Hello everyone, we are currently dealing with issues on a 2-stage reciprocating compressor. The suction pressure at the first stage is 700 Kpa, while the discharge pressure at the second stage is 7000 Kpa. When the compressor trips, it unloads and rapidly depressurizes from 7000 kpa to 1500 kpa in just 70 seconds. This rapid depressurization has led to numerous failures in the orings at the second stage discharge, specifically in the valve caps and gas release areas. Despite trying ED resistance orings, the issues persist. The compressors in question are from the Cooper Cameron (superior) brand. I am currently looking into the possibility that increasing the depressurizing time could potentially resolve the issue. It is crucial that the settle out pressure is lower than the first stage maximum operating pressure to prevent damage to the compressor. If anyone has experience with similar situations, please share your insights. Thank you.
Hello Brighton, I encourage you to get in touch with me so that I can pass on your information to our services department at Windrock. I am confident that Warren Laible will be able to assist you. Thank you, Buddy Lee Regional Sales Manager Windrock, Inc. Knoxville, TN USA 865-388-3802 cell SEO-friendly Version: Hello Brighton, feel free to contact me to connect you with our services department at Windrock. Warren Laible will be able to help you. Thank you, Buddy Lee, Regional Sales Manager at Windrock, Inc. in Knoxville, TN USA. Contact 865-388-3802.
Hey buddy, thank you for your help! I will send you the gas compositions and let you know that we are considering using Elastoline 101, which offers improved resistance to environmental stress cracking in a CO2 atmosphere compared to FR25/90. Thanks once more for your assistance!
Dear Brighton, I find the issue at hand to be quite intriguing. Can you please provide some additional clarification on the following points to help me better understand the problem statement: 1. How long has the compressor been operational? 2. What is causing the compressor to trip instead of unload? 3. Can you provide details on the unload and loading pressures? 4. Does the compressor have an air-cooled or water-cooled intercooler and aftercooler? 5. How long has the problem of gasket/o-ring failure been occurring in the compressor system? 6. Were the intercooler and aftercooler installed in the OEM factory or on-site? 7. If the compressor is located indoors, what is the room temperature during compressor operations? 8. What are the compressed air temperature readings at the inlet and outlet of the aftercooler assembly? Best regards, Md Rumman
Welcome back, Brighton! Md R raises a great question about compressor tripping. When compressing methane or other light gases, O rings may expand over time due to the materials used. This can cause them to become too large in size. Before seeking opinions on the material for ED, please share more data.
Hello Vee and MR, I apologize for the delay. Below are the answers to your questions: 1- The compressor has been in operation for almost a year, with a downtime of 2 months due to orings failure. 2- The compressor has trip set points for LL/HH suction pressure, HH suction temperature, HH discharge pressure, etc. If any of these setpoints are reached, the compressor trips and depressures rapidly through a 2x1" PV in 75 seconds from 7 MPa to 1.5 MPa. 3- I will need to follow up with additional information. 4- There is an air-cooled fin fan cooler at the interstage and aftercooler. 5- Initial issues with orings were due to using viton material, which was later changed to FR25/90 and then Elasto line 101. The problem occurs at the second stage discharge where the highest temperature and pressure are present. 6- The coolers are located outside the compressor skids and were installed on-site. 7- The compressors are housed in enclosures with internal ventilation. 8- Adjusting the temperature set point of the intercooler from 70°C to 50°C lowered the 2nd stage outlet temperature from 165°C to 145°C. The process gas consists of natural gas with 19% mol CO2. Since the second oring failure, the 2nd stage discharge pressure was increased from 6900 to 7600 KPa, and the discharge temperature was reduced from 165°C to 145°C. The blowdown time was also extended from 75 to 180 seconds to minimize stop/start cycles. The permeation of gas into the orings at high pressures is the main issue, suggesting the need to increase the blowdown time further. The compressor receives supply gas from the Condensate stabilizer overhead and operates with only 2 stages. If more information is required, please let me know. What other steps should be taken to protect the orings?
It sounds like you're dealing with a challenging situation there. You've correctly identified the rapid depressurization as a potential issue; it's likely causing quite the stress on the o-rings. Are you using proper anti-extrusion devices on your o-rings? Sometimes, even the highest quality of ED resistance o-rings can fail without an anti-extrusion device, especially under such severe variations in pressure. As for increasing the depressurization time, it might be a plausible approach. However, just remember that slowing down the depressurization rate could lead to the compressor running towards the surge line. Balancing this would be crucial. Lastly, have you looked into alternate materials or designs for the o-rings, perhaps something that can handle the stress better?
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Answer: - The common failures observed in the orings at the second stage discharge include issues with the valve caps and gas release areas.
Answer: - Despite trying ED resistance orings, the issues persist, and now there is a consideration to increase the depressurizing time to potentially resolve the problem.
Answer: - The compressor depressurizes rapidly from 7000 kpa to 1500 kpa in just 70 seconds when it trips. This rapid depressurization has led to multiple failures in the orings at the second stage discharge, specifically in the valve caps and gas release areas.
Answer: - The compressors in question are from the Cooper Cameron (superior) brand. It is crucial to ensure that the settle out pressure is lower than the first stage maximum operating pressure to prevent damage to the compressor.
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