Heat Exchanger Tube Bundle Cleaning via Inverted Lance

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Solution Overview

Problem

Existing cleaning methods for heat exchanger tube bundles are ineffective in reaching deep inside the bundle and between finned tubes due to limited penetration and reaction forces that can lift the cleaning carriage off the bundle, leading to incomplete cleaning and operational challenges.

Innovation Solution

A cleaning robot with a carriage equipped with motorized wheels or caterpillar tracks and a holder for a lance that penetrates between the tubes, using laterally directed high-pressure water jets to maintain contact and achieve thorough cleaning, with an actuator for adjusting lance depth and a pivoting mechanism for efficient sector cleaning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a spray lance is introduced from outside the tube bundle to clean the tubes, then the cleaning apparatus can access the tube surfaces, but the reaction force of the jet lifts the carriage off the bundle, preventing effective cleaning

Engineering Contradiction:

Improvecleaning accessibilityVSAvoidreaction force

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The lance is inverted to spray upward from below the tube bundle rather than downward from above. This reverses the direction of the jet force, allowing the reaction force to press the carriage against the bundle rather than lifting it away, thereby maintaining contact and enabling effective cleaning

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The upward spray direction creates a downward reaction force that counteracts the weight of the carriage, pressing it against the tube bundle. This counterforce mechanism ensures stable contact during cleaning operation

Inventive Principle:

Principle #8Anti-weight (Counterweight)

2Device complexity

If the lance sprays from outside the bundle, then the apparatus structure is simple, but the jet cannot reach very far into the bundle and can only clean surfaces in direct line of sight

Engineering Contradiction:

Improveapparatus structureVSAvoidcleaning penetration depth

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

By inverting the lance to spray upward from beneath the tube bundle, the cleaning jet can penetrate deep into the bundle structure and reach surfaces that are otherwise inaccessible from external spraying, dramatically improving penetration depth while maintaining relatively simple apparatus structure

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The cleaning approach transitions from external surface spraying to internal penetration spraying by positioning the lance beneath the bundle. This dimensional change allows the jet to travel through the bundle interior and clean deep-seated surfaces

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Force

If weights are loaded onto the carriage to prevent lifting, then the carriage remains in contact with the bundle, but the cleaning effectiveness is reduced due to the lifting reaction force

Engineering Contradiction:

Improvecontact stabilityVSAvoidcleaning effectiveness

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

Instead of adding weights to counteract the lifting force, the spray direction is inverted so that the reaction force itself becomes a pressing force. This eliminates the need for additional weights and ensures consistent contact pressure throughout the cleaning process

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The reaction force that initially caused the carriage to lift off is converted into a beneficial pressing force by inverting the spray direction. The same force that was harmful becomes the mechanism ensuring stable contact and effective cleaning

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

The robot provides thorough and efficient cleaning of heat exchanger tube bundles by maintaining contact and adjusting penetration depth, ensuring complete removal of deposits without lifting off the bundle, even in complex geometries, enhancing cleaning effectiveness and operational simplicity.

Implementation Method 1

a traction mechanism comprising motorised wheels or a pair of motorised caterpillar tracks which, in use, make frictional contact with the outer surface of the bundle to advance the carriage relative to the bundle

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

connected to water under high pressure and to clean the bundle by the force of one or more water jets discharged from the lance

Methodology Applied

Scientific EffectJet Erosion: Jet Erosion

Data Source

PatentUS9952008B2Cleaning of heat exchanger core

Publication Date: 2018.04.24 TUBE TECH IND LTD

AI summary

An apparatus is described for cleaning the exterior of a furnace heat exchanger that includes a bundle of finned convection or bare radiant tubes heated when in use by the flue gases of a heater furnace. The apparatus comprises a motorized carriage 10 guided for movement along the outer surface of the bundle in a direction parallel to the tubes and a holder 24 on the carriage for holding a lance 20 in a position relative to the carriage 10 that permits the lance 20 to penetrate between the tubes of the bundle and to be advanced along the core by the carriage while remaining in the latter position.