For the purpose of upgrading a cracker in a Chinese refinery a total of five plunger pump skids should be brought into operation by Lewa. Those in charge of the project opted for three triplex and two quintuplex plunger pumps in accordance with the API 674 standard. These pumps are equipped with the new KMC-L pump head with reduced clearance volume. This head consists of a single forging: The suction manifold is integrated as a result, allowing for a reduction in the sealing surface and thus in any potential leak points. An additional advantage is the fact that the suction side can be designed to handle backpressure, eliminating the need for a safety valve in the suction line. The new design makes it possible to realize pressures up to 1,075 bar. All pumps in use have been produced in Germany and mounted to a complete system in the Chinese plant.
These plunger pumps have a drive output of 260 kW and a flow rate of 25 m3/h. The suction pressure loss of the pump heads is very low, therefore a low suction pressure is needed and it is often possible to operate without a booster pump.
A leakage return line from the packing to the suction side ensures that operation has as little leakage as possible. If the process requires, the pump can be equipped with two sealing rings and installed with a flushing or sealing system so that any leakage during operation are entirely prevented.
The new KMC-L type, which is used in all five pumps ordered, consists of just one single forging. As a result, it is exceptionally rugged and features just a few sealing surfaces, reducing maintenance times and limiting potential leakage points. In addition, the new pump head features a modified material selection that enables fluids to be pumped at temperatures up to 200 °C. The redesign reduced clearance volumes in the working space, increasing the efficiency of the pump as a result. In order to further decrease maintenance times, the valves have been arranged vertically, ensuring easy installation and removal and making it unnecessary to dismantle connected pipelines. Even the stuffing box is maintenance-free. Re-tightening and adjustment of the packing is not necessary, since the plunger sealing set—just like the additional sealing rings—is fixed in the stuffing box.