Abstract: A method to control the performance of desiccant dryers is disclosed that senses multiple variables and optimizes the regeneration cycle to deliver the gas at the desired dew point. The length of the stripping step is reduced or eliminated depending on the desired set point and the operating conditions of the compression system. The control system has the capability to switch to high efficiency mode of operation should the dew point set point be changed. The savings come from not purging as much or any gas during stripping should the system requirements be only to meet the ISA standards for instrument air, despite the system capability of delivering far dryer air.

Abstract: A method to control the performance of desiccant dryers is disclosed that senses multiple variables and optimizes the regeneration cycle to deliver the gas at the desired dew point. The length of the stripping step is reduced or eliminated depending on the desired set point and the operating conditions of the compression system. The control system has the capability to switch to high efficiency mode of operation should the dew point set point be changed. The savings comes from not purging as much or any gas during stripping should the system requirements be only to meet the ISA standards for instrument air, despite the system capability of delivering far dryer air.

Abstract: A casting technique is disclosed which improves efficiency and reduces fabrication and assembly cost for a centrifugal compressor. The volute is cast integrally with the impeller housing to allow closer radial tolerances to be used to improve efficiency. In the preferred embodiment, compressors for multi-stage compression are assembled with intercoolers and the integral volute is cast together with the impeller housing and the lower gearbox housing and the associated intercooler. Efficiency increases of 2% or more are achievable. In multistage applications, efficiency gains in the early stages are compounded in each subsequent stage.

Abstract: A method and apparatus for compressing and drying a gas, typically air, are provided in which a multistage compressor is employed to produce interstage and final stage compressed gas. Regenerative adsorbent is employed to dry the final stage compressed gas. Interstage gas is used to regenerate the saturated adsorbent. Preferably, two beds of regenerable adsorbent are provided, each operable in a drying mode and a regeneration mode. In the drying mode, final stage compressed gas is passed through the bed of adsorbent in order to be dried, until the adsorbent is saturated. In the regeneration mode, moisture is removed from the saturated adsorbent by a stream of interstage compressed gas. The two beds are preferably alternately operated in the drying mode and the regeneration mode, in order to provide a continuous process.

Abstract: A centrifugal compressor assembly, especially one having two or more stages, has a first compressor casing having a fluid inlet and a fluid outlet and a first impeller rotatable within the first compressor casing. A second compressor casing provided having a fluid inlet and a fluid outlet and a second impeller rotatable within the second compressor casing. Drive for the compressors is provided by a switched reluctance motor disposed between the first and second compressor casings and comprising a stator and a rotor rotatable within the stator. A drive shaft is provided, wherein the first impeller, second impeller and the rotor are mounted on the drive shaft and rotatable therewith.