close

Вход

Забыли?

вход по аккаунту

?

Патент USA US3094497

код для вставки
June 18, 1963
R. M. BUTLER ETAL
3,094,431
HYDROFINING PROCESS WITH TEMPERATURE CONTROL
Filed Sept’. 9, 1960
I
2 Sheets-Sheet 1
FEED
|Q
{7H
‘
l2
1
‘3L,
xpREACTOR
PREHEAT
FURNACE
TAIL
2|
20
0“
34
,
$
,A A A
\/\/\ —>J
|4L maul/‘GAS
v v v’
%5
l5
SEPARATORé g__.
I?
‘
|31J
'L- 33
PREHEAT
ABSORBER
23
STRIPPER L’
%
25
FURNACE
A‘ A A r
‘
v v v
22
”
/
26
124
q 27
HYDROFORMER
REACTOR
SYSTEM
I9
32
COMPRESSOR
3|
128
F lG.-l
29
PRODUCT
SEPARATOR
Roger M. Butler
John A Bichord
By
-
3o
l
2
"
Inventors
SCSQ’WPatenT Attorney
June 18, 1963
R. M. BUTLER EI‘AL
3,094,481
HYDROFINING PROCESS WITH TEMPERATURE CONTROL
Filed Sept. 9, 1960
2 Sheets-Sheet 2
TYPICAL RELATIONSHIP OF VARIABLES
‘20° F
____ LINES OF CONSTANT FEED
TO RECYCLE RATIO
"50 ‘T
__ LINES OF CONSTANT AT’F.
\
uoo
IN THE REACTOR BED
—
\
I050 —
\
-
I000 -
RTE°MCPYFAL.URE,
lzl
A \
95o<>_25 so
15 I00 O EAT
90o ‘
e50
800
750
700
65o1|||||||.||
o
20
40
so
80
PERCENT OLEFINS m FRESH FEED
I00
Roger M. Butler
Inventors
By K1 . 32;, a 2,.
Patent Attorney
John A. Bichurd
2‘
:
United States Patent 0
3,094,481
1
Patented June 18, 1963
1
2
but below the temperature at which substantial deposits
3 094 481
are formed.
HYDROFINING PROéESS’ WITH TEMPERATURE
It is the object of this invention to provide a simple,
e?icient method whereby naphtha feedstocks can be
CONTROL
‘Roger M. Butler, Sarnia, Ontario, and John A. Bichard,
Point Edward’ Ontario’ Canada,‘ assignors to Essa Re_ 5 heatelcll ‘tio temperatures above about 500 F. for charging
search and Engineering Company, a corporation of
O a _Y mn'eatmg ul'llt-
Delaware
'
_
_
_
It is also an ‘object of this invention to provide a
Filed Sept. 9, 1960, SenNo. 54,867
method for heating naphtha feedstoclcs, along with by
5 Claims. (Cl. 208-255)
drogen-containing treat gas to temperatures above 500°
‘
10 F. while avoiding the formation of solid deposits on heat
This invention pertains to a hydrocarbon conversion
exchanger or furnace tubes,
process and more particularly to an improved Process for
These and other objects will appear more clearly from
the ‘catalytic conversion of petroleum naphthas in the
the detailed Speci?cation and claims‘ which fQHOW_
presence of added hydrogen.
It has now been found that fouling of heat exchanger
It is known that the quality of virgin or straight run 15 or preheat furnace tubes can be avoided by mixing the
as well as cracked or thermally reformed naphthas can
relatively cold naphtha feed with a recycled stream of
be improved by reacting such feedstocks with added hy-
heated hydro?ned naphtha product and hydrogen. It has
drogen .at elevated temperatures and superatmospheric
been found that the h'ydro?ned naphtha can be heated to
pressures in the presence of hydrogenation-dehydrogenatemperatures of about 900-1000a F. at pressures of 200
tion catalysts. Such operations are referred to as hydro~ 20 450 p.-s.i.g. and at hydrogen partial pressures of about
forming, hydro?ning, hydrocracking, hydrodesulfurizing
‘100-350 p.s.i.g. with little or no thermal cracking and
and the like. - The purpose and result of these treatments are to eifect a substantial reduction of the sulfur
without the formation of deposits upon the preheater
tubes that are formed when the fresh feed is heated to
‘content, to saturate certain highly unsaturated gum-formvaporization in such tubes. While this procedure re
ing constituents and to saturate at least a part of the 25 quires the recycle of hydro?ned product and thus sub
‘ole?ns present, to improve the color and odor of the
stantially increases the total throughput of the reactor,
product, to produce aromatic hydrocarbons vby the catathis can be taken care of by increasing the size of the
lytic dehydrogenation of naphthenic and cyclic ‘Ole?n
reactor, by increasing the space velocity or by a com~
components.
bination of the two. In existing plants the increase in
In most of these processes the feed is supplied alone 30 throughput will ordinarily ‘be effected by increasing the
or in admixture with the added hydrogen to the catalystspace velocity since rather large changes in space velocity
containing reaction zone at temperatures in the range of
can be made without any signi?cant change in product
from about 300° F. to 950° F. It is the general practice
quality. In some instances dilution of the fresh feed
to obtain such temperatures by passing the feed through
with good quality recycle could improve the overall
a heat exchanger provided with ‘a large number of tubes 35 quality of the feed to such an extent that running this
of small diameter. It has been found, however, that as
high quality feed at the necessary higher space velocity
temperatures about 300° ‘F. are reached, many naphtha
would produce a better quality product than could be
feeds tend to form deposits on the walls of the heat exobtained by running the fresh feed in a once-through
changer and thus decrease the e?iciency of the unit. In
operation at low space velocity.
some cases these deposits have even plugged the heat 40 ' It has been disclosed in Pichler U.S. Patent 2,910,433
exchanger tubes. The main constituent of these deposits
is iron and iron sul?de which is bound extremely tightly
to the inside of the preheat exchanger tubes 'by a hydro‘carbon binder. The following table summarizes the
analysis of typical deposits from a naphtha hydro?ner 45
‘that cracked stocks contain appreciable proportions of di
ole?ns and other gum-forming compounds which are con
verted to gums which deposit on heat exchanger surfaces
when the oils are heated to temperatures in excess ‘of
about 500° F. The Pichler patent proposes to overcome
‘feed heat exchanger.
‘this problem by preheating the charge stocks to such
Elemental Analysis 1
Spectrophotometric Analysis 1
Deposit Source
-
Percent Percent Percent Percent Major
0
H
N
S
Minor
Percent
Large Trace
Small Trace
Ash
(Dry)
(Oxide)
ExchangeInletBonneL.
ReamcdFromTubes..__
14.66
8.46
0.90
0.52
0.11
19
Fe_.__ Si _______ __ M,Mn,Gi_~..__ Mg,Pb,Cu,Zn_____
Fe___- Si,Mn____ M0,Or,N1_-_- Pb, 04, Sn, Mg ____ __
70.1
78.2
1 Atomic ratio of hydrogen to carbon in bonnet deposit is 0.74; atomic ratio of hydrogen to carbon in tubing deposit is 0.74.
2 Major: >10%; Minor: 1—10%; Large trace: 0.1—1%; Small trace: <0.1‘7
It should further be noted that the inlet =bonnet which 60 moderate temperatures, generally of the order of 500°
normally operates at less than about 300° F. has about
F., at which no gum deposits take place and to make up
15-16 wt. percent of the hydrocarbon ‘binder. The de
the heat requirements of the hydrogenation system by
posit reamed from further ‘down the tubes where tem
higher preheats of the treated and stabilized recycle oil.
peratures ‘as high as 900° F. are reached has only about
It should be noted that this patent was concerned with
_9 wt. percent of the binder.
‘
65 the treatment of oils boiling essentially above the gasoline
It has been proposed to overcome this difficulty in
range and in an operation wherein the oil remains in
various ways such as by distillation or by passing an inert
liquid phase so that there is continuous washing of the
gas through the feedstock to strip oif the free oxygen
heat exchanger surfaces and the catalyst bed with a re
content, by 'blanketing the feedstock to minimize con
cycle stream of the heated oil. In contrast to the Pichler
tact with air and by giving the feedstock a pretreatment 70 teachings the naphtha feedstoclcs cannot be preheated to
with hydrogen in contact with a hydrogenation-dehydro
the moderate temperatures of about 500° F. without seri
genation catalyst at temperatures above about 300° F.
ously ‘fouling the heat exchanger surfaces and more impor
3,094,481
4
tantly the preheat applied is sufficient to effect vapori
an elevated temperature in the event that the fresh feed
zation and, accordingly, there is no washing of heat ex
changer and catalyst surfaces with liquid phase oil.
is obtained directly from a fractionator, the resultant
mixture will be at the desired temperature for introduc
The feedstocks that can be treated advantageously by
the process of the present invention are those hydrocar
bons which boil within the gasoline boiling range, for
tion into the hydro?ning reactor. Normally the hydro
?ned liquid product, in admixture with the treat gas, can
be heated to 900-1000° F. for recycling in accordance
example, straight-run naphtha, coker naphtha, thermally
with this invention with very little if any thermal crack
or catalytically cracked naphthas, and steam cracked
ing provided that the pipe layout and ?ow are suitably
engineered. For example, at a design velocity of 40-60
from about 150 to 450° F., but may be narrow boiling 10 ftJsec. for the recycle stream, the stream plus hydrogen
naphthas. Ordinarily the fee-dstocks boil in the range of
cuts from within this range.
The process of this inven
can be conveyed up to about 4500 it. at 900° F. or up
tion is particularly adapted for the treatment of cracked
to about 330 it. at 1000° F. while holding cracking to less
or coker naphthas especially those which tend to form
than about 1%.
deposits when heated to vaporization temperatures in heat
Processing of stocks high in ole?n content would ordi
exchangers or preheat furnace tubes.
15 narily result in severe hydro?ner preheat exchanger foul
In carrying out the process in accordance with the pres
ing, rapid deactivation of the catalyst and a temperature
ent invention, any conventional hydro?ning or hydro
rise, approximately ?ve times the bromine number of the
genation-dehydrogenation type catalyst may be used.
feed. A recycle rate of about 1:1 to fresh feed, and a
Such catalysts include various oxides and sul?des of metals
recycle temperature of about 950° F. would provide su?i
of groups VI and VII such as molybdenum, tungsten, 20 cient heat to maintain a reactor inlet temperature of about
vanadium, chromium and the like, or mixtures such as
600° F. and a temperature rise within the reactor of about
nickel-tungsten sul?de and cobalt molybdate, or mixtures
50° F. with 25% ole?ns in the original feed. The lower
of cobalt oxide and molybdenum oxide preferably depos
the ole?n content of the fresh feed, the higher the recycle
ited on a support or carrier material such as activated
rate must be.
For example, a feed with zero percent
alumina, silica gel or activated alumina containing small 25 ole?ns would require a recycle (at 950° F.) to fresh feed
amounts (2 to 10 wt. percent) silica. The preferred cata
lyst is one containing vfrom about 5 to about 25 wt. per
cent of cobalt oxide and molybdenum oxide with the
ratio of about 13:1 for a 650° F. operation.
Reference is made to the accompanying drawings
wherein FIGURE "1 is a diagrammatic ?ow plan of one
ratio of the former to the latter in the range of from
embodiment of the present invention and FIGURE 2 illus
about 1 to 5 to about 5 to 1, supported upon an adsorp 30 :trates typical relationship of variables when operating in
tive or activated alumina containing about 25 wt. percent
accordance with this invention.
of silica. Such catalysts are prepared by ?rst forming
In the ?ow plan of FIGURE 1, feedstock such as a
adsorptive alumina, containing silica if desired, in any
naphtha fraction boiling between about 100 and 350° F.
suitable or known way and then compositing molybdenum
is supplied at system pressure through inlet line 10 at
oxide and cobalt oxide therewith. The molybdenum 35 ambient temperatures. Recycle product and hydrogen
oxide can, for example, be added as a slurry or it may
containing treat gas is supplied through line 11 in su?‘icient
be applied as a solution of ammonium molybdate. The
amount and temperature that upon mixing with the fresh
feed supplied through line '10, the resultant mixture will
be at the desired temperature for charging through inlet
cobalt oxide is conveniently added as a salt such as cobalt
nitrate or acetate, salts which are readily decomposed to
cobalt oxide and volatile materials. The catalyst may, 40 line '12 to the reactor 13. The reactor is charged with a
if desired, be given an activation treatment prior to use
suitable hydrogenation-dehydrogenation catalyst, prefer
in the hydro?ner by reacting the same with a suitable
ably a cobalt oxide-molybdenum oxide on alumina cata
sul?ding agent such as a sulfur-containing feedstock, hy
lyst as described above. The reaction mixture passes
drogen sul?de, carbon disul?de, and the like. The
through the reactor '13 at a suitable rate to obtain the
amount of sulfur added for preactivation of the catalyst 45 desired treatment of the feedstock, principally hydrogena
may vary from about 100% up to about 1500% of the
tion and hydrodesulfurizat-ion. The reaction products are
stoichiometric quantity necessary to convert the cobalt
withdrawn from the reactor via line 14, cooled and dis
oxide and molybdenum oxide to the corresponding sul
charged into separator 15 wherein the normally liquid
?des.
products are separated from the normally gaseous ma
The hydro?ning reaction conditions vary somewhat, 50 terials, ‘the latter being removed as tail gas from the sys
depending upon the nature of the feedstock, the character
tem via line v16. The normally liquid products are with
and quantity of the impurity or contaminant to be re
drawn from separator 15 via line .17 and discharged into
moved, and the degree of improvement desired. In gen- '
the upper part of absorber stripper column .18. Hydro
er-al, the reaction temperature is about 500-750° 1F., pref- ,
gen, or hydrogen-rich gas, is supplied through line ‘19 to
erably 575-650° F, reaction pressure 50-500 p.s.i.g., 55 the bottom of the column .18 in order to contact the hydro
preferably 200-250 p.s.i.g., and ‘feed rate 1-20 v./v./hr.,
?ned liquid product countercurrently, thereby shipping
preferably about 2-10 v./ v./ hr. The hydrogen-rich treat ‘
off hydrogen sul?de, ammonia, and the like from the nor-'
gas which should contain at least ‘about 25 volume per
mally liquid products. The gases pass overhead from
cent hydrogen is supplied to the hydroiining reaction zone ' i
column 18 and su?icient gas is withdrawn through line 20
at the rate of about 50-3000 s.c.i./b., usually about 500 60 to serve as treat gas in the hydro?ner while the excess
s.c.f./b., and the hydrogen consumption in the hydro
?ning operation is about 1 to 600 s.c.'f./b., usually about
30 s.c.'f./b. '
gas is discharged from the system through line 21. When
' hydroformer tail gas is used as the stripping gas in column
V‘
In view of the exothermic nature of some of the reac
tions that occur in hydro?ning, the temperature of the 65
18, hydrocarbons contained therein, particularly C3-C5
hydrocarbons, are absorbed in the liquid hydro?ned
product.
>
> The stripped, hydro?ned liquid product containing hy
drocarbons absorbed from the stripping gas are withdrawn
the reaction mixture up to the desired temperature level.
from column 18 through line 22. Part of this liquid prod
In accordance with the present invention a portion of the
net is discharged into line 26, mixed with hydrogen-rich
hydro?ned liquid product, preferably in admixture with 70 recycle gas supplied through line 24, and passed ‘through
the hydrogen-rich treat gas which may be recycle or fresh
preheat furnace 25 where the mixture is heated to suitable
or a mixture of recycled and fresh hydrogen-rich gas is
temperatures for charging via line 26 to the hydroformer
feed charged to the reaction zone is adjusted so that the
temperature rise that occurs in the reaction zone will bring
heated in a preheat furnace to a temperature su?iciently
above the hydro?ning reactor temperature that, upon mix
reaction system 27. it will be understood that this show‘
ing is purely diagrammatic and that this system may be
ture with ‘the fresh feed at ambient temperature or at 75 a conventional fluid or moving bed hydroforming systeni
3,094,481
5
6
charged ‘with a molybdenum oxide or platinum-alumina
ture may be charged directly to the hydrogenating step
without further heating.
2. A method for hydro?ning naphtha feedstocks which
catalyst, or it may be a ?xed bed system preferably
charged with a platinum-alumina catalyst which may be
operated nonregeneratively, semiregeneratively, or regen
tend to form deposits upon heat transfer surfaces when
eratively, all as well known in the art.
heated to temperatures above about 300° F. which com
The hydroformer reaction products are discharged from
the hydroformer reactorsystem through line 28, cooled and
passed into product separator 29 wherein the normally
liquid products are separated from the normally gaseous
products. The liquid products are discharged from sep 10
prises treating the feedstocks at temperatures of about
500-750‘7 F., at pressures of about 50-500 p.s.i.g. in the
presence of about 5 0-3000 s.c.f./ b. of hydrogen-rich treat
arator 29 through line 30 to suitable product blending or
storage.
gas and in contact with an active hydrogenation catalyst,
separating the hydrogenated liquid product from the ac
companying gases, heating a portion of the hydrogenated
The normally gaseous products, containing
liquid product to a temperature well above the tempera
ture in the hydrogenation reaction step, mixing the hot
hydrogenated product with naphtha feed at a temperature
from separator 29 via line 31, passed to compressor 32
and thence recycled via line 24 to the hydroformer reactor 15 substantially below 300° F. in su?icient amount that the
resultant mixture can be charged directly to the hydro
system or passed through line 19 to the absorber stripper
about 60-90% or more of hydrogen are taken overhead
genation reaction step without further heating.
18 as described above.
3. A method for hydro?ning naphtha feedstocks which
In accordance with this invention, a portion of the hy
tend to form deposits upon heat transfer surfaces when
dro?ned liquid product is discharged from line 22 into
line 3-3 for recycle to the hydro?ner. The hydro?ned 20 heated to temperatures above about 300° F. which com~
prises treating the feedstocks at temperatures of about
liquid product is mixed with the hydrogen-rich treat gas
500-750° F., at pressures of about 50-500 p.s.i.g. in the
supplied via line 20 and the mixture is passed via line 34
presence ‘of about 50-3000 s.c.f./b. of hydrogen-rich treat
into preheat furnace 35. Because of the improved sta
gas and in contact with an active hydrogenation catalyst,
bility of the hydro?ned liquid product, it may be heated
to temperatures of about 900-1000° F. in the coils in 25 separating the hydrogenated liquid product from the ac
companying gases, heating a portion of the hydrogenated
preheat furnace '35 without forming any appreciable de
liquid product to a temperature of about 900-l000° F.,
posits upon the coils. The preheated mixture of hydro
mixing the hot hydrogenated product with naphtha feed
?ned liquid and hydrogen-rich treat gas is then passed
at a temperature substantially below 300° F. in su?icient
from preheat furnace 35 through line ‘11 for intermixture
with the fresh feed supplied through line 10. Ordinarily 30 amount that the resultant mixture can be charged direct
ly to the hydrogenation reaction step without further
the fresh feed to recycle ratio will be selected depending
heating.
on the ole?n content of the fresh feed, the temperature
4. A method for hydro?ning naphtha feedstocks which
rise in the reactor, the temperature of operation, and the
tend to form deposits upon heat transfer surfaces when
temperature of the recycle stream as illustrated by the ex
ample in FIGURE 2. The relationship of these variables 35 heated to temperatures above about 300° F. which com
prises treating the feedstocks at temperatures of about
shown in FIGURE 2 is for a typical operation at about
500-750° F., at pressures of about 50-500 p.s.i.g. in the
355 p.s.i.g. 650° F. average reactor temperature, .1160
presence of about 50-3000 s.c.f./b. of hydrogen-rich treat
set. recycle gas (85 mol percent H2) per barrel of fresh
feed which is a 165/320° F. VT naphtha at 275° F. The
gas and in contact with a cobalt oxide-molybdenum oxide
of embodiments of the present invention. It will be un
derstood that numerous variations thereof are still within
the scope of the present invention.
What is claimed is:
alumina hydrogenation catalyst, separating the hydro
genated liquid product from the accompanying gases,
principal variables are the percent ole?ns in the fresh feed 40 alumina hydrogenation catalyst, separating the hydro
genated liquid product from the accompanying gases,
and the temperature of the recycle stream.
heating a portion of the hydrogenated liquid product to
Working examples of this invention can be readily
a temperature well above the temperature in the hydro
deduced from the correlation of variables shown in the
genation reaction step, mixing the hot hydrogenated prod
attached FIGURE 2, for example:
At the aforesaid conditions, i.e. 355 p.s.i.g., 650° F. 45 uct with naphtha feed at a temperature substantially be
low 300° F. in su?icient amount that the resultant mix
average reactor temperature, 1160 s.c.f. recycle gas rate,
ture can be charged directly to the hydrogenation re
and 165/ 320° F. VT naphtha feed at 275° F., and with
action step without further heating.
(1) 15%ole?ns in the feed,
5. A method for hydro?ning naphtha feedstocks which
(2) 50° F. temperature rise in the reactor, i.e. 625° F.
50 tend to form deposits upon heat transfer surfaces when
inlet temperature and 675° F. outlet temperature,
heated to temperatures above about 300° F. which com
(3) 975° F. temperature of the recycle stream, i.e. hy
prises treating the feedstocks at temperatures of about
dro?ned product plus hydrogen.
500-750° F., at pressures of about 50-500 p.s.i.g. in the
Then a fresh feed to recycle ratio of 1:14 would be
presence of about 50-3000 -s.c.f./b. of hydrogen-rich treat
used. This corresponds to point A in FIGURE 2.
The foregoing description contains a limited number 55 gas and in contact with a cobalt oxide-molybdenum oxide
1. A method for catalytically hydrogenating naphtha
00
feedstocks which tend to form deposits upon heat trans
fer surfaces when heated to temperatures above about
300° F. which comprises hydrogenating the feed at ele
vated temperature and pressure to improve the stability
of the naphtha, separating the hydrogenated liquid prod 65
uct from the accompanying gases, preheating a portion
of the hydrogenated liquid product to a temperature of
heating ‘a portion of the hydrogenated liquid product to
a temperature of about 900-1000° F., mixing the hot
hydrogenated product with naphtha feed at a temperature
substantially below 300° F. in su?’icient amount that the
resultant mixture can be charged directly to the hydro—
genation reaction step without further heating.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,866,750
Mosesman ___________ __ Dec. 30, ‘1958
about 900-1000° F., mixing the preheated hydrogenated
2,901,417
Cook et al ____________ __Aug. 25, 1959
product with naphtha feed at a temperature substantially
below 300° F. in su?icient amount that the resultant mix 70
2,910,433
2,927,891
Pi‘chler ______________ __ Oct. 27, 1959
Weikart ______________ __ Mar. 8, 1960
Документ
Категория
Без категории
Просмотров
2
Размер файла
632 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа