JP2511007B2 - Auxiliary steam device - Google Patents

Description

Description: [Industrial application] The present invention relates to an auxiliary steam apparatus optimal for improving the reliability and operability of an auxiliary steam facility of a combined plant having a plurality of units.

[Conventional technology]

Auxiliary steam equipment in a power plant supplies auxiliary steam as steam for steam turbine gland seal, steam for boiler equipment, steam for deaerator seal, etc. depending on plant operation.

As a known example related to this type of apparatus, there is, for example, JP-A-60-23707.

As a known example related to this type of apparatus, there is, for example, JP-A-60-23707.

FIG. 2 shows a conventional example of auxiliary steam equipment for a power generation plant having a plurality of combined plants. Book second
The figure shows one of a plurality of combined plants 1.

Auxiliary steam equipment 2 of a plurality of combined plants 1, which are constituent units of a power generation plant, are connected in parallel to auxiliary steam equipment 3 common to the power generation plant by auxiliary steam communication equipment 4, and auxiliary steam is supplied to common equipment 9 of the power generation plant. It is possible to supply.

The auxiliary steam facility 2 of the combined plant 1 reduces the pressure of the steam generated in the boiler 5 for recovering exhaust heat by the auxiliary steam pressure control valve 6 and supplies the steam to the auxiliary steam required facility.

Here, the auxiliary steam supply facility refers to the steam facility 7 for steam turbine gland seal of the combined plant 1, the steam facility 8 for degassing the condenser, and the common facility 9 of the power generation plant.

A conventional power generation plant has an auxiliary steam facility configuration as shown in FIG. 3, and is generally equipped with an auxiliary boiler facility 10 (see FIG. 2). Further, as the operation of the auxiliary steam equipment of the power generation plant, at the time of starting the plant, the auxiliary steam from the auxiliary bailer equipment 10 is supplied to the steam equipment for steam turbine gland seal 7, and after the combined plant 1 shifts to the load operation state, the auxiliary steam is supplied. Switch the source from the auxiliary boiler equipment 10 to the auxiliary steam equipment 2 of the combined plant 1,
It is operated to supply auxiliary steam to the common equipment 9 of the power generation plant. In this case, as the capacity of the auxiliary steam pressure control valve 6, the required steam amount of the common equipment 9 of the power generation plant may be taken into consideration. Further, the pressure set value of the auxiliary steam pressure control valve 6 is set to a constant value in order to keep the auxiliary steam pressure of the common auxiliary steam facility 3 of the power plant constant.

On the other hand, in a power plant equipped with a plurality of combined plants as shown in FIG. 2, daily start / stop operation is an essential condition due to the "ease of starting and stopping" and high efficiency, which are features of combined plants. . In this case, using an auxiliary boiler facility (10 in Fig. 2) as an auxiliary steam source at the time of plant startup, as in a conventional power plant, is high in price, low in efficiency, and operability of heavy oil as an auxiliary boiler fuel. A facility that takes out auxiliary steam from a combined plant under load operation and supplies it to the combined plant that is scheduled to start up, that is, a common auxiliary steam facility configuration that connects auxiliary steam facilities of multiple combined plants in parallel. Has been needed.

[Problems to be solved by the invention]

In the case of the above-described auxiliary steam equipment configuration, the auxiliary steam pressure control valve 6 of each combined plant 1 is arranged in parallel with the auxiliary steam equipment 3 common to the power generation plant, and the pressure set value of the auxiliary steam pressure control valve 6 is set. Since the auxiliary steam pressure control is performed with a constant value, the auxiliary steam pressure control valves 6 may hunt depending on the plant operating conditions, resulting in unstable auxiliary steam pressure control.

FIG. 3 shows a prior art example relating to the pressure setting of the auxiliary steam pressure control valve 6.

Further, FIG. 4 shows an example in which the auxiliary steam pressure control causes hunting when the pressure set value of the auxiliary steam pressure control valve 6 is set to a constant value.

FIG. 4 is a diagram assuming a state in which the combined plant 1 shown in FIG.
The valve and the valve correspond to the auxiliary steam pressure control valve 6 of the first and third units, respectively, and the valve corresponds to the steam turbine gland seal steam pressure control valve 11 of the second unit. Here, the plant operating condition is assumed to be one starting during two operating. That is,
The valve is opened to supply the steam turbine gland seal steam when the plant is started (point), and at this time, the auxiliary steam pressure temporarily drops (point). Along with this, the valve starts to open (), but the required amount of auxiliary steam when the plant is started is smaller than the capacity of the auxiliary steam pressure control valve, and the amount of auxiliary steam above the required amount from the auxiliary steam pressure control valve 6 is small. It will flow out, and as a result the auxiliary steam pressure will rise () and the valve will close (). By repeating such a state, the auxiliary steam pressure control causes hunting. Although FIG. 4 explained the three-machine configuration for convenience, in an actual power plant, a single-unit capacity of 100-150 MW is used.
It is planned to be a power plant with a configuration of up to 7 machines and a total power output of 600 to 1000 MW, and hunting is more likely to occur as the number of constituent units of the combined plant increases.

Regarding the capacity of the auxiliary steam pressure control valve 6, in addition to the required steam amount of the common equipment 9 of the power generation plant, the required steam amount at the time of starting a plurality of starting plants (steam turbine grandsail steam, condenser deaeration steam) The added capacity is required.

On the other hand, since the pressure set value of the auxiliary steam pressure control valve 6 is constant and the operation of the power generation plant is highly efficient, the operating machines are operated under a uniform load (same load), so that the auxiliary steam pressure per machine is increased. The control flow rate of the control valve is a value obtained by dividing the required amount of auxiliary steam by the number of operating units, and the auxiliary steam pressure control valve may be used in a small opening range.

As a result, the erosion of the adjusting valve may occur due to the use of the small opening of the adjusting valve. In addition, as shown in FIG. 5, the flow rate change rate is large (that is, the pressure change is large) near the initial valve opening degree, which may cause the auxiliary steam safety valve blowout. For these reasons, the conventional technology may impair the reliability and operability of the auxiliary steam facility and the power plant.

An object of the present invention is to hunt the auxiliary steam pressure control valve,
It is an object of the present invention to provide an auxiliary steam facility capable of preventing the generation of erosion and auxiliary steam safety valve blowout.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention provides a power plant with an auxiliary byer facility and at least two combined plants, and each of the two combined plants is supplied from a boiler for exhaust heat recovery. It has an auxiliary steam pressure control valve for reducing the pressure of steam, and is equipped with steam equipment for steam turbine gland seals and auxiliary steam equipment that can supply auxiliary steam to the common equipment of the power plant. When the combined plant is connected to the steam equipment in parallel and the auxiliary steam from the auxiliary boiler equipment is supplied to the steam turbine gland seal steam equipment and the combined plant operates under load, the auxiliary steam equipment supplies auxiliary steam to the common equipment of the power plant. The auxiliary steam pressure control valve can adjust the set pressure arbitrarily. In addition, the auxiliary steam system is set to different pressures in the range between the required minimum pressure of the auxiliary steam system and the maximum operating pressure of the auxiliary steam system, and the steam equipment for the steam turbine gland seal is operated under load by the supply of auxiliary steam from the auxiliary boiler equipment. In this case, the auxiliary steam pressure control valve having the larger set pressure is configured to supply the auxiliary steam to the common equipment of the power generation plant.

[Action]

FIG. 6 is a table showing the pressure control valve pressure set values of the n-type combined plant shown for explaining the operation when the present invention is applied, and corresponds to FIG. 3 in the above-mentioned conventional example. It is a figure.

Here, the auxiliary steam pressure set value is an appropriate value for the auxiliary steam system minimum required pressure P _L (pressure determined based on the auxiliary steam required facility required pressure) and the auxiliary steam system maximum operating pressure P _H (operating pressure of the auxiliary steam facility). It should be set to a value in the range sandwiched by the pressure with sufficient margin).

As the set pressure difference between each auxiliary steam pressure control valve, it is important to have a set pressure difference that always supplies auxiliary steam from the auxiliary steam pressure control valve of one combined plant according to the plant operating conditions. Is.

FIG. 7 shows the pressure control characteristics of the auxiliary steam facility when the variable pressure set value as shown in FIG. 6 is used.

Here, the valves are the same as those in FIG. 4 described above. That is, the valve is opened to supply the steam turbine gland seal steam at the time of start-up, and at this time, the pressure of the auxiliary steam facility temporarily drops. Along with this, the valve tries to start the opening operation, but at this time, since the pressure setting value of the valve is higher than the pressure setting value of the valve, the valve is opened first and the auxiliary steam supply is started. Therefore, the valve remains closed. In this way, since the steam turbine gland seal steam of the Unit 2 is all supplied from the valve of the Unit 3, hunting of the pressure control valve does not occur.

Considering the flow control range of the auxiliary steam pressure control valve, the required auxiliary steam is as follows when a 1000 MW power plant with seven combined plants is assumed.

(I) Steam turbine gland seal steam 1T / H / 1 unit (used at startup) (ii) Condenser degassing steam 5T / H / 1 unit (used at startup) (iii) Power plant common equipment 8T / H / Plant (during plant operation) Therefore, the auxiliary steam pressure control valve capacity will be 44T / H.

(1 + 5) × (7-1) + 8 = 44T / H / 1 machine On the other hand, the flow control range of the auxiliary steam pressure control valve is the pressure set value of the pressure control valve under the operating condition that 1 machine is started during operation of 6 machines. The lower limit of the control range differs between the constant setting and the variable setting as follows.

When the pressure setting value is constant (1 + 5) / 44 × 1 / (7-1) × 100 = 2.3% When the pressure setting value is variable (1 + 5) /44×100=13.6% Generally, the controllable range of the control valve is 10 to It is set to 90%, and when the pressure set value of the auxiliary steam pressure control valve is constant, it falls below the controllable range of the pressure control valve, but if it is a variable setting,
It can be within the controllable range.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.
This will be described with reference to FIG.

FIG. 1 shows an example of an auxiliary steam apparatus for a power plant in which a plurality of combined plants are installed.

The auxiliary steam equipment 2 of each combined plant 1 is connected in parallel to the auxiliary steam equipment 3 common to the power generation plant by the auxiliary steam communication equipment 4 so that the auxiliary steam can be supplied to the common equipment 9 of the power generation plant.

The auxiliary steam facility 2 of the combined plant 1 reduces the pressure of the steam generated in the boiler 5 for recovering exhaust heat by the auxiliary steam pressure control valve 6 and supplies the steam to the auxiliary steam required facility.

An auxiliary steam pressure control valve 14 is installed in the auxiliary steam facility 2 as required, and an auxiliary steam safety valve 12 is installed to prevent an increase in the auxiliary steam system pressure when the auxiliary steam pressure control valve fails.

On the other hand, as auxiliary steam required equipment, in the combined palant 1, a steam turbine gland seal steam supply equipment 7 for supplying the steam turbine gland steam to the steam turbine 16 and a start-up condenser 17 are used to promote degassing performance. There is a steam facility 8 for deaerating a water vessel.

Here, the steam facility for steam turbine gland seal 7 includes a desuperheater for the gland steam for adjusting the gland steam temperature.
Also, a steam pressure control valve 11 for a steam turbine gland seal is installed to adjust the gland steam pressure.

The condenser degassing steam facility 8 is equipped with a degassing steam desuperheater 19 for adjusting the degassing steam temperature, and is also equipped with a degassing steam stop valve 18 for controlling the degassing steam supply. It

The auxiliary steam pressure control valve 6 detects the auxiliary steam pressure by the auxiliary steam pressure detector 20, and detects this auxiliary steam pressure setter.
The pressure setting value set in 13 is compared, and the auxiliary steam pressure of the auxiliary steam facility 2 or the auxiliary steam facility common to the power plant is controlled to be a constant value.

In this embodiment, the pressure set value of the auxiliary steam pressure control valve pressure setter 13 is variably set as shown in FIG.

In Fig. 6, a convex type example is shown in which the auxiliary steam pressure control valve pressure set value is set higher for the intermediate unit between Unit 1 and Unit n. Therefore, it may be a concave type setting for increasing the pressure set value of both end machines, or an inclined type setting for sequentially setting the set value higher (or lower) from No. 1 machine to n machine. Use different values.

Due to the effect of the variable setting as shown in FIG. 6, hunting between the auxiliary steam pressure adjusting valves can be prevented as described with reference to FIG. 7, and the controllability of the auxiliary steam pressure adjusting valve 6 is improved. However, the erosion of the valve 6 and the blowout of the auxiliary steam safety valve 12 can be prevented.

In the auxiliary steam facility in the embodiment shown in FIG. 1, the generated steam of the boiler 5 for recovering exhaust heat is decompressed as the auxiliary steam to supply the auxiliary steam. Here, the auxiliary steam extraction amount and the gas turbine load are There is a limit between them as shown in FIG.

That is, the auxiliary steam needs to be supplied while satisfying the required pressure and the required temperature of the auxiliary steam required equipment, but the exhaust heat recovery boiler performance depends on the amount of extracted steam from the exhaust heat recovery boiler 5. It changes, and conditions that do not satisfy the required auxiliary steam conditions and flow rate restriction of the boiler for exhaust heat recovery occur.

Therefore, since the required amount of auxiliary steam is known, calculate the gas turbine load that can extract auxiliary steam from the maximum required amount of auxiliary steam, and set the gas turbine extractable load or the gas turbine extractable load equivalent signal value as the specified value. If an interlock for forcibly closing the auxiliary steam pressure control valve 6 is provided by comparing the actual gas turbine load or the signal value equivalent to the gas turbine load, it is possible to always supply the auxiliary steam that satisfies the auxiliary steam condition, The steam flow rate limitation of the boiler 5 for recovering exhaust heat is satisfied, and the generation of erosion can be prevented.

FIG. 9 shows an example of interlock of the auxiliary steam pressure control valve 6. FIG. 10 shows an example of an interlock when the auxiliary steam pressure adjusting valve front valve 14 is used instead of the auxiliary steam pressure adjusting valve 6.

In the interlock shown in FIGS. 9 and 10,
In both cases, the auxiliary steam supply is cut off when the gas turbine load is below the specified value, but it is necessary to secure the steam turbine ground steam when the station is completely stopped. Therefore, the auxiliary steam pressure control valve 6 or the auxiliary steam pressure is required only when the station is completely stopped. An interlock for releasing the forced closing of the control valve front valve 14 is additionally shown.

FIG. 11 shows another embodiment of the present invention. This example is
Although it is the same equipment as the auxiliary steam equipment in FIG. 1, a calculation device 21 of the pressure set value of the auxiliary steam pressure control valve 6 is installed.

The contents of the pressure set value calculation device 21 are shown in FIG. In the interlock of this example, the magnitudes of the gas turbine load or the gas turbine load-equivalent signal are compared, and the pressure set values are assigned in order of magnitude according to the magnitude order.

This is because, as shown in FIG. 8, more auxiliary steam can be supplied from an operating machine with a large gas turbine load.

〔The invention's effect〕

As described above, the present invention is configured so that each of the auxiliary steam pressure control valves of the combined plant can arbitrarily adjust the set pressure, and the auxiliary steam system minimum required pressure and auxiliary steam system maximum operating pressure When the steam turbine gland seal steam facility is operated under load due to the supply of auxiliary steam from the auxiliary boiler facility, the auxiliary steam is adjusted by the auxiliary steam pressure control valve with the larger set pressure. Since it is configured to supply to the common equipment, the auxiliary steam pressure control valve with the lower pressure remains closed and the auxiliary steam pressure control valve with the higher pressure supplies steam, resulting in the auxiliary pressure control. Excellent practical effect of preventing valve hunting, preventing erosion, and preventing auxiliary steam safety valve from blowing out Exert, operability of the combined plant improvement, improved reliability, and is a great place to contribute to the improvement of durability.

[Brief description of drawings]

FIG. 1 is a system diagram showing a configuration of an auxiliary steam device in one embodiment of the present invention, FIG. 2 is a system diagram showing a configuration of a conventional auxiliary steam device, and FIG. 3 is a conventional auxiliary steam pressure control valve. FIG. 4 is a diagram showing a pressure set value, FIG. 4 is a diagram showing a conventional auxiliary steam pressure control characteristic, FIG. 5 is a diagram showing a valve opening-flow rate characteristic of a control valve, and FIG. 6 is an embodiment of the present invention. Showing the auxiliary steam pressure control valve pressure setting value, FIG. 7 shows the auxiliary steam pressure control characteristic of one embodiment of the present invention, and FIG. 8 shows the relationship between the gas turbine load and the auxiliary steam extraction possible amount. FIG. 9 is a diagram showing the interlock of the auxiliary steam pressure control valve of one embodiment of the present invention, and FIG. 10 is a diagram showing the interlock of the auxiliary steam pressure control valve front valve of the one embodiment of the present invention. FIG. 11 is a system diagram showing an auxiliary steaming device according to another embodiment of the present invention, and FIG. 12 is an auxiliary device. It is a block diagram showing the contents of the gas-pressure regulating valve pressure setting calculator. 1 ... Combined plant, 2 ... Auxiliary steam facility, 3
...... Auxiliary steam equipment common to power plants, 4 ... Auxiliary steam connection equipment, 5 ... Boiler for exhaust heat recovery, 6 ... Auxiliary steam pressure control valve, 7 ... Steam equipment for steam turbine gland seal, 8 ... … Condenser degassing steam equipment, 9 …… Common equipment for power plants, 10 …… Auxiliary boiler equipment, 11 …… Steam turbine gland steam pressure control valve, 12 …… Auxiliary steam safety valve,
13 …… Auxiliary steam pressure control valve pressure setter, 14 …… Auxiliary steam pressure control valve front valve, 15 …… Grand steam desuperheater, 16 ……
Steam turbine, 17 …… condenser, 18 …… steam stop valve for desorption,
19 …… Desteamer steam desuperheater, 20 …… Auxiliary steam pressure detector,
21 …… Pressure set value calculator.

Claims (1)

(57) [Claims] 1. A power generation plant is equipped with an auxiliary boiler facility and at least two combined plants, and each of the two combined plants reduces the pressure of steam supplied from a boiler for exhaust heat recovery. Auxiliary steam pressure control valve and steam equipment for steam turbine gland seal, auxiliary steam equipment that can supply auxiliary steam to common equipment of power generation plant, and each auxiliary steam equipment in parallel with common auxiliary steam equipment Auxiliary steam that is connected and supplies auxiliary steam from the auxiliary boiler equipment to the steam turbine gland seal steam equipment to supply auxiliary steam to the common equipment of the power generation plant when the combined plant operates under load. In the apparatus, each of the auxiliary steam pressure control valves may be configured so that each set pressure can be adjusted arbitrarily. When the steam equipment for the steam turbine gland seal is operated under load by the supply of auxiliary steam from the auxiliary boiler equipment, the set pressure is set to different pressures in the range between the minimum required pressure of the auxiliary steam system and the maximum operating pressure of the auxiliary steam system. An auxiliary steam device characterized in that the auxiliary steam pressure control valve of the larger one is configured to supply the auxiliary steam to the common equipment of the power plant.