The unit operation model simulates incineration of wastewater sludges, hazardous wastes (liquid or solid), and municipal solid wastes. The primary objective of the model is to calculate the composition of the flue gas stream and estimate the flowrate of auxiliary fuel if needed.
The user specifies the elemental composition of all chemical components that are present in the feed streams (waste feed, fuel feed, and air inlet streams). The elemental composition in mass % includes the following elements/components: (i) Carbon, (ii) Hydrogen, (iii) Moisture, (iv) Oxygen, (v) Nitrogen, (vi) Chlorine, (vii) Fluorine, (viii) Bromine, (ix) Iodine, (x) Sulfur, (xi) Phosphorus, and (xii) Ash. The user must also identify the following components (that may be present in the flue gas stream): carbon dioxide, water, nitrogen, oxygen, hydrogen chloride, hydrogen fluoride, bromine, iodine, sulfur dioxide, phosphorous pentoxide, and ash. The following assumptions are made in the material balance calculations:
1. All carbon in the feed streams will be converted to carbon dioxide.
2. All hydrogen will be oxidized to water and if chlorine and/or fluorine are present, then, stoichiometric amounts of hydrogen will be used to convert the halogens into hydro-halogens.
3. All nitrogen contained in combustible components will be released as gaseous N2.
4. All bromine or iodine present will be released as gaseous Br2, I2.
5. All sulfur will be converted to sulfur dioxide.
6. All phosphorous will be converted to phosphorous pentoxide (P2O5) and
7. All ash will be released as ash.
The model first checks whether the waste feed stream can be burned autothermally at the specified excess oxygen % and flue gas temperature. If yes and the ‘Adjust Fuel Flow...’ button is checked, then, the fuel flowrate is set to zero. If no and the ‘Adjust Fuel Flow...’ button is checked, the required fuel flow is calculated and the fuel stream flowrate is adjusted accordingly. If the ‘Adjust Fuel Flow...’ button is not checked, then, the model checks whether the combined waste feed and fixed fuel feed streams can be burned autothermally. If no, a warning is displayed and material balance calculations are skipped.
In the energy balance calculations, the flue gas temperature that is specified by the user is assumed to be the temperature of the gas stream at the exit of the energy recovery unit. In other words, the model assumes some energy recovery by default.
The flowrate of the air (oxygen) inlet stream is always adjusted by the model based on the ‘Excess Oxygen %’ specified by the user. The user must make sure that the composition of the oxygen supply stream is correctly specified.
The capital cost estimation data are based on multiple-hearth incinerators used for burning wastewater sludge (EPA, 1979). If you need to model and cost incinerators of different designs (e.g., fluidized bed, rotary kiln, etc.), you may want to specify your own capital cost data (see Purchase Cost).
1. Theodore L. and J. Reynolds (1987), “Introduction to Hazardous Waste Incineration”, John Wiley & Sons.
2. Tchobanoglous G. and F.L. Burton (1991). “Wastewater Engineering: Treatment, Disposal, and Reuse”, 3rd edition, Metcalf & Eddy, Inc., McGraw-Hill, Sec. 12-15.
3. EPA 625/1-79-011 (1979). “Process Design Manual for Sludge Treatment and Disposal”, Chapter 9.
The interface of this operation has the following tabs:
● Oper. Cond’s, see Incineration: Oper. Conds Tab
● Elem. Comp, see Incineration: Elemental Composition Tab
● Components, see Incineration: Components Tab
● Labor, etc, see Operations Dialog: Labor etc. Tab
● Description, see Operations Dialog: Description Tab
● Batch Sheet, see Operations Dialog: Batch Sheet Tab
● Scheduling, see Operations Dialog: Scheduling Tab