Cooling Tower Heat Exchanger Scale Removal by Parallel Air Blasts
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Solution Overview
Problem
Cooling towers in power stations face issues with mineral salt deposits on heat exchange surfaces, which hinder heat exchange efficiency, provide a habitat for germ proliferation, and impose structural loads, with existing solutions like chemical treatment, mechanical shaking, or disassembly being costly or ineffective.
Innovation Solution
A method involving a low-pressure air blast generator that creates a parallel flow to detach and remove scale deposits from heat exchange bodies and droplet separators, using a device with a compressed gas source, nozzle, and control system to generate a continuous succession of blasts, and optionally heating the area to increase flexibility of thermoplastic walls for easier scale removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical treatment of water is used to prevent scaling, then heat exchange surfaces remain clean, but operating costs increase due to effluent treatment requirements
Solution Approach 1:
The patent replaces chemical treatment methods with a mechanical cleaning system using a shock wave generator that produces acoustic waves to detach mineral deposits from heat exchange surfaces. This substitution eliminates the need for chemical effluent treatment while maintaining surface cleanliness, directly resolving the contradiction between reliability and device complexity.
2Reliability
If mechanical shaking of the heat exchange body is used to remove deposits, then cleaning effectiveness is achieved, but the heat exchange body deteriorates and becomes unsuitable for subsequent use
Solution Approach 1:
The patent replaces direct mechanical contact cleaning (shaking) with a contactless acoustic cleaning method. The shock wave generator produces acoustic waves that propagate through the heat exchange body, creating localized elastic deformations that detach deposits without physically touching or damaging the structure, thus maintaining both cleaning effectiveness and structural integrity.
Solution Approach 2:
The patent utilizes acoustic vibrations generated by the shock wave to induce elastic deformations in the heat exchange body walls. These vibrations cause the brittle mineral deposits to detach from the flexible walls, achieving cleaning effectiveness while avoiding the structural damage associated with direct mechanical shaking.
3Reliability
If the heat exchange body is disassembled for mechanical cleaning, then thorough cleaning is achieved, but cleaning costs increase due to the large volume and complexity of the body
Solution Approach 1:
The patent enables the heat exchange body to be cleaned in situ without disassembly. The shock wave generator is positioned adjacent to the body and produces acoustic waves that propagate through the entire volume of the heat exchange body, allowing thorough cleaning of all internal surfaces while the body remains installed, thereby eliminating the complexity and costs associated with disassembly and reassembly operations.
4Reliability
If high pressure is used to blast away deposits, then cleaning power is increased, but the heat exchange body structure is damaged
Solution Approach 1:
The patent uses acoustic pressure waves instead of direct high-pressure mechanical blasting. The shock wave generator produces high-intensity acoustic waves that create localized elastic deformations in the heat exchange body walls, generating sufficient cleaning power to detach deposits while the flexible nature of the walls prevents permanent structural damage that would occur with direct high-pressure mechanical impact.
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
Effectively removes scale deposits in situ without structural damage, enhances cleaning power through abrasive action, and reduces operational costs by avoiding chemical treatments and mechanical disassembly, maintaining heat exchange efficiency while preventing germ proliferation.
Implementation Method 1
generating at least one air blast in large quantity and low pressure (e.g. of the order of 2 bars to 12 bars) by means of a generator serving to expand a mass of compressed gas
Implementation Method 2
giving rise as it passes to a kind of expansion of the inside channels of the element to be descaled and thus giving rise to local elastic deformation of the walls of said channels, the deformation being of an amplitude that is sufficient for the scale, which is hard or brittle, to become detached therefrom
Implementation Method 3
The flow of gas inside the element for cleaning suffers significant head loss such that the blast progresses into the inside of the body over a depth that corresponds to substantially half the total thickness of said element when it is a heat exchange body... The flow of gas tends to entrain at least some of the detached particles inside the channels, and it is found that they have an abrasive effect that increases the cleaning power of the method
Data Source
AI summary
A method of in situ scale removal from a heat exchange body suspended in a wet cooling tower, wherein the method generates at least one air blast by means of a generator implementing controlled expansion via a nozzle of a mass of compressed gas in a nozzle towards a zone of the body, the generator being opened at a distance (H) from said zone, and the method consisting in repeating said operation after moving the generator under the body outside said zone.