Systems and methods according to these exemplary embodiments provide sealing mechanisms for centrifugal compressors. Double seal support system with process gas as seal gas supply seal application. Dgs, the correct operation of the sealing system is. The gaspac seal is a proven design using either the bidirectional tgroove technology or the advanced pattern groove apg technology. Pdf improving dry gas seal reliability researchgate. Gas seal vendors have strict requirements for the seali ng gas quality. Inner seal faces primary ring carbon outer seal faces mating ring silicon carbide mating ring silicon carbide nitrogen barrier gas inlet dry gas seal cross section drawing. Hydraulic cylinder manufacturerepair increasing value for repair shops and their customers. Alternative solution sealoilgas separation and recoveryuse simple process of separating sealoil and entrained gas with the gas routed to recovery andor use. Field applications of dry gas seal designs were completed in 1952. Components dry gas seals dry gas seals, an alternative to isosleeve and isocarbon seals, eliminate the need for oil supply systems.
Aug 02, 2017 a continuous supply of the seal gas at steadystate conditions is essential to proper functioning of the dry gas seal. Gas conditioning units gas conditioning unit for noncontacting gas seal for turbo compressors. Api 692 does not apply to other types of shaft seals such as clearance seals, restrictive ring seals, or oil seals. Worldwide turbomachinery support compressor dry seal booster. This intensive 1day course is customized and designed for practitioners, engineers, and specialists who worked in epc companies andor operating companies to familiarize them with api 614692 dry gas seal principals and concepts used mainly in the centrifugal gas compressors. An article on dry gas sealing systems what is piping. Gas lubricated used for twenty years ago almost of the compressor use them 3. The leading manufacturer of dry gas seal boosters gas compression systems, inc. Pdgs10 the pdgs10 is the standard seal for high pressures up to 220 bar 3,191 psi. Type 28 compressor dry running gas seals have been the industry standard since early 1970 for gas handling turbomachinery. The dry gas seal panel is a critical component in a dry gas seal system. Gas seal solutions for high reliability chesterton. General this standard covers the minimum dry gas sealing system requirements in association with axial, centrifugal, and rotary screw compressors and expanders for use in the petroleum, chemical, and gas industry services as described in api 617 and api 619. 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.
Chesterton gas seals offer advanced, patented sealing technology in a compact and easytoinstall design. Despite the 20year trend of increasing dry gas seal applications, and industry accepted standard for gas seal support system design does not exist. Dry gas seal applications for high pressure youtube. The dry gas seal was marketed as a simple solution to seal oil system reliability issues, but in reality, when one considers all the possible process and operational related. Dry gas seals were introduced in the late 1960s but did not gain wide acceptance until 20 years later as the ultimate solution to compressor seal oil system problems. Also, some modifications are required for the existing rotor and casing. 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. Elliott dry gas buffer systems consist of a primary and separation gas supply to ensure that the gas face seals have a sufficient amount of filtered gas at all operating points. Aug 02, 2017 dry gas seals are an integral part of modern centrifugal compressors. Dry gas seal system design standards for centrifugal. All designs use buffering with dry gas, supplied through control and purification systems. Mechanical seal technology and selection eagleburgmann.
Gas seals eliminate the need for complex and costly seal oil systems, and the ongoing maintenance associated with them. Centrifugal compressor wet seals seal oil degassing and. The dry gas seals employed in dresserrand centrifugal compressors represent a significant advance in shaft sealing. The permian basin in west texas and eastern new mexico is one example of how john crane uses type 28 vl dry gas seals to seal supercritical co 2 for eor applications. When the compressor is not running and that flow is interrupted, the seal is.
The use of dry gas seals requires a system designed to supply sealing gas to the seal as a sealing and working fluid for the running gap. A dry gas seal is a mechanical seal that uses a sealing gas to create a barrier between the process gas and the atmosphere. Sealing gas pressures remain low enough that a dedicated compressor for supplying the sealing gases is not needed. Compressors built prior to the 1980s used earlier seal technology with varying amounts of success. The application of dry gas seal system is recommended. What is api 692 1st edition, compressor dry gas seals. Under dynamic condition, reverse pressure can result major damage to the dry gas seal system. Dry gas seal arrangement for zeroemission, zeroleak environment. It is characterized by very low leakage and sets the standard in the market for lowemission compressor gas seals. Over 80 percent of centrifugal gas compressors manufactured. A dry gas seal is a type of mechanical seal used to contain gases without incursion from contaminants or inadvertent release of the gas into the surrounding environment. Types of dry gas seal dry gas seal systems gas seal contamination how dry gas seal works. Our innovations in secondary seals are designed to eliminate the causes of oring hangup, the most common operational challenge in other compressor gas seal designs.
Dgs application rangejohn crane dgsoperating range temp. A dry gas seal control system must have an adequate range and controllability to maintain a minimum 16 fps 4. Reverse pressure under static condition will result in an increase in static leakage. An ideal system provides the required flow to a dry gas seal to ensure reliability and prevent the release of process gas. Each aesseal gas conditioning system contains the key api modules plus various enhancements derived from our own field experience, to ensure the highest degree of compressor dry gas seal reliability and longevity. Dry gas seals have been applied in process gas centrifugal compressors for more than 20 years. Type 28exp dry gas seals john crane mechanical seals. The faulttolerant design of our gas seals offers higher reliability, reduced gas consumption requirements, and allows for gas supply disruptions. This book presents a complete guide to the technology, from the principle of gas seal operation to lessons learned from actual field experience. There are two basic types of gas seal systems, differential pressure. Recovery system that separates gas from the exiting sealoil before routing to the degassing tank recovered gas sent to various outlets. Replacing wet seals with dry seals in centrifugal compressors. Dry gas seal system centrifugal compressor, dry gas seals are an integral part of modern centrifugal compressors.
Dry gas seals for compressors and auxiliary equipment, sms and shutdown safety systems duration. The use of dry gas seals requires a system designed to supply sealing gas to the seal as a working fluid for the running gap. To prevent this, to prevent this, s e p arati o n ga s i s inj e ct e d b e t ween t h e s ea l a nd b e a ring. Absorb the pressure drop and vent to atmosphere secondary seal. Wet systems require 50 to 100 kw per hour, while dry seal systems need about 5 kw of power per hour. Replacing wet seals with dry seals in centrifugal compressors pdf.
Dry gas seals 101 presentation free download as powerpoint presentation. The information found in dry gas seals handbook will help you make informed decisions regarding the application, operation, and maintenance of dry gas seals. Dry gas seals are noncontacting, dry running, mechanical face seals comprising a. Inadequate fuel gas pressure during start up typical conditions on inboardoutboard seal will include running. Dry gas seals require a buffer gas system to supply a sealing gas between the mechanical face seals. Standard filters are typically small in capacity and large in the mesh size. Mobile hydraulics system seals zero leak technology in mobile mining and other harsh environments. Dry gas sealing systems for oil sands pumping applications. These gas seal support systems sometimes referred to as gas seal panels because of their rackmounted design are normally supplied by the compressor manufacturer mounted on the. The parasitic power losses caused by oil shear and drag are also absent with gas seals. Gcs founded on january 1st, 2017, was previously a business unit within midwest pressure systems, inc. Dry gas seals 101 presentation gas compressor scribd. Over 80 percent of centrifugal gas compressors manufactured today are equipped with dry gas seals. Centrifugal compressor wet seals seal oil degassing and control.
Apr 27, 2011 common dry gas seal failures are discussed below along with their causes and remedies. Mining garlock sealing products are built for heavyduty performance and reliability. By proper balance of the seal face load factor, applied spring force, and friction coefficient of the seal face materials, dry gas seals have been designed to be suitable for slow roll operation at the sealed pressure ranging from 3 to 450 psig 21 to 3100 kpa. As noted earlier, it is not uncommon for dry gas seal systems to employ filtration of 1 micron or. Key considerations for dry gas seal performance flow. The single seal arrangement is used for moderate pressure applications, where small amounts of inert, nontoxic, or nonflammable process gas leakage into the atmosphere do not present a problem. Part 1general requirements this part of api 692 contains information pertinent to all equipment covered by the other parts of api 692.
We are committed to providing the latest technologies and designs in order to provide our turbo machinery customers within global energy industries with the solution. The backup seal may show reasonable performance under low pressure but may fail to perform under higher pressure if the primary seal fails. All dry gas seals need additional protection from the process and the bearing lubrication sides of the seal history. Double seals are normally applied where an inert seal gas usually n2, which is compatible with the process, is available at a pressure exceeding the maximum process pressure at the seal interface to prevent a seal pressure reversal. In case of the existing compressor equips oil film seal, seal oil console shall be replaced with dry gas seal control system. Aug 23, 2015 double seals can help simplify the seal gas control system, minimize the quality of seal gas, and optimize system reliability.
To avoid liquid and hydrate formation when the booster rack is not in operation, all seal gas pipework on the unit and the interconnecting piping have to be heat traced and lagged. A welldesigned dry gas seal system will prevent extensive damage to the dry gas seal, compressor and process. Dry gas seal systems for centrifugal compressors page 2 of. While dry gas seals can be very problematic if not properly applied at the time of plant, process, andor compressor design, the many successful installations are a testament to how troublefree these devices can be when properly applied. Flowserve offers a springenergized oring seal within regular operating range, and a springenergized ptfe jring seal for extended operating range. Dec 28, 2006 gas seals eliminate the need for complex and costly seal oil systems, and the ongoing maintenance associated with them. For dry gas seals, filters should be 25 times larger in terms of capacity, and 34 times smaller in mesh size than typical standard models. Dry gas seals may or may not provide positive gas sealing if the seal faces are damaged or distorted. Worldwide turbomachinery support compressor dry seal booster system an enviromentally friendly solution compressor dry gas seals depend on a clean and consistent supply of gas at the seal to maintain integrity and reliability. Dry gas seals are basically mechanical face seals, consisting of a mating rotating ring and a primary stationary ring during operation, grooves in the mating ring generate a fluid dynamic force causing the primary ring to. The benefit of dry gas seal reduce leakage gas process reduce the complex of system support reduce failure of mechanical system reduce amout of seal oil 4. Reverse rotation should be avoided as it will damage the delicate parts of a dry gas seal. These gas seal systems are normally supplied by the compressor oem mounted on the compressor base plate.
There are two basic types of gas seal systems differential pressure d p control. May 28, 2012 mechanical seals a mechanical seal is a device which helps join systems or mechanisms together by preventing leakage e. Compared to pump operations, dry gas seals and compressors usually operate at higher speeds and pressures. No further seal protection is necessary if the resulting gas seal system simulation shows that the seal gas supply remains in the gaseous phase for all operating situations. Preventing leakage of working gas from a machine inner side.
If a seal fails, the released gas could be detrimental to equipment or personnel within the area. Specifying engineers sometimes do not give enough attention to the scope. Drypactm gas conditioning system helps to lower the dew point of seal gas supply by removing heavier components in the gas through cooling, then heating the gas to achieve the recommended dew point margin of 20c 36f n2 genpactm nitrogen generation system produces standard n2 gas purity up to 99% for seal and separation gas supply. Dry gas seal systems for centrifugal compressors page 2. This prevents the direct escape of gas from the generator and at the same time prevents the ingress of air direct into the generator. Since many years the seal demonstrates their reliability worldwide in a wide variety of applications. Recently, as interest in carbon sequestration has increased, john crane has received a growing number of inquiries regarding how to seal supercritical co 2. These gas seal systems are normally supplied by the compressor oem mounted adjacent to the compressor. A sealing mechanism includes first, second and third dry gas seals arranged in series. Dry gas seal configurations dry gas seal assemblies are available in single, doubleopposed, and tandem configurations to suit all applications. Continuous exposure to sea water, steam, steamoil mixes, petroleum. Both proven liftoff patterns have high film stiffness and damping capabilities that maintain the gas film under slow roll conditions as well as high speeds up to 250 ms 49,212 fpm.
Jun 19, 2014 cobey has manufactured nearly 500 dry gas seal panels and has participated as a member of the api task force responsible for writing the 1st edition of api692. They will also learn what is required in a support system to ensure the reliability of dry gas seals. Dry gas seals and system this 5days course will help attendees understand the important features in a gas seal, so they can better understand why they may want to buy one seal over another. The alarm and shutdown devices of the seal oil system must be of reasonable range and sensitivity and. John cranes comprehensive range of dry gas mechanical seals are designed to provide you with the correct seal solution suited for your specific application, to ensure optimal reliability, safety and performance. Both proven liftoff patterns have high film stiffness and damping capabilities that maintain the gas film under slow roll conditions as well as high speeds up to. A gas heater maintains the required seal gas temperature above the dew points. Cost and maintenance of seal oil systems with their pumps, filters, seal traps, piping, etc.
Bp has wet seal gas recovery systems on 100 centrifugal compressors at its north slope facilities bps initial results show recovery of 99% of seal oil gas that would be otherwise vented to atmosphere from degassing tank bp and natural gas star collaborated on a detailed study of the alternative wet seal emission mitigation opportunity. The product for the most challenging and hostile environments with proven and independently audited performance to 425 barg. Dry gas seal dgs systems are used throughout the process industry to provide positive shaft sealing on compressors and other rotating machines in order to prevent the release of potentially harmful gasses or substances into the surrounding atmosphere. Dry gas seal systems the use of dry gas seals requires a system designed to supply sealing gas to the seal as a sealing and working fluid for the running gap. Pdf dry gas seal system design standards for centrifugal.
Both tandem and double seal consist of primary and. These systems support an ideal sealing environment to maintain. Inadequate fuel gas pressure during start up typical conditions on inboardoutboard seal will include. Common dry gas seal failures are discussed below along with their causes and remedies. Dry seals have fewer ancillary components, which translates into higher overall reliability and less compressor downtime. Figure 9 from dry gas seal system design standards for. 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 compressor and pipeline operating efficiency and performance, enhance compressor reliability, and require significantly less maintenance. Dependent on the process and operating conditions, gas conditioning unit gcu modules can be added to the standard john crane gas seal system to provide an integrated system that will further protect the gas seals. It is a very common practice to use seal gas tapped from the compressors discharge. Scribd is the worlds largest social reading and publishing site. Using dry gas seals in a centrifugal compressor requires a support system designed to supply sealing gas to the seal as the working fluid for the running gap. The seal gas supply pressure should be at least 50 psi 3. High quality compressor dry gas seal support systems engineered to customer requirements for all seal configurations and applications.
In some cases a retrofit to a dry gas seal can easily be justified. A sealing gas is injected into the seal, providing the working fluid for the running gap and the seal between the atmosphere or flare system and the compressor internal process gas. John crane gas sealsgas seals and their application for maximum reliability 2. Cobey has manufactured nearly 500 dry gas seal panels and has participated as a member of the api task force responsible for writing the 1st edition of api692. Another cause of dry gas seals contamination is lube oil migration towards the seals. It shall be used in conjunction with the following parts of api 692 as applicable. The original patent was for kaydons tapered ramp lift geometry, a constant diameter variable depth dynamic lift design. Dry gas seals, an alternative to isosleeve and isocarbon seals, eliminate the need for oil supply systems. Despite the 20year trend of increasing dry gas seal applications, an industry accepted standard for gas seal support system design does not exist. Each seal receives its own sealing gas and has its own venting mechanism. Dry gas seal technology has demonstrated reliability and cost savings for most applications of new compressors.
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