Title of Invention

"A METHOD AND AN APPARATUS FOR DRY QUENCHING OF COKE"

Abstract

Provided are a method and an apparatus, for dry quenching of coke, where clinker does not deposit even when an improvement in safety and the increase of the amount of heat recovery are attempted by injecting air into a pre-chamber and thus burning combustible gases and fine coke or by similar measures. The present invention provides a method and an apparatus for dry quenching of coke; wherein quenching tower 1 consisting of cooling chamber 2 and pre-chamber 3 located above it is used, red-hot coke 9 is charged into the quenching tower from above, the sensible heat of said red-hot coke is exchanged in the cooling chamber using inert gas as a heat exchange medium, and the heat is recovered as steam; which method is characterized by injecting water or steam 26 together with air 24 into pre-chamber 3 from above. Either one or both of the injection amount of water or steam 26 and of air 24 injected into the pre-chamber is controlled so that the temperature in pre-chamber 3 is kept at 1,150°C or lower.

Full Text

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for dry quenching of coke. 2. Description of the Related Art When cooling red-hot coke discharged from coke ovens, an apparatus for dry quenching of coke (so-called CDQ, Coke Dry Quencher) is used for the purpose of energy conservation through the recovery of the sensible heat of the red-hot coke. A dry quencher comprises a cooling chamber to transfer the sensible heat of the red-hot coke to an inert gas and a pre-chamber located above said cooling chamber. The red-hot coke is fed into the pre-chamber from above. The pre-chamber is provided for the purpose of absorbing fluctuations of the feeding rate of the red-hot coke and stabilizing the operation of the system. The coke to be charged at a temperature of from 950°C to 1,100°C exchanges its heat with the inert gas in the Cdoling chamber to be cooled to approximately 2 00 °C and is then discharged at a predetermined rate. The' inert gas heated to 900°C after the heat exchange is discharged to a ring duct through an upper portion of the cooling chamber, passes through a primary dust catcher and its heat is recovered at a waste heat boiler. The inert gas is then pumped back to the cooling chamber by a circulating blower. The coke charged to the apparatus contains volatile matter and fine coke. Since the volatile matter is highly combustible, when included in the circulating gas in a high percentage, it may cause abnormal combustion. When air is injected into the pre-chamber under such a condition, the volatile matter and fine coke remaining in the lump coke can be burned. There also are cases where injected air burns some of the surface layers of the red-hot coke. Consequently, it is possible to raise the heat amount of the gas discharged from the cooling chamber as a result of mixing the air heated by the above combustion and the combustion exhaust gas with the inert gas. Because the temperature of coke entering the cooling chamber via the pre-chamber has been raised, the amount of heat recovered by the inert gas at the cooling chamber also increases. As a result, it is possible to increase the amount of steam generated by the waste heat boiler. Said air injection into the pre-chamber makes it possible to maintain heat recovery amount of the waste heat boiler constant even when the coke temperature in the cooling chamber is lowered by a decrease in the supply of red-hot coke or a temperature decrease of the charged red-hot coke, and to increase the amount of heat recovered by the waste heat boiler during the stable operation of a coke dry quencher. Japanese Unexamined Patent Publication No. 61-37893 discloses a method to inject air into a pre-chamber. Combustion of the residual volatile matter, fine coke and some of the lump coke by air injection into the pre-chamber raises the temperatures of both the injected air and the coke much higher than the temperature of the charged red-hot coke in the pre-chamber. Then, when the temperature inside the pre-chamber is raised to approximately 1,200°C, ash in the coke melts and evaporates, and said evaporated ash is carried to the cooling chamber. As the inert gas temperature introduced to the cooling chamber is approximately 900°C, the evaporated ash in the pre-chamber condenses and coagulates on a sloping flue section located at the upper part of the cooling chamber. This coagulation called clinker causes problems of hindering circulation of the cooling gas to cool the high Temperature coke by clogging gas vent holes and increasing gas flow resistance. SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus, for dry quenching of coke, unsusceptible to the deposit of clinker as described above and capable of stabilizing the temperature of the boiler feed gas even when air is injected into the pre-chamber for the purpose of increasing the recovered heat amount, and for securing operational safety by burning combustible gases and fine coke or by similar measures. According to the present invention there is provided a method for dry quenching of coke wherein a quenching tower comprising a cooling chamber and a pre-chamber located above the cooling chamber, comprising the steps of, charging red-hot coke into the quenching tower from above, exchanging a sensible heat of said red-hot coke in the cooling chamber using inert gas as a heat exchange medium, recovering heat in the form of steam, characterized in that injecting one or both of water or steam with air by a controlled amount into the upper space of the pre-chamber so that the temperature inside the pre-chamber is kept at higher than a temperature of red-hot coke and lower than the predetermined temperature of 1150°C, burning components in a high temperature exhaust gas from the quenching tower by supplying air at a point before it reaches a waste heat boiler. According to the present invention there is also provided an apparatus for carrying out the method, said apparatus comprising; a quenching tower composed of a cooling chamber where sensible heat of red-hot coke is transferred to inert gas and a pre-chamber located above the cooling chamber, a waste heat boiler for recovering the heat of the inert gas in the form of steam. a system composed of injector to inject air into said pre-chamber and another injector to inject water or steam into said pre-chamber, which both injectors being installed at the upper part of said pre-chamber, an injection controller to control one or both of the injection amount of water or steam and the injection amount of air into the pre-chamber, a waste heat boiler connected to the exit side of the quenching tower, and an air injector, to supply air for burning components of the exhaust gas, installed in a high temperature gas exhaust route between the quenching tower and the waste heat boiler. Namely, the gist of the present invention is as follows: A method for dry quenching of coke wherein quenching tower 1 comprising cooling chamber 2 and pre-chamber 3 located above cooling chamber 2, com.prising the steps of charging red-hot coke 9 into the quenching tower form above, exchanging the sensible heat of said red-hot coke in the cooling chamber using inert gas as a heat exchange medium, and recovering the heat in the form of steam, and injecting water or steam 26 with air 24 into the upper space of the pre-chamber 2. A method for dry quenching of coke according to item (1), characterized in that one or both of the injection amount of water or steam 26 and the injection amount of air 24 into the pre-chamber is/are controlled so that the temperature inside pre-chamber 2 is kept at higher than a temperature of red-hot coke and lower than the predetermined temperature. A method for dry quenching of coke according to item (2), characterized in that the predetermined temperature is 1,150°C. A method for dry quenching of coke according to any one of items (1) to (3), characterized in that components of high temperature exhaust gas 22 from quenching tower 1 are burned by supplying air 25 to exhaust gas 22 at a point before it reaches waste heat boiler 7. A method for dry quenching of coke according to any one of items (!) to (4), characterized in that the temperature of waste heat boiler feed,gas 23 is lowered or controlled within a prescribed temperature range by supplying low temperature inert gas the to high temperature exhaust gas 22 discharged from quenching tower 1 at a point before said exhaust gas reaches waste heat boiler 7. A method for dry quenching of coke according to item (5), characterized in that the above-mentioned low temperature inert gas is gas 29 divided from the inert gas to be fed to the cooling chamber. A method for dry quenching of coke according to item (5) or (6), characterized in that the temperature of waste heat boiler feed gas 23 is controlled within a target range by controlling the injection amount of air 24 and/or injection amount of water or steam 26 into the pre-chamber and controlling the amount of low temperature inert gas added to the high temperature gas discharged from the cooling chamber and the pre-chamber at a point before the high temperature gas reaches the waste heat boiler. A method for dry quenching of coke according to any one of items (1) to (7), characterized in that water or steam 26 is injected into the pre-chamber through the nozzle of air injector 14. A method for dry quenching of coke according to any one of items (1) to (8), characterized in that the above-mentioned water injection into the pre-chamber is done in the form of mist. A method for dry quenching of coke wherein quenching tower 1 consisting of cooling chamber 2 and pre-chamber 3 located above cooling chamber 2 is used, red-hot coke 9 is charged into the quenching tower from above, the sensible heat of said red-hot coke is exchanged in the cooling chamber using inert gas as a heat exchange medium, and the heat is recovered in the form of steam, which method is characterized in that air 24 is injected into said pre-chamber from above and the injection amount of air 24 into the pre-chamber is controlled so that the temperature inside said pre-chamber is kept at 1,150°C or lower. The gist of the present invention is further as follows: An apparatus for dry quenching of coke comprising quenching tower 1 consisting of cooling chamber 2 where sensible heat of red-hot coke is transferred to inert gas and pre-chamber 3 located above cooling chamber 2, and waste heat boiler 7 for recovering the heat of the inert gas in the form of steam, which system is characterized by comprising air injector 14 to inject air 24 into said pre-chamber and injector 16 to inject water or steam 2 6 into the pre-chamber, both injectors being installed at the upper part of pre-chamber 3 . An apparatus for dry quenching of coke according to item (11), characterized by comprising injection controller 17 to control one or both of the injection amount of water or steam 2 6 and the injection amount of air 24 into pre-chamber 3 so that the temperature inside the pre-chamber is kept at 1,150°C or lower. An apparatus for dry quenching of coke according to item (11) or (12), characterized by comprising air injector 15 to supply air for burning components of exhaust gas 22, installed in a high temperature gas exhaust route between quenching tower 1 and waste heat boiler 7. An apparatus for dry quenching of coke according to any one of items (11) to (13), characterized by comprising an inert gas supply apparatus for supplying low temperature inert gas 2 9 to lower the temperature of waste heat boiler feed gas 23 or to control said temperature within a prescribed range, installed in a high temperature gas exhaust route between quenching tower 1 and waste heat boiler 7. An apparatus for dry quenching of coke according to item (14), characterized in that the supply apparatus of low temperature inert gas is apparatus 19 to supply gas divided from the inert gas to be fed to the cooling chamber. An apparatus for dry quenching of coke according to item (14) or (15), characterized in that controllers are provided to control the injection amounts of air 24 and/or of water or steam 26 into the pre-chamber and the amount of low temperature inert gas added to the high temperature gas discharged from the cooling cnamber and the pre-chamber at a point before the high temperature gas reaches the waste heat boiler, and that a processor is provided to control the temperature of waste heat boiler feed gas 23 within a target range. An apparatus for dry quenching of coke according to any one of items (11) to (16), characterized in that the nozzle of air injector 14 to inject air into the pre-chamber is also used for injecting the water or steam. An apparatus for dry quenching of coke according to any one of items (11) to (17), characterized in that the injector to inject water into the pre-chamber does so in the form of mist. An apparatus for dry quenching of coke comprising quenching tower 1 consisting of cooling chamber 2 where sensible heat of red-hot coke 9 is transferred to inert gas and pre-chamber 3 located above cooling chamber 2, and waste heat boiler 7 for recovering the heat of the inert gas in the form of steam, which system is characterized by comprising air injector 14 installed at the upper part of the pre-chamber to inject air into pre-chamber 3 and injection controller 17 to control the injection amount of air 24 into pre-chamber 3 so that the temperature inside the pre-chamber is kept at 1,150°C or lower. An apparatus for dry quenching of coke according to any one of items (12) to (19), characterized in that the temperature inside the pre-chamber is measured by temperature measuring apparatus 18 to measure the temperature of the atmosphere or the coke at the lower part of a brick lining inner shell using a thermometer or a radiation thermometer inserted from outside. The present invention is characterized in that water or steam 26 is injected into pre-chamber 3 together with air 24. Hydrogen gas and carbon monoxide are generated by the water gas reaction taking place when red-hot coke and steam contact each other, and the reaction is an endothermic reaction. When water is injected, another endothermic reaction of water evaporation is added to the endothermic reaction of the above-mentioned water gas reaction. Accordingly, while the temperature of the inside of pre-chamber 3 is reached to more than the temperature of red-hot coke by the air injection into the pre-chamber, an endothermic reaction is caused by the injection of water or steam into the pre-chamber, making it possible to maintain the inside temperature of pre-chamber 3 at or below a prescribed temperature as a result. In this way, the melting and evaporation of ash in pre-chamber 3 can be prevented, precluding the deposition of clinker in the gas circulation system. The hydrogen gas and carbon monoxide generated by the water gas reaction are immediately partially burned by the air injected into pre-chamber 3 but the remaining portions are discharged from the cooling chamber to ring duct 5 together with inert gas 27. Air 25 is injected into ring duct 5 or gas discharge pipe 12 leading to the boiler, and the hydrogen gas and the carbon monoxide burn in the ring duct or the gas discharge pipe to generate heat, which is finally recovered at waste heat boiler 7 in the form of steam. Accordingly, although the temperature inside the pre-chamber is decreased by the water gas reaction, the amount of heat finally recovered is increased. BRIEF DESCRIPTION OF THE Acompaying DRAWINGS Figure 1 is a schematic diagram of an apparatus for dry quenching of coke according to the present invention. 2 is a graph showing the relationship of the air in amount into the pre-chamber and the water addition am6unt into the pre-chamber with the gas temperature at the lower part of the pre-chamber. Figure 3 is a graph showing the relationship of the ring duct injection air amount and the inert gas addition amount with the boiler feed gas temperature. DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention is described hereafter based on Figure 1. Quenching tower 1 for cooling red-hot coke 9 consists of pre-chamber 3 and cooling chamber 2 arranged vertically. Pre-chamber 3 and cooling chamber 2 are separated in terms of gas flow by sloping flue section 4 formed along the circumference of its inner shell. Red-hot coke 9 at a temperature of approximately 980°C is charged into pre-chamber 3 from above and moves gradually downward, then is cooled in cooling chamber 2 by inert gas 27 injected through injection pipe 11 at the lower part of the cooling chamber. The temperature of coke 10 discharged from the bottom of the cooling chamber is approximately 210°C. The temperature of inert gas 27 injected into the cooling chamber increases as the gas exchanges heat with the red-hot coke while flowing upward in the cooling chamber. Then the gas is discharged to ring duct 5 through sloping flue section 4 located in the upper part of the cooling chamber. The inert gas is sent from ring duct 5 to primary dust catcher 6, then to waste heat boiler 7, where its heat is recovered and its temperature falls to approximately 180°C, and is then injected again to cooling chamber 2 by circulation blower 8. Air 24 is injected into pre-chamber 3 by air injector 14 located in the upper part of the pre-chamber. Oxygen in the injected air reacts with residual volatile matter, fine coke and some parts of the lump coke. The reactions are mainly exothermic reactions to generate carbon monoxide. The injected air, reaction product gas and coke travel down the pre-chamber, their temperatures rising, and the temperatures reach their respective highest figures at the bottom of the pre-chamber. At the bottom of pre-chamber 3 the injected air and the reaction product gas mix with the inert gas coming up from below and are then discharged to ring duct 5 through sloping flue section 4. Air 25 is injected through air injection pipe 15 into ring duct 5 or gas discharge pipe 12 to burn the carbon monoxide generated in the pre-chamber into carbon dioxide. Further, according to the present invention, water or steam 26 is injected into pre-chamber 3 from above by injector 16. The injected water absorbs heat when evaporating into steam, and the steam absorbs heat as well as generates hydrogen gas and carbon monoxide through a water gas reaction when it contacts the red-hot coke. Accordingly, the temperatures of gas and coke in the pre-chamber are decreased by injecting water or steam, and thus the temperatures of gas and coke in the pre-chamber can be controlled by regulating the injection amount of water or steam. The hydrogen gas and carbon monoxide generated through the water gas reaction flow down the pre-chamber and, after mixing with the inert gas coming from below at the lower part of the pre-chamber, are discharged to ring duct 5 through sloping flue section 4. Air 25 is injected into ring duct 5 or gas discharge pipe 12 to burn the hydrogen gas and carbon monoxide into water and carbon dioxide. At the same time, the heat amount of waste heat boiler feed gas 23 is increased by the combustion heat of said combustion. As a consequence of the injection of water or steam into the pre-chamber, the heat amount of waste heat boiler feed gas 23 increases. In the case of the present invention where water or steam is injected, therefore, it is also possible to decrease the air injection amount into the pre-chamber while ensuring the heat amount the waste heat boiler requires. Namely, it is possible to simultaneously control both the maximum temperature inside the pre-chamber and the amount and temperature of waste heat boiler feed gas 23 to the optimum conditions by means of regulating one or both of the air injection amount into the pre-chamber and the injection amount of water or steam into the pre-chamber. When the inert gas receives a large amount of heat from the cooling of red-hot coke and the heat amount to be fed to the waste heat boiler is sufficiently ensured, the temperature inside the pre-chamber can be lowered by simply decreasing the injection amount of air 24 into the pre-chamber, without supplying water or steam to the pre-chamber. Any one method can be chosen from among the following for measuring the temperature inside the pre-chamber: a method (18a) to measure the atmosphere temperature or the coke temperature near the inside wall of a brick lining inner shell by inserting a thermometer through the wall into the pre-chamber from outside; a second method (18b) to measure brick lining inner shell temperature or atmosphere temperature by a thermometer inserted into the brick lining inner shell; a third method (18c) to measure brick lining inner shell temperature near the lower part of the pre-chamber by a thermocouple or a non-contact type thermometer; or similar. In the present invention, the temperature inside. the pre-chamber is represented by the temperature of the brick lining inner shell temperature near the lower part of the pre-chamber. An preferable method is the one to measure atmosphere temperature or coke temperature at the lower part of the brick lining inner shell using a thermometer with a protective tube inserted from outside or the method to measure temperature of the brick or coke using a radiation thermometer. The measured temperature value inside the pre-chamber is sent to injection controller 17, not shown in the Figure, and injection controller 17 regulates the injection amount of water or steam 16 or air 24 so that the temperature inside the pre-chamber reaches a target temperature. It was conventionally considered that ash in fine coke melted at 1,400°C or more, but various tests have clarified tiiat it softens and melts at about 1,200°C. In the case of ash composed of many elements, the softening temperatuYe-tends to decrease. Hence, in consideratioln of temperature variation_ across the sectional area of a pre-chamber of a radius of about 10 m, the present inventors have found that a temperature inside the pre-chamber lower than 1,150°C can be regarded as a principal operating standard. It is effective for long-term stable operation to control the temperature to a yet lower figure in consideration of safety. As for the injection position of the air 24 and the water or steam 2 6 into the upper part of the pre-chamber, it is preferable to inject them onto upper part 30 of the red-hot coke layer in the pre-chamber or into space 31 formed by the surface of said red-hot coke layer and the pre-chamber. The reason for this is that, if the air and the water or steam are injected into red-hot coke layer 32, the reaction proceeds only with the coke near the injection point resulting in a non-homogeneous gas distribution, and temperature distribution and reactivity become uneven across the chamber section. The nozzle of air injector 14 and the nozzle of the injector of water or steam 16 can be installed as separate units, but it is acceptable to mix water or steam with air in the air injection nozzle and inject said mixed gas into pre-chamber 3. Further, it is particularly preferable to inject water in the form of mist. Besides raising the temperature inside the pre-chamber, another object of injecting air 24 into the pre-chamber from above is to burn volatile matter and fine coke included in the charged coke. For this reason, it is necessary to always maintain air injection even when the operating condition of the coke dry quencher is such that a sufficient amount of waste heat is recovered without air injection. A charging lid is opened when red-hot coke is charged. If atmospheric air comes into the pre-chamber on this occasion due to pressure balance, it is acceptable to stop the blower for forced injection. In order to use waste heat boiler 7 efficiently, it is essential to supply feed gas 23 for waste heat boiler 7 at a constant temperature and flow. It is also necessary to maintain a predetermined amount of air injection from above the pre-chamber, as stated above. Consequently, when there is enough heat input from red-hot coke, there may be cases where the temperature of gas 22 discharged from ring duct 5 exceeds the temperature adequate for feeding waste heat boiler 7. According to the present invention, the temperature of waste heat boiler feed gas 23 can be maintained at a target temperature by lowering the gas temperature by supplying low temperature inert gas to the gas pipe at a point between the exit of the ring duct and the primary dust catcher and mixing it with hot gas discharged from ring duct 5. It is preferable that a portion of the cool inert gas supplied by circulation blower 8 to cooling chamber 2 be divided by branch pipe 19 and divided cool gas 2 9 be used as the above-mentioned cool inert gas. The temperature of waste heat boiler feed gas 23 can be controlled by regulating the amount of said by-pass gas. Since the flow of inert gas 21 supplied to cooling chamber 2 is reduced by the amount corresponding to the flow of branched out gas 29, the flow of waste heat boiler feed gas 23 is kept constant. The philosophy of gas temperature control is described hereafter. Supposing that the temperature of red-hot coke charged to a CDQ is 950°C, as the amount of air injection into the pre-chamber is increased, the temperature inside pre-chamber rises, together with the temperature of coke,' as shown in Figure 2. The amount of air injection into the pre-chamber is determined by factors such as the amount of fine coke sticking to the surface of lump coke I charged into the system and the amount of residual volatile matter in the coke, which varies depending on the carbonization conditions. By injecting water or steam into the pre-chamber, the temperature is decreased as shown by the dotted and chain lines in Figure 2. I However, when there is any combustible gas in the pre-chamber due either to the water gas reaction or residual volatile matter in the coke, as described above, there are case where air 25 is injected into the ring duct or the gas duct leading to the boiler. (Said injected air is herein called "ring duct injection air".) This raises the temperature of the boiler feed gas, but the temperature can be controlled not to exceed an upper limit temperature, as shown in Figure 3, by increasing the injection amount of inert gas 29 to suppress the temperature rise. The temperature of the boiler feed gas changes depending on factors not easily measured during daily operation such as the temperature of charged coke, residual volatile matter in it, etc., besides the charging amount. In order to control the temperature within a target range, it is effective to regulate the amounts of air and/or inert gas 29 injected into the pre-chamber. As outlined in Figures 2 and 3, the method to control the temperature of the boiler feed gas by regulating the amount of air injection into the pre-chamber is applicable also to the case where no water is injected into the pre-chamber. When the amount of the ring duct injection air is set constant, the temperature of the boiler feed gas can be controlled by changing the injection amount of inert gas and, when "the gas from branch pipe 19 from the exit of the circulating blowe'r is used, the total balance of gas amount need not be considered, and thus control is easier. Figure 3 shows a case where the air injection amount into the pre-chamber is kept constant, but control is possible in a similar manner in cases where the air amount is changed. Example 1 The present invention was applied to an apparatus for dry quenching of coke as shown in Figure 1. The inner volume of cooling chamber 2 of the system for dry quenching of coke is 600 m3 and that of pre-chamber 3 is 300 m3. Red-hot coke 9 at a temperature of 980°C is cooled at a cooling rate of 170 t/h and the temperature of discharged coke 10 is 210°C. The temperature of red-hot coke is measured by a thermocouple inserted at the center position of the coke (center position of the coke in a vertical, horizontal and height direction) just before charging to the dry quenching cooling apparatus. Air 24 is injected from the upper part of the pre-chamber into space 31 formed by upper surface 30 of red-hot coke and the pre-chamber. The air injection amount is 7,000 Nm3/h. Further, water or steam 26 for controlling the temperature inside the pre-chamber was mixed with air 24 in a pipe of air injector 14 and then said mixed gas was injected into the pre-chamber. The temperature inside the pre-chamber was experimentally measured by several methods. The first process was (18a) wherein a thermometer was inserted from outside into the upper part of the pre-chamber where its shell is in a conical form. The second process was (18b) wherein a thermometer was inserted into a brick lining inner shell separating the inner part of the pre-chamber from the ring duct surrounding it. The third process (18c) wherein the ambient temperature at the lower part of the brick lining inner shell was measured by inserting from outside a thermometer having a protective tube of stainless steel. The first process gave a somewhat low temperature, but according to the second and the third processes, which gave nearly the same readings. According to the present invention, the temperature inside the pre-chamber is defined by the temperature measured by the third process. The temperature inside the pre-chamber was raised from 1,050°C before the air injection to as high as 1,200°C after beginning the air injection. In contrast, when 0.3 t/h of water was injected into the injected air intermittently through a pipe equipped with a nozzle at a pressure of 0.5 kg/cm% the temperature inside the pre-chamber fell to 1,100°C. Air 25 was injected at a rate of 4,000 Nm3/h into gas discharge pipe 12 for the purpose of raising the discharged gas temperature by burning combustible components in gas 22 discharged from the quenching tower. The amount of recovered steam, which had been 100 t/h normally, was increased to 105 t/h by the air injection. This was further raised to 108 t/h by an addition of water into the pre-chamber and an injection of the ring duct injection air. The adequate flow rate and temperature of the gas fed to waste heat boiler 7 are 298,000 NmVh and 980°C, respectively. But the temperature was raised to 1,000°C or more by injection of air 25. Then, in order to control said flow rate and temperature to the respective adequate values, a portion of the inert gas fed from circulating blower 8 to cooling chamber 2 was led to branch pipe 19 and mixed with the hot gas discharged from ring duct 5 at - \^- a rate of approximately 10,000 Nm3/h. By this, the boiler feed gas temperature was successfully decreased to 980°C or lower. After operation by injection only air for a week keeping the pre-chamber inside temperature at approximately 1,200°C without injecting water or steam into the pre-chamber, a deposit about 100 mm thick accumulated at the lower part of the brick lining inner shell. After removing the deposit, operation was resumed with the pre-chamber inside temperature kept at 1,150°C or lower by intermittently injecting water in the form of mist into air. As a consequence, a good result was obtained, without deposit of clinker after a long period of operation. Example 2 Test operation to control the boiler feed gas temperature within the range 970° to 980°C was carried out using the same system as Example 1. The amount of air 24 injected into the pre-chamber was measured with a flow meter installed on a pipe of air injector 14. Another flow meter was installed on ring duct injection air pipe 15. Yet another flow meter was installed on branch pipe 19 for supplying inert gas 29. Also installed were: a control valve to regulate each of these flows; a processor to calculate and output an appropriate flow rate for each of the flows based on inputs of their actual flow rates, the boiler feed gas temperature, and percentage contents of hydrogen and carbon monoxide in the circulating gas; and a controller for each of the flow control valves. The operation of the coke ovens to supply red-hot coke fluctuated so much that the charging of coke was unstable. The boiler operated at a steam generation level of 90 t/h or so despite having a capacity of 110 t/h. Since coal carbonization at the coke ovens was insufficient, the amount of combustible gas components contained in the charged lump coke was high. Therefore, when 8,000 Nm3/h of air was injected into the pre-chamber, the boiler feed gas temperature began to rise and, as the hydrogen content in the circulating gas increased, the flow of ring duct air 25 began to increase and the brick temperature at the lower part of the pre-chamber rose to 1,200°C. Having detected this temperature, a processor outputted an instruction to increase the flow of inert gas 29 controlled the opening of the control valve installed on the branch pipe. This processor also has functions to control the amount of air 24 injected into the pre-chamber and the amount of water injected into the pre-chamber in the form of mist. Accordingly, during a period when charging of red-hot coke was interrupted for about 10 min., the air injection amount was increased for stabilizing the boiler feed gas temperature. The flow of ring duct injection air 25 was also increased. When red-hot coke was charged after the interruption, an instruction to reduce the amount of air 24 injected into the pre-chamber was outputted since the processor was programmed to reduce it when the internal pressure of the pre-chamber was negative. When the coke oven operation became stable and charging of red-hot coke became constant, the boiler feed gas temperature began to rise. However, since it is necessary to continuously maintain the amount of air injection into the pre-chamber in principle, the temperature inside the pre-chamber began to rise. Then, water injection into the pre-chamber was commenced and the reading of a thermometer at the lower part of the prick lining inner shell fell to approximately 1,100°C. Since the amount of combustible gas components in the circulating gas began to increase, however, the flow of the ring duct injection air began to increase under automatic control. This would result in a rise in the boiler feed gas temperature, but then the flow of inert gas 2 9 began to increase and, as a result, the boiler feed gas temperature could be controlled stably within a target temperature range. A method was also attempted wherein the flow of ring duct injection air 25 was set manually following the increase in the amount of hydrogen in the circulating gas, but the automatic control proved to be capable of more precise control. As described hereinbefore, the present invention, by injecting water or steam together with air into a pre-chamber of a coke dry quencher, from above, it is made possible to ensure the heat recovery amount of a waste heat boiler, while keeping the temperature inside the pre-chamber within an adequate range and preventing the deposit of clinker on the equipment. WE CLAIM :- 1. A method for dry quenching of coke wherein a quenching tower comprising a cooling chamber and a pre-chamber located above the cooling chamber, comprising the steps of, charging red-hot coke into the quenching tower from above, exchanging a sensible heat of said red-hot coke in the cooling chamber using inert gas as a heat exchange medium, recovering heat in the form of steam, characterized in that injecting one or both of water or steam with air by a controlled amount into the upper space of the pre-chamber so that the temperature inside the pre-chamber is kept at higher than a temperature of red-hot coke and lower than the predetermined temperature of 1150°C, burning components in a high temperature exhaust gas from the quenching tower by supplying air at a point before it reaches a waste heat boiler. 2. A method as claimed in claim 1, wherein the temperature of waste heat boiler feed gas is lowered to, or controlled within, a presciibed temperature range by supplying low temperature inert gas to the high temperature exhaust gas discharged from the quenching tower at a point before said exhaust gas reaches to the waste heat boiler. 3. A method as claimed in claim 2, wherein the low temperature inert gas is divided from the inert gas to be fed to the cooling chamber, 4. A method as claimed in claims 2 or 3, wherein the temperature of the waste heat boiler feed gas is controlled within a target range by controlling the injection amount of air and/or injection amount of water or steam into the pre-chamber and controlling the amount of low temperature inert gas added to the high temperature gas discharged form cooling chamber and the pre-chamber at a point before the high temperature gas reaches the waste heat boiler. 5. A method as claimed in any one of claims 1 to 4, wherein the water or steam is injected into pre-chamber through the nozzle of the air injector. 6. A method as claimed in any one of claims 1 to 5, wherein the water injection into the pre-chamber is done in the form of mist. 7. An apparatus for carrying out the method as claimed in claim 1, said apparatus comprising; a quenching tower composed of a cooling chamber where sensible heat of red-hot coke is transferred to inert gas and a pre-chamber located above the cooling chamber, a waste heat boiler for recovering the heat of the inert gas in the form of steam, a system composed of injector to inject air into said pre-chamber and another injector to inject water or steam into said pre-chamber, which both injectors being installed at the upper pai"t of said pre-chamber, an injection controller to control one or both of the injection amount of water or steam and the injection amount of air into the pre-chamber, a waste heat boiler connected to the exit side of the quenching tower, and an air injector, to supply air for burning components of the exhaust gas, installed in a high temperature gas exhaust route between the quenching tower and the waste heat boiler. 8. An apparatus a claimed in claim 7, comprising an inert gas supply equipment for supplying low temperature inert gas, to lower the temperature of waste heat boiler feed gas or to control said temperature within a prescribed range, installed in a high temperature gas exhaust route between the quenching tower and the waste heat boiler. 9. An apparatus as claimed in claim 8, wherein the inert gas supply equipment is an equipment to supply gas divided from the inert gas to be fed to the cooling chamber. 10. A method for dry quenching of coke substantially as herein described with reference to the accompanying drawings. 11. An apparatus for dry quenching coke substantially as herein described with reference to the accompanying drawings.

Documents:

847-del-2000-abstract.pdf

847-del-2000-claims(cancelled).pdf

847-del-2000-claims.pdf

847-del-2000-complete specification(granted).pdf

847-del-2000-correspondence-others.pdf

847-del-2000-correspondence-po.pdf

847-del-2000-description (complete).pdf

847-del-2000-drawings.pdf

847-del-2000-form-1.pdf

847-del-2000-form-13.pdf

847-del-2000-form-19.pdf

847-del-2000-form-2.pdf

847-del-2000-form-3.pdf

847-del-2000-form-5.pdf

847-del-2000-gpa.pdf

847-del-2000-petition-137.pdf