Compressor Driver Power Limiting via Selective Inlet Throttling

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Solution Overview

Problem

Existing control schemes for multistage turbocompressors fail to reduce shaft power consumption while maintaining the compressor train in a stable operating condition, as throttling inlet valves can drive the compressor stages closer to surge, negating any power reduction and risking shutdown.

Innovation Solution

Implement a control strategy that selectively closes inlet throttling valves on all compressor stages except those near surge, using a power limiting approach to reduce driver power consumption while maintaining the compressor flow out of the surge region, utilizing a network of controllers to monitor and adjust valve positions based on driver overload and compressor performance maps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If inlet throttle valves are closed to reduce flow through compressor stages, then shaft power consumption is reduced, but the compressor operating point is driven nearer to surge

Engineering Contradiction:

Improveshaft power consumptionVSAvoidcompressor surge stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces a controller as an intermediary that coordinates between the inlet throttle valves and antisurge valves. The controller enables the inlet throttle valves to close for power reduction while simultaneously opening the antisurge valves to maintain compressor stability, thus mediating the conflict between power consumption and surge prevention

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent combines the functions of inlet throttle valves (for power control) and antisurge valves (for stability control) into a unified control strategy. By merging these two valve systems under a single control algorithm, the system achieves both power reduction and surge prevention simultaneously rather than treating them as separate conflicting objectives

Inventive Principle:

Principle #5Merging (Combining)

2Use of energy by moving object

If inlet throttle valves are closed to reduce driver power consumption, then power consumption is reduced, but compressor shutdown may be required to avoid damage

Engineering Contradiction:

Improvedriver power consumptionVSAvoidcompressor damage from surge

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by proactively opening the antisurge valves before compressor surge can occur. The control system continuously monitors the compressor operating point and anticipates surge conditions, opening the antisurge valves in advance to prevent the harmful surge phenomenon and subsequent compressor damage

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the potentially harmful effect of reduced inlet flow (which drives the compressor toward surge) into a beneficial outcome by using the antisurge valves to deliberately recirculate flow. This controlled recirculation transforms what would be a dangerous condition into a safe operating state, allowing power reduction without risking compressor damage

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS8323000B2Compressor-driver power limiting in consideration of antisurge control

Publication Date: 2012.12.04 CONOCOPHILLIPS CO

AI summary

A control method and apparatus for simultaneously protecting a compression system from driver overpowering and turbocompressor surge. When overpowering is detected, flow rate through the each compressor in the turbocompressor train is reduced by closing an inlet throttling valve at the inlet of each respective compressor stage unless a compressor operating point is sufficiently near surge. In this latter case, the inlet throttling valve is not closed. In this way, overall flow rate through the compressor train is reduced while maintaining adequate flow through compromised stages to avoid surge.