Flue Gas Desulfurization by Cooling and Phase Separation
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Solution Overview
Problem
Existing flue gas desulfurization and decarbonization processes are energy-intensive, generate significant wastewater, and require large amounts of chemicals, leading to inefficiencies and environmental concerns.
Innovation Solution
A system and method utilizing a water cooler, washing tower, solid-liquid separator, and rectification separation column with low-temperature pentane to cool and separate SO2 and CO2 from flue gas, employing indirect heat exchange and low-temperature pentane washing to condense pollutants into a solid form, followed by rectification to separate CO2 and H2O.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wet desulfurization is adopted, then desulfurization effect is improved, but wastewater generation increases and chemical consumption increases
Solution Approach 1:
The patent utilizes phase transition by cooling flue gas to condense water vapor and facilitate SO2 absorption, replacing traditional wet desulfurization methods that generate large amounts of wastewater. The condensed water from phase change is used for dust settlement and equipment cleaning, achieving zero liquid discharge.
Solution Approach 2:
The patent changes the temperature parameter by cooling flue gas from high temperature to near ambient temperature, enabling efficient SO2 absorption and condensation without requiring large amounts of chemical absorbents, thus reducing both wastewater generation and chemical consumption.
2Object-affected harmful factors
If chemical absorption decarbonization is adopted, then CO2 removal is improved, but energy consumption increases and absorbent loss increases
Solution Approach 1:
The patent combines desulfurization and decarbonization into a single integrated system where both SO2 and CO2 are removed simultaneously through cooling and condensation processes, eliminating the need for separate chemical absorption units and reducing overall energy consumption and absorbent loss.
Solution Approach 2:
The patent uses phase transition of CO2 from gas to liquid or solid state through cooling, replacing energy-intensive chemical absorption methods. This physical separation process significantly reduces energy consumption while maintaining effective CO2 removal.
3Object-affected harmful factors
If molecular sieve drying is adopted, then flue gas drying is improved, but device complexity increases and operational costs increase
Solution Approach 1:
The patent extracts and removes water vapor from flue gas through condensation in the cooling process, eliminating the need for separate molecular sieve drying equipment. The condensed water is utilized for settlement and cleaning purposes, simplifying the overall system while achieving effective drying.
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 energy consumption, minimizes wastewater generation, and effectively recovers cold energy, enabling efficient desulfurization and decarbonization without molecular sieve drying, thereby reducing operational costs and environmental impact.
Implementation Method 1
a water cooler, having a flue gas inlet for feeding a boiler flue gas after denitrating and dedusting, a condensed water outlet in a bottom of the water cooler, and a wet flue gas outlet, and configured to cool the boiler flue gas to a temperature near a room temperature to obtain a wet flue gas and condensed water
Implementation Method 2
washing the wet flue gas with a washing liquid sprayed from top to bottom in the washing tower and cooling the wet flue gas to a desublimation temperature of carbon dioxide, to separate H2O, SO2 and CO2 in a solid form from the flue gas
Implementation Method 3
heating the solid H2O, SO2 and CO2 by a reboiler at a bottom of the rectification separation column to separate CO2 from SO2 and H2O
Data Source
AI summary
A method for desulfurizing and decarbonizing a flue gas includes: feeding a boiler flue gas after denitrating and dedusting to a water cooler; cooling the boiler flue gas in the water cooler to a temperature near room temperature, and discharging condensed water; feeding a wet flue gas to a washing tower; washing and cooling the wet flue gas with a washing liquid to separate H2O, SO2 and CO2 in a solid form from the flue gas; feeding a solid-liquid mixed slurry from a bottom of the washing tower to a solid-liquid separator to separate solid H2O, SO2 and CO2 from the washing liquid; feeding the solid H2O, SO2 and CO2 to a rectification separation column; separating CO2 from SO2 and H2O by a reboiler at a bottom of the rectification separation column; and discharging CO2, SO2 and H2O.