JPH0250153B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for purging and removing soot from a regenerative gas heating furnace in an upright molded coke carbonization furnace of an upright heating type. (Prior art) For example, as a method for manufacturing shaped coke for metallurgy, lump coal is charged into a vertical carbonization furnace, and the lump coal is carbonized in the carbonization furnace using hot gas as a medium to obtain the desired shaped coke. It is known that (JP-A-52-23107
issue). This vertical carbonization furnace is provided with a low-temperature carbonization chamber and a high-temperature carbonization chamber from its upper part, and furthermore, a heating medium gas for carbonization is introduced into the carbonization furnace from an inlet provided in each of the chambers. The following method is already known for obtaining heat carrier gas for low-temperature carbonization. That is, the carbonization furnace top gas is introduced as a cooling gas from the lower part of the cooling chamber for thermoformed coke, which is directly connected to the high-temperature carbonization chamber, and is exchanged with the hot coke to be used as a heating medium gas for low-temperature carbonization. This method involves guiding the gas to the gas inlet (Japanese Patent Application Laid-Open No. 52-23102). In addition, in order to obtain heat carrier gas for high temperature carbonization,
Impact on product coke quality and recovered gas calorific value,
Considering that the heated gas temperature can reach 1000℃ or more, it was already discovered in another invention by the present inventors (Showa Disclosed in Japanese Patent Application No. 55-108927, filed on August 8, 1955, and Japanese Patent Application Laid-Open No. 1987-108928, "Purge method for regenerative gas heating furnace in vertical molded coke carbonization furnace" (1)(2)) In today's world, regenerative gas heating furnaces have already become commonplace in the steelmaking process as hot blast furnaces for blowing air into blast furnaces, but since the gas to be heated in hot blast furnaces for blast furnaces is air, it is possible to switch from the combustion period to the blowing period, or Conversely, when transitioning from the blowing period to the combustion period, there is basically no need to purge the atmosphere inside the regenerative furnace. Furthermore, since the gas to be heated is air and is thermally stable, there is no cause for clogging the duct. However, in the molded coke manufacturing process, the heated gas is a flammable gas with a composition relatively similar to that of normal coke oven gas and a hydrocarbon gas component concentration of 10 to 50 vol%, so there is no difference between the combustion period and the gas delivery period. , or vice versa, it is necessary to purge the atmosphere inside the regenerative furnace when transitioning from the gas supply period to the combustion period. Furthermore, in this process, in order to obtain sufficient quality of the product molded coke, the temperature of the heating medium gas for high-temperature carbonization, which is the gas to be heated, must be at 1000℃ or higher. It is thought that a large amount of soot is generated due to thermal decomposition of gas. According to experiments conducted by the present inventors on a regenerative furnace including a gas flow path, it was found that this soot has adhesive properties and has the property of clogging the gas flow path if continued operation for a long period of time. For this reason, when an actual carbonization furnace is operated for a long period of time, soot adheres to the tuyeres that supply heat transfer gas into the carbonization furnace, causing the gas volume balance between multiple tuyeres to collapse, and furthermore, If it adheres significantly to the flow path between the carbonization furnaces, there is a possibility that operations will not be able to continue. As a means for preventing this clogging phenomenon, air burning is known. Specifically, a method is disclosed in Japanese Patent Application No. 57-77743 in which a dehumidifier gas diluted with air is passed through a gas passage connecting the regenerator and the carbonization furnace once per switching cycle of the regenerator, after the combustion period. has been disclosed. As for the supply position of the removal gas, the
As exemplified in No. 77743, it is generally considered that a method of supplying from the low temperature end side of the regenerator is suitable. The first reason is that this position is upstream of the soot removal target gas flow path, and by supplying the soot removal gas from here, it is possible to reach the entire soot removal target section. The second reason is that since the soot removal gas is supplied via the regenerator, a drop in temperature of the duct can be prevented when the soot removal gas is supplied. (Problems to be Solved by the Invention) In an industrial-scale shaped coke carbonization furnace, a plurality of heating medium gas blowing tuyeres may be provided in order to make the gas flow uniform within the carbonization furnace. By the way, in the case of a plurality of tuyeres, it is difficult to uniformly remove the solvent from the plurality of tuyeres in the method of supplying the soot removal gas only from the low-temperature end side of the regenerative furnace for the following two reasons. First, the flow rate of the soot removal gas is set lower than the amount of heating medium gas for high-temperature carbonization to reduce the impact on the process. The point is that the distribution is not necessarily uniform. Second, the distribution characteristics of soot removal gas to each tuyere and the adhesion characteristics of soot do not necessarily match. The point is that it does not necessarily reach a larger amount. Therefore, in a carbonization furnace with multiple tuyeres, in order to ensure soot removal from each tuyere by supplying heat carrier gas only from the low-temperature end of the regenerator, it is necessary to remove soot from the tuyeres that are the most difficult to remove soot from. It is necessary to supply soot removal gas until completion. In this case, compared to the case where the soot removal gas is distributed to each tuyere to the minimum required level, extra soot removal gas will enter the carbonization furnace, and the oxygen in the extra soot removal gas will be mixed with the product coke. This reaction causes major problems that affect the essence of the molded coke process, such as lowering quality and product yield, and lowering the calorific value of the generated gas due to dilution. (Means for Solving the Problem) The present invention provides a method for preventing blockage of a gas flow path including a regenerator in a continuous molded coke process in order to solve the above-mentioned problems. In other words, the feature of the present invention is that, in order to remove the soot attached to the gas flow path connecting the regenerative furnace and the carbonization furnace within one switching cycle, the oxygen-containing gas is switched once after the combustion period of one cycle to the low temperature end of the regenerative furnace. It is divided into two parts: the side and the auxiliary gas duct corresponding to multiple tuyeres, and the gas is passed through the same flow path. Hereinafter, the content of the present invention will be explained according to the operation cycle of the regenerative furnace. After each combustion period a gas consisting of, for example, air or air diluted with _N2 or (and) water vapor, etc.
Soot removal gas containing oxygen is introduced from the low temperature side of the regenerator, and first the heated gas (combustion gas) remaining in the regenerator is purged out of the system. Next, while continuing to supply a part of the soot removal gas, this soot removal gas is guided to the carbonization furnace through the gas flow path between the regenerator and the carbonization furnace, and at the same time, the remaining soot removal gas is preliminarily supplied to each of the cylinders. After distributing the flow rate to the mouth and guiding it to each tuyere through an auxiliary gas duct corresponding to multiple tuyeres, the soot attached to the gas flow path is combusted with oxygen in the soot removal gas. and remove it. By the above method, it is possible to prevent the gas flow path from being clogged with soot while minimizing the impact on operation. (Function) Regarding the effects of the present invention, the following will be described: ・Soot removal gas type, ・Soot removal gas supply pattern, ・Soot removal gas supply position, and ・Soot removal gas supply timing. First, as a gas for removing soot adhering to the flow path, in consideration of the rapidity of the reaction, air is basically used to burn it off. however,
If it is necessary to prevent a rapid temperature rise on the duct surface due to the soot combustion reaction, it is also possible to use diluted air or combustion exhaust gas combusted at an air ratio higher than the theoretical air amount as the soot removal gas. be.
It is a nonflammable gas that is easy to obtain as a diluent gas.
_N2 or (and) steam are optimal. Next, the pattern for supplying soot removal gas is as follows:
There are two ways: (1) Soot removal method every time...Soot that adheres during one gas supply period is removed once per cycle. (2) Intensive soot removal method: Once during multiple gas supply periods, the soot that has adhered up to that point is removed. Next, based on data from experiments conducted by the present inventors, we will show the results of comparing the characteristics of both systems, with the total amount of oxygen required for soot removal being constant. 1 gas supply period is 30 minutes,
Assuming that the O ₂ concentration in the soot removal gas is 11%, with the soot removal method each time, under certain operating conditions, if the soot removal time required to remove soot in one gas supply period is 2 minutes, the soot removal time will be 2 minutes. The amount of soot gas is usually 20% of the amount of gas fed.
On the other hand, in a concentrated soot removal method using the same concentration of soot removal gas under the same operating conditions, when removing one day's worth of soot, the amount of soot removal gas is 60% of the normal gas supply amount.
Assuming that the total amount of oxygen required for soot removal is constant for each method, the required soot removal time: t [min/D] is 0.2V [Nm ³ /H] x (2/60) [ ^H/ times] x 24 [H/
D] x 60 [min/H] / 30 [min/times] x 0.11 = 0.6V [Nm ³ /H] x (t/60) [ ^H/D ] x 0.11 t = 0.2 x 2 x 24 x 60/ 0.6×30=32 [min/D] (where V: normal gas supply amount), which can be seen from the fact that it takes one gas supply period for soot removal per day of operation. However, the reason why the soot removal gas amount is set to 60% of the normal gas amount in the concentrated soot removal method is that in the case of _N2 dilution,
In order to prevent the amount of recovered gas from increasing by supplying soot removal gas and continuously exceeding the processing capacity limit of the gas processing equipment, and in the case of steam dilution,
This is because in order to suppress solution loss in the carbonization furnace, the operating rate must be at least 60% within the operable range in all cases. Table 1 shows the results of a comparative study of both methods, including the above-mentioned experimental results. As can be seen from Table 1, the every-time method has less impact on operational stability and product quality than the centralized method. This is due to the effect of temporally dispersing various influences, and in this sense, the most suitable soot removal method is the every-time method, which disperses the influences the most.

[Table] * The impact time is short. Next, we will discuss the reason why the soot removal gas supply location is divided into the low temperature end side of the regenerator and the auxiliary gas duct corresponding to multiple tuyeres. By introducing a part of the soot removal gas from the low temperature end side of the regenerator, soot is removed from the regenerator to the branch point to the multiple tuyeres in the gas flow path. At the same time, by introducing soot removal gas into the auxiliary gas duct for multiple tuyeres, that is, immediately downstream of the branch point to the branch point to the multiple tuyeres, with the flow rate distributed in advance to correspond to each tuyere, Remove soot from each tuyere. Here, if the distribution ratio of the soot removal gas flow rate to each tuyere is adjusted to the adhesion characteristics of soot to each tuyere, the amount of soot removal gas supplied to the carbonization system can be suppressed to the minimum necessary source. In addition, there are two possible timings for medium removal within one cycle: after the gas feeding period and after the combustion period. is suitable because residual elements are consumed and it is not efficient. Furthermore, after the combustion gas filling the regenerator is purged with soot removal gas immediately after the combustion period, the outlet gas of the regenerator is guided to the gas flow path leading to the carbonization furnace, so that the regenerator is filled immediately after the purging. Since the soot removal gas that is currently available can be used for soot removal, the time required for soot removal can be reduced. Therefore, it is best to remove soot after the combustion period. The amount of soot removal gas supplied per cycle is determined based on the O ₂ concentration in the soot removal gas and the amount of attached soot. Next, the method according to the present invention will be explained using a molded coke carbonization facility consisting of two regenerator furnaces and one combustion furnace as an example.
This will be explained in detail using drawings. Here, a case will be described in which air dilution gas is used as the soot removal gas. In Fig. 1, lump coal 1 is first charged into the furnace from the top of an upright carbonization furnace 5, which consists of a low-temperature carbonization chamber 2, a high-temperature carbonization chamber 3, and a cooling chamber 4, and is then lowered through the furnace. The coke is carbonized by the heating medium gas introduced from the tuyeres 6 and 7, and further cooled by the cooling gas introduced from the cooling gas inlet 8 and discharged from the cooling gas outlet 9 to form molded coke 10. It is discharged from the bottom of the carbonization furnace. On the other hand, the gas released from the top of the furnace is directly transferred to the cooler 11.
The gas is then cooled by an indirect cooler 12, and pressurized by a circulation blower 13. A part of the gas is guided outside the system as a recovery gas 34, and the rest is circulated within the system as a circulation gas. A part of the circulating gas is heated in the first heat storage chamber 17 or the second heat storage chamber 24 and introduced into the high temperature carbonization chamber 3 from the high temperature carbonization chamber heating medium gas supply port 7 .
A plurality of tuyeres 6, 7, 8 and discharge ports 9 for supplying gas to the carbonization furnace may be provided in order to make the gas flow uniform in the carbonization furnace. Here, only the high-temperature carbonization chamber heating medium gas supply tuyere 7 used for explanation is shown as a plurality in FIG. 1. Next, the gas flow in the full change cycle will be explained using diagrams. (1) Combustion period [Fig. 2a] Combustion gas generated by combustion of fuel 14 and combustion air 15 in the combustion furnace 16 for heating the regenerative furnace is introduced into the first regenerator 17 from the combustion gas inlet valve 18 and the internal After heating the Tietzker brick,
The combustion gas is discharged from the outlet valve 21 and diffused out of the system through the chimney 33. (2) Purge period after the end of the combustion period [Fig. 2b] The soot removal gas obtained by mixing N ₂ or steam supplied from the valve 31 and air supplied from the valve 32 is sent from the valve 23 to the first heat storage Introduced into room 17,
Purge gas outlet valve 20 for residual combustion gas in the heat storage chamber
Purge to chimney 33 via. (3) Desolvation period [Fig. 2c] A part of the soot-removed gas obtained in the same manner as in (2) is subsequently introduced into the first heat storage chamber 17, and the heated soot-removed gas is passed through the circulating gas outlet valve 19. , main gas duct 7
_-2 , auxiliary gas duct 7 _-1 , high-temperature carbonization chamber heating medium gas supply tuyere 7 to be introduced into the carbonization furnace, and at the same time, duct section soot removal gas inlet pipe 35 via duct section soot removal gas cutoff valve 36 , by introducing soot removal gas from auxiliary gas duct _7-1 , valve 1
Soot adhering to the gas flow path between 9 and tuyere 7 is removed. (4) Purge period after soot removal [Fig. 2 d] The air supply valve 32 is closed, and the N ₂ or water vapor continuously supplied from the valve 31 is supplied from the valve 23 to the first
By introducing the residual soot removal gas into the heat storage chamber 17, the residual soot removal gas is purged from the heat storage chamber via the circulating gas outlet valve 19. (5) Gas feeding period [Fig. 2 e, f] The circulating gas introduced from the circulating gas inlet valve 22 and heated by the Tietzker brick in the first heat storage chamber 17 is passed through the circulating gas outlet valve 19 to the high-temperature carbonization chamber heating medium gas. It is introduced into the carbonization furnace via the supply tuyere 7. (6) Purge period after gas supply [Fig. 2 b to e] In the second heat storage chamber 24, the circulating gas inlet valve 2
9. Close the circulating gas outlet valve 26 and temporarily interrupt the gas supply. (Fig. 2 b to d) Next, after the removal of the medium from the first heat storage chamber 17, N ₂ is supplied via the valves 31 and 30.
Alternatively, water vapor is introduced into the second heat storage chamber 24, and the residual circulating gas in the heat storage chamber is purged into the high temperature carbonization chamber 3 via the circulation gas outlet valve 26 and the high temperature carbonization chamber heating medium gas supply tuyere 7 (see Fig. 2e). ). Although the above explanation relates to the case where the number of regenerators is two, the essence of the explanation is the same for a gas heating furnace configured with three or more regenerators. Furthermore, if the amount of soot adhesion is small depending on operating conditions, the frequency of supplying oxygen-containing gas can be reduced to once per cycle or less (for example, once every 2 to 5 cycles), but such an operating method is also within the scope of the present invention. It's not something that deviates from. Furthermore, if it is possible due to the pressure balance, the combustion exhaust gas can be introduced from the regenerative furnace to the carbonization furnace as soot removal gas by adjusting the air ratio before the combustion period. . (Example) An operational test example will be shown in a molded coke carbonization furnace with a coke production rate of 200 t/d and carbonization furnace cross-sectional dimensions of width: 1250 mm and length 6450 mm. A part of the generated gas discharged from the top of the furnace is circulated and heated in a regenerative gas heating furnace.
It is heated to approximately 1100℃ and introduced into the carbonization furnace through 12 tuyeres as a heat carrier gas. The soot removal gas was supplied to the gas flow path after the combustion phase of the regenerative furnace switching cycle. Soot removal time is 4 minutes, regenerator switching cycle is 80
It was hot in minutes. Total soot removal gas flow rate is 1600Nm ³ /h (O ₂
(concentration: 11%), 80% of which was introduced from the low temperature end of the regenerator, and the remainder was divided into 12 parts and introduced into the gas supply pipes to each tuyere. As a result of approximately two months of operational tests, there was no accumulation of soot in the gas duct or all tuyeres, and the soot removal effect was sufficient. The furnace top gas composition is
_H2 : 55-65%, _CH4 : 10-20%, _CO2 : 1-3
%, CO: 10-20%, _N2 : 5-15% (vol%). Reference Example The soot removal gas flow rate was 1800 Nm ³ /h, all of which was introduced from the low temperature end of the regenerator, and other conditions were the same as in the example. As a result of about a month's operation test, the tuyere
Two of the 12 pipes were almost blocked due to soot. (Effects of the Invention) As described above, according to the present invention, it is possible to obtain a molded coke carbonization system that reliably prevents clogging of gas flow paths with soot while minimizing the effects on carbonization furnace operation stability and product quality. , and its practical value is extremely high.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a vertical molded coke carbonization furnace gas circulation system using the purging and clogging prevention method according to the present invention, Fig. 2 a, b, c, d, e, f
3 is a diagram showing the gas flow within one switching cycle, and FIG. 3 is a diagram showing the time schedule for opening and closing the valves around the regenerative furnace. 1: Lump coal, 2: Low-temperature carbonization chamber, 3: High-temperature carbonization chamber, 4: Cooling chamber, 5: Upright carbonization furnace, 6: Low-temperature carbonization chamber heating medium gas supply tuyere, 7: High-temperature carbonization chamber heating medium gas supply Tuyere, 8: Cooling gas inlet, 9: Cooling gas outlet, 10: Molded coke, 11: Direct gas cooler, 12: Indirect gas cooler, 13: Circulation blower, 14: Regenerator heating fuel, 15: Heat storage Combustion air for room heating, 16: Regenerator heating furnace, 17:
1st heat storage chamber, 18: 1st heat storage chamber combustion gas inlet valve,
19: First regenerator circulating gas outlet valve, 20: First regenerator purge gas outlet valve, 21: First regenerator combustion gas outlet valve, 22: First regenerator circulating gas inlet valve, 2
3: First heat storage chamber purge gas inlet valve, 24: Second heat storage chamber, 25: Second heat storage chamber combustion gas inlet valve, 26:
2nd regenerator circulating gas outlet valve, 27: 2nd regenerator purge gas outlet valve, 28: 2nd regenerator combustion gas outlet valve, 29: 2nd regenerator circulating gas inlet valve, 30: 2nd regenerator purge gas inlet valve , 31: N ₂ or steam cutoff valve, 32: Air cutoff valve, 33: Chimney, 3
4: Recovery gas, 35: Duct section soot removal gas introduction pipe,
36: Duct section soot removal gas cutoff valve.

Claims (1)

[Claims] 1. A part of the generated gas discharged from the top of the upright continuous carbonization furnace is circulated, heated in a regenerative gas heating furnace, and returned to the plurality of high-temperature carbonization chamber heat medium gas supply vanes as heat medium gas for carbonization. In a method of producing molded coke by carbonizing agglomerated coal by feeding it into a carbonization furnace through the mouth, after the combustion period of the switching cycle of the regenerative gas heating furnace, part of the oxygen-containing gas is transferred to the low temperature end of the heating furnace. gas flow path of a regenerative gas heating furnace in a molded coke carbonization furnace, characterized in that the remaining soot removal gas is supplied from the duct section to the auxiliary gas duct corresponding to the plurality of tuyeres. Soot method.