASES A cleaning device for hot dust laden flue/process gases comprising means for receiving hot flue gas; at least one vertical hollow gas flow path or channel for the hot dust laden flue gas with inlet at top and outlet at bottom ; at least one hollow gas flow path or channel for the cooled cleaned flue gas with inlet at bottom and outlet at top arranged adjacent to the said flow path or channel for hot flue gas; the adjacent walls of the said channels being made of thermally conducting material with or without intervening non conducting zones; means for receiving dust placed below the said channels; means for emission of cleaned flue gas. A process for such cleaning comprising receiving hot dust laden flue gas by means for receiving hot flue gas and transferring to vertical hollow gas flow path or channel for hot flue gas ; downward passing the hot dust laden flue gas through said channel by inlet at top and outlet at the bottom; upward passing of the cleaned gas after removal of dust and taking 'u" turn from the outlet of the hot flue channel to the inlet of the channel for the cooled cleaned flue gas with inlet at bottom and outlet at top arranged adjacent to the said flow path or channel for hot flue gas; simultaneous dissipation of heat through the adjacent walls of the said channels being made of thermally conducting material with or without intervening non conducting zones causing decrease in viscosity of the dust laden gases from top to bottom; separation of dust and agglomerated particles from the hot flue gas by gravity and arresting the same in the means placed below the said channels; directing the cleaned flue gases from the cold flue channels for emission through means for emission of cleaned flue gas. |
Full Text | FIELD OF THE INVENTION: The present invention relates to a device and process for cleaning flue gas as well as process gas. In particular the present invention relates to a thermal energy recuperation type flue gas cleaning device for hot dust laden flue gases and process thereof. The device consumes less power and nominal water yet effectively cleans flue gases. The device comprises vertical hot flue gas channels through which the gas to be cleaned in passed from top to bottom and simultaneous cooling of the hot flue gas by dissipation of heat through the adjacent walls of the channels leading to increasing viscosity of the dust particles to aid their separation from the flue gas and collecting in dust collector and passing cleaned flue gases through cold channels so that they are simultaneously reheated as they pass from bottom to top of the device to be lead outside. The device may be used for cleaning of the hot dust laden flue gases emitting out from any combustion sources or incineration source or thermal reduction, source. The device can be usedjmjependently or can be put in series to the existing cleaning devices as cyclon^ESF^\bag filter, venturi scrubber etc. BACKGROUND OF INVENTION The increasing air pollution is a serious cause of concern at all levels. To control the air pollution emitting from various types of combustion incineration and reduction processes, the flue gases are presently being cleaned by various methods such as Cyclone, Ventury Scrubber, Wet Scrubber, Box Type dust Catcher, Bag filter, ESPs, and such other devices. In most of these devices the hot flue gases are required to be cooled to a certain temperature for cleaning. There after the cleaned gases require to be mechanically blown out with the help of a mechanically driven blower or fan. All these processes consume lot of water in cooling and power in blowing; inspite of this, effective cleaning of flue gas is not achieved. In some of the wet scrubbing processes, acidic effluents are generated, which again is a problem for the environment. Of late a large number of sponge iron rotary kilns have been established and are being established, which emit enormous quantity of hot dust laden flue gases. The air pollution control and cleaning of these flue gases require huge investment and consume lot of power and consume lot of water too. The direct water scrubbing also cause huge amount of acidic effluent generation. At present the flue gas cleaning and particulate matter removal is done in the following manner. Hot dust laden flue gases emerging out of the reducing metallurgical process (such as DRI and sponge iron, blast furnace, sintering kiln, cement kiln etc. process) which contain sufficient quantities of un-combusted reducing gases are first pureed with air for combustion of un-combusted gases, in after burning chamber for effective combustion of these un-burnt gases, which increases the temperature and the volume of the flue gases. Then the hot flue gases are cooled in a GCT (gas Conditioning Tower) by spraying water on it, which again consumes lot of water and increases the gas volume due to the formation of steam and also generate acid, due to hot contact ofthese gases with water vapor. The hot un-cleaned flue gases are either passed after ABC/GCT or before through widened path called dust settling chamber, which arrest or allows to settle the course particles in the flue gases. The flue gases normally travel horizontally in this chamber. Then these gases are again cooled-directly or indirectly by air or water up-to 140°C to 200°C and then passed through ESP or bag filter or cyclone or wet scrubber and then these cleaned gases are drafted out through the chimney with the help of the FD/ID Fan; at the same [140 to 200°C] temperature, which requires enormous power for emitting or blowing out through chimney. At present in the above-explained course of cooling of the hot gases, the cleaned cooled gases are not used for extraction of thermal energy from hot flue gases. The cooling of the gases is done in various ways, which involves direct purging of water or indirect cooling through water or air. But also in the above-explained process of cooling the dust is normally not removed. The dust is normally removed after cooling. Only in case of wet scrubbing the dust also is washed out as well as the flue gases get cooled. The cleaning is carried on by various equipments such as cyclone dust collector, wet scrubber, venturi scrubber, dust catcher, electro-static precipitator etc. Most of these equipments are different in themselves, as explained below: Cyclone: Cyclone dust collector can be used to clean the gas in hot condition or cold condition of the gas too. But cooling of the gas is independent of the gas cleaning. In most of these gases cooling of the gas is done independently or separately. In these systems the gas cooling is not the part of the gas cleaning. In the Cyclone dust collector the gas is given a circular movement and due to the increasing circular velocity of the gas the dust are separated due to centrifugal force and trapped out in the bottom. There is no change in the temperature profile of the flue gas during the cleaning or separation of the dust. Almost the same temperature remains in the gas at the inlet and outlet of the cyclone. The dust collected at the bottom of the cyclone is some times collected in the water bath trough, but this water bath is slightly different then, what is proposed by me. Specially for the reason that the dust in cyclone is normally released from the flue gas stream at a point higher than the water bath, inside the cyclone and only the dust falls out of the flue stream or cyclone due to the centrifugal force and continue to fall due to gravity towards the bottom pot where dust is collected, thus in this case this box actually works only acts as a dust storage bin. Dust Catcher: Even in the conventional dust catcher the flue gas of any temperature is let into a larger box of a greater volume where the flue gas looses its velocity and the dust buoyant in it fall down due to the gravitational pull. Enough time is provided for settlement of the dust. No cooling is designed and the gas leaves the chamber in the same temperature normally such dust catcher are horizontally placed. Wet Scrubber: It is a device in which the flue gases are passed through a water/ liquid shower in which the dust are washed out of the gas stream and the dust is collected in the bottom as water slurry. The gas temperature also falls down thus requires mechanical power for drafting out through the chimney. The principle of dust separation is actually wet washing of the gases. Venturi Scrubber: The dust laden flue gases are forced downwards through a narrowed down venturi opening which is placed above a water bath. Thus due to the narrowed venturi opening the flue gas attain a greater velocity which is also attained by the particulate/ dust matter. Thus the dust or the particle get trapped into the water bath due to the jet force of the gases created at the venturi. Here the gravitational force is not so much important as the force created by venturi jet is normally higher than the self attained gravitational momentum. Also there is no change is created in the flue gas temperature, for separation of the dust. The cleaned gas are then forced out at the same temperature to the atmosphere by FD/ID fan through a chimney. Electrostatic Precipitator (E.S.P.): In the electrostatic precipitator the gases are cooled up to 160°C or below by various methods but none has so far used the cooled and cleaned waste gases for cooling the hot waste gases for cooling, cleaning through ESP. The cooled gases are passed through electro-statically charged plates charged with electricity and the dust get collected on these plates. Bag Filter: In this process the cooled gas below 170°C temperature is forced through a fabric which arrests the dust on it's pore and the collected dust is periodically collected by de-dusting, whereas in proposed device no filtration material is used. Known cooling method of hot flue gases: Mostly the hot flue gases are presently cooled independently and separately out side the above-mentioned gas cleaning devices. The hot flue gases are cooled in a number of ways: i. Direct spraying of water on hot flue gases: This consumes lot of water, creates acidic effluent, increases the volume of hot flue gases, causes slurry due to the dust in particulate matters. ii. Indirect cooling through water Tubes: This also consumes lot of water, requires cooling tower for cooling of heated up water, requires power for flow of cooling water and cooling tower fan. iii. Waste heat Recovery in combustion Air/or Air Cooling: a) in this process the heat is introduced in the combustion air which is utilized in the combustion, but cools only to a small extent. b) the flue gas may require further cooling with water or air. c) cooling done only by the atmospheric air causes lot of heat built up in the ground atmosphere and power is required to blow the cooling air as well as the flue gases. d) huge waste heat exchanger is required for the air cooling. There are several such other known process for the flue gas cooling. There are several other ways for dust collection, which is difficult to narrate all but none of these have the following features which are claimed by me in the proposed process. I. hot dust laden flue gas is gradually cooled by transferring the heat into cleaned cooled flue gases. II. hot dust laden flue gases travel downwards into a bell type or cone type of flue channel or parallel channel where in the dust laden flue gases get cooled to loose their viscosity and volume both thus a differential traveling speed is achieved between the gas and particle and reduced drag force is available for particles to settle. III. heat of the hot flue gases is recuperated to help the emission of the cleaned cooled flue gas. IV. draft control device used for maintaining the positive pressure in the kiln or combustion chamber is used to impart the increase in the entrance velocity of the flue gases into the cleaning devices. DRAWBACKS OF THE KNOWN ART: The known art has its own merits and demerits, which varies according to the equipment. But the main drawback is that the thermal energy contained in the flue gases is not imparted back in the emitting cleaned cooled flue gases. Thus in the process of cooling there is lot of energy required and lot of water or air is required to cool the hot flue gases, thereafter a lot of power is required for blowing out the cleaned cooled gases through the chimney. I. Draw back of the Known gas cleaning Systems: Electrostatic Precipitator (ESP): 1. needs lot of power to electrically charge the particles and to collect. 2. needs CO free gases or can cause explosion. 3. electrically resistant dust can not be trapped effectively. 4. need lot of water to cool the flue gases. 5.need lot of power to blow out the cleaned flue gases through chimney. Cyclone: I. dust removal is better in coarser particles. II. a great pressure drop is there thus needs lot of power to meet the pressure drop. III. need lot of water to cool the flue gases. IV. need lot of power to blow out the cleaned flue gases through chimney. Dust Catcher: Needs huge volumetric area Wet Scrubber: I. Generate acidic effluent. II. Consumes lot of water. III. Need lot of power to blow out the cleaned flue gases through chimney. Venturi Scrubber: I. Generate acidic effluent. II. Consumes lot of water. III. Need lot of power to blow out the cleaned flue gases through chimney. Bag Filter: I. can operate only at low temperature. II. the bag filters get burst out. III. there is a greater pressure drop with build up of the dust cake. IV. need lot of water to cool the flue gases. V. need lot of power to blow out the cleaned flue gases through chimney. II. Draw back of the known gas cooling system: i. in the present flue gas cooling systems lot of water is consumed and when direct water spraying is done then acid is formed. When cooled with air huge heat exchangers are required and lot of power is required for cooling air blowing. To avoid all these problems the present device has been developed, which consumes less power and consumes nominal water and cleans the flue gases, better than the conventional flue gas cleaning mechanism. OBJECTS OF THE INVENTION: Thus the primary object of the present invention is to provide a flue gas cleaning device which overcomes the drawbacks of known cleaning devices as discussed above. A further object of the of the present invention is to provide a flue gas cleaning device which consumes less power and nominal water yet effectively cleans hot dust laden flue gases. Another object of the present invention is to provide a flue gas cleaning device which utilizes variation of temperature, viscosity, drag force of the flue gas. Yet another object of the present invention is to provide a flue gas cleaning device which effects cooling and cleaning of flue gas simultaneously. Yet another object of the present invention is to provide a flue gas cleaning device which reheats the cleaned flue gas SUMMMARY OF INVENTION According to one aspect of the present invention there is provided a cleaning device for hot dust laden flue/process gases comprising: i) means for receiving hot flue gas; ii) at least one vertical hollow gas flow path or channel for the hot dust laden flue gas with inlet at top and outlet at bottom ; iii) at least one hollow gas flow path or channel for the cooled cleaned flue gas with inlet at bottom and outlet at top arranged adjacent to the said flow path or channel for hot flue gas; iv) the adjacent walls of the said channels being made of thermally conducting material with or without intervening non conducting zones; v) means tor receiving dust placed below the said channels; vi) means for emission of cleaned flue gas. According to another aspect of the present invention there is provided a process for cleaning hot dust laden flue/process gases comprising : i) receiving hot dust laden flue gas by means for receiving hot flue gas and transferring to vertical hollow gas flow path or channel for hot flue gas; ii) downward passing the hot dust laden flue gas through said channel by inlet at top and outlet at the bottom; iii) upward passing of the cleaned gas after removal of dust and taking 'u" turn from the outlet of the hot flue channel to the inlet of the channel for the cooled cleaned flue gas with inlet at bottom and outlet at top arranged adjacent to the said flow path or channel for hot flue gas; iv) simultaneous dissipation of heat through the adjacent walls of the said channels being made of thermally conducting material with or without intervening non conducting zones causing decrease in viscosity of the dust laden gases from top to bottom; v) separation of dust and agglomerated particles from the hot flue gas by gravity and arresting the same in the means placed below the said channels; vii) directing the cleaned flue gases from the cold flue channels for emission through means for emission of cleaned flue gas. DETAILED DESCRIPTION OF THE INVENTION: The vertical hollow gas flow path or channel for the hot dust laden flue gas referred as the hot flue channel, is essentially a vertical hollow gas flow path, called channel placed almost perpendicular to earth at an angle almost or nearest to 90° or such angle nearer to 90o to earth, by which the gravitational pull force created on the dust particles or particulate matters, is not obstructed or not restricted or not resisted, during free fall of the particles contained in the gases. The number of hot flue channels can be one and in plurality to one and upto any numbers as per the requirement depending on the volume of the gases and temperature of the gases and composition of the gases. The shape of the hot flue channel can be made in a number of ways, as parallely placed rectangular path, or parallely placed square path, or parallely placed circular (pipe like) path, or as hexagonal or triangular, or oval, or semi circular, path created out of the plain surface walls or corrugated surface (walls), finned surface (walls) or corrugated finned surface (walls) or rough surface walls etc, in either side or on both side or a combination thereof of any such type or surface, to facilitate better heat transfer. The material of construction for such walls can be metallic or non metallic material (such as SiC or pure alumina) having good thermal conductivity and enough thermal endurance. The walls so created can be in thermal continuity or can be horizontally broken, by providing a thermally non-conducting insulating material and thermally stable insulating materials, in the horizontal plain of the walls at certain intervals, to break the "thermal conductive continuity" in the hot flue channel walls from top to bottom and to avoid an isothermal temperature build up in the hot flue channel walls from top to bottom. These are referred to as thermal breakers, the thermal breakers can be created by slitting the walls and packing or sealing it with heat insulating material and heat resistant material. The passage volume of the hot flue channel can be increased gradually towards the bottom side, by gradually increasing the gap between both the facing walls (in "X" axis) as well as by increasing the total horizontal width (in "Y" axis) of the hot flue channel walls. Another essential part of this embodiment is to create a gradual cooling of these down flowing hot gases from top to the bottom in the hot flue channel, by means of conducting out the thermal energy contained in the hot gases through the thermally conductive metallic walls or thermally conductive non metallic walls, enclosing the hot flue channel and thereby forming this hot flue channel, without restricting or resisting the free fall of the dust falling down along with the down flow of the hot flue gases. Another essential part of this embodiment is to have an inlet at the top of these hot flue channels for entry of the hot flue gases and an outlet at the bottom for the exit of the cooled gases. Another important part of this embodiment is to provide a dust receiving box filled with any liquid such as water or oil or mixture of it, placed below the hot flue channels in sealed communication to the hot flue channels bottom on one side and in sealed communication to the exit of the cooled gases on the other-side, and also with provision to gradually remove the dust collected in it without causing any potential pressure disturbance to the flow of the gases falling down from the hot flue channels and particulate matter falling down from the hot flue channels and also with the facility to maintain the liquid levels in this dust collection box to the desired levels or operate without any liquid when the condition or design so permits. In case the dust Being separated out are of the very course nature then this bottom hopper can be kept empty without any liquid also. Another essential part of the present embodiment is creation of cooling passage surrounding the hot flue channels where in the cooled cleaned gases or fresh air, or any other cooling gas, or water or liquid can be flown in reverse up flow manner or cross up flow manner or any other up flow manner to ensure effective removal of heat for gradual cooling (upto desired temperature) of the hot gases flowing down in the hot flue channels. An important feature of the present device or process is gradually cooling mechanism for cooling the hot flue gases traveling down in the hot flue channel, it also can be created in a number of ways, as explained below: a) Allowing the reverse up flow or reverse flow or cross flow, through the cooling passage created between the hot flue channels here in with referred to as "cold flue channel" in this embodiment, by flow of the cleaned cooled gases to cool the hot gases and get heated up to facilitate better chimney draft, for exit in to the atmosphere or b) Allowing the up flow or reverse up-flow; cross up flow of the ambient air or cooled air into the cold flue channel and then administering these heated up hot air directly into the chimney; or letting out the heated up air in to open atmosphere; and forcing the cleaned cooled gases through chimney by means of ID/FD fan or letting it out through the self created chimney draft. c) Flowing the water or any other liquid in the cooling channels called cold flue channel, or jackets provided around the hot flue channel and forcing the cleaned cooled gases through chimney by means of ID/FD fan. Additional features which may be present along with these above essential features, are as under: 1) Draft Control Mechanism:. This can be provided at the entrance point of the each hot flue channel for narrowing down the entrance orifice area with a suitable port narrowing mechanism, or arrangement, which will suitably control the draft for the source flue gas path, as well as enhance the entrance speed of the hot gases entering the hot flue channels, which imparts greater kinetic energy created due to the enhanced entrance velocity of the gases and thereby on the particulate matters too. The draft control mechanism can be created in a number of ways one of such possible way is illustrated in this embodiment, but is not restricted to this and can be done in several other manners, which are known to the people skilled in the art. The draft control mechanism can be kept even at the outlet point of the, flue gas or cleaned flue gases or at any other suitable location or can be controlled in any other manner known to the people skilled in the art. The draft control mechanism is not an essential component of this cleaning device but definitely can be used for better cleaning and for designing a more compact and efficient system. Alternative draft can also be controlled by narrowing down the path of the hot flue gas flow at any suitable or required position. 2) Pre cooling and Pre cleaning: In case of temperature of flue gas or the process gas is very high i.e. above 900°C and the dust load also is too high i.e. above 50 gm/Nm3. Then in such case a pre-cooling and pre- cleaning device can be installed before this device to bring the temperature of the hot flue gases to below 900°C and the dust load to below 50 gm/Nm3. The pre-cooling device can be made in any known method. However the reheated cleaned flue gases or process gases coming out the above flue gas cleaning device can be routed through this pre-cooling system to cool the very hot dust laden gases, as well as to add heat into the cleaned cooled flue gases or process gas, for emitting through chimney or for using in any process. 3) Secondary cleaning and reheating: Whenever the property of flue dust in process gases or flue gases, is such that the desired level of dust could not be removed or totally cleaned from the above devices and yet further dust removal is essential, then the additional cleaning of primarily cleaned and cooled flue gases can be performed by withdrawing the cleaned cool gases with the help of a ID/FD fan from the bottom of cold flue channel and passing those gases through the conventional equipments like cyclone, wet scrubber or ESP or bag filter etc. After this is cleaned then the finally cleaned gases are fed back into the bottom of the cold flue channel slightly above withdrawal port/ gas seal arrangement. In such cases the bottom of the cold flue channel is provided with a gas flow locking arrangement or gas seal to separate the two withdrawal port and release port and to avoid the remixing or return of finally cleaned gases to the withdrawal port and to allow the clear passage for the finally cleaned flue gases to move upwardly for emission through the chimney. Unlike the cyclone dust collector in the device of present invention the dust in the flue stream impinges directly into the bath whereby the dust gets stuck into the water/ liquid bath, when the flue gas take an "U" turn from hot channel to cold channel. This also restricts the dust to get rebuoyant in the flue stream. So the principle of separation in the cyclone is first the centrifugal force for separation from flue gas stream and gravitational force for collection. Whereas in the proposed device the force of separation is accelerating gravitational pull in the particulate matter, due to reducing viscosity of the gases and reducing velocity of the gases. Although the above embodiment is designed primarily to remove the dust and particulate matters from the hot gas stream and to operate at the available positive pressure of the source and the draft created by the natural draft of the chimney but can be operated by inducing a mechanical draft by any electro-mechanical means. In addition to the above; the device can also be operated at higher pressures, in case of the requirement by suitably strengthening or keeping a higher thickness of the hot flue channel walls, and by creating a proper seal at the bottom hopper level. However in addition to the above "the system" can also be used for cleaning or removing or scrubbing of the gases by spray of suitable liquid absorbents for the absorption of the gas or gases, or by condensation, from the gaseous pollutants present in the flue gas/ process gas/ air, enabling removal of any specific gas, such as water vapour or CO2, SOx, NOx, H2S etc present in the gas. Besides the system can also be used for reheating of such cleaned gases or can be used for generating the hot combustion air, or for generation of hot water stream or for generation of steam at low pressure, or can be used for generating any other hot gases such as O2, CO2, N2, CO, H2, CH4, or any other gas. (which will require such gases or liquid to be passed through the cold flue channel, which is deployed in this device to recover the heat from the hot gases). All these features are the additional features of the device and are independent of each other and are not limited to what is described specifically in the present embodiment, but shall extend to all such application and modification created or adopted by those who are skilled in the art, by using the same principles. Another feature of the present embodiment is to increase the path flow cross sectional area of the hot dust laden gases flowing down through these hot flue channels, gradually increasing the volume or cross sectional area of hot flue channels, from the top of the channel towards the bottom of the channel to reduce the velocity of the hot gases flowing down. In another alternative arrangement the path flow cross sectional area of the hot dust laden gases flowing through hot flue channels can be gradually decreased and then increased after a certain height, depending on the requirement. Another feature of the embodiment is to reduce the velocity of these gases flowing down from the top of the hot flue channel to the bottom of the hot flue channel, by increasing the density of the hot gases by gradually reducing the temperature of these hot gases. Another feature of the embodiment is to cool such hot gases which contain H2O in the vapour form to such a temperature level that water vapour get condensed and the liquid water is absorbed or adsorbed by the particulate matter, to become heavier or to attain higher density than their own bulk density, and form agglomerate which will facilitate better dust removal. In the process of dust separation as well as if required scrubbing of the pollutant gases, or unwanted gases from the gas stream, be it a flue gas or a process gas or mixture of other gases or only one gas or air, having higher temperature than ambient and loaded with dust, emitting out of any process vessel, or furnace, or kiln or from any such enclosure emitting the gases through an outlet, the such gas stream is led to a path which is vertically placed, oriented towards gravity, which is termed as hot flue channel, which comprises of the thermally conductive metallic walls, which are parallelly divided in to segments at certain interspaces, and such dividing gap in the wall is hermetically sealed, with any heat insulating heat resistant material. The walls having plain surface or corrugated surface to finned surface, rough surface, or studded surface or such distorted surface so as to facilitate the best possible heat transfer from the hot gases flowing down through it in to cold gases flowing up in the parallel path. Such hot dust laden gases are flown into single or a number of such hot flue channels, which are parallelly placed; at the available flow velocity or with enhanced flow velocity by narrowing down the entry port or narrowing down the path at any other suitable level, according to the available positive pressure from the source of the hot gases. Simultaneously inducing the reduction in the viscosity of the gases by gradual cooling of the gases through the outwards thermal conduction from the thermally conductive walls enclosing the hot flue channels thus creating a decreasing viscosity gradient from higher viscosity at the top to lowest at the bottom or outlet of the hot flue channel outlet port. Simultaneously providing an opportunity to very finely divided particulate matters to agglomerate together or get clustered. Thus reducing the drag force exerted on the particles to keep these buoyant in the gas stream and allowing it to accelerate towards the bottom at greater velocity due to gravity than the gas flow velocity, consequently inducing the required differential and enhanced kinetic energy added due to the gravitational pull in the particles to fallout of the hot gas stream. Thus it is a process of separation of dust from the hot or warm gases which have higher temperature than ambient temperature [or such higher temperature than a lower temperature, which can be economically achieved] by indirect cooling of the hot gases through water, liquid or oil, or such source of cool gases or cool air, cool liquid etc., by which the hot or warm gases can be gradually cooled to the best economically feasible temperature level, to reduce the viscosity and volume of gases. Thus the process employs the principle of cooling of the hot gases preferably to ambient level or if essentially required then lower than ambient temperature. The fundamental process used remains the same to primarily cool down (mostly through indirect heat transfer cooling) the hot dust laden gases in a manner (i.e. in a vertical flowing path) by which the removal of dust particles due to acceleration due to gravity is facilitated by reduction in viscosity and reduction in gas velocity and increase in the particle fall velocity and removal is further facilitated by moistening of the particles and further facilitated by clustering or agglomerate fine particles, by reduction in the velocity of the gases and can also be facilitated by mist scrubbing or water spraying on the particles, and also create an additional facility of removal of desired- undesired gases like SO2, NOx, CO2 is possible by mist spraying of the absorbent or alkaline solutions. It is further facilitated to reduce the power requirement for emitting the cleaned gases to atmosphere, by permitting the cleaned gases to get hot by drawing the thermal energy from the hot gases, in their way to exhaust out through the chimney. It also provides a facility to enrich the partially spent or partially oxidized, process gases or partially oxidized flue gases having economically combustible gases for further use in any process. It also facilitates to reheat these cleaned gases for further applications in hot (reheated) condition. But the main spirit of the invention remains to allow the dust to fall due to change in the viscosity of the gases and changed drag force and by increase in particle drop velocity added due to the gravitational force also caused due to accumulation of moisture present in the gases or when injected in the gases in hot condition before cooling, and due to the accumulation and clustering caused in the particulate matters by the operation of the device. Other alternative embodiments are possible without departing from the spirit of the invention and no limitations are to be inferred except as specifically set forth in the appended claims. The invention is now described with non limiting illustrative accompanying drawings BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 :front side cross sectional view of the device of the present invention; Figure 2 : lateral side cross sectional view of the device; and Figure 3A: hot flue channel with inverted "V" type path and cold flue channel with cross flow path Figure 3B: device with hot flue channel with inverted "V" type path and cold flue channel with cross flow path Figure 4: hot flue channel with "V" type path and cold flue channel with inverted "V" and cross flow path Figure 5A: front view showing parallel path of hot flue channel and horizontal arrangement of cold flue channel as cross flow cold flue channel Figure 5B: side view showing flow of flue gases in horizontal type cross flow cold flue channel Figure 6A: hot flue channel with upper part being of "V" shape and lower part with inverted "V" shape arrangement and adjoining vertical type cold flue channel arrangement Figure 6B: hot flue channel with upper part being of "V" shape and lower part with inverted "V" shape arrangement and adjoining horizontal type cold flue channel arrangement Figure 7: movement of flue gases in horizontal type cross flow cold flue channel Figure 8A: Pre cooling and pre cleaning device where the un-cleaned flue gas coming form source enter in to the pre-cooler while flowing parallel to the earth and the semi-cleaned or pre-cleaned and pre-cooled gas is emitting out in parallel flow to the Earth and then enter into the device of present Figure 8B: Pre cooling and pre cleaning device the un-cleaned flue gas coming form source enters in to the pre-cooler while flowing vertically from top towards the Earth and the semi-cleaned or pre-cleaned and pre-cooled gas is emitting out in downward flow towards the Earth and then enter into device of present invention. Figure 9: chimney arrangement for flaring the un-combusted part of the flue gas emitting out of the cleaning device DETAILED DESCRIPTION OF THE DRAWINGS Primary Cooling and Primary cleaning: As illustrated in figures 1 and 2 flue gas cleaning device of the present invention has been developed to segregate or to remove and collect the dust or particulate matter contained in the hot flue/ process gas stream (generating from a furnace or a kiln or some such combustion chamber or process gas source) by injecting or directing the hot dust laden flue gas stream by source duct of hot flue gas (W) to the duct connecting the flue gas source (A) to the hot dust laden flue gas distribution dome(B) at the top of the dust collector (flue gas cleaning device) in to the hot flue channel (I) in hot condition, through a narrowed down entrance port by a unique draft control mechanism (F) by utilizing and for maintaining, the positive pressure of the kiln or combustion chamber or furnace or the gas source; to facilitate or to achieve the best possible gas entrance velocity (in accordance to the available positive pressure available at the kiln/ furnace/ combustion chamber outlet) or to impart best possible differential kinetic energy/force which can be imparted in the dust or particulate matter for separation of dust or particulate matter from flue stream. Without affecting the requirement of the positive pressure at the source. The flue stream in the hot condition is entered in to a number of hot flue channels (I), having gradually widening passage or wider space towards the earth or bottom of the device and parallelly placed and separated with a common thermal conductive metallic sheet wall (K) of the cold flue channels (J), which are having narrower space at the bottom and wider space at the top; The hot flue gases are entered through narrowed entry (narrowing of the port is adjusted according to the available positive pressure of the kiln/ furnace/ combustion chamber, without affecting the combustion chemistry inside the kiln) and directed towards the gravity i.e. towards the earth or bottom at an appropriate angle or at the right angle; so that the velocity or differential kinetic energy achieved by the particulate matters or dust are either maintained or accelerated or enhanced towards the earth due to gravity for separation. The hot gases traveling down towards earth are separated with good thermally conductive material made of metallic sheet or plates (K) (with heat resistant property), forming parallel gas up flow path, which is termed herewith as cold flue channel (J) in which the cooled and cleaned flue gas flow upwards towards chimney (CC)(shown in figure 9) for exhaust into the atmosphere, during the course of upward movement the cooled and cleaned flue gases regain the thermal energy through heat conduction through the thermally conductive jacket wall (K) made of metallic plate/ sheet/ pipe material (which are parallely divided at certain intervals by slitting across horizontally and this gap is filled up and hermetically sealed with any suitable heat resistant thermally insulating material) and thus get heated up and in the course of up-flow as well as cool down the downward traveling un-cleaned hot flue gases in the hot flue channels (I). This way the thermal energy content in hot un-cleaned flue gases required to be removed for the cooling is taken away by the cooled clean flue gases and thus the cleaned cool gases attain sufficient thermal energy to create a good chimney draft for emitting out through chimney (CC) to the atmosphere, hot un-cleaned flue gases while traveling down and while getting cooled, lose their thermal energy content thus their volume gets reduced and viscosity gets reduced. The particulate / dust matter falling velocity gets enhanced velocity than the gaseous velocity, also the finely divided particulate get an opportunity to agglomerate or cluster to a larger cluster of the particulates, all these together results in better separation of dust or particulate matter buoyant in the flue stream. With this flue heat recuperation the temperature of the hot flue gas stream is attempted to brought down to the best possible minimum temperature. It is worked out that a hot stream of flue gases emitting at 900°C or below from sponge iron kiln or furnace or combustion chamber or any other such combustions sources, can be cooled down up to or below 200°C most preferably to below 100°C in this way, and about 80% and above dust particulate matter attain or gain settle able/ removable differential kinetic energy in this process. Up to this stage of cooling is referred to as primary cooling. Secondary cooling: In order to remove the dust from the dust laden stream or to further clean the gas through a cyclone or bag filter or ESP or wet scrubbing the gas requires further cooling. Thus the secondary cooling is done by indirect cooling through water bearing carrying tubes over which the primarily cooled flue stream is flown through water carrying tubes (L & M) placed across the hot flue channels (I) and cold flue channels (J) and the heat remaining in the primarily cooled gases are conducted out in the water flowing inside these tubes, from the hot flue channel (I) gases and partially transmitted back in to the cold flue channel (J) gases. The flue gas so cooled is further continued to flow towards bottom; (i) for further cooling of the gases through bundle of water cooling tubes (L & M) and water misting tubes (O) and; (ii) after reaching to the bottom most part of the hot flue channel, the gases emit out of the hot flue channel and here the dust or particulate matters get removed from the gas stream while the dust laden gas take a "U" turn or a return upward path from hot flue channel (I) to cold flue channel (J), at this point the dust particle fall out in the bottom dust trap hopper (S) with liquid seal ( R) having liquid (T)or without any liquid. The dust accumulated or slurry formed with the dust in the dust hopper by trapping dust is removed through slurry discharge pipe (V) provided with slurry discharge port valve (U). The un-cleaned flue gas is cooled between 70 to 140°C for the dust removal from this device or for further cleaning through bag filter or cyclone or wet scrubber. When cyclone or bag filter is used for the further cleaning then the gas is cooled between 90 to 170°C. But when the gas is cleaned through a wet scrubber wet water bath or water sprinkling then the temperature of the flue gas is brought down below 90°C, [to reduce the evaporation losses and to avoid the boiling of the water]. In case the secondary cleaning is not required then the temperature of the flue gases for cleaning through this device is sufficient even up to 200°C. This stage of cooling through water bearing tubes is defined as secondary cooling. Optionally the equipment is so devised that the flue gases after this level of cleaning require further secondary cleaning, by processing through some other secondary device(Z), such as ESP, Cyclone, Wet Scrubber, Ventury Scrubber, Bag Filter etc. located out side the body of this device then the flue gases at this point take "L" turn or side path and are withdrawn out through the side openings which are connected to secondary cleaning devices in series to an ID/FD Fan and after the secondary cleaning those cleaned gases are fed into the cold flue channel bottom through the side openings Secondary cleaning: The so far cleaned cooled flue gases are then drafted out with the help of an ID/FD fan from the bottom of the cold flue channel through an opening (O) and are passed through the secondary cleaning ESP or wet scrubber or ventury scrubber or cyclone or bag filter and then finally cleaned flue gas is forced back in to flue gas recuperation chamber, called "cold flue channel" through an opening (N) for recovery of the heat contained in the un-cleaned hot flue gases. This way the un-cleaned hot flue gases (traveling down in the hot flue channel) get cooled as well as finally get cleaned; and cooled cleaned flue gases get hot for emission from the chimney. During the secondary cleaning process the cold flue channel seal (P) provided at the bottom of the channel is kept closed. When the secondary cleaning is not required then the cold flue channel seal (P) is kept open and the cleaned and cooled flue gases emitting out of the hot flue channel (I) take a "U" turn and enter in to the bottom of the cold flue channel (J) and flow upwards to get heated up by withdrawing the heat from the hot gases flowing down in the hot flue channel, and this way the cleaned gases emit out of cold flue channel top directly to the chimney or through the pre-cooling and pre-cleaning device to chimney (CC)) dust Trapping: The dust falling out of the hot flue channel (I) are trapped into a vessel known as dust collection hopper/trap (S) placed below the hot and cold flue channel (I & J), which can be kept empty or filled with water or liquid, placed below the hot & cold flue channels (I and J) as shown in figure 1 & 2. The water / liquid trap placed below the hot and cold channel (I & J) can be dry or can have a variable water/ liquid level (T). When the dust particles are coarser then the liquid or water is not required in the dust trap. When the dust particles are fine then the liquid or water filling in the dust trap bath is required for dust trapping. When the path resistance or the pressure drop in the hot and cold flue channel (I and J) is lower than the draft created by chimney draft then the water/ liquid level is so maintained up to a level that a clear space is available for the cooled down hot flue gases to comfortable pass through from hot channel (I) to cold channel (J) by taking an upward "U" turn and the gas seal (P) is kept open. But when it is required that the gases so cleaned need to be further cleaned through a Cyclone or Bag Filter or Wet scrubbing then the cold flue channel passage is sealed by closing the gas Sealing valve (P) placed in the cold flue channel (J), lower portion. In this situation the flue gases from the cold flue channel bottom are withdrawn or sucked by a Blower through the suction ports opening (Q) placed below the water cooling pipes or water cooling vessels and such withdrawn gases are forced through the ESP or ventury scrubber cyclone or bag filter or wet scrubber or any such secondary cleaning devices. After this secondary cleaning the cleaned cool flue gases are released into the bottom of cold flue channels (J) through the flue release port opening (N) provided at the bottom of cold flue channel, placed above the gas sealing valve (P). Then the gases flow upwards and emit out of the device through duct (G), which leads these cleaned gases directly to the chimney or through a pre-cooling device to the chimney. Flaring of the un-combusted gases: The clean cool flue gases attain sufficient temperature while traveling upward and during reheating, therefore the un-combusted gases like CO and or H2 and such combustible gases become flammable. As shown in figure 9, to inflamate / Flare these gases required quantity of air is forced into the chimney (CC) with the help of a Blower (BB) and released at the upper portion of chimney (CC) via combustion air nozzle (AA). Thus the un-combusted gases get combusted and flue gases become further hot and gain better draft due to additional heat generation due to combustion of these un-combusted gases. This additional blowing of required combustion Air, also propels the gases upwards for better emission out of chimney stack. The use of the Jet Nozzle (AA) at the combustion Air Release point further help to create an additional draft. Although the above invention is presented in a particular form and shape but the same can be fabricated in a number of ways without deviating from the main spirit of the inventions. The following changes can be done keeping the other features as above: Figures 3 A and 3B illustrate the hot flue channels as inverted "V" shape ie is broadening from top to bottom. Figure 3B illustrates the whole device where the hot flue channel in inverted "V" shape and other embodiments and their relation is shown.(Fig-3).Figure 4 illustrates the hot flue channels as normal "V" shape i.e narrowing from top to bottom while the hot flue channels as illustrated in figure 5A. Figures 6a and B illustrate the hot flue channels with the upper half "V" shape and lower half inverted "V" shape as in figure . The other features being similar as mentioned above. The hot flue channels may also be of rectangular or circular or conical shape or in any other shape. Similarly the cold flue channels can be provided variously. As illustrated in figures 1 and 6A they may be vertically arranged with as reverse flow or horizontally arranged with cross flow as demonstrated in Figures-3(A), 3(B),4,5(A), 5(B) 6(B), 7. The other features being similar as mentioned above. There may be further modifications in other known manners of flow of cooling gas or liquid to extract the heat out of the hot flue channels. The dust cleaned gas emerging out of the hot flue channels can be collected through a single port from either side or from two or plural port from various sides and processed through an outside cleaning device and forced into the cold flue channels for re-heating or let out directly to the chimney. Also the cleaned flue gas while being collected as defined above can be washed through water or some other liquid solution shower to further arrest the particulate matters or scrub the gases, during the withdrawal flow of such gases. It is also not essential to have a dust collection hopper as shown in the drawing, the hopper can also be fabricated in a number of ways such as circular, hexagonal, octagonal, triangular etc. in accordance to the main body. Thus the flue gas cleaning process involves the following Stages: a] Utilization of positive Pressure or Draft to be maintained in the Kiln for Injection/ Direction of the hot un-cleaned flue gases in to the cooling Recuperation chamber referred to as hot flue channel (I) through a "Narrowed Entry Port" to achieve the desired dust separation velocity/ or to Gain the best possible gas velocity from the available positive pressure, without affecting the Kiln/ Furnace or Combustion Chamber Environment. b] Primary Cooling of the hot flue gases in the Recuperative hot flue channels (I) through the cleaned cooled flue gases moving upward in cold flue channel (J) for emission to atmosphere through chimney c] Secondary cooling of un-cleaned hot flue gases through indirect contact of water with water carrying Tubes or Vessels up to steaming temperature in water pipes tubes, vessels (M) further cooling with water evaporating or cross water flowing type of water tubes(L), pipes, vessels and further cooling by water mists by releasing the mist through water misting pipes (O) and further contact of gases with water surface contact with water surface (T) placed in dust hopper (S). d] Arresting the dust falling out of flue stream into an liquid bath (T) or water bath or an Oil bath or water bath having floating Oil Film on it by placing this in Hopper (S) below the hot flue gas channel. e] If required Directing or drafting out the Primary cleaned flue gases into a Cyclone / Bag Filter/ water Scrubber/ ESP etc.(Secondary conventional cleaning devices) and then letting in the finally cleaned cooled gases into the cold flue channel (J) for gradually getting heated up for final emission through chimney (CC). f] It required Creating a mechanical draft with an ID/FD type motorized or mechanically driven Blower to compensate the Head loss caused during the Primary and Secondary cleaning. g] Directing the cleaned and cooled flue gases in to the recuperative heating channel called cold flue channels for upward movement for heat Gain for emission through chimney. (In case the gases being cleaned or cooled are required to be used in some other process and are not to be let out into the atmosphere or not required to be passed through the cold flue channel then the other cooling gases or liquid medium from outside can be deployed as Explained elsewhere in this embodiment] h] The so cleaned flue gases may contain some unburnt CO or Hydro Carbon or H2 thus a flaring provision is provided at just little bellow the top of the chimney by either forcing the combustion Air through a FD Fan (BB) and releasing the combustion air through a combustion air nozzle (AA) located at the upper segment of chimney (CC) (or by creating a self Air suction port at this level of chimney), which helps to combust the un-combusted part of reheated cleaned flue gases which further increases the temperature of the flue gases which results into better chimney draft. i] Pre-cleaning and Pre-cooling: In case of temperature of the process gas is very high i.e. above 900°C and the dust load also is too high i.e. above 50 gm/NM3. Then in such case a pre-cooling and pre-cleaning device can be installed before this device to bring the temperature of the hot flue gases to below 900°C and the dust load to below 60 gm/NM3. The pre-cooling device can be made in any known method. However the reheated cleaning flue gases or process gases coming out the above device can be routed through this pre-cooling system to cool the very hot dust laden gases, as well as to add heat into the cleaned cooled flue gases or process gas, for emitting through chimney or for using in any process. The Pre-cooling and Pre-cleaning device is placed in series between the hot gas source and the cleaning device for Pre-cooling and Pre-cleaning of the hot gases and it can also be put in series to the flue gas cleaning device and the chimney for further heating of cleaned Reheated flue gases. DESCRIPTION OF VARIOUS COMPONENTS OF THE PREFERRED EMBODIMENT OF THE DEVICE: a) hot dust Laden flue gas duct Connecting the flue gas source to the gas cleaning device. It is a simple duct made of Mild Steel Plates lined with some Refractory castables capable to withstand High temperature and connects the source of combustion flue gases or the outlet of the pre-cooling and pre-cleaning device to the top of the flue gas Distribution Hood (B) of the gas cleaning device. b) hot dust Laden flue gas Distribution Dome / Hood. The Dome/Hood also is made of Mild Steel Plates lined with refractory castables and it connects on one side to the Incoming flue gas duct (A) and distributes the gases through the Draft Control Hood (C). c) Draft Control Hood. This also is made of Mild Steel Plates lined with Refractory castables and accommodates throttle control assembly (E) and throttle control Body (F), which is mounted on the shaft and can be raised up and brought down through a screw down mechanism installed outside the draft control hood. d) Screw Down Mechanism for Draft/ Throttle Control and for gas velocity Acceleration. This mechanism is made of a set of screw down mechanism, which holds the throttle control body shaft, it is used for raising or lowering the throttle control body for increasing or decreasing the hot flue channel passage opening. e) Shaft for holding the opening and closing part or component for the hot flue gas Entrance Port, called Throttle Control Body holding shaft. On this shaft a number of throttle control Body (F) are fixed above the hot flue channel Inlet Point. This shaft is made of steel or stainless steel or can be a heat Resistant Steel. f) Throttle Control Body. These are lens shaped body made of stainless steel or heat resistant steel or Mild Steel, Plates or Solid Mass. The lens shape of this body helps to increase and decrease the flue passage at the Input port of the hot flue channel, and facilitate the Smooth Flow of gases. g) Clean flue gas discharge/ emission ducts : These duct are made of Mild Steel or Stainless Steel Plates and have got refractory lining in the inside and these carry the cleaned and reheated flue gases from cleaning device cold flue channel outlet located at the top of cold flue channel to chimney or can be passed through pre-cooling device to chimney. They emit out the cleaned flue gases from the Top of the cold flue channel, from the Side of the flue gas cleaning device. h) dust Collection device Casing or body : The dust collection device casing is fabricated out of Mild Steel Plates this can be lined with castables or can be kept without lining too. i) hot flue channel: hot flue channel are formed by the metallic plate separation wall, these channels are narrower at the top and wider at the bottom, and this can be vice- versa also or can be parallel path also, these are placed vertical. The hot flue enters from the Top and cooled flue gas discharges from the bottom, as shown in the fig-1. The channel wall are horizontally discontinued by horizontal slitting and Hermitically sealing the walls through an insulating gaskete called Thermal Break (Y) at certain horizontal intervals. j) cold flue channel: These cold flue channels are also formed due to the separation walls (K) made of metallic plates. The cold flue channel run parallel to the hot flue channel and these are placed vertical. The cold cleaned flue gases enter from the bottom and emits from the Top. The channel wall are horizontally discontinued through an insulating gaskete called, Thermal Break (Y) at certain intervals. k) hot/ cold flue channel separation/ formation Metallic Sheet Wall: These walls are made of conductive metallic plates, which can be stainless steel of heat Resistant Steel or Mild Steel or otherwise any type of metallic plate with a Good Thermal conductivity able to withstand the Thermal Endurance. The channel wall are horizontally discontinued by horizontal slitting and Hermitically sealing the walls through a thermal insulating gaskete called, Thermal Break (Y) at certain horizontal intervals. 1) Steaming water Tube/ Pipe/ Vessel Bundles : These pipes are made out of Boiler Grade Tubes or Pipes or can be stainless steel pipe or Good Thermal conducting Metal Pipes or Tubes or Vessels. These are placed in the Top Layer of the water Tube bundles. The hot water coming from the lower positioned Tubes enter at this level and emit out as Steam. m) Cooling water Carrying Bundles : The cooling water tubes can also be made out of Boiler Grade/ Tubes or Pipes and are placed below the steaming pipes or tubes, across the hot and cold flue channels. Tube Metal should have good thermal conductivity. n) Secondarily cleaned and cold flue gas input port (connected to the outlet of secondary cleaning mechanism): This is an opening created at the bottom of the cold flue channel above the gas sealing valve mechanism (P). The cleaned cold flue gas is fed to the cold flue channel, when it is withdrawn for the secondary cleaning by and ID/FD Fan. For cleaning through a secondary gas cleaning device. o) water Mist distribution Pipes or Nozzles : These are metallic pipes carrying small- small fine jet nozzles to create water mist and are placed just at the bottom of the hot flue channel slightly above the flue gas out-flow level as indicated in Fig-1. The pipe is connected to a water pump, which pumps the regulated quantity of water to create water mist in the channel bottom. p) Cold flue channel sealing (or opening/ closing) valve mechanism : This is made out of stainless steel or mild steel or any other suitable metal, it is used for closing and opening the bottom of the cold flue channel. When the semi-cleaned flue gas is required to be cleaned through a secondary system then the seal closes the channel at this level. And the gas is withdrawn from the outlet port created just below this seal. q) Cooled and semi cleaned flue gas outlet port connected to secondary cleaning mechanism : This is an opening provided just below the sealing valve mechanism in the cold flue channel. The semi cleaned and cold flue gas is withdrawn from this port with the help of suitable ID/FD Fan for further cleaning in a secondary cleaning device. r) Liquid Seal for dust cleaning device and dust Collection Hopper liquid sealing arrangement: The bottom portion of the gas cleaning device casing is extended to get immersed in a liquid Sealing channel, which is formed at the upper portion of the dust Collection Hopper, which creates a water or liquid sealing channel in which the casing wall plate is immersed. s) Dust Collection Hopper/ dust Trap: The dust Collection Hopper is made out of the steel plates and can be conical or any other suitable shape, this can be filled with water or liquid oil or a film of oil on water or can even be kept empty without any liquid as per the requirement and convenience. It is used for collection of dust Falling out of the cleaning device. t) Dust Collection Hopper liquid (water or oil or water with oil) : The dust collection hopper can be filled with a liquid which can be water or oil or oil film floating on the water. u) Slurry discharge port valve : A valve is provided at the bottom of the Hopper for discharging of the dust Slurry formed with the liquid used or even when the Hopper is empty without any liquid. Then the Dry dust is discharged. v) Slurry discharge pipe : A Steel or Metal Pipe is provided below the valve to facilitate smooth flow and guided flow of slurry or dust to be discharged when the valve is opened up. w) Source duct of hot flue gas : The Source of flue gas or gas can be any thing such as a Rotary Kiln/ Combustion Chamber/ Furnace/ Boiler etc. A duct made of Steel and Lined with heat insulating material on the inner side is provided to carry the hot uncleaned flue gas to dust cleaning device. x) Thermal Conductor Studs/Fins and restrengthing Bars : These are Plates, Strips, Bars and Rods Round or Oval or any other shape made of metallic material having Good thermal conductivity and able to withstand the heat Endurance. These are placed on the hot and cold flue channel Metallic Walls in continuation or in discontinuation, the purpose of installing these studs is to improve the Thermal conductivity as well as provide better reinforcement to the flue channel walls. The Gap and distance between the fins or studs can be kept according to the requirement. If the Thermal heat Transfer Quantum is less, then this may be avoided too. This is an optional feature to the device. y) Thermal Breaks : These are thermally insulating material placed horizontally in the hot/ cold flue channel wall horizontal split Gaps, at certain interspaces to discontinue the Thermal conductivity on the walls from the Top to bottom of the channel and to avoid the creation of isothermal condition. z) Secondary cleaning Conventional System inclusive of ID/FD Fan, ESP/ Cyclone/ Wet Scrubber/ Ventury Scrubber etc : These are the Known devices, which can be used in addition to the proposed device to additionally clean the flue gases emitting out of the device after the Primary cleaning as demonstrated in figure 8A and 8B. In Fig 8(A) the un-cleaned flue gas coming form source is entering in to the pre- cooler while flowing parallel to the earth and the semi-cleaned or pre-cleaned and pre-cooled gas is emitting out in parallel flow to the Earth and then entering into the device of present invention. Also in this arrangement the cleaned flue gases emitting from the into device of present invention is entering in to the pre-cleaning cross flow path from the bottom of the pre-cleaner and pre-cooler and emitting out from the top and getting connected to chimney. In Fig 8(B) the un-cleaned flue gas coming form source is entering in to the pre- cooler while flowing vertically from top towards the Earth and the semi-cleaned or pre-cleaned and pre-cooled gas is emitting out in downward flow towards the Earth and then entering into flue gas cleaning system (our device under patent application). Also in this arrangement the cleaned flue gases emitting from the into FLUE GAS cleaning system (our device under patent application) is entering into the pre-cleaning cross flow path in parallel to the Earth from the side of the pre-cleaner and pre-cooler and after re-heating is emitting out and connected to the chimney. These are two different way of assembling the pre-cleaner and pre-cooler and other combinations can also be device. AA. Combustion Air Nozzle: This air nozzle is provided in the chimney for post combustion of un-combusted flue gases remaining in the flue stream (As shown in Fig-9). BB. Combustion Air FD Fan: This combustion air FD Fan is provided near the chimney for blowing the post combustion air in to the combustion air nozzle provided in the chimney (As shown in Fig-9). CC. Chimney. The duct is connected to the chimney. The chimney can be of any type as is usually built in general practice. DD. Cleaned flue gas duct From - flue gas cleaning device.: This is a Metallic duct having the refractory lining to minimize the heat loss from the cleaned and reheated flue gases. Best mode of working of the invention: The working of the process according to the present invention is described below with respect to preferred embodiment which should not be regarded as limiting the present process. The device is attached to a sponge iron rotary kiln through which waste hot gases are emitting out at 750° to 900° C, with dust load of above 30 gm per NM3 and with about 12% of unburnt CO. Then this device is fitted to the exhaust port of the Rotary Kiln, through a duct as shown in the figure and hot gases are speeded up with the draft control mechanism and such cleaned and cooled gas is then reheated in the cold flue gases and collected at the top of the devices, which is then again connected to the chimney for emission. The un-combusted gases get combusted due to the reheating of the gases, which attain the combustion temperature for which post combustion Air or Secondary Air can be forced into chimney from an independent blower or self induced draft itself can flare up the gas. The dust is collected from the bottom hopper placed below this device. The device developed for removal of dust from hot dust laden flue gases functions in the following stages. 1) Draft control with acceleration of dust laden flue gases acceleration of hot flue gases velocity is enhanced by using the positive pressure available from the hot flue gas source as well as maintaining the positive pressure in the kiln or combustion chambers etc. by using an unique draft control device. 2) Cooling of the hot dust flue gases with Exchange of heat or transfer of heat into the cleaned dust free cooled flue gases through an unique heat Transfer mechanism created in the device called hot flue channels and cold flue channel which are placed adjacent and divided with a common metallic wall having good heat exchange capacity or good thermal conductivity, whereas these walls have the horizontal thermal breaks at certain interspaces on the horizontal plain. 3) Primary Removal of dust form the hot dust Laden flue gas Stream: The dust particle get greater acceleration than the flue gas velocity while traveling down or towards the Earth and attain greater Earth ward traveling speed due to the decreased drag force created by reduced viscosity, as well as reduced gas velocity (caused due to cooling of the gases as well as increase in the volumetric space at the downwards levels) as well as due to clustering of Fine dust Particles, and dust Particles fall out of the flue gas stream at the bottom of the channel, when the flue gas Stream take an upward turn ("U" turn) to enter from the hot flue channel to cold flue channel/ or take a side turn ("L" turn) when removed for the Secondary cleaning. At this Point most of the particles continue to travel downwards towards earth and leave or get separated from the flue gas Path and fall down into the bottom placed dust Trap. 4) Dust Trapping: The dust which are removed from the hot flue gas Stream at the upward return ("U" Turn) or side Turn ("L" turn) point while entering to the cold flue channel are collected in this dust Trap, this dust Trap can be kept dry when the dust particles are course or can be filled with some liquid or Oil such as plain water or saline water or salt dissolved water or mineral oil or vegetable oil. When the liquid is used in the trap then the level of the liquid is so maintained that there is enough space remaining in between the liquid level and channel separation wall to allow the free passage to the downward gases in hot flue channel to take U turn and enter in to the cold flue channel. 5) Cleaned gas Emission to the atmosphere: The cleaned and cooled gases start traveling upward and gain temperature, while traveling upward by extracting the heat from the hot flue channel by conduction through the separating metallic wall. The hot gases move upwards because of the increase in temperature and chimney draft created due to the heat gained in the cleaned cooled flue gases. The path resistance is maintained due to the gradually widening upward path and increasing volume of the cold flue channel, in spite of the increasing volume of the reheating up cold flue gases;. The above mechanism is simple mechanism to remove the dust from hot dust Laden flue gases without use of any extra mechanical power required for the Handling of the gases. Also the system requires very little water for cooling and is thus self sustaining. 6) Secondary Cooling: For further improvement in the cooling efficiency of the gases as well as cleaning efficiency of the gases following devices can be added in the bottom ¼ portion of hot flue channel, a bundle of Pipes or Tubes or Vessels carrying cooling water or coolant or cooling oil can be placed to remove the remaining heat in the already cooled dust Laden flue gases. These pipes are placed across the hot and cold flue channel. When water is used in these cooling pipes then the Top Layers of these pipes are exposed to the higher temperature of hot flue gases, thus this may cause steaming of the water, thus the steam generated out of the these pipes is let out into the atmosphere. 7) Tertiary cooling: If the gases require further cooling than the above cooled temperature level then a water mist release pipe is placed at the level below the above mentioned liquid bearing cooling pipes in the hot flue channel bottom portion. The mist released from this pipe takes away lot of heat due to phase change of water or due to evaporation in Dry flue gases. Which further facilitates the removal of dust, as also the dust particle gain some moisture and become heavier for separation. The flue gases can get further cooled when they partially get in contact with the water surface at the dust trap, while they take a "U" Turn or "L" Turn from the hot flue channel to cold flue channel. 8) Additional cleaning through the conventional devices: However the System can be added with the device for the secondary cleaning by attaching the conventional dust cleaning equipments such as Cyclone, dust Filter, Bag Filters, Venture Scrubber or ESP etc., along with an ID/FD fan to provide required power to handle the gases. Whenever the property of flue dust in process gases or flue gases, is such that the desired level of dust could not be removed or totally cleaned from the above devices and yet further dust removal is essential, then the additional cleaning of Primarily cleaned and cooled flue gases can be performed by withdrawing the cleaned cool gases with the help of a ID/FD fan from the bottom of cold flue channel and passing those gases through the conventional equipments like Cyclone, Wet Scrubber or ESP or Bag Filter etc. After this is cleaned then the finally cleaned gases are fed back into the bottom of the cold flue channel slightly above withdrawal port/ gas seal arrangement. In such cases the bottom of the cold flue channel is provided with a gas Flow locking arrangement or gas Seal to separate the withdrawal port and Release port and to avoid the remixing or return of finally cleaned gases to the withdrawal port and to allow the clear passage for the finally cleaned flue gases to move upwardly for emission through the chimney. To affect a better heat transfer through the separation walls or metallic conduction walls, the walls can be provided with the cross metallic studs/fins or cross wires or cross metallic rods or cross metallic pipes made of good thermally conductive metal. In such cases where the heat Transfer requirement can be met by simple ordinary wall plates then these are not provided. Thus the device of present invention scores over known gas cleaning system as under: i. In most of the known flue gas cleaning device the temperature profile is the same throughout the device where as in the present device there is tremendous temperature gradient. ii. In most of the known flue gas cleaning devices the viscosity of the gas, remains the same, whereas in the present device and process the viscosity of the gas changes substantially. iii. In most of the known flue gas cleaning devices the drag force acting against the particulate matter remains the same, whereas in the present process and device it varies substantially within the device. iv. In case of the known cyclonic type separators the cleaning or separation of the dust is affected by creating the different kinetic energy between dust and flue gases by enhancing the kinetic energy in the dust particulate matter, whereas in the present process and device it is also based on reducing the kinetic energy imparted in the flue gases. Thus increasing the gap between the kinetic energy level of gas and particulate matter. v. In case of ESP the dust is trapped due to electrostatic charge and in case of wet scrubber due to hygroscopic charge, whereas in the present process and device there is no electrostatic charge, even hygroscopic charge is very little, not as much as compared to the wet scrubbing. vi. In most of the presently known process cooling and cleaning is done separately, but in the present device cooling and cleaning is done simultaneously. vii. In none of the known device the flue gas is reheated, whereas in the present device the flue gas is reheated. Area of the application: This system or device is proposed to be used for cleaning of the hot dust Laden flue gases emitting out from any combustion sources or incineration source or Thermal Reduction Source such as Sponge Iron Rotary Kiln, Blast Furnaces, Billet Reheating Furnaces, Cement Plant Rotary Kiln, Cement Plant Cooler Grate Exhaust, Power Plant Boiler, Furnace, Forging Furnace, Cupola furnace, Vertical Shaft Kilns or Furnace, Glass Furnaces or any other heating or melting furnaces. The device can be used independently or can be put in series to the existing cleaning devices as Cyclone, ESP, Bag filter, Ventury Scrubber etc. The device can also be used only for the purpose of cooling of hot flue gases as well as for reheating of these cooled flue gases for any other applications independently or in conjunction with any other known device. The device can also be used for cleaning of any process gas. In such case the process gas is obtained from the process vessel or source and after dust cleaning gas scrubbing, cooling, reheating or without reheating is sent to the process destination. This device can also be used for gas scrubbing or gas removal by spraying the suitable absorbents through the misting pipes. The device is required to be connected to the outlet side of the above Equipment, through a preferably a refractory lined duct, into the flue gas input duct of the device, and the out put or exhaust side of the device is required to be connected preferably through a refractory lined duct to the chimney. I claim: 1. A cleaning device for hot dust laden flue/process gases comprising: i) means for receiving hot flue gas; ii) at least one vertical hollow gas flow path or channel for the hot dust laden flue gas with inlet at top and outlet at bottom ; iii) at least one hollow gas flow path or channel for the cooled cleaned flue gas with inlet at bottom and outlet at top arranged adjacent to the said flow path or channel for hot flue gas; iv) the adjacent walls of the said channels being made of thermally conducting material with or without intervening non conducting zones; v) means for receiving dust placed below the said channels; vi) means for emission of cleaned flue gas. 2. The device as claimed in claim 1 wherein the vertical hollow gas flow paths or channels for the hot dust laden flue gas have various shapes selected from broadening from top to bottom, narrowing from top to bottom, combination of both, parallel arrangement and the like. 3. The device as claimed in any preceding claims wherein the hollow gas flow paths or channels for the cold flue gas are selectively horizontally or vertically arranged with selective cross flow or reverse flow of gases. 4. The device as claimed in any preceding claim wherein the adjacent walls between said channels for hot and cold flue gas are provided with corrugated surface, finned surface or corrugated finned surface or rough surface and the like to facilitate better heat transfer. 5. The device as claimed in any preceding claim wherein the adjacent walls between said channels for hot and cold flue gas are provided with intermittent thermally non-conducting insulating material and thermally stable insulating materials, from top to bottom. 6. The device as claimed in any preceding claim wherein the means for receiving flue gas comprise duct from source of combustion flue gases or the outlet of the pre-cooling and pre-cleaning device and receiving hood. 7. The device as claimed in any preceding claim wherein the said hood comprise throttle control assembly and throttle control body, which is mounted at inlet of vertical hollow gas flow paths or channels for hot flue gas and is adapted to be raised up and brought down through screw down mechanism installed outside the draft control hood. 8. The device as claimed in any preceding claim wherein the throttle control body comprise lens shaped body made selectively from stainless steel, heat resistant steel, mild steel, plates or solid mass adapted to increase and decrease the flue passage at the input of the hot flue channel and facilitate the smooth flow of gases. 9. The device as claimed in any preceding claim optionally provided with draft control mechanism at the entrance point of the each hot flue channel for narrowing down the entrance orifice area comprising a suitable port narrowing mechanism, or arrangement 10. The device as claimed in any preceding claim wherein the channels for hot flue gas and cleaned cold flue gas along with the controlled input points for the cold flue channel are provided in a housing which is in operative connection with the said hood and dust and the means for collecting dust. 11. The device as claimed in any preceding claim optionally provided with means for secondary cooling the hot flue gases traveling down in the said hot flue channel comprising selectively water tube, pipe, vessel bundles and water mist distribution pipes or nozzles and placed near the exit of the hot flue gas and entry of the cold flue gas channels. 12. The device as claimed in any preceding claim wherein means for emission of cleaned flue gas comprise flue gas discharge or emission ducts adapted to carry the cleaned flue gases from cold flue channel outlet located at the top of cold flue channel to chimney to outside. 13. The device as claimed in any preceding claim optionally provided with means for withdrawing cleaned gas for secondary cleaning comprising sealing valve mechanism for closing and opening the bottom of the cold flue channel. 14. The device as claimed in any preceding claim wherein means for receiving dust comprise dust collection hopper which is in sealed communication with the flue gas channels at the bottom on one side and in sealed communication to the exit of the cooled gases on the other-side and provided with valve which control exit of the dry dust or slurry containing dust to the attached discharge pipe, 15. The device as claimed in claim 13 wherein the said dust collection hopper is with or without liquid selected from water, liquid oil or a film of oil on water. 16. The device as claimed in any preceding claim wherein the adjacent walls of the hot and cold flue gas channels are optionally provided with plates, strips, bars and rods of material having good thermal conductivity and able to withstand the heat. 17. The device as claimed in any preceding claim optionally provided with a pre- cooling-cum pre-cleaning arrangement as well as secondary cleaning arrangement by means of conventional devices wherein said pre-cooling and pre-cleaning device is placed in series between the hot gas source and the cleaning device for pre-cooling and pre-cleaning of the hot gases and optionally placed in series to the flue gas cleaning device and the chimney for further heating of cleaned flue gases. 18. The device as claimed in any preceding claim optionally comprising provision for flaring inflammable gases in the cleaned flue gas comprising blower, air nozzle provided in the chimney through which the cleaned gas is released. 19. A process for cleaning hot dust laden flue/process gases comprising: a. receiving hot dust laden flue gas by means for receiving hot flue gas and transferring to vertical hollow gas flow path or channel for hot flue gas; b. downward passing the hot dust laden flue gas through said channel by inlet at top and outlet at the bottom; c. upward passing of the cleaned gas after removal of dust and taking 'u" turn from the outlet of the hot flue channel to the inlet of the channel for the cooled cleaned flue gas with inlet at bottom and outlet at top arranged adjacent to the said flow path or channel for hot flue gas; d. simultaneous dissipation of heat through the adjacent walls of the said channels being made of thermally conducting material with or without intervening non conducting zones causing decrease in viscosity of the dust laden gases from top to bottom; e. separation of dust and agglomerated particles from the hot flue gas by gravity and arresting the same in the means placed below the said channels; f. directing the cleaned flue gases from the cold flue channels for emission through means for emission of cleaned flue gas. 20. A process as claimed in claim 19 wherein the velocity of the hot flue gas passing through the hot flue channels is increased on passing from top to bottom to achieve the desired dust separation velocity. 21. A process as claimed in any of claims 19 to 20 wherein the hot flue gases in the hot flue channels is primarily cooled by the cleaned cooled flue gases moving upward in cold flue channel for emission to atmosphere through chimney. 22. A process as claimed in any of claims 19 to 21 wherein the hot flue gases in the hot flue channels is optionally secondarily cooled by indirect contact of water with water carrying tubes or vessels up to steaming temperature in water pipes tubes, vessels further cooling with, water evaporating or cross water flowing type of water tubes, pipes, vessels and further cooling by water mists by releasing the mist through water misting pipes and further contact of gases with water surface contact with water surface placed in the means for receiving dust comprising dust hopper and adapted to further decrease the viscosity of the flue gas and agglomeration of the dust particles. 23. A process as claimed in any of claims 19 to 22 wherein the cleaned flue gas is reheated as it passes from bottom to the top of the channel 24. A process as claimed in any of claims 19 to 23 wherein the dust particles attain greater acceleration than the flue gas velocity while traveling down and further attain greater earth ward traveling speed due to the decreased drag force created by reduced viscosity and reduced gas velocity caused due to cooling of the gases along with increase in the volumetric space at the downwards levels and dust particles fall out of the flue gas stream at the bottom of the channel, when the flue gas stream take an upward turn ("U" turn) to enter from the hot flue channel to cold flue channel. 25. A process as claimed in any of claims 19 to 24 wherein the dust falling out of hot flue gas is arrested into liquid bath or water bath or an oil bath or water bath having floating oil film on it by placing this in said hopper below the hot flue gas channel. 26. A process as claimed in any of claims 19 to 25 wherein the vapour moisture available in stream is deposited on the dust particulates due to simultaneous cooling to form agglomerates for better removal and minimizing formation of gaseous acid. 27. A process as claimed in any of claims 19 to 26 wherein the primary cleaned flue gases are optionally secondarily cleaned by passing through conventional cleaning devices selected from cyclone, bag filter, water scrubber, ESP and then letting in the finally cleaned cooled gases into the cold flue channel for gradually getting heated up for final emission through chimney. 28. A process as claimed in any of claims 19 to 27 wherein optionally a mechanical draft is created with an ID/FD type motorized or mechanically driven blower to compensate the heat loss caused during the primary and secondary cleaning. 29. A process as claimed in any of claims 19 to 28 optionally combusting the unburnt CO or hydro carbon or H2 when present in the cleaned flue at just little below the top of the chimney by either forcing the combustion air through a FD Fan and releasing the combustion air through a combustion air nozzle located at the upper segment of chimney or by creating a self air suction port at this level of chimney to combust the un- combusted part of reheated cleaned flue gases, which further increases the temperature of the flue gases which results into better chimney draft. 30. A process as claimed in any of claims 19 to 29 optionally comprising pre-cleaning and pre-cooling in case of temperature of the process/flue gas is above 900°C and the dust load also is above 50 gm/NM3 by conventional devices. 31. A cleaning device and process for hot dust laden flue/process gases as described herein and illustrated with reference to accompanying drawings Title : DEVICE AND PROCESS FOR CLEANING HOT FLUE GASES ABSTRACT A cleaning device for hot dust laden flue/process gases comprising means for receiving hot flue gas; at least one vertical hollow gas flow path or channel for the hot dust laden flue gas with inlet at top and outlet at bottom ; at least one hollow gas flow path or channel for the cooled cleaned flue gas with inlet at bottom and outlet at top arranged adjacent to the said flow path or channel for hot flue gas; the adjacent walls of the said channels being made of thermally conducting material with or without intervening non conducting zones; means for receiving dust placed below the said channels; means for emission of cleaned flue gas. A process for such cleaning comprising receiving hot dust laden flue gas by means for receiving hot flue gas and transferring to vertical hollow gas flow path or channel for hot flue gas ; downward passing the hot dust laden flue gas through said channel by inlet at top and outlet at the bottom; upward passing of the cleaned gas after removal of dust and taking 'u" turn from the outlet of the hot flue channel to the inlet of the channel for the cooled cleaned flue gas with inlet at bottom and outlet at top arranged adjacent to the said flow path or channel for hot flue gas; simultaneous dissipation of heat through the adjacent walls of the said channels being made of thermally conducting material with or without intervening non conducting zones causing decrease in viscosity of the dust laden gases from top to bottom; separation of dust and agglomerated particles from the hot flue gas by gravity and arresting the same in the means placed below the said channels; directing the cleaned flue gases from the cold flue channels for emission through means for emission of cleaned flue gas. |
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74-KOL-2004-(05-09-2011)-ABSTRACT.pdf
74-KOL-2004-(05-09-2011)-AMANDED CLAIMS.pdf
74-KOL-2004-(05-09-2011)-DESCRIPTION (COMPLETE).pdf
74-KOL-2004-(05-09-2011)-DRAWINGS.pdf
74-KOL-2004-(05-09-2011)-EXAMINATION REPORT REPLY RECIEVED.PDF
74-KOL-2004-(05-09-2011)-FORM 1.pdf
74-KOL-2004-(05-09-2011)-FORM 2.pdf
74-KOL-2004-(05-09-2011)-OTHERS.pdf
74-KOL-2004-(24-01-2012)-CORRESPONDENCE.pdf
74-KOL-2004-CORRESPONDENCE 1.1.pdf
74-KOL-2004-CORRESPONDENCE 1.5.pdf
74-KOL-2004-CORRESPONDENCE-1.2.pdf
74-KOL-2004-CORRESPONDENCE.1.3.pdf
74-KOL-2004-CORRESPONDENCE.1.4.pdf
74-kol-2004-correspondence.pdf
74-kol-2004-description (complete).pdf
74-KOL-2004-EXAMINATION REPORT.pdf
74-KOL-2004-GRANTED-ABSTRACT.pdf
74-KOL-2004-GRANTED-CLAIMS.pdf
74-KOL-2004-GRANTED-DESCRIPTION (COMPLETE).pdf
74-KOL-2004-GRANTED-DRAWINGS.pdf
74-KOL-2004-GRANTED-FORM 1.pdf
74-KOL-2004-GRANTED-FORM 2.pdf
74-KOL-2004-GRANTED-SPECIFICATION.pdf
74-KOL-2004-REPLY TO EXAMINATION REPORT.pdf
Patent Number | 255439 | ||||||||
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Indian Patent Application Number | 74/KOL/2004 | ||||||||
PG Journal Number | 09/2013 | ||||||||
Publication Date | 01-Mar-2013 | ||||||||
Grant Date | 22-Feb-2013 | ||||||||
Date of Filing | 26-Feb-2004 | ||||||||
Name of Patentee | SINGHANIA, LALIT KUMAR | ||||||||
Applicant Address | 205, SAMTA COLONY, RAIPUR, CHHATTISGARH, PIN | ||||||||
Inventors:
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PCT International Classification Number | B01D 53/34 | ||||||||
PCT International Application Number | N/A | ||||||||
PCT International Filing date | |||||||||
PCT Conventions:
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