Operation and maintenance of mixed bed equipment

1、 Process principle:

Principle characteristics:

The mixed ion exchanger (referred to as the mixed bed) produced by our company is used for the preparation of secondary desalination water in desalination engineering. The treated water flows from top to bottom through a strong acid and alkali resin layer filled and mixed in a certain proportion to produce finished water. In a uniformly mixed resin layer, the cation resin and anion resin are closely interlaced, and each pair of cation resin and anion resin particles is like a group of composite beds, while the mixed bed is like a composite bed running in series without an array. After mixed ion exchange, hydrogen ions and hydrogen oxygen ions entering the water will immediately generate water molecules (H2O) with very low ionization degree, which is unlikely to form counter ions during cation or anion exchange, making the exchange reaction very thorough, and thus producing highly purified finished water.

The regeneration process of mixed beds is more complex than that of cation and anion beds. After the resin layer in the mixed bed fails, it is necessary to first backwash and layer the resin in the bed to completely separate the cation resin and anion resin. Then, the cation and anion resins are regenerated, cleaned, restored to exchange capacity, and evenly mixed before they can continue to be put into operation.

2、 Technical parameters:

1. Inlet water: primary desalinated water or RO produced water

2. Outlet water quality: 2-15MQ: cm

SiO2 leakage<100ug/, pH close to neutral

3. Working pressure:<0.6MPa

4. Working temperature: 5-45 ° C

5. Operating flow rate: 40-60m/h

6. Water backwashing strength: 8-12m/h

7. Regeneration flow rate: 4-6 m/h

8. Regeneration liquid concentration: 4-5%

9. Filler height: cation resin 001X7  anion resin 201X7: 500  1000

3、 Structural form:

The equipment consists of a main body, water distribution device, water collection device, external piping, and instrument sampling device. The water inlet device consists of an upper water inlet and a baffle for water distribution, while the water collection device consists of a porous plate water filter cap for water collection; The external piping of the equipment body is equipped with a valve and a pressure sampling interface is left, which is convenient for users to install on site and achieve normal operation of the device.

4、 Installation of equipment

1) Before installation, check whether the civil foundation is constructed according to the design requirements.

2) The equipment is positioned according to the design drawings, the support leg pad iron is adjusted, and the levelness and verticality of the inlet and outlet flanges are checked.

3) Weld and fix the equipment and foundation with embedded iron plates, and then recheck the levelness and verticality of the inlet and outlet C flanges.

4) After distinguishing the equipment body piping by number, assemble according to the design drawings. Before assembling each section of pipeline, clean the inner wall with a clean cloth. After assembly, keep the piping axis horizontal and vertical, and the valve orientation reasonable (manual valve handle facing forward, pneumatic valve starting head facing up).

5) Check that the valve switch of the body is flexible, and rectify any inflexibility in a timely manner.

6) After the equipment body piping is completed, necessary support work should be carried out for the valve group.

7) Install inlet and outlet water pressure gauges, sampling valves, etc. equipped on the equipment; If there is a flow probe seat on the inlet and outlet water pipes, it should be blocked with a plug.

5、 First time driving

1) Flushing

Considering the welding residue during the connection of equipment and pipelines, as well as the surface dirt during the initial use of pipelines, flushing should be carried out during the initial operation of the equipment.

A. Open the manhole flange of the equipment, retighten the parts inside the equipment, and confirm that the components inside the tank (such as water caps) are not missing; Closed manhole flange.

B. Open the lower discharge valve of the equipment and confirm that the outlet valve of the equipment is closed.

C. Open the inlet and exhaust valves of the equipment, open the front system, and close the exhaust valve after the water outlet of the equipment. Rinse the equipment until the water outlet is clear, which is the flushing endpoint.

2) Fill the resin according to the designed resin height, and then fill it in sequence. After filling, smooth it out. Use the middle discharge device branch pipe as the cation resin reference line, and 200mm below the alkali distribution device branch pipe as the anion resin reference line. After filling the filter material, close the manhole.

3) Treat according to the following new resin treatment method.

4) After normal operation of the equipment, the difference in inlet and outlet water pressure should be checked to ensure that it does not exceed 0.5 bar, and the flow rate display of the inlet and outlet water should be checked.

Six operating instructions:

This instruction describes the routine operation of the equipment, and the operating procedures for the desalination station system I shall be subject to the "Operation Manual".

1. Washing

Start the first stage desalinated water pump, open the inlet and exhaust valves of the mixed bed, and ensure that the water flows from top to bottom. When the water fills the equipment, close the exhaust valve and open the lower discharge valve to stabilize its normal water production flow rate. The working flow rate is 40m/h, and the outlet conductivity is ≤ 0.2 μ S/cm, which means transferring to water production.

2. Water production

Open the outlet valve of the mixed bed, close the lower discharge valve, and stabilize the water production to reach the specified set value until the end of the water production cycle.

3. Regeneration

(1) Backwashing pre layering: Open the backwashing inlet valve and upper discharge valve, perform backwashing layering at a flow rate of 10m/h, or control the backwashing flow rate by keeping the resin in a fully flowing state and ensuring that normal particle resin is not washed out by the water flow. The backwashing end point is until the anion and cation resins are basically layered.

(2) Failure: Open the dilution valve of the alkali regeneration water, the outlet valve of the alkali metering tank, the alkali inlet valve and lower discharge valve of the mixed bed, start the regeneration pump, and control the flow rate at 5m/h for 5 minutes. The temperature of the regeneration water is 40~50 ° C.

(3) Backwashing layering: Open the backwashing inlet valve and upper discharge valve, and perform backwashing layering at a flow rate of 10m/h. The backwashing flow rate or flow rate is the same as the backwashing pre layering. The backwashing end point should be completely layered at the junction of anion and cation resins. At the end of backwashing, the inlet valve should be slowly closed to gradually settle resin particles, in order to achieve the best layering effect.

(4) Settlement: Close the backwash inlet valve and upper discharge valve, open the exhaust valve and lower discharge valve, so that the unfolded resin after backwashing settles naturally and evenly, and the liquid level in the container drops to 200mm above the resin surface.

(5) Regenerant injection: Using synchronous regeneration method, open the dilution valve of the regeneration water in the regeneration system, the outlet valve of the acid and alkali metering tank, the acid and alkali inlet valves, and the intermediate discharge valve of the mixed bed, start the regeneration pump, and the acid and alkali regeneration flow rate should be 5m/h. The regeneration time should be determined according to actual needs. The temperature of the regenerated water injected with the alkali solution should be heated to 40-45 "C to achieve good regeneration effect.

(6) Replacement: Close the acid and alkali discharge valves of the metering tank, and perform replacement cleaning at the same working flow rate as the regenerant injection. The time is 20 minutes or determined by the water discharge indicator reaching the set target.

4. Mixing

(1) Drainage:

Open the exhaust valve and lower the exhaust valve, and confirm that the accumulated water in the container is discharged to a position 200mm above the resin layer, allowing sufficient space for the resin layer to move.

(2) Mixing:

Open the upper exhaust valve, exhaust valve, and intake valve; The intake pressure is generally controlled within a mixing time of 0.1~0.15MPa for 2 minutes, or determined based on the standard of fully mixing the two resins in the container.

(3) Drainage:

Open the lower discharge valve; Drain the water level in the container below the resin layer, and at the end, drain it as soon as possible to promote rapid resin sinking, in order to prevent resin from re separating and incomplete mixing during the settling process. However, attention should be paid to preventing resin layer dehydration.

5. Washing

Start the first stage desalinated water pump, open the inlet valve of the mixed bed, close the backwash discharge valve, and lower discharge valve. When the water fills the equipment, close the exhaust valve, open the lower discharge valve, and set the water production flow rate as the washing flow rate (some changes in flow rate are not harmful). Enter the washing condition until the outlet conductivity is<0.2us/cm. The equipment will then enter normal water production or standby mode.

Note: It is strictly prohibited to backwash the resin when the liquid level is lower than the resin level, to prevent the dry resin from being pushed and squeezed to damage the intermediate discharge device or regeneration liquid distribution device!

After the equipment is shut down for a long time, the start-up should start from the regeneration process.

7、 Precautions:

1. The (1) backwashing pre layering and (2) failure step cough in the regeneration process shall be determined based on the specific situation, or when the resin layering in the mixed bed is not obvious.

2. It is strictly prohibited to backwash the resin when the liquid level is lower than the resin level, to prevent the dry resin from being pushed and squeezed to damage the intermediate discharge device and regeneration liquid distribution device.

3. When backwashing the ion exchanger, the backwash valve must be slowly opened to prevent excessive water flow from taking away the resin.

4. It is strictly prohibited to carry out welding or gas cutting operations on the surface of the steel lined rubber pipeline of the equipment body or valve group.

The above is the "Operation and Maintenance of Mixed Bed Equipment" introduced by Hongjie Water, hoping to be helpful to you. Before purchasing equipment, we need to have a certain understanding of its composition, then understand its characteristics and defects, and make a comprehensive selection.

As for the cost of a mixed bed equipment, it depends on the customer's water production capacity, the required configuration, and the price. Hongjie Water has 10 years of experience in producing pure water treatment equipment, rich production experience, professional technology, and after-sales service team. The equipment components are all made of well-known brands, with guaranteed quality and after-sales service.