Valves in action -
Differential pressure regulator DV 505
Differential pressure control in a natural gas compressor in a petrochemical plant
As a matter of principle, any gas under pressure represents a potential risk. However, the high flammability and/or explosive properties of natural gas are exceptionally hazardous and must, consequently, be taken into account in the oil and gas industry. There is a serious risk of an undesired gas leakage from the system particularly for rotating equipment and plant components, such as pumps, compressors or stirrers. Compressors are used for pressurization of the gas to enable transport in pipelines or to obtain the correct pressure for processes in petrochemical plants.
At the site of a leading manufacturer for high-quality polyolefins (polymers) in the United Arab Emirates, the source product natural gas is exposed to high pressure for further processing in order to trigger a polymerisation reaction. The natural gas is compacted in a steam turbine driven compressor before the subsequent production steps start. Since the mechanical energy needed for compression of the gas is introduced by the shaft, the shaft seals located between the shaft and the compressor are to be especially protected from leakages. For this purpose, lip seals with seal gas are inserted there.
Mankenberg’s mechanical differential pressure regulating valve DV 505 retains the pressure of the seal gas slightly above the process gas pressure. This specific pressure reducing valve monitors the non-constant working pressure within the compressor and constantly regulates the seal gas pressure to a value that is approx. 0.5 bar above that level. This overpressure prevents the natural gas from escaping out of the compressor, without damaging the seals or contributing to unnecessary gas losses. There is no need for external measuring or similar equipment. The DV 505 completely operates without necessitating external energy.
With their many fields of application, the compressors require the valve to adapt to the operating conditions. This applies to the valve’s pressure stage as well as to its control characteristics and the seals and standards to be used.
