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
  • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J19/087—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
  • B01J19/088—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
• • 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
  • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
• • 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
• • 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
• • 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
• • 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
• • 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
  • B01J2219/00157—Controlling the temperature by means of a burner
• • 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
  • B01J2219/00191—Control algorithm
  • B01J2219/00222—Control algorithm taking actions
  • B01J2219/00227—Control algorithm taking actions modifying the operating conditions
  • B01J2219/0024—Control algorithm taking actions modifying the operating conditions other than of the reactor or heat exchange system
• • 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
  • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J2219/0894—Processes carried out in the presence of a plasma

Definitions

• the present invention relates to a particularly gentle process and a device suitable for the production of ethylenically unsaturated
• Halogen compounds by thermal cleavage of halogenated aliphatic hydrocarbons, in particular the production of vinyl chloride by thermal cleavage of 1, 2-dichloroethane.
• VCM vinyl chloride
• EDC 1,2-dichloroethane
• VCM is mainly produced by thermal cleavage of EDC, with the implementation of the equation
• reaction tube which in turn is arranged in a gas or oil fired furnace.
• the reaction is usually allowed to proceed to a conversion of 55-65%, based on the EDC used (in the following Feed-EDC).
• the temperature of the furnace leaving the reaction mixture (hereinafter furnace outlet temperature) is about 480 - 520 0 C.
• the reaction is operated under pressure. Typical pressures at the inlet of the furnace amount to approx. 13-30 bar abs in today's processes.
• VCM is increasingly converted into secondary products such as acetylene and benzene, which in turn are precursors of coke deposits.
• the formation of coke deposits necessitates the shutdown and cleaning of the reactor at regular intervals.
• a conversion of 55%, based on the EDC used has proven to be particularly advantageous in practice.
• the reaction tube is arranged centrally as a coil constructed of vertically stacked horizontal tubes, wherein the coil can be made one or two-speed.
• the tubes can be arranged either in alignment or offset.
• the furnaces are heated by burners arranged in rows in the furnace walls.
• the heat transfer to the reaction tubes is predominantly by wall and gas radiation, but also convective by the resulting during heating by burner flue gas.
• the EDC cleavage is carried out in other furnace types, with different arrangement of the reaction tubes and the burner.
• the invention is in principle applicable to all furnace types and burner arrangements as well as to other ways of heating the reaction.
• a typical tube reactor used for EDC cleavage comprises a furnace and a reaction tube.
• a furnace fired with a primary energy source such as oil or gas, is divided into a so-called radiation zone and a convection zone.
• the heat required for the cleavage is transferred to the reaction tube mainly by radiation from the burner-heated furnace walls and the hot flue gas.
• the energy content of the hot, emerging from the radiation zone flue gases is used by convective heat transfer.
• the starting material of the cleavage reaction for example EDC
• EDC can be preheated, evaporated or superheated.
• the generation of water vapor and / or the preheating of combustion air is possible.
• liquid EDC is first preheated in the convection zone of the cracking furnace and then evaporated in a special evaporator outside the cracking furnace.
• the vaporous EDC is then in turn fed to the convection zone and overheated there, which can already use the cleavage reaction. After overheating, the EDC enters the radiation zone, where the conversion to vinyl chloride and hydrogen chloride takes place.
• the burners are usually arranged on the longitudinal and front sides of the furnace in superimposed rows, wherein the aim is to achieve the most uniform distribution of heat radiation along the circumference of the reaction tubes by the type and arrangement of the burner.
• the part of the furnace in which the burners and the reaction tubes are arranged and in which the predominant conversion of the cleavage reaction takes place is called
• reaction zone in the context of the invention, the reaction tubes located in the flow direction of the reaction gas following the shock zone, the preferably vertically aligned or staggered one above the other, to understand.
• EDC electrospray
• the actual cleavage reaction takes place in the gaseous state of matter.
• the EDC is first preheated and then evaporated and possibly overheated.
• the vaporous EDC enters the reactor, where it is usually heated further in the shock pipes and finally enters the reaction zone, where at temperatures above about 400 0 C, the thermal cracking reaction begins.
• the heat of the hot smoke gas leaving the radiation zone is utilized in the convection zone, which adjoins the radiation zone and is arranged spatially above it by convective heat transfer, wherein, for example, the following operations can be carried out:
• the apparatus combination of radiation and convection zone with the associated flue gas chimney is called by the expert cracking furnace.
• the use of the heat content of the flue gas, for example, for the preheating of the EDC, is of central importance for the efficiency of the process, as a As complete as possible utilization of the heat of combustion of the fuel must be sought.
• the reaction mixture leaving the cracking furnace contains, in addition to the desired product VCM, also HCl (hydrogen chloride) and unreacted EDC. These are separated in subsequent process steps and returned to the process or further utilized. Furthermore, the reaction mixture contains by-products, which are also separated, worked up and further recycled or recycled back into the process. These relationships are known in the art.
• the by-products coke and tarry substances that arise over several reaction steps from low molecular weight by-products such as acetylene and benzene and settle in the coils of the cracking furnace (and in downstream equipment such as the EDC evaporator), where they a deterioration in the heat transfer, and, over the narrowing of the free cross-section, lead to an increase in the pressure loss.
• the sensible heat of the cracked gas can be used to vaporize the feed EDC.
• the cracking gas is washed in a so-called quench column by direct contact with a cool, liquid recycle or circulating stream and further cooled.
• This has, above all, the purpose of washing out coke particles contained in the cracking gas or of condensing vapor-like tarry substances and likewise of washing them out, since both components would interfere in the subsequent work-up steps.
• the cleavage gas is fed to a work-up by distillation in which the components hydrogen chloride (HCl), VCM and EDC are separated from one another.
• this work-up stage generally comprises at least one column which is operated under pressure and is recovered in pure HCl as the top product (hereinafter HCI column).
• the thermal EDC cleavage is a radical chain reaction whose first step is the cleavage of a chlorine radical from an EDC molecule:
• heterogeneous catalyst allows cleavage of a chlorine radical from the EDC molecule, e.g. by dissociative adsorption of the EDC molecule on the catalyst surface.
• very high EDC conversions can be achieved.
• decomposition of the VCM and thus coke formation on the catalyst surface occurs which leads to rapid deactivation of the catalyst. Due to the frequent regeneration required thereby, heterogeneous catalysts have hitherto not found entry into the large-scale production of VCM.
• Chemical initiators either a chlorine atom is cleaved from the EDC molecule by reaction of the EDC with the initiator, or the chlorine radicals are provided by decomposition of the initiator.
• Chemical initiators are, for example, elemental chlorine, bromine, iodine, elemental oxygen, chlorine compounds such as carbon tetrachloride (CCI 4 ), or chlorine-oxygen compounds such as hexachloroacetone.
• Cleavage gas is metered in after exit from the cracking furnace, that is, in the post-reaction zone.
• the heat content of the fission gas is utilized in order to increase the total conversion of the EDC cleavage.
• this method is inferior measures to increase the space-time yield in the cracking furnace itself, since only after the exit from the cracking furnace in the gap gas stream still contained heat can be utilized and the usable amount of heat is limited when the heat of the cracked gas stream to evaporate the feed -EDC should be used.
• DE 102 19 723 A1 relates to a process for the addition of cleavage promoters in the preparation of unsaturated halogen-containing hydrocarbons. This document does not disclose details of the thermal design of the reactor.
• DE 10326248 A1 describes an energy optimization in the production of vinyl chloride by splitting DCE and exploiting the energy contents in the exhaust gas stream. This document does not describe the use of cleavage promoters nor electromagnetic radiation. Also, this document contains no reference to the combined measures a) to d) described below.
• DE 1908 624 A discloses a tube furnace for the thermal cracking of hydrocarbons. A use of cleavage promoters or of locally limited energy supply is not described.
• the object of the present invention is to provide a reactor in which the thermal decomposition of halogenated aliphatic hydrocarbons can be realized at substantially lower temperatures but comparable efficiency in comparison with conventional systems. It is another object of the present invention to provide a process for the thermal cracking of halogenated aliphatic hydrocarbons which can operate at substantially lower temperatures than conventional processes without sacrificing the efficiency of the process.
• the invention relates to a process for the thermal cleavage of halogenated aliphatic hydrocarbons into ethylenically unsaturated halogenated hydrocarbons in a reactor which comprises reaction tubes extending through a convection zone and through a radiation zone arranged downstream in the flow direction of the reaction gas, characterized in that a) the reaction tubes are a chemical promoter is supplied for thermal cleavage and / or within the reactor at one or more locations a localized energy supply for the formation of radicals in the reaction tubes is carried out, b) a part of the total underfeuerten heat output by burner in the
• the invention further relates to a device for the thermal cleavage of halogenated aliphatic hydrocarbons to ethylenically unsaturated halogenated hydrocarbons
• a device for the thermal cleavage of halogenated aliphatic hydrocarbons to ethylenically unsaturated halogenated hydrocarbons comprising a reactor comprising reaction tubes extending through a convection zone and a radiation zone arranged downstream in the direction of flow of the reaction gas, with the elements:
• the radiation zone of the cracking furnace is heated less than in non-inventive method, both amount and temperature of the flue gas emerging from the radiation zone, lower than in prior art methods. From a certain reduction of underfeuerten power in the radiation zone is therefore not enough heat available to meet the procedural tasks of the convection zone, especially the preheating of EDC.
• the fuel gas supply to the burners of the radiation zone and the burners at the smoke gas inlet into the convection zone is preferably separately controllable.
• Heat exchanger condenses and the waste heat of the flue gas is used to preheat the burner air.
• the heat exchange takes place in measure f) preferably at the outlet of the flue gas from the convection zone.
• the method according to the invention can include the measures e) or f) or a combination of the measures e) and f).
• the method according to the invention preferably comprises the measure e).
• Measure e is used in particular for fuels with a medium or high proportion of acid-forming components. This measure can also be at Fuels are used with a low proportion of acid-forming components.
• Measure f is used in particular for fuels with a low proportion of acid-forming components. However, this measure can also be used for fuels with a medium or high proportion of acid-forming components.
• E means for controlling the amount of fuel and / or for controlling the addition amount of the chemical promoter and / or for controlling the intensity of the localized energy supply, wherein the dew point of the flue gas on
• Outlet of the convection zone or in the flue gas chimney serves as a reference variable for the control.
• At least one heat exchanger for the recovery of waste heat from the condensation of the flue gas for the preheating of the combustion air or other media, e.g. EDC.
• the method according to the invention is described by way of example on the system EDC / VC. It is also suitable for the preparation of other halogen-containing unsaturated hydrocarbons from halogen-containing saturated hydrocarbons. All these reactions have in common that the cleavage is a radical chain reaction, in addition to the desired product unwanted by-products are formed, which lead to a coking of plants in continuous operation. Preferably, the preparation of vinyl chloride from 1, 2-dichloroethane.
• localized energy input for the formation of radicals in the reaction tubes in the context of this description, those physical measures are to be understood which are capable of initiating the cleavage reaction. It may be z. B. to the coupling of high-energy electromagnetic radiation, the local supply of thermal or non-thermal plasmas, such as hot inert gases.
• Means for supplying chemical promoters for the thermal cleavage together with the halogenated aliphatic hydrocarbon in the reaction tubes are known in the art. These may be feed lines which allow the introduction of predetermined amounts of chemical promoters into the feed gas stream, which is then fed to the reactor. However, they can also be supply lines which allow the introduction of predetermined amounts of chemical promoters into the reaction tubes, for example at the level of the convection zone and / or at the level of the radiation zone. These feed lines may have nozzles at the reactor end. One or more of these feed lines preferably open into the radiation zone, very particularly preferably in the direction of flow of the reaction gas in the first third of the radiation zone into the pipelines.
• Means for supplying locally limited energy to form radicals in the reaction tubes are also known to those skilled in the art.
• These may also be supply lines, which optionally have nozzles at the reactor end, via which thermal or non-thermal plasma at the level of the convection zone and / or at the height of the radiation zone is conducted into the reaction tubes; or it can be windows, via which electromagnetic radiation or particle radiation is coupled into the reaction tubes.
• the supply lines or windows may be in the height of the convection zone and / or in the height of the radiation zone in the reaction tubes open / mounted in the reaction tubes.
• one or more of these feed lines open in the direction of flow of the reaction gas in the first third of the radiation zone into the pipelines; or in the first third of the radiation zone, the windows are mounted for coupling the radiation.
• the amount of the chemical promoter and / or the intensity of the localized energy supply is to be selected in the individual case so that at the given internal reactor temperature of the desired molar conversion of the cleavage reaction is also achieved.
• Means for selecting the amount of the chemical promoter and / or the intensity of the localized energy supply to form radicals in the reaction tubes are also known in the art. These are generally control loops in which a leader is used to control the quantity or intensity. As guide variables, all process parameters can be used, with the help of which the molar conversion of the cleavage reaction can be concluded. Examples include the temperature of the exiting reaction gases, the content of cleavage products in the reaction gases or the wall temperature of the reaction tubes at selected locations.
• electromagnetic radiation of a suitable wavelength or particle radiation is irradiated at one or more points of the shock tubes or tubes in the reaction zone or a chemical promoter is added or a combination of these measures takes place.
• a chemical promoter the addition may preferably also be made in the feed line of the gaseous feed, for example to the EDC from the EDC evaporator, for entry into the cracking furnace.
• the localized energy supply for the formation of radicals by electromagnetic radiation or by particle radiation is effected; This is particularly preferably ultraviolet laser light.
• the chemical promoter may be diluted with a gas that is inert with respect to the cleavage reaction, with the use of hydrogen chloride being preferred.
• the amount of inert gas used as diluent should not exceed 5 mol% of the feed stream.
• the intensity of the electromagnetic radiation or the particle radiation or the amount of the chemical promoter is adjusted so that at the intended reactor internal temperature of the molar conversion, based on the feed, at the gap-side outlet of the feed evaporator is between 50 and 65%, preferably between 52 and 57%.
• the temperature of the reactor leaving the reaction mixture is preferably between 400 0 C and 470 0 C.
• the inventive method is particularly preferably used for the thermal cleavage of 1,2-dichloroethane to vinyl chloride.
• the evaporation of the liquid feed, for example of the liquid EDC, before entry into the radiation zone is still another process step made of the cracking furnace.
• a preferred embodiment of the invention is directed to a process in which the sensible heat of the fission gas is utilized to provide liquid, preheated feed, e.g. EDC to evaporate before entering the radiation zone, wherein preferably a heat exchanger is used, as has already been described in EP 276,775 A2. It is particularly important to ensure that on the one hand the fission gas is still hot enough when leaving the cracking furnace to evaporate with its sensible heat content, the total amount of the feed and that on the other hand, the temperature of the fission gas does not fall below a minimum value when entering this heat exchanger, to prevent the condensation of tarry substances in the heat exchanger tubes.
• the sensible heat of the fission gas is utilized to provide liquid, preheated feed, e.g. EDC to evaporate before entering the radiation zone, wherein preferably a heat exchanger is used, as has already been described in EP 276,775 A2. It is particularly important to ensure that on the one hand the fission gas is still hot enough when leaving the cracking furnace to evaporate with its sensible heat
• the temperature of the cracking gas at the outlet from the cracking furnace is so low that the heat content of the cracking gas is insufficient to completely vaporize the feed.
• the missing portion of vaporous feed is produced by flash evaporation of liquid feed into a container, preferably in the Ausdampfgefäß a heat exchanger, as described in EP 276,775 A2.
• the preheating of the liquid feed takes place advantageously in the convection zone of the cracking furnace.
• care must be taken that the temperature of the fission gas does not fall below a minimum value when entering this heat exchanger in order to prevent the condensation of tarry substances in the heat exchanger tubes.
• the heat content of the fission gas is used in this preferred process variant to evaporate by indirect heat exchange at least 80% of the feed used, without the fission gas thereby partially or completely condensed.
• a heat exchanger an apparatus is preferably used, as described for example in EP 264.065 A1.
• liquid halogenated aliphatic hydrocarbon with the hot, containing the ethylenically unsaturated halogenated hydrocarbon product gas leaving the reactor indirectly heated, evaporated and introduced the resulting gaseous educt gas into the reactor, wherein the liquid halogenated aliphatic hydrocarbon in a first container with the product gas is heated to boiling and transferred from there to a second container in which it is partially evaporated without further heating at a lower pressure than in the first container, the vaporized educt gas fed into the reactor and the unvaporized halogenated aliphatic hydrocarbon in the first Container is returned.
• the halogenated aliphatic hydrocarbon is heated prior to feeding into the second vessel in the convection zone of the reactor with the flue gas which produces the burner heating the reactor.
• Particularly preferred is a procedure in which the entire feed used is vaporized by indirect heat exchange with the cleavage gas, without the cleavage gas thereby partially or completely condensed.
• the residual amount of feed is preferably evaporated by flash evaporation in a container, wherein the feed is previously preheated in the liquid state in the convection zone of the cracking furnace.
• a container for flash evaporation while the Ausdampfgefäß a heat exchanger is preferably used, as he z. As described in EP 264.065 A1.
• the temperature of the reaction gas entering into the heating device arranged outside the reactor is measured and serves as a reference variable for the regulation of the addition amount of the chemical promoter and / or for the intensity of the local limited energy intake.
• other measured variables can be used as a reference variable, for example, the content of products of the cleavage reaction.
• Cleavage reaction downstream after the exit of the cracked gas from the EDC evaporator or at the top of the quench column determined, for example with an on-line analyzer, preferably by means of an online gas chromatograph.
• the flue gas is sucked off after leaving the convection zone by a flue gas blower and transferred into one or more heat exchangers, where it is condensed.
• the waste heat is used to heat the burner air.
• the resulting condensate is optionally worked up and discharged from the process.
• the remaining gaseous constituents of the flue gas are optionally purified and discharged into the atmosphere.
• the amount of fuel can be distributed both to unequal parts and preferably in equal parts on the rows of burners of the furnace.
• the economy of the process is also influenced by the sum of the pressure losses of the cracking furnace (consisting of convection and radiation zone), the heat exchanger for the evaporation of the feed and any quenching system ("quench column") in the distillative separation of cleavage products they must be condensed at the top of a column, wherein used for cooling the condenser, a chiller becomes.

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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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• 2008
  • 2008-09-26 DE DE102008049261.2A patent/DE102008049261B4/de active Active
• 2009
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  • 2009-09-03 CN CN200980137992XA patent/CN102203036A/zh active Pending
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