JPH10290912A - Coal gasification combined power generator and its operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent sulfuric acid dew point corrosion at low temperature and sulfurization corrosion at high temperature caused by corrosive gas in raw product gas generated in a coal gas furnace by fitting a metal filter element to a dust collector. SOLUTION: Raw product gas from a coal gas furnace 1 generates steam by a steam generator 2 to lower its temperature and is led to a dust a dust collector 3, and it gets rid of dust to a concentration of scores of mg/Nm<3> there. After the raw product gas from which dust has been removed exchanges heat with outlet gas from a desulfurizer 5 by a gas-gas heat exchanger 4 and gets rid of H2 S+COS by the desulfurizer 5, the outlet gas from the heat exchanger 4 is burned by a combustor 6 to form high temperature combustion gas to drive a gas turbine 7 by which a generator is driven. Waste gas from the gas turbine 7 is led to a waste heat recovery boiler 8, where waste heat is recovered to obtain steam. The steam from the steam generator 2 and steam from the waste heat recovery boiler 8 are led to a steam turbine. Since the dust collector 3 is fitted with a filter element of metallic fiber, it can be operated within the temperature range of 100-500 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated coal gasification combined cycle power generation system in which the reliability and economy of a filter element of a dust removal system are improved and a method of operating the same.

[0002]

2. Description of the Related Art As one of new technologies for high-efficiency power generation using coal, there is integrated coal gasification combined cycle. In the integrated coal gasification combined cycle, coal is gasified, a gas turbine is driven by the gasified fuel, steam is recovered from waste heat of the gas turbine, and a steam turbine is driven to generate power. The crude product gas from the coal gasifier contains dust such as char and ash and H ₂ S generated from sulfur in the coal, and a dust removal device is provided upstream of the gas turbine to prevent wear and corrosion of the gas turbine. And a desulfurization device. If the char collected by the dust removal device is returned to the coal gasifier and gasified again, the gasification efficiency is improved.

[0003]

A typical dust remover includes an electric dust collector, a bag filter, a ceramic filter, and a granular bed. Among them, the electric precipitator is not applicable because there is a problem of leakage due to the small particle size of the char which is the unburned portion contained in the crude product gas and the main component is carbon which is an electric conductor. If the filter cloth is organic, the bag filter cannot be used because the heat resistance temperature is 100 ° C or less. If the filter cloth is glassy, the heat resistance temperature is 300 ° C, but it becomes brittle due to H ₂ S contained in the crude gas. Loses rigidity and cannot withstand long-term use. Ceramic filters can withstand high temperatures, but are cracked by thermal shock or damaged by a difference in the coefficient of thermal expansion between the ceramic and the metal of the support material at the element support, resulting in poor reliability and high cost. The granular bed collects the char as the particles descend inside the filter panel, separates the char by a vibrating sieve outside the filter panel and circulates the particles, and the collected char re-scatters inside the filter panel. However, it is complicated and causes abrasion and loss of particles, which is not suitable for practical use. An object of the present invention is to improve the reliability and economy of a dust removing device that removes crude product gas generated in a coal gasifier.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a coal gasifier for gasifying coal to obtain a crude product gas, a dust removing device for removing dust from the crude product gas, and a generator using the produced gas as fuel. In the combined gasification combined cycle power plant having a gas turbine that drives a gas turbine, the dust removal device is provided with a metallic filter element. The above object is to provide a coal gasifier having a coal gasifier for gasifying coal to obtain a crude product gas, a dust removing device for removing dust from the crude product gas, and a gas turbine driving a generator using the removed dust gas as fuel. In the combined gasification power generation apparatus, the present invention is achieved by providing the dust removal apparatus with a filter element that is a fiber of a Cr-based alloy steel containing at least 10 Wt% of Cr. The above object is a coal gasifier for gasifying coal to obtain a crude product gas,
In a coal gasification combined cycle power plant having a dust removing device for removing a crude product gas and a gas turbine driving a generator using the removed product gas as a fuel, the dust removing device is a Cr-based gas containing at least 10 Wt% of Cr. Cr, N on alloy steel fiber
This is achieved by mounting a filter element plated with i, Ti. Set the dedusting device at a temperature of 100 to 50.
It is desirable to operate at 0 ° C. According to the above configuration, H
_A sulfide film is formed on the metal surface in a crude gas containing 500 ppm of ₂ S and HCl at 500 ° C., and the corrosion does not proceed. Crude gas contains several% of water and dew point is about 100 ℃
Therefore, if the dust remover is operated at 100 ° C. or higher, dew point corrosion does not proceed. Since alloy steel is used for the filter element, it resists thermal shock and does not break due to a difference in thermal expansion coefficient with the supporting metal material.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an integrated coal gasification combined cycle power generation device according to an embodiment of the present invention. As shown in this figure, a steam generator 2 is installed downstream of a coal gasifier 1 for supplying pulverized coal and oxygen to gasify. Further, a dust removing device 3 having a metallic filter element mounted downstream of the steam generator 2 and a gas / gas heat exchanger 4, a desulfurizing device 5, a combustor 6 and a gas turbine 7 are installed downstream of the dust removing device 3. I have. An exhaust heat recovery boiler 8 is provided downstream of the gas turbine 7. In the coal gasifier 1, pulverized coal and oxygen are H
A crude product gas containing ₂ and CO as main components and containing trace amounts of CO ₂ and H ₂ O. Due to gasification, the sulfur content in pulverized coal becomes H
₂ S and COS. In addition, the crude product gas includes char, which is an unburned portion of the pulverized coal, and dust composed of ash from the pulverized coal. The crude product gas from the coal gasifier 1 generates steam in the steam generator 2, and the temperature of the gas itself decreases to be guided to the dust removal device 3. When dust flows into the gas turbine 7, the turbine blades are worn.
Dedust to a concentration of Nm ³ or less. The degassed crude product gas is heat-exchanged with the outlet gas of the desulfurization unit 5 by the gas-gas heat exchanger 4, H ₂ S and COS are removed by the desulfurization unit 5, and then burned by air in the combustor 6 to obtain a high temperature. And a gas turbine 7 drives a generator (not shown). Gas turbine 7
The exhaust gas from the furnace is guided to an exhaust heat recovery boiler 8 to recover the exhaust heat to obtain steam. The steam from the steam generator 2 and the steam from the exhaust heat recovery boiler 8 are guided to a steam turbine (not shown). The dust removing device 3 can be operated in a temperature range of 100 to 500 ° C. since the filter element is provided with a metallic fiber filter element. The smaller the diameter of the fiber constituting the metallic filter element is, the larger the surface area becomes, and the dust collecting performance is improved. However, if the diameter is too small, the fiber is corroded by corrosive H ₂ S and HCl contained in the crude gas. Disappear. Therefore, excellent corrosion resistance is required as a material of the metallic filter element, and the corrosion resistance increases in proportion to the Cr content in the alloy steel of the metallic filter element material. On the other hand, since the corrosion rate depends on the concentration of H ₂ S and HCl in the crude product gas, it is necessary to change the Cr content in the alloy steel depending on the properties of the coal supplied to the coal gasifier 1, and at least 1
0 Wt% or more is necessary.

FIG. 2 is a table showing the relationship between the temperature of the simulation product gas and the amount of corrosion of the Cr-based alloy steel. This figure shows the results of a corrosion test performed on an alloy steel having a Cr content of 2.25 to 18 Wt% in a simulated product gas containing 1,000 ppm of H ₂ S as a corrosive component. Each test piece was 2.25Cr1Mo steel, 9Cr1Mo steel, 12C
r1Mo steel and 18Cr10Ni steel. Although the amount of corrosion of all test pieces increased rapidly at a temperature of 500 ° C. or more, 9Cr1M
Corrosion progresses remarkably in o steel and 2.25Cr1Mo steel. Even at 150 ° C. or lower, corrosion of 9Cr1Mo steel and 2.25Cr1Mo steel remarkably progresses. This is due to the acid dew point corrosion when the simulated product gas becomes lower than the dew point. Even if the Cr content is 10 Wt% or more, if the simulated product gas is below the dew point, acid dew point corrosion is slow but progresses. Therefore, the dust removal device 3 is set to a temperature range of not less than the dew point of the crude gas and not more than the sulfidation corrosion occurrence temperature, namely
Operating at 00 ° C, preferably 150-400 ° C, can slow the progress of corrosion. Since the dust removing device 3 is provided with the metallic fiber filter element, the dust removing device 3 withstands thermal shock and does not break due to a difference in thermal expansion coefficient with the supporting metal material. The diameter of the metallic fiber needs to be determined in relation to the particle diameter of dust and the collecting performance, but is preferably in the range of several μm to several tens μm. The backwashing of the dust removing device 3 is performed by flowing a generated gas and a nitrogen gas which are recycled in a direction opposite to the direction of the crudely generated gas, thereby peeling off the dust collected by the metal fiber filter element. SUS410 (13Cr) and SUS430 (1) are used as the alloy steel having a Cr content of 10 Wt% or more used for the filter element of the metallic fiber of the dust removing device 3.
8Cr), SUS304 (18Cr8Ni), SUS3
10 (25Cr20Ni) can be used. When corrosion at low temperatures is a concern, it is effective to include Mo, and SUS316 (18Cr8NiMo) may be used. When the sulfur in the coal supplied to the coal gasifier 1 is extremely high, Cr, Ni, Ti
May be plated to improve corrosion resistance. Furthermore, if a cyclone is installed upstream of the dust removal device 3 of the present embodiment to perform coarse dust removal, precise dust removal becomes possible with the dust removal device 3, which brings about a favorable state for long-term continuous operation of the gas turbine 7. The burden of backwashing the filter element of the upper metallic fiber is also reduced.

[0007]

According to the present invention, acid dew point corrosion at low temperature and sulfurization corrosion at high temperature, which are generated by corrosive gas in the crude product gas led to the dust removal device, are prevented, and the reliability of the dust removal device is improved. The effect of improving economic efficiency can be obtained. Also,
Since alloy steel is used for the filter element, it can withstand thermal shock and prevent damage due to a difference in thermal expansion coefficient with the supporting metal material.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an integrated coal gasification combined cycle device according to an embodiment of the present invention.

FIG. 2 is a table showing the relationship between the temperature of a simulation product gas and the amount of corrosion of a Cr-based alloy steel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coal gasifier 2 Steam generator 3 Dust removal device 4 Gas / gas heat exchanger 5 Desulfurization device 6 Combustor 7 Gas turbine 8 Exhaust heat recovery boiler

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuji Fukuda 3-36 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Kure Research Institute

Claims (4)

[Claims] 1. A coal gasifier for gasifying coal to obtain a crude product gas, a dust removing device for removing the crude product gas, and a gas turbine for driving a generator using the removed dust gas as a fuel. An integrated coal gasification combined cycle device, wherein the dust removal device is provided with a metallic filter element. 2. A coal gasifier for gasifying coal to obtain a crude product gas, a dust removing device for removing dust from the crude product gas, and a gas turbine for driving a generator using the removed dust gas as fuel. An integrated coal gasification combined cycle power plant, wherein the dust removal device is provided with a filter element that is a fiber of a Cr-based alloy steel containing at least 10 Wt% of Cr. 3. A coal gasifier for gasifying coal to obtain a crude product gas, a dedusting device for removing dust from the crude product gas, and a gas turbine for driving a generator using the removed dust gas as fuel. Coal gasification combined cycle power plant, wherein the dust removal device is equipped with a filter element in which Cr, Ni, and Ti are plated on fibers of a Cr-based alloy steel containing at least 10 Wt% of Cr. Combined power generator. 4. A method for operating a coal gasification combined cycle power plant, comprising operating the dust removing device according to any one of claims 1 to 3 at a temperature of 100 to 500 ° C. .