JP2011089001A - Method for producing molded coke - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing molded coke for efficiently performing prevention of ignition and dust explosion of heated raw materials, prevention in reduction of temperature, and heat insulation in production of molded coke (normal molded coke, ferro coke) using raw materials comprising powder coal containing volatile components. <P>SOLUTION: When raw material heater exhaust gas discharged from a raw material heater 5 is blown to raw materials heated by the raw material heater 5, the atmosphere of the raw materials is replaced by the raw material heater exhaust gas. In this way, prevention of ignition and dust explosion of the raw materials, prevention in reduction of temperature, and heat insulation are carried out. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing molded coke used in producing pig iron in a blast furnace.

  Molded coke is sometimes used when producing pig iron in a blast furnace. Molded coke is obtained by adding a binder (binder) to powdered coal that is a raw material, press molding, and dry-distilling the molded product (see, for example, Patent Document 1).

  Also, ferro-coke, which is a type of molded coke, may be used. Ferro-coke is obtained by adding a binder (binder) to a mixture of powdered coal and powdered iron ore as raw materials, press molding, and subjecting the molded product to dry distillation (see, for example, Patent Document 2). ).

  In addition, here, what uses pulverized coal as a raw material but does not use pulverized iron ore is called "ordinarily formed coke", and what uses pulverized coal and pulverized iron ore as raw materials is called "ferrocoke". To do. And “normally formed coke” and “ferro-coke” are collectively referred to as “molded coke”.

  Usually, the manufacturing process of molded coke (usually molded coke, ferro-coke) is kneaded in a heating process for heating a raw material containing powdered coal, a kneading process for kneading the raw material heated in the heating process, and a kneading process. A molding process for pressure-molding the raw material, and a carbonization process for obtaining molded coke by dry distillation of the molded product obtained in the molding process.

  FIG. 2 shows a typical ferro-coke manufacturing process.

  In FIG. 2, powdery coal and powdered iron ore as raw materials are quantitatively cut out from a coal supply hopper 1 and an iron ore supply hopper 2, respectively. The pulverized coal and the pulverized iron ore that are quantitatively cut are loaded on the raw material mixing conveyor 3 and conveyed to the next step.

  The raw material conveyed by the raw material mixing conveyor 3 is put into the raw material heating machine 5, and the adhering moisture content is less than a predetermined value (for example, 1% or less) by the hot air generated by the hot air furnace 4 and supplied by the hot air pipe 21. And the temperature at the outlet side of the raw material heater 5 is heated to a predetermined value (for example, 180 ° C.). The exhaust gas from the raw material heater 5 is discharged from the heater exhaust tower 6 via the heater exhaust gas pipe 22.

  The raw material heated by the raw material heating machine 5 is cut out from the double cutting device 7, passed through the vertical conveyor 8, the surge hopper 9, and the scale hopper 10, and put into the kneader 11, and a predetermined temperature (for example, 140 ° C.). ˜160 ° C.). At that time, for example, asphalt pitch (ASP) is added as a binder in the scale hopper 10, and soft pitch (SOP) is added as a binder in the kneader 11.

  The raw material kneaded by the kneading machine 11 is conveyed to the molding machine 13 via the supply hopper 12 and molded by the molding machine 13.

  The molded product molded by the molding machine 13 is transferred to the ferro-coke dry distillation furnace 15 via the ferro-coke dry distillation furnace loading conveyor 14, and is subjected to dry distillation in the ferro-coke dry distillation furnace 15 to produce ferro-coke. .

  The manufactured ferro-coke is discharged from the lower part of the ferro-coke dry distillation furnace 15 and conveyed by the ferro-coke discharge conveyor 16.

  In such a ferro-coke manufacturing process, the raw material is kneaded at a predetermined kneading temperature (for example, 140 ° C. to 160 ° C.) so that the raw material is well kneaded in the kneading machine 11, and the kneading temperature (for example, The raw material is heated to a predetermined heating temperature (for example, 180 ° C.) by the raw material heater 5 so that 140 to 160 ° C. can be obtained.

  However, this causes the following problems.

  That is, since the raw material contains pulverized coal having a volatile content, the raw material heated to a predetermined heating temperature (for example, 180 ° C.) by the raw material heater 5 may cause ignition or dust explosion if left as it is. There is sex.

  Moreover, even if the raw material is heated to a predetermined heating temperature (for example, 180 ° C.), if the subsequent temperature drop is large, a desired kneading temperature (for example, 140 ° C. to 160 ° C.) may not be obtained. If the desired kneading temperature cannot be obtained, the raw materials will not be kneaded well, and it will be difficult to produce high quality ferrocoke.

  In the above description, the case of producing ferro-coke has been described as an example, but the same applies to the case of producing ordinary molded coke.

  That is, the above-mentioned problem has always been a problem to be noted when producing molded coke.

  In general, the following measures are taken for these problems.

  In other words, in transporting pulverized coal having a volatile content, the oxygen concentration in the pulverized coal atmosphere is reduced by purging with an inert gas (mainly nitrogen gas) in order to prevent ignition and dust explosion. It is generally done. Incidentally, ignition and dust explosion of pulverized coal are unlikely to occur when the oxygen concentration in the atmosphere is below a predetermined value (for example, 10% or less).

  Moreover, not only powdered coal but the method of using a vapor | steam and an electrical heating apparatus is generally applied about the temperature fall prevention and heat retention of the heated substance.

Japanese Patent Application Laid-Open No. 07-252480 Japanese Patent Application Laid-Open No. 64-081889

  However, when producing molded coke (usually molded coke, ferro-coke) using raw materials containing pulverized coal with volatile content, the raw materials are used to prevent ignition and dust explosion of the heated raw materials. The method of purging the surrounding air with nitrogen gas to reduce the oxygen concentration around the raw material requires a nitrogen gas purging facility including a nitrogen gas storage facility, and involves a large capital investment.

  In addition, in order to prevent the temperature decrease of the heated raw material and to keep the temperature, the method using steam and electric heating equipment requires steam generation equipment and electric heating equipment, which involves a large capital investment.

  And when using valuable nitrogen gas, steam, and electric power, the running cost will increase.

  The present invention has been made in view of the circumstances as described above, and is heated when producing formed coke (usually formed coke, ferro-coke) using a raw material containing powdered coal having a volatile content. It is an object of the present invention to provide a method for producing molded coke that can efficiently ignite raw materials, prevent dust explosions, prevent temperature drop, and keep warm.

  In order to solve the above problems, the present invention has the following features.

[1] In a heating step of heating a raw material containing powdered coal, a kneading step of kneading the raw material heated in the heating step, a molding step of pressure-molding the raw material kneaded in the kneading step, and a molding step In a method for producing molded coke comprising a carbonization step of carbonizing the obtained molded product to obtain molded coke,
By supplying the exhaust gas discharged in the heating process as a purge gas into the atmosphere of the raw material from the heating process to at least the downstream molding process, the raw material is ignited, dust explosion is prevented, the temperature is reduced, and the temperature is kept low. A method for producing molded coke characterized by the above.

  [2] The heating temperature of the raw material in the heating step is adjusted so that the kneading temperature of the raw material in the kneading step is measured and the measured kneading temperature becomes a desired kneading temperature. A method for producing molded coke.

  [3] The temperature of the exhaust gas discharged in the heating process is measured, and when the measured temperature of the exhaust gas is out of the predetermined temperature range, the temperature of the exhaust gas is set within the predetermined temperature range. The method for producing molded coke according to [1] or [2], wherein the heating temperature of the raw material is adjusted.

  [4] Measure the oxygen concentration of the exhaust gas discharged in the heating step, and if the measured oxygen concentration of the exhaust gas exceeds a predetermined oxygen concentration, the oxygen concentration of the exhaust gas is equal to or lower than the predetermined oxygen concentration. The method for producing molded coke according to any one of [1] to [3], wherein nitrogen gas is injected into the exhaust gas and then supplied as a purge gas into the atmosphere of the raw material.

  [5] The method for producing molded coke according to any one of [1] to [4], wherein the molded coke is ferro-coke using powdered coal and powdered iron ore as raw materials.

  In the present invention, when producing molded coke (usually molded coke, ferro-coke) using a raw material containing powdered coal having a volatile content, exhaust gas discharged in the heating process is supplied to the atmosphere of the raw material. Therefore, ignition of the heated raw material, prevention of dust explosion, prevention of temperature decrease, and heat insulation can be performed efficiently.

  That is, since the exhaust gas discharged in the heating process has a low oxygen concentration in the gas (for example, 2 to 3%), the oxygen concentration in the raw material atmosphere is ignited by supplying the exhaust gas to the raw material atmosphere.・ It can be reduced to oxygen concentration (for example, 10% or less) where dust explosion is unlikely to occur, and the effect of preventing ignition and dust explosion of raw materials can be obtained, and the temperature of exhaust gas discharged in the heating process is heated Therefore, the sensible heat of the exhaust gas is effectively used, and the kneading temperature of the raw material in the kneading step is a desired kneading temperature (for example, 140 ° C. to 160 ° C.). ) So that the temperature of the raw material can be prevented from being lowered and the heat retaining effect can be obtained.

  Therefore, there is no need for nitrogen gas purge equipment, steam generation equipment, and electric heating equipment as in the case of using the prior art, and it can be done with low-cost equipment investment.

  Moreover, valuable nitrogen gas, steam, and electric power are not unnecessarily used as in the case of using the prior art, and can greatly contribute to reduction of running cost.

It is a figure which shows one Embodiment of this invention. It is a figure which shows the manufacturing process of ferro-coke.

  An embodiment of the present invention will be described with reference to the drawings. Here, the case where ferro-coke is produced as molded coke will be described as an example.

  FIG. 1 shows a ferro-coke manufacturing process in an embodiment of the present invention.

  In FIG. 1, as in the ferro-coke manufacturing process shown in FIG. 2, powder coal and powder iron ore as raw materials are quantitatively cut out from a coal supply hopper 1 and an iron ore supply hopper 2, respectively. . The pulverized coal and the pulverized iron ore that are quantitatively cut are loaded on the raw material mixing conveyor 3 and conveyed to the next step.

  The raw material conveyed by the raw material mixing conveyor 3 is put into the raw material heating machine 5, and the adhering moisture content is less than a predetermined value (for example, 1% or less) by the hot air generated by the hot air furnace 4 and supplied by the hot air pipe 21. And the temperature at the outlet side of the raw material heater 5 is heated to a predetermined value (for example, 180 ° C.). In addition, the exhaust gas (raw material heater exhaust gas) of the raw material heater 5 is discharged from the heater exhaust tower 6 via the heater exhaust gas pipe 22.

  The raw material heated by the raw material heater 5 is cut out from the double cutting device 7, passed through the vertical conveyor 8, the surge hopper 9, and the scale hopper 10, and put into the kneading machine 11, and a predetermined temperature (for example, 140 ° C.˜ 160 ° C.). At that time, for example, asphalt pitch (ASP) is added as a binder in the scale hopper 10, and soft pitch (SOP) is added as a binder in the kneader 11.

  The raw material kneaded by the kneading machine 11 is conveyed to the molding machine 13 via the supply hopper 12 and molded by the molding machine 13.

  The molded product molded by the molding machine 13 is transferred to the ferro-coke dry distillation furnace 15 via the ferro-coke dry distillation furnace loading conveyor 14, and is subjected to dry distillation in the ferro-coke dry distillation furnace 15 to produce ferro-coke. .

  The manufactured ferro-coke is discharged from the lower part of the ferro-coke dry distillation furnace 15 and conveyed by the ferro-coke discharge conveyor 16.

  In addition, in this embodiment, the heater exhaust gas supply pipe 25 branched from the heater exhaust gas pipe 22 includes a vertical conveyor 8, a surge hopper 9, a scale hopper 10, a kneader 11, and a supply hopper 12. And it is installed toward each of the molding machines 13.

  The heater exhaust gas supply pipe 25 is used to spray the raw material heater exhaust gas discharged from the raw material heater 5 onto the raw material between the vertical conveyor 8 and the molding machine 13. The raw material heater exhaust gas sprayed on the raw material is discharged via the heater exhaust gas discharge pipe 26.

  Since the raw material heater exhaust gas discharged from the raw material heater 5 has a low oxygen concentration (for example, 2 to 3%), the raw material heater exhaust gas is sprayed on the raw material as a purge gas to purge the air in the raw material atmosphere. By replacing the raw material atmosphere with the raw material heater exhaust gas, the oxygen concentration in the raw material atmosphere can be reduced to an oxygen concentration (for example, 10% or less) where ignition of the raw material and dust explosion are difficult to occur. Dust explosion prevention can be accurately achieved.

  Further, since the temperature of the raw material heater exhaust gas discharged from the raw material heater 5 is substantially the same as or higher than the temperature of the heated raw material (for example, 180 ° C.), the raw material heater exhaust gas is sprayed onto the raw material. Thus, by effectively utilizing the sensible heat of the exhaust gas from the raw material heater, the temperature reduction of the raw material is prevented and the temperature is kept so that the kneading temperature of the raw material in the kneading machine 11 becomes a desired kneading temperature (for example, 140 ° C to 160 ° C). Can be achieved appropriately.

  Further, in addition to the above, the kneading temperature of the raw material in the kneading machine 10 is measured by the thermometer 34, and the raw material heating machine 5 is adjusted so that the measured kneading temperature becomes a desired kneading temperature (for example, 140 ° C to 160 ° C). The heating temperature of the raw material (that is, the temperature of hot air generated in the hot air furnace 4) is adjusted. The heating temperature of the raw material is measured with a thermometer 31.

  Thereby, the raw material can be appropriately heated in the raw material heater 5. In other words, it is possible to prevent heating to an excessive temperature for obtaining a desired kneading temperature, or conversely, insufficient heating to prevent the desired kneading temperature from being obtained.

  Moreover, when the temperature of the raw material heater exhaust gas discharged from the raw material heater 5 is measured by the thermometer 32 and the measured temperature of the raw material heater exhaust gas is out of a predetermined temperature range (for example, 160 ° C. to 180 ° C.) Includes a heating temperature of the raw material in the raw material heater 5 (that is, a temperature of hot air generated in the hot air hot stove 4 so that the temperature of the raw material heater exhaust gas falls within a predetermined temperature range (for example, 160 ° C. to 180 ° C.). ) May be adjusted.

  As a result, for some reason, the temperature of the raw material heater exhaust gas becomes excessively high (eg, over 180 ° C.) to obtain a desired kneading temperature (eg, 140 ° C. to 160 ° C.). The kneading temperature (for example, 140 ° C. to 160 ° C.) is not sufficiently low (for example, less than 160 ° C.).

  Further, when the oxygen concentration of the raw material heater exhaust gas discharged from the raw material heater 5 is measured by the oxygen concentration meter 33, and the measured oxygen concentration of the raw material heater exhaust gas exceeds a predetermined oxygen concentration (for example, 10%) Uses a nitrogen gas supply pipe 27 attached to the heater exhaust gas supply pipe 25 so that the oxygen concentration of the raw material heater exhaust gas becomes a predetermined oxygen concentration (for example, 10%) or less. Gas may be injected.

  This prevents the oxygen concentration of the raw material heater exhaust gas from becoming high for some reason, making it impossible to reduce the oxygen concentration of the raw material atmosphere to an oxygen concentration (for example, 10% or less) where ignition of the raw material and dust explosion are difficult to occur. Is done.

Thus, in this embodiment, when manufacturing ferro-coke, the raw material heater exhaust gas discharged from the raw material heater 5 is sprayed on the raw material to prevent ignition of the heated raw material and dust explosion. Therefore, nitrogen gas purging equipment, steam generation equipment, and electric heating equipment are not required as in the case of using the conventional technology. Valuable nitrogen gas, steam, and electric power are not unnecessarily used, and can greatly contribute to reduction of running cost. Furthermore, since excessive heating of the raw material in the raw material heater 5 is prevented, it is possible to reduce the fuel consumption in the heater hot stove 4 and the CO ₂ emission amount.

  Therefore, in this embodiment, when manufacturing ferro-coke, it is possible to efficiently prevent ignition of the heated raw material, prevention of dust explosion, temperature reduction, and heat retention.

  In the above embodiment, the range in which the raw material heater exhaust gas is sprayed onto the raw material is from the vertical conveyor 8 to the molding machine 13, but is not limited thereto, and necessary ignition / dust explosion prevention is possible. What is necessary is just to select suitably the place which sprays raw material heater exhaust gas to a raw material so that an effect, temperature fall prevention, and a heat retention effect may be acquired.

  In the above embodiment, the raw material heater exhaust gas is sprayed on the raw material, and the atmosphere of the raw material is replaced with the raw material heater exhaust gas. By mixing it in the atmosphere, the atmospheric oxygen concentration may be reduced and the atmospheric temperature may be increased.

  And although said embodiment described as an example the case where the ferro-coke which uses powdered coal and powdered iron ore as a raw material was described as an example, the normal molding coke which does not use powdered iron ore using powdered coal as a raw material The same can be applied to the case of manufacturing.

DESCRIPTION OF SYMBOLS 1 Coal supply hopper 2 Iron ore supply hopper 3 Raw material mixing conveyor 4 Heater hot air furnace 5 Raw material heating machine 6 Heater exhaust tower 7 Double cutting device 8 Vertical conveyor 9 Surge hopper 10 Scale hopper 11 Kneading machine 12 Supply hopper 13 Molding Machine 14 Ferro-coke carbonization furnace charging conveyor 15 Ferro-coke carbonization furnace 16 Ferro-coke discharge conveyor 21 Hot air piping 22 Heater exhaust gas piping 25 Heater exhaust gas supply piping 26 Heater exhaust gas exhaust piping 27 Nitrogen gas supply piping 31 Thermometer 32 Thermometer 33 Oxygen concentration meter 34 Thermometer

Claims (5)

Obtained in a heating step of heating the raw material containing powdered coal, a kneading step of kneading the raw material heated in the heating step, a molding step of pressure-molding the raw material kneaded in the kneading step, and a molding step In a method for producing molded coke, comprising a carbonization step of carbonizing a molded product to obtain molded coke,
The exhaust gas discharged in the heating process is supplied as a purge gas into the atmosphere of the raw material from the heating process to at least the molding process downstream, thereby preventing ignition of the raw material, dust explosion, temperature reduction, and thermal insulation. A method for producing molded coke characterized by the above.   2. The molding coke according to claim 1, wherein the kneading temperature of the raw material in the kneading step is measured, and the heating temperature of the raw material in the heating step is adjusted so that the measured kneading temperature becomes a desired kneading temperature. Method.   When the temperature of the exhaust gas discharged in the heating process is measured and the measured temperature of the exhaust gas is out of the predetermined temperature range, the heating of the raw material in the heating process is performed so that the temperature of the exhaust gas is within the predetermined temperature range. The method for producing molded coke according to claim 1 or 2, wherein the temperature is adjusted.   When the oxygen concentration of the exhaust gas discharged in the heating process is measured, and the measured oxygen concentration of the exhaust gas exceeds a predetermined oxygen concentration, nitrogen is added to the exhaust gas so that the oxygen concentration of the exhaust gas is not more than the predetermined oxygen concentration. The method for producing molded coke according to any one of claims 1 to 3, wherein after the gas is injected, a purge gas is supplied into the atmosphere of the raw material.   The method for producing molded coke according to any one of claims 1 to 4, wherein the molded coke is ferro-coke using powdered coal and powdered iron ore as raw materials.

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