JP3993472B2 - Operation control method of gasification furnace for coal gasification combined power plant - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a crude gas of coal (pulverized coal) generated in a coal gasification furnace is purified by a gas purification facility to generate fuel gas, and the fuel gas is burned by a gas turbine to produce a coal gasification power plant. The present invention relates to a gasification furnace to be used, and more particularly to a char circulation type coal gasification power plant system in which unburned coal (hereinafter referred to as char) generated in the gasification furnace is returned to the gasification furnace to improve combustion efficiency. .
[0002]
[Prior art]
Generally, a coal gasification combined power plant is provided with a coal gasification furnace that generates flammable gas by reacting pulverized coal with a gasifying agent, and gas purification equipment for the crude coal gas generated in the gasification furnace The fuel gas is generated by refining the gas, and the fuel gas is combusted by the gas turbine. The exhaust heat of the exhaust gas combusted by the gas turbine and steam are generated by the gasifier equipment, and the steam turbine is driven by the steam. It is configured to generate electricity, and after cooling the pyrolysis gas generated in the gasification furnace in recent years with a boiler, etc., it collects fine unburned coal (char) with a recovery device such as a cyclone to collect coal gas. It was returned to the chemical furnace to improve thermal efficiency.
[0003]
This technique will be described with reference to FIG. 2. In FIG. 2, reference numeral 1 denotes an air blown pressurized two-stage entrained bed gasification furnace comprising a combustor 1a and a reductor 1b. After injecting air and, if necessary, oxygen-enriched air for high-temperature combustion, pulverized coal (coal) is further introduced into the upper reductor 1b, and dry distillation gasification is performed using the high-temperature combustion gas of the combustor 1a. Let The gasified product gas such as CO and H ₂ is cooled by a cooler 12 such as a heat recovery boiler, and then char is recovered and separated by a porous filter, a cyclone or the like, and then a gas heat exchanger 21 and a COS converter 22 are obtained. , through the gas heat exchanger 23 at gas cooling tower 14 and the gas washing tower 15, cooling, after being cleaned, it is fed to the H ₂ S absorption tower 16, to remove the H ₂ S.
In the H ₂ S absorption tower 16, sulfur compounds such as H ₂ S, COS and the like in the crude gas are removed by the absorption liquid to an allowable concentration below the gas turbine 17.
[0004]
On the other hand, the gas refined in the H ₂ S absorption tower 16 is heated in sequence in the steam heat exchanger 24, the gas heat exchanger 23 and the gas heat exchanger 21 and sent to the gas turbine 17, where combustion power generation is performed. On the other hand, the combustion exhaust gas from the gas turbine 17 is cooled by an exhaust heat recovery boiler (not shown), and at the same time, the high pressure steam heated by the cooler 12 is recovered, and the steam obtained here is a steam turbine (not shown). To generate electricity.
[0005]
The absorbent that has absorbed the sulfur compounds H ₂ S and the like in H ₂ S absorption tower 16 is sent to the absorption liquid regenerator 18, de the H ₂ S which is absorbed by heating the absorption liquid regeneration heater 19 Played away.
[0006]
However, the calorific value of the fuel gas generated in such a char recirculation-type coal gasifier has fluctuated due to fluctuations in the input amount of unburned coal (char) generated.
Generally, the char input amount is controlled in combination with the weight control so as to keep the hopper weight of the circulation system constant or to keep the calorific value to some extent. It is extremely difficult to prevent the char input amount from fluctuating due to temporary clogging of the burner and the conveyance path or fluctuation in the flow rate in the conveyance path from the hopper to the gasification furnace when jetting into the gasification furnace and burning. It was.
The calorific value fluctuates due to the fluctuation of the char. As a result, the output of the gas turbine generator, that is, the plant load fluctuates, so that a stable power output cannot be obtained.
[0007]
Especially in coal gasifiers that produce combustible gas from coal by charging coal + char, air, and oxygen into a high-pressure reactor, char, which is a particle containing unburned carbon at the gasifier outlet, is gasified. Recycled into a furnace for operation. In particular, it is sometimes difficult to stably supply the char due to partial blockage of the char transfer pipe or fluctuation in the pressure of the gasification furnace. In such a case, since the calorific value of the generated gas changes, a stable operation is hindered in the coal gas combined power generation system having a power generation device such as a gas turbine in the downstream.
In the conventional operation, control is performed to obtain a predetermined heat generation amount by adjusting the supply amount of coal or char with respect to such a variation in the heat generation amount of the generated gas. However, since the flow rate of powders such as coal and char is difficult to measure, there has been a problem in the detailed control of the calorific value.
[0008]
Japanese Patent Laid-Open No. 10-82330 exists as a prior art similar to the present invention.
However, the technology does not recirculate the char and the invention is not only fundamentally different, but also from the correction signal generator using the calorific value of the crude gas generated in the gasifier facility as a reference signal from the gasifier fuel command. The correction signal is output to the gasifier fuel command from the second controller, and the corrected gasifier fuel command is output. It presupposes that the fluctuation of the pressure accompanying the change of the fuel flow rate of the turbine is suppressed in advance, and the heating value from the gasifier equipment is assumed to fluctuate.
[0009]
In other words, this technique measures the calorific value of the crude gas, but attempts to suppress pressure fluctuations associated with the fuel flow rate on the gas turbine side based on the calorific value.
However, trying to suppress fluctuations in the amount of heat generated on the input side on the downstream side makes the correction accuracy unstable from the correction signal generator, making accurate correction difficult.
[0010]
[Problems to be solved by the invention]
In order to stabilize the gas calorific value and the output of the gas turbine, etc., the present invention calculates the gas calorific value by analyzing the combustible gas obtained from the coal gasification furnace in order to stabilize the gas calorific value and the output of the gas turbine. By controlling the combustion-supporting gas side, the heat generation amount in the coal gasification furnace is essentially stabilized, and as a result, the gas heat generation amount and the output of the gas turbine and the like are stabilized.
[0011]
[Means for Solving the Problems]
In order to solve such a problem, the present invention refines crude coal gas (combustible gas) generated in a coal (pulverized coal) gasifier facility with a gas purification facility to generate fuel gas, and the fuel gas. The gas is burned by a gas turbine to generate power, and unburned coal (hereinafter referred to as char) is recovered and separated from the crude gas via a char recovery device and returned to the gasifier via a conveyance path. In the operation control method for a gasification furnace for a coal gasification combined power plant, CO and H ₂ are measured by a gas analyzer in coal gas in crude gas after the char is recovered by the char recovery device. , CO ₂ , H ₂ O, CH ₄ component content ratio of three or more components including CO, H ₂ , CH ₄ , deviation ΔH of the generated gas calorific value obtained from the function set in the analyzer Based on gasifying agent As a gasifying agent, a gas containing a relatively large amount of nitrogen (for example, air) and a gas containing a large amount of oxygen (for example, oxygen-enriched air) are increased or decreased to keep the oxygen gas flow rate in the gasifying agent constant. The flow rate of nitrogen in the gasifier is increased / decreased, and the oxygen concentration in the combustion support containing oxygen introduced into the gasifier is adjusted, so that the calorific value of the combustible gas generated from the gasifier is controlled to be constant. It is characterized by driving while.
In this case, the temperature in the coal gasifier is measured, and as a function of the temperature, the amount of oxygen gas flow in the gasifying agent is increased or decreased by increasing or decreasing the amount of air and oxygen-enriched air that are injected into the coal gasifier. It is better to adjust the oxygen concentration while keeping the constant.
[0012]
According to this invention, the char gas immediately after the coal gas furnace outlet is mixed, and the char gas is recovered by the char recovery device, and then the coal gas in the crude gas separated from the char is analyzed. Therefore, there is no blockage due to the char of the sample grin, and a gas component necessary as a heat generating component can be detected.
[0013]
The present invention will be specifically described.
In the coal gasification furnace, the ratio of the flow rate of coal and the flow rate of oxygen in the gasifying agent that can achieve a predetermined calorific value of generated gas is set and operated. At this time, the flow rate ratio of oxygen gas and nitrogen gas contained in the gasifying agent, that is, the oxygen concentration is operated at a constant value.
In the gasifier, oxygen in the gasifying agent reacts with coal, and gases such as CO, CO ₂ , H ₂ O, H ₂ , and CH ₄ are generated in the product gas. At this time, the combustible gas such as CO, H ₂ and CH ₄ in the product gas is diluted with nitrogen or non-combustible gas such as CO ₂ and H ₂ O contained in the gasifying agent, and the generated gas generates heat. The amount is determined.
[0014]
Here, for example, when the recycled char flow rate varies for some reason, the gas flow rates of CO, CO ₂ , H ₂ O, H ₂ , CH _4, etc. in the product gas also vary. And when the nitrogen flow rate which occupies most of the component which dilutes combustible gas is constant, the emitted-heat amount of generated gas also fluctuates.
Therefore, when such a calorific value variation occurs, the calorific value in the product gas can be controlled to be constant by adjusting the nitrogen flow rate in the gasifying agent so as to cancel the calorific value variation.
[0015]
Specifically, when a gas containing a large amount of nitrogen, such as air, and a gas containing a large amount of oxygen, such as oxygen, are introduced into a coal gasifier, nitrogen is used when the generated gas has a reduced calorific value. By reducing the flow rate of the gas containing a large amount and increasing the flow rate of the gas containing a large amount of oxygen, while maintaining the oxygen gas flow rate in the gasification agent constant, reducing the flow rate of nitrogen in the gasification agent, The calorific value of the product gas rises and can be recovered to a predetermined value. In addition, by reducing the nitrogen flow rate in the gasifying agent, the temperature of the gasification furnace rises, and the gasification reaction of coal is accelerated, and the flow rate of combustible gas such as CO, H ₂ , CH ₄ is increased. It increases and contributes to recovery of the generated gas heat generation.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, unless otherwise specified, the dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention.
FIG. 1 is a block diagram showing the main part of a coal gasifier according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an air blown pressurized two-stage entrained bed gasifier comprising a combustor 1a and a reductor 1b. After laminating pulverized coal (coal) from the coal supply device 19 and char from the transport pipe 8 and further air and oxygen-enriched air from the oxygen supply air supply device 7 and oxygen-enriched air supply device 7 in 1a Further, pulverized coal (coal) is further introduced into the upper reductor 1b, and dry distillation gasification is performed using high-temperature combustion of the combustor 1a. The gasified product gas such as CO or H ₂ is cooled by a cooler 12 such as a heat recovery boiler, and then char is recovered and separated by a char recovery device 13 such as a porous filter or a cyclone, and then gas purification equipment 20 Then, the purified gas is sent to the gas turbine 17 for predetermined power generation, while the combustion exhaust gas from the gas turbine 17 is cooled by a waste heat recovery boiler (not shown) and at the same time has a high pressure. Steam is collected and sent to a steam turbine for power generation.
The char recovered and separated by the char recovery device 13 is temporarily stored in the char supply device 2 such as a hopper, and then returned to the gasification furnace 1 through the transport pipe 8.
[0017]
On the other hand, in the crude gas line 13a after the char is recovered and separated by the char recovery device 13, CO, H ₂ , CO ₂ , H ₂ O, and CH ₄ in the crude gas are measured before going to the gas purification facility 20. The gas analyzer 3 is provided, and the analysis result is sent to the analyzer 5.
A temperature sensor 4 is attached to the upper part of the coal gasification furnace 1, and the furnace temperature measured by the sensor 4 is also sent to the analysis device 5.
[0018]
Next, a first embodiment of the present invention will be described.
In the first embodiment, the actual calorific value of the product gas is calculated from the function set in the analyzer 5 from the content ratio of the three components CO, H ₂ , and CH ₄ related to the heat generation measured by the gas analyzer 3. ((H ± ΔH) is obtained. In this case, CO ₂ and H ₂ O may be corrected as an endothermic reaction, where H is a reference target heating value.
[0019]
From the actual calorific value of the product gas ((H ± ΔH)), the oxygen concentration in the combustion support containing oxygen to be introduced into the gasifier 1 is determined.
The oxygen concentration of the combustion support is calculated from the air Qair charged into the gasification furnace 1, the flow rate Qoxy of the oxygen-enriched air, and the oxygen concentration ro2 in the oxygen-enriched air Qoxy by the following equation.
Here, the oxygen concentration is adjusted to obtain y ′ as the oxygen concentration necessary for adjusting the flow rate of both or one of oxygen-enriched air and air, which are the combustion support agents to be fed into the coal gasification furnace 1.
[0020]
That is, when a deviation ΔH occurs in the calorific value measured by the gas analyzer with respect to the set coal, air, oxygen, and flow rate with respect to the target calorific value H,
(H ± ΔH / H) = {1/1 + (1 / y ′)} / {1/1 + (1 / y)}
1+ (1 / y ′) = {1+ (1 / y)} * (H ± ΔH / H)
y ′ = 1 / {1+ (1 / y)} * (H ± ΔH / H) −1
It becomes.
Therefore, it is calculated as O ₂ concentration y ′ = 0.21 * air + oxygen-enriched air * ro 2 / air + oxygen-enriched air,
The air supply device 6 and the oxygen-enriched air supply device 7 are controlled and adjusted.
[0021]
In the second embodiment, the temperature inside the furnace is measured by the temperature sensor 4 and the distribution of air or oxygen-enriched air is adjusted so that the O ₂ concentration becomes y ′. In this case, measurement is performed including CO ₂ , H ₂ O affecting heat absorption in addition to CO, H ₂ , CH ₄ related to heat generation.
Specifically, in the coal gasification furnace, the operation is carried out by setting the ratio between the coal flow rate and the oxygen flow rate in the gasifying agent that can achieve a predetermined calorific value of the generated gas. At this time, the flow rate ratio of oxygen gas and nitrogen gas contained in the gasifying agent, that is, the oxygen concentration is operated at a constant value.
In the gasifier, oxygen in the gasifying agent reacts with coal, and gases such as CO, CO ₂ , H ₂ O, H ₂ , and CH ₄ are generated in the product gas. At this time, the combustible gas such as CO, H ₂ and CH ₄ in the product gas is diluted with nitrogen or non-combustible gas such as CO ₂ and H ₂ O contained in the gasifying agent, and the generated gas generates heat. The amount is determined.
[0022]
Here, for example, when the recycled char flow rate varies for some reason, the gas flow rates of CO, CO ₂ , H ₂ O, H ₂ , CH _4, etc. in the product gas also vary. And when the nitrogen flow rate which occupies most of the component which dilutes combustible gas is constant, the emitted-heat amount of generated gas also fluctuates.
Therefore, when such a calorific value variation occurs, the calorific value in the product gas can be controlled to be constant by adjusting the nitrogen flow rate in the gasifying agent so as to cancel the calorific value variation.
[0023]
Specifically, when a gas containing a large amount of nitrogen, such as air, and a gas containing a large amount of oxygen, such as oxygen, are introduced into a coal gasifier, nitrogen is used when the generated gas has a reduced calorific value. By reducing the flow rate of the gas containing a large amount and increasing the flow rate of the gas containing a large amount of oxygen, while maintaining the oxygen gas flow rate in the gasification agent constant, reducing the flow rate of nitrogen in the gasification agent, The calorific value of the product gas increases and can be restored to a predetermined value. In addition, by reducing the nitrogen flow rate in the gasifying agent, the temperature of the gasification furnace rises, and the gasification reaction of coal is accelerated, and the flow rate of combustible gas such as CO, H ₂ , CH ₄ is increased. It increases and contributes to recovery of the generated gas heat generation.
[0024]
For example, when the temperature in the gasification furnace 1 is as high as around 1500 ° C. and the amount of CO ₂ and H ₂ O is large, the amount of oxygen-enriched air input is reduced and CO and H ₂ are increased by endothermic reaction. Good. In other words, H ₂ O, CO ₂ and C such as char are reacted with each other by an endothermic reaction to form H ₂ , CO to form a gas component useful as a fuel.
If the ratio of CO, H ₂ , and CH ₄ is small, the thermal decomposition reaction has not progressed. Therefore, it is preferable to reduce the amount of air and increase the distribution ratio of oxygen-enriched air to increase the temperature. .
If the ratio of CO, H ₂ , CH ₄ is low and the furnace temperature is 1300 ° C or lower, the polymer hydrocarbon is in a tar state and the thermal decomposition is insufficient. It is better to increase O2 and raise the furnace temperature.
[0025]
【The invention's effect】
As described above, according to the present invention, by analyzing the combustible gas obtained from the coal gasification furnace, calculating the gas calorific value, and controlling the combustion-supporting gas side, essentially the inside of the coal gasification furnace As a result, it is possible to stabilize the heat generation amount of the gas and the output of the gas turbine or the like.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a main part around a coal gasifier according to an embodiment of the present invention.
FIG. 2 is an overall view of a combined coal gasification combined power generation system corresponding to FIG. 1 according to the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Gasification furnace 3 Gas analyzer 4 Temperature sensor 5 Analysis apparatus 6 Air supply apparatus 7 Oxygen-enriched air supply apparatus 13 Char recovery apparatus 13a Coarse gas line

Claims (2)

While generating crude fuel gas (combustible gas) generated by coal (pulverized coal) gasification furnace equipment by gas purification equipment and generating fuel gas, the fuel gas is burned by gas turbine to generate electricity A gasification furnace for a combined coal gasification combined power plant configured to recover and separate unburned coal (hereinafter referred to as char) from the crude gas via a char recovery device and return it to the gasification furnace via a conveyance path. In the operation control method,
After the char is recovered by the char recovery device, CO of the components of CO, H ₂ , CO ₂ , H ₂ O, and CH ₄ measured by a gas analyzer in the coal gas in the crude gas from which the char has been separated, It contains a relatively large amount of nitrogen as a gasifying agent based on the deviation ΔH of the calorific value of the product gas determined from the function set in the analyzer from the content ratio of three or more components including H ₂ and CH ₄ Increasing and decreasing gas and oxygen-rich gas, increasing and decreasing the nitrogen flow rate in the gasifying agent while keeping the oxygen gas flow rate in the gasifying agent constant, and supporting oxygen containing oxygen to be introduced into the gasifier A method for controlling the operation of a coal gasifier, comprising adjusting the oxygen concentration therein and controlling the combustible gas generated from the gasifier so that the amount of heat generated is constant.   Measure the temperature in the coal gasifier, and increase or decrease the air and oxygen-enriched air that are the combustion supporter to be input to the coal gasifier as a function of the temperature, and keep the oxygen gas flow rate in the gasifier constant. 2. The operation control method for a coal gasifier according to claim 1, wherein the oxygen concentration is adjusted while maintaining the temperature.

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