Mercury Reduction System Liquid Phase Chemical Supply
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Solution Overview
Problem
Existing mercury reduction systems face challenges in controlling the ratio of NH3 and HCl when supplied in gaseous states, leading to potential imbalances that affect the reduction of nitrogen oxide and metallic mercury in flue gas, requiring separate gas supply equipment and struggling with controlled generation of NH3 and HCl gases from NH4Cl solutions.
Innovation Solution
A mercury reduction system that mixes NH4Cl, NH3, and HCl solutions in liquid states, allowing for precise control and simultaneous supply of reducing and chlorinating agents in any proportion through a chemical supplying unit with adjusting valves and flowmeters, and injects the mixed solution into the flue gas, utilizing a two-fluid nozzle for efficient spraying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NH3 and HCl are supplied in gaseous states separately, then the reduction of nitrogen oxide and oxidation of mercury can be achieved, but the device complexity increases due to requiring separate gas supply equipment
Solution Approach 1:
The patent combines the supply of NH3 and HCl into a single liquid-phase system. By dissolving both ammonia and hydrogen chloride in water to form a unified chemical solution, the system eliminates the need for separate gas supply equipment while maintaining the chemical reactions needed for NOx reduction and Hg oxidation.
Solution Approach 2:
The patent changes the physical state of the chemical agents from gaseous to liquid phase. By dissolving NH3 and HCl in water, the system transforms the delivery mechanism from gas injection to liquid spray, simplifying the supply equipment while preserving the functional effectiveness of the chemical reactions.
2Ease of operation
If NH4Cl solution is used to generate NH3 and HCl gases, then the supply can be simplified, but the controlling precision of NH3 and HCl generation ratio deteriorates
Solution Approach 1:
The patent segments the chemical solution into separate components: NH3 solution and HCl solution, each dissolved in water independently. This allows separate control of each chemical agent's concentration and flow rate, enabling precise adjustment of the NH3:HCl ratio while maintaining ease of liquid-phase supply.
Solution Approach 2:
The patent introduces dynamic control capabilities through separate flow meters and adjusting valves for NH3 solution and HCl solution. This enables real-time adjustment of the chemical agent ratio according to actual flue gas composition, transforming the static NH4Cl decomposition approach into a dynamically controllable system.
3Productivity
If the chemical solution is sprayed into the flue, then the mixing efficiency improves, but the requirement for spray equipment increases
Solution Approach 1:
The patent makes the spray equipment multi-functional by using it to deliver both NH3 and HCl chemicals simultaneously through a single liquid solution. The spray system serves the dual purpose of chemical delivery and mixing enhancement, eliminating the need for separate injection equipment for each chemical agent.
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 enables precise control and efficient oxidation and reduction of nitrogen oxide and mercury in flue gas, enhancing the performance of mercury reduction and nitrogen oxide denitration while simplifying the device requirements, allowing for flexible agent proportioning based on flue gas composition.
Implementation Method 1
NH3 promotes the reduction reaction of nitrogen oxide NOx in the flue gas as the following formula (1)
Implementation Method 2
HCl promotes the oxidation reaction of Hg as the following formula (2)
Implementation Method 3
When the agents are supplied in a liquid state as NH4Cl solution, NH4Cl is dissociated into NH3 gas and HCl gas
Implementation Method 4
A chemical supplying unit that mixes a reducing agent for reducing nitrogen oxide in the flue gas on a denitration catalyst
Data Source
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AI summary
A mercury reduction system 10A according to the present embodiment is a mercury reduction system that reduces NOx and Hg in flue gas 12 discharged from a boiler 11, and includes a chemical supplying unit 19A that mixes an NH4Cl solution 14, an NH3 solution 15, and an HCl solution 16 in liquid states, and supplies a mixed solution 17 into a flue 18 provided downstream of the boiler 11, a reduction denitration apparatus 20 that includes a denitration catalyst reducing NOx in the flue gas 12 with NH3 and oxidizing Hg in the presence of HCl, and a wet desulfurization apparatus 25 that reduces Hg oxidized in the reduction denitration apparatus 20 with limestone-gypsum slurry 24.