Details

The biological Liqin process is used to treat domestic sludge (containing corrosive sand and stones) with a solid content of 5%. The filter press is a box type diaphragm filter press with a filtration area of 700 square meters. The moisture content of the treated sludge cake is 35%.

Usage of the original screw pump:

Two imported brand screw pumps are used to rotate for feeding to the filter press. First, one low-pressure alloy screw pump is used for feeding. After working for about two hours, the low-pressure pump stops working when the pipeline pressure reaches 6 kilograms. The other high-pressure alloy screw pump starts and continues feeding for about two hours. When the pipeline pressure reaches 12 kilograms, the feeding is completed. Due to the presence of sand and corrosive substances in the material, the screw pump experiences significant wear and backflow after a short period of use, which gradually prolongs the feeding time and reduces production. If the flow rate of the screw pump cannot meet the process requirements after 2-3 months of use, it needs to be replaced with a set of screws, which costs 30000 yuan. Therefore, the annual usage fee is 120000-180000 yuan, and each maintenance requires 2-3 people and 4 hours.

Usage of the replaced plunger pump:

In 2015, our company replaced a screw pump with a YB400N plunger pump at the Longjiang Sewage Treatment Plant. The current situation is as follows: the plunger pump has a high frequency of plunger operation during the low-pressure feeding stage, with a large feed flow rate and a working time of about 2 hours. When the pipeline pressure reaches 12 kilograms, the plunger frequency gradually decreases. The plunger pump works to maintain pressure and complete the feeding process in about 2 hours. Due to the presence of sand and corrosive materials, the valve plates and rubber seals of the ceramic plungers in the four one-way valves of the plunger pump are prone to damage. According to maintenance records over the past year, a total of three repairs were carried out, with each replacement costing 1500 yuan for valve plates and rubber seals, resulting in an annual usage fee of 4500 yuan. Each repair was carried out by one person, and the working time was 1-2 hours.

Comprehensive evaluation

In the case of equivalent feeding working time, plunger pumps have significantly reduced annual maintenance costs, repair time, and number of repairs by maintenance personnel compared to screw pumps. The annual maintenance cost is only 3% of screw pumps, and the annual repair time is only 15% of screw pumps.