Scrubber Temperature Gradient for Sulfur Dioxide and Ammonia Removal
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Solution Overview
Problem
The existing processes for producing ammonium thiosulfate, ammonium bisulfite, or ammonium sulfate fail to effectively capture sulfur dioxide and ammonia from vapor phase combustion gases, leading to their release into the atmosphere due to high temperatures and pH levels that increase the vapor pressure of these gases, resulting in excessive emissions.
Innovation Solution
A process that creates a temperature gradient within the scrubber by circulating chilled media and adjusting the pH of the scrubbing solution to maintain it within an optimal range of 5.3-7.3, specifically 5.7-6.6, to lower the vapor pressure of sulfur dioxide and ammonia, facilitating their solubility and capture in the solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water scrubbing solution is used at process temperature to capture NH3 and SO2, then most of the gases can be captured, but the concentration of sulfites quickly reaches maximum concentration and equilibrium pressure is reached, preventing further capture
Solution Approach 1:
The patent changes the temperature parameter of the scrubbing solution by introducing chilled media, lowering it from process temperature (around 150-180°F) to a lower temperature. This parameter change increases the solubility of NH3 and SO2 gases in the solution, allowing continued capture beyond the equilibrium concentration limit at higher temperatures.
Solution Approach 2:
The patent implements periodic cooling cycles where chilled media is intermittently introduced to maintain the scrubbing solution temperature below the threshold where equilibrium concentration is reached. This periodic temperature reduction allows continuous gas capture capability.
2Temperature
If combustion gases are scrubbed at elevated temperatures (150-180°F), then the process can handle hot gases, but the vapor pressure of NH3 and SO2 increases, preventing complete capture and leading to atmospheric release
Solution Approach 1:
The patent changes the temperature parameter by introducing chilled media to lower the scrubbing solution temperature from the equilibrium temperature range (150-180°F) to a lower temperature. This parameter change reduces the vapor pressure of NH3 and SO2, enabling complete capture and preventing harmful emissions.
Solution Approach 2:
The patent converts the harmful effect of high temperature (increased vapor pressure leading to emissions) into a benefit by using the temperature difference between hot combustion gases and chilled media. The chilled media absorbs excess heat, lowering the temperature to a range where complete gas capture is achieved, thus converting the harmful high temperature into a useful temperature gradient for cooling and capture.
3Quantity of substance
If the concentration of sulfites in the scrubbing solution reaches maximum concentration at equilibrium pressure, then the solution is saturated, but further NH3 and SO2 gases cannot be captured and are released to the atmosphere
Solution Approach 1:
The patent changes the temperature parameter by introducing chilled media, lowering the scrubbing solution temperature to increase gas solubility. This parameter change allows the solution to accommodate higher concentrations of dissolved NH3 and SO2 beyond the equilibrium concentration limit at higher temperatures, preventing atmospheric release.
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 achieves a substantial removal of sulfur dioxide and ammonia from the gas stream, with up to 99.99% capture, reducing harmful emissions and maintaining acceptable ranges across various pH conditions.
Implementation Method 1
at least a stream of chilled media is circulated in a scrubber to create a temperature gradient within the scrubber
Implementation Method 2
The temperature gradient facilitates an increased solubility of ammonia and sulfur dioxide in the process solution by lowering the vapor pressure of these gases
Implementation Method 3
the water scrubbing solution, at process condition temperature, can capture most of the NH3 and SO2 gases from the process
Implementation Method 4
The temperature gradient facilitates an increased solubility of ammonia and sulfur dioxide in the process solution
Implementation Method 5
the vapor pressure of sulfur dioxide and ammonia are lowered such that it is not released in the gaseous phase
Data Source
AI summary
According to an embodiment of the invention, a process for substantially completely removing sulfur dioxide and ammonia from a gas stream is disclosed. The process involves lowering the vapor pressure in a scrubber by contacting the gas stream with one or more streams of re-circulating chilled media. The process further involves adjusting the pH of the process solution in the scrubber to within a predetermined range. The lowering of the vapor pressure and pH adjustment results in an increase in the solubility of sulfur dioxide and ammonia in the process solution thereby facilitating a substantially complete removal of sulfur dioxide and ammonia from the gas stream.