WO2024110316A1 - Four - Google Patents

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Publication number
WO2024110316A1
WO2024110316A1 PCT/EP2023/082094 EP2023082094W WO2024110316A1 WO 2024110316 A1 WO2024110316 A1 WO 2024110316A1 EP 2023082094 W EP2023082094 W EP 2023082094W WO 2024110316 A1 WO2024110316 A1 WO 2024110316A1
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WO
WIPO (PCT)
Prior art keywords
furnace
gas
cabin
recirculation loop
heating
Prior art date
Application number
PCT/EP2023/082094
Other languages
English (en)
Inventor
Paul Degraeve
Roel MILIS
Original Assignee
Inovyn Europe Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Inovyn Europe Limited filed Critical Inovyn Europe Limited
Publication of WO2024110316A1 publication Critical patent/WO2024110316A1/fr

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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
    • B01J6/00—Heat treatments such as Calcining; Fusing ; Pyrolysis
    • B01J6/008—Pyrolysis reactions
    • 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
    • B01J19/2425—Tubular reactors in parallel
    • 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
    • B01J19/2455—Stationary reactors without moving elements inside provoking a loop type movement of the reactants
    • B01J19/2465—Stationary reactors without moving elements inside provoking a loop type movement of the reactants externally, i.e. the mixture leaving the vessel and subsequently re-entering it
    • 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
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
    • B01J8/06—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds in tube reactors; the solid particles being arranged in tubes
    • B01J8/062—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds in tube reactors; the solid particles being arranged in tubes being installed in a furnace
    • 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
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G9/24—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils by heating with electrical means
    • 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
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00106—Controlling the temperature by indirect heat exchange
    • B01J2208/00265—Part of all of the reactants being heated or cooled outside the reactor while recycling
    • 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
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00389—Controlling the temperature using electric heating or cooling elements
    • B01J2208/00415—Controlling the temperature using electric heating or cooling elements electric resistance heaters
    • 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
    • B01J2219/00076—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements inside the reactor
    • 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
    • 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
    • B01J2219/00132—Controlling the temperature using electric heating or cooling elements
    • 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
    • B01J2219/00132—Controlling the temperature using electric heating or cooling elements
    • B01J2219/00135—Electric resistance heaters
    • 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
    • B01J2219/00186—Controlling or regulating processes controlling the composition of the reactive mixture

Definitions

  • the present invention relates to an electrically heated furnace (and which as used herein may also be referred to a reactor), particularly a furnace for chemical reaction, for example for cracking of hydrocarbons such as ethane, naphtha and 1,2-dichloroethane.
  • the present invention also relates to an electrically heated furnace used for heating-up petroleum or chemical products or for gas processing.
  • Furnaces for cracking of hydrocarbons such as ethane, naphtha, 1,2-dichloroethane and others are well-known.
  • the reaction has been performed by passing the reactant hydrocarbon through an externally heated reaction tube located within a furnace to provide the heating for the endothermic cracking reaction.
  • the heat required has been obtained by combustion of a fuel in burners located inside the furnace.
  • the present invention provides an electrically heated furnace, the furnace comprising: a. A furnace cabin, the furnace cabin comprising: i. one or more process tubes which extend through the furnace cabin, ii. a plurality of electrically powered heating means located inside the furnace cabin for heating the one or more process tubes, iii. one or more gas inlets, iv. one or more gas outlets, characterised in that the furnace further comprises: b. An external recirculation loop which connects the one or more gas outlets of the furnace cabin to the one or more gas inlets of the furnace cabin, c. At least one gas analyser or detector and/or at least one pressure monitor for measurement of pressure provided on the external recirculation loop.
  • the present invention provides an electrically heated furnace, the furnace comprising: a. A furnace cabin, the furnace cabin comprising: i. one or more process tubes which extend through the furnace cabin, ii. a plurality of electrically powered heating means located inside the furnace cabin for heating the one or more process tubes, iii. one or more gas inlets, iv. one or more gas outlets, characterised in that the furnace further comprises: b. An external recirculation loop which connects the one or more gas outlets of the furnace cabin to the one or more gas inlets of the furnace cabin, c. One or more heaters for heating the gas in the external recirculation loop.
  • the present invention in both the first and second aspects, provides an electrically heated furnace.
  • the furnace comprises a furnace cabin, which comprises one or more process tubes which extend through the furnace cabin.
  • reactants to be reacted are passed through the inside of the process tubes.
  • the process tube or tubes are heated, and thereby the reactants passing through the process tube or tubes are heated and caused to react.
  • Furnaces of this general structure albeit using other heating means, are known for a variety of different chemical processes, including for heating-up petroleum or chemical products or for gas processing.
  • the process tube or tubes may, for example, each be a single straight tube which passes once through the furnace cabin.
  • the process tube or tubes may, for example, have several straight sections within the furnace, linked by elbows or 180° bends e.g. to form a serpentine structure.
  • furnaces for the process of the present invention are furnaces for cracking of hydrocarbons such as ethane, naphtha and 1 ,2-dichloroethane.
  • the process tube or tubes are electrically heated.
  • a plurality of electrically powered heating means located inside the furnace cabin for heating the one or more process tubes. Any suitable heating means may be provided.
  • the plurality of electrically powered heating means may be a plurality of electrically powered heating elements, in particular located on the walls inside the furnace cabin.
  • the plurality of electrically powered heating means may be a plurality of heating coils, in particular each being provided in the furnace cabin adjacent to one or more process tubes.
  • the plurality of electrically powered heating means may be means by which a process tube or tubes are directly electrically heated. Combinations of different heating means may also be used, including combinations of the above examples.
  • the furnace generally will comprise an electricity supply means located outside the furnace cabin for providing electricity to the electrically powered heating means.
  • An issue with electrically heated furnaces is that this requires provision of electrical energy into a furnace which is not only at high temperatures, but where the external environment outside of the furnace is a hazardous “ATEX” area.
  • ATEX generally refers to an area in which there is, or is a risk of, the presence of flammable gases which can give rise to the risk of explosion.
  • An example of a suitable system can be found in WO 2021/214256, which provides movable current feed elements.
  • the electricity supply means may utilise one or more hermetically sealed boxes (and which as used herein may also be referred to as “ATEX boxes”) which boxes are connected externally to the furnace cabin.
  • the electrical connection to the heating means may be provided by one or more electrical connecting rods or other connections which pass through the wall of the hermetically sealed box and of the furnace.
  • the furnace cabin in the present invention also comprises one or more gas inlets and one or more gas outlets. In general, there may be a plurality of inlets and/or a plurality of outlets.
  • the one or more gas inlets and one of more gas outlets provide, respectively, for introduction and removal of a gas from the furnace cabin, and in particular from to and from the volume of the furnace cabin which is outside of the one or more process tubes.
  • the one or more gas inlets and one or more gas outlets are preferably located on opposite sides of the furnace cabin. (“Sides” as used herein includes also the top and bottom.) This enables the gas to flow through the whole furnace cabin when passing from the one or more inlets to the one or more outlets.
  • a plurality of inlets and/or outlets may be used, for example, to spread the gas flow across the volume of the furnace cabin.
  • baffles can also be used to optimise the gas flow through the furnace cabin.
  • the one or more gas inlets are located at the base of the furnace cabin and the one or more gas outlets are located at or close to the top of the cabin. In this manner the gas passes in an overall vertically upwards direction through the furnace cabin from the one or more gas inlets to the one or more gas outlets.
  • the furnace cabin may comprise a vent.
  • a vent is an outlet by which gas from the furnace cabin is vented to atmosphere or at least externally to the furnace. In conventional furnaces this may be a chimney, for example.
  • the one of more gas outlets of the present invention are outlets which are connected to an external recirculation loop. (The one or more gas outlets may be considered as recirculating gas outlets. Similarly, the one or more gas inlets may be considered as recirculating gas inlets.)
  • the one of more gas outlets are preferably provided on the main body of the furnace cabin and separate to any vent.
  • the one or more gas outlets are in addition to the vent, it is also within the scope of the present invention that one or more gas outlets may be taken from the base of the vent/chimney rather than directly from the furnace cabin or that a vent/chimney may be provided on the recirculation loop. It is a key feature of the present invention that there is provided an external recirculation loop which connects one or more of the gas outlets of the furnace cabin to one or more of the gas inlets of the furnace cabin.
  • the external recirculation loop provides a connection such that gas exiting the one or more gas outlets of the furnace cabin flows to the one or more gas inlets. It is thereby recirculated to the furnace cabin. More generally, in the furnace of the present invention gas flows through the furnace cabin, exits the furnace cabin through the one or more gas outlets, and then is returned through the external recirculation loop to the one or more gas inlets, and hence back into the furnace cabin.
  • the gas which is recirculated may be herein referred to as the “recirculating gas”, and should be distinguished from the reactants and product gases (which may be referred to as “process gases”) in the one or more process tubes.
  • At least one gas analyser or detector and/or at least one pressure monitor for measurement of pressure on the external recirculation loop.
  • gas is withdrawn from the furnace cabin through one or more gas outlets and enters the recirculation loop.
  • Analysis and/or pressure measurement of the gas in the recirculation loop can be performed, whilst the gas circulates and passes through the one or more gas inlets back into the furnace cabin. It should be noted that those measurements are made on the gas in the recirculation loop, which is the gas from the furnace cabin. This is separate to any analysis on the reactants fed to or the products removed from the one or more process tubes.
  • At least one gas analyser or detector on the external recirculation loop.
  • at least one pressure monitor may be provided in addition to the at least one gas analyser or detector in such embodiments.
  • one or more heaters in the external recirculation loop for heating the gas in the external recirculation loop.
  • gas is withdrawn from the furnace cabin through one or more gas outlets and enters the recirculation loop. It is heated in the recirculation loop and then passes through the one or more gas inlets back into the furnace cabin.
  • a first recirculation loop by which one or more gas outlets are connected to one or more gas inlets
  • a second recirculation loop by which one or more different gas outlets are connected to one or more gas inlets.
  • at least one gas analyser or detector and/or at least one pressure monitor for measurement of pressure may be provided on one or both of the recirculation loops and/or one or more heaters may be present on one or both of the recirculation loops. It is preferred that one or more heaters are present on both recirculation loops. More preferably, however there is a single recirculation loop with all gas outlets combining to form a single pipe and which then feeds into the one or more gas inlets of the furnace cabin.
  • the use of external heating allows additional heat input into the gas, and hence into the furnace cabin and to the process tubes. This can provide improved control of the energy input to the process. It also means that the gas entering the furnace cabin is hotter (than if external heating were not applied), so process tubes at or close to the one or gas inlets, for example at the base of the furnace cabin, receive more heat than they otherwise might. This can enable a more even heating of the furnace tubes overall, and better yield.
  • recirculation loop with gas analysis/detection and/or pressure monitoring thereon, this is also advantageous.
  • gas analysis is more easily done on the recirculation loop than trying to analyse gas inside the furnace cabin.
  • the gas analysis on the recirculation loop can also more quickly identify any changes or issues in the gas medium in the furnace cabin.
  • a relatively high recirculation loop flow (relative to the volume of the furnace cabin) can be used to ensure that the furnace cabin atmosphere is effectively sampled.
  • the volumetric flow rate in the recirculation loop (“recirculation rate”) may be from 2 to 100% of the furnace cabin volume per minute (i.e.
  • the flow rate may be between 0.02 times X m 3 /min and X m 3 /min). This means that the gas in the furnace cabin has an average residence time of 1 to 50 minutes. Where one or more heaters for heating the gas are provided in the external recirculation loop then the optimum recirculation flow rate will generally be selected based on the desired temperature for the recirculating gas after heating. In addition, or alternatively, a plurality of gas outlets can be used such that the recirculating gas is representative of the atmosphere in multiple parts, if not all, of the furnace cabin. In contrast, if analysers are provided in the furnace cabin itself then multiple analysers may be required for effective coverage of the furnace volume.
  • a typical furnace cabin volume for a conventional furnace for cracking of 1 ,2-dichloroethane may, for example, be from 200 to 500m 3 .
  • Steam cracking furnaces for cracking of ethane may be of a similar size or even bigger. Effectively sampling all areas of such furnaces requires multiple analysers.
  • the gas in the furnace cabin may be circulating within the furnace cabin itself (as well as in the external recirculation loop). This is advantageous as it also means that an individual gas outlet can sample gas circulating from other parts of the furnace cabin rather than from a single static location, and this can be achieved even without a relatively large volumetric flow rate in the external recirculation loop. This can also allow to more quickly identify any changes or issues in the gas medium throughout the furnace cabin, therefore.
  • the volumetric flow rate in the recirculation loop (“recirculation rate”) may be in the ranges previously noted, although in such cases it is preferably at the lower end of the ranges previously noted, such as from 2 to 25% of the furnace cabin volume per minute.
  • the volumetric flow rate in the recirculation loop (“recirculation rate”) may be lower than 2% of the furnace cabin volume per minute.
  • the volumetric flow rate in the recirculation loop (“recirculation rate”) may be in the range 0.5 to 25%, such as 0.5 to 5%, of the furnace cabin volume per minute.) Circulation within the furnace cabin in such embodiments may be achieved by any suitable means.
  • circulation within the furnace cabin is achieved, at least in part, by convection currents within the furnace cabin. For example, providing heating on the walls of a furnace cabin can lead to gas which rises at the walls of the furnace cabin (as it is heated), and then cools and sinks in the centre of the furnace cabin, where is contacts (and heats) process tubes, leading to circulation by convection currents.
  • EDC ethylene dichloride
  • an analyser will provide a concentration, whereas a detector provides an alert if the component is detected.
  • the recirculating gas may be an inert gas (like N2, C02, argon) or may include oxygen, such as being air or a gas mixture of an inert gas with 1-21% oxygen.
  • oxygen such as being air or a gas mixture of an inert gas with 1-21% oxygen.
  • a small amount of oxygen in the furnace cabin, such as l-10vol% oxygen, may, for example, be desirable for the optimum operation of the electric heating means.
  • an 02 analyser or detector is also provided.
  • the presence of 02 e.g. when using an inert gas
  • a deviation from the expected oxygen content e.g. when using a gas comprising oxygen
  • a pressure monitor on the external recirculation loop there may be provided a pressure monitor on the external recirculation loop.
  • the reactants in the process tubes are at a much higher pressure than the gas in the furnace cabin.
  • a deviation in pressure on the external recirculation loop (and in particular a pressure increase) may also be used as an indication of a leak from the process tubes. If the furnace cabin is itself at a pressure higher than atmospheric, which is preferred in some embodiments, then a reduction in pressure may indicate a leak from the furnace cabin to the external environment.
  • the recirculating gas may include steam.
  • the analysis/detection/monitoring thus provides significant safety advantages by detecting potentially dangerous situations rapidly.
  • a reading which indicates a deviation from the expected value, for example of hydrocarbon, HC1 or oxygen, would then trigger a safety response.
  • the response would be selected by the person skilled in the art but would generally depend on the specific gas detected and the extent thereof. For example, a small oxygen increase may need to be monitored but operation could potentially continue.
  • a leak of a reactant or product such as (depending on the process) a hydrocarbon leak, an HC1 leak or an ammonia leak would result in stopping of the process.
  • Various actions may be taken in this scenario, including purging of the furnace cabin and/or flushing of the process tubes, as would be apparent to a person skilled in the art.
  • the furnace may comprise, in the recirculation loop, a suitable fan or blower, or gas ejector.
  • Fresh gas for the furnace cabin/recirculation loop may be introduced in either the furnace cabin (by one or more separate fresh gas inlets) or in the recirculation loop. Where an ejector is used then the fresh gas is suitably introduced into the ejector as the motive gas.
  • the second aspect of the present invention there are provided one or more heaters for heating the gas in the external recirculation loop.
  • the first aspect it is also preferred that there are provided one or more heaters for heating the gas in the external recirculation loop.
  • the following description therefore applies to the second aspect and also to those embodiments of the first aspect where one or more heaters are provided for heating the gas in the external recirculation loop.
  • the one or more heaters for heating the gas in the external recirculation loop may be any suitable heaters.
  • the present invention is particularly advantageous where the external heating is also provided by one or more electrical heating means.
  • any suitable electrical heating means may be provided.
  • the installed heating capacity of the electrical heating elements in the furnace cabin (“internal” heating or heating capacity) is larger than the installed heating capacity in the heaters for heating the gas in the external recirculation loop (“external” heating or heating capacity).
  • installed heating capacity means the amount of heating power which is available. This is independent of whether, in use, all this capacity is used for heating.
  • the size of the furnace cabin can limit the number of heating elements which can be provided in the furnace cabin, and hence the heating capacity which can be installed.
  • the installed heating capacity in the furnace cabin is maximised (taking into account the constraint of it size), and sufficient external heating provided to provide the desired total heating capacity for the furnace.
  • the installed heating capacity in the furnace cabin is 50-95% of the total installed heating capacity (i.e. total heat capacity of the electrically powered heating means located inside the furnace cabin and the one or more heaters for heating the gas in the external recirculation loop), such as 60-90% of the total installed heating capacity.
  • the total available installed heat capacity may be selected as required, not least based on the feed to be heated and its throughput i.e. the scale of the process. It may be, for example, 5 to 200 MW, such as 5 to 100 MW.
  • the installed heat capacity of the electrically powered heating means located inside the furnace cabin may be 4 to 175 MW and the typical installed heat capacity of the one or more heaters for heating the gas in the external recirculation loop may be 1 to 100 MW.
  • the total available installed heat capacity may be 5 to 60 MW, with the installed heat capacity of the electrically powered heating means located inside the furnace cabin being 4 to 50 MW and the installed heat capacity of the one or more heaters for heating the gas in the external recirculation loop being 1 to 30 MW. In most preferred embodiments, the total available installed heat capacity may be 5 to 30 MW, with the installed heat capacity of the electrically powered heating means located inside the furnace cabin being 4 to 25 MW and the installed heat capacity of the one or more heaters for heating the gas in the external recirculation loop being 1 to 15 MW.
  • the ratio of heat delivered by the external heaters in the external recirculation loop to the total heat delivered by the furnace may be from 5 to 100 %.
  • the preferred ratio is 5 to 50 % i.e. preferably most of the total heat is delivered by the electrical heating elements in the furnace cabin, not by the external heaters.
  • the present invention provides the ability to adjust this ratio as required.
  • the total amount of heating applied, and the relative heating applied in the furnace cabin and in the recirculation loop may be adjusted, for example, based on the feedstock to be cracked.
  • the recirculation loop includes a box or a pipe or of several pipes which are conveying the recirculating gas and which contain electrically powered heating elements or coils located on the internal walls or distributed within the gas flow. Heating elements or coils may be equipped with fins to improve heat transfer.
  • the recirculation loop is made of one tube or of multiple tubes in parallel who are externally heated in a box containing electrically powered heating element.
  • This external box may be of much simpler design than the furnace cabin since no reactants or products are present.
  • the recirculation loop is made of one tube or of multiple tubes in parallel who are directly electrically heated
  • Figure 1 shows schematically an electrically heated furnace comprising a furnace cabin (1) with a serpentine process tube (2) and heating elements (13).
  • the furnace cabin has gas inlets (3) and gas outlets (4) - four of each are shown but this may be more or less.
  • Gas removed from the one or more gas outlets is passed through a recirculation loop (5) using a circulation fan (6).
  • the gas is heated in an external heating box (7), which is also electrically heated.
  • Fresh gas is introduced via line 8, whilst there are provided analysers (9), for example for analysis of HC1 and 02.
  • the furnace further comprises a chimney (10), whilst reactant gas is introduced to the process tube (2) via an inlet (11), with products being removed via an outlet (12).
  • Figure 2 shows schematically a furnace formed by fitting electrical heating elements and a recirculation loop (5) to a conventional fired furnace cabin.
  • This type of configuration could be used for retrofitting/conversion of an existing gas fired furnace, enabling the utilisation of the existing furnace cabin and process tubes, as well as feed controls and product work-up.
  • the furnace cabin comprises a conventional gas fired furnace cabin with a radiation section (la) and a convection section (lb).
  • the gas fired heaters (burners) in the radiation section have been replaced with electrical heating elements (13a).
  • Process tubes pass reactant gas to and through the convection section (lb) and then the radiation section (la), as in the conventional/existing furnace arrangement.
  • the furnace cabin has a gas inlet (3) and a gas outlet (4).
  • Gas removed from the gas outlet (4) is passed through a recirculation loop (5) using a circulation fan (6).
  • the gas is heated in an external heating box (7) for heating gas in the recirculation loop before it is recycled to the furnace cabin via the inlet (3).
  • the heating may in particular use further electrical heating elements (13b) in the external heating box (7).
  • Analysers (9), for example for analysis of HC1 and 02, are provided on the recirculation loop (5), along also with a pressure monitor (14).
  • an inlet can be provided on the recirculation loop for introduction of fresh inert gas or air.
  • Figures 1 and 2 both illustrate a furnace which includes both analysers and external heating on the external recirculation loop
  • the external recirculation loop may comprise solely one or more analysers or solely heaters for heating the gas in the external recirculation loop, and still be according to the respective first and second aspects of the present invention.
  • the furnace of the first aspect or the second aspect of the present invention may be used for any process which typically operates in furnaces in which reactants or process fluids are passed through heated process tubes, including any processes conventionally or historically operated in fired (burner based) furnaces.
  • the present invention provides a process for performing a chemical reaction which process comprises a. providing a furnace according to the first aspect and/or according to the second aspect of the invention, b. passing one or more reactants through the one or more process tubes, c. circulating a gas through the one or more gas outlets, the recirculation loop, the one or more gas inlets and the furnace cabin, and d. heating the reactants in the one or more process tubes to effect reaction of the reactants within the process tubes.
  • the temperature of the reaction will depend on the specific process and is not especially limited, but in preferred processes the furnace may typically operate at a temperature of the process tubes in the range 300 to 1200°C
  • the process may be catalytic or non-catalytic.
  • catalysts may be provided in the process tubes either as a catalyst bed or as a coating on the inside of the process tubes.
  • suitable processes include steam and other cracking processes, various reforming processes, such as steam reforming and dry reforming, processes for the dehydrogenation of alkanes.
  • the process is a process for cracking, and most particularly a process for cracking of 1 ,2-dichloroethane (EDC) to produce vinyl chloride monomer (VCM).
  • EDC 1 ,2-dichloroethane
  • VCM vinyl chloride monomer
  • the cracking of EDC to produce VCM is well-known in the art.
  • the present invention similar to operation in a conventional process operates in a furnace by passing an EDC containing stream through a process tube inside the furnace cabin, and heating the tube to heat and crack the EDC therein.
  • the (or each if more than one) process tube in such a furnace is in the form of a serpentine tube which is located in a vertical plane or close to a vertical plane in the centre of the furnace cabin. Heating can then be applied from heating elements on both sides of the furnace cabin.
  • the EDC containing stream is heated to a temperature sufficient to cause cracking of the EDC. Typically this is at least 35O°C, and preferably in the range 35O°C to 550°C.
  • the temperatures, residence times etc. may be selected by the person skilled in the art for the degree or rate of cracking required. They may, in particular, be similar to cracking in conventional (hydrocarbon burner) systems.
  • the EDC containing stream may be introduced in a form where the EDC is in the liquid phase.
  • the EDC is vaporised in the earlier sections of the process tube or tubes, then further heated to a temperature, for example within the range 350°C to 550°C, at which cracking occurs in later sections.
  • the EDC containing stream introduced at the inlet may have been heated (“pre-heated”) externally to the furnace, for example to a temperature sufficient to vaporise any liquid EDC. In such a case the EDC containing stream is in the gaseous phase at the inlet of the process tube(s).
  • the furnace may however also be designed for and used for other processes, such as steam cracking.
  • the furnace may also be designed for heating-up petroleum or chemical products.
  • the furnace may comprise one or more heaters for heating the gas in the external recirculation loop.
  • the ratio of heat delivered by any external heaters in the external recirculation loop to the total heat delivered by the furnace may be from 5 to 100 %.
  • the preferred ratio is 5 to 50 % i.e. preferably most of the total heat is delivered by the electrical heating elements in the furnace cabin, not by the external heating elements.
  • the present invention provides the ability to adjust this ratio as required.
  • the total amount of heating applied, and the relative heating applied in the furnace cabin and in the recirculation loop may be adjusted, for example, based on the feedstock to be cracked. (And this may be, for example, based on different hydrocarbon feeds, for example ethane versus naphtha cracking may have different requirements, or the “state” of the feed on entry to the process e.g. whether EDC is liquid or gaseous on entry to the furnace.)
  • the (recirculating) gas may be an inert gas or a gas comprising oxygen.
  • an inert atmosphere is preferred, although a small amount of oxygen (for example, a gas mixture which comprises an inert gas and less than 10 vol% oxygen) may be desirable for the use of certain types of electrical heating elements.
  • the furnace cabin maybe operated above atmospheric pressure. This is advantageous in relation to potential external contamination with air because it ensures that the gas in the furnace cabin leaks “out” rather than air leaking “in”.
  • the present invention can be illustrated by the following Example, which illustrates the retrofitting of a conventional (burner based) EDC (ethylene dichloride) cracker.
  • the retrofitted furnace is as shown in Figure 2.
  • the EDC cracker produces 160 kt/y of VCM (vinyl chloride monomer).
  • EDC feed is 53 t/h of EDC, which is fed to the convection section of the cracker, and then passes to the radiation section.
  • the thermal cracker Prior to retrofitting the thermal cracker is heated up by natural gas burners distributed on several rows on the lateral walls of the radiation section of the cracking furnace. Flat type flame burners are heating up the process tubes in the radiation section. Flue gases are then passing through the convection section of the furnace. At the top of the cracker, flue gases are removed through the chimney and either sent to atmosphere or to an independent heat recovery step.
  • the required heat duty of the burners is 17,9 MW. A significant part of this heat leaves the cracker in the flue gases.
  • the electrical cracker is as shown in Figure 2, and is equipped with an external recirculation loop.
  • This loop recirculates gases from top of the cracker (top of convection section) back into the radiation section, via an external electrical heating section.
  • Analysers are provided on the recirculation loop for analysis of HC1 and O2. These constantly analyse the recirculating gas stream. In particular, the presence of HC1 or a change in O2 concentration would rapidly identify the presence of a leak from a process tube.
  • nickel-chromium-aluminium heating elements are used as electrical heating means in both the radiation section of the cracking furnace and in the external heating section.
  • the circulating gas exits the convection section at 450°C (which is the same as the exiting flue gas in the “conventional” furnace) and is heated to 800°C in the external heating section before it is reintroduced to the radiation section.
  • the recirculation gas flow is close to 30000 Nm 3 /h (500 Nm 3 /min).

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • General Chemical & Material Sciences (AREA)
  • Furnace Details (AREA)

Abstract

La présente invention concerne un four chauffé électriquement, en particulier un four pour des réactions chimiques, et en particulier dans un mode de réalisation, un four chauffé électriquement. Ledit four comprend : a. une cabine de four comportant : i. un ou plusieurs tubes de traitement qui s'étendent à travers la cabine de four, ii. une pluralité de moyens de chauffage alimentés électriquement situés à l'intérieur de la cabine de four pour chauffer le ou les tubes de traitement, iii. une ou plusieurs entrées de gaz, iv. une ou plusieurs sorties de gaz ; b. une boucle de recirculation externe qui relie la ou les sorties de gaz de la cabine de four à la ou aux entrées de gaz de la cabine de four de telle sorte que le gaz sortant de la ou des sorties de gaz de la cabine de four s'écoule vers la ou les entrées de gaz et est remis en circulation vers la cabine de four ; c. au moins un analyseur ou détecteur de gaz et/ou au moins un dispositif de surveillance de pression pour mesurer la pression fournie sur la boucle de recirculation externe.
PCT/EP2023/082094 2022-11-22 2023-11-16 Four WO2024110316A1 (fr)

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EP22208938.5 2022-11-22

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5972300A (en) * 1996-03-11 1999-10-26 Kashima Vinyl Chloride Monomer Co., Ltd. Method and means for recovering heat in the pyrolysis of 1,2-dichloroethane
GB2445465A (en) * 2007-01-05 2008-07-09 Sterecycle Ltd Municipal waste treatment
WO2021214256A1 (fr) 2020-04-23 2021-10-28 Linde Gmbh Réacteur et procédé pour réaliser une réaction chimique
WO2022094455A1 (fr) * 2020-11-02 2022-05-05 Lummus Technology Llc Four électrique pour la production d'oléfines
WO2022200256A1 (fr) * 2021-03-24 2022-09-29 Sabic Global Technologies B.V. Systèmes et procédés pour la production d'oléfines dans un four de craquage chauffé électriquement

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5972300A (en) * 1996-03-11 1999-10-26 Kashima Vinyl Chloride Monomer Co., Ltd. Method and means for recovering heat in the pyrolysis of 1,2-dichloroethane
GB2445465A (en) * 2007-01-05 2008-07-09 Sterecycle Ltd Municipal waste treatment
WO2021214256A1 (fr) 2020-04-23 2021-10-28 Linde Gmbh Réacteur et procédé pour réaliser une réaction chimique
WO2022094455A1 (fr) * 2020-11-02 2022-05-05 Lummus Technology Llc Four électrique pour la production d'oléfines
WO2022200256A1 (fr) * 2021-03-24 2022-09-29 Sabic Global Technologies B.V. Systèmes et procédés pour la production d'oléfines dans un four de craquage chauffé électriquement

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