On decomposition of difference schemes for numerical solution of differential algebraic equations

We consider quasi-linear systems of ordinary differential equations (ODE) with identically singular matrix multiplying the derivative of the desired vector-function and difference scheme for their numerical solution. We discuss conditions that make it possible to solve algebraic (finite-dimensional) equations at each step of numerical process and substitute the solutions obtained into the dynamics equations. Results of numerical solution of ODE systems modeling direct-flow boiler unit are given.