Example: dental hygienist

www.BetaMachinery.com Foundation And Skid …

Foundation And Skid Design Considerations For Large, high - speed Reciprocating Compressors > New GMRC Guideline will draw on industry best practices By Norm Shade piers (equipment mounted on a con- crete block supported by deep driven steel piers), block and skid on driven steel pilings (equipment mounted on a fabricated steel skid mounted on a concrete block supported by driven steel pilings), and skid on driven steel pilings (equipment mounted on a fab- ricated steel skid mounted on driven steel pilings). high - speed reciprocating com- pressors are much more likely to be installed on a skid than classic slow- speed models. The skid is the fabri- cated steel structure that supports the compressor and driver and often the n Figure 1. Shown above is a common arrangement of a skid-mounted motor/ vessels, piping and other equipment compressor package.

OCTOBER 2012 COmpREssORtech2 I n the past decade, high-speed (700 rpm and above) reciprocat-ing compressors have become common for gas transmission and

Tags:

  High, Speed

Information

Domain:

Source:

Link to this page:

Please notify us if you found a problem with this document:

Other abuse

Transcription of www.BetaMachinery.com Foundation And Skid …

1 Foundation And Skid Design Considerations For Large, high - speed Reciprocating Compressors > New GMRC Guideline will draw on industry best practices By Norm Shade piers (equipment mounted on a con- crete block supported by deep driven steel piers), block and skid on driven steel pilings (equipment mounted on a fabricated steel skid mounted on a concrete block supported by driven steel pilings), and skid on driven steel pilings (equipment mounted on a fab- ricated steel skid mounted on driven steel pilings). high - speed reciprocating com- pressors are much more likely to be installed on a skid than classic slow- speed models. The skid is the fabri- cated steel structure that supports the compressor and driver and often the n Figure 1. Shown above is a common arrangement of a skid-mounted motor/ vessels, piping and other equipment compressor package.

2 Required for the compressor system. Figure 1 shows a typical arrange- ment of a skid-mounted motor/. I. n the past decade, high - speed ing Compressor Packages for Natural compressor package. The skid is of- (700 rpm and above) reciprocat- Gas Transmission and Storage Appli- ten composed of two main structures: ing compressors have become cations is the product of a two-year in- a main skid and one or more pedes- common for gas transmission and vestigation of industry experience and tals. The pedestal structure supports storage applications. best practices. This article provides a the compressor and the driver. It may Driven by gas engines or electric preview of some of the GMRC guide- be integral with the main skid. The motors, these compressor pack- line's recommendations for skid and main skid supports the pedestal as ages are generally 1491 to 5966 kW.

3 Foundation design. well as the other components of the Foundations and skids and support Many types of foundations are used compressor package. the compressor and driver, ensuring for reciprocating compressors: block The Foundation is the structure frame and coupling alignment and Foundation (equipment mounted di- that supports the skid. The founda- providing energy paths for dissipation rectly on a concrete block), skid on tion and the skid must provide the of equipment unbalance and other block Foundation (equipment mount- compressor, driver and other equip- time-variant forces. ed on a fabricated steel skid that is ment with a stable base for safe, Proper Foundation and skid design mounted on a concrete block), block long term operation. is a critical success factor when ap- on mat Foundation (equipment mount- Skids and foundations have to be plying high - speed reciprocating ed on a concrete block supported designed to support the compressor compressors in this size range.)

4 The on a mat), block on concrete piers and driver weights and resist the driver soon-to-be-completed Gas Machinery (equipment mounted on a concrete dynamic (roll) torque, frame unbalance Research Council (GMRC) Design block supported by deep reinforced forces and moments, vertical cross- Guideline for high - speed Reciprocat- concrete piers), block on driven steel head forces, time domain gas and in- OCTOBER 2012 Compressortech2. between the technical specialists as the design is developed, and attention to construction details throughout the construction process. Performance criteria, guidelines and design strat- egy have to be agreed upon prior to the start of the design. Once the initial compressor and driver types and sizes are chosen, a rough sizing of the skid footprint can be made.

5 Since the final design of the skid is strongly influenced by the Foundation design, the Foundation type must be the next decision. The Foundation design is dictated by soil conditions and other factors, such as type of compressor, type of driver, and distance to neighbors. n Figure 2. The vibratory energy created by the operating equipment must Very early in the project, a site in- have a continuous path into an appropriate Foundation . spection is required to measure soil properties and understand environ- mental factors. A specialized geotech- ertia forces at each compressor throw, cy associated with the rated oper- nical report will help determine the re- and the effects of frame flexibility. ating speed . In addition, there are quired type of Foundation for the site, Designing simply for unbalance harmonic frequencies (multiples of as well as provide basic soil proper- forces is not adequate.)

6 Skids must operating speed ) that result from me- ties that are necessary for the founda- be designed for compatibility with chanical and gas pulsation forces. A tion design and vibration analysis. their foundations, and must also be constant speed driver ( , synchro- Foundations are generally catego- suitable for compressor package lift- nous electric motor) has a discrete rized as either shallow (concrete block ing and transportation prior to and set of forcing frequencies. designs) or deep (pile foundations that during installation. Preferably, the Variable speed drivers (gas en- include a concrete block with piles or, skid and Foundation should be de- gines or variable frequency electric alternately, a skid that is mounted di- signed as a system by the same en- motors) create ranges or bands of rectly to the piles).

7 Economics associ- gineering entity. forcing frequencies that must be ated with the availability of concrete, Compressor and driver time vari- dealt with, making the placement and pile-driving equipment, etc. will influ- ant forces are dissipated by trying to control of natural frequencies much ence the choice of Foundation , as will move a large Foundation mass. The more challenging. Wide speed rang- the size and type of compressor and vibratory energy created by the oper- es make the task of natural frequency number of throws. Poor soil condi- ating equipment must have a continu- placement very difficult, and if the tions usually force the decision toward ous path into an appropriate founda- speed ranges are too wide, the har- deep foundations. tion (Figure 2).

8 Monic bands overlap such that there It is important to map out the entire If a skid is isolated or not properly are no safe zones for placement of area that must support the Foundation . anchored to the Foundation , there is the higher frequency modes. Clay and sand are common types of no energy path into the Foundation Solely from a vibration standpoint, soils in most locations. Wet clay can for dissipation. If the Foundation is constant speed equipment is always expand and contract, causing settle- not large enough, it will not dissipate preferable, and the wider the speed ment and uplift. Dry sand has no cohe- enough energy. Time variant forces ranges, the higher the risk of serious sion and low-to-moderate load-bear- that are not dissipated by the founda- vibration related problems.

9 For optimal ing capacity. Slightly moist mixtures of tion can excite natural frequencies of vibration avoidance, flexible unloading clay and sand have moderate-to- high package components and cause fail- schemes (combinations of automatic bearing capacity, good stiffness, and ures of instrumentation, small-bore clearance volume pockets and, if ab- are desirable. Rock, shale and lime- piping and pressure vessel nozzles, solutely necessary, end deactivators) stone are extremely dense and form as well as fastener loosening and oth- are almost always preferable to wide good bedrock support. er problems that result in unscheduled operating speed ranges. Layered soil is often encountered, shutdowns and safety hazards. Successful design and construction and understanding the effects of lay- Each driver and compressor com- of a skid and Foundation system re- ering is critical.

10 Soil properties must bination has a fundamental frequen- quires effective planning, coordination be obtained for each layer. The depth OCTOBER 2012 Compressortech2. of the soil analysis is influenced by the type of Foundation . Generally, a depth equal to four times the founda- tion equivalent radius is adequate for shallow foundations, but more depth should be assessed to determine that there is no undesirable layer present. Specialized geotechnical testing is required to measure the soil dynamic properties. It is advisable to select a local geotechnical consultant, since they can be expected to have special- ized knowledge regarding the local soil and climatic conditions. n Figure 3. A best practice skid design with four Vibration results from the structural full-length main runner beams parallel to the flexibility of all components and time crankshaft, with additional width in the engine variant forces originating from the op- area for auxiliaries and maintenance platforms.


Related search queries