Study Of An Oil Boiler Transformation For Energy Saving On The Basis Of Flameless Combustion

As the energy situation of international is becoming increasingly tense, how to save energy and make full and effectively use of energy is an important issue which the human being faces. Small oil-fired boiler is widely used because of its convenient operation and maintenance. To enhance the thermal efficiency of boiler will reduce its operating cost. In this paper, a small vertical oil-fired boiler in which furnace heating is uneven and heat exchange is not sufficient, so the exhaust gas temperature is high, as a result, the boiler thermal efficiency is low. Therefor, a transformation scheme was designed to save energy by installing a combustion reactor in the furnace, combined with the air flow arrangement style of Flameless Combustion.The thermal efficiency was obtained before and after transformation by carrying out heat balance tests. The diesel combustion process problem was solved by using Eular-lagrange approach. Gas turbulence, turbulent combustion, gas phase radiation and liquid droplets motion were described by Realizable k -εtwo-equation model, presumed Probability Density Function (PDF) model based on mixture fraction, Dis-crete Ordinate (DO) model and Stochastic Trajectory model respectively. The nu-merical simulation of combustion and heat exchange process in the boiler was per-formed on FLUENT 6.3 software platform. Numerical calculations are agreed well with experimental results. The results show that installation of combustion reactor in the furnace can increase the residence time of hot flue gas in the furnace, and the hot flue gas is recirculated back to dilute the reactants, finally, high temperature and low oxygen environment is formed to promote the ignition of fuel combustion. The com-bustion reaction of diesel occurred in the all reactor space. At the same time, the reac-tor wall can play the role of radiant plate to strengthen the furnace radiation heat transfer by transforming the convection and radiation heat of hot flue gas into solid radiation heat. And this eliminates the hot spotes on the water wall, the export water flow is stable. Eventually, the exhaust gas temperature is reduced significantly and the thermal efficiency of boiler is improved remarkably. This is an effective way for in-dustrial enterprises to save energy.