Method and apparatus for reducing process disturbances during pressurization of an adsorber in an air separation unit
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Solution Overview
Problem
Conventional air separation units face process disturbances and reduced throughput due to the need to adjust air flow for adsorber pressurization, leading to inefficient operation and increased MAC size.
Innovation Solution
A high pressure buffer tank is used to store a portion of the boosted air stream, allowing for constant air flow to the MAC and eliminating the need for IGV adjustments, thereby maintaining continuous operation and increasing ASU throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a portion of processed air is reserved for adsorber pressurization, then the adsorber can be re-pressurized, but the amount of continuous air delivered by the MAC is reduced
Solution Approach 1:
The invention applies preliminary action by continuously filling the buffer tank with pressurized air from the BAC during normal operation, so that when pressurization is needed, the pre-stored air is immediately available without affecting continuous air delivery to the process
Solution Approach 2:
The buffer tank acts as an intermediary between the BAC and the adsorber pressurization system, decoupling the continuous pressurization supply from the periodic adsorber pressurization demand, thereby eliminating the trade-off between reliability and productivity
2Reliability
If the IGV is adjusted to increase air flow for adsorber pressurization, then the pressurization requirement is met, but process upset occurs in the ASU
Solution Approach 1:
The air flow is segmented into two independent paths: one continuous path through the MAC to the process, and another path through the BAC to the buffer tank for pressurization. This segmentation allows the IGV to remain fixed for process stability while the buffer tank supplies pressurization air independently
Solution Approach 2:
The buffer tank serves as an intermediary that absorbs the variability of pressurization demand, preventing it from propagating to the main process air flow and causing upset, thereby maintaining process stability while fulfilling pressurization requirements
3Reliability
If the MAC is sized to accommodate additional air for pressurization, then pressurization capacity is sufficient, but the MAC size increases
Solution Approach 1:
The BAC performs the pressurization function in advance by continuously filling the buffer tank, allowing the MAC to be sized for its primary continuous air delivery function without needing excess capacity for periodic pressurization demands
Solution Approach 2:
The system uses its own BAC output to service the pressurization requirement independently, eliminating the need for the MAC to be oversized for this secondary function, thereby optimizing MAC size for its main purpose
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 solution stabilizes the ASU operation, increases throughput, and reduces the need for larger MAC equipment by maintaining constant air flow and utilizing high-pressure compressed air for adsorber re-pressurization.
Implementation Method 1
FEP unit 20 includes a set of adsorbers that operate in a permutative fashion. While one adsorber A is operating in an adsorption cycle, the other adsorber P is being regenerated and then pressurized.
Implementation Method 2
a second portion is further boosted in the BAC 30 to form a boosted stream 32. This boosted stream 32 is then introduced to the cold box 40 at a higher pressure than the first portion 24 such that the boosted stream 32 can provide additional refrigeration via expansion within the cold box 40.
Implementation Method 3
the boosted stream 32 can provide additional refrigeration via expansion within the cold box 40
Data Source
AI summary
A method for reducing process disturbances during pressurization of an adsorber in an air separation unit is provided, in which the air separation unit includes a front end purification unit and an air buffer tank. In one embodiment, the method can include the steps of: pressurizing a first adsorber while a second adsorber operates in an adsorption cycle, wherein the step of pressurizing the first adsorber further includes the steps of withdrawing a pressurized air stream from the air buffer tank and introducing the pressurized air stream to the first adsorber until the first adsorber is at a target pressure, wherein the air buffer tank is in fluid communication with the booster air compressor, wherein the method further includes the step of continually sending a first portion of air flow from the booster air compressor to the air buffer tank and continually sending a second portion of air flow from the booster air compressor to a system of columns within a cold box for rectification therein.