Cement Feed Meal Volatilization and Combustion Control
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Solution Overview
Problem
Cement manufacturing facilities face challenges in controlling atmospheric emissions, particularly from the drying chambers, where hydrocarbons and ammonia compounds are released, leading to hazardous pollutants like dioxins and furans, which are difficult to manage with existing control technologies.
Innovation Solution
A method and apparatus that involves heating the feed meal in a separate chamber using hot exhaust gases to drive off volatile compounds, which are then directed into a combustion region, such as the precalciner, where they undergo combustion-induced reactions to reduce harmful emissions, and using a base-base exchange reaction with calcium oxide to convert ammonium species into less harmful compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feed meal is heated in drying chambers to remove moisture, then drying efficiency is improved, but volatile harmful compounds are released into the atmosphere
Solution Approach 1:
The patent extracts volatile harmful compounds from the drying process by directing them through a duct system into a separate combustion chamber, isolating the harmful byproducts from the main drying operation and enabling their separate treatment.
Solution Approach 2:
The patent converts harmful volatile compounds into beneficial combustion energy by directing them into a combustion chamber where they burn, producing heat that can be reused in the drying process and eliminating the harmful emissions.
2Object-affected harmful factors
If existing control technologies are used to manage dioxins and furans, then some pollution control is achieved, but effectiveness is insufficient due to the difficulty of managing these hazardous pollutants
Solution Approach 1:
The patent applies preliminary action by combusting volatile harmful compounds immediately upon release from the drying chamber, preventing their transformation into more hazardous substances like dioxins and furans before they can form.
Solution Approach 2:
The patent uses combustion (a form of accelerated oxidation) to completely oxidize volatile harmful compounds in the combustion chamber, converting them into less harmful substances and preventing the formation of dioxins and furans.
3Quantity of substance
If ammonia-bearing species are released from feed meal, then nitrogen content is reduced, but ammonia combines with acid vapors to form aerosols that reduce visibility
Solution Approach 1:
The patent extracts ammonia-bearing species from the drying process by directing them into the combustion chamber, separating them from the main process stream where they would otherwise combine with acid vapors to form harmful aerosols.
Solution Approach 2:
The patent uses combustion to oxidize ammonia-bearing species, converting them into nitrogen gas and water vapor, thereby preventing their reaction with acid vapors to form visibility-reducing aerosols.
4Productivity
If volatile compounds are driven off from feed meal during heating, then moisture and organic compounds are removed, but these volatile materials create pollution if released directly
Solution Approach 1:
The patent merges the volatilization process with a combustion process by directing volatile compounds from the heating chamber into a combustion chamber, combining two functions (volatilization and destruction of harmful compounds) into an integrated system.
Solution Approach 2:
The patent converts harmful volatile emissions into beneficial combustion energy, where the volatile compounds serve as fuel in the combustion chamber, producing heat that can be reused in the drying process while eliminating pollution.
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 reduces the release of harmful pollutants into the atmosphere by oxidizing organic compounds and converting ammonia-bearing species, thereby improving air quality and compliance with regulatory standards.
Implementation Method 1
heating the feed meal in a separate chamber using hot exhaust gases to drive off volatile compounds
Implementation Method 2
directed into a combustion region, such as the precalciner, where they undergo combustion-induced reactions to reduce harmful emissions
Implementation Method 3
oxidizing organic compounds
Implementation Method 4
using a base-base exchange reaction with calcium oxide to convert ammonium species into less harmful compounds
Data Source
AI summary
A method and apparatus for reducing air 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 compounds, such as organic materials and salts of ammonia. Preferably, the feed meal is heated to a temperature of at least 350° F. The gases that are driven off flow to the precalciner where they are combusted and rendered harmless. Heat is provided by diverting at least a portion of the exhaust gases from the cement pyroprocessing kiln to the special heater. The raw feed meal is indirectly heated using a heat exchange wall between the feed meal and the kiln exhaust gas flow. In addition, a base-containing material such as lime or precalcined feed meal, may be added to the raw feed before treatment meal to promote the breakdown of inorganic ammonium compounds, thereby releasing gaseous ammonia which is also destroyed upon subsequent combustion. Hot precalcined meal may also be used to provide some of the heat required to heat the raw feed meal in the special heating chamber.