On the Optimalizing Control of Boiler Efficiency by a Heat Loss Method

Abstract

This paper presents the experimental results and the theoretical analysis of the optimalizing control of boiler efficiency, which is attained by the minimization of the total heat loss consisting of a sensible heat loss of exhaust gas and a heat loss due to CO. The experiment is carried out using a gas-fired boiler. The control method and the experimental apparatus are explained in brief. The experiment shows the optimalizing control is satisfactroy. On the basis of the above results, a mathematical model of the controlled system is constructed, where the input is the excess air ratio and the output the total heat loss. The analysis of the optimalizing control system is performed on the steady-state deviation from the optimum and the stability near the value, taking account of dynamic lags and unsymmetrical characteristics of the system. The contributions of each parameter of the system to these problems are clarified. Moreover, the effect of noise on the steady-state deviation is analysed by use of the probability density function obtained from the Fokker-Planck equation. The theoretical values are found to be in good agreement with the results obtained from the simulation on a digital computer.