JPS58178808A - Control system for coal gasification composite power generating facility - Google Patents

Abstract

PURPOSE:To improve the efficiency of sub-combustion of a sub-combustion burner even in case of the decreased temperature of gas turbine exhaust gas by a method wherein the rate of distribution of fuel gas to the gas turbine power generating facility and the sub-combustion burner is varied when the calory or flow rate of fuel gas is varied or when a partial load is applied. CONSTITUTION:A steam turbine power generating facility 5 is composed of a pluality of systems of a gas turbine power generating facility 3, sub-combustion burner 14 and waste heat recovery boiler facility 4, respectively. Purified gas 11 is divided into parts 11a and 11b with a distribution control device 20 and then supplied to the gas turbine facility 3 and the sub-combustion burner 14. Under a partial excessive load of the steam turbine, much more volume of fuel is supplied to the sub-combustion burner to keep a combustion gas temperature which is approximate to that of the designed value. The corresponding gas turbine is operated as a blower fan for the boiler. Thereby, it is possibl to improve an efficiency even in case of a partial loading of the gas turbine when a calory or rate of flow of the gas fuel is varied.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operating method for a coal gasification combined cycle power generation facility, and is particularly suitable for improving efficiency during partial loads. Regarding the operating method of equipment.

Figure 1 shows the block composition of a conventional coal gasification combined cycle facility. Coal 7, which is a raw material, is gasified by extracting air 8, which is an oxidizing agent, from gas turbine power generation equipment 3. In some cases, the oxidizing agent may be oxygen 9 obtained from the attached oxygen generating equipment 6, and steam, not shown here, may also be supplied as required. Gasifier equipment 1
The crude gas 10 emitted from the coal contains sulfur compounds generated from sulfur in the coal, ash, and dust particles composed of unburned carbon, and is therefore purified by the subsequent cooling and purification equipment 2. The purified gas 11 that exits this is supplied to the gas turbine power generation equipment 3.
One shot power generation now. Since there is a theoretical efficiency limit with only the gas turbine power generation equipment 3, the exhaust gas 1 of approximately 500C
2 is directly led to the exhaust heat recovery boiler equipment 4 to obtain steam 13. This steam drives the steam turbine power generation equipment 5, and as a whole, it is possible to obtain efficiency equal to or greater than that of ordinary steam power generation equipment. At present, the temperature of the exhaust gas 12 discharged from the gas turbine power generation equipment 3 does not exceed 550C due to the strength of heat-resistant materials and the limits of cooling power methods for high-temperature members. - If the usable steam conditions (pressure and temperature) of the steam turbine power generation equipment 5 improve,
It is known that it is more efficient. However, due to the limitations of the gas turbine power generation equipment 3, this 'f case cannot be expected to improve efficiency as a combined power generation equipment. In FIG. 2, an auxiliary combustion burner 14 is provided between the gas turbine power generation equipment 3 and the exhaust heat recovery boiler equipment 4, and the exhaust gas from the gas turbine power generation equipment 3 is heated to 1210°C, regardless of the type of fuel used. ,
Achieved higher temperature combustion gas18 and improved steam conditions.
The U.S.-based Nukigo power plant is shown in the Knoblock configuration (U.S.
(See P 3.443.5bo-Q). The fuel used in the United States (kerosene or natural gas) has a high calorific value;
Air 15 taken into the gas turbine power generation equipment 3 due to the
On the other hand, since a small amount (approximately 2%) of ft is supplied, the increase in the flow rate of the exhaust gas 12 is small and rare. In such a case, auxiliary combustion would rather result in a low T efficiency, and the only advantage would be an increase in output. Therefore, with conventional auxiliary combustion, the temperature of the exhaust gas 12 of the gas turbine power generation equipment 3 is extremely low.
It has been used only when fuel is cheap and output can be easily increased. Reed, known example U
σ has also been used to improve the response of a steam turbine, as in SP3879616. Back in the day, when the heat resistance of the high-temperature materials used in gas turbines was less than that of today, it was not possible to maintain the temperature at the turbine entrance. For this reason, the exhaust temperature of the gas turbine is also low, and the steam conditions of the combined cycle power generation equipment cannot be made high enough.
The electrical power that can be generated by gas turbines and steam turbines is low power. However, such combined power generation facilities were relatively easy to install, had better load followability than steam power generation facilities of the same output, and had a certain appeal.

There is a reason why equipment with such an auxiliary burner was adopted in order to compensate for the shortage of electric power supply. The temperature of the high-temperature gas (that is, the amount of fuel and steam conditions) achieved by the auxiliary combustion burner is selected by taking into consideration all factors such as the target output, efficiency, amount of equipment, etc., but it is more attractive than full-scale steam power generation equipment. It wasn't.

-10,000, coal is originally produced in coal-producing areas and coal seams.
There is considerable variation in composition. Therefore, even if the amount of coal supplied, the oxidizing agent (air or oxygen) added to the coal, and the steam added as necessary are kept constant, the fuel produced by gasifying this nitrogen will generate less heat. Quantity-? Flow rate fluctuates. Furthermore, since the weight ratio of inherent moisture, ash, hydrogen and carbon that become gases fluctuates, the amount of coal includes all of these, so even if you decide the ratio of additives to this supply amount, the flow rate will vary. The amount of heat generated fluctuates. In most cases, the power generation equipment must be controlled to meet a certain predetermined set point in order to supply the required load.

Therefore, the amount of heat generated or the flow rate fluctuates, or the amount of power generated is over or under. If there is a shortage, all you have to do is increase the amount of coal supplied and all the materials to be supplied, and if there is an excess, all you have to do is thin them out, but gasification equipment and cooling purification equipment Since it involves manual operation, its load response is not sufficiently high. In addition, the exhaust heat recovery boiler equipment supplies n
The steam generated in the process causes a delay in response due to the hold-up of heat. Only gas turbine-generated WL equipment can respond rapidly to changes in the calorific value and flow rate of the fuel.

However, gas turbine power generation equipment is limited by the mabin inlet temperature and cannot consume excess fuel and convert it into electricity. When the calorific value of the fuel increases,
If the pressure in the system is increased, the output power can be kept constant with one casing that reduces the total amount of fuel supplied to the gas turbine, but this is not possible above a certain limit. The reverse is also true.

An object of the present invention is to prevent deterioration of efficiency of a steam turbine due to a drop in exhaust gas temperature, etc., in a coal gasification combined cycle power generation facility, even when the calorific value or flow rate of gas fuel fluctuates, or when the gas turbine is under partial load. The purpose is to improve partial load efficiency and maintain load output at Pfr.

In order to achieve this objective, the present invention changes the distribution of gas fuel to the gas turbine power generation equipment and the auxiliary burner when the calorific value, IN, or amount of the gas fuel fluctuates, or when there is a partial load. The feature is that even if the gas temperature decreases, it can be handled by increasing the auxiliary combustion rate of the auxiliary combustion burner.

Hereinafter, the present invention will be described in detail based on Examples.

FIG. 3 shows a block diagram of a first embodiment of a combined coal gasification combined power generation facility to which the present invention is fully applied.

In FIG.
Although the series is shown as γ, it is good to use two or more bases in a row. - It is not necessary that the gasification furnace equipment 1 and the cooling purification equipment 2 are arranged in a row of three units. The trenched steam turbine power generation equipment 5 is configured such that one unit is provided for each of the multiple series of gas turbine power generation equipment 3, auxiliary combustion burner 14, and exhaust heat recovery boiler equipment 4.

Further, the elliptical gas 11 is divided into lla and ll by the distribution control device 20.
Divided into b: n1 gas turbine, power generation equipment 3 and auxiliary burner 1
4. For the purpose of the present invention, it is preferable that the auxiliary burner 14 is always in operation and that the steam conditions are good.

Here, the gas turbine power generation equipment 3 is a fluid machine, and has the characteristic that the total intake air volume hardly changes from no load to full load 1, and when using gas with a low calorific value such as coal gas as fuel, Compared to high calorific value fuels such as natural gas, it requires almost an order of magnitude more fuel flow rate.

In the configuration shown in Figure 3, the partial load operation method of the engine startup equipment reduces the output of all gas turbines, and as a result, the exhaust gas temperature decreases, so the amount of steam generated also decreases. In addition, there are cases in which the overall output is reduced due to lower steam conditions, and cases in which the total output is reduced by stopping some of the gas turbines or making them unloaded. The point to note here is that after exhaust heat recovery boiler 4,
The steam system has a large response delay based on its heat capacity, and the steam turbine, especially the large steam turbine used in FIG. 3, has strength constraints that do not allow sudden temperature fluctuations. Taking these characteristics into consideration, in order to compensate for the performance deterioration caused by the significant partial load of the steam turbine, more fuel is supplied to the auxiliary combustion burner to maintain the combustion gas temperature close to the design point.

In this case, the corresponding gas turbine is operated under no-load conditions to maintain its own rotational speed, as if it were a blower for a boiler. In this way, as a secondary effect, both the gas turbine and the steam turbine can be maintained in a state where they can easily respond to load increase commands.

FIG. 4 shows the block composition of a second embodiment of a combined coal gasification combined power generation facility to which the present invention is applied.

In FIG. 4, for one steam turbine power generation facility, there is one row of gasifier equipment 1 and cooling purification equipment 2, one row of gas turbine power generation equipment 3, exhaust heat recovery boiler equipment 4, and an intermediate row thereof. As a complete basic configuration, a fuel gas distribution control device 20 is provided between the cooling purification equipment 2 and the gas turbine 30, and the fuel gas 11 is distributed between the gas turbine fuel gas 16 and the auxiliary burner fuel. 17. When the calorific value or flow rate of the fuel gas 110 increases, the amount of fuel #L required to maintain a constant output of the gas turbine 3 is determined by the predetermined turbine inlet temperature (9) degrees, and becomes unnecessary above a certain temperature value. Become. If you can't consume the flow rate, t! In this case, the pressure between the gasifier equipment 1 and the gas turbine power generation equipment 3 increases, so this must be dealt with. However, since the gas system is designed at a certain design pressure, it is not possible to increase the pressure above the critical pressure. If all the auxiliary burners 14 are installed in advance to obtain exhaust gas 18 with a temperature higher than that of gas turbine exhaust gas 12, the distribution of fuel gases 16 and 17 can be changed to prevent overpressure in the gas system. It is possible to keep the output at a low level. That is, after the overpressure limit, the output of the gas turbine power generation equipment 3 is reduced, and the amount of fuel gas 16 commensurate with this reduction is supplied to the auxiliary burner 14 as the amount of fuel gas 17 subtracted from the supplied gas fuel 11. At this time,
Since the temperature of the exhaust gas 12 discharged from the gas turbine power generation equipment 3 decreases, more fuel 17 than before is consumed to compensate for this decrease and generate steam 13 which is the steam condition originally determined. . The fuel gas distribution control device 20 distributes the fuel gas covers 16 and 17 so that the sum of (10) of the output of the gas turbine generator equipment 3 and the output of the steam turbine generator equipment 5 is constant. I will make you do it. At this time, the design points of the gas turbine power generation equipment 3, the steam turbine power generation equipment 5, etc. are planned? It is determined in advance assuming the case where the calorific value of the fuel gas is the lowest or the case where the flow rate is the lowest.

The auxiliary burner 14 in FIG. 4 is constantly supplied with auxiliary burner fuel gas 17, and the exhaust gas 18 of the auxiliary burner 14 is at a high temperature compared to the temperature of the gas turbine exhaust gas 12. The turbine power generation equipment 5 can be provided with a reheat type, for example. However, it is not necessary to always supply the auxiliary burner fuel gas 17 to the auxiliary burner 14 to provide the above conditions, and this is not related to the essence of the present invention. When the calorific value of the refined gas fuel 11 that can be completely supplied increases, the overall flow rate can be reduced, but if the flow rate is reduced, the pressure in the system increases, so in response to this,
The gas turbine fuel 16 is decreased, and the auxiliary burner fuel 17 is completely increased.

(11) This distribution can be achieved by detecting the temperature of the exhaust gas 12 or the amount of power generation in the case of a gas turbine, or by detecting the temperature of the exhaust gas 12 or the amount of power generation in the case of a steam turbine, and performing feedback control by detecting the temperature of the exhaust gas 12 or the amount of power generation in the case of a steam turbine.

Quantitatively, in the current gas turbine, the turbine inlet temperature is about 1100 tr, and the exhaust gas temperature is 500 C or 5.
In this case, the steam condition of the exhaust heat recovery boiler is set to the full limit of about 450C, so it is considered to be quite difficult for the overall efficiency of the integrated power generation equipment to exceed the performance of steam power generation equipment, which is 40%. The present invention performs auxiliary combustion to reduce the inlet gas temperature of the exhaust heat recovery boiler.
If you choose C, you can select a reheat type steam turbine, and it will not be difficult to achieve an overall efficiency of over 40%. In such a configuration, in particular, the steam map side becomes larger -1=-+
However, there are economies of scale and it is desirable.

In such a case, if the partial load operation method according to the present invention is applied based on the equipment configuration, desirable results can be obtained.

As explained above, according to the present invention, deterioration in steam conditions can be compensated for by the auxiliary burner even during partial load (12), so deterioration in partial load performance of the steam turbine can be compensated for and the overall partial load efficiency can be improved. It has the effect of maintaining a high level of

In addition, the output can be controlled without causing overpressure noise in the system after the gasification equipment, even when the calorific value and flow rate of the gas fuel fluctuates due to changes in the shape of the coal and the temperature conditions of gasification. As a result, wasteful release of fuel gas due to pressure release in the middle of the system can be avoided, which has the effect of improving the overall energy utilization rate.

[Brief explanation of drawings]

Figure 1 shows the entire block configuration of a conventional coal gasification combined cycle equipment, Figure 2 shows the block configuration of a conventional coal gasification combined cycle equipment that has all auxiliary burners, and Figure 3 shows the entire block configuration of the conventional coal gasification combined cycle equipment. The entire block configuration of the first embodiment of the combined coal gasification combined power generation facility to which the present invention is applied is shown, and FIG. 4 shows the block configuration of the second example of the combined coal gasification combined power generation facility to which the present invention is applied. 1... Gasification equipment, 2... Cooling purification equipment, 3...
Gaster (13) - Bin power generation equipment, 4...Exhaust heat recovery boiler equipment. Agent Patent Attorney Toshiyuki Usuda 3 Figure 2 Tomi 4 Figure

Claims (1)

[Claims] 1. At least one row of gas turbine power generation equipment, an auxiliary combustion burner that heats exhaust gas from the power generation equipment, an exhaust heat recovery boiler equipment that recovers heat from the heated exhaust gas, and one steam turbine power generation equipment. and a coal gasification combined cycle facility comprising at least one series of gasification equipment that completely gasifies the coal and cooling purification equipment that completely cools and purifies the gas, the temperature fluctuation of the exhaust gas mentioned above. A coal gasification complex characterized in that the gas sent out from the cooling and purification equipment is distributed to the gas turbine power generation equipment and the auxiliary burner so as to maintain all the predetermined steam conditions for the steam turbine power generation equipment when the above occurs. Control method for power generation equipment.