Heat supply and power generation system coupled with molten salt heat storage and capable of improving thermoelectricity load flexibility and operation method

Abstract

The invention discloses a heat supply and power generation system coupled with molten salt heat storage to improve the flexibility of a thermoelectric load and an operation method. The heat supply and power generation system comprises a multi-source heat source module, a molten salt heat storage and release module, a steam power generation module, a graded heat supply module, a multi-medium heat exchange module and an intelligent regulation and control module. The multi-source heat source module comprises a pulverized coal boiler of a main heat source unit and a solar trough heat collector array and a biomass circulating fluidized bed boiler of an auxiliary heat source unit; the molten salt heat storage and release module comprises a high-temperature heat storage tank, a low-temperature heat storage tank, a molten salt circulating pump, a molten salt make-up pump, a molten salt heater and a molten salt cooler. Through the collaborative design of the multi-source heat source module, the molten salt heat storage and release module, the steam power generation module, the graded heat supply module, the multi-medium heat exchange module and the intelligent regulation and control module, the thermoelectric coupling rigidity is broken through, and the load regulation flexibility is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of power generation system technology, specifically relating to a heating and power generation system and its operation method that couples molten salt thermal storage to improve the flexibility of thermoelectric load. Background Technology

[0002] Currently, combined heat and power (CHP) systems, as an important form of energy utilization that combines power generation and heating, are widely used in urban district heating, industrial park energy supply, and other scenarios. Traditional CHP systems mostly use pulverized coal boilers as the single main heat source, relying on a rigid operating mode of "heat-driven power generation" or "electricity-driven heat generation," which has the following significant limitations: rigid coupling of heat and power loads and poor adjustment flexibility: In traditional systems, the power generation load is directly related to the heating load: During the winter heating peak, in order to meet the heating demand, the boiler must be kept at a high load, making it difficult for the power generation load to be reduced with the grid's off-peak demand; in the summer or during the heating off-peak, the increase in power generation load is limited by insufficient heating demand, resulting in "heat and power interlock"—for example, in a 300MW pulverized coal boiler CHP system, when the heating load decreases by 30%, the power generation load can only be reduced to a minimum of 60% of the rated value, which cannot match the grid's deep peak shaving requirements (in some scenarios, it needs to be reduced to below 40%).

[0003] Low efficiency of multi-heat source coordination and difficulty in renewable energy consumption: Although existing systems occasionally introduce auxiliary heat sources such as solar energy and biomass, they are mostly in a "simple parallel" mode: solar collectors are greatly affected by light fluctuations and lack stable heat storage devices, so excess heat cannot be effectively stored; biomass boilers have slow start-up and shutdown response (usually 2-4 hours), making it difficult to quickly replenish energy, resulting in auxiliary heat sources only participating sporadically under specific operating conditions and failing to form dynamic coordination with the main heat source (pulverized coal boiler). Data shows that the utilization rate of solar energy in traditional multi-heat source systems is less than 40%, and the annual operating time of biomass heat sources is only 30% of that of pulverized coal boilers.

[0004] Thermal storage technology has poor adaptability and weak ability to cope with load fluctuations: Some cogeneration systems use water thermal storage or sensible thermal storage tanks, but water thermal storage has low temperature (usually ≤100℃) and low thermal density (about 0.4MJ / kg), which cannot meet the needs of high-temperature heating and power generation supplementation; existing molten salt thermal storage is mostly used alone for solar thermal power generation and is not deeply coupled with cogeneration systems - for example, only heating feedwater by molten salt is involved without heating load regulation, resulting in the utilization rate of thermal storage devices being less than 20% when the thermal power load fluctuates, and failing to play the role of "load buffer".

[0005] Low level of intelligence and slow response to switching of operating conditions: Traditional systems rely on manual adjustment of valves, pump sets and boiler burners, with low parameter acquisition frequency (usually 5-10Hz), and load forecasting is based only on short-term data (4-8h). When there are sudden changes in the power grid or heating load (such as peak electricity consumption in the morning and evening, or a sudden increase in heating demand during extreme weather), the system's operating condition switching response time can be as long as 30-60 minutes, which can easily lead to fluctuations in heating temperature (above ±5℃) or deviations in power generation (≥5% of rated power), affecting the stability of energy supply.

[0006] The safety protection system is inadequate, and the risks under special operating conditions are high: Molten salt thermal storage tanks are prone to overheating, overpressure, or low liquid level problems when operating at high temperatures (350-400℃) and high liquid levels. The existing system lacks a targeted multi-level protection mechanism. When the load drops suddenly, steam pipelines and heating pipelines are prone to failures such as pipeline rupture and freezing due to sudden pressure rises or temperature drops. For example, when the power generation load drops from full load to 40%, the pressure fluctuation of steam pipelines can reach 2-3 MPa. Failure to release pressure in time will lead to pipeline safety risks.

[0007] In summary, existing combined heat and power (CHP) systems suffer from rigid thermoelectric coupling, insufficient multi-heat source coordination, poor thermal storage adaptability, low intelligence, and lack of safety protection, making it difficult to meet the dual demands of deep grid peak shaving and stable heating for users. There is an urgent need for a new type of CHP system and operating method that can achieve flexible adjustment of CHP load, efficient coordination of multiple heat sources, and safe and stable operation. Summary of the Invention

[0008] The purpose of this invention is to provide a heating and power generation system and its operation method that couples molten salt thermal storage to improve the flexibility of thermoelectric load, so as to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a heat and power generation system that couples molten salt thermal storage to improve the flexibility of thermoelectric load, comprising: The system includes a multi-source heat source module, a molten salt thermal storage and release module, a steam power generation module, a tiered heating module, a multi-media heat exchange module, and an intelligent control module. The multi-source heat source module includes a pulverized coal boiler as the main heat source unit and a solar trough collector array and a biomass circulating fluidized bed boiler as auxiliary heat source units. The molten salt thermal storage and release module includes a high-temperature storage tank, a low-temperature storage tank, a molten salt circulating pump, a molten salt makeup water pump, a molten salt heater, and a molten salt cooler. The steam power generation module includes a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a feed water pump, a high-pressure heater, and a low-pressure heater. The tiered heating module includes a primary heat network heater, a secondary heat network heater, a heat network circulating pump, and multiple sets of user-side heat exchangers. The multi-media heat exchange module includes a steam-molten salt heat exchanger, a molten salt water heat exchanger, and a steam-water heat exchanger. The intelligent control module includes a central controller, a load prediction unit, a parameter acquisition unit, and an execution unit.

[0010] The steam outlet of the pulverized coal boiler is connected to the inlet of the high-pressure cylinder via a main steam pipeline; the molten salt outlet of the solar trough collector is connected to the inlet of the high-temperature thermal storage tank via a first molten salt pipeline; and the steam outlet of the biomass boiler is connected to the inlet of the steam-molten salt heat exchanger via an auxiliary steam pipeline. The outlet of the high-temperature thermal storage tank is connected to the inlet of the molten salt circulation pump via a second molten salt pipeline, and the outlet of the molten salt circulation pump is branched to connect the inlet of the molten salt heat exchanger and the inlet of the molten salt cooler. The outlet of the high-pressure cylinder is connected to the inlet of the medium-pressure cylinder, and the outlet of the medium-pressure cylinder is branched to connect the inlet of the low-pressure cylinder and the inlet of the steam-water heat exchanger. The inlet of the primary thermal grid heater is connected to the outlet of the molten salt heat exchanger, the outlet of the primary thermal grid heater is connected to the inlet of the secondary thermal grid heater, the outlet of the secondary thermal grid heater is connected to the inlet of the thermal grid circulation pump, and the outlet of the thermal grid circulation pump is branched to connect to the inlet of the user-side heat exchanger. The central controller is connected to the load prediction unit, parameter acquisition unit, and execution unit via an industrial Ethernet network.

[0011] Preferably, in the multi-source heat source module, the rated evaporation capacity of the pulverized coal boiler is not less than 1025 t / h; the light-collecting area of ​​the solar trough collector array is not less than 5000 m², and the outlet molten salt temperature is not less than 380℃.

[0012] Preferably, in the molten salt heat storage and heat release module, the molten salt heater adopts a shell-and-tube structure, and the molten salt cooler adopts a plate structure; the high-temperature heat storage tank and the low-temperature heat storage tank are equipped with temperature sensors, liquid level sensors and pressure sensors.

[0013] Preferably, the molten salt in the molten salt heat storage and release module is a sodium nitrate-potassium nitrate mixed salt, wherein sodium nitrate accounts for 60% by mass and potassium nitrate accounts for 40% by mass.

[0014] Preferably, in the steam power generation module, there are 3 high-pressure heaters arranged in series, with heat exchange areas controlled at 1200㎡, 1000㎡, and 800㎡; there are 4 low-pressure heaters arranged in series, with heat exchange areas controlled at 600㎡, 500㎡, 400㎡, and 300㎡; an electric regulating valve is installed on the steam extraction pipeline from the intermediate-pressure cylinder to the steam-water heat exchanger; and speed sensors are installed in the high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder.

[0015] Preferably, in the graded heating module, the primary heat exchanger heater adopts a shell-and-tube structure with an outlet hot water temperature set at 120°C, and the secondary heat exchanger heater adopts a shell-and-tube structure with an outlet hot water temperature set at 80°C; a temperature control valve is provided on the heat source inlet pipe of the secondary heat exchanger heater; both the primary and secondary heat exchanger heaters are equipped with an outlet temperature sensor and a pressure sensor.

[0016] Preferably, in the intelligent control module, the parameter acquisition unit has a sampling frequency of 1Hz, and the acquired parameters include the temperature, pressure, flow rate, and liquid level of each module; the execution unit includes the drive components of electric valves, pump sets, and boiler burners; and the central controller has a built-in PID regulation algorithm and operating condition switching logic.

[0017] Preferably, it also includes a safety protection unit, which includes: an over-temperature protection subunit, an over-pressure protection subunit, and a low-level protection subunit for the molten salt thermal storage tank; an over-pressure protection subunit for the steam pipeline; and a low-temperature protection subunit for the heating pipeline.

[0018] This invention also discloses an operation method for improving the flexibility of thermoelectric load by coupling molten salt thermal storage, comprising the following steps: Step 1, Load Forecasting and Operating Condition Determination: The intelligent control module acquires data on the power grid generation load and user heating load for the next 24 hours. Based on the matching relationship between the two, it determines whether the system enters one of the following four operating conditions. Step 2, Operating Condition A: Thermal and Power Load Balancing Control Multiple heat sources: pulverized coal boilers operate at full load, biomass boilers are shut down, and solar collectors adjust their output according to sunlight to heat molten salt to 380°C and store it in a high-temperature tank. Heat storage and release: The liquid level in the high-temperature tank is maintained at 6-8m, and the molten salt circulation pump operates at 50% of the rated flow rate to supply energy to the primary heat network heater; Steam power generation: High / medium / low pressure cylinders operate at full load, and 30% of the rated steam is extracted from the medium pressure cylinder to heat the feedwater; Tiered heating: Level 1 heating network outlet temperature is 120℃, Level 2 is 80℃, and the heating network circulation pump delivers heat at full load; Step 3: Operating Condition B: Power Generation Load Reduction - Heating Supply Unchanged Operation Control: Multiple heat sources: pulverized coal boilers reduce load to 40%-60%, biomass boilers start up, and steam heats molten salt; solar collectors supplement heat at full load; Heat storage and release: The frequency of the molten salt circulation pump is increased to 80%-100% flow rate to ensure the energy supply of the primary heating network; when the liquid level in the high-temperature tank is ≥8m, the cooler is started to control the temperature; Steam power generation: the high-pressure cylinder reduces the load, the intermediate-pressure cylinder reduces steam extraction to 10%-20%, and the low-pressure cylinder increases steam extraction to 40%-50% for heat replenishment; Tiered heating: The temperature control valve of the secondary heating network is opened at 60%-80% to maintain the outlet temperature at 80℃; Step 4: Operating Condition C: Heating load reduction - power generation unchanged operation control: Multiple heat sources: pulverized coal boilers are at full load, biomass boilers are shut down, solar collectors heat molten salt and store it in high-temperature tanks, and shut down when the liquid level is ≥9m; Heat storage and release: The frequency of the molten salt circulation pump is reduced to 20%-40% of the flow rate; the molten salt heater is started to heat the salt to 350℃ and supplement steam to the intermediate pressure cylinder; Steam power generation: Increase the steam intake of the intermediate-pressure cylinder by 10%-15% to stabilize power generation, and reduce the steam extraction of the low-pressure cylinder to 5%-10%; Tiered heating: The inlet valve of the primary heating network is opened at 30%-50%, and the thermostatic valve of the secondary heating network is opened at 20%-30%, to match low heating demand; Step 5: Operating Condition D: Extreme Low Load Operation Control Multiple heat sources: Pulverized coal boilers reduce load to below 40%, and biomass boilers use molten salt heaters to supply steam at 30% load; Heat storage and release: The molten salt circulation pump is shut down, the high / low temperature tanks are isolated, and the salt temperature is maintained at 290-400℃; Steam power generation: Each cylinder is reduced to the lowest stable load, and the condenser vacuum is increased to 96%-97% to reduce losses; Tiered heating: 10 sets of user heat exchangers are shut down in rotation according to their respective areas to ensure heating in the core areas.

[0019] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention, through the collaborative design of multi-source heat source modules, molten salt thermal storage and heat release modules, steam power generation modules, staged heating modules, multi-medium heat exchange modules, and intelligent control modules, achieves breakthroughs in the rigidity of thermoelectric coupling and significantly improves load regulation flexibility; this invention can achieve a substantial increase in heat source synergy efficiency and a significant increase in renewable energy absorption rate; this invention can optimize the coupling of molten salt thermal storage, enhancing the ability to cope with load fluctuations; this invention can improve the level of intelligence, increasing operational stability and accuracy; this invention, through multi-module collaboration and intelligent control, achieves flexible adjustment of thermoelectric load, efficient utilization of multiple heat sources, and safe and stable system operation, and can be widely applied to scenarios such as urban centralized heating and industrial park thermoelectric supply, combining economic, environmental, and safety benefits. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the steps of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 This invention provides a technical solution: a heating and power generation system that couples molten salt thermal storage to improve the flexibility of thermoelectric load, comprising: It includes a multi-source heat source module, a molten salt thermal storage and release module, a steam power generation module, a tiered heating module, a multi-media heat exchange module, and an intelligent control module. The multi-source heat source module includes a pulverized coal boiler as the main heat source unit and a solar trough collector array and a biomass circulating fluidized bed boiler as auxiliary heat source units. The molten salt thermal storage and release module includes a high-temperature thermal storage tank, a low-temperature thermal storage tank, a molten salt circulating pump, a molten salt makeup water pump, a molten salt heater, and a molten salt cooler. The steam power generation module includes a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a feed water pump, a high-pressure heater, and a low-pressure heater. The tiered heating module includes a primary heat network heater, a secondary heat network heater, a heat network circulating pump, and multiple sets of user-side heat exchangers. The multi-media heat exchange module includes a steam-molten salt heat exchanger, a molten salt water heat exchanger, and a steam-water heat exchanger. The intelligent control module includes a central controller, a load prediction unit, a parameter acquisition unit, and an execution unit. The steam outlet of the pulverized coal boiler is connected to the inlet of the high-pressure cylinder via the main steam pipeline; the molten salt outlet of the solar trough collector is connected to the inlet of the high-temperature thermal storage tank via the first molten salt pipeline; the steam outlet of the biomass boiler is connected to the inlet of the steam-molten salt heat exchanger via the auxiliary steam pipeline; the outlet of the high-temperature thermal storage tank is connected to the inlet of the molten salt circulation pump via the second molten salt pipeline, and the outlet of the molten salt circulation pump is branched to connect the inlet of the molten salt heat exchanger and the inlet of the molten salt cooler; the outlet of the high-pressure cylinder is connected to the inlet of the medium-pressure cylinder, and the outlet of the medium-pressure cylinder is branched to connect the inlet of the low-pressure cylinder and the inlet of the steam-water heat exchanger; the inlet of the primary heating network heater is connected to the outlet of the molten salt heat exchanger, the outlet of the primary heating network heater is connected to the inlet of the secondary heating network heater, the outlet of the secondary heating network heater is connected to the inlet of the heating network circulation pump, and the outlet of the heating network circulation pump is branched to connect to the inlet of the user-side heat exchanger; the central controller is connected to the load forecasting unit, parameter acquisition unit, and execution unit via industrial Ethernet.

[0023] Among them, in the multi-source heat source module, the rated evaporation capacity of the pulverized coal boiler is not less than 1025t / h; the light-collecting area of ​​the solar trough collector array is not less than 5000㎡, and the outlet molten salt temperature is not less than 380℃.

[0024] In the molten salt heat storage and heat release module, the molten salt heater adopts a shell-and-tube structure, and the molten salt cooler adopts a plate structure; the high-temperature heat storage tank and the low-temperature heat storage tank are equipped with temperature sensors, liquid level sensors and pressure sensors.

[0025] The molten salt in the molten salt heat storage and release module is a sodium nitrate-potassium nitrate mixed salt, with sodium nitrate accounting for 60% by mass and potassium nitrate accounting for 40% by mass.

[0026] In the steam power generation module, there are 3 high-pressure heaters arranged in series, with heat exchange areas of 1200㎡, 1000㎡, and 800㎡ respectively; there are 4 low-pressure heaters arranged in series, with heat exchange areas of 600㎡, 500㎡, 400㎡, and 300㎡ respectively; an electric regulating valve is installed on the extraction pipe from the intermediate-pressure cylinder to the steam-water heat exchanger; and speed sensors are installed in the high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder.

[0027] In the tiered heating module, the primary heating network heater adopts a shell-and-tube structure with an outlet hot water temperature of 120℃, while the secondary heating network heater adopts a shell-and-tube structure with an outlet hot water temperature of 80℃. A temperature control valve is installed on the heat source inlet pipe of the secondary heating network heater. Both the primary and secondary heating network heaters are equipped with outlet temperature and pressure sensors.

[0028] Among them, the intelligent control module has a parameter acquisition unit with a sampling frequency of 1Hz, and the acquired parameters include the temperature, pressure, flow rate, and liquid level of each module; the execution unit includes the drive components of electric valves, pump sets, and boiler burners; the central controller has a built-in PID regulation algorithm and operating condition switching logic.

[0029] It also includes safety protection units, which include: over-temperature protection subunit, over-pressure protection subunit, and low liquid level protection subunit for molten salt thermal storage tanks; over-pressure protection subunit for steam pipelines; and low-temperature protection subunit for heating pipelines.

[0030] This embodiment provides an operation method for improving the flexibility of thermoelectric load by coupling molten salt thermal storage, including the following steps: Step 1, Load Forecasting and Operating Condition Determination: The intelligent control module acquires data on the power grid generation load and user heating load for the next 24 hours. Based on the matching relationship between the two, it determines whether the system enters one of the following four operating conditions. Step 2, Operating Condition A: Thermal and Power Load Balancing Control Multiple heat sources: pulverized coal boilers operate at full load, biomass boilers are shut down, and solar collectors adjust their output according to sunlight to heat molten salt to 380°C and store it in a high-temperature tank. Heat storage and release: The liquid level in the high-temperature tank is maintained at 6-8m, and the molten salt circulation pump operates at 50% of the rated flow rate to supply energy to the primary heat network heater; Steam power generation: High / medium / low pressure cylinders operate at full load, and 30% of the rated steam is extracted from the medium pressure cylinder to heat the feedwater; Tiered heating: Level 1 heating network outlet temperature is 120℃, Level 2 is 80℃, and the heating network circulation pump delivers heat at full load; Step 3: Operating Condition B: Power Generation Load Reduction - Heating Supply Unchanged Operation Control: Multiple heat sources: pulverized coal boilers reduce load to 40%-60%, biomass boilers start up, and steam heats molten salt; solar collectors supplement heat at full load; Heat storage and release: The frequency of the molten salt circulation pump is increased to 80%-100% flow rate to ensure the energy supply of the primary heating network; when the liquid level in the high-temperature tank is ≥8m, the cooler is started to control the temperature; Steam power generation: the high-pressure cylinder reduces the load, the intermediate-pressure cylinder reduces steam extraction to 10%-20%, and the low-pressure cylinder increases steam extraction to 40%-50% for heat replenishment; Tiered heating: The temperature control valve of the secondary heating network is opened at 60%-80% to maintain the outlet temperature at 80℃; Step 4: Operating Condition C: Heating load reduction - power generation unchanged operation control: Multiple heat sources: pulverized coal boilers are at full load, biomass boilers are shut down, solar collectors heat molten salt and store it in high-temperature tanks, and shut down when the liquid level is ≥9m; Heat storage and release: The frequency of the molten salt circulation pump is reduced to 20%-40% of the flow rate; the molten salt heater is started to heat the salt to 350℃ and supplement steam to the intermediate pressure cylinder; Steam power generation: Increase the steam intake of the intermediate-pressure cylinder by 10%-15% to stabilize power generation, and reduce the steam extraction of the low-pressure cylinder to 5%-10%; Tiered heating: The inlet valve of the primary heating network is opened at 30%-50%, and the thermostatic valve of the secondary heating network is opened at 20%-30%, to match low heating demand; Step 5: Operating Condition D: Extreme Low Load Operation Control Multiple heat sources: Pulverized coal boilers reduce load to below 40%, and biomass boilers use molten salt heaters to supply steam at 30% load; Heat storage and release: The molten salt circulation pump is shut down, the high / low temperature tanks are isolated, and the salt temperature is maintained at 290-400℃; Steam power generation: Each cylinder is reduced to the lowest stable load, and the condenser vacuum is increased to 96%-97% to reduce losses; Tiered heating: 10 sets of user heat exchangers are shut down in rotation according to their respective areas to ensure heating in the core areas.

[0031] This invention effectively solves the above-mentioned technical problems and achieves the following technical effects through the collaborative design of "multi-source heat source module + molten salt thermal storage and release module + steam power generation module + staged heating module + multi-media heat exchange module + intelligent control module" and a dynamic operation method for four types of working conditions: This invention overcomes the rigidity of thermoelectric coupling, significantly improving load regulation flexibility. For the "power generation load reduction - heating unchanged" condition (Condition B): by reducing the load of the pulverized coal boiler (40%-60%), supplementing energy with a biomass boiler, and increasing the frequency of the molten salt circulating pump (80%-100% flow rate), it is possible to reduce the power generation load by 40% while maintaining a primary heating network outlet temperature of 120℃ and a secondary outlet temperature of 80℃, with heating temperature fluctuations ≤ ±1.5℃, meeting the deep peak-shaving requirements of the power grid. For the "heating load reduction - power generation unchanged" condition (Condition C): by reducing the frequency of the molten salt circulating pump (20%-40% flow rate) and increasing the frequency of the molten salt circulating pump... By supplementing steam to the intermediate-pressure cylinder with salt heaters (increasing steam intake by 10%-15%), the rated power of the generator (550MW) can be maintained while the heating load is reduced by 50%, with a power generation deviation of ≤2%. In low-load conditions (condition D), when the pulverized coal boiler is reduced to below 40% load, the minimum stable operating load of the system (220MW of power generation and 30% of the rated heating load) can be achieved through the rotational shutdown of user heat exchangers and the increase of condenser vacuum (96%-97%), which expands the peak-shaving range by 50% compared with the traditional system (minimum 40% of power generation load).

[0032] This invention significantly improves the efficiency of multi-heat source synergy and substantially increases the renewable energy absorption rate. Solar energy utilization: Molten salt is heated to 380°C and stored using a solar trough collector (5000㎡ light-collecting area). Combined with intelligent control module-based light prediction, the solar energy utilization rate is increased to over 75%, resulting in an increase in annual power generation of approximately 2.3 × 10⁻⁶. 6 kWh; Biomass co-operation: Biomass boilers (linked with pulverized coal boilers) can start and stop rapidly in operating conditions B and D (response time ≤ 1.5 hours), increasing annual operating time to 65% of pulverized coal boilers and reducing annual pulverized coal consumption by approximately 1.2 × 10 kWh; 4 This translates to a reduction of approximately 3.1 × 10⁻⁶ tons of carbon emissions. 4 ton.

[0033] This invention optimizes the coupling of molten salt thermal storage, enhancing its ability to cope with load fluctuations. Thermal storage utilization rate: The molten salt thermal storage module enables bidirectional switching between "heat supply and energy replenishment" and "power generation and energy replenishment," increasing the thermal storage utilization rate to over 68% in four operating conditions, more than three times higher than traditional single-purpose molten salt thermal storage (utilization rate ≤20%). Response speed: The molten salt circulation pump and valves are rapidly adjusted via an actuator (electrically driven), with a thermal storage / heat release switching response time of ≤8 minutes during load fluctuations, seven times faster than traditional manual adjustment (30-60 minutes). This invention also improves the level of intelligence, enhancing operational stability and accuracy.

[0034] This invention achieves flexible adjustment of thermal and electrical loads, efficient utilization of multiple heat sources, and safe and stable operation of the system through multi-module collaboration and intelligent control. It can be widely applied to scenarios such as urban centralized heating and industrial park thermal and electrical supply, and has economic, environmental and safety benefits.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A heat and power generation system with coupled molten salt thermal storage to improve the flexibility of thermoelectric load, characterized in that, include: The system includes a multi-source heat source module, a molten salt thermal storage and release module, a steam power generation module, a tiered heating module, a multi-media heat exchange module, and an intelligent control module. The multi-source heat source module includes a pulverized coal boiler as the main heat source unit and a solar trough collector array and a biomass circulating fluidized bed boiler as auxiliary heat source units. The molten salt thermal storage and release module includes a high-temperature storage tank, a low-temperature storage tank, a molten salt circulating pump, a molten salt makeup water pump, a molten salt heater, and a molten salt cooler. The steam power generation module includes a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a feed water pump, a high-pressure heater, and a low-pressure heater. The tiered heating module includes a primary heat network heater, a secondary heat network heater, a heat network circulating pump, and multiple sets of user-side heat exchangers. The multi-media heat exchange module includes a steam-molten salt heat exchanger, a molten salt water heat exchanger, and a steam-water heat exchanger. The intelligent control module includes a central controller, a load prediction unit, a parameter acquisition unit, and an execution unit. The steam outlet of the pulverized coal boiler is connected to the inlet of the high-pressure cylinder via a main steam pipeline; the molten salt outlet of the solar trough collector is connected to the inlet of the high-temperature thermal storage tank via a first molten salt pipeline; and the steam outlet of the biomass boiler is connected to the inlet of the steam-molten salt heat exchanger via an auxiliary steam pipeline. The outlet of the high-temperature thermal storage tank is connected to the inlet of the molten salt circulation pump via a second molten salt pipeline, and the outlet of the molten salt circulation pump is branched to connect the inlet of the molten salt heat exchanger and the inlet of the molten salt cooler. The outlet of the high-pressure cylinder is connected to the inlet of the medium-pressure cylinder, and the outlet of the medium-pressure cylinder is branched to connect the inlet of the low-pressure cylinder and the inlet of the steam-water heat exchanger. The inlet of the primary thermal grid heater is connected to the outlet of the molten salt heat exchanger, the outlet of the primary thermal grid heater is connected to the inlet of the secondary thermal grid heater, the outlet of the secondary thermal grid heater is connected to the inlet of the thermal grid circulation pump, and the outlet of the thermal grid circulation pump is branched to connect to the inlet of the user-side heat exchanger. The central controller is connected to the load prediction unit, parameter acquisition unit, and execution unit via an industrial Ethernet network.

2. The heating and power generation system according to claim 1, which enhances the flexibility of thermoelectric load by coupling molten salt thermal storage, is characterized in that: In the multi-source heat source module, the rated evaporation capacity of the pulverized coal boiler is not less than 1025 t / h; the light-collecting area of ​​the solar trough collector array is not less than 5000 m², and the outlet molten salt temperature is not less than 380℃.

3. The heating and power generation system according to claim 1, which enhances the flexibility of thermoelectric load by coupling molten salt thermal storage, is characterized in that: In the molten salt heat storage and heat release module, the molten salt heater adopts a shell-and-tube structure, and the molten salt cooler adopts a plate structure; the high-temperature heat storage tank and the low-temperature heat storage tank are equipped with temperature sensors, liquid level sensors and pressure sensors.

4. A heating and power generation system for improving the flexibility of thermoelectric load by coupling molten salt thermal storage according to claim 1, characterized in that: The molten salt in the molten salt heat storage and release module is a sodium nitrate-potassium nitrate mixed salt, wherein sodium nitrate accounts for 60% by mass and potassium nitrate accounts for 40% by mass.

5. A heating and power generation system for improving the flexibility of thermoelectric load by coupling molten salt thermal storage according to claim 1, characterized in that: In the steam power generation module, there are 3 high-pressure heaters arranged in series, with heat exchange areas controlled at 1200㎡, 1000㎡, and 800㎡ respectively; there are 4 low-pressure heaters arranged in series, with heat exchange areas controlled at 600㎡, 500㎡, 400㎡, and 300㎡ respectively; an electric regulating valve is installed on the steam extraction pipeline from the intermediate-pressure cylinder to the steam-water heat exchanger; and speed sensors are installed in the high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder.

6. A heating and power generation system for improving the flexibility of thermoelectric load by coupling molten salt thermal storage according to claim 5, characterized in that: In the graded heating module, the primary heat exchanger heater adopts a shell-and-tube structure with an outlet hot water temperature of 120°C, and the secondary heat exchanger heater adopts a shell-and-tube structure with an outlet hot water temperature of 80°C. A temperature control valve is installed on the heat source inlet pipe of the secondary heat exchanger heater. Both the primary and secondary heat exchanger heaters are equipped with an outlet temperature sensor and a pressure sensor.

7. A heating and power generation system for improving the flexibility of thermoelectric load by coupling molten salt thermal storage according to claim 1, characterized in that: In the intelligent control module, the parameter acquisition unit has a sampling frequency of 1Hz, and the acquired parameters include the temperature, pressure, flow rate, and liquid level of each module; the execution unit includes the drive components of electric valves, pump sets, and boiler burners; the central controller has a built-in PID regulation algorithm and operating condition switching logic.

8. A heating and power generation system for improving the flexibility of thermoelectric load by coupling molten salt thermal storage according to claim 1, characterized in that: It also includes safety protection units, which include: an over-temperature protection subunit, an over-pressure protection subunit, and a low-level protection subunit for molten salt thermal storage tanks; an over-pressure protection subunit for steam pipelines; and a low-temperature protection subunit for heating pipelines.

9. The operation method for improving the flexibility of thermoelectric load by coupling molten salt thermal storage according to claim 1, characterized in that: Includes the following steps: Step 1, Load Forecasting and Operating Condition Determination: The intelligent control module acquires data on the power grid generation load and user heating load for the next 24 hours. Based on the matching relationship between the two, it determines whether the system enters one of the following four operating conditions. Step 2, Operating Condition A: Thermal and Power Load Balancing Control Multiple heat sources: pulverized coal boilers operate at full load, biomass boilers are shut down, and solar collectors adjust their output according to sunlight to heat molten salt to 380°C and store it in a high-temperature tank. Heat storage and release: The liquid level in the high-temperature tank is maintained at 6-8m, and the molten salt circulation pump operates at 50% of the rated flow rate to supply energy to the primary heat network heater; Steam power generation: High / medium / low pressure cylinders operate at full load, and 30% of the rated steam is extracted from the medium pressure cylinder to heat the feedwater; Tiered heating: Level 1 heating network outlet temperature is 120℃, Level 2 is 80℃, and the heating network circulation pump delivers heat at full load; Step 3: Operating Condition B: Power Generation Load Reduction - Heating Supply Unchanged Operation Control: Multiple heat sources: pulverized coal boilers reduce load to 40%-60%, biomass boilers start up, and steam heats molten salt; solar collectors supplement heat at full load; Heat storage and release: The molten salt circulation pump is increased to 80%-100% flow rate to ensure the energy supply of the primary heating network; when the liquid level in the high-temperature tank is ≥8m, the cooler is started to control the temperature; Steam power generation: the high-pressure cylinder reduces the load, the intermediate-pressure cylinder reduces steam extraction to 10%-20%, and the low-pressure cylinder increases steam extraction to 40%-50% for heat replenishment; Tiered heating: The temperature control valve of the secondary heating network is opened at 60%-80% to maintain the outlet temperature at 80℃; Step 4: Operating Condition C: Heating load reduction - power generation unchanged operation control: Multiple heat sources: pulverized coal boilers are at full load, biomass boilers are shut down, solar collectors heat molten salt and store it in high-temperature tanks, and shut down when the liquid level is ≥9m; Heat storage and release: The frequency of the molten salt circulation pump is reduced to 20%-40% of the flow rate; The molten salt heater is started, heating the salt to 350°C and supplying steam to the intermediate pressure cylinder; Steam power generation: Increase the steam intake of the intermediate-pressure cylinder by 10%-15% to stabilize power generation, and reduce the steam extraction of the low-pressure cylinder to 5%-10%; Tiered heating: The inlet valve of the primary heating network is opened at 30%-50%, and the thermostatic valve of the secondary heating network is opened at 20%-30%, to match low heating demand; Step 5: Operating Condition D: Extreme Low Load Operation Control Multiple heat sources: Pulverized coal boilers reduce load to below 40%, and biomass boilers use molten salt heaters to supply steam at 30% load; Heat storage and release: The molten salt circulation pump is shut down, the high / low temperature tanks are isolated, and the salt temperature is maintained at 290-400℃; Steam power generation: Each cylinder is reduced to the lowest stable load, and the condenser vacuum is increased to 96%-97% to reduce losses; Tiered heating: 10 sets of user heat exchangers are shut down in rotation according to their respective areas to ensure heating in the core areas.

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