Methane problem formulation

The constant-pressure formulation results in a high-index problem even with implementation of instead of A as the dependent variable. This results from the absence of any time derivatives for u. Attempts to solve the methane-ignition problem with the constant-pressure formulation were generally unsuccessful, except by significantly relaxing the error control on A and u. Even then, while the solutions appear generally correct, they exhibit unstable behavior near fast transients, particularly on A. 

Other Commercial Catalyst Formulations. Many papers and patents have recently appeared which are also addressed to the problem of maintaining mechanical strength as well as activity and chemical stability during steam reforming and methanation. Hence, only selected examples will be given in the following paragraphs. 

The steady-state permeation model of in situ coal gasification is presented in an expanded formulation which includes the following reactions combustion, water-gas, water-gas shift, Boudouard, methanation and devolatilization. The model predicts that substantial quantities of unconsumed char will be left in the wake of the burn front under certain conditions, and this result is in qualitative agreement with postburn studies of the Hanna UCG tests. The problems encountered in the numerical solution of the system equations are discussed. 

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