JPS63297736A - Heating value controlling method for entrained bed coal gasifying furnace upon load fluctuation - Google Patents

Abstract

PURPOSE:To control the heating value constant in separately supplying a coal and a gasifying agent to upper and lower stages of a gasifying furnace by controlling a ratio of gasifying agent quantity/coal quantity in the upper stage variably according to a quantity of load fluctuation and controlling the ratio in the lower stage in constant. CONSTITUTION:A pulverized coal pulverized by a coal pulverizer 1 is filled into a supply hopper 2. Then, a supply quantity of the pulverized coal is set by a coal supplying device 3, and the pulverized coal is supplied with an inert gas through branch pipes 4 to upper and lower stages of a gasifying furnace 7. On the other hand, a gas from a gasifying agent compressor 11 is supplied through upper and lower stage gasifying agent flow control valves 14 and 13 to coal burners 5 and 6, respectively. The gas at the outlets of the coal burners 5 and 6 contacts the pulverized coal to gasifying the same. A gasified coal formed in the gasifying furnace 7 is supplied through a refiner 15 to a combustor and a gas turbine 12. A formed gas analyzer 16 is provided to detect a CH formation quantity and a heating value of the formed gas. According to a detection value of the analyzer 16, the flow control valves 13 and 14 are controlled by a controller 23 to specify a ratio of gasifying agent quantity/ coal quantity in supplying the gasifying agent.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a spouted bed coal gasifier, and particularly to a pulverized coal spouted bed gasifier for gasification using oxygen-containing gas (air and oxygen), etc. The present invention relates to a method of controlling the generated gas calorific value to a constant value even if the coal supply amount fluctuates.

[Conventional technology]

Coal has the largest reserves and is attracting attention as an energy alternative to petroleum.Coal is solid and inconvenient to handle, and it has a high ash content.
It contains sulfur, nitrogen, etc., and in order to use it effectively, it is desirable to convert it into a clean energy source. Coal gasification is attracting attention as an effective method for achieving a clean fuel ratio, and among these, the coal gasification combined cycle system, which uses clean gas from coal for power generation, is attracting attention.

As shown in Figure 2, in this combined power generation system, pulverized coal produced by a crusher 1 is supplied to a gasification furnace 2 and reacted with a gasification agent, and the generated gas is purified by dust collection and desulfurization equipment, etc. Equipment It
3, the gas is supplied to the combustor 4, the combusted gas is sent to the gas turbine 5, the waste heat energy is converted into steam by the waste heat boiler 6, and the steam is used to power the steam turbine. 7 to generate electricity.

In this method, it is important to control heat generation when it is desired to reduce the load amount, such as at night and on holidays. If the calorific value fluctuates when the load fluctuates, it is conceivable that the combustion of the gas turbine itself will be adversely affected.

Conventional control methods during load fluctuations include: (1) using a tank to temporarily store coal gasification gas after the refining equipment (Japanese Patent Application Laid-Open No. 57-61086); (2) pressure of the coal gasification furnace; A typical method is to perform variable pressure operation by lowering the pressure to a level that can supply the fuel gas required by the gas turbine.

For example, in method (1), as described in Japanese Patent Application Laid-open No. 57-61086, coal gasification gas generated in a gasification furnace is purified and then temporarily stored in a tank, and then used as needed. , and is supplied to the combined power generation system in response to load fluctuations and the amount of fluctuation. This has the advantage of improving the ability to respond to load fluctuations, and making it possible to generate electricity using the gas in the storage tank during maintenance and inspection of the gasifier or in the event of a failure.

In addition, the method (2) is equipped with a gasifier control device set to a variable pressure mode as described in JP-A-59-134331, and a load request signal is input to this gasifier control device. The gasifier control device gives a command signal according to the load to the coal supply equipment and gas compressor, and automatically controls the fuel supply pressure of the gas turbine during partial load operation to perform variable pressure operation. It is something.

[Problem that the invention seeks to solve]

In gasification combined cycle power generation, in which coal is gasified in an entrained bed gasifier and the resulting gas is used as fuel for the power generation system, the calorific value of the fuel gas is reduced so that the operation of the gas turbine will not be affected even during load fluctuations. must be maintained approximately constant.

In general, the above (1) and (2) are typical control methods for responding to load fluctuations. However, in method (1), the gasification equipment itself is under high pressure.

Storage tank manufacturing technology 1 There is a drawback that there are restrictions on the size of the tank and its installation location depending on the power generation capacity. In addition, when the flow rate control valves and produced gas intake valves installed at the inlet and outlet of the storage tank are operated for a long time, their operability deteriorates due to thermal wear and other factors, resulting in a reduction in the flow rate of combustion gas supplied to the gas turbine. It is possible that the adjustment becomes difficult. Additionally, the plant requires new equipment such as tanks and valves, which tends to complicate the gasification process.

There is a drawback that the operability of the gasifier is deteriorated.

In method (2), by controlling the variable pressure operation, there is a possibility that the response to the load on the gas and other furnace side 9 coal supply systems will be significantly delayed, and there are drawbacks such as a decrease in the load response capacity.

An object of the present invention is to provide a method that can easily control and maintain a constant calorific value in response to load fluctuations and load fluctuations when a spouted bed coal gasifier is combined with a combined cycle power plant.

[Means for solving problems]

The above purpose is to install a produced gas analyzer that can detect CH4 and calorific value in the produced gas at the gasifier outlet, and in response to load fluctuations, the produced gas analyzer will send a command signal according to the load to the gasifier. The agent amount/coal amount ratio control device is applied to the gas and other agent control devices via the gasifier, and this is achieved by specifically adjusting the upper stage gasifying agent amount 7 right coal amount ratio in response to fluctuations in calorific value. It is something to do.

In order to overcome the above-mentioned drawbacks and improve load handling, the pressure of one gasifier should be kept constant, the ratio of the upper and lower coal supply rates should be 1:1, and only the amount of gasifying agent should be changed. So I thought it would be good if I could control it.

Therefore, first of all, to explain the basics of operation of this gasifier, the lower stage promotes slagging by raising the temperature above the temperature at which the ash content in the coal is welded, the upper stage promotes the generation of active char, and the lower stage as much as possible. It is to supply the high temperature zone. In order to satisfy the lower requirement, the temperature in the furnace increases by supplying the gasifying agent in excess of the amount of coal supplied, and a temperature at which the ash melts is obtained. A highly active char is produced in the upper stage by supplying a fraction of the amount of gasifying agent to the lower stage. During steady operation, when the amount of lime is constant and the total amount of gasifying agent (air) 7 is increased, the ratio of amount of lime is increased, Hz t COp CH in the generated gas
4 decreases and COz increases, so the calorific value decreases1
The calorific value of the generated gas for power generation fuel is at least 800 kc
al/Nrd or more is required, and in order to increase the amount of heat, it is necessary to control the overall gasifying agent amount/coal amount ratio to a low level. However, if the gasifying agent amount/coal amount ratio is too low, the temperature near the lower stage will decrease, making it difficult for the slag to flow down, and it is conceivable that the slab tap hole will be clogged.

Therefore, during coal supply fluctuation operation, 800kca
If gasification is performed by changing from a high load to a low load while keeping the overall gasifying agent amount/coal amount ratio (upper and lower stage gasifying agent amount/coal amount ratio constant) satisfying l/Nrn' or more.

As the flow rate of coal supplied to the gasifier decreased and the overall temperature inside the furnace decreased, the reaction rate slowed and the calorific value decreased. Therefore, it became necessary to consider setting conditions other than the above conditions.

Therefore, as mentioned above, the purpose of the lower gasification conditions is to raise the temperature above the melting temperature of the ash, so the lower gasification conditions are such that the ratio of gasifying agent amount/lime amount is constant even if the load changes, and the upper gasification conditions are The aim is to control the amount of heat generated by considering the following.

Therefore, we decided to focus on methane, which has the highest calorie among the produced gases, and to understand the conditions for methane production.

First, we investigated the effect of temperature on methane production using a small external heating reactor. The result is shown in Figure 3. This figure shows that the amount of methane produced is dominated by temperature, and that the temperature near the upper stage is preferably 1400°C or lower. Further, FIG. 4 shows the result of investigating the influence of the air ratio on the amount of gas produced at a temperature of 1200°C. As shown in this figure, when a small amount of air was supplied, Hz and Go rose sharply, but on the contrary, CH4 suddenly fell. The reason for this is thought to be that CH4 reacts with oxygen to generate Hz and Co2, and the gasification of volatile components is proceeding.

CHa+1/20z→CO+ 2 HzCH4+ 20
x-e COz+ 2 HzO As the air is further increased, gasification of char occurs, and this reaction causes C+
COz→2CO2C+HxO→CO+ HzCO, H
Consider that z increases.

As described above, by referring to these results and changing the upper stage gasifying agent amount/coal amount ratio, it becomes possible to control the calorific value.

[Effect]

That is, CHa in the produced gas is present in the outlet line of the gasifier.
After installing a produced gas analyzer with arithmetic functions to detect the amount of CH4 gas produced and calorific value, and understanding the amount of CH4 gas produced and calorific value during load fluctuations, these signals are adjusted to a certain set amount of gas. A signal from the gas and other agent control device is sent to the upper and lower gas and other agent flow control valves through the gasifying agent amount/coal amount ratio control device, and the gasifying agent amount/coal amount is By changing the amount ratio at a constant value and adjusting the amount of CH4 generated while changing the gasifying agent amount/coal amount ratio in the upper stage, the aim is to achieve control that maintains the calorific value even when the load is reduced. .

〔Example〕

FIG. 1 shows the configuration of an embodiment of the present invention.

The overall configuration includes a lime supply system, a gasifying agent supply system, a gasifier, a purification device, and a control system.

The coal supply system consists of a crusher 1. It consists of a pulverized coal transport line 24, a coal supply hopper 22, a coal supply device 3, an air flow transport line 19, and a branch pipe 4. The pulverized coal pulverized by the pulverizer 1 passes through the pulverized coal transport line 24 and is filled into the 1 coal supply water tank 2. After setting the supply amount with the 1 coal supply device 3, it is heated with an inert gas (N2° COz, etc.). Airflow transport, airflow transport line 1
After passing through the pipe 9 and branching into upper and lower stages at the branch pipe 4, the gas is supplied to the gasifier 7. At this time, the amount of coal supplied to the upper and lower stages is the same.

The gasification agent supply system includes a gas and other agent compressor 11. It consists of a lower stage gasifying agent flow rate control valve 13 and an upper stage gasifying agent flow rate controlling valve 14.

The gas from the gas and other agent compressor 11 passes through the gas and other agent line 20, and passes through the upper and lower gas and other agent flow rate control valves 14 and 13.
The coal is supplied to coal burners 5 and 6 installed at the upper and lower stages of the gasifier 7, and is gasified by contacting pulverized coal at the outlet thereof.

The gasifier 7 has upper and lower reaction zones 8 and 9, and the upper reaction zone 8 produces activated char.

In the lower reaction zone 9, coal burners 5 and 6 are installed in the lower reaction zone 8゜9 above the gasifier to keep the ash content in one coal at a temperature higher than that of melting, and the char produced in the upper reaction zone 8 is transferred to the lower reaction zone. After being supplied to a high temperature zone and reacting with Co and HzO, the ash becomes a molten sliding state, and the slag freely falls into the slag recovery device 10 filled with water, where it is rapidly cooled and then recovered.

The gas generated from the gasification furnace 7 passes through the generated gas line 22 and is purified in the purification bag W115 of the dust collection and desulfurization equipment.
Supplies the combustor and gas turbine 12.

The analysis and control system is a generated gas analysis analyzer with a calculation mechanism for CH4 generation amount and calorific value! 16 Gasifying agent control device 17, coal supply control bag [18, gasifying agent amount/coal amount ratio control device! Consists of 23.

When you want to reduce the amount of electricity at night or on holidays, issue a command to reduce the power generated from the gas turbine 12 side.

At the same time as the coal supply control device 18 began to reduce the coal supply amount, the generated gas analysis device was installed at the outlet of the gas furnace 7! 16 and detects the CHa production amount and calorific value, the signals are sent to the entire gasifying agent control device through the upper and lower gasifying agent amount/coal amount ratio control devices 23! 117, and in response to changes in load amount, gas and other agent control devices! The signal from 17 is given to the upper and lower gasifier flow rate control wells 13 and 14 to control the gasifier amount/coal amount ratio! ! 23 supplies the gasifying agent so that the specified gasifying agent amount/coal amount ratio is achieved.

At that time, the lower stage gasifier amount/coal amount ratio is such that the load amount is 100.
% to 50%, the gasifying agent amount/coal amount ratio is controlled to remain constant.

On the other hand, the upper stage gasifying agent amount/coal amount ratio is changed as the load amount changes so as to suppress the temperature near the upper stage to 1400° C. or less, and is controlled while checking the amount of CHa produced.

The gasification furnace had an inner diameter of 300 am, a reaction section height of 800 cm, and was insulated and lined with refractory material, and a slag tap with a slag flow hole was installed in the lower part of the gasification furnace.

In the reaction section of the gasifier, four lower stage coal burners were installed at 100 points from the top of the slag tap, and four upper stage coal burners were installed at 6501 points from the top of the slab tap.

A dust collector and desulfurizer was installed in the line after the gasifier to remove dust and Has from the gas, which was then incinerated in a flare stack. In addition, a gas analyzer was installed at the outlet of the gasifier, as well as a gas and other agent control device and a coal supply control device to improve the responsiveness of the gasification agent amount and coal supply amount to changes in load.

The transport conditions for pulverized coal (particle size of 0.1 sm or less) were such that the amount of nitrogen transported from the coal supply hopper to the branch pipe was 4 kg/h, and the amount of nitrogen supplied from the branch pipe was 8 kg/h. The amount of coal supplied at this time is changed from 30 kg/h to 1
The load was changed to 0 kg/h. Air was used as the amount of gasifying agent. The amount of gasifying agent is 100% coal (30k coal)
g/h) so that the total gasifying agent amount/coal amount ratio (hereinafter referred to as air ratio) is 3.5, 105 kg/h, and 30 kg so that the upper stage air ratio at this time is 2.0. /h, and the air was supplied at a rate of 75 kg/h so that the lower stage air ratio was 5.0. When reducing the load, while detecting the CHA amount and calorific value with the gas analyzer, the lower stage air ratio is kept constant at 5 according to the load, and the upper stage air ratio is determined based on the results obtained under the following conditions. I decided to control it.

Before conducting experiments under the above conditions, in order to understand the conditions for setting the upper stage air ratio in a single gasifier, the influence of the upper stage air ratio on the amount of methane produced was investigated. These conditions are: the coal supply rate is 10 kg/h and 28 kg/h, the total air ratio is constant 3.5,
The results were investigated by varying the upper stage air ratio. The results are shown in FIG. 5. As shown in this figure, as the upper stage air ratio becomes lower, the amount of C1+4 produced increases regardless of the amount of coal. The calorific value has also increased.When the amount of coal per unit is 28 kg/h and the upper stage air ratio is 2.0, the calorific value is 880 kcal/N rrr.
It is. If control is attempted using this calorific value as a guideline, it is necessary to set the upper stage air ratio to 1.0 when the amount of coal is 10 kg/h.

Based on the above results, we decided to set the upper stage air ratio,
I decided to conduct an experiment under the conditions described above.

The results are shown in Figure 6, where the horizontal axis is the coal supply amount.

The vertical axis shows the amount of heat generated and efficiency. The dotted line in the figure is the result when the total gasifying agent amount/coal amount ratio was set to 3.5 and the air ratio in the upper and lower stages was kept constant even if the load amount changed. As shown in this figure, compared to the conventional method, the amount of heat generated could be controlled to be constant even if the amount of load changed.

As described above, according to this embodiment, the amount of heat generated could be maintained constant even when the load fluctuated.

〔Effect of the invention〕

According to the present invention, by controlling the upper stage gasifying agent amount 7 coal amount ratio to change and controlling the lower stage gasifying agent amount 7 coal amount ratio to a constant value in accordance with the amount of load fluctuation, the calorific value is increased even when the load is reduced. It has the effect of maintaining a constant value.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the calorific value control method of the spouted bed coal gasifier of the present invention, Figure 2 is a system diagram of the coal gasification combined cycle process, and Figure 3 is the effect of reaction temperature on the amount of methane produced. Figure 4 is a diagram showing the influence of the air ratio on the amount of produced gas, Figure 5 is a diagram showing the influence of the upper stage air ratio on the amount of methane produced, and Figure 6 is a diagram showing the influence of the air ratio on the amount of methane produced. FIG. DESCRIPTION OF SYMBOLS 1...Crusher, 2...Coal supply hopper, 3...Coal supply device, 4...Coal branch pipe, 5...Upper stage coal burner, 6...Lower stage stone step burner, 7...・Gasifier, 8
...Upper reaction zone, 9...Lower reaction zone, 10
... Slag recovery device, 11 ... Gas and other agent compressor, 1
2... Gas turbine and combustor, 13... Lower stage gas other agent control valve, 14... Upper stage gas other agent control valve, 15...
・Purification device, 16...Produced gas analysis device, 17・
...Gas and other agent control equipment. 18... Coal supply control device, 19... Coal supply line, 20... Gas and other agent supply line, 21... Signal,
22...Produced gas line, 23...Gasifying agent amount/coal amount ratio control 2nd Kuchifu3 Figure 1σσ0 /2σσ /44)σ 16σσ
/8σσ46 Ryo (r) 94 Old Y5 Figure 1σ 2. σ upper fiAtr/cnttl certain L figure

Claims (1)

[Claims] 1. Coal supply in a spouted bed coal gasifier that uses oxygen-containing gas as a gasifier and distributes and supplies coal and gasifier to the upper and lower stages of the gasifier for gasification. Corresponding to the amount, the gasifying agent amount/coal amount ratio in the lower stage is constant at a certain value that can maintain the temperature above the melting point of the coal type, and the gasifying agent amount/coal amount ratio in the upper stage is such that the temperature near the upper stage is 1400. A method for controlling the amount of heat generated during load fluctuations in a spouted bed coal gasifier, characterized by adjusting the amount of gasifying agent so that the temperature is below ℃. 2. In claim 1, the above-mentioned upper stage gasifying agent amount/coal amount ratio is set according to the amount of methane produced in the generated gas. Volume control method.