Improvements in the performance of a medium-pressure-boiler through the adjustment of inlet fuels in a refinery plant

Abstract

Hydrogen has been considered as a promising alternative for fossil fuel in recent years because it is very “clean”. Fossil fuel generates CO 2, CO, SO x , unburned hydrocarbon and particles during combustion, while hydrogen only yields NO x . In this study, a medium-pressure boiler with 130 ton/h boiler loading in a full-scale plant was studied with two inlet hydrogen-rich refinery gas (RG)/fuel oil (FO) volumetric flow rate ratios (inlet RG/FO ratio) and two residual O 2 concentration (vol.%) in flue gases (2%, 4%) to evaluate their influence on the emissions of NO x and CO 2, flue gas temperatures and boiler efficiencies. The result shows significant improvements in both boiler efficiencies and emissions of air pollutants. By increasing the inlet RG/FO ratio from 1:5 to 1:1.5, the fuel cost was reduced by 11%, NO x emission down by 12%, and the CO 2 emission 20,200 ton lower per year was achieved. Thus, better economic operating conditions for the boiler are suggested at inlet RG/FO ratio = 1:1.5 with the residual O 2 concentration in flue gases = 2%.