Patent Application
20150353849
The present disclosure relates to a gasified-gas generation system that gasifies a gasification material to generate a gasified gas.
In recent years, technologies for gasifying a gasification material such as coal, biomass, or tire chips in place of petroleum to generate a gasified gas have been developed. The gasified gas generated in this way is used in power generation systems, production of hydrogen, production of synthetic fuel (synthetic petroleum), or production of chemical products such as chemical fertilizers (urea). Among gasification materials used as feedstock for gasified gases, coal in particular has a reserves-to-production ratio of about 150 years, which is at least three times that of the petroleum, and is also being anticipated as a natural resource that can be stably supplied over a long period of time because its deposits are distributed more evenly than those of petroleum.
As technology for gasifying a gasification material such as coal, technology for gasifying a gasification material in a gasifier in which a fluid medium forms a fluidized bed from steam of about 800° C. has been developed (for instance, Patent Document 1).
In the technology of Patent Document 1, an apparatus equipped with a combustor and a gasifier is used, the fluid medium heated by the combustor is introduced into the gasifier, the gasification material is gasified in the gasifier, and then the fluid medium is introduced from the gasifier into the combustor. In this way, in the technology of Patent Document 1, the fluid medium circulates between the combustor and the gasifier. Also, in the technology of Patent Document 1, the residue (char) of the gasification material after the gasification is introduced into the combustor together with the fluid medium, and the residue is burned in the combustor and heats the fluid medium.
In addition, Patent Documents 2 to 5 also describe gasifiers using fluid media.
[Patent Document 1]
Japanese Patent No. 3933105
[Patent Document 2]
Japanese Unexamined Patent Application, First Publication No. 2005-41959
[Patent Document 3]
Japanese Unexamined Patent Application, First Publication No. H07-35322
[Patent Document 4]
Japanese Unexamined Patent Application, First Publication No. 2003-176486
[Patent Document 5]
Japanese Unexamined Patent Application, First Publication No. 2013-46893
In the gasified-gas generation system through which the fluid medium circulates described in Patent Document 1 described above, a fuel of the combustor is the residue of the gasification material. Accordingly, the amount of heating of the fluid medium in the combustor becomes a difference between the amount of heat generated by burning the residue and the amount of heat radiated from the combustor.
The amount of residue introduced into the combustor depends on the amount of generated gasified gas required for the gasifier, and the amount of heat radiated from the combustor depends on the size (volume) of the combustor. To be specific, the surface area per unit volume (specific surface area) of the combustor is larger when the combustor is smaller, i.e., when the size of the gasified-gas generation system is smaller. Thus, the amount of heat radiated from the combustor increases. Further, the specific surface area is smaller when the combustor is larger. Thus, the amount of heat radiated from the combustor decreases.
Here, if the size of the gasified-gas generation system is enlarged in order to increase the generated amount of the gasified gas, the amount of the residue introduced into the combustor increases, and the amount of heat radiated from the combustor decreases. Thus, the amount of heating of the fluid medium in the combustor increases excessively (the combustor overheats). As a result, the fluid medium may be dissolved and lose its function as a fluid medium. In addition, if the temperature of the fluid medium rises excessively, the combustor or pipes connecting the combustor and the gasifier, for example, needs to have increased strength at high temperatures, which results in an increased cost.
The present disclosure has been made in consideration of this problem, and an object of the present disclosure is to provide a gasified-gas generation system capable of preventing a combustor from overheating without reducing the amount of generated gasified gas.
A gasified-gas generation system according to a first aspect of the present disclosure includes: a combustor configured to heat a fluid medium; a gasifier into which the fluid medium heated by the combustor is introduced and which gasifies a gasification material with heat of the fluid medium so as to generate a gasified gas; and a cooling mechanism configured to cool the fluid medium flowing between the gasifier and the combustor. The fluid medium circulates between the combustor and the gasifier. The fluid medium and a residue of the gasification material are introduced from the gasifier into the combustor, and the combustor burns the residue to heat the fluid medium.
Also, in the gasified-gas generation system according to a second aspect of the present disclosure, the cooling mechanism is provided at a downstream side of the gasifier, and cools the fluid medium which flows an upstream side of the combustor.
Also, the gasified-gas generation system according to a third aspect of the present disclosure includes: a temperature measuring unit configured to measure the temperature of the fluid medium at an inlet of the combustor; and a control unit configured to control the cooling mechanism based on the temperature measured by the temperature measuring unit so as to cool the fluid medium to be within a preset temperature range.
Also, the gasified-gas generation system according to a fourth aspect of the present disclosure includes: a loop seal provided between the gasifier and the combustor and configured to prevent any one or both of an outflow of the gasified gas generated by the gasifier to the combustor and an inflow of a gas from the combustor to the gasifier. The cooling mechanism cools the fluid medium in the loop seal.
In addition, in the gasified-gas generation system according to a fifth aspect of the present disclosure, the cooling mechanism exchanges heat between water and the fluid medium to cool the fluid medium and generate steam. Further, the cooling mechanism includes an introduction unit that introduces the steam generated by the cooling mechanism into the gasifier, and the gasification material in the gasifier is gasified by the steam.
According to the present disclosure, the gasified-gas generation system can prevent the combustor from overheating without reducing the amount of generated gasified gas.
Hereinafter, a preferred embodiment of the present disclosure will be described in detail with reference to the attached drawings. Dimensions, materials, other specific numerical values, and so on indicated in these embodiments are merely examples for facilitating comprehension of the disclosure, and unless indicated otherwise, the present disclosure is not limited thereto. Note that in the specification and drawings, elements having substantially the same functions and constitutions will be given the same reference numerals, and a duplicate description thereof will be omitted. Further, elements not directly related to the present disclosure are not shown in the drawings.
In the present embodiment, the gasified-gas generation system 100 is a circulating fluidized bed type gasification system, and generally circulates a fluid medium composed of sands such as silica sands having a particle diameter of about 300 μm as a heat carrier. To be specific, first, the fluid medium is heated in the combustor 110 at about 900° C. to 1000° C., and is introduced into the medium separator 120 together with the combustion discharge gas. In the medium separator 120, the combustion discharge gas is separated from the high-temperature fluid medium, and heat is recovered from the separated combustion discharge gas by a heat exchanger (e.g., a boiler) that is not shown.
On the other hand, the high-temperature fluid medium separated by the medium separator 120 is introduced into the gasifier 140 via the loop seal 130. Although the details will be described below, the loop seal 130 has a fluidized bed formed therein, and serves to prevent an inflow of the combustion discharge gas from the medium separator 120 to the gasifier 140 and an outflow of the gasified gas from the gasifier 140 to the medium separator 120.
The fluid medium introduced from the medium separator 120 into the gasifier 140 via the loop seal 130 flows with a gasifying agent (here, steam) introduced from a steam distribution unit 142, and returns to the combustor 110 via the loop seal 150.
In this way, in the gasified-gas generation system 100 relating to the present embodiment, the fluid medium moves to the combustor 110, the medium separator 120, the loop seal 130, the gasifier 140, and the loop seal 150 in this order, and is introduced into the combustor 110 again. Thereby, the fluid medium circulates.
In addition, the steam distribution unit 142 is provided at a lower side of the gasifier 140, and steam supplied from a steam supply source (not shown) is introduced from the bottom of the gasifier 140 into the gasifier 140 via the steam distribution unit 142. In this way, the steam is introduced into the high-temperature fluid medium introduced from the medium separator 120, and thereby a fluidized bed (bubble fluidized bed) is formed in the gasifier 140.
A gasification material (solid material) such as coal, biomass, or tire chips is introduced into the gasifier 140. The introduced gasification material is gasified by heat of about 800° C. to 900° C. of the fluid medium. Thereby, a gasified gas (synthetic gas) is generated.
In the gasified-gas generation system 100 in which this fluid medium circulates between the combustor 110 and the gasifier 140, a residue that remains after the gasification material is gasified in the gasifier 140 is introduced into the combustor 110. Accordingly, the residue introduced from the gasifier 140 into the combustor 110 becomes a fuel (heat source) in the combustor 110. The fluid medium is heated in the combustor 110 by heat generated by burning the residue. That is, the amount of heating of the fluid medium in the combustor 110 becomes the difference between the amount of heat generated by burning the residue and the amount of heat radiated from the combustor 110.
Here, the amount of residue introduced into the combustor 110 depends on the amount of generated gasified gas required for the gasifier 140, and the amount of heat radiated from the combustor 110 depends on the size (volume) of the combustor 110. For example, in a relatively small gasified-gas generation system 100 in which the throughput of the gasification material in the gasifier 140 is about 5 tons/day, the combustor 110 has a large specific surface area and radiates a large amount of heat. Thus, it is not always possible to heat the fluid medium to the temperature (800° C. to 900° C.), which is required for the gasifier 140, using only the residue. In that case, an additional fuel (auxiliary fuel) is introduced into the combustor 110 in addition to the residue.
In addition, for example, in a gasified-gas generation system 100 in which the throughput of the gasification material in the gasifier 140 is about 50 tons/day, the fluid medium can be heated to the temperature required for the gasifier 140, using only the residue. Thus, it is not necessary to introduce the auxiliary fuel into the combustor 110.
On the other hand, for example, in a relatively large gasified-gas generation system 100 in which the throughput of the gasification material in the gasifier 140 is about 500 to 2000 tons/day, the combustor 110 has a small specific surface area and radiates a small amount of heat. Thus, even if only the residue is burned, the fluid medium sometimes overheats to a temperature higher than the temperature required for the gasifier 140.
If the fluid medium overheats, the fluid medium may be dissolved. Also, for instance, the combustor 110 or the loop seal 150 or pipes connecting the combustor 110 and the gasifier 140 needs to be strengthened against high temperatures, which increases the cost of the gasified-gas generation system 100. In this case, to inhibit the combustor 110 from overheating, reducing the amount of the residue introduced from the gasifier 140 into the combustor 110, that is, reducing the amount of the gasification material introduced into the gasifier 140, may also be considered, but the required amount of generated gasified gas may not be secured.
Therefore, in the gasified-gas generation system 100 relating to the present embodiment, the overheating of the fluid medium is prevented by the cooling mechanism 160. The cooling mechanism 160 includes a circulation pipe 162 and a pump 164, and cools the fluid medium flowing between the gasifier 140 and the combustor 110. In the present embodiment, the cooling mechanism 160 cools the fluid medium flowing through the loop seal 150.
In this way, the steam is introduced into the fluid medium and the residue introduced from the gasifier 140 via an inlet 150a of the loop seal 150, and thereby a fluidized bed (bubble fluidized bed) is formed in the loop seal 150 (or the main body 154). Thus, when a height of the fluidized bed in a vertical direction increases due to additional introduction of a fluid medium and the residue from the gasifier 140, the fluid medium and the residue overflow from an outlet 150b of the loop seal 150 and are introduced into the combustor 110.
Due to the constitution having the loop seal 150, an outflow of the gasified gas generated by the gasifier 140 to the combustor 110 and an inflow of a gas from the combustor 110 to the gasifier 140 can be prevented. The loop seal 130 has substantially the same constitution as the loop seal 150, and so a duplicate description thereof will be omitted.
The circulation pipe 162 constituting the cooling mechanism 160 has one end connected to the pump (introduction unit) 164 and the other end connected to the steam distribution unit 142 (see
The pump 164 introduces water into the circulation pipe 162 in response to a control command of the control unit 180 to be described below. When the water is introduced into the circulation pipe 162 by the pump 164, the water exchanges heat with the fluid medium and the residue when flowing through the loop seal 150, and the fluid medium and the residue are cooled, whereas the water is heated into steam.
Due to the constitution having the cooling mechanism 160, the fluid medium can be cooled (release heat) without changing the amount of the residue, that is, without reducing the amount of generated gasified gas (introduced amount of the gasification material).
Meanwhile, since a gasification reaction is an endothermic reaction, even if the overheated fluid medium is introduced into the gasifier 140, the fluid medium is cooled in the gasifier 140. Accordingly, it does not particularly matter if the overheated fluid medium is introduced into the gasifier 140. However, since a combustion reaction is an exothermic reaction, if the overheated fluid medium is introduced into the combustor 110, the fluid medium further overheats in the combustor 110. Accordingly, if the overheated fluid medium is introduced into the combustor 110, the fluid medium may be dissolved in the combustor 110.
Therefore, the cooling mechanism 160 in the present embodiment cools the fluid medium flowing between the gasifier 140 and the combustor 110 (a downstream side of the gasifier 140 and an upstream side of the combustor 110). Thereby, the fluid medium introduced into the combustor 110 can be cooled, and a situation in which the combustor 110 overheats and the fluid medium is dissolved can be avoided.
In addition, since a fluidized bed needs to be formed in the loop seal 150, a volume is secured to some extent. As a result, a relatively great volume can be employed for installation of the circulation pipe 162. Accordingly, as the cooling mechanism 160 cools the fluid medium in the loop seal 150, the fluid medium can be efficiently cooled.
Also, in the present embodiment, the steam generated at the part 162a of the circulation pipe 162 disposed in the loop seal 150 is introduced into the gasifier 140 via the steam distribution unit 142. That is, the steam generated at the part 162a of the circulation pipe 162 is introduced into the gasifier 140 by driving the pump 164.
Thereby, energy for generating the steam required to gasify the gasification material can be reduced.
The temperature measuring unit 170 is made up of, for instance, a thermocouple, and measures the temperature of fluid medium at an inlet of the combustor 110.
In one embodiment, the control unit 180 is composed of a semiconductor integrated circuit including a central processing unit (CPU), reads a program or a parameter for operating the CPU out of a read-only memory (ROM), cooperates with a random access memory (RAM) or another electronic circuit as a work area, and manages or controls the entire gasified-gas generation system 100. In the present embodiment, the control unit 180 controls the amount of driving of the pump 164 (cooling mechanism 160) so as to cool the fluid medium to a preset temperature range based on the temperature of the fluid medium in which the temperature measuring unit 170 measures.
Due to the constitution having the temperature measuring unit 170 and the control unit 180, the temperature of the fluid medium introduced into the combustor 110 can be maintained within the preset temperature range. Accordingly, the temperature of the fluid medium after being heated in the combustor 110 is set to a temperature range that is a temperature at which the fluid medium is not dissolved and that becomes a temperature required in the gasifier 140. Thereby, the temperature of the fluid medium in the gasifier 140 can be maintained at a temperature suitable for the gasification while the fluid medium is prevented from overheating. In addition, the amount of the residue introduced into the combustor 110 is derived based on the amount of gasification material introduced (required amount of the gasified gas), and then, the amount of heat generated by burning the introduced residue is derived. As a result, the amount of heating of the fluid medium in the combustor 110 can be derived based on the amount of heat generated and the amount of heat radiated by the combustor 110.
As described above, according to the gasified-gas generation system 100 relating to the present embodiment, the overheating of the combustor 110 can be prevented without reducing the amount of gasified gas generated.
While a preferred embodiment of the present disclosure has been described with reference to the drawings, it goes without saying that the present disclosure is not limited to this embodiment. It will be apparent to those skilled in the art that various modifications or alterations can be contrived and implemented within the scope described in the specification, and it will be understood that these modifications and alterations also fall within the technical scope of the present disclosure.
For example, in the aforementioned embodiment, the cooling mechanism 160 is provided at the downstream side of the gasifier 140 and cools the fluid medium flowing in the loop seal 150 provided at the upstream side of the combustor 110. However, as long as the fluid medium flowing between the gasifier 140 and the combustor 110 is cooled, there is no limitation on the cooling position of the fluid medium. For example, the fluid medium flowing through the pipe connecting the gasifier 140 and the loop seal 150 or the pipe connecting the loop seal 150 and the combustor 110 may be cooled. Also, a heat exchanger may be provided between the gasifier 140 and the combustor 110.
In addition, in the aforementioned embodiment, the constitution in which the cooling mechanism 160 cools the fluid medium flowing between the gasifier 140 and the combustor 110 has been described by way of example. However, in addition to the fluid medium flowing between the gasifier 140 and the combustor 110, the fluid medium flowing between the medium separator 120 and the gasifier 140 (provided at a downstream side of the medium separator 120 and flowing through an upstream side of the gasifier 140, for instance, through the loop seal 130) may be cooled. Thereby, the temperature of the fluid medium in the gasifier 140 can be maintained within a desired temperature range.
Furthermore, in the aforementioned embodiment, the cooling mechanism 160 configured to include the circulation pipe 162 and the pump 164 has been described. However, the cooling mechanism 160 need only be able to cool the fluid medium and generate steam by exchanging heat between the water and the fluid medium. For example, the cooling mechanism 160 may be configured of a natural circulation boiler (drum boiler) for which the pump 164 is not required.
The present disclosure can be used in the gasified-gas generation system that gasifies the gasification material to generate the gasified gas.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-057509 | Mar 2013 | JP | national |
This application is a continuation application based on a PCT Patent Application No. PCT/JP2014/57554, filed on Mar. 19, 2014, whose priority is claimed on Japanese Patent Application No. 2013-57509, filed on Mar. 21, 2013. The contents of both the PCT Application and the Japanese Application are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2014/057554 | Mar 2014 | US |
| Child | 14827801 | US |
