JPH0781152B2 - Operation method of coal gasification combined plant - Google Patents

Description

TECHNICAL FIELD The present invention relates to an operating method for reducing NO _X and SO _X in exhaust gas in a coal gasification combined plant.

[Conventional technology]

FIG. 2 is a system diagram of a conventional coal gasification combined plant, in which a coal 1 stored in a bunker is supplied to a mill 2 and pulverized into fine powder. The pulverized coal is supplied into the gasification furnace 3 together with a gasifying agent such as air to carry out a gasification reaction. The gas produced by the gasification reaction contains a small amount of S content (H ₂ S, COS) and N content (NH ₃ , HCN) in addition to the main components CO and H ₂ . The unreacted char and the produced gas are introduced into the sensible heat recovery heat exchanger 4, where the temperature is cooled from 1000 ° C to 400 ° C and heat is recovered. Next, the unreacted char in the produced gas is removed by the coarse dedusting device 5. The removed unreacted char passes through the char recovery line 6 and is supplied to the gasification furnace 3 as auxiliary fuel. On the other hand, the degassed product gas enters the dry desulfurization unit 7, and the S content is burned to SO _X , about 90% of which
After being desulfurized, the dust is completely removed by the precision dust removing device 8 and supplied to the gas turbine 9. Exhaust gas burned in the gas turbine 9 together with NH ₃ supplied from the outside denitration device 1
At 0, NO _x in the combustion exhaust gas is denitrated and then discharged to the atmosphere through the exhaust gas boiler 11 and the chimney 12.

[Problems to be solved by the invention]

In the above conventional coal gasification combined plant, the effect of reducing SO _X and NO _X which are air pollutants in combustion exhaust gas is 90% for S content and 80% for N content by using a dry desulfurization device as a denitration device. % Efficiency, not perfect. When a wet desulfurization device is used instead of the dry desulfurization device 7 in the above plant, the desulfurization effect can be improved up to about 98%, but there are problems such as reduction in thermal efficiency and rapid deterioration of absorption liquid. Many.

Therefore, in the conventional coal gasification combined plan, when coal containing a large amount of sulfur content and nitrogen content is gasified, a large amount of SO _X , NO _X in the exhaust gas may be emitted into the atmosphere, and When a wet desulfurization device is used to improve the desulfurization effect, there are problems such as a decrease in thermal efficiency.

The present invention seeks to solve these problems.

[Means for solving problems]

The present invention is a coal gasification combined plant equipped with a coal gasification furnace, a dry desulfurization apparatus and a gas turbine, in which a part of the gas generated in the coal gasification furnace is extracted from between the coal gasification furnace and the gas turbine. After being introduced into the wet absorption device to remove the sulfur and nitrogen components in the gas such as H ₂ S and NH ₃ , it is supplied to the above gas turbine, and the above wet absorption device collects NH ₃ in the absorption liquid. The SO _x and NO _x in the exhaust gas were reduced by introducing them into the denitration device together with the combustion exhaust gas from the gas turbine and treating them.

[Action]

In the present invention, a part of the gas supplied to the gas turbine produced in the coal gasification furnace is extracted, processed by a wet absorption device, and H ₂ S, NH _{3 and the} like that become air pollutants are removed and then the gas turbine Supply to. Therefore, SO _X and NO _{X in} the combustion exhaust gas of the gas turbine are reduced. In addition, NH ₃ in the absorption liquid is stripped in the wet absorption device to separate it from the absorption liquid, and this is treated together with the combustion exhaust gas from the gas turbine in the denitrification device to make the NH ₃ absorbed in the absorption liquid effective. To reduce SO _X and NO _{X in} exhaust gas.

Further, in the present invention, since the dry desulfurization device is used, problems such as reduction in thermal efficiency of the plant do not occur.

〔Example〕

An embodiment of the present invention will be described with reference to FIG. In FIG. 1, coal 1 stored in a bunker, a mill 2, a gasification furnace 3, a sensible heat recovery heat exchanger 4, a rough dedusting device 5, a chair recovery line 6, a dry desulfurization device 7, a precision dedusting device 8 The gas turbine 9, the denitration device 10, the exhaust gas boiler 11, and the chimney 12 are second
Since it is similar to the conventional one shown in the figure, its explanation is omitted.

In the present embodiment, a part of the product gas that has undergone rough dedusting is introduced into the wet absorption device 14 using the bypass line 13, and in the wet absorption device 14, H ₂ S and NH ₃ etc. in the product gas are introduced. Absorbs sulfur and nitrogen in the absorbent. The generated gas after absorption is supplied to the gas turbine 9 from the wet absorption device 14 through the bypass line 15 and burned in the gas turbine 9. On the other hand, in the wet absorber 14 performs stripping of the NH ₃ from the absorption liquid, NH ₃ supply line 16 NH _{3 is} discharged
Through the exhaust gas of the gas turbine 9 and the denitration device 10
Supply to. At this time, when the amount of NH ₃ supplied from the supply line 16 is insufficient, NH ₃ is separately supplied as shown in the figure to replenish it. Exhaust gas boiler 11 and chimney 12
A SO _X meter 17a and a NO _X meter 17b are arranged in the pipe between them, and the SO _X and NO _X concentrations in the exhaust gas are detected by using these, and based on this, the valve 15a installed in the bypass line 15a. By controlling the bypass flow rate of the gas supplied from the wet absorption device 14 to the gas turbine 9 by controlling the
Measure effective reduction of SO _X and NO _X. H ₂ S, NH ₃ from generated gas
As a method for removing the above, a rectizole method using methanol as an absorbing solution, a selexol method using glycol ether, or the like can be used.

In this embodiment, as described above, a part of the gas generated in the coal gasification furnace is extracted and guided to the wet absorption device 14, where the H ₂
After removing S and N components such as S and NH ₃ , the gas turbine 9
The SO _X and N in the flue gas to supply the
O _X can be reduced.

Further, in the wet absorption device 14, stripping is performed to
NH ₃ contained in the produced gas by separating ₃ from the absorbing liquid and treating this with the combustion exhaust gas in a denitration device.
Can be effectively used for denitration.

Further, since the dry desulfurization device 7 is used as the desulfurization device, problems such as a decrease in thermal efficiency and deterioration of the absorbing liquid do not occur.

Furthermore, by detecting the concentrations of SO _X and NO _{X in} the exhaust gas after denitration and by-passing by this to control the bypass flow rate supplied from the wet absorption device 14 to the gas turbine 9, the SO _X and NO _X are controlled. It is possible to perform optimum operation in terms of the reduction of power consumption and plant efficiency.

[Experimental example]

The SO _X and NO _X concentrations in the exhaust gas were measured in a test using a basic experimental device (coal throughput of 100 kg / H) having the configuration of Fig. 1 (excluding the exhaust gas boiler), and the results in Table 1 were obtained. Obtained. In addition, the conventional example in Table 1 shows the test result by the apparatus having the configuration shown in FIG.

According to this, it was confirmed that the present invention can significantly reduce the concentrations of SO _X and NO _{X in} the exhaust gas.

[Effects of the Invention] As described above, according to the present invention, NO in exhaust gas of a gas turbine that burns gas produced in a coal gasifier
_X and SO _X can be reduced, and NH ₃ in the produced gas can be effectively used for denitration.

In addition, the plant can be operated without reducing the overall thermal efficiency of the plant.

[Brief description of drawings]

FIG. 1 is a system diagram of an apparatus for carrying out the present invention, and FIG. 2 is a system diagram of a conventional coal gasification combined plant. 1 ... Coal, 2 ... Mill, 3 ... Gasification furnace, 4 ... Sensible heat recovery heat exchanger, 5 ... Coarse dedusting device, 6 ... Char recovery line, 7 ... Dry desulfurization device, 8 …… Precision dedusting device, 9 …… Gas turbine, 10 …… Denitration device, 11 …… Exhaust gas boiler, 12 …… Chimney, 13 …… Bypass line, 14 …… Wet absorption device, 15 …… Bypass line, 15a …… Valve, 16 …… NH ₃ supply line, 17a …… SO _X meter, 17b …… NO _X meter

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // B01D 53/14 C 53/60 53/77

Claims (1)

[Claims] 1. In a coal gasification combined plant equipped with a coal gasification furnace, a dry desulfurization apparatus and a gas turbine, a part of the gas produced in the coal gasification furnace and supplied to the gas turbine is used as a coal gasification furnace. Withdrawing from between the gas turbine and introducing it into the wet absorption device to remove the sulfur content and nitrogen content in the gas and then supplying it to the gas turbine,
A method for operating a coal gasification combined plant, characterized in that NH ₃ in the absorption liquid is collected by the wet absorption device and introduced into a denitration device together with the combustion exhaust gas from the gas turbine for treatment.