It is useful to perform numerical simulation of the process to now the prospects of plasma gasification of chicken manure. Calculation of equilibrium composition allows evaluating the yield limits of valuable gasification products at the set param­eters (oxidant/feedstock ratio, temperature, and pressure) [52]. Deficiencies of the method are the restrictions imposed by assumptions: ideal mixing and unlimited residence time [53]. Nevertheless, the given approach accords satisfactory with the experimental data [39, 54-56].

Calculations of the equilibrium composition were implemented by means of the software Chemical WorkBench (Kinetic Technologies Ltd., http://www. kintech. ru/).

Possibility to supply energy with plasma almost completely removes the kinetic restrictions imposed on the process by low temperatures in autothermal modes. Ac­tually, the plasma mode boundary lines are determined by the oxygen consumption required for oxidation of carbon of the feedstock to CO (so-called carbon boundary) and autothermal limit when additional energy is not required for achievement of the set parameters. For chicken manure, the carbon boundary is ~245g/kg (mode 1, Fig. 12.1) for air and ~63.9g/kg (mode 3) for steam plasma. Autothermal mode (temperature 1,500 K, pressure 1 atm) air gasification is achieved at oxidizer con­sumption ~2.16 kg/kg. Accordingly, all regimes between these two air consumptions are allothermal under equal conditions (temperature and pressure).

Let us examine modes of stoichiometric gasification of chicken manure by air and steam, and also a mode with an air consumption ~ 1.20 kg/kg (mode 2) that is between autothermal and stoichiometric modes, and a mode with the steam consumption ~0.314 kg/kg (mode 4), matching to the previous one by the amount of fed oxygen. Figure 12.1 shows the results of calculations. In calculations, the composition and heating value of a chicken manure specified in Table 12.1 were used and also the following composition of air was used: N2—78.09, O2—20.95, Ar—0.93, CO2—

0. 03 %mol.

Approximation of synthesis rate was used for calculation of space velocity of Fischer-Tropsch process on Co-Mn/TiO2 catalyst [57] at pressure 10 bar and tem­perature 523 K. Before Fischer-Tropsch synthesis, the syngas was cleaned from sulfur compounds and nitrogen oxides, part of CO was converted to H2 by water-gas shift reaction to provide stoichiometric relation of synthesis—H2/CO = 2 according to its chemical equation (12.1).

CO + 2H2 ^ -(CH2) — +H2O (12.1)

The synthesis continued until CO content in convertible gas decreased to 0.1 %mol. The process rate was calculated according to equation (12.2) [57].

rCO = kp x bCO x Pco x Ph2/(1 + bco x Pco) (12.2)

where, rCO is CO conversion rate (mmolCO/min gcat), kP and bCO are kinetic param­eters equal to 0.367 and 1.454, respectively, Pco and Ph2- are partial pressures of CO and H2.