The Use of Carbon Monoxide and Other Gases for Process Control

The application of the analysis of trace gas emissions downstream of the process dust filters in a precalciner kiln as the means of controlling the air-fuel ratio is described. This application eliminated the need for a high-temperature probe in the kiln as the kiln excess-air requirement is determined and controlled based on carbon monoxide, nitrogen oxide, and sulfur dioxide concentrations downstream of the bypass dust filter. Control of the excess air in the precalciner is also based on the carbon monoxide concentration downstream of the preheater dust collector. Control by carbon monoxide has shown considerable advantages over the traditional technique of control based on oxygen analysis. These advantages include: 1) simplification of sampling, 2) increased kiln productivity and efficiency, 3) better operator response to analyzer information, 4) precise combustion control showing promise for reducing nitrogen-oxide emissions, and 5) control of clinker quality.