Low-Temperature Evaporation-Crystallization for Waste Stream Solids
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Solution Overview
Problem
Conventional evaporation-crystallization processes for waste streams containing high solubility salts require clarification and chemical conditioning, leading to increased system footprint, capital costs, and maintenance, and are inefficient in removing dissolved solids at high temperatures, which can cause corrosion.
Innovation Solution
An evaporation-crystallization process operating at low temperatures (less than 60°C) and low pressures, using a dual-stage system with a liquid-solid separator to precipitate and crystallize dissolved solids without clarification or chemical conditioning, effectively reducing the concentration of dissolved species in waste streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional evaporation-crystallization processes are used at high temperatures, then dissolved solids can be removed from waste streams, but corrosion occurs and system reliability decreases
Solution Approach 1:
The patent changes the operating parameters from high temperature to low temperature (below 60°C) and from atmospheric pressure to reduced pressure. This parameter change allows evaporation-crystallization to proceed effectively without causing corrosion, resolving the contradiction between removing dissolved solids and preventing corrosion.
Solution Approach 2:
The patent utilizes phase transition of water from liquid to vapor at low temperatures and reduced pressure to enable evaporation-crystallization. By operating below atmospheric pressure, water evaporates at temperatures below 60°C, allowing solid precipitation without the high-temperature corrosion problems of conventional methods.
2Reliability
If clarification and chemical conditioning are used, then dissolved solids can be removed, but system footprint and capital costs increase
Solution Approach 1:
The patent extracts and eliminates the need for clarification and chemical conditioning stages from the conventional treatment train. By using reduced-pressure evaporation-crystallization, the system directly precipitates and removes dissolved solids without requiring separate clarification tanks or chemical dosing systems, thereby reducing system footprint and capital costs while maintaining removal efficiency.
Solution Approach 2:
The patent merges the evaporation, crystallization, and solid-liquid separation functions into a single integrated system. The evaporator also serves as the crystallization chamber, and the same equipment performs both water removal and solid separation, eliminating the need for separate clarification and conditioning units.
3Reliability
If conventional evaporation processes are used, then dissolved solids are removed, but operational costs increase due to high energy consumption
Solution Approach 1:
The patent changes the operating pressure parameter from atmospheric to reduced pressure, which lowers the boiling point of water and enables evaporation at temperatures below 60°C. This parameter change significantly reduces the energy input required for evaporation while maintaining effective dissolved solids removal, thereby resolving the contradiction between removal effectiveness and energy consumption.
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 process efficiently removes dissolved solids from waste streams, such as those from flue gas scrubbers, without the need for clarification or chemical conditioning, reducing corrosion risks and operational costs, while maintaining a smaller system footprint.
Implementation Method 1
Water forming a part of the waste stream is evaporated which causes the waste stream to be concentrated
Implementation Method 2
dissolved solids precipitating and crystallizing which results in the formation of a slurry stream
Implementation Method 3
The slurry stream is directed to a liquid-solid separator which separates the crystallized solids from the slurry
Data Source
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AI summary
A method for removing dissolved solids from a waste stream, such as that produced in flue gas scrubbing, through an evaporation-crystallization process operated at relatively low temperature. A waste stream is directed into an evaporator and heated at a temperature of less than 6O°C at a pressure below atmospheric pressure. The waste stream is concentrated through the evaporation process and forms a slurry stream having crystallized solids. At the low temperature of evaporation, the solids crystallize at substantially lower temperature and the solution has a substantially lower boiling point elevation than at atmospheric pressure. The slurry stream is directed to a solid-liquid separator where the crystallized solids in the slurry stream are separated, producing a solid cake and mother liquor.