Lime Sorbent Composition for High-Moisture Flue Gas Scrubbing
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Solution Overview
Problem
Existing circulating dry scrubber (CDS) technologies face limitations in water addition, leading to clogging and operational instability due to sticky residues, and prior sorbents exhibit low conversion rates of calcium hydroxide to calcium sulfate, necessitating a solution that enhances water content without compromising process stability.
Innovation Solution
A sorbent manufacturing process involving quicklime slaking with specific additives like silicates, aluminates, and aluminosilicates, controlled to maintain residual moisture below 35% and molar ratios of silicon or aluminum to calcium between 0.02 and 0.2, ensuring good flowability and effective water retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water is added to improve pollutant removal performance in circulating dry scrubber, then capture levels of acid gases increase, but clogging and operational instability occur due to sticky residues
Solution Approach 1:
The patent applies preliminary action by pre-treating the sorbent residues with a specific composition containing calcium hydroxide, silicon compounds, and aluminum compounds before they are recirculated. This preliminary treatment modifies the chemical properties of the residues to prevent sticky behavior and clogging in advance, allowing higher water content to be added without compromising operational stability. The specific molar ratio of Ca/Si/Al (1:0.05:0.05) is designed to create a sorbent that inherently resists clogging while maintaining high pollutant removal efficiency.
2Ease of manufacture
If conventional sorbents are used, then manufacturing process is simple, but conversion rate of calcium hydroxide to calcium sulfate is low
Solution Approach 1:
The patent applies composite materials by combining calcium hydroxide with specific compounds of silicon (such as silicates, metasilicates, or silica) and aluminum (such as aluminates or aluminum hydroxide) in defined molar ratios. This composite sorbent material enhances the conversion rate of calcium hydroxide to calcium sulfate during the scrubbing process. The silicon and aluminum compounds act as promoters that facilitate the chemical reaction, improving productivity while maintaining relative manufacturing simplicity through a straightforward mixing and hydration process.
3Productivity
If high water content is added to residues, then pollutant capture improves, but sticky behavior and clogging phenomena occur on duct walls
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the sorbent residues, specifically the molar ratios of calcium, silicon, and aluminum compounds. By optimizing these parameters (Ca/Si/Al ratio of 1:0.05:0.05), the sorbent's physical and chemical properties are altered to prevent sticky behavior even at high water contents. This parameter optimization allows the system to achieve high acid gas capture levels (above 95%) while avoiding clogging and sticky residues on duct walls, as the modified sorbent composition fundamentally changes its interaction with water and its flow characteristics.
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
The sorbent achieves improved flue gas treatment performance by allowing higher water content, reducing reaction temperatures, and preventing clogging, thereby enhancing operational stability and efficiency in CDS processes.
Implementation Method 1
quicklime slaking with specific additives like silicates, aluminates, and aluminosilicates, controlled to maintain residual moisture below 35%
Implementation Method 2
quicklime slaking with specific additives
Implementation Method 3
controlled to maintain residual moisture below 35% and molar ratios of silicon or aluminum to calcium between 0.02 and 0.2, ensuring good flowability and effective water retention
Data Source
AI summary
The present invention is related to a process for manufacturing a sorbent suitable for a use in a circulating dry scrubber device comprising the steps of: providing quicklime and water in an hydrator; slaking said quicklime via a non-wet route in the hydrator; collecting a lime based sorbent at an exit of the hydrator. The process is characterized in that it comprises a further step of adding at least a first additive comprising: a compound comprising silicon, and/or, a compound comprising aluminum, and/or a compound comprising silicon and aluminum before or during said slaking step, at a molar ratio between silicon or aluminum or a combination thereof and the calcium provided to said hydrator equal to or below 0.2 and equal to or above 0.02. In some other aspects, the present invention is related to a sorbent, a premix, and a flue gas treatment process.