Lafarge Aluminates Boosts Efficiency, Cuts Downtime With Servomex Gas Analysis System
The Servomex Gas Analysis System monitors combustion on one of the two furnaces at Lafarge. The furnace, used for the more complex manufacturing process, is loaded with raw material, a mixture of bauxite, limestone and various chemical additives, which is progressively melted by two burners at high temperature. When the reaction is complete, the material is poured and cast as ingots, a few hundred tones being produced from each oven every day.
The Problems:
Yves Bergeron, Development Engineer at Fos-sur-Mer, points out that although the plant itself is quite old, the site was largely rebuilt during the eighties and early nineties. The company decided to install new process control systems as part of the upgrade, including a gas analysis system to monitor combustion. "We decided that we needed some outside expertise", said Yves Bergeron. "We called in Servomex, who then showed that they were good at solving gas analysis problems as well as knowing all about gas analyzers".
The Analyzers:
The hostile environment of the cement works created some initial problems, since the probe of the gas analysis system has to be located close to the burners within the furnace. This tends to cause blockage of the probe. Servomex studied these problems and the overall requirement in detail. They came up with a solution, installing three Servomex gas analyzers in the original system house, remote from the furnace, and linked to the main process control computer. Servomex has immense experience of gas analysis in combustion control and has a range of specially adapted probes to suit virtually all circumstances. The team was therefore able to provide a probe that overcame the blockage problem.
The installation now consists of a Servomex 1100 oxygen analyzer, a Servomex Xendos 2500, measuring concentrations of nitric oxide and a Xendos 2510 measuring carbon monoxide. Additionally, there is a Servomex sample conditioning system that cleans and dries the gas sample before it is presented to the analyzers. Data from the three analyzers enables the process control computer to optimize the use of fuel at the burners, thereby minimizing fuel costs and also ensuring that the reaction in the furnace takes place exactly to specification, thereby maintaining the quality of the product.
The Servomex 1100 is an oxygen analyzer designed for the analysis of gas streams in processes where accuracy, repeatability and stability are critical. The analyzer comes in two parts, the transducer unit containing the measuring cell, and the control unit, which houses the electronics and can be sited well away from unfavorable conditions. The two units can be separated by up to 500 meters is required, although the transducer and control unit at Lafarge are close-coupled in the analyzer house.
The Xendos 2500 and 2510 are infrared process analyzers. The 2500 is designed for continuous monitoring of a single component of group in a gas or liquid sample stream and is certified for use in hazardous areas. The 2510 is a single-beam gas filter correlation infrared analyzer suitable for measuring a single infrared absorbing component in a sample gas stream. Both are designed for dirty industrial environments and are of extremely rugged construction, yet is a precision instrument delivering a high standard of accuracy and repeatability.
Second System:
The Servomex Gas Analysis System has enabled Lafarge to achieve precise control of the combustion process and significant fuel savings on the furnace. The system as it has been developed is so reliable that it is running some 95% of the time with virtually no downtime, and makes a major contribution to the cost-effectiveness of the process.
Asked if Lafarge Aluminates will install a second similar system on the other furnace, Yves Bergeron emphasized that the company always seeks several quotations from alternative suppliers. "However, we are keen to have another similar Servomex System on the second furnace because we do not want to have to go through the development process again", he said. "Without the technical support of Robert Thiebaud and the Servomex team we would never have achieved the process control we have now".
Servomex is a member of Fairey Group plc, a process technology company specializing in electronic controls, process instrumentation and filtration systems.