“Efficiency – what is that?” – How to measure the performance of a kiln line?

In the past editions I have written in a rather abstract way about “process optimization” time and time again – and you may be asking yourself: what does that mean in a specific case? The question is justified – but let me also ask: What does “optimal” mean in a specific case? How would one measure “optimal operation”? Classically, parameters such as production output or energy consumption will be mentioned here. However, these performance values are not well suited to describe whether a system really runs optimally, because any installed system could easily benefit if reserves are built into its design. How can you assess the performance of the operating personnel and the kiln line without falsifying the assessment due to hidden reserves? Specific parameters or KPI’s are then used to calculate a target value in relation to cost. A classic example is the specific fuel requirement or the specific amount of exhaust gas, which process engineers particularly like to consider. However, these values are also only suitable to a limited extent because they depend heavily on the fuels used and particularly strongly on the raw material moisture of the specific case. The performance and excellence of the operating personnel, as well as the performance of the plant system, is probably best represented by the oxygen content during operation in the kiln inlet chamber and after the preheater. This parameter describes best how close the kiln system is operated “at its optimum” – or in other words: how much the operation of the system exploits the potential of the system technology. Of course, the oxygen values too cannot be compared 1:1 between different kilns, because plant and fuel specifics can be very different. In any case however, high “required” oxygen values are either a sign of the comfort zone of the kiln operation or a sign of the combustion process not working properly. Often coarse fuel falls from the calciner or the kiln riser duct into the kiln inlet, where it reduces oxygen unnoticed in the material bed and thus signals to the system operator either through build-up or quality problems: “We need more oxygen!” If, on the other hand, the fuel were to be kept in suspension, the kiln would also be able to be operated with a lower oxygen supply and would therefore be considerably more energy efficient.

Best regards
Matthias Mersmann

Related articles:

Issue 2015-10 US 2015/0232382 A1

Process and apparatus for improving the combustion of secondary fuel in a rotary kiln and process for retrofitting a rotary kiln with a burner assembly

(22) 04.10.2013 (43) 20.08.2015 (57) The present invention relates to a process and apparatus for improving the combustion of a secondary fuel supplied in a first stream in a rotary kiln, wherein the...

Issue 2015-11 WO 2015/133161 A1

Cement burning apparatus, and method for denitrating exhaust gas from cement kiln

(22) 08.01.2015 (43) 11.09.2015 (57) [Problem] To efficiently reduce the concentration of NOx in an exhaust gas from a cement kiln while keeping the burned state at a good level regardless of the type...

Issue 2018-4 WO2018025482 (A1)

Method for operating cement kiln

(22) 31.05.2017 (43) 08.02.2018 (57) [Problem] To reduce the concentration of both SOx and NOx in combustion gas discharged from a cement kiln. [Solution] A method for operating a cement kiln 7,...

Issue 2017-12 WO 2017/178254 A1

Process and plant for manufacturing cement in the oxyfuel mode

(22) 31.03.2017 (43) 19.10.2017 (57) Process for operating a cement or lime plant comprising a cement (1, 11) or lime kiln (21, 31) and a calciner (2, 12), wherein heat is generated by combustion of...

Issue 2019-5 US 2019/0071351 A1

Process and plant for manufacturing cement in the oxyfuel mode

(22) 31.03.2017 (43) 07.03.2019 (57) Process for operating a cement or lime plant comprising a cement or lime kiln and a calciner, wherein heat is generated by combustion of a fuel in the kiln and/or...