The invention relates to a process for carrying out
fractionation to
oil shale by utilizing gas as a thermal carrier under the condition of whole circulation. The
oil shale is divided into three classes with different specifications: 0 to 6 millimeters, 6 to 20 millimeters and 20 to 50 millimeters; and the
oil shale enters different
carbonization furnaces for
carbonization. The daily handling capacity of each set of the
carbonization furnace is 1,000 tons. The oil shale is crushed and sifted, is dried and heated to the temperature of over 50 DEG C by
smoke gas and enters the carbonization furnaces with different specifications for carbonization. The inside of the carbonization furnace is provided with feed distribution perforated wall which is matched with the particle size of the oil shale and a gas distribution structure. Thermal circulating gas is heated to the temperature of 700 DEG C in a
heating furnace and is evenly and continuously transported to the middle part of the carbonization furnaces. Cold circulating gas enters from the lower part of the carbonization furnaces; carbonized carbocoal is cooled to the temperature of 250 DEG C, is discharged to a water-sealed carbocoal
pool, is cooled to the temperature of 80 DEG C and is discharged to the outside of the furnace. One part of the carbocoal is transported to the
heating furnace, is mixed with the gas for
combustion; and one part of the carbocoal is transported to a power
plant as a fuel. Carbonized oil gas passes through a
cooling tower and is subjected to oil collection by an electric catcher and performs oil-gas-water separation; oil enters a
storage tank; and water enters a circulating
water pool. One part of the gas is used as the thermal carrier and is circularly used. One part of the gas is used as the fuel for the
heating furnace; and one part of the gas is used as
fuel gas for power generation. The theoretical oil yield of the process can reach over 90 percent.