JP2006070171A - Method of fluidized bed type gasification and device for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve and stabilize the gasification efficiency of a treated material. <P>SOLUTION: In a method of fluidized bed type gasification, forming combustible gas by heating the treated material supplied to a gasification oven 3 and also fluidizing it with fluidizing gas and taking out a part of the combustible gas and returning to the gasification oven 3 as the fluidizing gas, the part of the combustible gas is burned with an oxygen-rich gas and heated to a set temperature before the combustible gas is returned to the gasification over 3. Thereby, since the ignition of the fluidized gas is inhibited in a supplying piping and the fluidized gas having a high heat value is supplied stably, it is possible to maintain a high gasification efficiency. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fluidized bed gasification method and apparatus for fluidizing and gasifying waste.

  A waste gasification system that uses municipal combustible waste as a fuel by injecting it into a gasification furnace, blowing it into a fluidized bed, fluidizing it, heating it, and heating it. It has been.

  In this gasification system, waste is partially combusted with air, heated to a high temperature (for example, 600 to 900 ° C.) and pyrolyzed, and the combustible gas and char generated by the pyrolysis are separated into a dust collector, It is cooled and removed through a heat exchanger, a gas cooling tower, etc., and stored in a storage tank for use as fuel gas. Here, the char collected by the dust collector is further returned to the gasification furnace for gasification. On the other hand, coarse incombustibles contained in the waste are deposited at the bottom of the fluidized bed and discharged out of the furnace through the piping.

  By the way, for example, in low-calorie waste containing incombustible foreign substances such as biomass and high-moisture sludge, the temperature inside the furnace is not raised to the temperature required for reaction during combustion, and the gasification efficiency is low. Recycling applications are limited. In particular, when air is used as the fluidizing gas in the fluidized bed, nitrogen, which occupies about 80% of the air, is supplied to the gasification furnace as an inert gas, and the heating capacity of waste in the furnace is reduced. For this reason, for example, if the amount of water in the waste increases, the temperature in the furnace may be insufficient, and gasification efficiency may be reduced. Further, since nitrogen is stored in the storage tank together with the combustible gas, the tank capacity is increased, and the concentration of combustible components that are fuel and chemical raw materials is reduced, resulting in poor storage efficiency.

  Thus, attempts have been made to use oxygen-rich gas instead of air as fluidizing gas. However, if oxygen-rich gas is blown directly into the fluidized bed, not only a large amount of oxygen-rich gas is required for fluidization, but the inside of the furnace may be locally heated, so it is discharged from the gasification furnace. A technique is disclosed in which a part of a combustible gas is blown into a furnace together with oxygen or separately (see Patent Document 1). According to this, since the calorific value of fluidization gas is adjusted by adjusting the flow rate ratio of combustible gas and air suitably, local high temperature can be controlled.

JP 2000-18531 A (page 3)

  However, as described in Patent Document 1, for example, when a waste gas is burned by blowing a mixed gas of a combustible gas and an oxygen-rich gas into a furnace through an air diffuser, due to the influence of the gas flow rate, the furnace temperature, and the like. Otherwise, ignition may occur in the supply pipe, and abnormal combustion may occur. In this case, there is a problem that the furnace temperature becomes unstable and the gasification of waste becomes unstable.

  An object of the present invention is to improve and stabilize the gasification efficiency of the object to be processed.

  In order to solve the above-mentioned problem, the present invention heats the workpiece supplied to the gasification furnace, fluidizes it with a fluidizing gas to generate a combustible gas, and extracts a part of the combustible gas to flow. In the fluidized bed type gasification method for returning to the gasification furnace as the gasification gas, before returning the combustible gas to the gasification furnace, a part of the combustible gas is burned with an oxygen-rich gas and heated to a set temperature. To do.

  That is, by partially burning the combustible gas with the oxygen-rich gas, the added oxygen is not consumed by the combustion of the combustible gas, and is supplied to the gasifier while being heated to the set temperature. Moreover, since the inert gas in oxygen rich gas is few, the fall of the emitted-heat amount of the fluidization gas by an inert gas is suppressed. Thereby, since the ignition of the fluidized gas in the supply pipe is suppressed, the fluidized gas having a high calorific value is stably supplied, and the gasification efficiency of the workpiece can be maintained high.

  In this case, the combustible gas burned with the oxygen-rich gas is preferably supplied after being cooled to a set temperature that does not exceed the heat resistance temperature of the fluidizing gas supply system, for example. Thereby, the local temperature rise in a fluidized bed can be suppressed.

  In addition, the fluidized bed type gasifier of the present invention heats an object to be processed and fluidizes the fluidized gas to generate a combustible gas, and supplies the fluidized gas to the gasifier. Gas supply means, and the gas supply means guides a part of the combustible gas discharged from the gasification furnace to the partial combustor, partially burns it with oxygen-rich gas, and heats the heated combustible gas. Is supplied as a fluidizing gas to a gasification furnace.

  In this case, the gas supply means has a heat exchanger that adjusts the temperature of the combustible gas between the partial combustor and the gasifier, and cools the partially combustible combustible gas to a set temperature by heat exchange. It is preferable. Further, the gas supply means may detect the temperature of the combustible gas discharged from the partial combustor and control the supply amount of the oxygen-rich gas used for the partial combustion based on the detected value.

  On the other hand, it is preferable to supply oxygen-rich gas to the empty space of the gasifier. By supplying a set amount of oxygen to the empty tower and maintaining the temperature of the empty tower at a set temperature (for example, 800 to 1100 ° C.), the gasification efficiency of the object to be processed can be maintained higher. Here, it is preferable to detect the temperature of the empty tower and control the supply amount of the oxygen-rich gas supplied to the empty tower based on the detected value. That is, when the temperature of the empty tower is lower than the set temperature, the supply amount of oxygen-rich gas is increased, and when it is higher than the set temperature, the supply amount of oxygen-rich gas is controlled to decrease.

  According to the present invention, the gasification efficiency of the workpiece can be improved and stabilized.

(First embodiment)
Hereinafter, a first embodiment of a fluidized bed gasifier to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a system diagram of a fluidized bed gasification system to which the present invention is applied.

  As shown in FIG. 1, the fluidized bed type gasification system of the present embodiment includes a partial combustor 1, a gasification furnace 3, a dust collector 5, a heat exchanger 7, an air heater 9, and a gas quenching tower. 11, a dust collector 13, a storage tank 15, and an oxygen generator 17.

  In the gasification furnace 3, a feeder 21 for supplying waste is connected to a side surface of a substantially central height of a vertically formed container via a supply chute 22, and fluidized below a connection port of the supply chute 22. A diffuser tube 23 for blowing gas is provided extending in the horizontal direction. The air diffuser 23 blows a fluidizing gas into the fluidized bed 25 to fluidize the fluidized bed 25 using, for example, sand having a particle size of about 1 mm as a medium. The lower part of the container is formed with a narrowed cross section so that, for example, non-combustible foreign matter deposited on the bottom of the fluidized bed 25 can be separated and discharged out of the furnace through a pipe. An activation burner 27 is provided on the side surface of the container at a substantially central height. An empty tower 31 is formed in the upper space of the vessel above the activation burner 27, and an oxygen supply line 33 is connected to this space. A gas discharge line 35 is connected to the top of the container.

  A detection end of a temperature detector 29 is disposed in the fluidized bed 25, and when the detected temperature of the fluidized bed 25 detected by the temperature detector 29 is input to the controller 37, supply is made based on this detected temperature. A command is output to the machine 21 to control the amount of waste supplied. Further, a detection end of a temperature detector 39 is disposed in the empty tower section 31. When the detected temperature of the empty tower section 31 detected by the temperature detector 39 is input to the controller 41, the detected temperature Based on the above, a command is output to the control valve 43 attached to the oxygen supply line 33, the valve opening is adjusted, and the oxygen supply amount is controlled.

  The gas discharge line 35 of the gasification furnace 3 is connected to the entrance side of the dust collector 5 where char accompanying the combustible gas is collected. The char collected by the dust collector 5 is supplied into the gasification furnace 3 via a pipe and is recirculated. The exit side of the dust collector 5 is connected to the entrance side of the heat exchanger 7 through a pipe, and the combustible gas is cooled by heat exchange. The outlet side of the heat exchanger 7 is connected to the inlet side of the air heater 9, and the combustible gas is cooled by exchanging heat with oxygen supplied into the gasification furnace 3 as a fluidizing gas. Next, the exit side of the air heater 9 is connected to the entrance side of the gas quenching tower 11, and the exit side of the gas quenching tower 11 is connected to the entrance side of the dust collector 13, and the combustible gas is passed through each device. Sequentially cooled. The gas that has passed through the dust collector 13 is stored in the storage tank 15 via the induction fan 14.

  The oxygen generation device 17 is connected to the heat transfer tube entrance side of the air heater 9 through a pipe provided with the induction blower 45, where the oxygen rich gas flowing through the heat transfer tube is heated by exchanging heat with the high-temperature combustible gas flowing in the air heater 9. Is done. The heat transfer tube outlet side of the air heater 9 is connected to an oxygen supply line 47. The oxygen supply line 47 is connected to the inlet side of the partial combustor 1, while branching to the oxygen supply line 33 from the middle and gasifying furnace. 3 empty towers 31. On the other hand, the piping on the downstream side of the induction blower 14 branches to the gas supply line 50 provided with the induction blower 49 and is connected to the entry side of the partial combustor 1.

  In the partial combustor 1, a mixed gas of oxygen-rich gas and combustible gas is ejected and ignited by the igniter 51, and the high-temperature combustible gas after partial combustion is supplied to the diffuser pipe 23 as a fluidized gas. It has become. The exit side of the partial combustor 1 is connected to the entry side of the diffuser tube 23 via the heat exchanger 53. Here, the detection end of the temperature detector 55 is disposed in the piping on the outlet side of the heat exchanger 53, and the detected temperature of the combustible gas discharged from the heat exchanger 53 is input to the controller 57. Based on the detected temperature, an output command is issued to the control valve 59 attached to the oxygen supply line 47 to adjust the opening, and the supply amount of oxygen rich gas supplied to the partial combustor 1 is controlled. .

  A pipe 61 having a valve 63 and a pipe 67 having a valve 65 by branching the oxygen supply line 47 are connected to the activation burner 27. The pipe 61 takes air into the furnace from the atmosphere. The system takes in oxygen from the oxygen generator 17. The valve 63 and the valve 65 are linked to each other.

  In addition, as the waste to be treated in the present embodiment, for example, low-calorie waste having incombustible foreign matters such as biomass and high moisture sludge is preferably used, but is not limited to this, for example, municipal waste It may be waste.

  Next, the operation of this embodiment will be described. The waste is introduced into the fluidized bed 25 from the feeder 21 through the supply chute 22, and the fluidized gas is supplied to the fluidized bed 25. The fluidizing gas is preheated in the partial combustor 1 and is blown into the fluidized bed 25 from the diffuser pipe 23 while being adjusted to the set temperature by the heat exchanger 53. The waste is heated in the fluidized bed 25 and thermally decomposed to generate combustible gas and char. The combustible gas rises in the furnace accompanied by char, and the gasification reaction is further promoted in the empty space 31 on the way.

  On the other hand, coarse incombustibles or the like normally contained in the waste are gradually deposited on the bottom as the fluidized bed 25 flows, and are discharged out of the furnace through the piping.

  The combustible gas discharged from the top of the gasification furnace 3 is introduced into the dust collector 5 through the gas discharge line 35 and removed, and the separated char is put into the gasification furnace 3 through the pipe. It is returned and gasified. The combustible gas that has passed through the dust collector 5 sequentially passes through the heat exchanger 7, the air heater 9, and the gas quenching tower 11 and is cooled to a predetermined temperature, and is then introduced into the dust collector 13 and removed. The combustible gas that has passed through the dust collector 13 is sent to the storage tank 15 as product gas by the induction blower 14.

  Next, the operation relating to the in-furnace supply of fluidized gas will be described in detail. First, the oxygen rich gas (including pure oxygen gas) produced by the oxygen generator 17 is pressurized by the blower 45 and supplied to the partial combustor 1 through the air heater 9 and the pipe 47. On the other hand, the extracted combustible gas is boosted by the circulation blower 49 through the pipe 50 branched from the discharge side pipe of the induction blower 14, supplied to the partial combustor 1 and circulated. In the partial combustor 1, a mixed flame of oxygen rich gas and combustible gas is ignited by the igniter 51, and a stable flame is formed. The partial combustor 1 is in an oxygen-deficient state.

  The high-temperature combustible gas generated in the partial combustor 1 is cooled to a set temperature through the heat exchanger 53 and then ejected from the diffuser pipe 23 into the fluidized bed 23 as a fluidized gas to fluidize the fluidized bed 23. . Thereby, the waste material supplied from the supply chute 22 is fluidized and heated to be gasified.

  Here, the temperature of the fluidized gas discharged from the heat exchanger 53 is detected by the temperature detector 55, and the detected temperature does not exceed the heat resistance temperature (for example, about 800 ° C.) of the air diffuser 23, for example. Then, the opening degree of the control valve 59 is adjusted via the controller 57 to control the supply amount of the oxygen-rich gas supplied to the partial combustor 1.

  Thus, by partially burning the combustible gas with the oxygen-rich gas, the oxygen supplied to the partial combustor 1 is not consumed for combustion, and the combustible gas heated to the set temperature is fluidized gas. Is supplied to the gasification furnace 3. Moreover, since the inert gas in oxygen rich gas is few and the inert gas in fluidization gas is fully reduced, the calorific value fall of fluidization gas is suppressed and storage efficiency improves. That is, in the supply pipe including the diffuser pipe 23, the ignition of the fluidized gas is suppressed, and the fluidized gas having a high calorific value can be stably supplied. Therefore, the waste gasification efficiency can be maintained high. Moreover, according to this embodiment, the low calorie waste containing incombustible foreign materials, such as biomass and a high moisture sludge, can be efficiently gasified.

  Furthermore, in order to avoid a melt adhesion trouble, the following control is performed so that the temperature of the fluidized bed 25 does not exceed 900 ° C., for example. That is, if the temperature of the fluidized bed 25 is detected by the temperature detector 29 and this temperature is too high, the amount of waste supplied is increased via the controller 37 to lower the bed temperature. If the layer temperature is too low, the layer temperature can be maintained within an appropriate range by performing an operation to reduce the amount of waste supplied. Thus, for example, when it is assumed that non-combustible foreign matter having low heat resistance such as an aluminum can is recovered, it is preferable to control the temperature so that the temperature of the fluidized bed 25 is operated at about 600 ° C.

  On the other hand, in the gasification furnace 3, in order to promote the gasification reaction, it is preferable to maintain the empty column 31 at a set temperature (for example, about 800 to 1100 ° C.). For this reason, in this embodiment, the oxygen supply line 47 is branched, a part of the oxygen rich gas supplied from the oxygen generator 17 is extracted, and supplied to the superficial portion 31 through the oxygen supply line 33. Here, the temperature of the empty tower 31 is detected by the temperature detector 39, and based on this detected temperature, the valve opening of the control valve 43 is adjusted via the controller 41 to control the oxygen supply amount. That is, when the temperature of the empty tower 31 is lower than the set temperature, the oxygen supply amount is increased to increase the temperature of the empty tower 31, and when the temperature of the empty tower 31 is higher than the set temperature. By performing the operation of reducing the oxygen supply amount, the temperature of the empty tower 13 can be maintained within the appropriate temperature range for gasification.

  As described above, by supplying the oxygen-rich gas to the superficial part 31 separately from the fluidized gas, the superficial part 31 can be maintained at an optimum temperature state for gasification independently of the fluidized bed 25. The gasification efficiency of waste can be further improved.

(Second Embodiment)
Hereinafter, a second embodiment of a fluidized bed gasifier to which the present invention is applied will be described with reference to the drawings. FIG. 2 is a detailed view showing a configuration of a diffuser tube of a fluidized bed gasification system to which the present invention is applied. In the present embodiment, only different parts from the first embodiment will be described, and description of the same parts will be omitted.

  In 1st Embodiment, the combustible gas after dust-removing with the dust collector 13 is guide | induced to the partial combustor 1, and is partially burned with oxygen rich gas. On the other hand, in this embodiment, as shown in the figure, for example, the combustible gas immediately after being discharged from the gasification furnace 3 is extracted from, for example, the upstream side of the dust collector 5 and replaced with the partial combustor 1. Therefore, the second embodiment is different from the first embodiment in that it is led to the air diffuser 71 and partially burned.

  In the present embodiment, the air diffusion pipe 71 is formed with a combustion portion 73 that partially burns combustible gas. In the combustion unit 73, a mixed gas of combustible gas supplied from the upstream side of the air diffusion pipe 71 and oxygen-rich gas introduced from the nozzle 75 is burned by ignition of the igniter 51. The combustible gas heated in the combustion unit 73 is blown into the fluidized bed 25 from the ejection holes 77.

  According to this, since combustible gas can be utilized as high-temperature circulation gas, the amount of oxygen supplied to the partial combustor 1 can be saved, and the facility can be simplified. In addition, since the combustible gas extracted from the gasification furnace 3 contains tar, char, etc. and is high in temperature, it is necessary to take measures to prevent thermal damage and blockage of equipment on a circulation line such as a circulation blower. Needless to say.

1 is a system diagram of a fluidized bed gasification system according to a first embodiment to which the present invention is applied. In the fluidized bed type gasification system of a 2nd embodiment to which the present invention is applied, it is a detailed figure showing composition of a diffuser tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Partial combustor 3 Gasifier 5,13 Dust collector 15 Storage tank 17 Oxygen generator 23,71 Air diffuser 25 Fluidized bed 29,39,55 Temperature detector 37,41,57 Controller 73 Combustion part

Claims (7)

A fluidized bed that heats the workpiece supplied to the gasification furnace and fluidizes it with a fluidizing gas to generate a combustible gas, extracts a part of the combustible gas, and returns the fluidized gas to the gasification furnace. In the type gasification method,
Before returning the combustible gas to the gasification furnace, a part of the combustible gas is combusted with an oxygen-rich gas and heated to a set temperature. The fluidized bed gasifier method according to claim 1, wherein the combustible gas burned with the oxygen-rich gas is cooled to a set temperature. In a fluidized bed gasifier having a gasification furnace that heats an object to be processed and fluidizes with a fluidizing gas to generate a combustible gas, and a gas supply means for supplying the fluidizing gas to the gasification furnace. ,
The gas supply means guides a part of the combustible gas discharged from the gasification furnace to a partial combustor, partially burns it with an oxygen-rich gas, and heats the heated combustible gas. As a fluidized bed type gasifier. The fluidized-bed gasifier according to claim 3, wherein the gas supply unit includes a heat exchanger that adjusts a temperature of the combustible gas between the partial combustor and the gasification furnace. . The gas supply means detects the temperature of the combustible gas discharged from the partial combustor, and controls the supply amount of the oxygen-rich gas used for the partial combustion based on the detected value. The fluidized bed type gasifier according to claim 3. The fluidized-bed gasifier according to any one of claims 3 to 5, wherein an oxygen-rich gas is supplied to an empty portion of the gasifier. The fluidized bed type gasifier according to claim 6, wherein the temperature of the empty tower portion is detected, and the supply amount of the oxygen-rich gas supplied to the empty tower portion is controlled based on the detected value.

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