JP4800569B2 - Fuel gas production apparatus and fuel gas production method - Google Patents

Description

  The present invention relates to a method for producing fuel gas from a reaction mixture obtained by reacting organic waste in supercritical water or subcritical water.

As a technique for treating fuel sludge such as sewage sludge, waste water such as domestic waste water or industrial waste water, organic waste such as food residue or hay, and producing fuel gas, for example, a method for producing fuel gas shown in Patent Document 1 There is.
In Patent Document 1, a liquid gas is hydrothermally reacted in supercritical water or subcritical water in a reaction tower to produce a fuel gas containing hydrogen as a main component. Then, in the hydrothermal reaction tower, a gas-liquid mixed phase is formed from the liquid organic substance, and this gas-liquid mixed phase is separated into a gas phase mainly composed of hydrogen and the remaining reaction liquid (liquid phase) in a cooling device. To do. Thereafter, hydrogen sulfide (H ₂ S) is removed from the gas phase to produce a fuel gas mainly composed of hydrogen.
According to the method for producing fuel gas of Patent Document 1, organic waste can be treated with high gasification efficiency and can be reused as fuel gas.

However, in the conventional method for producing fuel gas, it is necessary to use an adsorbent such as ZnS in order to remove hydrogen sulfide from the gas phase. Therefore, it is not considered to produce fuel gas by removing hydrogen sulfide without using a catalyst such as an adsorbent. Further, no consideration is given to removing ammonia (NH ₃ ) from the gas phase.

JP 2002-105466 A

  The present invention has been made in view of such conventional problems, and removes almost the entire amount of hydrogen sulfide and ammonia from the gas phase without using a catalyst such as an adsorbent, and the gas phase in the reaction mixture has. An object of the present invention is to provide a fuel gas production method capable of efficiently producing fuel gas using temperature and pressure.

A first aspect of the present invention is a reaction tower for obtaining a reaction mixture by reacting organic waste in supercritical water or subcritical water;
A cooler for supplying the reaction mixture from the reaction tower, cooling the reaction mixture, and starting gas-liquid separation;
A gas-liquid separation tank that is supplied with a reaction mixture subjected to gas-liquid separation from the cooler and forms a gas phase component at the upper portion and a liquid phase component at the lower portion for gas-liquid separation;
By injecting absorption water into the gas phase component supplied from the gas-liquid separation tank, the absorption water is brought into contact with the gas phase component, and carbon dioxide, hydrogen sulfide and An absorption tower for absorbing and removing ammonia;
A primary diffusion tank that introduces the liquid phase separated in the gas-liquid separation tank under reduced pressure , diffuses and removes carbon dioxide and hydrogen sulfide from the liquid phase, and discharges waste water containing ammonia in water; ,
The carbon dioxide in the absorption tower is introduced under reduced pressure the primary absorbent removing water which is absorbed water after the absorption removal of hydrogen sulfide and ammonia, removal of carbon dioxide and hydrogen sulfide from said primary absorption free water and a second spreading tank for discharging the secondary absorbent removing water comprising ammonia,
An ammonia removal device for removing ammonia from the secondary absorption and removal water supplied from the secondary diffusion tank;
A pump for transferring water after the removal of the ammonia supplied from the ammonia removal device to the absorption tower as the absorption water;
Carbon dioxide know the vapor phase in the absorption tower, and the fuel gas removal line for taking out fuel gas after removal of hydrogen sulfide and ammonia,
Carbon dioxide separated respectively in the first spreading tank and said second spreading tank, and the off-gas exhaust line for exhausting the hydrogen sulfide,
A fuel gas production apparatus having a circulation line for transferring the absorption water to the absorption tower by the pump (claim 1).
Further, the second aspect of the present invention is a cooling step of cooling a reaction mixture obtained by reacting organic waste in supercritical water or subcritical water using the fuel gas production apparatus,
A gas-liquid separation step in which in the gas-liquid separation tank, the cooled reaction mixture is gas-liquid separated into a gas phase component and a liquid phase component containing hydrogen sulfide and ammonia;
In the absorption tower, by bringing the gas phase into contact with water for absorption, an absorption step of absorbing and removing hydrogen sulfide and ammonia remaining in the gas phase into the water for absorption is performed. A fuel gas production method is characterized in that the fuel gas is produced (claim 2).

In the present invention, the cooling step and the gas-liquid separation step are performed, and the cooled reaction mixture is gas-liquid separated into the gas phase and the liquid phase in a gas-liquid separation tank. At this time, most of the hydrogen sulfide and ammonia contained in the reaction mixture are transferred to the liquid phase, and part of the hydrogen sulfide and ammonia remain in the gas phase.
Then, the absorption step is performed, and the gas phase component is brought into contact with the absorption water in the absorption tower, whereby hydrogen sulfide and ammonia remaining in the gas phase component are absorbed and removed by the absorption water.

The reaction mixture obtained by reacting the organic waste in supercritical water or subcritical water has high temperature and high pressure energy. In the absorption step, the reaction mixture is subjected to the gas-liquid separation. By utilizing the temperature and pressure of the gas phase component in, hydrogen sulfide and ammonia can be absorbed and removed by the water for absorption.
Therefore, according to the present invention, almost all of the hydrogen sulfide and ammonia are removed from the gas phase component without using a catalyst such as an adsorbent, and the temperature and pressure of the gas phase component in the reaction mixture are utilized to make the fuel Gas can be produced efficiently.

A preferred embodiment of the present invention described above will be described.
The fuel gas produced in the present invention can be a fuel gas containing at least one of hydrogen and methane.
Examples of the organic waste include sludge such as sewage sludge, wastewater such as domestic wastewater or industrial wastewater, food residue or hay.

The reaction performed in the supercritical water or subcritical water can be performed in a reaction tower that generates the reaction mixture from water and the organic waste, and the cooling of the reaction mixture is performed between the reaction tower and the gas-liquid. It can carry out in the cooler provided between the separation tanks.
The gas-liquid separation performed in the gas-liquid separation tank in the gas-liquid separation step can be performed at a temperature of 20 to 50 ° C. and a pressure of 2 to 50 MPa · G.

The cooling of the reaction mixture performed in the cooling step can lower the temperature of the reaction mixture by 150 ° C. or more. And the temperature in a gas-liquid separation tank can be made 150 degreeC or more lower than the temperature in the said reaction tower.
Moreover, in the absorption tower in the absorption step, hydrogen sulfide and ammonia can be absorbed and removed by the absorption water without reheating the gas phase component sent from the gas-liquid separation tank. The gas phase temperature and pressure in the absorption tower can be made substantially the same as the gas phase temperature and pressure in the gas-liquid separation tank. Moreover, the temperature of the said water for absorption supplied to an absorption tower can be 20-50 degreeC.
Moreover, in the absorption tower in the absorption step, when the gas phase component is brought into contact with the absorption water, carbon dioxide and the like can be absorbed and removed from the gas phase component.

The reaction in the supercritical water or subcritical water is preferably performed in water having a temperature of 200 ° C. or higher and a pressure of 2 MPa · G or higher.
Further, when the reaction is performed in the absence of a catalyst, the reaction is performed in water having a temperature of 300 ° C. or higher (more preferably 350 ° C. or higher) and a pressure of 10 MPa · G or higher (more preferably 15 MPa · G or higher). Preferably it is done.

On the other hand, when the reaction is performed in the presence of a catalyst, the reaction is performed in water at a temperature of 200 ° C. or higher (more preferably 250 ° C. or higher) and a pressure of 2 MPa · G or higher (more preferably 5 MPa · G or higher). It is preferable.
In this case, as the catalyst, for example, at least one of titanium oxide, zirconium oxide, a mixture of these oxides, or a titanium-zirconia composite oxide can be used.

Further, the above reaction is preferably carried out at a liquid standard space velocity (reactor inlet standard) in the reaction tower of 0.5 to 1000 hr ⁻¹ . The liquid reference space velocity in the reaction tower is a reaction that has a long shape, supplies water and organic waste from one end in the long direction, and advances the reaction toward the other end in the long direction. In the tower, when the amount of water and organic waste fed into the reaction tower is Q [cm ³ / hr] and the volume of the reaction part of the reaction tower is V [cm ³ ], it is represented by Q / V. It means the speed.
In addition, the upper limit values of the temperature and pressure at which the reaction is performed can be a temperature of 800 ° C. or lower and a pressure of 50 MPa · G or lower.

The critical point of water has a temperature of 374 ° C. or higher and a pressure of 22.1 MPa · G, and the supercritical water refers to water having a temperature and pressure higher than the critical point of water. . In this supercritical water, there is no distinction between a gas phase and a liquid phase, and a supercritical water reaction mainly including a hydrolysis reaction is performed.
On the other hand, the subcritical water refers to water having a temperature and pressure close to the critical point and lower than the critical point of the water. In the subcritical water, a gas phase and a liquid phase are formed, and a hydrothermal reaction involving a hydrolysis reaction in the liquid phase, such as a thermal decomposition reaction in the gas phase, is performed.

Moreover, in the said absorption tower, the said water for absorption is injected into the said gaseous-phase component .
Thereby , in the said absorption tower, the said water for absorption and the said gaseous phase component can be made to contact effectively, and the absorption efficiency of hydrogen sulfide and ammonia to the water for absorption can be improved.

Further, the absorption water in which the hydrogen sulfide and ammonia are absorbed is circulated to the absorption tower again after removing the hydrogen sulfide and ammonia .
Thereby , the said water for absorption can be used repeatedly and the manufacturing efficiency of fuel gas can be improved.

Hereinafter, an embodiment according to the method for producing fuel gas of the present invention will be described with reference to FIG.
Example 1
As shown in FIG. 1, in the manufacturing method of the fuel gas F of this example, the cooling process which cools the reaction mixture R obtained by making the organic waste A react in supercritical water or subcritical water, and a gas-liquid separation tank 4, the gas-liquid separation step of separating the cooled reaction mixture R into a gas phase G containing hydrogen and methane and a liquid phase L containing hydrogen sulfide and ammonia, etc. Do.
Thereafter, in the production method, in the absorption tower 5, the gas phase component G is brought into contact with the water W for absorption, whereby carbon dioxide in the gas phase component G and hydrogen sulfide remaining in the gas phase component G are obtained. Then, an absorption step of absorbing and removing ammonia and the like in the absorption water W is performed, and a fuel gas F containing hydrogen and methane is produced from the gas phase component G.
This will be described in detail below.

In this example, as shown in FIG. 1, when producing the fuel gas F, a fuel gas production apparatus 1 having the following reaction tower 2, cooler 3, gas-liquid separation tank 4, absorption tower 5 and the like is used. Use.
The reaction tower 2 reacts the organic waste A in supercritical water or subcritical water to obtain a reaction mixture R. The reaction tower 2 of this example has a long shape, and supplies water and organic waste A from one end in the long direction, and advances the reaction toward the other end in the long direction. Further, in this example, the organic waste A contains water, and the organic waste A containing this water is supplied to the reaction tower 2, and the inside of the reaction tower 2 is elevated until the water reaches a supercritical state. Warm and conduct a supercritical water reaction. The reaction tower 2 can be supplied with organic waste A and water.

The cooler 3 supplies (transfers) the reaction mixture R from the reaction tower 2, cools the reaction mixture R, and starts gas-liquid separation.
The gas-liquid separation tank 4 is cooled (cooled) by the cooler 3 and supplied (transferred) to the reaction mixture R which has been subjected to gas-liquid separation. A gas phase component G is formed above and a liquid phase component L is formed below and gas-liquid separation is performed.
The absorption tower 5 is supplied (transferred) with the gas phase component G from the gas-liquid separation tank 4, and the absorption water W is brought into contact with the gas phase component G by injecting the absorption water W into the gas phase component G. The absorption water W absorbs and removes carbon dioxide, hydrogen sulfide, ammonia and the like in the gas phase G.
The absorption water W refers to water for absorbing and removing hydrogen sulfide and ammonia.

  As shown in FIG. 1, the absorption tower 5 of the present example is configured to inject the absorption water W into the gas phase component G. That is, an injection nozzle 51 for injecting the absorption water W is disposed in the upper portion of the absorption tower 5, and the absorption water W injected from the injection nozzle 51 includes carbon dioxide, hydrogen sulfide, and It absorbs ammonia and the like and descends in the absorption tower 5.

Further, the fuel gas production apparatus 1 of the present example includes a primary diffusion tank 61 to which the liquid phase L in the gas-liquid separation tank 4 is transferred, and absorption of carbon dioxide, hydrogen sulfide, ammonia and the like in the absorption tower 5. And a secondary diffusion tank 62 to which primary absorption removal water, which is absorption water W after removal, is transferred.
The primary diffusion tank 61 introduces the liquid phase component L separated in the gas-liquid separation tank 4 under reduced pressure, diffuses and removes carbon dioxide, hydrogen sulfide, and the like therefrom, and contains wastewater containing ammonia and the like in water. Are to be discharged. The secondary diffusion tank 62 introduces the primary absorption removal water in the absorption tower 5 under reduced pressure, removes carbon dioxide, hydrogen sulfide, and the like therefrom, and contains secondary absorption removal water containing ammonia and the like. Are to be discharged.

The reaction tower 2 and the gas-liquid separation tank 4 are connected by a cooling line 801 through which the reaction mixture R flows, and the cooler 3 is disposed in the cooling line 801.
The gas-liquid separation tank 4 and the absorption tower 5 are connected by a gas phase transfer line 802 through which the gas phase G formed in the gas-liquid separation tank 4 flows.
Further, the gas-liquid separation tank 4 and the primary diffusion tank 61 are connected by a liquid phase transfer line 803 through which the liquid phase L formed in the gas-liquid separation tank 4 flows.
The absorption tower 5 and the secondary diffusion tank 62 are connected by a primary absorption / removal water transfer line 806 through which the primary absorption / removal water flows.

Further, the absorption tower 5 includes a fuel gas extraction line 804 for extracting the fuel gas F after removing almost all of the hydrogen sulfide and ammonia from the gas phase component G, and the absorption tower 5 includes the absorption water W. An absorption water supply line 805 for supplying water is connected.
Further, the fuel gas F taken out from the fuel gas take-out line 804 is taken out of the fuel gas production apparatus 1 as a product gas.
The primary diffusion tank 61 has an off-gas exhaust line 808A for exhausting carbon dioxide, hydrogen sulfide, etc. separated in the primary diffusion tank 61, and waste water separated in the primary diffusion tank 61. A wastewater discharge line 809 to be discharged is connected.

The secondary diffusion tank 62 includes an off-gas exhaust line 808B for exhausting carbon dioxide, hydrogen sulfide, etc. separated in the secondary diffusion tank 62, and the primary absorption removal in the secondary diffusion tank 62. A secondary absorption removal water extraction line 807 for taking out secondary absorption removal water after removing carbon dioxide, hydrogen sulfide, and the like from water is connected.
Carbon dioxide, hydrogen sulfide, and the like exhausted from the off-gas exhaust lines 808A and 808B are exhausted to the outside of the fuel gas production apparatus 1 as off-gas.

Further, as shown in FIG. 1, the fuel gas production apparatus 1 removes the hydrogen sulfide and ammonia from the primary absorption removal water, and then uses the water after the removal as the absorption water W again. It is configured to circulate in the absorption tower 5.
That is, the secondary absorption removal water extraction line 807 connected to the secondary diffusion tank 62 and the absorption water supply line 805 connected to the absorption tower 5 are connected via the circulation line 810. The circulation line 810 includes a cooling device 71 for cooling the secondary absorption removal water sent from the secondary diffusion tank 62, an ammonia removal device 72 for removing ammonia from the secondary absorption removal water, and removal of the ammonia. And a pump 73 for transferring the water after performing the above operation to the absorption tower 5 as the absorption water W.

  The cooling device 71 is connected to a diffusion gas exhaust line 811 for exhausting the diffusion gas generated when the secondary absorption removal water is cooled. The diffusion gas is exhausted to the outside of the fuel gas production apparatus 1 through the diffusion gas exhaust extraction line 811.

Next, a method for producing a fuel gas F containing hydrogen and methane by performing a reaction process, a cooling process, a gas-liquid separation process, and an absorption process using the fuel gas production apparatus 1 will be described in detail.
As shown in FIG. 1, in the production of the fuel gas F, first, as the reaction step, sewage sludge containing water is supplied as organic waste A to the reaction tower 2 to bring the water into a supercritical state. To perform supercritical water reaction. The supercritical water reaction of this example is carried out under conditions where the temperature is 200 to 800 ° C., the pressure is 2 to 50 MPa, and the liquid standard space velocity in the reaction tower 2 is 0.5 to 1000 hr ⁻¹ .
And in the said reaction tower 2, a hydrolysis reaction etc. occur and the reaction mixture R in the state by which each component contained in the organic waste A in water was gasified is produced | generated.

  Next, as the cooling step, the reaction mixture R is transferred to the cooler 3 through the cooling line 801, and in the cooler 3, the reaction mixture R is cooled to 20 to 50 ° C. The pressure of the reaction mixture R is set to 2 to 50 MPa · G. Further, the cooled reaction mixture R is in a state where gas-liquid separation is performed, and is transferred to the gas-liquid separation tank 4 via the cooling line 801.

  Next, as the gas-liquid separation step, the cooled reaction mixture R sent from the cooler 3 in the gas-liquid separation tank 4 includes hydrogen, methane, carbon monoxide, nitrogen, hydrogen sulfide, ammonia, and the like. Gas-liquid separation is performed into a gas phase component G and a liquid phase component L containing water, hydrogen sulfide, ammonia, and the like. When this gas-liquid separation is performed, most of the hydrogen sulfide and ammonia contained in the reaction mixture R are transferred to the liquid phase L, and a part of the hydrogen sulfide and ammonia remain in the gas phase G. To do.

The gas phase component G in the gas-liquid separation tank 4 is transferred to the absorption tower 5 via the gas phase component transfer line 802.
On the other hand, the liquid phase L in the gas-liquid separation tank 4 is depressurized via the liquid phase transfer line 803 and transferred to the primary diffusion tank 61. In the primary diffusion tank 61, carbon dioxide, hydrogen sulfide, and the like diffused and removed from the liquid phase L are exhausted from the off-gas exhaust line 808A, and the remaining liquid phase L is used as waste water as the waste water discharge line. It is discharged from 809.

  Next, as the absorption step, in the absorption tower 5, the absorption water W is injected from the injection nozzle 51, and the absorption water W is brought into contact with the gas phase component G sent from the gas-liquid separation tank 4. At this time, carbon dioxide, hydrogen sulfide, and ammonia contained in the gas phase component G are absorbed into the absorption water W. Then, carbon dioxide, hydrogen sulfide and ammonia are removed from the gas phase component G.

In the absorption tower 5, the absorption water W and the gas phase component G can be effectively brought into contact with each other by the injection of the absorption water W from the injection nozzle 51, and carbon dioxide, hydrogen sulfide, and ammonia are supplied to the absorption water W. It is possible to increase the absorption efficiency.
Thereafter, the gas phase G after the absorption and removal is supplied from a fuel gas extraction line 804 connected to the absorption tower 5 to a fuel gas F (product gas) containing hydrogen, methane, carbon monoxide, nitrogen and the like. As taken out.

Thus, the fuel gas F containing hydrogen and methane can be produced from the gas phase G after the absorption removal.
The primary absorption / removed water from which hydrogen sulfide and ammonia have been absorbed and removed is decompressed via the primary absorption / removed water transfer line 806 and sent to the secondary diffusion tank 62. In the secondary diffusion tank 62, carbon dioxide, hydrogen sulfide, etc. diffused and removed from the primary absorption removal water are exhausted from the off-gas exhaust line 808B, and the remaining primary absorption removal water is secondary absorbed. It is sent to the cooling device 71 from the secondary absorption removed water extraction line 807 as removed water.

  Then, the secondary absorption removed water passes through the cooling device 71 and the ammonia removal device 72, and then again becomes the absorption water W by the pump 73 via the circulation line 810 and the absorption water supply line 805. It is sent to the absorption tower 5. Therefore, the absorption water W supplied to the absorption tower 5 is repeatedly circulated in the fuel gas production apparatus 1, and the energy efficiency for producing the fuel gas F can be improved.

  In the method for producing the fuel gas F of this example, as described above, the absorption step is performed after the gas-liquid separation step. Therefore, most of the carbon dioxide from the gas phase component G can be absorbed and removed by the absorption water W, and almost all the hydrogen sulfide and ammonia remaining in the gas phase component G are removed from the absorption water W. Can be absorbed and removed.

The reaction mixture R obtained by reacting the organic waste A in supercritical water or subcritical water has high temperature and high pressure energy.
And in the said absorption tower 5, without giving energy of temperature and pressure with respect to the gaseous-phase part G sent from the said gas-liquid separation tank 4, (without reheating), from the said gas-liquid separation tank 4 Using the temperature and pressure of the gas phase component G to be sent as it is, it is possible to absorb and remove unnecessary substances such as carbon dioxide, hydrogen sulfide and ammonia in the absorption water W. Further, in the absorption tower 5, the unnecessary substance can be removed from the gas phase component G only by using water as the absorption water W.

  Therefore, according to the method for producing the fuel gas F of this example, the carbon dioxide, the sulfide can be efficiently produced without using a catalyst such as an adsorbent and without applying energy such as temperature and pressure from the outside. Hydrogen and ammonia can be removed. Then, almost all the hydrogen sulfide and ammonia are removed from the gas phase component G, and the fuel gas F containing hydrogen and methane can be efficiently produced.

(Example 2)
This example assumes the composition of the organic waste A and confirms the above production method in order to confirm the excellent effect in the production method of the fuel gas F using the fuel gas production apparatus 1 shown in Example 1 above. It is the example which simulated the composition of the fuel gas F obtained when implemented.
That is, the organic waste A of this example has ash content: 15 wt%, C (carbon); 43.6 wt%, H (hydrogen); 6.8 wt%, O (oxygen); 28.0 wt%, N (nitrogen) 5.9 wt%, S (sulfur); 0.7 wt%.
And in the said reaction tower 2, it reacts in the said supercritical water on the conditions of temperature; 600 degreeC and pressure; 35 Mpa * G, In the said gas-liquid separation tank 4, temperature; 50 degreeC, pressure; 15 Mpa * G The gas-liquid separation was performed under the conditions described above. Moreover, the injection amount of the water for absorption W to the absorption tower 5 was 894.4 kmol / hr.

  Table 1 shows the result of the simulation. In the same table, the gas composition of the reaction mixture R in the reaction tower 2, the gas composition of the gas phase G in the gas-liquid separation tank 4, the gas composition of the fuel gas F (product gas) taken out from the absorption tower 5 and The gas composition etc. of the off-gas exhausted from the said primary diffusion tank 61 and the secondary diffusion tank 62 are shown.

  In the same table, when decarboxylation (high-pressure absorption removal of carbon dioxide into the absorption water W in the absorption tower 5) is performed so that the concentration of carbon dioxide in the fuel gas F is 1 mol% or less, It can be seen that the concentration of hydrogen sulfide and the concentration of ammonia can be almost 0 ppm. As for hydrogen sulfide, about 65% is dissolved and removed in the liquid phase in the gas-liquid separation tank 4, and the remaining about 35% is absorbed and removed in the absorption tower 5. As for ammonia, 99% is dissolved and removed in the liquid phase in the gas-liquid separation tank 4, and the remaining less than 1% is absorbed and removed in the absorption tower 5.

Thus, as the product gas, CH ₄ (methane); about 41 mol%, H ₂ (hydrogen); about 52 mol%, N ₂ (nitrogen); about 5 mol%, CO (carbon monoxide); about 1 mol%, CO ₂ (carbon dioxide): It was found that fuel gas F having a composition of about 1 mol% can be produced.
As described above, if the method for producing the fuel gas F of Example 1 is used, almost all the amounts of hydrogen sulfide and ammonia are removed from the gas phase G subjected to the gas-liquid separation, and the gas phase G has the gas G. It has been found that fuel gas F containing hydrogen and methane can be efficiently produced using temperature and pressure.

Explanatory drawing which shows the structure of the fuel gas manufacturing apparatus in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel gas production apparatus 2 Reaction tower 3 Cooler 4 Gas-liquid separation tank 5 Absorption tower 51 Injection nozzle 61 Primary diffusion tank 62 Secondary diffusion tank A Organic waste R Reaction mixture G Gas phase component L Liquid phase component W Absorption water F Fuel gas

Claims (3)

A reaction tower for reacting organic waste in supercritical water or subcritical water to obtain a reaction mixture;
A cooler for supplying the reaction mixture from the reaction tower, cooling the reaction mixture, and starting gas-liquid separation;
A gas-liquid separation tank that is supplied with a reaction mixture subjected to gas-liquid separation from the cooler and forms a gas phase component at the upper portion and a liquid phase component at the lower portion for gas-liquid separation;
By injecting absorption water into the gas phase component supplied from the gas-liquid separation tank, the absorption water is brought into contact with the gas phase component, and carbon dioxide, hydrogen sulfide and An absorption tower for absorbing and removing ammonia;
A primary diffusion tank that introduces the liquid phase separated in the gas-liquid separation tank under reduced pressure , diffuses and removes carbon dioxide and hydrogen sulfide from the liquid phase, and discharges waste water containing ammonia in water; ,
The carbon dioxide in the absorption tower is introduced under reduced pressure the primary absorbent removing water which is absorbed water after the absorption removal of hydrogen sulfide and ammonia, removal of carbon dioxide and hydrogen sulfide from said primary absorption free water and a second spreading tank for discharging the secondary absorbent removing water comprising ammonia,
An ammonia removal device for removing ammonia from the secondary absorption and removal water supplied from the secondary diffusion tank;
A pump for transferring water after the removal of the ammonia supplied from the ammonia removal device to the absorption tower as the absorption water;
Carbon dioxide know the vapor phase in the absorption tower, and the fuel gas removal line for taking out fuel gas after removal of hydrogen sulfide and ammonia,
Carbon dioxide separated respectively in the first spreading tank and said second spreading tank, and the off-gas exhaust line for exhausting the hydrogen sulfide,
And a circulation line for transferring the absorption water to the absorption tower by the pump. Using the fuel gas production apparatus according to claim 1,
A cooling step of cooling a reaction mixture obtained by reacting organic waste in supercritical water or subcritical water;
A gas-liquid separation step in which in the gas-liquid separation tank, the cooled reaction mixture is gas-liquid separated into a gas phase component and a liquid phase component containing hydrogen sulfide and ammonia;
In the absorption tower, by bringing the gas phase into contact with water for absorption, an absorption step of absorbing and removing hydrogen sulfide and ammonia remaining in the gas phase into the water for absorption is performed. A method for producing fuel gas, characterized by producing fuel gas.   3. The fuel gas according to claim 2, wherein the reaction mixture is generated at a pressure of 15 to 50 MPa · G, and the reaction mixture is supplied to the gas-liquid separation tank at a pressure of 15 to 50 MPa · G. Production method.

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