Cracks in the cylinder block of reciprocating air compressors
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Dear colleagues and peers, I have a question I’d like to ask: Our unit has a reciprocating air compressor of the model VW-60/7, manufactured by Shengjian, which is primarily used to supply air for production purposes. The rated outlet pressure is 0.7 MPa; in actual use, the system pressure can be maintained at 0.5–0.55 MPa. I’ve been using it for about 9 years. During this period, cracks have appeared in the first cylinder block during operation, resulting in water entering the cylinder on three occasions. It occurs every few years. I always thought that the quality of the cylinders was just that, and since the air compressor kept running continuously, no in-depth analysis was done when it broke down. It still seems to me that there must be some issue caused by its use. The problem still lies in cracks appearing on the cylinder block on the side of the primary intake. I’m not sure if anyone else has encountered this situation; please help analyze it below.
I guess it’s a problem with the cylinder block material. The primary air inlet supplies cold air; the cylinder temperature is on the high side. Cracks are likely to appear, right? The temperature of the cooling water in your system might be high, right? I’m just guessing randomly; if I’m wrong, please don’t take it personally!
Reply to 2# shwg-2008: I agree with your view that the cylinder temperature is on the high side. In any case, I think the cracks must be caused by the interaction of cold and hot air; as you said, the inlet side is the source of cold air. The next step is to determine the cause of the high cylinder block temperature. The cooling water is fine; this can be ruled out. Well, I suspect the additional reasons are as follows: 1. Air leakage in the outlet valve (detected during previous inspections); 2. Severe wear of the piston rings and support rings (new piston rings and support rings were just installed); 3. Additionally, the quality of the new piston rings and support rings was poor – they wore out after just a few days and stuck to the cylinder walls, causing wear on the piston and cylinder surface. I wonder how to determine the quality of these piston rings and support rings?
How is the quality of piston rings and support rings determined? There should be professional standards for this. Requirements for the support ring: hardness, high-temperature resistance, and wear resistance. It must have a certain lifespan under a certain load. So it is directly related to its material. The main components inside are graphite and polymers. It is mainly resistant to high temperatures and wear. Piston rings primarily serve a sealing function, and they possess high-temperature resistance, elastic deformation capacity, and wear resistance. You can check the relevant specifications and have the material tested at a materials research institute. You mean the quality of those rings is poor, so they’ve stuck to the cylinder walls? Is there still a problem with the temperature inside the cylinder? The temperature tolerance of any material has a certain limit. By the way, are there any issues with the cylinder liner material and wall thickness of the compressors in your company? Have you asked the manufacturer whether such problems with your equipment are normal? As far as I know, ordinary cylinder liners last for about two to three years, after which the inner diameter of the liner wears out, resulting in low gas generation efficiency. It needs to be replaced.
Another possibility is that the cooling water contains high levels of impurities, leading to scaling on the cooling surfaces and preventing effective heat dissipation. The internal temperature is high. The cooling water temperature is not high.
Thank you for everyone’s ratings. OP, am I right? Have you guys checked it?
The compressor in your facility suddenly malfunctioned during operation, followed by a water treatment failure. Or in other words, there is a water supply interruption during operation. If that’s the case, it’s easy to explain: after the water supply is cut off, the temperature of the cylinder jacket rises, and then when cooling water is suddenly injected into the cylinder, the cylinder contracts abruptly due to this temperature change, which naturally leads to cracks.