Analysis of the Heat Requirement for Sewage Sludge Incineration

The process design and evaluation of sludge incinerator performance is generally conducted using either generalized average parameters or, alternatively, complex and detailed calculations which require computer programming for their use. In the first instance the generalized parameters are found to be applicable only to an “average” incinerator which is not encountered in actual practice. In the second instance, the calculations are so numerous that a clear and general picture of what is occurring cannot be readily obtained. This paper presents a new analytical approach to incineration performance evaluation which has been developed in an attempt to redress this situation. A three-term linear equation is developed for the combustion heat balance using net heat value of the fuels. Net heat value is defined as that heat value, per pound of fuel, which is available to perform useful thermal work other than the discharge of its own combustion products. The well-established procedure of using ultimate chemical analyses of fuels together with an element by element accounting for combustion components has been simplified by defining three combustion ratios for a given fuel. These ratios are then used to determine the net available heat values for use in the heat balance equation. Operating data are used to illustrate the application of the analysis technique and to demonstrate the practical application of the procedure.