Pneumatic Vapor Valve to Shorten Coking Cycle

Coke drum overhead vapor valves are massive affairs. Switching a pair of 20-ft diameter drums may require the manipulation of four 18-in. and four 12-in. valves. Size aside, the vapor valves are difficult to open and close because of coke deposits on valve internal parts. Removing the insula­tion on piping upstream of the vapor valves or injecting a small liquid quench (typically 3 vol%) into the vapor line at the first 90° turn will help.

To minimize the amount of hard physical labor required to switch drums every 12 hours, the vapor valves should be fitted with locally con­trolled air operators. Such a device is little more than an air gun permanently mounted to the stem of each valve. The speed of the valve movement is controlled with a Win. air valve.

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