What are the advantages and disadvantages of choosing two-cylinder and three-cylinder slurry pumps?

I have visited many manufacturers. Those that produce slurry pumps mostly use three-cylinder single-acting pumps for high-pressure slurry pumps (both Qihao and Fronova use this type), while those that produce low-pressure slurry pumps generally use two-cylinder double-acting pumps. Only a few manufacturers produce three-cylinder single-acting low-pressure coal slurry pumps. As for why it is configured this way, I’m also waiting for a professional answer.

I have a guess – could it be because high-pressure coal slurry pumps require higher stability?

High-pressure coal slurry pumps, including three-cylinder single-acting pumps and two-cylinder double-acting pumps, are related to the gasification process of water-coal slurry/coal-sludge slurry. Generally speaking, three-cylinder single-acting pumps are more suitable for top-mounted single-nozzle gasification, as this type of pump results in less pulsation in the coal slurry flow； However, in the multi-nozzle gasification process, a double-cylinder double-acting pump is definitely more appropriate, as this process requires that there be as little flow difference as possible in the coal slurry. Regarding the differences between high-pressure slurry pumps and low-pressure slurry pumps, I suggest the original poster search previous posts; I have also replied to them before. Personally, I believe that to understand the operating principles of high-pressure and low-pressure slurry pumps, as well as pumps with a certain number of cylinders and their functions, one should first grasp the structure and working principles of these devices, and then understand the process requirements. Once these two aspects are understood, the earlier issues will no longer be a problem…………

I like such in-depth replies. :)

In the case of single-acting systems, a three-cylinder design naturally results in less pulsation than a two-cylinder design. However, in double-acting two-cylinder systems where the crankshafts are arranged at 90 degrees to each other, the pulsation is even less than that in a single-acting three-cylinder system. So from this perspective, it seems a bit illogical.

I think pumps with three cylinders and single-acting cylinders are suitable for transportation under medium to high pressure conditions, while pumps with two cylinders and double-acting cylinders are suitable for pipeline transportation under low pressure conditions. A single-cylinder, single-acting pump has three piston rods connected to one crankshaft; during operation, these piston rods exert both thrust and pull forces on the crankshaft. The loads associated with these forces over their respective strokes are quite significant for crankshafts operating under medium to high pressure conditions. This is evident from the GLOST system installed in third-generation Qihao pumps (I’m not sure if the name is correct; it’s an oil system designed to reduce the load on the crankshaft). From the perspective of the operation mode of single-cylinder single-acting pumps, it is impossible for the maximum pulling or pushing forces from any two piston rods to act on the crankshaft at the same time; this is crucial for the safe operation and service life of the pump. It is also this feature that enables single-cylinder single-acting pumps to be used in high-pressure transportation applications. In a double-cylinder, double-acting pump, where one crankshaft is connected to four piston rods, it is inevitable that two piston rods on the same side will exert the maximum tensile or compressive load on the crankshaft. If such a pump is used for high-pressure transmission, the strength of the crankshaft must be extremely high; so high that no suitable material available today can be used to manufacture it. Currently, single-cylinder single-acting pumps are commonly used for medium and high-pressure transmission, while double-cylinder double-acting pumps are used for low-pressure transmission. Occasionally, single-cylinder single-acting pumps are used for low-pressure transmission as well, but double-cylinder double-acting pumps are hardly ever used for medium and high-pressure applications. I think this is also one of the important reasons. I have been to many units equipped with four nozzles, and without exception, they all use single-cylinder, single-acting pumps for high-pressure slurry pumping. Whether it’s Chi Hao pumps or Fenoa pumps, they are all of the single-cylinder, single-acting type; I have not seen any unit with four nozzles that uses double-cylinder, double-acting pumps for high-pressure slurry pumping.

Thank you for all that. However, both the New Energy Phoenix and Yankuang Guotai four-nozzle high-pressure coal slurry pumps with 4.7 MPa pressure are double-cylinder, double-acting types, while the Luhua Texaco pump is a three-cylinder, single-acting type. As for what my brother mentioned, are there any available materials on the optimization of the stress structure of the Qihao three-cylinder crankshaft? Could I borrow them?