Pyrolysis furnace with an internally finned U shaped radiant coil
AssigneeExxonMobil Chemical Patents Inc.
InventorsArthur R. Di Nicolantonio, David B. Spicer, Victor K. Wei
Life of this patent
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Abstract
The present invention is directed towards a fired heater for heating a process fluid that uses U tubes provided with increased internal heat transfer surface to reduce tube metal temperatures and coking. and at the same time is not prone to plugging from coke. The fired heater comprises a radiant section enclosure with a number of U tubes in the radiant section. The U tubes are formed by connecting one or more tubular sections, and the U tubes are provided with internal generally longitudinal fins. The invention also is directed towards a process utilizing a fined heater with U tubes as disclosed for producing olefins from hydrocarbon feedstocks.
Claims68
A heater for heating a process fluid comprising:
- a radiant section enclosure means having a plurality of U tubes disposed therein,
- an inlet means for introducing the process fluid into the U tubes,
- a means for exposing the external surface of the U tubes to radiant heat,
- an outlet means for cooling and collecting the process fluid from each of the U tubes,
- wherein the length of the U tubes are provided with internal generally longitudinal fins.
A heater for heating a process fluid comprising:
- a radiant enclosure having a plurality of U tubes with an inside diameter of about 1.25 inches to about 3.0 inches and a total length from about 50 ft to about 90 ft disposed therein;
- an inlet header for introducing the process fluid into the U tubes;
- burners disposed within the radiant enclosure for exposing the external surface of the U tubes to radiant heat;
- an outlet means for cooling and collecting the process fluid from the U tubes;
- wherein the U tubes are formed by connecting one or more tubular sections and wherein the length of the U tubes are provided with from 8 to 24 internal generally longitudinal fins spaced around the inside circumference of the U tubes with a fin height of 0.10 to 0.25 inch, wherein the internal generally longitudinal fins have a fin root radius in the range of 0.10 to 0.20 inch and have a fin tip radius in the range of 0.10 to 0.20 inch.
In a fired heater for heating a process fluid in which a radiant section enclosure with a plurality of U tubes disposed therein which includes an inlet header for introducing the process fluid into the U tubes, and which includes a plurality of burners for exposing the external surface of the U tubes to radiant heat, in which the improvement comprises providing the entire length of the U tubes with internal generally longitudinal fins.
A heater for heating a process fluid comprising:
- a radiant enclosure means having disposed therein a plurality of two pass tubes comprising:
- (a) at least one inlet leg in flow communication with
- (b) at least one outlet leg and
- (c) a curved tubular means for providing flow communication between the inlet leg and outlet leg
- wherein each outlet leg is provided with internal generally longitudinal fins;
- a means for introducing the process fluid into the inlet leg;
- a means for exposing the external surface of the two pass tubes to heat;
- an outlet means for cooling and collecting the process fluid from the outlet leg.
A process for manufacture of olefins comprising:
- preheating a hydrocarbon feedstock,
- introducing the preheated feedstock into a plurality of radiant coils,
- heating the radiant coils by a plurality of burners to cause the hydrocarbon feedstock to thermally crack,
- collecting the cracked hydrocarbon feedstock from the radiant coil,
- cooling the cracked hydrocarbons feedstock,
- recovering at least one olefin from the cracked hydrocarbon feedstock,
- wherein each of the radiant coils comprise:
- (a) at least one inlet leg in flow communication with
- (b) at least one outlet leg and
- (c) a curved tubular means for providing flow communication between the inlet leg and outlet leg
- wherein each outlet leg is provided with internal generally longitudinal fins.
A process for manufacture of olefins comprising:
- preheating a hydrocarbon feedstock,
- introducing the preheated feedstock into a plurality of radiant coils,
- heating the radiant coils by a plurality of burners to cause the hydrocarbon feedstock to thermally crack,
- collecting the cracked hydrocarbon feedstock from the radiant coil,
- cooling the cracked hydrocarbon feedstock,
- recovering at least one olefin from the cracked hydrocarbon feedstock,
- decoking radiant coil of coke accumulated therein due to the thermal cracking reactions,
- wherein the radiant coils comprise an inlet leg and an outlet leg connected to form a U shape, and are provided with internal generally longitudinal fins and wherein the radiant coil decoke process is begun before the thickness of the coke accumulated therein exceeds a thickness sufficient to cause large coke particles to spall off the tube surface and plug downstream sections of the radiant coil during the decoking step.
Dependencies are inferred from the claim text.