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Procedure for a regenerative heat recovery and preheating of combustion air

Special burner for high-temperature-aluminium-melting-furnaces

 

The challenge in terms of sustainability:

The development of a gas burner designed specifically for this application was desired. The aim was to increase energy efficiency, to increase the service intervals and reduce emissions.

The initial situation:

Technology available on the market was used up to the development of this new concept. The burners used are state of the art, however they are not designed for the use in a specific environment/application, resulting in compromises in terms of efficiency, maintenance intervals, .....

 

The solution:

The design of a combustion / burner system is significantly affected by the required duties. These include the power required, the applicable emission limits, the fuel to be used and the required furnace temperature.

The method and system concept was developed in cooperation with the BFI. In this case, the flow simulation software CFT was used. The operational testing and adoption took place at Aluminium Norf GmbH. There, all required set points for the use of the VAREGA-system were determined.

The sustainable strengths:

One significant advantage of this combustion system is the fact, that it is not necessary to operate it in pairs as it is the case with conventional systems. The result is a significant advantage in controlling the heat input, because it can be adjusted using a PLC system, and operated at an optimized operating point. In principle, regenerative combustion systems offer the highest efficiency of all conventional combustion systems (fuel savings compared with a recuperative system up to about  25%). Normally, such systems are fitted with a regenerator bed using ceramic balls as a heat storage medium. Disadvantage of these ceramic balls are: high maintenance requirements, since the spaces can quickly get clogged by dust-containing exhaust gases. Thus, an exchange of the heat storage medium is needed several times a year. Our heat storage system consists of honeycomb modules. Under normal furnace operation, the top layer must be changed once a year. In addition, the use of honeycomb modules leads to lower pressure losses within the system, resulting in constant conditions over the complete maintenance cycle. At the same time, this stabilizes the process and reduces the energy consumption of the blowers significantly. To reduce the emissions combustion close to the stoicometric point is important. This system offers cycle times which are up to three times longer compared to alternative combustion systems. Resulting again in a more stable operation and less stress on the instrumentation.

 

Brief profile of the company:

Name: Gautschi Engineering GmbH
Company headquarter: Tägerwilen                                                                                           
Year established: 1922
Employees: 50
Solutions: Leading provider of equipment and facilities for the production and heat treatment of primary and secondary aluminium
Internationality: Switzerland, Germany and China