Application Notes

There are several items regarding the application of reciprocating compressors that must be considered. These items are minor, bin if neglected may cause a great deal of concern when the inevitable problem occurs.

Reciprocating compressors are not fond of liquids of any sort, particularly when delivered with the inlet gas stream. For any application, a good-sized suction drum with a drain provision is in order. It may be a part of the pulsation control if properly done. The pulsation control will be covered in more detail later in the chapter. If the stream is near satura tion or has a component near saturation, consideration should be given to using a horizontally oriented cylinder configuration, with the discharge nozzle on the bottom side of the cylinder. While on the subject of condensation, for the same gas near saturation, cylinder cooling must be monitored and controlled. It would not do to let the gas condense inside the cylinder after all the care has been taken not to let it condense outside the cylinder. A rule of thumb is to keep the cooling water temperature 10°F above the gas inlet temperature.

It would appear obvious for startup, and in some cases full-time operation, that a suction strainer or filter is mandatory. The reason for ihe strainer is to keep junk and pipe scale out of the compressor. Fines from pipe scale and rust will make short work of the internal bore of a cylinder and are not all that good for the balance of the components. In some severe cases, cylinders have been badly damaged in a matter of a few weeks. The strainer should be removable in service for cleaning, particularly when it is intended for permanent installation. Under all circumstances, provision must be made to monitor the condition of the strainer. Much frustration has been expended because a compressor overheated or lost capacity and no one knew if the strainer had fouled or blinded.

The discharge temperature should be limited to 3Q0°F as recommended by API 618. Higher temperatures cause problems with lubricant coking and valve deterioration. In nonlube service, the ring material is also a factor in setting the temperature limit. While 300°F doesn't seem all that hot, it should be remembered that this is an average outlet temperature, whereas the cylinder will have "hot" spots exceeding this temperature.

Finally, planning may save money and time if process changes are foreseeable. For instance, capacity increase, or an increase in molecular weight due to a catalyst change, results in decreased volumetric flow. Although the cylinders must be sized for economical operation at the present rate, the frame can be sized for future applications. When the future conditions become a reality, the cylinders can be changed while keeping the same frame. This saves the investment cost and delivery time of a complete new compressor without the penalty of oversizing and its inherent inefficient operation.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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