JPS62185788A - Feeding of coal in coal gasification power generation - Google Patents

Abstract

PURPOSE:To improve the thermal efficiency in a coal gasification power generation system, by drying an aqueous slurry of a coal which is to be fed into a coal gasification oven by means of a drier wherein the exhaust gas from a gas turbine is utilized and neumatically conveying only a powdered coal to feed into the coal gasification oven. CONSTITUTION:A drier 4 is provided wherein the exhaust gas (a) from a gas turbine 1 is utilized, by means of which an aqueous slurry of a coal (c) is dried to remove the slurry water [to discharge it from the system as steam (d)]. Thus, only a coal (e) is fed into a coal gasification oven 5 by neumatic conveying. The drying of the aqueous slurry of a coal will make the feed into the gasification oven 5 equal to that in a dry feeding system; therefore, the temperature drop in the gasification oven due to the heat of vaporization of the slurry water can be prevented. Consequently, as compared with a system wherein an aqueous slurry of a coal is directly fed, the ash in a coal can be melted well with a lower air ratio to be discharged from the oven, and therefore the thermal efficiency in a coal gasification power generation system can be improved correspondingly.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a coal feeding method in a coal gasification combined cycle power generation.

(Prior Art and its Problems) In contrast to oil-fired power generation, which has traditionally been the mainstream in thermal power generation, power generation using coal as fuel is beginning to attract attention.

In order to achieve this, coal is first gasified without burning the coal itself, and then the combustion gas is used to generate combined power generation with high efficiency.For example, a gas turbine is driven by the combustion gas, and its waste heat is supplied to a boiler. So-called combined power generation, in which power is generated by a steam turbine driven by the steam generated by the steam, is attracting a lot of attention.

By the way, in realizing thermal power plants, which are almost always built around cities, there are well-known problems such as difficulty in securing land due to the need for large-scale coal storage facilities, increased construction costs, and problems with the surrounding environment. There is a strong demand for a solution to the pollution problem caused by As a solution to this problem, a so-called coal-water slurry feed method was proposed in which pulverized coal is transported through a pipeline using water as a carrier. This method has the advantage of superior handling compared to the dry feed method, which transports pulverized coal through pipelines using air as a carrier, and allows coal to be unloaded far from the power plant. can be pulverized and transported to power plants. Therefore, the above-mentioned problems of land acquisition difficulties and pollution can be solved all at once, and the momentum for its adoption is increasing recently.

However, if you try to gasify coal that has been transported using the coal-water slurry feed method by directly feeding it into a coal gasifier, the dry feed method will not work because of the heat of evaporation of the slurry water that is fed into the furnace together with the coal. In comparison, it is difficult for the temperature inside the gasifier to rise, making it difficult to melt the ash in the coal and discharge it from the furnace. In order to prevent this, it is necessary to increase the air ratio in the gasifier, but this has the disadvantage that the thermal efficiency of the coal gasification combined cycle power plant inevitably decreases compared to when the coal gasification combined cycle power plant is supplied using the dry feed method. be.

(Object of the Invention) The present invention has been made with the aim of eliminating the drawbacks of the coal-water slurry feed system as described above, and will next be described in detail with reference to the drawings.

[Method of invention]

(Means for Solving the Problems) The present invention is characterized by the following points. That is, as shown in Fig. 1, which shows a conceptual diagram of the configuration, the exhaust heat (a) of the gas turbine (1) is recovered and the driving steam (2) of the steam turbine (2) is recovered.
b) By installing a dryer (4) using the exhaust heat (for example, around 150°C) in the gas turbine (11 exhaust heat recovery boiler (3)) to make the coal-water slurry (C) Slurry water is released as steam (d) to the outside of the system (4a is a steam release blower), and pulverized coal (a)
This is characterized by supplying only the coal gasifier to the coal gasifier (5) by air conveyance.

In Figure 1, (5) is a coal gasification furnace, (6) is a gas cooler, (7) is a gas purification device, (8) is a combustor, (
9) is an air compressor, a is a booster, αD is a generator, α is a generator, α is a condenser. and coal gasifier (
The gas (f) produced by 5) is a cooling bag! The combustion air (g
) together with the gas turbine (1).
A working gas (i) is produced, which drives the driving gas turbine (1) of the generator αD to generate electricity. In addition, the gas turbine exhaust heat recovery boiler (3) receives condensate from the condenser α of the steam turbine (2) and generates steam U), which is in turn generated by the gas cooler (
Together with the steam (g) produced using the heat from step 6), the steam turbine (2) for driving the generator (b) is driven to generate electricity. a4) is the slurry tank, Q51 is the feed pump,
α is an exhaust stack, αη is a pulverized coal bin, α is a lock hopper, al is a supply hopper, and (to) is a feed burner, which is the pulverized coal obtained by drying and separating slurry water in the dryer (4). (e) is sent to the pulverized coal bin aη by air flow conveyance, is pressurized by the lock hopper (to), and is sent to the coal gasifier ( 5) is dry fed. Note that the figure shows a simplified steam system.

(Effect) As described above, if the coal-water slurry is dried by the exhaust gas of the gas turbine +1) and only the coal is supplied into the coal gasifier, the coal supply to the gasifier (5) will be reduced. It is equivalent to the dry feed method, and can prevent the temperature inside the gasifier from decreasing due to the heat of evaporation of slurry water. As a result, compared to the coal-water slurry direct feed method, the ash in the coal can be well melted and discharged from the furnace with a lower air ratio, and the thermal efficiency of the combined power generation system can be increased accordingly.

According to trial calculations, as shown in Figure 2, the air ratio in the gasifier can be lowered by about 0.07 compared to the case where coal-water slurry is directly fed. It was found that the relative value could be improved by about 2.2% compared to the case of direct feeding. Note that FIG. 2 shows the relative thermal efficiency in dry feed coal transportation for reference.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram of the structure of the present invention, and FIG. 2 is a comparison diagram of various feed methods and relative thermal efficiency. (Former...gas turbine, (2)...steam turbine, (
3)...Gas turbine exhaust heat recovery boiler, (4)...
・Dryer that utilizes gas turbine exhaust heat, (5)...
Coal gasifier, (6)...gas cooler, (7)...
Gas purification equipment, (8)...combustor, (9)...compressor, α [booster, α-to...generator, (b)...generator, Q31...condenser ,Q4)...slurry tank,
α9...Feed pump, aQ...Exhaust stack,
aη...Pulverized coal bin, α smell...lock hopper, α saliva...supply hopper, (2m...feed burner.

Claims (1)

[Claims] Coal gas characterized in that it is equipped with a dryer that utilizes the exhaust gas of a gas turbine, thereby once drying the coal water slurry, separating and removing the slurry water, and supplying only the coal to the coal gasifier by airflow conveying it. Coal feeding method in combined cycle power generation.