| 摘要 |
A vapor recovery system for closed volatile liquid storage facilities including loading rack systems for tank trucks, rail cars, ship and barge cargo compartments. These facilities have provision for charging the system with blanketing gas under controlled pressure conditions for admixture with vapor of the volatile liquid. This mixture is processed for recovery of the vapor and gas constituents under the supervision and control of precision oxygen monitoring. Whenever the detected percentage of oxygen exceeds a predetermined safe value, corrective measures are taken immediately and automatically and acknowledging devices are activated and additional blanketing gas may be supplied to decrease the percentage of oxygen in the facility. Vapor and gas mixtures monitored and found safely non-combustible are processed by compression and heat exchange to condense some of the vapor and to elevate the pressure level. Vapor and blanketing gas is conducted from sweet and/or sour liquid storage tanks into a holding tank before being processed for recovery of the gas and vapor, whereas vapor and blanket purge gas originating from loading rack facilities bypasses the holding tank and flows directly to compressing and condensing components. Portions of the vapor not condensed remain in the gas and vapor mixture at pressures where they can be beneficially utilized. If the blanket gas is combustible, such as natural gas from a gas utility, the net exhalations may be used as a general purpose fuel gas or returned to the gas utility. The system includes automatic equipment safeguarding against contamination of sweet liquid by vapor from sour liquid sources.
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