CN100497190C - Low-position heat energy spray evaporation-multiple-effect distillation seawater desalination method and device - Google Patents

Abstract

The invention discloses a low-level thermal energy spray evaporation-multi-effect distillation seawater desalination method and device, belonging to the technical field of seawater or brackish water desalination. The seawater desalination device includes a spray evaporation chamber provided with a nozzle and a demister, the air inlet of which is connected to the gas-water separator, and a fan and a heater are arranged on the connecting pipeline; the first-effect heating steam of the multi-effect distillation device The inlet and outlet are respectively connected with the hot and humid air outlet of the spray evaporation chamber and the middle port of the gas-water separator. The secondary steam of each effect is used as the heating steam of the next effect, but the secondary steam of the last effect is pressurized and heated and mixed into the humid heat discharged from the spray evaporation chamber. Air; the top of each effect device of the multi-effect distillation device is connected with the tube side of the shell-and-tube heat exchanger, and the bottom is connected with the concentrated brine pipeline. The invention utilizes low-level thermal energy as an energy source in the desalination process, couples spray evaporation and multi-effect distillation technology, and realizes comprehensive utilization of energy and resources.

Description

Low-level thermal energy spray evaporation-multi-effect distillation seawater desalination method and device

technical field

The invention relates to a spray evaporation-multi-effect distillation seawater desalination method and device, belonging to the technical field of seawater or brackish water desalination.

Background technique

With the development of our country's society and economy, the problem of water shortage is becoming more and more serious, and seawater and brackish water desalination technology is an effective means to solve the problem of water shortage. The existing industrial seawater desalination methods are divided into two categories: thermal methods (such as multi-stage flash evaporation, multi-effect distillation) and membrane methods (such as reverse osmosis). Thermal desalination uses thermal energy to cause a phase change in brine, evaporates water, and then condenses to obtain fresh water; thermal desalination requires steam as a heat source, which requires high energy consumption, and requires a steam generating device, which is expensive and requires a large investment. Membrane method is to use separation membrane to intercept or remove the salt in brine to obtain fresh water; there is membrane fouling problem in membrane desalination process, which requires regular cleaning or replacement of membrane components, and the daily operation and maintenance are more complicated, so the The requirements for raw seawater pretreatment are relatively strict, and the cost of pretreatment is high. The concentrated seawater produced by the two desalination methods is generally discharged directly. Although it can also be used to make salt and extract various chemical elements such as potassium and magnesium, it still needs secondary concentration.

The spray evaporation desalination technology avoids the above problems. The principle of this technology is: spray the brine in the form of mist to the hot air, so that the water in the brine quickly turns into water vapor, so the brine is highly concentrated or the salt in the brine forms solid particles Precipitation separates from water, and fresh water can be produced by cooling a hot air stream containing water vapor. In daily operation, this desalination method does not require complicated maintenance like the membrane method, nor does it need to be equipped with a special device for generating steam. The requirements for the pretreatment of the feed brine are relatively low. Studies have shown that by using spray evaporation desalination technology, more than 95% of the water in seawater can be separated, and the precipitated salt has a very low water content, and can even directly form solid crystals, which can be conveniently used for salt production or for extraction of various other substances. class of chemical elements. However, in the spray evaporation desalination process, in order to produce fresh water, a large amount of cooling water is required in the cooling process of the hot gas stream containing water vapor. The amount of cooling water required to produce 1 kg of fresh water ranges from about 7 kg to more than 20 kg. The promotion of this technology Therefore subject to certain restrictions.

Contents of the invention

The object of the present invention is to provide a spray evaporation-multi-effect distillation seawater desalination method, which couples spray evaporation and multi-effect distillation technology to realize comprehensive utilization of energy and resources.

Another object of the present invention is to provide a spray evaporation-multi-effect distillation seawater desalination device.

The purpose of the present invention is achieved through the following technical solutions.

A spray evaporation-multi-effect distillation seawater desalination device, characterized in that:

i) The device includes a spray evaporation chamber, a brine nozzle is installed on the left side of the spray evaporation chamber cavity, the inlet of the nozzle is connected to the outlet of the brine storage tank, and a pump is provided on the connecting pipeline;

j) The air inlet on the left side wall of the spray evaporation chamber is connected to the upper port of the vertical gas-water separator, and a fan and a heater 1 are sequentially arranged on the connecting pipeline from the gas-water separator to the spray evaporation chamber;

k) The bottom of the spray evaporation chamber is provided with a high-concentration brine outlet, the right side wall is provided with a hot and humid air outlet, and a demister is installed in front of the hot and humid air outlet;

1) The heating steam inlet and outlet of the first effect device of the multi-effect distillation device are respectively connected with the hot and humid air outlet of the spray evaporation chamber and the middle port of the gas-water separator, and the heating steam inlets of the other effect devices are connected with the secondary steam of the previous effect device. export connectivity;

m) The secondary steam outlet of the final effect device of the multi-effect distillation device is connected with the heating steam inlet of the first effect device, and a compressor and a heater are arranged in sequence on the connecting pipeline from the secondary steam outlet of the final effect device to the heating steam inlet of the first effect device. device two;

n) The outlets of the heating steam condensed water of the multi-effect distillation units except the first effect are all connected to the fresh water pipeline;

o) The top of each effect device of the multi-effect distillation device is connected to the tube side of the heat exchanger, and the bottom end is connected to the concentrated brine pipeline, wherein a branch is provided on the concentrated brine pipeline to communicate with the brine storage tank;

p) The shell side of the heat exchanger communicates with the lower port of the gas-water separator.

Utilize the seawater desalination method of above-mentioned spray evaporation-multi-effect distillation seawater desalination device, it is characterized in that comprising following process:

h) The air is transported by the fan to the heater 1, and enters the spray evaporation chamber after being heated; at the same time, the concentrated brine in the brine storage tank is transported to the nozzle by the pump, and then sprayed in the inner cavity of the spray evaporation chamber in the form of mist, and is mixed with the heat The gas flow contacts and vaporizes;

i) The water vapor obtained from the vaporization of salt water droplets is mixed with air, and the hot and humid air formed passes through the demister and then discharged out of the spray evaporation chamber; after vaporization, the remaining salt water droplets are concentrated and condensed into high-concentration salt water at the bottom of the spray evaporation chamber, and are produced Discharge from the outlet at the bottom of the spray evaporation chamber;

j) The hot and humid air discharged from the spray evaporation chamber enters the heating pipe of the first effect device of the multi-effect distillation device, and is used as a heat source of the multi-effect distillation device; the moisture in the hot and humid air is condensed in the heating pipe of the first effect device of the multi-effect distillation device. Water and air are discharged into the air-water separator;

k) Air is discharged from the upper port of the gas-water separator and reintroduced into the fan for recycling; water is discharged from the lower port of the gas-water separator, enters the shell side of the heat exchanger and is used to preheat the feed brine of the tube side;

1) The preheated feed salt flows horizontally into each effect of the multi-effect distillation device, and the concentrated brine after evaporation is discharged into the brine pipeline from the bottom outlet of each effect device, and a part of the brine is discharged into the brine storage tank. The secondary steam generated by each effect is used as the heating steam for the next effect;

m) After the final effect secondary steam of the multi-effect distillation device is compressed by the compressor and heated by the second heater, it is mixed with the hot and humid air discharged from the spray evaporation chamber;

n) The condensed water of the heating steam of each effect except the first effect of the multi-effect distillation device is discharged into the fresh water pipeline.

in,

The above-mentioned heater two is a solar heat collector, or a partition heat exchanger using low-level thermal energy as a heat source.

The low-level thermal energy heat source used by the above-mentioned heater 2 is ground heat or factory waste heat.

The water vapor outlet temperature of the above-mentioned heater two is 60-250°C.

The number of effects of the above-mentioned multi-effect distillation device 4 is 1 effect to 20 effects.

The above-mentioned heat exchanger is a shell-and-tube structure or a plate-and-frame structure.

The above-mentioned heater one is a solar heat collector, or a partitioned wall heat exchanger using low-level thermal energy as a heat source.

The low-level thermal energy heat source used by the above-mentioned heater 1 is ground heat or factory waste heat.

The air outlet temperature of the above-mentioned heater one is 60-250°C.

The present invention uses low-level thermal energy as a heat source, which is beneficial to reduce the cost of seawater desalination; on the basis of the traditional multi-effect distillation seawater desalination process, fresh water is further extracted from concentrated brine by spray evaporation, and the produced high-concentration brine can also be used for The seawater comprehensive utilization process such as salt production and the extraction of potassium, magnesium and other chemical elements not only increases the freshwater production, but also helps to reduce the cost of comprehensive utilization of seawater, and has broad application prospects.

Description of drawings

Fig. 1 is a schematic diagram of the composition of the device of the present invention.

In the picture:

1-spray evaporation chamber; 2-demister; 3-heater two; 4-multi-effect distillation device; 5-compressor; 6-heat exchanger; 7-gas-water separator; 8-nozzle; 9-pump ; 10-brine storage tank; 11-fan; 12-heater one.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments.

Example 1:

a) The air is transported by the fan 11 to the heater one 12, and enters the spray evaporation chamber 1 after being heated to 100°C; at the same time, the concentrated brine in the brine storage tank 10 is transported to the nozzle 8 by the pump 9, and then sprayed on the spray In the inner cavity of the evaporation chamber 1, it is in contact with the hot air flow and vaporized;

b) The water vapor obtained from the vaporization of salt water droplets is mixed with air, and the hot and humid air formed passes through the demister 2 and then discharged out of the spray evaporation chamber 1; the remaining salt water droplets after vaporization are concentrated at the bottom of the spray evaporation chamber 1 and condensed into high-concentration salt water , and discharged from the outlet at the bottom of the spray evaporation chamber 1; the high-concentration brine is used for salt production and the extraction of chemical elements such as potassium and magnesium;

c) The hot and humid air discharged from the spray evaporation chamber 1 enters the heating pipe of the first effect device of the multi-effect distillation device 4, and is used as the heat source of the multi-effect distillation device 4; the moisture in the hot and humid air is heated in the first effect device of the multi-effect distillation device 4 Condensate in the tube, and the condensed water is discharged into the air-water separator 7 together with the air;

d) Air is discharged from the upper port of the gas-water separator 7 and reintroduced into the fan 11 for recycling; water is discharged from the lower port of the gas-water separator 7, enters the shell side of the heat exchanger 6 and is used for feeding brine for preheating the tube side;

e) The feed salt after preheating enters each effect of multi-effect distillation device 4 horizontally, and the concentrated brine after evaporation is discharged into the concentrated brine pipeline from the bottom outlet of each effect device, wherein a part of the concentrated brine of the first effect device is discharged into The brine storage tank 10, the secondary steam produced by each effect is used as the heating steam of the next effect;

f) After the final effect secondary steam of the multi-effect distillation device 4 is compressed by the compressor 5 and heated by the heater 23, it is mixed with the hot and humid air discharged from the spray evaporation chamber 1;

g) The condensed water of the heating steam of each effect except the first effect of the multi-effect distillation device 4 is discharged into the fresh water pipeline.

The heat source of heater two 3 and heater one 12 described in this embodiment is waste heat from a power plant.

The feed seawater flow rate described in this embodiment is 209kg/h, the initial temperature is 20°C, and the initial concentration is 3.21%; the effect number of the multi-effect distillation device 4 is 3 effects, and the effective heat transfer area of each effect is 2.0m ² ; the fresh water output of the multi-effect distillation unit 4 is 102.6kg/h, and the salt content of the fresh water is 4.9mg/L.

The air flow rate produced by the blower fan 11 described in this embodiment is 92.08kg _{dry air} /h, the temperature of the normal-pressure hot and humid air produced by the spray evaporation chamber 1 is 75°C, and the water content is 0.37kg _water /kg _{dry air} . After the hot and humid air is condensed The fresh water output provided is 31.07kg/h, and the salt content of the fresh water is 5.1mg/L.

The spray evaporation-multi-effect distillation process described in this embodiment increases the fresh water production by 30.28% on the basis of the common multiple-effect distillation process, and the benefit of increasing production is obvious.

Example 2:

The device and working process are the same as in Example 1, except that the air flow produced by the fan 11 is 139kg _{dry air} /h, the heating temperature of the air in the heater one 12 is 95°C, and the normal pressure hot and humid air produced by the spray evaporation chamber 1 The temperature is 70°C, the water content is 0.27kg _water /kg _{dry air} , and the fresh water output provided by the condensation of hot and humid air is 32.4kg/h. In this embodiment, the feed seawater flow rate of the multi-effect distillation device 4 is 221.1 kg/h, the fresh water output is 100.5 kg/h, and the salt content of the fresh water is 4.6 mg/L. The spray evaporation-multi-effect distillation process described in this embodiment increases the fresh water production by 32.24% on the basis of the common multiple-effect distillation process.

Claims (10)

1. A low-level thermal energy spray evaporation-multi-effect distillation seawater desalination device, characterized in that: a) the device comprises a spray evaporation chamber (1), a brine nozzle (8) is installed on the left side of the spray evaporation chamber (1) inner cavity, the inlet of the nozzle (8) is connected with the outlet of the brine storage tank (10), and A pump (9) is provided on the connecting pipeline; b) The air inlet on the left side wall of the spray evaporation chamber (1) is connected to the upper port of the vertical gas-water separator (7), and on the connecting pipeline from the gas-water separator (7) to the spray evaporation chamber (1) A blower fan (11) and a heater one (12) are arranged in turn; c) The bottom of the spray evaporation chamber (1) is provided with a high-concentration brine outlet, the right side wall is provided with a hot and humid air outlet, and a demister (2) is installed in front of the hot and humid air outlet; d) The heating steam inlet and outlet of the first effect device of the multi-effect distillation device (4) are respectively connected with the hot and humid air outlet of the spray evaporation chamber (1) and the central port of the gas-water separator (7), and the heating steam inlets of the other effect devices are uniform Connected with the secondary steam outlet of the previous effect device; e) Multi-effect distillation unit (4) The secondary steam outlet of the final effect device is connected with the heating steam inlet of the first effect device, and the connecting pipeline from the secondary steam outlet of the final effect device to the heating steam inlet of the first effect device is sequentially provided with compression Machine (5) and heater two (3); f) Multi-effect distillation unit (4) Except for the first effect, the condensed water outlets of the heating steam of each effect unit are connected to the fresh water pipeline; g) The top of each effect device of the multi-effect distillation device (4) is connected to the pipe side of the heat exchanger (6), and the bottom end is connected to the concentrated brine pipeline, wherein a branch is provided on the concentrated brine pipeline and the brine storage tank (10 ) connected; h) The shell side of the heat exchanger (6) communicates with the lower port of the gas-water separator (7). 2. A low-level thermal energy spray evaporation-multi-effect distillation seawater desalination method is characterized in that it comprises the following processes: a) The air is delivered to the heater one (12) by the fan (11), and enters the spray evaporation chamber (1) after being heated; at the same time, the concentrated brine in the brine storage tank (10) is delivered to the nozzle (8) by the pump (9) ), then spray in the inner cavity of the spray evaporation chamber (1) in mist form, contact with the hot air flow and vaporize; b) The water vapor obtained from the vaporization of salt water droplets is mixed with air, and the hot and humid air formed passes through the demister (2) and then discharged out of the spray evaporation chamber (1); after vaporization, the remaining salt water droplets are concentrated at the bottom of the spray evaporation chamber (1) , Condensed into high-concentration brine, and discharged from the outlet at the bottom of the spray evaporation chamber (1); c) The hot and humid air discharged from the spray evaporation chamber (1) enters the heating pipe of the first effect device of the multi-effect distillation device (4), and is used as the heat source of the multi-effect distillation device (4); the moisture in the hot and humid air is in the multi-effect distillation The device (4) condenses in the heating tube of the first effect device, and the condensed water is discharged into the air-water separator (7) together with the air; d) Air is discharged from the upper port of the gas-water separator (7) and reintroduced into the fan (11) for recycling; water is discharged from the lower port of the gas-water separator (7), enters the shell side of the heat exchanger (6) and is used for pre-heating Feed brine for heat pipe; e) The preheated feed salt horizontally flows into each effect of the multi-effect distillation device (4), and the concentrated brine after evaporation is discharged into the brine pipeline from the bottom outlet of each effect device, wherein a part of the brine is discharged into the brine Storage tank (10), the secondary steam that each effect produces is used as the heating steam of next effect; f) After the final effect secondary steam of the multi-effect distillation device (4) is compressed by the compressor (5) and heated by the second heater (3), it is mixed with the hot and humid air discharged from the spray evaporation chamber (1); g) Multi-effect distillation unit (4) The condensed water of the heating steam of each effect except the first effect is discharged into the fresh water pipeline. 3. The low-level thermal energy spray evaporation-multi-effect distillation seawater desalination device according to claim 1, characterized in that: the second heater (3) is a solar heat collector, or a partition heat exchanger using low-level thermal energy as a heat source. 4. The low-level thermal energy spray evaporation-multi-effect distillation seawater desalination device according to claim 1, characterized in that: the low-level thermal energy heat source used by the heater two (3) is geothermal or factory waste heat. 5. The low-level thermal energy spray evaporation-multi-effect distillation seawater desalination device according to claim 1, characterized in that the temperature of the water vapor outlet of the heater two (3) is 60-250°C. 6. The low-level thermal energy spray evaporation-multi-effect distillation seawater desalination device according to claim 1, characterized in that: the number of effects of the multi-effect distillation device (4) is 1 to 20 effects. 7. The low-level thermal energy spray evaporation-multi-effect distillation seawater desalination device according to claim 1, characterized in that: the heat exchanger (6) is a shell-and-tube structure or a plate-and-frame structure. 8. The low-level thermal energy spray evaporation-multi-effect distillation seawater desalination device according to claim 1, characterized in that: heater one (12) is a solar heat collector, or a partition heat exchanger using low-level thermal energy as a heat source. 9. The low-level thermal energy spray evaporation-multi-effect distillation seawater desalination device according to claim 1, characterized in that: the low-level thermal energy heat source used by heater one (12) is geothermal or factory waste heat. 10. The low-level heat energy spray evaporation-multi-effect distillation seawater desalination device according to claim 1, characterized in that: the air outlet temperature of heater one (12) is 60-250°C.

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