Hydrocarbon pyrolysis

Patent metadata

Field	Value
Publication number	US-10669488-B2
Application number	US-201716320396-A
Country	US
Kind code	B2
Filing date	Aug 15, 2017
Priority date	Aug 31, 2016
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

The invention relates to hydrocarbon pyrolysis, to equipment and materials useful for hydrocarbon pyrolysis, to processes for carrying out hydrocarbon pyrolysis, and to the use of hydrocarbon pyrolysis for, e.g., hydrocarbon upgrading.

First claim

The invention claimed is:

1. A hydrocarbon pyrolysis process, the process comprising:
(a) providing a feed comprising ≥1 wt. % of C 2+ hydrocarbon, wherein the feed has a pyrolysis heat of reaction (ΔH in cal./mol);
(b) providing an elongated flow-through reactor having (i) an internal volume which includes first and second regions, opposed first and second openings in fluidic communication with the internal volume, wherein the first and second openings are separated by a reactor length (L R ), and (ii) a first thermal mass located in the first region, wherein the first channeled thermal mass has a solid density (ρ s ) ≤12 g/cm 3 , a heat capacity (C P ) ≤0.5 cal/g° C., and an open frontal area (OFA) ≤55%, and wherein the first channeled thermal mass includes:
(A) a first aperture, the first aperture being proximate to the first opening and in fluidic communication with the first opening,
(B) at least one internal channel in fluidic communication with the first aperture, and
(C) a second aperture, the second aperture being in fluidic communication with the first aperture via a flowpath through the channel;

(c) preselecting pyrolysis conditions for pyrolysis of the feed in the channel, wherein the pyrolysis conditions include a residence time in the channel (t R ) ≤1 sec., a feed conversion (X) ≥50%, an average total pressure in the channel (P) ≥1 bar, an average bulk gas temperature in the channel (T av ) ≤1500° C. at the start of the pyrolysis, a peak gas temperature (T P ) located in the channel, T P >T av , and a change in average bulk gas temperature during the pyrolysis (ΔT av ) ≤100° C.;
(d) predetermining a reference pyrolysis step time (t ref ), wherein
t ref =( t R *ρ s *C p *R*T av *ΔT av )*([1− OFA ]* OFA −1 )*( X*ΔH*P ) −1 ,

and R is substantially equal to the feed's Gas Constant; and
(e) pyrolysing the feed in the channel under the preselected conditions during a pyrolysis time interval t P that does not exceed t Ref .

2. The process of claim 1 , wherein (i) the location of T P remains substantially constant during t P , (ii) the feed is introduced into the reactor through the first opening, through the first aperture, and toward the second aperture at a flow rate ≥0.01 kg/s, (iii) when t ref is >0.001 second, t P is ≤t ref , and when t ref is ≤0.001 second, t P is 0.001 second, and (iv) the process further comprises:
(f) at least part of the pyrolysis of the feed flow's C 2+ hydrocarbon is carried out in the channel, which cools the first channeled thermal mass and produces a flow of a pyrolysis product comprising molecular hydrogen, acetylene, C 2+ olefin, and coke; and
(g) during t P , conducting the flow of at least a portion of the pyrolysis product into the second region of the internal volume via the second aperture, and away from the reactor via the second opening.

3. The process of claim 1 , wherein the pyrolysis conditions further include a hydrocarbon partial pressure of ≥7 psia (48 kPa) and an average total pressure of ≥5 psig (34 kPag), and (v) t P is ≥2 seconds.

4. The process of claim 1 , wherein (i) the reactor is a reverse-flow thermal pyrolysis reactor, the reactor further comprising a second thermal mass located in the second region of the internal volume, the second thermal mass having at least one internal channel having at least one in fluidic communication with the internal channel of the first thermal mass, and (ii) the process further comprises (f) conducting the pyrolysis product through the internal channel of the second thermal mass before the pyrolysis product is conducted away from the reverse-flow reactor, and (g) cooling the pyrolysis product by transferring heat from the pyrolysis product to the second thermal mass.

5. The process of claim 1 , wherein (i) the C 2+ olefin includes one or more of ethylene, propylene, and butylene, (ii) the pyrolysis product further comprises coke and one or more of acetylene, benzene, methane, and at least a portion of any unconverted feed, and (iii) at least a portion of the coke remains in the internal channel of the first thermal mass as a deposit.

6. The process of claim 1 , wherein the feed comprises one or more of ethane, propane, butanes, saturated and unsaturated C 6 hydrocarbon, including those derived from one or more of Fischer-Tropsch synthesis products, shale gas, biogas, associated gas, natural gas and mixtures or components thereof, steam cracked gas oil and residues, gas oils, heating oil, jet fuel, diesel, kerosene, gasoline, naphtha (including coker naphtha, steam cracked naphtha, and catalytically cracked naphtha), hydrocrackate, reformate, raffinate reformate, Fischer-Tropsch liquids, natural gasoline, distillate, virgin naphtha, crude oil, atmospheric pipestill bottoms, vacuum pipestill streams including bottoms, wide boiling range naphtha to gas oil condensates, heavy non-virgin hydrocarbon streams from refineries, vacuum gas oils, heavy gas oil, naphtha contaminated with crude, synthetic crudes, shale oils, coal liquefaction products, coal tars, tars, atmospheric resid, heavy residuum, C 4 -residue admixture, naphtha-residue admixture, cracked feed, coker distillate streams, and hydrocarbon streams derived from plant or animal matter.

7. The process of claim 1 , wherein X is ≥60 wt. %.

8. The process of claim 1 , wherein (i) the OFA ≤50%, and (ii) ΔT av 75° C.

9. The process of claim 1 , wherein (i) t P is ≥2 seconds, (ii) the pyrolysis conditions include a gas residence time in the channel of ≤0.5 seconds, (iii) the feed flow rate is (A) substantially constant during t P and (B) ≥0.1 kg/s, (iv) the OFA is in the range of from 10% to 50%; (v) the first thermal mass has a thermal conductivity in the range of from 0.5 W/m° K to 50 W/m° K, a coefficient of thermal expansion in the range of from 1×10 −7 /° K to 2×10 5 /° K, an average wetted surface area per unit volume in the range of from 1 cm −1 to 100 cm −1 , an average wetted surface area per unit volume in the range of from 1 cm −1 to 100 cm −1 ; (vi) the internal channel of the first thermal mass includes a plurality of substantially parallel passages and has a passage density in the range of from 77000/m 2 to 1.3×10 6 /m 2 ; (vii) the refractory has a specific heat capacity at 300° K ≥0.04 [kj/(° K kg)] and a mass density ≥3000 kg/m 3 ; and (vii) the refractory includes at least one oxide of one or more elements selected from Groups 2-14 of the Periodic Table.

10. The process of claim 9 , wherein the first thermal mass is in the form of at least one monolithic honeycomb having a mass ≥1 kg; the refractory's oxide includes oxide of at least one of Al, Si, Mg, Ca, Fe, Mn, Ni, Co, Cr, Ti, Hf, V, Nb, Ta, Mo, W, Sc, La, Yt, Zr, and Ce; the refractory's specific heat capacity at 300° K is in the range of from 0.04 [kj/(° K kg)] to 1.2 [kj/(° K kg)]; the refractory's mass density is in the range of from 3000 kg/m 3 to 5000 kg/m3; and t R is in the range of from 0.01 second to 0.4 second.

11. A hydrocarbon pyrolysis process, the process comprising:
(a) providing a feed comprising ≥1 wt. % of C 2+ hydrocarbon, wherein the feed has a pyrolysis heat of reaction (ΔH in cal./mol);
(b) providing an elongated flow-through reactor having (i) an internal volume which includes first and second regions, (ii) opposed first and second openings in fluidic communication with the internal volume, wherein the first and second openings are separated by a reactor length (L), and (iii) a thermal mass located in the first region, wherein the thermal mass has a solid density (ρ s ) ≤12 g/cm 3 , a heat capacity (C P ) ≤0.5 cal/g° C., and a predetermined open frontal area (OFA), and wherein the thermal mass includes:
(A) a fi

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Barrai Federico
• Lattner James R
• Hershkowitz Frank
• Mahoney Elizabeth G

Classifications

• B01J6/008

  Pyrolysis reactions (of hydrocarbons C10G9/00) · CPC title

• C10G9/002

  Cooling of cracked gases · CPC title

• C10G9/26 Primary

  with discontinuously preheated non-moving solid material, e.g. blast and run · CPC title

• C10G2400/20

  C2-C4 olefins · CPC title

• B01J8/0492 Primary

  Feeding reactive fluids (for solid material, see B01J8/0015) · CPC title