CN106745428A - A kind of heat collection type solar multistage flash evaporation seawater desalting device and method - Google Patents

Abstract

The invention provides a heat-collecting solar multi-stage flash seawater desalination device, comprising a solar heat collector, an auxiliary electric heater, a flash device, a heat exchanger, a cavity, a fresh water collector, a seawater inlet pump, a vacuum pump, a seawater Circulation pump, concentrated seawater effluent pump and PLC controller, and the flash device includes a first-stage flash barrel, a second-stage flash barrel, and a third-stage flash barrel, which are connected in series through pipelines from bottom to top, and the pressure is gradually reduced. The seawater desalination device provided by the present invention makes full use of solar energy to heat seawater, has low cost, good seawater desalination effect, does not need to add chemicals, and the obtained freshwater is clear. This part of the seawater is used for salt production and other operations to realize the utilization of waste products. At the same time, the output of this device avoids the use of pumps and other power devices to directly pump out seawater. Instead, it chooses to use a cavity as a liquid delivery device, which consumes a lot of energy. few.

Description

A heat-collecting solar multi-stage flash seawater desalination device and method

technical field

The invention belongs to the technical field of seawater desalination, and mainly relates to a heat-collecting solar multi-stage flash seawater desalination device and method.

Background technique

With the growth of the world's population, rapid economic development and climate change, the crisis of global fresh water resources continues to aggravate. About 36% of the world's population lacks clean and safe drinking water. At the same time, the shortage of water resources also hinders the development of industries. . my country is also one of the countries with water shortages. Due to environmental pollution in recent years, fresh water resources have decreased sharply, which has had a great impact on the stable development of society. The lack of fresh water resources is a problem faced by all countries in the world, and the use of seawater desalination to solve the shortage of water resources has become a problem that many countries are paying attention to.

Seawater desalination methods include electrodialysis, membrane, distillation and freezing methods.

Electrodialysis refers to the desalination process in which the potential difference is used as the driving force and the selective permeability of the ion exchange membrane is used to remove ions in water.

The membrane method can be divided into reverse osmosis membrane method and membrane distillation method in principle.

Reverse osmosis refers to the desalination process in which seawater is pressurized and forced to pass through a semi-permeable membrane. The membrane allows only pure water to pass through and rejects salt ions. In reverse osmosis, seawater at ambient temperature is required to be raised in pressure and then exposed to a semi-permeable polymeric membrane. The reverse osmosis method is characterized by no phase change in the process, low energy consumption, and the separation of organic impurities and uncharged impurities can also be achieved.

Membrane distillation is the evaporation process of steam through a hydrophobic microporous membrane. Most of them use temperature difference as the driving force, and some use concentration difference as the driving force. There is no mist entrainment problem in the membrane distillation process, the structure of the components is very compact, suitable for large-scale, does not require high operating temperature, does not need to be heated to the boiling point, and can make good use of low-temperature and low-grade heat sources.

Distillation refers to the process of heating seawater to turn it into water vapor, and then condensing the water vapor to obtain fresh water. According to the energy used, process and equipment, it can be divided into flash evaporation, pressure steam distillation, and standpipe multi-effect evaporation. and solar distillation.

The freezing method uses the principle of cooling to precipitate ice crystals from salt water and obtain fresh water after melting. This method does not require high temperature, will not cause corrosion, is safe and efficient in operation, and the obtained fresh water is pollution-free and of good water quality.

Compared with traditional heat and power sources, solar energy is a sustainable seawater desalination technology due to its advantages of no pollution and abundant storage. more attention.

The main problems encountered by current seawater desalination equipment are large energy consumption, high investment cost, and low water production rate. Therefore, there is an increasing demand for high-efficiency heat-collecting seawater desalination devices with simple structure, low cost, and full use of renewable energy. bigger.

Contents of the invention

The object of the present invention aims at the problems encountered by the current seawater desalination equipment, and provides a heat-collecting solar multi-stage flash seawater desalination device and method with simple structure, good seawater desalination effect and reasonable design.

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

A heat-collecting solar multi-stage flash seawater desalination device, including a solar collector, an auxiliary electric heater, a flash device, a heat exchanger, a cavity, a freshwater collector, a seawater inlet pump, a vacuum pump, a seawater circulation pump, Concentrated seawater outlet pump and PLC controller, the flash device includes a first-stage flash barrel, a second-stage flash barrel, and a third-stage flash barrel that are connected in series through pipelines from bottom to top, and the pressure is gradually reduced. The first-stage flash barrel, the second-stage flash barrel, and the third-stage flash barrel have the same structure, and are provided with an exhaust port, a condensation pipe, a fresh water tank, a sprinkler, and a seawater outlet in sequence from top to bottom. The outlets of the exhaust ports of the first-stage flash barrel, the second-stage flash barrel, and the third-stage flash barrel are respectively provided with a third electric valve, a fourth electric valve, and a fifth electric valve and pass through the pipeline The vacuum pump is connected, and the outlets of the exhaust ports of the first-stage flash barrel, the second-stage flash barrel, and the third-stage flash barrel are respectively provided with a first pressure sensor and a second pressure sensor. and the third pressure sensor, the condensation pipes of the first-stage flash barrel, the second-stage flash barrel and the third-stage flash barrel are connected in series, and the condensation pipes of the three-stage flash barrel The inlet is communicated with the new seawater outlet of the heat exchanger, and the outlet of the condensation pipe of the first-stage flash barrel is communicated with the inlet of the solar collector through a pipeline provided with a first electric valve. The inlet of the sprinkler of the first-stage flash tank is communicated with the outlet of the solar collector through the pipeline provided with the seawater circulation pump, and the seawater outlet of the first-level flash tank is connected with the outlet of the solar collector through the pipeline. The sprayer of the secondary flash tank is connected, and the seawater outlet of the secondary flash tank is connected with the sprinkler of the three-stage flash tank through a pipeline, and the three-stage flash tank The seawater outlet of the barrel communicates with the concentrated seawater inlet of the heat exchanger through the pipeline provided with the concentrated seawater outlet pump, the first-stage flash barrel, the second-stage flash barrel and the third-stage The outlet of the fresh water tank of the flash tank is respectively provided with a sixth electric valve, a seventh electric valve and an eighth electric valve and communicates with the inlet of the cavity through a pipeline, and there is also a gap between the two ends of the solar collector. The pipeline with the auxiliary electric heater and the second electric valve is connected in parallel, the outlet of the solar collector is also provided with a temperature sensor, and the heat exchanger is also provided with a new seawater inlet and a concentrated seawater outlet, so The new seawater inlet of the heat exchanger communicates with the outlet of the seawater inlet pump, and the position of the cavity is lower than the first-stage flash barrel, the second-stage flash barrel and the third-stage flash barrel, The outlet of the cavity is also communicated with the inlet of the fresh water collector which is located lower than the cavity through the pipeline provided with the ninth electric valve, and the first water level sensors are arranged in the cavity in sequence from low to high , the second water level sensor, the third water level sensor and the fourth water level sensor, the first water level sensor, the second water level sensor, the third water level sensor, the fourth water level sensor, the first pressure sensor , the second pressure sensor, the third pressure sensor and the temperature sensor are all connected to the PLC controller through signal cables, the first electric valve, the second electric valve, the third electric valve, the Fourth electric valve , the fifth electric valve, the sixth electric valve, the seventh electric valve, the eighth electric valve and the ninth electric valve are connected to the PLC controller through control cables and are controlled by the PLC controller control.

Further, a heat insulation layer is provided between the inner wall and the outer wall of the first-stage flash tank, the second-stage flash tank and the third-stage flash tank, so as to increase the heat preservation effect.

Further, the first electric valve, the second electric valve, the third electric valve, the fourth electric valve, the fifth electric valve, the sixth electric valve, the seventh electric valve , The eighth electric valve and the ninth electric valve are straight-stroke electric valves, which are stronger and more durable.

Further, the heat exchanger is preferably a shell-and-tube heat exchanger, which is easy to install.

Further, the solar heat collector includes an all-glass vacuum heat collecting tube and a heat collector header, and there may be multiple all-glass vacuum heat collecting tubes, whose open ends are inserted into the heat collector header.

Further, the outlet of the fresh water collector is also connected with a water outlet nozzle to facilitate water intake.

The present invention also provides a method for the above-mentioned heat-collecting solar multi-stage flash seawater desalination device, comprising the following steps:

Step 1: Start the vacuum pump, open the third electric valve, and the pressure in the first-stage flash barrel gradually decreases under the action of the vacuum pump. When the pressure in the first-stage flash barrel reaches the The value set by the first pressure sensor, the first pressure sensor transmits the monitored signal to the PLC controller, and the PLC controller makes a judgment according to the received signal to control the closing of the third electric valve, And open the fourth electric valve, similarly under the action of the vacuum pump, the pressure in the secondary flash barrel gradually decreases, when the pressure in the secondary flash barrel reaches the second pressure sensor setting The second pressure sensor transmits the monitored signal to the PLC controller, and the PLC controller makes a judgment according to the received signal, and controls the fourth electric valve to close and open the first electric valve. Five electric valves, similarly, under the action of the vacuum pump, the pressure in the three-stage flash barrel gradually decreases. When the pressure in the three-stage flash barrel reaches the value set by the third pressure sensor, the The third pressure sensor transmits the monitored signal to the PLC controller, and the PLC controller makes a judgment according to the received signal, and controls the closing of the fifth electric valve and the vacuum pump;

Step 2: Connect the inlet of the seawater inlet pump to seawater, start the seawater inlet pump, the seawater circulation pump and the concentrated seawater outlet pump and open the first electric valve, at this time the seawater passes through the seawater The water inlet pump is pressurized into the heat exchanger for heat exchange and then enters the condensation pipes of the first-stage flash tank, the second-stage flash tank and the third-stage flash tank, and then flows into the The solar heat collector, after being heated in the solar heat collector, is pressurized twice through the seawater circulation pump, and then enters the first-stage flash barrel through the sprinkler of the first-stage flash barrel, because The pressure in the first-stage flash tank is lower than the saturated vapor pressure corresponding to the entering seawater, so after the seawater enters the first-stage flash tank, it will be partially evaporated immediately, and the temperature of the unevaporated seawater will decrease at the same time. Enter the secondary flash barrel through the sprayer of the secondary flash barrel, the pressure in the secondary flash barrel is lower than the saturated vapor pressure corresponding to the seawater, so there will still be some evaporation, and at the same time The temperature of the unevaporated seawater continues to decrease, and then enters the third-stage flash barrel through the sprayer of the three-stage flash barrel, and continues to flash, and the temperature of part of the seawater that has not been flashed continues to decrease, and passes through the three-stage flash barrel. The seawater outlet of the three-stage flash tank flows into the concentrated seawater inlet of the heat exchanger under the action of the concentrated seawater outlet pump, and after heat exchange with new seawater, the The concentrated seawater flows out of the outlet, and the steam in the first-stage flash barrel, the second-stage flash barrel, and the third-stage flash barrel encounters the condensation pipe, condenses to obtain fresh water, and is collected by the fresh water tank;

Step 3: The PLC controller controls the opening of the eighth electric valve, at this time, the cavity communicates with the third-stage flash barrel, and the gas in the cavity enters the third-stage flash barrel through a pipeline , when the pressures of the two containers are balanced, the fresh water in the three-stage flash tank flows into the cavity through the pipeline under the action of gravity;

Step 4: When the water level flowing into the cavity reaches the second water level sensor, the second water level sensor transmits the monitored signal to the PLC controller, and the PLC controller makes a decision based on the received signal Judgment, control the eighth electric valve to close, control the seventh electric valve to open, because the pressure in the three-stage flash tank and the cavity has been balanced, the pressure in the cavity has changed from normal pressure to Negative pressure, while the internal pressure is lower than the pressure of the secondary flash barrel and the primary flash barrel, so when the seventh electric valve is opened, the fresh water in the secondary flash barrel is directly into the cavity;

Step 5: When the water level flowing into the cavity reaches the third water level sensor, the third water level sensor transmits the monitored signal to the PLC controller, and the PLC controller makes a decision based on the received signal Judgment, control the seventh electric valve to close, control the sixth electric valve to open, since the pressure in the cavity is lower than the pressure in the first-stage flash tank, when the sixth electric valve is opened , the fresh water in the primary flash tank directly flows into the cavity;

Step 6: When the water level flowing into the cavity reaches the fourth water level sensor, the fourth water level sensor transmits the monitored signal to the PLC controller, and the PLC controller makes a decision based on the received signal Judging, controlling the sixth electric valve to close, controlling the ninth electric valve to open, the pressure in the cavity returns to normal pressure, and at the same time, fresh water flows into the fresh water collector under the action of gravity;

Step 7: When the fresh water in the cavity flows out completely, the first water level sensor in the cavity transmits the monitored signal to the PLC controller, and the PLC controller makes a judgment according to the received signal and controls the The ninth electric valve is closed.

Further, when the temperature sensor detects that the temperature at the outlet of the solar collector is lower than a set value, the PLC controller controls the second electric valve to open and turn on the auxiliary electric heater.

Compared with the prior art, the beneficial effects of the present invention are: the seawater desalination device provided by the present invention fully utilizes the renewable energy solar energy to heat seawater, the equipment is simple, the connection is compact, the cost is low, the seawater desalination effect is good, and no chemicals need to be added , the resulting fresh water quality is clear, and at the same time, after the heat exchange between the concentrated seawater discharged from the final stage and the new seawater, this part of the seawater can also be used for salt production and other operations to realize the utilization of waste products, which can not only solve the shortage of water resources, but also uphold sustainable development concept. At the same time, the fresh water output of this device avoids the use of pumps and other power devices to directly pump out seawater, but chooses a cavity as a liquid delivery device, and balances the pressure difference between the cavity and the three-stage flash tank with the lowest pressure. Due to the small volume of the cavity, the three-stage flash tank can achieve pressure balance with it in a very short time, and the energy consumption is relatively small. At the same time, after the first-stage flash barrel and the second-stage flash barrel are connected to the cavity, fresh water will flow directly into the cavity through the pipeline. The time of the fresh water collector realizes the direct outflow of fresh water in the multi-stage flash barrel by consuming the pressure difference of one level. This step-by-step utilization of the pressure difference effectively realizes energy saving.

Description of drawings

Fig. 1 is the schematic diagram of device structure of the embodiment of the present invention;

In the figure: 1 is the solar collector, 2 is the auxiliary electric heater, 3 is the primary flash barrel, 4 is the secondary flash barrel, 5 is the tertiary flash barrel, 6 is the heat exchanger, and 7 is the cavity body, 8 is a fresh water collector, 9 is a seawater inlet pump, 10 is a vacuum pump, 11 is a seawater circulation pump, 12 is a concentrated seawater outlet pump, 13 is a temperature sensor, 14 is a first pressure sensor, 15 is a second pressure sensor, 16 17 is the first water level sensor, 18 is the second water level sensor, 19 is the third water level sensor, 20 is the fourth water level sensor, 21 is the first electric valve, 22 is the second electric valve, 23 is the third electric valve, 24 is the fourth electric valve, 25 is the fifth electric valve, 26 is the sixth electric valve, 27 is the seventh electric valve, 28 is the eighth electric valve, 29 is the ninth electric valve, 30 31 is a PLC controller, 32 is a fresh water tank, 33 is a water outlet nozzle, and 34 is an exhaust port.

detailed description

In order to make the above objects, features and advantages of the present invention more comprehensible, specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1: it is a heat-collecting solar multi-stage flash seawater desalination device of the present invention, comprising a solar heat collector 1, an auxiliary electric heater 2, a flash device, a heat exchanger 6, a cavity 7, Fresh water collector 8, seawater inlet pump 9, vacuum pump 10, seawater circulation pump 11, concentrated seawater outlet pump 12 and PLC controller 31, the flash evaporation device includes a series connection of pipelines from bottom to top in order to reduce the pressure step by step The primary flash barrel 3, the secondary flash barrel 4 and the tertiary flash barrel 5, the structure of the primary flash barrel 3, the secondary flash barrel 4 and the tertiary flash barrel 5 Same, the exhaust port 34, the condensation pipe 30, the fresh water tank 32, the sprinkler and the seawater outlet are arranged in sequence from top to bottom, the first-stage flash barrel 3, the second-stage flash barrel 4 and the third-stage The outlet of the exhaust port 34 of the flash barrel 5 is respectively provided with a third electric valve 23, a fourth electric valve 24 and a fifth electric valve 25 and is connected with the vacuum pump 10 through a pipeline, and the first-stage flash barrel 3. A first pressure sensor 14, a second pressure sensor 15 and a third pressure sensor 16 are respectively provided at the outlets of the exhaust ports 34 of the secondary flash tank 4 and the tertiary flash tank 5, The condensation pipe 30 of the first-stage flash barrel 3, the secondary flash barrel 4 and the third-stage flash barrel 5 is connected in series, and the condensation pipe 30 of the three-stage flash barrel 5 is connected in series. The inlet is communicated with the new seawater outlet of the heat exchanger 6, and the outlet of the condensation pipe 30 of the primary flash barrel 3 is connected to the solar collector 1 through a pipeline provided with a first electric valve 21. The inlet is connected, and the inlet of the sprayer of the first-stage flash tank 3 is communicated with the outlet of the solar collector 1 through a pipeline provided with the seawater circulation pump 11, and the first-stage flash tank 3 The seawater outlet of the secondary flash tank 4 communicates with the sprayer of the secondary flash tank 4 through a pipeline, and the seawater outlet of the secondary flash tank 4 communicates with the third-level flash tank 5 through a pipeline. The sprayer is connected, and the seawater outlet of the three-stage flash tank 5 is connected with the concentrated seawater inlet of the heat exchanger 6 through a pipeline provided with the concentrated seawater outlet pump 12. The outlets of the fresh water tank 32 of the steaming barrel 3, the secondary flash barrel 4 and the tertiary flash barrel 5 are respectively provided with a sixth electric valve 26, a seventh electric valve 27 and an eighth electric valve 28 and pass through The pipeline communicates with the inlet of the cavity 7, and the pipelines with the auxiliary electric heater 2 and the second electric valve 22 are connected in parallel between the two ends of the solar heat collector 1, and the solar heat collector The outlet of the device 1 is also provided with a temperature sensor 13, and the heat exchanger 6 is also provided with a new seawater inlet and a concentrated seawater outlet, and the new seawater inlet of the heat exchanger 6 communicates with the outlet of the seawater inlet pump 9, so The position of the chamber 7 is lower than the first-stage flash barrel 3, the second-stage flash barrel 4 and the third-stage flash barrel 5, and the outlet of the chamber 7 is also provided with a ninth electric valve The pipeline at 29 communicates with the inlet of the fresh water collector 8 which is lower than the cavity 7. The first water level sensor 17, the second water level sensor 18, and the first water level sensor 17 are arranged in the cavity 7 from low to high. Three water level sensors 19 and the fourth water level sensor sensor 20, the first water level sensor 17, the second water level sensor 18, the third water level sensor 19, the fourth water level sensor 20, the first pressure sensor 14, the second pressure sensor 15, the third The pressure sensor 16 and the temperature sensor 13 are all connected to the PLC controller 31 through signal cables, the first electric valve 21, the second electric valve 22, the third electric valve 23, the fourth electric valve The electric valve 24, the fifth electric valve 25, the sixth electric valve 26, the seventh electric valve 27, the eighth electric valve 28 and the ninth electric valve 29 are connected to the electric valve 29 through control cables. The PLC controller 31 is connected to and controlled by the PLC controller 31 .

A thermal insulation layer is provided between the inner wall and the outer wall of the first-stage flash barrel 3 , the second-stage flash barrel 4 and the third-stage flash barrel 5 .

The first electric valve 21, the second electric valve 22, the third electric valve 23, the fourth electric valve 24, the fifth electric valve 25, the sixth electric valve 26, the The seventh electric valve 27 , the eighth electric valve 28 and the ninth electric valve 29 are all straight stroke electric valves.

The heat exchanger 6 is a shell-and-tube heat exchanger.

The solar heat collector 1 includes an all-glass vacuum heat collecting tube and a heat collector header.

The outlet of the fresh water collector 8 is also connected with a water outlet nozzle 33 .

A kind of method of heat collection type solar energy multi-stage flash seawater desalination device of the present invention comprises the following steps:

Step 1: Start the vacuum pump, open the third electric valve, and the pressure in the first-stage flash barrel gradually decreases under the action of the vacuum pump. When the pressure in the first-stage flash barrel reaches the The value set by the first pressure sensor, the first pressure sensor transmits the monitored signal to the PLC controller, and the PLC controller makes a judgment according to the received signal to control the closing of the third electric valve, And open the fourth electric valve, similarly under the action of the vacuum pump, the pressure in the secondary flash barrel gradually decreases, when the pressure in the secondary flash barrel reaches the second pressure sensor setting The second pressure sensor transmits the monitored signal to the PLC controller, and the PLC controller makes a judgment according to the received signal, and controls the fourth electric valve to close and open the first electric valve. Five electric valves, similarly, under the action of the vacuum pump, the pressure in the three-stage flash barrel gradually decreases. When the pressure in the three-stage flash barrel reaches the value set by the third pressure sensor, the The third pressure sensor transmits the monitored signal to the PLC controller, and the PLC controller makes a judgment according to the received signal, and controls the closing of the fifth electric valve and the vacuum pump;

Step 2: Connect the inlet of the seawater inlet pump 9 to seawater, start the seawater inlet pump 9, the seawater circulation pump 11 and the concentrated seawater outlet pump 12, and open the first electric valve 21, at this time The seawater is pressurized by the seawater inlet pump 9 and enters the heat exchanger 6 for heat exchange, and then enters all of the primary flash barrel 3, the secondary flash barrel 4, and the tertiary flash barrel 5. The condensing pipe 30, then flows into the solar heat collector 1 through the pipeline, after being heated in the solar heat collector 1, it is pressurized twice through the seawater circulation pump 11, and then passes through the first-stage flash tank 3 The said sprayer of said sprayer enters said one-stage flash tank 3, because the pressure in said one-stage flash tank 3 is lower than the saturated vapor pressure corresponding to the seawater entering, so the seawater enters said one-stage flash tank After 3, partial evaporation will take place immediately, and the seawater temperature that does not evaporate simultaneously reduces, and continues to enter described secondary flash barrel 4 through the described sprinkler of described secondary flash barrel 4, and described secondary flash barrel 4 The pressure inside is lower than the saturated vapor pressure corresponding to the entering seawater, so there will still be some evaporation, while the temperature of the unevaporated seawater continues to decrease, and then enters the tertiary flash barrel 5 through the sprayer of the tertiary flash barrel 5 The steaming barrel 5 continues to flash, and the temperature of part of the seawater that has not flashed continues to decrease, and flows into the exchange through the seawater outlet of the third-stage flash barrel 5 under the action of the concentrated seawater outlet pump 12. The concentrated seawater inlet of the heat exchanger 6 flows out from the concentrated seawater outlet of the heat exchanger 6 after exchanging heat with new seawater. The primary flash barrel 3, the secondary flash barrel 4 and After the steam in the three-stage flash tank 5 encounters the condensation pipe 30, it is condensed to obtain fresh water, which is collected by the fresh water tank 32;

Step 3: the PLC controller 29 controls the eighth electric valve 28 to open, at this time, the cavity 7 communicates with the three-stage flash barrel 5, and the gas in the cavity 7 enters the In the three-stage flash tank 5, when the pressures of the two containers are balanced, the fresh water in the three-stage flash tank 5 flows into the cavity 7 through the pipeline under the action of gravity;

Step 4: When the water level flowing into the cavity 7 reaches the second water level sensor 18, the second water level sensor 18 transmits the monitored signal to the PLC controller 31, and the PLC controller 31 Make a judgment based on the received signal, control the eighth electric valve 28 to close, and control the seventh electric valve 27 to open. Since the three-stage flash tank 5 and the cavity 7 have been pressure balanced, the The pressure in the cavity 7 has changed from normal pressure to negative pressure, and the pressure inside it is lower than the pressure of the secondary flash tank 4 and the primary flash tank 3, so when the seventh electric valve After 27 is opened, the fresh water in the secondary flash tank 4 directly flows into the cavity 7;

Step 5: When the water level flowing into the cavity 7 reaches the third water level sensor 19, the third water level sensor 19 transmits the monitored signal to the PLC controller 31, and the PLC controller 31 Make a judgment according to the received signal, control the seventh electric valve 27 to close, and control the sixth electric valve 26 to open, because the pressure in the cavity 7 is lower than that in the first-stage flash tank 3 pressure, so when the sixth electric valve 26 is opened, the fresh water in the primary flash tank 3 directly flows into the cavity 7;

Step 6: When the water level flowing into the cavity 7 reaches the fourth water level sensor 20, the fourth water level sensor 20 transmits the monitored signal to the PLC controller 31, and the PLC controller 31 Make a judgment according to the received signal, control the sixth electric valve 26 to close, control the ninth electric valve 29 to open, the pressure in the cavity 7 returns to normal pressure, and at the same time, fresh water flows into the Said fresh water collector 8;

Step 7: When the fresh water in the cavity 7 flows out completely, the first water level sensor 15 in the cavity 7 transmits the monitored signal to the PLC controller 31, and the PLC controller 31 according to the received signal to make a judgment and control the ninth electric valve 29 to close.

Further, when the temperature sensor 13 detects that the temperature at the outlet of the solar collector 1 is lower than the set value, the PLC controller 31 controls the second electric valve 22 to open and turn on the auxiliary electric heater 2.

In such a cycle, according to the ratio of the cavity 7 to the fresh water tank 32 in the first-stage flash barrel 3, the second-stage flash barrel 4 and the third-stage flash barrel 5, calculate how much it needs to circulate Once, all the fresh water produced by flash evaporation every day can be sent to the fresh water collector 8.

Although the present invention is disclosed above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention should be based on the scope defined in the claims.

Claims (8)

1. a kind of heat collection type solar multistage flash evaporation seawater desalting device, it is characterised in that：Including solar thermal collector (1), auxiliary Help electric heater (2), flash distillation plant, heat exchanger (6), cavity (7), fresh water collecting apparatus by means (8), seawater intake pump (9), vavuum pump (10), sea water circulating pump (11), concentrated seawater go out water pump (12) and PLC (31), and the flash distillation plant includes passing through pipeline Primary flash bucket (3), two-stage flash bucket (4) and three stages of flashing bucket that the pressure being sequentially connected in series from bottom to top reduces step by step (5), primary flash bucket (3), two-stage flash bucket (4) are identical with the structure of three stages of flashing bucket (5), from top to bottom It is disposed with exhaust outlet (34), condenser pipe (30), fresh-water tank (32), sprinkler and seawer outlet, the primary flash bucket (3), the outlet of the exhaust outlet (34) of two-stage flash bucket (4) and three stages of flashing bucket (5) is respectively equipped with the 3rd electricity Dynamic valve (23), the 4th motor-driven valve (24) and the 5th motor-driven valve (25) are simultaneously connected with the vavuum pump (10), described one by pipeline The outlet of the exhaust outlet (34) of level flash distillation bucket (3), two-stage flash bucket (4) and three stages of flashing bucket (5) is also distinguished It is provided with first pressure sensor (14), second pressure sensor (15) and the 3rd pressure sensor (16), the primary flash bucket (3), the condenser pipe (30) of two-stage flash bucket (4) and three stages of flashing bucket (5) is connected in series, the three stages of flashing The entrance of the condenser pipe (30) of bucket (5) is connected with the new seawer outlet of the heat exchanger (6), primary flash bucket (3) The condenser pipe (30) outlet by being provided with the pipeline of the first motor-driven valve (21) and the entrance of the solar thermal collector (1) Connection, the entrance of the sprinkler of primary flash bucket (3) is by being provided with pipeline and the institute of the sea water circulating pump (11) The outlet of solar thermal collector (1) is stated, the seawer outlet of primary flash bucket (3) passes through pipeline with described two grades The sprinkler connection of flash distillation bucket (4), the seawer outlet of two-stage flash bucket (4) is dodged by pipeline with the three-level The sprinkler connection of steaming kier (5), the seawer outlet of three stages of flashing bucket (5) is by being provided with the concentrated seawater water outlet The concentrated seawater inlet communication of the pipeline of pump (12) and the heat exchanger (6), primary flash bucket (3), two-stage flash bucket (4) and the three stages of flashing bucket (5) the fresh-water tank (32) outlet be respectively equipped with the 6th motor-driven valve (26), the 7th motor-driven valve (27) and the 8th motor-driven valve (28) and the inlet communication that passes through pipeline and the cavity (7), the two of the solar thermal collector (1) The pipeline for being provided with the electrical auxiliary heater (2) and the second motor-driven valve (22) also in parallel, the solar thermal collector between end (1) outlet is additionally provided with temperature sensor (13), and the heat exchanger (6) is additionally provided with new sea intake and concentrated seawater outlet, described The outlet of the new sea intake of heat exchanger (6) and the seawater intake pump (9), the position of the cavity (7) is less than described Primary flash bucket (3), two-stage flash bucket (4) and three stages of flashing bucket (5), the outlet of the cavity (7) is also by setting There is inlet communication of the pipeline of the 9th motor-driven valve (29) with position less than the fresh water collecting apparatus by means (8) of the cavity (7), it is described The first level sensor (17), the second level sensor (18), the 3rd level sensor are disposed with from low to high in cavity (7) Device (19) and the 4th level sensor (20), it is first level sensor (17), second level sensor (18), described 3rd level sensor (19), the 4th level sensor (20), the first pressure sensor (14), the second pressure Sensor (15), the 3rd pressure sensor (16) and the temperature sensor (13) pass through signal cable and the PLC Controller (31) is connected, first motor-driven valve (21), second motor-driven valve (22), the 3rd motor-driven valve (23), described It is 4th motor-driven valve (24), the 5th motor-driven valve (25), the 6th motor-driven valve (26), the 7th motor-driven valve (27), described 8th motor-driven valve (28) and the 9th motor-driven valve (29) are connected and by institute by controlling cable with the PLC (31) State PLC (31) control.

2. a kind of heat collection type solar multistage flash evaporation seawater desalting device according to claim 1, it is characterised in that：Described one Thermal insulation layer is provided between the inner and outer wall of level flash distillation bucket (3), two-stage flash bucket (4) and three stages of flashing bucket (5).

3. a kind of heat collection type solar multistage flash evaporation seawater desalting device according to claim 1, it is characterised in that：Described One motor-driven valve (21), second motor-driven valve (22), the 3rd motor-driven valve (23), the 4th motor-driven valve (24), described Five motor-driven valves (25), the 6th motor-driven valve (26), the 7th motor-driven valve (27), the 8th motor-driven valve (28) and described Nine motor-driven valves (29) are straight stroke electric valve.

4. a kind of heat collection type solar multistage flash evaporation seawater desalting device according to claim 1, it is characterised in that：It is described to change Hot device (6) is preferably shell-and-tube heat exchanger.

5. a kind of heat collection type solar multistage flash evaporation seawater desalting device according to claim 1, it is characterised in that：It is described too Positive energy heat collector (1) includes all-glass vacuum thermal-collecting tube and heat collector header.

6. a kind of heat collection type solar multistage flash evaporation seawater desalting device according to claim 1, it is characterised in that：It is described light The outlet of water collector (8) is also associated with Water outlet spray head (33).

7. a kind of method of the heat collection type solar multistage flash evaporation seawater desalting device according to claim 1 to 6 any one, It is characterised in that it includes following steps：

Step one：Start the vavuum pump (10), the 3rd motor-driven valve (23) is opened, in the presence of the vavuum pump (10) Pressure in primary flash bucket (3) is gradually reduced, when the pressure in primary flash bucket (3) reaches the first pressure The value of sensor (14) setting, the signal that the first pressure sensor (14) will monitor is transmitted to the PLC (31), The PLC (31) judges according to the signal for receiving, and controls the 3rd motor-driven valve (23) to close, and open institute The 4th motor-driven valve (24) is stated, similarly the pressure in two-stage flash bucket (4) in the presence of the vavuum pump (10) gradually drops It is low, when the pressure in two-stage flash bucket (4) reaches the value of second pressure sensor (15) setting, the second pressure The signal that sensor (15) will be monitored is transmitted to the PLC (31), and the PLC (31) is according to the letter for receiving Number judge, control the 4th motor-driven valve (24) to close and open the 5th described motor-driven valve (25), similarly described true Pressure in the presence of empty pump (10) in three stages of flashing bucket (5) is gradually reduced, the pressure in three stages of flashing bucket (5) The value of the 3rd pressure sensor (16) setting is reached, the signal that the 3rd pressure sensor (16) will monitor is transmitted to institute PLC (31) is stated, the PLC (31) judges according to the signal for receiving, and controls the 5th motor-driven valve (25) closed with the vavuum pump (10)；

Step 2：By the inlet communication seawater of the seawater intake pump (9), and start the seawater intake pump (9), the seawater Circulating pump (11) and the concentrated seawater go out water pump (12) and open first motor-driven valve (21), and now seawater is by the seawater Intake pump (9) pressurization enters and enters primary flash bucket (3), two-stage flash bucket after the heat exchanger (6) is exchanged heat (4) and the three stages of flashing bucket (5) the condenser pipe (30), the solar thermal collector (1) is then flowed into by pipeline, Then dodged by the one-level by the sea water circulating pump (11) secondary pressurized after heating in the solar thermal collector (1) The sprinkler of steaming kier (3) enter the primary flash bucket (3), due to the primary flash bucket (3) in pressure be less than into The saturated vapor pressure corresponding to seawater for entering, so seawater is after primary flash bucket (3) is entered, can at once occur part and steam Hair, while the reduction of unevaporated ocean temperature, continues through the sprinkler of two-stage flash bucket (4) into described two grades Flash distillation bucket (4), the pressure in two-stage flash bucket (4) is less than and enters the corresponding saturated vapor pressure of seawater, thus still has portion Divide evaporation, while unevaporated ocean temperature continues to reduce, then by the sprinkler entrance of three stages of flashing bucket (5) Three stages of flashing bucket (5), continuation is flashed, and the ocean temperature that part flashes continues to reduce, and by described three The seawer outlet of level flash distillation bucket (5) flows into the institute of the heat exchanger (6) in the presence of the concentrated seawater goes out water pump (12) Concentrated seawater import is stated, outflow is exported from the concentrated seawater of the heat exchanger (6) after being exchanged heat with new seawater, the one-level is dodged After steam in steaming kier (3), two-stage flash bucket (4) and three stages of flashing bucket (5) runs into the condenser pipe (30), condensation Fresh water is obtained, is collected by the fresh-water tank (32)；

Step 3：The PLC (31) controls the 8th motor-driven valve (28) to open, now the cavity (7) with it is described Three stages of flashing bucket (5) connection, the gas in the cavity (7) is entered in three stages of flashing bucket (5) by pipeline, when two containers Pressure balance when, the fresh water in three stages of flashing bucket (5) flows into the cavity (7) under gravity by pipeline；

Step 4：When the water level in the inflow cavity (7) reaches the second level sensor (18), second water level The signal that sensor (18) will be monitored sends the PLC (31) to, what PLC (31) basis was received Signal is judged, and controls the 8th motor-driven valve (28) to close, and controls the 7th motor-driven valve (27) to open, due to described three Level flash distillation bucket (5) carries out over-pressed dynamic balance with the cavity (7), and the pressure in the cavity (7) becomes negative pressure from normal pressure, together When its internal pressure less than two-stage flash bucket (4) and the pressure of primary flash bucket (3), therefore when the described 7th electricity After dynamic valve (27) is opened, the fresh water in two-stage flash bucket (4) is flowed directly into the cavity (7)；

Step 5：When the water level in the inflow cavity (7) reaches the 3rd level sensor (19), the 3rd water level The signal that sensor (19) will be monitored sends the PLC (31) to, what PLC (31) basis was received Signal is judged, and controls the 7th motor-driven valve (27) to close, and controls the 6th motor-driven valve (26) to open, due to the chamber Pressure in body (7) is less than the pressure in primary flash bucket (3), therefore after the 6th motor-driven valve (26) is opened, institute The fresh water in primary flash bucket (3) is stated to flow directly into the cavity (7)；

Step 6：When the water level in the inflow cavity (7) reaches the 4th level sensor (20), the 4th water level The signal that sensor (20) will be monitored is transmitted to the PLC (31), and the PLC (31) is according to the letter for receiving Number judge, control the 6th motor-driven valve (26) to close, control the 9th motor-driven valve (29) to open, the cavity (7) Interior pressure returns to normal pressure, while fresh water flows into the fresh water collecting apparatus by means (8) under gravity；

Step 7：When the fresh water in the cavity (7) is flowed completely out, the first level sensor (17) will be supervised in the cavity (7) The signal for measuring is transmitted to the PLC (31), and the PLC (31) judges according to the signal for receiving, and controls The 9th motor-driven valve (29) is made to close.

8. a kind of method of heat collection type solar multistage flash evaporation seawater desalting device according to claim 7, it is characterised in that： When the temperature sensor (13) monitors that the temperature of the solar thermal collector (1) outlet is less than setting value, the PLC controls Device (31) processed controls second motor-driven valve (22) to open and open the electrical auxiliary heater (2).