Q & A > Question Details
Ours is Axens liacence CCR we are facing frequent problem of regen gas drier cyclomatic valve stucking and when valve opened some power type material observed must be desi ant. Does anyone suggest how to overcome this problem. Second issue is though regen drier working fine dew point varies from +5 to - 30 deg c. Is this because of activated alumina property loss or dis functioning.
17/02/2017 A: Peter Marsh, XBP Refining Consultants Ltd, peter.marsh@xbprefining.co.uk
The cyclomatic valve may be sticking due to accumulation of salts or corrosion products at the valve seal faces. The cold sections of the regeneration loop are susceptible to corrosion due to imperfect scrubbing of corrosives in the wash tower. This may be due to inefficient mixing of the circulating caustic stream with the regeneration gas due caused by damage to the static mixer, damage to the wash tower internals or inadequate control of caustic strength. Corrosion can occur due to hydrochloric acid attack (especially at the dew point location) due to presence of residual chlorides, carbonic acid attack due to presence of residual carbon dioxide or pitting via under-deposit (salt) corrosion. Careful monitoring and control of the wash tower will prevent washwater carryover to the driers which could damage the dessicant. It is also important to ensure the line between the wash tower and driers is efficiently heat traced (preferably electrically traced with common alarm on local tracing control panel) to avoid moisture condensation.
Dew point variation may be due to variable moisture content at the drier inlet (condensation?) or partial blockage or damage to the dessicant bed (accumulation of corrosion deposits?). Partial blockage of the dessicant bed could be detected by comparing pressure drops and the shape of the temperature profiles during heatup and cooldown phases of the regeneration sequence for each dessicant bed. Asymmetric piping at the drier inlets may cause corrosion deposits to preferentially accumulate in one drier rather than evenly over both driers.
13/02/2017 A: Rupesh Patel, Saudi Aramco Total Refining and Petrochemical Company, rupeshgpatel@gmail.com
Check outlet basket in absorber when got opportunity. Second carry over of free water to adsorber lead to early saturation of dessicant.Check prefilter functionality may be plugged or not efficient to remove water. Also excessive water Cary over from wash tower may be wash tower delisted pad having issue.
Is valve sticking em xams in winter? If it so apply steam on actuator.