JP2012001686A - Gasified gas manufacturing system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use drainage, generated by the production of a gasified gas, as boiler water.SOLUTION: A gasified gas manufacturing system includes a gasification means for gasifying a combustible raw material using water vapor generated with a boiler 2, and a gas purification means for purifying the gasified gas generated by the gasification means, wherein the gas purification means performs the organic component removing treatment and the nitrogen component removing treatment on the drainage generated from the purification of the gasified gas to generate the boiler water to be supplied to the boiler 2.

Description

  The present invention relates to a gasification gas production system and method.

  In Patent Documents 1 and 2, as a technology for purifying a generated gas (gasification gas) generated in a coal gasification facility, hydrogen chloride, hydrogen cyanide, and ammonia contained in the generated gas are absorbed in the washing water by a washing tower. The washing water is decompressed with a stripper and heated with steam to separate hydrogen cyanide and ammonia as gas, and the separated hydrogen cyanide and ammonia are combusted in a combustion furnace, while a part of the washing water is returned to the washing tower for recycling. It is described to do. Moreover, in the refiner | purifier of the gasification gas described in patent document 1, the activated sludge process is performed to the waste_water | drain which passed through the various refinement | purification processes with a water-resistant activated sludge process equipment. In the gasification facility, gasified gas is generated by adding steam generated by a boiler to combustible waste or coal as a raw material and heating it to about 900 ° C.

JP 2007-045857 A JP 2006-232904 A

  By the way, as mentioned above, the boiler which generates water vapor | steam is indispensable for gasification equipment. On the other hand, for example, it is often difficult to obtain water in an area where low-grade coal as a raw material is mined, and boiler water becomes extremely valuable in a gasification facility constructed in such an area. ing. The above-described prior art does not take such precious boiler water into consideration, and development of a coal gasification system that takes into account the availability of boiler water is eagerly desired.

  In the activated sludge treatment of waste water, organic components cannot be removed sufficiently, especially when some trouble occurs in the gasification gas production process and tar components exceeding the specified value are mixed in the gasification gas. However, there is a problem that the waste water treatment is unstable. Therefore, the activated sludge treatment is not preferable as a treatment of waste water generated in the process of producing gasification gas.

  This invention is made | formed in view of the situation mentioned above, and aims at using effectively the waste_water | drain generated in the manufacture process of gasification gas as boiler water. Another object of the present invention is to stably treat waste water generated in the process of producing gasification gas.

  In order to achieve the above object, in the present invention, as a first solution means for a gasification gas production system, a gasification means for gasifying a combustible raw material using water vapor generated in a boiler, and the gasification means A gas purification means for purifying the gasified gas produced in step (i), wherein the gas purification means performs an organic component removal treatment and a nitrogen component removal treatment on the wastewater generated from the purification of the gasification gas. The means of generating boiler water to be used for

  As the second solving means relating to the gasification gas production system, in the first solving means, the gas purification means further adopts a means in which either or both of an inorganic ion removing process and a distillation process are further performed. .

  As the third solving means relating to the gasification gas production system, in the first or second solving means, the gas purification means includes at least a coagulation sedimentation tank as equipment for performing organic component removal treatment on the waste water. Adopt means.

  As a fourth solving means related to the gasification gas production system, in any one of the first to third solving means, the gas purification means includes an ammonia tripping device as equipment for performing nitrogen component removal treatment on the waste water, Adopt the means.

  As a fifth solving means relating to the gasification gas production system, in any one of the second to fourth solving means, the gas purification means includes an ion exchange membrane as equipment for performing an inorganic ion removing process. Is adopted.

  Further, in the present invention, as a first solving means related to the gasified gas production method, a purification process is performed in which gasified gas is generated from a combustible raw material using water vapor generated in a boiler and impurities are removed from the gasified gas. A method for producing gasified gas, wherein the waste water generated from the purification treatment is subjected to organic component removal treatment and organic component removal treatment to generate boiler water for use in the boiler.

  According to the present invention, since organic components and nitrogen components are removed from wastewater generated by purification of gasification gas, wastewater to the extent required as boiler water can be purified and effectively used as boiler water.

It is a system configuration figure of the gasification gas manufacturing system concerning one embodiment of the present invention. It is a block diagram which shows the function structure of the waste water treatment equipment 8 in the gasification gas manufacturing system which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the gasification gas production system according to this embodiment includes a gasification furnace 1, a boiler 2, an oxidation reforming furnace 3, a direct cooler 4, an indirect cooler 5, a compressor 6, a desulfurization / de-CO. ₂ device 7 and waste water treatment device 8. Among these components, the gasification furnace 1, the boiler 2, and the waste water treatment device 8 constitute gasification means, and the oxidation reforming furnace 3, the direct cooler 4, the indirect cooler 5, the compressor 6, and the desulfurization. and de-CO ₂ device 7 constitute a gas purification unit.

  As will be described in detail below, such a gasification gas production system is a product obtained by gasifying a combustible raw material into a gasification gas using water vapor and subjecting the gasification gas to a purification treatment to remove impurities. This is a facility for producing gas (gasification gas). In addition, the combustible raw material in this embodiment is coal.

  The gasification furnace 1 is a device that gasifies the combustible raw material by mixing the combustible raw material supplied from the inlet with the water vapor supplied from the boiler 2 and heating it to about 900 ° C., for example. That is, the gasification furnace 1 includes a combustion chamber, and gasifies by heating the combustible raw material mixed with water vapor to about 900 ° C. using heat generated by burning fuel in the combustion chamber. Generate gas. The gasification gas generated in such a gasification furnace 1 is discharged from the gasification furnace 1 to the oxidation reforming furnace 3.

  The boiler 2 is a device that generates steam by heating the boiler water supplied from the waste water treatment device 8 using heat generated in the combustion chamber of the gasification furnace 1. That is, the boiler 2 is an exhaust heat recovery boiler that recovers exhaust heat of the gasification furnace 1 and vaporizes boiler water, and supplies the steam generated by itself to the gasification furnace 1. The oxidation reforming furnace 3 is an apparatus that performs oxidation reforming by heating a gasification gas to, for example, 1100 to 1300 ° C. by heat obtained by burning hydrogen as fuel. The oxidation reforming furnace 3 is provided with a cooling water spray device that sprays cooling water in the vicinity of the outlet of the reformed gasification gas, and is cooled to, for example, 1000 to 1200 ° C. by spraying the cooling water. The gasified gas thus discharged is directly discharged to the cooler 4.

  The direct cooler 4 is a device that directly cools the gasified gas supplied from the oxidation reforming furnace 3 by spraying cooling water. The direct cooler 4 discharges the gasified gas after cooling to the indirect cooler 5, and discharges the cooling water supplied to the direct cooling to the waste water treatment device 8 as waste water. The indirect cooler 5 is a heat exchanger that indirectly cools the gasified gas by exchanging heat with the cooling water and discharges it to the compressor 6, and drains the cooling water after being used for the indirect cooling as waste water. It discharges to the device 8.

The compressor 6 is a device that boosts the gasification gas to, for example, 1 to 5 MPa in order to reduce the saturated vapor concentration of the tar component contained in the gasification gas. In the compressor 6, some components such as the tar component are condensed to some extent as condensed water. The compressor 6 discharges such condensed water as waste water to the waste water treatment device 8. The desulfurization / de-CO ₂ device 7 is a device that removes sulfur (S) and carbon dioxide (CO ₂ ) contained in the gasification gas. Although desulfurization and the removal CO ₂ system are known some things may be of any type as the desulfurization and removal CO ₂ device 7.

  The waste water treatment device 8 purifies each waste water supplied from the direct cooler 4, the indirect cooler 5 and the compressor 6 and supplies the waste water as boiler water to the boiler 2. This waste water treatment device 8 is the most characteristic component among the various components constituting the gasification gas production system, and as shown in FIG. 2, a sedimentation tank 8a, a coagulation sedimentation tank 8b, and an ammonia tripping device 8c. The first distillation device 8d, the first ion exchange device 8e, the second distillation device 8f, the second ion exchange device 8g, and the selection device 8h.

  The sedimentation basin 8a precipitates organic components based on the stationary separation method and separates them from the waste water, and drains the supernatant water into the coagulation sedimentation tank 8b as treated water. The coagulation sedimentation tank 8b forcibly removes the organic components remaining in the treated water by adding a coagulant to the treated water, and the treated water from which the organic components are forcibly removed by coagulation is supplied to the ammonia tripping device 8c. Drain. The ammonia tripping device 8c is a device that separates and removes nitrogen components (existing as ammonia) contained in the treated water supplied from the coagulation sedimentation tank 8b as ammonia gas by chemically reacting with water. The ammonia tripping device 8c drains the treated water from which the nitrogen component has been removed to the first distillation device 8d, the second distillation device 8f, and the second ion exchange device 8g.

  The first distillation device 8d is for removing various solids such as tar components remaining in the treated water by subjecting the treated water supplied from the ammonia tripping device 8c to a distillation treatment. The first distillation apparatus 8d drains distilled water from which solids such as tar components have been removed to the first ion exchange apparatus 8e. The first ion exchange device 8e is a device that removes inorganic ions contained in the distilled water with an ion exchange membrane. The first ion exchange device 8e drains the permeated water of the ion exchange membrane from which inorganic ions have been removed to the selection device 8h.

  Similarly to the first distillation apparatus 8d, the second distillation apparatus 8f removes solids such as tar components remaining in the treated water by subjecting the treated water supplied from the ammonia tripping apparatus 8c to a distillation treatment. It is. The second distillation device 8f drains distilled water to the selection device 8h. The second ion exchange device 8g is a device that removes inorganic ions contained in the treated water supplied from the ammonia tripping device 8c with an ion exchange membrane. The second ion exchange device 8g drains the permeated water of the ion exchange membrane to the selection device 8h.

  The selection device 8h is a device that selectively selects any one of the first ion exchange device 8e, the second distillation device 8f, the second ion exchange device 8g, and the ammonia tripping device 8c. The selection device 8h supplies permeated water, distilled water or treated water supplied from the device selected by itself to the boiler 2 as boiler water.

  The first distillation apparatus 8d and the second distillation apparatus 8f perform distillation using the exhaust heat of the gasification furnace 1 in order to improve the overall energy efficiency of the gasification gas production system. preferable.

Next, the operation of the gasified gas production system will be described in detail.
In this gasification gas production system, gasification gas is generated from a combustible raw material using water vapor by the gasification means, and the gasification gas becomes product gas by being generated by the gas purification means. Various types of wastewater are generated during the purification process of the gasification gas by the gas purification means. These wastewaters are purified by the wastewater treatment device 8 that is a component of the gas purification means until they can be reused as boiler water. It is supplied to the boiler 2 constituting the gasification means.

  That is, each waste water generated by the direct cooler 4, the indirect cooler 5, and the compressor 6 is sequentially supplied to the settling basin 8 positioned in the uppermost stream in the waste water treatment device 8. Such wastewater is mainly composed of water, but is directly in gas-liquid contact with the gasification gas in the cooler 4 or condensed in the compressor 6, and the generation process or oxidation reforming in the gasification furnace 1. In the oxidation reforming process in the furnace 3, a tar component, an organic component, and an inorganic component are included as impurities. Such drainage is less than the purity required by the boiler 2 as boiler water due to the impurities.

  Generally, boilers are classified into low-pressure boilers and high-pressure boilers, but high-pressure boilers are designed to require boiler water having a higher purity than low-pressure boilers. In addition, the purity (water quality) required for boiler water varies depending on the design specifications in the boilers belonging to each of these categories. Therefore, in order to use the waste water for boiler water, it is necessary to purify the waste water to a purity required according to the boiler type and design specifications by removing impurities.

  The sedimentation basin 8a located at the uppermost stream in the wastewater treatment device 8 of the gasification gas production system is configured to allow the wastewater sequentially supplied from the direct cooler 4, the indirect cooler 5 and the compressor 6 to stand for a certain period. Organic components contained in the waste water that are relatively easily precipitated are precipitated and separated and removed. However, since removal of organic components in the sedimentation basin 8a is not always sufficient, the treated water (supernatant water) of the sedimentation basin 8a is introduced into the subsequent agglomeration sedimentation tank 8b, added with a flocculant, and the remaining organic The components are forcibly coagulated and precipitated. The organic components in the wastewater satisfy the allowable value of the remaining organic components in the boiler water required by the boiler 2 by the sedimentation basin 8a and the coagulation sedimentation tank 8b.

  The treated water from which the organic components have been removed in the settling basin 8a and the coagulation settling tank 8b is converted into ammonia so that the nitrogen content of the treated water in the ammonia tripping device 8c satisfies the allowable value of the residual nitrogen component required by the boiler 2. Separated and removed. Then, the treated water from which the nitrogen component has been removed in the ammonia tripping device 8c is selectively treated by the first distillation device 8d, the second distillation device 8f, or the second ion exchange device 8g, whereby solids such as tar components are obtained. After object removal or inorganic ion removal is performed, boiler water is supplied to the boiler 2 from the selection device 8h.

  That is, in the treated water supplied from the ammonia tripping device 8c to the first distillation device 8d, solids such as tar components are removed by the first distillation device 8d, and inorganic ions are removed by the first ion exchange device 8e. After that, it is supplied as boiler water to the boiler 2 via the selection device 8h. On the other hand, the treated water supplied from the astripping device 8c to the second distillation device 8f is supplied to the boiler 2 via the selection device 8h after the solid matter such as the tar component is removed by the second distillation device 8f. Supplied as On the other hand, the treated water supplied from the ammonia tripping device 8c to the second ion exchange device 8g is supplied as boiler water to the boiler 2 via the selection device 8h after the inorganic ions are removed in the second ion exchange device 8g. Is done.

  The selection device 8h has the purity (water quality) required by the boiler 2 as boiler water out of the treatment routes in which the boiler water that is the three treatment routes and the treatment water discharged from the ammonia tripping device 8c are used as boiler water as they are. ) Is selected and supplied to the boiler 2. That is, since the processing path (first processing path) composed of the first distillation apparatus 8d and the first ion exchange apparatus 8e removes both solid substances such as tar components and inorganic ions, the three processing paths The boiler water with the highest purity (the best water quality) can be provided to the boiler 2.

  On the other hand, the treatment path (second treatment path) composed of the second distillation apparatus 8f removes only solids such as tar components, and thus more inorganic ions than boiler water generated through the first treatment path. The boiler water with a large remaining amount is provided to the boiler 2. On the other hand, the processing path (third processing path) composed of the second ion exchange device 8g removes only inorganic ions, and therefore solids such as tar components rather than boiler water generated through the first processing path. The boiler water with a large amount of remaining is provided to the boiler 2. On the other hand, in the treatment path (fourth treatment path) in which the treated water discharged from the ammonia tripping device 8c is used as boiler water as it is, solid substances such as tar components and inorganic ions are generated more than the boiler water generated through the first treatment path. The boiler water with a large amount of remaining is provided to the boiler 2.

According to the present embodiment as described above, since at least organic components are removed from the wastewater generated by purification of the gasification gas, the wastewater can be effectively used as boiler water. Further, since the selection device 8h can selectively select a solid component such as a tar component and inorganic ions, the solid component such as the tar component and / or inorganic ions can be selected as necessary in addition to the removal of the organic component. The boiler water from which the water is removed can be supplied to the boiler 2.
Moreover, according to this embodiment, since waste water is processed without using activated sludge processing, it aims also to process stably the waste water generated in the production process of gasification gas.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, coal is used as a combustible raw material, and in this connection, tar components, organic components, and inorganic components are contained as impurities in the wastewater. However, the combustible raw material is not limited to coal. As the combustible raw material to be supplied to the gasification furnace 1, in addition to coal, solid fuel such as various types of waste such as municipal waste, industrial waste, sludge, and agricultural waste, biomass, and the like can be considered. Impurities contained in the wastewater differ depending on the properties of the raw materials, so even if a device that removes tar components, organic components, and inorganic components that are inconvenient as boiler water (such as chlorine components and cyan components) is added. good.

(2) In the above embodiment, the first to fourth processing paths are alternatively selected by the selection device 8h, but the present invention is not limited to this. For example, the waste water treatment device 8 may be composed of only the sedimentation basin 8a, the coagulation sedimentation tank 8b, and the ammonia tripping device 8c, and the first distillation apparatus 8d and the sedimentation basin 8a, the coagulation sedimentation tank 8b, and the ammonia tripping device 8c A configuration in which only the first ion exchange device 8e is added, or a configuration in which only the second distillation device 8f is added to the sedimentation tank 8a, the coagulation sedimentation tank 8b, and the ammonia tripping device 8c, or a sedimentation tank 8a, the coagulation sedimentation tank 8b, and the ammonia tripping. It is good also as a structure which added only the 2nd ion exchange apparatus 8g to the apparatus 8c.

(3) In the above embodiment, the gas purification means is constituted by the oxidation reforming furnace 3, the direct cooler 4, the indirect cooler 5, the compressor 6, the desulfurization / deoxygenation CO ₂ device 7 and the waste water treatment device 8. However, the present invention is not limited to this. Since the gist of the present invention is to use boiler water as wastewater generated in the process of producing gasified gas, various device configurations other than those necessary for using wastewater as boiler water can take various configurations.

(4) In the said embodiment, although the treated water obtained with the waste water treatment apparatus 8 was supplied to the boiler 2 as boiler water, the amount of the treated water which the waste water treatment apparatus 8 outputs requires the boiler 2. When the amount of water is exceeded, a part of the treated water output from the waste water treatment device 8 may be supplied to the oxidation reforming furnace 3, the direct cooler 4, and the indirect cooler 5 as cooling water.

1 ... gasification furnace, 2 ... boiler, 3 ... oxidation reformer, 4 ... direct cooler, 5 ... indirect cooler, 6 ... compressor, 7 ... desulfurization and removal CO ₂ device, 8 ... waste water treatment apparatus, 8a ... Precipitation basin, 8b ... Coagulation sedimentation tank, 8c ... Ammonia tripping device, 8d ... First distillation device, 8e ... First ion exchange device, 8f ... Second distillation device, 8g ... Second ion exchange device, 8h ... Selection device

Claims (6)

Gasification means for gasifying a combustible raw material using water vapor generated in a boiler;
Gas purification means for purifying the gasification gas produced by the gasification means,
The gas purification means generates boiler water for use in the boiler by performing an organic component removal process and a nitrogen component removal process on the wastewater generated from the purification of the gasification gas. .   2. The gasification gas production system according to claim 1, wherein the gas purification means further performs one or both of an inorganic ion removal process and a distillation process.   The gasification gas production system according to claim 1 or 2, wherein the gas purification means includes at least a coagulation sedimentation tank as equipment for performing an organic component removal treatment on the waste water.   The gasification gas production system according to any one of claims 1 to 3, wherein the gas purification means includes an ammonia tripping device as equipment for performing a nitrogen component removal process on the waste water.   The gasification gas production system according to any one of claims 2 to 4, wherein the gas purification means includes an ion exchange membrane as equipment for performing an inorganic ion removal treatment. A gasified gas production method for producing a gasification gas from a combustible raw material using water vapor generated in a boiler and subjecting the gasification gas to a purification treatment to remove impurities,
The gasification gas manufacturing method characterized by producing | generating boiler water for supplying to the said boiler by performing the organic component removal process and the organic component removal process to the waste_water | drain produced | generated from the said refinement | purification process.

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