• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
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    • 专利摘要:
    A device is used to control a deflagration or a thermal detonation in a continuously operated chemical tubular reactor with at least one reactor section, the tubular reactor (1, 1 ', 1' ') having an inlet (2) and an outlet (3) and wherein the The inlet (2) and the outlet (3) define a main flow direction (5) in the reactor. The device has at least one lock (5, 5 ', 5 ") to interrupt the inlet (2) and / or the outlet (3), the lock (5, 5', 5") at least one valve and has a body. The body is designed to hold a heat front of deflagration or thermal detonation until the valve is closed. This device prevents a heat front from spreading.
    公开号:CH716747A2
    申请号:CH01275/20
    申请日:2020-10-07
    公开日:2021-04-30
    发明作者:Altenburger Daniel；Rosasco Esteban；Andreoli Silvano；Georg Alain
    申请人:Fluitec Invest Ag；
    IPC主号:
    专利说明:

    TECHNICAL AREA
    The present invention relates to a device for controlling a deflagration or a thermal detonation in a continuously operated chemical tube reactor. The device serves to reduce the risk in the event of thermal decomposition during a chemical reaction in the reactor.
    STATE OF THE ART
    The safety of a production process in the chemical industry plays an important role. Chemical production processes are therefore usually constantly monitored in order to avoid possible dangerous conditions that could lead to an explosion or the release of chemicals.
    It is common to provide controls for the operation, monitoring and security of an installation or a system. EP 3 181 221 A1 discloses a monitoring of a reaction by means of heat balance detection and local temperature measurement. This makes it possible to reliably detect an accumulation and / or a migration of the reaction. Depending on the embodiment, probes for measuring material properties (for example refractive index, pH probes, infrared, NIR, Raman and ATR probes) are preferably also present.
    Many chemical reactions are exothermic and are therefore associated with the release of heat. If the amount of heat released per unit of time cannot be sufficiently dissipated, the reaction mass itself heats up. As a result, the reaction rate increases and the reaction accelerates. If this situation can no longer be controlled, a so-called thermal explosion occurs, which is usually associated with high pressure build-up due to the onset of evaporation and gas development. One speaks here of a “runaway” or “runaway” of the reaction.
    It is known that processes in continuously operated chemical tubular reactors are considered to be significantly safer than processes in large chemical stirred vessels, such as, for example, a CSTR reactor (continuously stirred reactor). On the one hand, this is due to the lower volumes; on the other hand, the tubular reactor has a better surface / volume ratio, so that the heat can be better dissipated in tubular reactors.
    EP 3 147 935 describes a method and a system for controlling a chemical reaction in a continuously operated reactor. To prevent an uncontrolled course of the reaction, measures are taken which include at least the following steps: interruption of the inlet and outlet, active pressure relief of the reactor and flushing of the reactor with an inert substance. Thanks to these measures, the chemical reaction can be interrupted efficiently and safely.
    Particular attention should be paid to cases where deflagration or thermal detonation occurs. Deflagration is a rapid combustion process in which the explosion pressure is caused by the developing and expanding gases. The propagation takes place through the heat released during the reaction, i.e. the ignition of the unburned mixture takes place through the heating of the mixture at the flame front. A spread of this warm front can therefore have devastating effects.
    It is known to use flame arresters or quick-closing valves as protection against such uncontrolled ignitions of gas mixtures.
    The construction of flame arresters, in particular flame filters and flame arresters, is known to those skilled in the art. Flame arresters are clearly defined in accordance with the DIN EN ISO 16852 standard. A distinction is made between deflagration protection and detonation protection. In practice, the type of flame arrester used as a pipe fuse depends on the medium and the distance to the ignition source. In the event of a gas flashback, for example, the flame races through the pipeline at twice the speed of sound.
    Unfortunately, however, these measures alone are not sufficient to reliably hold back a decomposition reaction which deflagrates or thermally detonates in a reactor. The reason is that, as already described, such a decomposition reaction can lead to different flow conditions as well as very different temperature and pressure profiles. Flame arresters only withstand the increased pressure and high temperatures for a certain period of time. Even fast-closing valves are often too slow in the event of deflagration or thermal detonation, or valves that are already closed are skipped by the warming front.
    The interruption of a thermal explosion is possible in the initial stage by cooling, flooding, flushing or by relieving pressure. A deflagration that has just begun, which in its initial stage propagates at low speed, can also be interrupted by flooding, flushing or by relieving pressure.
    However, if a rapid deflagration, a thermal explosion or even a detonation occurs, then no interruption is possible due to the high speed of propagation. This behavior makes handling reactive substances difficult. Knowledge of the hazard potential is therefore an absolute prerequisite for the correct selection of measures.
    For checking purposes, there are special test methods corresponding to the mechanism to be investigated, which have been developed for the classification and classification of potential hazardous substances for transport and storage, but can also be used analogously for handling these reactive substances. They are known in the specialist field and are only briefly explained below: In order to examine the thermal sensitivity of a sample with partial inclusion, the sample is thermally stressed in a steel sleeve with a defined opening in the so-called Koenen test. It is checked whether a thermal explosion occurs depending on the diameter of the lid opening.
    When examining the transmission of deflagration, for example, a sample is examined in a pressure-time test in a closed container. By igniting a booster charge, the decomposition reaction is triggered locally and the development of pressure over time is monitored.
    When testing for detonation, for example, a sample is enclosed in a steel pipe and the decomposition reaction is triggered locally by the ignition of a booster charge that causes a shock wave. In the cavitated version of the BAM 50/60 steel pipe test, the sample is additionally traversed with oxygen or air at a defined flow rate. This cavitated version is regarded as a test of practical relevance when testing peroxides, since when decomposition begins, the resulting gases flow through the sample and increase the sensitivity of the sample to the propagation of detonation.
    As already described, a deflagration or a thermal detonation can lead to different flow states as well as very different temperature and pressure profiles.
    Although the continuously operated tubular reactor has the advantage of lower volume, in the event of deflagration or thermal detonation it has the disadvantage that the uncontrolled reaction can propagate via the inflow of the feed streams and the outflow of the product. In the worst case, this will result in decomposition in the template and / or in the collecting container.
    In order to be able to stop such a continuous (“run-away”) reaction, a commercially available flame arrester is generally not sufficient, since the reaction medium can behave differently. The decomposing reaction medium can be gaseous, vaporous, liquid or a gas-liquid mixture.
    Even if the hot medium is cooled in the flame arrester, there is a risk that the reaction medium will heat up again, so that it propagates through the flame arrester and that it decomposes further medium in the pipeline. The heat front created by the decomposition is thus planted through the barrier. This is due to the fact that the liquid still has thermal energy and also has a decomposition potential, which can lead to evaporation or gas formation. Conventional flame arresters are therefore not suitable for reaction media that decompose through deflagration or thermal detonation, since the course of the reaction cannot be foreseen. In particular, the usually considerable rise in pressure and temperature makes the course of the reaction unpredictable.
    Flame arresters and flame filters are also known in other areas of application. For example, DE 29815151 shows a flame arrester for liquid and gas lines, for example for feed lines and discharge lines of pumps for conveying flammable and explosive liquids, for example fuels. These flame barriers or flashback arresters are arranged at certain points on the conveyor lines in order to prevent the further spread of flames. They are designed as a metal grid.
    WO 2009/030598 AI discloses a flame filter for closed gas-filled spaces, such as for ship engines and diesel or gas engines. The flame filter can be used together with an explosion relief valve. It consists of flat metal sheets densely stacked on top of each other to form a package. The mode of operation is based on the fact that a flame front is cooled by built-in components to such an extent that a flame cannot spread further behind the flame arrester.
    DISCLOSURE OF THE INVENTION
    It is therefore an object of the invention to provide an apparatus and a method which ensure protection in the event of deflagration or thermal detonation in a continuously operated tubular reactor.
    This object is achieved by a device with the features of claim 1 and a method with the features of claim 15.
    The device according to the invention is used to control a deflagration or a thermal detonation in a continuously operated chemical tubular reactor with at least one reactor section. The tubular reactor has an inlet and an outlet, the inlet and the outlet defining a main flow direction in the reactor. The device has at least one barrier for interrupting the inflow and / or the outflow, the barrier having at least one valve and a body, the body being designed to stop a heat front of the deflagration or the thermal detonation until the valve is closed .
    The lock according to the invention acts as a deflagration protector. The at least one valve prevents the uncontrolled reaction from spreading in the lines. The body delays the spread of the warmth front and gives the valve enough time to close. The barrier thus prevents the thermal decomposition of reactive, flowing liquids, gases and liquid-gas mixtures from being able to propagate in a system. The deflagation protector thus protects both the storage container and the collecting container of a system with a continuously operated reactor from deflagration.
    If the reactor has several pipe sections separated from one another by lines, a barrier according to the invention is preferably also arranged in the direction of flow between the first and second pipe sections, which prevents the uncontrolled reaction from spreading into the second pipe section. The barrier according to the invention can also be arranged between further downstream pipe sections.
    If the reactor consists of several pipe sections which are connected to one another via lines, these segments are preferably stacked on top of one another from bottom to top and / or preferably connected in series. The reactor inlet is preferably arranged at the bottom and the reactor outlet at the top.
    Preferably, the valve has a defined closing time, the body holding the heat front at least during this closing time. The valve is preferably a quick release valve and more preferably it is a quick release valve with a maximum closure time of 1 second.
    The quick release valve is preferably a seat valve, as it is sold, for example, by KFM, Samson, Kühme, Albrecht Automatik or HD Industrie. Seat valves are preferred in which the valve head is pressed into the seat when the pressure rises. The valve preferably has a pressure rating of PN64 to PN320.
    Instead of a quick-acting valve, other types of shut-off means, referred to here as a whole as a valve, can also be used. Such shut-off means are, for example, ball valves, needle valves, butterfly valves or the like. In particular embodiments, the shut-off means are cooled.
    A filter is preferably connected upstream of the shut-off means, in particular the quick-release valve, in order to avoid clogging of the shut-off means, for example due to deposits. The filter is preferably arranged at the inlet of the reactor. It is preferably installed in front of the metering pump or in front of the shut-off device. Depending on the embodiment, the filter is alternatively or additionally arranged at the outlet of the reactor. In this case it is preferably mounted directly in front of the shut-off means.
    The body is preferably arranged in a component. The component can be an independent component or form a unit with the at least one valve.
    The body is preferably a porous filter body. The body is preferably made from a sintered or foamed material. In other embodiments, the body is a cylinder with numerous small longitudinal bores. The holes have such a small diameter that the thermal front cannot break through. The diameter of the longitudinal bores is preferably 0.2 mm to 1 mm. This body can be produced using 3D printing, for example. The body preferably has open channels and / or cavities, especially if it is produced using the 3D printing process, the channels and / or cavities having a diameter of less than 1 mm, preferably less than 0.5 mm, and even more preferably smaller than 0.3 mm. If the cross-sectional shape of the channels and / or pipes deviates from a round cross-section, then their hydraulic diameter preferably has the values mentioned above.
    The body is preferably designed in the shape of a disk or a cylinder. If it is designed as a cylinder, it preferably extends in its longitudinal direction in the main flow direction.
    The body preferably has a high intrinsic mass and / or narrow channels. Furthermore, the body is preferably designed in such a way that it has a high phi factor. The Phi factor is the ratio between the total heat capacity of a heated system, here the body, and the heat capacity of the examined sample, here the reaction mixture in the body.
    This configuration of the body not only ensures a reliable thermal barrier, but also increases the pressure in the pipe section and thus leads to faster detection of an uncontrolled reaction in the pipe section, for example by means of a pressure sensor arranged in the pipe section. The body is preferably designed in such a way that the pressure loss across the body in normal operation is less than 5 bar, preferably less than 1 bar and particularly preferably less than 0.2 bar. The body is preferably designed in such a way that the mechanically maximum permissible pressure loss over the body is greater than 10 bar, preferably greater than 50 bar and particularly preferably greater than 100 bar.
    The body is preferably arranged in front of the valve in the direction of propagation of the heat front. If the barrier is in the inlet, the body is preferably arranged in the main flow direction after the valve. If the barrier is in the drain, the body is preferably arranged upstream of the valve in the main flow direction.
    In embodiments in which there are at least two pipe sections which are connected in series one behind the other, a bursting disc and / or a safety valve is preferably arranged between the two pipe sections. It is also possible to arrange a safety valve between two of the pipe sections and a bursting disc between two other pipe sections of the same reactor. In this case, the rupture disk is preferably arranged upstream of the safety valve in the main flow direction.
    The device preferably has at least one sensor for monitoring the reaction in the reactor, the at least one valve being able to be closed in accordance with a signal from this sensor. For example, temperature sensors and / or pressure sensors and / or a thermocouple are suitable as sensors. A PT-100 temperature sensor is particularly suitable as a temperature sensor.
    Commercially available quick-release valves react within a maximum of one second after a sensor has detected a hazard.
    The highest level of security is achieved if the deflagration protector or parts thereof are built redundantly. This increases the SIL safety. In preferred embodiments, flushing, for example with nitrogen, is provided in an intermediate piece if the heat front propagates through the body and the quick-release valve. The flushing ensures that the warming front does not penetrate the second redundant quick-release valve. Optionally, the flush can be relieved via a small safety valve at the outlet of the intermediate piece. This embodiment of the deflagration protector meets the highest requirements in terms of reactor safety.
    In a preferred embodiment, the lock according to the invention therefore has a first valve and a second valve, the second valve being arranged after the first valve in the direction of propagation of the warming front. A flushing unit is preferably arranged between the first valve and the second valve.
    In selected embodiments, the reactor has, via a reactor section, a circuit controlled by a pump, as is described, for example, in WO 2017/080909 A1.
    In preferred embodiments, the chemical reaction in the reactor is monitored. Methods such as those described in EP 3 181 221 A1 are particularly suitable as monitoring. In these procedures, the following measures, for example, are taken to prevent an uncontrolled reaction sequence:Interruption of the inflow and the outflow according to a sensor signal,active pressure relief of the reactor andFlushing the reactor with an inert substance.
    There is preferably a reactor safety concept which has monitoring and control by means of a monitoring device of the plant. Furthermore, event-preventing protective devices and damage-limiting protective devices are preferably provided in this safety concept.
    In preferred embodiments, the control of a deflagration or a thermal detonation means that if the monitoring device and the event-preventing protective devices fail at the same time, a deflagration or thermal detonation occurs, but that this only affects a specific reactor section and the storage container and in a controlled manner the collecting container are not endangered. The barrier according to the invention thus forms a damage-limiting protective device of the above-mentioned reactor safety concept.
    In preferred embodiments, in the event that deflagration or thermal detonation could occur, the reactor is designed both for higher pressures and for higher temperatures than usual.
    [0048] Reaction monitoring as described in EP 3 181 221 A1 mentioned at the outset is preferably used. If the sensors mentioned in EP 3 181 221 A1 are used, a migration at the outlet of the reactor can be determined. However, other types of reaction monitoring can also be used in the method according to the invention.
    The inventive method for controlling a deflagration or a thermal detonation in a continuously operated chemical tubular reactor with at least one reactor section uses a reactor with an inlet and an outlet, the inlet and the outlet defining a main flow direction in the reactor. The procedure has at least the following steps:Monitoring a chemical reaction taking place in the reactor,Closing at least one valve in the inlet and / or in the outlet in the event of an uncontrolled reaction sequence of the monitored chemical reaction andDelaying the spread of a heat front resulting from the uncontrolled reaction sequence in the direction of the valve at least until a point in time at which the valve has closed at least approximately completely.
    The method according to the invention makes it possible, in the event of a decomposition reaction, to limit the volume in the event of a possible deflagration and / or in the event of a possible thermal detonation and thus considerably reduce the potential risk. Thanks to the interruption of the inlet and outlet, the reactor volume is completely sealed off. Thus, the method according to the invention prevents a chain reaction in the system, e.g. spreading to a possibly downstream dwell reactor or collecting container and / or to any storage container that may be present.
    The method according to the invention and the device according to the invention allow reactions to be carried out with higher permissible temperature differences than conventional devices. The use of higher temperature differences has the following advantages in particular:The reactions run faster and therefore shorter residence times are necessary. This leads directly to lower investment costs.The use of solvents can be reduced and / or they can even be dispensed with entirely. This means that additional energy-intensive separation processes can be dispensed with or at least considerable energy savings can be achieved.
    It is also advantageous that the installation position of the reactor can be freely selected. However, the device is preferably designed in such a way that the reactor can be completely flushed and emptied.
    Further embodiments are given in the dependent claims.
    BRIEF DESCRIPTION OF THE DRAWINGS
    Preferred embodiments of the invention are described below with reference to the drawings, which are only used for explanation and are not to be interpreted as restrictive. The drawings show: FIG. 1 a schematic representation of a device according to the invention with three horizontal reactor sections and with four deflagration protectors; FIG. 2a shows a reactor segment section with a schematic representation of a “hotspot” during decomposition; FIG. 2b shows a temperature profile within the reactor section according to FIG. 2a; FIG. 3 shows a schematic representation of a deflagration protector according to the invention for an inflow flow; FIG. 4 shows a schematic representation of a deflagration protector according to the invention for an outflow flow; FIG. 5 shows a schematic representation of a quick-release valve with an upstream filter according to the prior art; FIG. 6 shows a schematic representation of a deflagration protector according to the invention and a redundant quick-release valve in an embodiment for an outflow flow; FIG. 7a shows a side view of a body according to the invention and FIG. 7b shows a view of the body according to FIG. 7a from the front.
    DESCRIPTION OF PREFERRED EMBODIMENTS
    In FIG. 1, a first embodiment of the device according to the invention is shown. The figure is purely schematic. The device comprises a reactor, preferably a continuously operated tubular reactor, with one or more reactor sections 1, 1 ', 1 "or tube sections.
    The reactor is operated continuously and is therefore not a stirred tank, in particular it is not a stirrer and not a CSTR reactor. It also has no agitator.
    The pipe sections 1, 1 ', 1 "are preferably empty pipes, rectangular profiles or pipes with at least one installation or several internals. The internals are, for example, mixer-heat exchangers, packings, packings or static mixers.
    The reactor sections 1, 1 ', 1 "are preferably connected in series. If several reactor sections 1, 1', 1" are present, they are preferably connected in series.
    Preferably at least one of the reactor sections 1, 1 ', 1 ", preferably all reactor sections 1, 1', 1" have a heat transfer medium flowing through them for the purpose of temperature control (i.e. heating and / or cooling). The reactor sections 1, 1 ', 1 "are preferably provided with a static mixer or a mixer-heat exchanger.
    A feed serves to feed substances into the first reactor section 1. The substances are starting materials such as main components, additives, activators, solvents, emulsion additives and catalysts. They can be in liquid, gaseous or partly in solid form. In addition, the reactions can be carried out in a dilute solution or in a dispersion.
    The feed comprises one or more feed services 2. The individual feed lines 2 are preferably each provided with a metering pump 7 for metering the substances fed in.
    A discharge line leads from the last reactor section 1 ″ to the outside.
    The connection between the inlet and the outlet of the reactor, ie between the inlet and the outlet, defines a main flow direction S. It is thus the straight connection between the inlet and outlet or, in the case of several reactor sections connected to one another by lines, the straight one Connection between the inputs and outputs of the respective reactor sections. This main flow direction S usually corresponds to the direction of the longitudinal extent of the reactor section.
    The reactor preferably has at least one safety valve 4 and / or at least one bursting disk 6. The installation location and position are different depending on the embodiment. They are preferably arranged between the reactor sections 1, 1 ', 1 "or at the inlet and / or outlet. In this example, there is a rupture disk 6 between the first reactor section 1 and the second reactor section 1' and a safety valve 4 between the second reactor section 1 'and the third and last reactor section 1 ".
    According to the invention, the device has at least one deflagration protector, also called shut-off device or barrier 5, 5 ', 5 "here. The barrier 5, 5', 5" can be on the inlet side and / or outlet side and / or between the reactor sections 1, 1 ', 1 ". In this example, there are three inlet-side locks 5 and one outlet-side lock 5". Furthermore, a central barrier 5 'is preferably, but not mandatory, present between the first and second reactor sections 1, 1' in the flow direction. The barriers 5 on the inlet side are preferably arranged after the metering pumps 7 in the direction of flow.
    The device according to FIG. 1 is preferably part of a system which comprises a safety unit (not shown here). The system is preferably part of a plant. The security unit preferably has means for monitoring the reaction in the device. These means are preferably sensors, more preferably they are temperature sensors. Furthermore, the system preferably comprises an electronic control for controlling the entire system including the device according to the invention. Even more preferably, the electronic control is part of a control of the system, the control of the system controlling the individual elements of the system. The control of the system preferably controls the valves 4 and the metering pumps 7 as well as other actuatable elements of the device according to the invention. The control is preferably carried out in accordance with the values measured by the sensors or other monitoring means.
    The security unit comprises at leasta monitoring device which has the means mentioned, in particular the sensors, for controlling the device,event-preventing protective devices as well asdamage-limiting protective devices.
    The locks 5, 5 ', 5 "are connected to an electronic control, preferably with the control of the safety unit. They can be closed according to this control. The locks 5, 5', 5" preferably have locking means in the form of seat valves, needle valves, ball valves or butterfly valves. The shut-off means are preferably spring-closing.
    The shut-off means of the barriers 5, 5 ', 5 "is preferably a quick-release valve that can switch in less than a second and preferably has SIL approval (SIL = safety integrity level).
    A filter 8 is preferably connected upstream of the shut-off means, in particular the quick-release valve. The filter 8 prevents deposits and any clogging of the quick-release valve. This ensures safe operation of the locks 5.5 '. On the inlet side, the filter 8 is arranged upstream of the pump 7 in the direction of flow, as shown. On the outlet side, the filter is preferably arranged in front of the quick-release valve of the lock 5 ″.
    If a deflagration or a thermal detonation now occurs in the reactor 1 as a result of a deviation from normal operation, the monitoring means, in particular the sensors, detect this deviation. The control closes all barriers 5, 5 ', 5 "according to these sensor values and thus seals off the reactor sections 1, 1', 1" and thereby the entire reactor from inlet 2 and outlet 3.
    The at least one safety valve 4 and / or the at least one bursting disc 6 prevent the permissible operating pressure in the reactor from being exceeded. The entire mass of the decomposing fluid can thus be discharged into a quench tank (not shown here) without any risk. In this way, greater damage can be avoided.
    FIG. 2a shows a reactor section 1 of a reactor with several reactor sections or an entire reactor consisting of a single reactor section. FIG. 2b shows, in a schematic representation, the temperature profile along a longitudinal axis L of the reactor or of the reactor section 1.
    The reactor section 1 has an inlet opening 20 for the feed line 2 and an outlet opening 30 for the discharge line 3. The reactor section 1 shown here is preferably tempered (i.e. cooled and / or heated) by means of an HTM medium. If there is a deviation from normal operation, a local “hotspot” can occur in an area along the longitudinal axis L. In the event of rapid decomposition, the educts are suddenly and completely converted at the “hotspot” and strong local overheating occurs, as can be seen in FIG. 2b. A decomposition reaction takes place with a simultaneous production of gas and / or steam. The decomposition product expands very quickly and pushes the reaction liquid in the event of a deflagration, respectively. Deflagration simultaneously with an increasing length L1 of the area of the hotspot towards the inflow and the outflow. The pressure increases suddenly. This pressure is released via the bursting disc and the safety valve. In order to enable adequate protection in the event of a deflagration or a detonation, this reactor section 1 according to FIG. 2a is provided with at least one barrier 5 according to the invention. As already mentioned above, it can be arranged on the inflow side and / or the outlet side.
    In Figure 3, an inflow-side lock 5 according to the invention is shown schematically. It has a quick-release valve 9 and a component with a body 10. The quick-release valve 9 switches preferably within a maximum of 1 second. The body 10 is preferably positioned after the quick-release valve 9. The body 10 must be able to perform the following tasks in an emergency:the rapidly moving heat front, which moves against the direction of flow, must be able to be stopped with the body 10,the decomposition reaction must not penetrate through the quick release valve 9 and must be stopped before the quick release valve 9,In the event of a rapid pressure build-up due to the decomposition reaction, the pressure within the pipe section concerned should increase so that the pressure sensor triggers the quick-release valve 9 immediately.
    A lock 5 ″ according to the invention on the outlet side is shown schematically in FIG. 4. This lock 5 ″ also has the quick-release valve 9 and the component with the body 10. The quick-switching valve 9 again preferably has a switching time of a maximum of 1 second. The body 10 is preferably positioned in front of the quick-release valve 9. This body 10 must also be able to perform the following tasks in an emergency:the rapidly moving heat front, which moves in the direction of flow, must be able to be stopped with the body 10.the decomposition reaction must not penetrate through the quick release valve 9 and must be stopped before the quick release valve 9,In the event of a rapid pressure build-up due to the decomposition reaction, the pressure should increase so that the pressure sensor triggers the quick-release valve 9 immediately.
    FIG. 5 shows a schematic representation of a quick-release valve 9 with an upstream filter 8 according to the prior art. This design is not suitable as a damage-limiting protective device.
    In FIG. 6, a further embodiment of the inventive barrier 5 ″ on the outlet side is shown schematically. It has essentially the same structure as the embodiment according to FIG. 4. In addition, however, a second and thus redundant quick-release valve 11 is present. Between the two quick-release valves 9, 11, an intermediate piece 12 is preferably arranged, with a second inlet 13 and a second outlet 14. The intermediate piece 12 can thereby be flushed to limit damage so that the reaction cannot skip the intermediate piece 12.
    Since, in the case of a very high adiabatic temperature increase ΔTad, the body 10 is not able to cool sufficiently, there is the risk that the heat front will propagate and the quick-release valve 9 will be able to jump over. The redundant quick-release valve 11 is used to reliably avoid this. If the heating front has skipped the first valve 9, it will also migrate through the intermediate piece 12.
    This can be avoided by flushing the intermediate piece 12 with an inert or non-reactive substance at the same time as the quick-closing valves 9, 11 close via the second inlet 13 and the second outlet 14. This substance can be nitrogen or a solvent, for example.
    A safety valve is preferably arranged between the two quick-release valves 9, 11, which is intended to prevent expansion of the thermal front or deflagration. The safety valve can be arranged in the second outlet 14, for example. It is not shown here. By using the safety valve, the PED guideline is fulfilled, which requires that a protection against thermal expansion must be installed between two valves that are closed at the same time.
    Thanks to the structural design of the lock 5 ″ according to FIG. 6, it is no longer possible for the reactive, decomposing medium to build up a new heat front and thus to wander unhindered through the pipeline of the entire system.
    In the following, the design of the component of the deflagration protector according to the invention is explained using an example: The component essentially consists of a body 10, for example a cylinder, which has axially extending cavities that are drawn from the feed streams at the inlet or from Reaction product are flowed through at the outlet. The cavities are, for example, small bores in a perforated plate. Alternatively, the body 10 is made porous, so that it has relatively small channels and / or cavities, which, however, are of different sizes. The channels and / or cavities preferably have a diameter of less than 1 mm, preferably less than 0.5 mm, and even more preferably less than 0.3 mm.
    The body is, for example, a sintered body or it is foamed or produced by means of additive manufacturing, i.e. 3D printing. The body is installed in a flow channel and characterized by means of flow tests, so that the resistance factors α can be determined both in the laminar and in the turbulent flow range. The pressure loss over this body in normal operation should preferably be less than 5 bar, preferably less than 1 bar and particularly preferably less than 0.2 bar.
    The maximum permissible pressure drop is then determined based on strength values and the length of the body 10 is determined. The body 10 should preferably allow a maximum permissible pressure drop of greater than 10 bar, preferably greater than 50 bar and particularly preferably greater than 100 bar.
    The open channels or cavities of the body are preferably smaller than 1 mm, preferably smaller than 0.5 mm and particularly preferably smaller than 0.3 mm. For a version smaller than 0.3 mm, an additional proof of calculation according to Frank-Kamenetskii or Baers is not necessary.
    Finally, the maximum temperature increase ΔTmax in the body 10 can now be determined. The Phi factor of the body 10 is preferably greater than 1.5, preferably greater than 2.0 and particularly preferably greater than 2.5.
    If the maximum temperature increase ΔTmax in the reactor or in the reactor section is known and if T0 + ΔTmax> TONSET, a redundant design according to FIG. 6 is preferably used.
    An exemplary embodiment of such a body 10 according to the invention is shown in FIGS. 7a and 7b. In this example, it has a solid, i.e. filled, cylindrical base body which is penetrated by a large number of channels running in the longitudinal direction. The channels can be clearly seen in FIG. 7b. They extend over the entire length of the body 10 and they are continuously open.
    The body according to the invention is pressure-stable, withstanding a high operating pressure as well as a high pressure loss. It preferably withstands pressures of up to 400 bar. The compressive strength of such a body can be demonstrated, for example, by means of the known FEM calculation (Finite Element Method).
    The body according to the invention also has a high Phi factor, i.e. the mass fraction of the body is sufficiently large so that the migration of the warm front is delayed for a sufficiently long time. The maximum permissible diameter of the channels can be calculated using the Frank-Kamenteskij method or the Baers method, for example.
    The mode of operation of preferred deflagration protectors according to the invention is described below. If there is a deviation from normal operation, a thermal runaway, a so-called “hotspot”, can occur in one of the tube sections of the tube reactor. In such a “hotspot”, the educts are suddenly and completely converted and severe local overheating occurs. If the temperature exceeds the maximum permissible ONSET temperature, a decomposition reaction occurs. This can be expressed as follows:does not fizzle out and has a minimal effect on heating and pressure (no deflagration),slowly deflagrates with little heating and little pressure increase including the reactor volume (slow deflagration),fizzles out quickly and has a significant influence on the warming and pressure increase including the reactor volume (deflagration),thermal explosion with a sudden increase in temperature and pressure (detonation).
    In all cases, the decomposition can lead to gas or steam production, depending on the operating pressure. There are also reactions that can produce both gas and steam.
    In the tubular reactor with several segments, the decomposition takes place at one point along the reactor. At this point, there can be both an increase in temperature and an increase in pressure as a result of gas and / or steam production. With a steady rise in temperature, the heat front propagates along the reactor at the same time to the inlet and outlet of the reactor and it continuously decomposes the reaction liquid. The numerous temperature sensors along the reactor record this temperature rise and first trigger measures to prevent the event, i.e. the reactor is cooled or flushed with an inert fluid, for example. If this is unsuccessful, measures to limit the damage are initiated, i.e. the reactor is activated and at the same time closed by the deflagration protectors, so that the decomposition can only take place in the reactor.
    Deflagration is an explosion that can propagate at subsonic speeds. In these cases, the sensors that may be present in the reactor can usually only detect the heat front with a delay. In these cases, cooling a valve is insufficient to prevent reproduction. The body according to the invention with a very high intrinsic mass or a high Phi factor must hold up a rapidly moving heat front long enough so that the temperature sensors can detect the temperature increase and close the valves in good time. At very high decomposition temperatures, however, there is still a minimal risk that the mass can heat up and the warmth front propagates.
    The use of a rinsing system of the reactor according to EP 3 147 935 is advantageous because the rinsing is triggered at a lower temperature and the valves used here are usually the same quick-release valves as in the deflagration protector. This means that the quick-release valves are closed at an early stage. The quick-release valves are even used redundantly for critical applications.
    In the case of rapid decomposition, the educts are suddenly and completely converted at the “hotspot” and severe local overheating occurs. A decomposition reaction takes place with a simultaneous gas and / or steam production. As a result, the decomposition product expands as quickly as possible and pushes the reaction liquid in the event of a deflagration, respectively. Deflagration to the inlet and outlet at the same time. The pressure increases suddenly. A pressure sensor integrated in the reactor has fast response times and is able to operate the quick-release valves sufficiently quickly. Here, too, the body according to the invention has a very high intrinsic mass, respectively. a high phi factor, has considerable advantages. In this way, the narrow channels not only ensure a reliable thermal barrier, but also ensure a pressure increase with the pressure loss generated, which is reliably detected by the pressure sensor and can be reported to the control of the device or the system.
    The body in a deflagration protector is preferably designed as follows:- Calculation of the pressure loss in the body, where the volume flow, s the body length, η the dynamic viscosity, A the area through which the air flows and α the resistance factor.- Calculation of the mechanical strength based on the shear stress, where τ corresponds to the shear stress, F to the shear force and As the sheared area.- definition of a maximum allowable pressure drop,
    - where dp corresponds to the pressure drop, F to the force on the body and A to the area flowed through.- Calculation of the critical reactor diameter for the hotspot formation with known calculation models according to Frank-Kamenetskii or Baers. Experience has shown that the critical reactor diameters for hotspot formation are in a range of <0.75 mm.- Calculation of the adiabatic temperature increase in the body taking into account the phi factor,
    The device according to the invention serves as a damage-limiting protective device in that it prevents the thermal front from spreading.
    REFERENCE LIST
    1 pipe section 2 supply line 20 inlet opening 3 outlet line 30 outlet opening 4 safety valve 5 inlet-side lock 5 'middle lock 5 "outlet-side lock 6 bursting disc 7 metering pump 8 filter 9 first quick-action valve 10 body 11 second quick-action valve 12 intermediate piece 13 inflow 14 outflow L longitudinal axis L1 length of the Hotspots H Hotspot S Main flow direction
    权利要求:
    Claims (15)
    [1]
    1. Device for controlling a deflagration or a thermal detonation in a continuously operated chemical tubular reactor with at least one reactor section (1, 1 ', 1 "), wherein the tubular reactor has an inlet (2) and an outlet (3) and wherein the inlet (2) and the outlet (3) define a main flow direction (S) in the reactor, characterized in that the device has at least one barrier (5, 5 ', 5 ") for interrupting the inlet (2) and / or the outlet (3 ), wherein the barrier (5, 5 ', 5 ") has at least one valve (9, 11) and a body (10), the body (10) being designed to stop a heat front of deflagration or thermal detonation until the valve (9, 11) is closed.
    [2]
    2. Device according to claim 1, wherein the valve (9, 11) has a defined closing time and the body (10) holds the heat front at least during the closing time.
    [3]
    3. Device according to one of claims 1 or 2, wherein the valve (9, 11) is a quick-release valve with a closure time of a maximum of 1 second.
    [4]
    4. Device according to one of claims 1 to 3, wherein the body (10) is arranged in the direction of propagation of the heat front in front of the valve.
    [5]
    5. Device according to one of claims 1 to 4, wherein the lock (5, 5 ', 5 ") is arranged in the inlet (2) and wherein the body (10) is arranged in the main flow direction after the valve (9, 11).
    [6]
    6. Device according to one of claims 1 to 5, wherein the lock (5, 5 ', 5 ") is arranged in the outlet (3) and wherein the body (10) is arranged in the main flow direction upstream of the valve (9, 11).
    [7]
    7. Device according to one of claims 1 to 6, wherein the lock (5, 5 ', 5 ") has a first valve (9) and a second valve (11), wherein the second valve (11) in the direction of propagation of the heat front the first valve (9) is arranged.
    [8]
    8. The device according to claim 7, wherein a flushing unit (12, 13, 14) is arranged between the first valve (9) and the second valve (11).
    [9]
    9. Device according to one of claims 1 to 8, wherein the body (10) is a porous filter body.
    [10]
    10. Device according to one of claims 1 to 9, wherein the body (10) consists of a sintered or foamed material or is created by means of additive manufacturing.
    [11]
    11. Device according to one of claims 1 to 10, wherein the body (10) is cylindrical and its longitudinal direction extends in the main flow direction (S).
    [12]
    12. Device according to one of claims 1 to 11, wherein the device has at least one sensor for monitoring a reaction in the reactor and wherein the at least one valve (9, 11) can be closed in accordance with a signal from the sensor.
    [13]
    13. Device according to one of claims 1 to 12, wherein at least two pipe sections (1, 1 ', 1 ") are present, which are connected in series one behind the other, and wherein between the two pipe sections (1, 1', 1") a bursting disc (6) and / or a safety valve (4) is arranged.
    [14]
    14. Device according to one of claims 1 to 13, wherein the body (10) has open channels and / or cavities and wherein the channels and / or cavities have a diameter of less than 1 mm, preferably less than 0.5 mm, and more preferably of less than 0.3 mm.
    [15]
    15. A method for controlling a deflagration or a thermal detonation in a continuously operated chemical tubular reactor with at least one reactor section (1, 1 ', 1 "), wherein the reactor has an inlet (2) and an outlet (3) and wherein the inlet (2) and the sequence (3) define a main flow direction (S) in the reactor, the method having at least the following steps:- Monitoring a chemical reaction taking place in the reactor,- Closing at least one valve (9, 11) in the inlet (2) and / or in the outlet (3) in the event of an uncontrolled reaction sequence of the monitored chemical reaction and- Delaying the spread of a heat front resulting from the uncontrolled reaction sequence in the direction of the valve (9, 11) at least until a point in time at which the valve (9, 11) has closed at least approximately completely.
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    同族专利:
    公开号 | 公开日
    DE102020126882A1|2021-04-22|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    EP19204238|2019-10-21|
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