How to debug the working pressure of RO membrane of reverse

AWT·2022-03-28

1. What is the influence of the working pressure of the reverse osmosis membrane of the reverse osmosis equipment?

1. Influence of low working pressure of reverse osmosis membrane

2. Influence of high working pressure of reverse osmosis membrane

If the working pressure of the reverse osmosis membrane is too high, the reverse osmosis membrane may be damaged. Theoretically, increasing the working pressure can increase the water production and increase the desalination rate. But you need to know that each membrane has an upper limit on its water production and desalination rate. When this upper limit is reached, even if the working pressure is increased, the water production cannot be increased, and the reverse osmosis membrane may be damaged.

3. Influence of inlet water pressure on reverse osmosis membrane

The inlet water pressure of the reverse osmosis membrane will not have a direct impact on the permeation of salt, but the increase in the inlet water pressure will increase the static pressure of reverse osmosis, because the amount of water produced increases, the salt permeation will not change at this time. If it is too large, the increase in water production will dilute the salt that permeates the membrane and reduce the salt permeability, which is equivalent to increasing the desalination rate. When the influent pressure exceeds a certain value, due to the high recovery rate, the concentration polarization will be increased, which will lead to an increase in salt permeation, which offsets the increased water production, so that the desalination rate no longer increases.

2. How to debug the pressure switch of reverse osmosis equipment?

The high/low pressure protection of water treatment reverse osmosis equipment is to prevent the RO high pressure pump from idling or working under extreme high/low pressure.

The high-voltage switch is for high-voltage protection. As the equipment's use time increases, the membrane will become fouled, and the natural membrane inlet pressure will increase. When the pressure increases to a certain level, in order to protect the equipment and pipelines from damage, a high-pressure switch is required for protection, and the pressure increases to the preset value of the pressure switch. , the equipment will be forced to stop.

Low pressure switch, when the pressure in the water inlet pipe is low, the reverse osmosis membrane cannot work normally and will always discharge waste water, so when the water inlet pressure fails to meet the working requirements, the circuit will be cut off and the machine will stop working. When the pressure in the inlet pipe reaches the working requirements, it will start working again.

Debugging method of reverse osmosis pressure switch in water treatment

The low pressure switch has two adjustable screws, one is to adjust the reference pressure, generally 0-6bar, and the other is to adjust the differential pressure, generally 0-2bar, which can be adjusted with a screwdriver.

There are two possibilities that the common low pressure switch always jumps, one is that the raw water pressure fluctuates greatly, and the other is that the reference pressure is near the raw water pressure value and the return differential pressure is small.

The engineer of Dior water treatment factory believes that the first one is generally easy to solve, such as exhausting the pretreatment equipment and increasing the opening of the outlet valve of the raw water pump, so that the pressure of the raw water is relatively large, and it is not easy to jump.

For the second one, it can be adjusted as follows:

1. First observe the pressure during normal operation of the equipment, and adjust the reference pressure to be slightly lower than it. For example, the pretreatment water pressure is 2.5bar, then the reference pressure can be adjusted to 2bar;

2. Set the pressure value of the low pressure jump. For example, when the raw water pressure is lower than 1.5bar, the pressure switch starts to jump, then adjust the return pressure to 0.5bar;

3. Although it has been adjusted, the accuracy of the adjustment is also different. Therefore, adjust according to the actual pressure condition until it meets your own requirements. The pressure is adjusted by adjusting the high pressure pump valve or the raw water pump outlet valve).

4. If you want the pressure hysteresis to be larger, you can also adjust the hysteresis pressure to 0.8-1.0bar, so that when the pressure reaches 2bar, it will close, and when the pressure is lower than 1bar, it will jump.