Power grid-friendly circular cooler waste heat cascade control system and method

Abstract

The invention discloses a power grid friendly circular cooler waste heat cascade control system and method, relates to the technical field of circular coolers, and solves the technical problems that a traditional sintering circular cooler waste heat power generation system is insufficient in utilization of low-temperature flue gas, the energy utilization efficiency is low, and then negative influences are generated on the operation stability of a power grid. The high-temperature power generation module recycles high-temperature flue gas and medium-temperature flue gas, and waste heat steam is generated to drive the turbine to generate power; the low-temperature power generation module recovers low-temperature smoke, generates waste heat steam and conveys the waste heat steam to the high-temperature power generation module; the absorption refrigeration module recovers redundant flue gas and converts the redundant flue gas into cold water for storage; through gradient utilization of flue gas waste heat, stable output of electric power is achieved, impact on a power grid is reduced, the waste heat recovery and utilization rate is improved, the generating capacity is improved, meanwhile, the stability of the power grid is enhanced, and the system is particularly suitable for power grid operation under the condition that new energy installation is greatly increased.

Description

Technical Field

[0001] The invention belongs to the field of annular cooler, and particularly relates to a cascade control system and method for the waste heat of an electric power grid-friendly annular cooler. Background Art

[0002] The waste heat power generation system of a sintering annular cooler is a key link for energy conservation and consumption reduction in a steel plant. In existing waste heat power generation systems of sintering annular coolers, high-temperature and medium-temperature flue gases are introduced into a waste heat boiler to produce two streams of steam with different pressures, which are then introduced into a high-temperature steam turbine to drive the high-temperature steam turbine to do work and output electric energy. Due to the changes in the temperature and flow rate of the flue gas, the output electric energy fluctuates, and the fluctuation range is relatively large due to the changes in the external environment, which has a large impact on the power grid. Moreover, sometimes the impact is greater because the parameters of the medium-temperature flue gas are relatively high or low. At the same time, there may still be a large amount of heat in the tail gas of the waste heat boiler that has not been utilized, and the flue gas at the end of the annular cooler is abandoned, resulting in a large proportion of the overall waste heat not being utilized, causing low energy utilization efficiency and having a negative impact on the operation stability of the power grid and the steel plant. Therefore, the invention provides a cascade control system and method for the waste heat of an electric power grid-friendly annular cooler. Summary of the Invention

[0003] The invention aims to solve at least one of the technical problems existing in the prior art; for this purpose, the invention provides a cascade control system and method for the waste heat of an electric power grid-friendly annular cooler, which is used to solve the technical problems that the traditional waste heat power generation system of a sintering annular cooler has insufficient utilization of low-temperature flue gas, resulting in low energy utilization efficiency and further having a negative impact on the operation stability of the power grid.

[0004] To achieve the above object, the first aspect of the invention provides a cascade control system for the waste heat of an electric power grid-friendly annular cooler, which includes a high-temperature power generation module, a low-temperature power generation module, and an absorption refrigeration module; High-temperature power generation module: used to recover the high-temperature and medium-temperature flue gases of the annular cooler equipment and generate waste heat steam to be transported to a driving turbine for power generation; Low-temperature power generation module: used to recover the low-temperature flue gas of the annular cooler equipment and transport the generated waste heat steam to the high-temperature power generation module; Absorption refrigeration module: used to recover the flue gases discharged by the high-temperature power generation module and the low-temperature power generation module, absorb and refrigerate the heat of the discharged flue gases, and convert it into cold water for storage.

[0005] Preferably, the high-temperature power generation module includes a high-temperature flue gas circulation channel composed of a high-temperature flue, a high-temperature waste heat boiler, a high-temperature steam turbine, a turbine generator, a condenser, a pressurizing pump, and a third valve connected in sequence; A medium-temperature flue gas circulation channel composed of a medium-temperature flue, a high-temperature waste heat boiler, a high-temperature steam turbine, a turbine generator, a condenser, a pressurizing pump, and a third valve; Among them, the high-temperature flue gas enters the high-temperature flue, and the medium-temperature flue gas enters the medium-temperature flue.

[0006] Preferably, the output ends of the high-temperature flue and the medium-temperature flue are respectively connected to the input end of the high-temperature waste heat boiler, and a third valve is arranged between the connecting pipeline of the medium-temperature flue and the high-temperature waste heat boiler; a circulation pipeline is sequentially formed among the high-temperature steam turbine, the condenser and the high-temperature waste heat boiler, and a pressure pump is arranged on the pipeline between the high-temperature waste heat boiler and the condenser.

[0007] Preferably, the low-temperature power generation module includes a low-temperature flue gas circulation passage formed by sequentially connecting a low-temperature flue, a low-temperature waste heat boiler, an ORC power generation main engine and a low-temperature circulation pump; among them, the low-temperature flue gas enters the low-temperature flue.

[0008] Preferably, a first valve is arranged between the connecting pipeline of the low-temperature flue and the low-temperature waste heat boiler, and a circulation channel is formed among the low-temperature waste heat boiler, the ORC power generation main engine and the low-temperature circulation pump.

[0009] Preferably, the absorption refrigeration module includes an absorption refrigerating machine and a cold storage container which are communicated with each other, and a cooling tower communicated with the output end of the absorption refrigerating machine; a chilled water circulation pump is arranged on the connecting pipeline between the output end of the cold storage container and the input end of the absorption refrigerating machine, a cooling water pump is connected to the output end of the cooling tower, and a condenser water pump is connected to the output end of the cold storage container.

[0010] Preferably, the output end of the condenser water pump is connected to the input end of the condenser, the output end of the cooling water pump is respectively communicated with the input end of the condenser and the input end of the ORC power generation main engine, and an eighth valve is further arranged on the connecting pipeline between the output end of the cooling water pump and the ORC power generation main engine; a sixth valve is further arranged on the connecting pipeline between the output end of the cooling water pump and the input end of the condenser; a seventh valve is further arranged on the connecting pipeline between the output end of the cooling water pump and the input end of the absorption refrigerating machine.

[0011] Preferably, the input end of the absorption refrigerating machine is respectively communicated with the output end of the high-temperature waste heat boiler and the output end of the low-temperature waste heat boiler, and a fourth valve is arranged between the connecting pipeline of the output end of the low-temperature waste heat boiler and the input end of the absorption refrigerating machine; The output end of the ORC power generation main engine is communicated with the input end of the cooling tower; The output end of the condenser is communicated with the input end of the cooling tower; A second valve is arranged between the medium-temperature flue and the low-temperature flue; The output end of the low-temperature waste heat boiler is communicated with the input end of the high-temperature waste heat boiler, and a fifth valve is further arranged on the connecting pipeline between the output end of the low-temperature waste heat boiler and the input end of the high-temperature waste heat boiler.

[0012] In a second aspect of the present invention, a method for cascade control of waste heat of an electric - friendly annular cooler is provided, including a control method for a high - temperature power generation module and a control method for a low - temperature power generation module.

[0013] Preferably, the control method for the high - temperature power generation module includes: The flue gas discharged from the high - temperature flue and the medium - temperature flue enters the high - temperature waste - heat boiler. The high - temperature waste - heat boiler recovers the heat of the high - temperature flue gas and the low - temperature flue gas, generates two streams of steam with different pressures and enters the main steam inlet and the supplementary steam inlet of the high - temperature steam turbine respectively. The high - temperature steam turbine does work to drive the turbo - generator to generate electricity; the exhaust steam after the high - temperature steam turbine does work enters the condenser and condenses into a liquid, and then after passing through a pressurizing pump, it re - enters the high - temperature waste - heat boiler to be heated and undergoes a power - generation cycle; The control method for the low - temperature power generation module includes the following steps: The flue gas discharged from the low - temperature flue enters the low - temperature waste - heat boiler. The low - temperature waste - heat boiler heats the low - temperature flue gas to generate steam and hot water. The steam enters the high - temperature waste - heat boiler to de - oxygenate the boiler water, and the hot water enters the ORC power generation main engine for heat exchange. The hot water after heat exchange re - enters the waste - heat boiler to be heated into steam and hot water and undergoes a reciprocating cycle.

[0014] According to the present invention, according to the changes in the ambient temperature and the output of the high - temperature power generation module, the flue gas of the high - temperature flue, the medium - temperature flue and the low - temperature flue is output to the high - temperature waste - heat boiler of the high - temperature power generation module and the low - temperature waste - heat boiler of the low - temperature power generation module through different flow paths; wherein, the steam generated by the low - temperature waste - heat boiler of the low - temperature waste - heat power generation system is controlled by a fifth valve to output different flow rates to the hot - water de - oxygenator of the high - temperature power generation module; by adjusting each valve, the stability of the output of the high - temperature power generation module is ensured, and thus the stability of the power grid is guaranteed; In addition, the high - temperature power generation module and the low - temperature power generation module are organically combined, and a medium - temperature flue - gas heat source is introduced to realize the cascade utilization of energy. Moreover, by precisely adjusting the flow rate and heat distribution of the medium - temperature flue gas entering the high - temperature and low - temperature power generation modules through valves, the optimization of energy utilization is ensured; at the same time, the chilled water produced by the absorption refrigeration system is introduced into the high - temperature power generation module, further improving the overall efficiency of the system. In addition, the flue gas discharged from the high - temperature and low - temperature power generation modules is transported to the absorption refrigeration system as a heat source to drive the refrigeration unit, realizing the reuse of waste heat.

[0015] Compared with the prior art, the beneficial effects of the present invention are: The present invention mainly includes a high-temperature power generation module, a low-temperature power generation module, and an absorption refrigeration module. The high-temperature power generation module is similar to the traditional one, with the difference that it enters the low-temperature power generation module from the low-temperature flue gas, and the waste heat steam generated by the low-temperature waste heat boiler is sent to the high-pressure deaeration part of the high-temperature power generation module to improve the power generation efficiency of the high-temperature power generation module. At the same time, the low-temperature power generation module generates electricity by itself, improving the waste heat power generation of the annular cooler. By controlling the gas production of the low-temperature waste heat boiler, the fluctuations of the high-temperature power generation module are adjusted to suppress the grid fluctuations. Moreover, through the flexible configuration of the flue gas and the two waste heat boilers, and further utilization of the flue gas waste heat, the effective migration of the heat source or medium is realized, the volatility of power generation and grid connection is reduced, and the stable output of electricity is achieved. The stable output of sinter ring cooler power generation is realized through an efficient control logic, improving the waste heat recovery utilization rate and waste heat power generation, while reducing the impact on the grid, ensuring the stable output of the power generation system, enhancing the stability of the grid, and being beneficial to the operation of the microgrid, especially having a positive significance for the grid operation limit in the case of a large increase in new energy installed capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a schematic diagram of a traditional sinter ring cooler waste heat power generation system; Figure 2 It is a schematic diagram of the sinter ring cooler cascade coupling power generation system of the present invention; Figure 3 It is a schematic diagram of the sinter ring cooler cascade deep recovery and utilization system of the power grid-friendly power generation system of the present invention; In the figure: 11. High-temperature flue gas; 12. Medium-temperature flue gas; 13. Low-temperature flue gas; 21. High-temperature waste heat boiler; 22. High-temperature steam turbine; 23. Turbine generator; 24. Condenser; 31. Low-temperature waste heat boiler; 32. ORC power generation main engine; 41. Absorption refrigerator; 42. Cold storage container; 51. Cooling tower; 61. First valve; 62. Second valve; 63. Third valve; 64. Fourth valve; 65. Fifth valve; 66. Sixth valve; 67. Seventh valve; 68. Eighth valve; 81. Booster pump; 82. Low-temperature circulation pump; 83. Chilled water circulation pump; 84. Condenser water pump; 85. Cooling water pump. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0019] The traditional waste heat power generation system of the ring cooler is as Figure 1 shown. The high-temperature flue gas and the medium-temperature flue gas enter the high-temperature waste heat boiler 21 through the high-temperature flue 11 and the medium-temperature flue 12 respectively. The high-temperature waste heat boiler 21 uses the heat of the high-temperature flue gas and the medium-temperature flue gas to generate two different-pressure steams. Subsequently, the steam enters the high-temperature steam turbine 22 to drive the turbo generator 23 to generate electricity. The exhaust steam after the high-temperature steam turbine 22 does work enters the condenser 24 and condenses into a liquid. Then, after passing through the pressure pump 81, it re-enters the high-temperature waste heat boiler 21 to be heated and undergoes a power generation cycle. However, there are many problems in the actual operation of this system, resulting in low energy utilization efficiency and having an adverse impact on the stable operation of the power grid and the steel plant.

[0020] First of all, due to the uneven composition and particle size distribution of the materials during the sintering process, the temperature and flow rate of the flue gas fluctuate significantly. This fluctuation directly affects the steam output and parameter stability of the high-temperature waste heat boiler 21, and further leads to the fluctuation of the output power of the high-temperature steam turbine 22. The fluctuation of the output power of the turbo generator 23 not only reduces the power generation efficiency but also causes an unfriendly impact on the power grid. The power grid needs to be adjusted frequently to cope with this fluctuation, increasing the difficulty of power grid dispatching and even possibly affecting the stable power supply of other electricity users. Secondly, the traditional waste heat power generation system of the ring cooler has insufficient utilization of low-temperature flue gas. The low-temperature flue gas is directly discharged after power generation, and it still contains a large amount of unused low-temperature heat. If this part of the heat can be effectively recovered, the overall energy utilization efficiency of the system can be further improved. However, due to technical and equipment limitations, this part of the heat is usually directly discharged into the atmosphere, causing serious energy waste. In addition, the flue gas at the end of the ring cooler is also often directly discharged without being effectively utilized. Although the temperature of this part of the flue gas is relatively low, if appropriate heat recovery technologies such as heat pipe heat exchangers and organic Rankine cycle systems are used, some heat can still be recovered for power generation or other uses. However, the traditional waste heat power generation system of the ring cooler usually ignores the recovery and utilization of this part of the flue gas, further reducing the overall waste heat recovery efficiency.

[0021] The present invention effectively suppresses the output fluctuation of the power grid by utilizing the flue gas of the sintering ring cooler system in segments and subsystems and extending the chain of cascade utilization. The sintering ring cooler system of the present invention mainly includes the original high-temperature power generation system, the newly added low-temperature power generation system, the absorption refrigeration system for realizing gradient utilization, and the control part, etc.

[0022] An embodiment of the first aspect of the present invention provides a power grid-friendly ring cooler waste heat cascade control system, including a high-temperature power generation module, a low-temperature power generation module, and an absorption refrigeration module; The high-temperature power generation module recovers the high-temperature flue gas and medium-temperature flue gas of the ring cooler equipment to generate waste heat steam; the waste heat steam drives a turbine to generate electricity and transmits the electric energy to the power grid; Among them, the ring cooler equipment includes a high-temperature flue 11, a medium-temperature flue 12, and a low-temperature flue 13. The high-temperature flue gas is the flue gas entering the high-temperature flue 11, the medium-temperature flue gas is the flue gas entering the medium-temperature flue 12, and the low-temperature flue gas is the flue gas entering the low-temperature flue 13; It should be noted that the temperature range of the high-temperature flue gas is greater than or equal to 400 °C, the temperature range of the medium-temperature flue gas is [200 °C, 400 °C], and the temperature range of the low-temperature flue gas is less than or equal to 200 °C.

[0023] Specifically, please refer to Figures 2 - 3 , the high-temperature power generation module includes a high-temperature flue gas circulation channel formed by sequentially connecting a high-temperature flue 11, a high-temperature waste heat boiler 21, a high-temperature steam turbine 22, a turbo generator 23, a condenser 24, a pressure pump 81, and a third valve 63; A medium-temperature flue gas circulation channel formed by a medium-temperature flue 12, a high-temperature waste heat boiler 21, a high-temperature steam turbine 22, a turbo generator 23, a condenser 24, a pressure pump 81, and a third valve 63; Among them, the output ends of the high-temperature flue 11 and the medium-temperature flue 12 are respectively communicated with the input end of the high-temperature waste heat boiler 21, and a third valve 63 is arranged between the communication pipeline of the medium-temperature flue 12 and the high-temperature waste heat boiler 21; a circulation pipeline is sequentially formed among the high-temperature steam turbine 22, the condenser 24, and the high-temperature waste heat boiler 21, and a pressure pump 81 is arranged on the pipeline between the high-temperature waste heat boiler 21 and the condenser 24.

[0024] The control method of the high-temperature power generation module includes the following steps: The flue gas discharged from the high-temperature flue 11 and the medium-temperature flue 12 enters the high-temperature waste heat boiler 21. The high-temperature waste heat boiler 21 recovers the heat of the high-temperature flue gas and the low-temperature flue gas, generates two streams of steam with different pressures and enters the main steam port and the secondary supplementary steam port of the high-temperature steam turbine 22 respectively. The high-temperature steam turbine 22 does work to drive the turbo generator 23 to generate electricity; the exhaust steam after the high-temperature steam turbine 22 does work enters the condenser 24 and is condensed into a liquid, and then re-enters the high-temperature waste heat boiler 21 after passing through the pressure pump 81 to be heated, and the power generation cycle is carried out.

[0025] The low-temperature power generation module recovers the low-temperature flue gas, generates waste heat steam, and transports the waste heat steam to the high-temperature power generation module; Specifically, please refer to Figures 2 - 3 , the low-temperature power generation module includes a low-temperature flue gas circulation passage composed of a low-temperature flue 13, a low-temperature waste heat boiler 31, an ORC power generation main engine 32 and a low-temperature circulation pump 82 connected in sequence.

[0026] Among them, a first valve 61 is arranged between the connecting pipeline of the low-temperature flue 13 and the low-temperature waste heat boiler 31, and a circulation passage is formed among the low-temperature waste heat boiler 31, the ORC power generation main engine 32 and the low-temperature circulation pump 82.

[0027] The control method of the low-temperature power generation module includes the following steps: The flue gas discharged from the low-temperature flue 13 enters the low-temperature waste heat boiler 31. The low-temperature waste heat boiler 31 heats the low-temperature flue gas to generate steam and hot water. The steam enters the high-temperature waste heat boiler 21 to deoxidize the boiler water, and the hot water enters the ORC power generation main engine 32 for heat exchange. The heat-exchanged hot water re-enters the low-temperature waste heat boiler 31 to be heated into steam and hot water, and the cycle repeats.

[0028] The present invention realizes the stable power output of the power generation system through the coordinated regulation of the high-temperature power generation module and the low-temperature power generation module. Specifically, when the flue gas temperatures of the high-temperature flue 11 and the medium-temperature flue 12 decrease, the power generation efficiency of the high-temperature power generation module decreases accordingly. At this time, the system automatically adjusts the steam flow of the low-temperature waste heat boiler 31 and compensates for the power loss of the high-temperature power generation module by increasing the steam supply. Since the installed capacity of the low-temperature power generation module is differentially configured with that of the high-temperature power generation module, its adjustment ability can effectively offset the fluctuations in the power generation on the high-temperature side, thereby maintaining the stability of the total system output power and reducing the impact on the power grid. This control strategy is based on a temperature-power dynamic response model. By adjusting the steam flow in real time, the power generation of the high-temperature power generation module can still maintain positive correction when the flue gas temperature fluctuates, ensuring the smooth operation of the overall power generation system.

[0029] The absorption refrigeration module recovers the flue gas discharged from the high-temperature power generation module and the low-temperature power generation module, that is, the unused excess flue gas, absorbs and refrigerates the heat of the discharged flue gas and converts it into cold water for storage.

[0030] Specifically, please refer to Figure 3 , the absorption refrigeration module includes an absorption chiller 41 and a cold storage container 42 that are interconnected, and a cooling tower 51 that is connected to the output end of the absorption chiller 41; a chilled water circulation pump 83 is provided on the connecting pipeline between the output end of the cold storage container 42 and the input end of the absorption chiller 41, the output end of the cooling tower 51 is connected to a cooling water pump 85, and the output end of the cold storage container 42 is connected to a condenser water pump 84.

[0031] Among them, the output end of the condenser water pump 84 is connected to the input end of the condenser 24, the output end of the cooling water pump 85 is respectively connected to the input end of the condenser 24 and the input end of the ORC power generation main engine 32, and an eighth valve 68 is also provided on the connecting pipeline between the output end of the cooling water pump 85 and the ORC power generation main engine 32; a sixth valve 66 is also provided on the connecting pipeline between the output end of the cooling water pump 85 and the input end of the condenser 24.

[0032] And, the input end of the absorption chiller 41 is respectively connected to the output end of the high-temperature waste heat boiler 21 and the output end of the low-temperature waste heat boiler 31, and a fourth valve 64 is provided between the connecting pipelines between the output end of the low-temperature waste heat boiler 31 and the input end of the absorption chiller 41; The output end of the ORC power generation main engine 32 is connected to the input end of the cooling tower 51; The output end of the condenser 24 is connected to the input end of the cooling tower 51; A second valve 62 is provided between the medium-temperature flue 12 and the low-temperature flue 13; The output end of the low-temperature waste heat boiler 31 is connected to the input end of the high-temperature waste heat boiler 21, and a fifth valve 65 is also provided on the connecting pipeline between the output end of the low-temperature waste heat boiler 31 and the input end of the high-temperature waste heat boiler 21.

[0033] The present invention realizes the efficient cascade utilization and intelligent regulation of energy by constructing a multi-temperature gradient waste heat power generation system. The system dynamically adjusts the flue gas flow directions of the high-temperature flue 11, the medium-temperature flue 12, and the low-temperature flue 13 according to the environmental temperature change and the output characteristics of the high-temperature power generation module, and respectively conveys them to the high-temperature waste heat boiler 21 and the low-temperature waste heat boiler 31 to form a differential heat energy utilization path, and the steam generated by the low-temperature waste heat boiler 31 is accurately regulated in flow rate through a valve and coupled with the deaerator in the high-temperature waste heat boiler 21 to ensure the stable output of the high-temperature power generation module and guarantee the reliability of the power grid.

[0034] In addition, by introducing medium-temperature flue gas as a supplementary heat source and using a valve combination to achieve intelligent allocation of high / low-temperature power generation modules, the scope of heat source utilization is expanded, and a thermal energy cascade effect is formed. Moreover, in the absorption refrigeration technology, the flue gas discharged from the high-temperature power generation module is used as the driving heat source to produce chilled water, which feeds back to the high-temperature power generation module to improve efficiency. At the same time, the waste heat of the flue gas from the low-temperature power generation module is used to drive the absorption refrigeration module, forming a "heat-electricity-cooling" combined heat and power cycle. Through multi-parameter coupling regulation and energy cascade conversion, the total thermal efficiency of the system is improved, and the energy utilization is optimized under all working conditions, providing a technical solution with both flexibility and economy for distributed energy systems.

[0035] The working process of the absorption refrigeration module includes the following steps: The flue gas discharged from the medium-temperature flue enters the low-temperature waste heat boiler 31. The flue gas discharged from the high-temperature waste heat boiler 21 and the low-temperature waste heat boiler 31 enters the absorption chiller 41. The absorption chiller 41 produces chilled water, which is stored in the chilled water storage container through the chilled water circulation pump 83. The chilled water in the chilled water storage container 42 enters the condenser 24 through the condenser water pump 84.

[0036] In this embodiment, the third valve 63 adjusts the flue gas volume of the medium-temperature flue gas entering the high-temperature waste heat boiler 21, and the second valve 62 adjusts the flue gas volume entering the low-temperature waste heat boiler 31. When all equipment is started, the cooling tower 51 adjusts the flow rate through the cooling water pump 85 and adjusts the cooling capacity of the absorption chiller 41 through the seventh valve 67; The cooling capacity of the condenser 24 is adjusted through the sixth valve 66, and the cooling capacity of the ORC power generation main engine 32 is adjusted through the eighth valve 68.

[0037] Assuming that the average power generation power within a cycle is used as a benchmark, when the high-temperature power generation power is lower than the preset power threshold, the second valve 62 is adjusted to a smaller value or even closed, and the fifth valve 65 is adjusted to a larger value. The output power of the high-temperature waste heat power generation module will increase, and the condenser water pump 84 is started to reduce the inlet water temperature of the condenser 24; wherein, the length of a cycle can be set by those skilled in the art according to the actual situation.

[0038] When the high-temperature power generation power is higher than the preset power threshold, the fifth valve 65 is adjusted to a smaller value or even closed, and the second valve 62 is adjusted to a larger value.

[0039] When it is detected that the flue gas temperatures of the high-temperature flue 11, the medium-temperature flue 12 and the tail gas temperature at the outlet of the high-temperature waste heat boiler 21 are all greater than the corresponding preset temperatures, the flue gas will enter the absorption chiller 41 for refrigeration and storage.

[0040] When the temperature of the low-temperature flue gas and the temperature of the tail gas at the outlet of the low-temperature waste heat boiler 31 are both lower than the corresponding preset temperatures, the fourth valve 64 closes to ensure the stable heat source temperature of the absorption chiller 41, preventing the main engine from shutting down due to excessively low temperature.

[0041] The present invention adds a low-temperature power generation module. Aiming at the problem that the low-temperature flue gas in the traditional system is not fully utilized, through the technology of heat pipe heat exchanger or ORC power generation main engine 32, the waste heat of the low-temperature flue gas is converted into electric energy, improving the overall power generation. To further extend the cascade utilization chain, the present invention also introduces an absorption refrigeration module. Using the waste heat of medium- and low-temperature flue gas to drive the refrigeration unit, the chilled water produced can be used for cooling requirements in the steel plant, such as equipment cooling and workshop cooling, thus reducing the consumption of external power. This combined cooling and power supply method realizes the efficient comprehensive utilization of energy.

[0042] By monitoring the flue gas temperature, flow rate, steam parameters, and power generation output power, the system of the present invention can dynamically adjust the operating states of each subsystem. For example, when the flue gas temperature is high, priority is given to using high-temperature flue gas for power generation; when the flue gas temperature is low, the low-temperature power generation module or the absorption refrigeration module is started. In addition, the system is also equipped with energy storage devices such as battery energy storage or heat storage systems to smooth out the power generation output fluctuations and ensure the stability of power supply. The present invention not only improves the utilization rate of waste heat resources but also significantly reduces the volatility of the power generation system and enhances the friendliness to the power grid through multi-stage energy recovery and intelligent control. At the same time, it provides technical support for the energy conservation, emission reduction, and carbon neutrality goals of the steel plant.

[0043] The preset parameters and preset thresholds of the present invention are set by those skilled in the art according to the actual situation or obtained through a large amount of data simulation.

[0044] The above embodiments are only used to illustrate the technical method of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical method of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A grid-friendly ring cooler waste heat cascade control system, characterized in that: It includes a high-temperature power generation module, a low-temperature power generation module and an absorption refrigeration module; High-temperature power generation module: used to recover high-temperature flue gas and medium-temperature flue gas from the ring cooler equipment, and generate waste heat steam to drive the turbine for power generation; Low-temperature power generation module: used to recover the low-temperature flue gas from the ring cooler equipment and transport the waste heat steam to the high-temperature power generation module; Absorption refrigeration module: used to recover the flue gas emitted by the high-temperature power generation module and the low-temperature power generation module, absorb and cool the heat of the emitted flue gas and convert it into cold water for storage.

2. A grid-friendly ring cooler waste heat cascade control system according to claim 1, characterized in that: The high-temperature power generation module comprises a high-temperature flue gas flow channel composed of a high-temperature flue (11), a high-temperature waste heat boiler (21), a high-temperature steam turbine (22), a turbine generator (23), a condenser (24), a booster pump (81) and a third valve (63) connected in sequence; A medium-temperature flue gas flow channel composed of a medium-temperature flue (12), a high-temperature waste heat boiler (21), a high-temperature steam turbine (22), a turbine generator (23), a condenser (24), a booster pump (81) and a third valve (63); The high-temperature flue gas enters the high-temperature flue (11), and the medium-temperature flue gas enters the medium-temperature flue (12).

3. A grid-friendly ring cooler waste heat cascade control system according to claim 2, characterized in that: The output ends of the high-temperature flue (11) and the medium-temperature flue (12) are respectively connected to the input end of the high-temperature waste heat boiler (21), and a third valve (63) is provided between the connecting pipeline between the medium-temperature flue (12) and the high-temperature waste heat boiler (21); a circulation pipeline is formed in sequence between the high-temperature steam turbine (22), the condenser (24) and the high-temperature waste heat boiler (21), and a booster pump (81) is provided on the pipeline between the high-temperature waste heat boiler (21) and the condenser (24).

4. A grid-friendly ring cooler waste heat cascade control system according to claim 3, characterized in that: The low-temperature power generation module comprises a low-temperature flue gas circulation channel composed of a low-temperature flue (13), a low-temperature waste heat boiler (31), an ORC power generation host (32) and a low-temperature circulation pump (82) connected in sequence; wherein the low-temperature flue gas enters the low-temperature flue (13).

5. A grid-friendly ring cooler waste heat cascade control system according to claim 4, characterized in that: A first valve (61) is provided between the low-temperature flue (13) and the connecting pipeline of the low-temperature waste heat boiler (31), and a circulation pipeline is formed between the low-temperature waste heat boiler (31), the ORC power generation host (32) and the low-temperature circulation pump (82).

6. A grid-friendly ring cooler waste heat cascade control system according to claim 5, characterized in that: The absorption refrigeration module comprises an absorption refrigeration machine (41) and a cold storage container (42) which are interconnected, and a cooling tower (51) which is connected to the output end of the absorption refrigeration machine (41); a chilled water circulation pump (83) is provided on the connecting pipeline between the output end of the cold storage container (42) and the input end of the absorption refrigeration machine (41), the output end of the cooling tower (51) is connected to a cooling water pump (85), and the output end of the cold storage container (42) is connected to a condenser water pump (84).

7. A grid-friendly ring cooler waste heat cascade control system according to claim 6, characterized in that: The output end of the condenser water pump (84) is connected to the input end of the condenser (24); the output end of the cooling water pump (85) is respectively connected to the input end of the condenser (24) and the input end of the ORC power generation host (32); an eighth valve (68) is also provided on the connecting pipeline between the output end of the cooling water pump (85) and the ORC power generation host (32); a sixth valve (66) is also provided on the connecting pipeline between the output end of the cooling water pump (85) and the input end of the condenser (24); and a seventh valve (67) is also provided on the connecting pipeline between the output end of the cooling water pump (85) and the input end of the absorption refrigeration machine (41).

8. A grid-friendly ring cooler waste heat cascade control system according to claim 7, characterized in that: The input end of the absorption refrigeration machine (41) is respectively connected to the output end of the high-temperature waste heat boiler (21) and the output end of the low-temperature waste heat boiler (31), and a fourth valve (64) is provided between the connecting pipeline between the output end of the low-temperature waste heat boiler (31) and the input end of the absorption refrigeration machine (41); The output end of the ORC power generation host (32) is connected to the input end of the cooling tower (51); The output end of the condenser (24) is in communication with the input end of the cooling tower (51); A second valve (62) is provided between the medium-temperature flue (12) and the low-temperature flue (13); The output end of the low-temperature waste heat boiler (31) is connected to the input end of the high-temperature waste heat boiler (21), and a fifth valve (65) is also provided on the connecting pipeline between the output end of the low-temperature waste heat boiler (31) and the input end of the high-temperature waste heat boiler (21).

9. A power-friendly ring cooler waste heat cascade control method, based on the power-friendly ring cooler waste heat cascade control system according to any one of claims 4 to 8, characterized in that: It includes a control method for a high-temperature power generation module and a control method for a low-temperature power generation module.

10. A grid-friendly ring cooler waste heat cascade control method according to claim 9, characterized in that: The control method of the high temperature power generation module comprises: Flue gas discharged from the high-temperature flue (11) and the medium-temperature flue (12) enters the high-temperature waste heat boiler (21). The high-temperature waste heat boiler (21) recovers heat from the high-temperature flue gas and the low-temperature flue gas to generate two streams of steam with different pressures, which respectively enter the steam inlet and the supplementary steam port of the high-temperature steam turbine (22). The high-temperature steam turbine (22) performs work to drive the turbine generator (23) to generate electricity. Exhaust steam from the high-temperature steam turbine (22) after performing work enters the condenser (24) to be condensed into liquid, and then passes through the booster pump (81) and re-enters the high-temperature waste heat boiler (21) to be heated, thereby performing a power generation cycle. The control method of the low temperature power generation module comprises the following steps: Flue gas discharged from the low-temperature flue (13) enters the low-temperature waste heat boiler (31), the low-temperature waste heat boiler (31) heats the low-temperature flue gas to generate steam and hot water, the steam enters the high-temperature waste heat boiler (21) to deoxygenate the boiler water, the hot water enters the ORC power generation host (32) for heat exchange, and the hot water after heat exchange re-enters the low-temperature waste heat boiler (31) to be heated into steam and hot water, and the cycle repeats.

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