The oil film seal commonly used in earlier compressor designs has been mostly phased out by dgss. The programmable logic controller plc starts the auxiliary ac powerdriven lubricating oil pump. Process gas compressor lube oil and seal oil systems by. Oil and natural gas sector compressors ourenergypolicy. The application of dry gas seal system is recommended. Pdf analysis of mechanical seals for highspeed centrifugal gas. An effective seal is provided at the settleout pressure when the compressor is not running. The compressor seal oil system is designed and furnished with instrumentation similar to the lube oil system shown in figure 154. The separation gas should be filtered to 5 microns solid particles and should be 99. Turbomachinery lubrication and sealing systems play an integral role in keeping. Compressor and sealing system gas compressor scribd. Recovery system that separates gas from the exiting sealoil before routing to the degassing tank recovered gas sent to various outlets. Processdesign considerations for a compressor drygas seal.
The isosleeve cartridge seal creates a liquid film seal by injecting oil between stationary bushings at a pressure higher than the process pressure. However, there is an established machinery population that still requires support systems for oil wetted bearings and seals. Us4477223a sealing system for a turboexpander compressor. Inboard of the dry gas seal is an inner labyrinth seal, which separates the process gas from the gas seal. Lubrication, seal and piping systems for turbomachinery. Apr 21, 2015 the seal oil supply system must be capable of supplying higher seal oil pressure than the highest possible compressor process pressure inboard of the oil seal which may include settle out, or compressor discharge pressure. These systems require auxiliary equipment such as pumps, regulators, filters, and so on for proper operation. The oil system was designed to include a common lube and seal oil system with a pump design pressure of 590 psi. A turboexpander compressor for use in a gas processing system has a seal system that avoids communication of gas with the oil being pumped through the bearings. Alternative solution sealoil gas separation and recoveryuse simple process of separating sealoil and entrained gas with the gas routed to recovery andor use. We also provide accessory skids for water wash, fire suppression, denox and water injection. Industrial compressors are too often manufactured and maintained with identical seals and little understanding for how those seals affect overall performance.
Frick rwf screw compressor pdf screw compressors specialist. The seal oil circulation system is composed of a seal oil reservoir, pumps to pressurize the seal oil, filters to. Flexa seal wants to make your decision process clear and provide the right product for your needs. Low flash point of turbine, compressor and seal oil could pose a. Dec 08, 2016 centrifugal compressors have lubrication systems designed as per api 614 consisting of an oil reservoir, pumps, filter, cooler and oil lines. Outboard of the dry gas seal is a barrier seal, which separates the gas seal from the compressor shaft bearings fig. In case of the existing compressor equips oil film seal, seal oil console shall be replaced with dry gas seal control system. The purpose of the seal oil system is to keep the compressed gas from entering the bearing assembly and escaping from the compressor to the atmosphere. More than 80% of centrifugal compressors today are manufactured with a dgs stahley 2001. Pdf surge detection system for centrifugal compressor.
The seal oil is normally supplied from a combined lube and seal oil system, an example of one such system is shown in. Centrifugal compressor, mechanical seal, seal face. Api 617 compressor api 614 the leader in lube oil and. In the wake of gas compression offshore the problem of contamination of. We are currently experiencing leakage and seal oil coming out of the vent both on the seal assembly as well as on the vent coming out of the seal oil tank. This seal system does not use any circulating seal oil. Double seal arrangements are utilized when product leakage to the atmosphere is unacceptable or for low pressure applications. Recovery system that separates gas from the sour seal oil before being sent to. Includes an oil reservoir, mechanical oil pump, electric fullflow auxiliary oil pump, fixedbundle oil cooler, single fullflow oil filter, safety devices and instrumentation for safe compressor operation assembled and packaged on a compressor base when compressor layout permits.
For a more complete description of dry gas seal principles of operation, see shah 1988. The seal oil is normally supplied from a combined lube and seal oil system, an example of one such system is shown in figure 1. Elliott first began to manufacture oil consoles for its own turbomachinery nearly 80 years ago. Replacing wet seals with dry seals in centrifugal compressors.
Processdesign considerations for a compressor drygas seal system interface chung leong, independent consultant, and sanjiv goyal, fluor enterprises ments. The mechanical face seal uses a liquid, such as oil, to lubricate, cool, and create a positive sealing action to the sealing components during normal operation. Dry gas seal systems for centrifugal compressors page 3 of. Specifying engineers sometimes do not give enough attention to the scope. Sep 11, 2018 dry gas seal system centrifugal compressor,dry gas seals are an integral part of modern centrifugal compressors. Routing centrifugal compressor seal oil degassing emissions to. Overview application of compressors types of compressors reciprocal rotary axialcentrifugal centrifugal compressor system compressor casing, impeller shaft and seals lube oil system seal oil system driver. Centrifugal compressor wet seals seal oil degassing and.
The device has a shaft carried in a housing on bearings with a compressor wheel on one side and an expander wheel on the other side. The seal oil system can be considered as having three. Each system is arranged for seal gas dry, filtered gas supplied to the highpressure side of a selfacting gas seal and secondary seal gas supply clean purge gas supplied to the area between the seals of a tandem selfacting gas seal at the correct volume, pressure, and temperature to rotating equipment components e. Compressor turbine fuel seal oil circulation pump new fuel pressure seal oil degassing drum and demister sour seal oil trap less gas vented to atmosphere atmospheric seal oil degassing drum note. Seal oil uncontaminated seal oil contaminated with gas spinning shaft compressor side inboard process gas leaks through inboard labyrinth seal y s an alternative to the traditional wet oil seal system is the mechanical dry seal system. The only essential difference is how the endsupply control is handled. The seal oil system prevents gas from leaking out of the compressor case.
Dry gas seal systems for centrifugal compressors page 4 of. Manual purpose to be used for selection, application into the system, power and cooling water estimation. Basic seal oil systems engineering photos,videos and. Optimal seal performance depends upon proper selection for the process application. The turbo compressor surge is an unstable operating mode of compression system that occurs at mass flows below the socalled surge line. Contamination of centrifugal process gas compressor lube oil and. From frick manual the first requirement of the compressor foundation is that it must be able to support the weight of the compressor package including coolers, oil, and refrigerant charge. The seal oil system may be a completely separate oil system, however in most cases it is apart of the compressor main lube oil system. Elimination of the wet seal system improves operational safety by eradicating any dangerous build up of hydrocarbon gas in the seal oil. Most hydrogen cooled generator are incorporate the seal oil system, just because to avoid the contact between and air and hydrogen generally pressure of hydrogen in generator around 4bar. Engineers modelled the hydrogen seal systems and used the simulated results to identify the case of their system trips. The lubricant pressures and flows may vary from compressor to compressor depending upon the speed and size. Howden compressor wrv 255 screw compressor manual screw.
A differential pressure is supplied at 35 to 50 psi above the compressor suction pressure. The mechanical seal input shaft seal is the fragile component of any screw compressor. For most companies, it is not economically practical to convert to new bearings and seals to eliminate the oil support system. Centrifugal compressor with lube and seal oil system using voice, video, animation and graphics. At system seals, we take the time to understand the nuances on each piece of equipment and make modifications that carry large resultsresults in reliability, performance, and. A differential pressure is supplied at 35 to 50 psi above. The use of pressurized air from the engine compressor to both seal the oil bearing chamber and supply cabin bleed air provides a mechanism for lowlevel oil leakage in routine engine operations 4. This manual does not for designing centrifugal compressor and those parts. The oil that flows across the outboard ring mixes with the.
This system is designed to keep the seal oil pressure above the sealed gas pressure. Aug 02, 2017 a dry gas seal control system must have an adequate range and controllability to maintain a minimum 16 fps 4. Choosing the correct sealing system for your compressor can be daunting. Recovery system that separates gas from the sour seal oil before being sent to the degassing tank recovered gas sent to various outlets. Centrifugal compressor wet seals seal oil degassing. The seal oil, or seal liquid system figure 5 supplies the mechanical contact and floating ring seals with an adequate flow of seal liquid at all times, correctly ensuring proper function. Pdf oil bearing seals and aircraft cabin air contamination. Flash point lower than 180c could be a prob lem regarding safety.
Dry seals operate mechanically under the opposing force created by hydrodynamic grooves and static. Improve reliability of turbomachinery lubrication and sealing. Low level in seal oil tank if compressor incorporates seal oil system over speed. Sour seal oil vapor recovery system 4 options flare purge 27 psi 65 psi 275 psi boiler. Oil seals are generally grouped into two different groups. Frick rwf screw compressor pdf with instalation information. If the header pressure is low, the standby oil pump starts and maintains oil pressure during operation.
Pressure at the oil header creates starts the drive. In fact, compressor oil seals are not gas seals at all, but rather liquid seals designed to minimize the amount of seal oil that passes into the compressor. A compressors bearings are among vital components of a screw compressor. The instability is characterized by large limit cycle oscillations in compressor flow and pressure rise. Centrifugal compressor wet seals high pressure seal oil circulates between rings around the compressor shaft oil absorbs the gas on the inboard side little gas leaks through the oil seal seal oil degassing typically vents methane to the atmosphere seal oil degassing may vent 40 to 200 scfminute. The group he supervises is responsible for field support during.
The circulated oil entrains and absorbs some compressed natural gas that may be released to the atmosphere during the seal oil recirculation process degassing or offgassing. Low flash point of turbine, compressor and seal oil. Seal oil piping vibration on an oil free screw compressor in. Aug 02, 2017 a clean and dry separation gas is continuously injected into the barrier seal to protect the migration of lube oil from the outboard bearing housing. The mechanical seal seen as occurring in two general areas. In the singlestage compressor, air is drawn in from the atmosphere and compressed to final pressure in a single stroke. The oil that flows across the outboard ring mixes with the bearing lube oil and returns to a lube oil tank. We have a two 2 mw natural gas feed centrifugal compressor barrel type that is still equipped with a seal oil system. The oil is circulated at high pressure to form a barrier against compressed natural gas leakage. Oct 18, 2016 lube oil system in centrifugal compressors. Upgrade to dry gas seal is foreseen but not immediately. Replacing wet seals with dry seals in centrifugal compressors pdf. Low control oil pressure for turbo driven high differential pressure high axial thrust high radial vibration in some cases high temperature after inter cooler or after cooler alarm events all emergency stop conditions will first generate alarm. Configuring lubrication systems turbomachinery magazine.
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