Processes and systems for fractionating a pyrolysis effluent

A process for fractionating a steam cracker effluent, comprising:

• contacting a steam cracker effluent with a quench fluid to produce a cooled steam cracker effluent;
• separating a tar product and a light product from the cooled steam cracker effluent, wherein the light product is substantially in a vapor phase and at a temperature of ≥155° C. to ≤315° C.;
• indirectly transferring heat from the light product to water, steam, or a mixture of water and steam to produce a cooled light product and a first medium pressure steam, wherein the first medium pressure steam is at a pressure of about 827 kPag to about 1,720 kPag and wherein the cooled light product is at a temperature of ≥150° C. to ≤300° C.;
• introducing the cooled light product into a primary fractionator having a maximum inner diameter of ≤16.8 meters;
• separating a steam cracker quench oil, a steam cracker gas oil, and an overhead product from the primary fractionator, wherein the overhead product comprises steam cracker naphtha and a process gas comprising ethylene;
• separating the steam cracker naphtha and the process gas from the overhead product, wherein >136 tonnes per hour of ethylene is separated from the overhead product;
• cooling the steam cracker quench oil by indirect heat exchange with water, steam, or a mixture of water and steam to produce a first cooled steam cracker quench oil and a second medium pressure steam, wherein the second medium pressure steam is at a pressure of about 827 kPag to about 1,720 kPag;
• cooling at least a portion of the first cooled steam cracker quench oil by indirect heat exchange with water, steam, or a mixture of water and steam to produce a second cooled steam cracker quench oil and low pressure steam, wherein the low pressure steam is at a pressure of <827 kPag;
• and
• introducing at least a portion of the second cooled steam cracker quench oil into the primary fractionator as a quench medium.

A process for fractionating a steam cracker effluent, comprising:

• contacting a steam cracker effluent with a quench fluid to produce a cooled steam cracker effluent, wherein the steam cracker effluent is at a temperature of ≥400° C. when initially contacted with the quench fluid;
• separating a tar product and a light product from the cooled steam cracker effluent, wherein the light product is substantially in a vapor phase and at a temperature of ≥155° C. to ≤315° C.;
• cooling the light product by indirect heat exchange with water, steam, or a mixture of water and steam to produce a cooled light product and a first medium pressure steam, wherein the cooled light product is at a temperature of ≥150° C. to ≤300° C., wherein the first medium pressure steam is at a pressure of about 827 kPag to about 1,720 kPag, and wherein the cooled light product is in the vapor phase and liquid phase;
• introducing the cooled light product into a flash zone section of a primary fractionator, wherein the cooled light product is at a temperature of ≥150° C. to ≤280° C. when introduced into the primary fractionator, and wherein the primary fractionator comprises the flash zone section located toward a bottom of the primary fractionator, a bottom pump-around section located above the flash zone, a mid-fractionation section located above the bottom pump-around section, a top pump-around section located above the mid-fractionation section, and a top-fractionation section located above the top pump-around section, wherein:
• one or more first trays is disposed within the bottom pump-around section and wherein the one or more first trays including a plurality of liquid passes,
• one or more second trays is disposed within the mid-fractionation section,
• one or more third trays is disposed within the top pump-around section, and
• one or more fourth trays is disposed in the top-fractionation section;
• separating a steam cracker quench oil from the flash zone section;
• separating a steam cracker gas oil from the mid-fractionation section;
• separating an overhead product comprising steam cracker naphtha and a process gas comprising ethylene from the top-fractionation section, wherein ≥136 tons per hour of ethylene is separated from the overhead product;
• separating the steam cracker naphtha and the process gas from the overhead product, wherein the steam cracker naphtha has a final atmospheric boiling point of ≤260° C., as measured according to ASTM D2887-18;
• cooling the steam cracker quench oil by indirect heat exchange with water, steam, or a mixture of water and steam to produce a first cooled steam cracker quench oil and a second medium pressure steam, wherein the second medium pressure steam is at a pressure of about 827 kPag to about 1,720 kPag;
• cooling at least a portion of the first cooled steam cracker quench oil by indirect heat exchange with water, steam, or a mixture of water and steam to produce a second cooled steam cracker quench oil and low pressure steam, wherein the low pressure steam is at a pressure of <827 kPag;
• and
• introducing a portion of the steam cracker naphtha into the top-fractionation section, wherein the steam cracker naphtha is introduced into the top-fractionation section, relative to a weight of hydrocarbons in the steam cracker effluent, at a weight ratio of about 0.2:1 to about 0.45:1.