JP6127215B2 - Gasification system - Google Patents

Description

  The present invention relates to a gasification system that generates a fuel gas by decomposing a slurry body produced by preparing biomass in a supercritical state.

  There is known a gasifier that obtains fuel gas by decomposing biomass in a supercritical state. For example, Patent Document 1 discloses that a biomass slurry containing a nonmetallic catalyst is hydrothermally treated under conditions of a temperature of 374 ° C. or higher and a pressure of 22.1 MPa or higher, and the generated fuel gas is used for a power generator. A biomass gasification power generation system that generates power and heats a slurry body using exhaust heat from a power generation device is described.

JP 2008-246343 A

  FIG. 7 is a diagram illustrating a general biomass gasification power generation system. As shown in the figure, the gasification system 2 includes a heat exchanger 3, a heater 4, and a gasification reactor 5. Among these parts, the heat exchanger 3 is a device for heating the slurry-like raw material (slurry body). This slurry body is prepared by, for example, adding water and activated carbon (catalyst) to biomass such as shochu residue, egg-collecting chicken manure, and sludge and mixing them. The heater 4 is a device that raises the temperature of the slurry heated by the heat exchanger 3 to a gasification reaction temperature (temperature at which the slurry is gasified (gasification is possible)). The gasification reactor 5 is an apparatus that keeps the slurry body constant at the gasification reaction temperature. The fluid that has undergone the gasification reaction is then gas-liquid separated, and the gas component is used as fuel gas.

  Here, as the heat exchanger 3, for example, a double-pipe heat exchanger is used. FIG. 8 is a diagram illustrating the configuration of the double pipe 6 provided in the double pipe heat exchanger. As shown in the figure, in the double pipe 6, a low-temperature flow path 8 is defined inside the inner pipe 7, and a high-temperature flow path 11 is defined between the outer pipe 9 and the inner pipe 7. A slurry body 13 is circulated through the low temperature flow path 8. On the other hand, a high-temperature fluid 14 that exchanges heat with the slurry body 13 flows through the high-temperature channel 11 in the opposite direction to the slurry body 13. Then, the slurry body 13 introduced from the inlet 12 of the low-temperature channel 8 is heated while exchanging heat with the high-temperature fluid 14 and discharged from the outlet 15.

  FIG. 9 is a diagram illustrating an example of a change in the temperature of the slurry body 13 and a change in the temperature of the high-temperature fluid 14 in the heat exchanger 3 including the double pipe 6. In this figure, the vertical axis indicates the temperature of the fluid, and the horizontal axis indicates the distance of the double pipe 6. Supplementing the distance of the double pipe 6, the distance of the double pipe 6 is from the inlet 12 when the position of the inlet 12 in the inner pipe 7 is 0 and the position of the outlet 15 is 100. Is the distance.

  As shown in FIG. 9, the temperature of the slurry 13 introduced into the inlet 12 at room temperature is raised, but the intermediate portion 16 of the heat exchanger 3 (the temperature of the slurry 13 is about 380 ° C. It can be seen that the temperature increase rate of the slurry body 13 is extremely slow at a portion of about 30 to about 70). Similarly, in the high temperature fluid 14, almost no temperature change is observed in the intermediate portion 16, and the temperature is about 380 ° C., which is substantially the same as that of the slurry body 13.

  Thus, the reason why the temperature change of the slurry body 13 and the high-temperature fluid 14 in the intermediate portion 16 is smaller than that of the other portions is that the constant pressure specific heat of the slurry body 13 and the high-temperature fluid 14 in the intermediate portion 16 is high. It is thought that it is because.

  That is, the internal pressure of the heat exchanger 3 is a high pressure (for example, 25 MPa), but under such a high pressure, the constant pressure specific heat of the slurry body 13 and the high temperature fluid 14 is a specifically high peak near the critical temperature (about 380 ° C.). It is known to take a value. Actually, the constant pressure specific heat of the high temperature fluid 14 peaks at a temperature slightly lower than the constant pressure specific heat of the slurry body 13 due to pressure loss in the double pipe 6. For this reason, the temperature difference between the slurry body 13 and the high temperature fluid 14 is minimized in the intermediate portion 16, and the heat exchange amount per unit heat transfer area is a portion other than the intermediate portion, and the low temperature portion 17 and the high temperature of the heat exchanger 3. Smaller than the portion 18. As a result, the slurry body 13 is not easily heated.

  Further, it is known that tar derived from biomass components is easily generated in the intermediate portion 16. The generated tar adheres to the inner wall of the inner pipe 7 to reduce the heat passage rate, and closes the pipe, thereby obstructing the flow of the slurry body 13 and further reducing the exchange heat per unit heat transfer area. It has become.

  This invention is made | formed in view of such the present condition, The objective is to provide the gasification system for performing gasification of biomass efficiently.

In order to achieve the above object, the present invention provides a gasification system for generating a fuel gas by decomposing a slurry body produced by preparing biomass in a supercritical state, wherein a high-temperature fluid in a supercritical state is used. A heat exchanger that heats the slurry body by exchanging heat between the high-temperature fluid and the slurry body, and heats the slurry body that is sent from the heat exchanger, and the supercritical high-temperature fluid. And the heat exchanger is configured by a high-temperature channel and a low-temperature channel, and the high-temperature fluid generated in the gasification reactor is circulated through the high-temperature channel. The low-temperature flow path is divided into a first block for circulating the slurry body and a second block for circulating a fluid having a pressure lower than that of the high-temperature fluid, which is used in a separate heat engine. block, the Specific heat at constant pressure of the slurry body, in a temperature range equal to or less than the value of the constant pressure specific heat at pseudocritical point of the slurry body and the slurry body and the hot fluid is provided so as to be heat-exchanged, the second block, the Provided in portions other than the first block.

  In the gasification system of the present invention, the low-temperature flow path is divided into a first block that circulates the slurry body and a second block that circulates a fluid having a pressure lower than that of the high-temperature fluid used in a separate heat engine. ing. Further, in this system, the first block is provided so that heat can be exchanged between the slurry body and the high-temperature fluid in a temperature range in which the constant pressure specific heat becomes a predetermined value or less. For this reason, the temperature of the slurry body can be efficiently increased by the heat transferred from the high-temperature fluid to the slurry body. That is, it is possible to utilize a portion where the temperature exchange performance between the high-temperature fluid and the slurry body in the heat exchanger is high. As a result, biomass gasification can be performed efficiently. Furthermore, since the second block is arranged in a portion other than the first block, the thermal energy of the high-temperature fluid can be used as a heat source for another heat engine without waste.

  In the above gasification system, the fluid used in the separate heat engine is steam, and the separate heat engine uses steam generated by flowing through the second block as power. It preferably includes a turbine. In this configuration, the thermal energy supplied from the high-temperature fluid can be effectively used as power for the steam turbine.

In the gasification system described above, the exhaust gas discharged from the combustion device provided in the gasification reactor is circulated, and heat exchange is performed between the water obtained by agglomeration of water vapor that has finished work in the steam turbine and the exhaust gas. It is preferable to provide an exhaust duct. In this configuration, the thermal energy of the exhaust gas discharged from the gasification reactor can be effectively used as power for the steam turbine.

  According to the gasification system of the present invention, biomass can be efficiently gasified.

It is a figure explaining the composition of the gasification system concerning a 1st embodiment. It is the figure which illustrated the temperature change of the high temperature fluid in a double pipe type heat exchanger, a slurry body, and motive power steam. It is a graph which shows the relationship between the temperature in water, a pressure, and a constant pressure specific heat. It is a graph which shows the constant pressure specific heat and temperature relationship in a slurry body. It is a figure explaining the structure of the gasification system which concerns on 2nd Embodiment. It is a figure explaining the 1st modification of a heat exchanger. It is a figure explaining the 2nd modification of a heat exchanger. It is a figure explaining a general biomass gasification power generation system. It is a figure explaining the structure of the double pipe in a double pipe type heat exchanger. It is the figure which illustrated the temperature change of the high temperature fluid and the slurry body in a double tube type heat exchanger.

  Embodiments of the present invention will be described below. First, the first embodiment will be described. FIG. 1 is a diagram illustrating a configuration of a gasification system 10 according to the first embodiment. In the gasification system 10, a slurry body is prepared from biomass such as shochu residue, egg-collecting chicken manure, and sludge as raw materials, and combustion gas is generated by heating and pressurizing the prepared slurry body. As shown in the figure, the gasification system 10 includes a raw material preparation unit 20, a heat treatment unit 30, and a gas processing unit 40.

  The raw material preparation unit 20 is a part that prepares a slurry body from biomass. The raw material preparation unit includes a preparation tank 21, a pulverizer 22, a supply pump 23, and a heat exchanger introduction pump 24.

  The preparation tank 21 is a container for mixing biomass, water, and activated carbon (a kind of nonmetallic catalyst). In the preparation tank 21, a mixture in which biomass, water, and activated carbon are mixed is prepared. For example, porous particles having an average particle diameter of 200 μm or less are used as the activated carbon. The mixing ratio of biomass, water, and activated carbon is appropriately adjusted according to the type, amount, moisture content, and the like of biomass.

  The pulverizer 22 is an apparatus for crushing the solid content of the mixture prepared in the preparation tank 21 to obtain a uniform size (preferably an average particle size of 500 μm or less, more preferably an average particle size of 300 μm or less). is there. By being processed by the pulverizer 22, the mixture becomes a slurry-like slurry body.

  The supply pump 23 supplies the slurry body discharged from the pulverizer 22 to the heat exchanger introduction pump 24. The heat exchanger introduction pump 24 pressurizes the slurry body sent from the supply pump 23 and supplies it to the heat treatment unit 30. The slurry body is pressurized to about 0.1 to 4 MPa by the heat exchanger introduction pump 24.

  The heat treatment unit 30 is a part that heats and gasifies the slurry body prepared by the raw material preparation unit 20. The heat treatment unit 30 includes a heat exchanger 31, a heater 32, a gasification reactor 33, and a power generation unit 34.

  The heat exchanger 31 is a device that heats the slurry body sent from the raw material preparation unit 20. The heat exchanger 31 is a double tube heat exchanger including a double tube, and includes a low temperature channel 36 and a high temperature channel 37. The low-temperature flow path 36 is divided into a first block 36 a through which the slurry body sent from the raw material preparation unit 20 circulates and a second block 36 b through which steam for power of about a dozen MPa serving as power for the power generation unit 34 circulates. It is divided. On the other hand, a supercritical high-temperature fluid (hereinafter also referred to as a processed fluid, which will be described later) generated in the gasification reactor 33 is introduced into the high-temperature channel 37, and this processed fluid flows. Then, heat is exchanged between the processed fluid flowing through the high-temperature channel 37 and the slurry for flowing through the first block 36a and the steam for power flowing through the second block 36b. The heat exchanger 31 will be described later.

  The heater 32 is a device that heats the slurry body sent from the heat exchanger 31. The heater 32 includes a combustion device 32a. The combustion device 32a introduces the combustion gas sent from the gas processing unit 40 into liquefied petroleum gas such as propane gas or air and burns it, thereby heating the slurry body. To do. Thereby, the temperature of the slurry introduced into the heater 32 is raised to, for example, about 600 ° C. The heated slurry body is sent to the gasification reactor 33.

  The gasification reactor 33 keeps the slurry sent from the heater 32 constant at the gasification reaction temperature (temperature at which the slurry is gasified (gasification is possible)), and is contained in the slurry. This is an apparatus for hydrothermal treatment of organic matter. The gasification reactor 33 includes a combustion device 33a. The combustion device 33a introduces combustion gas sent from the gas processing unit 40 into liquefied petroleum gas or air and burns it, and hydrothermally heats the slurry body. In this hydrothermal treatment, the slurry body is hydrothermally treated for 1 to 2 minutes under conditions of, for example, 600 ° C. and 25 MPa. The hydrothermally treated slurry body undergoes a gasification reaction and then is sent to the high-temperature channel 37 of the heat exchanger 31 as a post-treatment fluid.

  The power generation unit 34 is a part that generates power using the power steam generated by the heat exchanger 31, and corresponds to a heat engine of another system. The power generation unit 34 includes a steam turbine 51, a generator 52, a condenser 53, and a pump 54. The steam turbine 51 is a device that performs work (rotational motion) with the power steam generated by the heat exchanger 31. The generator 52 is a device that generates power by the rotation of the steam turbine 51. The condenser 53 is a device that condenses water vapor that has finished work in the steam turbine. The pump 54 is a device that sends out the water obtained by aggregation to the heat exchanger 31.

  In this power generation unit 34, the steam turbine 51 is caused to work by power steam generated by the heat exchanger 31 (second block 36 b), and electric power is obtained from the generator 52. And the water vapor | steam which finished work is condensed with the condenser 53, and the steam for power is produced | generated by sending out the obtained water to the heat exchanger 31. FIG.

  The gas processing unit 40 is a part that extracts fuel gas from the processed fluid sent from the heat exchanger 31. The gas processing unit 40 includes a decompression mechanism 41, a cooling mechanism 42, a gas-liquid separator 43, and a gas tank 44.

  The decompression mechanism 41 is a device that decompresses the processed fluid sent from the heat exchanger 31. The cooling mechanism 42 is a device that cools the processed fluid sent from the decompression mechanism 41. The gas-liquid separator 43 is a device that separates the treated fluid cooled by the cooling mechanism 42 into a liquid (a liquid containing activated carbon or ash) and a gas (a gas such as hydrogen or methane). Among these, the liquid is treated as drainage, and the gas is sent to the gas tank 44.

  The gas tank 44 is a container for storing the gas (product gas) separated by the gas-liquid separator 43. Part of the product gas stored in the gas tank 44 is supplied to the heater 32 and the gasification reactor 33 and consumed as fuel gas. In addition, this fuel gas can also be used as power generation or a power source.

  Next, the heat exchanger 31 will be described. As described above, in the heat exchanger 31 of the present embodiment, the low temperature flow path 36 is divided into the first block 36a through which the slurry body flows and the second block 36b through which power steam flows. The second block 36b is arranged on the upstream side (high temperature side) of the high temperature flow path 37, and the first block 36a is arranged on the downstream side (low temperature side) of the high temperature flow path 37.

  Thereby, as shown in FIG. 2, in the section from the slurry body inlet (distance 0) to the distance L1 in the heat exchanger 31, heat exchange is performed between the high-temperature fluid (that is, the treated fluid) and the slurry body. The slurry body is heated by the heat transferred from the fluid after the treatment. Similarly, in the section from the distance L2 after the distance L1 to the treated fluid introduction port (distance 100), heat exchange is performed with the fluid used in the power generation unit 34.

  In this section, the water sent from the pump 54 of the power generation unit 34 is evaporated by the heat from the processed fluid, and power steam is generated. The generated power steam is heated by heat from the treated fluid, and the temperature and pressure are increased. Here, the pressure of the power vapor is sufficiently lower than the pressure of the treated fluid, for example, about a dozen MPa. For this reason, the water and power steam sent from the pump 54 absorb the heat from the treated fluid and are quickly heated.

  And the ratio of the length of the 1st block 36a and the 2nd block 36b in the low-temperature flow path 36 is defined based on the final heating temperature T1 of a slurry body. Hereinafter, this point will be described.

  FIG. 3 is a graph showing the relationship between temperature, pressure, and constant pressure specific heat in water. From this graph, it can be seen that, under ultra-high pressure, the constant pressure specific heat in a specific temperature range (a range of about 370 ° C. to about 400 ° C.) called a pseudocritical point rapidly increases. And the slurry body which contains water as a main component also has the same characteristic.

  FIG. 4 is a graph conceptually showing the relationship between the constant-pressure specific heat and the temperature in the slurry body under 25 MPa. As shown in the figure, in this slurry body, the constant pressure specific heat at the temperature TP shows the peak value SHP. If the specific heat at a constant pressure becomes too high, it becomes difficult for temperature changes to occur even if heat is absorbed or released. Therefore, in the present embodiment, the first block 36a is placed in the high-temperature channel 37 so that heat exchange is performed between the slurry body and the processed fluid in a temperature range where the constant pressure specific heat is equal to or less than the predetermined value SH1 (range of temperature T1 or less). It is arranged on the downstream side.

  In this configuration, the slurry body is heated by the heat transferred from the treated fluid to the slurry body, and the temperature is increased. Here, since the heat exchange is performed in the range up to the temperature T1 at which the constant pressure specific heat becomes equal to or less than the predetermined value SHP, the slurry body can be efficiently heated to the temperature T1. In other words, it is possible to utilize a portion where the temperature exchange performance between the processed fluid and the slurry body in the heat exchanger is high. As a result, biomass gasification can be performed efficiently. Further, since the second block 36b is arranged on the upstream side of the high-temperature flow path 37, a portion of the thermal energy of the processed fluid that is not used for heating the slurry body is used in the power generation unit 34. It is possible to generate power steam of about several tens of MPa.

  Next, a second embodiment will be described with reference to FIG. As shown in the figure, in the second embodiment, with respect to the power generation unit 34, an exhaust gas duct 55 is provided in the middle of a pipe connecting the condenser 53 and the pump 54, and the exhaust gas from the gasification reactor 33 is exhausted. It is characterized in that it is introduced into the duct 55. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

  In the second embodiment, the exhaust gas from the gasification reactor 33 and the water from the condenser 53 are heat-exchanged in the exhaust gas duct 55 to heat the water from the condenser 53. The heated water is sent to the heat exchanger 31 by the pump 54, and power steam is generated. In this configuration, the thermal energy of the exhaust gas discharged from the gasification reactor 33 can be effectively used as power for the steam turbine.

  The above description of the embodiment is for facilitating the understanding of the present invention, and does not limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof. For example, you may comprise as follows.

  For example, the raw material of biomass may be other than shochu residue, for example, egg-collecting chicken manure, sewage sludge and other water-containing biomass.

  In each of the above embodiments, water and a catalyst are mixed when the slurry body is generated, but these may not be mixed.

  Further, as shown in FIG. 6A, with respect to the heat exchanger 31, the second block 36 b is disposed in the middle portion of the low temperature channel 36, which is a temperature range where the constant pressure specific heat of the slurry body reaches a peak, You may arrange | position the 1st block 36a in each of a side part and a high temperature side part.

  Further, as shown in FIG. 6B, with respect to the heat exchanger 31, the second block 36 b is arranged from the middle part of the low temperature channel 36 where the constant pressure specific heat of the slurry body reaches a peak to the low temperature side part, and the low temperature channel 36. You may arrange | position the 1st block 36a in the high temperature side part.

  In short, with respect to the low-temperature flow path 36 of the heat exchanger 31, the first block 36a through which the slurry body circulates exchanges heat between the slurry body and the treated fluid in a temperature range where the constant pressure specific heat of the slurry body is a predetermined value or less. The second block 36b through which the low-pressure fluid used in the heat engine of another system flows may be provided in a portion other than the first block 36a in the low-temperature channel 36.

  In addition, the heat exchanger may be divided into a first heat exchanger and a second heat exchanger. In this case, in the first heat exchanger, heat is exchanged between the processed fluid and the first block 36a, and in the second heat exchanger, heat is exchanged between the processed fluid and the second block 36b. Good.

  In addition, regarding the heat engine of another system, the power generation unit 34 has been exemplified in the above-described embodiment. However, as long as the heat of the processed fluid flowing in the high-temperature channel 37 is used, heating equipment, chemical reaction equipment, and other It may be a type of heat engine. In this case, the fluid used in another heat engine is not limited to water vapor. Any fluid having a lower pressure than the treated fluid may be used.

DESCRIPTION OF SYMBOLS 2 ... Gasification system, 3 ... Heat exchanger, 4 ... Heater, 5 ... Gasification reactor, 6 ... Double pipe, 7 ... Inner piping, 8 ... Low temperature flow path, 9 ... Outer piping, 10 ... Gasification system, 11 ... high temperature flow path, 12 ... inlet, 13 ... slurry body, 14 ... high temperature fluid, 15 ... discharge port, 16 ... intermediate part, 17 ... low temperature part, 18 ... high temperature part, 20 ... raw material preparation part , 21 ... Preparation tank, 22 ... Crusher, 23 ... Supply pump, 24 ... Heat exchanger introduction pump, 30 ... Heat treatment part, 31 ... Heat exchanger, 32 ... Heater, 32a ... Combustion device, 33 ... Gasification reaction 33a ... combustion device 34 ... power generation unit 35 ... boiler 36 ... low temperature channel 36a ... first block of low temperature channel 36b ... second block of low temperature channel 37 ... high temperature channel 40 ... Gas processing unit 41 ... Depressurization mechanism 42 ... Cooling mechanism 43 ... Gas-liquid separator 44 ... Gas Tank, 51 ... steam turbines, 52 ... generator, 53 ... condenser 54 ... pumps, 55 ... exhaust gas duct

Claims (3)

A gasification system for producing a fuel gas by decomposing a slurry body produced by preparing biomass in a supercritical state,
A high temperature fluid in a supercritical state is introduced, and a heat exchanger that heats the slurry body by exchanging heat between the high temperature fluid and the slurry body;
A gasification reactor for heating the slurry body delivered from the heat exchanger and generating the supercritical high-temperature fluid;
The heat exchanger is constituted by a high temperature channel and a low temperature channel,
In the high temperature flow path, the high temperature fluid generated in the gasification reactor is circulated,
The low-temperature flow path is divided into a first block that circulates the slurry body and a second block that circulates a fluid having a pressure lower than that of the high-temperature fluid, which is used in a separate heat engine,
The first block is a portion that circulates through the low-temperature flow path and the temperature of the slurry body that is heat-exchanged with the high-temperature fluid is equal to or lower than the pseudo-critical temperature of the slurry body,
The second block is a gasification system provided in a portion other than the first block. The fluid used in the separate heat engine is water vapor,
The gasification system according to claim 1, wherein the separate heat engine includes a steam turbine powered by steam generated by flowing through the second block. The exhaust gas discharged from the combustion device provided in the gasification reactor is circulated, and the exhaust gas is provided with an exhaust duct for exchanging heat between water obtained by agglomeration of water vapor that has finished work in the steam turbine and the exhaust gas. 2. The gasification system according to 2.