|Title of Invention||
A NOVEL PROCESS AND SYSTEM FOR RECOVERY OF ENERGY AND RECYCLABLES FROM MUNICIPAL WASTE TO SEFUL FUEL
|Abstract||The invention relates to a Novel Process and System for Converting Municipal waste to Useful Fuel. (a) means for feeding the raw material into the system. (b) rotary screening for separating sand, grit and other noncambustible that are loosely mixed. (c) means for drying to obtain a canbustibl e refined fuel such that the waste becomes campletely bio-inert by killing all bacteria. (d) means for separating ferrous and non-ferrous metals fran the waste. (e) means for shredding various materials in to pieces (f) means for air classifying the aforesaid product for differential density separation. (g) means for pellestising the aforesaid matter to produce general purpose fuel pellets having substantially smokeless and free burning characteristics and the material is subsequently collected.|
Field of Technology
This invention relates to solid waste management. It concerns with obtaining energy / power using novel fuel. It further concerns with a novel technology for converting municipal solid waste to produce combustible fuel. More particularly fuel pellets of general purpose. A novel process and system have been developed using city municipal waste as raw material to produce substances which can be used as fuel both in industrial sector as well as in domestic sector.
Salient features of the technology are as follows.
1. Converting waste to useful energy resource.
2. Problem of garbage disposal is solved by recycling the waste.
3. This technology is a refuse derived fuel technology wherein the process of converting waste to fuel is eco friendly.
4. The fuel is a substitute to natural resources.
5. The technology leads to enhancement of environment. It is not only eco friendly technology but also environment benign technology.
6. The technology produces three kinds of successive / concurrent effect.
a. Energy production
b. Ecology conservation.
c. Environment friendly
The refuse derived fuel process is not just environment-friendly but also environment-benign, for it actually contributes to the enhancement of the environment by providing a continuous outlet for the garbage generated - with a conversion time of just 25 minutes. This technology enriches garbage by the process of elimination, not addition. In fact, while the calorific value of garbage before the refuse derived fuel process is in the region of 900 cal/g, the post refuse derived fuel garbage is enriched to about 3600-3800 cal/g.
The refuse derived fuel technology is also extremely profitable - for the raw material is practically free of cost. Besides, the plant and machinery are completely indigcniscd. So, by investing in it, one get economical fuel for the industry and, at the same time, play a role in keeping the surroundings clean.
The burning characteristics of this fuel can be tailor-made within a certain range by blending with other waste material. The process is flexible enough to accommodate different blends and produce fuel pellets of different characteristics to suit specific demands. This means the process can adjust to changes in the supply side and in the
These fuel pellets can be used in a conventional steam power plant for steam and power generation. So one can stop at developing a primary source of energy from garbage (via fuel pellets), or go ahead and generate steam and power, depending on local requirements.
The plant, will eliminate additional transport costs and ensure adequate supply of raw material. The basic problem that is being solved here is that of garbage disposal, which is actually being converted into an energy asset.
The pellet plant can replace coal in the industrial sector and kerosene in the domestic sector. This fuel has been successfully tried in industrial boilers as a substitute for coal, with clean emissions and high efficiency. And in the domestic sector, substituting kerosene, charcoal and firewood. Efficient stoves have also been developed for using this fuel in the domestic sector. So, the refuse derived fuel process will actually help not only to conserve our natural resources but also provide a clean economic alternate fuel to poor people who use kerosene and firewood.
Waste is a perennial resource - and by recycling it, the environment is kept clean. And as the process rejects come out sterilised, they do not pose a health hazard - which the open dumping of garbage does. Also, industrial waste like bagasse and pith can be blended with the normal waste for differing types of fuels.
This process is so flexible that one can offer it in modules that vary according to the quantum of garbage in townships. In fact, one can install just a fuel plant. Or commission an entire integrated power plant. The refuse derived fuel process also contributes towards maintaining the ecological balance. Further by adopting the said process and generate fuel to replace fire wood this strain on forests could be reduced, as
the only raw material needed is waste. Therefore it is clear that this novel technology tackles a ever increasing problem of garbage disposal and converters it into an energy
The municipal solid waste poses a disposal problem day by day in metro cities all over the world as landfills - which is the usual form of disposal and the landfill areas the receding from cities collection of waste result in escalating transport costs because of increasing consumption of diesel oil, a petroleum.
The municipal solid waste has dormant energy which when tapped for useful purposes will be a perennial source of renewable energy. Thus, a disposal problem could be converted into an energy asset. This will be a substitute for wood based and petroleum based fuels in use. To that extent, the present invention will contribute to minimize the ill-effects of deforestation on ecology, and conserve the precious petroleum reserves.
Heterogeneous product consisting of a conglomerate of various substances with wide ranging qualities. Broadly, it consists of combustible materials which on burning gives out heat energy and non-combuslibles which do not burn. Thus, it has energy bearing constituents. Municipal Solid Waste as such does not respond easily to combustion for release of the dormant energy present in it because of the large quantities of non-combustibles present therein.
When allowed to burn this municipal solid waste will not burn easily and will give out lot of smoke and pollute the atmosphere. It has to be processed to eliminate the non-combustibles before it can be burnt to release energy.
A new technology has been developed by which the dormant energy in the Municipal Solid Waste could be made available in the form of free burning fuel.
The process comprises refining municipal solid waste by progressively identifying and eliminating the non-combustibles therefrom. The remaining material which is rich in combustibles will burn well.
The refined fuel may be further processed along with or without additives to produce pellestised fuel. This way, a general purpose fuel is produced which can be used in place of other conventional fuels in their respective burning equipments without modifying them in any manner. By varying the blend, pelletised fuel can be made in a wide range, matching the burning characteristics of most of the other fuels in use.
Generally waste is found to be a mixture of various material, plant based biomass, synthetic material like plastics, inserts like sand, grit, glass, ceramics, metals both ferrous and nonferrous, moisture etc., all in various combinations.
The integral processing plant according to the present invention performs various functions starting with removal of ferrous metals by magnetic separation, non-ferrous metals by metal detectors / air classification and elimination thereof.
Sand, grit etc are removed in several stages starting with initial screening and then winnowing and screening. Moisture reduction to the desired level is achieved by heating and drying using hot air medium in multiple stages. Non-ferrous non-combustibles are eliminated by using the principle of differential density in air lift system at different stages. Winnowing and screening process is again carried out to eliminate non-combustibles to the desired level.
The refining of municipal solid waste to the desired level of presence of non-combustibles is achieved upto this stage. Now, in specially designed boiler furnaces, this refined product can be used as fuel and steam and power can be generated. By using Extraction stream from the turbine for hot air generation to dry the garbage, the thermal efficiency of the system is greatly increased and the cost of power generation is reduced. This process of using this fuel in order to generate power form subject matter for another patent. The other option is to make a general purpose fuel in pelletised form, which can again be used as fuel in a conventional boiler for steam and power generation, or the fuel can be used in the domestic sector to replace charcoal, firewood, kerosene etc.,
The segregated combustibles are then shredded to the required size, say less than approximately 1/4". The fibre length may be restricted to 3/4" approximately. The shredded municipal solid waste is airlifted and screened once again to eliminate fine dust. In the air classifier, all non ferrous non combustible solids are eliminated.
The shredded waste can be pelletised as such or proportioned and blended with other waste and mixed thoroughly with or without binder as the case may be and then pelletised in a pelletiser. The size of the pellets can be controlled by changing the die in the pelletiser suitably. The pelletisation process is a heat generating process and therefore the pellets are cooled and sieved once again for removal of any fine materials.
By suitably blending the shredded municipal solid waste with other waste materials the desired burning characteristics and calorific value of the fuel pellets can be achieved.
Pellets can be made of any desired shape and size. The generally preferred dimensions are from 5mm to 30mm or more in diameter and from 5mm to 50mm or more in length.
The additives are generally waste material from agriculture, forest, industrial & plantation sectors. Any other suitable material could be added to meet special requirements and particular fuels. Besides these materials, certain agents for improving ignition, free burning quality, retentivity and calorific value could be added. Fines from mineral fuels like coal, lignite, coke etc. or some proportion of petroleum distillates could be added.
The wide choice of these substances enables production of pellets with wide range of quality and grade. Specific blends could be selected to achieve desired quality in the fuel pellets. Binders could be used in pellet formation or binders need not be used as per the need of the specific blend.
The novel process of municipal solid waste conversion comprises the following series of steps
(a) metal separation both ferrous and non-ferrous,
(b) separation of sand, grit etc that are loosely mixed,
(c) separation of fine sand, mud etc that is sticking to combustibles,
(d) separation of non-ferrous non-combustibles like ceramics, stones, glass pieces, aluminium, leather etc.
(e) Removal of excess moisture.
Each of these steps can be carried out in single stage or multiple stages depending on the composition of the Municipal Solid Waste and the required composition of the refined Municipal Solid Waste. The sequence of the process also could be varied as per the demands of the product. As garbage is a substance without any precise composition, the process essentially has to be kept flexible, to get a reasonably consistent product starting with raw material of varying composition. Each of these functions is carried out in specially designed equipment and all of these integrated into a plant. As mentioned earlier, the sequence of operation could be different to meet the particular needs of composition.
Apart from the process invented as aforesaid, the invention address to novel
system/plant for a executing the invented process. Both the process and the system
constitute the core of this novel invention.
It is the primary object of the invention to invent a novel process for conversion of Municipal Solid Waste to combustible fuel.
It is another object of the invention to invent a novel system for conversion of municipal solid waste to combustible fuel.
It is another object of the invention to invent a novel system for conversion of municipal solid waste to combustible fuel where in the system employes indigenous machines and hence economical.
It is another object of the invention to invent a novel system for conversion of municipal solid waste to combustible fuel by which an economical fuel is obtained.
It is another object of the invention to invent a novel system for conversion of municipal solid waste to combustible fuel where in the system uses raw material which is available free of cost.
It is another object of the invention to invent a novel system for conversion of municipal solid waste to combustible fuel wherein the use of fuel on the system results in eco friendly atmosphere and hence the system is eco friendly and eco benign.
It is another object of the invention to invent a novel system for conversion of municipal solid waste to combustible fuel where in the conversion time of waste in to fuel is quick.
Futher objects of the invention will be clear from the following description.
The invention also relates to system for converting municipal solid waste to useful power.
The invention will now be described, by way of illustration only, with reference to the accompanying drawings in which :
Fig. 1 shows a flow diagram of municipal solid waste conversion process
Fig. 2 shows entire flow diagram of the pelletising process starting with the municipal
waste as raw material. Fig. 3 shows schematic diagram of refining and pelletising processes starting from raw
municipal solid waste in order to produce blended fuel pellets, Fig. 4 shows a typical configuration of the entire conversion plant, depicting various
Figuie 1 & 2 shows the process steps in involving the conversion of municipal solid waste into novel fuel. The process comprises mainly the following steps.
a) Visual Inspection & screening for removal of any extraneous matter which cannot be converted into waste.
b) Chopping of municipal waste to smaller size.
c) Screening and Feeding into appropriate device for further action.
d) Drying (1st stage) for reduction of water Content and rendering it bioinert.
e) Separating ferrous and non-ferrous material from the waste.
f) Screening & Feeding to next stage.
g) Shredding the product into small pieces.
h) Air Lifting the product for density separation i) Mixing of other waste which is optional, j) Pelletising the product k) Cooling and baggaging.
It is to be noted that mixing with other waste is an optional step. Figure 3 & 4 shows the system layout for executing the process mentioned in this description.
As illustrated in Fig. 4, Municipal Solid Waste is charged into a hopper 1 generally made of MS plate construction. The mode of charging the hopper could be by any means, manual, by pay-loader, by E.O.T. crane etc. depending on the size of the refining plant and other local factors.
Municipal Solid Waste is discharged from the hopper 1 into a conveying system, either a moving belt type or vibrating type.
Sand and grit of certain size forming a mixture with the combustibles in Municipal Solid Waste are removed by sieving, as Municipal Solid Waste moves along the conveying systems. Due to lack of thorough exposure, only partial removal of loose sand and grit will be achieved in one stage operation.
Municipal Solid Waste is then subjected to shredding in a rotary shredder. This equipment has a rotor with swivel or fixed arms rotating inside a casing. Municipal Solid Waste is subjected to a process of bashing and tumbling to shake out sand and grit sticking to the combustibles. Also, soft stone, brick pieces etc will be reduced in size. The entire mass is filtered through steel rod basket, and air lifted in a vertical column or sieved in a vibrating conveyer.
Moisture reduction in Municipal Solid Waste is achieved in a rotary drier 3 by exposure to hot air. Municipal Solid Waste is fed into the rotary drum of the drier by a vibratory conveyor which passes through the inlet hood. The drum is mounted on idle rollers with a predetermined inclination. A device to change the inclination of the drum also can be incorporated in the design of the drier.
The drum has flights fixed in a particular pattern suitable to the raw material. The flights are rectangular plates fixed radially at the inside surface of the drum at calculatea intervals. The flights lift the material as the drum rotates, and drop the material from the top position. At the same time for every round the material drops a little forward because of the inclination of the drum. Thus, after several revolutions of the drum, the material would reach the exit end of the drum after dropping from the top several times being carried again and again by the flights. The dwell-time of the product in the drum is set by controlling the inclination and speed of the drum. While dropping from the top, the material is exposed to the stream of hot air which is blown in from the exit end and travels to the inlet hood at a predetermined velocity.
As material flows towards the exit end and hot air towards the entry end, in the counter-flow stream, heat transfer occurs from hot air to material. This heat evaporates the moisture in the material and the vapour is absorbed in the air. This way transfer of moisture occurs from Municipal Solid Waste to air. In this process air looses temperature and increases in relative humidity. At the entry end when air leaves the drier, its temperature is lower and its humidity is higher. At the exit end the material has lost moisture and is drier than when it entered the drier.
As the air of higher humidity and lower temperature leaves the inlet hood of the drier 3, part of it is exhausted to atmosphere and part of it is recirculated into the heater for reuse in the drier, in order to increase process efficiency of moisture removal.
A hot air generator supplies hot air to the drier. The hot air generator could be different types using any kind of fuel like oil, coal, fuel pellets, wood etc., It essentially consists of a furnace suitably designed to burn a particular fuel with forced, induced, or balanced air system. The hot flue gas from the furnace is made to heat the air for
drier through a heat exchanger, tubular, plate, or any other type. The heat transfer occurs through this heat exchanger and the air gets heated to the required temperature and the low temperature flue gas is exhausted through a chimney. The temperature of hot air maintained at desired level by controlling the fuel burned.
Air is blown through a heat exchanger by a blower and the hot air from the exit of heat exchanger enters the drier at the exit through ducts, and the return air from the drier is partly exhausted and partly recirculated depending on the moisture content in the Municipal Solid Waste. This is achieved by judicious control of dampers in the circulating air system.
Municipal Solid Waste as it leaves the drier 3 is relatively drier and some of the fine dust sticking to the combustibles reel off during its passes through the drier, which can be removed by seiving in a vibrator conveyer.
As the material is moved on this system, powerful magnets attract any ferrous metals in the Municipal Solid Waste and separate them. The separated metal is collected periodically. The magnetic separation 4 itself could be done either by plates, suspended, drum type, permanent or electro magnets.
Non-ferrous metals are detected by metal detectors mounted on the conveying system. These detectors form a circuit enclosing the material in the conveyors and the presence of any metal creates a disturbance in the circuit and this signal is used to announce the presence of metal by audio/visual display or it can be used to stop the system. In either case it enables the metal to be picked out from the system. Non-ferrous metals are also removed in the air classifier.
Municipal Solid Waste leaving the magnetic separate may be further fed in to shredder (5).
In the airlift system, the separation of non-ferrous non-combustibles is achieved, using the principle of differential density. The heavier glass, ceramics, bricks, stones
etc will flow down from the vertical column and mostly combustibles, fine dust sand grit etc would be carried up. Then the stream of air containing all these material is turned horizontal and it enters a tangential separator.
This equipment has a suction cone one side, and the air stream entering tangentially at the top at a predetermined velocity. The air being lighter is sucked through the suction cone. The material takes a circular path along the periphery of the tangential separator. As the material reaches the bottom side it drops into a cutout in the circular body of the tangential separator. The cutout has a vertical neck leading to an airlock valve. The material drops into the top quadrant of the airlock and as the valve rotates, reaches the bottom of the neck and drops down into a chute. The airlock valve seals the inside of the tangential separator from the atmosphere. The air that is sucked through the cone by a powerful fan is blown into a bag type filter for collecting fine dust that it may carry with it and allow only clean air to blow out. The bag filter can be cleared periodically.
All the above systems are so arranged for continuous flow of material and the elimination of non-combustibles occurring in steps at various stages as the material moves along the plant. Each of the precesses mentioned above could be incorporated in single stage of multiple stages depending on the amount of particular non-combustibles to be removed.
The output material from the plant will be very rich in combustibles with only very little presence of non-combustibles. The degree of refinement depends on the requirement of the quality of the end product. The plant can be made suitable to meet this requirement. This product as such could be used as fuel in a specially designed furnace and steam and power could be generated. Alternatively, this product could be further processed to produce a general purpose fuel pellets in different grades to substitute various fuels in use in different sectors of energy usage.
Figure 4 depicts the entire plant / system to carry out the said novel process. As indicated individual components will vary according to the process. As mentioned earlier
the mixing of additional waste is a optional step. Accordingly the system components are adjusted. Main function of the system components are explained in the following description.
Referring to Fig. 4 of the drawings, it is clear that the entire system has various components the details of which are clearly and particularly described in this complete specification. Municipal Solid Waste will be unloaded from lorries in the intake yard where it is first subjected to visual inspection.
The Municipal Solid Waste is mechanically handled and fed on to a conveying system 1. Here it is subjected to first stage seiving and rotating screen (2) for removal of dirt, debris, sand, grit.
Thereafter, the material enters the rotary drier 3 for removal of excess moisture through a chopper, (not numbered) The materiar leaving the drier 3 is taken in single stream or multiple streams for shredding and pelletising. Magnetic seperator (4) separates the magnetic waste from the raw material.
The dried material enters shredder 5 where it is shredded to the desired size. The shredded material is air-lifted by air-lift system - air classifier (6) and dropped into the bin. In this process further non-combustibles are removed to obtain Municipal Solid Waste refined and shredded to the desired level. From the bin 12 Municipal Solid Waste is proportioned and fed on the mixer, (not shown) Other wastes are screened in vibratory conveyer and dried in drier, dried in drier and fed, through a proportioning and conveying system, on to mixer. In the mixer, the shredded Municipal Solid Waste is blended with other waste. There after the mixture is fed on to the pre densifier 7 for consolidating. The densified fuel from the pre dentifier 7 are taken to secondary drier.
There is a provision for exhaust (10) for heating air in the first stage. Further there is another provision for exhaust for filtering air in the second stage (13). There is
Further a provision by way of a bunker 12 for storing and forwarding waste in the process flow to synchronize the speed of the entire process. There is a provision for a bag filter to clean air. Hot air generator (14) is of two types. With feed back of the fuel used in the process or use of the steam from the power plant.
Most of the waste materials obtained from plantation sector, industrial sector, forest sector are added depending on their proximity to the location of this plant and their cost fact.
The condition of the mixture as it enters the pelletiser is critical for good pelletising. Moisture, heat, blending agent, composition of mixture, physical size matrix of the constituents are all to be closely monitored and corrected. Any kind of mixture or a mixture of any condition will not pelletise. Control of the parameters mentioned above is very important to produce good pellets using Municipal Solid Waste.
It will be appreciated that the embodiments described herein are merely illustrative, and the entire process essentially has to be kept flexible to get a reasonably consistent product starting with raw Municipal Solid Waste of randomly varying composition. It is to be appreciated that various modifications / improvements as are known to a person skilled in the art are possible and incorporated herein falling within the scope of the present invention.
In another application for patent a process of using the fuel obtained by this invention will be advantageously used for producing electric power and in the same application a novel system for the generating electric power is also described and claimed.
I Claim :-
1. A Device for the preparation of combustible fuel from municipal solid waste
which comprises refining municipal solid waste to eliminate the non-combustibles
there from to a desired level by the following equipments.
(a) means for feeding the raw material into the system.
(b) rotary screening for separating sand, grit and other noncombustible that are loosely mixed.
(c) means for drying to obtain a combustible refined fuel such that the waste becomes completely bio-inert by killing all bacteria,
(d) means for separating ferrous and non-ferrous metals from the waste.
(e) means for shredding various materials in to pieces
(f) means for air classifying the aforesaid product for differential density separation.
(g) means for pellestising the aforesaid matter to produce general purpose fuel pellets having substantially smokeless ad free burning characteristics and the material is subsequently collected.
2. Device, as claimed in claim 1, wherein means are employed by which ferrous
metals are removed by magnetic separation and non-ferrous metals are removed using metal detectors/ airclassifier.
3. Device as claimed in claim 1 or 2, wherein sand, grit, mud and like non-
combustibles are removed in one or more stages by screening.
4. Device claimed in any of the proceeding claims 1 to 3, wherein means are
employed by which the non-ferrous / non-combustibles are removed in one or more stages using the principle of differential density in air-classifier systems and using appropriate means to carryout such effect.
5. A system as claimed in any of the preceding claims, wherein said drying is
carried out in one ore more stages using means for generating hot air either by
feed back of fuel are by using extraction stream from a power plant.
6. Device as claimed in any of the proceeding claims, wherein before pelletisation the refined fuel is shredded to the desired size, air-lifted and screened to eliminate fine dust, either proportioned, and mixed and blended with or without additives/ garbages and/or binders and the said system employes appropriate means to carryout this step in the process of conversion of municipal waste into fuel.
7. Device as claimed in claim 6, wherein means by which pellets are cooled and
seived to remove any fine non-combustible materials embodied in the system.
8. Device for the preparation of combustible fuel from municipal solid waste, substantially as herein described and illustrated in the accompanying drawings.
9. A combustible fuel whenever prepared by a process as claimed in any of the preceding claims.
10. A process for the preparation of combustible fuel from municipal solid waste for which a system is claimed in claim 1 the said process comprises refining municipal solid waste to eliminate the non-combustibles therefrom to a desired level by the following steps :
a) Visual Inspection & screening for removal of any extranous matter which cannot be converted into fuel.
b) Chopping of municipal waste to smaller size.
c) Screening and Feeding into appropriate device for further action.
d) Drying (1st stage) for reduction of water content and rendering it bio-inert.
e) Separating ferrous and non-ferrous material from the waste.
0 Screening & Feeding to next stage.
g) Shredding the product into small pieces.
h) Air classifier the product by density separation
i) Mixing of Additives / other waste which is optional.
j) Pelletising the product
k) Cooling and baggaging.
11. A process as claimed in claim 10, wherein ferrous metals are removed by magnetic separation and non-ferrous metals are removed using metal detectors / classifiers.
12. A process as claimed in claim 10, wherein sand, grit, mud and like non-
subustibles are removed in one or more stages by screening
A process as claimed in any of the proceeding claims 10, wherein the non-ferrous non-combustibles are removed in one or more stages using the principle of differential density in air-classifying systems.
14. A process as claimed in any of the preceding claims, wherein said drying is
carried out in one ore more stages using hot air.
15. A process as claimed in any of the proceeding claims, wherein before pelletisation
fuel is shredded to the desired size, air-lifted and screened to eliminate fine dust,
proportioned, mixed and blended with or without additives and/or binders.
16. A process as claimed in claim 10, wherein the pellets are cooled and seived to
remove any fine non-combustible materials.
17. A process for the preparation of combustible fuel from municipal solid waste,
substantially as herein described and illustrated in the accompanying drawings.
18. A combustible fuel whenever prepared by a process as claimed in any of the
|Indian Patent Application Number||469/MAS/2000|
|PG Journal Number||50/2007|
|Date of Filing||20-Jun-2000|
|Name of Patentee||SHRI. K.S. SHIVAPRASAD|
|Applicant Address||2349, FIRST FLOOR, 16TH MAIN, 2ND, 'B' CROSS, HAL II STAGE, BANGALORE - 560 102|
|PCT International Classification Number||C1OL 5/40|
|PCT International Application Number||N/A|
|PCT International Filing date|