Fluidized Bed Crystallizer for Scale Prevention in Thermal Desalination
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Solution Overview
Problem
The presence of dissolved minerals, particularly calcium and carbonates, in feed water limits the operating temperature and efficiency of thermal desalination systems, necessitating either low recovery rates and low temperatures or undesirable chemical pre-treatment.
Innovation Solution
A thermal desalination system incorporating a multi-effect evaporator with a fluidized bed crystallizer between effects to remove dissolved minerals and solids, using seed materials like sand particles to precipitate minerals, and a post-treatment unit to re-mineralize product water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the operating temperature is increased to improve efficiency, then the system efficiency improves, but calcium carbonate precipitation increases causing scale formation
Solution Approach 1:
The fluidized bed crystallizer performs preliminary removal of calcium and carbonate ions from the feed water before the water enters the evaporator effects. By pre-precipitating these minerals in the crystallizer, the water is protected from scale formation during subsequent high-temperature evaporation, allowing the system to operate at higher temperatures without damage from calcium carbonate precipitation.
2Object-affected harmful factors
If chemical pre-treatment is implemented to remove dissolved minerals, then scale formation is reduced, but the complexity and cost of the system increases
Solution Approach 1:
The fluidized bed crystallizer uses seed crystals to induce spontaneous precipitation of calcium carbonate from the feed water. This self-service mechanism eliminates the need for external chemical additives or complex pre-treatment systems, as the crystallizer naturally removes dissolved minerals through controlled crystallization on the seed material surface.
3Object-affected harmful factors
If the operating temperature is limited to prevent mineral precipitation, then scale formation is minimized, but the energy efficiency and cost-effectiveness deteriorate
Solution Approach 1:
By removing dissolved minerals in advance through the fluidized bed crystallizer, the system enables subsequent evaporation stages to operate at high temperatures without risk of scale formation. This preliminary purification allows the evaporator to function at optimal thermal efficiency, maximizing energy utilization while preventing mineral precipitation issues.
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 configuration allows for increased operating temperatures and improved efficiency by reducing dissolved solids, minimizing the need for chemical treatment and enhancing the cost-effectiveness of the desalination process.
Implementation Method 1
The fluidized bed crystallizer may be configured to precipitate said minerals on a seed material
Implementation Method 2
Water vapour is evaporated from the feed water and is passed through heating tubes in a subsequent effect
Implementation Method 3
fluidized bed crystallizer, configured to remove dissolved minerals and/or solids from the water
Data Source
AI summary
A thermal desalination system, comprising a multi-effect evaporator comprising a plurality of effects, configured to produce product water and brine and a fluidized bed crystallizer, configured to remove dissolved minerals and/or solids from the water, wherein the fluidized bed crystallizer is disposed between at least two effects of the multi-effect evaporator.