Submersible Pump Column Access for Zero-Purge Cryogenic Handling
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Solution Overview
Problem
The installation and removal of submersible pumps in liquefied gas storage tanks require excessive amounts of expensive purge gas to prevent boil-off gas release and pose safety risks to workers due to exposure to low-temperature cables and boil-off gas.
Innovation Solution
A pump installation apparatus with an actuator-driven door, suspension cable, and crane system that allows for remote operation, minimizing purge gas use and ensuring a safe working environment by containing boil-off gas within an enclosed working space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the upper opening of the pump column is left open for pump installation and removal, then the pump can be easily installed and removed, but a large amount of expensive purge gas is required to prevent boil-off gas from being released and air from entering
Solution Approach 1:
The pump column is divided into two separate openings: a large upper opening for easy pump installation and removal, and a smaller purge-gas introduction port for gas injection. This segmentation allows the large opening to remain open without requiring excessive purge gas, as the smaller port suffices for maintaining internal pressure and preventing boil-off gas escape.
Solution Approach 2:
A purge gas introduction port serves as an intermediary mechanism that injects purge gas directly into the pump column interior. This mediator allows the system to maintain positive pressure and prevent external air infiltration without requiring the entire upper opening to be sealed, thus reducing overall purge gas consumption while enabling easy pump access.
2Reliability
If purge gas is used to prevent boil-off gas release during pump installation and removal, then boil-off gas containment is improved, but worker safety deteriorates due to exposure to low-temperature cables and boil-off gas
Solution Approach 1:
The hazardous elements (boil-off gas and low-temperature cables) are extracted from the working environment by performing pump installation and removal operations outside the pump column. The pump is suspended by a cable from above and lowered into the column through the open upper opening, keeping workers away from the confined space where boil-off gas accumulates and where cold cables are handled.
Solution Approach 2:
The pump column itself serves the containment function through its structural design with the purge-gas introduction port, eliminating the need for additional protective equipment or procedures around workers. The system self-regulates by maintaining internal pressure to prevent boil-off gas escape, thereby protecting the external working environment without requiring worker proximity to hazardous zones.
3Ease of operation
If a large upper opening is used for pump installation, then pump access is improved, but the amount of purge gas required increases significantly
Solution Approach 1:
The opening system is segmented into a large upper opening for pump access and a separate small purge-gas introduction port for gas injection. This allows the large opening to remain open without proportionally increasing purge gas requirements, as the smaller port is sufficient for maintaining internal pressure and preventing air infiltration.
Solution Approach 2:
Purge gas is injected locally through the purge-gas introduction port positioned at the appropriate location within the pump column. This localized injection approach is more efficient than attempting to seal and pressurize through a large opening, reducing the total volume of purge gas needed while maintaining effective containment.
Data Source
AI summary
The pump installation apparatus includes a working chamber forming a closed working space, an actuator-driven door covering an upper opening of a pump column, a suspension cable for suspending a submersible pump in the pump column, and a crane for raising and lowering the suspension cable. An upper opening of the pump column, the actuator-driven door, and the crane are arranged in the working space.