JP2007146066A - Fuel gas production system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel gas production system capable of obtaining a high-calory fuel gas by using an organic waste as a raw material. <P>SOLUTION: The fuel gas production system uses a water-containing organic waste such as sewage dewatered sludge as a raw material and the system is equipped with a high-temperature and high-pressure solubilizing part 1 for solubilizing the organic waste to a water-soluble organic material and a high-temperature and high-pressure gasifying part 2 for converting the solubilized water-soluble to a fuel gas. In the system, the rear end of the solubilizing part 1 is integrally connected through a filter 7 passing through only gas and liquid to the top of the gasifying part. The gas and the liquid discharged from the solubilizing part 1 are directly charged into the gasifying part 2 and a solid-like insolubilized material is taken out to the outside and dehydrated by a dehydrating machine 11 and burned in a hot air-generating furnace 12 and is used as an outside heat source for the gasifying part 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel gas production system which obtains fuel gas by decomposing at high temperature and high pressure using water-containing organic waste such as sewage sludge as a raw material.

  It has been conventionally known that organic components such as sewage sludge are decomposed under high temperature and high pressure conditions and converted into fuel gas such as methane and hydrogen as disclosed in Patent Document 1, for example. In order to increase the yield of fuel gas, it is necessary to suppress the oxygen ratio. However, water-containing organic waste is decomposed and processed into fuel gas under high temperature and high pressure conditions of 5 to 15 MPa and 300 to 600 ° C. In this case, there is a problem that the pyrolysis of the organic component proceeds and a hardly decomposable char is generated.

For example, when dehydrated sewage sludge is gasified under the conditions of 15 MPa, 520 ° C., and oxygen ratio of 0.5, about 15% of the input carbon is included in the residue and discharged as hardly decomposable char. If the oxygen ratio is 1.2, the input carbon is decomposed 100% and char is not generated, but the produced gas is only CO ₂ and fuel gas cannot be obtained. If the oxygen ratio is 0.7, the calorie of the fuel gas is reduced by 44% compared to the case where the oxygen ratio is 0.5. As described above, if the calorie of the fuel gas is increased, the amount of carbon discharged as char increases, and the carbon gasification rate cannot be increased.

  In order to solve this problem, a method for increasing the carbon gasification rate by pretreating sewage sludge has been studied. For example, when dehydrated sludge is pretreated at 10 MPa and 250 ° C., the organic matter in the sludge is rapidly decomposed and reduced in molecular weight by the action of liquid phase water having a maximum hydrolyzing power. Thus, if it introduce | transduces into a gasification part after making it low molecular, since the activation energy required for gasification will fall, it is anticipated that the ratio of the carbon which remains in a residue will fall.

  However, the rate of hydrolysis is extremely rapid and the organic content is not evenly distributed in the sewage sludge. Therefore, hydrolysis is applied to 100% of organic substances, and further secondary decomposition and repolymerization are performed. It is difficult to stop the reaction before it occurs. For example, even if it takes about 1 hour for temperature increase and about 2 hours for temperature decrease, only about 35% of the total carbon in the sewage sludge is solubilized, and about 45% is discharged as a residue.

  This residue includes char generated by thermal decomposition before being hydrolyzed, organic matter that has been solubilized, but has lost its hydrophilicity due to secondary decomposition, and organic matter that has become larger due to re-polymerization. It is assumed that Thus, it is not easy to increase the solubilization rate even if pretreatment is performed.

As a solution to the above-described problem, Patent Document 2 describes a system that solubilizes and dehydrates biomass and uses this as an external heat source of a gasification reaction apparatus. As a result, the oxygen ratio can be suppressed and high-calorie fuel gas can be recovered. However, in this system, since a solid-liquid separation mechanism and a press-fitting pump are arranged between the solubilizing part and the gasifying part, the high-pressure solubilized liquid discharged from the solubilizing part is once released and cooled. Therefore, it is necessary to separate into solid and liquid and then press into the gasification reactor again. For this reason, there is a problem in that energy loss is large and a press-fitting pump is required for each of the solubilization part and the gasification part.
JP 2005-205252 A Japanese Patent No. 2961247

  The present invention solves the above-mentioned conventional problems, can obtain a high-calorie fuel gas from organic waste as a raw material, has a high carbon gasification rate, low energy loss, and requires a plurality of press-fitting pumps. An object of the present invention is to provide a fuel gas production system that does not.

  The present invention made to solve the above-mentioned problems is a fuel gas production system using water-containing organic waste as a raw material, and a high-temperature and high-pressure solubilization section for solubilizing organic waste into water-soluble organic matter, A high-temperature and high-pressure gasification unit that converts the solubilized water-soluble organic substance into fuel gas, and the solubilization unit and the gasification unit are integrally connected through a filter that allows only gas and liquid to pass through. It is characterized by being.

  The temperature of the solubilizing part is 80 to 400 ° C., preferably 200 to 350 ° C., the pressure is equal to or higher than the saturated vapor pressure of water at the temperature, and the temperature of the gasifying part is 200 to 650 ° C., preferably 450 It is ˜650 ° C. and the pressure is below the critical pressure of water, desirably 4 to 15 MPa.

  Also, a non-solubilized product generated in the solubilized part is taken out in a form mixed with a part of the solubilized product, and a separation mechanism for dehydrating and separating is provided, and a scraping mechanism for the non-solubilized product attached to the filter is provided. In addition, it is possible to employ a configuration in which the non-solubilized product separated by the separation mechanism is used as a heat source for the solubilization part or the gasification part, or a catalyst for promoting gasification is supported on the filter.

  According to the present invention, since the solubilization part and the gasification part are integrally connected via the filter that allows only gas and liquid to pass through, insoluble organic substances are not introduced into the gasification part. For this reason, the oxygen ratio of the gasification part can be lowered, the combustion of organic matter can be suppressed, a high-calorie fuel gas can be obtained, and the carbon gasification rate can be increased. Further, according to the present invention, unlike the patent document 2, the solubilizing part and the gasifying part are integrated, so that it is not necessary to lower the pressure / temperature for solid-liquid separation and increase it again. Therefore, only one press-fitting pump is required and energy loss is small.

Hereinafter, preferred embodiments of the present invention will be described.
In FIG. 1, reference numeral 1 denotes a solubilizing part made of a pressure-resistant cylindrical body, and 2 denotes a gasifying part made of a pressure-resistant cylindrical body. The solubilization part 1 is provided with the jacket 3 for external heating, The inside is 80-400 degreeC, Preferably it is 200-350 degreeC, and the pressure is maintained more than the saturated vapor pressure of the water in the said temperature. Water-containing organic waste such as sewage dewatered sludge is pressed into the inlet of the solubilizing unit 1 by the press-fitting pump 4, and the inside of the solubilizing unit 1 is gradually moved toward the gasifying unit 2 by the spiral feed blade 5. It is solubilized in water-soluble organic matter while being transferred. In addition, it is preferable to add an alkali to the solubilization part 1 in order to promote solubilization.

  The gasification unit 2 is a high-temperature and high-pressure unit for converting solubilized water-soluble organic substances into fuel gas, and is formed of a pressure-resistant cylindrical body having a jacket 3 for external heating similar to the solubilization unit 1. . The inside is 200 to 650 ° C., preferably 450 to 650 ° C., and the pressure is maintained below the critical pressure of water, preferably 4 to 15 MPa. A spiral feed blade 6 is also provided inside the gasification unit 2.

  In the present invention, the rear end of the solubilization unit 1 and the front end of the gasification unit 2 are integrally connected via a filter 7 that allows only gas and liquid to pass through. The filter 7 can be a sintered metal filter or a ceramic filter that does not corrode even in the above-described high temperature and high pressure state and can maintain strength. Thus, since the solubilization part 1 and the gasification part 2 are connected via the filter 7 which can pass gas and a liquid, both pressure becomes substantially the same, for example, the solubilization part 1 is 10 MPa. The gasification section 2 has a pressure of about 9 MPa which is lower by the differential pressure of the filter 7.

  As described above, the water-containing organic waste is solubilized in the water-soluble organic substance and gas by the solubilizing unit 1, but a part thereof becomes a solid insolubilized product and is separated by the filter 7. The water-soluble organic substance and gas enter the gasification section 2 while being in a high temperature and high pressure state, and are gasified at a higher temperature to be converted into a fuel gas such as methane or hydrogen. In the present invention, since the rear end of the solubilizing unit 1 and the front end of the gasifying unit 2 are directly connected, unlike the method of Patent Document 2, energy loss is small, and only one press-fitting pump 4 is required. If the filter 7 is loaded with a catalyst for promoting gasification, it can be more efficiently gasified.

  On the other hand, a mechanical scraping mechanism 8 for removing non-solubilized material adhering to the surface of the filter 7 is provided on the solubilizing part 1 side of the filter 7. The solubilized product is discharged to the outside through the double valves 9 and 9 while being mixed with a part of the solubilized product. A cooler 10 and a dehydrator 11 are provided below the double valves 9 and 9 to cool and dehydrate the non-solubilized material and the solubilized material discharged from the filter 7. As the dehydrator 11, for example, a centrifugal dehydrator or a belt press can be used.

  As described above, the non-solubilized product dehydrated by the dehydrator 11 includes the char generated by thermal decomposition before being subjected to hydrolysis, the organic matter precipitated by losing the hydrophilicity by secondary decomposition of what was once solubilized, It contains organic matter that has grown due to repolymerization and has a large amount of carbon. Then, this is burned in the hot-air generator 12, and the high-temperature exhaust gas is sent to the jacket 3 of the gasification unit 2 and used for external heating of the gasification unit 2. Thereby, the carbon contained in the organic waste can be effectively used. Since the separated water is a small amount, it may be mixed with water-containing organic waste and sent to the press-in pump 4.

  Thus, since the water-soluble organic substance solubilized is gasified in the gasification part 2, an oxygen ratio can be restrained low. In addition, since the tar content etc. and solid residue which were not gasified also generate | occur | produce in this gasification part 2, gas and residue waste liquid are isolate | separated with the gas-solid-liquid separator 13 provided in the exit side of the gasification part 2, The gas is taken out from the pressure reducing valve 14 and used as fuel gas.

  In the fuel gas production system of the present invention described above, the non-solubilized product that is difficult to gasify is separated by the filter 7, and only the liquid solubilized product that is easily gasified is gasified in the gasification unit 2, while the Since the lysate is used as an external heat source of the gasification unit 2, carbon in the organic waste as a raw material can be effectively taken out as a fuel gas.

  FIG. 2 is a diagram showing the carbon balance in the present invention, where the raw material is dehydrated sludge and the carbon content is 100%. The solubilization part 1 has a temperature of 200 to 300 ° C. and a pressure of 10 MPa, and the gasification part 2 has a temperature of 500 to 600 ° C. and a pressure of 9 MPa. The gas passing through the filter 7 contains 20% carbon, and the liquid solubilized product contains 35% carbon. The remaining 45% is burned in the hot air generator 12 and released as carbon dioxide.

  Further, 30% of the 55% carbon transferred to the gasification section 2 is recovered as fuel gas, 20% becomes carbon dioxide gas, and 5% moves to the residual liquid. Thus, according to the present invention, a high-calorie fuel gas having a low carbon dioxide content can be obtained.

  On the other hand, when all of the effluent from the solubilization unit 1 is put into the gasification unit 2 without being separated by the filter 7, it is necessary to increase the oxygen ratio of the gasification unit 2, so as shown in FIG. 60% of the carbon in the organic waste as a raw material is carbon dioxide, and the rate of transfer into the fuel gas is 20%. For this reason, the carbon dioxide content in the extracted fuel gas becomes very high, and only low-calorie fuel gas can be obtained. 15% of carbon is discharged as a residue.

  Thus, according to the present invention, the non-solubilized product that is difficult to gasify is separated by the filter 7, so that the oxygen ratio of the gasification unit 2 can be reduced, and the combustion of organic matter is suppressed to obtain a high calorie fuel gas. The carbon gasification rate can be increased. Further, in the present invention, there is an advantage that only one press-fitting pump is required and energy loss is small.

It is a conceptual sectional view showing an embodiment of the present invention. It is explanatory drawing of the carbon balance in this invention. It is explanatory drawing of the carbon balance at the time of putting all the discharge | emission from a solubilization part into a gasification part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solubilization part 2 Gasification part 3 Jacket 4 Press injection pump 5 Feeding blade 6 Feeding blade 7 Filter 8 Scraping mechanism 9 Double valve 10 Cooler 11 Dehydrator 12 Hot-air generator 13 Gas-solid-liquid separator 14 Pressure reducing valve

Claims (6)

  A fuel gas production system that uses hydrous organic waste as a raw material, and converts the solubilized water-soluble organic matter into fuel gas, and a high-temperature and high-pressure solubilization section that solubilizes the organic waste into water-soluble organic matter. A fuel gas production system comprising a high-temperature and high-pressure gasification unit, wherein the solubilization unit and the gasification unit are integrally connected via a filter that allows only gas and liquid to pass through.   The temperature of the solubilizing part is 80 to 400 ° C., preferably 200 to 350 ° C., the pressure is equal to or higher than the saturated vapor pressure of water at the temperature, and the temperature of the gasifying part is 200 to 650 ° C., preferably 450 to 650. 2. The fuel gas production system according to claim 1, wherein the fuel gas production system is at 1 ° C. and the pressure is equal to or lower than the critical pressure of water, preferably 4 to 15 MPa.   The fuel gas production system according to claim 1 or 2, further comprising a separation mechanism for taking out the non-solubilized product produced in the solubilized part in a form mixed with a part of the solubilized product, and dehydrating and separating it.   The fuel gas production system according to any one of claims 1 to 3, further comprising a scraping mechanism for non-solubilized material adhering to the filter.   4. The fuel gas production system according to claim 3, wherein the non-solubilized product separated by the separation mechanism is used as a heat source for the solubilization unit or the gasification unit.   The fuel gas production system according to any one of claims 1 to 5, wherein a catalyst for gasification promotion is supported on the filter.

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