Oxygen Backup Tank Layout for Transient Supply Continuity
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Solution Overview
Problem
Existing air separation plants face challenges in maintaining a reliable oxygen supply during transient operations due to the need for separate high-pressure pumps and increased refrigeration costs, leading to inefficiencies and capital expenses.
Innovation Solution
A method and system utilizing a surge tank and reserve storage tank, where oxygen-rich liquid is pumped from the lower pressure column to a heat exchanger during normal operation and to an auxiliary vaporizer during transient operation, eliminating the need for separate high-pressure pumps and reducing refrigeration losses by locating the surge tank closer to the plant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a remote storage tank is used to accumulate liquid oxygen for transient operations, then oxygen supply reliability is improved, but capital expenses and device complexity increase due to the need for separate high-pressure pumps
Solution Approach 1:
The invention merges the functions of the remote storage tank and the plant heat exchanger by using the plant heat exchanger to serve dual purposes: cooling air during normal operation and vaporizing liquid oxygen during transient operations. This eliminates the need for separate auxiliary vaporizers and reduces the number of high-pressure pumps required, thereby lowering capital expenses and device complexity while maintaining oxygen supply reliability.
Solution Approach 2:
The plant heat exchanger is designed to perform multiple functions: it serves as the primary air cooling heat exchanger during normal operation and as an auxiliary vaporizer during transient operations when liquid oxygen is pumped from the remote storage tank. This multi-functionality eliminates the need for dedicated auxiliary vaporization equipment, reducing system complexity and capital costs.
2Reliability
If a remote storage tank is used to accumulate liquid oxygen, then oxygen supply reliability is improved, but energy efficiency deteriorates due to increased refrigeration losses
Solution Approach 1:
The invention implements preliminary action by continuously pumping liquid oxygen from the remote storage tank to the plant heat exchanger before transient operations occur. This maintains a ready supply of liquid oxygen in the plant heat exchanger, eliminating the need for rapid vaporization during transients and reducing refrigeration losses associated with sudden temperature changes and equipment startup.
Solution Approach 2:
The system maintains continuous useful action by continuously circulating liquid oxygen from the remote storage tank through the plant heat exchanger, even during normal operation. This ensures the liquid oxygen is already positioned and temperature-conditioned for immediate vaporization during transients, minimizing energy losses and maintaining operational readiness without requiring separate auxiliary systems.
3Reliability
If separate high-pressure pumps are provided for remote storage tank and plant, then oxygen supply reliability during transients is improved, but capital expenses increase
Solution Approach 1:
The plant high-pressure pump is designed to serve dual functions: pumping liquid oxygen from the plant to the product during normal operation and pumping liquid oxygen from the remote storage tank to the plant heat exchanger during transient operations. This eliminates the need for separate high-pressure pumps at the remote storage tank, reducing capital expenses while maintaining oxygen supply reliability during transients.
4Reliability
If liquid oxygen is continuously pumped from remote storage tank to plant heat exchanger, then oxygen supply readiness is improved, but refrigeration losses increase
Solution Approach 1:
The system implements self-service by using the cold liquid oxygen pumped from the remote storage tank to the plant heat exchanger to pre-cool the incoming air stream. This utilizes the cold energy of the liquid oxygen for its intended purpose of cooling, reducing the refrigeration load and minimizing refrigeration losses while maintaining oxygen supply readiness. The liquid oxygen serves itself by providing cooling during normal operation and vaporization during transients.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces capital expenses, minimizes refrigeration losses, and enhances energy efficiency by eliminating the need for additional high-pressure pumps and optimizing the location of the surge tank, ensuring a reliable oxygen supply during both normal and transient operations.
Implementation Method 1
a liquid oxygen stream composed of an oxygen-rich liquid column bottoms of a lower pressure column is pumped and then heated to supply the oxygen
Implementation Method 2
to an auxiliary vaporizer... the pumped liquid oxygen stream is heated within an auxiliary vaporizer to supply the oxygen during the transient
Data Source
AI summary
A method and backup system for backing up a supply oxygen in an air separation plant in which during normal operation, a stream of oxygen-rich liquid is pumped through a main flow path, extending from a surge tank to a heat exchanger, to deliver an oxygen product. The surge tank receives the oxygen-rich liquid from a bottom region of the lower pressure column of the plant. Additionally, during normal operations, a stream of the oxygen-rich liquid is also introduced to a reserve storage tank through a backup flow path. During a transient operation, where the air separation plant has ceased operation, the surge tank is isolated and liquid is pumped from the surge tank through an auxiliary flow path to an auxiliary vaporizer to continue the supply of the oxygen product and the surge tank is replenished with oxygen-rich liquid previously stored in the reserve storage tank.