The advantages of dry gas seals over wet seal systems can be defined as follows. This current calm attitude of universal pressure seal design acceptance is a far cry from the battles waged in the. Gas seal manufacturers have stringent requirements for seal gas quality. Typically, the sealing gas must be dry and filtered of particles three microns and larger. Improper installation of an igu window can also cause a seal to fail.
Gas seal performance and start up condition enhancing with. This allows for a pressure balance to be achieved providing a small opening force on. Gaslubricated used for twenty years ago almost of the compressor use them 3. Dry gas seals 101 presentation gas compressor bearing. An ebook reader can be a software application for use on a computer such as. Gcs founded on january 1st, 2017, was previously a business unit within midwest pressure systems, inc. Feb 01, 2017 dry gas seals for compressors and auxiliary equipment. Pdf advanced dynamic model development of dry gas seal.
Wet seal degassing recovery system for centrifugal compressors. Drygas seals are designed with many of the basic characteristics of liquid. Gas compression systems dry gas seal pressure boosters ensure that gas quality is maintained during startup. This book presents a complete guide to the technology, from the principle of gas seal operation to lessons learned from actual field experience.
Concerns with flare header pressures that can cause seal pressure reversals. There are a twomass dynamic model, hydraulic model to determine pressure distribution in the sealing. Because of this, most dry gas seals have a maximum operating temperature of 177c. Large numbers of dry gas seal assemblies have problems because of an issue with an oring or a vring. Aug 02, 2017 a dry gas seal control system must have an adequate range and controllability to maintain a minimum 16 fps 4. This process requires sealing turbomachinery for high pressure reinjection at the wells and sealing the pumps that transport the co 2 throughout the pipeline. Because the seal gas undergoes different levels of pressure reduction within the seal, potential liquid or condensation and, in some cases, solid hydrate formation in the gas seals must be studied together with its mitigating measures in the design. Seal configuration an overview sciencedirect topics. Type 28at seal design featurescompliant stationary face design.
For example, applying this formula to a moderatespeed application with a sealing pressure of 3,118 psig and a speed of 7,700 rpm results in an estimated churning heat of 15 to 16 kilowatts. The leading manufacturer of dry gas seal boosters gas compression systems, inc. The normal flare pressure is generally close to the atmospheric pressure and the maximum pressure can be as high as 50 psig. As part of the german freudenberg and japanese ekk group, eagleburgmann is one of the worlds leading providers of industrial sealing technology. The dry gas seals employed in siemens centrifugal compressors represent a significant advance in shaft sealing. The switch of oil wet seals to dry gas seals in centrifugal compressors is a good. The dry gas seal contains temperaturelimited static seals between the seal cartridge and the casing and between the shaft sleeve and shaft. Apr 27, 2011 insufficient pressure of the buffer gas during startup can cause the process gas inside the compressor to go through dry seal faces. How to prevent trips in dry gas seals turbomachinery.
Dry gas seals dgs used in ultrahigh pressure gas reinjection systems are setting a new standard in offshore, deepwater applications. Dry gas seal configurations dry gas seal assemblies are available in single, doubleopposed, and tandem configurations to suit all applications. This stateoftheart solution will help by eliminating the ongoing maintenance costs associated with wet oil seals and thereby greatly increases equipment reliability and efficiency. Insufficient pressure of the buffer gas during startup can cause the process gas inside the compressor to go through dry seal faces. Evolution of gas turbine combustion systems to dle extending fuel. Dec 28, 2006 disassociating entrained gas and the hazard of explosive mixtures in the oil reservoir of combined lube and seal oil systems are eliminated.
There are two basic types of gas seal systems differential pressure d p control. Dry gas seal systems for centrifugal compressors page 4 of. 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. Filters are normally provided in the gas seal system to meet this requirement. 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. Seal gas cleanliness demands fine gas filtration as mandatory before gas entry to the seals.
The single seal arrangement is used for moderate pressure applications, where small amounts. Dry gas seal booster systems the use of dry gas mechanical shaft seals in centrifugal compressors has increased dramatically in the past 25 years. These tools include predictive software code developed inhouse, finite element. A sight glass can be installed in this drain to allow for easier observation of oil in this.
Today, pressure seal valves are manufactured of low carbon steel, chrome moly and austenitic stainless steel in pressure classes up to 4500. It is the original gas seal, with a design pedigree stretching back over 30 years. Technology insight dry gas seals for low and high pressure by a. Dry gas seal arrangement typical dry gas seal seal face of dry gas theory of noncontact lift off of stationary ring achieved by increased pressure at the taper. Exposure to the dirty gases will make the dry gas seal groove ineffective causing the damage to the seal faces. Processdesign considerations for a compressor drygas seal. Dry gas seals services siemens siemens global website. The gas seal housing, including seal faces surfaces, andor bushing.
The backup seal may show reasonable performance under low pressure but may fail to perform under higher pressure if the primary seal fails. The seal gas supply pressure must be a higher pressure than the compressor seals will ever encounter. Pdf dry gas face seal design with arbitrary gap shape. Seals on the rotating shafts prevent the high pressure natural gas from escaping the compressor casing. Dry gas seals 101 presentation free download as powerpoint presentation. When dry gas seals were first installed, differential pressure was measured and. Upon receiving an order for a h2rich gas centrifugal compressor with a design pressure of 20. The information found in dry gas seals handbook will help you make informed decisions regarding the application, operation, and maintenance of dry gas seals.
Process design considerations for a compressor dry gas seal system interface chung leong, independent consultant, and sanjiv goyal, fluor enterprises ments. Replacing wet seals with dry seals in centrifugal compressors. 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. Dry gas seals for low and high pressure sciencedirect. Dry gas seal systems for centrifugal compressors page 4. Advanced pressure seal design standard design new liveloaded design liveloading maintains bonnet seal regardless of pressure temperature fluctuations a a bonnet seal decreases with bonnet seal loss of pressure increases with pressure a a b c system pressure b d d c c sealing forces due to pressure. Although these window seals are meant to be longlasting and may hold up for decades, they can and do fail. Centrifugal compressor wet seals seal oil degassing and control. The design of pressure windows worked examples caf 2 window 50mm o with 1 atmosphere p. Seal oil systems require low settle out pressures necessitating flaring large. Jul 30, 20 each dry gas seal is tested in the laboratory before shipment and quality guaranteed. Total elimination of contamination of the process gas by seal lubricants. There are two basic types of gas seal systems differential pressure d p control and flow control. The action of the gas flowing across the seal generates pressure that keeps a minute gap, therefore optimizing fluid film stiffness and providing protection against face contact.
The influence of various combina tions of materials on the operating behaviour of the seals is also analyzed. Scribd is the worlds largest social reading and publishing site. 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. Seal buffer gas pressure max process gas pressure 2. Dry gas seals operate under extremely tight tolerances, which demand that special care be taken in the design of the gas seal environment, and in the operation of the compressor and gas seal system. Oct 07, 2014 this best practice has been recommended since 2000, initially on a project that used the first dry gas seal system in an existing chemical plant that previously had used oil seal systems. About us at the leading edge of industrial sealing technology. If it appears to dry up, theres still the chance that deposits in the water could remain and dirty or scratch the inside of the panes. Dry gas seal applications for high pressure youtube. The seal gas used as the sealing medium is usually a clean, dry and cool gas that is compatible with the process gas being compressed. The purpose of this project was to design a cost effective smart dgs system using. The oilfilm seal commonly used in earlier compressor designs has been mostly phased out by dgss. Each dry gas seal is tested in the laboratory before shipment and quality guaranteed.
Preventing contamination of the gas used by these seals is necessary to assure long life. A break in the perimeter seal releases the argon gas between the layers, replacing it with ordinary air, which condensates when the temperature between indoors and out is just right. 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. This paper presents the philosophy of one centrifugal compressor and dry gas seal original equipment manufacturer. There are many sealing elements orings, vrings, urings, etc. John crane type 28at dry gas seals ensure reliability and uptime in missioncritical applications. Type 28at dry gas seals john crane mechanical seals. Therefore, in hightemperature sco 2 turbines, the seal buffer gas also serves to cool the seal.
Seal leakage will change based on the seals size, speed, operating pressure. Demands and regulations to reduce emissions and improve compressor reliability have encouraged users to convert their wet compressor sealing devices to a dry gas seal design. More than 80% of centrifugal compressors today are manufactured with a dgs stahley 2001. Key considerations for dry gas seal performance flow. This paper proposes a set of gas seal system design standards for process gas centrifugal compressors on the basis of safety, reliability, and economics. The color coding of the dry gas seal system by operations and engineering greatly increased awareness and understanding of this system. Dry gas seals may or may not provide positive gas sealing if the seal faces are damaged or distorted. John crane gas sealsgas seals and their application for maximum reliability. Dry gas seals for compressors and auxiliary equipment.
Mathematical model of dry gas seal with spiral grooves design sketches of. Pdf dynamic processes of dry gas seal operation are investigated in this paper. Replacing wet seals with dry seals in centrifugal compressors executive summary centrifugal compressors are widely used in production and transmission of natural gas. Aug 02, 2017 dry gas seals are an integral part of modern centrifugal compressors. How to repair a failed seal on insulated glass windows. 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. Screw compressor package design considerations duration. By using an empirical formula for dry gas seals in highdensity fluids based on the bilgenboulos equations for high reynolds numbers, estimating an applications churning heat is possible.
The secondary or outboard seal normally operates at a pressure lower than the. 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. Engineered dry gas seal control systems ampliflowtm seal supply gas boosting system to help avoid seal contamination problems during low differential pressure conditions across the compressor cleanpactm gas conditioning system enhances filtration by removing excess particulate contamination down to 0. Pressure seal design today is fairly standardized by manufacturers all over the world. Seals can be damaged by house painters using heat guns to strip paint or by homeowners using pressure washers to clean the windows. A sight glass is ideal for this application allowing operators to see if liquidoil is.