USSR PROCEDURES FOR THE AROMATIZATION OF PETROLEUM (PYROLYSIS)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000700090310-6
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 12
• Document Creation Date: December 22, 2016
• Document Release Date: August 11, 2011
• Sequence Number: 310
• Publication Date: November 12, 1952
• Content Type: REPORT

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vT' , u CIASSlF1CATID
~~ CENTRAL ILIGENCE Cjr REPORT
1y INFORMATION FROM
FOREIGN DOCUMENTS OR RADIO BROADCASTS CD NO.
COUNTRY USSR
DATE OF
SUBJECT Scientific - Chemistry, Petroleum INFORMATION 1946
HOW
PUBLISHED Book
DATE DIST. !.9. Nov 1952
WHERE -C?ITRI
PUBLISHED Moscow/Lenin d C[,"X;:' ~0. OF PAGES 12
PUBLISHED 1948
Pererabotka Nefti (Pat-rni.um aion) Gosto
PP 190-2002 7 Ptekhizdat, 1948,
USSR PRneFnT p FORT AROMATI2ATION OF PETROLEUM PYROLYSIS
Captions and tables Ire appended.
Definition of Pyrolysis; Chemistry of Pero vsie
The first Pyrolysis Plant in Russia was built at the end of the last
century, it was intended for the production of artificial gas from petroleum
and for that reason was called a petroleum gas plant. This name has been re-
tained up to the present for pyrolysis plants, although their purpose had
changed as early as the beginning of World War I. At that time, large
quantities of toluene were required for the production of smokeless powder,
so that petroleum gas plants were adapted to the production of aromatic hydro-
carbons, particularly toluene. Besides toluene, benzene, xylene, and
naphthalene are obtained in pyrolysis. Aromatic hydrocarbons also have other
applications in addition to the production of explosives: they are used in
the chemical, dyestuff, pharmaceutical, and other industries.
Pyrolysis of kerosene with the aid of comparatively simple equipment
yields 10-12% of aromatic hydrocarbons. Pyrolysis is also referred to as
aromatization of petroleum.
Pyrolysis is a cracking process which is carried out at very high
atures (of the order 670-7200 C) and ordi temper-
nary Iatmoapheric7 pressure.
STATE
ARMY
- 1 -
CONFIDENTIAI,_.
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The molecules of petroleum products, on being heated to 670-7200 C, split
into simple, small particles which, under the conditions of the pyrolysis process,
have the property of condensing under formation of aromatic hydrocarbons. Thus,
the formation of benzene may be regarded as being due to the polymerization of
three molecules of acetylene: 3 C2H2 C6H6.
Pyrolysis is a complex process in which reactions of decomposition and
condensation are comprised. The sequence of these reactions is approximately
as follows. First, paraffinic hydrocarbons are transformed into olefins with
one double bond. These olefins in turn split under formation of olefins having
two double bonds, i.e., diolefins. The diolefins either condense under formation
of aromatic hydrocarbons or else are transformed first into naphthenes and then
into aromatics by dehydrogenation. The reactions in question can be represented
by the following scheme:
Paraffins -, olefins -. diolfsfins ---. aromatics
naphthenes -* aromatics
By means of pyrolysis, any petroleum product, beginning with gas and
ending with tar, can be converted into aromatic hydrocarbons. However, the
temperature conditions required for different types of crude material are
different, and the vi.elds of aromatic hydrocarbons are also different, depending
on the crude material. Light hydrocarbons (e.g., gasoline) give a high yield
of carbon black, while h::avy hydrooarbo s such as mazut and tar yield large
quantities of coke. The best crude material for pyrolysis are the middle
fractions of petroleum, i.e., kerosene and gas oil. The chemical composition
of the crude material is also of considerable importance: naphthenes are more
easily converted into aromatics than any other hydrocarbons.
From the practical standpoint, kerosene and the so-called pyrolysis crude
material (i.e., kerosene -- gas oil fractions of petroleum) are used as initial
materials for conversion by pyrolysis at petroleum plants.
Installations for Pyro3yele and Their Operation
The oldest pyrolyzing jiterally, "pyrogenizing"7 installation is a furnace
equipped with cast-iron stills These stills jiterally,
"retorts"7 consist of three batteries containing three horizonal sections each.
The diameter of the stills is 30 cm and the length of each section, one meter.
The capacity of a tlirni:e of this type is 1-1.5 tons of crude material Ior
*yro3ysis7 a day. Luring operation, a temperature of 350-1100? C mist be main-
tained in the upper horizontal section of the still a temperature of 500? C
in the middle section, and a temperature of 650-7006 C in the bottom section.
From the still, the products pyrolysis enter hydraulic separators (3),
which are horizonal cylinders having a partition in the middle that does not
quite reach the bottom of the cylinder. The cylinders are filled with liquid
to approximately half their height. Gas and vapors enter the hydraulic separator
through a tube which also does not quite reach the bottom of the cylinder: its
opening is several centimeters above the bottom. Gas and vapor bubble through
the liquid and leave the hydraulic separator through an outlet at its top. The
heaviest fraction of pyrolysis products condenses in the separator and flows by
gravity into a receptacle. The product which collects in this receptacle is
known as hydraulic tar. The vapor passes through a gas line into a series of
air-cooled and water-cooled condensers.
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The air-cooled condensers (4) are vertical, hollow cylinders. In these
cylinders, a liquid known as condenser tar is condensed out of the pyrolysis
air- producolts. ed condor era, exlcept that=coolers are identical in design with the
Alternatively, vertical tube condensers cooled by water may spraying used.
water. ing is effected The gas leaving the condensers still contains a certain quantity of aromatic
hydrocarbons. These aromatic hydrocarbons are extracted by washing the gas with
wash oil. This is done in vertical cylindrical scrubbers W. To increase the
surface of contact between ail and gas, the scrubber columns are equipped with
wooden gratings. The wash all, on being sprayed from the top of the scrubbers,
cascades along the gratings and extracts the aromatic hydrocarbons from the
gas which is introduced into the scrubbers from the bottom. Wash oil saturated
with aromatics (scrubber oil) leaves the scrubbers at the bottom, while the gas
freed of aromatics (10) is conducted into a gas holder, from which it is supplied
to consumers.
Furnaces equipped with cast-iron stills have many drawbacks such as low
efficiency, high expenditure of fuel reaching 25%_35% with reference to the
crude material processed, and a short period of service (4-5 months). For that
reason, furnaces of this type have been replaced by furnaces with chamotte
stills.
The furnace with chamotte stills is a circular structure built of refractory
bricks, inside of wh_ail Eight vertical chamotte stills (A) are disposed (see
Figure 105). The hills consist of four sections having a diameter of 30 cm
and a length of 3 m per section. The bottom section
pot
having an outlet which coanecte it with the hydraulics separator r impinges
tor on (a c).
epaa (C).
The furnace is heated by a spray burner. The combustion products rise
inside the furnace, and in the process of rising, they heat the stills from the
inside. The combustion products then pass over the wall and heat the stills
from the other side. Finally, they pass into the flue and from there into the
chimney. The crude material (kerosene or gas oil) is fed into the stills by
gravity from an elevated tank. The crude material enters drop by drop at a
predetermined speed into the individual stills.
To bring about better distribution, iron chains with disks are suspended
inside the stills. The lizuid evaporates in the upper part of the still and is
subjected to pyrolysis in the middle and lower sections of the still at a temper-
ature of 650-7000 C. The products of pyrolysis pass from the still into the
hydraulic separator. The rest of the flow sheet is the same as in the case of
the installation already described.
The temperature of the furnace is controlled by measuring the temperature
of the furnace space with an optical pyrometer. The temperature in this space
must be maintained at a level of 1,130-1,1500 C, which corresponds to a temper-
ature of 700-7200 C in the stills. The operator must make sure that every still
is heated uniformly by car-ying out observation through the combustion chamber
and using the upper and lower peepholes of the furnace for that purpose. If
leakage Is discovered in one of the stills, feeding of crude material into that
still is interrupted and the still is coked up, i.e., any cracks which might
have formed are sealed with coke. Normally, the run of a still continues fo:
about 3 days, after which the -oks must be cleaned out.
Occasionally, stills become clogged with coke before expiration of the
normal period of a run. The fact that clogging has occurred can be seen from
the following indications: (a) the crude material spills over the edge of the
still; and (b) the still beings "to gas." In such cases, the still must be
cleaned. To do this, the top cover of the still is lifted, the iron chain with
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disks is withdrawn, the bottom cover of the still is removed to produce a draft,
and a burning torch is set to the still. After all the gas has burned out,
still maintenance workers clean out the coke from the still. If there is a
large quantity of coke in the still, the coke must not only be scraped out,
but also burned out. In some cases, the process of burning it out may take
as long as 24 hr. After cleaning has been completed, both covers are replaced,
and operation of the still is resumed.
The hyraulic separators are designed ir. such a manner that removal of coke
and soot can be carried out once a day without interrupting operation.
The capacity of the t.ustallation is 3-3.5 tons a day. This type of
installation has Severn: drawbacks,i.e., low efficiency, high expenditure of
power, and complexity of the service required.
Further significtint progress in the pyrolysis process was achieved by the
use of generator,,.
A generator +see Figure 106, p 193) consists of two cylindrical, towers
6 m high and having a 9laa_t r of 2 m, which are constructed of refractory
brick (brick checkerwork7 in such a manner that they resemble a cage. The
towers are covered with shells made of iron sheeting. The two towers are
interconnected at the bot`..:m by means of a metal pipe, which is also lined with
refractory brick. At the 'op of the first tower, there is an inlet for crude
material (2) with an appliance for dis{,ereing it. In the upper part of this
tower (on the side) there is a nozzle (1) for spraying in fuel (a spray burner)
and an inlet for air (3'. The second tower has a supplementary spray burner
at the bottom and an outlet to the smokestack on top (4). On the side of the
second tower, there is an outlet +5) into the hydraulic separator (6). After
leaving the hydraulic separator, the pyrolysis products are conducted through
the cooling and condensing system in the same manner as described above.
The generator works intermittently: besting is carried out for 30 min and
after ;:pis, pyrolysis for 30 min. The checkerwork of the generator is heated
by direct contact with circulating combustion products which are yielded by the
fuel that is consumed in the burner. The combustion gases move from the top to
the bottom in the first tower and from the bottom to the top in the second
tower, finally coming out through the smokestack. When the generator has been
heated to 735-7500 C. (the temperature is measured by means of a thermocouple),
the burner is shut off, t. vent to the smokestacks is also shut off, and the
slide valve which establishes communication between the generator and the
hydraulic separator is opened, After this, the process of pyrolysis is started,
which is referred to as gasification -- feeding in the crude material and
spraying it onto the heated refractory bricks at a rate of 30 kg/min.
The rate of feeaing of crude material into the generator is regulated by
an appliance called the "talarce." The crude material evaporates in the first
tower and is then subjected to splitting into small molecules. In the second
tower, formation of aromatic hydrocarbons from these molecules takes place.
Simultaneously with the formation of aromatic hydrocarbons, carbon black and
coke are formed, and these are deposited on the brick cherkerwork of the gener-
ator. There is also formation of gaseous hydrocarbons.
From the second tower, the pyrolysis products enter the hydraulic separator
and from there go into t:.e condensing equipment (this part of the flow sheet
is exactly the same as in the installations described above). The pipe which
connects the generator with the hydraulic separator is equipped with a heat
exchanger utilizing the heat of the pyrolysis products.
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Within 3(' min aft,.: the ..ginning of gasification, the temperature in the
towers drops to 50-600 r
a t::r vnirh iyrclysis proceeds less energetically.
To heat the generator again to the necessary temperature, the feeding in
of crude material Is interrupted, the outlet to the smokestack is closed, and,
with the aid of a FeserPil blver, air is blown in to remove vapors of petroleum
products and to burn out soot and coke. At the same time-, the spray burner is
ignited. The blowicg out and poking of the generator are continued for the
same length of tirn es the gasification, namely, 30 m1-.
As can be teen fr.m the drscrlptioa of the operation of the generators,
they work intermittently at charg+_rg to pexaturea. The initial temperature is
too high, while the final temperatue i; too low for normal Pyrolysis. This is
the fundamiental d,:avback. of the generators, which can be partially offset by
using generators with th--ittled feeding. la this t'rpe of generator, the crude
material is fed in at, a rerid rite in the beginning of the gasification stage
and slowly at the cruel of that stage.
The latest acur.?:e ,at of pyrol.ysi.e te--haology is the use of pyrolysis
ffiterally, "progenic_'7 pipe stifle, in which the operation proceeds continuously
with a high yield of e.r.?tice and a 1n+ P'Yp?nditure of fuel. The servicing of
pyrolysis pipe still? is coneldsribly easier than that of generators.
The flow sheet of the pnr.?ecs wing a p r_' ,is p i still is shown in
Figure 107, P 195. the cz&..ide material, after being e
, is pumped through the c,~tvection chAmt.r of thehipe still (2)
(1) and from
there into the evaporabr? (3;, from which the heavy fraction of the crude
material is drtiined. The evattiirat_d light fractioc pasties through a separator.
where entrained drops of liquid ere eliminated. From there the vapors
are conducted throu,_1. th_ radiant sectioc of the pipe still and then pass into
the reaction chamber The reaction chamber ie a cylindrical piece of equip-
ment lined with refractory brick. The formation of aromatic compounds takes
place in the reaction chbm}her. The rest of the flow sheet dose not differ much
from that of the pyroiy_le initallaticmri which have already been described.
The vapors enter tbe hrdreulic 4epnrator (7i, where the heavy hydraulic tar is
eliminated, The vepryrs,, which hw't been freed of hydraulic tar, are fractionated
in the distillation colu '11`.. Light oil and Pyrolysis gas are taken from the
top of this column, while the distillation residue is drained off at the bottom.
In the gas separator (IS), yj.??,lyai; gas is separated from the light oil. The
light oil is conducted ;heed for additional processing.
The pipe furnace Is a ulpped with pipes of large diameter (up to 150 mm
made from steel of high gwsl.i.ty, so twit uninterrupted operation is possible)
for long periods. The coke which fors in the reaction chamber is burned out
periodically.
As can be seen from the dus+cription cf the technological aspects of the
flow sheet, pipe-still iastaliatiorne for pyrolysis have the following advantages:
(1) high efficiency achieved iz a continuous process; (2) ease of servicing;
(3 small area occupied by the installation; and (4) possibility of carrying
out distillation of tier. in the installation.
Catalytic Arometization
Catalytic arcm&tlzstlrln is brought about by passing through catalysis
chambers lc-r-octane gn8olt a or ligroin mixed with gas that has been enriched
with hydrogen. Application of the process in question makes it possible to
obtain up to 80% aromatic;.
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(2), which is icw~ L't Ciuv of the proceaa. The pipe still
and the circulating gi with two f pi.~, bests the crude material (l)
leaving the 1 circulating gas e.riched with kvd: ,gea; each in its separate coil. C,
e till has
the nr-' ma .arid1, xhict a
and the gas, FP which has , t.?mxw,:ure _ 60& nature of 5300 C,
of two reaction chambers (6;1, which a at a mixed and enter the first
emperature of 5500 b boat at Pressure of 20 atm and a
temperat and cbgnbers s.r hollar maid;..; they are filled with
Cataly operate alterute7p is such .a rsanner that either the reaction is
carried out ar the catalyst
chambers rare ytpd 1,.:-a any one ch,smber. on leaving the
, the resctio:h tzcdu::r.n :lr= cy:
Part of the gad
lsl 6n!1 enter the. Sys aelerator (8), A
fuel line. T ThA t7 i, z"`cin c at :; vY..t1~ eocrthr:r the is cocductpd into the
~he l].!iS.ir~ ~.~, 9.rv1'i?.:: f~C4 ~C"~: ?1 "!g i.nt.l ,we etabil]Ter (9), where
the rest of the gas le slim ;dtrri, TT,??. : r.; ]liTei p:-otu.:t Is distilled in a
second-stage diet].llat.io:, coin
(11) and po?ymera ''13;, ="'P9rat~ It into finished gasoline
The crl:de mst.;r2e: v5v'tr crz:c3a.? y?clz atry]ghL.:.an gasoline, c:
ligroin. A su;flcie_-,c ;x t1t;: r".~ a ;cateLi].,g bvdr,
installation.: geR is obtained at the
The proceaa tai pi.'~:, i:-, .b,? . T.~
Pressure of 2C atm. r. ra.: r? , 1st ,! j0.5500 G'mud at a
During the
of the ring tee ,)ti`"' :`'t+]-yet; so tbi,t the ativity
burning out the coke. To i. _ni=.; ?. t:fa ~,~o, the cntalr,-t i; brought about by
passed through the cat-,iv t 4io gt,E, tainii aXygea are
the temperature must be wetcr,- L^.:ri^:r~ the tin,e . the coke ke is being bux d out,
the catalyst loser it: act? ] if the tom,~ratu a rises above 600? C
vt*y,
,
The pro; eea cf oat..:l) ,.i a.^Jmet
to control at will the 1?ta:~. 1s ilr:ib}.c, ?o that it is s, one
pogs:Lble
may obtain different tvF..s Op
z s]c ' 1r=;iu t Kyr_. ~ j t?twith b In other worde one
and ending with higbiy arorrv tii, gS,;ri] lRin i s with igh--.ct a gasoline
Principally benzene t.csts ;..:, ecj ,_i.;E .. 13].r.L?g up to & 1% of eaontatica
,
The yield of higa-ctf 8 q, :.;4 ?, r
losses) 18%,. and of gAs ?inrluding
Table 1 lists the i'rarFr-t, ,,,T Lh,?
gasoline obtaiilFd b "t`.1-`iag vet-.ri~1 and of the finished
} c.a.tr,..-, td.?'. cramytl.2;*,1 .r.,
40-50% The re a ping gqs? lid. contains
aromatics, lzrlyd.irg 15-e
Treatment oY ~ O ysia 'r'r JlU('tA
In the pyroiv?ia et P.: cllnla r
14 coke and soot to F I?'vlr t,, {:t.{?i' gh?, t:5-4
( 8. the with ter =.:re obta1a_d., Products havter ing the follow-
ing clia'ecteriati.cs are cbtiit 1 at rTM,rru].y.~iN inat~iletiose
1. Hydraulic ttr I;yiel.d 1 -IM with res.
to the snide material).
light Oiladistills oft beluir 117 0b-,l:?!. I.or; eugt 1; bp 130-135c" C; -`%
2. 0ondeaser tar .y-,e 3. with re?'_re'ace to the crude naterial).
A brown liquid with a. Pe etr,tine Odor, which has the following average
constants characterizing Its tc,
determined by y di diastillation wild .jityz d1, - 0.856 (fractional eompoaition as
i%adsb_jE'r !tcmi)
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5%
17.1% (benzene fraction)
83-108? C
5%
108-113? C
23%
'toluene fraction)
1'1.3.136? C
6%
1:36-1 3? C
13%
(xylene fraction)
^p to 175
C
75%
3. Scrubber oil. Corttine 6-7% of light oil extracted from gases in the
scrubbers. The fractional contxxeitio: of the light oil is as follows:
B...lov Inc C
78-83? C
6.3-108? C
10}'.-113? C
113-118`' C:
4. Gas, freed of 1ignid hyercc rbcua; which contains up to 30% of un-
saturated hydrocarbons.
The production cf s.rom.tic hydrocarbons involves the following
processes:
a. Tars resulting from the pyrolysis of crude material are distilled
in tar-distillation iast.e:Ustions to seps.rate the light oils contained in the
tars.
b. The light oil is distilled is fractionation installations to
obtain crude fraction which contain aromatic hydrocarbons (first fractionation).
d. The purified fractions are distilled in fractionation installations
to obtain pure benzene, toluene, and xylene (second fractionation).
In addition to facilities for the processes mentioned above, many petroleum
gas plants are equipped with installations for the production of petroleum coke,
naphthalene, and varnish jil jiterally "ltakoyl"7.
The processes for the rroductiac of aromatic hydrocarbons which are
enumerated above will now be deac:ribed in further detail.
Condenser tar and scrubber oil are distilled in pipe still instal-
lations equipped with distillation columns. In these installations, light oil
(2l%), green oil (35%), and liquid pitch (4p$) are obtained. If the green oil
has not been separated out, the residue is wash oil.
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The lil~ht oil, which has a specific graviy of 0.850, consists to the
extent of 85-90% of fractions which boil below 175' C. It is composed of a
benzene fraction (20$), toluene traction (16%), and xylene fraction (11!x).
Green oil is a valuable product from which carbon black used in auto-
mobile coatings and rubber products is obtained. The initial boiling point of
green oil should not be lower than 175? C, the end point no higher than 3500 C.
Naphthalene oil contains up to 1.5% naphthalene. The initial boiling
point of naphthalene oil is 190? C, the end point 235? C.
Liquid pitch hee a specific gravity of the order of 1.03-1.07. It is
a good crude material for the production of coke.
Wash oil does not contain jhoul.d not contain?] more than 0.1% of
carbon black. Its initial boiling point is between 175-200? C.
First (Preliminazy) Fractionation
In addition to aromatic hydrocarbons, light oil also contains a con-
siderable amount of unsaturated and saturated hydrocarbons. Unsaturated hydro-
carbons are eliminated by treatment with sulfuric acid, while the saturated
hydrocarbons are removed by fractionation.
To achieve a saving of sulfuric acid, narrow crude fractions are
distilled off in the first fractionation of the light oil. These fractions are
purified and then subject