Oil-Injected Compressor Cooling Control to Prevent Condensate

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing compressor devices with oil-injected compressor elements face issues with condensate formation downstream of the oil separator, leading to inefficiencies and shorter oil lifetime due to high temperature settings required to prevent condensate, which are not effectively controlled by traditional methods.

Innovation Solution

A compressor device with controllable cooling means and a control unit that measures and adjusts the temperature of the compressed gas downstream of the oil separator to maintain a temperature above the dew point, using a feed-forward or master-slave control system to stabilize and optimize the cooling process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the temperature of compressed gas downstream of the oil separator is controlled to be sufficiently high above the dew point (typically 20°C), then condensate formation is prevented, but oil lifetime decreases and compressor efficiency reduces

Engineering Contradiction:
Improvecondensate preventionVSAvoidoil lifetime
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The control unit continuously monitors the actual temperature downstream of the oil separator and adjusts the cooling means accordingly to maintain the temperature within the optimized range, preventing condensate formation while minimizing oil temperature degradation

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system changes the temperature parameter from a fixed high margin (20°C above dew point) to a dynamically optimized margin (minimum necessary above dew point), thereby reducing oil temperature and extending oil lifetime while still preventing condensate

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If the temperature control is based on the outlet temperature of the compressor element, then the control system is simpler, but the temperature downstream of the oil separator drops below the dew point causing condensate formation

Engineering Contradiction:
Improvecontrol system complexityVSAvoidcondensate prevention
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The control system takes preliminary action by measuring and controlling the temperature downstream of the oil separator (where condensate would form) rather than waiting to measure at the outlet, preventing the harmful effect before it occurs

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary temperature measurement and control point downstream of the oil separator, which acts as a mediator between the compressor outlet and the final outlet, ensuring temperature is maintained at the critical location where condensate formation occurs

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If the temperature control responds only when condensate conditions occur downstream of the oil separator, then the control is more targeted, but the response is too late and leads to temperature instabilities

Engineering Contradiction:
Improvetemperature control precisionVSAvoidtemperature stability
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The control unit uses feedback from the downstream temperature sensor to continuously adjust the cooling means, maintaining stable temperature control downstream of the oil separator and preventing the instabilities that would occur with delayed response

Inventive Principle:
Principle #23Feedback

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 effectively prevents condensate formation while keeping the oil temperature low, enhancing the compressor's efficiency and extending its lifespan by allowing for more precise control of the temperature downstream of the oil separator.

Implementation Method 1

a cooler (16) which can be bypassed by means of a bypass line (17)

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

a controlled mixing valve (18) with an inlet (19) and two outlets (20a, 20b), the mixing valve (18) having its inlet (19) and one of the outlets (20a) connected to the injection line (10) and the other outlet (20b) connected to the bypass line (17)

Methodology Applied
Scientific EffectFluid mixing:

Implementation Method 3

an oil-injected compressor element (2) with an inlet (3) for gas to be compressed and an outlet (4) for compressed gas

Methodology Applied
Scientific EffectGas compression: Compression

Implementation Method 4

an outlet (4) for compressed gas, wherein the outlet (4) connects to an oil separator (9)

Methodology Applied
Scientific EffectOil-gas separation: Centrifugal Separation

Data Source

PatentEP4211353B1Compressor device and method for controlling such compressor device
Publication Date: 2024.07.03 ATLAS COPCO AIRPOWER NV
  • EP4211353B1 patent drawingFigure 1~2
  • EP4211353B1 patent drawingFigure 3

AI summary

Compressor device comprising an oil-injected compressor element (2) with an outlet (4) connected via an outlet line (8) to an oil separator (9) which is connected via an injection pipe (10) to the compressor element (2), wherein controllable cooling means (15) for the oil are provided, the compressor device (1) being provided with a control unit (21) and thereto connected measuring means (22a, 22b) for controlling the cooling means (15) to control a temperature (T_uit_afsch) downstream of the oil separator (9), the measuring means (22a, 22b) including means (22a) for determining a temperature (T_uit) at the outlet (4) and a temperature sensor (22b) for determining the temperature (T_uit_afsch) downstream of the oil separator (9), the control unit (21) including a controller (25) for controlling the cooling means (15) on the basis of signals from said measuring means (22a, 22b) and on the basis of a dew point.