![]() Nevertheless, compressor operating temperatures must never exceed the stipulated or mutually agreed values in order to protect the compressor’s internals. In reality, the Author has seen cases, where this deviation was taken up to ~135 deg.C depending on the manufacturer and believes that this is due to a variety of operating conditions between string test conditions and actual conditions. ![]() In the event that the above design criteria cannot be met, purchaser and vendor shall mutually agree on acceptable bearing metal temperatures. 2.7.1.3.1 of the said document also says, Vendors shall provide bearing temperature alarm and shutdown limits on the datasheets. As per API 617 (7th Edition, 2002), Clause 2.7.1.3, it states,Īs a design criteria, bearing metal temperatures shall not exceed 100☌ (212☏) at specified operating conditions with a maximum inlet oil temperature of 50☌ (120☏). However, this needs to be checked with a dynamic simulation study since over-sizing the Hot gas system can cause the compressor to overheat the bearings and seals. Deviations from Design Criteria for Compressor surge controlĪs a thumb rule, the hot gas system is sized for 50% (max) during the FEED stage. In simple terms, lower response time increases the chances of responding faster to a compressor surge. However, with advances in technology, these timings can be considered at ~100 milliseconds. ![]() During an ESD scenario (e.g., power loss), taking a conservative approach for design purposes, the control output signal from the compressor driver after a trip, takes ~300 milliseconds to reach the Distributed Control System (DCS) and another ~300 milliseconds from the DCS to reach the HGV to open. The hot gas piping should also be laid as short as possible between the discharge line and the suction line to have a fast response. The second image below shows a gas compressor with hot gas recycles whose operating point moved away from the compressor surge line during an emergency shutdown. When such solutions still fail to stop a compressor surge event from occurring, a hot gas recycles (a.k.a HGV) is used as a last resort. In these situations, a necessity arises to recycle more flow for which an additional ASV with quick opening characteristics is installed in parallel to the first ASV. Compressor Surge Control: Hot Gas Recycle ValveĪlthough the anti-surge valve (ASV) is the chief protector, in brownfield projects, often the ASV becomes inadequate to deal with a compressor surge due to the addition of new compressors in parallel or series (e.g., booster compressors), change of plant piping or change of vapor composition. The chief protecting agent of a centrifugal compressor is the anti-surge line/valve that recycles cold gas from the discharge side cooler back to the suction scrubber to keep the operating point away from the surge line. Compressor Surge Control Compressor Surge Control using Anti-surge Valve (ASV)-Cold Gas Recycle The bottom line is: Always avoid a surge in compressors and other rotating equipment. Other bad consequences of the compressor surge are: The consequences of a compressor surge are more mechanical in nature whereby ball bearings, seals, thrust bearings, collar shafts, impellers, etc wear out and sometimes depending on how powerful are the compressor surge forces, cause fractures to the machinery parts due to excessive vibrations. Consequences of Centrifugal Compressor Surge ![]() Very high rotation speed and insufficient flow.Restrictions in the inlet and outlet of the system.Misdistribution of load in the compressor.Various reasons could contribute to a centrifugal compressor surge. The Surge in a centrifugal compressor can be simply defined as a situation where a flow reversal from the discharge side back into the compressor casing occurs causing mechanical damage What Causes Compressor Surge?
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |