Mercury Capture in Cement Plants via Feed Meal Volatilization
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Solution Overview
Problem
Current methods for controlling mercury emissions from cement plants are costly and inefficient, as they rely on secondary capture systems, high capital costs, and unpredictable mercury forms, with existing technologies failing to effectively address the recirculating pattern of mercury pollutants in cement manufacturing processes.
Innovation Solution
A method involving heating the raw feed meal to volatilize mercury pollutants, separating the volatilized pollutants in a distinct gas flow, condensing them, and adsorbing them onto carbon particles, which are then filtered out, using a non-contact heat exchanger and fabric filter, with optional treatment of carbon particles and lime to enhance capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If secondary capture systems are used to control mercury emissions, then mercury capture is achieved, but capital cost and operating cost increase substantially
Solution Approach 1:
The patent extracts mercury from the main exhaust gas stream by directing a portion of the gas through a separate treatment path. The feed meal is heated to volatilize mercury, which is then captured in a dedicated fabric filter, separating the mercury control function from the main exhaust treatment system.
Solution Approach 2:
The patent applies preliminary action by heating the feed meal before it enters the kiln to volatilize mercury in advance. This pre-treatment converts mercury from solid/liquid form to vapor, making it easier to capture downstream in the fabric filter rather than dealing with it in its original form.
2Object-affected harmful factors
If carbon injection is used to adsorb mercury, then mercury capture is improved, but the volume of contaminated waste increases and disposal costs rise
Solution Approach 1:
The patent uses fabric filter media that can be disposed of after capturing mercury, replacing the need for expensive carbon injection systems. The fabric filter becomes contaminated with mercury and is replaced periodically, providing a simpler, more economical waste management approach.
3Object-affected harmful factors
If wet scrubbers are used to remove mercury, then mercury capture is achieved, but the gypsum product becomes unusable and wastewater treatment is required
Solution Approach 1:
The patent converts the harmful effect of heating feed meal (which could generate unwanted emissions) into a benefit by using the same heating process to volatilize mercury for capture. The fabric filter then captures the volatilized mercury, turning a potential pollution source into a controlled capture opportunity.
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 reduces mercury emissions by isolating and capturing mercury pollutants efficiently, reducing the volume of contaminated waste and operational costs, while being adaptable to existing cement plant infrastructure, thus addressing the economic and environmental challenges of mercury pollution.
Implementation Method 1
heating the raw feed meal to volatilize mercury pollutants
Implementation Method 2
cooling the gas flow to condense the mercury pollutants
Implementation Method 3
adsorbing them onto carbon particles
Data Source
AI summary
A method and apparatus for reducing discharges into the atmosphere of mercury pollutants associated with dry process, precalciner cement manufacturing is shown. Raw feed meal used in cement production is heated in a special heating chamber to drive off volatile mercury pollutants, such as elemental mercury and mercury oxides. Preferably, the feed meal is heated to a temperature of at least 175° C. The gases that are driven off flow are then cooled to condense the mercury pollutants causing them to be adsorbed on carbon particles injected into the gas flow. The carbon particles containing the condensed mercury pollutants are then filtered out of gas flow, for example, using a fabric filter. The gas flow may be burned to destroy other volatile pollutants such as hydrocarbons and/or ammonia.