Original water tank:
Function: Overcoming the instability of the water supply of the pipe network, ensuring the stable and continuous water supply of the whole system; at the same time, it also provides a guarantee for the long-term performance of each equipment.
Control: Formulate the liquid level automatic control system. When the water pressure is in the low position, the original water valve is automatically opened. When the water level is high, the original water valve is automatically closed.
Original water pump:
Function: Provide the necessary working pressure selection for the pretreatment equipment: according to the design pressure drop of the pretreatment equipment (the pressure drop of each filter equipment is 0.5Mpa), and the pressure before the high pressure pump can not be less than 0.5 kg/cm 2 Work pressure.
Control: The whole system adopts PLC controller for the whole system, which can be operated manually and automatically.
The diaphragm is used to adjust the pressure and water intake (manual operation).
Motor characteristics:
Sealing level: IP54
Insulation class: F
Standard voltage: 3 × 380-415V; 50HZ
Motor speed: 2900 rev / min <br> <br> mechanical filter:
The raw water contains fine particles of dust, humus, starch, cellulose, bacteria, algae and other microorganisms. These impurities form colloidal particles with water in the sol state, and exhibit sedimentation stability and polymerization stability due to Brownian motion and electrostatic repulsion. Sexuality, usually can not be removed by the method of gravity natural sedimentation. Generally, the suspended matter contained in the suspended matter in the water can not be removed by sedimentation or the like, and the mechanical impurities can remove the water by mechanical filtration, thereby reducing the turbidity of the water. To improve clarity. The system is fully automatic operation, the valve is a stainless steel ball valve, enters the manual cleaning state, that is, the processes of backwashing, washing, staining, decontamination, and emptying are all done manually. When entering the normal working state, the water is discharged. Inlet water, manual opening, the system uses manual control.
Activated carbon filter:
In addition to requiring SDI less than or equal to 5, the reverse osmosis water has another influent index of residual chlorine of less than 0.1 mg/L. The carbon filter mainly has two functions: 1. Adsorption of some organic substances in water, the adsorption rate is about 60%; 2. Residual chlorine in the adsorption water. Inorganic colloids, organic colloids, and soluble organic polymer impurities and residual chlorine having a particle size of about 10-20 angstroms are difficult to remove in a sand filter. In order to further purify the raw water to achieve the reverse osmosis water inflow index, a carbon filter was designed in the process. The active carbon can be used to adsorb active materials with a particle size of several tens of angstroms due to the large average pore size of the structure. 20-50 angstroms of micropores and grain gaps, this structural feature of activated carbon, its surface adsorption area can reach 500-2000 square meters / gram, because the general organic molecules are slightly less than 20-50 angstroms, so activated carbon Has a strong adsorption of organic matter. In addition, active carbon has a strong deoxidation property, and residual chlorine reacts with carbon to form carbon dioxide and -1 valent chloride ions, so that only a small amount of carbon is lost, so dechlorination of activated carbon can be used for a relatively long period of time.
Activated carbon not only has the above functions, but also removes odors and pigments in water and improves the clarity of water. After using activated carbon for a period of time, its adsorption capacity decreases and needs to be regenerated or replaced. Therefore, after the raw water passes through the carbon filter, the water quality can be greatly improved, and the pollution to the reverse osmosis membrane can be reduced. After the treatment, the water quality can reach the requirement of the reverse osmosis water quality (residual chlorine <0.1 mg/L), in order to prevent higher concentration. The chloride ions cause long corrosion on the stainless steel surface, so the inner wall of the carbon filter is treated with anti-corrosion treatment to improve the service life of the equipment. The activated carbon filter operates through a carbon bed. The activated carbon particles constituting the carbon bed have a large number of micropores and a large specific surface area, and have a strong physical adsorption capacity. In addition, there are some oxygen-containing energy groups on the non-crystalline part of the activated carbon surface, so that the organic pollutants in the water passing through the carbon bed are effectively adsorbed by the activated carbon. The filter is a relatively common water treatment equipment, which is used as a pretreatment equipment in the water treatment desalination system, which can effectively ensure the service life of the latter equipment, improve the effluent water quality, prevent pollution, and especially prevent the reverse osmosis membrane. Poisoning of free residual oxygen such as ion exchange resin. Activated carbon filter has obvious removal ability for organic matter, colloid and pigment in water. Activated carbon filters are mainly used to remove organic matter, odor, color, heavy metal ions, residual chlorine (CL2), etc. in water. As a pretreatment of reverse osmosis, electrodialysis, and ion exchangers. Activated carbon can provide a good protection for these devices. The activated carbon adsorption filter is a pressure type filtering device which uses activated carbon as a filter material, and can be softened with ion exchange, and the desalination equipment is connected in series to form a treatment system. The activated carbon adsorption filter not only has the function of filtering the suspended matter by the ordinary mechanical filter, but also removes impurities such as free residual chlorine, odor, color and organic matter which are difficult to remove by conventional means. The system is fully automatic operation, the valve is a stainless steel ball valve, enters the manual cleaning state, that is, the processes of backwashing, washing, staining, decontamination, and emptying are all done manually. When entering the normal working state, the water is discharged. Inlet water, manual opening, the system uses manual control.
First stage multistage pump:
Fresh water is obtained by applying a certain pressure on the concentrated water side of the reverse osmosis membrane to achieve the penetration of the solution from the high concentration to the low concentration side. Here, the multistage pump functions to increase the water pressure. The Danish Grundfos multistage pump used by our company has a thermal protection function, and when the temperature rises, the multistage pump automatically stops working. In addition, the multi-stage pump uses high and low pressure protection switches on the water inlet and outlet side. When the inlet pressure is low or no water, the multistage pump automatically shuts down. When the membrane concentrated water side pressure is high, the multistage pump automatically shuts down, thus Multi-stage pumps and membranes play an important role in protecting the system from normal operation.
Precision filter:
The precision filter, also known as the security filter, uses a 5 micron PP fuse core. This filter has strong hydrophilicity, good filtering effect and long service life. The precision filter is a process after the raw water enters the reverse osmosis, and its function is to prevent some particles from being brought into the reverse osmosis to ensure the reverse osmosis water quality to prolong the service life of reverse osmosis.
Secondary multistage pump:
Reverse osmosis is obtained by applying a certain pressure on the concentrated water side of the RO membrane to achieve the penetration of the solution from a high concentration to a low concentration side. Here, the multistage pump functions to increase the water pressure. The multi-stage pump of the Danish Grundfos pump used by our company has thermal protection function. When the temperature rises, the multi-stage pump automatically stops working. In addition, the low-pressure protection switch is used on the inlet side of the multi-stage pump. When the inlet pressure is low or no water, the multi-stage pump is automatically closed to protect it.
Reverse osmosis host:
1. Permeation and osmotic pressure penetration are common in nature. For example, when a cucumber is placed in salt water, the process of changing the water molecules in the cucumber into the saline solution due to water loss is the infiltration process. If a water tank is used to penetrate a pool, the water pool is divided into two parts, and pure water and brine are injected into the same height on both sides of the diaphragm. After a while, it can be found that the pure water level is lowered, and the liquid level of the brine is raised. The phenomenon in which water molecules migrate through the membrane into the brine is called infiltration. The rise in salt water is not endless, reaching a point of equilibrium at a certain height. At this time, the pressure represented by the liquid level difference at both ends of the diaphragm is called the osmotic pressure. The magnitude of the osmotic pressure is directly related to the concentration of the brine.
2. Reverse osmosis phenomenon and reverse osmosis water purification technology After the above device reaches equilibrium, if a certain pressure is applied to the liquid surface of the brine end, at this time, the water molecules will migrate from the brine end to the pure water end. The phenomenon that the liquid molecules migrate from a dilute solution to a concentrated solution under pressure is called a reverse osmosis phenomenon. If brine is added to one end of the above facility and a pressure above the osmotic pressure of the brine is applied at that end, we can get pure water at the other end. This is the principle of reverse osmosis water purification. There are two key points in the production of pure water by reverse osmosis facilities. One is a selective membrane, which we call a semi-permeable membrane, and the other is a certain pressure. Simply put, the reverse osmosis semipermeable membrane has a large number of pores, the size of which is equivalent to the size of water molecules. Since bacteria, viruses, most organic pollutants and hydrated ions are much larger than water molecules, they cannot be penetrated. The reverse osmosis semipermeable membrane is separated from the aqueous phase that passes through the reverse osmosis membrane. Among the many kinds of impurities in water, the soluble salts are difficult to remove. Therefore, the water purification effect of reverse osmosis is often determined according to the level of salt removal. The level of reverse osmosis desalination is mainly determined by the selectivity of the reverse osmosis semipermeable membrane. At present, the selectivity of the highly selective reverse osmosis membrane element can be as high as 99.7%.
3. Reverse osmosis and ion exchange comparison reverse osmosis advantages:
* Continuous operation, product water quality is stable * No need to use acid and alkali regeneration * No downtime due to regeneration * Save backwash and cleaning water * Produce ultrapure water in high yield (up to 95% yield)
* No reclaimed sewage, no need for sewage treatment facilities * No need for acid and alkali reserves and acid-base dilution transport facilities * Reduce the floor area of ​​the workshop * Safe and reliable use, avoid workers' exposure to acid and alkali * Reduce operating and maintenance costs * Simple installation and low installation cost The weakness of reverse osmosis and the solution The system salt removal rate of reverse osmosis equipment is generally 98-99%. Such salt removal rate can meet the requirements in most cases. In the electronics industry, ultra-high pressure boiler feed water, individual pharmaceutical industries may have higher requirements for pure water. At this point, the single-stage reverse osmosis equipment cannot meet the requirements. The system uses reverse osmosis and ion exchange to reduce the plant floor area and reduce low operating costs.
The main part of the first-stage reverse osmosis main engine is the RO membrane component. The company selected the low-pressure polyamide composite membrane (BW30-400) produced by American Dow Company, which not only has low working pressure, strong anti-pollution ability, but also has higher rated water production. Large, high salt rejection rate, and a large use margin, to ensure that the designed water production is still achieved after three years of use. The production temperature of reverse osmosis is 20 °C, the water utilization rate is 65%, and the first-stage reverse osmosis desalination rate is greater than 98%. The control part of the electric appliance adopts domestic high-quality products and has a long service life. In addition, the PLC controller is also configured to ensure automatic flushing by reverse osmosis and reduce the cleaning frequency.
Dow membrane element technical parameters standard test environment: 1500ppm NaCl
1.55MPa
25°C
Ng; 15%
PH: 6.5-7.0
Conditions of Use:
Temperature range: 5 ° C - 45 ° C
Influent PH: 3-10
Zui high operating pressure: 4.16MPa
Zui high influent water flow: 3.6m3/h
Intake water Zui high SDI (15 minutes) ≤ 5
Inlet water Zui high speed: 1.0NTU
Zui high influent residual chlorine concentration: ≤0.1ppm
Single membrane element Zui high pressure loss: 0.07MPa
The ratio of concentrated water to the amount of water permeated on a single membrane element: 5:1
Cleaning device:
When the reverse osmosis membrane element is used for a long time, it is inevitably subject to certain pollution, such as fouling of inorganic substances, bacteria, and microbial growth. At this time, the water production of the device is reduced, the salt rejection rate is reduced, and the system is equipped with a cleaning and reverse osmosis membrane element, so that the basic working ability is restored.
Description:
1. Causes and characteristics of heavy contamination of membrane components Although the design of water treatment systems will have a certain amount of sufficiency, it will ensure that the water supply will not be insufficient due to the decrease in water production or salt rejection rate and increase in pressure difference in an emergency. It poses a threat to safe production, but it is precisely because of the existence of these wealthy that sometimes hidden faults can not be manifested in time, so that zui may eventually become a serious pollution of membrane components.
1.1 The concept of heavy contamination of membrane elements refers to the surface adhesion, sedimentation pollution of the UF, NF, RO membranes or the chemical ion components in the water on the membrane surface caused by suspended solids, colloids, organic matter, microorganisms and other particles contained in the system inlet water. The ion product caused by factors such as concentration polarization is larger than the chemical scale formation after the solubility product. Heavy pollution means that the single-stage pressure difference after pollution is greater than twice the single-stage pressure difference at the initial stage of the system operation, the system water production is reduced by more than 30%, or the weight of the single-membrane element exceeds the normal value of 3 kg or more.
Heavy pollution is often a superposition of severe physical pollution and severe chemical pollution, and in some cases, both are accompanied.
1.2 Causes and characteristics of heavy pollution of membrane components Due to the different water quality of different water sources, the treatment methods and methods are not the same. The common pollution causes and characteristics are as follows:
1.2.1 Water treatment process system design and manufacturing defects (1) For the pretreatment filter, when the source water is well water, the equipment filtration speed is greater than 8.5 m / h, and the surface water design equipment filtration rate is greater than 8 m / h, resulting in poor water quality; (2) source water contains colloids, suspended solids and other impurities, and there are no removal measures in the design; (3) COD in the source water is too high without removal measures; (4) membrane element design The amount exceeds the standard.
All of the above design flaws may result in an increase in system pressure differential and a decrease in system water production.
1.2.2 Improper use of additives and other consumables (1) Improper selection of flocculants and coagulants in the pretreatment system may cause serious contamination of the membrane components, and improper selection of fungicides may cause serious damage to the desalination rate of the reverse osmosis system. (2) improper use of scale inhibitor type or dosing amount, such as: reverse osmosis scale inhibitor type is not compatible with source water, such as aluminum ion, iron ion or pretreatment dosing in the source water, iron, aluminum Such as flocculant, try to choose organic antimony scale inhibitor, try to avoid polycarboxylic acid type; the amount of anti-scaling agent is generally between 2-4ppm (calculated according to the amount of water), zui can not exceed 6ppm, etc. Improper choice of scale inhibitor type and dosing amount will lead to a rapid decrease in system water production and a significant increase in system pressure difference; (3) Security filter cartridges must ensure reliable quality during the selection process, claiming 5 microns and actual accuracy is not achieved. The filter element is very disadvantageous for the safe operation of the membrane element.
1.2.3 Systematic abnormalities caused by sudden changes in water treatment operating conditions are generally caused by climate change resulting in an increase in suspended solids content in the source water, or a change in the type of source water (eg, the change from groundwater to tap water results in residual chlorine in the influent) When the system is increased, the operating conditions deteriorate and severe pollution is formed.
1.2.4 System operation operation management problems (1) Failure to operate according to the operation rules; (2) Unadjusted adjustment of equipment status parameters; (3) Improper adjustment of operation parameters; (4) Measurement of added chemicals is not optimized; (5) When the system reaches the cleaning conditions, the system is not cleaned in time; (6) the system meter is not adjusted on time; (7) lack of operational management summary.
1.2.5 Water treatment system water supply tension In addition to the above situation, in a considerable number of enterprises, due to the tight water supply of the water treatment system, even if the operation parameters deteriorate, the system is polluted, but it cannot be timely due to the shortage of water supply. Cleaning results in serious pollution of the system, resulting in heavy pollution. 2. Off-line cleaning of severely contaminated membranes requires offline cleaning of heavily contaminated membrane components when the following conditions occur: (1) Membrane component contamination meets the criteria for “severe pollutionâ€; (2) The system cannot meet the system's rated standard through online cleaning; (3) The water treatment system cannot be cleaned online or has no online cleaning equipment due to tight water supply; (4) The pollution type is more complicated, which is easily caused by online cleaning. Cross-contaminated
3. Off-line cleaning method and step of membrane element 3.1 Firstly replace the membrane element to be cleaned on the system with spare membrane element with excellent performance to ensure that the system does not stop running and ensure the continuous stability of the whole production process.
3.2 membrane component performance test:
1 Each membrane element is tested separately for its performance indicators, including: salt rejection, water production, pressure difference, weight, etc., and records before the test 2 salt rejection rate, water production and pressure difference test conditions: meet different types Standards provided by membrane manufacturers.
3.3 Know the current operating status of the system before cleaning the system;
3.4 Collect the parameters of the operating system and make the original records;
3.5 Judging the cleaning process according to the user's original water analysis report, performance test results and the system information learned;
3.6 Identification of pollutants. Firstly, according to the analysis results of 3.5, preliminary judgment is made, and further verification is carried out by special equipment and instruments to determine the specific pollutant type.
3.7 According to the analysis results of 3.5 and 3.6, determine the required cleaning formula. When the contaminants on the membrane are determined, we can choose the series of formulas provided by the membrane manufacturer, choose one or two formulas that are more suitable; or choose a special formula (when the membrane is contaminated with special contaminants, use a common formula) The effect is not good, or when it is economically compared, the special formula is more economical). At present, there are many special agents for cleaning membrane elements at home and abroad, series of cleaning agents and fungicides. According to experience, the effect is good, and compared with traditional medicines, the economy is also good.
3.8 On the special cleaning equipment, use the above cleaning agent combined with physical treatment cleaning means for experimental cleaning to select the appropriate cleaning formula and cleaning procedure;
3.9 Determine the cleaning method and treat all the above membrane elements;
3.10 The cleaned membrane element enters the test platform for testing and recording. If it does not meet the requirements, it will be re-sent into the cleaning equipment for processing the fresh water tank:
Reverse osmosis water, into the pure water tank, and then sent to the water points through the pure water tank, in order to meet the verification requirements, the pure water tank is equipped with air breathing apparatus, in order to prevent the water level from rising and falling, the air in and out, the dust brought into the air and Microorganisms ensure that purified water is not contaminated. It is equipped with a spherical sprinkler and is cleaned in all directions from the inside of the pure water tank.
The control configuration inlet pressure sensor can set the height difference of the water level according to the height of the water tank. When the water level is not in the middle position, the secondary system automatically opens the condition, and when the water level is high, the secondary system automatically shuts down. When the water level is low, the pure water pump will automatically shut down. The unqualified water return device is configured to pass the qualified water into the pure water tank, and the unqualified water is returned to the raw water tank, which not only ensures the water quality of the water used in the later process, but also improves the utilization rate of the water.
Pure water tank:
Reverse osmosis water, into the pure water tank, and then sent to the water points through the pure water tank, in order to meet the verification requirements, the pure water tank is equipped with air breathing apparatus, in order to prevent the water level from rising and falling, the air in and out, the dust brought into the air and Microorganisms ensure that purified water is not contaminated. It is equipped with a spherical sprinkler and is cleaned in all directions from the inside of the pure water tank.
The control configuration inlet pressure sensor can set the height difference of the water level according to the height of the water tank. When the water level is not in the middle position, the secondary system automatically opens the condition, and when the water level is high, the secondary system automatically shuts down. When the water level is low, the pure water pump will automatically shut down. The unqualified water return device is configured to pass the qualified water into the pure water tank, and the unqualified water is returned to the raw water tank, which not only ensures the water quality of the water used in the later process, but also improves the utilization rate of the water.
Pure water pump:
This system adopts the Danish Grundfos stainless steel series, the pump head cover, the intermediate cavity, the shaft, the impeller, the outer sleeve and the spring are all 304 stainless steel. Good quality and long service life (no idling).
Control System:
This system adopts PLC centralized control (except cleaning device) control principle: raw water tank, fresh water tank and pure water tank all have sensing liquid level control meter, when the liquid level is opened or lowered to the level gauge control At the liquid level, the level gauge will output an electrical signal to the corresponding pump and solenoid valve to make a reasonable response (on, off) between the pump and the valve. Control of the inlet water solenoid valve: When the liquid level of the original water tank is higher than the set high level, the high level liquid level meter is disconnected, the solenoid valve is closed, and the water inlet is stopped; when the liquid level drops to the neutral position, the medium level The meter is combined, the electric signal is output, and the solenoid valve is opened to replenish water.
The function of low pressure protection is as follows: if the front end of the high pressure pump comes in (no pressure), the low voltage protection is disconnected from the high pressure pump electric signal, and the high pressure pump cannot operate. (Low pressure protection prevents high pressure pump from running at no load)
The function of high pressure protection is: when the operating pressure of the system exceeds the set safety pressure, the electrical signal between the high pressure protection and the high pressure pump is turned on, and the high pressure pump is stopped (preventing the valve parts of the system from being damaged by high pressure, effectively strengthening the safety of the system operation) )
Flushing solenoid valve control: When the high pressure pump runs for 2 hours (PLC is also timing), the PLC outputs an electric signal to the flushing solenoid valve, and the flushing solenoid valve opens the blowdown. After 3 minutes, the PLC electrical signal is disconnected, the solenoid valve is closed, and the normal production is normal. Water, (each time, turn off, the PLC sets the flushing magnetic valve to open for 3 minutes, then close the water to prevent fouling of organic matter and bacteria on the membrane element).
Overview: All liquid level gauges are used as input signals of PLC, and the signals are fed back to each pump and solenoid valve through PLC. That is to say, the pump and solenoid valve can only operate normally and reasonably when various liquid level signals are satisfied. . And the data is automatically printed by the panel printer, which plays the role of the whole process of the prosecution system. Effectively ensure the reliability of the system.
System self-circulation system (1) The complete set of equipment should be operated in accordance with a procedure; the purified water preparation system should remain operational even without water requirements.
(2) The product effluent is controlled according to the liquid level of the purified water storage tank.
(3) The secondary RO device has a self-circulating pipeline. When the liquid level of the storage tank is full and the water is not needed, the equipment is manually switched to the small cycle operation state, and the secondary production water is returned to the first-stage pressure pump to ensure the passage. The water in the reverse osmosis unit is living water.
(4) Continuous monitoring of the conductivity of raw water and primary and secondary RO water production (the value of this conductivity can be set) with unqualified water discharge and automatic alarm function; when the product water has low conductivity At the set point, the product water begins to enter the purified water storage tank.
Function: Overcoming the instability of the water supply of the pipe network, ensuring the stable and continuous water supply of the whole system; at the same time, it also provides a guarantee for the long-term performance of each equipment.
Control: Formulate the liquid level automatic control system. When the water pressure is in the low position, the original water valve is automatically opened. When the water level is high, the original water valve is automatically closed.
Original water pump:
Function: Provide the necessary working pressure selection for the pretreatment equipment: according to the design pressure drop of the pretreatment equipment (the pressure drop of each filter equipment is 0.5Mpa), and the pressure before the high pressure pump can not be less than 0.5 kg/cm 2 Work pressure.
Control: The whole system adopts PLC controller for the whole system, which can be operated manually and automatically.
The diaphragm is used to adjust the pressure and water intake (manual operation).
Motor characteristics:
Sealing level: IP54
Insulation class: F
Standard voltage: 3 × 380-415V; 50HZ
Motor speed: 2900 rev / min <br> <br> mechanical filter:
The raw water contains fine particles of dust, humus, starch, cellulose, bacteria, algae and other microorganisms. These impurities form colloidal particles with water in the sol state, and exhibit sedimentation stability and polymerization stability due to Brownian motion and electrostatic repulsion. Sexuality, usually can not be removed by the method of gravity natural sedimentation. Generally, the suspended matter contained in the suspended matter in the water can not be removed by sedimentation or the like, and the mechanical impurities can remove the water by mechanical filtration, thereby reducing the turbidity of the water. To improve clarity. The system is fully automatic operation, the valve is a stainless steel ball valve, enters the manual cleaning state, that is, the processes of backwashing, washing, staining, decontamination, and emptying are all done manually. When entering the normal working state, the water is discharged. Inlet water, manual opening, the system uses manual control.
Activated carbon filter:
In addition to requiring SDI less than or equal to 5, the reverse osmosis water has another influent index of residual chlorine of less than 0.1 mg/L. The carbon filter mainly has two functions: 1. Adsorption of some organic substances in water, the adsorption rate is about 60%; 2. Residual chlorine in the adsorption water. Inorganic colloids, organic colloids, and soluble organic polymer impurities and residual chlorine having a particle size of about 10-20 angstroms are difficult to remove in a sand filter. In order to further purify the raw water to achieve the reverse osmosis water inflow index, a carbon filter was designed in the process. The active carbon can be used to adsorb active materials with a particle size of several tens of angstroms due to the large average pore size of the structure. 20-50 angstroms of micropores and grain gaps, this structural feature of activated carbon, its surface adsorption area can reach 500-2000 square meters / gram, because the general organic molecules are slightly less than 20-50 angstroms, so activated carbon Has a strong adsorption of organic matter. In addition, active carbon has a strong deoxidation property, and residual chlorine reacts with carbon to form carbon dioxide and -1 valent chloride ions, so that only a small amount of carbon is lost, so dechlorination of activated carbon can be used for a relatively long period of time.
Activated carbon not only has the above functions, but also removes odors and pigments in water and improves the clarity of water. After using activated carbon for a period of time, its adsorption capacity decreases and needs to be regenerated or replaced. Therefore, after the raw water passes through the carbon filter, the water quality can be greatly improved, and the pollution to the reverse osmosis membrane can be reduced. After the treatment, the water quality can reach the requirement of the reverse osmosis water quality (residual chlorine <0.1 mg/L), in order to prevent higher concentration. The chloride ions cause long corrosion on the stainless steel surface, so the inner wall of the carbon filter is treated with anti-corrosion treatment to improve the service life of the equipment. The activated carbon filter operates through a carbon bed. The activated carbon particles constituting the carbon bed have a large number of micropores and a large specific surface area, and have a strong physical adsorption capacity. In addition, there are some oxygen-containing energy groups on the non-crystalline part of the activated carbon surface, so that the organic pollutants in the water passing through the carbon bed are effectively adsorbed by the activated carbon. The filter is a relatively common water treatment equipment, which is used as a pretreatment equipment in the water treatment desalination system, which can effectively ensure the service life of the latter equipment, improve the effluent water quality, prevent pollution, and especially prevent the reverse osmosis membrane. Poisoning of free residual oxygen such as ion exchange resin. Activated carbon filter has obvious removal ability for organic matter, colloid and pigment in water. Activated carbon filters are mainly used to remove organic matter, odor, color, heavy metal ions, residual chlorine (CL2), etc. in water. As a pretreatment of reverse osmosis, electrodialysis, and ion exchangers. Activated carbon can provide a good protection for these devices. The activated carbon adsorption filter is a pressure type filtering device which uses activated carbon as a filter material, and can be softened with ion exchange, and the desalination equipment is connected in series to form a treatment system. The activated carbon adsorption filter not only has the function of filtering the suspended matter by the ordinary mechanical filter, but also removes impurities such as free residual chlorine, odor, color and organic matter which are difficult to remove by conventional means. The system is fully automatic operation, the valve is a stainless steel ball valve, enters the manual cleaning state, that is, the processes of backwashing, washing, staining, decontamination, and emptying are all done manually. When entering the normal working state, the water is discharged. Inlet water, manual opening, the system uses manual control.
First stage multistage pump:
Fresh water is obtained by applying a certain pressure on the concentrated water side of the reverse osmosis membrane to achieve the penetration of the solution from the high concentration to the low concentration side. Here, the multistage pump functions to increase the water pressure. The Danish Grundfos multistage pump used by our company has a thermal protection function, and when the temperature rises, the multistage pump automatically stops working. In addition, the multi-stage pump uses high and low pressure protection switches on the water inlet and outlet side. When the inlet pressure is low or no water, the multistage pump automatically shuts down. When the membrane concentrated water side pressure is high, the multistage pump automatically shuts down, thus Multi-stage pumps and membranes play an important role in protecting the system from normal operation.
Precision filter:
The precision filter, also known as the security filter, uses a 5 micron PP fuse core. This filter has strong hydrophilicity, good filtering effect and long service life. The precision filter is a process after the raw water enters the reverse osmosis, and its function is to prevent some particles from being brought into the reverse osmosis to ensure the reverse osmosis water quality to prolong the service life of reverse osmosis.
Secondary multistage pump:
Reverse osmosis is obtained by applying a certain pressure on the concentrated water side of the RO membrane to achieve the penetration of the solution from a high concentration to a low concentration side. Here, the multistage pump functions to increase the water pressure. The multi-stage pump of the Danish Grundfos pump used by our company has thermal protection function. When the temperature rises, the multi-stage pump automatically stops working. In addition, the low-pressure protection switch is used on the inlet side of the multi-stage pump. When the inlet pressure is low or no water, the multi-stage pump is automatically closed to protect it.
Reverse osmosis host:
1. Permeation and osmotic pressure penetration are common in nature. For example, when a cucumber is placed in salt water, the process of changing the water molecules in the cucumber into the saline solution due to water loss is the infiltration process. If a water tank is used to penetrate a pool, the water pool is divided into two parts, and pure water and brine are injected into the same height on both sides of the diaphragm. After a while, it can be found that the pure water level is lowered, and the liquid level of the brine is raised. The phenomenon in which water molecules migrate through the membrane into the brine is called infiltration. The rise in salt water is not endless, reaching a point of equilibrium at a certain height. At this time, the pressure represented by the liquid level difference at both ends of the diaphragm is called the osmotic pressure. The magnitude of the osmotic pressure is directly related to the concentration of the brine.
2. Reverse osmosis phenomenon and reverse osmosis water purification technology After the above device reaches equilibrium, if a certain pressure is applied to the liquid surface of the brine end, at this time, the water molecules will migrate from the brine end to the pure water end. The phenomenon that the liquid molecules migrate from a dilute solution to a concentrated solution under pressure is called a reverse osmosis phenomenon. If brine is added to one end of the above facility and a pressure above the osmotic pressure of the brine is applied at that end, we can get pure water at the other end. This is the principle of reverse osmosis water purification. There are two key points in the production of pure water by reverse osmosis facilities. One is a selective membrane, which we call a semi-permeable membrane, and the other is a certain pressure. Simply put, the reverse osmosis semipermeable membrane has a large number of pores, the size of which is equivalent to the size of water molecules. Since bacteria, viruses, most organic pollutants and hydrated ions are much larger than water molecules, they cannot be penetrated. The reverse osmosis semipermeable membrane is separated from the aqueous phase that passes through the reverse osmosis membrane. Among the many kinds of impurities in water, the soluble salts are difficult to remove. Therefore, the water purification effect of reverse osmosis is often determined according to the level of salt removal. The level of reverse osmosis desalination is mainly determined by the selectivity of the reverse osmosis semipermeable membrane. At present, the selectivity of the highly selective reverse osmosis membrane element can be as high as 99.7%.
3. Reverse osmosis and ion exchange comparison reverse osmosis advantages:
* Continuous operation, product water quality is stable * No need to use acid and alkali regeneration * No downtime due to regeneration * Save backwash and cleaning water * Produce ultrapure water in high yield (up to 95% yield)
* No reclaimed sewage, no need for sewage treatment facilities * No need for acid and alkali reserves and acid-base dilution transport facilities * Reduce the floor area of ​​the workshop * Safe and reliable use, avoid workers' exposure to acid and alkali * Reduce operating and maintenance costs * Simple installation and low installation cost The weakness of reverse osmosis and the solution The system salt removal rate of reverse osmosis equipment is generally 98-99%. Such salt removal rate can meet the requirements in most cases. In the electronics industry, ultra-high pressure boiler feed water, individual pharmaceutical industries may have higher requirements for pure water. At this point, the single-stage reverse osmosis equipment cannot meet the requirements. The system uses reverse osmosis and ion exchange to reduce the plant floor area and reduce low operating costs.
The main part of the first-stage reverse osmosis main engine is the RO membrane component. The company selected the low-pressure polyamide composite membrane (BW30-400) produced by American Dow Company, which not only has low working pressure, strong anti-pollution ability, but also has higher rated water production. Large, high salt rejection rate, and a large use margin, to ensure that the designed water production is still achieved after three years of use. The production temperature of reverse osmosis is 20 °C, the water utilization rate is 65%, and the first-stage reverse osmosis desalination rate is greater than 98%. The control part of the electric appliance adopts domestic high-quality products and has a long service life. In addition, the PLC controller is also configured to ensure automatic flushing by reverse osmosis and reduce the cleaning frequency.
Dow membrane element technical parameters standard test environment: 1500ppm NaCl
1.55MPa
25°C
Ng; 15%
PH: 6.5-7.0
Conditions of Use:
Temperature range: 5 ° C - 45 ° C
Influent PH: 3-10
Zui high operating pressure: 4.16MPa
Zui high influent water flow: 3.6m3/h
Intake water Zui high SDI (15 minutes) ≤ 5
Inlet water Zui high speed: 1.0NTU
Zui high influent residual chlorine concentration: ≤0.1ppm
Single membrane element Zui high pressure loss: 0.07MPa
The ratio of concentrated water to the amount of water permeated on a single membrane element: 5:1
Cleaning device:
When the reverse osmosis membrane element is used for a long time, it is inevitably subject to certain pollution, such as fouling of inorganic substances, bacteria, and microbial growth. At this time, the water production of the device is reduced, the salt rejection rate is reduced, and the system is equipped with a cleaning and reverse osmosis membrane element, so that the basic working ability is restored.
Description:
1. Causes and characteristics of heavy contamination of membrane components Although the design of water treatment systems will have a certain amount of sufficiency, it will ensure that the water supply will not be insufficient due to the decrease in water production or salt rejection rate and increase in pressure difference in an emergency. It poses a threat to safe production, but it is precisely because of the existence of these wealthy that sometimes hidden faults can not be manifested in time, so that zui may eventually become a serious pollution of membrane components.
1.1 The concept of heavy contamination of membrane elements refers to the surface adhesion, sedimentation pollution of the UF, NF, RO membranes or the chemical ion components in the water on the membrane surface caused by suspended solids, colloids, organic matter, microorganisms and other particles contained in the system inlet water. The ion product caused by factors such as concentration polarization is larger than the chemical scale formation after the solubility product. Heavy pollution means that the single-stage pressure difference after pollution is greater than twice the single-stage pressure difference at the initial stage of the system operation, the system water production is reduced by more than 30%, or the weight of the single-membrane element exceeds the normal value of 3 kg or more.
Heavy pollution is often a superposition of severe physical pollution and severe chemical pollution, and in some cases, both are accompanied.
1.2 Causes and characteristics of heavy pollution of membrane components Due to the different water quality of different water sources, the treatment methods and methods are not the same. The common pollution causes and characteristics are as follows:
1.2.1 Water treatment process system design and manufacturing defects (1) For the pretreatment filter, when the source water is well water, the equipment filtration speed is greater than 8.5 m / h, and the surface water design equipment filtration rate is greater than 8 m / h, resulting in poor water quality; (2) source water contains colloids, suspended solids and other impurities, and there are no removal measures in the design; (3) COD in the source water is too high without removal measures; (4) membrane element design The amount exceeds the standard.
All of the above design flaws may result in an increase in system pressure differential and a decrease in system water production.
1.2.2 Improper use of additives and other consumables (1) Improper selection of flocculants and coagulants in the pretreatment system may cause serious contamination of the membrane components, and improper selection of fungicides may cause serious damage to the desalination rate of the reverse osmosis system. (2) improper use of scale inhibitor type or dosing amount, such as: reverse osmosis scale inhibitor type is not compatible with source water, such as aluminum ion, iron ion or pretreatment dosing in the source water, iron, aluminum Such as flocculant, try to choose organic antimony scale inhibitor, try to avoid polycarboxylic acid type; the amount of anti-scaling agent is generally between 2-4ppm (calculated according to the amount of water), zui can not exceed 6ppm, etc. Improper choice of scale inhibitor type and dosing amount will lead to a rapid decrease in system water production and a significant increase in system pressure difference; (3) Security filter cartridges must ensure reliable quality during the selection process, claiming 5 microns and actual accuracy is not achieved. The filter element is very disadvantageous for the safe operation of the membrane element.
1.2.3 Systematic abnormalities caused by sudden changes in water treatment operating conditions are generally caused by climate change resulting in an increase in suspended solids content in the source water, or a change in the type of source water (eg, the change from groundwater to tap water results in residual chlorine in the influent) When the system is increased, the operating conditions deteriorate and severe pollution is formed.
1.2.4 System operation operation management problems (1) Failure to operate according to the operation rules; (2) Unadjusted adjustment of equipment status parameters; (3) Improper adjustment of operation parameters; (4) Measurement of added chemicals is not optimized; (5) When the system reaches the cleaning conditions, the system is not cleaned in time; (6) the system meter is not adjusted on time; (7) lack of operational management summary.
1.2.5 Water treatment system water supply tension In addition to the above situation, in a considerable number of enterprises, due to the tight water supply of the water treatment system, even if the operation parameters deteriorate, the system is polluted, but it cannot be timely due to the shortage of water supply. Cleaning results in serious pollution of the system, resulting in heavy pollution. 2. Off-line cleaning of severely contaminated membranes requires offline cleaning of heavily contaminated membrane components when the following conditions occur: (1) Membrane component contamination meets the criteria for “severe pollutionâ€; (2) The system cannot meet the system's rated standard through online cleaning; (3) The water treatment system cannot be cleaned online or has no online cleaning equipment due to tight water supply; (4) The pollution type is more complicated, which is easily caused by online cleaning. Cross-contaminated
3. Off-line cleaning method and step of membrane element 3.1 Firstly replace the membrane element to be cleaned on the system with spare membrane element with excellent performance to ensure that the system does not stop running and ensure the continuous stability of the whole production process.
3.2 membrane component performance test:
1 Each membrane element is tested separately for its performance indicators, including: salt rejection, water production, pressure difference, weight, etc., and records before the test 2 salt rejection rate, water production and pressure difference test conditions: meet different types Standards provided by membrane manufacturers.
3.3 Know the current operating status of the system before cleaning the system;
3.4 Collect the parameters of the operating system and make the original records;
3.5 Judging the cleaning process according to the user's original water analysis report, performance test results and the system information learned;
3.6 Identification of pollutants. Firstly, according to the analysis results of 3.5, preliminary judgment is made, and further verification is carried out by special equipment and instruments to determine the specific pollutant type.
3.7 According to the analysis results of 3.5 and 3.6, determine the required cleaning formula. When the contaminants on the membrane are determined, we can choose the series of formulas provided by the membrane manufacturer, choose one or two formulas that are more suitable; or choose a special formula (when the membrane is contaminated with special contaminants, use a common formula) The effect is not good, or when it is economically compared, the special formula is more economical). At present, there are many special agents for cleaning membrane elements at home and abroad, series of cleaning agents and fungicides. According to experience, the effect is good, and compared with traditional medicines, the economy is also good.
3.8 On the special cleaning equipment, use the above cleaning agent combined with physical treatment cleaning means for experimental cleaning to select the appropriate cleaning formula and cleaning procedure;
3.9 Determine the cleaning method and treat all the above membrane elements;
3.10 The cleaned membrane element enters the test platform for testing and recording. If it does not meet the requirements, it will be re-sent into the cleaning equipment for processing the fresh water tank:
Reverse osmosis water, into the pure water tank, and then sent to the water points through the pure water tank, in order to meet the verification requirements, the pure water tank is equipped with air breathing apparatus, in order to prevent the water level from rising and falling, the air in and out, the dust brought into the air and Microorganisms ensure that purified water is not contaminated. It is equipped with a spherical sprinkler and is cleaned in all directions from the inside of the pure water tank.
The control configuration inlet pressure sensor can set the height difference of the water level according to the height of the water tank. When the water level is not in the middle position, the secondary system automatically opens the condition, and when the water level is high, the secondary system automatically shuts down. When the water level is low, the pure water pump will automatically shut down. The unqualified water return device is configured to pass the qualified water into the pure water tank, and the unqualified water is returned to the raw water tank, which not only ensures the water quality of the water used in the later process, but also improves the utilization rate of the water.
Pure water tank:
Reverse osmosis water, into the pure water tank, and then sent to the water points through the pure water tank, in order to meet the verification requirements, the pure water tank is equipped with air breathing apparatus, in order to prevent the water level from rising and falling, the air in and out, the dust brought into the air and Microorganisms ensure that purified water is not contaminated. It is equipped with a spherical sprinkler and is cleaned in all directions from the inside of the pure water tank.
The control configuration inlet pressure sensor can set the height difference of the water level according to the height of the water tank. When the water level is not in the middle position, the secondary system automatically opens the condition, and when the water level is high, the secondary system automatically shuts down. When the water level is low, the pure water pump will automatically shut down. The unqualified water return device is configured to pass the qualified water into the pure water tank, and the unqualified water is returned to the raw water tank, which not only ensures the water quality of the water used in the later process, but also improves the utilization rate of the water.
Pure water pump:
This system adopts the Danish Grundfos stainless steel series, the pump head cover, the intermediate cavity, the shaft, the impeller, the outer sleeve and the spring are all 304 stainless steel. Good quality and long service life (no idling).
Control System:
This system adopts PLC centralized control (except cleaning device) control principle: raw water tank, fresh water tank and pure water tank all have sensing liquid level control meter, when the liquid level is opened or lowered to the level gauge control At the liquid level, the level gauge will output an electrical signal to the corresponding pump and solenoid valve to make a reasonable response (on, off) between the pump and the valve. Control of the inlet water solenoid valve: When the liquid level of the original water tank is higher than the set high level, the high level liquid level meter is disconnected, the solenoid valve is closed, and the water inlet is stopped; when the liquid level drops to the neutral position, the medium level The meter is combined, the electric signal is output, and the solenoid valve is opened to replenish water.
The function of low pressure protection is as follows: if the front end of the high pressure pump comes in (no pressure), the low voltage protection is disconnected from the high pressure pump electric signal, and the high pressure pump cannot operate. (Low pressure protection prevents high pressure pump from running at no load)
The function of high pressure protection is: when the operating pressure of the system exceeds the set safety pressure, the electrical signal between the high pressure protection and the high pressure pump is turned on, and the high pressure pump is stopped (preventing the valve parts of the system from being damaged by high pressure, effectively strengthening the safety of the system operation) )
Flushing solenoid valve control: When the high pressure pump runs for 2 hours (PLC is also timing), the PLC outputs an electric signal to the flushing solenoid valve, and the flushing solenoid valve opens the blowdown. After 3 minutes, the PLC electrical signal is disconnected, the solenoid valve is closed, and the normal production is normal. Water, (each time, turn off, the PLC sets the flushing magnetic valve to open for 3 minutes, then close the water to prevent fouling of organic matter and bacteria on the membrane element).
Overview: All liquid level gauges are used as input signals of PLC, and the signals are fed back to each pump and solenoid valve through PLC. That is to say, the pump and solenoid valve can only operate normally and reasonably when various liquid level signals are satisfied. . And the data is automatically printed by the panel printer, which plays the role of the whole process of the prosecution system. Effectively ensure the reliability of the system.
System self-circulation system (1) The complete set of equipment should be operated in accordance with a procedure; the purified water preparation system should remain operational even without water requirements.
(2) The product effluent is controlled according to the liquid level of the purified water storage tank.
(3) The secondary RO device has a self-circulating pipeline. When the liquid level of the storage tank is full and the water is not needed, the equipment is manually switched to the small cycle operation state, and the secondary production water is returned to the first-stage pressure pump to ensure the passage. The water in the reverse osmosis unit is living water.
(4) Continuous monitoring of the conductivity of raw water and primary and secondary RO water production (the value of this conductivity can be set) with unqualified water discharge and automatic alarm function; when the product water has low conductivity At the set point, the product water begins to enter the purified water storage tank.
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