Gas Scrubber Shield Separation for Liquid Entrainment Control

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Solution Overview

Problem

The entrainment of scrubbing liquid in scrubbers due to high exhaust gas velocity and reduced draining capabilities leads to increased back pressure, scrubbing liquid hold-up, and reduced efficiency, particularly in multi-stage scrubbing systems.

Innovation Solution

Incorporation of a separation device with a shield element having perforated holes to separate scrubbing liquid from the gas flow, allowing it to be collected and drained upstream of the deflector device, facilitated by a drain outlet and drain pipe.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a deflector device is provided in the scrubbing chamber to prevent scrubbing liquid from flowing into the exhaust gas line, then the scrubbing liquid drainage capability is improved, but the gas velocity increases due to limited available area, which causes scrubbing liquid entrainment to a higher level

Engineering Contradiction:

Improvescrubbing liquid drainage capabilityVSAvoidgas velocity

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The scrubbing chamber is divided into multiple scrubbing sections with intermediate deflector devices, segmenting the gas flow path. This allows scrubbing liquid to be drained at multiple levels rather than one location, reducing entrainment in each segment while maintaining overall drainage capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An intermediate deflector device is introduced as a mediator between the gas inlet and exhaust gas line. This deflector creates a barrier that redirects gas flow while allowing scrubbing liquid to drain through designated openings, preventing direct carry-over to the exhaust line.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If the available area for exhaust gas to pass is limited to minimize the overall footprint of the scrubber, then the compactness is improved, but the gas velocity becomes high, making it difficult to drain scrubbing liquid and causing entrainment

Engineering Contradiction:

Improvescrubber footprintVSAvoidscrubbing liquid drainage capability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The deflector devices are arranged radially around the central gas passage, utilizing the radial dimension to create multiple drainage paths. Scrubbing liquid can drain both axially downward and radially outward through the deflector structures, adding dimensional complexity to the drainage system.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If scrubbing liquid is sprayed into the scrubbing chamber to react with exhaust gas for removing contaminants, then the cleaning effectiveness is improved, but scrubbing liquid entrainment increases due to high gas velocity

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidscrubbing liquid entrainment

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The high gas velocity that causes entrainment is converted into a benefit by using it to drive scrubbing liquid through the deflector device openings and toward the drainage system. The kinetic energy of the gas flow is harnessed to enhance liquid removal rather than just being a harmful effect.

Inventive Principle:

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

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

Reduces scrubbing liquid entrainment, enhances drainage efficiency, and maintains scrubber performance by preventing liquid from being forced towards the gas outlet, thereby reducing back pressure and improving overall cleaning effectiveness.

Implementation Method 1

The dynamic pressure will vary in the scrubbing chamber. In particular, the dynamic pressure outside the shield element will be higher than in the collecting gap between the shield element and the upstream surface of the downstream deflector device. This pressure difference will force at least a part of the droplets, hitting the shield element, to enter the collecting gap via the holes

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

scrubbing liquid is sprayed into the scrubbing chamber, which may comprise one or more scrubbing sections, to react with the exhaust gas for removing contaminants, such as sulfur, soot and particles

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 3

A lower scrubbing chamber deflection body is arranged above the opening of the exhaust gas tube for redirecting the exhaust gas towards the walls of the scrubber and for creating turbulent gas flow

Methodology Applied

Scientific EffectTurbulence: Turbulence

Implementation Method 4

The shield element is arranged so as to provide a collecting gap between the upstream surface and the shield element, and the holes extend through the shield element from the scrubbing chamber, or outside the shield element, to the collecting gap to permit scrubbing liquid to enter the collecting gap through the holes and the shield element and be collected in the collecting gap

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentEP3661629B1A scrubber for cleaning of a gas

Publication Date: 2026.03.11 ALFA LAVAL CORP AB

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AI summary

A scrubber (1) for cleaning of a gas comprises a casing (3) extending along a longitudinal central axis (x) and enclosing a scrubbing chamber (4). The casing has a gas inlet (5) and a gas outlet. The casing is configured to permit a gas flow of the gas to flow through the scrubbing chamber in a flow direction (F) from the gas inlet to the gas outlet. A deflector device (12) is provided in the scrubbing chamber between the gas inlet and the gas outlet and forms a gas passage (28) between the deflector device (12) and the casing (3). The deflector device comprises an upstream surface (16) facing the gas inlet. A spraying nozzle (8) is configured to spray a scrubbing liquid into the scrubbing chamber and the gas flow. A separation device (40) comprises a shield element (41) and is arranged between the upstream surface of the deflector device and the gas inlet. The shield element shields the upstream surface from the gas flow and is perforated by a plurality of holes.