SO2 Scrubber Recirculation for PCDD/F Reduction
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Solution Overview
Problem
Existing methods for reducing polyhalogenated compounds like PCDD/F in incineration plants face limitations, particularly in achieving the required emission limits without significant efficiency losses due to the need for large amounts of recirculated flue gas, leading to increased waste-gas volume flow and reduced combustion temperatures.
Innovation Solution
Selective separation and recirculation of sulfur dioxide as sulfuric acid into the combustion chamber, optimizing the sulfur dioxide to hydrochloric acid ratio through a two-stage washing process, allowing for concentrated sulfur dioxide re-circulation without dilution, thereby enhancing dioxin reduction without auxiliary agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large amounts of flue gas are recirculated into the combustion chamber to increase the sulfur dioxide to hydrochloric acid ratio, then the PCDD/F emissions are reduced, but the waste-gas volume flow increases and combustion temperatures decrease
Solution Approach 1:
The invention extracts and separates sulfur dioxide from the flue gas using a scrubber system, isolating the beneficial component (SO2) from the harmful dilution effect of recirculating large volumes of flue gas. This allows selective reintroduction of SO2 without the negative consequences of full flue gas recirculation.
Solution Approach 2:
The flue gas treatment process is segmented into distinct stages: initial cooling, dust collection, SO2 separation in a scrubber, and selective SO2 recirculation. This segmentation allows each component to be treated independently, optimizing the S/Cl ratio without compromising combustion temperature.
2Object-affected harmful factors
If large amounts of flue gas are recirculated to achieve the desired sulfur dioxide to hydrochloric acid ratio, then PCDD/F formation is suppressed, but the waste-gas volume flow increases requiring larger equipment
Solution Approach 1:
The invention extracts only the necessary sulfur dioxide component from the flue gas using a scrubber, rather than recirculating the entire flue gas stream. This dramatically reduces the volume of gas that needs to be handled by downstream equipment, simplifying the overall system design.
Solution Approach 2:
The invention changes the concentration parameter of sulfur dioxide by separating and concentrating it in the scrubber before recirculation. This allows achieving the desired S/Cl ratio with much smaller gas volumes, reducing equipment size and complexity.
3Quantity of substance
If flue gas is recirculated to increase sulfur dioxide concentration, then the sulfur dioxide to hydrochloric acid ratio improves, but auxiliary heating or chemical additives are required to maintain combustion temperature
Solution Approach 1:
The invention extracts and concentrates sulfur dioxide in the scrubber, allowing recirculation of small volumes of SO2-rich gas. This eliminates the need for auxiliary heating or chemical additives that would be required if large volumes of diluted flue gas were recirculated, significantly reducing 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 approach effectively increases the sulfur dioxide to hydrochloric acid ratio in the waste gas, reducing chlorine content and PCDD/F formation, thereby meeting emission limits without efficiency losses, as the sulfur dioxide concentration is increased in areas of dioxin formation.
Implementation Method 1
separating out of sulfur dioxide from the flue gas in a scrubber
Implementation Method 2
combustion chamber (1) with an oxygen-containing primary and secondary gas feed-in (6, 16)
Data Source
AI summary
The invention relates to a method for reducing polyhalogenated compounds in incineration plants comprising at least one combustion chamber. The aim of the invention is to provide a more efficient method. To achieve this, SO2 is separated from the flue gas in at least one gas washer and is recirculated to the combustion chamber.