JP4074521B2 - Combustible gas recovery method during biomass processing in CDQ - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for recovering combustible gas during biomass treatment of wood, sewage sludge cake, and the like in a coke dry fire extinguishing facility (referred to as CDQ in this specification).
[0002]
[Prior art]
In CDQ, red hot coke is charged into the pre-chamber of the CDQ main body, lowered into the cooling chamber, and the inert gas, which is the cooling gas introduced from the lower part of the cooling chamber, is exchanged with red hot coke to recover the heat of the red hot coke. After the inert gas is introduced into the boiler via the annular duct and the flue to exchange heat, it is circulated by being pumped again to the cooling chamber by a circulation blower. Steam obtained by heat exchange in the boiler is sent to a generator and collected as electrical energy.
[0003]
As a method for treating biomass using CDQ, for example, Patent Document 1 discloses a method in which biomass (sewage sludge cake) is charged into a pre-chamber of a CDQ main body and pyrolyzed.
[0004]
The thermal decomposition treatment method disclosed in Patent Document 1 uses the sensible heat of red hot coke to thermally decompose the organic components of the sewage sludge cake in the pre-chamber, and the water and red hot coke in the sewage sludge cake are aqueous. A gasification reaction is performed and the gas is introduced into a flue as a combustible gas such as CO and H ₂ , and combustion air is introduced and burned in the flue.
[0005]
However, ash contained in biomass such as wood and sewage sludge cake contains more alkali metal components such as Na and K than coal ash, and has a low melting point and high adhesion. Therefore, when combustible gas containing biomass ash generated from biomass such as wood and sewage sludge cake is burned, the combustion temperature is limited (usually 900 ° C.) in order to avoid melting of biomass ash. In other words, when combustible gas containing biomass ash is burned at high temperatures, the biomass ash melts, causing stickiness and adverse effects on bricks due to adhesion to the furnace wall and troubles that adhere to the heat transfer tube surface of the boiler and reduce thermal efficiency. Arise. Therefore, combustion must be performed at a combustion temperature of about 900 ° C., and as a result, only low efficiency heat recovery can be performed.
[0006]
On the other hand, biomass such as wood containing a lot of combustible volatile matter, sewage sludge cake, etc. is pyrolyzed by CDQ, and as a method of using the combustible gas generated by pyrolysis, a large amount of combustible gas generated by pyrolysis is used. If it can be recovered as a fuel gas, it can be used for other purposes as a fuel or chemical raw material that substitutes for petroleum and LNG. Furthermore, if the biomass ash is removed after the combustible gas is recovered, high-temperature combustion is possible without causing ash melting problems, and highly efficient heat recovery is possible.
[0007]
For example, Patent Document 2 discloses a method for recovering the surplus cooling gas containing combustible gas in CDQ. However, CDQ described in Patent Document 2 does not process biomass. Since ash is contained in biomass as described above, special management such as thermal decomposition temperature is necessary.
[0008]
[Patent Document 1]
Japanese Patent No. 2789988 [0009]
[Patent Document 2]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-200237
[Problems to be solved by the invention]
The problem to be solved by the present invention is due to the combustion of combustible gas, which can only recover heat with low efficiency in effectively using the combustible gas generated by pyrolysis by thermally decomposing biomass such as wood and sewage sludge cake in CDQ. The object is to provide a method for recovering combustible gas that can be used for other purposes as a fuel or chemical raw material instead of petroleum / LNG.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the method for recovering combustible gas during biomass processing in CDQ according to the present invention introduces reddish coke into the cooling chamber of the CDQ main body, introduces the cooling gas from the cooling chamber lower portion, And the red hot coke are brought into contact with each other in the cooling chamber to raise the temperature of the cooling gas, and this heated gas is conveyed from the cooling chamber to the boiler via the annular duct and the flue to collect the heat of the heated gas and cool it. In the CDQ that is recirculated and reused as the cooling gas that is circulated again and introduced into the lower part of the cooling chamber, the biomass such as wood and sewage sludge cake is charged from the biomass charging port provided in the pre-chamber at the upper part of the cooling chamber, The biomass is pyrolyzed using sensible heat of red hot coke, and combustible gas generated by pyrolysis is used as the cooling gas, and surplus combustible gas is used as fuel gas. Upon recovering Te, the pre-chamber to a temperature suitable for the pyrolysis of biomass, is introduced a partial combustion air for burning a portion of the combustible gas produced by the pyrolysis of biomass in the pre-chamber, the The amount of air for partial combustion introduced into the pre-chamber is controlled by the pre-chamber temperature .
[0013]
Further, water and / or steam may be introduced into the prechamber. This water and / or steam is used for controlling the pre-chamber temperature and also has a function of causing a gasification reaction with biomass-fixed carbon and red hot coke to increase the amount of combustible gas produced.
[0014]
Further, air for adjusting the gas calorie of the fuel gas to be recovered may be introduced into the annular duct and / or the flue.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples shown in the drawings.
[0016]
Example 1
FIG. 1 is a configuration diagram of a CDQ that implements a combustible gas recovery method according to the present invention. In the CDQ, the red hot coke 1 is supplied from the coke charging inlet 3 at the upper part of the CDQ main body 2, the lid 3 a is opened, then the pre-chamber 4 is loaded and lowered into the cooling chamber 5, and supplied from the cooling gas pipe 14 at the lower portion of the cooling chamber 5. Heat is exchanged between the inert gas as the cooling gas and the red hot coke 1, and the high temperature inert gas recovered from the heat of the red hot coke 1 is introduced from the annular duct 6 into the boiler 13 via the flue 10 to exchange heat. After that, the circulation blower 15 is pumped and circulated to the lower part of the cooling chamber 5. The cooled coke is discharged from the coke discharge port 7 at the bottom of the CDQ main body 2.
[0017]
The pre-chamber 4 is provided with a biomass charging port 8 such as wood and sewage sludge cake and a partial combustion air inlet 9. Of the biomass, wood is roughly crushed to about 10 to 50 mm with a hammer crusher or the like (not shown) and is continuously charged from the biomass charging port 8. The flue 10 is provided with a collision wall 11 and a dust catcher 12 for collecting the dust separated by the collision wall 11. Further, a cyclone 16 for separating dust is provided in a pipe between the boiler 13 and the circulation blower 15. Further, a gas recovery pipe 17 for recovering surplus combustible gas (cooling gas) is provided on the outlet side of the circulation blower 15.
[0018]
In the CDQ having the above configuration, the biomass charged into the pre-chamber 4 is pyrolyzed by the sensible heat of the red hot coke 1 to generate a combustible gas such as CO and H ₂ . However, the latent heat of vaporization of the moisture contained in the biomass, the endotherm in the water gasification reaction between the evaporated water and the reddish coke 1 and the temperature rise sensible heat of the generated gas are deprived from the sensible heat of the reddish coke 1. The temperature of the pre-chamber 4 decreases.
[0019]
On the other hand, the composition of gas generated by pyrolysis of biomass such as wood and sewage sludge is determined by the pyrolysis temperature. When pyrolyzed at a low temperature of about 700 to 800 ° C., a liquid component such as tar is generated. The liquid component such as tar is a gas at a high temperature, but when the temperature is lowered to about 400 ° C., condensation occurs as a liquid. For this reason, when liquid components such as tar are generated, condensation occurs in the heat transfer tube or the like of the boiler 13 and becomes a factor of deteriorating thermal efficiency. When pyrolysis is further performed at a low temperature, the amount of flammable gas that is originally generated is reduced, and the solid is discharged from the coke discharge port 7 together with the coke or is collected as dust by the dust catcher 12 or the cyclone 16. Therefore, it cannot be used effectively.
[0020]
Therefore, in order to charge a large amount of biomass into the pre-chamber 4 of the CDQ main body 2 and cause thermal decomposition so as not to cause trouble with high efficiency, it is necessary to keep the temperature of the pre-chamber 4 constant. Moreover, the temperature fall of the pre-chamber 4 leads also to the fall of the amount of heat collect | recovered with the boiler 13, and reduces the amount of main steams. A decrease in the amount of main steam also leads to a decrease in power generation efficiency.
[0021]
Therefore, in the present invention, air is introduced into the pre-chamber 4 from the partial combustion air inlet 9. The introduced partial combustion air reacts and burns with a part of the combustible gas generated from the biomass, prevents the temperature of the pre-chamber 4 from decreasing, and makes the biomass highly efficient without generating liquid components such as tar. It is maintained at a temperature at which it can be pyrolyzed (about 900 ° C.). In addition, by not lowering the temperature of the pre-chamber 4, it is possible to avoid a decrease in the amount of heat collected by the boiler 13, so that power generation efficiency is not reduced.
[0022]
Further, the combustible gas generated in the pre-chamber 4 is introduced from the lower part of the cooling chamber 5 and mixed with the high-temperature coke cooling gas exchanged with the red hot coke 1, led from the annular duct 6 to the flue 10, and in the boiler 13. Heat exchange and cooling. The mixed gas of the coke cooling gas and the combustible gas cooled by the boiler 13 is pressurized by the circulation blower 15 and reintroduced into the cooling chamber 5 as the cooling gas for the red hot coke 1. This circulating use turns the coke cooling gas into a combustible gas, and the surplus combustible gas that is not necessary for red hot coke cooling is recovered from the gas recovery pipe 17 as a fuel gas, which can be used as a fuel or chemical raw material to replace petroleum and LNG. Effectively used for applications.
[0023]
Example 2
FIG. 2 is a configuration diagram of a CDQ that implements another combustible gas recovery method according to the present invention. The same components as those in the CDQ shown in FIG.
[0024]
In this embodiment, in order to keep the temperature of the pre-chamber 4 constant, the amount of partial combustion air introduced into the pre-chamber 4 is controlled by the temperature of the pre-chamber 4. Specifically, the partial combustion air introduction pipe is controlled by the controller 19 so that the temperature of the pre-chamber 4 measured by the temperature sensor 18 provided in the pre-chamber 4 becomes a predetermined temperature (about 900 ° C.). The degree of opening and closing of the flow rate adjustment valve 20 provided in is adjusted.
[0025]
Example 3
FIG. 3 is a block diagram of a CDQ that implements another combustible gas recovery method according to the present invention. The same components as those of the CDQ shown in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.
[0026]
In the second embodiment, the amount of partial combustion air introduced into the prechamber 4 is controlled in order to keep the temperature of the prechamber 4 constant. In this embodiment, the amount of partial combustion air varies. Instead, the temperature of the pre-chamber 4 is controlled by introducing water and / or steam from the water and / or steam inlet 21 provided in the pre-chamber 4. Specifically, the controller 22 introduces water and / or steam so that the temperature of the pre-chamber 4 measured by the temperature sensor 18 provided in the pre-chamber 4 becomes a predetermined temperature (about 900 ° C.). The degree of opening and closing of the flow rate adjusting valve 23 provided in the pipe is adjusted.
[0027]
According to the present embodiment, combustible gas (H ₂ , CO) is generated by water gasification reaction between water and / or steam introduced into the pre-chamber 4 and biomass-fixed carbon or red hot coke 1, and combustible gas is generated. Can be increased.
[0028]
Example 4
FIG. 4 is a configuration diagram of a CDQ for implementing another combustible gas recovery method according to the present invention. The same components as those in the CDQ shown in FIGS.
[0029]
In the present embodiment, an air inlet 24 is provided in the flue 10 and air for adjusting gas calories is introduced therefrom.
[0030]
When the biomass is pyrolyzed in the pre-chamber 4 to generate a combustible gas, the amount and composition of the gas generated by the pyrolysis varies depending on the temperature conditions of the pre-chamber 4 and the introduction of the red hot coke 1. Since it is easier to effectively use the gas recovered as fuel gas when it is controlled to a constant calorie, the calorie of the gas recovered as the fuel gas is made constant by burning the changed calorie content with the air introduced into the flue 10 I try to keep it. The calorie | heat amount for the fluctuation | variation calorie burned with air is converted into heat by combustion, is heat-recovered by the boiler 13, and is utilized effectively.
[0031]
The air amount is controlled by opening and closing the flow rate adjusting valve 27 provided in the air introduction pipe by the controller 26 so that the gas calorie measured by the gas calorimeter 25 provided on the outlet side of the cyclone 16 becomes a predetermined calorie. Do by adjusting the degree.
[0032]
In this embodiment, the gas calorie adjusting air is introduced into the flue 10, but it may be introduced from the annular duct 6 or from both the flue 10 and the annular duct 6. good.
[0033]
【The invention's effect】
According to the present invention, since the temperature of the pre-chamber becomes a temperature suitable for the thermal decomposition of biomass, the thermal decomposition of the biomass is performed efficiently, and the combustible gas can be reduced without causing troubles in equipment and a decrease in heat recovery efficiency. Recovery can be performed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a CDQ for carrying out a combustible gas recovery method according to the present invention.
FIG. 2 is a configuration diagram of a CDQ for carrying out another combustible gas recovery method according to the present invention.
FIG. 3 is a configuration diagram of a CDQ for carrying out another combustible gas recovery method according to the present invention.
FIG. 4 is a configuration diagram of a CDQ for carrying out another combustible gas recovery method according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Red hot coke 2 CDQ main body 3 Coke charge inlet 3a Coke charge inlet lid 4 Prechamber 5 Cooling room 6 Annular duct 7 Coke discharge 8 Biomass charge inlet 9 Partial combustion air inlet 9 Combustion air inlet 10 Flue 11 Collision wall 12 Dust catcher 13 Boiler 14 Cooling gas pipe 15 Circulating blower 16 Cyclone 17 Gas recovery pipe 18 Temperature sensor 19 Controller 20 Flow rate adjusting valve 21 Water and / or steam inlet 22 Controller 23 Flow rate adjusting valve 24 Air inlet 25 Gas calorimeter 26 Controller 27 Flow control valve

Claims (3)

Red hot coke is charged into the cooling chamber of the CDQ main body, cooling gas is introduced from the lower part of the cooling chamber, the cooling gas and red hot coke are brought into contact with each other in the cooling chamber, and the cooling gas is heated. In the CDQ, which is transported from the cooling chamber to the boiler via the annular duct and the flue, recovers the heat of the heated gas, becomes a cooling gas, and is recirculated and reused as the cooling gas introduced into the lower portion of the cooling chamber.
Combustibles produced by pyrolysis by charging biomass such as wood and sewage sludge cake from the biomass inlet installed in the pre-chamber at the top of the cooling chamber, and thermally decomposing this biomass using sensible heat of red hot coke. In using the gas as the cooling gas and recovering excess combustible gas as fuel gas,
In order to bring the pre-chamber to a temperature suitable for biomass pyrolysis, partial combustion air for burning a part of combustible gas generated by biomass pyrolysis is introduced into the pre-chamber and also introduced into the pre-chamber. A method for recovering combustible gas during biomass processing in CDQ , wherein the amount of air for partial combustion is controlled by pre-chamber temperature . The method for recovering combustible gas during biomass processing in CDQ according to claim 1, wherein water and / or steam is introduced into the pre-chamber. The method for recovering combustible gas during biomass processing in CDQ according to claim 1 or 2 , wherein air for adjusting the gas calorie of the fuel gas to be recovered is introduced into the annular duct and / or the flue.

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