A multistage centrifugal compressor has primary dry gas seal means for preventing leakage of working gas from a machine inner side, and secondary dry gas seal means for backing up the first dry gas seal means. Dry gas seal construction and operation for centrifugal compressor. Solar is not aware of any control techniques used for vented emissions from centrifugal compressor gas seal systems other than the two options discussed in the white paper. Centrifugal compressor wet seals seal oil degassing and control. Compression process of gas in centrifugal compressor gas compression process is presented in enthalpy versus entropy chart. Over 80 percent of centrifugal gas compressors manufactured today are equipped with dry gas seals. Additionally, the risk of process gas being released into the atmosphere in case of seal failure is limited. The part number convention for ordering the dry gas seal rulepak is as follows. Several process stages and side streams can be included in each casing depending on process requirements, including intercooling. Process gas seal support gas seal support systems are designed, built and tested per api 614. Dry gas seals have been applied in process gas centrifugal compressors for more than 20 years. All of the seals are john crane 28at tandem seals with a process labyrinth and separation labyrinth. There are 35 suppliers who sells compressor dry gas seal on, mainly located in asia. Centrifugal compressor spiral dry gas seal simulation working.
Dry gas seal systems for centrifugal compressors page 2 of. Despite the 20year trend of increasing dry gas seal applications, and industry accepted standard for gas seal support system design does not exist. Part 1general requirements, contains information pertinent to all equipment covered by the other parts of. 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 vents methane to the. Replacing wet seals with dry seals in centrifugal compressors. Replacing wet seals with dry seals in centrifugal compressors executive summary centrifugal compressors are widely used in production and transmission of natural gas. Gas enter compressor through suction nozzle 1 at ps p1 measured as total pressure and become p2 as static pressure in isentropic. Seals on the rotating shafts prevent the highpressure natural gas from escaping the compressor casing. Dry gas seal systems for centrifugal compressors august 2, 2017 july 1, 2019 ct2 staff centrifugal compressor, dry gas seals, reliability, seals the faces of a dry gas seal can contact during slow roll if hydrostatic, or hydrodynamic forces are not adequate to achieve seal face liftoff. The installed dry gas seal set were just installed 10 months ago in.
Unless a flare gas recovery unit is available, or the gas is reintroduced at the compressor suction, gas losses can be as high as 30 times the equivalent dry gas seal loss. Over 80 percent of centrifugal gas compressors manufactured. Dry gas seal system design standards for centrifugal. Our industry milestones include the first highpressure compressors for ammonia and urea plants, the most powerful compressors for offshore applications over 30,000 hp and reinjection compressors with delivery pressures as high as 10,000 psi 700 bar. Centrifugal compressor spiral dry gas seal simulation working at reverse rotation. Double dry gas seal systems as compared to tandem systems eliminate the. Advances in dry gas seal technology for compressors. Compression process of gas in centrifugal compressor describes with fig. All compressor internals are arranged as a bundle that can be pulled horizontally out of the casing to allow easy access for inspection and maintenance. Dry gas seals iso carbon oil film seals labyrinth seals performance and capacity controls elliott single stage centrifugal compressors operate in a wide range of conditions due to the standardized impeller design and the vaneless diffuser.
This configuration eliminates the need to remove gas piping. Several potential sources of dry gas seal contamination will be analyzed, drawing from actual field experience, and various means of increasing dry gas seal reliability. Pdf unidirectional dry gas seal may experiences reverse rotation when equipped in a centrifugal compressor. Gtseries centrifugal compressor for air and process gas applications atlas copco gtseries integrally geared centrifugal compressors feature innovative gearbox and impeller designs for air and process gas applications up to 205 bar. Oct 03, 2012 ensure the gas is clean and dryexternal gas for extended reliability filter filtered process gas clean dry seal gas is the module most importantprocess gas gas should be filtered fi fi to around 1 micron coalescing filters can be used to dry the gas heaters can be used to provide superheat heat tracing should be used to. Elliott offers a wide variety of seal options including. Inadequate fuel gas pressure during start up typical conditions on inboardoutboard seal will include.
Aug 02, 2017 dry gas seals are an integral part of modern centrifugal compressors. Trouble shooting the problems of dry gas seals and systems. Contamination is a leading cause of dry gas seal degradation and reduced reliability. Us7854587b2 centrifugal compressor and dry gas seal system. Dry gas seals operate with clearances measured in microns, much less than the thickness of a human hair. The scope of supply is virtually unlimited and fully automatic. Dry gas seals 101 presentation free download as powerpoint presentation. System designs can be based on differential pressure control, flow control or other control methods. Dry gas seal systems for centrifugal compressors page 2. Main buffer fuel gas is provided in the seal gas line if the compressor discharge pressure is not high enough or the process gas is not suitable to be used as seal gas. Inadequate fuel gas pressure during start up typical conditions on inboardoutboard seal will include running. Ensure the gas is clean and dryexternal gas for extended reliability filter filtered process gas clean dry seal gas is the module most importantprocess gas gas should be filtered fi fi to around 1 micron coalescing filters can be used to dry the gas heaters can be used to provide superheat heat tracing should be used to. Despite the fact that the use of dry gas seals in process gas centrifugal compressors has increased dramatically over the last 20 years, the technology remains misunderstood by many in the industry. Multistage centrifugal compressor general questions.
Dry gas seals are considered the standard sealing technology between the process gas and lubrication systems in centrifugal compressors. These standards are based on over 20 years of experience in the area of gas seal system design, drawing from actual field experience of thousands of compressors. Replacing wet seals with dry seals in centrifugal compressors pdf. The top countries of supplier is china, from which the percentage of compressor dry gas seal supply is 100% respectively. Pdf dry gas seal system design standards for centrifugal. Dry gas seals 101 presentation gas compressor bearing. This paper will examine the experiences of one centrifugal compressor oem in. The compressor was kept stopped for an investigation, which confirmed that an actual dry gas seal dgs failure had happened.
In some cases a retrofit to a dry gas seal can easily be justified. Dynamic dry gas seals another of the compressor s technical features are its dynamic, contactless dry gas seals. This paper presents the philosophy of one centrifugal compressor and dry gas seal original equipment manufacturer oem. Gas emissions from wet seal centrifugal compressors have been found to be higher than dry seals compressors primarily due to the offgassing of the entrained gas from the oil. With aura, operators gain access to localized technical expertise from the largest global service network in the industry with over 200 service engineers. The present invention relates to a centrifugal compressor using a dry gas seal system for protecting seal means. Manual or customerspecified systems can be engineered for most gas seal types. Although the use of dry gas seals dgss in process centrifugal compressors has become an industry standard since the 1980s end users are still facing operational issues related to premature failur. Jun 16, 2014 solar is not aware of any control techniques used for vented emissions from centrifugal compressor gas seal systems other than the two options discussed in the white paper.
Scribd is the worlds largest social reading and publishing site. Mechanical upgrades to improve centrifugal compressor operation and. The use of dry gas seals in process gas centrifugal compressors has increased dramatically over the last twenty years, replacing traditional oil film. Dry seals, which use highpressure gas to seal the compressor, emit less natural gas up to 6 scfm for a two seal system, have lower power requirements, improve. Premature dry gas seal failure on a sales gas centrifugal. Moreover, our compressor design supports api specifications. A multistage centrifugal compressor has primary dry gas seal means for preventing leakage of working gas from a machine inner side, and secondary dry gas seal means for. The outboard labyrinth reduces warm seal gas leakage to the process side. I tried to find answers on the web for these questions but i either failed to find anything or i found conflicting responses. For more information on ordering rulepaks in general, please consult specification and ordering information document 175487. Trouble shooting the problems of dry gas seals and systems in. Centrifugal compressor spiral dry gas seal simulation. Compressors built prior to the 1980s used earlier seal technology with varying amounts of success. Unidirectional dry gas seal may experiences reverse rotation when equipped in a centrifugal compressor.
Technical data and information for the epa white paper on. A wide variety of compressor dry gas seal options are available to you, such as metal. The principles of operation of dry gas seal faces, the methods of seal gas control, slow roll and challenging sealing environments. Hence the proper design and monitoring of dry gas seals are most important. For dry gas seals in rotary compressors equipment in gas production. Nov 04, 2016 with aura, operators gain access to localized technical expertise from the largest global service network in the industry with over 200 service engineers located worldwide. Technical data and information for the epa white paper.
Pemex wet seals leak little gas at the seal face most emissions are from seal. Compressor dry gas seals posted in industrial professionals. Sealing gas pressures remain low enough that a dedicated compressor for supplying the sealing gases is not needed. The switch of oil wet seals to dry gas seals in centrifugal compressors is a good example of this continuous advancement. Dry gas seals, also known as gas lubricated mechanical seals, are the preferred solution for lng compressors in onshore and offshore applications because of their superior capabilities in reducing power dissipation and leakage at shaft ends. Dry gas sealing solutions for highpressure compressor.
This gas is not suitable for sale and is either released to the atmosphere, flared, or routed back to a process. Solar cautions the use of flaring with gas seal vented emissions due to risk of. Centrifugal compressor seals are a critical subsystem, carefully integrated into the overall unit design. Solar cautions the use of flaring with gas seal vented emissions due to risk of the potential explosive hazard and backflashing. Aug 02, 2017 dry gas seal systems for centrifugal compressors august 2, 2017 july 1, 2019 ct2 staff centrifugal compressor, dry gas seals, reliability, seals the faces of a dry gas seal can contact during slow roll if hydrostatic, or hydrodynamic forces are not adequate to achieve seal face liftoff. Dry gas seal technology has demonstrated reliability and cost savings for most applications of new compressors. Hello, i am currently involved in hazop and lopa studies involving dry gas seal systems associated with a number of centrifugal compressors we have on site. Insufficient pressure of the buffer gas during start up can cause the process dirty gas inside the. Dry gas seals are an integral part of modern centrifugal compressors. The dry gas seal rulepak is available for system 1 software installations of version 6.
This paper proposes a set of gas seal system design standards for process gas centrifugal compressors on the basis of safety, reliability, and economics. This paper will examine the experiences of one centrifugal compressor oem in this regard. Infield tests show that compared to standard carbon ring seals dynamic dry gas seals release a fraction of co2 into the. Pdf centrifugal compressor spiral dry gas seal simulation. Specifying engineers sometimes do not give enough attention to the scope. Compressor manufacturers prefer them for their capacity to simplify the seal control panel and make it.
Dry seals keep gas from escaping while rotating with the shaft. Dry gas seal systems for centrifugal compressors page 3 of 5. This instructorled 4day course introduces the principles of dry gas seals and seal support systems for centrifugal compressors, including dry gas seal installation, operation and maintenance. Specifying engineers sometimes do not give enough attention to the scope, definition and selection of the most appropriate gas seal type, its control system and auxiliaries for a given service application. Dec 28, 2006 centrifugal compressor seals are a critical subsystem, carefully integrated into the overall unit design. Feb 24, 2015 compressor dry gas seals posted in industrial professionals. Centrifugal compressor wet seals seal oil degassing and. Mar 23, 2019 unless a flare gas recovery unit is available, or the gas is reintroduced at the compressor suction, gas losses can be as high as 30 times the equivalent dry gas seal loss.
Common dry gas seal failures are discussed below along with their causes and remedies. Our customers realize cost savings by eliminating expensive seal oil systems and the need to dispose of contaminated oil. The seal gas supply skids were designed by another. The turboexpander dry gas seal consists of the conventional dry gas seal mating ring and primary ring, an outboard labyrinth, an inboard labyrinth, and the cavity to be vented, if desired. The dry gas seals employed in dresserrand centrifugal compressors represent a significant advance in shaft sealing. Learning is through an effective blend of classroom theory sessions and practical, handson activities. Dry gas seal system centrifugal compressor,dry gas seals are an integral part of modern centrifugal compressors. Pdf design, operation, and maintenance considerations for. Dry gas seals for lng compressors modern pumping today. The seal gas supply skids were designed by another vendor. Insufficient pressure of the buffer gas during start up can cause the process dirty gas inside the compressor to go through the dry gas seal faces. Dry gas seal for compressors free download as powerpoint presentation.
Api 692, first edition standard is expected to cover compressor dry gas seals. This paper presents the philosophy of one centrifugal compressor and dry gas seal original equipment manufacturer oem in regard to gas seal system design standards. Gas seal buffer system engineering and manufacturing are available at elliotts donora, pennsylvania, plant. This paper describes how the reverse rotation effects on the spiral unidirectional dry gas seal performance and pressure distribution inside the gas.
Driving centrifugal compressor technology over the past century, atlas copco has built close relationships with customers around the globe. Each seal receives its own sealing gas and has its own venting mechanism. Hello all, i have a couple of general questions that are not really related to each other, however, i thought that making separate posts for each question will not be efficient. Dry gas seals, also known as gaslubricated mechanical seals, are the preferred solution for lng compressors in onshore and offshore applications because of their superior capabilities in reducing power dissipation and leakage at shaft ends. Gas seals eliminate the need for complex and costly seal oil systems, and the ongoing maintenance associated with them. Up to 75 scfm per seal have been reported for a 10,000 hp compressor in average condition. Multistage centrifugal compressor general questions posted in industrial professionals. Pdf improving dry gas seal reliability researchgate. Singleshaft centrifugal compressors compressors and. These dry gas seals ensure that co2 remains inside the compression loop and is delivered to the plant.
Gtseries centrifugal compressor for air and process gas. Apr 27, 2011 common dry gas seal failures are discussed below along with their causes and remedies. The pros and cons of dry gas seals installation in an. Centrifugal compressors baker hughes, a ge company. The installed dry gas seal set were just installed 10 months ago in september 2011, following a complete k002d. 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.
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