CN201065345Y - Device for producing ultra-pure water by desalinizing sea water - Google Patents

Abstract

The utility model provides a seawater desalination production device, which includes a water inlet unit, a pretreatment unit and a reverse osmosis unit connected in the order of water inlet, wherein: the water inlet unit is used to send the seawater to be desalinated into the pretreatment unit. treatment unit, and the seawater to be desalinated is the once-through circulating cooling water drainage of the power plant; the pretreatment unit includes a sedimentation device and a filter device connected in the order of water intake, and the upstream of the sedimentation device is connected to the water inlet unit, so The downstream of the sedimentation device is connected to the filter device; the reverse osmosis unit includes a booster device, an energy recovery device and a reverse osmosis device connected in the order of water inflow; wherein, the upstream of the booster device communicates with the pretreatment unit In the filter device, the downstream of the booster device communicates with the reverse osmosis device. The seawater desalination device of the utility model has low cost, can be popularized in a large range, is environmentally friendly, has scale benefits, and can be used for producing ultrapure water.

Description

Seawater desalination to produce ultrapure water device

technical field

The utility model relates to a separation and purification device and a method, in particular to a seawater desalination device and a method thereof.

Background technique

The problem of water shortage is very urgent and important to the sustainable development of our country. The total amount of fresh water resources in my country ranks sixth in the world, but the per capita fresh water resources are only 1/4 of the world average. Most of the water levels are less than 500 cubic meters, and Tianjin, Qingdao, Lianyungang, and Shanghai are less than 200 cubic meters, which is much lower than the internationally recognized standard of serious water shortage of 1,000 cubic meters per capita. According to estimates, after 2010, my country will enter a period of severe water shortage.

Solutions to water shortages include traditional water transfer and storage projects, water conservation, and sewage reuse, but these measures only redeploy fresh water resources regionally and temporally, and do not fundamentally increase fresh water resources. The total amount of fresh water shortage is still very serious. At present, seawater desalination technology has received more and more attention.

At present, seawater desalination is widely used with reverse osmosis, distillation and electrodialysis. Among them, reverse osmosis seawater desalination technology is a more advanced, stable and effective desalination technology, but the existing reverse osmosis seawater desalination technology has its shortcomings.

First of all, it has high requirements for pretreatment and large initial investment. For example, the SDI (pollution index) of the influent water of the reverse osmosis device must be <3. In order to ensure the quality of the influent water, it is necessary to install a huge pretreatment device, that is, a multi-media filter, an activated carbon filter and other equipment. If large-scale production is carried out, there will be a large number of equipment, a large area, complex water quality control and a low degree of system automation.

Secondly, since the water production rate of the reverse osmosis device varies greatly with the water temperature (generally, the water production rate of the reverse osmosis membrane element changes by 2.5% for every 1°C change in temperature), in order to ensure a stable water supply, it is usually necessary to configure a heater to keep the entire system at a constant temperature. The heating source is either steam or power supply, which increases the investment cost and operating cost, and the consequence of the increased cost is the rise in water price, which ultimately increases the burden on users.

Furthermore, using the reverse osmosis method to desalinate seawater, only part of the seawater becomes fresh water, while the other becomes concentrated brine, which causes environmental problems. The current development direction is a comprehensive utilization model, such as drying salt from seawater, but this approach may be restricted by land resources, salt markets and other factors.

To sum up, there is a lack of a low-cost, environmentally friendly and scale-effective seawater desalination device and method for producing ultrapure water. In order to adapt to the increasingly tense situation of fresh water resources, the increasing improvement of national environmental protection policies and the development of water treatment technology, there is an urgent need to develop devices and methods for producing ultrapure water from seawater desalination that are low in cost and can be widely promoted, environmentally friendly and have economies of scale.

Utility model content

The purpose of the utility model is to obtain a seawater desalination production device with low cost, which can be popularized in a wide range, is environmentally friendly and has scale benefits.

On the one hand, the utility model provides a seawater desalination production device, which includes a water inlet unit, a pretreatment unit and a reverse osmosis unit connected in the order of water inlet, wherein:

The water inlet unit is used to send the seawater to be desalinated into the pretreatment unit;

The pretreatment unit includes a precipitation device and a filter device connected in the order of water inflow, the upstream of the precipitation device is connected to the water inlet unit, and the downstream of the precipitation device is connected to the filter device;

The reverse osmosis unit includes a booster device and a reverse osmosis device that are connected in the order of water inflow; wherein, the upstream of the booster device communicates with the filter device in the pretreatment unit, and the downstream of the booster device communicates with the reverse osmosis unit.

In a preferred example, in the reverse osmosis unit, the booster is a high-pressure frequency conversion pump, and the reverse osmosis unit does not include a heating constant temperature device.

In a preferred example, the high-voltage variable-frequency pump is a high-voltage variable-frequency pump of duplex steel. Preferably, the pressure rating of the high-pressure frequency conversion pump is 6.2±0.2MPa, more preferably 6.2MPa.

In a preferred example, the filter device in the pretreatment unit is an ultrafiltration device.

In a preferred example, the ultrafiltration device is a submerged external pressure ultrafiltration membrane.

Preferably, the device satisfies one or more of the following conditions (i)-(iii):

(i) The precipitation device removes impurities in water so that the turbidity is 20NTU or below; the probability of <1% is 100mg/L; the total dissolved solids content is 10mg/L or below;

(ii) the filter device is used to further remove impurities in the water body, until its turbidity<0.1NTU, SDI90% time is below 2.5; 99% time<3; and/or

(iii) The desalination rate of the reverse osmosis device is >99%.

In a preferred example, the reverse osmosis device in the reverse osmosis unit includes a primary seawater reverse osmosis membrane module connected to an upstream pretreatment unit and a secondary or multi-stage freshwater membrane module downstream of the primary seawater reverse osmosis membrane module. reverse osmosis membrane components.

In a preferred example, the concentrated water side of the primary seawater reverse osmosis membrane module is equipped with an energy recovery device.

In a preferred example, the energy recovery device is a PX type energy recovery device.

In a preferred example, the two-stage or multi-stage freshwater reverse osmosis membrane module communicates with the filtered water tank provided downstream of the filter device,

Wherein the concentrated water discharged from the two-stage or multi-stage fresh water reverse osmosis membrane module is collected in the filtered water production tank, and in the filtered water production tank, the filter device produces water and the two-stage or multi-stage fresh water reverse osmosis Concentrated water discharged from the membrane modules enters the reverse osmosis device after being combined.

In a preferred example, the concentrated water side of the energy recovery device is also connected to an electrolytic preparation of sodium hypochlorite device, wherein the primary seawater reverse osmosis concentrated water after energy recovery is discharged to the electrolytic preparation of sodium hypochlorite device for electrolytic production of chlorine.

The beneficial effects of the utility model are:

1. The raw seawater is taken from the drainage of circulating cooling water, and its temperature rise is fully utilized (under normal circumstances, the temperature rise is 9°C), that is, the waste heat is used, and the raw water heating device is omitted in the entire system, thereby saving engineering investment;

2. The utility model greatly reduces the water consumption in the power generation process. my country's water resources are relatively short, especially in areas where coal reserves are relatively concentrated. However, coal-fired power generation requires a large amount of circulating cooling water, industrial cooling water and chemical make-up water. The utility model takes "saving water and reducing water consumption" as an important subject, strives to improve the reuse index of water used in power plants, adopts advanced sewage treatment technology, implements zero discharge (Z L D), and at the same time converts the obtained ultrapure water It is used to prepare industrial water and/or ultrapure water required by ultra-supercritical coal-fired power generating units.

3. The device of the present invention can be scaled up conveniently. For example, the total water production capacity of the whole set of seawater desalination system is not less than 44000m ³ per day (ie 1830m ³ per hour). The system can supply water by quality, recycle, and basically achieve zero discharge, so that the degree of environmental pollution can be minimized;

4. In a preferred embodiment, the submerged external pressure ultrafiltration membrane is used, so that the hollow fiber ultrafiltration membrane, which was mostly used for sewage treatment, is now used in the seawater desalination system, which increases the adaptability of water intake, thereby simplifying pretreatment The configuration of the reaction precipitation device and the reduction of the water control requirements of the device;

5. In a preferred embodiment, the submerged external pressure ultrafiltration membrane is adopted. The ultrafiltration membrane backwash water has no difference in water quality and influent water except for the increase in suspended impurities content, so after collection, it is recycled to the reaction sedimentation tank of the previous stage, so as to Reduce water intake and waste water discharge;

6. In a preferred embodiment, ultrafiltration, first-stage reverse osmosis, and second-stage reverse osmosis effluent all enter corresponding water tanks, which can ensure continuous water supply of the entire system even when each unit equipment fails or is overhauled;

7. In a preferred embodiment, the concentrated water discharged from the primary seawater reverse osmosis membrane module passes through the PX type energy recovery device and converts high-pressure energy into water inlet pressure, thereby reducing the water inlet flow rate of the high-pressure pump by 48%, reducing The operating power load;

8. In a preferred embodiment, the first-stage concentrated drainage after energy conversion (salt content is twice that of the original seawater) is used as the influent of the electrolytic sodium hypochlorite system, which not only improves the efficiency of the electrolytic chlorine production device, but also reduces The degree of impact of direct discharge of concentrated water on nearby sea areas;

9. In a preferred embodiment, the fresh water recovery rate of the two-stage fresh water reverse osmosis membrane module device is as high as 85%, which greatly improves the water production efficiency. At the same time, all the concentrated water discharged is recycled to the ultrafiltration water production tank without any external discharge .

Description of drawings

Fig. 1 is a schematic diagram of an embodiment of the present invention.

Fig. 2 is a schematic diagram of the dosing unit of the implementation device in Fig. 1 . Figures 2.1 to 2.3 show the composition of the dosing unit in each link.

Detailed ways

After extensive and in-depth research, the utility model uses the original seawater as the source of circulating cooling water by improving the preparation process, and uses the drained water after the thermal system circulation as the inflow of the seawater desalination to produce ultra-pure water, thereby eliminating the need for The heater before the reverse osmosis unit is installed. Completed the utility model on this basis. In the preferred embodiment of the present utility model, specific technical means (such as specific filter device, booster device, recovery device) are also used to obtain seawater desalination production with low cost, environmental protection and scale benefit Ultrapure water apparatus and method.

As used in this article, the definition of "circulating cooling water" in the present invention is: use natural water body water source under normal temperature to cool the steam in the thermal system, cool it to become condensed water, and then return to the steam system to circulate . For example, the once-through circulating cooling water drainage of the power plant is adopted, and its purpose is to make full use of the waste heat of the drainage. Usually, the temperature of the once-through circulating cooling water drainage of the power plant is raised by about 9±2°C on the basis of normal temperature seawater, usually about 9°C.

As used herein, the definition of "turbidity" in the present invention adopts the commonly used meaning in the technical field of the present invention. The turbidity measuring method of the present utility model adopts the mensuration (formazin turbidity) of national standard GB12151-198 boiler water and cooling water analysis method turbidity.

As used herein, the "SDI" mentioned in the present invention is pollution index. It is commonly used to characterize the content of particles, colloids, and other objects in water that can clog various water purification equipment. The assay method of SDI of the present utility model is according to common standard in this area, such as ASTM 4189-95 method. The pollution index of the seawater obtained by the filter device of the utility model is, for example, SDI 90% of the time below 2.5; 99% of the time <3.

As used herein, the "security filter device" in the present invention refers to a filter device used to protect reverse osmosis membrane modules. Specifically, for example, particulate matter with a particle size >5 μm is prevented from passing through. The installation position of the "safety filter device" of the present invention is usually upstream of the reverse osmosis device, specifically, for example, the downstream of the booster device communicates with the security filter device, and the downstream of the security filter device communicates with the reverse osmosis device.

As used herein, the "salination rejection rate" of the present invention is based on the salt content of influent water (such as seawater to be desalinated, including raw seawater).

As used herein, the "boosting device" of the present invention refers to a device for increasing the water inlet pressure of the reverse osmosis device of the present invention. Specifically, for example, it is used to increase the water inlet pressure of a seawater reverse osmosis membrane module.

As used herein, "pure water" and "fresh water" in the present invention can be used interchangeably.

Each technical feature of the utility model is described in detail below.

Inlet unit

The water inlet unit of the utility model is used for sending the seawater to be desalinated into the pretreatment unit, and the seawater to be desalinated is drained by the direct current circulating cooling water of the power plant. The structure of the water inlet unit is not particularly limited. Specifically, for example, the water inlet unit communicates with the circulating cooling water drainage channel, so the influent water of the entire seawater desalination production device is seawater from the circulating cooling water drainage.

In the prior art, it is usually necessary to configure a heater to keep the whole system at a constant temperature, thereby increasing the cost. However, the water intake of the utility model is taken from the drainage of circulating cooling water, and its temperature rise is fully utilized (under normal circumstances, the temperature rise is 9°C), that is, waste heat is used, and seawater heating devices are omitted in the entire system, thereby saving engineering investment. .

preprocessing unit

The pretreatment unit of the present utility model includes a sedimentation device and a filter device connected in the order of water inflow, the upstream of the sedimentation device is connected to the water inlet unit, and the downstream of the sedimentation device is connected to the filter device.

Preferably, the device meets one or more of the following conditions (i)-(iii): (i) the precipitation device removes impurities in water so that the turbidity is 20NTU or below; <1% probability 100mg/L; the total dissolved solids content is 10mg/L or less; (ii) the filter device is used to further remove impurities in the water until the turbidity < 0.1NTU, and the SDI 90% time is below 2.5 99% time<3; (iii) the desalination rate of the reverse osmosis device>99%. The "<1% probability", "total dissolved solids content" and the like are commonly used terms in the field, and adopt the meanings stated in national standards.

For example, the pretreatment unit of the present utility model is used to remove impurities in water until its turbidity is 20NTU or below (normal conditions), and the total dissolved solid content is 10mg/L or below, and the filter device is used to further remove > For particulate impurities with a particle size of 5 μm, until the turbidity <0.1 NTU, the SDI (pollution index) is below 2.5 for 90% of the time; <3 for 99% of the time.

Precipitation device

The precipitation device of the present invention is a device for adding chemicals to remove solid substances and/or oxidative substances (such as CaCO ₃ , CaSO ₄ , SrSO ₄ , CaF ₂ , SiO ₂ , iron, aluminum oxides, etc.) Prevent solid substances from depositing on the membrane surface of the reverse osmosis membrane module of the subsequent unit or oxidative substances from oxidative damage to the membrane.

The precipitation device of the present invention is not particularly limited, for example, it includes one or more reaction sedimentation tanks.

filter

The filter device of the utility model is a device for removing colloidal substances, suspended solid particles, and organic matter in seawater generated in the sedimentation device, so as to prevent colloidal matter, solid particles or organic matter from fouling the reverse osmosis membrane module of the subsequent unit.

The filter device of the present invention can adopt one-stage or multi-stage media filter, activated carbon filter or filter device commonly used in the field.

In a preferred example of the utility model, the filtering part adopts an ultrafiltration device. More preferably, a submerged external pressure ultrafiltration membrane is used. While adopting the submerged external pressure ultrafiltration membrane, the ultrafiltration security filter is omitted.

The prior art usually uses an internal pressure ultrafiltration membrane, but the utility model adopts the submerged external pressure ultrafiltration membrane. The advantage is that the membrane has a relatively large flux and a high water production per unit area, thereby reducing the number of equipment , to save space. The submerged external pressure ultrafiltration membrane does not require pressure for water intake, as long as the intake water can flow into the ultrafiltration membrane pool.

At the same time, the submerged external pressure ultrafiltration membrane makes the hollow fiber (high-strength polyvinylidene fluoride, PVDF for short) ultrafiltration membrane that was originally used for sewage treatment now used in seawater desalination systems, increasing the water intake The adaptability of the system can simplify the configuration of the pretreatment part of the reaction sedimentation device and the control requirements of the system effluent. At the same time, the ultrafiltration security filter is also omitted. In addition, the submerged external pressure ultrafiltration membrane is easy to backwash after fouling, and can be cleaned with chemicals after serious pollution. The membrane material is resistant to alternating cleaning of sodium hypochlorite, hydrochloric acid, citric acid and other chemicals.

In a preferred example, an ultrafiltration product water box is arranged downstream of the ultrafiltration device.

reverse osmosis unit

The reverse osmosis unit of the present utility model includes a booster device and a reverse osmosis device connected in the order of water intake; wherein, the upstream of the booster device communicates with the filter device in the pretreatment unit, and the downstream of the booster device communicates with reverse osmosis device.

Booster

Preferably, in the reverse osmosis unit, the booster device is a high-pressure frequency conversion pump, and the reverse osmosis unit does not include a heating constant temperature device; preferably, the high-pressure frequency conversion pump is a dual-phase steel high-voltage frequency conversion pump .

In a preferred example, the booster device is used to increase the water pressure entering the primary seawater reverse osmosis device to 6.2±1MPa, preferably 6.2±0.2MPa, most preferably 6.2MPa.

In a preferred example of the utility model, since the seawater reverse osmosis unit adopts a high-pressure variable-frequency pump, the operating pressure is about 6.2 MPa. The high-pressure variable-frequency pump makes the water production rate and desalination rate of reverse osmosis more stable, and the general control variation range is between Between 85% and 100%. In this way, the drainage of raw seawater from circulating cooling water can make full use of its temperature rise (under normal circumstances, the temperature rise is 9°C), that is, waste heat can be used, and at the same time, the raw water heating device is omitted in the whole system, thereby saving engineering investment.

reverse osmosis device

The reverse osmosis device includes a first-stage seawater reverse osmosis membrane module connected to an upstream pretreatment unit and a second-stage or multi-stage freshwater reverse osmosis membrane module arranged downstream of the first-stage seawater reverse osmosis membrane module.

Preferably, the concentrated water side of the primary seawater reverse osmosis membrane module is equipped with an energy recovery device. The energy recovery device of the present utility model can adopt various types of energy recovery devices such as PX, HTC, HPB, WEER, PES, VARI-RO, Clark Pump, etc., preferably a PX type energy recovery device. Specifically, for example, the diverted seawater is in contact with the high-pressure concentrated water discharged from the outlet of the reverse osmosis membrane unit at a similar flow rate, and the pressure energy in the high-pressure concentrated water is directly transferred to the diverted seawater; then, the diverted seawater carries the recovered energy through a liter After the pressurized device is pressurized, it joins the part of the seawater that passes through the high-pressure pump and then enters the reverse osmosis unit.

Preferably, the concentrated water discharged from the two-stage or multi-stage fresh water reverse osmosis membrane module is collected through a filtered product water tank arranged downstream of the filter device, wherein in the filtered product water tank, the filter device produces water and the The concentrated water discharged from the two-stage or multi-stage freshwater reverse osmosis membrane module enters the reverse osmosis device after being combined.

More preferably, the energy recovery device is also connected to an electrolytic preparation of sodium hypochlorite device, wherein the primary seawater reverse osmosis concentrated water after energy recovery is discharged to the electrolytic preparation of sodium hypochlorite device for electrolytic production of chlorine.

The reverse osmosis device may be a one-stage or multi-stage reverse osmosis device. In a preferred example, the reverse osmosis device is a two-stage reverse osmosis device. For example but not limited to, it includes a primary seawater reverse osmosis membrane module connected upstream to a pretreatment unit and a secondary freshwater reverse osmosis membrane module downstream of the primary seawater reverse osmosis membrane module. Preferably, an energy recovery device is connected between the pretreatment unit and the first-stage seawater reverse osmosis membrane module, so that the concentrated water discharged from the first-stage seawater reverse osmosis membrane module is discharged after passing through the energy recovery device, Thereby improving the efficiency of the whole set of one-stage reverse osmosis device. Or, the downstream of the above-mentioned filter device is provided with an ultrafiltration water production tank, and the concentrated water discharged from the two-stage fresh water reverse osmosis membrane module is communicated with the ultrafiltration water production tank, so that the concentrated water of the two-stage fresh water reverse osmosis membrane module returns to the The ultrafiltration water production tank is reused.

In a preferred example, the first-stage reverse osmosis concentrated water can also be used in a device for preparing sodium hypochlorite by electrolysis. Wherein the energy-recovered concentrated water discharged from the energy recovery device is sent to the electrolytic preparation of sodium hypochlorite device for electrolytic production of chlorine.

In a preferred example, the ultrafiltration device is a submerged external pressure ultrafiltration membrane, and the security filter at the front end can be omitted.

In a preferred embodiment of the present utility model, the energy recovery device of the present utility model allows the concentrated water discharged from the first-stage seawater reverse osmosis membrane module with a pressure >5.0 MPa to enter the energy recovery device, thereby reducing the output of the high-pressure frequency conversion pump, The flow rate of the high-pressure variable-frequency pump is only 48% of the total water intake capacity of the first-stage seawater reverse osmosis membrane module, so that the service life of the high-pressure variable-frequency pump is longer.

Below in conjunction with specific embodiment, further illustrate the utility model. It should be understood that these embodiments are only used to illustrate the present utility model and are not intended to limit the scope of the present utility model.

Example 1

Figure 1 is a schematic diagram of the composition of the seawater desalination system. This process can be used in systems with a water production capacity of 1000t/h and above. Below in conjunction with accompanying drawing, the utility model is made a general description.

The seawater desalination production device of the utility model comprises a water inlet unit 1 (circulating water drainage siphon well), a pretreatment unit 2 and a reverse osmosis unit 3 connected in sequence.

The water inlet unit 1 is used to send the seawater to be desalinated into the pretreatment unit, and the seawater to be desalinated is the once-through circulating cooling water drainage of the power plant. The water inlet unit 1 adopts.

When in use, in the water inlet unit 1, the raw seawater is discharged into the siphon well of the water inlet unit 1 after heat exchange (at this time, the temperature rise is about 9°C), and the raw seawater is sent to the sedimentation of the pretreatment unit 2 through the delivery pump. Device 21 (reaction sedimentation tank).

The pretreatment unit 2 includes a sedimentation device 21 and a filter device 22 connected in the order of water inflow, the upstream of the sedimentation device 21 is connected to the water inlet unit 1 , and the downstream of the sedimentation device 21 is connected to the filter device 22 . The precipitation device 21 adopts a reaction sedimentation tank; the filter device 22 adopts a submerged external pressure ultrafiltration membrane. Downstream of the filtering device 22, a filtered water production tank 23 (ie, an ultrafiltration water production tank) is provided via a permeate pump 24 .

During use, in the pretreatment unit 2, a coagulant and a coagulant are added to the sedimentation device 21 (reaction sedimentation tank) to remove suspended particulate impurities in the raw water. The effluent from the reaction sedimentation tank 21 flows to the filtration device 22 (ultrafiltration membrane pool) by gravity, and the raw water passes through the ultrafiltration membrane 22 under the suction of the permeate pump 24 and then enters the produced water tank 23 . The ultrafiltration membrane 22 automatically performs backwashing when the pressure difference between the inlet and outlet water is greater than the set value. When the fouling is serious and it is difficult to restore the membrane flux through the backwashing process, the ultrafiltration membrane 22 can be restored to normal operation by chemical cleaning. . What enters and stores in the produced water tank 23 is pure seawater.

The reverse osmosis unit 3 includes a pressurization device 31 and a reverse osmosis device 32 connected in sequence; wherein, the upstream of the pressurization device 31 communicates with the filter device 21 in the pretreatment unit 2, and the booster The downstream of the device 31 communicates with a reverse osmosis device 32 . In the reverse osmosis unit 3, no heating and constant temperature device is required. The booster 31 is a booster pump, usually a high-voltage frequency conversion pump, preferably a duplex steel high-voltage frequency conversion pump.

The downstream of the booster pump 31 is connected to the security filter 325 , wherein the water output from the ultrafiltration water production tank 23 enters the security filter 325 through the booster pump 31 .

The reverse osmosis device 32 includes a primary seawater reverse osmosis membrane module 321 connected to the upstream pretreatment unit 2 and a secondary freshwater reverse osmosis membrane module 322 arranged downstream of the primary seawater reverse osmosis membrane module 321 . The secondary fresh water reverse osmosis membrane assembly 322 communicates with the filtered water production tank 23 (or referred to as an ultrafiltration water production tank) disposed downstream of the filtering device 22 . Wherein the concentrated water discharged from the secondary fresh water reverse osmosis membrane module 322 is collected in the filter product water tank 23, and in the filter product water tank 23, the filter device 22 product water and the secondary fresh water reverse osmosis membrane module The concentrated water discharged from 322 enters the reverse osmosis device 3 after being combined.

A first-stage seawater reverse osmosis high-pressure pump 326 is arranged between the security filter 325 and the first-stage seawater reverse osmosis membrane module 321 . The concentrated water side of the primary seawater reverse osmosis membrane module 321 is equipped with an energy recovery device 323, and the energy recovery device 323 is a PX type energy recovery device. The concentrated water side of the energy recovery device 323 is also connected to the electrolytically prepared sodium hypochlorite device 324 (that is, the electrolytic seawater chlorine production device), wherein the primary seawater reverse osmosis concentrated water after energy recovery is discharged to the electrolytic seawater chlorine production device 324 to produce chlorine by electrolysis. The energy recovery device 323 is connected in parallel with a primary seawater reverse osmosis high pressure pump 326 .

When in use, seawater enters the reverse osmosis unit 3 for the reverse osmosis desalination step, that is, enters the desalination unit. The water output from the ultrafiltration water production tank 23 enters the security filter 325 through the booster pump 31 to remove particulate matter with a particle size > 5 μm, so as to ensure that the reverse osmosis membrane is not scratched. Add antiscalant and reducing agent respectively before and after the security filter 325, and then connect a first-stage seawater reverse osmosis high-pressure pump 326 in series. MPa (depending on the salinity of the original seawater). The first-stage high-pressure pump 326 pumps the desalted water into the seawater reverse osmosis membrane module 321, the recovery rate is 45%, and the desalination rate is 99%. Since the pH value of the product water treated by the reverse osmosis membrane is generally around 6, a certain amount of lye (42% industrial soda ash) is added at this time to adjust the pH value of the industrial water to further meet the water quality requirements of industrial water. The concentrated water discharged from the seawater reverse osmosis membrane module 321 still has relatively high pressure. For this reason, a group of energy recovery devices 323 are set up to convert the concentrated water into power by using the pressure discharged from the concentrated water to push 52% of the total flow into the reverse osmosis membrane module. The amount of water enters the booster pump 330. At this time, the lift of the booster pump 330 only needs to overcome the pressure loss of the seawater reverse osmosis membrane module. The concentrated water discharged after passing through the energy recovery device 323 is reused and recycled to the chlorine production system (electrolytic seawater chlorine production device 324 ) as raw water for electrolytic seawater chlorine production.

Most of the industrial water stored in the primary industrial water tank 327 is used in various process systems, such as motor shaft seal cooling water, fire sprinkler water, air conditioning system cooling water, domestic water (except drinking water) and so on. At the same time, part of the first-level industrial water directly enters the second-level fresh water high-pressure pump 328 and passes through the second-level fresh water reverse osmosis membrane module 322, with a recovery rate of 85% and a desalination rate of 98%. Concentrated water discharged from the secondary reverse osmosis membrane module 322 is recycled to the ultrafiltration water product tank 23 .

No matter how closely the inlet water quality of the reverse osmosis membrane module is controlled, the phenomenon of membrane fouling is still unavoidable. For this reason, a reverse osmosis membrane chemical cleaning unit is set up to perform chemical cleaning on the membrane stack on a regular basis to restore the flux and desalination of the membrane. Rate. In this embodiment, the primary and secondary reverse osmosis membrane modules share a set of chemical cleaning devices to improve the utilization rate of the devices (not shown in the figure).

As shown in Figures 2.1 to 2.3 in Figure 2, in each specific implementation mode, there are multiple links in the above-mentioned process for dosing treatment to adjust the water quality. For this purpose, a group of combined dosing devices is set up, and dosing boxes, dosing pumps, control cabinets, etc. for various medicines are installed. Then use the respective dosing pipeline to inject the medicine into the required part. The medicines and dosage of the medicine adding unit can be selected according to the prior art. As shown in Figure 2.1, the coagulant dosing unit 2b and coagulant aid dosing unit 2a are connected in series on the reaction sedimentation tank 21; Agent dosing unit 325b; as shown in Figure 2.3, NaOH dosing unit 321a is set downstream of primary seawater reverse osmosis membrane 321.

The entire desalination system has a high degree of automation, each unit has a program control system, the production volume and water quality temperature are constant, even if the water volume fluctuates, it can be adjusted and buffered through the water tanks of each node; the water quality fluctuations can bypass the units that have problems , so as not to affect the subsequent process. The final water production and water quality control are continuous and stable.

Taking the water production rate of 1000t/h (ie 24000t/d) as an example, the entire seawater desalination plant occupies an area of about 80×65 meters, of which the structure part occupies an area of 2400m ² , where all equipment and devices except various water tanks are placed. Including process, electrical, control, etc. All kinds of water tanks can be arranged in the open air.

During use, the device of the present utility model adopts the method that comprises the following steps to carry out seawater desalination preparation, and it comprises the following steps:

(A) Pretreating the seawater to be desalinated from the once-through circulating cooling water drainage, the pretreatment includes sedimentation and filtration steps to obtain pretreated seawater with a pollution index <2.5;

(B) performing reverse osmosis on the pretreated seawater obtained in step (A) to obtain fresh water with the required water standard; and obtain corresponding concentrated seawater at the same time.

The water production capacity of the pretreatment in step (A) is 86400±2000 tons/day, and the water production capacity of the reverse osmosis device in step (B) is 44000±2000 tons/day.

The reverse osmosis step in the step (B) includes a pre-pressurization step, which adopts a high-voltage frequency conversion method, and the constant temperature heating step is omitted in the reverse osmosis step.

The reverse osmosis step of described step (B) comprises the following steps: (1) one-level reverse osmosis, obtains the first-level fresh water that satisfies the industrial water standard; Obtains corresponding one-level concentrated seawater simultaneously; The utility model " first-level concentrated seawater "Usually its salt content is about twice that of the original seawater. For example, 1.5 to 2.5 times.

(II) performing reverse osmosis on the primary fresh water produced in step (I) to obtain secondary or multi-stage fresh water; and simultaneously obtain corresponding secondary or multi-stage concentrated seawater.

Recycling the concentrated seawater at all levels obtained by reverse osmosis, so that all the concentrated seawater is not discharged outside, it includes the following steps: (s1) performing chlorine production by electrolysis after recycling the first-level concentrated seawater obtained in the step (B); (s2) recovering the secondary or multi-stage concentrated seawater in the step (C), merging with the seawater to be desalinated in the step (A), and performing pretreatment together.

The seawater desalination production device of the utility model can prepare pure water for various purposes as required. The pure water is prepared as required, for example in accordance with GB12151-1989 (analysis method of boiler water and cooling water-determination of turbidity (formazin turbidity)) or in accordance with GB5749-85 (sanitary standard for drinking water) standard Fresh water, or pure water that meets industrial pure water standards. Generally, "pure water meeting industrial pure water standards" means that the conductivity of the obtained pure water is between 10 and 15 μs/cm.

The seawater desalination production device of the utility model can also be used to prepare industrial water and ultrapure water required by ultra-supercritical coal-fired generating sets.

The fresh water recovery rate of the utility model is as high as 85%, which greatly improves the water production efficiency, and at the same time, all the concentrated water discharged is recovered to the ultrafiltration water production tank without any external discharge.

All documents mentioned in this application are incorporated by reference in this application as if each were individually incorporated by reference. In addition, it should be understood that after reading the above teaching content of the utility model, those skilled in the art can make various changes or modifications to the utility model, and these equivalent forms also fall within the scope defined by the appended claims of the application.

Claims (10)

1. a preparing ultrapure water by sea water desalination device is characterized in that, comprises the water inlet unit (1), pretreatment unit (2) and the reverse osmosis units (3) that are linked in sequence by water inlet, wherein:

Described water inlet unit (1) is used for seawater to be diluted is sent into described pretreatment unit (2);

Described pretreatment unit (2) comprises settler (21), the filtration unit (22) that is linked in sequence according to water inlet, and the upstream of described settler (21) connects described water inlet unit (1), and the downstream of described settler (21) connects described filtration unit (22);

Described reverse osmosis units (3) comprises increasing apparatus (31) and the reverse osmosis unit (32) that is linked in sequence according to water inlet; Wherein, the upstream of described increasing apparatus (31) is communicated with the filtration unit (22) in the described pretreatment unit (2), and the downstream of described increasing apparatus (31) is communicated with described reverse osmosis unit (32).

2. device as claimed in claim 1 is characterized in that, in the described reverse osmosis units (3), described increasing apparatus (31) is the high-pressure frequency-conversion pump, and does not comprise heating constant-temperature equipment in the described reverse osmosis units (3).

3. device as claimed in claim 2 is characterized in that, described high-pressure frequency-conversion pump is a dual phase steel high-pressure frequency-conversion pump.

4. device as claimed in claim 1 is characterized in that, the filtration unit (22) in the described pretreatment unit (2) is a ultra-filtration equipment.

5. device as claimed in claim 4 is characterized in that, described ultra-filtration equipment is an immersion external pressure ultra-filtration membrane.

6. device as claimed in claim 1, it is characterized in that the reverse osmosis unit (32) in the described reverse osmosis units (3) comprises one-level seawater reverse osmosis membrane assembly (321) that is communicated with upstream pretreatment unit (2) and secondary or the multistage fresh water reverse osmosis membrane assembly (322) that is located at described one-level seawater reverse osmosis membrane assembly (321) downstream.

7. device as claimed in claim 6 is characterized in that, the dense water side of described one-level seawater reverse osmosis membrane assembly (321) is equipped with energy recycle device (323).

8. device as claimed in claim 7 is characterized in that, described energy recycle device (323) is a PX type energy recycle device.

9. device as claimed in claim 6 is characterized in that,

Described secondary or multistage fresh water reverse osmosis membrane assembly (322) are communicated with the filtration that is provided with in described filtration unit (22) downstream and produce water tank (23),

The dense water that wherein said secondary or multistage fresh water reverse osmosis membrane assembly (322) are discharged is collected by producing water tank (23) in filtration, and described filtration is produced in the water tank (23), enters described reverse osmosis unit (3) after the dense hydration also that described filtration unit (22) product water and described secondary or multistage fresh water reverse osmosis membrane assembly (322) are discharged.

10. device as claimed in claim 1, it is characterized in that, the dense water side of described energy recycle device (323) also connects electrolytic preparation clorox device (324), and wherein the saturating concentrated water discharge of one-level seawater reverse osmosis after energy recovery arrives described electrolytic preparation clorox device (324) for preparing chlorine by electrolysis.

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