The thermal decomposition and vaporisation of ammonium sulphate, (NH4)2SO4, is shown to take place via two distinct sets of reactions. In the first, ammonium pyrosulphate, (NH4)2S2O7, is the primary condensed phase product: 2(NH4)2SO4 ← (NH4)2S2O7+2NH3+H2O The second stage concerns the decomposition of the pyrosulphate. Ammonia, sulphur dioxide, nitrogen and water are the major products, the dominant reaction being 3(NH4)2S2O7 ← 2NH3+6SO2+2N2+9H2O

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The saturated vapour pressure of K2S04 has been measured by a combination of the Knudsen effusion and transpiration techniques, over the temperature range 1 180-1 668 K. Between 11 80 and 1342 K (the melting point of K2S04), the vapour pressures may be expressed by the equation loglo(l'/atni) = -1.47rt0.09 x 104/TK+6.84f0.69, the mean heat of sublimation being 67.344.0kcalfniol. Between 1342 and 1668 K the vapour pressures follow the equation loglo(P/atm) = -1,2740.09 x 104/TK+5.37f0.69, the mean lieat of cvaporation being 58.3&4.1 kcal/mol. Extrapolation to 1 atm gives a theoretical boiling point of 237O-f 100 K and an entropy of evaporation at the boiling point of 24.6 f2.2 cal/rnol K.

The role of chloride in the corrosion of oil- and coal-fired boilers and gas turbines, by flue gases and their deposits, is discussed, on the basis of both experimental and theoretical studies. It is concluded that in most boilers, the presence of chloride in the fuel will not result in any serious increase in the rate of corrosion of plant components. On the other hand, a number of situations are identified, which can arise in both boilers and gas turbines, in which high chloride levels in the fuel can be associated with enhanced rates of corrosion.

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