The term “engineering” represents the use of science and mathematics to solve problems. It is engineers who figure out how inventions work practically. They also find practical applications for scientific inventions and discoveries.  While inventors get rewarded for their discoveries, it is really engineers who make these inventions useful to people.

So what is the relevance of engineering to incinerator making? First of all, an incinerator is not just a hollow construction where one dumps waste and it burns. It is an engineered apparatus, designed to suit particular waste. The results of using an incinerator should be:

•             Proper disposal of waste for which the incinerator is used.

•             Emissions to meet environmental standards.

•             Not creating any other problem in the process of disposing of the designated waste.

What are the factors considered by design engineers to achieve these results? What results are expected from such engineering?

1)            Process Flow Diagram: This is a diagram used in process engineering to identify and indicate the flow of plant process and equipment. It explains the relationship between different equipment of the facility.  The PFD is the first step to decide the process flow and the various equipment and components that are being considered.

2)            Piping and Instrumentation Diagram: The P&ID shows important piping and instruments; control philosophy, safety, startup and operational information. It is important to provide this at the design stage to determine control schemes and to give inputs to HAZOP studies.

3)            Heat and Mass balance: This is a basic process engineering document generated by process design engineers providing for operating conditions, compositions and key physical properties of the process stream. The H&MB may be made independently or a part of the PFD.

After drawing up the above basic engineering documents, the design engineer has to decide further:

a)            Volume of chambers: The volume of the primary combustion chamber and that of the secondary combustion chamber should be calculated carefully so that the waste has enough room to burn in the primary chamber and the flue gas the required dwell time in the secondary chamber. For this purpose the calorific value of the waste, the amount of flue gas generated and the thermal capacity of the incinerator itself will also have to be calculated to arrive at optimum sizing of the chambers.

b)            Thermal capacity: The hourly quantity of waste to be burnt, its calorific value, the thickness of refractory, the heat release rate of the system will all decide the thermal capacity of the incinerator.

c)            Refractory: The thickness of refractory and insulating material, their heat conductivity and thermal profile will have to be carefully considered if the incinerator is to withstand the high heat (in excess of 1000 deg.C) inside the system and insulate the outer body from the heat. It has to be borne in mind that the refractory, being a very critical component of the system, should have optimum conductivity and good strength at high temperatures.

d)            Design of downstream equipment: The MOC, size, location, etc. of whatever downstream equipment that is chosen for the specific application will have to be carefully chosen, considering, the operating conditions, flow and life of the equipment.

These are some information on basic engineering to design a good incinerator system keeping in mind that it has to meet the performance parameters required, is maintenance-free and has a long MTBF and a decent Service Life.