The following is the knowledge about the operation experience of the sludge dewatering system of the stacked screw machine. I hope it will be helpful to everyone.
1. Sludge conveying pump and chemical liquid conveying pump should use screw pump instead of centrifugal pump
The sludge delivery pump of the sludge dewatering system of the stacked screw machine originally used a slurry pump (belonging to a centrifugal pump). During the operation process, the problem that the pump cannot plug the mud or the pump leaks mud often occurs, causing the pump to often need to be flushed during operation, maintenance and repair of the pump The workload is also large. After technical research and actual operation tests, it was found that the use of a screw pump to transport this type of sludge has the advantages of stable flow and pressure, and no plugging or leakage. Later, we conducted frequency conversion control on the screw pump, which greatly improved the sludge flow and pressure. The digital control has created a good prerequisite for the stable operation of the stacked screw machine, which is currently running well.
At the same time, we believe that the liquid pump should also use a screw pump with frequency conversion speed control device. If you choose a plunger pump or a diaphragm pump, due to the high viscosity of PAM, it will adhere to the pump's inlet and outlet spherical check valves, causing the valve Failure, cleaning and maintenance work is relatively large, so far has not been modified, plunger pumps are still used, in the process of operation (guò chéng) often valve failure, the pump is blocked and no medicine (Condition).
2. The filter belt deflection device should be installed with anti-mud device
The phenomenon of deviation of the filter belt often occurs in the initial stage of the operation of the stacked screw machine, which often causes the filter belt to be damaged due to being caught in the squeeze roller, which greatly reduces the service life of the filter belt. Later, after analysis, we found that the main reason for the deviation of the filter belt was caused by the failure of the filter belt adjustment device to enter the mud. After the installation of the mud prevention device, the problem of the deviation of the filter belt was solved.
3. The filter belt should use the filter belt with the interface method as the adhesive connection method, and should not use the filter belt with metal buckle and steel wire connection method.
The filter belt of the metal buckle wire connection interface (interface) is constantly worn by the scraper during the actual operation, and it is easy to break from the interface, causing the mesh belt to be damaged. It must be replaced afterwards. The operating cycle is only 3 months On the left and right, when the filter belt deviates, even one month the filter belt breaks. After replacing the filter belt with the adhesive connection method, the problem was solved, and the operating period of the filter belt was increased to 6 months to 1 year. The main reason is that this type of filter belt interface is very flexible and not easy Get injured.
4. The tension of the lower filter belt should be less than the tension of the upper filter cloth
The difference in tension between the upper and lower filter belts has a significant effect on the sludge dewatering effect. The side with higher pressure will press the mud cake to the side with lower pressure. Adjust the tension of the filter belt so that the tension of the lower filter belt is less than that of the upper filter belt, which can increase the amount of sludge that the lower filter belt can peel freely and increase the rate of cake formation. In the actual operation process, we adjusted the tension of the upper filter belt to 40-50 psi and the tension of the lower filter belt to 30-40 psi, and achieved a good sludge dewatering effect.
5. The pressure of the filter belt flushing water (specifically: pressure) should be increased, and the flushing pipeline should be installed at the necessary position to ensure the filter belt washing effect
During the sludge dewatering operation of the helical screw machine, the moisture content of the mud cake is often high, which causes the mud cake to seriously fall out during the transportation process, which affects the environment and does not meet the environmental protection requirements. The technicians found that one of the main reasons is that the filter belt is not washed and there is a blockage phenomenon, which causes the filtered water to be blocked, resulting in a high moisture content of the mud cake. After increasing the pressure of the filter belt washing water from the original 0.6Mpa to 0.8Mpa, and adding a washing water pipe before the filter belt enters the gravity dewatering zone, the sludge dewatering effect is improved, and the mud cake moisture content is also obtained Down.
6. The belt speed of the filter belt should be adjusted in time to ensure the sludge dewatering effect
The belt speed of the filter belt also has a greater influence on the sludge dewatering effect. When the water content of the sludge is high or the mixing effect of the sludge and the chemical liquid is not good, the belt speed should be reduced to extend the filtration time of the gravity dewatering area. To prevent the sludge from squeezing out from both sides of the filter belt during the pressing stage. Under normal circumstances, the belt speed is 4-6m/min, and the dehydration effect is better.
7. The dosage and concentration of PAM dosing water is too small to affect the sludge removal effect
According to the actual operation experience, when the sludge dehydration effect is not good, the water content of the mud cake is generally large. The main reason in the process is that the PAM drug dosed in the wastewater treatment process is insufficient or the concentration is relatively high. Small, usually the amount or concentration of PAM should be increased. If a good sludge removal effect cannot be achieved through adjustment, an experiment should be conducted to determine. At present, the concentration of PAM used is (0.04-0.06)%, and the effect is good.
8. The static mixer should be cleaned regularly, and should be replaced when the wear and tear (a basic type of component failure) is serious
The mixer of sludge and liquid medicine uses a spiral static mixer. In actual operation, it is found that when the static mixer is clogged, the problem of uneven and incomplete mixing of sludge and liquid medicine will occur, and the sludge will be dehydrated. The effect has a great impact, so we recommend that the static mixer should be cleaned regularly.
9. The drainage channel of gravity dehydration area should be cleaned in time
During the operation of the stacked screw machine, the moisture content on both sides of the processed mud cake is normal and the middle moisture content is relatively high. After technical research and analysis, it is found that the main reason is that the trace sludge of the filter belt leaks and accumulates for a long time. In the ribs under the filter belt in the gravity dehydration zone, the cleaning failed to be in place during cleaning, resulting in blockage of the water channel in the middle of the filter belt, resulting in difficulty in dewatering sludge in the middle of the filter belt and the consequence of high water content. Therefore, we recommend that the drainage channels in the gravity dehydration area should be cleaned in time to avoid affecting the sludge dehydration effect.