Molten Salt Steam Generation System Coupled with Coal-Fired Unit, Control Method and Control Device

Abstract

The present invention discloses a molten salt steam generation system coupled with a coal-fired unit, a control method, and a control device. The control method includes the following steps: obtaining two different opening command functions, where the two opening command functions are broken line functions regarding the change of the comprehensive valve position command at the outlet of the feed water pump; obtaining the comprehensive valve position command at the outlet of the feed water pump in real time, obtaining the first opening through the first opening command function f1(x), and obtaining the second opening through the second opening command function f2(x); controlling the opening of the main path regulating valve to be the first opening, controlling the opening of the bypass regulating valve to be the second opening, and adjusting the feed water flow rate so that the measured value of the evaporator water level is equal to the set value of the evaporator water level. According to the present invention, by obtaining the magnitude of the comprehensive valve position command at the outlet of the feed water pump, the opening commands of the main path and bypass regulating valves are respectively obtained through two opening command functions to adjust the feed water flow rate, weakening the non-linearity of a single valve, facilitating the control of the header flow rate, realizing the full-condition control of the evaporator water level, and ensuring the safe operation of the unit.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired units, and particularly to a molten salt steam generation system coupled with a coal-fired unit, a control method, and a control device therefor. Background Art

[0002] With the increasing proportion of new energy installed capacity in the power grid, continuous efforts and research are required to promote the flexibility of the power system and the accommodation of new energy. A flexible and resilient power system needs high-flexibility power sources as support. For a long time, thermal power generation has been the main force for ensuring power supply and peak regulation and frequency modulation, and will still be the dominant power source in a long time to come. Facing the goal of large-scale new energy accommodation, how to tap the flexible operation potential of thermal power units and improve the grid friendliness of the power output on the source side is one of the key issues that need to be studied and solved in the new energy power system.

[0003] As an energy storage medium, molten salt is widely used in the field of solar thermal power generation, and has the characteristics of high energy storage efficiency and good economy. Adding a molten salt steam generation system to a traditional coal-fired unit is a new idea to improve the load change rate of the unit, that is, to store part of the heat of the boiler by molten salt and release it when the unit needs to quickly increase the load. The energy time control of the unit is completed through the storage / heat release process of the molten salt system. In the heat release stage, the molten salt heats the feed water to generate steam, which is combined with the steam generated by the boiler and sent to the steam turbine to do work, greatly improving the load increase rate of the unit.

[0004] In order to ensure the stable operation of the molten salt steam generation system, a prior art full-load molten salt steam generation system and its control method disclose a molten salt steam generation system and a control method applicable to the full-load operation of a solar thermal power station. The system decouples the heat exchange process in the superheater, evaporator, and preheater, and adjusts the opening of the valve to control the molten salt flow through the superheater, evaporator, and preheater respectively when the load changes, reducing the solidification risk of the molten salt.

[0005] However, the prior art only regulates the molten salt flow rate and lacks attention to the feed water flow rate and steam flow rate, which may lead to the imbalance of feed water and steam, affecting the safe operation of the unit. Summary of the Invention

[0006] The purpose of the present invention is to provide a molten salt steam generation system coupled with a coal-fired unit, a control method, and a control device therefor to ensure the safe operation of the unit.

[0007] To solve the above technical problems, the present invention provides a control method for a molten salt steam generation system coupled with a coal-fired unit, including the following steps:

[0008] Obtain the first opening command function f 1 (x) and the second opening command function f 2(x), the first opening command function f 1 (x) and the second opening command function f 2 (x) are both piecewise linear functions with respect to the change of the comprehensive valve position command at the outlet of the feed water pump, and f 1 (x) ≠ f 2 (x);

[0009] Obtain the comprehensive valve position command at the outlet of the feed water pump in real time, and obtain the first opening through the first opening command function f 1 (x), and obtain the second opening through the second opening command function f 2 (x);

[0010] Control the opening of the main path regulating valve in the molten salt steam generation system to be the first opening, and control the opening of the bypass regulating valve in the molten salt steam generation system to be the second opening, so as to adjust the feed water flow rate of the molten salt steam generation system, so that the measured value of the evaporator water level in the molten salt steam generation system is equal to the set value of the evaporator water level;

[0011] The main path regulating valve and the bypass regulating valve are arranged in parallel between the feed water outlet of the feed water pump and the feed water inlet of the evaporator in the molten salt steam generation system.

[0012] The control method of the molten salt steam generation system coupled with a coal-fired unit, according to the magnitude of the comprehensive valve position command obtained at the outlet of the feed water pump, passes through two first opening command functions f with different forms but complementary characteristics 1 (x) and the second opening command function f 2 (x), respectively obtain the opening commands of the main path regulating valve and the bypass regulating valve, and adjust the feed water flow rate of the molten salt steam generation system, which can not only weaken the nonlinearity of a single valve and is beneficial to the control of the main pipe flow rate, but also avoid the complex main / bypass switching logic, so that the comprehensive valve position command at the outlet of the feed water pump and the actual feed water flow rate show a good linear relationship, realizing the full-condition automatic control of the evaporator water level in the large-flow heat release mode and the small-flow heat tracing mode of the molten salt steam generation system.

[0013] Optionally, obtaining the comprehensive valve position command at the outlet of the feed water pump in real time specifically includes the following steps:

[0014] Monitor the evaporator water level and feed water flow rate of the molten salt steam generation system in real time, obtain the measured value of the evaporator water level and the measured value of the feed water flow rate, generate a feed water flow rate set value according to the deviation between the measured value of the evaporator water level and the set value of the evaporator water level, and generate a first comprehensive valve position command at the outlet of the feed water pump according to the deviation between the measured value of the feed water flow rate and the feed water flow rate set value;

[0015] Monitor the steam flow rate of the molten salt steam generation system in real time, obtain the measured value of the steam flow rate, and generate a second comprehensive valve position command for the outlet of the feed water pump according to the measured value of the steam flow rate;

[0016] Monitor the working state of the coupled coal-fired unit in real time, obtain the actual power of the unit, and receive the AGC load command. Calculate the deviation between the AGC load command and the actual power of the unit. When the deviation between the AGC load command and the actual power of the unit is not less than the preset deviation, generate a third comprehensive valve position command for the outlet of the feed water pump according to the deviation between the AGC load command and the actual power;

[0017] Superimpose the first comprehensive valve position command, the second comprehensive valve position command, and the third comprehensive valve position command to obtain a comprehensive valve position command for the outlet of the feed water pump.

[0018] Optionally, the following steps are further included:

[0019] When any one of the first signal and the second signal is valid, delay for the first preset time, generate a feed water flow rate locking increase signal, and control the opening degrees of the main path regulating valve and the bypass regulating valve not to increase;

[0020] When the measured value of the deaerator water level is lower than the low-1 value of the deaerator water level, the first signal is valid;

[0021] When the measured value of the evaporator water level is higher than the high-1 value of the evaporator water level and the measured value of the deaerator water level is not higher than the high-1 value of the deaerator water level, the second signal is valid.

[0022] Optionally, the following steps are further included:

[0023] When any one of the third signal and the fourth signal is valid, delay for the second preset time, generate a feed water flow rate locking decrease signal, and control the opening degrees of the main path regulating valve and the bypass regulating valve not to decrease;

[0024] When the measured value of the deaerator water level is higher than the high-1 value of the deaerator water level, the third signal is valid;

[0025] When the measured value of the evaporator water level is lower than the low-1 value of the evaporator water level and the measured value of the deaerator water level is not lower than the low-1 value of the deaerator water level, the fourth signal is valid.

[0026] Optionally, the following steps are further included:

[0027] Obtain the outlet pressure and the inlet pressure of the feed water pump, generate a feed water pump frequency command on the condition that the deviation between the outlet pressure and the inlet pressure of the feed water pump deviates from the preset deviation value, and adjust the feed water pump frequency according to the feed water pump frequency command so that the deviation between the outlet pressure and the inlet pressure of the feed water pump is maintained at the preset deviation value.

[0028] Optionally, when the deviation between the outlet pressure and the inlet pressure of the feed water pump is lower than the preset deviation value, increase the frequency of the feed water pump; when the deviation between the outlet pressure and the inlet pressure of the feed water pump is higher than the preset deviation value, decrease the frequency of the feed water pump.

[0029] The present invention provides a control device for a molten salt steam generation system coupled with a coal-fired unit, which is applicable to the control method of the molten salt steam generation system coupled with the foregoing coal-fired unit, and includes a molten salt evaporator water level control device. The molten salt evaporator water level control device includes a storage unit, a first calculation unit, and a first control unit that are communicatively connected. Among them:

[0030] The storage unit stores a first opening command function f 1 (x) and a second opening command function f 2 (x). Both the first opening command function f 1 (x) and the second opening command function f 2 (x) are piecewise linear functions regarding the change of the comprehensive valve position command at the outlet of the feed water pump, and f 1 (x) ≠ f 2 (x);

[0031] The first calculation unit can calculate and obtain the comprehensive valve position command at the outlet of the feed water pump in real time, and obtain a first opening through the first opening command function f 1 (x), and obtain a second opening through the second opening command function f 2 (x);

[0032] The first control unit can control the opening of the main path regulating valve in the molten salt steam generation system to be the first opening, and control the opening of the bypass regulating valve in the molten salt steam generation system to be the second opening, so as to adjust the feed water flow rate in the molten salt steam generation system, so that the measured value of the evaporator water level in the molten salt steam generation system is equal to the set value of the evaporator water level.

[0033] Optionally, it further includes:

[0034] An RTU system, the RTU system is communicatively connected to the first calculation unit, and the RTU system can obtain the AGC load command in real time and transmit the AGC load command to the calculation unit;

[0035] A DCS system, the DCS system is communicatively connected to the first calculation unit, and the RTU system can obtain the actual power of the unit in real time and transmit the actual power of the unit to the calculation unit;

[0036] The first water level monitoring device, which is communicatively connected to the first calculation unit. The first water level monitoring device can obtain the measured value of the evaporator water level of the molten salt steam generation system in real time and transmit the measured value of the evaporator water level to the first calculation unit;

[0037] The flow rate monitoring device, which is communicatively connected to the first calculation unit. The flow rate monitoring device can obtain the measured value of the feed water flow rate and the measured value of the steam flow rate of the molten salt steam generation system in real time and transmit the measured value of the feed water flow rate and the measured value of the steam flow rate to the calculation unit;

[0038] The first calculation unit can calculate and obtain the comprehensive valve position command at the outlet of the feed water pump according to the received AGC load command, the actual power of the unit, the measured value of the evaporator water level, the measured value of the feed water flow rate and the measured value of the steam flow rate.

[0039] Optionally, the storage unit further stores a set value of the evaporator water level. The first calculation unit includes:

[0040] The main controller, which can receive the measured value of the evaporator water level and the set value of the evaporator water level, and calculate and obtain the set value of the feed water flow rate according to the deviation between the measured value of the evaporator water level and the set value of the evaporator water level,

[0041] The sub-controller, which is communicatively connected to the main controller. The sub-controller can receive the set value of the feed water flow rate and the measured value of the feed water flow rate, and calculate and obtain the first comprehensive valve position command at the outlet of the feed water pump according to the deviation between the set value of the feed water flow rate and the measured value of the feed water flow rate;

[0042] The first feedforward controller, which can receive the measured value of the steam flow rate and calculate and obtain the second comprehensive valve position command at the outlet of the feed water pump according to the measured value of the steam flow rate;

[0043] The second feedforward controller, which can receive the AGC load command and the actual power of the unit, and on the condition that the deviation between the AGC load command and the actual power is not less than a preset deviation, calculate and obtain the third comprehensive valve position command at the outlet of the feed water pump according to the deviation between the AGC load command and the actual power;

[0044] The adder, to which the sub-controller, the first feedforward controller and the second feedforward controller are all communicatively connected. The adder can calculate and obtain the comprehensive valve position command at the outlet of the feed water pump after superimposing the first comprehensive valve position command, the second comprehensive valve position command and the third comprehensive valve position command.

[0045] Optionally, it further includes a second water level monitoring device, which is communicatively connected to the first calculation unit. The first water level monitoring device can obtain the measured value of the deaerator water level in the molten salt steam generation system in real time and transmit the measured value of the deaerator water level to the first calculation unit;

[0046] The first calculation unit further includes a lock-up increase module, which can receive the measured value of the deaerator water level and the measured value of the evaporator water level, and when either the first signal or the second signal is valid, delay for a first preset time to generate a feed water flow lock-up increase signal;

[0047] When the measured value of the deaerator water level is lower than the low 1 value of the deaerator water level, the first signal is valid;

[0048] When the measured value of the evaporator water level is higher than the high 1 value of the evaporator water level and the measured value of the deaerator water level is not higher than the high 1 value of the deaerator water level, the second signal is valid;

[0049] When the feed water flow lock-up increase signal is valid, the first control unit controls the opening degrees of the main path regulating valve and the bypass regulating valve not to increase.

[0050] Optionally, the first calculation unit further includes a lock-up decrease module, which can receive the measured value of the deaerator water level and the measured value of the evaporator water level, and when either the third signal or the fourth signal is valid, delay for a second preset time to generate a feed water flow lock-up decrease signal;

[0051] When the measured value of the deaerator water level is higher than the high 1 value of the deaerator water level, the third signal is valid;

[0052] When the measured value of the evaporator water level is lower than the low 1 value of the evaporator water level and the measured value of the deaerator water level is not lower than the low 1 value of the deaerator water level, the fourth signal is valid;

[0053] When the feed water flow lock-up decrease signal is valid, the first control unit controls the opening degrees of the main path regulating valve and the bypass regulating valve not to decrease.

[0054] Optionally, it further includes a pressure detection device, which can obtain the outlet pressure and the inlet pressure of the feed water pump in real time;

[0055] The molten salt evaporator water level control device further includes a second calculation unit and a second control unit that are communicatively connected. The pressure detection device is communicatively connected to the second calculation unit, where:

[0056] The second calculation unit can receive the outlet pressure and the inlet pressure of the feed water pump, and calculate and obtain the feed water pump frequency command on the condition that the deviation between the outlet pressure and the inlet pressure of the feed water pump deviates from a preset deviation value;

[0057] The second control unit can adjust the feed water pump frequency of the molten salt steam generation system according to the feed water pump frequency command, so that the deviation between the outlet pressure and the inlet pressure of the feed water pump is maintained at the preset deviation value.

[0058] The present invention also provides a molten salt steam generation system coupled with a coal-fired unit, including a deaerator, a feed water pump, a regulating valve, a preheater, an evaporator, a superheater, a hot salt tank, a hot salt pump and a cold salt tank. According to the flow direction of the molten salt, the hot salt tank, the hot salt pump, the superheater, the evaporator, the preheater and the cold salt tank are connected in sequence. According to the flow direction of the steam and water, the deaerator, the feed water pump, the regulating valve, the preheater, the evaporator and the superheater are connected in sequence. The regulating valve includes a main path regulating valve and a bypass regulating valve, and the main path regulating valve and the bypass regulating valve are arranged in parallel;

[0059] It also includes the control device of the molten salt steam generation system coupled with the coal-fired unit as described above. The control device of the molten salt steam generation system coupled with the coal-fired unit is configured to control the opening degrees of the main path regulating valve and the bypass regulating valve so that the measured value of the evaporator water level is equal to the set value of the evaporator water level.

[0060] The molten salt steam generation system coupled with the coal-fired unit of the present invention includes the control device of the molten salt steam generation system coupled with the coal-fired unit as described above, and thus has the same technical effects as the control device of the molten salt steam generation system coupled with the coal-fired unit as described above, which will not be elaborated here. Description of the Drawings

[0061] Figure 1 It is the structure of a specific embodiment of the molten salt steam generation system coupled with the coal-fired unit provided by the present invention;

[0062] Figure 2 It is the first opening command function f 1 (x) and the second opening command function f 2 (x) are line graphs showing the change with the comprehensive valve position command at the outlet of the feed water pump;

[0063] Figure 3 It is a partial signal communication schematic diagram of the control device of the molten salt steam generation system coupled with the coal-fired unit provided by the present invention;

[0064] Figure 4 It is Figure 3Control logic diagram of the molten salt evaporator water level control device in the control device of the molten salt steam generation system coupled with a coal-fired unit;

[0065] Figure 5 For Figure 3 Schematic diagram of the feed water interlock increase logic structure in the control device of the molten salt steam generation system coupled with a coal-fired unit;

[0066] Figure 6 For Figure 3 Schematic diagram of the feed water interlock decrease logic structure in the control device of the molten salt steam generation system coupled with a coal-fired unit;

[0067] Among them, Figures 1-6 The descriptions of the reference numerals in the figures are as follows:

[0068] 1 - Deaerator; 2 - Feed water pump; 3 - Preheater; 4 - Evaporator; 5 - Superheater; 6 - Hot salt tank; 7 - Hot salt pump; 8 - Cold salt tank; 9 - Main path regulating valve; 10 - Bypass regulating valve;

[0069] 01 - Molten salt evaporator water level control device; 011 - Main controller; 012 - Sub - controller; 013 - First feed - forward controller; 014 - Second feed - forward controller; 015 - Adder; 016 - First low - alarm device; 017 - First high - alarm device; 018 - Second high - alarm device; 019 - NOT gate; 020 - AND gate; 021 - OR gate; 022 - First delay device; 023 - Third high - alarm device; 024 - Second low - alarm device; 025 - Third low - alarm device; 026 - Second delay device;

[0070] 02 - RTU system;

[0071] 03 - DCS system. Specific embodiments

[0072] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0073] As used herein, "a plurality" generally means more than two; and when "a plurality" is used to represent the quantity of several components, it does not represent the mutual relationship in quantity of these components.

[0074] In this article, Figure 1 In the figures, solid lines represent the flow paths of molten salt, and dashed lines represent the flow paths of steam - water.

[0075] Please refer to Figures 1-2 , Figure 1 which is the structure of a specific embodiment of the molten salt steam generation system coupled with a coal - fired unit provided by the present invention; Figure 2 Is the first opening command function f 1(x) and the second opening command function f 2 (x) is a broken line graph showing the variation with the combined valve position command at the outlet of the feed water pump.

[0076] The present invention discloses a control method for a molten salt steam generation system coupled with a coal-fired unit, comprising the following steps:

[0077] Obtain the first opening command function f 1 (x) and the second opening command function f 2 (x), the first opening command function f 1 (x) and the second opening command function f 2 (x) are both broken line functions regarding the variation of the combined valve position command at the outlet of the feed water pump, and f 1 (x) ≠ f 2 (x);

[0078] Obtain the combined valve position command at the outlet of the feed water pump in real time, and obtain the first opening through the first opening command function f 1 (x), and obtain the second opening through the second opening command function f 2 (x);

[0079] Control the opening of the main path regulating valve 9 in the molten salt steam generation system to be the first opening, and control the opening of the bypass regulating valve 10 in the molten salt steam generation system to be the second opening, so as to adjust the feed water flow rate of the molten salt steam generation system, so that the measured value of the evaporator water level in the molten salt steam generation system is equal to the set value of the evaporator water level;

[0080] The main path regulating valve 9 and the bypass regulating valve 10 are arranged in parallel between the feed water outlet of the feed water pump 2 and the feed water inlet of the evaporator 4 in the molten salt steam generation system.

[0081] The control method of the molten salt steam generation system coupled with the coal-fired unit of the present invention is applicable to the molten salt steam generation system coupled with the coal-fired unit as shown in Figure 1 In order to improve the load change rate of the unit and support the rapid load change of the unit, the molten salt steam generation system needs to be put into use throughout the operation of the unit. Therefore, the molten salt steam generation system is usually set with a heat release mode and a heat tracing mode. In the heat tracing mode, the molten salt and the steam-water circuit operate with a small flow rate, and a temperature field similar to the heat release mode is established in the system to prepare for responding to the rapid load increase of the unit at any time; when the molten salt steam generation system receives an auxiliary unit load increase command, the molten salt steam generation system needs to switch from the heat tracing mode to the heat release mode, and the molten salt heats the feed water to generate steam, which is jointly fed into the steam turbine to do work with the steam generated by the boiler.

[0082] During this process, in order to ensure the steam-water balance and achieve the safe operation of the unit, the present invention precisely controls the water level of the evaporator that characterizes the feed water and steam balance. Structurally, a main path regulating valve 9 and a bypass regulating valve 10 are arranged in parallel between the feed water outlet of the feed water pump 2 and the feed water inlet of the evaporator 4 in the molten salt steam generation system. The main path regulating valve 9 and the bypass regulating valve 10 cooperate to regulate the feed water flow of the molten salt steam generation system. Usually, the pipe diameter of the main path regulating valve 9 is larger than that of the bypass regulating valve 10, that is, the maximum flow area of the main path regulating valve 9 is larger than the maximum flow area of the bypass regulating valve 10.

[0083] It can be understood that in the heat release mode, the steam-water flow rate is large; in the heat tracing mode, the steam-water flow rate is small. In the control of the main path regulating valve 9 and the bypass regulating valve 10, if the feed water simply passes through the bypass regulating valve 10 with a smaller self-flow area in the heat tracing mode and through the main path regulating valve 9 with a larger self-flow area in the heat release mode, it will inevitably cause a large fluctuation in the feed water flow rate during the switching process between the main path regulating valve 9 and the bypass regulating valve 10, which is not conducive to the full-automatic control of the molten salt steam generation system.

[0084] Based on this, the present invention provides the control method of the molten salt steam generation system coupled with the above coal-fired unit, wherein the first opening command function f 1 (x) and the second opening command function f 2 (x) can be actually debugged in advance according to parameters such as the flow areas of the main path regulating valve 9 and the bypass regulating valve 10 and the feed water flow rate. The obtained first opening command function f 1 (x) and the second opening command function f 2 (x) are in the form as Figure 2 shown. Both the first opening command function f1(x) and the second opening command function f2(x) are broken-line functions regarding the change of the comprehensive valve position command at the feed water pump outlet. The first opening command function f 1 (x) is used to control the opening of the main path regulating valve 9, and the second opening command function f 2 (x) is used to control the opening of the bypass regulating valve 10. In this way, by obtaining the comprehensive valve position command at the feed water pump outlet in real time, the opening of the main path regulating valve 9 can be obtained through the first opening command function f1(x), and the opening of the bypass regulating valve 10 can be obtained through the second opening command function f 2 (x). The openings of the main path regulating valve 9 and the bypass regulating valve 10 are adjusted in real time according to the obtained opening commands, so as to adjust the feed water flow rate of the molten salt steam generation system, make the measured value of the water level of the evaporator in the molten salt steam generation system equal to the set value of the evaporator water level, indicating that the molten salt steam generation system is in a steam-water balance state. At this time, the main path regulating valve 9 and the bypass regulating valve 10 can be maintained at the current opening.

[0085] In summary, the control method of the molten salt steam generation system coupled with a coal-fired unit obtains the opening commands of the main path regulating valve 9 and the bypass regulating valve 10 respectively through two first opening command functions f 1 (x) and the second opening command function f 2 (x) with different forms but complementary characteristics according to the magnitude of the comprehensive valve position command at the outlet of the feed water pump, and adjusts the feed water flow of the molten salt steam generation system. It can not only weaken the nonlinearity of a single valve, which is beneficial to the control of the header flow, but also avoid large fluctuations in the feed water flow during the switching process of the main path regulating valve 9 and the bypass regulating valve 10, making the comprehensive valve position command at the outlet of the feed water pump and the actual feed water flow show a good linear relationship, realizing the full-condition automatic control of the evaporator water level in the large-flow heat release mode and the small-flow heat tracing mode of the molten salt steam generation system, and ensuring the safe operation of the unit.

[0086] Among them, the real-time acquisition of the comprehensive valve position command at the outlet of the feed water pump specifically includes the following steps:

[0087] Real-time monitor the evaporator water level and feed water flow of the molten salt steam generation system, obtain the measured values of the evaporator water level and the feed water flow, generate a feed water flow set value according to the deviation between the measured value of the evaporator water level and the set value of the evaporator water level, and generate a first comprehensive valve position command at the outlet of the feed water pump according to the deviation between the measured value of the feed water flow and the set value of the feed water flow;

[0088] Real-time monitor the steam flow of the molten salt steam generation system, obtain the measured value of the steam flow, and generate a second comprehensive valve position command at the outlet of the feed water pump according to the measured value of the steam flow;

[0089] Real-time monitor the working state of the coupled coal-fired unit, obtain the actual power of the unit, and receive the AGC (Automatic Generation Control) load command, calculate the deviation between the AGC load command and the actual power of the unit. When the deviation between the AGC load command and the actual power of the unit is not less than the preset deviation, generate a third comprehensive valve position command at the outlet of the feed water pump according to the deviation between the AGC load command and the actual power;

[0090] Superimpose the first comprehensive valve position command, the second comprehensive valve position command and the third comprehensive valve position command to obtain the comprehensive valve position command at the outlet of the feed water pump.

[0091] As described above, the water level control of the evaporator of the present invention adopts a three - impulse control strategy. The first integrated valve position command at the outlet of the feed water pump is obtained through the water level and feed water flow rate of the evaporator in the molten salt steam generation system; the steam flow rate of the molten salt steam generation system is used as the first feed - forward signal to obtain the second integrated valve position command at the outlet of the feed water pump; the deviation between the AGC load command and the actual power of the unit is used as the second feed - forward signal to obtain the third integrated valve position command at the outlet of the feed water pump; the integrated valve position command at the outlet of the feed water pump is obtained after superimposing the above three signals. For example, if the value of the first integrated valve position command at the outlet of the feed water pump actually generated is 80, the value of the second integrated valve position command at the outlet of the feed water pump is 3, and the value of the third integrated valve position command at the outlet of the feed water pump is - 1, after superimposing, the value of the integrated valve position command at the outlet of the feed water pump is 82, that is, the feed water flow rate at the outlet of the feed water pump should be 82% of the maximum feed water flow rate. By obtaining the above three signals in real - time, the whole - process automatic control of the evaporator water level can be realized, with higher control accuracy and ensuring the safe operation of the unit.

[0092] Among them, the water level of the evaporator in the molten salt steam generation system can be detected by a water level sensor arranged inside the evaporator; the feed water flow rate of the molten salt steam generation system can be detected by a flow sensor arranged on the feed water return line; the steam flow rate of the molten salt steam generation system can be detected by a flow sensor arranged on the steam return line.

[0093] As mentioned above, when obtaining the third integrated valve position command at the outlet of the feed water pump, the third integrated valve position command at the outlet of the feed water pump will be generated only when the deviation between the AGC load command and the actual power of the unit is not less than the preset deviation. If the deviation between the AGC load command and the actual power of the unit is lower than the preset deviation, it can be considered that the actual power of the unit has reached the AGC load command. At this time, the third integrated valve position command at the outlet of the feed water pump is 0. In practice, this preset deviation can be adaptively set according to the actual operating conditions of the unit and is not limited here.

[0094] Furthermore, the control method of the molten salt steam generation system coupled with a coal - fired unit of the present invention further includes the following steps:

[0095] When any one of the first signal and the second signal is valid, after delaying for the first preset time, the feed water flow rate locking increase signal is valid, and the opening degrees of the main - path regulating valve 9 and the bypass regulating valve 10 are controlled not to increase;

[0096] When the measured value of the deaerator water level is lower than the deaerator water level low - 1 value, the first signal is valid;

[0097] When the measured value of the evaporator water level is higher than the evaporator water level high - 1 value and the measured value of the deaerator water level is not higher than the deaerator water level high - 1 value, the second signal is valid.

[0098] Since the molten salt steam generation system extracts a part of deaerated water from the deaerator, long-term operation will affect the water level of the deaerator, and further affect the safe operation of the unit. Based on this, the control method of the molten salt steam generation system coupled with a coal-fired unit also monitors the water level of the deaerator and the water level of the evaporator, and sets a water supply blocking increment logic. If the evaporator water level or the deaerator water level shows a corresponding abnormal state during the operation of the steam generation system, that is, the first signal is valid or the second signal is valid, after a first preset time delay, the water supply flow blocking increment signal is valid. At this time, the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 are controlled not to increase, that is, the water supply flow of the molten salt steam generation system is controlled not to continue to increase, so as to avoid the continuous deterioration of the evaporator water level or the deaerator water level, and ensure the safety of the unit operation.

[0099] There are two abnormal states that conform to the water supply flow blocking increment logic. Specifically:

[0100] The first abnormal state is that the measured value of the deaerator water level is lower than the low 1 value of the deaerator water level. The low 1 value of the deaerator water level can be set according to the actual working conditions of the deaerator. The low 1 value of the deaerator water level is usually slightly lower than the lower limit of the safe water level of the deaerator. When the measured value of the deaerator water level is lower than the low 1 value of the deaerator water level, it indicates that the deaerator water level has dropped below the lower limit of the safe water level of the deaerator, that is, the deaerator water level is in an abnormally low state. At this time, the first signal is valid, and the water supply flow of the molten salt steam generation system cannot continue to increase, so as to avoid the continuous deterioration of the deaerator water level, ensure that the deaerator water level can recover to the safe range faster, ensure the safe operation of the deaerator, and further ensure the safety of the unit operation.

[0101] The second abnormal state is that the measured value of the evaporator water level is higher than the high 1 value of the evaporator water level, and the measured value of the deaerator water level is not higher than the high 1 value of the deaerator water level. Among them, the high 1 value of the evaporator water level and the high 1 value of the deaerator water level can both be set according to the actual working conditions of the evaporator. The high 1 value of the evaporator water level is usually slightly higher than the upper limit of the safe water level of the evaporator, and the high 1 value of the deaerator water level is usually slightly higher than the upper limit of the safe water level of the deaerator. When the measured value of the evaporator water level is higher than the high 1 value of the evaporator water level, and the measured value of the deaerator water level is not higher than the high 1 value of the deaerator water level, it indicates that the evaporator water level has risen above the upper limit of the safe water level of the evaporator, that is, the evaporator water level is in an abnormally high state. At this time, the second signal is valid, and the water supply flow of the molten salt steam generation system also cannot continue to increase, so as to avoid the continuous deterioration of the evaporator water level, ensure that the evaporator water level can recover to the safe range faster, ensure the safe operation of the evaporator, and further ensure the safety of the unit operation.

[0102] In this embodiment, the first preset time is 3s. Of course, this numerical limitation is only for illustrative purposes. In practice, it can be adaptively adjusted according to the operating conditions of the unit to ensure the safe operation of the unit.

[0103] As described above, when the water supply flow rate lock-up increase signal is valid, the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 are no longer increased. In practice, the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 can remain unchanged or gradually decrease, so that the water level of the evaporator or the water level of the deaerator can return to the safe range faster.

[0104] Furthermore, the control method of the molten salt steam generation system coupled with a coal-fired unit of the present invention further includes the following steps:

[0105] When any one of the third signal and the fourth signal is valid, delay for a second preset time, and the water supply flow rate lock-up decrease signal is valid, controlling the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 to no longer decrease;

[0106] When the measured value of the deaerator water level is higher than the high 1 value of the deaerator water level, the third signal is valid;

[0107] When the measured value of the evaporator water level is lower than the low 1 value of the evaporator water level and the measured value of the deaerator water level is not lower than the low 1 value of the deaerator water level, the fourth signal is valid.

[0108] The control method of the molten salt steam generation system coupled with a coal-fired unit of the present invention also monitors the deaerator water level and the evaporator water level, and sets a water supply lock-up decrease logic. If the evaporator water level or the deaerator water level appears in a corresponding abnormal state during the operation of the steam generation system, that is, the third signal is valid or the fourth signal is valid, after delaying for a second preset time, the water supply flow rate lock-up decrease signal is valid. At this time, the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 are controlled to no longer decrease, that is, the water supply flow rate of the molten salt steam generation system is controlled not to continue to decrease, avoiding the continuous deterioration of the evaporator water level or the deaerator water level, and ensuring the safety of the unit operation.

[0109] Among them, there are two abnormal states that conform to the water supply flow rate lock-up increase logic. Specifically:

[0110] The first abnormal state is that the measured value of the deaerator water level is higher than the high 1 value of the deaerator water level. As described above, the high 1 value of the deaerator water level here can be set according to the actual working conditions of the deaerator. The high 1 value of the deaerator water level is usually slightly higher than the upper limit of the safe water level of the deaerator. When the measured value of the deaerator water level is higher than the high 1 value of the deaerator water level, it indicates that the deaerator water level has risen above the upper limit of the safe water level of the deaerator, that is, the deaerator water level is in an abnormally high state. At this time, the third signal is valid, and the water supply flow rate of the molten salt steam generation system cannot continue to decrease, avoiding the continuous deterioration of the deaerator water level, ensuring that the deaerator water level can return to the safe range faster, ensuring the safe operation of the deaerator, and further ensuring the safety of the unit operation.

[0111] The second abnormal state is that the measured value of the evaporator water level is lower than the first low value of the evaporator water level, and the measured value of the deaerator water level is not lower than the first low value of the deaerator water level. Herein, the first low value of the evaporator water level and the first low value of the deaerator water level can both be set according to the actual working conditions of the evaporator. The first low value of the evaporator water level is usually slightly lower than the lower limit of the safe water level of the evaporator, and the first low value of the deaerator water level is usually slightly lower than the lower limit of the safe water level of the deaerator. When the measured value of the evaporator water level is lower than the first low value of the evaporator water level and the measured value of the deaerator water level is not lower than the first low value of the deaerator water level, it indicates that the evaporator water level has dropped below the lower limit of the safe water level of the evaporator, that is, the evaporator water level is in an abnormally low state. At this time, the fourth signal is valid, and the feed water flow rate of the molten salt steam generation system cannot be further reduced either, so as to avoid the continuous deterioration of the evaporator water level, ensure that the evaporator water level can recover to the safe range faster, ensure the safe operation of the evaporator, and further guarantee the safety of the unit operation.

[0112] In this embodiment, the second preset time is 3 s. Of course, this numerical limitation is only for illustrative purposes. In practice, it can be adaptively adjusted according to the operating conditions of the unit to ensure the safe operation of the unit.

[0113] Similarly, as described above, when the feed water flow rate blocking reduction signal is valid, the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 are no longer reduced, that is, the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 can remain unchanged or increase, so that the evaporator water level or the deaerator water level can recover to the safe range faster.

[0114] Furthermore, the control method of the molten salt steam generation system coupled with a coal-fired unit of the present invention further includes the following steps:

[0115] Obtain the outlet pressure and the inlet pressure of the feed water pump, generate a feed water pump frequency command based on the deviation between the outlet pressure and the inlet pressure of the feed water pump deviating from a preset deviation value, and adjust the feed water pump frequency so that the deviation between the outlet pressure and the inlet pressure of the feed water pump is maintained at the preset deviation value.

[0116] With the above settings, the control method of the molten salt steam generation system coupled with a coal-fired unit of the present invention also monitors the outlet pressure and the inlet pressure of the feed water pump, and controls the deviation between the outlet pressure and the inlet pressure of the feed water pump to be maintained at the preset deviation value by adjusting the feed water pump frequency, providing a certain head for the feed water circuit of the molten salt steam generation system to ensure that the feed water can be continuously discharged from the outlet of the feed water pump.

[0117] In practice, the outlet pressure of the feed water pump can be detected by a pressure sensor arranged at the outlet of the feed water pump, and the inlet pressure of the feed water pump can be detected by a pressure sensor arranged at the inlet of the feed water pump.

[0118] Among them, when adjusting the frequency of the feed water pump, if the deviation between the outlet pressure and the inlet pressure of the feed water pump is lower than the preset deviation value, the feed water frequency should be increased to increase the outlet pressure of the feed water pump, so that the deviation between the outlet pressure and the inlet pressure of the feed water pump is maintained at the preset deviation value; if the deviation between the outlet pressure and the inlet pressure of the feed water pump is higher than the preset deviation value, the feed water pump frequency should be decreased to reduce the outlet pressure of the feed water pump, so that the deviation between the outlet pressure and the inlet pressure of the feed water pump is maintained at the preset deviation value.

[0119] The present invention provides a control device for a molten salt steam generation system coupled with a coal-fired unit, which is applicable to the control method of the molten salt steam generation system coupled with the coal-fired unit described above. It includes a molten salt evaporator water level control device 01. The molten salt evaporator water level control device 01 includes a storage unit, a first calculation unit, and a first control unit that are communicatively connected. Among them:

[0120] The storage unit stores a first opening command function f 1 (x) and a second opening command function f 2 (x). The first opening command function f 1 (x) and the second opening command function f 2 (x) are both piecewise functions regarding the change of the comprehensive valve position command at the outlet of the feed water pump, and f 1 (x) ≠ f 2 (x);

[0121] The first calculation unit can calculate and obtain the comprehensive valve position command at the outlet of the feed water pump in real time, and obtain the first opening through the first opening command function f 1 (x), and obtain the second opening through the second opening command function f 2 (x);

[0122] The first control unit can control the opening of the main path regulating valve 9 in the molten salt steam generation system to be the first opening, and control the opening of the bypass regulating valve 10 in the molten salt steam generation system to be the second opening, so as to adjust the feed water flow rate in the molten salt steam generation system, so that the measured value of the evaporator water level in the molten salt steam generation system is equal to the set value of the evaporator water level.

[0123] The control device of the molten salt steam generation system coupled with the coal-fired unit of the present invention is applicable to the control method of the molten salt steam generation system coupled with the coal-fired unit described above. Therefore, it has the same technical effects as the control method of the molten salt steam generation system coupled with the coal-fired unit described above, and will not be elaborated here.

[0124] Among them, the first opening command function f 1 (x) and the second opening command function f 2 (x) can be actually debugged in advance according to parameters such as the flow area of the main path regulating valve 9 and the bypass regulating valve 10, and the feed water flow rate, etc., to obtainFigure 2 The first opening command function f 1 (x) and the second opening command function f 2 (x). The obtained first opening command function f 1 (x) and the second opening command function f 2 (x) are pre-stored in the storage unit.

[0125] It can be understood that in practice, the first control unit is electrically connected to the main path regulating valve 9 and the bypass regulating valve 10 to precisely control the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 through the first control unit.

[0126] Furthermore, the control device of the molten salt steam generation system coupled with the coal-fired unit of the present invention further includes:

[0127] An RTU (Remote Terminal Unit) system. The RTU system is communicatively connected to the first calculation unit. The RTU system can obtain the AGC load command in real time and transmit the AGC load command to the calculation unit;

[0128] A DCS (Distributed Control System) system. The DCS system is communicatively connected to the first calculation unit. The RTU system can obtain the actual power of the unit in real time and transmit the actual power of the unit to the calculation unit;

[0129] A first water level monitoring device. The first water level monitoring device is communicatively connected to the first calculation unit. The first water level monitoring device can obtain the measured value of the evaporator water level of the molten salt steam generation system in real time and transmit the measured value of the evaporator water level to the first calculation unit;

[0130] A flow monitoring device. The flow monitoring device is communicatively connected to the first calculation unit. The flow monitoring device can obtain the measured value of the feed water flow and the measured value of the steam flow of the molten salt steam generation system in real time and transmit the measured value of the feed water flow and the measured value of the steam flow to the calculation unit;

[0131] The first calculation unit can calculate and obtain the comprehensive valve position command at the outlet of the feed water pump according to the received AGC load command, the actual power of the unit, the measured value of the evaporator water level, the measured value of the feed water flow, and the measured value of the steam flow.

[0132] The control device of the molten salt steam generation system coupled with a coal-fired unit couples the RTU system, DCS system, first water level monitoring device, flow monitoring device, and molten salt evaporator water level control device 01, and obtains the AGC load command, actual unit power, measured value of the evaporator water level, measured value of the feed water flow rate, and measured value of the steam flow rate in real time to calculate and obtain the comprehensive valve position command at the outlet of the feed water pump, realizing the full-process automatic control of the evaporator water level. The three-impulse control strategy has higher control accuracy and ensures the safe operation of the unit.

[0133] Among them, the RTU system and DCS system are both mature existing technologies in the art and will not be elaborated here.

[0134] Among them, the first water level monitoring device can be a water level monitoring sensor and is arranged inside the evaporator.

[0135] Among them, the flow monitoring device can include at least two flow sensors. At least one flow sensor is arranged on the feed water loop of the molten salt steam generation system to detect the feed water flow rate; at least one flow sensor is arranged on the steam loop of the molten salt steam generation system to detect the steam flow rate.

[0136] Please refer to Figure 4 , Figure 4 For Figure 3 the control logic diagram of the molten salt evaporator water level control device in the control device of the molten salt steam generation system coupled with a coal-fired unit.

[0137] Furthermore, the storage unit also stores the set value of the evaporator water level. The first calculation unit includes:

[0138] The main controller 011 can receive the measured value of the evaporator water level and the set value of the evaporator water level, and calculate and obtain the set value of the feed water flow rate according to the deviation between the measured value of the evaporator water level and the set value of the evaporator water level.

[0139] The secondary controller 012 is communicatively connected to the main controller 011. The secondary controller 012 can receive the set value of the feed water flow rate and the measured value of the feed water flow rate, and calculate and obtain the first comprehensive valve position command at the outlet of the feed water pump according to the deviation between the set value of the feed water flow rate and the measured value of the feed water flow rate.

[0140] The first feedforward controller 013 can receive the measured value of the steam flow rate and calculate and obtain the second comprehensive valve position command at the outlet of the feed water pump according to the measured value of the steam flow rate.

[0141] The second feed-forward controller 014 can receive the AGC load command and the actual power of the unit, and on the condition that the deviation between the AGC load command and the actual power of the unit is not less than a preset deviation, calculate and obtain the third comprehensive valve position command at the outlet of the feed water pump according to the deviation between the AGC load command and the actual power;

[0142] An adder 015, the secondary controller 012, the first feed-forward controller 013, and the second feed-forward controller 014 are all communicatively connected to the adder 015. The adder 015 can calculate and obtain the comprehensive valve position command at the outlet of the feed water pump after superimposing the first comprehensive valve position command, the second comprehensive valve position command, and the third comprehensive valve position command.

[0143] With the above settings, the first calculation unit of the present invention adopts a cascade plus two-way feed-forward control method. Specifically, the main controller generates a feed water flow rate set value based on the measured value of the evaporator water level and the set value of the evaporator water level, and enters the secondary controller; the secondary controller generates the first comprehensive valve position command at the outlet of the feed water pump according to the feed water flow rate set value and the measured value of the feed water flow rate, and then superimposes two-way feed-forward signals: one feed-forward signal is determined by the first feed-forward controller through the measured value of the steam flow rate, and the other feed-forward signal is determined by the second feed-forward controller through the AGC load command and the actual power of the unit. At the same time, from Figure 3 It can be seen that a dead zone is designed in the second feed-forward controller, so that this path of signal is effective only when the deviation between the AGC load command and the actual power of the unit is not less than the preset deviation.

[0144] Please refer to Figure 5 , Figure 5 For Figure 3 the schematic diagram of the feed water interlock increase logic structure in the control device of the molten salt steam generation system coupled with a coal-fired unit.

[0145] Furthermore, the control device of the molten salt steam generation system coupled with a coal-fired unit of the present invention further includes a second water level monitoring device. The second water level monitoring device is communicatively connected to the first calculation unit. The second water level monitoring device can obtain the measured value of the deaerator water level of the molten salt steam generation system in real time and transmit the measured value of the deaerator water level to the first calculation unit;

[0146] The first calculation unit further includes an interlock increase module. The interlock increase module can receive the measured value of the deaerator water level and the measured value of the evaporator water level, and generate a feed water flow rate interlock increase signal after delaying for a first preset time when any one of the first signal and the second signal is effective;

[0147] When the measured value of the deaerator water level is lower than the low 1 value of the deaerator water level, the first signal is effective;

[0148] When the measured value of the evaporator water level is higher than the high 1 value of the evaporator water level and the measured value of the deaerator water level is not higher than the high 1 value of the deaerator water level, the second signal is effective;

[0149] When the water supply flow rate lock - increase signal is valid, the first control unit controls that the opening degrees of the main - path regulating valve 9 and the bypass regulating valve 10 do not increase any more.

[0150] The control device of the molten - salt steam generation system coupled with a coal - fired unit according to the present invention is provided with a first water - level monitoring device and a second water - level monitoring device to monitor the water level of the evaporator and the water level of the deaerator. The first calculation unit sets the logic of the water supply lock - increase. If an abnormal state that matches occurs in the water level of the evaporator or the water level of the deaerator during the operation of the steam generation system, that is, the first signal is valid or the second signal is valid, after a first preset time delay, the water supply flow rate lock - increase signal is valid. At this time, the control unit controls that the opening degrees of the main - path regulating valve 9 and the bypass regulating valve 10 do not increase any more, that is, controls that the water supply flow rate of the molten - salt steam generation system does not continue to increase, avoiding the continuous deterioration of the water level of the evaporator or the water level of the deaerator, and ensuring the safety of the unit operation.

[0151] Among them, when the measured value of the deaerator water level is lower than the low - 1 value of the deaerator water level, it indicates that the deaerator water level has dropped below the lower limit value of the deaerator safety water level, that is, the deaerator water level is in an abnormally low state. At this time, the first signal is valid, and the water supply flow rate of the molten - salt steam generation system cannot continue to increase, avoiding the continuous deterioration of the deaerator water level, ensuring that the deaerator water level can recover to the safe range faster, ensuring the safe operation of the deaerator, and further ensuring the safety of the unit operation. The low - 1 value of the deaerator water level is usually set slightly lower than the lower limit value of the deaerator safety water level.

[0152] Among them, when the measured value of the evaporator water level is higher than the high - 1 value of the evaporator water level and the measured value of the deaerator water level is not higher than the high - 1 value of the deaerator water level, it indicates that the evaporator water level has risen above the upper limit value of the evaporator safety water level, that is, the evaporator water level is in an abnormally high state. At this time, the second signal is valid, and the water supply flow rate of the molten - salt steam generation system also cannot continue to increase, avoiding the continuous deterioration of the evaporator water level, ensuring that the evaporator water level can recover to the safe range faster, ensuring the safe operation of the evaporator, and further ensuring the safety of the unit operation. The high - 1 value of the evaporator water level is usually set slightly higher than the upper limit value of the evaporator safety water level, and the high - 1 value of the deaerator water level is usually set slightly higher than the upper limit value of the deaerator safety water level.

[0153] In this embodiment, the first preset time is 3 s. Of course, this numerical limit is only for illustrative purposes. In practice, it can be adjusted adaptively according to the operating conditions of the unit to ensure the safe operation of the unit.

[0154] Among them, the first control unit controls the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 not to increase. In practice, the first control unit can control the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 to remain unchanged, or can control the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 to gradually decrease, so that the evaporator water level or the deaerator water level can return to the safe range faster.

[0155] It can be seen from Figure 5 that in this embodiment, the closing increment module includes a first low alarm device 016, a first high alarm device 017, a second high alarm device 018, a NOT gate 019, an AND gate 020, an OR gate 021, and a first delay device 022. Among them, the input end of the first low alarm device 016 is the measured value of the deaerator water level, the output end of the first low alarm device 016 is connected to the first input end of the OR gate 021, the input end of the first high alarm device 017 is the measured value of the deaerator water level, the output end of the first high alarm device 017 is connected to the input end of the NOT gate 019, the output end of the NOT gate 019 is connected to the first input end of the AND gate 020, the input end of the second high alarm device 018 is the measured value of the evaporator water level, the output end of the second high alarm device 018 is connected to the second input end of the AND gate 020, the output end of the AND gate 020 is connected to the second input end of the OR gate 021, and the output end of the OR gate 021 is connected to the first delay device 022.

[0156] With the above settings, when the measured value of the deaerator water level is lower than the low 1 value of the deaerator water level, the output signal of the first low alarm device 016 is 1, that is, the first signal is valid. When the measured value of the deaerator water level is not higher than the high 1 value of the deaerator water level, the output signal of the first high alarm device 018 is 0. After passing through the NOT gate 019, the output signal of the NOT gate 019 is 1, that is, the first input end of the AND gate 020 is 1; when the measured value of the evaporator water level is higher than the high 1 value of the evaporator water level, the output signal of the second high alarm device 018 is 1. Thus, both input signals of the AND gate 020 are 1, and the output signal of the AND gate 020 is 1, that is, the second signal is valid. The output end of the first low alarm device 016 and the output end of the AND gate 020 are connected to the two input ends of the OR gate 021. That is, when any one of the first signal and the second signal is valid, the output signal of the OR gate is 1. After being delayed by the first preset time by the first delay device 022, a feed water flow closing increment signal is generated.

[0157] Please refer to Figure 6 , Figure 6 is Figure 3 a simplified logic diagram of the feed water closing decrement in the control device of the molten salt steam generation system coupled with a coal-fired unit.

[0158] Further, in the control device of the molten salt steam generation system coupled with a coal-fired unit of the present invention, the first calculation unit further includes a block and reduce module. The block and reduce module can receive the measured value of the deaerator water level and the measured value of the evaporator water level, and when either the third signal or the fourth signal is valid, delay for a second preset time to generate a feed water flow block and reduce signal;

[0159] When the measured value of the deaerator water level is higher than the high 1 value of the deaerator water level, the third signal is valid;

[0160] When the measured value of the evaporator water level is lower than the low 1 value of the evaporator water level and the measured value of the deaerator water level is not lower than the low 1 value of the deaerator water level, the fourth signal is valid;

[0161] When the feed water flow block and reduce signal is valid, the first control unit controls the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 not to decrease any further.

[0162] In the control device of the molten salt steam generation system coupled with a coal-fired unit of the present invention, the first calculation unit sets a feed water block and reduce logic. If the evaporator water level or the deaerator water level shows a corresponding abnormal state during the operation of the steam generation system, that is, the third signal or the fourth signal is valid, after delaying for a second preset time, the feed water flow block and reduce signal is valid. At this time, the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 are controlled not to decrease any further, that is, the feed water flow of the molten salt steam generation system is controlled not to continue to decrease, avoiding the continuous deterioration of the evaporator water level or the deaerator water level and ensuring the safety of the unit operation.

[0163] Among them, when the measured value of the deaerator water level is higher than the high 1 value of the deaerator water level, it indicates that the deaerator water level has risen above the upper limit of the deaerator safety water level, that is, the deaerator water level is in an abnormally high state. At this time, the third signal is valid, and the feed water flow of the molten salt steam generation system cannot continue to decrease, avoiding the continuous deterioration of the deaerator water level, ensuring that the deaerator water level can recover to the safe range faster, ensuring the safe operation of the deaerator, and further ensuring the safety of the unit operation. The high 1 value of the deaerator water level is usually set slightly higher than the upper limit of the deaerator safety water level.

[0164] Among them, when the measured value of the evaporator water level is lower than the low 1 value of the evaporator water level and the measured value of the deaerator water level is not lower than the low 1 value of the deaerator water level, it indicates that the evaporator water level has dropped below the lower limit of the evaporator safety water level, that is, the evaporator water level is in an abnormally low state. At this time, the fourth signal is valid, and the feed water flow of the molten salt steam generation system also cannot continue to decrease, avoiding the continuous deterioration of the evaporator water level, ensuring that the evaporator water level can recover to the safe range faster, ensuring the safe operation of the evaporator, and further ensuring the safety of the unit operation. The low 1 value of the evaporator water level is usually set slightly lower than the lower limit of the evaporator safety water level, and the low 1 value of the deaerator water level is usually set slightly lower than the lower limit of the deaerator safety water level.

[0165] Among them, in this embodiment, the second preset time is 3 s. Of course, this numerical limit is only for illustrative purposes. In practice, it can be adaptively adjusted according to the operating conditions of the unit.

[0166] From Figure 6 It can be seen that in this embodiment, the closed-loop reduction module includes a third high alarm device 023, a second low alarm device 024, a third low alarm device 025, a NOT gate 019, an AND gate 020, an OR gate 021, and a second delay device 026. Among them, the input end of the third high alarm device 023 is the measured value of the deaerator water level. The output end of the third high alarm device 023 is connected to the first input end of the OR gate 021. The input end of the second low alarm device 024 is the measured value of the deaerator water level. The output end of the second low alarm device 024 is connected to the input end of the NOT gate 019. The output end of the NOT gate 019 is connected to the first input end of the AND gate 020. The input end of the third low alarm device 025 is the measured value of the evaporator water level. The output end of the third low alarm device 025 is connected to the second input end of the AND gate 020. The output end of the AND gate 020 is connected to the second input end of the OR gate 021. The output end of the OR gate 021 is connected to the second delay device 026.

[0167] With the above settings, when the measured value of the deaerator water level is higher than the high 1 value of the deaerator water level, the output signal of the third high alarm device 023 is 1, that is, the third signal is valid. When the measured value of the deaerator water level is not lower than the low 1 value of the deaerator water level, the output signal of the second low alarm device 024 is 0. After passing through the NOT gate 019, the first input end of the AND gate 020 is 1. When the measured value of the evaporator water level is lower than the low 1 value of the evaporator water level, the output signal of the third low alarm device 025 is 1. Thus, both input signals of the AND gate 020 are 1, and the output signal of the AND gate 020 is 1, that is, the fourth signal is valid. The output end of the third high alarm device 023 and the output end of the AND gate 020 are connected to the two input ends of the OR gate 021. That is, when any one of the first signal and the second signal is valid, the output signal of the OR gate is 1. After being delayed by the second preset time by the second delay device 026, a feed water flow closed-loop reduction signal is generated.

[0168] Furthermore, the control device of the molten salt steam generation system coupled to the coal-fired unit of the present invention further includes a pressure detection device, and the pressure detection device can acquire the outlet pressure and inlet pressure of the feed water pump in real time;

[0169] The molten salt evaporator water level control device 01 further includes a second calculation unit and a second control unit connected by communication. The pressure detection device is communicatively connected to the second calculation unit, where:

[0170] The second calculation unit can receive the outlet pressure and inlet pressure of the feed water pump, and calculate and obtain the feed water pump frequency command on the condition that the deviation between the outlet pressure and inlet pressure of the feed water pump deviates from the preset deviation value;

[0171] The second control unit can adjust the feed pump frequency of the molten salt steam generation system according to the feed pump frequency command, so that the deviation between the feed pump outlet pressure and the feed pump inlet pressure is maintained at a preset deviation value.

[0172] The control device of the molten salt steam generation system coupled with the coal-fired unit of the present invention is also provided with a pressure detection device to monitor the feed pump outlet pressure and the feed pump inlet pressure. The second calculation unit calculates and obtains the feed pump frequency command, and the second control unit adjusts the feed pump frequency to control the deviation between the feed pump outlet pressure and the feed pump inlet pressure to be maintained at a preset deviation value, providing a certain head for the feed water circuit of the molten salt steam generation system to ensure that the feed water can be continuously discharged from the feed pump outlet.

[0173] In practice, the pressure detection device can be a pressure sensor, and the number of pressure sensors is at least two. At least one pressure sensor is arranged at the feed pump outlet, and at least one pressure sensor is arranged at the feed pump inlet.

[0174] Among them, when the second control unit adjusts the feed pump frequency, if the deviation between the feed pump outlet pressure and the feed pump inlet pressure is lower than the preset deviation value, the feed water frequency should be increased, that is, the feed pump outlet pressure should be increased, so that the deviation between the feed pump outlet pressure and the feed pump inlet pressure is maintained at the preset deviation value; if the deviation between the feed pump outlet pressure and the feed pump inlet pressure is higher than the preset deviation value, the feed pump frequency should be decreased, that is, the feed pump outlet pressure should be decreased, so that the deviation between the feed pump outlet pressure and the feed pump inlet pressure is maintained at the preset deviation value.

[0175] The present invention also provides a molten salt steam generation system coupled with a coal-fired unit, including a deaerator 1, a feed pump 2, a regulating valve, a preheater 3, an evaporator 4, a superheater 5, a hot salt tank 6, a hot salt pump 7 and a cold salt tank 8. According to the flow direction of the molten salt, the hot salt tank 6, the hot salt pump 7, the superheater 5, the evaporator 4, the preheater 3 and the cold salt tank 8 are connected in sequence. According to the flow direction of the steam and water, the deaerator 1, the feed pump 2, the regulating valve, the preheater 3, the evaporator 4 and the superheater 5 are connected in sequence. The regulating valve includes a main path regulating valve 9 and a bypass regulating valve 10, and the main path regulating valve 9 and the bypass regulating valve 10 are arranged in parallel;

[0176] It also includes the control device of the molten salt steam generation system coupled with the coal-fired unit as described above. The control device of the molten salt steam generation system coupled with the coal-fired unit is configured to control the opening degrees of the main path regulating valve 9 and the bypass regulating valve 10 so that the measured value of the evaporator water level is equal to the set value of the evaporator water level.

[0177] The molten salt steam generation system of the present invention is coupled to a coal-fired unit, including the control device of the molten salt steam generation system coupled to the coal-fired unit described above. Therefore, it has the same technical effects as the control device of the molten salt steam generation system coupled to the coal-fired unit described above, which will not be elaborated here.

[0178] Meanwhile, according to different feed water flow rates, the molten salt steam generation system of the present invention coupled to a coal-fired unit has two different operating modes: the heat release mode and the heat tracing mode. In the heat tracing mode, the molten salt and the steam-water circuit operate with a small flow rate, and a temperature field similar to that in the heat release mode is established in the system to prepare for quickly responding to the rapid load increase of the unit at any time; when the molten salt steam generation system receives an instruction to assist the unit in increasing the load, the molten salt steam generation system switches from the heat tracing mode to the heat release mode with a large flow rate, significantly improving the load increase rate of the unit.

[0179] The molten salt steam generation system, control method, and control device of the present invention coupled to a coal-fired unit have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A control method for a molten salt steam generation system coupled to a coal-fired unit, characterized in that: The steps include: Obtaining a first opening instruction function f1(x) and a second opening instruction function f2(x), wherein the first opening instruction function f1(x) and the second opening instruction function f2(x) are both broken line functions of changes in the integrated valve position instruction at the outlet of the feedwater pump, and f1(x)≠f2(x); Acquire the integrated valve position instruction of the water supply pump outlet in real time, and obtain the first opening through the first opening instruction function f1(x), and obtain the second opening through the second opening instruction function f2(x); Controlling the opening of a main regulating valve in a molten salt steam generating system to be the first opening, and controlling the opening of a bypass regulating valve in the molten salt steam generating system to be the second opening, so as to adjust the feed water flow of the molten salt steam generating system so that the measured value of the evaporator water level in the molten salt steam generating system is equal to the set value of the evaporator water level; The main regulating valve and the bypass regulating valve are arranged in parallel between the feed water outlet of the feed water pump and the feed water inlet of the evaporator in the molten salt steam generation system.

2. The control method of the molten salt steam generation system coupled with the coal-fired unit according to claim 1, characterized in that: Real-time acquisition of the integrated valve position instruction of the water supply pump outlet specifically includes the following steps: Monitor the evaporator water level and feed water flow of the molten salt steam generation system in real time, obtain the actual measured value of the evaporator water level and the actual measured value of the feed water flow, generate the feed water flow set value according to the deviation between the actual measured value of the evaporator water level and the evaporator water level set value, and generate the first comprehensive valve position instruction of the feed water pump outlet according to the deviation between the actual measured value of the feed water flow and the feed water flow set value; Monitor the steam flow of the molten salt steam generation system in real time, obtain the actual value of the steam flow, and generate a second comprehensive valve position instruction for the outlet of the feedwater pump according to the actual value of the steam flow; Monitor the working status of the coupled coal-fired unit in real time, obtain the actual power of the unit, receive the AGC load instruction, calculate the deviation between the AGC load instruction and the actual power of the unit, and when the deviation between the AGC load instruction and the actual power of the unit is not less than a preset deviation, generate a third comprehensive valve position instruction for the outlet of the feedwater pump according to the deviation between the AGC load instruction and the actual power; The first comprehensive valve position instruction, the second comprehensive valve position instruction and the third comprehensive valve position instruction are superimposed to obtain the water supply pump outlet comprehensive valve position instruction.

3. The control method of the molten salt steam generation system coupled with the coal-fired unit according to claim 1, characterized in that: The following steps are also included: When any one of the first signal and the second signal is valid, a first preset time is delayed to generate a water flow rate locking increase signal to control the opening of the main regulating valve and the bypass regulating valve to no longer increase; When the measured value of the deaerator water level is lower than the deaerator water level low value 1, the first signal is valid; When the actual measured value of the evaporator water level is higher than the evaporator water level high value 1, and the actual measured value of the deaerator water level is not higher than the deaerator water level high value 1, the second signal is valid.

4. The control method of the molten salt steam generation system coupled with the coal-fired unit according to claim 1, characterized in that: The following steps are also included: When any one of the third signal and the fourth signal is valid, a second preset time is delayed to generate a water flow rate locking reduction signal to control the opening of the main regulating valve and the bypass regulating valve to no longer decrease; When the measured value of the deaerator water level is higher than the deaerator water level high value 1, the third signal is valid; When the actual measured value of the evaporator water level is lower than the evaporator water level low value 1, and the actual measured value of the deaerator water level is not lower than the deaerator water level low value 1, the fourth signal is valid.

5. The control method of the molten salt steam generation system coupled with the coal-fired unit according to claim 1, characterized in that: The following steps are also included: Obtain the outlet pressure and the inlet pressure of the water feed pump, generate a water feed pump frequency instruction based on the deviation of the outlet pressure and the inlet pressure of the water feed pump from a preset deviation value, and adjust the water feed pump frequency according to the water feed pump frequency instruction so that the deviation between the outlet pressure and the inlet pressure of the water feed pump is maintained at the preset deviation value.

6. The control method of the molten salt steam generation system coupled with the coal-fired unit according to claim 5, characterized in that: When the deviation between the outlet pressure of the water pump and the inlet pressure of the water pump is lower than the preset deviation value, the frequency of the water pump is increased; when the deviation between the outlet pressure of the water pump and the inlet pressure of the water pump is higher than the preset deviation value, the frequency of the water pump is reduced.

7. A control device for a molten salt steam generating system coupled to a coal-fired unit, applicable to the control method for a molten salt steam generating system coupled to a coal-fired unit according to any one of claims 1 to 6, characterized in that: The invention comprises a molten salt evaporator water level control device, wherein the molten salt evaporator water level control device comprises a communication-connected storage unit, a first calculation unit and a first control unit, wherein: The storage unit stores a first opening instruction function f1(x) and a second opening instruction function f2(x), wherein the first opening instruction function f1(x) and the second opening instruction function f2(x) are both broken line functions of changes in the integrated valve position instruction at the outlet of the feedwater pump, and f1(x)≠f2(x); The first calculation unit is capable of calculating and acquiring the integrated valve position instruction of the water supply pump outlet in real time, and obtaining the first opening degree through the first opening instruction function f1(x), and obtaining the second opening degree through the second opening instruction function f2(x); The first control unit is capable of controlling the opening of the main regulating valve in the molten salt steam generating system to be the first opening, and controlling the opening of the bypass regulating valve in the molten salt steam generating system to be the second opening, so as to adjust the feed water flow of the molten salt steam generating system so that the actual measured value of the evaporator water level in the molten salt steam generating system is equal to the evaporator water level set value.

8. The control device for the molten salt steam generation system coupled with a coal-fired unit according to claim 7, characterized in that: Also includes: An RTU system, wherein the RTU system is communicatively connected with the first computing unit, and the RTU system is capable of acquiring an AGC load instruction in real time and transmitting the AGC load instruction to the computing unit; A DCS system, wherein the DCS system is in communication with the first computing unit, and the RTU system is capable of acquiring the actual power of the unit in real time and transmitting the actual power of the unit to the computing unit; a first water level monitoring device, the first water level monitoring device being communicatively connected to the first computing unit, the first water level monitoring device being capable of acquiring a measured value of the evaporator water level of the molten salt steam generating system in real time, and transmitting the measured value of the evaporator water level to the first computing unit; A flow monitoring device, wherein the flow monitoring device is communicatively connected to the first computing unit, and the flow monitoring device is capable of obtaining a measured feed water flow rate and a measured steam flow rate of the molten salt steam generating system in real time, and transmitting the measured feed water flow rate and the measured steam flow rate to the computing unit; The first calculation unit can calculate and obtain the feedwater pump outlet comprehensive valve position instruction based on the received AGC load instruction, the actual power of the unit, the evaporator water level measured value, the feedwater flow measured value and the steam flow measured value.

9. The control device for a molten salt steam generation system coupled with a coal-fired unit according to claim 8, characterized in that: The storage unit also stores a water level setting value of the evaporator, and the first calculation unit includes: A main controller, wherein the main controller is capable of receiving an evaporator water level measured value and an evaporator water level set value, and calculating and obtaining a water supply flow set value according to a deviation between the evaporator water level measured value and the evaporator water level set value, A sub-controller, the sub-controller is communicatively connected with the main controller, the sub-controller is capable of receiving the water supply flow rate setting value and the water supply flow rate measured value, and calculating and obtaining the first comprehensive valve position instruction of the water supply pump outlet according to the deviation between the water supply flow rate setting value and the water supply flow rate measured value; a first feedforward controller, wherein the first feedforward controller is capable of receiving the actual value of the steam flow rate and calculating and obtaining a second integrated valve position instruction of the feedwater pump outlet according to the actual value of the steam flow rate; a second feedforward controller, the second feedforward controller being capable of receiving the AGC load instruction and the actual power of the unit, and obtaining a third integrated valve position instruction of the feedwater pump outlet according to the deviation between the AGC load instruction and the actual power, on the condition that the deviation between the AGC load instruction and the actual power of the unit is not less than a preset deviation; The adder, the sub-controller, the first feedforward controller and the second feedforward controller are all communicatively connected to the adder, and the adder can superimpose the first comprehensive valve position instruction, the second comprehensive valve position instruction and the third comprehensive valve position instruction to calculate and obtain the water supply pump outlet comprehensive valve position instruction.

10. The control device for a molten salt steam generation system coupled with a coal-fired unit according to claim 8, characterized in that: It also includes a second water level monitoring device, which is communicatively connected to the first computing unit, and the first water level monitoring device can obtain the actual measured value of the deaerator water level of the molten salt steam generating system in real time, and transmit the actual measured value of the deaerator water level to the first computing unit; The first calculation unit further includes a locking increase module, which can receive the measured value of the deaerator water level and the measured value of the evaporator water level, and when any one of the first signal and the second signal is valid, delays the first preset time to generate a water flow locking increase signal; When the measured value of the deaerator water level is lower than the deaerator water level low value 1, the first signal is valid; When the measured value of the evaporator water level is higher than the evaporator water level high value 1, and the measured value of the deaerator water level is not higher than the deaerator water level high value 1, the second signal is valid; When the water supply flow rate locking increase signal is valid, the first control unit controls the opening of the main regulating valve and the bypass regulating valve to no longer increase.

11. The control device for a molten salt steam generation system coupled with a coal-fired unit according to claim 10, characterized in that: The first calculation unit further includes a locking reduction module, which can receive the measured value of the deaerator water level and the measured value of the evaporator water level, and when any one of the third signal and the fourth signal is valid, delays for a second preset time to generate a water flow locking reduction signal; When the measured value of the deaerator water level is higher than the deaerator water level high value 1, the third signal is valid; When the measured value of the evaporator water level is lower than the evaporator water level low value 1, and the measured value of the deaerator water level is not lower than the deaerator water level low value 1, the fourth signal is valid; When the water supply flow rate locking reduction signal is valid, the first control unit controls the opening of the main regulating valve and the bypass regulating valve to no longer decrease.

12. The control device for a molten salt steam generation system coupled with a coal-fired unit according to claim 8, characterized in that: It also includes a pressure detection device, which can obtain the outlet pressure and inlet pressure of the water pump in real time; The molten salt evaporator water level control device further comprises a second calculation unit and a second control unit which are communicatively connected, and the pressure detection device is communicatively connected to the second calculation unit, wherein: The second calculation unit is capable of receiving the outlet pressure of the water feed pump and the inlet pressure of the water feed pump, and calculating and obtaining the frequency instruction of the water feed pump based on the condition that the deviation between the outlet pressure of the water feed pump and the inlet pressure of the water feed pump deviates from the preset deviation value; The second control unit can adjust the feedwater pump frequency of the molten salt steam generation system according to the feedwater pump frequency instruction so that the deviation between the feedwater pump outlet pressure and the feedwater pump inlet pressure is maintained at the preset deviation value.

13. A molten salt steam generating system coupled with a coal-fired unit, characterized in that: It includes a deaerator, a water supply pump, a regulating valve, a preheater, an evaporator, a superheater, a hot salt tank, a hot salt pump and a cold salt tank. According to the flow direction of the molten salt, the hot salt tank, the hot salt pump, the superheater, the evaporator, the preheater and the cold salt tank are connected in sequence. According to the flow direction of the steam and water, the deaerator, the water supply pump, the regulating valve, the preheater, the evaporator and the superheater are connected in sequence. The regulating valve includes a main regulating valve and a bypass regulating valve. The main regulating valve and the bypass regulating valve are arranged in parallel. It also includes the control device of the molten salt steam generating system coupled to the coal-fired unit as described in any one of claims 7 to 12, wherein the control device of the molten salt steam generating system coupled to the coal-fired unit is configured to control the opening of the main regulating valve and the bypass regulating valve so that the actual measured value of the evaporator water level is equal to the set value of the evaporator water level.

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