Piston operation mode of reciprocating compressors and its impact on safety
Thread Content
The reciprocating compressor for high-pressure hydrogen in the new plant installed by our company adopts a two-stage, single-acting design with oil-minimized lubrication. We invited two manufacturing plants to develop proposals: one of the production plants uses a single-acting design on the shaft side ； Another one uses a single-acting design on the cover side. Operating conditions: inlet and exhaust pressures of 16.5/18.5 MPa, exhaust temperature of 100 degrees, with a medium consisting of 85% recycled hydrogen along with a small amount of hydrocarbons. For axial single-acting design, the manufacturer connects the non-active side to the inlet (with the medium flowing in from above and out from below). Given that the non-active cylinder is connected to the inlet, there are concerns that the accumulation of lubricant over time could pose a risk to the safe operation of the unit; therefore, we recommend switching to a cover-side single-acting design instead. I would like to ask everyone: based on your practical experience, how should one choose the type of cylinder mechanism for similar equipment? I hope everyone will participate in the discussion! Thank you! !
Whether the cover side or the shaft side is used, there must always be a non-active side that is connected to the inlet; therefore, the influence of lubricant cannot be eliminated. To truly eliminate the negative effects of lubricant, oil-free lubrication must be employed； Single-acting cylinders are generally designed to be single-acting on the cover side, as there is a piston rod on the shaft side, which results in a relatively smaller working volume. I don’t understand why one of them was designed to be single-acting on the shaft side! ? It is recommended that both parties follow the lid-side design, and then compare the design options and prices, etc. :lol
Thank you, 2nd floor! We have advised the manufacturer to use a single-acting mechanism on the cover side. Furthermore, since it is difficult to achieve oil-free lubrication for this compressor, and considering the risks of cylinder damage and carbon buildup caused by the absence of lubricating oil inside the cylinders, we suggest that the manufacturer connect the non-operating cylinders to the outlet. Is this approach feasible? Anyone with practical experience in this area, please share your insights! Thank you!
Normally, oil-free compressors are chosen, as this has a significant impact on the purity of the gas
:Oh, I haven’t seen a balanced chamber that uses outlet pressure. Leaving aside the negative effects of this approach (the piston force might **increase**), it won’t achieve the goal intended by the designer. If there is only one interface, then when it’s connected to the inlet, the side without an interface will always be under inlet pressure; and when it’s connected to the outlet, it will be under outlet pressure. The lubricating oil inside the cylinder won’t be carried away in larger quantities just because of the higher pressure! One more thing: even if it can be taken away, what about the side that does the work! How can we ensure that the oil stays on the non-active side and doesn’t flow to the other side? ! :Q I really don’t know which company designed the units for you? !