Catalytic conversion process and system for producing gasoline and propylene

A process for producing gasoline and propylene, comprising the steps of:

• 1) Subjecting a feedstock oil to a first catalytic conversion reaction in a first catalytic conversion reaction device to obtain a first reaction product comprising propylene, C4 olefin and a gasoline component;
• 2) separating the first reaction product to obtain a propylene fraction, a gasoline fraction, a first C4 olefin-containing fraction having 40-100 wt % C4 olefin, optionally a light cycle oil fraction and optionally a fluidized catalytic cracking gas oil (FGO) fraction;
• 3) Subjecting the first C4 olefin-containing fraction obtained in step 2) or a combination of the first C4 olefin-containing fraction obtained in step 2) and a C4 olefin-containing fraction from an external source to olefin oligomerization in an oligomerization reactor to obtain an oligomerization product comprising C12 olefin, and separating the oligomerization product to obtain a C12 olefin-containing fraction, wherein the C12 olefin-containing fraction has a C12 olefin content of no less than 70 wt %, based on the weight of the C12 olefin-containing fraction;
• 4) Sending the C12 olefin-containing fraction to the first catalytic conversion reaction device, and/or sending the C12 olefin-containing fraction to a second catalytic conversion reaction device for a second catalytic conversion reaction to obtain a second reaction product comprising propylene;
• and
• 5) optionally, subjecting the FGO fraction to a first hydrotreatment in a first hydrotreating reactor to obtain a hydrogenated FGO, and recycling at least a part of the hydrogenated FGO to the first catalytic conversion reaction device and/or sending it to the second catalytic conversion reaction device, and/or recycling the light cycle oil fraction to the first catalytic conversion reaction device and/or sending it to the second catalytic conversion reaction device,
• wherein the second catalytic conversion reaction device, when present, is a fluidized bed reactor that is a riser reactor or a composite reactor comprising a riser in combination with a dense phase bed, wherein the riser reactor is an equal-diameter riser reactor, a constant-linear-velocity riser reactor or a diameter-transformed riser reactor, and
• wherein the first catalytic conversion reaction device is a diameter-transformed riser reactor comprising a first reaction zone and a second reaction zone having a diameter greater than the first reaction zone along the direction of the reaction stream,
• wherein the reaction conditions in the first reaction zone include:
• a reaction temperature of about 450-620° C., a reaction time of about 0.5-2.0 seconds, and a catalyst-to-feedstock weight ratio of about 3:1 to about 15:1, a steam-to-feedstock weight ratio of about 0.03:1 to about 0.3:1, and
• the reaction conditions in the second reaction zone include:
• a reaction temperature of about 460-550° C., a reaction time of about 2-30 seconds, a catalyst-to-feedstock weight ratio of about 4:1 to about 18:1, and a steam-to-feedstock weight ratio of about 0.03:1 to about 0.3:1, and
• wherein, in step 4), the C12 olefin-containing fraction is recycled to the second reaction zone of the first catalytic conversion reaction device that is a diameter-transformed riser reactor in step 4), at least a part of the hydrogenated FGO is recycled to the first reaction zone of the diameter-transformed riser reactor in step 5), and/or the light cycle oil fraction is recycled to the first reaction zone of the diameter-transformed riser reactor in step 5).

A system for producing gasoline and propylene, comprising a first catalytic conversion reaction device, a regenerator, an oil-catalyst separation device, a product separation device, an oligomerization reactor, a rectifying column and optionally a second catalytic conversion reaction device, wherein:

• the first catalytic conversion reaction device is configured to perform a first catalytic conversion reaction on a feedstock oil therein to obtain a reaction effluent comprising a first reaction product and a spent catalyst, wherein the first reaction product comprises propylene, C4 olefin, and a gasoline component;
• the oil-catalyst separation device is configured to separate the first reaction product from the spent catalyst in the reaction effluent of the first catalytic conversion reaction device,
• the regenerator is configured to regenerate the spent catalyst and recycle the regenerated catalyst to the first catalytic conversion reaction device,
• the product separation device is configured to separate the first reaction product to obtain a propylene fraction, a gasoline fraction, a C4 olefin-containing fraction comprising C4 olefin, optionally a light cycle oil fraction and optionally a FGO fraction,
• the oligomerization reactor is configured to conduct an olefin oligomerization on the C4 olefin-containing fraction to obtain an oligomerization product comprising C12 olefin, and send the oligomerization product to the rectifying column;
• the rectifying column is configured to separate the oligomerization product to obtain a C12 olefin-containing fraction having a C12 olefin content of no less than 70 wt %, based on the weight of the C12 olefin-containing fraction, and recycle the C12 olefin-containing fraction to the first catalytic conversion reaction device or to the optional second catalytic conversion reaction device;
• the second catalytic conversion reaction device, when present, is configured to perform a second catalytic conversion reaction on the C12 olefin-containing fraction to obtain a second reaction product comprising propylene,
• wherein the first catalytic conversion reaction device is provided with a catalyst inlet, at least one catalytic conversion feedstock inlet, and an oil-catalyst outlet, the regenerator is provided with a spent catalyst inlet and a regenerated catalyst outlet, the oil-catalyst separator is provided with an oil-catalyst inlet, an oil-gas outlet, and a spent catalyst outlet, the product separator is provided with an oil-gas inlet, a propylene fraction outlet, a gasoline fraction outlet, and a C4 olefin-containing fraction outlet, the oligomerization reactor is provided with an oligomerization feedstock inlet and an oligomerization product outlet, and the rectifying column is provided with an oil-gas inlet and a C12 olefin-containing fraction outlet;
• the catalyst inlet of the first catalytic conversion reaction device is in fluid communication with the regenerated catalyst outlet of the regenerator, the oil-catalyst outlet of the first catalytic conversion reaction device is in fluid communication with the oil-catalyst inlet of the oil-catalyst separation device, the spent catalyst outlet of the oil-catalyst separation device is in fluid communication with the spent catalyst inlet of the regenerator, the oil-gas outlet of the oil-catalyst separation device is in fluid communication with the oil-gas inlet of the product separation device, the C4 olefin-containing fraction outlet of the product separation device is in fluid communication with the oligomerization feedstock inlet of the oligomerization reactor, the oligomerization product outlet of the oligomerization reactor is in fluid communication with the oil-gas inlet of the rectifying column, and the C12 olefin-containing fraction outlet of the rectifying column is in fluid communication with one catalytic conversion feedstock inlet of the first catalytic conversion reaction device or in fluid communication with the feedstock inlet of the second catalytic conversion reaction device,
• wherein the system further comprises a first hydrotreating reactor, wherein the product separation device is further provided with a FGO fraction outlet, the feedstock inlet of the first hydrotreating reactor is in fluid communication with the FGO fraction outlet of the product separation device, and the product outlet of the first hydrotreating reactor is in fluid communication with one catalytic conversion feedstock inlet of the first catalytic conversion reaction device or in fluid communication with the feedstock inlet of the second catalytic conversion reaction device;
• and
• the product separation device is further provided with a light cycle oil fraction outlet, and the light cycle oil fraction outlet of the product separation device is in fluid communication with one catalytic conversion feedstock inlet of the first catalytic conversion reaction device or is in fluid communication with the feedstock inlet of the second catalytic conversion reaction device.