Process for mild hydrocracking of heavy hydrocarbon fractions with optimized thermal integration for the purpose of reducing greenhouse gas emissions

A process for mild hydrocracking of a fraction of the VGO type for the purpose of constituting the feedstock of a catalytic cracking unit, comprising:

• hydrocracking a VGO stream in a zone R wherein the VGO stream has been heated by a diesel-circulating reflux and a furnace F-1,
• separating a hydrogen rich gaseous phase and a liquid stream from the reaction effluent of zone R in a high-pressure hot separator tank B-1,
• separating a hydrogen rich gas stream and a liquid stream from the hydrogen rich gaseous phase stream from B-1 which has been cooled, wherein the separation occurs in a high-pressure cold separator tank B-2,
• storing the liquid stream from B-2 which has been compressed, wherein the storage occurs in a low-pressure cold separator tank B-3,
• washing the hydrogen rich stream with an amine and compressing the washed rich hydrogen stream, wherein both washing and compressing occur in a zone K-1,
• compressing a VGO feedstock and mixing the compressed VGO feedstock with the washed and compressed hydrogen rich stream obtained from K-1,
• stripping a mixture of the liquid streams obtained from B-1 and B-3 in a stripper C-1,
• separating naphtha, diesel, and residue from the stripped stream obtained from C-1, where the separating occurs in a fractionator C-2 wherein the striped stream obtained from C-1 has been heated by a furnace F-2,
• stripping the diesel obtained from C-2, wherein said stripping occurs in a second stripper C-3,
• wherein the VGO stream is heated in exchanger E-8 with the stripped diesel obtained from C-3, in exchanger E-4 with the diesel-circulating reflux, and in exchanger train E-7 with the bottom of the fractionator C2, wherein train E-7 comprises at least one calendar, and/or
• the hydrogen rich gaseous phase stream from B-1 is cooled in exchanger E-2 A and exchanger E-2 B with the liquid stream from B-3, in exchanger E-9 with a high-pressure feedstock mixed with hydrogen, and in E-3 A and E-3 B with a mixture of addition hydrogen and a part of a recycled hydrogen stream, where the heat exchange occurs in the following order:
• E-2 A, E-9, E-3 A, E-2 B, and E-3 B, and/or
• the effluent of zone R is cooled in exchanger train E-1 with the VGO feedstock, wherein train E-1 comprises at least one calendar;
• and in exchanger train E-10 with the feedstock of the fractionator C-2, wherein exchanger train E-10 comprises at least one calendar and wherein the calendars are located between calendars of exchanger train E-1, and/or
• the bottom of the fractionator C-2 is cooled by exchanger E-5 with the diesel for reboiling the diesel stripper C-3 and the exchanger E-6 with the feedstock of the fractionator C-2.