Compressor Surge Prevention via Supplemental Gas Injection

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Solution Overview

Problem

During the start-up and turndown periods of paraffin dehydrogenation (PDH) processes, the gas composition in the product compressor deviates from the normal operating range, leading to compressor surge, equipment damage, and increased capital costs due to the need for dynamic compressors rated for heavier gases, which are not suitable for normal operation.

Innovation Solution

A method is introduced to maintain a consistent gas composition by providing supplemental hydrocarbon and hydrogen streams to the product compressor based on measurements of average molecular weight, hydraulic pressures, and inlet gas temperature, ensuring the gas composition remains within the desired range during start-up and turn down, thereby preventing compressor surge and reducing capital expenditures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a dynamic compressor rated for heavier gas is employed during start-up, then the compressor can handle the heavier gas composition, but the capital cost increases and the compressor is not suitable for normal operation

Engineering Contradiction:

Improvecompressor operating rangeVSAvoidcompressor rating requirements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the physical parameters of the gas stream by injecting supplemental hydrocarbon and hydrogen streams to modify the average molecular weight. This allows the compressor to operate within its designed parameters throughout both start-up and normal operation, eliminating the need for a specially rated compressor.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces supplemental hydrocarbon and hydrogen streams as intermediary substances to modify the gas composition. These intermediary streams act as mediators between the heavy start-up gas and the compressor's operational requirements, enabling the compressor to handle varying gas compositions without requiring special ratings.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the product compressor is supplied with heavier gas during start-up, then the compressor can operate, but surge occurs causing equipment damage and reduced reliability

Engineering Contradiction:

Improvecompressor operational stabilityVSAvoidcompressor surge

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback control system that continuously monitors the average molecular weight of the gas stream and adjusts the injection rates of supplemental hydrocarbon and hydrogen streams accordingly. This feedback mechanism maintains the gas composition within the compressor's safe operating envelope, preventing surge conditions during start-up and turndown.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary anti-action by proactively modifying the gas composition before it enters the compressor during start-up conditions. By injecting supplemental streams in advance to lighten the gas, the system prevents surge from occurring rather than reacting to it after the fact.

Inventive Principle:

Principle #9Preliminary anti-action

3Productivity

If compression occurs at the reactor outlet, then dehydrogenation efficiency improves, but gas composition deviation during start-up requires compressor capability beyond normal operation

Engineering Contradiction:

Improvedehydrogenation efficiencyVSAvoidcompressor operating window

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent changes the compositional parameters of the gas stream through supplemental injection to maintain compatibility with the compressor's operating window. This allows the process to maintain high dehydrogenation efficiency with outlet compression while managing start-up gas composition to fit within the existing compressor's capabilities.

Inventive Principle:

Principle #35Parameter changes

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 stabilizes the gas composition, reduces the risk of compressor surge, and extends equipment life by maintaining optimal operating conditions, thereby enhancing the reliability and efficiency of the product compressor and downstream separation systems.

Implementation Method 1

reacting a feed stream over a catalyst to produce a gas stream and spent catalyst

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

passing the gas stream to a compressor

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS12012557B2Start-up method for contacting a feed stream with fluidized catalyst

Publication Date: 2024.06.18 UOP LLC

AI summary

A start-up method for contacting a feed stream with fluidized catalyst is disclosed. The start-up method comprises reacting a feed stream over a catalyst to produce a gas stream and spent catalyst. The gas stream is separated from the spent catalyst. The separated gas stream is passed to a compressor. The operating condition associated with the compressor is measured. Based on the measured operating condition associated with the compressor, one or both of a supplemental hydrocarbon stream and a supplemental hydrogen gas stream is provided to the compressor to meet a predetermined operating condition associated with the compressor.