Study On The Combustion Characteristics Of Biomass And Low Volatile Pulverized Coal Blends

Energy crisis is one of the major world problems.Electricity in China is mainly fire power generation that needs exhaust a large mounts of coal resource.In our country the amount of low volatile coal is large but its ignition property is bad.The low volatile coal is difficult to ignite. Biomass is a kind of renewable energy with high volatile content.Co-firing-mixing low volatile pulverized coal with biomass can use the biomass energy in large-scale and improve the ignition property of low volatile coal.The study of the combustion characteristics of biomass and low volatile coal blends is of great significance.At the same time in the power plant the boiler ignition and low-load stable-combustion need a amount of pulverized coal and fuel oil. Tiny-oil ignition technology is an effective way to solve this problem, the study of the technology to ignite mixture of low volatile coal and biomass also has practical significance.This paper study content mainly be divided into three large aspects/with com stalk, cotton stalks, apple wood three kinds of biomass and a low volatile coal as the study object, including thermogravimetric experiments about the combustion characteristic of biomass and low volatile coal, experimental study on pollutant emission characteristics of biomass and low volatile pulverized coal and numerical simulation of tiny-oil ignition.Through thermogravimetric experiments we get the TG and DTG curves of combustion.It is found that the process of biomass combustion includes moisture evaporation,volatile evolution and combustion,char combustion three stages.the main stage is volatile evolution and combustion stage.The low volatile coal contains a little moisture and its moisture evaporation stage is not obvious.The main weight loss happens in the char combustion stage.The weight loss peak grows with the heating rate increasing,at the same time the combustion curves move to the side of high temperature.The bigger blending ratio is,the lower the the ignition temperature and the better the burnout characteristics is. The pollutant emission characteristics experimental study shows that the low volatile pulverized coal’s emission of NO is larger than the biomass’s.These three biomass can drive down the emission of NO and SO2.With the blending ratio increasing the pulverized coal mixture’emission diminishes gradually and the effect is remarkable.Ignition process of pulverized coal in the burner is simulated by the way of numerical simulation, the ignition process of burner internal had a more profound understanding.Changing biomass blending ratio pulverized coal ignition characteristics had no obvious change in general, but the greater the biomass blending ratio coal mixture is ignited in advance.The lower primary air velocity is,the more early the ignition happens.The low primary air velocity is in favour of ignition.While low the primary air velocity may bring the problem of air deficiency and enlarge the coking property.The smaller the particle size is, the better ignition property is.Small particle size can lead to that the fuel heating area is bigger, precipitation of volatile will be more quickly and the performance of fuel burning is better.But considering the reality that the smaller particle size needs the coal pulverizing system have a high requirements and the energy consumption is high.This paper holds that the ideal size of pulverized coal is around0.12mm (120mesh).