| The increasing use of fossil fuels and the declining quality of the environment have prompted the search for new and renewable energy sources.Because of the abundant resources,wide distribution,low price and high sustainability of biomass,people pay more and more attention to biomass energy.Biomass energy has the potential to replace existing fossil fuels due to its advantages of storage,renewable and environmental protection.The gasification,liquefaction,pyrolysis or combustion of biomass energy hinder the development of the biomass energy industry because of its loose structure,low density,high moisture content and irregular shape,all of which lead to the increase of the cost of biological transportation and storage.Biomass dense molding technology can extrude biomass into pellets,rods and cylinders,thereby improving molding density and reducing storage,transportation and handling costs.After extrusion molding of biomass energy,biomass products have a uniform shape and size,which meet the standards of transportation and storage.The forming particles can be directly burned,co-burned with coal,pyrolysis and other thermochemical conversion methods.In order to improve the energy consumption,density,water absorption,combustion and other characteristics of the formed particles were studied and analyzed.At present,torrefaction and pyrolysis technology is an effective method to improve biomass pellet forming.Biomass is usually roasted and pyrolyzed in a nitrogen atmosphere to improve the performance of biomass.In order to solve the large amount of municipal sewage sludge,incineration is by far one of the most effective treatment methods.In this experiment,the amount of sludge and the quality of molding particles were improved,so the method of preparing molding fuel by mixing semi-dried sludge(moisture content 50%)and biomass obtained from torrefaction and pyrolysis of camellia shell was proposed.In this paper,the effect of different molding conditions on the quality of biomass particles formed by semi-drying sludge and torrefaction pyrolysis was studied,and the emission of particles after combustion was analyzed.Mainly from the molding pressure(3-5k N),molding temperature(70-110℃),raw material pretreatment(baking,pyrolysis),sludge proportion(10%-80%)and other aspects of the molding particles were studied,and its mechanism was analyzed.In this paper,the extrusion energy consumption,pushing energy consumption,density,water absorption,combustion and particulate emissions were analyzed,and the effects of torrefaction and pyrolysis on mixed particles were investigated.The influences of various influencing factors on the energy consumption and particle properties of molding were determined,and the optimum process conditions for the mixed molding of sludge and biomass derived from torrefaction and pyrolysis of camellia oil shell were determined,which provided a basis for the possibility of replacing fossil fuels with sludge mixed molding fuel.This research is mainly carried out from the following aspects:1)The camellia shell is washed and put into the oven to dry,and the camellia shell is crushed by a grinder to obtain powder.The resulting camellia shell powder is screened out by a screening machine to 40-120 mesh camellia shells;Take 200 g of the obtained camellia shell and bake it in a tube furnace at different temperatures(270℃,300℃)to get the baked camellia shell.200 g of camellia shell was pyrolyzed in a tube furnace at different temperatures(500℃,600℃,700℃)to obtain biochar.The heating value,water absorption and combustibility of camellia shell can be improved by torrefaction and pyrolysis technology.Take 1kg of dehydrated sludge into the oven at 40℃ to dry completely dry sludge,said its quality,40℃ oven can preserve the activity of microorganisms in sludge;Take the same quality of ultrapure water and completely dried sludge for stirring,the moisture content of 50% of the sludge,called semi-dried sludge.2)The calorific values of various biomass(Camellia oleifera shells,torrified Camellia oleifera shells,Camellia oleifera shells biochar)and sludge were measured,and the biomass was mixed with semi-desiccated sludge at the first-level standard calorific value of national shaped fuel of 16.9J/g.The density of forming particles can be enhanced by mixing with sludge,and the energy consumption in the formation process reduces with the increase of the amount of sludge.In the experiment of measuring the water absorption of particles,the content of sludge in the formed particles is enormous,and the water absorption of particles is minor,so as to decrease the cost of particles in the process of production,transportation and storage.In particle combustion experiments,the higher the sludge content in the process of forming fuel particles,the lower the relative particulate matter.Among them,PM1 has the most significant emission reduction effect,with an emission reduction rate of59.78%.Accordingly,the experimental results demonstrate that the semi-dried sludge can be blended with biomass shaped,which can resolve the problem of insufficient supply of biomass raw materials and biomass shaped fuel. |
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