JP2009292905A - Tar reforming method and equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently recover heat from gasified gases that have undergone tar reforming treatment without increasing the amount of the gases to effectively utilize the exhaust heat. <P>SOLUTION: A two-tower gasification facility is equipped with: a gasification furnace 1 that forms the fluidized bed of a fluid medium 4 by introduction of a gasifying agent 3 to gasify a raw material 5; and a combustion furnace 2 that introduces the fluid medium 4 in the gasification furnace 1 along with unreacted chars and burns the unreacted chars while blowing them up by air 8 to heat the fluid medium 4, and is devised so that the fluid medium 4 heated in the combustion furnace 2 is separated from a combustion exhaust gas 9 and returned to the gasification furnace 1. Regarding a tar reforming method applied to the two-tower gasification facility, the gasified gases 6 produced in the gasification furnace 1 are rose in temperature by promoting the combustion by adding an oxidant 12, and the tar component is oxidized and subjected to steam reforming, and the gasified gases 6 imparted with the tar reforming treatment are subjected to heat exchange with the fluid medium 4 on the way of returning to the gasification furnace 1 from the combustion furnace 2 and cooled. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tar reforming method and apparatus.

  Conventionally, development of gasification equipment that generates gasification gas from raw materials such as coal, biomass, waste plastics, various water-containing wastes, etc. has been promoted, but gasification was performed at a low temperature of 600 ° C to 900 ° C. In this case, the generated gasification gas contains tar, and when this kind of gasification gas is used as a raw material for chemical synthesis, the gasification gas is used in a downstream purification process or chemical synthesis process. As the temperature decreases, tar condenses into mist, and the condensate of the tar may cause problems such as blockage of pipes, troubles in equipment, poisoning of the synthetic catalyst, and the like.

  The technology for removing this kind of tar is to introduce gasified gas to the reforming furnace, add oxidant such as oxygen and air, and burn a part of the gasified gas in this reforming furnace. Conventionally, a tar reforming technique in which the tar content is oxidized and steam reformed while raising the temperature is known. In this case, of course, the amount of the oxidant introduced is controlled so that the inside of the gasifier is maintained at an appropriate temperature.

  FIG. 4 shows an example in which a reforming furnace is applied to a two-column gasification facility as a conventional tar reforming technology. This type of two-column gasification facility includes a gasification furnace 1 and a combustion furnace 2. A fluidized bed of a fluidized medium 4 (eg, sand, limestone, etc.) by supplying a gasifying agent 3 (water vapor, air, oxygen, etc.) to the lower part of the gasification furnace 1 by a diffuser (not shown). The raw material 5 (coal, biomass, waste plastic, etc.) introduced from above the fluidized bed is gasified, and the gasified gas 6 generated here is supplied to the reforming furnace 7. ing.

  On the other hand, the fluidized medium 4 in the gasification furnace 1 is introduced into the combustion furnace 2 together with the unreacted char generated in the gasification furnace 1 due to overflow, and a diffusion device (not shown) is provided below the combustion furnace 2. The air 8 is blown up by the introduced air 8, and the unreacted char is combusted and the fluidized medium 4 is heated at this time.

  Further, in the combustion furnace 2, the combustion exhaust gas 9 blown up together with the fluid medium 4 is introduced into the cyclone 10 from the upper part of the combustion furnace 2, and the fluid medium 4 separated by the cyclone 10 passes the downcomer seal 11. The combustion exhaust gas 9 is returned from the upper part of the cyclone 10 to the exhaust gas treatment facility.

  The gasified gas 6 supplied to the reforming furnace 7 is heated with the addition of an oxidant 12 (oxygen, air, or the like) and burns, thereby oxidizing and reforming the tar content. The reforming reaction to be performed proceeds and tar reforming is performed, but the outlet temperature of the reforming furnace 7 is also 1000 to 1500 ° C., which exceeds the heat resistance temperature (800 to 900 ° C.) of the metal. Therefore, it is cooled to 900 ° C. or less by spraying quenching water with the cooling equipment immediately after that, and then heat is recovered with a boiler heat transfer tube or the like and led to the gas purification equipment.

In addition, as prior art document information regarding tar reforming technology, for example, there is Patent Document 1 below, and as prior art document information regarding a two-column gasification facility, for example, there is Patent Document 2 below.
JP 2005-60533 A JP 2005-41959 A

  However, in the prior art as described above, since the gasified gas 6 exiting from the reforming furnace 7 is cooled by spraying quenching water, the thermal energy of the gasified gas 6 exiting from the reforming furnace 7 is reduced. There is a problem that it is wasted, and cooling by spraying quenching water has a problem that the amount of steam increases and the amount of gas led to the gas purification facility increases remarkably.

  The present invention has been made in view of the above circumstances, and tar reforming has been made so that effective heat recovery can be achieved by efficiently recovering heat without increasing the amount of gas from the gasification gas subjected to tar reforming treatment. It is an object to provide a quality method and apparatus.

  The present invention includes a gasification furnace that gasifies a raw material by forming a fluidized bed of a fluidized medium by introducing a gasifying agent, and the fluidized medium in the gasification furnace is introduced together with unreacted char and blown up by air. A two-column gasification facility comprising a combustion furnace for burning the unreacted char to heat the fluidized medium, wherein the fluidized medium heated in the combustion furnace is separated from the combustion exhaust gas and returned to the gasifier The tar reforming method is applied to the gasification gas by adding an oxidant to the gasification gas generated in the gasification furnace to promote combustion, and the temperature is raised to oxidize and steam reform the tar content. The gasification gas subjected to the tar reforming process is cooled by exchanging heat with a fluid medium in the middle of being returned from the combustion furnace to the gasification furnace.

  The present invention also includes a gasification furnace that gasifies a raw material by forming a fluidized bed of a fluidized medium by introducing a gasifying agent, and the fluidized medium in the gasification furnace is guided together with unreacted char by air. A two-column gas comprising a combustion furnace for heating the fluidized medium by burning the unreacted char while blowing, and separating the fluidized medium heated in the combustion furnace from the combustion exhaust gas and returning it to the gasifier A tar reforming apparatus applied to a gasification facility, wherein an oxidizing agent is added to the gasification gas generated in the gasification furnace to promote combustion, and the tar content is oxidized and steam reformed by raising the temperature. The reforming furnace and the gasification gas that has undergone tar reforming in the reforming furnace are introduced, and the gasification gas is cooled by heat exchange with the fluidized medium that is being returned from the combustion furnace to the gasification furnace. It is also characterized by having a heat exchange part

  Furthermore, in carrying out such a tar reforming apparatus more specifically, a reforming furnace and a heat exchanging unit are configured independently, and the reforming furnace includes gasification gas and oxidant from the gasification furnace. And the tar reforming treatment and heat exchange between the gasified gas and the fluidized medium can be performed in the heat exchange section.

  In addition, the reforming furnace is configured integrally with the heat exchange unit, the gasification gas and the oxidant from the gasification furnace are introduced into a part of the heat exchange unit, tar reforming is performed, and the heat exchange unit You may comprise so that heat exchange with gasification gas and a fluidized medium can be performed in the remaining part.

  Further, the reforming furnace is integrally formed on the upper part of the gasification furnace, the oxidant is introduced into the upper part of the gasification furnace, tar reforming is performed, and the gasification gas is transferred from the upper part of the gasification furnace to the heat exchange unit. It is also possible to configure so that heat exchange with the fluidized medium can be performed.

  According to the tar reforming method and apparatus of the present invention, the following various excellent effects can be obtained.

  (I) According to the first, second, and third aspects of the present invention, the gasification gas heated to a high temperature by the tar reforming treatment is not cooled by spraying quench water, and is converted from a combustion furnace to a gasification furnace. Since heat is exchanged with the fluid medium on the way back to cooling, the heat is efficiently recovered without increasing the amount of gas from the gasification gas subjected to the tar reforming treatment, and effective exhaust heat utilization is achieved. This can reduce the amount of combustion in the combustion furnace, reduce unreacted char leading to the combustion furnace, increase the reaction amount in the gasification furnace, and increase the yield of gasification gas. Can be greatly increased as compared with the prior art.

  (II) According to the invention described in claim 4 of the present invention, since the reforming furnace is integrated with the heat exchanging portion, it is not necessary to provide the reforming furnace independently. Can be realized.

  (III) According to the invention described in claim 5 of the present invention, since the reforming furnace is integrated with the upper part of the gasification furnace, it is not necessary to provide the reforming furnace independently. In addition, since the tar reforming process can be performed in a place where the fluid medium does not exist, heat loss to the fluid medium during the tar reforming process can be eliminated.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is an example of an embodiment for carrying out the present invention, and the parts denoted by the same reference numerals as those in FIG. 4 represent the same items. In the example shown here, the gas of a two-column gasification facility is shown. A vertically long container-shaped heat exchanging portion 13 is provided above the downcomer seal 11 inserted into the upper part of the conversion furnace 1 and reaching the fluidized bed, and the fluidized medium 4 separated by the cyclone 10 is looped. It is introduced into the upper side surface of the heat exchanging part 13 through a seal 14.

  Here, the loop seal 14 has a U-shaped structure in which a pipe line extending downward from the lower part of the cyclone 10 is folded upward, and the pipe is closed by the fluid medium 4 accumulated in the folded part, thereby combusting exhaust gas 9. The fluid medium 4 itself is fluidized by the water vapor 15 introduced from the bottom into the folded portion and pushed up toward the heat exchanging portion 13 to overflow the predetermined height. The heat exchange unit 13 is sequentially introduced to the upper side surface.

  On the other hand, in the vicinity of the heat exchanging section 13, the gasified gas 6 generated in the gasification furnace 1 is introduced, and an oxidant 12 (oxygen or air or the like) is added thereto to promote combustion, thereby increasing the temperature. A reforming furnace 7 for raising and oxidizing and steam reforming the tar content is disposed, and the gasification gas 6 at 1000 to 1500 ° C. discharged after being subjected to tar reforming treatment in the reforming furnace 7 It is introduced into the lower side surface of the heat exchange unit 13.

  That is, in the inside of the heat exchanging section 13, the gasified gas 6 introduced and raised on the lower side surface and the fluidized medium 4 introduced and lowered on the upper side surface are in countercurrent contact. Yes (also possible to be a co-current type), the gasification gas 6 is cooled to 900 ° C. or less by heat exchange with the fluidized medium 4 by this contact, and then further recovered by a heat exchanger tube (not shown) or the like. After that, they are led to gas purification equipment.

  The downcomer seal 11 that guides the fluidized medium 4 from the heat exchanger 13 to the fluidized bed of the gasification furnace 1 is buried in the fluidized bed at the lower end, and the fluidized medium 4 is also fluidized in the fluidized bed. Since the deposit is higher than the above, sealing is performed so that the gasification gas 6 does not return to the gasification furnace 1.

  Thus, the gasification gas 6 generated in the gasification furnace 1 is guided to the reforming furnace 7, where the oxidant 12 is added to promote combustion to raise the temperature and oxidize / steam reform the tar content. Then, when the gasified gas 6 subjected to the tar reforming treatment is introduced into the heat exchange unit 13, heat exchange with the fluidized medium 4 is returned from the combustion furnace 2 to the gasification furnace 1 in the heat exchange unit 13. As a result, the gasification gas 6 is cooled to 900 ° C. or lower, and further heat is recovered by a boiler heat transfer tube (not shown) or the like before being led to the gas purification facility.

  Therefore, according to the above-described embodiment, the gasified gas 6 that has been heated by the tar reforming process is not cooled by spraying quench water, and the fluidized medium 4 that is being returned from the combustion furnace 2 to the gasification furnace 1 Since heat is exchanged and cooled, heat recovery can be efficiently performed without increasing the amount of gas from the gasified gas 6 subjected to the tar reforming treatment, and effective exhaust heat utilization can be achieved. The amount of combustion in the combustion furnace 2 can be reduced, the amount of unreacted char leading to the combustion furnace 2 can be reduced, the amount of reaction in the gasification furnace 1 can be increased, and the yield of the gasification gas 6 can be increased compared to the prior art. Can also be greatly increased.

  That is, in the two-column gasification facility, the unreacted char generated in the gasification furnace 1 is burned in the combustion furnace 2 to heat the fluidized medium 4 to be a heat source for the reaction in the gasification furnace 1. When there is a heat source (heat recovered from the gasification gas 6 in the present embodiment), less unreacted char can be put into the combustion furnace 2 than in the conventional case, and as a result, the amount of reaction in the gasification furnace 1 increases. As a result, the yield of the gasification gas 6 increases.

  FIG. 2 shows another embodiment of the present invention. In the example shown here, the reforming furnace 7 is structured integrally with the heat exchanging section 13, and the lower part of the heat exchanging section 13 is shown. The gasification gas 6 and the oxidant 12 from the gasification furnace 1 are introduced into the gas, the tar reforming process is performed, and the heat exchange between the gasification gas 6 and the fluidized medium 4 is performed in the remaining part of the heat exchange unit 13. It is configured so that it can be performed.

  FIG. 3 shows still another embodiment of the present invention. In the example shown here, the reforming furnace 7 is constructed integrally with the upper part of the gasification furnace 1, and the gas An oxidant 12 is introduced into the upper part of the gasification furnace 1 to perform a tar reforming process, and the gasification gas 6 is guided from the upper part of the gasification furnace 1 to the heat exchanging unit 13 to exchange heat with the fluidized medium 4. It is constituted as follows.

  Thus, in either case of FIG. 2 or FIG. 3, the reforming furnace 7 does not have to be provided independently, so that the entire apparatus can be greatly reduced in size. In the case of the example, the tar reforming process in the place where the fluidized medium 4 exists as shown in FIG. 2 can be avoided, and the tar reforming is performed in the place where the fluidized medium 4 does not exist (upper part of the gasifier 1). Since the quality treatment can be performed, the heat loss to the fluidized medium 4 during the tar reforming treatment can be eliminated.

  It should be noted that the tar reforming method and apparatus of the present invention are not limited to the illustrated examples described above, and it is needless to say that various modifications can be made without departing from the scope of the present invention.

It is the schematic which shows an example of the form which implements this invention. It is the schematic which shows another form example of this invention. It is the schematic which shows another example of a form of this invention. It is the schematic which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gasification furnace 2 Combustion furnace 3 Gasifying agent 4 Fluid medium 5 Raw material 6 Gasification gas 7 Reforming furnace 8 Air 12 Oxidant 13 Heat exchange part

Claims (5)

A gasification furnace that gasifies the raw material by forming a fluidized bed of a fluidized medium by introducing a gasifying agent, and the unreacted char while the fluidized medium in the gasification furnace is guided together with unreacted char and blown up by air. And a combustion furnace that heats the fluidized medium by burning the fluidized medium, and is applied to a two-column gasification facility in which the fluidized medium heated in the combustion furnace is separated from the combustion exhaust gas and returned to the gasification furnace A tar reforming method comprising:
By adding an oxidant to the gasification gas generated in the gasification furnace and promoting combustion, the temperature is raised and the tar content is oxidized and steam reformed,
A tar reforming method comprising cooling the gasified gas subjected to the tar reforming treatment by exchanging heat with a fluid medium in the middle of being returned to the gasifier from the combustion furnace. A gasification furnace that gasifies the raw material by forming a fluidized bed of a fluidized medium by introducing a gasifying agent, and the unreacted char while the fluidized medium in the gasification furnace is guided together with unreacted char and blown up by air. And a combustion furnace that heats the fluidized medium by burning the fluidized medium, and is applied to a two-column gasification facility in which the fluidized medium heated in the combustion furnace is separated from the combustion exhaust gas and returned to the gasification furnace A tar reformer,
A reforming furnace for increasing the temperature by adding an oxidant to the gasification gas generated in the gasification furnace to promote combustion and oxidizing and steam reforming the tar content;
A heat exchange section for introducing gasified gas that has undergone tar reforming in the reforming furnace and cooling the gasified gas with a fluidized medium that is being returned from the combustion furnace to the gasification furnace; A tar reformer characterized by comprising.   A reforming furnace and a heat exchanging unit are configured independently, and a gas reforming process is performed by introducing a gasification gas and an oxidizing agent from a gasification furnace into the reforming furnace, and a gas is formed in the heat exchanging unit. The tar reforming apparatus according to claim 2, wherein the tar reforming apparatus is configured to perform heat exchange between the gasified gas and the fluidized medium.   The reforming furnace is configured integrally with the heat exchanging part, and the tar reforming process is performed by introducing the gasification gas and the oxidant from the gasification furnace into a part of the heat exchanging part and the remaining part of the heat exchanging part The tar reforming apparatus according to claim 2, wherein the tar reforming apparatus is configured such that heat exchange between the gasified gas and the fluidized medium can be performed in a part.   A reforming furnace is integrally formed on the upper part of the gasification furnace, an oxidant is introduced into the upper part of the gasification furnace to perform tar reforming treatment, and the gasification gas is led from the upper part of the gasification furnace to the heat exchange section. The tar reforming apparatus according to claim 2, wherein the tar reforming apparatus is configured to perform heat exchange with a fluid medium.

Images