Vacuum belt dehydrator nozzle belt filter press

The vacuum belt dewatering machine is an important equipment for the secondary dewatering of gypsum. The quality of the filter cloth determines the dewatering effect of the filter machine. The service life of the filter cloth is determined by many factors such as the type, performance, operating conditions, and temperature of the processed material of the filter machine. However, clogging often occurs during the use of filter cloth,

This shortens the service life of the filter cloth and seriously affects the filtration effect.

The main reasons for filter cloth blockage are as follows:

1filter clothDue to inherent reasons

1. The quality of filter cloth is determined by various factors such as its material, weaving process, and interface process,

A、 Polyester material: This material is an ideal choice under acidic conditions, with high temperature resistance (less than 150 degrees Celsius for pH values 1-9), strong tensile strength, longitudinal and transverse stability, and wear resistance second only to nylon.

B、 Polypropylene: It has good acid and alkali resistance, with a pH value of 1-13 and a usage temperature of less than 90 degrees, but its tensile strength is not high. Most foreign filter cloth manufacturers do not use this material. Due to the fact that the pH value of the slurry coming out of the absorption tower is generally between 4-7, and the temperature of gypsum is between 70-80 degrees.

United States with TanzDacotexThe filter cloth is woven with high temperature resistant and alkali resistant polyester silk thread for flue gas desulfurization.

2. Weaving process:

Generally, the weaving process of single filament and double filament blending and satin weaving is used. The advantage of this weaving method is that the surface is smooth, the back is rough, and the size of the front and rear openings is different. The surface holes are large and the back holes are small, which makes it easy to intercept solids and facilitate drainage. The smooth surface makes it more efficient to remove solids from the surface.

Many filter cloth manufacturers' polyester threads contain polypropylene, not polyester material. The filter cloth is affected by the temperature and pH value of the gypsum slurry in the absorption tower, and is prone to deformation and tearing.

2、 Due to the nature of the filter itself:

1. Host flushing system:

Because the washing water used for the filter cloth is process water, it generally does not clog. The filter cake flushing water generally uses process water, filter cloth flushing water return water, and vacuum pump

Circulating water return (using a water ring vacuum pump) mainly consists of circulating water from the vacuum pump and flushing water from the filter cloth, with occasional replenishment of process water. The gypsum content in the return water of the filter cloth washing water is relatively high, which can easily cause blockage of the filter cake washing water nozzle. The pressure of the nozzle in the host flushing system is generally greater than 3 kilograms. When it is less than this value, the flushing effect on the filter cloth cannot be achieved. If it is not cleaned thoroughly for a long time, gypsum will accumulate on the surface of the filter cloth and blockage may occur.

2. The distance between the scraper and the surface of the filter cloth is too large, causing a large amount of gypsum to accumulate on the surface of the filter cloth, making it difficult to clean. Over time, it is also easy to scale on the surface of the filter cloth, resulting in a high rate of surface blockage.

3. Sealing performance of the host:

If the moisture content of the secondary dehydrated gypsum is greater than 10%, the sealing of the host should also be considered. Poor sealing can lead to low vacuum degree in the entire system, and the moisture content of the dehydrated gypsum filter cake is significantly higher, affecting the filtration effect.

The main reasons for this problem are:

A、 The joint of the vacuum chamber may come loose. The vacuum chamber is usually made of high molecular weight polymer, which has strong elasticity and deformation. If it is not fixed in time or not fixed properly, it may cause the vacuum chamber to come loose. In this case, the only solution is to stop the vehicle, put down the vacuum chamber, re glue it, and fix each section of the vacuum chamber.

B、 Leakage at the flange connection below the vacuum chamber. This usually involves blowing a whistle. To solve this problem, the vacuum chamber needs to be lowered after parking, and the gasket condition should be checked. If there is a problem with the gasket, it should be replaced; If it's not a gasket issue, then simply tighten the flange bolts at the leak location.

C、 If the filtrate main pipe leaks, only tighten the bolts at the leakage point. If there is a problem with the gasket, it needs to be replaced after parking.

To prevent vacuum leakage, it is necessary to conduct a vacuum degree test after the system is installed and before the filter cloth is installed. This can control the problem before driving and avoid trouble after driving.

3、 Improper operation causes blockage of the filter cloth

Some power plants are not turned on 24 hours a day and may be shut down. If the filter cloth is not cleaned in a timely manner during shutdown, gypsum will accumulate on the surface of the filter cloth, clogging the gaps on the surface of the filter cloth. This will make it difficult to clean in future use, shortening the service life of the filter cloth and affecting the filtration effect. So when the filter machine stops, be sure to clean the residual gypsum on the surface of the filter cloth first. Keep the surface of the filter cloth clean..

In general, the filter cloth needs to be replaced after being used for more than 10 months, because the filter cloth will deform and shrink after such a long period of normal use; In addition, impurities from the processed material remain in the filter cloth and cannot be washed away. Although the filter cloth is not damaged, it has seriously affected the filtration effect.