Production of ethylene using high temperature demethanization

A method for producing a secondary ethylene rich product stream from a mixed charge gas comprising:

• introducing a pressurized mixed olefin bearing charge gas into a demethanizer;
• separating said mixed charge gas under conditions effective to produce a bottoms and an overhead comprising said secondary ethylene rich product stream;
• separating said overhead into a vapor phase and a liquid phase, wherein said vapor phase comprises said secondary ethylene rich product stream;
• and
• recovering a primary ethylene rich product stream from said bottoms.

In a process for producing a primary ethylene rich product stream from a pressurized mixed olefin bearing charge gas comprised of a mixture of olefins inclusive of ethylene, aliphatics, inclusive of methane, and hydrogen and carbon monoxide by fractionation in a distillation column provided with multiple distillation trays, heat is input during the operation to a reboiler located at the bottom of the column, and a portion of the effluent vapor from the overhead of the column containing methane and products lower boiling than methane is cooled, liquified, and reintroduced to the top of the column as reflux, the combination of steps comprising:

• (a) introducing the charge gas at a temperature above about -55.degree. F. directly from an olefins generation/preparation process to the feed tray of a high temperature demethanizer fractional distillation tower whose condenser temperature is above about -55.degree. F. under conditions sufficient to produce from the overhead of the column a vapor containing methane and products lower boiling than methane,
• (b) producing also by operation of said demethanizer a secondary ethylene rich product stream which contains virtually all of the hydrogen, carbon monoxide and methane in the charge gas along with a quantity of ethylene that is less than 50% and greater than 1% of the ethylene contained in the charge gas, and a demethanizer bottoms stream containing the balance of the material in the charge gas stream, and
• (c) introducing said demethanizer bottoms stream to a deethanizer fractional distillation tower to produce a deethanizer overhead stream containing propylene and higher boiling materials that is less than 50% of those higher boiling materials contained in the demethanizer bottoms stream, and a deethanized bottoms stream containing the balance of the material in the demethanizer bottoms stream.

In a process for producing a primary ethylene rich product stream from a pressurized mixed olefin bearing charge gas comprised of a mixture of olefins, inclusive of ethylene, aliphatics, inclusive of methane, and hydrogen and carbon monoxide by fractionation in a distillation column provided with multiple distillation trays, heat is input during the operation to a reboiler located at the bottom of the column, and a portion of the effluent vapor from the overhead of the column containing methane and products lower boiling than methane is cooled, liquified, and reintroduced to the top of the column as reflux, the combination of steps comprising:

• (a) introducing the charge gas at a temperature above about 55.degree. F., to a deethanizer fractional distillation tower to produce a deethanizer overhead stream containing over 50% of the ethane in the charge gas along with a quantity of propylene and higher boiling materials that is less than 50% of those higher boiling materials contained in the charge gas, and a deethanized bottoms stream containing the balance of the-material in the charge gas,
• (b) introducing deethanizer overhead stream at a temperature above about -55.degree. F., to the feed tray of a high temperature demethanizer fractional distillation tower whose condenser temperature is above about -55.degree. F.,
• (c) operating said demethanizer to produce a secondary ethylene rich product stream as the overhead containing virtually all of the hydrogen, carbon monoxide and methane in the charge gas along with a quantity of ethylene that is less than 50% and greater than 1% of the ethylene contained in the deethanizer overhead stream, and a demethanized bottoms stream containing the balance of the material in the deethanizer overhead stream,
• (d) introducing said demethanizer bottoms stream to a C2 splitter fractional distillation tower to produce a primary ethylene rich product stream as the overhead or sidestream above the feed tray containing over 50% of the ethylene in the demethanizer bottoms stream along with a quantity of ethane and other higher boiling materials that is less than 50% of those higher boiling materials contained in the demethanizer bottoms stream, and a C2 splitter bottoms stream containing the balance of the material in the demethanizer bottoms stream.

In a process for producing a primary ethylene rich product stream from a Pressurized mixed olefin bearing charge gas comprised of a mixture of olefins, inclusive of ethylene, aliphatics, inclusive of methane, and hydrogen and carbon monoxide by fractionation in a distillation column provided with multiple distillation trays, heat is input during the operation to a reboiler located at the bottom of the column., and a portion of the effluent vapor from the overhead of the column containing methane and products lower boiling than methane is cooled, liquified, and reintroduced to the top of the column as reflux, the combination of steps comprising:

• (a) introducing the charge gas at a temperature above about -55.degree. F., to a high temperature demethanizer fractional distillation tower whose condenser temperature is above about -55.degree. F.,
• (b) operating said demethanizer to produce a secondary ethylene rich product stream as the overhead containing virtually all of the hydrogen, carbon monoxide and methane in the charge gas along with a quantity of ethylene that is less than 50% and greater than 1% of the ethylene contained in the charge gas, and a demethanizer bottoms stream containing the balance of the material in the charge gas stream,
• (c) introducing said demethanizer bottoms stream to a C2 splitter fractional distillation tower to produce a primary ethylene rich product stream as the overhead containing over 50% of the ethylene in the deethanizer overhead stream along with a quantity of ethane and other higher boiling materials that is less than 50% of those higher boiling materials contained in the demethanizer bottoms stream, and a C2 splitter bottoms stream containing the balance of the material in the demethanizer bottoms stream.