A steam generating device and method based on coal gas combustion and molten salt heat storage

Abstract

The application discloses a steam generating device and method based on coal gas combustion and fused salt heat storage, and relates to the technical field of energy utilization and power engineering, and comprises the following steps: S1, a fused salt heat storage, coal gas combustion heating and steam generation subsystem is arranged; S2, the power grid load is monitored, and energy storage or energy release working conditions are determined and switched; S3, in the energy storage working condition, coal gas is combusted to heat low-temperature fused salt, and the low-temperature fused salt is converted into high-temperature fused salt and stored in a hot salt tank; and S4, in the energy release working condition, the high-temperature fused salt enters a heat exchanger to heat feed water to generate steam, and the steam is merged into a steam turbine generator set to generate power. The application significantly improves the adaptability of the unit to power grid load changes and the peak shaving flexibility.

Description

Technical Field

[0001] This invention relates to the field of energy utilization and power engineering technology, specifically to a steam generation device and method based on coal gas combustion and molten salt thermal storage. Background Technology

[0002] In the current industrial power generation sector, the operating status of conventional gas generator units is closely related to the real-time demand of the power grid load. In order to ensure the stability of power supply, the units need to adapt to the load requirements that fluctuate significantly at different times. However, in actual production, there is often a structural contradiction of surplus gas during off-peak hours and insufficient output during peak hours. This supply-demand mismatch not only leads to energy waste but also limits the peak-shaving capacity of the units. Traditional operating modes often lack energy transfer mechanisms over time and are highly susceptible to fluctuations in industrial production of gas sources, resulting in unstable fuel supply pressure and consequently, drastic fluctuations in steam production. These factors combined make it difficult for generator units to maintain efficient and stable operation under variable external conditions. While existing technologies offer adjustment schemes for combustion systems, these methods generally suffer from insufficient quantification of energy balance relationships and reliance on empirical values ​​for adjustment. Traditional control strategies often struggle to accurately perceive the dynamic deviation between the unit's internal energy state and external dispatch demands, resulting in significant lag in the system's response to grid load commands or sudden changes in gas source pressure, making it impossible to achieve precise matching of energy supply and demand. Furthermore, existing technologies often neglect the real-time impact of environmental heat exchange temperature differences or pipeline pressure drops on system thermal energy, lacking dynamic compensation mechanisms and feedforward control strategies based on real-time parameter calculations. This makes it difficult to offset thermal energy attenuation caused by environmental disturbances, thus failing to guarantee the quality and stability of steam produced under peak loads or extreme operating conditions.

[0003] Therefore, how to provide a steam generation method based on gas combustion and molten salt thermal storage that can alleviate the mismatch between gas supply and grid demand and has high-precision dynamic response capability is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a steam generation device and method based on coal gas combustion and molten salt thermal storage, so as to solve the problems mentioned in the background art; specifically, the technical solution of this invention is as follows:

[0005] A steam generation method based on coal gas combustion and molten salt thermal storage includes:

[0006] S1. A molten salt thermal storage subsystem, a gas combustion and molten salt heating subsystem, and a steam generation subsystem are provided. The molten salt thermal storage subsystem includes a cold salt storage tank and a hot salt storage tank. The gas combustion and molten salt heating subsystem includes a gas combustion molten salt heater equipped with a burner and a heating surface. The steam generation subsystem includes a molten salt-feedwater / steam heat exchanger.

[0007] S2. Obtain grid load status information, and determine whether the current operating condition is energy storage or energy release and power generation by comparing the real-time load value with the preset load threshold, so as to complete the initial allocation of the system operation mode.

[0008] S3. Execute the energy storage mode, guide the gas into the gas combustion molten salt heating furnace for combustion and heat generation, drive the cold salt pump to transport the low-temperature molten salt in the cold salt storage tank to the heating surface, and the low-temperature molten salt absorbs the combustion heat and is converted into high-temperature molten salt, which flows into the hot salt storage tank through the pipeline for storage.

[0009] S4. Execute the energy release and power generation mode, drive the hot salt pump to pump the high-temperature molten salt in the hot salt storage tank into the molten salt-feedwater / steam heat exchanger, heat the feedwater through the high-temperature molten salt to generate high-temperature and high-pressure steam, and control the high-temperature and high-pressure steam to flow into the working pipe of the steam turbine generator set through the steam manifold interface, while adjusting the circulation flow rate of the high-temperature molten salt to compensate for heat loss.

[0010] Preferably, step S2 includes:

[0011] S2.1. Based on the current operating conditions determined in step S2, collect the pressure of the main steam pipeline and the flow rate of the gas pipeline of the steam turbine generator set, and establish a theoretical energy balance vector containing the effective parameters of the current operating conditions.

[0012] S2.2. Monitor the power grid peak-shaving command in real time, calculate the target energy demand vector, and generate a global operation correction matrix based on the deviation between the target energy demand vector and the theoretical energy balance vector set.

[0013] Preferably, step S4 includes:

[0014] S4.1 Monitor the real-time steam parameters at the outlet of the molten salt-feedwater / steam heat exchanger. When the turbine generator set is in the peak load stage, increase the circulation flow rate of the high-temperature molten salt proportionally to meet the total energy input increment required by the turbine generator set in the peak load stage.

[0015] S4.2 Calculate the real-time heat transfer temperature difference between the high-temperature molten salt and the feed water, generate a heat loss compensation factor based on the heat transfer temperature difference, and dynamically adjust the frequency of the hot salt pump based on the heat loss compensation factor.

[0016] Preferably, step S4.1 is preceded by:

[0017] Analyze the real-time pressure fluctuations of the current gas pipeline. When the pressure fluctuations exceed the preset critical stability threshold, determine that the period is a period of unstable fuel supply and initiate the molten salt energy release compensation program to smooth out steam production fluctuations.

[0018] A steam generating device based on coal gas combustion and molten salt thermal storage, applied to the aforementioned steam generating method based on coal gas combustion and molten salt thermal storage, includes:

[0019] The molten salt thermal storage subsystem includes a cold salt storage tank, a hot salt storage tank, and a pump assembly for transporting molten salt.

[0020] A gas combustion and molten salt heating subsystem includes a gas combustion molten salt heating furnace located outside the molten salt thermal storage subsystem. The gas combustion molten salt heating furnace is equipped with a heat-receiving surface tube bundle that communicates with the cold salt storage tank.

[0021] The steam generation subsystem includes a molten salt-feedwater / steam heat exchanger. The molten salt side inlet of the molten salt-feedwater / steam heat exchanger is connected to the hot salt storage tank, and its steam side outlet is connected to the main steam pipeline of the steam turbine generator set through a steam manifold interface. Its molten salt side outlet is connected to the cold salt storage tank through a return pipeline.

[0022] An integrated control system, including controllers and sensor components, is used to execute the steam generation method based on gas combustion and molten salt thermal storage.

[0023] Preferably, the gas-fired molten salt heating furnace includes an inner chamber and an outer shell. The inner chamber has radiant heating surfaces and convective heating surfaces distributed alternately. The flame center generated by the burner and the radiant heating surfaces are coaxially distributed in space.

[0024] Preferably, several support structures are evenly distributed below the tank bodies of the cold salt storage tank and the hot salt storage tank, and thermal displacement compensation components are configured inside the support structures.

[0025] Preferably, the material of the heating surface tube bundle is a high-temperature and corrosion-resistant alloy, and a preset expansion gap is maintained between the heating surface tube bundle and the furnace wall of the gas-fired molten salt heating furnace.

[0026] Preferably, the integrated control system further includes a flue gas recirculation regulating valve slidably installed on the gas-fired molten salt heating furnace, and a flow control valve vertically installed on the feed water inlet pipe of the molten salt-feed water / steam heat exchanger. The pump assembly includes a frequency-controlled cold salt pump and a hot salt pump.

[0027] Preferably, the molten salt-feedwater / steam heat exchanger adopts a shell-and-tube structure, wherein the tube-side fluid is high-pressure feedwater and the shell-side fluid is high-temperature molten salt flowing out from the hot salt storage tank.

[0028] Compared with the prior art, the present invention has the following improvements and advantages:

[0029] 1. This invention constructs a molten salt thermal energy storage subsystem and embeds it into the gas combustion and steam generation process. It can store the combustion heat energy of surplus gas in high-temperature molten salt during off-peak hours and release the heat energy to generate high-temperature and high-pressure steam to drive the steam turbine generator set during peak load periods. This energy time-shifting mechanism based on operating condition determination effectively solves the structural contradiction between surplus gas during off-peak hours and insufficient output during peak hours faced by traditional gas generator sets, alleviates the limitation of gas supply fluctuations on power generation stability, and significantly improves the unit's adaptability to changes in grid load and its peak-shaving flexibility.

[0030] 2. This invention abandons the traditional adjustment method that relies on experience values. It establishes a theoretical energy balance vector by collecting the pressure of the main steam pipeline and the flow rate of the gas pipeline, and calculates the actual energy demand vector by combining the power grid commands. It uses a global operation correction matrix to convert the energy supply and demand deviation into specific execution commands for pump frequency and valves, realizing the digitalization and quantification of the control strategy. At the same time, it generates a heat loss compensation factor by calculating the heat transfer temperature difference, and dynamically adjusts the frequency of the hot salt pump to offset the heat attenuation caused by environmental heat exchange, thereby eliminating control lag and ensuring the quality of steam production and energy conservation under variable operating conditions.

[0031] 3. To address the common problem of unstable gas supply pressure in industrial production, this invention introduces a feedforward control mechanism based on the rate of pressure change. The system monitors pressure fluctuations in the gas pipeline in real time. Once the pressure exceeds the critical stability threshold, it immediately converts the fuel shortfall caused by the pressure drop into molten salt heat demand through an energy equivalence conversion factor, and initiates the molten salt thermal storage compensation program in advance to increase the output of the hot salt pump. This compensation method, utilizing the rapid response characteristics of the molten salt thermal storage, can effectively mitigate steam production fluctuations caused by unstable fuel supply, significantly enhancing the generator set's resistance to external disturbances.

[0032] 4. This invention incorporates several structural optimizations: the gas-fired molten salt heater adopts a design where the flame center and the radiant heating surface are coaxially distributed, ensuring uniform heating of the tube walls and preventing molten salt deterioration caused by localized overheating; the thermal displacement compensation component located below the storage tank effectively absorbs the displacement caused by the thermal expansion of the tank, preventing weld cracking; the design of reserved expansion gaps in the heating surface tube bundle alleviates thermal fatigue stress; furthermore, the molten salt-feedwater / steam heat exchanger adopts a layout where high-pressure feedwater flows through the tube side and high-temperature molten salt flows through the shell side, balancing pressure safety and heat exchange efficiency. These improvements to the mechanical structure collectively ensure the long-term operational safety and reliability of the system under high-temperature, high-pressure, and corrosive environments. Attached Figure Description

[0033] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0034] Figure 1 This is a schematic diagram of the overall structure of the device;

[0035] Figure 2 This is a schematic diagram of the structure of a molten salt-feedwater / steam heat exchanger;

[0036] Figure 3 This is a schematic diagram of a gas-fired molten salt heating furnace;

[0037] Figure 4 This is a flowchart of the method of the present invention.

[0038] In the diagram: 100, Molten Salt Thermal Storage Subsystem; 110, Cold Salt Storage Tank; 120, Hot Salt Storage Tank; 130, Cold Salt Pump; 140, Hot Salt Pump; 200, Gas Combustion and Molten Salt Heating Subsystem; 210, Gas Combustion Molten Salt Heating Furnace; 300, Steam Generation Subsystem; 310, Molten Salt-Feedwater / Steam Heat Exchanger; 400, Integration and Control System. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0040] Example 1:

[0041] Please see Figures 1-4 A steam generation method based on coal gas combustion and molten salt thermal storage, comprising:

[0042] S1. A molten salt thermal storage subsystem 100, a gas combustion and molten salt heating subsystem 200, and a steam generation subsystem 300 are provided. The molten salt thermal storage subsystem 100 includes a cold salt storage tank 110 and a hot salt storage tank 120. The gas combustion and molten salt heating subsystem 200 includes a gas combustion molten salt heater 210, which is equipped with a burner and a heating surface. The steam generation subsystem 300 includes a molten salt-feedwater / steam heat exchanger 310.

[0043] S2. Obtain grid load status information, and determine whether the current operating condition is energy storage or energy release and power generation by comparing the real-time load value with the preset load threshold, so as to complete the initial allocation of the system operation mode.

[0044] S3. Execute the energy storage mode, guide the gas into the gas combustion molten salt heating furnace 210 for combustion and heat generation, drive the cold salt pump 130 to transport the low temperature molten salt in the cold salt storage tank 110 to the heating surface, and the low temperature molten salt absorbs the combustion heat and is converted into high temperature molten salt, which flows into the hot salt storage tank 120 for storage through the pipeline.

[0045] S4. Execute the energy release power generation mode, drive the hot salt pump 140 to pump the high temperature molten salt in the hot salt storage tank 120 into the molten salt-feedwater / steam heat exchanger 310, heat the feedwater with the high temperature molten salt to generate high temperature and high pressure steam, and control the high temperature and high pressure steam to flow into the working pipe of the steam turbine generator set through the steam manifold interface, while adjusting the circulation flow of the high temperature molten salt to compensate for heat loss.

[0046] During the operation of conventional gas generator sets, the grid load fluctuates significantly at different times, resulting in a surplus of gas during off-peak hours and insufficient output during peak hours. To address this issue, the system first constructs the basic hardware environment by setting up a molten salt thermal storage subsystem 100, a gas combustion and molten salt heating subsystem 200, and a steam generation subsystem 300. In specific operation, the integration and control system 400 uses a Siemens S7-1500 controller to obtain load status information from the grid in real time.

[0047] The controller compares the real-time load value with the preset load threshold in its internal memory. When the real-time load is lower than the threshold, it is determined to be in energy storage mode. In this mode, gas enters the gas combustion molten salt heater 210 to release heat energy, driving the cold salt pump 130, controlled by an ABB ACS880 frequency converter, to send the low-temperature molten salt in the cold salt storage tank 110 to the heating surface. The low-temperature molten salt flows in the tube bundle of the heating surface and absorbs the radiation and convection heat of the furnace. The heated high-temperature molten salt is then stored in the hot salt storage tank 120 by the hot salt pump 140. During peak grid load, the controller switches to the energy release and power generation mode. The hot salt pump 140 pumps the high-temperature molten salt into the molten salt-feedwater / steam heat exchanger 310. The high-temperature molten salt and feedwater exchange heat non-contactly in the heat exchanger, heating the feedwater into high-temperature and high-pressure steam. The generated steam is then fed into the turbine generator unit through the steam manifold interface, realizing the transfer of energy in the time dimension.

[0048] This method utilizes the heat capacity characteristics of molten salt medium to alleviate the mismatch between gas supply and grid demand, which helps to improve the operational stability of generator sets.

[0049] The steps in S2 include:

[0050] S2.1. Based on the current operating conditions determined in step S2, collect the pressure of the main steam pipeline and the flow rate of the gas pipeline of the steam turbine generator set, and establish a theoretical energy balance vector containing the effective parameters of the current operating conditions.

[0051] S2.2 Real-time monitoring of power grid peak-shaving commands, calculation of the target energy demand vector, and generation of a global operation correction matrix based on the deviation between the target energy demand vector and the theoretical energy balance vector set.

[0052] To achieve precise switching of operating modes, the system needs to sense the balance between the unit's internal energy state and external dispatch demands. During this process, a main steam pipeline pressure sensor and a gas pipeline flow meter collect pressure and flow rate data, respectively. The gas pipeline flow meter is specifically installed at the inlet of the fuel branch pipeline entering the molten salt combustion furnace 210 to measure the raw energy input participating in the thermal storage conversion. The main steam pipeline pressure sensor is installed at the steam-side outlet header of the molten salt-feedwater / steam heat exchanger 310 to monitor the dynamic potential energy state of the produced steam. The controller uses these data as components to establish a theoretical energy balance vector reflecting the unit's current capacity. : ;

[0053] in, Main steam pressure, The gas flow rate is used to calculate the deviation. When calculating the deviation, the vector components and deviation values ​​corresponding to non-current operating conditions are set to zero to decouple the energy storage and release control strategies.

[0054] The controller monitors the power grid peak-shaving commands in real time through the communication interface and calculates the power demand in the commands to include the target main steam pressure. With target gas flow rate Actual energy demand vector ,Right now: ;

[0055] The calculation logic is as follows: subtract the current energy state vector from the target energy demand vector, i.e. The obtained numerical deviation is used to generate the global operational correction matrix; here, the deviation is represented as a matrix containing pressure variation and flow variation values. Column vector;

[0056] The controller uses this column vector with the internally stored decoupling gain matrix. Perform matrix multiplication to calculate the global runtime correction matrix. ,Right now The global runtime correction matrix The output vector is defined as ;

[0057] It should be noted that the decoupling gain matrix elements in and Not limited to a single proportional gain constant, but preferably a transfer function that includes both proportional P and integral I operators to eliminate the steady-state error of the system; for example, when the pressure deviation is positive, i.e., when the target demand is greater than the current measured value, the corresponding gain output is positive to increase the frequency, and the elements in this matrix... The corresponding pressure deviation affects the main regulating gain of the hot salt pump frequency, element The main regulating gain of the gas regulating valve opening corresponding to the flow deviation, rather than the diagonal element. and As a decoupling term, it takes the form of a feedforward transfer function or static gain derived from the object coupling model. Its value is pre-set based on the cross-coupling transfer function model between the gas flow control loop and the main steam pressure control loop, and is used to eliminate the coupling effect between the pressure loop and the flow loop, thereby realizing the transformation of the energy demand gap into physical action commands of the actuator; wherein, the decoupling gain matrix The elements in the system are determined by first conducting a step response experiment on the system and measuring the coupling transfer function between the gas flow rate and the main steam pressure. Then, the system is tuned using the system identification method and the decoupling algorithm in multivariable control theory.

[0058] This matrix directly determines the opening step value of the subsequent gas regulating valve and the rotational frequency of the pump assembly. Through this mathematical derivation process, the system can quantify the correspondence between the heat released by gas combustion and the heat absorbed by molten salt. This approach avoids the lag caused by simply relying on empirical values ​​for adjustment, making the system's response to power grid fluctuations more accurate and ensuring the energy conservation of heat storage and release.

[0059] The steps in S4 include:

[0060] S4.1 Monitor the real-time steam parameters at the outlet of the molten salt-feedwater / steam heat exchanger 310. When the turbine generator set is in the peak load stage, increase the circulation flow rate of the high-temperature molten salt proportionally to meet the total energy input increment required by the turbine generator set in the peak load stage.

[0061] S4.2 Calculate the real-time heat transfer temperature difference between the high-temperature molten salt and the feed water, generate a heat loss compensation factor based on the heat transfer temperature difference, and dynamically adjust the frequency of the hot salt pump 140 based on the heat loss compensation factor.

[0062] Under the condition of energy release and power generation, the stability of the steam output from the heat exchanger directly affects the working safety of the turbine generator set. The Rosemount 3051S pressure transmitter monitors the real-time steam parameters at the outlet of the molten salt-feedwater / steam heat exchanger 310. When it is determined that the unit is under peak load and the steam pressure shows a downward trend, the controller controls the hot salt pump 140 to increase the circulation flow rate of the high-temperature molten salt proportionally. The calculation logic is: based on the change in steam enthalpy, the required heat compensation value is deduced, and then the increase in flow rate is determined to maintain the total energy input to the turbine generator set per unit time at a constant state. At the same time, the PT100 temperature sensor monitors the temperature of the high-temperature molten salt inlet and the feedwater inlet, and the controller calculates the real-time heat transfer temperature difference between the two. Since the temperature difference change will change the heat exchange efficiency and cause fluctuations in the heat loss ratio, the system generates a heat loss compensation factor based on the temperature difference value.

[0063] This factor acts as a multiplier in the variable frequency control algorithm of the hot salt pump 140, dynamically adjusting the pump's speed and frequency. The derivation logic of the heat loss compensation factor aims to offset the heat energy attenuation caused by environmental heat exchange. The specific calculation logic quantifies the change in heat dissipation rate through measured temperature difference. The calculation formula is: ;

[0064] in As a heat loss compensation factor, This refers to the real-time temperature of the high-temperature molten salt. For real-time water temperature, The standard design temperature difference between the high-temperature molten salt inlet temperature and the feedwater inlet temperature under design conditions is taken as a reference value, for example... , This is a dimensionless thermal compensation constant preset based on the pipeline insulation coefficient;

[0065] When the measured temperature difference Less than the design reference value When heat loss occurs, causing the temperature difference to decrease, molecules... If it is a positive number, then... A value greater than 1 increases the rotational frequency of the hot salt pump 140, compensating for the decrease in enthalpy per unit mass of working fluid by increasing the amount of high-temperature molten salt circulating per unit time, thus maintaining the stability of the total heat exchange power. Simultaneously, the controller monitors the superheat at the feedwater outlet; if the superheat is lower than a preset safety threshold, for example... If the flow rate is too high, the controller will prioritize the outlet temperature protection logic, pausing or fine-tuning the frequency of the hot salt pump to prevent insufficient heat exchange of molten salt due to excessive flow rate, which could damage the system's hot and cold temperature gradient.

[0066] This flow regulation method offsets the interference caused by fluctuations in ambient temperature or changes in the physical properties of the medium during the heat exchange process, ensuring the quality of the produced steam and thus helping to maintain the stable operation of the steam turbine generator unit under high load.

[0067] The steps preceding S4.1 include:

[0068] Analyze the real-time pressure fluctuations of the gas pipeline. When the pressure fluctuations exceed the preset critical stability threshold, the period is determined to be a period of unstable fuel supply, and the molten salt energy release compensation program is activated to smooth out steam production fluctuations.

[0069] The stability of the gas supply is affected by fluctuations in industrial production, often resulting in unstable pipeline pressure. Pressure sensors installed on the main gas pipe collect pressure data in real time and transmit it to the controller. The controller analyzes the rate of pressure change over time. When the fluctuation amplitude exceeds a preset pressure fluctuation rate threshold (for example, the preset threshold is set to the absolute value of the pressure change exceeding...), a further action is taken. The system automatically determines that the current period is a period of unstable fuel supply. At this time, if the molten salt heating furnace 210 is operated solely by gas combustion, the steam output will fluctuate significantly. To this end, the controller starts the molten salt energy release compensation program, which increases the output of the hot salt pump 140 in advance. The adjustment strategy of the compensation program adopts a feedforward control mechanism based on the pressure change rate.

[0070] The controller calculates the pressure drop gradient in the gas pipeline in real time. When the pressure drop exceeds the preset critical stability threshold, the program converts the calorific value loss of the gas caused by the pressure drop into the required molten salt heat value based on the energy equivalence conversion factor. Energy equivalent conversion factor The pressure-calorific value conversion coefficient is a preset value derived from the ideal gas law and fuel combustion characteristics. It characterizes the chemical energy loss corresponding to the reduction in gas mass caused by a unit pressure drop. The calculation formula is as follows: ;

[0071] in, This is the pressure drop value. This refers to the physical pipe volume from the main gas pipe to the furnace inlet. The value of takes into account the molar mass of the gas, the gas constant, the temperature, and the lower heating value (LHV) of the gas. Its physical meaning is approximately equal to This is used to map the change in mass flow rate caused by gas pressure fluctuations into a gap in combustion chemical energy;

[0072] The system then uses this heat value as a benchmark to synchronously increase the output frequency of the hot salt pump 140, so that the increase in heat energy released by the molten salt can accurately fill the drop in the heat energy of the gas on the time axis and smooth out the fluctuation of steam production.

[0073] The heat in the hot salt storage tank 120 is quickly converted into steam to supplement the main pipeline; this linkage process, through the rapid response characteristics of thermal energy storage, mitigates the power shortage caused by unstable gas supply; by predicting the gas supply status and intervening in molten salt thermal storage, the system weakens the impact of external fuel fluctuations on the power generation side and enhances the overall energy output's anti-interference capability.

[0074] Example 2:

[0075] Please see Figures 1-3 A steam generating device based on coal gas combustion and molten salt thermal storage, comprising:

[0076] The molten salt thermal storage subsystem 100 includes a cold salt storage tank 110, a hot salt storage tank 120, and a pump assembly for transporting molten salt.

[0077] The gas combustion and molten salt heating subsystem 200 includes a gas combustion molten salt heater 210 located outside the molten salt thermal storage subsystem 100. The gas combustion molten salt heater 210 has a heat-receiving surface tube bundle that communicates with the cold salt storage tank 110 inside.

[0078] The steam generation subsystem 300 includes a molten salt-feedwater / steam heat exchanger 310. The molten salt side inlet of the molten salt-feedwater / steam heat exchanger 310 is connected to the hot salt storage tank 120, and its steam side outlet is connected to the main steam pipeline of the steam turbine generator set through a steam manifold interface. Its molten salt side outlet is connected to the cold salt storage tank 110 through a return pipeline.

[0079] The integrated control system 400 includes controller and sensor components and is used to execute a steam generation method based on gas combustion and molten salt thermal storage.

[0080] The steam generator achieves energy conversion through the structured combination of various subsystems. The molten salt thermal storage subsystem 100 serves as a thermal energy container, with the cold salt storage tank 110 and the hot salt storage tank 120 connected by high-temperature resistant pipes. The pump assembly is specifically a Flowserve vertical molten salt pump, responsible for the circulation power of the molten salt within the system. The gas combustion and molten salt heating subsystem 200 serves as a heat source and is located outside the storage tank area to ensure safety. The heating surface tube bundle inside the gas combustion molten salt heater 210 is arranged in a serpentine pattern and connected to the outlet of the cold salt storage tank 110 via flanges or welding. The molten salt-feedwater / steam heat exchanger 310 in the steam generation subsystem 300 is responsible for transferring the high-temperature molten salt energy from the hot salt storage tank 120 to the feedwater. Regarding the connections between subsystems, such as the connection between the pump assembly and the storage tank, flange connections with metal spiral wound gaskets can be used for sealing, or a long-shaft extension installation method can be used to place the pump body directly above the storage tank, as long as stable extraction and transportation of the medium can be achieved.

[0081] The integrated control system 400 uses a Siemens PLC as the core controller and is connected to Rosemount sensors in various locations through electrical control circuits. This configuration rationally divides the three processes of chemical energy conversion, thermal energy storage and steam generation in physical space, ensuring the mechanical structural reliability of the system under extreme high-temperature conditions.

[0082] The gas-fired molten salt heating furnace 210 includes an inner chamber and an outer shell. The inner chamber has radiant heating surfaces and convective heating surfaces that are alternately distributed. The flame center generated by the burner and the radiant heating surfaces are coaxially distributed in space.

[0083] In the design of the gas-fired molten salt heating furnace 210, heating efficiency and tube bundle life are the core considerations. The furnace structure includes a pressure-bearing outer shell and an inner chamber for combustion reaction. Inside the inner chamber, radiant heating surfaces are arranged around the burner, while convective heating surfaces are arranged at the flue gas turning points. The flame center formed by the burner jet and the cylindrical radiant heating surface tube bundle are spatially coaxially distributed. This design utilizes the physical characteristic that radiant heat transfer decreases with increasing distance, and the coaxial arrangement ensures uniform radiant intensity of the flame on the surrounding tube walls. This layout avoids local hot spots or overheating in the tube bundle and reduces the risk of local deterioration of the molten salt inside the tubes. The staggered convective heating surfaces further increase flue gas disturbance and prolong the residence time of high-temperature flue gas in the furnace, allowing the heat released by gas combustion to be more fully absorbed by the molten salt, thereby improving the heat conversion level of the heating furnace.

[0084] Several support structures are evenly distributed below the tank bodies of cold salt storage tank 110 and hot salt storage tank 120, and thermal displacement compensation components are installed inside the support structures.

[0085] When storing media at temperatures of several hundred degrees Celsius, the molten salt storage tank experiences significant thermal expansion. Below the bottoms of the cold salt storage tank 110 and the hot salt storage tank 120, a uniformly distributed support structure is installed. The thermal displacement compensation components within these support structures can be either combined spring supports or sliding polytetrafluoroethylene (PTFE) sliding plates. When the tank expands radially or axially due to temperature increases, the thermal displacement compensation components absorb these movements through the compression deformation of the springs or the relative displacement between the sliding plates. This mechanical linkage design alleviates the rigid constraint between the tank and the foundation ground, preventing cracking of the tank bottom welds or foundation damage caused by thermal stress concentration. Through this support method, the tank can freely expand and contract under hot operating conditions, ensuring the long-term safe operation of large-scale thermal storage devices.

[0086] The material of the heating surface tube bundle is a high-temperature and corrosion-resistant alloy, and a preset expansion gap is maintained between the heating surface tube bundle and the furnace wall of the gas-fired molten salt heating furnace 210.

[0087] The heated surface tube bundle is in direct contact with high-temperature flames and corrosive molten salt, which is an extremely harsh environment. The tube bundle material is 1Cr18Ni9Ti high-temperature and corrosion-resistant alloy steel pipe. In terms of physical installation, the tube bundle is not completely and tightly connected to the furnace wall of the gas-fired molten salt heating furnace 210, but a preset expansion gap is retained. This expansion gap is filled with a flexible sealing material such as ceramic fiber packing.

[0088] Because the coefficient of thermal expansion of the tube bundle after heating is much greater than that of the furnace wall masonry, this gap provides the necessary expansion and contraction space for the tube bundle; the preset expansion gap is based on the total length of the tube bundle. The linear expansion amount is calculated and determined; the heat exchange surface tube bundle is suspended from the top of the furnace by a hanger structure, and its bottom and sides maintain a sliding physical gap with the furnace wall. The free expansion of the mechanical structure alleviates the thermal fatigue stress of the metal material; this structure prevents the tube bundle from hitting the furnace wall during expansion, which would cause the tube to deform or the furnace wall to collapse; the combination of the chemical stability of the material and the mechanical redundancy of the structure reduces the frequency of equipment damage caused by thermal fatigue and extends the service life of the core heat exchange components.

[0089] The integrated control system 400 also includes a flue gas recirculation regulating valve that is slidably installed on the gas-fired molten salt heating furnace 210, and a flow control valve that is vertically installed on the molten salt-feed water / steam heat exchanger 310 pipeline. In specific implementations, it is recommended to select an electric regulating ball valve or a pneumatic diaphragm regulating valve whose nominal diameter matches the inlet feed water pipeline of the heat exchanger, as long as it can achieve the change of fluid cross-sectional area; the pump assembly includes a frequency-controlled cold salt pump 130 and a hot salt pump 140.

[0090] To finely regulate the heat transfer process, the integrated control system 400 incorporates multiple actuators. The flue gas recirculation regulating valve is installed in the tail flue of the furnace via a sliding guide rail, while the flow control valve is vertically installed on the heat exchanger inlet water pipe. In practical implementation, it is recommended to use an electric regulating ball valve or a pneumatic diaphragm regulating valve with a nominal diameter matching the heat exchanger inlet feed water pipe. By changing the relative stroke of the valve core within the valve body, precise throttling of the water flow is achieved. The cold brine pump 130 and hot brine pump 140 are equipped with frequency converters. When the controller detects that the molten salt temperature is too high, the flue gas recirculation regulating valve is increased to introduce cold flue gas to lower the furnace temperature. When an increase in steam is required, the frequency of the hot brine pump 140 is simultaneously increased, and the flow control valve is adjusted. These mechanisms, through unified scheduling by the controller, achieve closed-loop adjustment of thermal parameters. This multi-dimensional adjustment method allows the system to flexibly adapt to different fluctuations in the calorific value of the gas, maintaining relatively stable steam parameters.

[0091] The molten salt-feedwater / steam heat exchanger 310 adopts a shell-and-tube structure, in which the tube-side fluid is high-pressure feedwater and the shell-side fluid is high-temperature molten salt flowing out from the hot salt storage tank 120.

[0092] The molten salt-feedwater / steam heat exchanger 310 undertakes intense heat exchange tasks, and its internal flow channel design is crucial to its heat exchange performance. This heat exchanger adopts a shell-and-tube structure, with high-pressure feedwater flowing in the tube side and high-temperature molten salt flowing in the shell side. The tube side is equipped with reinforcing tube bundles, while the shell side has baffles. Guided by the baffles, the high-temperature molten salt advances in a wave-like pattern within the shell side, increasing the scouring velocity against the tube wall and thus improving the overall heat transfer coefficient. The high-pressure feedwater absorbs heat and vaporizes within the tubes. Placing the high-pressure fluid inside the tubes effectively reduces the pressure-bearing thickness requirement of the shell, while placing the molten salt in the shell side facilitates media discharge and ash removal. This design physically balances pressure safety and heat exchange efficiency, making the heat exchange process smoother and providing structural support for the stable generation of high-quality steam.

[0093] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A steam generation method based on coal gas combustion and molten salt thermal storage, characterized in that, include: S1. A molten salt thermal storage subsystem (100), a gas combustion and molten salt heating subsystem (200), and a steam generation subsystem (300) are provided. The molten salt thermal storage subsystem (100) includes a cold salt storage tank (110) and a hot salt storage tank (120). The gas combustion and molten salt heating subsystem (200) includes a gas combustion molten salt heater (210), which is equipped with a burner and a heating surface. The steam generation subsystem (300) includes a molten salt-feedwater / steam heat exchanger (310). S2. Obtain grid load status information, and determine whether the current operating condition is energy storage or energy release and power generation by comparing the real-time load value with the preset load threshold, and complete the initial allocation of the system operation mode. S3. Execute the energy storage mode, guide the gas into the gas combustion molten salt heating furnace (210) for combustion and heat generation, drive the cold salt pump (130) to transport the low temperature molten salt in the cold salt storage tank (110) to the heating surface, and the low temperature molten salt is converted into high temperature molten salt after absorbing the combustion heat, and flows into the hot salt storage tank (120) through the pipeline for storage. S4. Execute the energy release power generation mode, drive the hot salt pump (140) to pump the high temperature molten salt in the hot salt storage tank (120) into the molten salt-feedwater / steam heat exchanger (310), heat the feedwater with the high temperature molten salt to generate high temperature and high pressure steam, control the high temperature and high pressure steam to flow into the working pipe of the steam turbine generator set through the steam manifold interface, and at the same time adjust the circulation flow of the high temperature molten salt to compensate for heat loss, and transport the molten salt after heat exchange and cooling back to the cold salt storage tank (110) through the return pipe to complete the medium circulation.

2. The steam generation method based on coal gas combustion and molten salt thermal storage according to claim 1, characterized in that, The steps in S2 include: S2.

1. Based on the current operating conditions determined in step S2, collect the pressure of the main steam pipeline and the flow rate of the gas pipeline of the steam turbine generator set, and establish a theoretical energy balance vector containing the effective parameters of the current operating conditions. S2.

2. Monitor the power grid peak-shaving command in real time, calculate the target energy demand vector, and generate a global operation correction matrix based on the deviation between the target energy demand vector and the theoretical energy balance vector set.

3. The steam generation method based on coal gas combustion and molten salt thermal storage according to claim 1, characterized in that, The steps in S4 include: S4.1 Monitor the real-time steam parameters at the outlet of the molten salt-feedwater / steam heat exchanger (310). When the turbine generator set is in the peak load stage, increase the circulation flow rate of the high-temperature molten salt proportionally to meet the total energy input increment required by the turbine generator set in the peak load stage. S4.2 Calculate the real-time heat transfer temperature difference between the high-temperature molten salt and the feed water, generate a heat loss compensation factor based on the heat transfer temperature difference, and dynamically adjust the frequency of the hot salt pump (140) based on the heat loss compensation factor.

4. The steam generation method based on coal gas combustion and molten salt thermal storage according to claim 3, characterized in that, The steps preceding S4.1 include: Analyze the real-time pressure fluctuations of the current gas pipeline. When the pressure fluctuations exceed the preset critical stability threshold, determine that the period is a period of unstable fuel supply and initiate the molten salt energy release compensation program to smooth out steam production fluctuations.

5. A steam generator based on coal gas combustion and molten salt thermal storage, applied to the steam generation method based on coal gas combustion and molten salt thermal storage as described in any one of claims 1 to 4, characterized in that, include: The molten salt thermal storage subsystem (100) includes a cold salt storage tank (110), a hot salt storage tank (120), and a pump assembly for conveying molten salt; The gas combustion and molten salt heating subsystem (200) includes a gas combustion molten salt heater (210) located outside the molten salt thermal storage subsystem (100), and the gas combustion molten salt heater (210) has a heat-receiving surface tube bundle that communicates with the cold salt storage tank (110) inside. The steam generation subsystem (300) includes a molten salt-feedwater / steam heat exchanger (310), the molten salt side inlet of which is connected to the hot salt storage tank (120), its steam side outlet is connected to the main steam pipeline of the steam turbine generator set through a steam manifold interface, and its molten salt side outlet is connected to the cold salt storage tank (110) through a return pipeline. An integrated control system (400) including a controller and sensor components is used to execute the steam generation method based on gas combustion and molten salt thermal storage.

6. A steam generator based on coal gas combustion and molten salt thermal storage according to claim 5, characterized in that, The gas-fired molten salt heating furnace (210) includes an inner chamber and an outer shell. The inner chamber has radiant heating surfaces and convective heating surfaces that are alternately distributed. The flame center generated by the burner and the radiant heating surfaces are coaxially distributed in space.

7. A steam generator based on coal gas combustion and molten salt thermal storage according to claim 5, characterized in that, Several support structures are evenly distributed below the tank bodies of the cold salt storage tank (110) and the hot salt storage tank (120), and thermal displacement compensation components are configured inside the support structures.

8. A steam generator based on coal gas combustion and molten salt thermal storage according to claim 5, characterized in that, The material of the heating surface tube bundle is a high-temperature and corrosion-resistant alloy, and a preset expansion gap is maintained between the heating surface tube bundle and the furnace wall of the gas-fired molten salt heating furnace (210).

9. A steam generator based on coal gas combustion and molten salt thermal storage according to claim 5, characterized in that, The integrated control system (400) also includes a flue gas recirculation regulating valve slidably mounted on the gas-fired molten salt heater (210) and a flow control valve vertically mounted on the feed water inlet pipe of the molten salt-feed water / steam heat exchanger (310). The pump assembly includes a frequency-controlled cold salt pump (130) and a hot salt pump (140).

10. A steam generator based on coal gas combustion and molten salt thermal storage according to claim 5, characterized in that, The molten salt-feedwater / steam heat exchanger (310) adopts a shell-and-tube structure, wherein the tube-side fluid is high-pressure feedwater and the shell-side fluid is high-temperature molten salt flowing out from the hot salt storage tank (120).

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