Air Separation Plant Pressure Control for Variable Oxygen Pipelines

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Solution Overview

Problem

Air separation units (ASUs) face inefficiencies when supplying oxygen to pipelines with variable pressure, as they are designed to operate at constant pressures, leading to suboptimal performance when pipeline pressures fluctuate.

Innovation Solution

Designing ASU equipment with flexibility to adjust gaseous oxygen production pressure to match pipeline pressure, using a process control strategy to automatically adjust product pressure and maintain constant discharge pressure of boosters, thereby optimizing liquid production without additional compression or expansion steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the ASU is designed to provide oxygen gas at a constant pressure above the highest expected pipeline pressure, then the ASU operates efficiently at steady state conditions, but energy is wasted through pressure letdown across a control valve when pipeline pressure is below design pressure

Engineering Contradiction:

Improvesteady state operationVSAvoidpressure letdown energy loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements dynamic pressure control by adjusting the discharge pressure of the liquid oxygen pump to match the actual pipeline pressure in real-time, replacing the static constant pressure design with a dynamic adaptive system that eliminates unnecessary pressure letdown and energy waste

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the operating pressure parameter of the liquid oxygen pump discharge based on pipeline pressure conditions, allowing the ASU to adapt its output pressure to match actual demand and avoid energy losses from fixed high-pressure operation followed by pressure reduction

Inventive Principle:

Principle #35Parameter changes

2Stress or pressure

If a control valve is used to let down the pressure of gaseous oxygen to match pipeline pressure, then the oxygen can be introduced to the pipeline at the correct pressure, but liquid production decreases when pipeline pressure is below design pressure

Engineering Contradiction:

Improveoxygen delivery pressureVSAvoidliquid oxygen production

Core Design Contradiction:

Stress or pressureVSProductivity

Solution Approach 1:

The patent adjusts the discharge pressure parameter of the liquid oxygen pump to match pipeline pressure, which directly increases liquid oxygen production by eliminating the pressure differential that limits production capacity in conventional constant-pressure systems

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If the ASU operates at constant pressure design, then equipment can be optimized for steady state efficiency, but the system cannot adapt to variable pipeline pressure conditions

Engineering Contradiction:

Improvesteady state efficiencyVSAvoidpressure variation adaptation

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The patent transforms the static constant-pressure operation into dynamic variable-pressure operation by continuously adjusting the liquid oxygen pump discharge pressure to match pipeline pressure, enabling the system to adapt to varying demand conditions while maintaining energy efficiency

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The liquid oxygen pump is designed to perform multiple functions: it can operate at variable discharge pressures to match different pipeline conditions, eliminating the need for separate pressure regulation equipment and enhancing system versatility

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 increases liquid oxygen and nitrogen production by reducing energy losses and heat exchange inefficiencies, enhancing refrigeration availability without increasing power usage, and maintaining process stability despite pipeline pressure variations.

Implementation Method 1

cooling the gaseous oxygen stream in the heat exchanger by indirect heat exchange against a liquid oxygen stream to condense the gaseous oxygen into liquid oxygen

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

condense the gaseous oxygen into liquid oxygen

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 3

pumped from low pressure to a higher pressure than that of the pipeline

Methodology Applied

Scientific EffectPumping: Pump

Data Source

PatentUS10260802B2Apparatus for operating an air separation plant

Publication Date: 2019.04.16 LAIR LIQUIDE SA POUR LETUDE & LEXPLOITATION DES PROCEDES GEORGES CLAUDE

AI summary

An apparatus for the production of air gases with variable liquid production by the cryogenic separation of air can include a cold box having a heat exchanger, and a system of columns; a pressure monitoring device; and a controller. The cold box can be configured to receive a purified and compressed air stream under conditions effective for cryogenically separating the air stream to form an air gas product. The apparatus may also include means for transferring the air gas product from the cold box to an air gas pipeline. The pressure monitoring device is configured to monitor the pipeline pressure, and the controller is configured to adjust the product pressure of the air gas product coming out of the cold box based upon the pipeline pressure and to further adjust liquid production from the cold box based on the adjusted product pressure.