Daily Failure Of Belt Filter Press In Sri Lanka

The belt filter press is mainly composed of a distribution device, dehydration device, automatic dosing system, air compressor, and air-electric control system. In the process of operation, once the coordination between the various parts is wrong, it is easy to malfunction. The more common ones are the filter belt in Sri Lanka running the mud and the low solid content of the mud cake. Here is an analysis of the causes and solutions for these two problems.

The filter belt runs mud

When the moisture content of the sludge to be dewatered is too high, the sludge will overflow from both sides of the filter during the operation. The reason is that the liquid slurry has high fluidity during the transition from liquid to semi-solid. The pulp will overflow from both sides of the roller. The common reasons that cause the filter belt to run out of mud are as follows.

1. The flocculation effect of sludge is not ideal

Poor sludge flocculation will cause the capillary water to be unable to be converted into free water and be stripped off in the gravity zone. Therefore, the fluid sludge can easily escape after it enters the squeezing zone and is squeezed. To solve this problem, an appropriate amount of PAM solution can be added according to the flocculation of the sludge and the moisture content of the sludge cake sludge.

2. Low mud concentration is the main reason

The sludge concentration refers to the solid content of the sludge. When the solid content of the sludge is lower than a certain level, the dewatering performance of the sludge is poor and the amount of flocculant will increase. When sludge with low solid content enters the belt filter press, it may leak and the filter belt cannot be pressed out during operation. This problem can be solved by turning off the aeration and maximizing the sludge concentration time.

3. The filter belt is arched

The arching of the filter belt means that the two filter belts wound on the surface of the roller do not overlap, and the outer belt is arched or the lower belt is open. Because the tension of the filter belt is not uniform, the running resistance cannot be overcome, and the filter belt is slack, causing the filter belt to arch. The solution is to check the running status of the adjacent rollers at the camber and maintain the bearings. Or check the tensioning system of the arched filter belt to reduce the resistance of the tensioning guide rod. The tensioning air pressure can also be adjusted to make the tension of the two filter belts at a moderate level.

4. The air pressure is too high

After the flocculated material enters the extrusion section, it is extruded by strong pressure before it reaches a stable state from the flow state. This is caused by the excessive pressure of the filter belt under the action of the cylinder. At this time, the air pressure should be adjusted to a suitable range.

The treated dehydrated cake has low solid content

The dewatered sludge has a low solid content, which will cause the wet sludge to stick to the filter cloth and be difficult to remove, which increases the difficulty of the sludge dewatering operation. At the same time, the high water content will increase the cost of sludge treatment. The main reasons for the low solid content of the sludge cake after sludge dewatering are as follows.

1. The belt speed is too fast

If the filter belt speed is too fast, it will cause insufficient time for sludge pressing and pre-dehydration, which will make the mud cake thinner and decrease the solid content. The solution is to reduce the belt speed.

2. The amount or type of flocculant is not suitable

The wrong choice of flocculant will cause changes in the properties of the sludge or the amount of sludge inflow, resulting in a decrease in the dewaterability of the sludge. At this time, the test should be carried out again to select the appropriate type or dosage of the flocculant.

3. The tension of the filter belt is too small

If the filter belt tension is too small, the squeezing force of the sludge is insufficient and the solid content of the sludge cake after dewatering is reduced. At this time, the tension of the filter belt should be appropriately increased, and the pressure of the belt filter press is generally adjusted to 0.5-0.6 MPa.

4. The filter belt is blocked

The clogging of the filter belt will cause the water to be unable to filter out and increase the moisture content of the dewatered sludge. At this time, the machine should be shut down immediately, and the sludge on the filter belt should be flushed before putting it into operation.

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