Waste heat utilization system based on energy conservation and emission reduction of thermal power plant

Abstract

The invention provides a waste heat utilization system based on energy conservation and emission reduction of a thermal power plant, and relates to the technical field of energy conservation and emission reduction of the thermal power plant. The organic Rankine cycle module is connected with the heat exchanger and converts waste heat into electric energy; the chemical heat storage module is also connected with the heat pipe heat exchange module, and when waste heat is sufficient and the organic Rankine cycle module cannot be completely utilized, redundant heat is stored and released as required; the power grid demand acquisition module acquires the demand power of the current power grid for the waste heat; the intelligent control module is connected with each module, monitors and controls the operation of the whole system, and automatically switches a heat distribution proportion according to monitoring parameters and power grid demand power to realize energy-saving operation; organic Rankine cycle and chemical heat storage are combined, the power grid electric energy requirement is met, redundant heat is stored, and the application range is widened; parameters can be monitored in real time, required power of a power grid can be obtained, heat distribution is automatically adjusted, system efficiency and reliability are improved, and energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy conservation and emission reduction in thermal power plants, and in particular to a waste heat utilization system based on energy conservation and emission reduction in thermal power plants. Background Art

[0002] With the continuous growth of global energy demand and the increasing attention to environmental protection, improving energy efficiency and reducing greenhouse gas emissions have become key goals in the energy field. As the main energy production unit, thermal power plants generate a large amount of waste heat during the power generation process. If this waste heat is not effectively utilized, it will not only waste energy, but also cause adverse effects such as thermal pollution to the environment.

[0003] In the early days, the use of waste heat in thermal power plants was relatively simple and extensive, mainly using some basic heat exchange equipment to use waste heat for simple purposes such as heating within the plant area. With the development of technology, some more efficient ways of using waste heat have gradually emerged; for example, using waste heat to drive absorption refrigerators to achieve refrigeration functions, and using waste heat for preheating in industrial production processes, which has increased the utilization value of waste heat.

[0004] However, the existing waste heat utilization system can only convert waste heat into one form of energy, such as heating or power generation, and cannot flexibly adjust the energy output form according to actual needs, thus limiting the application scope of the waste heat utilization system; at the same time, most of the existing waste heat utilization systems lack intelligent control methods, and cannot automatically adjust the system's operating parameters and working modes according to real-time waste heat generation and grid demand, resulting in the system being unable to operate stably and efficiently. Summary of the invention

[0005] The present invention provides a waste heat utilization system based on energy conservation and emission reduction of thermal power plants, which is used to solve the problems existing in the above-mentioned prior art and realize efficient utilization of waste heat and energy conservation and emission reduction of thermal power plants.

[0006] The present invention provides a waste heat utilization system based on energy saving and emission reduction of thermal power plants, comprising:

[0007] Heat pipe heat exchange module, which is installed on the exhaust pipe of a thermal power plant to recover waste heat from flue gas;

[0008] An organic Rankine cycle module, which is connected to the heat pipe heat exchange module and is used to convert the recovered waste heat into electrical energy;

[0009] A chemical heat storage module, which is connected to the heat pipe heat exchange module and is used to store excess heat when the waste heat supply is sufficient and the organic Rankine cycle module cannot fully utilize it, and release it when needed;

[0010] A power grid demand acquisition module, which is used to obtain the current power grid demand for waste heat;

[0011] An intelligent control module is connected to the heat pipe heat exchange module, the organic Rankine cycle module, the chemical heat storage module, and the grid demand acquisition module, and is used to monitor and control the operation of the entire system, and automatically switch different heat distribution ratios according to various parameters monitored during the waste heat utilization process and the current power demand of the grid to achieve energy-saving operation.

[0012] Furthermore, the heat pipe heat exchange module comprises:

[0013] a heat exchange pipeline connected to the input ends of the organic Rankine cycle module and the chemical heat storage module, and used to obtain heat from the flue gas and send it to the organic Rankine cycle module and the chemical heat storage module respectively;

[0014] A flow monitor, which is arranged at the inlet of the heat exchange pipe and is used to obtain the flue gas mass flow rate passing through the heat exchange pipe in real time; the flue gas mass flow rate represents the mass of flue gas passing through the heat exchange pipe per unit time;

[0015] A temperature monitor, which is arranged at the inlet and outlet of the heat exchange pipe, and is used to obtain the temperature of the flue gas when it enters and leaves the heat exchange pipe, as well as the ambient temperature in real time;

[0016] The flow splitting unit is arranged at the end of the heat exchange pipe and is used to control the ratio of heat distributed to the organic Rankine cycle module and the chemical heat storage module.

[0017] Furthermore, the organic Rankine cycle module includes an evaporator, an expander, a generator, a condenser and a working fluid pump; the evaporator is used to receive the heat transferred by the heat exchange pipe, the expander and the working fluid pump drive the generator to operate and convert the energy of the working fluid into electrical energy, and the condenser is used to quickly cool the working fluid and provide working conditions for the working fluid pump.

[0018] Furthermore, the chemical heat storage module includes a heat storage container and a reversible chemical reactant; the reversible chemical reactant is used to undergo a chemical reaction after heat input, which is absorbed and stored in the heat storage container; and to undergo a reverse reaction when necessary to release heat.

[0019] Furthermore, the intelligent control module includes:

[0020] A heat recovery power calculation unit, which is connected to the flow monitor and the temperature monitor, and calculates the heat recovery power Ph,r based on the flue gas mass flow and the flue gas temperature;

[0021] The power generation calculation unit is connected to the heat recovery power calculation unit and the diversion unit, and based on the heat recovery power P h，r Calculate the power generation P with the current allocation ratio ORC ;

[0022] The heat storage power calculation unit is connected to the temperature monitoring meter and the power generation calculation unit, based on the heat recovery power P h，r and ambient temperature and power generation P ORC Calculate the heat storage power P s，in and heat release power P s，out ;

[0023] The proportional distribution unit is connected to the heat recovery power calculation unit, the power generation power calculation unit, the heat storage power calculation unit and the grid demand acquisition module, and based on the current heat recovery power P h，r , power generation P ORC , heat storage power P s，in , heat release power P s，out and the power grid's demand for waste heat P g Calculate the ideal allocation ratio k x and (1-k x ), where k x is the proportion allocated to the organic Rankine cycle module, (1-k x ) is the proportion allocated to the chemical heat storage module.

[0024] Optionally, the heat recovery power calculation unit calculates the heat recovery power P by the following formula: h，r :

[0025]

[0026] Among them, P h，r is the heat recovery power; C p The specific heat capacity of flue gas indicates the amount of heat absorbed by a unit mass of flue gas when the unit temperature is raised. Its value is related to the composition of the flue gas. is the flue gas mass flow rate; T f，in and T f，out are the temperatures of the flue gas when it enters and leaves the heat exchange pipe, respectively.

[0027] Optionally, the power generation calculation unit calculates the power generation P by the following formula: ORC :

[0028] P ORC =η ORC *(P h，r *t*k0)

[0029] Among them, P ORC is the power generation; η ORC is the efficiency of the organic Rankine cycle module, which is related to the performance of each component of the module; t is the length of time for flue gas emission; k0 is the proportion allocated to the organic Rankine cycle module in the initial state.

[0030] Optionally, the heat storage power calculation unit calculates the heat storage power P by the following formula: s，in and heat release power P s，out :

[0031]

[0032] P s，out =η s *∫P s，in dt

[0033] Among them, P s，in is the heat storage power, P s，out is the heat release power; represents the power loss, where j loss is the heat loss coefficient of the heat exchange pipe, determined based on experiments, A is the average cross-sectional area of ​​the heat exchange pipe, T hot is the average flue gas temperature, T amb is the ambient temperature; η s is the heat release efficiency of the chemical heat storage module, which is related to the properties of the reversible chemical reactants and the structure of the heat storage container and is obtained through experimental measurement; ∫P s，in dt represents the heat currently stored in the chemical heat storage module.

[0034] According to a waste heat utilization system based on energy saving and emission reduction of thermal power plants provided by the present invention, the proportion allocation unit calculates the ideal allocation ratio k x and (1-k x ) process is:

[0035] Calculate the remaining power P` for heat storage s，in :

[0036] P` s，in =P h，r -P g -P ORC ;

[0037] For the remaining power P` s，in Make a judgment:

[0038] When P` s，in >0, set the first adjustment coefficient α and calculate the ideal allocation ratio kx:

[0039]

[0040] Further we get (1-k x );

[0041] When P` s，in ≤0, set the second adjustment coefficient β and calculate the ideal allocation ratio k x :

[0042]

[0043] Further we get (1-kx);

[0044] When P h，r ≤P g When , set the third adjustment coefficient γ and calculate the ideal allocation ratio kx:

[0045]

[0046] Further we get (1-k x );

[0047] The value ranges of the first adjustment coefficient α, the second adjustment coefficient β, and the third adjustment coefficient γ are {0, 1}, and the specific values ​​are pre-set based on actual conditions;

[0048] The ideal allocation ratio k x and (1-k x ) is sent to the proportional distribution unit to complete the heat distribution action.

[0049] Compared with the prior art, the beneficial effects of this application are:

[0050] This application combines the organic Rankine cycle with chemical heat storage. The organic Rankine cycle meets the power demand of the power grid, and the chemical heat storage module stores excess heat, which can be used for refrigeration, power grid transmission or industrial preheating as needed, thereby broadening the scope of application. At the same time, this application can monitor parameters in real time and obtain the power demand of the power grid, automatically adjust the heat distribution ratio and power generation power, improve system efficiency and reliability, and achieve energy conservation and emission reduction in thermal power plants.

[0051] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0052] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0054] Figure 1 It is a structural schematic diagram of a waste heat utilization system based on energy conservation and emission reduction in a thermal power plant provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0056] Embodiment 1:

[0057] The embodiment of the present invention provides a waste heat utilization system based on energy saving and emission reduction of thermal power plants. Figure 1 ,include:

[0058] Heat pipe heat exchange module, which is installed on the exhaust pipe of a thermal power plant to recover waste heat from flue gas;

[0059] An organic Rankine cycle module, which is connected to the heat pipe heat exchange module and is used to convert the recovered waste heat into electrical energy;

[0060] A chemical heat storage module, which is connected to the heat pipe heat exchange module, is used to store excess heat when the waste heat supply is sufficient and the organic Rankine cycle module cannot fully utilize it, and release it when needed;

[0061] A power grid demand acquisition module, which is used to obtain the current power grid demand for waste heat;

[0062] The intelligent control module is connected to the heat pipe heat exchange module, the organic Rankine cycle module, the chemical heat storage module, and the grid demand acquisition module to monitor and control the operation of the entire system. It automatically switches different heat distribution ratios according to the various parameters monitored during the waste heat utilization process and the current power demand of the grid to achieve energy-saving operation.

[0063] The principle of this embodiment is as follows: the heat pipe heat exchange module is installed on the exhaust pipe of the thermal power plant. When the flue gas passes through the heat exchange pipe, the heat is transferred to the working medium through the efficient heat transfer mechanism of the heat pipe; the working medium inside the heat pipe absorbs heat at the heating end and vaporizes, and the steam flows to the condensing end under the action of the pressure difference, releases latent heat at the condensing end and condenses into liquid, and then flows back to the heating end by capillary force or gravity, etc., and the cycle is repeated to achieve efficient recovery of flue gas waste heat;

[0064] The recovered heat is transferred to the organic Rankine cycle module. In the evaporator, the working fluid absorbs heat and becomes high-temperature and high-pressure steam, which then enters the expander. In the expander, the steam expands and does work, driving the generator to rotate and generate electricity. The steam discharged from the expander enters the condenser and is cooled into liquid, which is then pumped back to the evaporator by the working fluid pump, completing an organic Rankine cycle.

[0065] When the organic Rankine cycle module cannot fully utilize the recovered waste heat, the excess heat is transferred to the chemical heat storage module; the reversible chemical reactants in the chemical heat storage module undergo chemical reactions after absorbing heat and store the heat in the form of chemical energy; when heat is needed, the reversible chemical reactants undergo reverse reactions and release the stored heat;

[0066] The intelligent control module is connected to each module to obtain the flue gas temperature, flow rate and other parameters of the heat pipe heat exchange module, calculate the heat recovery power; obtain the power generation power and other parameters of the organic Rankine cycle module; obtain the heat storage state and other parameters of the chemical heat storage module; and obtain the power demand of the power grid for waste heat provided by the power grid demand acquisition module; then, based on these parameters, the ideal heat distribution ratio is calculated through a preset algorithm, the diversion unit of the heat pipe heat exchange module is controlled, and the ratio of heat distribution to the organic Rankine cycle module and the chemical heat storage module is adjusted.

[0067] The beneficial effects of this embodiment are: achieving efficient waste heat recovery and utilization, providing flexible energy output forms, solving the problem of heat supply and demand mismatch, and realizing intelligent optimized operation.

[0068] In order to further optimize the above embodiment, the heat pipe heat exchange module includes:

[0069] A heat exchange pipeline, which is connected to the input end of the organic Rankine cycle module and the chemical heat storage module, and is used to obtain heat in the flue gas and send it to the organic Rankine cycle module and the chemical heat storage module respectively;

[0070] A flow monitor is provided at the inlet of the heat exchange pipe to obtain the flue gas mass flow rate through the heat exchange pipe in real time; the flue gas mass flow rate represents the flue gas mass passing through the heat exchange pipe per unit time;

[0071] The temperature monitor is installed at the entrance and exit of the heat exchange pipe to obtain the temperature of the flue gas when it enters and leaves the heat exchange pipe, as well as the ambient temperature in real time;

[0072] The flow splitter unit is arranged at the end of the heat exchange pipe and is used to control the ratio of heat distributed to the organic Rankine cycle module and the chemical heat storage module.

[0073] It should be noted that the flow monitor obtains the flue gas mass flow rate by measuring the flue gas mass passing through the heat exchange pipe per unit time; its working principle is based on a specific measurement technology, for example, the principle of a thermal mass flow meter can be used, that is, the relationship between the heat taken away by the gas when it flows through a heated sensor and the mass flow rate is used for measurement; when the flue gas passes through the flow monitor, the sensor calculates the flue gas mass flow rate based on the heat change and transmits the data to the intelligent control module;

[0074] The temperature monitor is installed at the entrance and exit of the heat exchange pipe, and can sense the temperature of the flue gas when it enters and leaves the heat exchange pipe and the ambient temperature in real time; it uses the characteristics of temperature sensitive elements (such as thermocouples or thermal resistors). When the temperature changes, the electrical characteristics of the temperature sensitive elements (such as resistance or thermoelectric potential) will also change accordingly; by measuring the changes in these electrical characteristics, the temperature monitor converts the temperature signal into an electrical signal and transmits it to the intelligent control module;

[0075] The diversion unit is located at the end of the heat exchange pipe. It controls the ratio of heat distribution to the organic Rankine cycle module and the chemical heat storage module according to the instructions of the intelligent control module. Its working principle is based on adjustable valves or other flow control devices. When the intelligent control module calculates the ideal heat distribution ratio according to the operating parameters and requirements of the system, it will send a control signal to the diversion unit. After receiving the signal, the diversion unit changes the heat flow to the organic Rankine cycle module and the chemical heat storage module by adjusting the valve opening or other flow control methods, thereby achieving reasonable distribution of heat to meet the different operating requirements of the system. It sets another initial configuration ratio, usually 50%.

[0076] In order to further optimize the above embodiment, the organic Rankine cycle module includes an evaporator, an expander, a generator, a condenser and a working fluid pump; the evaporator is used to receive the heat transferred by the heat exchange pipe, the expander and the working fluid pump drive the generator to operate and convert the energy of the working fluid into electrical energy, and the condenser is used to quickly cool the working fluid and provide working conditions for the working fluid pump.

[0077] It should be noted that the evaporator receives heat transferred from the heat exchange pipe, so that the working fluid inside absorbs the heat and undergoes a phase change, from liquid to gas; its working principle is based on the heat exchange process, and the heat transferred by the heat exchange pipe can be efficiently transferred to the working fluid through the pipe or tube bundle structure inside the evaporator; the working fluid continuously absorbs heat in the evaporator, and the temperature and pressure gradually increase until it reaches a saturated state and begins to vaporize, providing high-temperature and high-pressure steam for subsequent expansion and work in the expander; when the high-temperature and high-pressure working fluid steam enters the expander from the evaporator, the steam expands in the special structure inside the expander (such as turbine blades or piston structures), and the pressure and temperature drop rapidly; according to the law of conservation of energy, the internal energy of the steam is converted into mechanical energy, driving the rotor or piston of the expander to move; the rotation of the expander is connected to the generator through a shaft, thereby transferring the mechanical energy to the generator to provide power for power generation; the main function of the condenser is to quickly cool the working fluid discharged from the expander Steam, turning it from gaseous state back into liquid state, providing suitable working conditions for the working fluid pump; its working principle is to transfer the heat of the working fluid steam to the cooling medium (such as cooling water or air) through heat exchange; the inside of the condenser usually adopts a tube bundle structure or a plate structure to increase the contact area between the working fluid steam and the cooling medium and improve the cooling efficiency; after the working fluid steam releases heat in the condenser, the temperature and pressure decrease and condenses into a liquid state, which is convenient for the working fluid pump to transport it back to the evaporator to complete an organic Rankine cycle; the working fluid pump is responsible for transporting the liquid working fluid cooled in the condenser back to the evaporator to maintain the continuous progress of the organic Rankine cycle; it overcomes the flow resistance of the working fluid in the pipelines and components through mechanical work, and transports the liquid working fluid back to the evaporator at a certain pressure and flow rate; the working principle of the working fluid pump is based on the principle of a volumetric pump or a centrifugal pump. According to the design and requirements of the system, a suitable pump type is selected to ensure that the working fluid can circulate stably in the organic Rankine cycle module.

[0078] In order to further optimize the above embodiment, the chemical heat storage module includes a heat storage container and a reversible chemical reactant; the reversible chemical reactant is used to undergo a chemical reaction after heat input, which is absorbed and stored in the heat storage container; and to undergo a reverse reaction when necessary to release heat.

[0079] It should be noted that the heat storage container provides a closed space environment for the reversible chemical reaction, ensuring that the chemical reaction can proceed under stable conditions while preventing heat loss; it needs to have good thermal insulation performance to reduce heat loss during storage; generally, the container wall is made of materials with low thermal conductivity, such as ceramic fiber, rock wool and other insulation materials, or a double-layer structure is used with a vacuum in the middle to further improve the insulation effect;

[0080] Reversible chemical reactants are the core of the chemical heat storage module. When heat is input, the reversible chemical reactants undergo a forward chemical reaction, absorbing heat and storing it in the form of chemical energy. For example, taking the common calcium carbonate-calcium oxide-carbon dioxide (CaCO3-CaO-CO2) system as an example, at high temperatures, calcium carbonate decomposes into calcium oxide and carbon dioxide. This reaction is an endothermic reaction, i.e., CaCO3→CaO+CO2↑, and heat is absorbed and stored in the reaction system.

[0081] When heat needs to be released, the reversible chemical reactants undergo a reverse reaction; still taking the calcium carbonate-calcium oxide-carbon dioxide system as an example, calcium oxide and carbon dioxide react again to form calcium carbonate, that is, CaO+CO2→CaCO3. This reaction is an exothermic reaction, releasing the previously stored heat;

[0082] Different reversible chemical reactant systems have different reaction conditions and heat storage performances. When selecting, it is necessary to make comprehensive considerations based on the specific requirements of the system and the actual application scenarios.

[0083] In order to further optimize the above embodiment, the intelligent control module includes:

[0084] The heat recovery power calculation unit is connected to the flow monitor and temperature monitor to calculate the heat recovery power P based on the flue gas mass flow and flue gas temperature. h，r ;

[0085] The power generation calculation unit is connected to the heat recovery power calculation unit and the diversion unit, and based on the heat recovery power P h，r Calculate the power generation P with the current allocation ratio ORC ;

[0086] The heat storage power calculation unit is connected to the temperature monitoring meter and the power generation calculation unit, based on the heat recovery power P h，r and ambient temperature and power generation P ORC Calculate the heat storage power P s，in and heat release power P s，out ;

[0087] The proportional allocation unit is connected with the heat recovery power calculation unit, the power generation power calculation unit, the heat storage power calculation unit and the grid demand acquisition module, and based on the current heat recovery power P h，r , power generation P ORC , heat storage power P s，in , heat release power P s，out and the power grid's demand for waste heat P g Calculate the ideal allocation ratio k x and (1-k x ), where k xis the proportion allocated to the organic Rankine cycle module, (1-k x ) is the proportion allocated to the chemical heat storage module;

[0088] The calculation formula of the heat recovery power calculation unit is:

[0089]

[0090] Among them, P h，r is the heat recovery power; C p The specific heat capacity of flue gas indicates the amount of heat absorbed by a unit mass of flue gas when the unit temperature is raised. Its value is related to the composition of the flue gas. is the flue gas mass flow rate; T f，in and T f，out are the temperatures of the flue gas when it enters and leaves the heat exchange pipe respectively;

[0091] The calculation formula of the power generation calculation unit is:

[0092] P ORC =η ORC *(P h，r *t*k0)

[0093] Among them, P ORC is the power generation; η ORC is the efficiency of the organic Rankine cycle module, which is related to the performance of each component of the module; t is the length of time for flue gas emission; k0 is the proportion allocated to the organic Rankine cycle module in the initial state;

[0094] The calculation formula of the heat storage and release power calculation unit is:

[0095]

[0096] P s，out =η s *∫P s，in dt

[0097] Among them, P s，in is the heat storage power, P s，out is the heat release power; represents the power loss, where j loss is the heat loss coefficient of the heat exchange pipe, determined based on experiments, A is the average cross-sectional area of ​​the heat exchange pipe, T hot is the average flue gas temperature, T amb is the ambient temperature; η s is the heat release efficiency of the chemical heat storage module, which is related to the properties of the reversible chemical reactants and the structure of the heat storage container and is obtained through experimental measurement; ∫P s，in dt represents the heat currently stored in the chemical heat storage module.

[0098] It should be noted that the basic principle of the calculation formula of the heat recovery power calculation unit is that heat is equal to the product of specific heat capacity, mass flow rate and temperature change; in the heat pipe heat exchange module, the flue gas carries heat. By measuring the temperature difference of the flue gas entering and leaving the heat pipe heat exchange module, combined with the specific heat capacity and mass flow rate of the flue gas, the heat power recovered by the heat pipe heat exchange module can be calculated; the power generation power of the organic Rankine cycle module depends on the heat input to the module and the efficiency of the module itself; for the heat storage power formula, when the waste heat power recovered by the heat pipe heat exchange module is greater than the power utilized by the organic Rankine cycle module, the excess heat will be stored in the chemical heat storage module, so the heat storage power is equal to The power of the recovered waste heat minus the power of the organic Rankine cycle; the heat release power formula is based on the characteristics of the chemical heat storage module, and the heat power released is related to the stored energy and the heat release efficiency; as for the loss, it also includes the pipeline pressure loss, which represents the pressure loss caused by factors such as friction when the fluid flows. When the fluid flows in the pipeline, the friction resistance of the pipe wall will reduce the pressure of the fluid. This formula comprehensively considers the length and diameter of the pipeline, the properties of the fluid (density and flow rate) and the friction coefficient to calculate the pressure loss; its calculation formula can refer to the Darcy-Weisbach formula, which is a prior art, so there is no need to explain the principle;

[0099] The heat recovery power calculation unit obtains the flue gas mass flow measured by the flow monitor and the temperature of the flue gas in and out of the heat exchange pipe measured by the temperature monitor, and uses the heat recovery power calculation formula for calculation; this formula is based on the basic principle of heat calculation, that is, heat is equal to the product of specific heat capacity, mass flow and temperature change; by accurately measuring these parameters and substituting them into the formula, the heat power recovered by the heat pipe heat exchange module can be accurately calculated;

[0100] The power generation calculation unit is connected to the heat recovery power calculation unit and the shunt unit; it first obtains the heat recovery power calculated by the heat recovery power calculation unit, and then calculates the power generation power using the power generation calculation formula in combination with the current allocation ratio set by the shunt unit and the known parameters such as the efficiency of the organic Rankine cycle module and the length of flue gas emission time; this process takes into account the ability of the organic Rankine cycle module to convert heat into electrical energy and the actual heat ratio allocated to the module;

[0101] The heat storage and release power calculation unit is connected to the temperature monitor and the power generation calculation unit; it calculates the heat storage power and the heat release power using the heat storage and release power calculation formula based on the ambient temperature obtained by the temperature monitor and the power generation power obtained by the power generation calculation unit, combined with the heat recovery power calculated by the heat recovery power calculation unit; when calculating the heat storage power, it is necessary to consider the part of the heat recovery power that is not used for power generation and the heat loss of the heat exchange pipeline; when calculating the heat release power, it is necessary to consider the heat release efficiency of the chemical heat storage module and the current stored heat.

[0102] In order to further optimize the above embodiment, the proportion allocation unit calculates the ideal allocation ratio k x and (1-k x ) process is:

[0103] Calculate the remaining power P` for heat storage s，in ;

[0104] P s，in =P h，r -P g -P ORC

[0105] For the remaining power P` s，in Make a determination;

[0106] When P` s，in >0, set the first adjustment coefficient α and calculate the ideal allocation ratio k x :

[0107]

[0108] Further we get (1-kx);

[0109] When P` s，in ≤0, set the second adjustment coefficient β and calculate the ideal allocation ratio k x :

[0110]

[0111] Further we get (1-k x );

[0112] When P h，r ≤P g When , set the third adjustment coefficient γ and calculate the ideal allocation ratio kx:

[0113]

[0114] Further we get (1-kx);

[0115] The value ranges of the first adjustment coefficient α, the second adjustment coefficient β, and the third adjustment coefficient γ are {0, 1}, and the specific values ​​are pre-set based on actual conditions;

[0116] The ideal allocation ratio k x and (1-k x ) is sent to the proportional distribution unit to complete the heat distribution action.

[0117] It should be noted that the calculation of the remaining power P for heat storage is s，in It is to determine whether there is excess heat in the current system that can be stored;

[0118] When P` s，in When >0, the system has excess heat that can be used for heat storage. The principle of the corresponding formula is to adjust the proportion allocated to the organic Rankine cycle module based on the power generation, the difference between the power demand of the grid and the power generation, and the adjustment coefficient. If it is larger, it means that the proportion of the organic Rankine cycle module is more inclined to be adjusted according to the power grid demand; if it is smaller, it pays more attention to the current power generation situation.

[0119] When P` s，in When ≤0, the system has no excess heat for heat storage, and may even need to obtain heat from the heat storage module to meet the grid demand; the principle of the corresponding formula is to adjust the proportion allocated to the organic Rankine cycle module according to the difference between the generated power and the grid demand power and the adjustment coefficient to meet the grid demand;

[0120] When P h，r ≤P g When the heat recovery power is less than or equal to the power demand of the power grid for waste heat, the system should give priority to meeting the power grid demand; the principle of the corresponding formula is to appropriately adjust the proportion allocated to the organic Rankine cycle module based on the relationship between the generated power and the power demand of the power grid and the adjustment coefficient on the basis of giving priority to meeting the power grid demand;

[0121] Specifically, the setting of the first adjustment coefficient α mainly considers the emphasis of the system on the power adjustment of the organic Rankine cycle module and the chemical heat storage module; if it is desired to adjust the power of the organic Rankine cycle module more to meet the power grid demand, α can take a larger value, such as 0.6, which means that when calculating the ideal allocation ratio, more emphasis will be placed on allocating heat according to the power adjustment demand of the organic Rankine cycle module;

[0122] The second adjustment coefficient β is set mainly to consider how to adjust the proportion of the organic Rankine cycle module to meet the grid demand when the waste heat is insufficient to meet the heat storage demand; if γ is large, such as 0.8, it means that in this case, it is more inclined to adjust the proportion of the organic Rankine cycle module to a greater extent according to the difference between the grid demand and the current power generation of the organic Rankine cycle module to ensure that the grid demand is met;

[0123] The setting of the third adjustment coefficient γ mainly considers how to give priority to meeting the grid demand while appropriately adjusting the allocation ratio according to the difference between the generated power and the grid demand power and the heat storage state of the chemical heat storage module when the heat recovery power is less than or equal to the grid demand power; if δ takes a small value, such as 0.2, it means that in this case, although the grid demand is given priority to allocating heat to the organic Rankine cycle module, the adjustment range is relatively small, that is, it is more inclined to maintain the current operating state of the organic Rankine cycle module, and the heat storage state of the chemical heat storage module will also be appropriately considered for fine-tuning.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A waste heat utilization system based on energy saving and emission reduction of thermal power plants, characterized in that: The system comprises: Heat pipe heat exchange module, installed in the exhaust pipe of thermal power plant, used to recover the waste heat of flue gas; An organic Rankine cycle module, connected to the heat pipe heat exchange module, for converting the recovered waste heat into electrical energy; A chemical heat storage module, connected to the heat pipe heat exchange module, for storing excess heat or releasing heat when the waste heat supply is sufficient and the organic Rankine cycle module cannot be fully utilized; A power grid demand acquisition module is used to obtain the power demand of the current power grid for waste heat; The intelligent control module is electrically connected to the heat pipe heat exchange module, the organic Rankine cycle module, the chemical heat storage module and the grid demand acquisition module, respectively, and is used to monitor system parameters and automatically switch the heat distribution ratio according to the system parameters and the current grid demand power.

2. The waste heat utilization system based on energy saving and emission reduction of thermal power plants according to claim 1 is characterized in that: The heat pipe heat exchange module comprises: a heat exchange pipeline, connected to the input ends of the organic Rankine cycle module and the chemical heat storage module respectively, for obtaining heat from the flue gas and delivering the heat to the organic Rankine cycle module and the chemical heat storage module respectively; A flow monitor, arranged at the inlet of the heat exchange pipe, for obtaining the flue gas mass flow rate passing through the heat exchange pipe in real time; wherein the flue gas mass flow rate represents the mass of flue gas passing through per unit time; A temperature monitor is provided at the inlet and outlet of the heat exchange pipe, and is used to obtain the ambient temperature and the temperature of the flue gas when it enters and leaves the heat exchange pipe in real time; The flow splitting unit is arranged at the end of the heat exchange pipe and is used to control the ratio of heat distributed to the organic Rankine cycle module and the chemical heat storage module.

3. The waste heat utilization system based on energy saving and emission reduction of thermal power plants according to claim 2 is characterized in that: The organic Rankine cycle module includes an evaporator, an expander, a generator, a condenser and a working fluid pump; the evaporator is used to receive the heat transferred by the heat exchange pipeline, the expander and the working fluid pump are used to drive the generator to operate and convert the energy of the working fluid into electrical energy; the condenser is used to quickly cool the working fluid and provide working conditions for the working fluid pump.

4. The waste heat utilization system based on energy saving and emission reduction of thermal power plants according to claim 2 is characterized in that: The intelligent control module comprises: A heat recovery power calculation unit, connected to the flow monitor and the temperature monitor, for calculating the heat recovery power Ph,r based on the flue gas mass flow and the flue gas temperature; The power generation calculation unit is connected to the heat recovery power calculation unit and the diversion unit, and is used to calculate the power based on the heat recovery power P h，r Calculate the power generation P based on the current allocation ratio ORC ; The heat storage power calculation unit is connected to the temperature monitoring meter and the power generation calculation unit, and is used to calculate the power based on the heat recovery power P h，r and ambient temperature and power generation P ORC Calculate the heat storage power P s，in and heat release power P s，out ; A proportional distribution unit is connected to the heat recovery power calculation unit, the power generation power calculation unit, the heat storage and release power calculation unit and the grid demand acquisition module, and is used to calculate the power based on the current heat recovery power P h，r , power generation P ORC , heat storage power P s，in , heat release power P s，out and the power grid's demand for waste heat P g Calculate the ideal allocation ratio k x and (1-k x ); wherein kx is the proportion allocated to the organic Rankine cycle module, (1-k x ) is the proportion allocated to the chemical heat storage module.

5. The waste heat utilization system based on energy saving and emission reduction of thermal power plants according to claim 4 is characterized in that: The heat recovery power calculation unit calculates the heat recovery power P by the following formula h，r : Among them, P h，r is the heat recovery power; C p is the specific heat capacity of flue gas, which indicates the amount of heat absorbed by a unit mass of flue gas when its temperature rises by a unit; is the flue gas mass flow rate; T f，in and T f，out are the temperatures of the flue gas when it enters and leaves the heat exchange pipe, respectively.

6. The waste heat utilization system based on energy saving and emission reduction of thermal power plants according to claim 4 is characterized in that: The power generation calculation unit calculates the power generation P by the following formula ORC : P ORC =η ORC *(P h，r *t*k0) Among them, P ORC is the power generation; η ORC is the efficiency of the organic Rankine cycle module; t is the duration of flue gas emission; k0 is the proportion allocated to the organic Rankine cycle module in the initial state.

7. The waste heat utilization system based on energy saving and emission reduction of thermal power plants according to claim 4 is characterized in that: The heat storage power calculation unit calculates the heat storage power P by the following formula s，in and heat release power P s，out : P s，out =η s *∫P s，in dt Among them, P s，in is the heat storage power, P s，out is the heat release power; represents the power loss, where j loss is the heat loss coefficient of the heat exchange pipe, A is the average cross-sectional area of ​​the heat exchange pipe, T hot is the average flue gas temperature, T amb is the ambient temperature; η s is the heat release efficiency of the chemical heat storage module; ∫P s，in dt represents the heat currently stored in the chemical heat storage module.

8. The waste heat utilization system based on energy saving and emission reduction of thermal power plants according to claim 4 is characterized in that: The proportion allocation unit calculates the ideal allocation ratio k x and (1-k x ) process includes: The remaining power P' for heat storage is calculated by the following formula: s，in : P` s，in =P h，r -P g -P ORC ; For the remaining power P` s，in Make a judgment: When P` s，in >0, set the first adjustment coefficient α, and calculate the ideal allocation ratio k by the following formula x and (1-k x ): When P` s，in ≤0, set the second adjustment coefficient β, and calculate the ideal distribution ratio k by the following formula x and (1-k x ): When P h，r ≤P g When the third adjustment coefficient γ is set, the ideal distribution ratio k is calculated by the following formula x and (1-k x ): The value ranges of the first adjustment coefficient αα, the second adjustment coefficient β, and the third adjustment coefficient γ are {0, 1}; The ideal allocation ratio k x and (1-k x ) is sent to the proportional allocation unit.

9. A waste heat utilization system based on energy saving and emission reduction in thermal power plants according to any one of claims 1 to 8, characterized in that: The chemical heat storage module comprises a heat storage container and a reversible chemical reactant arranged in the heat storage container; the reversible chemical reactant is used to absorb and store heat or release heat.

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