CN111573764A - Cold-hot coupling tower type seawater desalination system utilizing ship waste heat and application method - Google Patents

Abstract

The invention discloses a cold-heat coupled tower-type seawater desalination system and an application method using the waste heat of ships, belonging to the technical field of absorption refrigeration and seawater desalination. This cooling and heating coupled tower desalination system utilizing ship waste heat includes absorption refrigeration system and tower low temperature multi-effect evaporation system. The cascade of the system utilizes the heat of the exhaust of the marine diesel engine and the cooling water of the diesel cylinder liner, and treats the normal temperature seawater into 7 ℃ brine for the air conditioning and refrigeration of the ship, which greatly reduces the power consumption of the ship. This cold-heat coupled tower seawater desalination system utilizing the ship's waste heat replaces the evaporator and the condenser in the absorption refrigeration system through a tower-type multi-effect evaporation device, and couples the seawater desalination device and the air-conditioning refrigeration device to reduce the size of the system. The footprint of the device saves ship space. It solves the problem that the temperature range of low-temperature multiple-effect evaporation cannot be expanded due to the limitation of the cooling water temperature of the condenser.

Description

Cool and heat coupled tower seawater desalination system and application method using ship waste heat

technical field

The invention relates to a cold-heat coupled tower-type seawater desalination system and an application method using the waste heat of ships, and belongs to the technical field of absorption refrigeration and seawater desalination.

Background technique

With the rapid development of ship technology, the demand for fresh water and the cooling capacity are also increasing. Marine seawater desalination and air conditioning devices have become important equipment to ensure the ship's endurance. Ship power plant and crew life consume a lot of fresh water, and the power consumption of ship air-conditioning device is close to half of the ship's power consumption. In the case of not increasing the ship's load and power machinery energy consumption, generating enough fresh water and cooling capacity has become the development direction to improve the energy-saving and economical efficiency of ships.

Most of the heat generated by combustion in the cylinder of the marine diesel engine is wasted in the form of exhaust gas and cylinder liner cooling water, of which the heat taken away by the high temperature flue gas at 300-400°C and the cylinder liner cooling water at 80-90°C exceeds that of diesel fuel. Combustion releases 50% of the total heat. Among the existing main marine seawater desalination technologies, the high-pressure steam consumed by the flash seawater desalination device causes high energy consumption and large equipment volume. Due to the large footprint and complex system structure of traditional absorption refrigeration devices, it is difficult to meet the requirements of compact ship space. Therefore, how to effectively utilize the waste heat of engine exhaust and cylinder liner cooling water for seawater desalination and air-conditioning refrigeration according to the quality of waste heat, and to develop a device with a compact structure, low cost, and coupling of cooling and heating suitable for ships has become a technical problem that needs to be urgently solved.

The Chinese patent with the publication number CN102320674A discloses a marine seawater desalination method and equipment that utilizes an absorption heat pump to couple the freezing method and the distillation method, which only solves the problem of utilizing the waste heat resources of different temperatures on the ship, but retains the absorption heat pump system. On the basis of the thermal distillation system, the refrigerant direct contact refrigeration system and the waste heat utilization system of the ship's power plant are added, resulting in a complex system and a large footprint.

The Chinese Patent Publication No. CN109942137A discloses a combined supply system for marine waste heat-driven ammonia absorption refrigeration coupled membrane distillation seawater desalination. Although the use of engine exhaust and low-temperature waste heat of engine liner water for refrigeration and seawater desalination is achieved, seawater desalination and refrigeration The two systems are independent of each other, which makes the adjustment of fresh water production and air conditioning refrigeration capacity inflexible. Membrane distillation has high requirements on the quality of imported seawater, and a seawater pretreatment system needs to be used to prevent membrane fouling and blockage.

The Chinese utility model with the announcement number CN201665599U discloses a marine tower-type low-temperature multi-effect seawater desalination device, which adopts a tower-type horizontal tube low-temperature multi-effect evaporation system to save the brine connection pipeline between the evaporator effects, but the shell-and-tube heat exchange Compared with the plate heat exchanger, the size of the evaporator is larger than that of the plate heat exchanger, which is difficult to meet the requirements of the ship for the compact structure of the evaporator. The tower-type horizontal tube multi-effect evaporator does not fundamentally solve the problem that the device is easily affected by the tilting and swaying of the hull.

The problems existing in ship seawater desalination and air conditioning refrigeration units are as follows:

(1) The existing marine absorption refrigeration device includes a steam generator, a condenser, an evaporator and an absorber, the system is complex and the equipment occupies a large space;

(2) The volume of the desalination and evaporation device is large, and the fresh water quality is easily affected by the stability of the hull;

(3) Seawater desalination and absorption refrigeration devices operate independently of each other, resulting in a lack of flexibility in the regulation of fresh water production and air conditioning refrigeration capacity, and the coupling of cooling and heating cogeneration devices cannot be realized to reduce the equipment footprint.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the present invention proposes a cold-heat coupled tower-type seawater desalination system and an application method utilizing the ship's waste heat. The method uses the exhaust heat of the marine diesel engine and the waste heat of the cylinder liner cooling water as the heat source of the cooling and heating cogeneration device, and couples the absorption refrigeration device and the tower type seawater desalination device to realize the cascade utilization of waste heat resources and reduce the floor space of the device. It is actually necessary to flexibly adjust the fresh water production and the cooling capacity of air conditioners.

In order to achieve the above object, the present invention adopts the following technical solutions: a cold-heat coupled tower-type seawater desalination system utilizing ship waste heat, which includes a lithium bromide absorption refrigeration system and a tower-type low-temperature multi-effect evaporation system, and the lithium bromide absorption refrigeration system contains steam The generator, absorber and expansion valve, the diesel exhaust pipe is connected to the flue gas inlet of the flue gas heater inside the steam generator, the liquid outlet at the bottom of the steam generator is connected to the liquid inlet of the absorber shell side through the pipe, and the absorber shell side is connected to the liquid inlet of the absorber shell side. The liquid outlet is connected to the liquid inlet at the top of the steam generator through the liquid delivery pump, the cooling seawater pipeline is connected to the tube side inlet of the absorber, and the tube side outlet of the absorber is connected to the cooling seawater discharge pipeline.

The tower-type low-temperature multi-effect evaporation system includes an upper tower-type 12-effect evaporation device, a lower tower-type 6-effect evaporation device, a heat exchanger, a vacuum pump and a seawater transfer pump, and the upper tower-type 12-effect evaporation device includes an upper first-effect plate evaporation device. evaporator, upper second effect plate evaporator, upper third effect to eleventh effect plate evaporator and upper final effect plate evaporator, lower tower 6-effect evaporator includes lower first effect plate evaporator, lower second effect plate evaporator Plate evaporator, lower third effect to fifth effect plate evaporator and lower final effect plate evaporator.

The steam outlet at the top of the steam generator is connected to the steam inlet at the upper left of the upper first-effect plate evaporator, and the steam condensate outlet at the upper left of the upper first-effect plate evaporator is connected to the regulating valve through the steam condensation pipe, and the regulating valve is connected through the expansion valve. Connect the condensed water inlet at the bottom of the absorber; the seawater transfer pump is connected to the tube side inlet of the heat exchanger, and the tube side outlet of the heat exchanger is connected to the seawater inlet at the upper left of the upper first effect plate evaporator, and the upper first effect plate evaporator The secondary steam outlet at the upper right of the evaporator is connected to the steam inlet at the upper right of the upper second-effect plate evaporator, and the steam condensate outlet at the upper right of the upper second-effect plate evaporator is connected to the shell side inlet of the heat exchanger through the steam condensate pipe. The shell side at the top of the heat exchanger is connected to the vacuum pump, and the shell side outlet of the heat exchanger is connected to the distilled water piping system; the seawater outlet at the lower right of the upper first-effect plate evaporator is connected to the seawater inlet at the upper right of the upper second-effect plate evaporator.

The diesel engine cylinder liner cooling water pipe is connected to the hot water inlet in the upper left part of the lower first effect plate evaporator, the cylinder liner cooling water outlet in the upper left part of the lower first effect plate evaporator is connected to the cylinder liner cooling water inlet pipe, and the lower first effect plate evaporator is connected to the cylinder liner cooling water inlet pipe. The secondary steam outlet at the upper right of the plate evaporator is connected to the steam inlet at the upper right of the lower second effect plate evaporator, and the seawater outlet at the lower right of the lower first effect plate evaporator is connected to the seawater inlet at the upper right of the lower second effect plate evaporator. , the seawater discharge port at the bottom of the bottom end-effect plate evaporator is connected to the ship's air-conditioning refrigeration system.

The secondary steam outlet at the upper left of the upper end-effect plate evaporator is connected to the shell side of the heat exchanger through a secondary steam pipe, and the secondary steam outlet at the upper left of the lower end-effect plate evaporator is connected to the top of the absorber through a secondary steam pipe. The steam inlet; the seawater outlet at the lower left of the upper last-effect plate evaporator is connected to the seawater inlet at the upper left of the lower first-effect plate evaporator through a seawater pipeline.

Each effect plate evaporator in the upper tower type 12-effect evaporation device and the lower tower type 6-effect evaporation device includes a plate heat exchanger, a wire mesh demister and a vertical partition, and each effect plate evaporator is vertically separated. The baffle is divided into two cavities, left and right, which are connected to the lower part. The secondary steam on the plate heat exchanger flows to the lower part of the wire mesh demister along the discharge direction of the secondary steam, and the concentrated seawater on the plate heat exchanger flows along the The discharge direction of concentrated seawater flows to the lower part of the plate evaporator cavity; for plate evaporators with two adjacent effects, the secondary steam outlet of the former plate evaporator is connected to the steam inlet of the plate heat exchanger in the latter effect plate evaporator. , the seawater outlet of the first-effect plate evaporator is connected to the seawater inlet of the plate heat exchanger in the second-effect plate evaporator, and the outlet of the plate heat exchanger in the plate evaporator is connected to the shell side inlet of the heat exchanger through the steam condensing water pipe.

The application method of the cold-heat coupled tower-type seawater desalination system utilizing the ship's waste heat adopts the following steps:

a. Diesel engine exhaust at 300～400℃ is sent to the heater inside the steam generator through the diesel engine exhaust pipe, and the dilute solution of lithium bromide is heated, and the dilute lithium bromide solution is heated and evaporated to generate saturated steam at 60～70℃ as the upper tower 12 The heat source of the high-efficiency evaporation device, the saturated steam is condensed and released in the upper first-effect plate evaporator, and the condensed water after passing through the regulating valve is decompressed and cooled to 7 °C in the expansion valve. The condensed water enters the absorber, and the bottom of the steam generator The 55%-65% lithium bromide concentrated solution flowing out enters the absorber; except the upper first-effect plate evaporator and the upper end-effect plate evaporator, the secondary steam condensed water of other effect plate evaporators all enter the heat exchanger. Shell side, the secondary steam in the upper end-effect plate evaporator is condensed in the shell side of the heat exchanger, and the condensed water in the shell side of the heat exchanger is distilled water with salinity less than 5ppm, which is used as the fresh water source of the ship;

b. The cold water of the diesel engine cylinder liner at 80-90℃ is used as the heat source of the lower tower type 6-effect evaporation device, and the secondary steam generated in the lower first-effect plate type evaporator is used as the heat source of the lower second-effect plate type evaporator. In addition to the effect plate evaporator, the secondary steam condensed water of other effect plate evaporators all enter the shell side of the heat exchanger. In the shell side of the heat exchanger, the condensed water is distilled water with a salinity less than 5ppm, which is used as a fresh water source for ships. ;

c. For the upper tower type 12-effect evaporation device and the lower tower type 6-effect evaporation device, the temperature of the seawater used for desalination is increased from 20 to 25 °C to 40 °C in the heat exchanger, and the preheated seawater enters the upper Beginning with the first-effect plate evaporator, heating, evaporation and concentration are carried out step by step, and at the bottom end-effect plate evaporator of the 18th stage, the concentrated brine of 7°C and 7-8% is used for the refrigeration of the ship's air-conditioning refrigeration system;

d. After the secondary steam in the bottom end-effect plate evaporator enters the inside of the absorber and condenses, it is absorbed by 55% to 65% of the lithium bromide concentrated solution, and the diluted lithium bromide solution is pumped to the steam generator through the liquid transfer pump. For recycling, the cooling seawater at 20-25°C enters the tube side of the absorber through the cooling seawater pipeline, and the absorber shell side releases heat and then discharges through the cooling seawater discharge pipeline.

The seawater is heated, evaporated and concentrated in the heat exchange plate of the evaporator. The concentrated seawater flows to the lower part of the plate evaporator along the discharge direction of the concentrated seawater. The steam discharge flows to the lower part of the wire mesh demister. Under the action of the wire mesh demister, the seawater in the steam-water mixture flows back to the lower part of the plate evaporator cavity, and the secondary steam enters the evaporator of the lower plate evaporator. The heat exchange plate acts as a heat source and condenses, and the concentrated seawater in the upper plate evaporator enters the evaporator heat exchange plate of the lower plate evaporator for repeated heating, evaporation and concentration processes.

The beneficial effects of the present invention are as follows: the cold-heat coupled tower-type seawater desalination system and application method utilizing the ship's waste heat, the system includes an absorption refrigeration system and a tower-type low-temperature multi-effect evaporation system, and the absorption refrigeration system includes a steam generator, an absorber And expansion valve, tower type low temperature multi-effect evaporation system includes tower type multi-effect evaporation device, seawater transfer pump, heat exchanger and vacuum pump. The cascade of the system utilizes the heat of the exhaust of the marine diesel engine and the cooling water of the diesel cylinder liner, and processes the ordinary seawater into 7°C brine for the air conditioning and refrigeration of the ship, which greatly reduces the power consumption of the ship. The tower-type multi-effect evaporation device is used to evaporate and concentrate seawater, which simplifies the pipeline connection of the multi-stage plate evaporator, and at the same time, reduces the volume of the seawater desalination device and saves the space occupied by the ship. The upper plate multi-effect evaporator and the lower plate multi-effect evaporator of the tower multi-effect evaporation device use different waste heat heat sources respectively, which can be flexibly adjusted according to the fresh water output of the seawater desalination device and the demand for salt water for air conditioning and refrigeration. This cold-heat coupled tower seawater desalination system utilizing the ship's waste heat replaces the evaporator and condenser in the absorption refrigeration system through a tower-type multi-effect evaporation device, and couples the seawater desalination device and the air-conditioning refrigeration device to reduce the system size. The footprint of the device saves space on the ship. It solves the problem that the temperature range of low-temperature multiple-effect evaporation cannot be expanded due to the limitation of the cooling water temperature of the condenser. The new tower type multi-effect evaporation device has a compact structure, which further reduces the volume of the system device. The exhaust-driven absorption heat pump steam generator of the marine diesel engine provides the heat source for the upper plate type multi-effect evaporator, and the cylinder liner cooling water of the marine diesel engine provides the heat source for the lower plate type multi-effect evaporator. At the same time, the upper plate type multi-effect evaporator and the lower plate type The multi-effect evaporator realizes the internal circulation utilization of the steam heat source by connecting in series, and divides the tower-type multi-effect evaporation device into two parts, which are both independent and interrelated. flexible control.

Description of drawings

Figure 1 is a flow chart of a cold-heat coupled tower-type seawater desalination device utilizing ship waste heat.

FIG. 2 is a structural diagram of the upper tower type 12-effect evaporation device of FIG. 1 .

FIG. 3 is a structural diagram of the lower tower type 6-effect evaporation device of FIG. 1 .

Figure 4 is a structural diagram of adjacent two-effect plate evaporators.

In the figure: 1, steam generator, 1a, flue gas heater, 2, absorber, 2a, liquid transfer pump, 3, upper tower type 12-effect evaporation device, 3a, upper first-effect plate evaporator, 3b, upper part The second effect plate evaporator, 3c, the upper end effect plate evaporator, 4, the lower tower type 6-effect evaporator, 4a, the lower first effect plate evaporator, 4b, the lower second effect plate evaporator, 4c, the lower end Efficient plate evaporator, 5, heat exchanger, 6, vacuum pump, 7, regulating valve, 8, expansion valve, 9, seawater transfer pump, 10, marine air conditioning and refrigeration system; a1, plate heat exchanger, a2, wire mesh removal Foamer, a3, vertical partition, a4, secondary steam discharge flow, a5, concentrated seawater discharge flow, a6, steam condensate pipe, a7, seawater pipe, a8, secondary steam pipe.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. In the figure, the discharge flow direction a4 of the secondary steam is indicated by a broken line and an arrow, and the discharge flow direction a5 of the concentrated seawater is indicated by a solid line and an arrow.

Figure 1 shows a flow chart of a cold-heat coupled tower-type seawater desalination device utilizing ship waste heat. In the figure, this cooling-heat coupled tower-type seawater desalination system utilizing ship waste heat includes a lithium bromide absorption refrigeration system and a tower-type low-temperature multi-effect evaporation system. The lithium bromide absorption and refrigeration system includes a steam generator 1, an absorber 2 and an expansion valve 8, and a diesel engine The exhaust pipe is connected to the flue gas inlet of the flue gas heater 1a inside the steam generator 1, the liquid outlet at the bottom of the steam generator 1 is connected to the liquid inlet of the shell side of the absorber 2 through the pipe, and the liquid outlet of the shell side of the absorber 2 passes through the liquid The transfer pump 2a is connected to the liquid inlet at the top of the steam generator 1, the cooling seawater pipeline is connected to the tube side inlet of the absorber 2, and the tube side outlet of the absorber 2 is connected to the cooling seawater discharge pipeline.

The tower-type low-temperature multi-effect evaporation system includes an upper tower-type 12-effect evaporation device 3, a lower tower-type 6-effect evaporation device 4, a heat exchanger 5, a vacuum pump 6 and a seawater transfer pump 9, and the upper tower-type 12-effect evaporation device 3 includes The upper first effect plate evaporator 3a, the upper second effect plate evaporator 3b, the upper third to eleventh effect plate evaporators and the upper final effect plate evaporator 3c, the lower tower 6-effect evaporator 4 includes the lower The first effect plate evaporator 4a, the lower second effect plate evaporator 4b, the lower third to fifth effect plate evaporators and the lower final effect plate evaporator 4c.

The steam outlet at the top of the steam generator 1 is connected to the steam inlet at the upper left of the upper first-effect plate evaporator 3a, and the steam condensate outlet at the upper left of the upper first-effect plate evaporator 3a is connected to the regulating valve 7 through the steam condensation pipe, and the regulating valve 7 The condensed water inlet at the bottom of the absorber 2 is connected through the expansion valve 8; the seawater delivery pump 9 is connected to the tube side inlet of the heat exchanger 5, and the tube side outlet of the heat exchanger 5 is connected to the upper left side of the first-effect plate evaporator 3a. The seawater inlet, the secondary steam outlet at the upper right of the upper first effect plate evaporator 3a is connected to the steam inlet at the upper right of the upper second effect plate evaporator 3b, and the steam condensate outlet at the upper right of the upper second effect plate evaporator 3b passes through the steam The condensed water pipe a6 is connected to the inlet of the shell side of the heat exchanger 5, the shell side of the top of the heat exchanger 5 is connected to the vacuum pump 6, and the shell side outlet of the heat exchanger 5 is connected to the distilled water piping system; The outlet is connected to the seawater inlet at the upper right of the upper second-effect plate evaporator 3b.

The diesel engine cylinder liner cooling water pipe is connected to the hot water inlet at the upper left of the lower first effect plate evaporator 4a, the cylinder liner cooling water outlet at the upper left of the lower first effect plate evaporator 4a is connected to the cylinder liner cooling water inlet pipe, and the lower first effect plate evaporator 4a is connected to the cylinder liner cooling water inlet pipe. The secondary steam outlet at the upper right of the plate evaporator 4a is connected to the steam inlet at the upper right of the lower second effect plate evaporator 4b, and the seawater outlet at the lower right of the lower first effect plate evaporator 4a is connected to the upper right of the lower second effect plate evaporator 4b. The seawater inlet at the bottom and the seawater outlet at the bottom of the bottom end-effect plate evaporator 4c are connected to the marine air-conditioning and refrigeration system 10 .

The secondary steam outlet at the upper left of the upper final-effect plate evaporator 3c is connected to the shell side of the heat exchanger 5 through the secondary steam pipe (a8), and the secondary steam outlet at the upper left of the lower final-effect plate evaporator 4c is through the secondary steam pipe a8. Connect the steam inlet at the top of the absorber 2; the seawater outlet at the lower left of the upper final effect plate evaporator 3c is connected to the seawater inlet at the upper left of the lower first effect plate evaporator 4a through a seawater pipeline a7.

Each effect plate evaporator in the upper tower type 12-effect evaporation device 3 and the lower tower type 6-effect evaporation device 4 includes a plate heat exchanger a1, a wire mesh demister a2 and a vertical partition a3. Each effect plate type evaporator It is divided into two left and right cavities connected to the lower part by the vertical partition a3. The secondary steam on the plate heat exchanger a1 flows to the lower part of the wire mesh demister a2 along the secondary steam discharge flow a4. The plate heat exchanger The concentrated seawater on a1 flows to the lower part of the plate evaporator cavity along the discharge flow direction a5 of the concentrated seawater; for plate evaporators with two adjacent effects, the secondary steam outlet of the former effect plate evaporator is connected to the latter effect plate evaporator The steam inlet of the middle plate heat exchanger a1, the seawater outlet of the former one-effect plate evaporator is connected to the seawater inlet of the plate heat exchanger a1 of the latter one effect plate evaporator, and the steam condensate outlet of the plate heat exchanger a1 in the plate evaporator Connect the inlet of the shell side of the heat exchanger 5 through the steam condensate pipe a6 (as shown in Figure 2-4).

An application method of a cold-heat coupled tower-type seawater desalination system utilizing ship waste heat, using the following steps:

a. Diesel exhaust gas at 300～400℃ is sent to the heater 1a inside the steam generator 1 through the diesel engine exhaust pipe to heat the dilute lithium bromide solution, and the dilute lithium bromide solution is heated and evaporated to generate saturated steam at 60～70℃ as the upper tower The heat source of the 12-effect evaporation device 3, the saturated steam is condensed and released in the upper first-effect plate evaporator 3a. After the condensed water passes through the regulating valve 7, the condensed water that is decompressed and cooled to 7°C in the expansion valve 8 enters the absorption 2, the 55% to 65% lithium bromide concentrated solution flowing out from the bottom of the steam generator 1 enters the absorber 2; except the upper first-effect plate evaporator 3a and the upper end-effect plate evaporator 3c, other effect plate evaporators The condensed water of the secondary steam enters the shell side of the heat exchanger 5 to be cooled, the secondary steam in the upper end-effect plate evaporator 3c is condensed in the shell side of the heat exchanger 5, and the condensed water in the shell side of the heat exchanger 5 is condensed. The water is distilled water with salinity less than 5ppm, which is used as fresh water source for ships.

b. The cold water of the diesel engine cylinder liner at 80-90°C is used as the heat source of the lower tower type 6-effect evaporation device 4, and the secondary steam generated in the lower first-effect plate type evaporator 4a is used as the heat source of the lower second-effect plate type evaporator 4b, Except for the bottom end-effect plate evaporator 4c, the secondary steam condensed water of other effect plate evaporators all enter the shell side of the heat exchanger 5, and the condensed water in the shell side of the heat exchanger 5 is distilled water with a salinity less than 5ppm Used as a source of fresh water for ships.

c. For the upper tower type 12-effect evaporation device 3 and the lower tower type 6-effect evaporation device 4, the temperature of the seawater used for desalination is increased from 20 to 25 °C to 40 °C in the heat exchanger 5, and the preheated seawater is Entering the upper first-effect plate evaporator 3a and starting, heating, evaporating and concentrating step by step, to the bottom end-effect plate evaporator 4c of the 18th stage, condensing to 7°C, 7-8% concentrated brine for use in marine air-conditioning refrigeration System 10 cools.

d. After the secondary steam in the lower end-effect plate evaporator 4c enters the absorber 2 through the secondary steam pipeline a8 for condensation, it is absorbed by the 55%-65% lithium bromide concentrated solution, and the diluted lithium bromide solution is transported through the liquid The pump 2a is sent to the steam generator 1 to be recycled, and the cooling seawater at 20-25°C enters the tube side of the absorber 2 through the cooling seawater pipeline.

The seawater is heated, evaporated and concentrated in the evaporator heat exchange plate a1, and the concentrated seawater flows to the lower part of the plate evaporator cavity along the discharge flow direction a5 of the concentrated seawater. The secondary steam discharge flows to the lower part of the wire mesh demister a2 in the direction a4. Under the action of the wire mesh demister a2, the seawater in the steam-water mixture flows back to the lower part of the plate evaporator cavity, and the secondary steam enters the lower plate type evaporator. The evaporator heat exchange plate a1 of the evaporator is used as a heat source and condensed, and the concentrated seawater in the upper plate evaporator enters the evaporator heat exchange plate a1 of the lower plate evaporator for repeated heating, evaporation and concentration process.

The upper tower type 12-effect evaporation device 3 and the lower tower type 6-effect evaporation device 4 replace the condenser and evaporator of the traditional absorption refrigeration system, simplifying the combined cooling and heating system. Compared with the shell-and-tube heat exchanger, the plate-type evaporator has a more compact structure, and the plate-type multi-effect evaporator adopts a tower structure arrangement, which saves the space of the ship. The upper and lower low-temperature multi-effect evaporators use different waste heat sources to realize the coupling of cooling and heating co-generation devices. The structure of the tower-type multi-effect evaporation device can be flexibly adjusted according to the fresh water output of the seawater desalination device and the demand for salt water for ship air conditioning and refrigeration. .

Claims (4)

1. A cold-hot coupling tower type seawater desalination system utilizing ship waste heat comprises a lithium bromide absorption refrigeration system and a tower type low-temperature multi-effect evaporation system, and is characterized in that: the lithium bromide absorption refrigeration system comprises a steam generator (1), an absorber (2) and an expansion valve (8), wherein a diesel engine exhaust pipeline is connected with a flue gas inlet of a flue gas heater (1 a) in the steam generator (1), a liquid outlet at the bottom of the steam generator (1) is connected with a liquid inlet of a shell pass of the absorber (2) through a pipeline, a liquid outlet of the shell pass of the absorber (2) is connected with a liquid inlet at the top of the steam generator (1) through a liquid delivery pump (2 a), a cooling seawater pipeline is connected with a pipe pass inlet of the absorber (2), and a pipe pass outlet of the absorber (2) is connected with a cooling seawater discharge pipeline;

the tower type low-temperature multi-effect evaporation system comprises an upper tower type 12-effect evaporation device (3), a lower tower type 6-effect evaporation device (4), a heat exchanger (5), a vacuum pump (6) and a seawater delivery pump (9), wherein the upper tower type 12-effect evaporation device (3) comprises an upper first-effect plate evaporator (3 a), an upper second-effect plate evaporator (3 b), upper third-effect to eleventh-effect plate evaporators and an upper last-effect plate evaporator (3 c), and the lower tower type 6-effect evaporation device (4) comprises a lower first-effect plate evaporator (4 a), a lower second-effect plate evaporator (4 b), a lower third-effect to fifth-effect plate evaporator and a lower last-effect plate evaporator (4 c);

a steam outlet at the top of the steam generator (1) is connected with a steam inlet at the upper left part of the upper first-effect plate-type evaporator (3 a), a steam condensate outlet at the upper left part of the upper first-effect plate-type evaporator (3 a) is connected with an adjusting valve (7) through a steam condensate pipe, and the adjusting valve (7) is connected with a condensate inlet at the bottom of the absorber (2) through an expansion valve (8); the seawater delivery pump (9) is connected with a tube pass inlet of the heat exchanger (5), a tube pass outlet of the heat exchanger (5) is connected with a seawater inlet at the left upper part of the upper first-effect plate evaporator (3 a), a secondary steam outlet at the right upper part of the upper first-effect plate evaporator (3 a) is connected with a steam inlet at the right upper part of the upper second-effect plate evaporator (3 b), a steam condensate outlet at the right upper part of the upper second-effect plate evaporator (3 b) is connected with an inlet of a shell pass of the heat exchanger (5) through a steam condensate pipe (a 6), the shell pass at the top of the heat exchanger (5) is connected with the vacuum pump (6), and a shell pass outlet of the heat exchanger (5) is connected with the distilled water pipe; a seawater outlet at the right lower part of the upper first-effect plate evaporator (3 a) is connected with a seawater inlet at the right upper part of the upper second-effect plate evaporator (3 b);

the cooling water pipe of the diesel engine cylinder sleeve is connected with a hot water inlet at the left upper part of a first-effect plate evaporator (4 a) at the lower part, a cylinder sleeve cooling water outlet at the left upper part of the first-effect plate evaporator (4 a) at the lower part is connected with a cylinder sleeve cooling water inlet pipe, a secondary steam outlet at the right upper part of the first-effect plate evaporator (4 a) at the lower part is connected with a steam inlet at the right upper part of a second-effect plate evaporator (4 b) at the lower part, a seawater outlet at the right lower part of the first-effect plate evaporator (4 a) at the lower part is connected with a seawater inlet at the right upper part of the second-effect plate evaporator (4 b) at the lower part, and a seawater outlet at the bottom of a last-;

a secondary steam outlet at the left upper part of the upper end-effect plate evaporator (3 c) is connected with the shell pass of the heat exchanger (5) through a secondary steam pipeline (a 8), and a secondary steam outlet at the left upper part of the lower end-effect plate evaporator (4 c) is connected with a steam inlet at the top of the absorber (2) through a secondary steam pipeline (a 8); the seawater outlet at the left lower part of the upper end plate evaporator (3 c) is connected with the seawater inlet at the left upper part of the lower first-effect plate evaporator (4 a) through a seawater pipeline (a 7).

2. The cold-hot coupling tower-type seawater desalination system using ship waste heat according to claim 1, characterized in that: each effective plate evaporator in the upper tower type 12-effect evaporation device (3) and the lower tower type 6-effect evaporation device (4) comprises a plate heat exchanger (a 1), a wire mesh demister (a 2) and a vertical partition plate (a 3), each effective plate evaporator is divided into a left cavity and a right cavity with communicated lower parts by the vertical partition plate (a 3), secondary steam on the plate heat exchanger (a 1) flows to the lower part of the wire mesh demister (a 2) along a secondary steam discharge flow direction (a 4), and concentrated seawater on the plate heat exchanger (a 1) flows to the lower part of the cavity of the plate evaporator along a concentrated seawater discharge flow direction (a 5); for the adjacent two-effect plate type evaporator, a secondary steam outlet of the previous plate type evaporator is connected with a steam inlet of the plate type heat exchanger (a 1) in the next plate type evaporator, a seawater outlet of the previous plate type evaporator is connected with a seawater inlet of the plate type heat exchanger (a 1) in the next plate type evaporator, and a steam condensate outlet of the plate type evaporator plate type heat exchanger (a 1) is connected with an inlet of a shell pass of the heat exchanger (5) through a steam condensate pipe (a 6).

3. The application method of the cold-hot coupling tower-type seawater desalination system using the waste heat of the ship according to claim 1 or 2, which is characterized by comprising the following steps:

a. conveying diesel engine exhaust gas at 300-400 ℃ into a heater (1 a) in a steam generator (1) through a diesel engine exhaust pipeline, heating a lithium bromide dilute solution, heating and evaporating the lithium bromide dilute solution to generate saturated steam at 60-70 ℃ as a heat source of an upper tower type 12-effect evaporation device (3), condensing and releasing heat of the saturated steam in an upper first-effect plate evaporator (3 a) through a regulating valve (7), reducing pressure and cooling to 7 ℃ in an expansion valve (8), and then enabling condensed water to enter an absorber (2), wherein 55-65% of lithium bromide concentrated solution flowing out of the bottom of the steam generator (1) enters the absorber (2); except for the upper first-effect plate evaporator (3 a) and the upper last-effect plate evaporator (3 c), secondary steam condensate water of other plate evaporators enters the shell pass of the heat exchanger (5) to be cooled, secondary steam in the upper last-effect plate evaporator (3 c) is condensed in the shell pass of the heat exchanger (5), and the condensate water in the shell pass of the heat exchanger (5) is distilled water with salinity less than 5ppm and is used as a fresh water source of the ship;

b. cold water of a cylinder sleeve of a diesel engine at 80-90 ℃ serves as a heat source of a lower tower type 6-effect evaporation device (4), secondary steam generated in a lower first-effect plate evaporator (4 a) serves as a heat source of a lower second-effect plate evaporator (4 b), secondary steam condensate water of other plate evaporators enters a shell pass of a heat exchanger (5) except a lower last-effect plate evaporator (4 c), and the condensate water in the shell pass of the heat exchanger (5) is distilled water with salinity smaller than 5ppm and serves as a fresh water source of a ship;

c. for the upper tower type 12-effect evaporation device (3) and the lower tower type 6-effect evaporation device (4), the temperature of seawater for desalination is increased from 20-25 ℃ to 40 ℃ in a heat exchanger (5), the preheated seawater enters an upper first-effect plate evaporator (3 a) and is heated, evaporated and concentrated step by step to an 18-stage lower last-effect plate evaporator (4 c), and concentrated brine with the temperature of 7 ℃ and 7-8% is used for refrigerating a ship air-conditioning refrigeration system (10);

d. the secondary steam in the lower end-effect plate evaporator (4 c) enters the interior of the absorber (2) through a secondary steam pipeline (a 8) to be condensed and then is absorbed by 55% -65% of lithium bromide concentrated solution, the diluted lithium bromide dilute solution is sent to the steam generator (1) through the liquid delivery pump (2 a) to be recycled, the cooling seawater at the temperature of 20-25 ℃ enters the tube pass of the absorber (2) through a cooling seawater pipeline, and the cooling seawater is discharged through a cooling seawater discharge pipeline after the heat is released by the shell pass of the absorber (2).

4. The application method of the cold-hot coupling tower-type seawater desalination system using the waste heat of the ship according to claim 3, characterized in that: the seawater is heated, evaporated and concentrated in the evaporator heat exchange plate (a 1), the concentrated seawater flows to the lower part of the plate evaporator cavity along the concentrated seawater discharge flow direction (a 5) through the concentrated seawater, a steam-water mixture of secondary steam containing partial seawater droplets flows to the lower part of the wire mesh demister (a 2) along the secondary steam discharge flow direction (a 4), under the action of the wire mesh demister (a 2), the seawater in the steam-water mixture flows back to the lower part of the plate evaporator cavity, the secondary steam enters the evaporator heat exchange plate (a 1) of the lower plate evaporator to be used as a heat source and is condensed, and the concentrated seawater in the upper plate evaporator enters the evaporator heat exchange plate (a 1) of the lower plate evaporator to be repeatedly heated, evaporated and concentrated.

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