In this paper,the temperature rise characteristics of Huadian oil shale,its semi-coke and mixture were examined in the microwave field.The results showed that oil shale was a poor microwave absorbing material and can ...In this paper,the temperature rise characteristics of Huadian oil shale,its semi-coke and mixture were examined in the microwave field.The results showed that oil shale was a poor microwave absorbing material and can not be pyrolyzed while semi-coke produced can be used as microwave absorbent due to its high heat-up rate in the microwave field.The mixture of oil shale and semi-coke can be pyrolyzed by microwave radiation.The pyrolysis in the microwave field was performed and the effect of mixed ratio,microwave power and particle size were discussed.It was found that the more the semi-coke added,the more the oil yield produced.The higher the microwave power,the more the oil yield and gas loss,while the less the semi-coke yield in the same time.The influence of particle size was small on the pyrolysis except the particle size <0.2 mm due to its serious entrainment in the experiment.展开更多
The semi-coke was prepared by solid heat carrier with dry distillation in single factor method. The pore structures of raw coal and semi-coke were characterized by Brunauer-Emmett-Teller (BET) and scanning electron mi...The semi-coke was prepared by solid heat carrier with dry distillation in single factor method. The pore structures of raw coal and semi-coke were characterized by Brunauer-Emmett-Teller (BET) and scanning electron microscope (SEM). The results show that the adsorption and desorption isotherm of semi-coke are not coincident. There was a wide pore distribution on the semi-coke, in which mesopores and micropores account for a considerable proportion. Also there are many more secondary pores. With the increase of the final temperature of heat carrier and constant temperature, as well as the decrease of volume ratio of coal and hot carrier reactor, specific surface area and pore volume of semi-coke increased rapidly first and then decreased and finally increased, along with the rapidly reduction of average pore size. SEM photos show that the surface of semi-coke becomes increasingly rough and glossy.展开更多
In a test rig,pulverized semi-coke was preheated to 850℃in a circulating fluidized bed(CFB)and then cornbusted at 1100℃in a down-fired combustor(DFC).Experiments were conducted to reveal the effects of three seconda...In a test rig,pulverized semi-coke was preheated to 850℃in a circulating fluidized bed(CFB)and then cornbusted at 1100℃in a down-fired combustor(DFC).Experiments were conducted to reveal the effects of three secondary air nozzle cases(co-axial jet,top circular jet and wall circular jet)on the NO emission.The results show that the optimized secondary air nozzle can reduce NO emission.O_2 concentration profile is the major factor affecting NO generation and emission,which is led by the secondary air nozzle.The lower O_2 concentration led to the generation of lower initial NO.The NO emission at the exit of the DFC was reduced from 189 to 92mg/m^3(@6%O_2)with the decrease of initial generation.The peak of NO at 100 mm below the nozzle should be attributed to the oxidization of NH_3 in the syngas,rather than the oxidization of fuel-N in the char.The low and well-distributed O_2 concentration contributes to the reduction of initial NO,which helps to reduce the NO emission.The combustion effieiencies of the eases of the co-axial jet,the top circular jet,and the wall circular jet are97.88%,98.94%and 98.74%,respectively.展开更多
文摘In this paper,the temperature rise characteristics of Huadian oil shale,its semi-coke and mixture were examined in the microwave field.The results showed that oil shale was a poor microwave absorbing material and can not be pyrolyzed while semi-coke produced can be used as microwave absorbent due to its high heat-up rate in the microwave field.The mixture of oil shale and semi-coke can be pyrolyzed by microwave radiation.The pyrolysis in the microwave field was performed and the effect of mixed ratio,microwave power and particle size were discussed.It was found that the more the semi-coke added,the more the oil yield produced.The higher the microwave power,the more the oil yield and gas loss,while the less the semi-coke yield in the same time.The influence of particle size was small on the pyrolysis except the particle size <0.2 mm due to its serious entrainment in the experiment.
基金financial support from the Major State Basic Research Development Program of China (No. 2012CB214902)the National Natural Science Foundation of China (No. 51104159) are greatly appreciated
文摘The semi-coke was prepared by solid heat carrier with dry distillation in single factor method. The pore structures of raw coal and semi-coke were characterized by Brunauer-Emmett-Teller (BET) and scanning electron microscope (SEM). The results show that the adsorption and desorption isotherm of semi-coke are not coincident. There was a wide pore distribution on the semi-coke, in which mesopores and micropores account for a considerable proportion. Also there are many more secondary pores. With the increase of the final temperature of heat carrier and constant temperature, as well as the decrease of volume ratio of coal and hot carrier reactor, specific surface area and pore volume of semi-coke increased rapidly first and then decreased and finally increased, along with the rapidly reduction of average pore size. SEM photos show that the surface of semi-coke becomes increasingly rough and glossy.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA07030100)
文摘In a test rig,pulverized semi-coke was preheated to 850℃in a circulating fluidized bed(CFB)and then cornbusted at 1100℃in a down-fired combustor(DFC).Experiments were conducted to reveal the effects of three secondary air nozzle cases(co-axial jet,top circular jet and wall circular jet)on the NO emission.The results show that the optimized secondary air nozzle can reduce NO emission.O_2 concentration profile is the major factor affecting NO generation and emission,which is led by the secondary air nozzle.The lower O_2 concentration led to the generation of lower initial NO.The NO emission at the exit of the DFC was reduced from 189 to 92mg/m^3(@6%O_2)with the decrease of initial generation.The peak of NO at 100 mm below the nozzle should be attributed to the oxidization of NH_3 in the syngas,rather than the oxidization of fuel-N in the char.The low and well-distributed O_2 concentration contributes to the reduction of initial NO,which helps to reduce the NO emission.The combustion effieiencies of the eases of the co-axial jet,the top circular jet,and the wall circular jet are97.88%,98.94%and 98.74%,respectively.
