Molecular Sieve Dryer
After extensive testing by the customer to well over 4000 cycles the engineer noted that the valves had no visible leakage. The customer immediately installed additional valves and has continued to replace other valves.
| Valve Supplied | |
|---|---|
| Size | 4" and 6" ANSI 300 Class |
| Body | WCC Carbon Steel |
| Internals | Carbon steel with electrolysis nickel plating |
| Trim | Teflon seat with Kalrez seals |
| Port | Reduced Port |
| Connections | Raised Face Flanged |
| Service Conditions | |
|---|---|
| Media | Nitrogen Dryer Switching Valve |
| Manual/Actuated | Actuated with override |
| Temperature | 450F norm to 500F maximum |
| Orientation | Vertical |
| Pressure | 450 psig |
| Cycle Frequency | Approximately 4 cycles per day |
Challenge
The targeted valve installation is a molecular sieve dryer valve (also known as: mole sieve switching valve, de-hydration switching valve, gas de-hy switching valve, among others).
Brief overview on molecular sieve dryer; A cyclical adsorption desorption system to transfer contaminants – or non-desired gas molecules from one stream to another. Mole sieve drying systems are utilized in processes where the end user is ultimately trying to purify (remove moisture and contaminates or isolate specific gas strains). Natural Gas Processing - Removes CO2, H20, H2S, RSH, COS, Hg, S, etc. Petrochemical and Specialty Gas Manufacturing – Allows the separation of specific gas molecules (example methane for liquefaction) Regeneration done thermally with high temperature gas flow
Common application: valve cycles 4-6 times each day - year round. Pneumatically actuated. High temperature swings from ambient to 500F (some as high as 620F max).
Potential Issues: On occasion, drying material is upset (desiccate) and is blown into valving during operation. This desiccate dust (material is as small as dust and as large as one inch in diameter) is extremely hard and has the tendency to crush in between the more commonly utilized valve design and damages the seating surfaces to the point that a positive seal cannot be achieved to isolate the dryer beds. Customer has to de-pressure entire system to repair in-line and they cannot repair themselves. Other designs require special tools. Multiple customers with this application complain about the accessibility/availability and cost of the certified repair technicians.
Solution
The customer selected our HCV Valve for testing purposes and it was installed immediately to replace a valve they were previously planning to have repaired. The HCV valve performed so well they have now replaced all of the switching valves in their dryer system with HCV product line.