JP3794724B2 - Gasification combined power generation facility - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a gasification combined power generation facility that generates gas fuel from solid and liquid fuel and uses it as fuel for a power generation system.
[0002]
[Prior art]
FIG. 3 shows a schematic system diagram of a conventional typical combined gasification power generation facility. In the figure, a gas cooling facility 2 for cooling the gas to a predetermined temperature is provided downstream of the gasification furnace 1 for gasifying solids and liquids, and water is supplied to the gas cooling facility 2 from the exhaust heat recovery boiler 6 through the water supply pipe 10a. The gas is supplied and used as a cooling medium for gas cooling and is vaporized and returned to the exhaust heat recovery boiler 6 again through the steam pipe 10b, heated, and then supplied to the steam turbine 8. Usually, when the exhaust heat recovery boiler 6 of the water supply source mainly performs partial load operation of the steam turbine 8, that is, transformer operation in which the pressure changes according to the load at the time of partial load, the gas cooling facility 2 is also dependent. Transformer operation will be performed.
[0003]
In the figure, 3 is a char recovery facility for recovering pulverized coal in gas, 4 is a gas purification facility for removing dust and sulfur in the gas, 5 is a gas turbine, and 7 is finally exhaust gas. A chimney for discharging the air into the atmosphere, 8 is a steam turbine, 9 is a condenser for condensing the steam that has finished work in the steam turbine 8 and returning it to water, and 10 is an exhaust heat recovery boiler that supplies the condensate as feed water again. Boiler feed pump for sending to 6, 12 driven by gas turbine 5, a compressor for so-called primary compression of combustion air to gasification furnace 1, 13 further compresses the air compressed by compressor 12 An air pressure booster for boosting the pressure, 14 is a solid or liquid fuel used as fuel for the gasifier 1, and 15 is a feed water sent by the boiler feed pump 10 to the gas cooling facility 2 and the evaporator 17. A water supply control valve 17 for allocating by ratio is an evaporator for generating a so-called primary steam of the main steam for driving the steam turbine 8 by exhaust heat of the exhaust gas of the gas turbine 5 in the exhaust heat recovery boiler 6. It is.
[0004]
The gas turbine 5 and the steam turbine 8 are connected to a generator that is not shown in the figure and generates electricity.
[0005]
Further, hereinafter, pressure-related objects such as “transformation” and “constant pressure” refer to, for example, the pressure of the water / steam system in the pipeline system including the water supply pipe 10a and the steam pipe 10b, unless otherwise specified. Therefore, the pressure of the “exhaust heat recovery boiler 6” refers to the pressure in the pipe line passing through the “exhaust heat recovery boiler 6”, and does not refer to the pressure of the exhaust gas.
[0006]
Incidentally, the exhaust heat recovery boiler 6 is a heat exchanger, and the heat exchanger cannot perform effective heat exchange unless the temperature difference between the two fluids performing heat exchange is secured to a certain level or more. In other words, if there is a very large temperature difference, the heat transfer area required for heat exchange is small, but if there is almost no temperature difference, a large heat transfer area is required, which is difficult to design and deteriorates economic efficiency. As a result, the performance is deteriorated due to an increase in pressure loss.
[0007]
At the rated load, the exhaust heat recovery boiler 6 also maintains an appropriate temperature difference between the exhaust gas of the gas turbine 5 that is a high-temperature fluid and the steam of steam that is a low-temperature fluid. The temperature drops and the temperature of both approaches.
[0008]
On the other hand, the temperature on the steam side is determined by a saturation temperature in which the drum internal pressure is the saturation pressure, and is basically a constant temperature unless the internal pressure is changed. Therefore, the temperature difference between the two gradually approaches 0, and accordingly, the amount of exchange heat decreases, and the amount of evaporation, that is, the flow rate of steam to the steam turbine 8 also decreases.
[0009]
Therefore, the exhaust heat recovery boiler 6 is transformed at a partial load or the like, and when the temperature of the exhaust gas of the gas turbine 5 is lowered, the pressure of the steam system is lowered, and an operation is always performed to ensure an appropriate temperature difference. . As a result, the pressure at the inlet of the steam turbine 8 decreases, so the output of the steam turbine 8 also decreases. However, the rate of this decrease is smaller than the rate of output decrease due to the aforementioned decrease in the amount of evaporation.
[0010]
For the reasons as described above, it is generally performed in the normal combined cycle that the transformer operation is performed at the time of partial load to improve the plant efficiency at the time of partial load.
[0011]
[Problems to be solved by the invention]
The conventional gasification combined power generation facility has the following problems to be solved.
[0012]
In other words, in the conventional gas turbine combined cycle in the conventional equipment, when the gas turbine exhaust temperature decreases during partial load, etc., in the case of transformer operation without pressure control at the steam turbine inlet, the steam system of the exhaust heat recovery boiler The pressure drops naturally. On the other hand, in the conventional combined gasification power generation facility, when water supply to the gas cooling facility is branched and supplied from an appropriate position in the exhaust heat recovery boiler, the gas cooling facility inevitably performs a transformation operation. Become. In such a case, the following problems (1) and (2) occur. Further, constant pressure operation may be performed at a certain negative pressure or lower, but in this case, there is the following problem (3).
[0013]
(1). In any operating condition, consideration must be given to avoiding steaming in the heat transfer tubes of the gas cooling equipment from the viewpoint of protecting the heat transfer tubes. When it drops, it may cause steaming and serious damage to the heat transfer tubes. Therefore, the gas cooling equipment feed water temperature cannot be set high even at the rated point. However, as shown in FIG. 4, generally, the higher the gas cooling facility feed water temperature, the higher the plant efficiency. Therefore, setting the feed water temperature low causes a problem that the plant efficiency decreases.
[0014]
(2). Gasification furnace equipment and gas cooling equipment often have a water-cooled wall structure composed of evaporator tubes. In this case, the temperature of the water cooling wall depends on the saturation temperature determined by the pressure of saturated water or saturated steam flowing inside. When the gas cooling facility is transformed, the temperature of the water-cooled wall rises and falls greatly, resulting in a large difference in thermal elongation. Therefore, special consideration is required for the structure. In particular, in a combined gasification power generation facility, for the convenience of driving a gas turbine with the product gas after gasification, the gasification furnace facility and the gas cooling facility are often housed in a pressurized vessel. There is a problem that the section is easily affected by a difference in thermal elongation between the water-cooled wall and the pressurized container.
[0015]
(3). Even when the exhaust heat recovery boiler is operated at a constant pressure, depending on the operating conditions, it may be possible to perform constant control with the steam pressure of the exhaust heat recovery boiler lowered, such as a decrease in the exhaust gas temperature of the gas turbine. However, even in such a case, since the temperature inside the gas cooling facility is sufficiently high, it is not necessary to reduce the steam pressure in conjunction with that of the exhaust heat recovery boiler, and it is desirable to perform constant control at a rather high pressure. In other words, the gas cooling facility has a problem that it cannot be used when a means for controlling the pressure in the steam system is desired independently of the operating state of the exhaust heat recovery boiler that is the supply source of the feed water.
[0016]
An object of this invention is to provide the gasification combined cycle power generation facility which solved the said problem.
[0017]
[Means for Solving the Problems]
The present invention is intended to provide the combined gasification combined power generation facility described in the following (1) and ( 2 ) as means for solving the above-mentioned problems.
[0018]
(1). A power generation facility that gasifies solid and liquid fuels and uses them as fuel for gas turbines, a gas cooling facility that cools the gas after gasification, a boiler that generates steam using the exhaust gas of the gas turbine as a heat source, and the generated steam In a facility equipped with a steam turbine that generates electricity at a point , the water supply to the gas cooling facility is branched from the boiler and supplied to the gas cooling facility, and under normal operation or partial operation conditions, Including the boiler for performing transformer operation and the gas cooling facility for performing constant pressure operation, the gas cooling facility comprising pressure control means capable of performing constant pressure operation under operating conditions of either steady operation or partial operation. A combined gasification power generation facility characterized by
[0021]
( 2 ). In the above (1) Symbol placement gasification combined cycle plant, the outlet side of the steam generated in the gas cooling equipment comprises a pressure control valve, before pressure control Similar be is capable of controlling the system pressure of the equipment Gasification combined power generation facility characterized by
[0022]
In (1) and ( 2 ) above, “transforming operation” means changing the internal pressure of the steam drum in the steam system according to the operating conditions (partial load operation etc.) (by supplying steam to the steam turbine). The operation method, such as when the pressure in the system drops), and the "constant pressure operation" is an operation method that keeps the steam drum unit pressure of the steam system constant regardless of the operation conditions, and "pre-pressure control" Means to control the pressure control means (pressure control valve or the like) in front of the target pressure.
[0023]
[Action]
Since this invention is comprised as mentioned above, it has the following effect | action.
[0024]
(1). In the configuration of the above (1), it has a pipeline for supplying water to the gas cooling facility from the boiler and supplying the water to the gas cooling facility, and under normal operation or partial operation conditions, For example, a power generation facility includes a boiler that performs a transformer operation and a gas cooling facility that performs a constant pressure operation, and includes pressure control means that can operate the gas cooling facility under a constant pressure operation under either a steady operation or a partial operation condition. However, even during the transformation operation depending on the steam turbine inlet pressure, only the gas cooling facility can be maintained at a relatively high constant pressure by the pressure control means, and the induction of steaming can be suppressed.
[0025]
Therefore, since the feed water temperature of the gas cooling facility can be kept high, the plant efficiency is improved.
[0026]
In addition, in the type of power generation equipment in which the gas cooling equipment is housed in the pressurized container, the pressure and the feed water temperature are kept constant, so that the pressure between the pipe line penetrating the pressurized container and the pressurized container is maintained. There is no concern about the occurrence of defects such as cracks and leaks because there is no difference in strain or thermal strain due to fluctuations or thermal fluctuations.
[0028]
In particular, it is equipped with a pipeline that branches the water supply to the gas cooling facility from the boiler and supplies it to the gas cooling facility. As a result, it is possible to increase the temperature of the gas cooling facility water supply without causing steaming or other problems, thereby improving plant efficiency.
[0029]
( 2 ). In the configuration of ( 2 ), a pressure control valve is provided on the outlet side of the generated steam of the gas cooling facility in the configuration of (1 ) , and the system pressure of the facility can be controlled by pre-pressure control. The gas cooling facility can be controlled to a constant pressure, and the same effect as the above (1) can be obtained.
[0030]
【Example】
A gasification combined power generation facility according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. In addition, the same code | symbol is attached | subjected to the same structural member as a prior art example, and description is abbreviate | omitted unless it is required.
[0031]
FIG. 1 is a schematic system diagram of a combined gasification power generation facility according to the present embodiment, and FIG. 2 is a relationship diagram between plant loads and various temperatures in operation at a partial load according to the present embodiment.
[0032]
In FIG. 1, 11 is a pressure control valve interposed in the middle of the steam pipe 10b from the gas cooling facility 2 to the exhaust heat recovery boiler 6. Other configurations are the same as those of the conventional example.
[0033]
Next, the operation of the above configuration will be described.
[0034]
First, the general operation will be described. After the solid or liquid fuel 14 supplied to the gasification furnace 1 is cooled to a predetermined temperature by the gas cooling facility 2, unburned carbon content is removed by the char recovery facility 3. After the dust and harmful sulfur are removed by the gas refining equipment 4, the gas is burned by the combustor of the gas turbine 5 and the generator is driven. The high-temperature exhaust gas of the gas turbine 5 is guided to the exhaust heat recovery boiler 6, cooled by exchanging heat with the feed water fed by the boiler feed water pump 10, and discharged from the chimney 7 to the atmosphere. On the other hand, part of the water supplied by the boiler water pump 10 branches according to the opening of the water supply control valve 15 and is led to the gas cooling facility 2 to cool the product gas after gasification. That is, it absorbs heat and becomes high temperature to generate steam. The generated steam is returned to the exhaust heat recovery boiler 6 again, and after joining the main steam of the exhaust heat recovery boiler 6, the steam turbine 8 is driven.
[0035]
The exhaust heat recovery boiler 6 is operated at a pressure determined by accumulating the pressure loss of each part from the inlet pressure of the steam turbine 8. That is, the transformer is operated. The inlet pressure of the steam turbine 8 is uniquely determined by the steam flow rate, and the steam flow rate changes according to the amount of heat absorbed in the exhaust heat recovery boiler 6, so that the exhaust heat recovery boiler 6 performs a transformation operation. . On the other hand, a pressure control valve 11 is installed at the main steam outlet of the gas cooling facility 2, and the internal pressure of the steam system of the gas cooling facility 2 is controlled to be constant by pre-pressure control using this. That is, the gas cooling facility 2 is operated at a constant pressure.
[0036]
Next, each operation of voltage transformation, constant pressure, and pre-pressure control will be described.
[0037]
The feed water supplied to the exhaust heat recovery boiler 6 at a sufficiently high pressure by the boiler feed water pump 10 branches into the exhaust heat recovery boiler 6 and the gas cooling facility 2. In the transformer operation, the steam system of the exhaust heat recovery boiler 6 is operated at a pressure accumulated from the inlet pressure of the steam turbine 8. In the constant pressure operation, the operation is performed in a state where the steam system pressure of the exhaust heat recovery boiler 6 is kept constant by the pre-pressure control by adjusting a control valve (not shown) at the inlet of the steam turbine 8. Further, as described above, the steam system pressure in the facility is controlled to be constant by the pre-pressure control of the pressure control valve 11 provided at the outlet of the gas cooling facility 2.
[0038]
In the transformer operation, when the exhaust temperature of the gas turbine 5 decreases during a partial load operation or the like, the system pressure of the exhaust heat recovery boiler 6 naturally decreases.
[0039]
Incidentally, even in the constant pressure operation, depending on the operation conditions, there is a case where the operation is performed such that the control pressure is temporarily changed to protect the heat transfer surface and prevent the plant efficiency from being lowered.
[0040]
Here, by setting the gas cooling facility 2 to a constant pressure control, the temperature distribution of each part of the gas cooling facility 2 is kept constant even when the operating condition of the exhaust heat recovery boiler 6 changes, at the time of partial load, etc. The stress resulting from the difference in thermal elongation generated in the penetrating portion of the pressure vessel of the facility 2 can be reduced as much as possible. Further, since the internal pressure of the gas cooling facility 2 does not drop even during partial load, it is not necessary to consider measures for preventing steaming inside the economizer (not shown), for example. It is possible to set the feed water temperature and achieve higher plant performance. That is, by controlling the pressure control valve 11 and operating the gas cooling facility 2 at a constant pressure, such a special effect can be obtained.
[0041]
According to the diagrams showing the operating conditions at the partial load in the present embodiment in FIG. 2, the drum saturation temperature of the exhaust heat recovery boiler 6 decreases in conjunction with the gas turbine exhaust gas temperature decreasing at the partial load. ing. This is because the amount of steam generated in the exhaust heat recovery boiler 6 decreases due to the temperature drop of the exhaust gas from the gas turbine 5 and the inlet pressure of the steam turbine 8 decreases. It is because it went down. The drum saturation temperature in the gas cooling facility 2 is pre-pressure controlled by the pressure control valve 11 so that it does not become lower than a certain set value, so that a substantially constant saturation temperature is maintained even during partial load. Yes. It is assumed that the outlet pressure of the boiler feed water pump 10 is controlled or a constant discharge pressure is maintained in order to ensure the feed water pressure required by the gas cooling facility 2 even at the partial load.
[0042]
As described above, according to the present embodiment, since the pressure control valve 11 is provided in the steam pipe 10b on the outlet side of the generated steam of the gas cooling facility 2, a system that depends on the inlet pressure of the steam turbine 8 such as the exhaust heat recovery boiler 6 or the like. Even during the voltage transformation operation, by controlling the pressure control valve 11 to be pre-pressured, the gas cooling facility 2 can be operated at a constant pressure, so that there is an advantage that steaming is prevented.
[0043]
Moreover, since the gas cooling facility 2 can be maintained at a constant pressure and a higher pressure, there is an advantage that the plant efficiency is improved.
[0044]
In addition, since the pressure of the gas cooling facility 2 can be made constant, the supply water temperature depending on the saturation pressure can be kept constant, and in combination with the pressurized container and the water / steam system pipe passing through it. There is an advantage that no mechanical strain difference based on pressure fluctuation or thermal strain difference based on thermal fluctuation occurs between them, and therefore there is no risk of cracks or the like occurring at the site where the pipe passes through the pressurized container.
[0045]
【The invention's effect】
Since this invention is comprised as mentioned above, it has the following effect.
[0046]
That is, according to the present invention, since the gas cooling facility can be operated at a constant pressure by the pressure control means, the gas cooling facility feed water temperature can be set high, the high plant efficiency at the rated point, and the exhaust heat recovery according to the change in the gas turbine exhaust temperature High plant efficiency can be achieved even at points other than the rated point by boiler transformer operation. In addition, the constant temperature distribution of the gas cooling equipment maintains a constant temperature distribution under various operating conditions, and the water / steam system through-hole displacement breaks against a pressure vessel that is greatly affected by differences in thermal expansion. The risk of incurring etc. is completely eliminated.
[0047]
Further, since the gas cooling equipment can be kept at a high constant pressure, there is no danger of steaming.
[Brief description of the drawings]
FIG. 1 is a schematic system diagram of a combined gasification power generation facility according to an embodiment of the present invention;
FIG. 2 is a diagram showing the relationship between plant load and various temperatures in the partial load operation of the above embodiment,
FIG. 3 is a schematic system diagram of a conventional gasification combined power generation facility;
FIG. 4 is a relationship diagram between the feed water temperature of a conventional gas cooling facility and plant efficiency.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Gasification furnace 2 Gas cooling equipment 5 Gas turbine 6 Waste heat recovery boiler 8 Steam turbine 10 Boiler feed pump 11 Pressure control valve 14 Solid or liquid fuel 15 Feed water control valve 17 Evaporator

Claims (2)

A power generation facility that gasifies solid and liquid fuels and uses them as fuel for gas turbines, a gas cooling facility that cools the gas after gasification, a boiler that generates steam using the exhaust gas of the gas turbine as a heat source, and the generated steam In a facility equipped with a steam turbine that generates electricity at a point , the water supply to the gas cooling facility is branched from the boiler and supplied to the gas cooling facility, and under normal operation or partial operation conditions, Including the boiler for performing transformer operation and the gas cooling facility for performing constant pressure operation, the gas cooling facility comprising pressure control means capable of performing constant pressure operation under operating conditions of either steady operation or partial operation. A combined gasification power generation facility characterized by 2. The combined gasification power generation facility according to claim 1 , wherein a pressure control valve is provided on the outlet side of the generated steam of the gas cooling facility , and the system pressure of the facility can be controlled by pre-pressure control. gasification combined power generation facilities to be.

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