WO2024080182A1

WO2024080182A1 - Powder recovery device and method for controlling powder recovery device

Info

Publication number: WO2024080182A1
Application number: PCT/JP2023/035973
Authority: WO
Inventors: 康弘山内; 克彦篠田; 篤藤井
Original assignee: 三菱重工業株式会社; 三菱パワー株式会社
Priority date: 2022-10-11
Filing date: 2023-10-02
Publication date: 2024-04-18
Also published as: JP2024056360A

Abstract

The present invention provides a dust collector (31) comprising: a generated gas filter (31A); a cooling hopper (31B); a first discharge valve (31D) disposed on an introduction line (31Ba) of the cooling hopper (31B); a second discharge valve (31E) disposed on a discharge line (31Bc) of the cooling hopper (31B); a pressurizing part (31F) that executes a pressurizing operation to pressurize a recovery container (31Bb) of the cooling hopper (31B); a depressurizing part (31G) that executes a depressurizing operation to depressurize the recovery container (31Bb); and a control unit. The control unit provides control such that the pressurizing operation executed by the pressurizing part (31F) and the depressurizing operation executed by the depressurizing part (31G) are alternately repeatedly with the first discharge valve (31D) and the second discharge valve (31E) placed in a closed state, and then char recovered into the recovery container (31Bb) is discharged from the discharge line (31Bc) with the second discharge valve (31E) placed in an open state.

Description

Powder recovery device and method for controlling the powder recovery device

This disclosure relates to a powder recovery device and a method for controlling the powder recovery device.

　Conventionally, there is known an ash treatment device that reduces the temperature of ash collected from combustion gas by an ash collector and discharges it outside the system (see, for example, Patent Document 1). The ash treatment device disclosed in Patent Document 1 cools the ash collected from the high-pressure, high-temperature combustion gas containing ash in an ash cooler and transports it to a high-pressure ash storage tank. The ash that accumulates at the bottom of the high-pressure ash storage tank is discharged into a vacuum hopper, and after being depressurized to atmospheric pressure, it is sent to an ash silo.

Japanese Patent Application Laid-Open No. 7-42910

However, in Patent Document 1, an ash cooler is required as equipment for reducing the temperature of the ash collected by the ash collector, which increases the installation cost of the ash collector and requires installation space for the ash cooler. In addition, if flammable gas is adsorbed into the pores of the ash particles collected by the ash collector, the ash containing unburned matter discharged from the ash collector may oxidize and generate heat (spontaneous heating), or the flammable gas may desorb from the ash and pollute the outside air.

The present disclosure has been made in consideration of these circumstances, and aims to provide a powder recovery device and a control method for a powder recovery device that can separate and cool powder from a heated gas to be treated while suppressing increases in installation costs and installation space, spontaneous heating of the powder, and pollution of the outside air.

In order to solve the above problems, the present disclosure employs the following solutions.
A powder recovery device according to the present disclosure is a powder recovery device that separates and recovers powder from a heated gas to be treated, and includes a powder separation section to which the gas to be treated is introduced and which separates the powder from the gas to be treated, an introduction section to which the powder separated by the powder separation section is introduced, a recovery container that temporarily recovers the powder introduced from the introduction section, and a discharge section that discharges the powder recovered in the recovery container, the powder recovery device including a first recovery section having a first on-off valve provided in the introduction section, a second on-off valve provided in the discharge section, and a pressurizing gas supply section provided in the recovery container. the pressurizing unit performs a pressurizing operation to pressurize the collection container by discharging the pressurizing gas from the collection container to the outside, and a control unit controls the first on-off valve, the second on-off valve, the pressurizing unit, and the decompression unit, and the control unit controls the first on-off valve and the second on-off valve to be in a closed state so as to alternately repeat the pressurizing operation by the pressurizing unit and the decompression operation by the decompression unit, and then controls the second on-off valve to be in an open state so as to discharge the powder collected in the collection container from the discharge unit.

The control method of a powder recovery device according to the present disclosure is a control method of a powder recovery device that separates and recovers powder from a heated gas to be treated, the powder recovery device comprising a first recovery section having a powder separation section into which the gas to be treated is introduced and which separates the powder from the gas to be treated, an introduction section into which the powder separated by the powder separation section is introduced, a recovery container that temporarily recovers the powder introduced from the introduction section, and a discharge section that discharges the powder recovered in the recovery container, a first opening/closing valve installed in the introduction section, a second opening/closing valve installed in the discharge section, and a valve for discharging the powder recovered in the recovery container. The apparatus includes a pressurizing unit that supplies a pressurizing gas to perform a pressurizing operation to pressurize the collection container, and a depressurizing unit that performs a depressurizing operation to depressurize the collection container by discharging the pressurizing gas from the collection container to the outside, and includes a pressurizing step in which the pressurizing operation is performed with the first and second opening/closing valves in a closed state, a depressurizing step in which the depressurizing operation is performed by the depressurizing unit with the first and second opening/closing valves in a closed state, and a discharging step in which the pressurizing step and the depressurizing step are alternately repeated, and then the second opening/closing valve is opened and the powder collected in the collection container is discharged from the discharging unit.

The present disclosure provides a powder recovery device and a method for controlling the powder recovery device that can separate and cool powder from a heated gas to be treated while minimizing increases in installation costs and installation space, spontaneous heating of the powder, and pollution of the outside air.

1 is a schematic configuration diagram showing a biomass gasification facility according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram showing a system configuration of the dust collection facility shown in FIG. 1 . 4 is a flowchart showing a method for controlling the dust collection equipment of the present embodiment. 1 is a graph showing a relationship between the time for repeatedly performing pressurizing and depressurizing operations and the temperature of char in a cooling hopper. 10 is a graph showing the relationship between the time required to repeatedly perform pressurizing and depressurizing operations and the dilution rate of gas in a cooling hopper. 1 is a graph showing a relationship between a pressure ratio of a first internal pressure to a second internal pressure and a cooling time of char inside a cooling hopper.

Below, a biomass gasification facility 10 according to an embodiment of the present disclosure will be described with reference to FIG. 1. The biomass gasification facility 10 according to this embodiment is a device that generates combustible biomass gas by partially burning and gasifying biomass fuel. Biomass fuel is a renewable organic resource derived from living organisms, and examples include thinned wood, waste wood, driftwood, grass, waste, sludge, and recycled fuels (pellets and chips) made from these raw materials, but is not limited to those presented here. Biomass fuel is carbon neutral, meaning that it does not emit carbon dioxide, a greenhouse gas, because it captures carbon dioxide during the biomass growth process, and various uses of biomass fuel are being considered.

As shown in FIG. 1, the biomass gasification equipment 10 includes a biomass gasification furnace 11 that generates biomass gas, a high-temperature synthesis gas cooler 12 (high-temperature SGC: synthesis gas cooler) to which the biomass gas discharged from the biomass gasification furnace 11 is guided, a char recovery equipment 30 that recovers char (mainly unburned carbon and ash) contained in the biomass gas, a char cooler (heat exchange unit) 16 that cools the recovered char, a low-temperature synthesis gas cooler 14 (low-temperature SGC) to which the biomass gas from which the char has been removed is guided, a feedwater preheating unit 17 that preheats the gasification agent that is guided to the low-temperature synthesis gas cooler 14, a scrubber 18 that removes impurities from the biomass gas, and a control unit 90.

The biomass gasifier 11 generates biomass gas by gasifying the biomass fuel supplied by the biomass supply unit 19. The biomass supply unit 19 transports the biomass fuel to the biomass gasifier 11 and has a feeder (not shown) that feeds the biomass fuel into the biomass gasifier 11.

The biomass gas generated in the biomass gasifier 11 is guided to the high-temperature synthesis gas cooler 12 via the first biomass gas line L1. An oxygen line L17 is connected to the biomass gasifier 11. Oxygen supplied from an oxygen supply device (not shown) flows through the oxygen line L17.

The high-temperature syngas cooler 12 and the low-temperature syngas cooler 14 exchange heat between the biomass gas and the feed water or steam (gasification agent). The high-temperature syngas cooler 12 and the low-temperature syngas cooler 14 use the heat of the biomass gas generated in the biomass gasifier 11 to heat the steam that is led to the biomass gasifier 11 as a gasification agent, and to cool the biomass gas. The biomass gas discharged from the high-temperature syngas cooler 12 is led to the dust collection equipment 31 of the char recovery equipment 30 via the second biomass gas line L2. The biomass gas discharged from the low-temperature syngas cooler 14 is led to the scrubber 18 via the fourth biomass gas line L4.

The char recovery equipment 30 passes biomass gas and recovers char contained in the passing biomass gas. The char recovery equipment 30 includes a dust collection equipment (powder recovery device) 31 and a supply hopper 32. The dust collection equipment 31 can separate the char contained in the product gas generated in the biomass gasification furnace 11. The biomass gas (product gas) from which the char has been separated is then sent to the low-temperature synthesis gas cooler 14 via the third biomass gas line L3. Details of the char recovery equipment 30 will be described later.

The char separated in the dust collection equipment 31 is guided to the supply hopper 32 via the first char line L6. The char stored in the supply hopper 32 is discharged from the outlet of the supply hopper 32 at a predetermined timing and guided to the char cooler 16 via the second char line L7.

The char cooler 16 cools the char with make-up water. Make-up water (gasification agent) is guided to the char cooler 16 from a make-up water supply device (not shown) via a first make-up water line L9. The cooled char is discharged outside the system via a third char line L8. Make-up water at room temperature is supplied to the char cooler 16 from a make-up water supply device (not shown). The make-up water is heated by multiple devices including the char cooler 16 and then guided to the biomass supply unit 19 via a second make-up water line L10. The make-up water heated in the biomass supply unit 19 is guided to the first feed water line L12 via a third make-up water line L11 that connects the biomass supply unit 19 to the feed water line.

The feedwater preheating section 17 heats the feedwater using a heat medium. The feedwater preheating section 17 is supplied with room temperature feedwater from a feedwater supply device (not shown). In the feedwater preheating section 17, the feedwater is heated by heat exchange with the heat medium, and some or all of the feedwater becomes steam. The feedwater is heated in the low-temperature synthesis gas cooler 14 to a temperature that does not cause problems in terms of condensation or precipitation of impurities. The steam discharged from the feedwater preheating section 17 is guided to the low-temperature synthesis gas cooler 14 via the first steam line L13. The steam heated in the low-temperature synthesis gas cooler 14 is guided to the high-temperature synthesis gas cooler 12 via the second steam line L14.

The scrubber 18 removes impurities (e.g., tar, ammonia, etc.) contained in the biomass gas. The impurities and excess water vapor removed by the scrubber 18 are discharged as wastewater together with scrubber water to the outside of the system via the drainage line L18. The biomass gas from which the impurities and excess water vapor have been removed is discharged from the scrubber 18 and guided to the downstream equipment via the fifth biomass gas line L5. One example of the downstream equipment is a liquid fuel synthesis equipment for biojet fuel, etc.

The control unit 90 is a device that controls each part of the biomass gasification equipment 10, including the char recovery equipment 30.

Next, the dust collection equipment 31 of this embodiment will be described in detail. FIG. 2 is a schematic diagram showing the system configuration of the dust collection equipment 31 shown in FIG. 1. As shown in FIG. 2, the dust collection equipment 31 includes a generated gas filter (powder separation section) 31A, a cooling hopper (first recovery section) 31B, a discharge hopper 31C, a first discharge valve (first opening/closing valve) 31D, a second discharge valve (second opening/closing valve) 31E, a pressurizing section 31F, a decompressing section 31G, a temperature sensor (detection section) 31H, a first level sensor 31I, and a second level sensor 31J. As shown in FIG. 2, the generated gas filter 31A, the cooling hopper 31B, and the discharge hopper 31C are arranged in this order from the top in the vertical direction.

The generated gas filter 31A is a device that receives generated gas (gas to be treated) from the high-temperature synthesis gas cooler 12 via the second biomass gas line L2, and separates and recovers char (powder containing unreacted biomass fuel and ash) from the generated gas. The generated gas supplied to the generated gas filter 31A has a temperature in the range of, for example, 300°C or higher and 500°C or lower.

The product gas filter 31A includes a filter 31Ab in a container 31Aa. The filter 31Ab is a filter with many pores and is made of, for example, ceramics or sintered metal. The filters 31Ab are, for example, cylindrical, and a plurality of filters are provided in parallel with an axis in the vertical direction. The filter 31Ab divides the space in the container 31Aa into upper and lower spaces, with the lower space 31Ac being the pre-filtration space into which the product gas containing char flows, and the upper space 31Ad being the post-filtration space.

A second biomass gas line L2 that guides the generated gas containing char is connected to the lower space 31Ac of the generated gas filter 31A. A third biomass gas line L3 that guides the generated gas after char separation to the low-temperature synthesis gas cooler 14 is connected to the upper space 31Ad of the generated gas filter 31A.

The product gas filter 31A is provided with a backwashing device 31Ae. The backwashing device 31Ae backwashes the filter 31Ab and sprays backwashing gas in a pulsed manner (e.g., at intervals of 0.5 seconds) from the upper space 31Ad side toward the lower space 31Ac side to brush off char adhering to the surface of the filter 31Ab on the lower space 31Ac side. An inert gas such as nitrogen is used as the backwashing gas.

The cooling hopper 31B is a device that temporarily collects and cools the char discharged from the product gas filter 31A and discharges it to the discharge hopper 31C. The cooling hopper 31B has an inlet line (inlet section) 31Ba, a recovery container 31Bb, and a discharge line (discharge section) 31Bc. The inlet line 31Ba is a pipe that introduces the char separated from the product gas by the product gas filter 31A into the recovery container 31Bb. The recovery container 31Bb is a container that temporarily collects the char introduced from the inlet line 31Ba. The discharge line 31Bc is a pipe that discharges the char collected in the recovery container 31Bb to the discharge hopper 31C.

The discharge hopper 31C is a device that temporarily collects the char discharged from the cooling hopper 31B and supplies it to the supply hopper 32. The discharge hopper 31C has a collection container 31Ca, a rotary feeder 31Cb, and a discharge line 31Cc. The collection container 31Ca is a container that temporarily collects the char introduced from the discharge line 31Bc. The rotary feeder 31Cb is a device that guides the char from the collection container 31Ca to the discharge line 31Cc by rotating with the driving force of a motor. The discharge line 31Cc is a pipe that supplies the char collected in the collection container 31Ca to the supply hopper 32.

The first discharge valve 31D is disposed in the inlet line 31Ba and is an on-off valve that switches between an open state that connects the internal space of the container 31Aa of the product gas filter 31A to the internal space of the collection container 31Bb of the cooling hopper 31B, and a closed state that does not connect the internal space of the container 31Aa of the product gas filter 31A to the internal space of the collection container 31Bb of the cooling hopper 31B.

The second discharge valve 31E is disposed in the discharge line 31Bc, and is an on-off valve that switches between an open state that connects the internal space of the collection container 31Bb of the cooling hopper 31B to the internal space of the collection container 31Ca of the discharge hopper 31C, and a closed state that does not connect the internal space of the collection container 31Bb of the cooling hopper 31B to the internal space of the collection container 31Ca of the discharge hopper 31C.

The pressurizing unit 31F is a device that performs a pressurizing operation to supply pressurizing gas to the collection container 31Bb of the cooling hopper 31B to pressurize the internal space of the collection container 31Bb. The pressurizing unit 31F has a pressurizing gas supply source 31Fa and an on-off valve 31Fb. The on-off valve 31Fb switches between an open state in which pressurizing gas is supplied from the pressurizing gas supply source 31Fa to the collection container 31Bb, and a closed state in which pressurizing gas is not supplied from the pressurizing gas supply source 31Fa to the collection container 31Bb.

The pressurizing gas is, for example, nitrogen gas, but other inert gases may be used. For example, a gas with an oxygen concentration of 10% or less that will not oxidize the char and generate heat when it comes into contact with the char can be used. As shown in FIG. 2, the pressurizing unit 31F introduces the pressurizing gas into the recovery area 31Bd where the char is recovered below the recovery container 31Bb of the cooling hopper 31B, and agitates the char present in the recovery area 31Bd.

The decompression unit 31G is a device that performs a decompression operation to discharge the pressurization gas from the collection container 31Bb of the cooling hopper 31B to the outside and decompress the internal space of the collection container 31Bb. The decompression unit 31G has a filter 31Ga, a discharge line 31Gb, an on-off valve 31Gc, and an orifice 31Gd. The decompression unit 31G discharges the pressurization gas from the collection container 31Bb via the discharge line 31Gb by switching the on-off valve 31Gc from a closed state to an open state when the internal space of the collection container 31Bb is in a pressurized state higher than atmospheric pressure.

Note that the pores of the char collected in the collection vessel 31Bb may contain generated gas (flammable gas). In such a case, the pressurization gas discharged from the collection vessel 31Bb to the outside (e.g., into the atmosphere) will contain flammable gas, but since the pressurization gas has diluted the flammable gas to below the environmental standard value and below the flammable range, pollution of the surrounding environment is suppressed. In addition, in order to treat the flammable gas contained in the pressurization gas, the discharge line 31Gb may be connected to a treatment device such as a ground flare or a flare stack (not shown) and the flammable gas may be combusted.

The filter 31Ga is a filter having many pores, and is made of, for example, ceramics or sintered metal. The filter 31Ga is, for example, cylindrical. The pressure reducing section 31G shown in FIG. 2 has a single filter 31Ga, but may have multiple filters 31Ga.

The discharge line 31Gb is a pipe that guides the pressurized gas, from which char has been removed as it passes through the filter 31Ga, to the outside. An on-off valve 31Gc and an orifice 31Gd are installed in the discharge line 31Gb.

The on-off valve 31Gc is a device that switches between an open state in which the internal space of the collection container 31Bb is connected to the outside via the discharge line 31Gb, and a closed state in which the internal space of the collection container 31Bb is not connected to the outside via the discharge line 31Gb.

The orifice 31Gd is a device for limiting the flow rate of the pressurizing gas that flows through the exhaust line 31Gb per unit time when the on-off valve 31Gc is open. The orifice 31Gd determines the maximum flow rate of the pressurizing gas that flows through the exhaust line 31Gb per unit time by setting the flow path cross-sectional area to a predetermined value.

The temperature sensor 31H is a device that detects the temperature of the char collected in the collection area 31Bd of the collection container 31Bb of the cooling hopper 31B. The temperature sensor 31H transmits the detected char temperature to the control unit 90.

The first level sensor 31I is a sensor that detects whether the pile height of the char collected in the collection container 31Bb of the cooling hopper 31B has reached a first predetermined height. The second level sensor 31J is a sensor that detects whether the pile height of the char collected in the collection container 31Bb of the cooling hopper 31B has reached a second predetermined height that is higher than the first predetermined height. In the state shown in FIG. 2, the first level sensor 31I detects that the pile height of the char has reached the first predetermined height, but the second level sensor 31J does not detect that the pile height of the char has reached the second predetermined height.

Next, a method for controlling the dust collection equipment 31 of this embodiment will be described with reference to FIG. 3. FIG. 3 is a flowchart showing a method for controlling the dust collection equipment 31 of this embodiment. Each process of the flowchart in FIG. 3 is executed by the control unit 90 using a control program stored in a storage unit (not shown). In each process of the flowchart shown in FIG. 3, the control unit 90 controls the first discharge valve 31D, the second discharge valve 31E, the pressurizing unit 31F, and the depressurizing unit 31G.

In step S101, the control unit 90 controls the second discharge valve 31E installed in the discharge line 31Bc to close the second discharge valve 31E. When the second discharge valve 31E is closed, the cooling hopper 31B and the discharge hopper 31C are not in communication with each other.

In step S102, the control unit 90 controls the first discharge valve 31D installed in the inlet line 31Ba to open the first discharge valve 31D. When the first discharge valve 31D is open, the product gas filter 31A and the cooling hopper 31B are in communication with each other, and char is supplied from the product gas filter 31A to the cooling hopper 31B.

In step S103, the control unit 90 controls the first discharge valve 31D installed in the inlet line 31Ba to close the first discharge valve 31D in response to the lapse of a predetermined time since the first discharge valve 31D was opened in step S102. When the first discharge valve 31D is closed, the product gas filter 31A and the cooling hopper 31B are not in communication with each other, and the supply of char from the product gas filter 31A to the cooling hopper 31B is stopped.

In step S104, the control unit 90 determines whether the height of the char collected in the cooling hopper 31B accumulated in the collection container 31Bb is equal to or greater than a second predetermined height, and proceeds to step S105 if the height is equal to or greater than the second predetermined height. If the second level sensor 31J detects that the height of the char has reached the second predetermined height, the control unit 90 determines YES in step S104. If the control unit 90 determines NO in step S104, it repeats the processes of steps S102 and S103 until it determines YES in step S104.

In step S105, the control unit 90 closes the first exhaust valve 31D and the second exhaust valve 31E to form a closed space in the collection container 31Bb, and executes a pressurizing operation to supply pressurizing gas to the collection container 31Bb to pressurize the internal space of the collection container 31Bb. The control unit 90 keeps the on-off valve 31Fb open until the pressure in the internal space of the collection container 31Bb reaches a first internal pressure that is higher than atmospheric pressure, and closes the on-off valve 31Fb when the pressure in the internal space of the collection container 31Bb reaches the first internal pressure.

The control unit 90 detects the pressure in the internal space of the collection container 31Bb, for example, with a pressure sensor (not shown), and determines whether the pressure in the internal space of the collection container 31Bb has reached the first internal pressure. The control unit 90 may preset a set time for which the on-off valve 31Fb should be open until the pressure in the internal space of the collection container 31Bb reaches the first internal pressure from atmospheric pressure, and determine that the pressure in the internal space of the collection container 31Bb has reached the first internal pressure when the set time has elapsed since the on-off valve 31Fb was opened.

In step S106, the control unit 90 closes the first exhaust valve 31D and the second exhaust valve 31E to form a closed space in the collection container 31Bb, and performs a decompression operation to exhaust the pressurizing gas from the collection container 31Bb and decompress the internal space of the collection container 31Bb. The control unit 90 keeps the on-off valve 31Gc open until the pressure in the internal space of the collection container 31Bb reaches a second internal pressure (e.g., atmospheric pressure) lower than the first internal pressure from the first internal pressure, and closes the on-off valve 31Gc when the pressure in the internal space of the collection container 31Bb reaches the second internal pressure.

The control unit 90, for example, detects the pressure in the internal space of the collection container 31Bb using a pressure sensor (not shown) and determines whether the pressure in the internal space of the collection container 31Bb has reached the second internal pressure. The control unit 90 may preset a set time for which the on-off valve 31Gc should be open until the pressure in the internal space of the collection container 31Bb reaches the second internal pressure from the first internal pressure, and determine that the pressure in the internal space of the collection container 31Bb has reached the second internal pressure when the set time has elapsed since the on-off valve 31Gc was opened.

In step S107, the control unit 90 determines whether the pressurizing operation in step S105 and the depressurizing operation in step S106 have each been performed N times (N is an integer equal to or greater than 2), and if YES, the process proceeds to step S108, and if NO, the pressurizing operation in step S105 and the depressurizing operation in step S106 are repeated until step S107 returns YES. In other words, the control unit 90 alternately performs the pressurizing operation and the depressurizing operation N times each, and then proceeds to step S108.

Now, with reference to Figures 4 and 5, we will explain why the pressurization and depressurization operations are repeated alternately N times. Figure 4 is a graph showing the relationship between the time it takes to perform repeated pressurization and depressurization operations and the temperature of the char in the cooling hopper. Figure 5 is a graph showing the relationship between the time it takes to perform repeated pressurization and depressurization operations and the dilution rate of the gas in the cooling hopper.

The example shown in Fig. 4 shows a case where the initial temperature of the char recovered in the cooling hopper 31B is 420°C, the volume of the internal space of the cooling hopper 31B is ² m2, and the weight of the char that has reached the second predetermined height in the cooling hopper 31B is 50 kg, in which the pressurization operation is repeated for 40 seconds and the depressurization operation is repeated for 120 seconds. The plots shown in Fig. 4 show the timing at which the pressurization operation is started, and the interval between the plots is 160 seconds, which is the execution time of the pressurization operation and the depressurization operation.

As shown in Figure 4, by repeating the pressurization and depressurization operations, the pressurization gas to which the heat of the char has been transferred is discharged to the outside, and the temperature of the char gradually drops. In the example shown in Figure 4, by repeating one set of pressurization and depressurization operations 21 times, the temperature of the char drops from 420°C to below the natural oxidation temperature (e.g., 150°C).

For example, if the target temperature of the char in the cooling hopper 31B after cooling is to be less than 150°C, N is set to 21 in step S107. In steps S105 to S107, the control unit 90 alternately repeats the pressurizing operation by the pressurizing unit 31F and the depressurizing operation by the depressurizing unit 31G N times so that the temperature of the char in the cooling hopper 31B becomes less than 150°C, and then discharges the char from the cooling hopper 31B to the discharge hopper 31C.

In step S107, the pressurization and depressurization operations are repeated N times to determine that the temperature of the char in the cooling hopper 31B has fallen below 150°C, but other configurations are also possible. For example, when the char temperature detected by the temperature sensor 31H falls below 150°C, the control unit 90 may stop the pressurization and depressurization operations, proceed to step S108, and open the second discharge valve 31E to discharge the char collected in the collection container 31Bb of the cooling hopper 31B from the discharge line 31Bc.

As shown in FIG. 5, the pressurization gas remaining in cooling hopper 31B after depressurization is diluted by new pressurization gas introduced from pressurization section 31F, so the dilution rate gradually decreases (the dilution factor gradually increases) by repeating the pressurization and depressurization operations. Therefore, after repeating the pressurization and depressurization operations N times, the concentration of the flammable gas present in cooling hopper 31B is below the flammable range and below the environmental standard value, and is a concentration that will not cause ignition or pollution even if it is discharged to the outside.

In step S108, the control unit 90 controls the second discharge valve 31E to be open after alternately repeating the pressurizing operation by the pressurizing unit 31F and the depressurizing operation by the depressurizing unit 31G N times, and then discharges the char collected in the collection container 31Bb of the cooling hopper 31B from the discharge line 31Bc to the discharge hopper 31C.

In step S109, the control unit 90 determines whether the height of the char collected in the cooling hopper 31B accumulated in the collection container 31Bb is less than a first predetermined height, and proceeds to step S110 if the height is less than the first predetermined height. If the first level sensor 31I detects that the height of the char is less than the first predetermined height, the control unit 90 determines YES in step S109. If the control unit 90 determines NO in step S109, it repeats the process of step S109 until it determines YES in step S109.

In step S110, the control unit 90 controls the second discharge valve 31E to be closed to stop the discharge of char from the collection container 31Bb of the cooling hopper 31B to the discharge hopper 31C because the height of the char collected in the cooling hopper 31B and accumulated in the collection container 31Bb is less than the first predetermined height. After executing step S110, the control unit 90 ends the processing of this flowchart.

Here, the first internal pressure in the pressurizing operation of step S105 will be described. The first internal pressure is preferably set to 20 times or less the second internal pressure. Figure 6 is a graph showing the relationship between the pressure ratio (first internal pressure/second internal pressure), which is the ratio of the first internal pressure to the second internal pressure, and the cooling time of the char inside the cooling hopper 31B. The cooling time is the time required for the char inside the cooling hopper 31B to drop from its initial temperature of 420°C to 150°C.

As shown in FIG. 6, in the region where the pressure ratio exceeds 20, there is almost no change in the cooling time even if the pressure ratio is increased. Therefore, increasing the pressure ratio beyond 20 has almost no effect on shortening the cooling time. Therefore, in this embodiment, the first internal pressure is set to 20 times or less than the second internal pressure.

In this embodiment, the pressurization operation by the pressurization unit 31F and the depressurization operation by the depressurization unit 31G are repeated, and the char is cooled by heat transfer from the char to the pressurization gas and by discharging the pressurization gas to which the heat has been transferred. If the temperature of the char before one pressurization operation and one depressurization operation is T1, and the temperature of the char after one pressurization operation and one depressurization operation is T2, T1 and T2 satisfy the following formula (1). The pressurization gas is nitrogen gas.

a T2 ² + b T2 + c (1)
Here, a, b, and c are coefficients shown in the following expressions (2), (3), and (4).

a = Cpm G (2)
b = _CpN2 _ρN2 V [(P1-P2)/P0] Ts-T1 Cpm G
(3)
c = -T0 _CpN2 _ρN2 V [(P1-P2)/P0] Ts (4)

Here, Cpm is the specific heat of char [kJ/kg·K], G is the weight of char [kg], _CpN2 is the specific heat of nitrogen gas [kJ/kg·K], _ρN2 is the specific gravity of nitrogen gas [kg/m ³ ], V is the volume of the internal space of cooling hopper 31B [m ³ ], P1 is the first internal pressure [kPa], and P2 is the second internal pressure [kPa]. Ts is the standard temperature of 273.14 [K], and T0 is the temperature [K] of the nitrogen gas supplied to cooling hopper 31B.

The powder recovery device and the control method for the powder recovery device described in each of the above-described embodiments can be understood, for example, as follows.
A powder recovery device according to a first aspect of the present disclosure is a powder recovery device (31) that separates and recovers powder from a heated gas to be treated, the powder recovery device including a powder separation section (31A) into which the gas to be treated is introduced and which separates the powder from the gas to be treated, an introduction section (31Ba) into which the powder separated by the powder separation section is introduced, a recovery container (31Bb) that temporarily recovers the powder introduced from the introduction section, and a discharge section (31Bc) that discharges the powder recovered in the recovery container, a first recovery section (31B), a first opening/closing valve (31D) provided in the introduction section, and a second opening/closing valve (31E) provided in the discharge section. a pressurizing section (31F) that performs a pressurizing operation of supplying a pressurizing gas to the collection container to pressurize the collection container, a depressurizing section (31G) that performs a depressurizing operation of discharging the pressurizing gas from the collection container to the outside to depressurize the collection container, and a control section (90) that controls the first on-off valve, the second on-off valve, the pressurizing section, and the depressurizing section, wherein the control section controls the first on-off valve and the second on-off valve to be in a closed state so as to alternately repeat the pressurizing operation by the pressurizing section and the depressurizing operation by the depressurizing section, and then controls the second on-off valve to be in an open state so as to discharge the powder collected in the collection container from the discharge section.

In the powder recovery device according to the first aspect of the present disclosure, powder is separated from the gas to be treated that has been heated in the powder separation section and introduced into the inlet section of the first recovery section, temporarily stored in the recovery container, and then discharged from the outlet section. A first on-off valve is provided in the inlet section, and a second on-off valve is provided in the outlet section, and a closed space is formed in the recovery container of the first recovery section by closing the first on-off valve and the second on-off valve. The recovery container is pressurized with the pressurizing gas by the pressurizing section performing a pressurizing operation, and is depressurized by the depressurizing section performing a depressurizing operation to discharge the pressurizing gas.

In the powder recovery device according to the first aspect of the present disclosure, the control unit controls the first and second opening/closing valves to be in a closed state, and alternately repeats the pressurizing operation by the pressurizing unit and the depressurizing operation by the depressurizing unit. By repeating the pressurizing operation and the depressurizing operation, the pressurizing gas to which heat has been transferred from the powder in the recovery container is replaced multiple times, and the powder is gradually cooled.

In this way, according to the powder recovery device of the first aspect of the present disclosure, the powder can be cooled without providing a separate cooler, which prevents an increase in the installation cost and installation space of the powder recovery device. In addition, when the pressurizing gas in the recovery container is replaced multiple times, flammable gases adsorbed on the powder are discharged to the outside in a diluted state with the pressurizing gas, which prevents fire and pollution of the outside air.

The powder recovery device according to the second aspect of the present disclosure is the first aspect, and further includes the following configuration. That is, the control unit controls the pressurizing unit and the decompression unit so that the first internal pressure of the recovery container pressurized by the pressurizing operation is 20 times or less than the second internal pressure of the recovery container decompressed by the decompression operation.

According to the powder recovery device according to the second aspect of the present disclosure, by pressurizing the recovery container by a pressurizing operation, it is possible to reliably cool the powder recovered in the recovery container and dilute the flammable gas adsorbed to the powder. In addition, by making the first internal pressure of the recovery container pressurized by the pressurizing operation 20 times or less the second internal pressure of the recovery container depressurized by the depressurizing operation, it is possible to prevent the first internal pressure of the recovery container from being excessively high, which is unnecessary for cooling the powder or diluting the flammable gas adsorbed to the powder.

The powder recovery device according to the third aspect of the present disclosure is the first or second aspect, and further includes the following configuration: That is, the control unit controls the second on-off valve to be in an open state so that the powder recovered in the recovery container is discharged from the discharge unit after alternately repeating the pressurizing operation by the pressurizing unit and the depressurizing operation by the depressurizing unit so that the temperature of the powder becomes lower than a natural oxidation temperature.
According to the powder recovery device of the third aspect of the present disclosure, the powder recovered in the recovery container is discharged only after its temperature becomes lower than the natural oxidation temperature, thereby appropriately preventing the powder discharged at or above the natural oxidation temperature from naturally oxidizing in the atmosphere.

The powder recovery device according to the fourth aspect of the present disclosure is the third aspect, and further includes the following configuration: A detection unit (31H) that detects the temperature of the powder recovered in the powder recovery device, and the control unit controls the second on-off valve to be opened so that the powder recovered in the recovery container is discharged from the discharge unit in response to the temperature of the powder detected by the detection unit becoming lower than the natural oxidation temperature.
According to the powder recovery device of the fourth aspect of the present disclosure, the powder can be discharged from the recovery container in response to the detection unit detecting that the temperature of the powder has fallen below the natural oxidation temperature.

The powder recovery device according to the fifth aspect of the present disclosure is the third aspect, and further includes the following configuration: That is, the control unit controls the second on-off valve to be in an open state so as to discharge the powder recovered in the recovery container from the discharge unit after the pressurizing operation by the pressurizing unit and the depressurizing operation by the depressurizing unit have been performed a predetermined number of times.
According to the powder recovery device of the fifth aspect of the present disclosure, the number of repeated pressurization and depressurization operations required to reduce the temperature of the powder below the natural oxidation temperature is set to a predetermined number, and the powder that has reached a temperature below the natural oxidation temperature after the pressurization and depressurization operations have been performed a predetermined number of times can be discharged from the recovery container.

A powder recovery device according to a sixth aspect of the present disclosure is the first or second aspect, wherein the pressurizing gas has an oxygen concentration of 10% or less.
According to the powder recovery device of the sixth aspect of the present disclosure, by introducing gas having an oxygen concentration of 10% or less into the recovery container, it is possible to reliably prevent natural oxidation of high-temperature powder that comes into contact with the gas inside the recovery container.

A powder recovery device according to a seventh aspect of the present disclosure is the sixth aspect, wherein the pressurizing gas is nitrogen gas.
According to the powder recovery device of the seventh aspect of the present disclosure, by introducing nitrogen gas into the recovery container, it is possible to reliably prevent natural oxidation of high-temperature powder that comes into contact with the gas inside the recovery container.

The powder recovery device according to the eighth aspect of the present disclosure is the first or second aspect, further comprising the following configuration: That is, the pressurizing unit introduces the pressurizing gas into a recovery area (31Bd) in which the powder is recovered on the lower side of the recovery container.
According to the powder recovery device of the eighth aspect of the present disclosure, a pressurizing gas is introduced into the recovery area where the powder on the lower side of the recovery container is recovered, so that the powder is agitated by the pressurizing gas and the heat of the powder can be efficiently transferred to the pressurizing gas.

A control method for a powder recovery device according to a ninth aspect of the present disclosure is a control method for a powder recovery device that separates and recovers powder from a heated gas to be treated, the powder recovery device comprising a first recovery section having a powder separation section into which the gas to be treated is introduced and which separates the powder from the gas to be treated, an introduction section into which the powder separated by the powder separation section is introduced, a recovery container that temporarily recovers the powder introduced from the introduction section, and a discharge section that discharges the powder recovered in the recovery container, a first opening/closing valve installed in the introduction section, a second opening/closing valve installed in the discharge section, and a pressurizing gas supply to the recovery container. The system includes a pressurizing unit that supplies gas to the collection container to perform a pressurizing operation and a depressurizing unit that discharges the pressurizing gas from the collection container to the outside to perform a depressurizing operation of the collection container, and includes a pressurizing step (S105) that closes the first and second opening/closing valves to perform the pressurizing operation, a depressurizing step (S106) that closes the first and second opening/closing valves to perform the depressurizing operation by the depressurizing unit, and a discharging step (S108) that alternately repeats the pressurizing step and the depressurizing step, and then opens the second opening/closing valve to discharge the powder collected in the collection container from the discharging unit.

According to the control method for a powder recovery device according to the ninth aspect of the present disclosure, powder is separated from the gas to be treated that has been heated in the powder separation section and introduced into the inlet section of the first recovery section, temporarily stored in the recovery container, and then discharged from the outlet section. A first on-off valve is provided in the inlet section, and a second on-off valve is provided in the outlet section, and a closed space is formed in the recovery container of the first recovery section by closing the first on-off valve and the second on-off valve. The recovery container is pressurized with the pressurizing gas by the pressurizing section performing a pressurizing operation, and is depressurized by the depressurizing section performing a depressurizing operation to discharge the pressurizing gas.

According to the control method for a powder recovery device according to the ninth aspect of the present disclosure, in the discharge step, the first and second on-off valves are closed and the pressurization step and the depressurization step are alternately repeated. By repeating the pressurization and depressurization steps, the pressurizing gas to which heat has been transferred from the powder in the recovery container is replaced multiple times, and the powder is gradually cooled.

In this way, according to the control method for a powder recovery device according to the ninth aspect of the present disclosure, the powder can be cooled without providing a separate cooler, which prevents an increase in the installation cost and installation space of the powder recovery device. In addition, when the pressurizing gas in the recovery container is replaced multiple times, flammable gases adsorbed on the powder are discharged to the outside in a diluted state with the pressurizing gas, which prevents fire and pollution of the outside air.

10 Biomass gasification equipment 11 Biomass gasification furnace 12 High temperature synthesis gas cooler 14 Low temperature synthesis gas cooler 16 Char cooler 17 Feed water preheating section 18 Scrubber 30 Char recovery equipment 31 Dust collection equipment (powder recovery device)
31A Produced gas filter (powder separation section)
31Aa container 31Ab filter 31Ac lower space 31Ad upper space 31Ae backwash device 31B cooling hopper (first collection section)
31Ba introduction line (introduction section)
31Bb Collection container 31Bc Discharge line (discharge section)
31Bd Collection area 31C Discharge hopper (second collection section)
31Ca: collection container 31Cb: rotary feeder 31Cc: discharge line 31D: first discharge valve (first opening/closing valve)
31E Second exhaust valve (second opening/closing valve)
31F Pressurizing section 31Fa Pressurizing gas supply source 31Fb On-off valve 31G Pressure reducing section 31Ga Filter 31Gb Discharge line 31Gc On-off valve 31Gd Orifice 31H Temperature sensor (detection section)
31I First level sensor 31J Second level sensor 32 Supply hopper 90 Control unit

Claims

A powder recovery device that separates and recovers powder from a heated gas to be treated,
a powder separation section into which the gas to be treated is introduced and which separates the powder from the gas to be treated;
a first collection unit including an introduction unit into which the powder separated by the powder separation unit is introduced, a collection container that temporarily collects the powder introduced from the introduction unit, and a discharge unit that discharges the powder collected in the collection container;
A first on-off valve installed in the introduction portion;
A second on-off valve installed in the discharge portion;
a pressurizing unit that performs a pressurizing operation of pressurizing the collection container by supplying a pressurizing gas to the collection container;
a pressure reducing unit that performs a pressure reducing operation of reducing the pressure of the collection container by discharging the pressurizing gas from the collection container to the outside;
a control unit that controls the first on-off valve, the second on-off valve, the pressurizing unit, and the depressurizing unit,
The control unit controls the powder recovery device so that the first opening/closing valve and the second opening/closing valve are closed to alternately repeat the pressurizing operation by the pressurizing unit and the depressurizing operation by the depressurizing unit, and then the second opening/closing valve is opened to discharge the powder recovered in the recovery container from the discharge unit.
The powder recovery device according to claim 1, wherein the control unit controls the pressurizing unit and the decompression unit so that the first internal pressure of the recovery container pressurized by the pressurizing operation is 20 times or less than the second internal pressure of the recovery container decompressed by the decompression operation.
The powder recovery device according to claim 1 or claim 2, wherein the control unit alternately repeats the pressurizing operation by the pressurizing unit and the depressurizing operation by the depressurizing unit so that the temperature of the powder becomes less than the natural oxidation temperature, and then controls the second opening/closing valve to be in an open state so that the powder recovered in the recovery container is discharged from the discharge unit.
a detection unit for detecting a temperature of the powder collected in the collection container,
The powder recovery device according to claim 3, wherein the control unit controls the second opening/closing valve to an open state so as to discharge the powder recovered in the recovery container from the discharge unit when the temperature of the powder detected by the detection unit becomes lower than the natural oxidation temperature.
The powder recovery device according to claim 3, wherein the control unit controls the second opening/closing valve to be open and the powder recovered in the recovery container to be discharged from the discharge unit after the pressurizing operation by the pressurizing unit and the depressurizing operation by the depressurizing unit are each performed a predetermined number of times.
The powder recovery device according to claim 1 or 2, wherein the pressurizing gas has an oxygen concentration of 10% or less.
The powder recovery device according to claim 6, wherein the pressurizing gas is nitrogen gas.
The powder recovery device according to claim 1 or 2, wherein the pressurizing unit introduces the pressurizing gas into a recovery area below the recovery container where the powder is recovered.
A method for controlling a powder recovery device that separates and recovers powder from a heated gas to be treated, comprising the steps of:
The powder recovery device includes:
a powder separation section into which the gas to be treated is introduced and which separates the powder from the gas to be treated;
a first collection unit including an introduction unit into which the powder separated by the powder separation unit is introduced, a collection container that temporarily collects the powder introduced from the introduction unit, and a discharge unit that discharges the powder collected in the collection container;
A first on-off valve installed in the introduction portion;
A second on-off valve installed in the discharge portion;
a pressurizing unit that performs a pressurizing operation of supplying a pressurizing gas to the collection container to pressurize the collection container;
a pressure reducing unit that performs a pressure reducing operation of reducing the pressure of the collection container by discharging the pressurizing gas from the collection container to the outside,
a pressurizing step of performing the pressurizing operation with the first on-off valve and the second on-off valve in a closed state;
a depressurizing step of performing the depressurizing operation by the depressurizing unit with the first on-off valve and the second on-off valve in a closed state;
a discharge step of opening the second opening/closing valve and discharging the powder recovered in the recovery container from the discharge section after alternately repeating the pressurization step and the depressurization step.