[ID] => 9410
[post_author] => 34
[post_date] => 2018-04-06 08:56:25
[post_date_gmt] => 2018-04-06 07:56:25
[post_content] => There are no cookie-cutter solutions for any applications that involve the handling and transfer of industrial gases. Therefore, making assumptions based on past experience, or what the other guy is doing, can only get you in trouble.
In order to help ease the burden of selecting the proper compressor technology for the handling of industrial gases, this article will lay out a general framework that can be used to help the end user identify and select the proper solution.
When a customer comes with a request to move product, the application engineer has to ask a lot of questions. What product or products are involved? What pressures and flow rates are expected? What exactly is the application? Is this even a job for a compressor?
Only after the parameters of the operation are established will the application engineer know if a compressor is an appropriate technology for use in completing the process.
Generally speaking, there are three typical product transfer applications that hit the sweet spot for compressors:
- Vapour recovery, for instance the removal of flammable gas vapours remaining in a tank after the liquid has been transferred, natural gas vapours in stock tanks, sulphur hexafluoride in electrical transformers, seal leakage from process compressors in larger plants and the emptying of storage vessels prior to their maintenance, reconditioning or replacement;
- Pressure boosting, in order to move gas from one location to another, or for the transfer of refined natural gas from a low-pressure distribution line into a storage tank that feeds a burner in a heat-treating process; and
- Liquefied gas transfer, during the loading, unloading or transloading of railcars or other transport vessels.
Once the actual process is identified, the application conditions must be determined. To ease this process, many equipment suppliers have created a data sheet that they give to their customers to complete. In addition to general information like the site location and elevation, and whether the equipment is located indoors or outdoors and stationary or mobile, the questionnaire will ask for more specific operational parameters.
Once these operational parameters have been determined, the application engineer will initiate the process of selecting the proper compressor for the operation – although there may well be more than one option.
It pays to reiterate that every technology and every model design within that technology has very concrete limits on what its operational capabilities are. This can also require some outside-the-box thinking. For example, if a single compressor cannot meet the required flow rate and pressure, it may be possible to add a second compressor in series or parallel to achieve the desired performance.
DOWN THE FUNNEL
Reciprocating piston compressors are positive displacement machines, as are their diaphragm cousins. There are also positive displacement rotary compressors, such as the vane, screw, liquid ring and blower types. Finally, there are axial or radial turbo compressors. All excel in their own operational niche in industrial gas transfer, whether it be the ability to produce high flow at high pressure, high flow at low pressure, low flow at low pressure or low flow at high pressure. Again, the operational parameters of the process will provide a roadmap to the best compressor technology.
Another significant factor is cost – especially in today’s world of highly controlled budgets. Generally speaking, reciprocating piston compressors are among the most cost-effective technologies available to the market. That being said, the operation’s process parameters and requirements will play a large role in the final cost of the equipment required for the application. Machines that must meet API-618 design requirements, for instance, will have a much higher purchase price than a non-API-618 design.
Many applications will be able to use the chosen machine straight out of the box but there will always be occasions where a specially designed or configured machine is required. In this case, there are bound to be added system costs as the compressor and/or system are modified to fit the unique needs of the operation.
Furthermore, within those categories of compressor, there are further segments. Within the family of reciprocating piston compressors, for instance, there are oil-free, non-lube, lubricated and oil-less designs. Again, knowing the operational parameters and requirements will create a path that leads to the selection of the proper technology. For example, the transfer of crude natural gas may not require an oil-free compressor because there are already impurities in the gas itself so that any small amounts of oil carryover from the compressor that enters the gas stream will not harm the product or the process.
Oil-free designs are inevitably more expensive and there is no point offering the customer an unnecessary technical upgrade. Emission compliance requirements, however, could mean that an oil-free design might still be the best solution due to its leak-control capabilities. Fugitive emissions control regulations may also point to more comprehensive leakage control, ruling out lubricated compressor designs that require oil lubrication in the upper cylinder and valve area, which can be prone to significantly higher leakage rates.
THINGS TO REMEMBER
Having settled on an oil-free reciprocating piston compressor, the engineer must now consider the actual environmental operating conditions. Oil-free designs have very specific discharge temperature limitations. In this instance, the top end of the machine is designed to operate without lubrication, so it has non-metallic wear parts (e.g. piston rings, packing seals, etc) that become sacrificial wear parts because they operate without lubrication. By design, those parts will need to be serviced and replaced on a regular basis. Typically this is done as part of an annual preventative maintenance programme.
In some applications where operating temperatures are low, and operating pressures and compressor rpms are in a moderate range, a user can see the compressor operate for a few years without any need for significant maintenance. In other applications where temperatures are high and pressures more demanding, the operator may only get 2,000 hours of service out of the compressor before it needs to have those top-end wear parts serviced.
Finally, and most importantly, the performance of the reciprocating piston compressor must meet or exceed the requirements of the process that it is operating in. This often means that the compressor manufacturer will need to reach out to other professionals in the field – distributors, fabricators, system integrators, etc – for assistance in completing a turnkey gas compressor system for the application.
In the end, reciprocating piston compressors – like any comparable technology – are only effective in performing their duties if they are put in a position to be successful. Reaching a state of ideal operation can be attainable if the proper legwork is done to ensure that the compressor can satisfy the many unique and varied needs of the application. By asking the right questions, performing the required research and working closely with the customer and other channel partners the unknowns will be removed from the compressor selection process, resulting in an optimized operation and contented clients.
*Glenn Webb is business development manager, Blackmer Compressors at Blackmer and PSG. He can be reached at firstname.lastname@example.org. More information on Blackmer’s full line of pumps and compressors can be found at www.blackmer.com.
[post_title] => Compressors: Tool for the job
[post_status] => publish
[comment_status] => open
[ping_status] => open
[post_name] => compressors-tool-job
[post_modified] => 2018-04-05 17:59:34
[post_modified_gmt] => 2018-04-05 16:59:34
[post_parent] => 0
[guid] => https://www.hcblive.com/?p=9410
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