Ship low-temperature flue gas waste heat power generation and seawater desalination system and working method thereof

Abstract

The invention relates to the technical field of ship waste heat utilization, and discloses a ship low-temperature flue gas waste heat power generation and seawater desalination system and a working method thereof.The system comprises a waste heat seawater desalination device, an organic Rankine cycle and a heat-carrying water cycle; the waste heat seawater desalination device is divided into an upper part and a lower part by a sealing plate, the upper part is a flash chamber, and the lower part is a flue gas heat recovery heat exchange chamber; a high-temperature seawater outlet of the flue gas heat recovery heat exchange chamber is connected with an inlet of the flash chamber through a pressure reducing valve; one path of low-temperature seawater passes through a condenser pipe, the other path of low-temperature seawater passes through a condenser to recover steam condensation latent heat and working medium condensation latent heat, the low-temperature seawater is communicated with an inlet of a second heat recovery heat exchange pipe after converging, and an outlet of a first heat recovery heat exchange pipe is communicated with a heat-carrying water inlet of an evaporator and is coupled with an organic Rankine cycle. Fresh water and seawater are heated step by step through flue gas, seawater desalination and waste heat power generation are achieved at the same time, energy consumption is low, the waste heat utilization rate is high, the flue gas and water flow can be automatically adjusted, and the stability of the system is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of ship waste heat utilization, and in particular to a ship low-temperature flue gas waste heat power generation and seawater desalination system and a working method thereof. Background Art

[0002] As human society continues to develop, many regions are facing serious water shortages. The continued development of seawater desalination technology will provide important support for solving the global water shortage problem. Currently, ocean-going ships consume a lot of water, so most of them need to be equipped with seawater desalination equipment. Existing seawater desalination methods are mainly divided into thermal and membrane methods. Membrane-based ship seawater desalination has problems such as high cost and high energy consumption of pumps. In addition, most existing seawater desalination methods require electricity, and the cost of ship electricity resources is high. Therefore, it is particularly important to improve the economy and sustainability of seawater desalination.

[0003] Ships usually use internal combustion engines as prime movers for main engines and marine generators. Although existing combustion and post-processing technologies have become increasingly mature, the energy utilization rate of ships is still low. Of all the heat released by the combustion of fuel in ship diesel engines, only 30% is converted into mechanical work, and the rest is lost as waste heat. The high-temperature flue gas discharged by the diesel engine is first recovered by the waste heat boiler and steam is generated to supply various needs of the ship, such as driving the steam turbine to generate electricity and supply the heating system, but the exhaust temperature of the waste heat boiler is still as high as about 110-150°C, resulting in waste of heat from the low-temperature flue gas. Summary of the invention

[0004] In order to solve the problem that the exhaust temperature of the high-temperature flue gas discharged by the diesel engine in the above-mentioned prior art is still about 110-150°C after heat recovery by the waste heat boiler, resulting in waste heat of the low-temperature flue gas. The present invention proposes a ship low-temperature flue gas waste heat power generation and seawater desalination system and a working method thereof, aiming to provide a low-energy consumption, low-cost integrated system, deeply recover the waste heat of low-temperature flue gas, and realize seawater desalination and waste heat power generation at the same time.

[0005] The present invention is realized by the following technical scheme: comprising a waste heat seawater desalination device, an organic Rankine cycle and a hot water cycle, wherein a sealing plate is horizontally arranged in the middle of the waste heat seawater desalination device, and the sealing plate divides the waste heat seawater desalination device into an upper flash chamber and a lower flue gas heat recovery heat exchange chamber;

[0006] The flash chamber comprises a horizontally arranged water collecting plate and a condenser pipe, and the water collecting plate is arranged below the condenser pipe, and the lower part of the water collecting plate is connected to the second outlet and the first drainage pump in sequence through a pipeline; one end of the condenser pipe is connected to the first inlet, and the other end is connected to the second inlet through a pipeline;

[0007] The flue gas heat recovery heat exchange chamber includes a flue gas inlet arranged at the bottom, a flue gas outlet arranged below the sealing plate, a first heat recovery heat exchange pipe arranged near the flue gas inlet, and a second heat recovery heat exchange pipe arranged near the flue gas outlet, one end of the first heat recovery heat exchange pipe is connected to the fourth inlet, and the other end is connected to the fourth outlet, one end of the second heat recovery heat exchange pipe is connected to the second inlet, and the other end is connected to the first outlet; the first inlet is connected to the outlet of the water supply pump, and the outlet of the water supply pump is also connected to the organic Rankine cycle, the first outlet is connected to the third inlet through a pipeline and a pressure reducing valve, the third inlet is arranged below the water collecting plate, and a third outlet is arranged above the sealing plate, the third outlet is connected to the second drainage pump through a pipeline, and the other end of the second drainage pump is connected to the organic Rankine cycle;

[0008] The hot water circulation is respectively connected to the fourth inlet, the fourth outlet and the organic Rankine cycle;

[0009] The organic Rankine cycle is also connected to a generator for generating electricity.

[0010] As a further preference, the organic Rankine cycle includes a condenser, a working fluid pump, a drainage heat recovery heat exchanger, an evaporator and an expander connected in sequence; the condenser includes a fifth inlet, a fifth outlet, a sixth inlet and a sixth outlet, the drainage heat recovery heat exchanger includes a ninth inlet, a ninth outlet, a tenth inlet and a tenth outlet, and the evaporator includes a seventh inlet, a seventh outlet, an eighth inlet and an eighth outlet; the fifth inlet is connected to the outlet of the expander, the fifth outlet is connected to the working fluid pump, the sixth inlet is connected to the water supply pump, and the sixth outlet is connected to the second inlet; the ninth inlet is connected to the working fluid pump, the ninth outlet is connected to the eighth inlet, and the tenth inlet is connected to the second drainage pump; the seventh inlet is connected to the fourth outlet, the seventh outlet is connected to the hot water circulation, and the eighth outlet is connected to the inlet of the expander; the expander is also connected to a generator.

[0011] As a further preference, the hot water circulation includes a hot water tank and a circulation pump, one end of the hot water tank is connected to the seventh outlet and the other end is connected to the circulation pump, and the circulation pump is also connected to the fourth inlet.

[0012] As a further preferred embodiment, a first regulating valve is arranged between the first inlet and the water supply pump, a pressure controller is arranged on the top of the flash chamber, a control signal of the pressure controller is connected to the first regulating valve through a wire, and the opening of the first regulating valve is positively correlated with the pressure in the flash chamber; a third regulating valve is arranged between the second drainage pump and the third outlet, a liquid level controller is arranged below the water collecting plate, and a control signal of the liquid level controller is connected to the third regulating valve through a wire; a second regulating valve is arranged between the sixth inlet and the water supply pump, a first temperature controller is arranged at the fifth outlet, and a control signal of the first temperature controller is connected to the second regulating valve through a wire; a fourth regulating valve is arranged at the flue gas inlet, a second temperature controller is arranged on the pipeline between the first outlet and the pressure reducing valve, a control signal of the second temperature controller is connected to the fourth regulating valve through a wire, and the opening of the fourth regulating valve is negatively correlated with the temperature of the seawater entering the flash chamber from the third inlet; a fifth regulating valve is arranged between the circulation pump and the fourth inlet, a third temperature controller is arranged at the seventh inlet, a control signal of the third temperature controller is connected to the fifth regulating valve through a wire, and the opening of the fifth regulating valve is positively correlated with the temperature at the seventh inlet.

[0013] As a further preference, a first stop valve is arranged between the first drainage pump and the second outlet, a third stop valve is arranged at the smoke outlet, and a second stop valve is arranged at the seventh inlet and the fourth outlet.

[0014] As a further preference, a flue gas purifier is provided at the flue gas inlet.

[0015] As a further preference, the working fluid of the organic Rankine cycle is one or a combination of R245fa and R123.

[0016] As a further preference, the outer surfaces of the first heat recovery heat exchange tube and the second heat recovery heat exchange tube are provided with corrosion-resistant enhanced heat exchange fins, and the first heat recovery heat exchange tube and the second heat recovery heat exchange tube are "S" shaped as a whole.

[0017] As a further preference, the waste heat seawater desalination device is a detachable structure, and the sealing plate is connected to the inner wall of the waste heat seawater desalination device via a connecting flange.

[0018] A working method applicable to the ship low-temperature flue gas waste heat power generation and seawater desalination system of the present invention comprises the following steps:

[0019] S1, seawater enters the flash chamber for desalination, and finally flows out through the first drainage pump for the crew's daily use;

[0020] S11, evacuate the flash chamber until the vacuum degree reaches a set value;

[0021] S12, opening the first regulating valve, the second regulating valve, the water supply pump and the fourth regulating valve, so that the seawater enters the condenser pipe of the flash chamber in one way and passes through the condenser in the other way to respectively recover the steam condensation latent heat and the working fluid condensation latent heat;

[0022] S13, the seawater passing through the condenser pipe and the condenser merges and then flows into the second heat recovery heat exchange pipe to recover the waste heat of the flue gas introduced by the fourth regulating valve;

[0023] S14, after the temperature of the seawater in the second heat recovery heat exchange tube increases, it enters the flash chamber through the pressure reducing valve for flash evaporation. The steam obtained by flash evaporation is condensed into fresh water by the low-temperature seawater on the surface of the condenser tube, drips onto the water collecting plate, and is finally transported outward through the first drainage pump;

[0024] S15, when the liquid level of the unevaporated seawater in the flash chamber is higher than the set value, the liquid level controller sends a control signal to the third regulating valve to increase the opening of the third regulating valve, and the unevaporated seawater enters the drainage heat recovery heat exchanger through the third regulating valve and the second drainage pump to release heat and then be discharged;

[0025] S16, when the pressure detected by the pressure controller is higher than the set value, the pressure controller sends a control signal to the first regulating valve to increase the opening of the first regulating valve; otherwise, the opening of the first regulating valve is reduced;

[0026] S17, when the temperature detected by the second temperature controller is higher than the set value, a control signal is sent to the fourth regulating valve to reduce the opening of the fourth regulating valve; otherwise, the opening of the fourth regulating valve is increased;

[0027] S2, the working fluid of the organic Rankine cycle starts from the working fluid pump, passes through the drainage heat recovery heat exchanger, evaporator, expander, condenser in sequence, and finally returns to the working fluid pump. The working fluid performs expansion work at the expander to drive the generator to generate electricity;

[0028] S21, opening the working fluid pump and the fifth regulating valve, sending the working fluid liquid into the drainage heat recovery heat exchanger to absorb the heat of the unevaporated seawater discharged by the second drainage pump, and obtaining the preheated working fluid liquid;

[0029] S22, the hot water in the hot water tank enters the first heat recovery heat exchange pipe through the circulation pump and the fifth regulating valve to absorb the heat of the flue gas to obtain the hot water after heat absorption, and the hot water after heat absorption enters the evaporator;

[0030] S23, the preheated working fluid enters the evaporator to absorb the heat of the hot water after absorbing heat, evaporates into high-temperature and high-pressure steam, and then expands through the expander and outputs expansion work to drive the engine to generate electricity; the hot water after cooling in the evaporator returns to the hot water tank;

[0031] S24, the expanded low-temperature and low-pressure working fluid gas enters the condenser, releases heat and condenses before continuing the next cycle;

[0032] S25. When the temperature detected by the first temperature controller is higher than the set value, a control signal is sent to the second regulating valve to increase the opening of the second regulating valve; otherwise, the opening of the second regulating valve is reduced.

[0033] S26. When the temperature detected by the third temperature controller is lower than the set value, a control signal is sent to the fifth regulating valve to reduce the opening of the fifth regulating valve; otherwise, the opening of the fifth regulating valve is increased.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention utilizes organic Rankine cycle (ORC) waste heat power generation and low-temperature seawater desalination technology to deeply recover the waste heat of flue gas generated by ship waste heat boilers, can reduce the flue gas emission temperature to below 100°C, and can convert waste heat into mechanical energy or electrical energy. It has the characteristics of high thermal efficiency and simple structure.

[0036] 2. The present invention expands and integrates the Organic Rankine Cycle (ORC) waste heat power generation technology into the existing limited ship deck space, thereby integrating multiple systems within a limited space.

[0037] 3. The present invention effectively improves the utilization rate of waste heat of ships, and couples the organic Rankine cycle (ORC) to simultaneously realize seawater desalination and waste heat power generation, saving space on board.

[0038] 4. In the system of the present invention, the flue gas first heats the fresh water and then heats the seawater, and the high-temperature seawater is flash evaporated and condensed to obtain fresh water, so as to solve the problem of water shortage of ocean-going ships; at the same time, the ORC cycle is introduced to recover the condensation latent heat of the high-temperature steam, which is then expanded by the expander and the expansion work is output to drive the engine to generate electricity, and the waste heat of the flue gas is used in a cascade manner to realize seawater desalination and waste heat power generation.

[0039] 5. Compared with existing seawater desalination and power generation devices, this system does not require additional steam during operation, reducing system energy consumption, and can automatically adjust the flue gas flow and water flow, with simple control, greatly improving the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the overall structure and connection relationship of the system of the present invention.

[0041] Indicated in the figure:

[0042] 1. Waste heat seawater desalination device; 2. Condenser; 3. Evaporator; 4. Expander; 5. Drainage heat recovery heat exchanger; 6. Hot water tank; 7. Circulation pump; 8. Working fluid pump; 9. Water supply pump; 10. First drainage pump; 11. Second drainage pump; 12. First regulating valve; 13. Second regulating valve; 14. Third regulating valve; 15. Fourth regulating valve; 16. Fifth regulating valve; 17. Pressure reducing valve; 18. First stop valve; 19. Second stop valve; 20. Third stop valve; 21. Pressure controller; 22. First temperature controller; 23. Liquid level controller; 24. Second temperature controller; 25. Third temperature controller; 26. Flue gas purifier; 27. Generator; 1a, water collecting plate; 1b, condenser; 1c, first heat recovery heat exchange tube; 1d, second heat recovery heat exchange tube; 1e, flue gas inlet; 1f, flue gas outlet; 1g, sealing plate; a1, first inlet; a2, second inlet; a3, first outlet; a4, third inlet; a5, second outlet; a6, third outlet; a7, fourth inlet; a8, fourth outlet; b1, fifth inlet; b2, fifth outlet; b3, sixth inlet; b4, sixth outlet; c1, seventh inlet; c2, seventh outlet; c3, eighth inlet; c4, eighth outlet; d1, ninth inlet; d2, ninth outlet; d3, tenth inlet; d4, tenth outlet. DETAILED DESCRIPTION

[0043] Advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments thereof, which are given by way of example only with reference to the accompanying drawings.

[0044] like Figure 1 As shown, the present invention provides a ship low-temperature flue gas waste heat power generation and seawater desalination system, including a waste heat seawater desalination device 1, an organic Rankine cycle ORC and a hot water cycle. A sealing plate 1g is horizontally arranged in the middle of the waste heat seawater desalination device 1, and the sealing plate 1g divides the waste heat seawater desalination device 1 into two parts, the upper half of the waste heat seawater desalination device 1 is a flash chamber, including a water collecting plate 1a and a condenser 1b; the lower half of the waste heat seawater desalination device 1 is a flue gas heat recovery heat exchange chamber, including a flue gas inlet 1e, a flue gas outlet 1f, a first heat recovery heat exchange pipe 1c and a second heat recovery heat exchange pipe 1d. Preferably, the waste heat seawater desalination device 1 can be disassembled, and the sealing plate 1g is connected to the inner wall of the waste heat seawater desalination device 1 through a connecting flange, which is convenient for cleaning the outer surface of the heat recovery heat exchange pipe in the flue gas heat recovery heat exchange chamber, thereby ensuring the heat recovery efficiency of the system and extending its service life.

[0045] The water collecting plate 1a and the condenser 1b are both arranged horizontally, and the water collecting plate 1a is arranged below the condenser 1b. The bottom of the water collecting plate 1a is connected to the second outlet a5 through a pipeline. The second outlet a5 is the outlet of the fresh water after distillation in the flash chamber. The second outlet a5 is connected to the first drainage pump 10. In order to better control the discharge volume of fresh water, a first stop valve 18 can be set between the first drainage pump 10 and the second outlet a5.

[0046] One end of the condenser pipe 1b is connected to the first inlet a1, and the other end is connected to the second inlet a2 through the waste heat seawater desalination device 1 through a pipeline. The first inlet a1 is the seawater inlet of the flash chamber, and the second inlet a2 is the inlet of the second heat recovery heat exchange pipe 1d of the flue gas heat recovery heat exchange chamber. The flue gas inlet 1e is arranged at the bottom of the flue gas heat recovery heat exchange chamber. The flue gas outlet 1f is arranged at the top of the flue gas heat recovery heat exchange chamber, that is, below the sealing plate 1g. The first heat recovery heat exchange pipe 1c is arranged below the second heat recovery heat exchange pipe 1d. In order to make the heat exchange efficiency higher, the first heat recovery heat exchange pipe 1c and the second heat recovery heat exchange pipe 1d can be arranged in an "S" shape. One end of the first heat recovery heat exchange pipe 1c is connected to the fourth inlet a7, and the other end is connected to the fourth outlet a8. One end of the second heat recovery heat exchange pipe 1d is connected to the second inlet a2, and the other end is connected to the first outlet a3, and the first outlet a3 is a high-temperature seawater outlet. The first inlet a1 is connected to the outlet of the water supply pump 9 on the outside, and the outlet of the water supply pump 9 is also connected to the sixth inlet b3, which is the seawater inlet of the condenser 2. The seawater outlet of the condenser 2, i.e., the sixth outlet b4, is connected to the second inlet a2 through a pipeline. In order to facilitate the control of the flow in the pipeline, a first regulating valve 12 is provided between the first inlet a1 and the water supply pump 9, and a second regulating valve 13 is provided between the sixth inlet b3 and the water supply pump 9.

[0047] The seawater passes through the water supply pump 9 through the first regulating valve 12, enters the condenser 1b in the flash chamber through the first inlet a1, and then enters the second heat recovery heat exchange tube 1d in the flue gas heat recovery heat exchange chamber through the second inlet a2; the seawater passes through the water supply pump 9 through the second regulating valve 13, enters the sixth inlet b3 of the condenser 2, and then enters the second heat recovery heat exchange tube 1d in the flue gas heat recovery heat exchange chamber from the sixth outlet b4 of the condenser 2 through the pipeline through the second inlet a2.

[0048] The first outlet a3 is connected to the third inlet a4 through a pipeline and a pressure reducing valve 17. The third inlet a4 is the high-temperature seawater inlet of the flash chamber, and the third inlet a4 is arranged below the water collecting plate 1a. The bottom of the flash chamber, that is, above the sealing plate 1g, is provided with a third outlet a6, which is the discharge outlet of the concentrated brine after flash evaporation concentration. The third outlet a6 is connected to the second drainage pump 11 through a pipeline. In order to facilitate the control of the pipeline flow, a third regulating valve 14 can be arranged between the second drainage pump 11 and the third outlet a6. The other end of the second drainage pump 11 is connected to the tenth inlet d3 through a pipeline, and the tenth inlet d3 is the concentrated brine inlet of the drainage heat recovery heat exchanger 5. The flue gas inlet 1e is provided with a flue gas purifier 26 and a fourth regulating valve 15, and the flue gas outlet 1f is provided with a third stop valve 20 for discharge. The flue gas first exchanges heat with the hot water in the first heat recovery heat exchange tube 1c and then heats the seawater in the second heat recovery heat exchange tube 1d. The high-temperature waste heat section is used to heat the hot water for the operation of the organic Rankine cycle ORC, while the low-temperature waste heat section is used for heating and flash evaporation of seawater to achieve low-temperature seawater desalination and avoid scaling and corrosion problems caused by high temperature.

[0049] The organic Rankine cycle ORC includes a condenser 2, a working fluid pump 8, a wastewater heat recovery heat exchanger 5, an evaporator 3 and an expander 4. The condenser 2 includes a fifth inlet b1, a fifth outlet b2, a sixth inlet b3 and a sixth outlet b4, wherein the fifth inlet b1 is the working fluid inlet of the condenser 2, the fifth outlet b2 is the working fluid outlet of the condenser 2, the sixth inlet b3 is the seawater inlet of the condenser 2, and the sixth outlet b4 is the seawater outlet of the condenser 2; the wastewater heat recovery heat exchanger 5 includes a ninth inlet d1, a ninth outlet d2, a tenth inlet d3 and a tenth outlet d4, wherein the ninth inlet d1 is the working fluid inlet of the wastewater heat recovery heat exchanger 5, and the ninth outlet d 2 is the working fluid outlet of the drainage heat recovery heat exchanger 5, the tenth inlet d3 is the concentrated brine inlet of the drainage heat recovery heat exchanger 5, and the tenth outlet d4 is the concentrated brine outlet of the drainage heat recovery heat exchanger 5 after heat exchange; the evaporator 3 includes the seventh inlet c1, the seventh outlet c2, the eighth inlet c3 and the eighth outlet c4, the seventh inlet c1 is the hot water inlet of the evaporator 3, the seventh outlet c2 is the hot water outlet of the evaporator 3, the eighth inlet c3 is the working fluid inlet of the evaporator 3, and the eighth outlet c4 is the working fluid outlet of the evaporator 3. The eighth outlet c4 is connected to the inlet of the expander 4 through a pipeline, the outlet of the expander 4 is connected to the fifth inlet b1 through a pipeline, the fifth outlet b2 is connected to the ninth inlet d1 through a pipeline via a working fluid pump 8, the ninth outlet d2 is connected to the eighth inlet c3 through a pipeline, and the expander 4 is also connected to the generator 27 for power generation.

[0050] The hot water circulation includes an evaporator 3, a hot water tank 6, a circulation pump 7, a fifth regulating valve 16, a first heat recovery heat exchange pipe 1c and a second stop valve 19. The seventh outlet c2 is connected to the hot water tank 6 through a pipeline, the other end of the hot water tank 6 is connected to the circulation pump 7 and the fifth regulating valve 16, the other end of the fifth regulating valve 16 is connected to the fourth inlet a7, and the fourth outlet a8 is connected to the seventh inlet c1 through a pipeline via the second stop valve 19. The high-temperature hot water or steam generated in the first heat recovery heat exchange pipe 1c enters the evaporator 3 to release heat for the organic working fluid to absorb heat and evaporate.

[0051] The working fluid of the organic Rankine cycle ORC is R245fa and R123 alone or in combination, or other new working fluids suitable for recovering 100-150° C. waste heat for power generation.

[0052] The outer surfaces of the first heat recovery heat exchange tube 1c and the second heat recovery heat exchange tube 1d in the flue gas heat recovery heat exchange chamber are provided with corrosion-resistant enhanced heat exchange fins to improve heat exchange efficiency and reduce maintenance costs.

[0053] A pressure controller 21 is provided at the top of the flash chamber, and the control signal of the pressure controller 21 is connected to the first regulating valve 12 through a wire; the pressure in the flash chamber is regulated by the pressure controller 21 in combination with the first regulating valve 12, and the opening of the first regulating valve 12 is positively correlated with the pressure in the flash chamber. When the pressure in the flash chamber is higher than the set value, the opening of the first regulating valve 12 is increased, thereby increasing the flow of low-temperature seawater entering the flash chamber, so that the flash steam can be condensed in time. A liquid level controller 23 is provided below the water collecting plate 1a of the flash chamber, and the control signal of the liquid level controller 23 is connected to the third regulating valve 14 through a wire; the opening of the third regulating valve 14 is controlled by the signal of the liquid level controller 23, and the opening of the third regulating valve 14 increases when the liquid level rises, thereby increasing the discharge flow of the concentrated brine after passing through the flash chamber.

[0054] A first temperature controller 22 is provided at the fifth outlet b2. The control signal of the first temperature controller 22 is connected to the second regulating valve 13 through a wire. The first temperature controller 22 cooperates with the second regulating valve 13 to adjust the working medium temperature at the fifth outlet b2. When the working medium temperature at the fifth outlet b2 is greater than the set value, the first temperature controller 22 sends a control signal to the second regulating valve 13, and the opening of the second regulating valve 13 increases, thereby increasing the flow rate of low-temperature seawater entering the condenser 2, so that the working medium is cooled in time; otherwise, the opening of the second regulating valve 13 is reduced.

[0055] A second temperature controller 24 is provided on the pipeline between the first outlet a3 and the pressure reducing valve 17. The control signal of the second temperature controller 24 is connected to the fourth regulating valve 15 through a wire. The temperature of the seawater entering the flash chamber from the third inlet a4 can be controlled by the cooperation of the second temperature controller 24 and the fourth regulating valve 15. The opening of the fourth regulating valve 15 is negatively correlated with the temperature of the seawater entering the flash chamber from the third inlet a4. When the seawater temperature detected by the second temperature controller 24 is higher than the set value, the opening of the fourth regulating valve 15 is reduced, thereby reducing the flue gas flow rate of the flue gas entering the system; otherwise, the opening of the fourth regulating valve 15 is increased, thereby increasing the flue gas flow rate of the flue gas entering the system.

[0056] The seventh inlet c1 is provided with a third temperature controller 25, and the control signal of the third temperature controller 25 is connected to the fifth regulating valve 16 through a wire. The opening of the fifth regulating valve 16 is positively correlated with the temperature at the seventh inlet c1. When the temperature detected by the third temperature controller 25 is higher than the set value, a control signal is sent to the fifth regulating valve 16, and the fifth regulating valve 16 increases its opening, thereby increasing the flow of hot water entering the first heat recovery heat exchange pipe 1c, so that the temperature of the hot water after the flue gas heat exchange is reduced, and the temperature of the hot water flowing into the evaporator 3 is guaranteed; otherwise, the opening of the fifth regulating valve 16 is reduced. Considering that the flue gas flow rate and temperature will change, the water flow rate is adjusted according to the heat source inlet temperature to ensure the temperature of the expander 4 inlet. Compared with the flue gas directly heating the working medium, the working medium evaporation temperature can be more accurately controlled, and the stability of the system operation is improved.

[0057] The present invention generally comprises four cycles, namely, a seawater desalination cycle, a flue gas cycle, an organic Rankine cycle (ORC) and a hot water cycle.

[0058] The seawater in the seawater desalination cycle starts from the water supply pump 9, and one loop passes through the first regulating valve 12, the first inlet a1, the condenser 1b, the second inlet a2, the second heat recovery heat exchange pipe 1d, the first outlet a3, the pressure reducing valve 17, the third inlet a4, the third outlet a6, the third regulating valve 14, the second drainage pump 11, the tenth inlet d3, and finally is discharged through the tenth outlet d4; the other loop passes through the second regulating valve 13, the sixth inlet b3, the sixth outlet b4, the second inlet a2, the second heat recovery heat exchange pipe 1d, the first outlet a3, the pressure reducing valve 17, the third inlet a4, the third outlet a6, the third regulating valve 14, the second drainage pump 11, the tenth inlet d3, and finally is discharged through the tenth outlet d4. One of the loops directly enters the second heat recovery heat exchange pipe 1d through the second inlet a2 to exchange heat with the flue gas; the other loop first enters the condenser 2 through the sixth inlet b3 to exchange heat with the working medium in the condenser 2, and then enters the second heat recovery heat exchange pipe 1d through the sixth outlet b4 to exchange heat with the flue gas; the two loops converge to the third inlet a4 to enter the flash chamber. At this time, the high-temperature seawater entering the flash chamber vaporizes and liquefies on the surface of the condenser tube 1b and drips onto the water collecting plate 1a, and finally passes through the pipeline at the bottom of the water collecting plate 1a through the second outlet a5, the first stop valve 18 and the first drainage pump 10 for the crew's life.

[0059] The flue gas cycle passes through the flue gas purifier 26, the fourth regulating valve 15, the flue gas inlet 1e, the flue gas outlet 1f in sequence, and finally is discharged from the hull through the third stop valve 20. The flue gas in the flue gas cycle exchanges heat with the hot water in the first heat recovery heat exchange pipe 1c and the seawater in the second heat recovery heat exchange pipe 1d in the flue gas heat recovery heat exchange chamber, and finally the low-temperature flue gas after heat exchange is discharged from the hull from the third stop valve 20.

[0060] The hot water circulation starts from the hot water tank 6, passes through the circulation pump 7, the fifth regulating valve 16, the fourth inlet a7, the first heat recovery heat exchange pipe 1c, the fourth outlet a8, the second stop valve 19, the seventh inlet c1, the evaporator 3, the seventh outlet c2, and finally returns to the hot water tank 6. The hot water in the hot water circulation undergoes heat exchange twice in the evaporator 3 and the first heat recovery heat exchange pipe 1c, first exchanges heat with the high-temperature flue gas through the first heat recovery heat exchange pipe 1c to absorb the heat energy of the high-temperature flue gas, and then enters the evaporator 3 to exchange heat with the working medium to release heat energy.

[0061] The organic Rankine cycle ORC starts from the working fluid pump 8, passes through the ninth inlet d1, the drainage heat recovery heat exchanger 5, the ninth outlet d2, the eighth inlet c3, the evaporator 3, the eighth outlet c4, the expander 4, the fifth inlet b1, the condenser 2, the fifth outlet b2, and finally returns to the working fluid pump 8. The working fluid liquid in the working fluid pump 8 first exchanges heat with the seawater with a high salinity concentrated by the flash chamber through the drainage heat recovery heat exchanger 5 to obtain preliminary waste heat, then enters the evaporator 3 to absorb the heat of the high-temperature hot water or steam that exchanges heat with the high-temperature flue gas and evaporates into high-temperature and high-pressure steam, then expands through the expander 4, and outputs expansion work to drive the generator to generate electricity, and the expanded low-temperature and low-pressure working fluid gas enters the condenser 2, and after the seawater in the condenser 2 releases heat and condenses, it flows into the working fluid pump 8 to continue the next cycle.

[0062] The working method of a ship low-temperature flue gas waste heat power generation and seawater desalination system of the present invention comprises the following specific steps:

[0063] Step 1: Seawater enters the flash chamber for desalination and finally flows out through the first drainage pump 10 for the crew's daily use.

[0064] Step 11, evacuate the flash chamber until the vacuum degree reaches a set value;

[0065] Step 12, open the first regulating valve 12, the second regulating valve 13 and the water supply pump 9, and the fourth regulating valve 15 of the flue gas inlet 1e, so that the seawater enters the condenser pipe 1b of the flash chamber in one way and passes through the condenser 2 in the other way to recover the steam condensation latent heat and the working medium condensation latent heat respectively;

[0066] Step 13, the seawater passing through the condenser pipe 1b and the condenser 2 merges and then flows into the second heat recovery heat exchange pipe 1d in the flue gas heat recovery heat exchange chamber to recover the waste heat of the flue gas introduced by the fourth regulating valve 15;

[0067] Step 14, after the temperature of the seawater in the second heat recovery heat exchange pipe 1d increases, it enters the flash chamber through the pressure reducing valve 17 for flash evaporation. The steam obtained by flash evaporation is condensed into fresh water by the low-temperature seawater on the surface of the condenser pipe 1b, drips onto the water collecting plate 1a, and is finally transported outward through the first drainage pump 10 to meet the water demand of the ship;

[0068] Step 15: When the liquid level of the unevaporated seawater in the flash chamber is higher than the set value, the liquid level controller 23 sends a control signal to the third regulating valve 14 to increase the opening of the third regulating valve 14, and the unevaporated seawater enters the drainage heat recovery heat exchanger 5 through the third regulating valve 14 and the second drainage pump 11 to release heat and then be discharged;

[0069] Step 16, when the pressure detected by the pressure controller 21 is higher than the set value, the pressure controller 21 sends a control signal to the first regulating valve 12 to increase the opening of the first regulating valve 12, thereby increasing the flow of seawater entering the flash chamber to condense the flash steam in time; otherwise, the opening of the first regulating valve 12 is reduced.

[0070] Step 17, when the temperature detected by the second temperature controller 24 is higher than the set value, a control signal is sent to the fourth regulating valve 15 to reduce the opening of the fourth regulating valve 15, thereby reducing the flue gas flow entering the system; otherwise, the opening of the fourth regulating valve 15 is increased.

[0071] Step 2: The working fluid of the organic Rankine cycle starts from the working fluid pump 8, passes through the drainage heat recovery heat exchanger 5, the evaporator 3, the expander 4, the condenser 2 in sequence, and finally returns to the working fluid pump 8. The working fluid performs expansion work at the expander 4 to drive the generator 27 to generate electricity.

[0072] Step 21, open the working fluid pump 8 and the fifth regulating valve 16 of the organic Rankine cycle, send the working fluid liquid into the drainage heat recovery heat exchanger 5 to absorb the heat of the unevaporated seawater discharged by the second drainage pump 11, and obtain the preheated working fluid liquid;

[0073] Step 22, the hot water in the hot water tank 6 enters the first heat recovery heat exchange pipe 1c of the flue gas heat recovery heat exchange chamber through the circulation pump 7 and the fifth regulating valve 16 to absorb the heat of the flue gas to obtain the hot water after heat absorption. According to the different flue gas temperatures, the hot water may partially evaporate or completely evaporate in the first heat recovery heat exchange pipe 1c, and the hot water or steam after heat absorption then enters the evaporator 3 to release heat for the organic working fluid to absorb heat and evaporate;

[0074] Step 23, the preheated working fluid enters the evaporator 3 to absorb the heat of the hot water after endothermic treatment, evaporates into high-temperature and high-pressure steam, and then expands through the expander 4 and outputs expansion work to drive the engine 27 to generate electricity; the hot water cooled in the evaporator 3 returns to the hot water tank 6.

[0075] Step 24: The expanded low-temperature and low-pressure working fluid gas enters the condenser 2, releases heat and condenses to continue the next cycle.

[0076] Step 25, when the temperature detected by the first temperature controller 22 is higher than the set value, a control signal is sent to the second regulating valve 13 to increase the opening of the second regulating valve 13, thereby increasing the flow of seawater entering the condenser 2 to condense the working medium in time; otherwise, the opening of the second regulating valve 13 is reduced.

[0077] Step 26: When the temperature detected by the third temperature controller 25 is lower than the set value, a control signal is sent to the fifth regulating valve 16 to reduce the opening of the fifth regulating valve 16 and reduce the circulation flow of the hot water; otherwise, the opening of the fifth regulating valve 16 is increased.

[0078] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A ship low-temperature flue gas waste heat power generation and seawater desalination system, characterized in that: It comprises a waste heat seawater desalination device (1), an organic Rankine cycle and a hot water cycle, wherein a sealing plate (1g) is horizontally arranged in the middle of the waste heat seawater desalination device (1), and the sealing plate (1g) divides the waste heat seawater desalination device (1) into an upper flash chamber and a lower flue gas heat recovery heat exchange chamber; The flash chamber comprises a horizontally arranged water collecting plate (1a) and a condensing pipe (1b), wherein the water collecting plate (1a) is arranged below the condensing pipe (1b), and the lower part of the water collecting plate (1a) is connected to a second outlet (a5) and a first drainage pump (10) in sequence through a pipeline; one end of the condensing pipe (1b) is connected to the first inlet (a1), and the other end is connected to the second inlet (a2) through a pipeline; The flue gas heat recovery heat exchange chamber comprises a flue gas inlet (1e) arranged at the bottom, a flue gas outlet (1f) arranged below the sealing plate (1g), a first heat recovery heat exchange pipe (1c) arranged near the flue gas inlet (1e), and a second heat recovery heat exchange pipe (1d) arranged near the flue gas outlet (1f), wherein one end of the first heat recovery heat exchange pipe (1c) is connected to the fourth inlet (a7) and the other end is connected to the fourth outlet (a8), and one end of the second heat recovery heat exchange pipe (1d) is connected to the second inlet (a2) and the other end is connected to the first outlet (a3); the first inlet (a1) is connected to the outlet of the water supply pump (9), and the outlet of the water supply pump (9) is also connected to the organic Rankine cycle. The first outlet (a3) ​​is connected to the third inlet (a4) through a pipeline and a pressure reducing valve (17). The third inlet (a4) is arranged below the water collecting plate (1a). A third outlet (a6) is arranged above the sealing plate (1g). The third outlet (a6) is connected to the second drainage pump (11) through a pipeline. The other end of the second drainage pump (11) is connected to the organic Rankine cycle. The hot water circulation is respectively connected to the fourth inlet (a7), the fourth outlet (a8) and the organic Rankine cycle; The organic Rankine cycle is also connected to a generator (27) for generating electricity.

2. The ship low-temperature flue gas waste heat power generation and seawater desalination system according to claim 1 is characterized by: The organic Rankine cycle comprises a condenser (2), a working fluid pump (8), a wastewater heat recovery heat exchanger (5), an evaporator (3) and an expander (4) connected in sequence; the condenser (2) comprises a fifth inlet (b1), a fifth outlet (b2), a sixth inlet (b3) and a sixth outlet (b4); the wastewater heat recovery heat exchanger (5) comprises a ninth inlet (d1), a ninth outlet (d2), a tenth inlet (d3) and a tenth outlet (d4); the evaporator (3) comprises a seventh inlet (c1), a seventh outlet (c2), an eighth inlet (c3) and an eighth outlet (c4); the fifth inlet (b1) and the expander (4) are connected in sequence; The outlet of the expander (4) is connected, the fifth outlet (b2) is connected to the working fluid pump (8), the sixth inlet (b3) is connected to the water supply pump (9), and the sixth outlet (b4) is connected to the second inlet (a2); the ninth inlet (d1) is connected to the working fluid pump (8), the ninth outlet (d2) is connected to the eighth inlet (c3), and the tenth inlet (d3) is connected to the second drainage pump (11); the seventh inlet (c1) is connected to the fourth outlet (a8), the seventh outlet (c2) is connected to the hot water circulation, and the eighth outlet (c4) is connected to the inlet of the expander (4); the expander (4) is also connected to a generator (27).

3. The ship low-temperature flue gas waste heat power generation and seawater desalination system according to claim 2 is characterized by: The hot water circulation comprises a hot water tank (6) and a circulation pump (7); one end of the hot water tank (6) is connected to the seventh outlet (c2) and the other end is connected to the circulation pump (7); the circulation pump (7) is also connected to the fourth inlet (a7).

4. The ship low-temperature flue gas waste heat power generation and seawater desalination system according to claim 3 is characterized by: A first regulating valve (12) is arranged between the first inlet (a1) and the water supply pump (9), a pressure controller (21) is arranged at the top of the flash chamber, a control signal of the pressure controller (21) is connected to the first regulating valve (12) through a wire, and the opening of the first regulating valve (12) is positively correlated with the pressure in the flash chamber; a third regulating valve (14) is arranged between the second drainage pump (11) and the third outlet (a6), a liquid level controller (23) is arranged below the water collecting plate (1a), and a control signal of the liquid level controller (23) is connected to the third regulating valve (14) through a wire; a second regulating valve (13) is arranged between the sixth inlet (b3) and the water supply pump (9), a first temperature controller (22) is arranged at the fifth outlet (b2), and a control signal of the first temperature controller (22) is connected to the third regulating valve (14) through a wire. A second regulating valve (13) is connected via a wire; a fourth regulating valve (15) is arranged at the flue gas inlet (1e); a second temperature controller (24) is arranged on the pipeline between the first outlet (a3) ​​and the pressure reducing valve (17); a control signal of the second temperature controller (24) is connected to the fourth regulating valve (15) via a wire; the opening of the fourth regulating valve (15) is negatively correlated with the temperature of seawater entering the flash chamber from the third inlet (a4); a fifth regulating valve (16) is arranged between the circulating pump (7) and the fourth inlet (a7); a third temperature controller (25) is arranged at the seventh inlet (c1); a control signal of the third temperature controller (25) is connected to the fifth regulating valve (16) via a wire; the opening of the fifth regulating valve (16) is positively correlated with the temperature at the seventh inlet (c1).

5. The ship low-temperature flue gas waste heat power generation and seawater desalination system according to claim 4 is characterized in that: A first stop valve (18) is provided between the first drainage pump (10) and the second outlet (a5), a third stop valve (20) is provided at the smoke outlet (1f), and a second stop valve (19) is provided at the seventh inlet (c1) and the fourth outlet (a8).

6. The ship low-temperature flue gas waste heat power generation and seawater desalination system according to claim 4 is characterized by: A flue gas purifier (26) is provided at the flue gas inlet (1e).

7. The ship low-temperature flue gas waste heat power generation and seawater desalination system according to claim 4 is characterized by: The working fluid of the organic Rankine cycle is one or a combination of R245fa and R123.

8. The ship low-temperature flue gas waste heat power generation and seawater desalination system according to claim 4 is characterized by: The outer surfaces of the first heat recovery heat exchange tube (1c) and the second heat recovery heat exchange tube (1d) are provided with corrosion-resistant enhanced heat exchange fins, and the first heat recovery heat exchange tube (1c) and the second heat recovery heat exchange tube (1d) are in an "S" shape as a whole.

9. The ship low-temperature flue gas waste heat power generation and seawater desalination system according to claim 4 is characterized by: The waste heat seawater desalination device (1) is a detachable structure, and the sealing plate (1g) is connected to the inner wall of the waste heat seawater desalination device (1) via a connecting flange.

10. A working method applicable to the ship low-temperature flue gas waste heat power generation and seawater desalination system according to any one of claims 5 to 9, characterized in that: The steps include: S1, seawater enters the flash chamber for desalination and finally flows out through the first drainage pump (10) for the crew's daily use; S11, evacuate the flash chamber until the vacuum degree reaches a set value; S12, opening the first regulating valve (12), the second regulating valve (13), the water supply pump (9) and the fourth regulating valve (15), so that the seawater enters the condensation pipe (1b) of the flash chamber in one way and passes through the condenser (2) in the other way to respectively recover the steam condensation latent heat and the working fluid condensation latent heat; S13, the seawater passing through the condenser (1b) and the condenser (2) merges and then flows into the second heat recovery heat exchange pipe (1d) to recover the waste heat of the flue gas introduced by the fourth regulating valve (15); S14, after the temperature of the seawater in the second heat recovery heat exchange pipe (1d) increases, it enters the flash chamber through the pressure reducing valve (17) for flash evaporation, and the steam obtained by flash evaporation is condensed into fresh water by the low-temperature seawater on the surface of the condenser (1b), drips onto the water collecting plate (1a), and is finally transported outward through the first drainage pump (10); S15, when the liquid level of the unevaporated seawater in the flash chamber is higher than the set value, the liquid level controller (23) sends a control signal to the third regulating valve (14) to increase the opening of the third regulating valve (14), and the unevaporated seawater enters the drainage heat recovery heat exchanger (5) through the third regulating valve (14) and the second drainage pump (11) to release heat and then be discharged; S16, when the pressure detected by the pressure controller (21) is higher than the set value, the pressure controller (21) sends a control signal to the first regulating valve (12) to increase the opening of the first regulating valve (12); otherwise, the opening of the first regulating valve (12) is reduced; S17, when the temperature detected by the second temperature controller (24) is higher than the set value, a control signal is sent to the fourth regulating valve (15) to reduce the opening of the fourth regulating valve (15); otherwise, the opening of the fourth regulating valve (15) is increased; S2, the working fluid of the organic Rankine cycle starts from the working fluid pump (8), passes through the drainage heat recovery heat exchanger (5), the evaporator (3), the expander (4), the condenser (2), and finally returns to the working fluid pump (8). The working fluid performs expansion work at the expander (4) to drive the generator (27) to generate electricity; S21, opening the working fluid pump (8) and the fifth regulating valve (16), sending the working fluid liquid into the drainage heat recovery heat exchanger (5) to absorb the heat of the unevaporated seawater discharged by the second drainage pump (11), and obtaining a preheated working fluid liquid; S22, the hot water in the hot water tank (6) enters the first heat recovery heat exchange pipe (1c) through the circulation pump (7) and the fifth regulating valve (16) to absorb the heat of the flue gas to obtain hot water after heat absorption, and the hot water after heat absorption enters the evaporator (3); S23, the preheated working fluid enters the evaporator (3) to absorb the heat of the hot water after absorbing heat, evaporates into high-temperature and high-pressure steam, and then expands through the expander (4) and outputs expansion work to drive the engine (27) to generate electricity; the hot water after cooling in the evaporator (3) returns to the hot water tank (6); S24, the expanded low-temperature and low-pressure working fluid gas enters the condenser (2), releases heat and condenses, and then continues the next cycle; S25. When the temperature detected by the first temperature controller (22) is higher than the set value, a control signal is sent to the second regulating valve (13) to increase the opening of the second regulating valve (13); otherwise, the opening of the second regulating valve (13) is reduced. S26. When the temperature detected by the third temperature controller (25) is lower than the set value, a control signal is sent to the fifth regulating valve (16) to reduce the opening of the fifth regulating valve (16); otherwise, the opening of the fifth regulating valve (16) is increased.

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