Anti-Coking Method for Production of Light Olefins from Crude Oil by Catalytic Cracking and Device Thereof

Abstract

A method for preventing coking in a reaction system for producing light olefins from crude oil by catalytic cracking includes: reducing temperature of oil gas discharged from a reactor, adsorbing a condensed liquid-phase oil by a spent catalyst, allowing a cooled oil gas to enter a disengager for gas-solid separation, and delivering most of the spent catalyst to the disengager. The above method is taken to avoid coking of the reaction system and to ensure stable operation of a device for a long period of time; and the high-temperature potential heat of the oil gas is fully utilized, making the energy utilization of the whole system more reasonable, and achieving the effects of energy saving and emission reduction.

1 . A method for preventing coking in a reaction system for producing light olefins from crude oil by catalytic cracking, including:
 reducing temperature of oil gas discharged from a reactor,   adsorbing a condensed liquid-phase oil by a spent catalyst,   allowing a cooled oil gas to enter a disengager for gas-solid separation, and   delivering most of the spent catalyst to the disengager.   
     
     
         2 . The method according to  claim 1 , wherein, the oil gas and the spent catalyst discharged from the reactor are first subjected to gas-solid separation in a primary separator, and a separated oil gas carries a part of the spent catalyst to enter a heat exchanger for heat exchange to reduce the temperature of the separated oil gas. 
     
     
         3 . The method according to  claim 2 , wherein, a total amount of the spent catalyst carried in the separated oil gas separated by the primary separator is less than 40% of a total amount of the spent catalyst carried in the oil gas from the reactor. 
     
     
         4 . The method according to  claim 2 , wherein, a total amount of the spent catalyst carried in the separated oil gas separated by the primary separator is in range of 5-25% of a total amount of the spent catalyst carried in the oil gas from the reactor. 
     
     
         5 . The method according to  claim 2 , wherein, a superficial gas velocity below an inlet of the primary separator is not more than 2 m/s. 
     
     
         6 . The method according to  claim 2 , wherein, a superficial gas velocity above an inlet of the primary separator is not less than 0.5 m/s. 
     
     
         7 . The method according to  claim 2 , wherein, the heat exchanger is located outside the reactor and the disengager, the primary separator is arranged between the heat exchanger and the reactor;
 the primary separator is connected with the reactor, the exchanger and the disengager;   the primary includes a separator body, an inlet, an outlet and a discharging inclined tube, and   in a vertical direction, an outlet end of the discharging inclined pipe is located above a middle portion of an expanding section of the disengager.   
     
     
         8 . The method according to  claim 7 , wherein, a slide valve is arranged on the discharging inclined pipe of the primary separator, and the amount of the catalyst carried by the oil gas entering the heat exchanger is regulated by controlling opening state of the valve. 
     
     
         9 . The method according to  claim 8 , wherein, a conveying medium driving the catalyst to enter the disengager is introduced into the discharging inclined pipe of the primary separator, and the amount of the catalyst carried by the oil gas entering in the heat exchanger is adjusted by adjusting the opening state of the slide valve and the amount of the conveying medium. 
     
     
         10 . A reaction device for producing light olefins from crude oil by catalytic cracking, including: a reactor, a disengager, and a heat exchanger, wherein the heat exchanger is located outside the reactor and the disengager, an inlet of the heat exchanger is connected with an outlet of the reactor, and an outlet of the heat exchanger is connected with a cyclone separator in the disengager. 
     
     
         11 . The reaction device according to  claim 10 , further including a primary separator, wherein, the primary separator is arranged between the heat exchanger and the reactor, and connected with the heat exchanger and the reactor respectively. 
     
     
         12 . The reaction device according to  claim 11 , wherein, the inlet of the heat exchanger for feeding the oil gas and the catalyst is located above the outlet of the reactor, and
 the inlet of the heat exchanger for feeding the oil gas and the catalyst is lower than the outlet of the heat exchanger.   
     
     
         13 . The reaction device according to  claim 11 , wherein, an upper part of the reactor has a bend, such that the outlet of the reactor faces downwards, and
 the outlet of the reactor is connected with the inlet of the heat exchanger for feeding the oil gas and the catalyst,   the inlet of the heat exchanger for feeding the oil gas and the catalyst is higher than the outlet of the heat exchanger.   
     
     
         14 . The reaction device according to  claim 11 , wherein, the inlet of the heat exchanger for feeding the oil gas and the catalyst is connected with the outlet of the reactor by a bent pipe, and
 the inlet of the heat exchanger for feeding the oil gas and the catalyst is higher than the outlet of the heat exchanger.   
     
     
         15 . The reaction device according to  claim 11 , wherein, the disengager includes a disengager tank and a cyclone separator arranged in the disengager tank, and
 the primary separator is arranged outside the disengager tank and the reactor.   
     
     
         16 . The reaction device according to  claim 11 , wherein, the primary separator includes a separator body, an inlet, an outlet, and a discharging inclined tube,
 an outlet end of the discharging inclined tube is located in the disengager tank,   the outlet of the primary separator is connected with the inlet of the heat exchanger, and the outlet of the heat exchanger is connected with the cyclone separator, and   the inlet of the primary separator is connected with the outlet of the reactor.   
     
     
         17 . The reaction device according to  claim 16 , wherein, the discharging inclined tube of the primary separator is extended into the disengager tank through a wall of the disengager tank, and the discharging inclined tube in the disengager is substantially perpendicular to the wall of the tank. 
     
     
         18 . The reaction device according to  claim 16 , wherein, the discharging inclined tube of the primary separator includes a horizontal section and a vertical section,
 the horizontal section is located below the vertical section,   the vertical section is connected to a bottom of the separator body,   the horizontal section is extended at least partially into the disengager tank,   the horizontal section is substantially parallel to a horizontal plane, and   the vertical section is a pipeline for conveying the catalyst downward.   
     
     
         19 . The reaction device according to  claim 16 , wherein, the discharging inclined tube of the primary separator is extended into the disengager tank through the tank wall of an expanding section of the disengager tank. 
     
     
         20 . The reaction device according to  claim 16 , wherein, a gas distributor is arranged within the separator body of the primary separator,
 the gas distributor is an annular pipe with vent holes uniformly formed in the wall of the pipe.   
     
     
         21 . The reaction device according to  claim 20 , wherein, the gas distributor is located in the separator body near the discharging inclined tube.