The secondary filter system is a device designed and developed to purify water and dirt, maintain the cleanliness of the condenser water chamber, ensure the normal operation of the rubber ball, and improve the rubber ball recovery rate. But I, the environment is relatively strict, especially the water pollution of rivers and lakes. Therefore, the open-loop cooling water system, which commonly uses fixed secondary filters and rotating negative pressure backwash secondary filters, has shown its shortcomings. Through continuous solicitation of opinions from users and repeated trial production and improvement of secondary filters in recent years, some structures have been retained, electric devices have been added, and strong sewage discharge devices have been added to improve the structure and usage of secondary filters. They have been applied to the cooling water open cycle system of 6MW to 300MW thermal power generator sets.

Secondary filter - outlet potential:

The circulating water system of condensers in various power plants (stations) - two commonly used secondary filters, fixed secondary filter and rotary secondary filter, have been proven to have the following main problems:

1. Fixed secondary filter -:

The fixed core of the secondary filter screen cannot rotate, and the cleaning effect is poor. The mesh holes are prone to blockage, and the cleaning needs to wait for the machine to stop.

2. Rotating secondary filter -:

During the rotation and cleaning of the secondary filter core, it relies on negative pressure backwashing. This filter has a stronger cleaning ability than the fixed type. However, during the peak flood season, when the cargo water pollution is severe, and the water contains plastic film. When weeds and other highly adhesive pollutants are cleaned, the cleaning results are still not taken care of. If the scraper in the sewage chamber is severely worn, the cleaning results are poor

There are also significant deficiencies in the secondary filter structure:

(1) The secondary filter screen drives the mesh core, and the gears are prone to wear and corrosion during operation in water containing impurities such as sediment, which seriously affects the safety and economic operation of the unit.

(2) The secondary filter transmission control system is relatively complex, usually composed of control solenoid valves, oil pumps, oil tanks, oil cylinders, oil motors, oil circuit control boxes, etc., which are prone to oil and control failures during operation.

(3) The maintenance and repair workload of the secondary filter is large. In response to the shortcomings of the secondary filter mentioned above, our factory has conducted investigation and research on the secondary filter and repeatedly developed an electric rotary recoil secondary filter, which is a purposeful and efficient secondary filter

The secondary filter has the following features:

1. Eliminated the complex and prone to faults in the transmission system of the secondary filter, ensuring safe and reliable operation, and convenient maintenance and repair.

2. Under the strict pollution of plastic film, a strong sewage discharge device has been added to overcome the situation of other secondary filter devices for plastic film cleaning.

Secondary filter structure -:

The electric rotary recoil type secondary filter structure is mainly composed of: ⑴ shell ⑵ stainless steel mesh core ⑶ transmission machine - ⑵ reducer ⑤ strong drainage device and other components.

Working principle of secondary filter screen:

The circulating water filtered through the trash rack and secondary filter still contains a lot of suspended solids, sediment and other impurities. After passing through the circulating water pump and entering the secondary filter, it is filtered again. When impurities such as water suspended solids and plastic films attach to a certain amount on the surface of the filter, the water pressure difference between the inside and outside of the secondary filter increases to the specified value in the control system (usually 500mmH2O column). The control system is activated and the sewage discharge machine is put into operation, Discharge the attached material from the secondary filter screen and wait for the pressure difference inside to return to normal (generally ≤ 400mmH2O column) to control the machine to shut down and cycle back and forth, thus completing the filtration and sewage discharge process. You can also choose to discharge pollutants on a scheduled basis according to the user's situation.

The secondary filter can be installed vertically or horizontally in the condenser, or at the outlet of the circulating pump, with the same effect. The length of the filter - straight pipe - should be greater than the diameter of the circulating water pipeline. During installation, it should not be tilted and the connection should be firm. Maintain a distance of at least 1000mm between the filter screen and the secondary filter pipe of the circulating water in the condenser, and install a compensation joint between the filter screen and the condenser for easy repair, disassembly, and compensation purposes. After installation, it is necessary to remove any debris from the filter - circulating water pipe -, put it into operation, and conduct a running test. Backwashing water volume: not more than 5% to 10% of the total circulating water volume. Backwashing interval (set): 1-24 hours. Adjustable backwashing time (set): 0-10 minutes.

Technical parameters of DE type fully enclosed electric pressure backwash secondary filter:

FE型切換式反沖洗二次濾網技術參數：

WE系列外旋式二次濾網技術參數：

二次濾網法蘭技術參數：

注意：以上二次濾網技術規格參數僅供參考以實際設計為主。

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