System and method for recovering waste heat of long-voyage ship

Abstract

The invention provides a system and method for recovering waste heat of a long-voyage ship. The system comprises a waste heat conveying assembly, a Rankine cycle assembly, an absorption type refrigeration cycle assembly and a heat storage type energy storage assembly. The input end of the Rankine cycle assembly and the input end of the heat storage type energy storage assembly are both connected with the waste heat conveying assembly, and the output end of the heat storage type energy storage assembly is connected with the Rankine cycle assembly and the absorption type refrigeration cycle assembly. The waste heat recovery system for the long-voyage ship not only can provide electric energy, but also can provide cold energy, so that the requirements of users can be better met; and meanwhile, through cooperation of the heat accumulating type energy storage assembly, the generating capacity and the refrigerating capacity of the heat accumulating type energy storage assembly can be produced according to the requirements of users, different from a traditional waste heat recovery system, the system energy is more efficient, and then the energy utilization efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of waste heat recovery of ships, and in particular to a waste heat recovery system and method for long-distance ships. Background Art

[0002] As the global ocean transport growth leads to an increasing number of ships, in traditional ship power systems, the waste heat emitted by the engine is usually simply discharged into the ocean, causing energy waste and environmental pollution. The country has introduced a dual carbon policy to solve the increasingly serious environmental problems. The shipping industry actively responds to the country's call to recycle the waste heat resources of ships.

[0003] At present, waste heat recovery of ships on the market usually only converts heat into electricity, heat into cold or electricity into cold, and the waste heat resource utilization rate is low. Moreover, the waste heat can only be utilized in the amount of heat generated by the engine, and the system can only generate as much electricity or cold as the system generates, and it is impossible to perform real-time regulation, resulting in a lot of wasted resources. Therefore, it is necessary to provide a waste heat recovery system and method for long-distance ships that can improve energy utilization efficiency to solve the above problems. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems raised in the above-mentioned background technology, and to provide a waste heat recovery system and method for long-distance ships capable of improving energy utilization efficiency.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A waste heat recovery system for a long-distance ship comprises a waste heat transport component, a Rankine cycle component, an absorption refrigeration cycle component and a thermal storage component; the input ends of the Rankine cycle component and the thermal storage component are both connected to the waste heat transport component, and the output end of the thermal storage component is connected to the Rankine cycle component and the absorption refrigeration cycle component.

[0007] Further, the waste heat transport assembly includes a main transport pipe, a main three-way valve, a first diverter pipe and a second diverter pipe, one end of the main transport pipe is connected to the inlet of the main three-way valve, one end of the first diverter pipe and one end of the second diverter pipe are respectively connected to two outlets of the main three-way valve, and a diverter control valve is installed on the first diverter pipe;

[0008] The Rankine cycle assembly includes a first heat exchanger, a second heat exchanger, an expander, a first condenser, a first liquid storage tank and a first solution pump; the first outlet of the first heat exchanger is connected to the first inlet of the first heat exchanger through a first circulation pipeline, and the second heat exchanger, the expander, the first condenser, the first liquid storage tank and the first solution pump are sequentially installed on the first circulation pipeline along the transmission direction of the first circulation pipeline; the second inlet of the first heat exchanger is connected to the other end of the first shunt pipe;

[0009] The absorption refrigeration cycle assembly includes a generator, a second condenser, a first throttle valve, an evaporator, an absorber, a second solution pump, a second throttle valve and a third heat exchanger, wherein the first outlet of the generator is connected to the first inlet of the generator through a second circulation pipeline, and the second condenser, the first throttle valve, the evaporator, the absorber, the second solution pump and the third heat exchanger are sequentially installed on the second circulation pipeline along the transmission direction of the second circulation pipeline; the third heat exchanger is also connected to the absorber through the second throttle valve; the second outlet of the generator is also connected to the third heat exchanger through a connecting pipeline;

[0010] The thermal storage energy storage component includes a fourth heat exchanger, a heat storage tank, a second liquid storage tank, a first switch valve, a third liquid storage tank, a first three-way valve, a second switch valve, a second three-way valve and a third switch valve. The first inlet of the fourth heat exchanger is connected to the other end of the second shunt pipe, the first outlet of the fourth heat exchanger is connected to the first inlet of the heat storage tank through the first pipeline, the first outlet of the heat storage tank is connected to the second inlet of the fourth heat exchanger through the second pipeline, and the second liquid storage tank and the first switch valve are both installed on the first pipeline; the second outlet of the heat storage tank is connected to the inlet of the third liquid storage tank, the outlet of the third liquid storage tank is connected to the inlet of the first three-way valve, the two outlets of the first three-way valve are respectively connected to one end of the first regulating pipeline and one end of the second regulating pipeline, the other end of the first regulating pipeline is connected to the second heat exchanger, and the second switch valve is installed on the first regulating pipeline; the other end of the second regulating pipeline is connected to the second inlet of the generator, and the third switch valve is installed on the second regulating pipeline; the two inlets of the second three-way valve are respectively connected to the third outlet of the second heat exchanger and the generator, and the outlet of the second three-way valve is connected to the second inlet of the heat storage tank through a collecting pipeline;

[0011] The main delivery pipe, the first circulation pipe, the second circulation pipe and the second regulating pipe are all equipped with flow sensors and temperature sensors. The first pipe is equipped with a temperature sensor, the second pipe is equipped with a flow sensor, the first regulating pipe is equipped with a flow sensor, and the collecting pipe is equipped with a temperature sensor.

[0012] The waste heat recovery system for long-distance ships also includes a controller, which is connected to a plurality of flow sensors, a plurality of temperature sensors, a diversion control valve, a first switch valve, a second switch valve and a third switch valve to distribute the working fluid flow for power generation, power generation supplementary heat and refrigeration cycle.

[0013] Furthermore, when the Rankine cycle component is working, the exhaust gas discharged by the engine enters the first heat exchanger after passing through the main delivery pipe and the first branch pipe. The working medium absorbs the heat from the exhaust gas discharged by the engine in the first heat exchanger. Then the working medium comes to the second heat exchanger to absorb the heat transferred from the heat storage device and is heated to a high-temperature gas state. The gaseous working medium runs to the expander, and the expander is connected to a steam turbine. The working medium after passing through the expander is used to drive the steam turbine to rotate. The rotor of the steam turbine is connected to the generator, so that the generator also rotates together, thereby generating electrical energy. The working medium that has lost energy passes through the first condenser and uses seawater to condense the gaseous working medium into a liquid working medium. The liquid working medium is stored in the first liquid storage tank. The liquid working medium in the first liquid storage tank is pressurized by the first solution pump and then sent to the first heat exchanger to complete a cycle.

[0014] Furthermore, when the absorption refrigeration cycle component is working, the rich solution is heated by the heat from the heat storage in the generator, and the heating causes the working fluid to evaporate from the rich solution. The evaporated working fluid gas is cooled by the second condenser and condensed into a liquid state. The condensed working fluid liquid enters the first throttle valve. After passing through the first throttle valve, the pressure of the working fluid liquid decreases, and the temperature also decreases. The low-pressure and low-temperature working fluid liquid absorbs the heat of the environment in the evaporator and evaporates into a gas, thereby achieving a refrigeration effect. The evaporated working fluid gas is sent back to the absorber; and the remaining lean solution in the generator flows to the third heat exchanger for heat exchange, and then flows to the second throttle valve for pressure reduction and temperature reduction, and finally flows into the absorber; in the absorber, the working fluid gas released in the evaporator is mixed and absorbed with the lean solution liquid; this process releases heat, and seawater is used to help dissipate heat; the rich solution formed after absorption is pressurized by the second solution pump and heated by the third heat exchanger, and then flows to the generator again to complete a cycle.

[0015] Furthermore, when the thermal storage energy storage component is working, the engine exhaust gas is diverted through the main three-way valve and then enters the fourth heat exchanger through the second diversion pipe. The engine exhaust gas exchanges heat with the working fluid through the fourth heat exchanger, and the working fluid flows into the heat storage device carrying the heat; when the heat stored in the heat storage device reaches a preset scale, the working fluid enters the second heat exchanger and the generator respectively through the diversion of the first three-way valve, and the flow rate of the working fluid entering the second heat exchanger is controlled by the second switch valve, and the flow rate of the working fluid entering the generator is controlled by the third switch valve.

[0016] Furthermore, the flow sensor and the temperature sensor on the second circulation pipeline are both located between the first throttle valve and the evaporator, and are used to collect the flow rate and temperature of the working medium entering the evaporator.

[0017] Furthermore, the temperature sensor on the first circulation pipeline is located between the second heat exchanger and the expander to collect the temperature of the working fluid that finally enters the expander; the flow sensor on the first circulation pipeline is located between the first liquid storage tank and the first heat exchanger to collect the flow of the working fluid involved in the entire Rankine cycle, and the first condenser uses seawater for condensation.

[0018] Furthermore, the controller includes a storage module, a first model prediction module, a second model prediction module and a third model prediction module, wherein the storage module stores a Rankine cycle model, an absorption refrigeration cycle model and a heat storage energy storage model, wherein the Rankine cycle model is used to calculate the working fluid flow required for the Rankine cycle component to reach the target output power according to the temperature data collected by the temperature sensor on the first circulation pipeline; the absorption refrigeration cycle model is used to calculate the working fluid flow required for the Rankine absorption refrigeration cycle component to produce the target cooling capacity according to the temperature data collected by the temperature sensor on the second circulation pipeline; the heat storage energy storage model is used to calculate the heat storage state of the heat storage according to the temperature sensor on the first pipeline and the flow sensor on the second pipeline; the first model prediction module is used to compare the required working fluid flow calculated according to the Rankine cycle model with the working fluid flow collected by the flow sensor of the first circulation pipeline to determine the heat storage state of the heat storage according to the temperature sensor on the first pipeline and the flow sensor on the second pipeline, so as to determine the heat storage state of the heat storage according to the temperature sensor on the first pipeline and the flow sensor on the second pipeline. whether the working fluid flow of the expander meets the requirement; if not, the opening of the shunt control valve is controlled so that the working fluid flow entering the expander meets the requirement; when the first model prediction module determines that the working fluid flow in the first circulation pipeline still cannot meet the required working fluid flow calculated by the Rankine cycle model when the opening of the shunt control valve is the largest, the second model prediction module can control the opening of the second switch valve according to the difference between the required working fluid flow calculated by the Rankine cycle model and the working fluid flow in the first circulation pipeline, thereby filling the difference in power generation of the Rankine cycle component; the third model prediction module is used to compare the required working fluid flow calculated according to the absorption refrigeration cycle model with the working fluid flow collected by the flow sensor of the second circulation pipeline to determine whether the working fluid flow entering the evaporator meets the requirement; if not, the opening of the third switch valve is controlled so that the working fluid flow entering the evaporator meets the requirement.

[0019] The present invention also provides a method for recovering waste heat from a long-distance ship using the waste heat recovery system for a long-distance ship, comprising the following steps:

[0020] S1, in the initial state, the thermal energy storage component works so that the heat storage device stores heat, and detects whether the heat storage reaches a preset scale. If so, it proceeds to step S2, if not, it continues to store heat in the heat storage device;

[0021] S2, collecting data from various temperature sensors and flow sensors, setting the target output power of the Rankine cycle component and the target cooling capacity of the absorption refrigeration cycle component, and setting safe operating parameters for the Rankine cycle component, the absorption refrigeration cycle component and the thermal energy storage component;

[0022] S3, setting the working state of the system, the working state of the system includes three types: power generation only, cooling only, and power generation and cooling at the same time. If the working state of the system is power generation only, then go to step S4; if the working state of the system is cooling only, then go to step S5; if the working state of the system is power generation and cooling at the same time, then go to step S6;

[0023] S4, according to the temperature data collected by the temperature sensor on the first circulation pipeline, the working fluid flow rate required for the Rankine cycle component to reach the target output power is calculated by the Rankine cycle model, and the first model prediction module compares the required working fluid flow rate calculated by the Rankine cycle model with the working fluid flow rate collected by the flow sensor of the first circulation pipeline to determine whether the working fluid flow rate entering the expander meets the requirement. If not, the opening of the shunt control valve is controlled to make the working fluid flow rate entering the expander meet the requirement;

[0024] When the first model prediction module determines that the working fluid flow in the first circulation pipeline still cannot meet the required working fluid flow calculated by the Rankine cycle model when the opening of the shunt control valve is at its maximum, the second model prediction module controls the opening of the second switch valve according to the difference between the required working fluid flow calculated by the Rankine cycle model and the working fluid flow in the first circulation pipeline, thereby filling the difference in power generation of the Rankine cycle component;

[0025] S5, the third model prediction module compares the required working fluid flow rate calculated according to the absorption refrigeration cycle model with the working fluid flow rate collected by the flow sensor of the second circulation pipeline to determine whether the working fluid flow rate entering the evaporator meets the requirement. If not, the opening of the third switch valve is controlled to make the working fluid flow rate entering the evaporator meet the requirement.

[0026] S6, controlling the power generation of the Rankine cycle component and the cooling capacity of the absorption refrigeration cycle component respectively through step S4 and step S5.

[0027] Furthermore, the first model prediction module, the second model prediction module and the third model prediction module all adopt a model predictive control system.

[0028] Furthermore, in step S1, when the system starts to run, the first switch valve is opened, the diversion control valve, the second switch valve and the third switch valve are closed, and only the heat storage device stores energy.

[0029] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0030] 1. The above-mentioned waste heat recovery system and method for long-distance ships can provide both electrical energy and cold energy, and can better meet user needs; at the same time, through the cooperation of thermal energy storage components, its power generation and cooling capacity can be produced according to user needs, which is different from the traditional waste heat recovery system, making the system energy more efficient, thereby improving energy utilization efficiency.

[0031] 2. The controller of the above-mentioned waste heat recovery system and method for long-distance ships adopts a model prediction algorithm to control the opening of each valve, thereby being able to more intelligently control the output of electrical energy and cold energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a structural diagram of a waste heat recovery system for a long-distance ship according to a preferred embodiment of the present invention;

[0033] Figure 2 This is a module diagram of a controller in a waste heat recovery system for a long-distance ship according to a preferred embodiment of the present invention;

[0034] Main component symbols

[0035] 10. Waste heat transport assembly; 11. Main transport pipe; 12. Main three-way valve; 13. First shunt pipe; 14. Second shunt pipe; 15. Shunt control valve; 20. Rankine cycle assembly; 21. First heat exchanger; 22. Second heat exchanger; 23. Expander; 24. First condenser; 25. First liquid storage tank; 26. First solution pump; 27. First circulation pipeline; 30. Absorption refrigeration cycle assembly; 31. Generator; 32. Second condenser; 33. First throttle valve; 34. Evaporator; 35. Absorber; 36. Second solution pump; 37. Second throttle valve; 38. Third heat exchanger; 391. Second circulation pipe channel; 392, connecting pipeline; 40, thermal storage component; 41, fourth heat exchanger; 42, heat storage; 43, second liquid storage tank; 44, first switch valve; 45, third liquid storage tank; 46, first three-way valve; 47, second switch valve; 48, second three-way valve; 49, third switch valve; 401, first control pipeline; 402, second control pipeline; 50, flow sensor; 60, temperature sensor; 70, controller; 71, storage module; 72, first model prediction module; 73, second model prediction module; 74, third model prediction module; 81, first pipeline; 82, second pipeline; 83, collecting pipeline. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0039] See also Figure 1 A preferred embodiment of the present invention provides a waste heat recovery system for a long-distance ship, comprising a waste heat transport component 10, a Rankine cycle component 20, an absorption refrigeration cycle component 30 and a thermal storage component 40, wherein the input ends of the Rankine cycle component 20 and the thermal storage component 40 are both connected to the waste heat transport component 10, and the output end of the thermal storage component 40 is connected to the Rankine cycle component 20 and the absorption refrigeration cycle component 30.

[0040] The waste heat transport assembly 10 is used to transport the exhaust gas generated by the engine when the long-distance ship is working to the waste heat recovery system of the long-distance ship. The waste heat transport assembly 10 includes a main transport pipe 11, a main three-way valve 12, a first diverter pipe 13 and a second diverter pipe 14. One end of the main transport pipe 11 is connected to the inlet of the main three-way valve 12, one end of the first diverter pipe 13 and one end of the second diverter pipe 14 are respectively connected to the two outlets of the main three-way valve 12, and a diverter control valve 15 is installed on the first diverter pipe 13.

[0041] The Rankine cycle assembly 20 is used to generate electricity using the heat of the exhaust gas generated by the engine, and includes a first heat exchanger 21, a second heat exchanger 22, an expander 23, a first condenser 24, a first liquid storage tank 25, and a first solution pump 26. The first outlet of the first heat exchanger 21 is connected to the first inlet of the first heat exchanger 21 through the first circulation pipeline 27, and the second heat exchanger 22, the expander 23, the first condenser 24, the first liquid storage tank 25, and the first solution pump 26 are sequentially installed on the first circulation pipeline 27 along the transmission direction of the first circulation pipeline 27. The second inlet of the first heat exchanger 21 is connected to the other end of the first diverter pipe 13.

[0042] The absorption refrigeration cycle assembly 30 can utilize heat for cooling, and includes a generator 31, a second condenser 32, a first throttle valve 33, an evaporator 34, an absorber 35, a second solution pump 36, a second throttle valve 37, and a third heat exchanger 38. The first outlet of the generator 31 is connected to the first inlet of the generator 31 through the second circulation pipeline 391, and the second condenser 32, the first throttle valve 33, the evaporator 34, the absorber 35, the second solution pump 36, and the third heat exchanger 38 are sequentially installed on the second circulation pipeline 391 along the transmission direction of the second circulation pipeline 391; the third heat exchanger 38 is also connected to the absorber 35 through the second throttle valve 37; the second outlet of the generator 31 is also connected to the third heat exchanger 38 through the connecting pipeline 392.

[0043] The thermal storage component 40 can store the heat of the exhaust gas generated by the engine, and includes a fourth heat exchanger 41, a heat storage tank 42, a second liquid storage tank 43, a first switch valve 44, a third liquid storage tank 45, a first three-way valve 46, a second switch valve 47, a second three-way valve 48 and a third switch valve 49. The first inlet of the fourth heat exchanger 41 is connected to the other end of the second shunt pipe 14, the first outlet of the fourth heat exchanger 41 is connected to the first inlet of the heat storage tank 42 through the first pipe 81, the first outlet of the heat storage tank 42 is connected to the second inlet of the fourth heat exchanger 41 through the second pipe 82, the second liquid storage tank 43 and the first switch valve 44 are both installed on the second pipe 82, and in this embodiment, the first switch valve 44 is arranged between the second liquid storage tank 43 and the fourth heat exchanger 41. The second outlet of the heat storage 42 is connected to the inlet of the third liquid storage tank 45, the outlet of the third liquid storage tank 45 is connected to the inlet of the first three-way valve 46, the two outlets of the first three-way valve 46 are respectively connected to one end of the first control pipeline 401 and one end of the second control pipeline 402, the other end of the first control pipeline 401 is connected to the second heat exchanger 22, and the second switch valve 47 is installed on the first control pipeline 401. The other end of the second control pipeline 402 is connected to the second inlet of the generator 31, and the third switch valve 49 is installed on the second control pipeline 402. The two inlets of the second three-way valve 48 are respectively connected to the second heat exchanger 22 and the third outlet of the generator 31, and the outlet of the second three-way valve 48 is connected to the second inlet of the heat storage 42 through the collecting pipeline 83.

[0044] When the Rankine cycle component 20 is working, the heat energy of the exhaust gas discharged by the engine enters the first heat exchanger 21 through the main delivery pipe 11 and the first branch pipe 13. The working medium absorbs the heat from the exhaust gas discharged by the engine in the first heat exchanger 21, and then the working medium comes to the second heat exchanger 22 to absorb the heat transferred from the heat storage tank 42, thereby being heated to a high-temperature gas state. The gaseous working medium runs to the expander 23, and the expander 23 is connected to a steam turbine (not shown in the figure). The working medium after passing through the expander 23 is used to drive the steam turbine to rotate. The rotor of the steam turbine is connected to the generator, so that the generator also rotates together, thereby generating electrical energy. The working medium that loses energy passes through the first condenser 24 and uses seawater to condense the gaseous working medium into a liquid working medium. The liquid working medium is stored in the first liquid storage tank 25. The liquid working medium in the first liquid storage tank 25 is pressurized by a solution pump and then sent to the first heat exchanger 21 to complete a cycle.

[0045] When the absorption refrigeration cycle component 30 is working, the rich solution (high-concentration working fluid) is heated by the heat from the heat storage device 42 in the generator 31, and the heating causes the working fluid to evaporate from the rich solution. The evaporated working fluid gas is cooled by the second condenser 32 and condensed into a liquid state. The condensed working fluid liquid enters the first throttle valve 33. After the working fluid liquid passes through the first throttle valve 33, the pressure is reduced and the temperature is also reduced. The low-pressure and low-temperature working fluid liquid absorbs the heat of the environment in the evaporator 34 and evaporates into gas, thereby achieving a refrigeration effect. The evaporated working fluid gas The liquid is sent back to the absorber 35; the remaining lean solution (low-concentration working fluid) in the generator 31 flows to the third heat exchanger 38 for heat exchange, and then flows to the second throttle valve 37 for pressure reduction and temperature reduction, and finally flows into the absorber 35; in the absorber 35, the working fluid gas released from the evaporator 34 is mixed and absorbed with the lean solution liquid; this process releases heat, and seawater is used to help dissipate heat; the rich solution formed after absorption is pressurized by the second solution pump 36 and heated by the third heat exchanger 38, and then flows to the generator 31 again, completing a cycle.

[0046] When the thermal storage component 40 is working, the waste heat of the engine enters the fourth heat exchanger 41 through the second shunt pipe 14 after the shunt of the main three-way valve 12. The waste heat of the engine exchanges heat with the working medium through the fourth heat exchanger 41, and the working medium carries the heat and flows into the heat storage 42, wherein the flow rate of the working medium entering the heat storage 42 is controlled by the first switch valve 44. When the heat stored in the heat storage 42 reaches a preset scale (in this embodiment, the energy storage in the heat storage 42 is set to reach more than half), the working medium enters the second heat exchanger 22 and the generator 31 respectively through the shunt of the first three-way valve 46, and the flow rate of the working medium entering the second heat exchanger 22 is controlled by the second switch valve 47, and the flow rate of the working medium entering the generator 31 is controlled by the third switch valve 49.

[0047] The main delivery pipe 11, the first circulation pipe 27, the second circulation pipe 391 and the second control pipe 402 are all equipped with flow sensors 50 and temperature sensors 60, the first pipe 81 is equipped with a temperature sensor 60, the second pipe 82 is equipped with a flow sensor 50 and a temperature sensor 60, the collecting pipe 83 is equipped with a temperature sensor 60, and the first control pipe 401 is equipped with a flow sensor 50. In this embodiment, the flow sensor 50 and the temperature sensor 60 on the second circulation pipe 391 are both located between the first throttle valve 33 and the evaporator 34, and are used to collect the flow and temperature of the working medium entering the evaporator 34. The temperature sensor 60 on the first circulation pipe 27 is located between the second heat exchanger 22 and the expander 23, and collects the temperature of the working medium that finally enters the expander 23; the flow sensor 50 on the first circulation pipe 27 is located between the first liquid storage tank 25 and the first heat exchanger 21, and collects the flow of the working medium involved in the entire Rankine cycle. The first condenser 24 and the second condenser 32 both use seawater for condensation.

[0048] The waste heat recovery system for long-distance ships also includes a controller 70, which is connected to a plurality of flow sensors 50, a plurality of temperature sensors 60, a diversion control valve 15, a first switch valve 44, a second switch valve 47 and a third switch valve 49 to distribute the working fluid flow for power generation, power generation supplementary heat and refrigeration cycle.

[0049] In this embodiment, the controller 70 includes a storage module 71, a first model prediction module 72, a second model prediction module 73 and a third model prediction module 74. The storage module 71 stores a Rankine cycle model, an absorption refrigeration cycle model and a heat storage energy storage model. The Rankine cycle model is used to calculate the working fluid flow required for the Rankine cycle component 20 to reach the target output power according to the temperature data collected by the temperature sensor 60 on the first circulation pipeline 27; the absorption refrigeration cycle model is used to calculate the working fluid flow required for the Rankine absorption refrigeration cycle component to produce the target cooling capacity according to the temperature data collected by the temperature sensor 60 on the second circulation pipeline 391; the heat storage energy storage model is used to calculate the heat storage state of the heat storage device 41 according to the temperature sensor 60 on the first pipeline 81 and the flow sensor 50 on the second pipeline 82; the first model prediction module 72 is used to compare the required working fluid flow calculated according to the Rankine cycle model with the working fluid flow collected by the flow sensor 50 of the first circulation pipeline 27 , to determine whether the working fluid flow entering the expander 23 meets the requirement. If not, the opening of the bypass control valve 15 is controlled so that the working fluid flow entering the expander 23 meets the requirement. When the first model prediction module 72 determines that the working fluid flow in the first circulation pipeline 27 still cannot meet the required working fluid flow calculated by the Rankine cycle model when the opening of the bypass control valve 15 is maximum, the second model prediction module 73 can control the opening of the second switch valve 47 according to the difference between the required working fluid flow calculated by the Rankine cycle model and the working fluid flow in the first circulation pipeline 27, thereby filling the difference in the power generation of the Rankine cycle component 20. The third model prediction module 74 is used to compare the required working fluid flow calculated according to the absorption refrigeration cycle model with the working fluid flow collected by the flow sensor 50 of the second circulation pipeline 391, to determine whether the working fluid flow entering the evaporator 34 meets the requirement. If not, the opening of the third switch valve 49 is controlled so that the working fluid flow entering the evaporator 34 meets the requirement.

[0050] Among them, the establishment of the heat storage model of the heat storage device: in the early stage of model establishment, the heat exchange between the heat storage device and the external environment is ignored, the heat storage device is assumed to be adiabatic, the assumption that pressure changes have little effect on system performance is ignored, the temperature of the heat storage medium is assumed to be uniform in the horizontal container, and the changes in the physical and chemical properties of the heat storage medium are ignored. Specifically,

[0051] The heat storage medium of the heat storage device is discretized using the finite difference method. The equation after fluid discretization is as follows:

[0052]

[0053] The equation of the heat storage medium after discretization is as follows:

[0054]

[0055] In the above equation, the subscripts f, r and w represent the fluid, the heat storage medium and the wall respectively; the bed porosity is represented by ε, the time is represented by t, and the specific heat is represented by c p The velocity is represented by u, the height is represented by x, the thermal conductivity is represented by λ, the temperature is represented by T, and the medium diameter is represented by d r The heat transfer coefficient between the fluid and the rock particles is represented by h, the inner diameter of the packed bed is represented by D, and the area of ​​the packed bed is represented by A. bed , density is denoted by ρ, and solid particles are denoted by p.

[0056] Establishment of Rankine cycle model: In the process of modeling Rankine cycle, critical superheat cycle is selected, so that the cycle efficiency is higher. At the beginning of the prediction model establishment, the pressure loss in the pipeline, pipeline friction and equipment energy consumption are ignored, and it is assumed that the cycle process is constant and uniform, and the cycle is in a stable operation state. The operation process of Rankine cycle has inertia and response delay, that is, the system cannot respond to the input changes immediately and needs time to adjust. After multiple model runs, some corrections should be made to the ignored details.

[0057] Establishment of Rankine cycle model:

[0058] The work done by the model in the expander 23 after the cycle is as follows:

[0059] W T =m ORC *η T *(h1-h2)

[0060] The work consumed by the model in the first solution pump 26 is as follows:

[0061] W p =m ORC *(h2-h1) / η p

[0062] The net work produced by the model is as follows:

[0063] W=W T +W p

[0064] In the above equation, m ORC is the flow rate of the working fluid in the Rankine cycle, ηT is the thermal efficiency of the expander, η p is the thermal efficiency of the pump, subscript 1 is the state before the working fluid enters the device, and subscript 2 is the state after the working fluid leaves the device.

[0065] Establishment of absorption refrigeration model: At the beginning of the prediction model establishment, it is assumed that the chemical reaction is fast and ideal, the specific reaction kinetics process is ignored, and the energy consumption of each component in the refrigeration cycle is ignored. After the model is run multiple times, these ignored factors need to be considered and corrected.

[0066] Establishment of absorption refrigeration model:

[0067] The model absorbs heat from the outside in the evaporator 34, and the cooling capacity is as follows:

[0068] Q e =m r *(h1-h2)

[0069] The input heat flow provided by the model system in generator 28 is as follows:

[0070] Q g =m s *(h2-h1)

[0071] The heat released by the model to the outside in the second condenser 32 is as follows:

[0072] Q c =m r *(h1-h2)

[0073] Among them, m r is the mass flow rate of refrigerant, m s is the mass flow rate of the solute, subscript 1 is the state before the refrigerant enters the device, and subscript 2 is the state after the refrigerant leaves the device; the refrigeration efficiency should also be considered during actual operation to correct the theoretical value and the performance loss under actual operation.

[0074] The heat storage model, Rankine cycle model and absorption refrigeration model all belong to the prior art and will not be described here in detail to save space.

[0075] In this embodiment, the controller 70 can also correct the flow distribution result according to the data sent back by the flow sensor 50 and the temperature sensor 60. Specifically, in this embodiment, the first model prediction module 72, the second model prediction module 73 and the third model prediction module 74 all adopt the model predictive control system (MPC). The model predictive control system is a system that predicts the future output of the system based on the existing model, the current measurement state of the system and the future predicted control quantity, and then compares it with the expected system output to obtain the cost function. Through the optimization method, the future control quantity is optimized to minimize the cost function. The optimized control quantity is the output of the algorithm. The model predictive control system MPC also adopts a rolling time domain strategy to optimize the control input (the valve opening in this embodiment). At the same time, the model predictive control system MPC establishes an effective cost function, which can reflect the overall performance objectives of the system, the equipment operating costs and the necessary penalty items to ensure the safety and reliability of the system:

[0076] The cost function is:

[0077]

[0078] Where U is the control input sequence, which is the valve opening, X is the system state sequence, which is the temperature and pressure measured during the operation of the system, e(k) is the error between the desired state and the actual state, u(k) is the intensity or size of the control action (i.e., the valve opening size), p(k) is a possible penalty term (penalty for exceeding the safety threshold), and Q and S are weight parameters used to adjust the relative importance of each term in the cost function.

[0079] Among the various weight parameters, Weight Q: Increasing this weight can make the system pay more attention to accurately reaching the target state. Weight S: Used to increase the penalty for violating the operating constraints, such as exceeding the maximum allowable pressure or temperature.

[0080] Solve the cost function and obtain the control quantity that minimizes the cost function, that is, complete the optimization of the control quantity (valve opening), and the optimized control quantity is the output of the algorithm.

[0081] The embodiment of the present invention further provides a method for recovering waste heat from a long-distance ship using the waste heat recovery system for a long-distance ship, comprising the following steps:

[0082] S1, in the initial state, the thermal energy storage component 40 works so that the heat storage device 42 stores heat, and detects whether the heat storage reaches a preset scale. If so, it proceeds to step S2, and if not, it continues to store heat in the heat storage device 42;

[0083] S2, collecting data from each temperature sensor 60 and flow sensor 50, setting the target output power of the Rankine cycle component 20 and the target cooling capacity of the absorption refrigeration cycle component 30, and setting the safe operation parameters of the Rankine cycle component 20, the absorption refrigeration cycle component 30 and the thermal energy storage component 40;

[0084] S3, setting the working state of the system, the working state of the system includes three types: power generation only, cooling only, and power generation and cooling at the same time. If the working state of the system is power generation only, then go to step S4; if the working state of the system is cooling only, then go to step S5; if the working state of the system is power generation and cooling at the same time, then go to step S6;

[0085] S4, according to the temperature data collected by the temperature sensor 60 on the first circulation pipeline 27, the working fluid flow required for the Rankine cycle component 20 to reach the target output power is calculated by the Rankine cycle model, and the first model prediction module 72 compares the required working fluid flow calculated by the Rankine cycle model with the working fluid flow collected by the flow sensor 50 of the first circulation pipeline 27 to determine whether the working fluid flow entering the expander 23 meets the requirement. If not, the opening of the diverter control valve 15 is controlled to make the working fluid flow entering the expander 23 meet the requirement;

[0086] When the first model prediction module 72 determines that the working fluid flow in the first circulation pipeline 27 still cannot meet the required working fluid flow calculated by the Rankine cycle model when the opening of the diverter control valve 15 is at its maximum, the second model prediction module 73 controls the opening of the second switch valve 47 according to the difference between the required working fluid flow calculated by the Rankine cycle model and the working fluid flow in the first circulation pipeline 27, thereby filling the difference in the power generation of the Rankine cycle component 20;

[0087] S5, the third model prediction module 74 compares the required working fluid flow rate calculated according to the absorption refrigeration cycle model with the working fluid flow rate collected by the flow sensor 50 of the second circulation pipeline 391 to determine whether the working fluid flow rate entering the evaporator 34 meets the requirement. If not, the opening of the third switch valve 49 is controlled to make the working fluid flow rate entering the evaporator 34 meet the requirement;

[0088] S6, controlling the power generation of the Rankine cycle component 20 and the cooling capacity of the absorption refrigeration cycle component 30 through step S4 and step S5 respectively.

[0089] Specifically, in step S1, when the system starts running, the operation is as follows:

[0090] The first switch valve 44 is opened, and the flow diversion control valve 15, the second switch valve 47 and the third switch valve 49 are closed. Only the heat storage device is used to store energy. The heat of the exhaust gas discharged by the engine is exchanged with the working medium in the fourth heat exchanger 41. The heat storage device energy storage model calculates the heat storage amount of the heat storage device 42 according to the data collected by the temperature sensor 60 of the first pipeline 81 and the flow sensor 50 of the second pipeline 82, until the heat storage amount of the heat storage device 42 reaches the set scale, for example, 1 / 2;

[0091] When the heat storage reaches the set scale, if only power generation is performed, the shunt control valve 15 and the first switch valve 44 remain in the open state. If the first model prediction module 72 determines that the working fluid flow in the current first circulation pipeline 27 can meet the working fluid flow required for power generation calculated by the Rankine cycle model, the shunt control valve 15 and the first switch valve 44 are controlled to remain in the open state, and the third switch valve 49 and the second switch valve 47 are closed to perform heat storage and thermal energy generation. The working fluid exchanges heat with the engine exhaust heat in the first heat exchanger 21 and the fourth heat exchanger 41, respectively, to perform power generation and heat storage.

[0092] If the first model prediction module 72 determines that the working fluid flow in the first circulation pipeline 27 still cannot meet the working fluid flow required for power generation calculated by the Rankine cycle model under the premise that the opening of the diverter control valve 15 is the largest, the first switch valve 44 and the second switch valve 47 are opened, and the third switch valve 49 is closed. The first model prediction module 71 controls the opening of the second switch valve 47 to fill the difference in the power generation of the Rankine cycle component 20 to meet the user's power demand;

[0093] (5) When the heat storage reaches 1 / 2, only cooling is performed:

[0094] The flow diversion control valve 15 and the second switch valve 47 are closed, the third switch valve 49 and the first switch valve 44 are opened, and the opening of the third switch valve 49 is controlled by the controller 70 to store heat and energy as well as refrigerate; if the third switch valve 49 is closed, all the heat discharged by the engine is used for energy and heat storage; the third model prediction module 74 compares the required working fluid flow calculated according to the absorption refrigeration cycle model with the working fluid flow collected by the flow sensor 50 of the second circulation pipeline 391 to determine whether the working fluid flow entering the evaporator 34 meets the requirements. If not, the opening of the third switch valve 49 is controlled so that the working fluid flow entering the evaporator 34 meets the requirements, thereby meeting the user's cooling demand;

[0095] (6) When the heat storage reaches 1 / 2, it is used for both power generation and cooling:

[0096] First, the first model prediction module 72 is used to control the opening of the diverter control valve 15 to control the power generation of the Rankine cycle:

[0097] When the first model prediction module 72 determines that the working fluid flow in the first circulation pipeline 27 still cannot meet the required working fluid flow calculated by the Rankine cycle model when the opening of the diverter control valve 15 is at its maximum, the second model prediction module 73 can control the opening of the second switch valve 47 according to the difference between the required working fluid flow calculated by the Rankine cycle model and the working fluid flow in the first circulation pipeline 27, thereby filling the difference in the power generation of the Rankine cycle component 20; for refrigeration, the third model prediction module 74 is used to control the opening of the third switch valve 49 for refrigeration.

[0098] The above-mentioned waste heat recovery system and method for long-distance ships can provide both electrical energy and cold energy, and can better meet user needs; at the same time, through the cooperation of the heat storage device, its power generation and cooling capacity can be produced according to user needs, which is different from the traditional waste heat recovery system, making the system energy more efficient, thereby improving energy utilization efficiency.

[0099] The above-mentioned waste heat recovery system and method for long-distance ships, the controller 70 uses a model prediction algorithm (MPC) to predict the future output of the system according to the current measurement state of the system and the future predicted control quantity, and then compares it with the expected system output to obtain a cost function, and optimizes the future control quantity through an optimization method to minimize the cost function. The optimized control quantity is the output of the algorithm, which is used to control the opening of each valve, thereby being able to more intelligently control the output of electrical energy and cold energy.

[0100] The above description is a detailed description of the preferred feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A waste heat recovery system for a long-distance ship, characterized in that: It includes a waste heat transport component, a Rankine cycle component, an absorption refrigeration cycle component and a thermal storage component; the input ends of the Rankine cycle component and the thermal storage component are both connected to the waste heat transport component, and the output end of the thermal storage component is connected to the Rankine cycle component and the absorption refrigeration cycle component.

2. A waste heat recovery system for a long-distance ship according to claim 1, characterized in that: The waste heat transport assembly includes a main transport pipe, a main three-way valve, a first diverter pipe and a second diverter pipe. One end of the main transport pipe is connected to the inlet of the main three-way valve. One end of the first diverter pipe and one end of the second diverter pipe are respectively connected to the two outlets of the main three-way valve. The first diverter pipe is equipped with a diverter control valve. The Rankine cycle assembly includes a first heat exchanger, a second heat exchanger, an expander, a first condenser, a first liquid storage tank and a first solution pump; the first outlet of the first heat exchanger is connected to the first inlet of the first heat exchanger through a first circulation pipeline, and the second heat exchanger, the expander, the first condenser, the first liquid storage tank and the first solution pump are sequentially installed on the first circulation pipeline along the transmission direction of the first circulation pipeline; the second inlet of the first heat exchanger is connected to the other end of the first shunt pipe; The absorption refrigeration cycle assembly includes a generator, a second condenser, a first throttle valve, an evaporator, an absorber, a second solution pump, a second throttle valve and a third heat exchanger, wherein the first outlet of the generator is connected to the first inlet of the generator through a second circulation pipeline, and the second condenser, the first throttle valve, the evaporator, the absorber, the second solution pump and the third heat exchanger are sequentially installed on the second circulation pipeline along the transmission direction of the second circulation pipeline; the third heat exchanger is also connected to the absorber through the second throttle valve; the second outlet of the generator is also connected to the third heat exchanger through a connecting pipeline; The thermal storage energy storage component includes a fourth heat exchanger, a heat storage tank, a second liquid storage tank, a first switch valve, a third liquid storage tank, a first three-way valve, a second switch valve, a second three-way valve and a third switch valve. The first inlet of the fourth heat exchanger is connected to the other end of the second shunt pipe, the first outlet of the fourth heat exchanger is connected to the first inlet of the heat storage tank through the first pipeline, the first outlet of the heat storage tank is connected to the second inlet of the fourth heat exchanger through the second pipeline, and the second liquid storage tank and the first switch valve are both installed on the first pipeline; the second outlet of the heat storage tank is connected to the inlet of the third liquid storage tank, the outlet of the third liquid storage tank is connected to the inlet of the first three-way valve, the two outlets of the first three-way valve are respectively connected to one end of the first regulating pipeline and one end of the second regulating pipeline, the other end of the first regulating pipeline is connected to the second heat exchanger, and the second switch valve is installed on the first regulating pipeline; the other end of the second regulating pipeline is connected to the second inlet of the generator, and the third switch valve is installed on the second regulating pipeline; the two inlets of the second three-way valve are respectively connected to the third outlet of the second heat exchanger and the generator, and the outlet of the second three-way valve is connected to the second inlet of the heat storage tank through a collecting pipeline; The main delivery pipe, the first circulation pipe, the second circulation pipe and the second regulating pipe are all equipped with flow sensors and temperature sensors. The first pipe is equipped with a temperature sensor, the second pipe is equipped with a flow sensor, the first regulating pipe is equipped with a flow sensor, and the collecting pipe is equipped with a temperature sensor. The waste heat recovery system for long-distance ships includes a controller, which is connected to a plurality of flow sensors, a plurality of temperature sensors, a diversion control valve, a first switch valve, a second switch valve and a third switch valve to distribute the working fluid flow for power generation, power generation supplementary heat and refrigeration cycle.

3. A waste heat recovery system for a long-distance ship as claimed in claim 2, characterized in that: When the Rankine cycle component is working, the exhaust gas discharged by the engine enters the first heat exchanger after passing through the main delivery pipe and the first branch pipe. The working medium absorbs the heat from the exhaust gas discharged by the engine in the first heat exchanger. Then the working medium comes to the second heat exchanger to absorb the heat transferred from the heat storage device and is heated to a high-temperature gas state. The gaseous working medium runs to the expander, and the expander is connected to a steam turbine. The working medium after passing through the expander is used to drive the steam turbine to rotate. The rotor of the steam turbine is connected to the generator, so that the generator also rotates together, thereby generating electrical energy. The working medium that loses energy passes through the first condenser and uses seawater to condense the gaseous working medium into a liquid working medium. The liquid working medium is stored in the first liquid storage tank. The liquid working medium in the first liquid storage tank is pressurized by the first solution pump and then sent to the first heat exchanger to complete a cycle.

4. A waste heat recovery system for a long-distance ship as claimed in claim 2, characterized in that: When the absorption refrigeration cycle component is working, the rich solution is heated by the heat from the heat storage in the generator, and the heating causes the working fluid to evaporate from the rich solution. The evaporated working fluid gas is cooled by the second condenser and condensed into a liquid state. The condensed working fluid liquid enters the first throttle valve. After passing through the first throttle valve, the pressure of the working fluid liquid decreases, and the temperature also decreases. The low-pressure and low-temperature working fluid liquid absorbs the heat of the environment in the evaporator and evaporates into gas, thereby achieving a refrigeration effect. The evaporated working fluid gas is sent back to the absorber; the remaining lean solution in the generator flows to the third heat exchanger for heat exchange, and then flows to the second throttle valve for pressure reduction and temperature reduction, and finally flows into the absorber; in the absorber, the working fluid gas released in the evaporator is mixed and absorbed with the lean solution liquid; this process releases heat, and seawater is used to help dissipate heat; the rich solution formed after absorption is pressurized by the second solution pump and heated by the third heat exchanger, and then flows to the generator again to complete a cycle.

5. The waste heat recovery system for a long-distance ship according to claim 2, characterized in that: When the thermal storage energy storage component is working, the engine exhaust gas is diverted by the main three-way valve and then enters the fourth heat exchanger through the second diversion pipe. The engine exhaust gas exchanges heat with the working medium through the fourth heat exchanger, and the working medium flows into the heat storage device carrying the heat. When the heat stored in the heat storage device reaches a preset scale, the working medium enters the second heat exchanger and the generator respectively through the diversion of the first three-way valve, and the flow rate of the working medium entering the second heat exchanger is controlled by the second switch valve, and the flow rate of the working medium entering the generator is controlled by the third switch valve.

6. The waste heat recovery system for a long-distance ship according to claim 1, characterized in that: The temperature sensor on the first circulation pipeline is located between the second heat exchanger and the expander, and collects the temperature of the working fluid that finally enters the expander; the flow sensor on the first circulation pipeline is located between the first liquid storage tank and the first heat exchanger, and collects the flow of the working fluid involved in the entire Rankine cycle. The first condenser uses seawater for condensation.

7. The waste heat recovery system for a long-distance ship according to claim 1, characterized in that: The controller includes a storage module, a first model prediction module, a second model prediction module and a third model prediction module. The storage module stores a Rankine cycle model, an absorption refrigeration cycle model and a heat storage energy storage model. The Rankine cycle model is used to calculate the working fluid flow required for the Rankine cycle component to reach the target output power according to the temperature data collected by the temperature sensor on the first circulation pipeline; the absorption refrigeration cycle model is used to calculate the working fluid flow required for the Rankine absorption refrigeration cycle component to produce the target cooling capacity according to the temperature data collected by the temperature sensor on the second circulation pipeline; the heat storage energy storage model is used to calculate the heat storage state of the heat storage according to the temperature sensor on the first pipeline and the flow sensor on the second pipeline; the first model prediction module The block is used to compare the required working fluid flow calculated according to the Rankine cycle model with the working fluid flow collected by the flow sensor of the first circulation pipeline to determine whether the working fluid flow entering the expander meets the requirement. If not, the opening of the shunt control valve is controlled to make the working fluid flow entering the expander meet the requirement; when the first model prediction module determines that the working fluid flow in the first circulation pipeline still cannot meet the required working fluid flow calculated by the Rankine cycle model when the opening of the shunt control valve is the largest, the second model prediction module can control the opening of the second switch valve according to the difference between the required working fluid flow calculated by the Rankine cycle model and the working fluid flow in the first circulation pipeline, thereby filling the difference in power generation of the Rankine cycle component; The third model prediction module is used to compare the required working fluid flow calculated according to the absorption refrigeration cycle model with the working fluid flow collected by the flow sensor of the second circulation pipeline to determine whether the working fluid flow entering the evaporator meets the requirement. If not, the opening of the third switch valve is controlled to make the working fluid flow entering the evaporator meet the requirement.

8. A method for recovering waste heat from a long-distance ship using the waste heat recovery system for a long-distance ship according to claim 7, characterized in that: The following steps are involved: S1, in the initial state, the thermal energy storage component works so that the heat storage device stores heat, and detects whether the heat storage reaches a preset scale. If so, it proceeds to step S2, if not, it continues to store heat in the heat storage device; S2, collecting data from various temperature sensors and flow sensors, setting the target output power of the Rankine cycle component and the target cooling capacity of the absorption refrigeration cycle component, and setting safe operating parameters for the Rankine cycle component, the absorption refrigeration cycle component and the thermal energy storage component; S3, setting the working state of the system, the working state of the system includes three types: power generation only, cooling only, and power generation and cooling at the same time. If the working state of the system is power generation only, then go to step S4; if the working state of the system is cooling only, then go to step S5; if the working state of the system is power generation and cooling at the same time, then go to step S6; S4, according to the temperature data collected by the temperature sensor on the first circulation pipeline, the working fluid flow rate required for the Rankine cycle component to reach the target output power is calculated by the Rankine cycle model, and the first model prediction module compares the required working fluid flow rate calculated by the Rankine cycle model with the working fluid flow rate collected by the flow sensor of the first circulation pipeline to determine whether the working fluid flow rate entering the expander meets the requirement. If not, the opening of the shunt control valve is controlled to make the working fluid flow rate entering the expander meet the requirement; When the first model prediction module determines that the working fluid flow in the first circulation pipeline still cannot meet the required working fluid flow calculated by the Rankine cycle model when the opening of the shunt control valve is at its maximum, the second model prediction module controls the opening of the second switch valve according to the difference between the required working fluid flow calculated by the Rankine cycle model and the working fluid flow in the first circulation pipeline, thereby filling the difference in power generation of the Rankine cycle component; S5, the third model prediction module compares the required working fluid flow rate calculated according to the absorption refrigeration cycle model with the working fluid flow rate collected by the flow sensor of the second circulation pipeline to determine whether the working fluid flow rate entering the evaporator meets the requirement. If not, the opening of the third switch valve is controlled to make the working fluid flow rate entering the evaporator meet the requirement. S6, controlling the power generation of the Rankine cycle component and the cooling capacity of the absorption refrigeration cycle component respectively through step S4 and step S5.

9. The method for recovering waste heat from a long-distance ship according to claim 8, characterized in that: The first model prediction module, the second model prediction module and the third model prediction module all adopt a model prediction control system.

10. The method for recovering waste heat from a long-distance ship according to claim 8, characterized in that: In step S, when the system starts to run, the first switch valve is opened, the diversion control valve, the second switch valve and the third switch valve are closed, and only the heat storage device stores energy.

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