Study On Ignite Low-Volatile Coal And Biomass By Tiny-oil Ignition Technology

Oil is very indigent in our country, lots of oil needs import. Ignition and stable combustion in burning coal units need lots of oil. So the tiny-oil ignition technology is researched to lower the fuel oil consumption in generate electricity. In our country power plant boiler fueled with low-volatile coal (LVC) accounts for a sizeable proportion, about5.0%to5.5%. Because of low content of volatile and ignition temperature high, tiny-oil ignition technology practical applications in low-volatile coal suffer commonly from low combustion efficiency, difficult to ignite and so on, which limited range of applications of tiny-oil ignition technology. As a clean and renewable energy, there are a lot of biomass resources in our country. The volatile content of biomass can reach60%to70%. Co-firing of biomass and coal is an effective way. which can improve the application of tiny-oil ignition technology to ignite the low-volatile coal (LVC), which expanded range of applications of tiny-oil ignition technology and can realize scale use biomass energy in the active power station boiler. Ignite low-volatile coal and biomass by tiny-oil ignition technology provided a feasible method to save coal, oil and other non-renewable energy and reduce CO2emissions, so this technology has important significance to the research. In the same spray nozzle flow under pressure with the export of diameter increases pressure increase fuel droplet spray nozzle center to tend to move.The core part of oil burner is the tiny-oil atomizer, and the atomization performance decided the tiny-oil gun flame temperature, stiffness and stability, therefore, in this paper using the numerical simulation to study the flowing and the spray characteristics of the nozzle. On the basis of theoretical analysis the structure characteristic physical and mathematical model of the pressure-oil atomizing nozzle are established. And then describes the traces of the fuel flow inside the nozzle, analyzes pressure and speed distribution in the process of spray. At last the structure parameters of nozzle and fuel atomization pressure on the impact of the fuel flow and atomization characteristics have been analyzed. The results show that:number of swirl groove has a great influence for the film thickness of the nozzle exit and the distribution of droplet diameter, the swirl groove number the greater the mist smaller droplet diameter distribution is more uniform.And then numerical simulation method is employed in this thesis to investigate the process of ignite low-volatile coal and biomass by tiny-oil ignition technology. Analyzed the temperature field, velocity field in the burner, after fuel combination which mixing up Yangquan anthracite with wheat straw, corn straw and peanut shells respectively in different mixing ratio were lit by tiny-oil ignition technology. And several important factors which influence the ignition of pulverized biomass and anthracite are analyze such as pulverized biomass and anthracite fineness, the inlet velocity of primary air flow. The results show that: co-firing biomass with anthracite can improve fuel volatile content and lower the ignition point of fuel combination, and effective improved the combustion process of low-volatile coal in the tiny-oil burner. The kinds of biomass which co-firing with anthracite has a larger impact on the temperature distribution in the burner, under the same mixing ratio when mixing with peanut shells the temperature lower about300℃than with straw and com straw. Co-firing biomass with anthracite flame temperature in the burner decrease with the increase of mixing ratio, for the Yangquan anthracite researched in this paper, when com straw mixing ratio is40%the flame temperature at the exit of burner lower about220℃than mixing ratio is10%. The inlet velocities of primary air flow and pulverized biomass and anthracite fineness also has a larger impact on the combustion of mixed fuel. The smaller the particle size the temperature in burner slightly lower at stage of ignition, but due to the rapid combustion of the fine particles and intense reaction at the stage of combustion stability, temperature rising faster which is propitious to fast and complete combustion. With the improvement of the primary air velocity, the ignition distance was increased and the combustion stability becomes worse, but the smaller primary air velocity the likelihood of coking in burner the greater. Comprehensive consideration of various factors, in this study while pulverized biomass and anthracite fineness is0.06mm to0.08mm, and the inlet velocities of primary air flow is20m/s to23m/s, mixing combustion effect is better.