CA1326687C - Process for the production of vinyl chloride by pyrolysis of 1,2-dichloroethane - Google Patents
Process for the production of vinyl chloride by pyrolysis of 1,2-dichloroethaneInfo
- Publication number
- CA1326687C CA1326687C CA000557498A CA557498A CA1326687C CA 1326687 C CA1326687 C CA 1326687C CA 000557498 A CA000557498 A CA 000557498A CA 557498 A CA557498 A CA 557498A CA 1326687 C CA1326687 C CA 1326687C
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- Prior art keywords
- dichloroethane
- vinyl chloride
- gas
- cracking furnace
- cracking
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C21/00—Acyclic unsaturated compounds containing halogen atoms
- C07C21/02—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds
- C07C21/04—Chloro-alkenes
- C07C21/06—Vinyl chloride
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/25—Preparation of halogenated hydrocarbons by splitting-off hydrogen halides from halogenated hydrocarbons
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Abstract Process for the production of vinyl chloride by pyrolysis of 1,2-dichloroethane A process is described for the production of vinyl chloride by pyrolysis of 1,2-dichloroethane. Gaseous 1,2-dichloro-ethane generated in various ways is indirectly warmed by means of the hot vinyl chloride-containing gases which are drawn off from the radiation zone of the cracking furnace. In this way, a favorable utilization of the cracking gas heat, higher cracking conversions or longer service lives of the cracking furnace are made possible.
Description
1326687 CA ~ USA
HOECHST AKTIENGESELLSCHAFT HOE 87/F 901 Dr~S-ba ~erk Gendorf UHDE GmbH
A process for ~he production of v;nyl chlor;de by -pyrolysis of 1,2-dichloroethane Description -The invention rela~es to a process for the productist7 of vinyl chloride as claimed in clai~
The incomplete pyrolysis of 1,2-dichloroethane at initial furnace pressures of 0.8 to 4 MPa and tPmperatures of 450 to 550C for the production o~ vinyl chloride has been opera~ed on an industrial scaLe for many y~ars~ The pro-cess requires considerable amoun~s of energy for heating ~
the 1,2-dichloroethane to the cracking temper~ture, for ~:
subsequen~ d;stillative separation of the crac~d gas mix-ture and also for purification of the unreacted and the newly s~ppli~d 1,2-dichloroethan~ ~hich represents a sub- ~ :
stantial cost factor. For the recovery of a part of the energy expended in ~he various process steps there are a series of kno~n processes, som~ of ~hich relate to ~h~
dis~illation and some of ~hich relate to the energy expen- --ded in ~he pyrolysis of the 1,2-dichloroethane. The vinyl chloride production proeess can be d~signed cons;derably more favorably #ith respect ~o the energy consumption : 25 using these proc~sses~ wherein, depending on the type of the energetically very complex process employed, sometimes the former and somet;mes the lat~er processes c3n be more ~:
favorably employed. In each case it is ~dvantageous to ~.
~ have a large nu~ber of processes for energy recovery to :: 30 hand, in order to be able to optimi~e th~ proc@ss in each case by suit~ble select;on. ~--.. :' To reuse the energy contained in the hot vinyl chloride- - :
containing gases which L~ave the cracking furnace~ proces-35 ses eo employ ~hese gases are kno~n from Canadian Patent ~ :
~. ..
` ~3266~7 1,127,669 and U.S. Patent 4,324,932, in order to ~vaporate ~ater or 1,2-dichloro~thane, for examPle~ and to use the stQam to heat apparatu~ elseuher~ ;n the vinyl chloride production process or to feed the ~Yaporated 1,2-dichloro-ethan~ at a temperaeure of 240 to 260C to the cracking zone ot the pyrol~sis furnac~. According to the process of EP 180~995, the gas Mixtur~ lea~ing the cr3c~ing furnace is chilled by direGt cooling and 3dde~ to a q~nch colu~n, in ~hich th~ gas ~ixtur~ i~ obtained as cond~ns~d vapDrs~ -These condensed vapors are brough~ to at l~ast th~ir dew poin~ by indirect cooling and, using ~he heat giuen otf, in ~his exa~ple, li~uid 1,2~dichloro~than~ is ~arm~d to 80~C and air tor co~bustion for the cr~cking furnace to .. 110~C, a~ ~ell as heating th~ botto~ of th~ distillation colu~n for th~ re~oval of hydrogen chloride.
More r~cently, it has ~een proposeld ~Ger~an Patent Appli~
ca~ion P 36 34 550.~3 to evapor~t~ ~iquid 1,2-dichloro-ethan~ in an appara~us, co~prising ~o containers, by ~eans of th~ hot viny~ chlorid~-eontaining ~as~s fro~ th~ cracking furnace ~nd to feed it ~ithou~ ~urther ~ar~ing at ~ t~mp-~rature of 170 to 230~C ingo the cr~cking furnac~. -All these ~no~n proc~s~es essentially ~mpLoy the h~t contained in th~ crackins g3ses ;n ord~r t~ ~ar~ and ~vaporatQ liqui~ 1O2-dichloroethane.
A proc~ ha~ now be~n found ~hich ~kes i~ poss;hle further to ~ar~ g~seous 1,2-dichloro~thane ~hich has b~en obtained, tor ~x~mple, by boil;ng at 170 ~o 280C, ~o th~ r~gion of the : -cr~cking t~mp~r~tur~, ~hile avoiding panti~l superheating, as occur~ in the hith~rto convantional he~ting in the radiation zone oY the eracking furn~ca.
The n~ proc~ss for the pro~uction of vinyl chlori~ by ther~l oli~ination nf hydrog~n chloride fro~ 1~2~dio ehloro~th~n~ in ~ er~ckin~ furnaee ~hich cont~ins ~ radia-Sion zone co~pris~s indir~etly ~ar~ing ~ 9~s ~hich contains ~t l~st 95X ~y ~eight o~ 1,2-dichloroethan~ in ~ h~e exchan- .
~r by ~eans o~ hot vinyl chlori~e-cont~ining g~sO ~hich is ':
_ 3 _ ~ ~2~68~
drawn off from ~he radiation zone of the cracking furnace after pyrolysis, and then feeding it into the cracking furn-ace.
For brevi~y, the zone of the cracking furnace in which the pyrolysis of the 1,Z-dichloroethane to vinyl chloride and hydrogen chloride essentially takes place is designated as - :
the radiat;on zone. In part, the ~arming of the gaseous -::
~ dichloroethane to the cracking temperature also occurs 10 in this zone in the presently conven~ional manner of ~-op~ration~ The name "radiation zon~" comes about since~ in the hitherto conventional cracking furnaces, the tube in ~hich the 1,2-dichloroethane is transported is exposed in this zone to direct heat radiation by the burner flames which :~:
heat the furnace~ The par~ of the furnace ~hich is as a rule above the radiation zone and in ~hich the 1,2-dichloroethan~
containing tube is heated only by the hot exhaust gases of the burner flames, is designated the ~convect;on zone" below. ^: :
... .
20 In principle, a gas which contains less than ~5% by weight ..
of 1,2-dichloroethane can also be tr@ated according to the invention~ in particu~ar wh~n the r~mainder essentially compris~s inert gas. Ho~ev~r, wh~n the r~mainder i5 the conventionaL process impuriti~s, a gas containing less than 95% by weight of ~2-d;chloroethane i~ generaLLy un~uitabLe for pyrolysis to vinyl chloride. This Limit has been se~ected here to distin~uish it from the gas mixture ~hich leaves the ..
: cracking ~wrnaee 3fter pyrolysis and still conta;ns considQr-able amounts of unreacted 1~2-dichloroethane, but not at 30 least 95X by w~i9hto A ~as containing at least 98X by ~eight ~:
of 1~2-d;chloroethan~ i5 preferably ~armed.
, : ~ Th~ gas ~hich is drawn off from the radiation zone of the cra~kin~ furnace after pyrolysis as a rule conta;ns at least 20X by weight of vinyl chloride. ~elo~ this level it is generally too uneconomical to carry out the cracking process.
The upper vinyl chloride content is limited by the obtainable ::.
: crack;ng conversion and generally does not exceed 50~ by ~e;ght.
'. ~.
_ 4 _ ~ 3~ ~ 6 ~7 Suitable heat exchangers are countercurrent or cross-flow heat exchangers of conventional design, for example double walled, bundled tube, sp;ral or ribbed tube heat exchangers of alloyed chemically resistan~ steels. On S ~hich s;de of the heat exchanger surface the t~G gases flow in each case is unimportant. A certain ~inimum flow rate of the g3ses~ which depends upon the design of the heat exchanger, should be ~aintained in the interests of good heat transfer. In generaL~ the flo~ rate should not ~all belo~ 8 m/s.
The pressure under ~hich the vinyl chLoride-containing gas is drawn off from the radiation zone of the cracking fur-nace ;s not important for the practicability of the pro- .
cess. For economical reasons, a pressure of 0.5 to 3 MPa is preferably selected, since under 0.5 MPa the space-ti~e -- -yield is relatively low and above 3 MPa costly high pres-sure apparatus would h~ve to be used. Particularly good results are ob7ained in the pressur~ range from 1.6 to 2.6 MPa.
The vin~ chloride-containing gas is generally drawn off from the radiation zone of the crackin~ furnace at a temperature of 450 to 5509C and introduced into the gas ~S heat exchanger~ In ~his heat exchanger, th~ gas contain- -:
ing at ieast 95~ by ~eight of 1,2-dichloroethane ;s ~armed tro~ 170 to 280C~ in particular from 230 to 270C, advant- -ageousLy to a temperature ~hich is at least 5DC be~o~ the temper~ture ae which the vinyl chloride-containing gas is 3D dra~n of~ from the radiation zone of the crack;ng furnace.
The gas~ous 1,2-dichloroethane ;s preferably ~armed ~o a temperature at is at least 100~C under the temperature ::
at which the vinyl chloride-sontaining gas leaves the radiation zone of the cracking furnace. :
~ :
Th@ prccess according to the invention can be cdrried out in various pref~rred v~riants. In one o~ these variants, ~
a cracking furnace i~ used which contains a radiation zone ~--2nd a convec~;on zone. Ths ~as containing at least 95X by ~326~7 - 5 - :
~eight of 1,2-dichloroethane ;s generated from liquid 1,2-dichloroethane wholly or par~ly ;n the convect;on zone of the crack;ng ~urnace by indirect heat exchange ~ith the exhaust ~asesu .
The 1,2-dichloroethane vaporated in the convection zone is dra~n sff from ~he cracking furnace and is heated outside in a heat exchanger ~ith the hot vinyl chloride-contain;ng ~ases, and then introduced into the rad;ation 10 zone of the cracking furnace and the majority of the ~ :
1,2-dichloroethane is pyrolyzed there.
In a furth~r variant of the process according to the inven~ion, the gas containing at Least 95X by ~e;ght of ~ -1~2-dichloroethane is generated from liquid 1,2-dichloro~
ethane vholly oc partly outs;de the cracking furnace in -an evaporator~ Heating media ~hich can be used here ar0:
hot exhaust gases originating from 2 co~bustion process :
outside the ccack;ng furnace, high pres~ure steam or high-20 boiling liquids such ~ d;phenyl9 ~Marlotherm S, condensed arooatics or su;tably heat-resistant cil;cone oils, which are heated to the te~p~rature nece~sary for the ~vaporation of th~ 10Z-dichloro~thane~ for exa~7ple by a combustion process or by hot vinyl chlorid@-ce~ntainin~ gases, which are drawn of f from th~ radiation zone of the cracking furn~
ace att~r th~ pyrolysis of the 1,2-dichloroethan~. Provided that these gases h3v~ initially been used according to the inv~ntion f~r heating gaseou~ 1,2-dichloroethan~, they can stil~ subsequ~ntly serve tor preheating these heat-trans-ferring ~edi~.
: In a further preferred ~mbodiment of the process according -to the invent;on, the ga~ cont~ining at least 95~ by ~eight of 102-diGhloroethane is generated from l;quid 19Z-di-ch~oroe~hane ~holly or p~rtly by ;ndirect heat exchange ~ith hot vinyl chloride-Gontainin~ gas ~hich has been dra~n off from th~ radia~ion ~one of the cracking furnace af~er pyroly-si~ of the 1,2 dichloro~thane. In this case, the processes -~:
aCCQrdin9 t9 the above~entioned European ~atent Applications ,-, - b - - 1326687 14,920 and 21,381r for example~ and also the more recently proposed process according to German Patent Applicat;on P 36 34 550.4, can be used. The conn~ction in series of the process according to the invention and a process as is described in ~he patent applications mentioned in the previous sentence is particularly advantag~ous. in this case, the hot~ vinyl chLoride-containing gas is initially employed to hea~ gaseous 1,2-dichloroethane according to ~he invention and subsequently to evaporate liquid 1,2-diçhloroethane. The v;nyl chloride-containing gas result-ing from this evaporation~ still at at least 170 ~o 280C, can subsequently be advantageously employ~d in an add-itional hea~ exchanger to warm liquid 1,2-dichloroethane ~o close ~o the evaporation temperature. The vinyl chloride-containing gas is then sooled to -20 to ~50C to eondense the unreacted 1,2-dichloroeth~ne contained --therein and the vinyl chloride and additional by-products, and ~he gaseous hydrogen chLoride is separated otf in a coLumn as is customary. The pressur~ at the top o7 this cvlumn 1s ad~antageousLy set in a knu~n manner so ~hat the ho~ vinyl chloride cont~inin~ gas leaves th~ radia~ion zonQ of the cracking furnace ~t a pr~ssure of 0.5 to 3 MPa.
In particular ~hen the process according to the invention 25 has been e~ployed ~ith evapor~tisn of ~h~ Liquid 1,2-di- :
chloroethane ~or the gen~ra~ion of a gas congaining at leas~ 95% by ~eight of 1,2-dichloroethan~ outsid~ ehe crack- -:
ing f~rnace~ the gas containing at least 95X by Yeight of :
7,2-dichloroethane can be introduced into the radiation zone and also the convection zone of the cracking furnace after ~he heating aceording to the invention.
-The gas con~aining at l~ast 95~ by ~ei~h~ of 1,2-dichloro-ethane can ori~inat~ from a distill~tion column, after which it is brou~h~, ~sing conventioni~l compressors~ to ehe pres-~ure ~hich ~s nec~s~ary for f~eding into the cr~riking furn- .
~G~ aft~r th~ ~ar~ing according to th~ invention. ~-~s already ~entioned at th2 beginning, the process according : . "" ' ~,, , ",.,,",,,,~ "~"1,. "~",~ ~', ,,, " ~, ~"~ "';~ '," "~
~ 7 ~ ~32~7 to the inventisn mak~s it possible to émploy th0 heat : .
contained in th~ hot gases Leaving the cracking furnac~
while in contrast ~o the kno~n prscesses there is an additional saving of primary energy (fuel)~ The ~ain S advantage is that the gas~ous 1,2-d;chloroethan~ is heated more gently by heat exchange according to the process according to ~he invention than in th~ radia-tion zone of the cracking furnace, in ~hich the compar-atively very ~uch hotter burn~r flames can g~n~rat~ unde-sired hoe spots. Considera~ly higher ~rac~ing sonver-sions can be obtained using th~ ne~ proc~ss ~ith an e~uivalent or even lengthened service lif~ of the crackin3 furnace, or, ~h~n it is not d~sirad to incr~a~ the con~
version, it i3 posisi~e to simply lengthen th~ service lif~ of ~he cracking furnac~ considerably and to generate f~wer byproduçts during craeking. --Th~ ex~mples 3nd co~parison ~xp~ri~nt~ belo~ s~rv~ t~
illustrate th~ invention in greater detail: -2~ In the example, reference is made to the figures in which: :
Figure 1 is a flow chart showing the process of this invention as conducted in accordance with Example l;
Figure 2 is a flow chart, for comparison purposes, showing the process as conducted in the prior art in accordance with European Patent Application 21,281;
Figur~ 3 lS a flow chart showing the process of this ;~:
invention as conducted in accordance with Example 2; and ~;~
Figure 4 i5 a flow chart, for comparison purposes, showing the process as conducted in the prior art, in accordance -: ~ 30 with German Patent Application P 36 34 550.4. :~
:
:
Exa~pl~ 1 ;~ A proc~ss is used aecording to the ~lo~ chart r~pres4nted in Fig~ 1. 826 kg o~ 1,Z-dichloro~than~ ~t ~ te~perature ~.;
: of 130~C ~r~ dr~n otf p~r hour fro~ ~ pu~p r2servoir ~1j: ::
~ 35 ænd~pumped 3t ~ t~operatur~ of 125C by oeans ot th~ pump .
~ 3 ~
- 7a -~2~ through ~h~ convec~ion zone t3) of a cr~cking furnac~.
The 1~2-dichlorQ~eh~ns evaporates co~Ple~ly at ~ ~e~per ~ure of 260~C, and is dra~n off in gas for~ fro~ ~h2 con vection 20n~ through the pipe ~43, ~ar~ed ~o 350C outside the furnace in a heat exchanger (5) ~nd in~roduc~d through the pipe t6) in~o the radiation zon~ ~7) of Sh~ cracking turn~cQ. This radi~tion zone (7) i~ h~t~d ~y four rows of burner~ arrang~d on~ ~bov~ ~h~ other, ~o ~hich 0.0876 Nm3 of fuel ~me~han~) p~r kg of gener~t~d vinyl chloride lO i~ f~d through the pip~ ~8). A ~ajor part of ~h~ 1,2-dichloro~thane is pyrolyzed to vinyl chlorid~ ~nd hydrog~n chloride in th~ radi~tion ~on~ ~7). The vinyl chloride-containin~ ga3 ~ixt~r~ a~ 518C whieh l~av~s the cracking zon~ ~7) is fed to the h~t exchang~r (5) through the ~'`' '`"
~, .
.
' , ..:
~ ,.' '.
.: .
., : ' . . ':" .
132~
pipe (9) and leaves the latter t~rough the pipe (10) a~ -a temperature of 433~C. The vinyl chloride-containing gas passes through the pipe (10) in~o a further heat e~changer (11)9 ~hich ;t leaves at Z20C through the pipe (12). It is subsequen~ly cooled as customary and distilled. The pressure at ~hich the hot vinyl chloride-containing gas leaves the radiation zone (7) through the pipe (9) is 1.8 MPa and i5 se~ at the top of the column in which hydrogen GhlOride i5 removed by distilla~ion. The heat ~xchanger 1~ t11) is supplied with boiler feed ~ater at a temperature of 100C through the pipe (13) and generates 90 kg/h of steam a~ a pressure of 0~9 MPa and a tempera~ure of 175C~ which -.
corresponds to a quantity of heat of 679.5 kJ/kg of vinyl chloride or 0.0191 Nm3 of fuel (methane) per Itg of gener-15 ated v;nyl chlsride~ The effective fuel ~ethane) consump- ..
tion is thus reduced to 000685 Nm of methane per kg of generated vinyl chloride. The steam leaves the heat ex- -changer (11~ through the pipe t14).
Z0 313 kg/h of vinyl chloride are produced~ the conversion of the crack;ng is 60% and s~rvice life of the cracking furn-ace is 7 months Comparison experiment A
~5 A process is used according to the flo~ shart repr~s~n~ed in Fig. 2, in ~hich the referenc~ numbers have the sam~
~eaning as explained in x~0ple 1. The toLlo~ing experi-~ental eonditions differ from Example 1: 904 kg/h o~ 1,2- : -:
dichLoroeth~ne at a te~perature of 1Z5C ~re pumped 3Q fro~ t~e pu~p reservoir tl) by the pump ~2) into the con-.~
vec~1on ~one S3~ of the cracking furnace~ and ar~ evapora- :
ted there and are ~urth~r introduced in gas for~ throu~h th~ pipe t15) into the radiation 20ne (7) in the furnace.
The hot vinyl chlorid~ containing ga~ at a te~p~rature of 3S 530C is taken from the radiation 20ne (7) through the : -pip~ tl6) into th~ he~t exchan~er t11) and l~aves the lat-t~r ~t a temp~r~ture of 220C through the pipe ~12~.
~oil~r feed ~ter at 100C is introduced into the heat ex- -ch~nger (11) through the pipe (13) ~nd from this 142 k~/h _ 9 _ ~32~
9f steam at a pressure of 0.9 MPa and a temperature of 175C are dra~n off through the pipe (14). This corres-ponds to a heat of 1100 kJ/kg of vinyl chloride, corres-ponding to an amount of fuel of 0.03 Nm3 of methane per kg of vinyl chLoride generated. The four ro~s of burnPrs in the cracking furnacs are suppl;ed ~hrough the pipe (8) ~ith 0.109 Nm3 of methane per kg of VC produced. The effective fuel consu~ption is thus 0.07~ N~3 of methane per k~ of vinyl chloride generated~ which is 15.3% ~-greater ~han in Exampl~ 1. 313 kg/h of vinyl chloride are produced, the conversion of the cracking is 55%
and the servic~ life of the cracking furnace i5 4 months.
This compar;son experiment ~as carried out analogously to the process described in European Patent Application 21,381.
Exa~ple 2 pro~ess ;s used according to the scheme represented in Fig. 3~ 798.5 kg of 192-dichloroethane per hour are dra~n 20 of~ from a pump reservoir ~1~ and are pump~d at a tempera- :
tur~ of 125C through a section (17) of $he convection zone of a cracking furnace by mean~s of a pump (2~. The :
1,2-dishlsroQthane is heated to 24l3~C ;n this section (17) ~nd is ~ed as a liq~id to an evaporator (19) through the p;pe t18~. Fro~ the evaporator (19) it passes through the descending pipes ~20) into the app~ratus t21~ and fro~ the latt~r circ~lat~s back through the ascending pipes (22~
into the evaporator (19~. The gaseous 1,2-dichloroe~hane : -~aves the evaporator (19) at a t~peratur~ of 260C and is ~ :~
fed to a heat exchang~r ~5~ through the pipe (24), ~hich it l~v~s at a te~per~turQ of 367C throu~h the pipe S25) and is introduced into the radiation zDne (7) of the craek-ing fu~nace. Gas~ous 1,2-d;ehloro~thane from the evapor-ator t19) can be introduced directLy into the radiation zon~ S7) ot the cracking furnace through a by-pass ~26), ~hich contains a control vaLve ~hich is reguLated through the l~v~l of the liquid in the ev3porator (19). The -:.
a~oun~ of thi~ gaseous 1,2~dichloro~thane is lo~ in compar-ison to the amhunt ~hich is introduced through the heat : . . ~ : . : .. , . : .. , ... : ~ : . :. : : . : ., : :: : :. ::
~326~7 exchanger (5) and only serves to equalize the energy duriny process fluc~ua~ions. From the radiation zone t7~, the hot vinyl chloride-conta;ning gas is fed at a temperature of 523C
to the heat exchan~er (S) through the pipe (9) and leaves the latter at a temperature of 422C through the pipe ~27), which Leads into the apparatus (21~, in ~hich the liquid 1,2-di-chloroethane, ~hich ;s recycled from the evaporator (19~ as described above, is indirectly heated to boiling by the hot : .
vinyl chloride-con~aining gas. The Yinyl chloride-containing ~as leaves the app3ratus (213 through the pipe (28~ at a temperature of 265C, is then cooled as cus~omary and worked up by distillation, the pressure at the top of the distill-ation column in ~hich the hydrogen chloride is removed by distillation being se~ so that the hot vinyl chloride-contain-15 ing gases leave the radiation zone (7) of the cracking furn- ::
ace through the pipe (9~ at a pressure of 1~9 MPa. --28 ~9 of 192-dichloroethane containing solid particles are dra~n off hourly 7rom th~ apparatus ~21) through the pipe (23~ and are freed ~ro~ the solids else~here in the process and re-employed. Th~ four rows of b~rners o~ the cracking ::
furn~ce ar~ supplied through the pipe (8) ~ith a total of 0.075 Nm of fuel (~ethane) per kg of vinyl chloride gener-ated. b75 dm3/h of boiler fe~d water (pressure 2.5 MPa), 25 which is f@d at 1D0C ~hrou~h ~he pipe t30)~ are heated to. .
~50C in the ~pper p~rt ~29) o~ the conYection zone of the cracking furnace in an ~conomizer and are dra~n off through the pipe ~31) and used elsewhere in the process. 317.7 kJ
o~ energy are thereby recovered per kg of vinyl chloride corr~sponding to a t~el (methane~ a~ount of 0.009 Nm3 per kg of vinyl chloride gener~ted. The effectlve fuel con-su~ption is thus reduced to 0.966 N~3 per kg of vinyl chlsride generated.
330 kg/h of vinyl chloride ~r~ produc~d, the sonversion in the crack;ng ~s 68X and the service life of the cracking furnace is 12 months.
Co~parison ~xperiment B
1326~87 Th;s comparison experiment is carried out analogously to Example Z of ~erman Patent Application P 36 34 550.4.
A process is used according to the scheme represented in Fig. 4 834 kg of 1,2-dichloroethane are dra~n off per hour from a pump reservoir (1) and are transported at a temperature of 125C through the heat exchanger ~32~ and through the pipe (33) into the evaporator ~19) by means of a pump.
The heat exchanger ~32) is heated using 25 kglh of high pressure steam ~2.1 MPa pressure; 215C) from ths boiler ~34) through the p;p~ (35~. ~y ~easuring the leveL o7 the liquid 1,2~dichloroethane (LIC) ;n the evaporator t19) as a regulating var;able, the high pressure steanl throughput ~o the heat e~changer (32~ is regulated. The 1,2-dichloro-ethane leave!s the heat exchanger (32) at a temperature of 161~C. .
rhe hot vinyl chloride-containing gas leaves the radiation 20 zon~ ~7) of the cracking turnace at a temperature of 533C : : -throu3h the pip2 (36)~ passes through the apparatus (21) : :
and leaves the l~tter at a temperature of 245C through the pipe (Z8). Following ~his~ the vinyl chloride-containing 9~5 is further cooled by a customary process and hydrogen chloride is r200ved by distillat;sn in a column. The pre~sure at the top o~ this colu~n is r~gulated so that hot vinyL chloride-containing ~as leaves the radiati~n zone ~7) of the craskin~ furnace ~t a pressur~ of 1.9 MPa. Liquid 1~Z-dichLoroethan~, as d~scribed ;n xamp~e 2, is circulated ~ :
30 in the pipes (20) and (22). The gaseous 1,2-d;chloroethane ;s fed into the radiation zon~ (7) of the cracking furnace through the pipe ~37~ from the evaporator (19) 3 30 kg/h of liquid 1,Z-dichloroethane are drawn of~ fro~ the app~r-atus ~21~ through the pipe (23), freed from solids and employed ~ls~h~re in ehe process. The four rows of bur-ners of th~ cracking ~urn~ce located one abov~ the other ar~ suppli~d through the pipe ~8) ~ith a total o~ 0.1074 : Nm3 of ~uel ~ethan~) per kg of vinyl chlorid~ ~enerated. :
330 dm3/h of boiler feed water (pressure 2.5 MPa), which ::
'~. .'.".:
~ 32~7 are fed at 80C through the pipe (39), ar~ heated to 150~C
in the upper part (38) through the convec~ion zone of the cracking furnace in an economizer and par~ly introduced into the boi~er (34) through the piPe (40), and partly reused elsewhere in the vinyl chloride production process through the pipe (41)~ The l;quid from the boiler (34) i5 fed to the lower part (43) of the convection zone of the cracking furnace through the pipe (42), is heated ~here and is fed in~o the boiler (34) through the pipe (44). As already ment;oned above, part of the steam generated ;n the boiler (343 is used for heating the heat exchanger (32). The m3 jori~y of this stea~, namely 167 kg/h, is dra~n off through the pipe (45) and used else~here in the process for the generation o~ vin~l chloride. 1~36.2 kJ
of energy are recovered per ~9 of vinyL chloride. 13b dm3/h of boiler feed ~ater at a tempera~ure of 150C are --fed for further use through the pipe (41~, ~hereby 121 kJ
of energy are recovered per kg of vinyl chloride. The total amount of energy recovered is 1236~2 ~ 121 = 1357.2 20 kJ~kg of vinyl chloride; this corre~ponds to a fuel (m2thane~ amount of a.o3s Nm3/kg of vinyL chLoride. The effective heat;ng ~as consumption is thereby reduced to 0~0694 Nm3/kg; this is 5X more than ~as neces~ary in Exa~ple 2. The cracking furn~ce ~ervice life is 9 months, 2$ 330 kg/h of vinyl chlor;de are produced and tho convers;on in th~ cracking of the 1,2-dichloroe~hane is 65X.
TeGhnic~-grade 1~2-dichloro~thane containing 99O7% by ~eight ot pure 1,2-dich~oroethane i5 employed in 3ll exa~ples and comparison experi~ents, the remainder being Gustomary by-products SUGh 3S trichloroethan2, benzene, tO1-dichloroethane, trichloroathylene, tetrachloroethylene, chloroform~ carb~n tetrachloride and chloroprene.
: '
HOECHST AKTIENGESELLSCHAFT HOE 87/F 901 Dr~S-ba ~erk Gendorf UHDE GmbH
A process for ~he production of v;nyl chlor;de by -pyrolysis of 1,2-dichloroethane Description -The invention rela~es to a process for the productist7 of vinyl chloride as claimed in clai~
The incomplete pyrolysis of 1,2-dichloroethane at initial furnace pressures of 0.8 to 4 MPa and tPmperatures of 450 to 550C for the production o~ vinyl chloride has been opera~ed on an industrial scaLe for many y~ars~ The pro-cess requires considerable amoun~s of energy for heating ~
the 1,2-dichloroethane to the cracking temper~ture, for ~:
subsequen~ d;stillative separation of the crac~d gas mix-ture and also for purification of the unreacted and the newly s~ppli~d 1,2-dichloroethan~ ~hich represents a sub- ~ :
stantial cost factor. For the recovery of a part of the energy expended in ~he various process steps there are a series of kno~n processes, som~ of ~hich relate to ~h~
dis~illation and some of ~hich relate to the energy expen- --ded in ~he pyrolysis of the 1,2-dichloroethane. The vinyl chloride production proeess can be d~signed cons;derably more favorably #ith respect ~o the energy consumption : 25 using these proc~sses~ wherein, depending on the type of the energetically very complex process employed, sometimes the former and somet;mes the lat~er processes c3n be more ~:
favorably employed. In each case it is ~dvantageous to ~.
~ have a large nu~ber of processes for energy recovery to :: 30 hand, in order to be able to optimi~e th~ proc@ss in each case by suit~ble select;on. ~--.. :' To reuse the energy contained in the hot vinyl chloride- - :
containing gases which L~ave the cracking furnace~ proces-35 ses eo employ ~hese gases are kno~n from Canadian Patent ~ :
~. ..
` ~3266~7 1,127,669 and U.S. Patent 4,324,932, in order to ~vaporate ~ater or 1,2-dichloro~thane, for examPle~ and to use the stQam to heat apparatu~ elseuher~ ;n the vinyl chloride production process or to feed the ~Yaporated 1,2-dichloro-ethan~ at a temperaeure of 240 to 260C to the cracking zone ot the pyrol~sis furnac~. According to the process of EP 180~995, the gas Mixtur~ lea~ing the cr3c~ing furnace is chilled by direGt cooling and 3dde~ to a q~nch colu~n, in ~hich th~ gas ~ixtur~ i~ obtained as cond~ns~d vapDrs~ -These condensed vapors are brough~ to at l~ast th~ir dew poin~ by indirect cooling and, using ~he heat giuen otf, in ~his exa~ple, li~uid 1,2~dichloro~than~ is ~arm~d to 80~C and air tor co~bustion for the cr~cking furnace to .. 110~C, a~ ~ell as heating th~ botto~ of th~ distillation colu~n for th~ re~oval of hydrogen chloride.
More r~cently, it has ~een proposeld ~Ger~an Patent Appli~
ca~ion P 36 34 550.~3 to evapor~t~ ~iquid 1,2-dichloro-ethan~ in an appara~us, co~prising ~o containers, by ~eans of th~ hot viny~ chlorid~-eontaining ~as~s fro~ th~ cracking furnace ~nd to feed it ~ithou~ ~urther ~ar~ing at ~ t~mp-~rature of 170 to 230~C ingo the cr~cking furnac~. -All these ~no~n proc~s~es essentially ~mpLoy the h~t contained in th~ crackins g3ses ;n ord~r t~ ~ar~ and ~vaporatQ liqui~ 1O2-dichloroethane.
A proc~ ha~ now be~n found ~hich ~kes i~ poss;hle further to ~ar~ g~seous 1,2-dichloro~thane ~hich has b~en obtained, tor ~x~mple, by boil;ng at 170 ~o 280C, ~o th~ r~gion of the : -cr~cking t~mp~r~tur~, ~hile avoiding panti~l superheating, as occur~ in the hith~rto convantional he~ting in the radiation zone oY the eracking furn~ca.
The n~ proc~ss for the pro~uction of vinyl chlori~ by ther~l oli~ination nf hydrog~n chloride fro~ 1~2~dio ehloro~th~n~ in ~ er~ckin~ furnaee ~hich cont~ins ~ radia-Sion zone co~pris~s indir~etly ~ar~ing ~ 9~s ~hich contains ~t l~st 95X ~y ~eight o~ 1,2-dichloroethan~ in ~ h~e exchan- .
~r by ~eans o~ hot vinyl chlori~e-cont~ining g~sO ~hich is ':
_ 3 _ ~ ~2~68~
drawn off from ~he radiation zone of the cracking furnace after pyrolysis, and then feeding it into the cracking furn-ace.
For brevi~y, the zone of the cracking furnace in which the pyrolysis of the 1,Z-dichloroethane to vinyl chloride and hydrogen chloride essentially takes place is designated as - :
the radiat;on zone. In part, the ~arming of the gaseous -::
~ dichloroethane to the cracking temperature also occurs 10 in this zone in the presently conven~ional manner of ~-op~ration~ The name "radiation zon~" comes about since~ in the hitherto conventional cracking furnaces, the tube in ~hich the 1,2-dichloroethane is transported is exposed in this zone to direct heat radiation by the burner flames which :~:
heat the furnace~ The par~ of the furnace ~hich is as a rule above the radiation zone and in ~hich the 1,2-dichloroethan~
containing tube is heated only by the hot exhaust gases of the burner flames, is designated the ~convect;on zone" below. ^: :
... .
20 In principle, a gas which contains less than ~5% by weight ..
of 1,2-dichloroethane can also be tr@ated according to the invention~ in particu~ar wh~n the r~mainder essentially compris~s inert gas. Ho~ev~r, wh~n the r~mainder i5 the conventionaL process impuriti~s, a gas containing less than 95% by weight of ~2-d;chloroethane i~ generaLLy un~uitabLe for pyrolysis to vinyl chloride. This Limit has been se~ected here to distin~uish it from the gas mixture ~hich leaves the ..
: cracking ~wrnaee 3fter pyrolysis and still conta;ns considQr-able amounts of unreacted 1~2-dichloroethane, but not at 30 least 95X by w~i9hto A ~as containing at least 98X by ~eight ~:
of 1~2-d;chloroethan~ i5 preferably ~armed.
, : ~ Th~ gas ~hich is drawn off from the radiation zone of the cra~kin~ furnace after pyrolysis as a rule conta;ns at least 20X by weight of vinyl chloride. ~elo~ this level it is generally too uneconomical to carry out the cracking process.
The upper vinyl chloride content is limited by the obtainable ::.
: crack;ng conversion and generally does not exceed 50~ by ~e;ght.
'. ~.
_ 4 _ ~ 3~ ~ 6 ~7 Suitable heat exchangers are countercurrent or cross-flow heat exchangers of conventional design, for example double walled, bundled tube, sp;ral or ribbed tube heat exchangers of alloyed chemically resistan~ steels. On S ~hich s;de of the heat exchanger surface the t~G gases flow in each case is unimportant. A certain ~inimum flow rate of the g3ses~ which depends upon the design of the heat exchanger, should be ~aintained in the interests of good heat transfer. In generaL~ the flo~ rate should not ~all belo~ 8 m/s.
The pressure under ~hich the vinyl chLoride-containing gas is drawn off from the radiation zone of the cracking fur-nace ;s not important for the practicability of the pro- .
cess. For economical reasons, a pressure of 0.5 to 3 MPa is preferably selected, since under 0.5 MPa the space-ti~e -- -yield is relatively low and above 3 MPa costly high pres-sure apparatus would h~ve to be used. Particularly good results are ob7ained in the pressur~ range from 1.6 to 2.6 MPa.
The vin~ chloride-containing gas is generally drawn off from the radiation zone of the crackin~ furnace at a temperature of 450 to 5509C and introduced into the gas ~S heat exchanger~ In ~his heat exchanger, th~ gas contain- -:
ing at ieast 95~ by ~eight of 1,2-dichloroethane ;s ~armed tro~ 170 to 280C~ in particular from 230 to 270C, advant- -ageousLy to a temperature ~hich is at least 5DC be~o~ the temper~ture ae which the vinyl chloride-containing gas is 3D dra~n of~ from the radiation zone of the crack;ng furnace.
The gas~ous 1,2-dichloroethane ;s preferably ~armed ~o a temperature at is at least 100~C under the temperature ::
at which the vinyl chloride-sontaining gas leaves the radiation zone of the cracking furnace. :
~ :
Th@ prccess according to the invention can be cdrried out in various pref~rred v~riants. In one o~ these variants, ~
a cracking furnace i~ used which contains a radiation zone ~--2nd a convec~;on zone. Ths ~as containing at least 95X by ~326~7 - 5 - :
~eight of 1,2-dichloroethane ;s generated from liquid 1,2-dichloroethane wholly or par~ly ;n the convect;on zone of the crack;ng ~urnace by indirect heat exchange ~ith the exhaust ~asesu .
The 1,2-dichloroethane vaporated in the convection zone is dra~n sff from ~he cracking furnace and is heated outside in a heat exchanger ~ith the hot vinyl chloride-contain;ng ~ases, and then introduced into the rad;ation 10 zone of the cracking furnace and the majority of the ~ :
1,2-dichloroethane is pyrolyzed there.
In a furth~r variant of the process according to the inven~ion, the gas containing at Least 95X by ~e;ght of ~ -1~2-dichloroethane is generated from liquid 1,2-dichloro~
ethane vholly oc partly outs;de the cracking furnace in -an evaporator~ Heating media ~hich can be used here ar0:
hot exhaust gases originating from 2 co~bustion process :
outside the ccack;ng furnace, high pres~ure steam or high-20 boiling liquids such ~ d;phenyl9 ~Marlotherm S, condensed arooatics or su;tably heat-resistant cil;cone oils, which are heated to the te~p~rature nece~sary for the ~vaporation of th~ 10Z-dichloro~thane~ for exa~7ple by a combustion process or by hot vinyl chlorid@-ce~ntainin~ gases, which are drawn of f from th~ radiation zone of the cracking furn~
ace att~r th~ pyrolysis of the 1,2-dichloroethan~. Provided that these gases h3v~ initially been used according to the inv~ntion f~r heating gaseou~ 1,2-dichloroethan~, they can stil~ subsequ~ntly serve tor preheating these heat-trans-ferring ~edi~.
: In a further preferred ~mbodiment of the process according -to the invent;on, the ga~ cont~ining at least 95~ by ~eight of 102-diGhloroethane is generated from l;quid 19Z-di-ch~oroe~hane ~holly or p~rtly by ;ndirect heat exchange ~ith hot vinyl chloride-Gontainin~ gas ~hich has been dra~n off from th~ radia~ion ~one of the cracking furnace af~er pyroly-si~ of the 1,2 dichloro~thane. In this case, the processes -~:
aCCQrdin9 t9 the above~entioned European ~atent Applications ,-, - b - - 1326687 14,920 and 21,381r for example~ and also the more recently proposed process according to German Patent Applicat;on P 36 34 550.4, can be used. The conn~ction in series of the process according to the invention and a process as is described in ~he patent applications mentioned in the previous sentence is particularly advantag~ous. in this case, the hot~ vinyl chLoride-containing gas is initially employed to hea~ gaseous 1,2-dichloroethane according to ~he invention and subsequently to evaporate liquid 1,2-diçhloroethane. The v;nyl chloride-containing gas result-ing from this evaporation~ still at at least 170 ~o 280C, can subsequently be advantageously employ~d in an add-itional hea~ exchanger to warm liquid 1,2-dichloroethane ~o close ~o the evaporation temperature. The vinyl chloride-containing gas is then sooled to -20 to ~50C to eondense the unreacted 1,2-dichloroeth~ne contained --therein and the vinyl chloride and additional by-products, and ~he gaseous hydrogen chLoride is separated otf in a coLumn as is customary. The pressur~ at the top o7 this cvlumn 1s ad~antageousLy set in a knu~n manner so ~hat the ho~ vinyl chloride cont~inin~ gas leaves th~ radia~ion zonQ of the cracking furnace ~t a pr~ssure of 0.5 to 3 MPa.
In particular ~hen the process according to the invention 25 has been e~ployed ~ith evapor~tisn of ~h~ Liquid 1,2-di- :
chloroethane ~or the gen~ra~ion of a gas congaining at leas~ 95% by ~eight of 1,2-dichloroethan~ outsid~ ehe crack- -:
ing f~rnace~ the gas containing at least 95X by Yeight of :
7,2-dichloroethane can be introduced into the radiation zone and also the convection zone of the cracking furnace after ~he heating aceording to the invention.
-The gas con~aining at l~ast 95~ by ~ei~h~ of 1,2-dichloro-ethane can ori~inat~ from a distill~tion column, after which it is brou~h~, ~sing conventioni~l compressors~ to ehe pres-~ure ~hich ~s nec~s~ary for f~eding into the cr~riking furn- .
~G~ aft~r th~ ~ar~ing according to th~ invention. ~-~s already ~entioned at th2 beginning, the process according : . "" ' ~,, , ",.,,",,,,~ "~"1,. "~",~ ~', ,,, " ~, ~"~ "';~ '," "~
~ 7 ~ ~32~7 to the inventisn mak~s it possible to émploy th0 heat : .
contained in th~ hot gases Leaving the cracking furnac~
while in contrast ~o the kno~n prscesses there is an additional saving of primary energy (fuel)~ The ~ain S advantage is that the gas~ous 1,2-d;chloroethan~ is heated more gently by heat exchange according to the process according to ~he invention than in th~ radia-tion zone of the cracking furnace, in ~hich the compar-atively very ~uch hotter burn~r flames can g~n~rat~ unde-sired hoe spots. Considera~ly higher ~rac~ing sonver-sions can be obtained using th~ ne~ proc~ss ~ith an e~uivalent or even lengthened service lif~ of the crackin3 furnace, or, ~h~n it is not d~sirad to incr~a~ the con~
version, it i3 posisi~e to simply lengthen th~ service lif~ of ~he cracking furnac~ considerably and to generate f~wer byproduçts during craeking. --Th~ ex~mples 3nd co~parison ~xp~ri~nt~ belo~ s~rv~ t~
illustrate th~ invention in greater detail: -2~ In the example, reference is made to the figures in which: :
Figure 1 is a flow chart showing the process of this invention as conducted in accordance with Example l;
Figure 2 is a flow chart, for comparison purposes, showing the process as conducted in the prior art in accordance with European Patent Application 21,281;
Figur~ 3 lS a flow chart showing the process of this ;~:
invention as conducted in accordance with Example 2; and ~;~
Figure 4 i5 a flow chart, for comparison purposes, showing the process as conducted in the prior art, in accordance -: ~ 30 with German Patent Application P 36 34 550.4. :~
:
:
Exa~pl~ 1 ;~ A proc~ss is used aecording to the ~lo~ chart r~pres4nted in Fig~ 1. 826 kg o~ 1,Z-dichloro~than~ ~t ~ te~perature ~.;
: of 130~C ~r~ dr~n otf p~r hour fro~ ~ pu~p r2servoir ~1j: ::
~ 35 ænd~pumped 3t ~ t~operatur~ of 125C by oeans ot th~ pump .
~ 3 ~
- 7a -~2~ through ~h~ convec~ion zone t3) of a cr~cking furnac~.
The 1~2-dichlorQ~eh~ns evaporates co~Ple~ly at ~ ~e~per ~ure of 260~C, and is dra~n off in gas for~ fro~ ~h2 con vection 20n~ through the pipe ~43, ~ar~ed ~o 350C outside the furnace in a heat exchanger (5) ~nd in~roduc~d through the pipe t6) in~o the radiation zon~ ~7) of Sh~ cracking turn~cQ. This radi~tion zone (7) i~ h~t~d ~y four rows of burner~ arrang~d on~ ~bov~ ~h~ other, ~o ~hich 0.0876 Nm3 of fuel ~me~han~) p~r kg of gener~t~d vinyl chloride lO i~ f~d through the pip~ ~8). A ~ajor part of ~h~ 1,2-dichloro~thane is pyrolyzed to vinyl chlorid~ ~nd hydrog~n chloride in th~ radi~tion ~on~ ~7). The vinyl chloride-containin~ ga3 ~ixt~r~ a~ 518C whieh l~av~s the cracking zon~ ~7) is fed to the h~t exchang~r (5) through the ~'`' '`"
~, .
.
' , ..:
~ ,.' '.
.: .
., : ' . . ':" .
132~
pipe (9) and leaves the latter t~rough the pipe (10) a~ -a temperature of 433~C. The vinyl chloride-containing gas passes through the pipe (10) in~o a further heat e~changer (11)9 ~hich ;t leaves at Z20C through the pipe (12). It is subsequen~ly cooled as customary and distilled. The pressure at ~hich the hot vinyl chloride-containing gas leaves the radiation zone (7) through the pipe (9) is 1.8 MPa and i5 se~ at the top of the column in which hydrogen GhlOride i5 removed by distilla~ion. The heat ~xchanger 1~ t11) is supplied with boiler feed ~ater at a temperature of 100C through the pipe (13) and generates 90 kg/h of steam a~ a pressure of 0~9 MPa and a tempera~ure of 175C~ which -.
corresponds to a quantity of heat of 679.5 kJ/kg of vinyl chloride or 0.0191 Nm3 of fuel (methane) per Itg of gener-15 ated v;nyl chlsride~ The effective fuel ~ethane) consump- ..
tion is thus reduced to 000685 Nm of methane per kg of generated vinyl chloride. The steam leaves the heat ex- -changer (11~ through the pipe t14).
Z0 313 kg/h of vinyl chloride are produced~ the conversion of the crack;ng is 60% and s~rvice life of the cracking furn-ace is 7 months Comparison experiment A
~5 A process is used according to the flo~ shart repr~s~n~ed in Fig. 2, in ~hich the referenc~ numbers have the sam~
~eaning as explained in x~0ple 1. The toLlo~ing experi-~ental eonditions differ from Example 1: 904 kg/h o~ 1,2- : -:
dichLoroeth~ne at a te~perature of 1Z5C ~re pumped 3Q fro~ t~e pu~p reservoir tl) by the pump ~2) into the con-.~
vec~1on ~one S3~ of the cracking furnace~ and ar~ evapora- :
ted there and are ~urth~r introduced in gas for~ throu~h th~ pipe t15) into the radiation 20ne (7) in the furnace.
The hot vinyl chlorid~ containing ga~ at a te~p~rature of 3S 530C is taken from the radiation 20ne (7) through the : -pip~ tl6) into th~ he~t exchan~er t11) and l~aves the lat-t~r ~t a temp~r~ture of 220C through the pipe ~12~.
~oil~r feed ~ter at 100C is introduced into the heat ex- -ch~nger (11) through the pipe (13) ~nd from this 142 k~/h _ 9 _ ~32~
9f steam at a pressure of 0.9 MPa and a temperature of 175C are dra~n off through the pipe (14). This corres-ponds to a heat of 1100 kJ/kg of vinyl chloride, corres-ponding to an amount of fuel of 0.03 Nm3 of methane per kg of vinyl chLoride generated. The four ro~s of burnPrs in the cracking furnacs are suppl;ed ~hrough the pipe (8) ~ith 0.109 Nm3 of methane per kg of VC produced. The effective fuel consu~ption is thus 0.07~ N~3 of methane per k~ of vinyl chloride generated~ which is 15.3% ~-greater ~han in Exampl~ 1. 313 kg/h of vinyl chloride are produced, the conversion of the cracking is 55%
and the servic~ life of the cracking furnace i5 4 months.
This compar;son experiment ~as carried out analogously to the process described in European Patent Application 21,381.
Exa~ple 2 pro~ess ;s used according to the scheme represented in Fig. 3~ 798.5 kg of 192-dichloroethane per hour are dra~n 20 of~ from a pump reservoir ~1~ and are pump~d at a tempera- :
tur~ of 125C through a section (17) of $he convection zone of a cracking furnace by mean~s of a pump (2~. The :
1,2-dishlsroQthane is heated to 24l3~C ;n this section (17) ~nd is ~ed as a liq~id to an evaporator (19) through the p;pe t18~. Fro~ the evaporator (19) it passes through the descending pipes ~20) into the app~ratus t21~ and fro~ the latt~r circ~lat~s back through the ascending pipes (22~
into the evaporator (19~. The gaseous 1,2-dichloroe~hane : -~aves the evaporator (19) at a t~peratur~ of 260C and is ~ :~
fed to a heat exchang~r ~5~ through the pipe (24), ~hich it l~v~s at a te~per~turQ of 367C throu~h the pipe S25) and is introduced into the radiation zDne (7) of the craek-ing fu~nace. Gas~ous 1,2-d;ehloro~thane from the evapor-ator t19) can be introduced directLy into the radiation zon~ S7) ot the cracking furnace through a by-pass ~26), ~hich contains a control vaLve ~hich is reguLated through the l~v~l of the liquid in the ev3porator (19). The -:.
a~oun~ of thi~ gaseous 1,2~dichloro~thane is lo~ in compar-ison to the amhunt ~hich is introduced through the heat : . . ~ : . : .. , . : .. , ... : ~ : . :. : : . : ., : :: : :. ::
~326~7 exchanger (5) and only serves to equalize the energy duriny process fluc~ua~ions. From the radiation zone t7~, the hot vinyl chloride-conta;ning gas is fed at a temperature of 523C
to the heat exchan~er (S) through the pipe (9) and leaves the latter at a temperature of 422C through the pipe ~27), which Leads into the apparatus (21~, in ~hich the liquid 1,2-di-chloroethane, ~hich ;s recycled from the evaporator (19~ as described above, is indirectly heated to boiling by the hot : .
vinyl chloride-con~aining gas. The Yinyl chloride-containing ~as leaves the app3ratus (213 through the pipe (28~ at a temperature of 265C, is then cooled as cus~omary and worked up by distillation, the pressure at the top of the distill-ation column in ~hich the hydrogen chloride is removed by distillation being se~ so that the hot vinyl chloride-contain-15 ing gases leave the radiation zone (7) of the cracking furn- ::
ace through the pipe (9~ at a pressure of 1~9 MPa. --28 ~9 of 192-dichloroethane containing solid particles are dra~n off hourly 7rom th~ apparatus ~21) through the pipe (23~ and are freed ~ro~ the solids else~here in the process and re-employed. Th~ four rows of b~rners o~ the cracking ::
furn~ce ar~ supplied through the pipe (8) ~ith a total of 0.075 Nm of fuel (~ethane) per kg of vinyl chloride gener-ated. b75 dm3/h of boiler fe~d water (pressure 2.5 MPa), 25 which is f@d at 1D0C ~hrou~h ~he pipe t30)~ are heated to. .
~50C in the ~pper p~rt ~29) o~ the conYection zone of the cracking furnace in an ~conomizer and are dra~n off through the pipe ~31) and used elsewhere in the process. 317.7 kJ
o~ energy are thereby recovered per kg of vinyl chloride corr~sponding to a t~el (methane~ a~ount of 0.009 Nm3 per kg of vinyl chloride gener~ted. The effectlve fuel con-su~ption is thus reduced to 0.966 N~3 per kg of vinyl chlsride generated.
330 kg/h of vinyl chloride ~r~ produc~d, the sonversion in the crack;ng ~s 68X and the service life of the cracking furnace is 12 months.
Co~parison ~xperiment B
1326~87 Th;s comparison experiment is carried out analogously to Example Z of ~erman Patent Application P 36 34 550.4.
A process is used according to the scheme represented in Fig. 4 834 kg of 1,2-dichloroethane are dra~n off per hour from a pump reservoir (1) and are transported at a temperature of 125C through the heat exchanger ~32~ and through the pipe (33) into the evaporator ~19) by means of a pump.
The heat exchanger ~32) is heated using 25 kglh of high pressure steam ~2.1 MPa pressure; 215C) from ths boiler ~34) through the p;p~ (35~. ~y ~easuring the leveL o7 the liquid 1,2~dichloroethane (LIC) ;n the evaporator t19) as a regulating var;able, the high pressure steanl throughput ~o the heat e~changer (32~ is regulated. The 1,2-dichloro-ethane leave!s the heat exchanger (32) at a temperature of 161~C. .
rhe hot vinyl chloride-containing gas leaves the radiation 20 zon~ ~7) of the cracking turnace at a temperature of 533C : : -throu3h the pip2 (36)~ passes through the apparatus (21) : :
and leaves the l~tter at a temperature of 245C through the pipe (Z8). Following ~his~ the vinyl chloride-containing 9~5 is further cooled by a customary process and hydrogen chloride is r200ved by distillat;sn in a column. The pre~sure at the top o~ this colu~n is r~gulated so that hot vinyL chloride-containing ~as leaves the radiati~n zone ~7) of the craskin~ furnace ~t a pressur~ of 1.9 MPa. Liquid 1~Z-dichLoroethan~, as d~scribed ;n xamp~e 2, is circulated ~ :
30 in the pipes (20) and (22). The gaseous 1,2-d;chloroethane ;s fed into the radiation zon~ (7) of the cracking furnace through the pipe ~37~ from the evaporator (19) 3 30 kg/h of liquid 1,Z-dichloroethane are drawn of~ fro~ the app~r-atus ~21~ through the pipe (23), freed from solids and employed ~ls~h~re in ehe process. The four rows of bur-ners of th~ cracking ~urn~ce located one abov~ the other ar~ suppli~d through the pipe ~8) ~ith a total o~ 0.1074 : Nm3 of ~uel ~ethan~) per kg of vinyl chlorid~ ~enerated. :
330 dm3/h of boiler feed water (pressure 2.5 MPa), which ::
'~. .'.".:
~ 32~7 are fed at 80C through the pipe (39), ar~ heated to 150~C
in the upper part (38) through the convec~ion zone of the cracking furnace in an economizer and par~ly introduced into the boi~er (34) through the piPe (40), and partly reused elsewhere in the vinyl chloride production process through the pipe (41)~ The l;quid from the boiler (34) i5 fed to the lower part (43) of the convection zone of the cracking furnace through the pipe (42), is heated ~here and is fed in~o the boiler (34) through the pipe (44). As already ment;oned above, part of the steam generated ;n the boiler (343 is used for heating the heat exchanger (32). The m3 jori~y of this stea~, namely 167 kg/h, is dra~n off through the pipe (45) and used else~here in the process for the generation o~ vin~l chloride. 1~36.2 kJ
of energy are recovered per ~9 of vinyL chloride. 13b dm3/h of boiler feed ~ater at a tempera~ure of 150C are --fed for further use through the pipe (41~, ~hereby 121 kJ
of energy are recovered per kg of vinyl chloride. The total amount of energy recovered is 1236~2 ~ 121 = 1357.2 20 kJ~kg of vinyl chloride; this corre~ponds to a fuel (m2thane~ amount of a.o3s Nm3/kg of vinyL chLoride. The effective heat;ng ~as consumption is thereby reduced to 0~0694 Nm3/kg; this is 5X more than ~as neces~ary in Exa~ple 2. The cracking furn~ce ~ervice life is 9 months, 2$ 330 kg/h of vinyl chlor;de are produced and tho convers;on in th~ cracking of the 1,2-dichloroe~hane is 65X.
TeGhnic~-grade 1~2-dichloro~thane containing 99O7% by ~eight ot pure 1,2-dich~oroethane i5 employed in 3ll exa~ples and comparison experi~ents, the remainder being Gustomary by-products SUGh 3S trichloroethan2, benzene, tO1-dichloroethane, trichloroathylene, tetrachloroethylene, chloroform~ carb~n tetrachloride and chloroprene.
: '
Claims (9)
1. A process for the production of vinyl chloride by thermal elimination of hydrogen chloride from 1,2-dichloroathane in a cracking furnace which contains a radiation zone, which comprises indirectly warming a gas which contains at least 95% by weight of 1,2-di-chloroethane in a heat exchanger by means of hot vinyl chloride-containing gas, which is drawn off from the radiation zone of the cracking furnace, after pyrolysis and then feeding it into the cracking furnace.
2. The process as claimed in claim 1, where a cracking furnace which contains a radiation and a convection zone is used, wherein the gas containing at least 95%
by weight of 1,2-dichloroethane was generated from liquid 1,2-dichloroethane wholly or partly in the convection zone of the cracking furnace by indirect heat exchange using the exhaust gases.
by weight of 1,2-dichloroethane was generated from liquid 1,2-dichloroethane wholly or partly in the convection zone of the cracking furnace by indirect heat exchange using the exhaust gases.
3. The process as claimed in claim 1, wherein the gas containing at least 95% by weight of 1,2-dichloroethane was generated from liquid 1,2-dichloroethane wholly or partly outside the cracking furnace in an evaporator-
4. The process as claimed in claim 3, wherein the gas containing at least 95% by weight of 1,2-dichloroethane was generated from liquid 1,2-dichloroethane wholly or partly by indirect heat exchange with hot vinyl chloride-containing gas, which was drawn off from the radiation zone of the cracking furnace after pyrolysis of the 1,2-dichloroethane.
5. The process as claimed in claim 4, wherein the hot, vinyl chloride-containing gas, which is drawn off from the radiation zone of the cracking furnace after the pyrolysis, initially warms the gas containing at least 95% by weight of 1,2-dichloroethane in the indirect heat exchange and subsequently generates the gas con-taining at least 95% by weight of 1,2-dichloroethane from liquid 1,2-dichloroethane by another indirect heat exchange.
6. The process as claimed in claim 1, 2 or 3, wherein the gas containing at least 95% by weight of 1,2-dichloroethane is warmed from between 170 and 280°C to a temperature which is at least 50°C under the temperature at which the vinyl chloride-containing gas is drawn off from the radiation zone of the cracking furnace.
7. The process as claimed in claim 4 or 5, wherein the gas containing at least 95% by weight of 1,2-dichloroethane is warmed from between 170 and 280°C to a temperature which is at least 50°C under the temperature at which the vinyl chloride-containing gas is drawn off from the radiation zone of the cracking furnace.
8. The process as claimed in any one of claims 1 to 3, wherein the hot vinyl chloride-containing gas is drawn off from the radiation zone of the cracking furnace at a pressure of 0.5 to 3 MPa.
9. The process as claimed in claim 4 or 5, wherein the hot vinyl chloride-containing gas is drawn off from the radiation zone of the cracking furnace at a pressure of 0.5 to 3 MPa.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3702438.8 | 1987-01-28 | ||
| DE19873702438 DE3702438A1 (en) | 1987-01-28 | 1987-01-28 | METHOD FOR PRODUCING VINYL CHLORIDE BY THERMAL CLEAVING 1,2-DICHLORETHANE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1326687C true CA1326687C (en) | 1994-02-01 |
Family
ID=6319670
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000557498A Expired - Fee Related CA1326687C (en) | 1987-01-28 | 1988-01-27 | Process for the production of vinyl chloride by pyrolysis of 1,2-dichloroethane |
Country Status (14)
| Country | Link |
|---|---|
| EP (1) | EP0276775B1 (en) |
| JP (1) | JP2593905B2 (en) |
| KR (1) | KR950008273B1 (en) |
| BG (1) | BG48808A3 (en) |
| BR (1) | BR8800317A (en) |
| CA (1) | CA1326687C (en) |
| DD (1) | DD267485A5 (en) |
| DE (2) | DE3702438A1 (en) |
| ES (1) | ES2054710T3 (en) |
| HU (1) | HU201722B (en) |
| IN (1) | IN170519B (en) |
| MX (1) | MX167604B (en) |
| PL (1) | PL157275B1 (en) |
| SU (1) | SU1665874A3 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5707592A (en) * | 1991-07-18 | 1998-01-13 | Someus; Edward | Method and apparatus for treatment of waste materials including nuclear contaminated materials |
| DE19859262A1 (en) * | 1998-12-22 | 2000-07-06 | Krupp Uhde Gmbh | Process for the evaporation of 1,2-dichloroethane (EDC) |
| DE10219723B4 (en) | 2002-05-02 | 2005-06-09 | Uhde Gmbh | Process for the preparation of unsaturated halogen-containing hydrocarbons and device suitable therefor |
| DE10326248A1 (en) * | 2003-06-06 | 2004-12-30 | Vinnolit Gmbh & Co. Kg. | Production of vinyl chloride comprises thermal cracking 1,2-dichloroethane in cracking furnace, in which medium pressure is maintained in system by externally heatable and separately regulatable heat exchanger |
| TWI327995B (en) * | 2003-04-11 | 2010-08-01 | Vinnolit Gmbh & Co Kg | Vorrichtung und verfahren zur herstellung von vinylchlorid durch thermische spaltung von 1,2-dichlorethan |
| DE10319811A1 (en) | 2003-04-30 | 2004-11-18 | Uhde Gmbh | Device for coupling electromagnetic radiation into a reactor and reactor containing this device |
| DE102008049261B4 (en) * | 2008-09-26 | 2018-03-22 | Thyssenkrupp Industrial Solutions Ag | Process and apparatus for the preparation of ethylenically unsaturated halogenated hydrocarbons |
| DE102008049262B4 (en) | 2008-09-26 | 2016-03-17 | Thyssenkrupp Industrial Solutions Ag | Process and apparatus for the preparation of ethylenically unsaturated halogenated hydrocarbons |
| DE102008049260B4 (en) * | 2008-09-26 | 2016-03-10 | Thyssenkrupp Industrial Solutions Ag | Process and apparatus for the preparation of ethylenically unsaturated halogenated hydrocarbons |
| DE102011014131A1 (en) * | 2011-03-15 | 2012-09-20 | Thyssenkrupp Uhde Gmbh | Process for drying moist polymer powder and apparatus suitable therefor |
| CN104185768A (en) * | 2012-06-01 | 2014-12-03 | 株式会社吴羽 | Pyrolysis furnace and production method for pyrolysis product |
| DE102019206154A1 (en) * | 2019-04-30 | 2020-11-05 | Thyssenkrupp Ag | Process and plant for the production of vinyl chloride from 1,2-dichloroethane |
| CN113976046B (en) * | 2021-10-22 | 2022-05-03 | 江苏格兰环境科技有限公司 | Novel anti-coking VDF cracking furnace system and using method thereof |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2913030A1 (en) * | 1979-03-31 | 1980-10-16 | Hoechst Ag | Vinyl chloride mfr. - by cleavage of 1,2-di:chloroethane, with recovery of heat from the hot cleavage gases by indirect heat exchange |
| DE2907066A1 (en) * | 1979-02-23 | 1980-09-04 | Hoechst Ag | Vinyl chloride mfr. - by cleavage of 1,2-di:chloroethane, with recovery of heat from the hot cleavage gases by indirect heat exchange |
| DE3061238D1 (en) * | 1979-02-23 | 1983-01-13 | Hoechst Ag | Process for the recovery of pyrolysis energy in the preparation of vinyl chloride by incomplete thermal splitting of 1,2-dichloroethane |
| DE2925720A1 (en) * | 1979-06-26 | 1981-01-22 | Hoechst Ag | METHOD FOR PRODUCING VINYL CHLORIDE BY THERMAL CLEAVING 1,2-DICHLORETHANE |
| JPS6013006B2 (en) * | 1981-02-26 | 1985-04-04 | 日立造船株式会社 | Waste heat recovery method in the production of vinyl chloride monomer |
| DE3440685A1 (en) * | 1984-11-07 | 1986-05-07 | Wacker-Chemie GmbH, 8000 München | METHOD FOR PRODUCING VINYL CHLORIDE BY THERMAL CLEAVING OF PURIFIED 1,2-DICHLORETHANE |
| DE3441080A1 (en) * | 1984-11-09 | 1986-05-15 | Wacker-Chemie GmbH, 8000 München | METHOD FOR PROCESSING THE PYROLYSIS PRODUCT FROM THE 1.2 DICHLORETHANE CLEAVAGE WITH HEAT RECOVERY |
| GB2179938B (en) * | 1986-08-29 | 1989-08-16 | Snam Progetti | Production of monomeric vinyl chloride |
| JPH0692328B2 (en) * | 1986-11-29 | 1994-11-16 | 東ソー株式会社 | Process for producing vinyl chloride monomer by thermal decomposition of 1,2-dichloroethane |
-
1987
- 1987-01-28 DE DE19873702438 patent/DE3702438A1/en not_active Withdrawn
- 1987-12-30 IN IN942/MAS/87A patent/IN170519B/en unknown
-
1988
- 1988-01-22 ES ES88100904T patent/ES2054710T3/en not_active Expired - Lifetime
- 1988-01-22 DE DE8888100904T patent/DE3878701D1/en not_active Expired - Lifetime
- 1988-01-22 EP EP88100904A patent/EP0276775B1/en not_active Expired - Lifetime
- 1988-01-26 BG BG82763A patent/BG48808A3/en unknown
- 1988-01-26 HU HU88290A patent/HU201722B/en not_active IP Right Cessation
- 1988-01-26 DD DD88312438A patent/DD267485A5/en unknown
- 1988-01-27 CA CA000557498A patent/CA1326687C/en not_active Expired - Fee Related
- 1988-01-27 BR BR8800317A patent/BR8800317A/en not_active Application Discontinuation
- 1988-01-27 SU SU4355075A patent/SU1665874A3/en active
- 1988-01-27 PL PL1988270315A patent/PL157275B1/en unknown
- 1988-01-27 JP JP63014811A patent/JP2593905B2/en not_active Expired - Lifetime
- 1988-01-28 KR KR1019880000677A patent/KR950008273B1/en not_active IP Right Cessation
- 1988-01-28 MX MX010237A patent/MX167604B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BR8800317A (en) | 1988-09-06 |
| KR950008273B1 (en) | 1995-07-27 |
| SU1665874A3 (en) | 1991-07-23 |
| PL157275B1 (en) | 1992-05-29 |
| JPS63192729A (en) | 1988-08-10 |
| MX167604B (en) | 1993-03-31 |
| PL270315A1 (en) | 1988-11-24 |
| KR880008966A (en) | 1988-09-13 |
| JP2593905B2 (en) | 1997-03-26 |
| ES2054710T3 (en) | 1994-08-16 |
| HUT45727A (en) | 1988-08-29 |
| DE3702438A1 (en) | 1988-08-11 |
| DD267485A5 (en) | 1989-05-03 |
| EP0276775A3 (en) | 1989-04-19 |
| DE3878701D1 (en) | 1993-04-08 |
| BG48808A3 (en) | 1991-05-15 |
| EP0276775A2 (en) | 1988-08-03 |
| EP0276775B1 (en) | 1993-03-03 |
| IN170519B (en) | 1992-04-04 |
| HU201722B (en) | 1990-12-28 |
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