CN114776396B - Quick starting system and operation method for coal-fired power plant - Google Patents

Abstract

The invention discloses a quick start-up system and an operation method of a coal-fired power plant. The invention recovers part of the bypass steam during shutdown of the power plant and stores it in a heat storage system, thereby reducing the energy loss of the power plant; , by utilizing the recovered energy steam to raise the parameters of the steam generated by the boiler, the steam turbine can be started in advance, the invention can increase the start-up rate of the coal-fired unit, reduce the start-up time of the power plant, reduce the start-up energy consumption, and improve the flexibility of the coal-fired unit sex. The invention heats the main steam during the start-up process of the power plant, so that more main steam can be utilized, and the energy loss during the start-up process of the power plant is reduced.

Description

A quick start system and operation method of a coal-fired power plant

technical field

The invention relates to the technical field of coal-fired power plants, in particular to a quick-start system and an operation method of a coal-fired power plant.

Background technique

With the continuous development of renewable energy, the capacity of renewable energy power generation is also increasing. Due to the random and unpredictable characteristics of renewable energy, renewable power generation has a negative impact on the stability of the power grid. Since the current peak-shaving tasks of the power grid are mainly undertaken by coal-fired power plants, the peak-shaving tasks of power plants are also increasing. .

Power plant peak shaving is mainly achieved through rapid load changes and start-stop and other methods. Increasing the start-up speed of coal-fired power plants and reducing energy consumption during start-up is conducive to improving the peak-shaving performance of coal-fired power plants. Existing units use boilers and steam turbines to generate electricity Unit joint start-up technology, before the parameters of the steam produced by the boiler meet the requirements for starting the steam turbine, the steam turbine cannot start, resulting in increased start-up time, and unqualified steam will be sent to the condenser through a bypass, resulting in energy waste. Therefore, how to improve the start-up time of coal-fired power plants and reduce the start-up energy consumption is an urgent problem to be solved to improve the flexibility of coal-fired power plants.

Contents of the invention

The purpose of the present invention is to overcome the above disadvantages and provide a quick start-up system and operation method of a coal-fired power plant. During the start-up process, the heat stored in the molten salt heat storage system is used to increase the temperature of the main steam so that the steam turbine can be preheated in advance. Reduce the start-up time of the power plant, reduce energy consumption, and help improve the flexibility of the power plant.

In order to achieve the above purpose, a quick start system for a coal-fired power plant includes a boiler, the boiler is connected to a steam-molten salt heat exchanger, a steam turbine unit and a condenser, and a main The steam bypass inlet valve, the steam turbine inlet regulating valve is installed on the connecting pipeline between the boiler and the steam turbine unit, the steam turbine bypass valve is installed on the connecting pipeline between the boiler and the condenser, the main steam of the boiler is sent into the steam-molten salt heat exchange On the heat source side of the steam-molten salt heat exchanger, the outlet of the cold source side of the steam-molten salt heat exchanger is connected to the high-temperature heat storage tank and the low-temperature heat storage tank, and the outlets of the high-temperature heat storage tank and the low-temperature heat storage tank are connected to the cold source side of the steam-molten salt heat exchanger The inlet, the heat source side outlet of the steam-molten salt heat exchanger are connected to the condenser through pipelines, and the steam turbine unit is connected to the condenser.

A high temperature heat storage tank inlet regulating valve is installed on the connecting pipeline between the steam-molten salt heat exchanger and the high-temperature heat storage tank, and a high-temperature molten salt pump and high-temperature Heat storage tank outlet regulating valve.

The inlet regulating valve of the low-temperature heat storage tank is installed on the connecting pipeline between the steam-molten salt heat exchanger and the low-temperature heat storage tank, and the low-temperature molten salt pump and low-temperature Heat storage tank outlet regulating valve.

A main steam bypass outlet valve is set on the connecting pipeline between the steam-molten salt heat exchanger and the steam turbine unit, and a main steam bypass exhaust valve is set on the connecting pipeline between the steam-molten salt heat exchanger and the condenser.

A bypass desuperheater is installed on the connecting pipeline between the boiler and the condenser.

The condenser is connected to the condensate pump, the condensate pump is connected to the regenerative heater group, the regenerative heater group is connected to the feedwater pump, the feedwater pump is connected to the feedwater regulating valve, and the feedwater regulating valve is connected to the boiler. heater group.

The heat source side inlet of the steam-molten salt heat exchanger is connected to the adjacent unit, and the adjacent unit and the steam-molten salt heat exchanger are connected by an adjacent machine supplementary steam desuperheater and an adjacent machine supplementary steam regulating valve.

A method for operating a quick start system of a coal-fired power plant, comprising the following steps:

During the shutdown process of the unit, adjust the main steam bypass inlet valve so that the steam flow rate entering the steam turbine unit meets the load reduction rate requirements of the steam turbine unit, and the excess steam generated by the boiler enters the steam-molten salt heat exchange through the main steam bypass inlet valve control the molten salt flow into the steam-molten salt heat exchanger, so that the temperature of the molten salt entering the high-temperature heat storage tank is higher than the lower limit, and the low-temperature steam after heat exchange in the steam-molten salt heat exchanger flows into the condensing If the temperature of the steam entering the steam-molten salt heat exchanger is lower than the set value, or the quality of the molten salt in the high-temperature heat storage tank reaches the upper limit, the excess steam generated by the boiler will flow into the condenser.

During the start-up process of the unit, when the steam pressure generated by the boiler meets the start-up requirements of the steam turbine unit, but the steam temperature does not meet the start-up requirements of the steam turbine unit, and the molten salt reserve of the high-temperature heat storage tank is higher than 30%, the main steam bypass is turned on. The inlet valve of the main steam bypass and the outlet valve of the main steam bypass allow the steam generated by the boiler to enter the steam-molten salt heat exchanger. The molten salt in the high-temperature heat storage tank heats the steam generated by the boiler, so that the temperature of the heated steam meets the start-up requirements of the steam turbine unit, so that the steam turbine unit can be started in advance; Consumed steam flow, if the steam flow produced by the boiler is higher than the steam flow expected to be consumed by the turbine unit, the excess steam D _bp will flow into the condenser, if the steam flow produced by the boiler is lower than the expected steam flow consumed by the turbine unit, then Open the adjacent machine supplementary steam regulating valve to supplement the steam D _cs lacking in the boiler;

利用熔融盐物性计算得到熔融盐焓值，获得蒸汽的温度和压力后利用水蒸气物性计算得到蒸汽焓值，最后得到高温熔融盐泵流量的目标值

为：The flow of high-temperature molten salt entering the steam-molten salt heat exchanger needs to be calculated through energy conservation. First, the temperature T _ht of the high-temperature heat storage tank is obtained, and the temperature of the molten salt entering the low-temperature heat storage tank 18 is set

Calculate the enthalpy value of molten salt by using the physical properties of molten salt, obtain the temperature and pressure of steam, calculate the enthalpy value of steam by using the physical properties of water vapor, and finally obtain the target value of the flow rate of the high-temperature molten salt pump

for:

In the formula: D _bl is the steam flow rate at the boiler outlet, H _bl is the enthalpy value of the boiler outlet steam, D _cs is the admission steam flow rate of the adjacent unit, H _cs is the admission steam enthalpy value of the adjacent unit, D _bp is the steam turbine bypass valve D _tb is the steam flow rate entering the steam turbine unit, H _tb is the steam enthalpy value entering the steam turbine unit, which is obtained by checking the physical property parameters of the steam entering the steam turbine unit T _tb and steam pressure P _tb , and H _ht is the high temperature storage The outlet molten salt enthalpy of the hot tank, H _ct is the molten salt enthalpy entering the low-temperature heat storage tank;

后，通过PID控制调整高温熔融盐泵15的流量至目标值

以进入汽轮机的蒸汽温度T_tb和设定温度

的差值反馈至控制器，通过PID控制调节主蒸汽旁路进口阀门的流量D_mb，主蒸汽旁路进口阀门阀门信号的传递函数为：When obtaining the target value of the flow rate of the high temperature molten salt pump

Finally, adjust the flow rate of the high-temperature molten salt pump 15 to the target value through PID control

Take the steam temperature T _tb entering the steam turbine and the set temperature

The difference value of is fed back to the controller, and the flow rate D _mb of the inlet valve of the main steam bypass is adjusted through PID control. The transfer function of the valve signal of the inlet valve of the main steam bypass is:

In the formula, U(s) is the control signal of the main steam bypass inlet valve, and K _p , _Ti and T _d are the proportional, integral and differential gains of the controller, respectively.

After the steam pressure and temperature generated by the boiler meet the start-up requirements of the steam turbine unit, close the main steam bypass inlet valve and the main steam bypass outlet valve, open the steam turbine inlet steam regulating valve, and let the steam generated by the boiler pass through the steam turbine inlet steam regulating valve Enter the steam turbine unit.

During the shutdown process of the unit, the minimum temperature of the steam entering the steam-molten salt heat exchanger is 370°C.

Compared with the prior art, the present invention recovers part of the bypass steam during the shutdown process of the power plant and stores it in the heat storage system, which reduces the energy loss of the power plant; The parameters of the steam generated by the boiler enable the steam turbine to be started in advance, and the main steam that does not meet the start-up requirements of the steam turbine can be recycled. The flexibility of coal-fired units.

Further, the present invention can increase the parameters of the steam generated by the boiler through the steam of the adjacent unit, and reduce the bypass energy loss.

Description of drawings

Fig. 1 is a system diagram of the present invention;

Among them, 1. Boiler, 2. Main steam bypass inlet valve, 3. Turbine inlet steam regulating valve, 4. Steam turbine bypass valve, 5. Steam turbine unit, 6. Condenser, 7. Condensate water pump, 8. Regenerator Heater group, 9. Feedwater pump, 10. Feedwater regulating valve, 11. Steam-molten salt heat exchanger, 12. Main steam bypass outlet valve, 13. Main steam bypass exhaust valve, 14. High temperature heat storage tank , 15. High temperature molten salt pump, 16. High temperature heat storage tank outlet regulating valve, 17. Low temperature heat storage tank inlet regulating valve, 18. Low temperature heat storage tank, 19. Low temperature molten salt pump, 20. Low temperature heat storage tank outlet adjustment Valve, 21, high temperature heat storage tank inlet regulating valve, 22, bypass desuperheater, 23, adjacent machine supplementary steam regulating valve, 24, adjacent machine supplementary steam desuperheater, 25, adjacent unit.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

Referring to Fig. 1, a quick start-up system for a coal-fired power plant includes a boiler 1 connected to a steam-molten salt heat exchanger 11, a steam turbine unit 5 and a condenser 6, and the boiler 1 and the steam-molten salt heat exchanger 11 The main steam bypass inlet valve 2 is set on the connecting pipeline, the steam turbine inlet regulating valve 3 is set on the connecting pipeline between the boiler 1 and the steam turbine unit 5, and the steam turbine bypass valve 4 is set on the connecting pipeline between the boiler 1 and the condenser 6 , the main steam of the boiler 1 is sent to the heat source side of the steam-molten salt heat exchanger 11, and the outlet of the cold source side of the steam-molten salt heat exchanger 11 is connected to the high-temperature heat storage tank 14 and the low-temperature heat storage tank 18, and the high-temperature heat storage tank 14 and the outlet of the low-temperature heat storage tank 18 are connected to the cold source side inlet of the steam-molten salt heat exchanger 11, the heat source side outlet of the steam-molten salt heat exchanger 11 is connected to the condenser 6 through pipelines, and the steam turbine unit 5 is connected to the condensing steam Device 6. A bypass desuperheater 22 is arranged on the connecting pipeline between the boiler 1 and the condenser 6 .

A high-temperature heat storage tank inlet regulating valve 21 is installed on the connecting pipeline between the steam-molten salt heat exchanger 11 and the high-temperature heat storage tank 14, and a high-temperature heat storage tank 14 is installed on the connecting pipeline between the high-temperature heat storage tank 14 and the steam-molten salt heat exchanger 11. Molten salt pump 15 and high temperature heat storage tank outlet regulating valve 16. A low-temperature heat storage tank inlet regulating valve 17 is provided on the connecting pipeline between the steam-molten salt heat exchanger 11 and the low-temperature heat storage tank 18, and a low-temperature Molten salt pump 19 and low temperature heat storage tank outlet regulating valve 20. A main steam bypass outlet valve 12 is set on the connecting pipeline between the steam-molten salt heat exchanger 11 and the steam turbine unit 5, and a main steam bypass outlet valve 12 is set on the connecting pipeline between the steam-molten salt heat exchanger 11 and the condenser 6. Air valve 13.

Condenser 6 is connected to condensate pump 7, condensate pump 7 is connected to regenerative heater group 8, regenerative heater group 8 is connected to feed water pump 9, feed water pump 9 is connected to feed water regulating valve 10, feed water regulating valve 10 is connected to boiler 1, steam turbine unit The steam extraction outlet of 5 is connected to the regenerative heater group 8 through pipelines.

The heat source side inlet of the steam-molten salt heat exchanger 11 is connected to the adjacent unit 25, and the adjacent unit 25 is connected to the steam-molten salt heat exchanger 11 on the connecting pipeline with an adjacent machine supplementary steam desuperheater 24 and an adjacent machine supplementary steam regulator. valve 23.

The working medium of the high-temperature heat storage tank 14 and the low-temperature heat storage tank 18 is molten salt, the minimum temperature of the working medium of the high-temperature heat storage tank 14 is 370°C, and the minimum temperature of the working medium of the low-temperature heat storage tank 18 is 240°C.

A method for operating a quick start system of a coal-fired power plant, comprising the following steps:

The outlet of the boiler 1 is divided into three branches, the first branch is connected with the inlet of the main steam bypass inlet valve 2, the second branch is connected with the inlet of the steam turbine inlet regulating valve 3, and the third branch is connected with the inlet of the steam turbine inlet regulating valve 3. A branch is connected with the inlet of the steam turbine bypass valve 4; the outlet of the main steam bypass inlet valve 2 merges with the outlet of the adjacent steam supplementary steam regulating valve 23, and is connected with the steam inlet of the steam-molten salt heat exchanger 11 , the steam outlet of the steam-molten salt heat exchanger 11 is divided into two branches, which are respectively connected with the inlet of the main steam bypass outlet valve 12 and the inlet of the main steam bypass exhaust valve 13, and the steam turbine inlet steam regulating valve 3 The outlet of the main steam bypass outlet valve 12 merges and connects with the inlet of the steam turbine unit 5, the outlet of the steam turbine bypass valve 4 merges with the outlet of the main steam bypass exhaust valve 13, and passes through the bypass reducing The thermostat 22 is connected with the steam inlet of the condenser 6; the exhaust steam outlet of the steam turbine unit 5 is connected with the exhaust steam inlet of the condenser 6; The condensate outlet of the condenser 6 is connected to the feedwater inlet of the regenerative heater group 8 through the condensate pump 7, and the feedwater outlet of the regenerative heater group 8 is connected to the inlet of the boiler 1 through the feedwater regulating valve 10. Connection; the molten salt outlet of the steam-molten salt heat exchanger 11 is divided into two branches, the first branch is connected with the inlet of the high-temperature heat storage tank 14 through the inlet regulating valve 21 of the high-temperature heat storage tank, and the high-temperature heat storage tank The outlet of 14 is connected to the inlet of the outlet regulating valve 16 of the high-temperature heat storage tank through the high-temperature molten salt pump 15, and the other branch is connected to the inlet of the low-temperature heat storage tank 18 through the inlet regulating valve 17 of the low-temperature heat storage tank. The outlet of the hot tank 18 is connected to the outlet regulating valve 20 of the low-temperature heat storage tank through the low-temperature molten salt pump 19; The molten salt inlets of the molten salt heat exchanger 11 are connected.

In the operation method of the quick start system of a coal-fired power plant, the main steam bypass inlet valve 2, the steam turbine inlet steam regulating valve 3, the main steam bypass exhaust valve 13, and the low-temperature molten salt pump are opened during the shutdown process of the unit. 19. Low-temperature heat storage tank outlet regulating valve 20 and high-temperature heat storage tank inlet regulating valve 21, close steam turbine bypass valve 4, main steam bypass outlet valve 12, high-temperature molten salt pump 15, high-temperature heat storage tank outlet regulating valve 16, The inlet regulating valve 17 of the low-temperature heat storage tank and the regulating valve 23 of the adjacent steam supply adjust the main steam bypass inlet valve 2, so that the steam flow rate entering the steam turbine unit 5 meets the requirements of the load reduction rate of the steam turbine unit 5, and the excess steam generated by the boiler 1 Then enter the steam-molten salt heat exchanger 11 through the main steam bypass inlet valve 2, and control the molten salt flow rate entering the steam-molten salt heat exchanger 11 by adjusting the low-temperature molten salt pump 19, so that the steam entering the high-temperature heat storage tank 14 The temperature of the molten salt is higher than 360°C. After the steam exchanges heat in the steam-molten salt heat exchanger 11, it flows into the condenser 6 through the bypass exhaust valve 13 and the bypass desuperheater 22. After entering the steam-molten salt When the steam temperature of heat exchanger 11 is lower than 360°C, close main steam bypass inlet valve 2, low-temperature molten salt pump 19, low-temperature heat storage tank outlet regulating valve 20 and high-temperature heat storage tank inlet regulating valve 21, and open steam turbine bypass valve 4. Make the excess steam generated by the boiler 1 flow into the condenser 6 after passing through the main steam bypass exhaust valve 13 and the bypass desuperheater 22 .

During the start-up process of the unit, especially at the stage before the turbine unit rotates at 5 liters, if the steam pressure generated by boiler 1 reaches the set value, but the temperature does not reach the set value, open the main steam bypass inlet valve 2, the main steam bypass Road outlet valve 12, high temperature molten salt pump 15, high temperature heat storage tank outlet regulating valve 16 and low temperature heat storage tank inlet regulating valve 17, close main steam bypass exhaust valve 13, low temperature molten salt pump 19, low temperature heat storage tank outlet The regulating valve 20 and the high-temperature heat storage tank inlet regulating valve 21, the goal of the control at this stage is to increase the temperature of the steam generated by the boiler 1 by using the heat stored in the high-temperature heat storage tank 14, so that the temperature of the steam reaches the starting point of the steam turbine unit 5 Require.

In this process, compare the steam flow produced by boiler 1 with the steam flow expected to be consumed by steam turbine unit 5. If the steam flow produced by boiler 1 is higher than the expected steam flow consumed by steam turbine unit 5, the excess steam D _bp will flow into the condenser 6. If the steam flow rate generated by boiler 1 is lower than the steam flow rate expected to be consumed by steam turbine unit 5, then open the adjacent machine supplementary steam regulating valve 23 to supplement the steam D _cs that boiler 1 lacks;

利用熔融盐物性计算得到熔融盐焓值，获得蒸汽的温度和压力后利用水蒸气物性计算得到蒸汽焓值，最后得到高温熔融盐泵15流量的目标值

为：The flow of high-temperature molten salt entering the steam-molten salt heat exchanger 11 needs to be calculated through energy conservation. First, the temperature T _ht of the high-temperature heat storage tank 14 is obtained, and the temperature of the molten salt entering the low-temperature heat storage tank 18 is set.

Calculate the enthalpy value of the molten salt by using the physical properties of the molten salt, obtain the temperature and pressure of the steam, and then calculate the enthalpy value of the steam by using the physical properties of the water vapor, and finally obtain the target value of the flow rate of the high-temperature molten salt pump 15

for:

In the formula: D _bl is the steam flow rate at the outlet of boiler 1, H _bl is the enthalpy value of steam at the outlet of boiler 1, D _cs is the flow rate of steam admission of adjacent unit 25, H _cs is the enthalpy value of steam admission of adjacent unit 25, D _bp is The steam flow rate of the steam turbine bypass valve 4, D _tb is the steam flow rate entering the steam turbine unit 5, H _tb is the steam enthalpy value entering the steam turbine unit 5, and the physical properties are checked by the steam temperature T _tb and steam pressure P _tb entering the steam turbine unit 5 The parameters are obtained, H _ht is the outlet molten salt enthalpy value of the high-temperature heat storage tank 14, and H _ct is the molten salt enthalpy value entering the low-temperature heat storage tank 18;

后，通过PID控制调整高温熔融盐泵15的流量至目标值

以进入汽轮机的蒸汽温度T_tb和设定温度

的差值反馈至控制器，通过PID控制调节主蒸汽旁路进口阀门2的流量D_mb，主蒸汽旁路进口阀门2阀门信号的传递函数为：Obtaining the target value of the flow rate of the high temperature molten salt pump 15

Finally, adjust the flow rate of the high-temperature molten salt pump 15 to the target value through PID control

Take the steam temperature T _tb entering the steam turbine and the set temperature

The difference is fed back to the controller, and the flow D _mb of the main steam bypass inlet valve 2 is adjusted through PID control. The transfer function of the valve signal of the main steam bypass inlet valve 2 is:

In the formula, U(s) is the control signal of the main steam bypass inlet valve 2, and K _p , T _i and T _d are the proportional, integral and differential gains of the controller, respectively.

After the steam pressure and temperature generated by boiler 1 meet the start-up requirements of steam turbine unit 5, close the main steam bypass inlet valve 2 and the main steam bypass outlet valve 12, and open the steam turbine inlet steam regulating valve 3 to make the steam generated by boiler 1 It enters the steam turbine unit 5 through the steam turbine intake regulating valve 3 .

During the shutdown process of the unit, the minimum temperature of the steam entering the steam-molten salt heat exchanger 11 is 370°C.

By using the system and method, the bypass loss of the coal-fired power plant can be stored when the power plant is shut down, and during the start-up process of the power plant, the temperature of the main steam can be increased by using heat storage to heat the main steam, so that the main steam can meet the start-up requirements of the steam turbine as soon as possible. The start-up time of the power plant is reduced, and the unqualified main steam is heated and utilized, which reduces the energy loss during the start-up process, improves the start-up efficiency of the power plant, and increases the flexibility of the power plant.

Claims (10)

1. The utility model provides a quick start-up system of coal fired power plant, a serial communication port, including boiler (1), boiler (1) connect steam-molten salt heat exchanger (11), turbine unit (5) and condenser (6), be provided with main steam bypass import valve (2) on the connecting line of boiler (1) and steam-molten salt heat exchanger (11), be provided with turbine admission control valve (3) on the connecting line of boiler (1) and turbine unit (5), be provided with turbine bypass valve (4) on the connecting line of boiler (1) and condenser (6), the heat source side of steam-molten salt heat exchanger (11) is sent into to main steam of boiler (1), high temperature heat storage tank (14) and low temperature heat storage tank (18) are connected to steam-molten salt heat exchanger (11) cold source side export all, the heat source side export of steam-molten salt heat exchanger (11) is through pipe connection (6), turbine unit (5) are connected condenser (6).

2. The rapid starting system of the coal-fired power plant according to claim 1, wherein a high-temperature heat storage tank inlet regulating valve (21) is arranged on a connecting pipeline of the steam-molten salt heat exchanger (11) and the high-temperature heat storage tank (14), and a high-temperature molten salt pump (15) and a high-temperature heat storage tank outlet regulating valve (16) are arranged on a connecting pipeline of the high-temperature heat storage tank (14) and the steam-molten salt heat exchanger (11).

3. The rapid starting system of the coal-fired power plant according to claim 1, wherein a low-temperature heat storage tank inlet regulating valve (17) is arranged on a connecting pipeline of the steam-molten salt heat exchanger (11) and the low-temperature heat storage tank (18), and a low-temperature molten salt pump (19) and a low-temperature heat storage tank outlet regulating valve (20) are arranged on a connecting pipeline of the low-temperature heat storage tank (18) and the steam-molten salt heat exchanger (11).

4. The rapid starting system of a coal-fired power plant according to claim 1, characterized in that a main steam bypass outlet valve (12) is arranged on a connecting pipeline of the steam-molten salt heat exchanger (11) and the steam turbine unit (5), and a main steam bypass exhaust valve (13) is arranged on a connecting pipeline of the steam-molten salt heat exchanger (11) and the condenser (6).

5. The rapid start system of a coal-fired power plant according to claim 1, characterized in that a bypass attemperator (22) is arranged on the connection line of the boiler (1) and the condenser (6).

6. The rapid starting system of a coal-fired power plant according to claim 1, wherein the condenser (6) is connected with a condensate pump (7), the condensate pump (7) is connected with a regenerative heater group (8), the regenerative heater group (8) is connected with a water supply pump (9), the water supply pump (9) is connected with a water supply regulating valve (10), the water supply regulating valve (10) is connected with the boiler (1), and a steam extraction outlet of the steam turbine group (5) is connected with the regenerative heater group (8) through a pipeline.

7. The rapid starting system of a coal-fired power plant according to claim 1, wherein a heat source side inlet of the steam-molten salt heat exchanger (11) is connected with an adjacent unit (25), and an adjacent steam supplementing attemperator (24) and an adjacent steam supplementing adjusting valve (23) are arranged on a connecting pipeline of the adjacent unit (25) and the steam-molten salt heat exchanger (11).

8. A method of operating the rapid start system of a coal-fired power plant of claim 1, comprising the steps of:

in the shutdown process of the unit, a main steam bypass inlet valve (2) is regulated, so that the steam flow entering the steam turbine unit (5) reaches the requirement of the load reduction rate of the steam turbine unit (5), redundant steam generated by the boiler (1) enters a steam-molten salt heat exchanger (11) through the main steam bypass inlet valve (2), the flow of molten salt entering the steam-molten salt heat exchanger (11) is controlled, the temperature of the molten salt entering a high-temperature heat storage tank (14) is higher than a low limit value, and low-temperature steam after heat exchange in the steam-molten salt heat exchanger (11) is led into a condenser (6); if the temperature of the steam entering the steam-molten salt heat exchanger (11) is lower than a set value or the mass of the molten salt in the high-temperature heat storage tank (14) reaches a high limit value, the redundant steam generated by the boiler (1) is led to the condenser (6).

9. The operation method of the rapid starting system of the coal-fired power plant according to claim 8, wherein in the starting process of the unit, if the steam pressure generated by the boiler (1) reaches the starting requirement of the turbine unit (5), but the steam temperature does not reach the starting requirement of the turbine unit (5), and meanwhile, when the molten salt storage amount of the high-temperature heat storage tank (14) is higher than 30%, the steam generated by the boiler (1) enters the steam-molten salt heat exchanger (11), the molten salt stored in the high-temperature heat storage tank (14) is utilized to heat the steam generated by the boiler (1), and the heated steam temperature reaches the starting requirement of the turbine unit (5), so that the turbine unit (5) is started in advance;

an adjacent unit (25) is connected to a heat source side inlet of the steam-molten salt heat exchanger (11), and an adjacent machine steam supplementing desuperheater (24) and an adjacent machine steam supplementing regulating valve (23) are arranged on a connecting pipeline of the adjacent unit (25) and the steam-molten salt heat exchanger (11);

on-machineIn the group starting process, comparing the steam flow generated by the boiler (1) with the steam flow expected to be consumed by the steam turbine unit (5), and if the steam flow generated by the boiler (1) is higher than the steam flow expected to be consumed by the steam turbine unit (5), superfluous steam D _bp The steam flows are converged into a condenser (6), if the steam flow generated by the boiler (1) is lower than the steam flow expected to be consumed by a steam turbine unit (5), an adjacent steam supplementing regulating valve (23) is opened to supplement the lacking steam D of the boiler (1) _cs ；

The calculation method of the flow rate of the high-temperature molten salt entering the steam-molten salt heat exchanger (11) is as follows:

a high-temperature molten salt pump (15) and a high-temperature heat storage tank outlet regulating valve (16) are arranged on the connecting pipeline of the high-temperature heat storage tank (14) and the steam-molten salt heat exchanger (11), and the temperature T of the high-temperature heat storage tank (14) is obtained _ht And the temperature T of the molten salt entering the low-temperature heat storage tank (18) is set _ct Calculating molten salt enthalpy value by using molten salt physical property, obtaining steam temperature and steam pressure, and using steam

Physical property calculation to obtain vapor enthalpy value, and finally obtaining target value D of flow of high-temperature molten salt pump (15) _hm The method comprises the following steps:

D _hm ＝(D _tb H _tb -D _bl H _bl -D _cs H _cs +D _bp H _bp )/(H _ht -H _ct )

wherein: d (D) _bl For the steam flow of the outlet of the boiler (1), H _bl For the enthalpy value of the outlet steam of the boiler (1), D _cs Is the steam supplementing flow rate H of the adjacent unit (25) _cs Is the vapor supplementing enthalpy value D of the adjacent unit (25) _bp For the steam flow of the bypass valve (4) of the steam turbine, D _tb For steam flow into the turbine set (5), H _tb For entering the steam enthalpy value of the turbine set (5), the steam temperature T entering the turbine set (5) is used for _tb And steam pressure P _tb Obtaining physical parameters, H _ht Is the enthalpy value of the outlet molten salt of the high-temperature heat storage tank (14), H _ct Enthalpy value of molten salt for entering the low temperature heat storage tank (18);

in obtaining a target value of the flow rate of a high-temperature molten salt pump (15)

Thereafter, the flow rate of the high-temperature molten salt pump 15 is adjusted to the target value +.>

To enter steam temperature T of steam turbine _tb And set temperature +.>

Is fed back to the controller, and the flow D of the main steam bypass inlet valve (2) is regulated by PID control _mb The transfer function of the valve signal of the main steam bypass inlet valve (2) is as follows:

wherein U(s) is the control signal of the main steam bypass inlet valve (2), K _p 、T _i And T _d Proportional, integral and differential gains of the controller, respectively;

after the pressure and the temperature of the steam generated by the boiler (1) reach the starting requirements of the turbine unit (5), the steam generated by the boiler (1) enters the turbine unit (5).

10. The method of operation of a rapid start system for a coal fired power plant according to claim 8, wherein during a unit shutdown, the minimum temperature of steam entering the steam-molten salt heat exchanger (11) is 370 ℃.

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