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Патент USA US2108636

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‘Feb. 15, 1938.
7
H, \(_ ATwELL
’ 2,108,636
PROPANE TREATING IN CRACKING SYSTEMS‘
Filed Feb. 16, 1934
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Pr'elim; 7Fl&a1s"h,
4
J
CTlaera’n_
INVENTOR
[go/1446(5
ATTORNEY
atented Feb. 1, I13’
namia v. Atwell, White Plains, n. y,
a
.to Standard Oil Company, Chicahh, a cor
I pcration of Indiana
Application February 16, 1934', Serial at. that"!
'
4 Claims.
(cl. 196-13)
This invention relates to the use of propane in
cracking systems and it pertains more particu
larly to an improved low temperature method of
?ltering pressure tar and of recovering and ,uti
5
lizing valuable products resulting from cracking
the naphtha or gasoline being withdrawn‘ for
use, and the dry gas being scrubbed with and
partially absorbed by the tar which has been
previously cooled, preferably by heat exchange
with incoming stock. The absorption of these 6
gases in the cooled pressure tar accomplishes at
least three important ‘results: (1) it reduces
oils or other carbonaceous materials are heated to the viscosity of the cooled tar so that the tar
about rI50" F. to 1250° F. at pressures ranging‘ may be readily handled and ?ltered at ordinary 10
room temperatures through simple canvas ?lter
10 from atmospheric to 1000 pounds per square inch,
and the reaction products are usually maintained elements in conventional closed ?lters; (2) it
,under pressure at é‘elevated temperatures for a. facilitates a sharp separation between valuable
suf?cient period of ltime to allow the conversion tarry and asphaltic compounds and lime, coke
of the oils or carbonaceous materials into light and ‘objectionable carbonaceous solids whereby 15
increased yields of by-products are obtained and
hydrocarbons such vas gasoline, heavy hydrocar
bons generally called “pressure tar,” and gases decreased yields of obnoxious, dimcultly dis-'
posable ‘residues are obtained; and (3) it pro
containing - appreciable ‘amounts of propane,
“vides a means for utilizing lime (which would
ethane, propylene, ethylene, etc. It is conven
be wasted) for sweetening the cracked
tional practice to use lime or equivalent materialv otherwise
gases and removing objectionable sulfur com 20
inv
the
cracking
stock
for
preventing
corrosion,
120 for preventing carbon depositiontor for other pounds therefrom, the sweetened gases being re
covered in the auto-tar distillation process. In
purposes. This lime or other solid material ac
cident to the above accomplishments are in
cumulates in the pressuretarv and it is conven
creased yields of valuable products, increased
tlonal practice to ?lter the pressure tar at temperatures of about‘ 350-500° F. (above the ?ash ?ltration rates, decreased’ labor and equipment
point of the oil) to remove the lime, together -“ requirements and decreased load- on the treat
units. Other advantagesi will be apparent
with coke particles or other solids. The high ing
from the following detailed description.
temperature is necessary because of the‘extreme
In the accompanying drawing which forms a
ly high viscosity of the tar at lower-temperatures.
part of ‘this speci?cation, l’. have shown a dia 30
However
high
temperature
pressure-tar
?lters
30
require the use of special ?lter elements which grarrm'iatic layout of my improved system. ‘ "
operations.
In'the production of cracked gasoline, mineral
The feed stock, which may be a petroleum gas
'
oil,
for example 3ll—35° A. P. I. midcontinent gas
An object of my invention is to provide a meth
od and means of ?ltering pressure tar at low oil or any other carbonaceous material which
commonly consist largely of‘ asbestos.
can be converted into lighter or more valuable
temperatures.
'
'
'
A further object of my invention is to utilize the I
pressure tar as an absorbing oil for removing
products by cracking or polymerization, is vin»
troduced through line it, re?ux coil l2 and ear
changer it to pipe still it in which it is heated '
propane and other normally gaseous hydrocar
bons from the gaseous products resulting from v to cracking orvpolymerization‘temperatures. The
hot miirture is then'introduced throughline it ‘
40
the cracking operation-from the so-called
to soaking ,drum it which may be. an enlarged
A further object is to provide an improved‘ reaction vessel'or which may be merely an elon
cruising system which includes .‘the recovery gated conduit of small cross sectional area con
to a hash chamber for separating tars
and utilizationoi propane and ‘other normally nected
from vapors and gases. The vapors and, gases
“high line gases” or even the so-called “wet gas."
gaseous hydrocarbons.v
'
.
Other objects will be apparent as the detailed
are conveyed by pipe ll to a lower or interme-'
charging'stock by subjecting it to elevated tem“
diate point of fractionatlng column 58, the “bot
toms" fromv this column being recycled through
line lg to the cracking or polymerization heater.
If. desired, I may introduce the feed stock through
paratus. The low-boilingproducts, including cy
it into the heater with the cycle stools in line 09.
description of my invention proceeds.
_
in practicing ,the invention I may crack car
bonaceous materials such as gas oil or other
peratures and pressures in any conventional ap- - ‘ valved line it directly into line ill and introduce
cle stock,‘ light and heavy naphtha, condensables
and fixed gases, are fractionated, the cycle stock
55 being returned to the heater oi the cracking unit,
Vaporized naphtha and normally gaseous. hy
drocarbons are moved from the top of column
l8 through line 2| and are passed through con 55.
2
2,108,636
denser 22 to separating chamber 23. The tem
perature and pressure conditions in the separat
ing chamber may vary throughout a relatively
wide range, it being designed to remove normally
liquid products such as pentane, hexane, etc.
from normally gaseous products suchas propane,
ethane, butane, propylene, ethylene, etc. The
liquids from separator 23 are introduced through
line 24 to a stabilizer 25 which is provided with
10 a suitable heater 28 and with re?ux means 21.
Gasoline is withdrawn through line 28 and the
propane and normally gaseous products removed
from'the gasoline are withdrawn through line
29 to storage tank 30 thence to lines 3|, or 32,‘
15 which will be hereinafter described.
- The dry gas from the top of separator 23 is
led through pipe 33 to a lower or intermediate
point of absorption tower 34 wherein it is
scrubbed by tar which has been withdrawn from
20 soaking drum I 6‘ through hot tar line 35, cooled
in cooler 36, and led to the top of the absorption
tower by pipe 31 which should be short and of
large cross sectional area.
Methane and unab
sorbed gases may be vented from the top of the
25 absorber through pipe 38 which may lead into
the conventional re?nery dry gas line or high
line. Likewise gas from the top of storage 30 may
be vented through pipe 33a and propane from
line 3| may be introduced into the tar scrubber
30 with gases from line 33. The absorber is prefer
ably operated under a pressure of from 250 to
400 pounds and at ordinary atmospheric tem
peratures of approximately 60° to 100° F. Under
these conditions ‘a suflicient amount of propane
35 is absorbed by the pressure tar to cause a strlkf
ing decrease in viscosity and to effect a thorough
washing of the lime particles. These lime parti
cles are thereby rendered accessible for chemical
action on the undesirable sulfur compounds
which are present in the gases and the propane
introduced through pipes 3| and 33 and the gases
which are introduced through these pipes are
,_ thereby‘ sweetened to a material extent. The
amount of liquefied gases which are absorbed
45 by the pressure tar is usually less than 10% of
the volume of the tar and under these condi
tions there is no appreciable phase separation of
asphaltic compounds from propane. .However,
the reduction of viscosity is so great that ?ltra
50 tion may be readily effected through ordinary
canvas ?lter leaves either in batch ?lters or in
continuous rotary ?lters. The lime, coke and
carbonaceous particles separate readily from the
diluted tar to'give a cake which may be easily
55 discharged and which may be disposed of much
more readily than hot ?lter cakes heretofore ob
tained. Thus it will be seen that I have elimi
nated the necessity of using asbestos ?lter ele
ments andwof operating at temperatures of from
60
400° to 500° F. and'at the same time I have made
it possible to obtain very rapid ?lter rates and
to obtain almost quantitative separation of valu
able by-products.
_v
p
The relatively cool diluted pressure tar may "
that suitable heat exchangers may be employed
to supply the heat necessary for removing the
propane, naphtha and cycle stock from the ?ash
drum residue which may be used as a fuel oil or
as a road oil. Flash drum 46 corresponds to the
conventional auto-tar plant.
Settled material from settler 42 may be with
drawn by pipe 41 and ?ltered material from filter
40 may be withdrawn through conduit 48, and
in each case the residue may be flashed in cham
ber v49 to recover propane and valuable oils
through line 50. Unevaporated liquids may be
drawn from flash drum 49 by line 49a. Fuel oil,
road oil or tar is withdrawn from ?ash drum 46
through pipe 5| and the propane, together with
naphtha vapors and heavier auto-tar distillates
are removed through pipe 52. Propane may be
passed by line 53 or compressed by pump 54
and then passed to condenser 55. Liquids are
collected in tank 56, gases being withdrawn
through vent 51 to a gas fuel line and sweetened
propane and heavier liquids being withdrawn
through line 58.
Instead of cooling the entire volume of pressure
tar before absorbing propane vapors, I may ?ash
the tar by introducing it through line 59 into
auto-tar still 60 which may be supplied with
steam heater 6| if the heat of the tar is not
sufficient to effect the desired vaporization. Auto
tar distillate may be removed through line 62, 30
condenser 63, receiver 64, etc., and the residue
may be passed by line 65 to line 35 or line 31.
While I have described in detail the preferred
embodiment of my invention, it should be'under
stood that I do not limit myself to the speci?c
arrangement hereinabove set forth or to any of
the details hereinabove described except as de
?ned by the following claims which should be
construed as broadly as the prior art will permit.
I claim:
40
1. In a process wherein hydrocarbon oil is sub
lected ‘to conversion conditions of temperature
and pressure to produce motor fuel, and a rela
tively viscous pressure tar which is characterized
by‘having asphalt in solution and by having sus 45
pended contaminating insoluble solid matter
therein which renders saidtar diiiicultto ?lterthe
improvement in refining said pressure tar to make
it suitable for fuel purposes which comprises cool
ing said tar, conducting said cooled tar into an 50
absorption chamber, conducting normally gaseous
hydrocarbons which are substantially free from
gasoline to said chamber, intimately contacting
said cooled tar and said normally gaseous hydro
carbons and dissolving not more than about one 55
liquid volume of said normally gaseous hydro
carbons in each ten liquid volumes of said tar,
thus decreasing the viscosity of said tar without
precipitating any substantial amount of asphalt
therefrom, separating undissolved gaseous hydro
carbons from the viscosity-reduced tar, passing
60
the said tar and dissolved normally gaseous hydrocarbons into a separating zone and separating
said contaminating insoluble solid matter from
be passed by line 39 to ?lter 40 or it may be - the said viscosity-reduced tar, and thereafter
- passed to linev 4| and settler 42 or it may be removing the dissolved gaseous , hydrocarbons 65.
passed'?rst to settler 42 and the decanted liq
from the tar.
uids passed through pipe 43 to the ?lter. Tar in
2. In a process wherein hydrocarbon oil is sub
line 39 may be further diluted with propane from jected'to conversion conditions of temperature
70 pipe 32.
and pressure to produce motor fuel, normally
The ?ltered or settled dilute pressure tar from gaseous hydrocarbons substantially free from
which all solid matters have been removed is in
gasoline, and a relatively viscous pressure tar
troduced by pipes 44 or 45 to ?ash drum 46, it which is characterized by having asphalt in solu-,'
being understood that a suitable collector and. tion and by having suspended contaminating in-I
75 feed pump maybe interposed in this line and
soluble solid matter therein which renders said 75
2,108,636
tar dimcult to ?lter, the improvement in refining
3
which is characterized by having asphalt in solu
tion and by having suspended contaminating iii-.
, said pressure tar to make it suitable ‘for fuel pur
poses whichcomprises cooling said tar, conduct- ' soluble solid matter therein which renders said
said chamber, intimately contacting said cooled
tar dif?cult to ?lter, the improvement .in re?ning
said pressure tar to make it suitable for fuel pur
poses which comprises cooling said tar, conducts
tar and said normally gaseous Hydrocarbons and
in'g said cooled tar-into an absorption chamber, a
ing said cooled tar into an absorption chamber,
conducting said normally gaseous hydrocarbons to
‘dissolving about one liquid volume of said nor
mally gaseous hydrocarbons in each ten liquid
~10 volumes of said tar, thus decreasing the viscosity
conducting said normally gaseous hydrocarbons
to said chamber, intimately contacting said cooled
tar and said normally gaseous hydrocarbons and
of said tar without precipitating any substantial
dissolving about one liquid volume of said normal- -
amount of asphalt ‘therefrom, separatingundis
solved gaseous hydrocarbons from the viscosity
1y gaseous hydrocarbons in each ten liquid vol
umes of said tar, thus decreasing the viscosity of
reduced tar, passing the said tar and dissolved
said tar without precipitating any substantial
15 normally gaseous hydrocarbons into a separat
amount of asphalt therefrom, separating undis
ing zone and separating said contaminating in
soluble solid matter from the said viscosity
reduced tar, and thereafter removing the .dis
solved gaseous hydrocarbons from the tar.
3. The process of claim 2 which comprises sub
20
solved gaseous hydrocarbons from the viscosity
reduced tar, passing the said tar and dissolved
normally gaseous hydrocarbons into a separating
jecting said pressure tar to a ?ash distillation
and removing a distillate fraction therefrom prior
to the steps of cooling and separating said tar.
4. In a process wherein hydrocarbon oil is sub
25 jected to conversion conditions of temperature
and pressure to produce motor fuel, normally
gaseous hydrocarbons substantially free from
gasoline,'and a relatively ‘viscous Pressure tar
zone and ?ltering the said viscosity-reduced ta'r.
vto remove contaminating insoluble solid inatter
therefrom without removing any substantial
amount of asphalt from the tar, and thereafter
removing the dissolved gaseous hydrocarbons from"
the tar whereby the-tar is converted into afuel
relatively rich .in asphalt and relatively free from
suspended insoluble, and non-combustible matter. 2
HAROLD V'. ATWELL.
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