The "Comburimetre" and its Use in Combustion Control

In any gas-fired industrial installation, improvement of production quality and overall efficiency requires adequate combustion control. Any combustion pequires a well defined combustion agent/fuel feed patio. Control of this patio is generally done through analysis of the combustion products. If the combustion products are polluted or not accessible it is necessary to know the fuel characteristics in order to maintain unchanged, by upstream action, the ideal conditions for combustion when those characteristics vary. The fact that a specific sensor is not commercially available has led Gaz de France to develop a meter called "COMBURIMETRE" in cooperation with a manufacturer. The "COMBURIMETRE" is a combustion simulator which enables the continuous measurement of an important characteristic of distributed natural gas : the combustion air requirement index (B) which is defined as B = Va/Id where "Va" is theoretical air requirement (unit m3(n)of aip/m3(n)of gas) and : "d" relative density with respect to air. Marketed as of three years ago, the "COMBURIMETRE" has proven its reliability, accuracy and speed of response, and therefore its capacity to control combustion in the most sensitive industrial processes. Furthermore, the tight analogy which exists between the combustion air requirement index (B=Va/Ia) and the r-lobbe number (W = gcv/.f(1) of natural gases allows using the "COMBURIMETRE" to regulate a constant thermal input under the same conditions. This paper consists of two parts : after presenting the characteristics of the unit, we shall emphasize the various regulation schemes using the "COMBURIMETRE", and give some application examples.