GB2179938A - Production of monomeric vinyl chloride - Google Patents
Production of monomeric vinyl chloride Download PDFInfo
- Publication number
- GB2179938A GB2179938A GB08620933A GB8620933A GB2179938A GB 2179938 A GB2179938 A GB 2179938A GB 08620933 A GB08620933 A GB 08620933A GB 8620933 A GB8620933 A GB 8620933A GB 2179938 A GB2179938 A GB 2179938A
- Authority
- GB
- United Kingdom
- Prior art keywords
- dichloroethane
- oven
- heat exchange
- tubes
- fluid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 title claims abstract description 10
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 claims abstract description 45
- 239000012530 fluid Substances 0.000 claims abstract description 19
- 238000005336 cracking Methods 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 14
- 239000000178 monomer Substances 0.000 claims abstract description 6
- 238000002485 combustion reaction Methods 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 9
- 238000005235 decoking Methods 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 6
- 239000000446 fuel Substances 0.000 claims description 6
- 238000009835 boiling Methods 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 238000004891 communication Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims 1
- 239000000047 product Substances 0.000 description 19
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000004140 cleaning Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 3
- 239000000571 coke Substances 0.000 description 3
- 238000013021 overheating Methods 0.000 description 3
- 238000009834 vaporization Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000004939 coking Methods 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/24—Stationary reactors without moving elements inside
- B01J19/2415—Tubular reactors
- B01J19/243—Tubular reactors spirally, concentrically or zigzag wound
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J6/00—Heat treatments such as Calcining; Fusing ; Pyrolysis
- B01J6/008—Pyrolysis reactions
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
- B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
- B01J2219/00094—Jackets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
- B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
- B01J2219/00099—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor the reactor being immersed in the heat exchange medium
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
Abstract
A process for the production of vinyl chloride by starting from dichloroethane, wherein dichloroethane is heated, without being vapourized, in the convective section of an oven, it is then vapourized by indirect heat exchange with air or another gaseous fluid, which is heated in its turn by exploiting the heat of the cracking products leaving that oven, and containing monomer vinyl chloride. Dichloroethane, as vapour, is introduced into the radiant section of the oven, wherein it undergoes the cracking and forms vinyl chloride and, if it has been used, a portion of the air heated by the heat of the cracking products can be delivered to the oven burners. Equipment for carrying out the process is described.
Description
SPECIFICATION
Production of monomeric vinyl chloride
The present invention relates to a process for the production of monomer vinyl chloride by means of the cracking of dichlorethane, and to a system suitable to carry out the process.
According to the technology of the prior art for the production of monomer vinyl chloride by the cracking of dichloroethane, this latter is pre-heated, vapourized, overheated and cracked inside one single piece of equipment heated by combustion (oven) and heat exchange by irradiation and convection from the combustion products towards the stream of dichloroethane. According to this technology, the enthalpy contained in the reaction products at the outlet of the oven, at the typical temperatures of from 450 to 550"C, is no longer used in the plant; the stream of outflowing products is quickly cooled to decrease the reaction rate of undesired reactions, but the enthalphy is not recovered to purposes useful to the system.Furthermore, according to the technology of the prior art, the stream of dichloroethane is vapourized inside the same oven, while being in contact with the combustion products at very high temperature, causing the production of dichloroethane breakdown products, among which coke and coal, which act as precursors of formation of further coke and coal in the irradiation section, which in its turn is quickly fouled up to render the oven no longer operable if not to prejudice of its integrity; the equipment must be hence shut off and submitted to the decoking operation to clean the inner surface of the tubes, with a frequency of about 3 - 5 times a year.
A variant of the known technology consists in vapourizing the charge in a heat exchanger external to the oven, by using steam, the consumption of which becomes however a considerable expenditure item among the plant consumptions, by it being always produced at expense of valuable fuels.
It has been surprisingly found that reducing the consumptions of fuel is possible, by using the enthalpy of the efficent from the oven to the purpose of both vapourizing the charge and overheating the combustion air, and that increasing is possible the operating time between two subsequent oven decoking operations, by very quickly cooling the efficent from the oven and vapourizing the charge by a high-temperature source at a temperature lower than of the fumes of the known art.
A first object of the present invention is a process for the production of monomer vinyl chloride by dichloroethane cracking, comprising feeding a stream of dichloroethane to the convective section of an oven, so to heat it up to a temperature lower than its boiling temperature under the pressure used, vapourizing the dichloroethane stream outflowing from the convective section of the oven in an area external to said oven, by indirect heat exchange with a hot gaseous fluid, selected from the oven combustion products, nitrogen and/or air, either alone or as mixtures with one another, heated by indirect heat exchange with the hot dichloroethane breakdown (cracking) products outflowing from said oven, drawing the stream of vapourized dichloroethane from said external area, and introducing it into the radiant section of said oven, the heat in the radiant section being supplied by the combustion of an either liquid or gaseous fuel with a comburent in particular constituted by a portion of the air heated by indirect heat exchange with the hot dichloroethane cracking products outflowing from said oven, if said air has been used as the high-temperature gaseous fluid for indirect heat exchange.
A second object of the present invention is an equipment system suitable to carry out the above disclosed process.
The system being the object the present invention comprises an oven with a radiant section and a convective section, equipped with heaters for either liquid or gaseous fuels, preferably installed in correspondence of the radiant section, the oven being provided in its interior with a first set of tubes in its convective section and with a second set of tubes in its radiant section, the set of tubes in the convective section being connected to pipes for the feed of fresh dichloroethane, and respectively the discharge of dichloroethane heated at a temperature lower than its boiling point, and the set of tubes of the radiant section being connected to pipes for the charging of vapourized dichloroethane, and for the discharging of the dichloroethane cracking products (among which, monomer vinyl chloride), and is characterized in that the tubes for the discharge of heated dichloroethane from the convective section lead to a first heat exchange device for vapourizing the dichloroethane, and that the tubes for the discharge of the dichloroethane cracking products lead to a second heat exchange device, which supplies the heat of the cracking product to a fluid, said fluid supplying in its turn heat to said first heat exchange device through a duct which places in said first and said second heat exchange devices in communication with each other, said duct being equipped with a burner for the initial heating of the fluid (in the absence of the cracking products) and for the possible decoking, and with a fluid circulator, the duct being furthermore provided with a pipe for the possible discharging of the fluid, and connected to a pipe for the delivery of the fluid, if air, as the comburent to the burners of the radiant section of the oven.
In a variant of the system of the present invention, the pipes supplying the heated dichloroethane to the first heat exchange device lead first to a separator, by which the dichloroethane vapour is separated from the liquid dichloroethane, which is continuously recycled by a pump through the said first heat exchange equipment and through said separator, the separator allowing also the possibly coked products to be separated.
The invention is now described with reference to the attached drawings, which are not to be intended as being limitative of the same' invention.
Figure 1 represents a whole equipment system suitable to carry out the process according to the invention.
Figure 2 shows the equipment system of
Fig. 1, with the variant of the recycling of the dichloroethane stream through the vapourizing equipment of the same, and through a separator of liquid dichloroethane from dichloroethane vapour, and from the coking products.
Figure 3 represents the structural details of the heat exchangers used for recovering the heat from the decomposition products which outflow from the oven, and for dichloroethane vapourization.
Reference shall be now made to Figs. 1, 2 and 3.
The oven (1) is composed by a convective section (2) wherein the liquid charge (3) of dichloreoethane is preheated; this stream is preheated up to a temperature lower than its boiling point under the pressure corresponding to the outlet from the convective section, and hence remains in the liquid phase. The preheating takes place by means of the sensible heat of the products of combustion, which is carried out in the radiant section (4) of the oven to supply the heat for the overheating and the reaction of cracking of dichloroethane (5), which is recycled to the radiant section in the vapour phase. The products of reaction (6) leave the radiant zone at a temperature generally comprised within the range of from 450 to 5500C.The preheating, the overheating and the reaction occur by heat transfer through tubes (7) and (8) suitably positioned in the radiant section and in the convective section.
The burners (9) can be installed either on the side walls, or on the crown and/or in the bedplate of the oven.
The sensible heat of the products of the reaction (6) is drawn in the refrigerator (10) and is transferred to the evaporator (11), wherein the vapourization of the charge previously preheated in the convective section (2) (8) of the over is made take place. The fluid used to transfer heat from (10) to (11) is air, drawn from the atmosphere, or nitrogen, drawn from the plant system and circulated in system (12) by the fan (13).
By the dotted line in Figs, 1 and 2 indicated has been the possible feed of the combustion products of the oven to the system (12).
The exchangers (10) and (11) are similar in structure to each other, and are constituted by the following components, as illustrated at Fig.
3:
Tube bundle constituted by finned tubes (1) with either cut or continuous fins having a height of up to 50 mm, a thickness comprised within the range of from 0.4 to 1.2 mm, and a density of up to 450 fins per metre, preferably of from 240 to 320 fins per. metre; the tubes with nominal diameter of up to 10 inches are preferably connected to each other so to maintain the same number of passages on process side as inside the oven; the connection bends can be welded to the tubes, or they can be connected to the tubes by a flanged connection, which allows the access to the interior of the tubes, to carry out the mechanical cleaning, as indicated in Fig. 3, find number (2).
In Fig. 3A, details of types of fins are shown.
The tube-containing outer housing is tightly sealed relatively to the inner and to the outer pressure, and can be internally insulated by insulating and refractory materials, or it can be externally insulated by insulating materials. The inner coating is provided for the case in which the cleaning of the inner surfaces of the tube nest is carried out by the operation of decoking by air and steam, in which case the temperature of air surrounding the tube nest is increased up to the values typical for the execution of decoking operation, by means of the burner (14) installed in the fan (13) delivery duct.
The burner (14) is preferably of the multiflame gas burner type tubed inside the delivery duct (15) of fan (13), and supplies the heat for the decoking operation and for contributing to the starting up of the system.
The exchangers (10) and (11) are provided with a perforated distribution plate, air side, for the uniform distribution of the same air throughout the passage area.
The circulating air, which is heated in the exchanger (10) up to typical values of 200 500"C, releases its heat in exchanger (11) wherein, on tubes side, the vapourization of the dichloroethane charge occurs under less severe temperature conditions than it would find in the convective section of oven (2) and with higher exchange coefficient.
This exchanger allows hence a reduction to be achieved in fouling due to the breakdown and production of precursors of coke formation and allows consequently a longer operating time to be obtained between two subsequent cleaning operations.
The air circulation duct (12) is provided with a bypass stack (16) to be used during the decoking operations, installed downstream (10) or (11), as required by the cleaning needs.
From the same air circulation duct (12), a line (17) is branched, which conveys the preheated combustion air to the oven burners (9), which can be either of natural draught or of forced draught type, and can hence be fed with air under a pressure ranging from atmospheric pressure to some hundred water millimetres, typically 150-250 mm H20 gauge pressure. The combustion air is typically at the temperature of 200-500"C, relatively to the amount circulated, to obtain the closure of the heat balance of exchangers (10) and (11).
In Fig. 2 the stream of dichloroethane, heated in (2) in the tube (8), is fed to a separator (18), vapour being obtained which is recycled to the oven through (5), as well as liquid which, through the pipe (19) is fed to pump (20), is then circulated via (21) through the vapourizer (11) and from here is passed through the separator (18), from which the coking products (22) are discharged.
Claims (11)
1. Process for the production of monomer vinyl chloride by dichloroethane cracking, characterized in that a stream of dichloroethane is fed to the convective section of an oven, so to heat it up to a temperature lower than its boiling temperature, the dichloroethane stream outflowing from the convective section of the oven is vapourized in an area external to said oven by indirect heat exchange with a gaseous fluid heated by indirect heat exchange with the hot dichloroethane cracking products outflowing from said oven, the stream of vapourized dichloroethane is drawn from said outer area, and is introduced into the radiant section of said oven.
2. Process according to claim 1, characterized in that the gaseous fluid is air.
3. Process according to claim 1, characterized in that the gaseous fluid is constituted by the combustion products from the oven.
4. Process according to claim 1, characterized in that the gaseous fluid is constituted by nitrogen.
5. Process according to claim 1 and 2, characterized in that the hot air is partly used for the combustion of a liquid or gaseous fuel for supplying heat to the radiant section of the oven.
6. Equipment system for carrying out the process according to claims from 1 to 5, comprising an oven with a radiant section and a convective section, equipped with heaters for either liquid or gaseous fuels, the convective section containing a first set of tubes, and the radiant section containing a second set of tubes, wherein the first set of tubes of the convective section is connected to pipes for the feed of fresh dichloroethane, and discharge into other pipes of the dichloroethane heated at a temperature lower than its boiling point, and wherein the second set of tubes is connected to pipes for the charging of vapourized dichloroethane, and for the discharging of the dichloroethane cracking products, characterized in that the pipes for the discharging of heated dichloroethane from the convective section lead to a first heat exchange device for vapourizing dichloroethane, that the pipes for the discharging of the dichloroethane cracking products lead to a second heat exchange device, which supplies the heat of the cracking product to a fluid circulating inside a duct which places said said first heat exchande device and said second heat exchange device in communication with each other, said duct being equipped with a burner for the initial heating of the fluid and for the possible decoking, and with a fluid circulator, the duct being furthermore provided with a pipe for the possible discharging of the fluid.
7. Equipment system according to claim 5, characterized in that the duct is connected to a pipe for the delivery of the fluid, if air, as the comburent to the burners of the radiant section of the oven.
8. Equipment system according to claims 6 and 7, characterized in that the pipes leading the heated dichloroethane to the first heat exchange device lead first to a separator for the separation of the vapours of dichloroethane from the liquid, which is recycled by a pump through said first heat exchange device, and said separator, the separator also allowing the possibly coked products to be separated.
9. Equipment system according to claim 6, characterized in that the first heat exchange device and the second heat exchange device have a tube bundle constituted by finned tubes with either cut or continuous fins having a height of up to 50 mm, a thickness comprised within the range of from 0.4 to 1.2 mm and a density of up to 450 fins per metre, the tubes having a nominal diameter of up to 10 inches.
10. Equipment system according to claim 9, characterized in that the density of the fins is comprised within the range of from 240 to 320 per metre.
11. Equipment system according to claim 9, characterized in that the finned tubes are connected to each other by a flanged connection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8620933A GB2179938B (en) | 1986-08-29 | 1986-08-29 | Production of monomeric vinyl chloride |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8620933A GB2179938B (en) | 1986-08-29 | 1986-08-29 | Production of monomeric vinyl chloride |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8620933D0 GB8620933D0 (en) | 1986-10-08 |
| GB2179938A true GB2179938A (en) | 1987-03-18 |
| GB2179938B GB2179938B (en) | 1989-08-16 |
Family
ID=10603399
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8620933A Expired GB2179938B (en) | 1986-08-29 | 1986-08-29 | Production of monomeric vinyl chloride |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2179938B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0270007A2 (en) * | 1986-11-29 | 1988-06-08 | Tosoh Corporation | Process for producing vinylchloride monomer by pyrolysis of 1,2-dichloroethane |
| EP0276775A2 (en) * | 1987-01-28 | 1988-08-03 | Hoechst Aktiengesellschaft | Method for the production of vinyl chloride by pyrolysis of 1,2-dichloroethane |
| FR2791055A1 (en) * | 1999-03-19 | 2000-09-22 | Krebs Speichim | PROCESS AND UNIT FOR PRODUCING VINYL CHLORIDE THERMAL CRACKING OF 1,2-DICHLOROETHANE |
-
1986
- 1986-08-29 GB GB8620933A patent/GB2179938B/en not_active Expired
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0270007A2 (en) * | 1986-11-29 | 1988-06-08 | Tosoh Corporation | Process for producing vinylchloride monomer by pyrolysis of 1,2-dichloroethane |
| EP0270007A3 (en) * | 1986-11-29 | 1989-04-19 | Tosoh Corporation | Process for producing vinylchloride monomer by pyrolysis of 1,2-dichloroethane |
| EP0276775A2 (en) * | 1987-01-28 | 1988-08-03 | Hoechst Aktiengesellschaft | Method for the production of vinyl chloride by pyrolysis of 1,2-dichloroethane |
| EP0276775A3 (en) * | 1987-01-28 | 1989-04-19 | Hoechst Aktiengesellschaft | Method for the production of vinyl chloride by thermal dissociation of 1,2-dichloroethane |
| FR2791055A1 (en) * | 1999-03-19 | 2000-09-22 | Krebs Speichim | PROCESS AND UNIT FOR PRODUCING VINYL CHLORIDE THERMAL CRACKING OF 1,2-DICHLOROETHANE |
| WO2000056686A1 (en) * | 1999-03-19 | 2000-09-28 | Technip France | Method and unit for producing vinyl chloride by thermal cracking of 1,2-dichloroethane |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8620933D0 (en) | 1986-10-08 |
| GB2179938B (en) | 1989-08-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19990829 |