Optimization of safe introduction of the mixture air + fuel into an industrial boiler, complying with the SIL2 safety level

Industrial boilers are mainly used in the industries of energy and oil&gas, concretely in refineries and thermal or solar power stations, in order to boil water and use the resultant steam to make the turbines rotate so that electricity is produced. This process of boiling water involves a combustion that has to be both safe and efficient. This means that a control of the mixture air-fuel has to be carried out: the less amount of gas per unit of amount of air, the less efficient the combustion is; but an excess of fuel in the mixture can produce an uncontrolled burst that could cause an accident. Traditionally, when developing the control system of a boiler, the actions of modulating itself would be developed with analog equipments (continuous). The start and stop sentences, as well as interlocks, are digital (all/nothing) that might imply digital equipments. Nowadays, due to advances in microprocessor-based systems, it is possible to achieve safety function with analog equipments that permit to evaluate different setting points in a unique device as well as provide a continuous measure of the variables in the whole operating range.Ingeniería Electrónica Industrial y Automátic