A device and method for mineralizing desalinated water

Abstract

The present invention provides a device and method for mineralizing desalinated seawater, belonging to the technical field of desalination water production. The device of the present invention comprises a concentrated brine device 100, a bipolar membrane device 200 and a mineralization device 300 connected in sequence; wherein the concentrated brine device 100 comprises a sodium sulfate concentrated solution tank 101. The present invention prepares desalinated water into a sodium sulfate solution, and there is no risk of scaling and clogging during bipolar membrane electrodialysis, thereby ensuring the safe operation of the bipolar membrane device 200, and the corrosiveness of sulfate to the pipe network is reduced compared to chloride ions. The mineralization device 300 of the present invention comprises a dilute acid tank 301, which can control the pH value of the acid solution before mineralization; the dilute sulfuric acid solution enters the mineralization tower 302, which can effectively convert the acidity of the solution into alkalinity and increase the hardness; the alkali produced by the bipolar membrane alkali chamber 201 enters the mineralized water mixing tank 303, which can adjust the pH value of the water produced by the mineralization tower, so that the mineralized water produced by the desalinated seawater meets the drinking standard.

Description

Technical Field

[0001] The invention relates to the technical field of seawater desalination water production, and in particular to a device and method for mineralizing seawater desalination water. Background Art

[0002] Due to the global shortage of fresh water resources, seawater desalination has developed rapidly in recent years as a water resource increment technology. Some coastal water-scarce cities have been using a large amount of desalinated water as a necessary supplement for urban water use. However, since the quality of desalinated water basically has no buffering capacity, it will dissolve the protective scale layer on the inner wall of cast iron pipes and steel pipes, causing corrosion of municipal pipe networks. At the same time, it will increase the turbidity, color, and iron content of water supply during transmission and distribution, causing the water quality to deteriorate and fail to meet drinking water standards. Therefore, before desalinated water enters the network, it needs to be post-mineralized to improve the buffering performance of desalinated water and reduce its erosion to the pipe network.

[0003] The ore dissolution method is currently the simplest and most widely used method for post-mineralization of desalinated water. It is to pass desalinated water through a reactor filled with calcium carbonate ore, dissolve the calcium carbonate in the ore to increase the alkalinity and hardness of the desalinated water, and achieve the mineralization of the desalinated water. However, the pH value of desalinated water is generally between 5 and 7, which leads to a very slow dissolution rate of the ore, so it is necessary to acidify the desalinated water to improve efficiency.

[0004] Bipolar membrane electrodialysis can produce acids and bases, which can be used for the acidification of desalinated water. However, the use of sodium chloride brine or seawater desalination reverse osmosis concentrate in bipolar membrane electrodialysis can cause chloride ions to enter the mineralized water, which is easy to corrode the pipeline facilities and does not meet the requirements of safe transmission and distribution; and the content of impurity ions in seawater desalination reverse osmosis concentrate is high, and direct use in bipolar membrane electrodialysis is prone to cause bipolar membrane blockage; at the same time, in the process of preparing acids and bases in bipolar membrane electrodialysis, the acid concentration cannot be accurately controlled, which affects the mineralization effect, resulting in the final mineralized water not meeting the standards and waste of production capacity. Summary of the invention

[0005] In view of this, the present invention aims to provide a device and method for mineralizing desalinated seawater. The desalinated seawater mineralized water obtained by the device and method provided by the present invention can meet drinking standards and safe distribution requirements.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a device for mineralizing desalinated seawater, comprising a concentrated brine device 100, a bipolar membrane device 200 and a mineralization device 300 which are connected in sequence;

[0008] The concentrated brine device 100 comprises a sodium sulfate concentrated solution tank 101; the sodium sulfate concentrated solution tank 101 is provided with a first desalinated water inlet, a desalinated brine inlet, a sodium sulfate feed port and a concentrated brine outlet;

[0009] The bipolar membrane device 200 includes a bipolar membrane electrodialysis chamber, a concentrated acid solution tank 205 and a concentrated alkali solution tank 204, wherein the bipolar membrane electrodialysis chamber is divided into a bipolar membrane alkali chamber 201, a bipolar membrane salt chamber 202 and a bipolar membrane acid chamber 203 by a bipolar membrane; the bipolar membrane alkali chamber 201 is provided with a second desalinated water inlet and a concentrated alkali outlet, and the concentrated alkali outlet is communicated with the inlet of the concentrated alkali solution tank 204; the bipolar membrane salt chamber 202 is provided with a third desalinated water inlet and a sodium sulfate concentrated solution inlet, the sodium sulfate concentrated solution inlet is communicated with the concentrated brine outlet of the sodium sulfate concentrated solution tank 101, and the outlet of the bipolar membrane salt chamber 202 is communicated with the desalinated brine inlet of the sodium sulfate concentrated solution tank 101; the bipolar membrane acid chamber 203 is provided with a fourth desalinated water inlet and a concentrated acid outlet, and the concentrated acid outlet is communicated with the inlet of the concentrated acid solution tank 205;

[0010] The mineralization device 300 includes a dilute acid tank 301, a mineralization tower 302 and a mineralized water mixing tank 303; the dilute acid tank 301 is provided with a fifth desalinated water inlet, a concentrated acid solution inlet and a dilute acid outlet, and the concentrated acid solution inlet is connected to the outlet of the concentrated acid solution tank 205; the inlet of the mineralization tower 302 is connected to the dilute acid outlet of the dilute acid tank 301; the mineralized water mixing tank 303 is provided with a sixth desalinated water inlet, a mineralization tower produced water inlet connected to the outlet of the mineralization tower 302, and a concentrated alkali solution inlet connected to the outlet of the concentrated alkali solution tank 204.

[0011] Preferably, the sodium sulfate concentrated solution tank 101 is provided with a first conductivity meter 102, a liquid level meter 103 and a first agitator 104;

[0012] The bipolar membrane alkali chamber 201 is provided with a first concentrated alkali concentration online monitoring device 206; the bipolar membrane salt chamber 202 is provided with a second conductivity meter 207 and a second stirrer 208; the bipolar membrane acid chamber 203 is provided with a first concentrated acid concentration online monitoring device 209;

[0013] The concentrated acid solution tank 205 is provided with a second concentrated acid concentration online monitoring device 211; the concentrated alkali solution tank 204 is provided with a second concentrated alkali concentration online monitoring device 210;

[0014] The diluted acid tank 301 is provided with a first online pH meter 304 .

[0015] Preferably, a second online pH meter 305, a first online hardness monitor 306 and a first online alkalinity monitor 307 are provided at the outlet of the mineralization tower 302;

[0016] A third online pH meter 308 , a second online hardness monitor 309 and a second online alkalinity monitor 310 are provided at the outlet of the mineralized water mixing tank 303 .

[0017] Preferably, the number of membrane pairs of the bipolar membrane is 5 to 80 pairs.

[0018] Preferably, the filler in the mineralization tower 302 includes limestone and medical stone in order according to the liquid flow direction;

[0019] The height of the limestone is 30 to 300 cm, and the height of the medical stone is 20 to 160 cm;

[0020] The particle sizes of the limestone and medical stone are independently 1 to 4 mm.

[0021] The present invention provides a method for mineralizing seawater desalination water based on the above device, comprising the following steps:

[0022] (1) Desalinated water and sodium sulfate enter the sodium sulfate concentrated solution tank 101 for mixing to obtain a sodium sulfate solution;

[0023] (2) Sodium sulfate solution enters bipolar membrane salt chamber 202, and desalinated water enters bipolar membrane salt chamber 202, bipolar membrane alkali chamber 201 and bipolar membrane acid chamber 203; desalinated water and sodium sulfate solution are mixed into bipolar membrane salt chamber 202 in proportion, and the volume ratio of sodium sulfate concentrated solution added to desalinated water mixed is 1:0.1-4; when the mass concentration of sodium sulfate solution in bipolar membrane salt chamber 202 is 3-8%, bipolar membrane electrodialysis is performed to obtain sulfuric acid solution in bipolar membrane acid chamber 203 and sodium hydroxide solution in bipolar membrane alkali chamber 201; when the mass concentration of sodium sulfate solution in bipolar membrane salt chamber 202 is lower than 3%, the sodium sulfate solution in bipolar membrane salt chamber 202 returns to sodium sulfate concentrated solution tank 101;

[0024] (3) The sulfuric acid solution obtained in the bipolar membrane acid chamber 203 enters the concentrated acid solution tank 205, and the sulfuric acid solution and desalinated water in the concentrated acid solution tank 205 enter the dilute acid tank 301 for mixing to obtain a dilute sulfuric acid solution, wherein the pH value of the dilute sulfuric acid solution is 1 to 3;

[0025] (4) The dilute sulfuric acid solution enters the mineralization tower 302 for mineralization reaction to obtain mineralization tower product water;

[0026] (5) The sodium hydroxide solution enters the concentrated alkali solution tank 204, and the sodium hydroxide solution in the concentrated alkali solution tank 204, the mineralization tower water and the desalinated water enter the mineralization water mixing tank 303 for mixing to obtain seawater desalinated water mineralized water; the flow ratio of the mineralization tower water and the seawater desalinated water mineralized water is 1:1-10;

[0027] There is no time sequence requirement for the sodium hydroxide solution entering the concentrated alkali solution tank 204 in step (5) and steps (3) and (4).

[0028] Preferably, the mass concentration of the sodium sulfate solution in step (1) is 8-14%.

[0029] Preferably, the current of the bipolar membrane electrodialysis is 10-50A; the mass concentration of the sulfuric acid solution obtained by the bipolar membrane acid chamber is 0.2-5%, and the mass concentration of the sodium hydroxide solution obtained by the bipolar membrane alkali chamber is 0.6-4%.

[0030] Preferably, the residence time of the dilute sulfuric acid solution during the mineralization reaction is 5 to 60 minutes; the pH value of the water produced by the mineralization tower is 6.3 to 7.1, the total hardness is 80 to 2000 mg / L, and the total alkalinity is 50 to 600 mg / L.

[0031] Preferably, in step (5), the volume ratio of the water produced from the mineralization tower to the water produced from the seawater desalination mineralization is 1:1-10; the pH value of the water produced from the seawater desalination mineralization is 7-8.5, the total alkalinity is 50-150 mg / L, and the total hardness is 50-200 mg / L.

[0032] The present invention provides a device for mineralizing desalinated seawater, comprising a concentrated brine device 100, a bipolar membrane device 200 and a mineralization device 300 connected in sequence. The concentrated brine device 100 of the present invention comprises a sodium sulfate concentrated solution tank 101 whose inlet is connected to desalinated water. The present invention prepares desalinated water into a sodium sulfate solution, thereby eliminating the risk of scaling and clogging during bipolar membrane electrodialysis, thereby ensuring the safe operation of the bipolar membrane device 200. The bipolar membrane device 200 produces a sulfuric acid solution, and sulfate ions enter the mineralized water after a mineralization reaction, which reduces the corrosiveness of the pipe network compared to chloride ions. The bipolar membrane device 200 of the present invention includes a dilute acid tank 301 connected to a concentrated acid solution tank 205, which can control the pH value of the acid solution before mineralization; the mineralization device 300 of the present invention includes a mineralization tower 302 and a mineralized water mixing tank 303. The dilute sulfuric acid solution produced by the dilute acid tank 301 enters the mineralization tower 302, which can effectively convert the acidity of the solution into alkalinity and increase the hardness; the alkali produced by the bipolar membrane alkali chamber 201 enters the mineralized water mixing tank 303, which can adjust the pH value of desalinated water and water produced by the mineralization tower, so that the mineralized water produced by seawater desalination meets the drinking standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1The present invention is a schematic structural diagram of a device for mineralizing seawater desalination water, wherein 100 is a concentrated brine device, 101 is a sodium sulfate concentrated solution tank, 102 is a first conductivity meter, 103 is a liquid level meter, 104 is a first agitator, 105 is a distribution valve, 106 is a brine pump, 107 is a concentrated salt metering pump, 200 is a bipolar membrane device, 201 is a bipolar membrane alkali chamber, 202 is a bipolar membrane salt chamber, 203 is a bipolar membrane acid chamber, 204 is a concentrated alkali solution tank, 205 is a concentrated acid solution tank, 206 is a first concentrated alkali concentration online monitoring device, 207 is a second conductivity meter, 208 is a second agitator, 209 is a first concentrated acid concentration online monitoring device, 210 is a second concentrated alkali concentration online monitoring device, 211 is a second concentrated alkali concentration online monitoring device, 212 is a second concentrated alkali concentration online monitoring device, 213 is a second concentrated alkali concentration online monitoring device, 214 is a second concentrated alkali concentration online monitoring device, 215 is a second concentrated alkali concentration online monitoring device, 216 is a second concentrated alkali concentration online monitoring device, 217 is a second concentrated alkali concentration online monitoring device, 218 is a second concentrated alkali concentration online monitoring device, 219 is a second concentrated alkali concentration online monitoring device, 220 is a second concentrated alkali concentration online monitoring device, 221 is a second concentrated alkali concentration online monitoring device, 222 is a second concentrated alkali concentration online monitoring device, 223 is a second concentrated alkali concentration online monitoring device, 224 is a second concentrated alkali concentration online monitoring device, 225 is a second concentrated alkali concentration online monitoring device, 226 is a second concentrated alkali concentration online monitoring device, 227 is a second concentrated 1-second concentrated acid concentration online monitoring device, 212-distribution valve, 213-distribution valve, 214-distribution valve, 215-concentrated alkali pump, 216-concentrated acid pump, 300-mineralization device, 301-diluted acid tank, 302-mineralization tower, 303-mineralized water mixing tank, 304-first online pH meter, 305-second online pH meter, 306-first online hardness monitor, 307-first online alkalinity detector, 308-third online pH meter, 309-second online hardness monitor, 310-second online alkalinity detector, 311-distribution valve, 312-distribution valve, 313-diluted acid pump, 314-mineralized water pump, 315-concentrated acid metering pump, 316-concentrated alkali metering pump. DETAILED DESCRIPTION

[0034] The present invention provides a device for mineralizing desalinated seawater, comprising a concentrated brine device 100, a bipolar membrane device 200 and a mineralization device 300 which are connected in sequence;

[0035] The concentrated brine device 100 comprises a sodium sulfate concentrated solution tank 101; the sodium sulfate concentrated solution tank 101 is provided with a first desalinated water inlet, a desalinated brine inlet and a sodium sulfate feeding port;

[0036] The bipolar membrane device 200 includes a bipolar membrane electrodialysis chamber, a concentrated acid solution tank 205 and a concentrated alkali solution tank 204, wherein the bipolar membrane electrodialysis chamber includes a bipolar membrane alkali chamber 201, a bipolar membrane salt chamber 202 and a bipolar membrane acid chamber 203; the bipolar membrane alkali chamber 201 is provided with a second desalinated water inlet and a concentrated alkali outlet, and the concentrated alkali outlet is communicated with the inlet of the concentrated alkali solution tank 204; the bipolar membrane salt chamber 202 is provided with a third desalinated water inlet and a sodium sulfate concentrated solution inlet, the sodium sulfate concentrated solution inlet is communicated with the outlet of the sodium sulfate concentrated solution tank 101, and the outlet of the bipolar membrane salt chamber 202 is communicated with the salt water inlet of the sodium sulfate concentrated solution tank 101; the bipolar membrane acid chamber 203 is provided with a fourth desalinated water inlet and a concentrated acid outlet, and the concentrated acid outlet is communicated with the inlet of the concentrated acid solution tank 205;

[0037] The mineralization device 300 includes a dilute acid tank 301, a mineralization tower 302 and a mineralized water mixing tank 303; the dilute acid tank 301 is provided with a fifth desalinated water inlet and an acid solution inlet, and the acid solution inlet is connected to the outlet of the concentrated acid solution tank 205; the inlet of the mineralization tower 302 is connected to the outlet of the dilute acid tank 301; the mineralized water mixing tank 303 is provided with a sixth desalinated water inlet, a mineralization tower produced water inlet connected to the outlet of the mineralization tower 302, and a concentrated alkali solution inlet connected to the outlet of the concentrated alkali solution tank 204.

[0038] The structural schematic diagram of the device for mineralizing seawater desalination water is as follows Figure 1 shown.

[0039] The device provided by the present invention includes a concentrated brine device 100, and the concentrated brine device 100 includes a sodium sulfate concentrated solution tank 101 whose inlet is connected to desalinated water; the sodium sulfate concentrated solution tank 101 is provided with a first desalinated water inlet, a desalinated brine inlet and a sodium sulfate feeding port. In the present invention, the sodium sulfate concentrated solution tank 101 is provided with a sodium sulfate solution outlet. The present invention has no special requirements on the material and specifications of the sodium sulfate concentrated solution tank 101, and the sodium sulfate concentrated solution tank 101 of a material familiar to those skilled in the art can be used and the specific specifications of the sodium sulfate concentrated solution tank 101 can be designed according to actual working conditions.

[0040] In the present invention, the sodium sulfate concentrated solution tank 101 is preferably provided with a first conductivity meter 102, a liquid level meter 103 and a first agitator 104. The present invention has no special requirements on the types of the first conductivity meter 102, the liquid level meter 103 and the first agitator 104, and the conductivity meter, liquid level meter and agitator well known to those skilled in the art can be used. The present invention has no special requirements on the installation positions of the first conductivity meter 102, the liquid level meter 102 and the first agitator 104 in the sodium sulfate concentrated solution tank 101, and it is sufficient to ensure that they play the corresponding role.

[0041] The device provided by the present invention includes a bipolar membrane device 200, and the bipolar membrane device 200 includes a bipolar membrane electrodialysis chamber, a concentrated acid solution tank 205 and a concentrated alkali solution tank 204; the bipolar membrane electrodialysis chamber includes a bipolar membrane alkali chamber 201, a bipolar membrane salt chamber 202 and a bipolar membrane acid chamber 203. In the present invention, the number of the bipolar membranes is preferably 5 to 80 pairs, and the specification is preferably 400×800mm; the present invention has no special requirements on the source of the bipolar membrane, and the conventional commercially available bipolar membranes in the field can be used. As a specific embodiment of the present invention, the bipolar membrane is preferably a Fuji bipolar membrane. The size specifications of the bipolar membrane alkali chamber 201, the bipolar membrane salt chamber 202 and the bipolar membrane acid chamber 203 are preferably 20 to 200L.

[0042] In the present invention, the bipolar membrane alkali chamber 201 is provided with a second desalinated water inlet and a concentrated alkali outlet, and the concentrated alkali outlet is connected to the concentrated alkali inlet of the concentrated alkali solution tank 204. As an embodiment of the present invention, the bipolar membrane alkali chamber 201 is provided with a first concentrated alkali concentration online monitoring device 206; the present invention has no special requirements on the model of the first concentrated alkali concentration online monitoring device 206, and a concentrated alkali concentration online monitoring device well known to those skilled in the art can be used; as a specific embodiment of the present invention, the first concentrated alkali concentration online monitoring device 206 is preferably an intelligent digital display PH (ORP) controller of model PG100 produced by Shanghai Sanxin Company. The present invention has no special requirements on the installation position of the first concentrated alkali concentration online monitoring device 206, and it can ensure that it plays a corresponding role.

[0043] In the present invention, the bipolar membrane salt chamber 202 is provided with a third desalinated water inlet and a sodium sulfate concentrated solution inlet, and the sodium sulfate concentrated solution inlet is connected to the outlet of the sodium sulfate concentrated solution tank 101; the outlet of the bipolar membrane salt chamber 202 is connected to the desalinated water inlet of the sodium sulfate concentrated solution tank 101. As a specific embodiment of the present invention, the bipolar membrane salt chamber 202 is provided with a second conductivity meter 207 and a second agitator 208. The present invention has no special requirements for the type and model of the second conductivity meter 207 and the second agitator 208, and the conductivity meter and agitator familiar to those skilled in the art can be used. The present invention has no special requirements for the installation position 208 of the second conductivity meter 207 and the second agitator, and it is sufficient to ensure that they play the corresponding role.

[0044] In the present invention, the bipolar membrane acid chamber 203 is provided with a fourth desalinated water inlet and a concentrated acid outlet, and the concentrated acid outlet is connected to the inlet of the concentrated acid solution tank 205. As an embodiment of the present invention, the bipolar membrane acid chamber 203 is provided with a first concentrated acid concentration online monitoring device 209; the present invention has no special requirements on the model of the first concentrated acid concentration online monitoring device 209, and a concentrated acid concentration online monitoring device familiar to those skilled in the art can be used; as a specific embodiment of the present invention, the first concentrated acid concentration online monitoring device 209 is preferably an intelligent digital display PH (ORP) controller of model PG100 produced by Shanghai Sanxin Company. The present invention has no special requirements on the installation position of the first concentrated acid concentration online monitoring device 209, and it can ensure that it plays a corresponding role.

[0045] In the present invention, the material of the concentrated alkali solution tank 204 is preferably PE; the present invention has no special requirements for the specifications of the concentrated alkali solution tank 204, and the corresponding specifications of the concentrated alkali solution tank 204 can be designed according to the actual working conditions. In the present invention, the concentrated alkali solution tank 204 is used to contain the alkali solution produced by the bipolar membrane alkali chamber 201. As an embodiment of the present invention, the concentrated alkali solution tank 204 is provided with a second concentrated alkali concentration online monitoring device 210. The present invention has no special requirements for the installation position of the second concentrated alkali concentration online monitoring device 210, and it can ensure that it plays a corresponding role.

[0046] In the present invention, the material of the concentrated acid solution tank 205 is preferably PE; the present invention has no special requirements for the specifications of the concentrated acid solution tank 205, and the corresponding specifications of the concentrated acid solution tank 205 can be designed according to the actual working conditions. In the present invention, the concentrated acid solution tank 205 is used to contain the acid solution produced by the bipolar membrane acid chamber 203. As a specific embodiment of the present invention, the concentrated acid solution tank 204 is provided with a second concentrated acid concentration online monitoring device 211. The present invention has no special requirements for the installation position of the second concentrated acid concentration online monitoring device 211, and it is sufficient to ensure that it plays a corresponding role.

[0047] The device for mineralizing desalinated seawater of the present invention comprises a mineralization device 300, and the mineralization device 300 comprises a dilute acid tank 301, a mineralization tower 302 and a mineralized water mixing tank 303. In the present invention, the dilute acid tank 301 is provided with a fourth desalinated water inlet and a concentrated acid inlet, and the concentrated acid inlet is connected to the outlet of the concentrated acid solution tank 205. In the present invention, the material of the dilute acid tank 301 is preferably PE; the present invention has no special requirements for the specifications of the dilute acid tank 301, and the corresponding specifications of the dilute acid tank 301 can be designed according to the actual working conditions. In the present invention, the function of the dilute acid tank 301 is to dilute the acid solution in the concentrated acid solution tank 205 to accurately control the pH value of the acid solution entering the mineralization tower 302. As an embodiment of the present invention, the dilute acid tank 301 is provided with a first online pH meter 304, and the present invention has no special requirements for the installation position of the first online pH meter 304, and it can ensure that it plays a corresponding role.

[0048] In the present invention, the inlet of the mineralization tower 302 is connected to the outlet of the dilute acid tank 301; the inlet of the mineralization tower is preferably located at the bottom of the mineralization tower. The present invention has no special requirements for the size of the mineralization tower 302, and the size of the mineralization tower 302 can be designed according to the actual working conditions. In the present invention, the filler in the mineralization tower 302 preferably includes limestone and medical stone in sequence according to the direction of water flow; the height of the limestone is preferably 30 to 300 cm, more preferably 50 to 200 cm; the height of the medical stone is preferably 20 to 160 cm, more preferably 40 to 120 cm; in the present invention, the particle size of the limestone and medical stone is independently preferably 1 to 4 mm, more preferably 2 to 4 mm. In the present invention, the role of the limestone is to react with the dilute acid flowing out of the dilute acid tank 301 to generate calcium sulfate and calcium bicarbonate, and no carbon dioxide gas escapes during this process; the role of the medical stone is to partially dissolve in the reaction with the dilute acid to increase the silicate content in the water.

[0049] In the present invention, the outlet of the mineralization tower 302 is preferably provided with a second online pH meter 305, a first online hardness monitor 306 and a first online alkalinity monitor 307, and the second online pH meter 305, the first online hardness monitor 306 and the first online alkalinity monitor 307 are preferably installed at the outlet pipeline of the mineralization tower 302; the present invention has no special requirements for the installation order of the second online pH meter 305, the first online hardness monitor 306 and the first online alkalinity monitor 307. The present invention monitors the pH value of the water produced by the mineralization tower through the second online pH meter 305, monitors the hardness of the water produced by the mineralization tower through the first online hardness monitor 306, and monitors the alkalinity of the water produced by the mineralization tower through the first online alkalinity monitor 307.

[0050] In the present invention, the inlet of the mineralized water mixing tank 303 is connected with the desalinated water, the outlet of the mineralization tower 302, and the outlet of the concentrated alkali solution tank 204. The present invention has no special requirements for the specifications of the mineralized water mixing tank 303, and the corresponding specifications of the mineralized water mixing tank 303 can be designed according to the actual working conditions. In the present invention, the outlet of the mineralized water mixing tank 303 is preferably provided with a third online pH meter 308, a second online hardness monitor 309, and a second online alkalinity monitor 310, and the third online pH meter 308, the second online hardness monitor 309, and the second online alkalinity monitor 310 are preferably installed at the outlet pipe of the mineralized water mixing tank 303; the present invention has no special requirements for the installation order of the third online pH meter 308, the second online hardness monitor 309, and the second online alkalinity monitor 310. The present invention monitors the pH value of the final mineralized water by an online pH meter 308, monitors the hardness of the final mineralized water by an online hardness monitor 309, and monitors the alkalinity of the final mineralized water by an online alkalinity monitor 310. In the present invention, the function of the mineralized water mixing tank 303 is to mix the water produced by the mineralization tower, the desalinated water and the alkali solution in the concentrated alkali solution tank 204 to obtain the desalinated seawater mineralized water that meets the drinking standard.

[0051] Unless otherwise specified, the present invention has no special requirements on the inlet and outlet positions of the above components.

[0052] As an embodiment of the present invention, the device for mineralizing seawater desalination water also includes a distribution valve, and the flow rate of desalinated water is controlled by the distribution valve. In a specific embodiment of the present invention, the device for mineralizing seawater desalination water includes 6 distribution valves, which are respectively located at the distribution valve 105 at the desalinated water inlet of the sodium sulfate concentrated solution tank 101, the distribution valve 212 at the desalinated water inlet of the bipolar membrane alkali chamber 201, the distribution valve 213 at the desalinated water inlet of the bipolar membrane salt chamber 202, the distribution valve 214 at the desalinated water inlet of the bipolar membrane acid chamber 203, the distribution valve 311 at the desalinated water inlet of the dilute acid tank 301 and the distribution valve 312 at the desalinated water inlet of the mineralized water mixing tank 303.

[0053] As an embodiment of the present invention, the device for mineralizing seawater desalination water also includes a pump, through which the liquid flows smoothly and the flow rate of the liquid is controlled. In a specific embodiment of the present invention, the device for mineralizing seawater desalination water includes 5 magnetic pumps and 3 metering pumps, wherein the magnetic pumps are respectively a salt water pump 106 located between the outlet of the bipolar membrane salt chamber 202 and the inlet of the sodium sulfate concentrated solution tank 101, a concentrated alkali pump 215 located between the outlet of the bipolar membrane alkali chamber 201 and the inlet of the concentrated alkali solution tank 204, a concentrated acid pump 216 located between the outlet of the bipolar membrane acid chamber 203 and the inlet of the concentrated acid solution tank 205, and a concentrated acid pump 217 located between the outlet of the dilute acid tank 301 and the inlet of the concentrated acid solution tank 305. A dilute acid pump 313 between the inlet of the mineralization tower 302 and a mineralized water pump 314 located between the outlet of the mineralization tower 302 and the inlet of the mineralized water mixing tank 303; the metering pumps are respectively a concentrated salt metering pump 107 located between the outlet of the sodium sulfate concentrated solution tank 101 and the inlet of the bipolar membrane salt chamber 202, a concentrated acid metering pump 315 located between the outlet of the concentrated acid solution tank 205 and the inlet of the dilute acid tank 301, and a concentrated alkali metering pump 316 located between the outlet of the concentrated alkali solution tank 204 and the inlet of the mineralized water mixing tank 303.

[0054] The present invention provides a method for mineralizing seawater desalination water based on the above device, comprising the following steps:

[0055] (1) Desalinated water and sodium sulfate enter the sodium sulfate concentrated solution tank 101 for mixing to obtain a sodium sulfate solution;

[0056] (2) The sodium sulfate solution enters the bipolar membrane salt chamber 202, and the desalinated water enters the bipolar membrane salt chamber 202, the bipolar membrane alkali chamber 201 and the bipolar membrane acid chamber 203. When the mass concentration of the sodium sulfate solution in the bipolar membrane salt chamber 202 is 3-8%, bipolar membrane electrodialysis is performed to obtain a sulfuric acid solution in the bipolar membrane acid chamber 203 and a sodium hydroxide solution in the bipolar membrane alkali chamber 201. When the mass concentration of the sodium sulfate solution in the bipolar membrane salt chamber 202 is lower than 3%, the sodium sulfate solution in the bipolar membrane salt chamber 202 returns to the sodium sulfate concentrated solution tank 101.

[0057] (3) The sulfuric acid solution obtained in the bipolar membrane acid chamber 203 enters the concentrated acid solution tank 205, and the sulfuric acid solution and desalinated water in the concentrated acid solution tank 205 enter the dilute acid tank 301 for mixing to obtain a dilute sulfuric acid solution, wherein the pH value of the dilute sulfuric acid solution is 1 to 3;

[0058] (4) The dilute sulfuric acid solution enters the mineralization tower 302 for mineralization reaction to obtain mineralization tower product water;

[0059] (5) The sodium hydroxide solution enters the concentrated alkali solution tank 204, and the sodium hydroxide solution in the concentrated alkali solution tank 204, the mineralization tower water and the desalinated water enter the mineralization water mixing tank 303 for mixing to obtain seawater desalinated water mineralized water; the flow ratio of the mineralization tower water and the seawater desalinated water mineralized water is 1:1-10;

[0060] There is no time sequence requirement for the sodium hydroxide solution entering the concentrated alkali solution tank 204 in step (5) and steps (3) and (4).

[0061] The present invention allows desalinated water and sodium sulfate to enter the sodium sulfate concentrated solution tank 101 for mixing to obtain a sodium sulfate solution. The present invention has no special requirements for the water quality of the desalinated water, and seawater desalination water of any water quality is suitable for the device and method of the present invention; as a specific embodiment of the present invention, the conductivity of the desalinated water is preferably 180-260 μs / cm, the total hardness is preferably 0-5 mg / L, and the pH value is preferably 5.9-6.6. In the present invention, the sodium sulfate is preferably food-grade sodium sulfate, and the purity of the sodium sulfate is ≥99%. In the present invention, the flow rate of the desalinated water is preferably 2-10 t / h, and more preferably 2-8 t / h. In the present invention, the mixing method is preferably stirring and mixing, the stirring device is preferably a stirrer 104, and the stirring rate is preferably 50-500 r / min, and more preferably 150-300 r / min. In the present invention, the mass concentration of the sodium sulfate solution is preferably 8-14%, and more preferably 10-14%.

[0062] In the present invention, the sodium sulfate solution is preferably prepared in an intermittent manner, and the intermittent preparation method preferably comprises the following steps:

[0063] When the liquid level of the sodium sulfate solution drops to the low liquid level of the sodium sulfate concentrated solution tank 101, the distribution valve 105 is opened, and the desalinated water enters the sodium sulfate concentrated solution tank 101; when the liquid level of the sodium sulfate solution rises to the high liquid level of the sodium sulfate concentrated solution tank 101, the distribution valve 105 is closed, and the desalinated water stops entering the sodium sulfate concentrated solution tank 101; food grade sodium sulfate is added and stirred to dissolve; the low liquid level is 5-10% of the full liquid level, and the high liquid level is 90-95% of the full liquid level;

[0064] When the conductivity value of the sodium sulfate solution reaches a set range value, stop adding sodium sulfate; the set range value is the conductivity value corresponding to the sodium sulfate solution with a mass concentration of 8 to 14%, specifically 55 to 75 ms / cm.

[0065] In the present invention, the liquid level of the sodium sulfate solution is preferably measured by a liquid level meter 103 , and the conductivity of the sodium sulfate solution is measured by a conductivity meter 102 .

[0066] After obtaining the sodium sulfate solution, the present invention allows the sodium sulfate solution to enter the bipolar membrane salt chamber 202, and the desalinated water to enter the bipolar membrane salt chamber 202, the bipolar membrane alkali chamber 201 and the bipolar membrane acid chamber 203. When the mass concentration of the sodium sulfate solution in the bipolar membrane salt chamber 202 is 3-8%, bipolar membrane electrodialysis is performed to obtain a sulfuric acid solution in the bipolar membrane acid chamber 203 and a sodium hydroxide solution in the bipolar membrane alkali chamber 201; when the mass concentration of the sodium sulfate solution in the bipolar membrane salt chamber 202 is lower than 3%, the sodium sulfate solution in the bipolar membrane salt chamber 202 returns to the sodium sulfate concentrated solution tank 101. In the present invention, the flow rate of the sodium sulfate solution entering the bipolar membrane salt chamber 202 is preferably 200-600 L / h, more preferably 400-600 L / h; the flow rate of the desalinated water entering the bipolar membrane salt chamber 202 is 500-1500 L / h, the flow rate entering the bipolar membrane alkali chamber 201 is preferably 1-100 L / h, and the flow rate entering the bipolar membrane acid chamber 203 is preferably 5-400 L / h. The present invention preferably uses a concentrated salt metering pump 107 to transport the sodium sulfate solution to the bipolar membrane salt chamber 202.

[0067] The present invention preferably monitors the mass concentration of the sodium sulfate solution in the bipolar membrane salt chamber 202 by means of a conductivity meter 207. In the present invention, when the mass concentration of the sodium sulfate solution in the bipolar membrane salt chamber 202 is 3-8%, the current of the bipolar membrane electrodialysis is preferably 10-50A, more preferably 20-40A; the bipolar membrane electrodialysis is preferably carried out under stirring, the stirring device is preferably a stirrer 208, and the stirring rate is preferably 80-500rpm, more preferably 150-400rpm.

[0068] In the present invention, the mass concentration of the sulfuric acid solution in 203 is preferably 0.2-5%, and more preferably 1-3%; the present invention preferably monitors the mass concentration of the sulfuric acid solution in the bipolar membrane acid chamber 203 by an online concentrated acid concentration monitoring device 209, and maintains the stability of the sulfuric acid solution concentration in the bipolar membrane acid chamber 203 by controlling the flow of the distribution valve 214 and the concentrated acid pump 216.

[0069] In the present invention, the mass concentration of the sodium hydroxide solution in 201 is preferably 0.6-4%, more preferably 1-3%; the present invention preferably monitors the mass concentration of the sodium hydroxide solution in the bipolar membrane alkali chamber 201 by an online concentrated alkali concentration monitoring device 206, and maintains the stability of the concentration of the sodium hydroxide solution in the bipolar membrane alkali chamber 201 by controlling the flow of the distribution valve 212 and the concentrated alkali pump 215.

[0070] In the invention, when the mass concentration of the sodium sulfate solution in the bipolar membrane salt chamber 202 is lower than 3%, the sodium sulfate solution in the bipolar membrane salt chamber 202 returns to the sodium sulfate concentrated solution tank 101. In the present invention, the rate at which the sodium sulfate solution returns to the sodium sulfate concentrated solution tank 101 is preferably 0.6 to 1.5 t / h. The present invention preferably achieves the reflux of the sodium sulfate solution by the dilute brine pump 106.

[0071] After obtaining the sulfuric acid solution and the sodium hydroxide solution, the sodium hydroxide solution obtained in the bipolar membrane alkali chamber 201 enters the concentrated alkali solution tank 204, the sulfuric acid solution obtained in the bipolar membrane acid chamber 203 enters the concentrated acid solution tank 205, and the sulfuric acid solution and desalinated water in the concentrated acid solution tank 205 enter the dilute acid tank 301 to obtain the dilute sulfuric acid solution.

[0072] In the present invention, the flow rate of the sodium hydroxide solution entering the concentrated alkali solution tank 204 is preferably 1 to 100 L / h; the present invention preferably uses a concentrated alkali pump 215 to achieve the transportation of the sodium hydroxide solution. In the present invention, the flow rate of the sulfuric acid solution entering the concentrated acid solution tank 205 is preferably 5 to 400 L / h; the present invention preferably uses a concentrated acid pump 216 to achieve the transportation of the sulfuric acid solution. In the present invention, the flow rate of the sulfuric acid solution entering the dilute acid tank 301 is preferably 5 to 400 L / h, and the flow rate of the desalinated water entering the dilute acid tank 301 is preferably 0.1 to 100 t / h; the present invention preferably controls the flow rate of the sulfuric acid solution entering the dilute acid tank 301 by a concentrated acid metering pump 315, and controls the rate at which the desalinated water enters the dilute acid tank 301 by a distribution valve 311. In the present invention, the pH value of the dilute sulfuric acid solution is preferably 1 to 3, and more preferably 2 to 3. The present invention preferably monitors the pH value of the dilute sulfuric acid solution by an online pH meter 304. When the data deviates, the present invention adjusts the inflow rate of the sulfuric acid solution and the desalinated water to make the pH value meet the requirements.

[0073] After obtaining the dilute sulfuric acid solution, the present invention allows the dilute sulfuric acid solution to enter the mineralization tower 302 for mineralization reaction to obtain mineralization tower water. In the present invention, the dilute sulfuric acid solution preferably enters from the bottom of the mineralization tower. In the present invention, the flow rate of the dilute sulfuric acid solution is preferably 0.1-100 t / h. In the present invention, the residence time of the dilute sulfuric acid solution during the mineralization reaction is preferably 5-60 min, more preferably 20-40 min; the pH value of the mineralization tower water is preferably 6.3-7.1, the total alkalinity is preferably 50-600 mg / L, and the total hardness is preferably 80-2000 mg / L, more preferably 200-800 mg / L. The present invention preferably monitors the pH value, alkalinity and hardness of the mineralization tower water by an online pH meter 305, an online hardness monitor 306, and an online alkalinity monitor 307. When the data deviates, the present invention adjusts the pH value and flow rate of the dilute sulfuric acid solution to make the pH value, alkalinity and hardness of the mineralization tower water meet the requirements.

[0074] After obtaining the water produced by the mineralization tower, the present invention allows the sodium hydroxide solution in the concentrated alkali solution tank 204, the water produced by the mineralization tower and the desalinated water to enter the mineralized water mixing tank 303 for mixing to obtain the mineralized water produced by seawater desalination water; the flow ratio of the water produced by the mineralization tower and the mineralized water produced by seawater desalination water is 1:1-10. In the present invention, the flow rate of the sodium hydroxide solution is preferably 1-100 L / h, more preferably 2-80 L / h; the flow rate of the water produced by the mineralization tower is preferably 0.1-100 t / h; the flow rate of the desalinated water is preferably 0.01-1000 t / h. The present invention has no special requirements for the mixing method, and a mixing method well known to those skilled in the art can be used, such as stirring and mixing. In the present invention, the pH value of the desalinated water is preferably 7-8.5, more preferably 7.5-8; the alkalinity is preferably 50-150 mg / L, more preferably 80-120 mg / L; the hardness is preferably 50-200 mg / L, more preferably 100-150 mg / L. In the present invention, the Langelier index (LSI) of the desalinated water is preferably -0.5-0.5. The existing safety standards for drinking water are: hardness: 50-450 mg / L, alkalinity not less than 50 mg / L, LSI: -0.5-0.5, pH: 6.5-8.5. The present invention preferably monitors the pH value, alkalinity and hardness of the seawater desalination water mineralization water through an online pH meter 308, an online hardness monitor 309 and an online alkalinity monitor 310. When the data deviates, the present invention adjusts the flow rate of the sodium hydroxide solution, the mineralization tower water and the desalinated water to make the pH value, alkalinity and hardness of the seawater desalination water mineralization water meet the requirements.

[0075] The device and method for mineralizing seawater desalination water provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the protection scope of the present invention.

[0076] Example 1

[0077] The conductivity of desalinated water is 196.2 μs / cm, the pH value is 6.43, and the total hardness is 3 mg / L, which is highly corrosive water. The desalinated water is mineralized using the device of the present invention, and the parameters are shown in Table 1.

[0078] Example 2

[0079] The conductivity of desalinated water is 203.5 μs / cm, the pH value is 6.37, and the total hardness is 3 mg / L, which is highly corrosive water. The desalinated water is mineralized using the device of the present invention, and the parameters are shown in Table 1.

[0080] Example 3

[0081] The conductivity of desalinated seawater is 193.6 μs / cm, the pH value is 6.42, and the total hardness is 3 mg / L, which is highly corrosive water. The desalinated seawater is mineralized using the device of the present invention, and the parameters are shown in Table 1.

[0082] Table 1 Operating conditions for seawater desalination water mineralization in Examples 1 to 3

[0083]

[0084]

[0085]

[0086] It can be seen from Table 1 that the desalinated water mineralized water produced by the device and method of the present invention can meet the drinking standards and safe transmission and distribution requirements.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for mineralizing desalinated water, characterized in that: The device used includes a concentrated brine device (100), a bipolar membrane device (200) and a mineralization device (300) which are connected in sequence; The concentrated brine device (100) comprises a sodium sulfate concentrated solution tank (101); the sodium sulfate concentrated solution tank (101) is provided with a first desalinated water inlet, a desalinated brine inlet, a sodium sulfate feed port and a concentrated brine outlet; The bipolar membrane device (200) comprises a bipolar membrane electrodialysis chamber, a concentrated acid solution tank (205) and a concentrated alkali solution tank (204); the bipolar membrane electrodialysis chamber is divided into a bipolar membrane alkali chamber (201), a bipolar membrane salt chamber (202) and a bipolar membrane acid chamber (203) by a bipolar membrane; the bipolar membrane alkali chamber (201) is provided with a second desalinated water inlet and a concentrated alkali outlet, the concentrated alkali outlet being in communication with an inlet of the concentrated alkali solution tank (204); the bipolar membrane salt chamber (202) is provided with a third desalinated water inlet and a sodium sulfate concentrated solution inlet, the sodium sulfate concentrated solution inlet being in communication with a concentrated salt water outlet of the sodium sulfate concentrated solution tank (101), and the outlet of the bipolar membrane salt chamber (202) being in communication with the desalinated salt water inlet of the sodium sulfate concentrated solution tank (101); the bipolar membrane acid chamber (203) is provided with a fourth desalinated water inlet and a concentrated acid outlet, the concentrated acid outlet being in communication with an inlet of the concentrated acid solution tank (205); The mineralization device (300) comprises a dilute acid tank (301), a mineralization tower (302) and a mineralized water mixing tank (303); the dilute acid tank (301) is provided with a fifth desalinated water inlet, a concentrated acid solution inlet and a dilute acid outlet, the concentrated acid solution inlet being in communication with the outlet of the concentrated acid solution tank (205); the inlet of the mineralization tower (302) is in communication with the dilute acid outlet of the dilute acid tank (301); the mineralized water mixing tank (303) is provided with a sixth desalinated water inlet, a mineralization tower produced water inlet in communication with the outlet of the mineralization tower (302), and a concentrated alkali solution inlet in communication with the outlet of the concentrated alkali solution tank (204); the filler in the mineralization tower (302) comprises limestone and medical stone in order according to the liquid flow direction; the height of the limestone is 30 to 300 cm, and the height of the medical stone is 20 to 160 cm; The device for mineralizing seawater desalination water comprises five magnetic pumps and three metering pumps, wherein the metering pumps are respectively a concentrated salt metering pump (107) located between the outlet of the sodium sulfate concentrated solution tank (101) and the inlet of the bipolar membrane salt chamber (202), a concentrated acid metering pump (315) located between the outlet of the concentrated acid solution tank 205 and the inlet of the dilute acid tank (301), and a concentrated alkali metering pump (316) located between the outlet of the concentrated alkali solution tank (204) and the inlet of the mineralized water mixing tank (303); The following steps are involved: (1) Desalinated water and sodium sulfate enter a sodium sulfate concentrated solution tank (101) for mixing to obtain a sodium sulfate solution; (2) The sodium sulfate solution enters the bipolar membrane salt chamber (202), and the desalinated water enters the bipolar membrane salt chamber (202), the bipolar membrane alkali chamber (201) and the bipolar membrane acid chamber (203); the desalinated water and the sodium sulfate solution are mixed into the bipolar membrane salt chamber (202) in proportion, and the ratio of the volume of the sodium sulfate concentrated solution added to the volume of the desalinated water mixed is 1:0.1-4; when the mass concentration of the sodium sulfate solution in the bipolar membrane salt chamber (202) is 3-8%, bipolar membrane electrodialysis is performed to obtain a sulfuric acid solution in the bipolar membrane acid chamber (203), and a sodium hydroxide solution in the bipolar membrane alkali chamber (201); when the mass concentration of the sodium sulfate solution in the bipolar membrane salt chamber (202) is lower than 3%, the sodium sulfate solution in the bipolar membrane salt chamber (202) returns to the sodium sulfate concentrated solution tank (101); (3) the sulfuric acid solution obtained in the bipolar membrane acid chamber (203) enters the concentrated acid solution tank (205), and the sulfuric acid solution and desalinated water in the concentrated acid solution tank (205) enter the dilute acid tank (301) for mixing to obtain a dilute sulfuric acid solution, wherein the pH value of the dilute sulfuric acid solution is 1 to 3; (4) The dilute sulfuric acid solution enters the mineralization tower (302) for a mineralization reaction to obtain mineralization tower product water; (5) The sodium hydroxide solution enters the concentrated alkali solution tank (204), and the sodium hydroxide solution in the concentrated alkali solution tank (204), the mineralization tower produced water and the desalinated water enter the mineralization water mixing tank (303) for mixing to obtain seawater desalinated water mineralized produced water; the flow ratio of the mineralization tower produced water to the seawater desalinated water mineralized produced water is 1:1-10; the pH value of the seawater desalinated water mineralized produced water is 7-8.5, the total alkalinity is 50-150 mg / L, and the total hardness is 50-200 mg / L; There is no time sequence requirement for the sodium hydroxide solution entering the concentrated alkali solution tank (204) in step (5) and steps (3) and (4).

2. The method according to claim 1, characterized in that The sodium sulfate concentrated solution tank (101) is provided with a first conductivity meter (102), a liquid level meter (103) and a first stirrer (104); The bipolar membrane alkali chamber (201) is provided with a first concentrated alkali concentration online monitoring device (206); the bipolar membrane salt chamber (202) is provided with a second conductivity meter (207) and a second stirrer (208); and the bipolar membrane acid chamber (203) is provided with a first concentrated acid concentration online monitoring device (209); The concentrated acid solution tank (205) is provided with a second concentrated acid concentration online monitoring device (211); the concentrated alkali solution tank (204) is provided with a second concentrated alkali concentration online monitoring device (210); The diluted acid tank (301) is provided with a first online pH meter (304).

3. The method according to claim 1 or 2, characterized in that: A second online pH meter (305), a first online hardness monitor (306) and a first online alkalinity monitor (307) are provided at the outlet of the mineralization tower (302); A third online pH meter (308), a second online hardness monitor (309) and a second online alkalinity monitor (310) are provided at the outlet of the mineralized water mixing tank (303).

4. The method according to claim 1, characterized in that: The number of membrane pairs of the bipolar membrane is 5 to 80 pairs.

5. The method according to claim 1, characterized in that The particle sizes of the limestone and medical stone are independently 1-4 mm.

6. The method according to claim 1, characterized in that The mass concentration of the sodium sulfate solution in step (1) is 8-14%.

7. The method according to claim 1, characterized in that The current of the bipolar membrane electrodialysis is 10-50A; the mass concentration of the sulfuric acid solution obtained in the bipolar membrane acid chamber is 0.2-5%, and the mass concentration of the sodium hydroxide solution obtained in the bipolar membrane alkali chamber is 0.6-4%.

8. The method according to claim 1, characterized in that The residence time of the dilute sulfuric acid solution during the mineralization reaction is 5 to 60 minutes; the pH value of the water produced by the mineralization tower is 6.3 to 7.1, the total hardness is 80 to 2000 mg / L, and the total alkalinity is 50 to 600 mg / L.

Images