Patent ID: 11905181
Assignee: GUANGXI SIWEI MATERIALS TECHNOLOGY CO., LTD.
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC C  B  F  Y | IPC B  C  F

Claim 0:
1. A method for preparing calcium oxide using a multistage suspension preheater kiln, wherein the method comprises steps of:
(1) feeding limestone powder to the multistage suspension preheater kiln for preheating to 800° C. to 900° C.;
(2) feeding a preheated material to a decomposition furnace and calcining at 900° C. to 1100° C. and a negative pressure of −0.9 kPa to −1.5 kPa for 25 s to 35 s;
(3) feeding a calcined material to a rotary kiln and calcining at 1100° C. to 1300° C. for 25 min to 35 min; cooling to obtain calcium oxide having a purity of 90% or greater;
wherein the multistage suspension preheater kiln comprises six-stage hot flue gas cyclones that are sequentially connected to a hot gas duct; the six-stage hot flue gas cyclones comprises a first-stage hot flue gas cyclone, a second-stage hot flue gas cyclone, a third-stage hot flue gas cyclone, a fourth-stage hot flue gas cyclone, a fifth-stage hot flue gas cyclone and a sixth-stage hot flue gas cyclone; the hot gas duct conveys hot flue gas upward; the first-stage hot flue gas cyclone on the hot gas duct is the topmost hot flue gas cyclone, and a material outlet of the fifth-stage hot flue gas cyclone connects to an inlet of the decomposition furnace;
an end of the hot gas duct is provided with an exhaust device; a material outlet of the first-stage hot flue gas cyclone connects to a hot flue gas outlet duct of the third-stage hot flue gas cyclone, a material outlet of the third-stage flue gas cyclone connects to a hot flue gas outlet duct of the fifth-stage hot flue gas cyclone; a material outlet of the second-stage hot flue gas cyclone connects to a hot flue gas outlet duct of the fourth-stage hot flue gas cyclone; a material outlet of the fourth-stage hot flue gas cyclone connects to a hot flue gas outlet duct of the sixth-stage hot flue gas cyclone; a material at an outlet of the decomposition furnace is fed to a feed pipe of the sixth-stage hot flue gas cyclone through a rising gas flow; a material outlet of the sixth-stage hot flue gas cyclone connects to a flue chamber of the rotary kiln; a raw material of the limestone powder is fed through the hot gas duct between the first-stage hot flue gas cyclone and the second-stage hot flue gas cyclone;
wherein a gas temperature in the first-stage hot flue gas cyclone is lower than that in the second-stage hot flue gas cyclone;
the second-stage hot flue gas cyclone has a gas temperature of 400° C. to 500° C. and a negative pressure of −4 kPa to −5 kPa;
the third-stage hot flue gas cyclone has a gas temperature of 500° C. to 600° C. and a negative pressure of −3.5 kPa to −4.5 kPa;
the fourth-stage hot flue gas cyclone has a gas temperature of 600° C. to 700° C. and a negative pressure of −2.5 kPa to −3.5 kPa;
the fifth-stage hot flue gas cyclone has a gas temperature of 800° C. to 900° C. and a negative pressure of −1.5 kPa to −2.5 kPa;
the sixth-stage hot flue gas cyclone has a gas temperature of 950° C. to 1130° C. and a negative pressure of −1.0 kPa to −2.0 kPa; and
wherein a particle size of the limestone powder is less than 70 mesh.