SELECT THE RIGHT VALVES FOR ADSORPTION PROCESSSES High cycling necessitates extra attention to tight shutoff and robust design

摘要

MANY PLANTS rely on adsorption to remove or separate specific components of a liquid or gaseous mixture.This mass transfer process typically involves multiple valves(Figure 1).Stroking frequency of those valves can exceed 60,000 cycles per year and maintaining industrial gas purity and efficiency requires tight shutoff to Class VI.Many problems occur from using the wrong valves.Poorly performing valves can lead to increased maintenance,unit trips and decreased efficiency.For example,when surveying ethanol producers from around the world,some of the most commonly reported maintenance problems related to adsorption include: 1.poor control and reduced cycle life due to oversized butterfly valves;2.accelerated bearing wear,often seen after only a few months;3.multiple mechanical failures because of inferior valve-actuator-positioner linkages;and 4.inadequate performance from low-quality valve positioners in both the adsorption and regeneration cycles.