Method and System for Monitoring a Chemical Reaction

Abstract

In a method for monitoring a chemical reaction in a continuously operated reactor with at least one tube section, wherein the reactor has an intake, an outlet and a main flow direction running between the intake and the outlet, substances are supplied to the reactor via the intake and a product mixture made up of these substances and the solidified products thereof is created in the reactor. The reaction is monitored and measures are taken to prevent an uncontrolled reaction process, wherein these measures comprise at least the following steps: interruption of the intake and outlet, active pressure relief of the reactor and flushing of the reactor with an inert substance. This facilitates a safe and efficient interruption of the chemical reaction.

Claims

1. A method for monitoring a chemical reaction in a continuously operated reactor with at least one tube section, wherein the reactor has an intake, an outlet and a main flow direction running between the intake and the outlet, wherein substances are supplied to the reactor via the intake and a product mixture made up of these substances and solidified products thereof is created in the reactor, wherein the reaction is monitored and measures are taken to prevent an uncontrolled reaction process, wherein these measures comprise at least the following steps: interruption of the intake and outlet, active pressure relief of the reactor and flushing of the reactor with an inert substance.

2. The method according to claim 1, wherein active pressure relief and flushing take place only after the intake and outlet have been interrupted.

3. The method according to claim 1, wherein active pressure relief and flushing take place simultaneously.

4. The method according to claim 1, wherein flushing takes place against the main flow direction of the reactor.

5. The method according to claim 1, wherein the main flow direction runs in a vertical direction and flushing takes place from top to bottom.

6. The method according to claim 1, wherein an inert gas is used as the inert substance for flushing.

7. The method according to claim 1, wherein an inert liquid is used as the inert substance for flushing.

8. The method according to claim 1, wherein the product mixture is flushed at pressure from the reactor by means of the inert substance.

9. The method according to claim 1, wherein the reaction mixture flushed from the reactor is flushed in a collecting tank provided with a second inert substance.

10. The method according to claim 9, wherein the reaction mixture is distributed in the collecting tank by a jet pump, a nozzle, a tube hole distributor or a similar means and mixed with the second inert substance.

11. The method according to claim 9, wherein the second inert substance is an inert liquid.

12. A system for implementing the method according to claim 1, wherein the system has a continuously operable reactor, having a main flow direction, with an intake for supplying substances to the reactor and an outlet for removing the product resulting from the substances through chemical reaction, wherein the system has controls with means for monitoring the reaction in the reactor, wherein the system has, in addition, safety means for preventing an unchecked reaction process, wherein these safety means comprise: at least a first shut-off means for shutting off the intake, at least a second shut-off means for shutting off the outlet, a flushing means tank and a flushing line from the flushing means tank to the reactor, wherein the flushing line is provided with at least a third shut-off means, a collecting tank for reaction mixture flushed out of the reactor and also a collecting line from the reactor to the collecting tank, wherein the collecting line is provided with at least a fourth shut-off means, wherein the aforementioned shut-off means can be opened and closed by means of the controls in accordance with the means for monitoring the reaction.

13. The system according to claim 12, wherein a jet pump, a nozzle, or a tube hole distributor is arranged in the collecting tank for mixing the back-flushed reactor mixture with a second inert substance found in the collecting tank.

14. The system according to claim 12, wherein the reactor is arranged in a vertical direction and the main flow direction takes place upwards from below.

15. The system according to claim 14, wherein the flushing line leads from the flushing tank to the upper end of the reactor, so that the flushing means flows through the reactor in the opposite direction to the main flow direction downwards from above.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Preferred embodiments of the invention are described below with the help of the drawings which are only used by way of explanation and should not be interpreted as limiting. In the drawings:

[0054] FIG. 1 shows a schematic representation of a system according to the invention having three horizontal reactor segments and a flushing device;

[0055] FIG. 2 shows a schematic representation of a system according to the invention having a vertical reactor and a flushing device and

[0056] FIG. 3 shows a schematic representation of a variant of the system according to FIG. 1.

DESCRIPTION OF THE INVENTION

[0057] Three embodiments of the system according to the invention are described below, with the help of which the method according to the invention can be understood.

[0058] The figures are purely schematic. Not shown, for example, are the means which monitor the reaction and also the electronic controls. The means and the evaluation are preferably used as described in the as yet unpublished EP 15 200 463.6.

[0059] The system according to FIG. 1 has a continuously operated tube reactor 1 with at least one tube section 1. If multiple tube sections 1 are present, they are preferably connected in series behind one another. At least one of the tube sections, preferably all tube sections 1, is/are preferably flowed through for the purpose of temperature regulation (i.e. heating or cooling) of a heat transfer medium. The tube sections are preferably provided with a static mixer or a mixer-heat exchanger.

[0060] At least when using the process monitoring according to EP 15 200 462, the tube sections are selected in such a manner that the temperature profile of the heat transfer medium has an approximately linear profile in each tube section.

[0061] Substances are fed to the reactor 1 via at least one supply line 2, 2, the intake. The substances are reactants such as main components, additives, activators, solvents, emulsion additives and catalysts. They may be present in liquid, gaseous or partially solid form. In addition, the reactions may be carried out in a diluted solution or also in a dispersion.

[0062] In the supply lines 2, 2 first flow meters 4, 4 are present which measure the flow of supplied substances. Each supply line 2, 2 is additionally provided with one, preferably two or more, first shut-off devices 3, 3, also referred to as shut-off fittings. These first shut-off devices 3, 3 are preferably arranged in the flow direction to the reactor 1 downstream of the flow meters 4, 4. They may also, however, be arranged upstream thereof. A first safety valve 14 with an outlet line 140 is arranged in at least one of the supply lines 2, 2. The first safety valve 14 is preferably arranged between two first shut-off devices 3, 3, as shown in FIG. 1. In case of only one single first shut-off device 3, the safety valve 14 is preferably arranged after the first shut-off device 3.

[0063] The first shut-off devices 3, 3 are connected to an electronic control which is not shown and are closed in accordance with this control. The shut-off devices are preferably valves, stop cocks or shut-off valves. They preferably have a spring closure.

[0064] The products of the chemical reaction taking place in the reactor 1 are removed via an outlet, more accurately a discharge line 15. In the example shown here, they reach a dwell time reactor 13 before they are moved on via an end line 16.

[0065] As a variant, a circulation line 22 can be provided in one or more of the tube or reactor sections 1, preferably in the first tube section 1 in the flow direction. This is depicted in FIG. 1. By means of a pump 21, the reaction mixture at the outlet of the corresponding tube section, in this case the first tube section 1, is fed back and introduced back into the reactor in the main flow direction further upstream. In the example shown, the line once again leads to the inlet of the first reactor section 1. This method and the advantages thereof are described in detail in WO 2017/080909.

[0066] Between reactor 1 and dwell time reactor 13 there is at least one second shut-off device 5. This is also preferably redundant, so that two or more second shut-off devices 5 of this kind are arranged in the discharge line 15. The second shut-off device 5, also referred to as the shut-off fitting, is likewise connected to the controls and can be closed by means thereof. It is likewise preferably spring-closing.

[0067] A second flow meter 6 for measuring the total volume flows of the product and a probe 7 for measuring substance properties is preferably present in the discharge line 15 between the reactor 1 and the dwell time reactor 13.

[0068] The second shut-off device 5 is preferably arranged in the flow direction upstream of these devices, like the second flow meter 6 and probe 7.

[0069] The dwell time reactor 13 preferably has a second safety valve 14. A further shut-off valve 17 is preferably arranged in the end line 16.

[0070] In addition, the system has a receiver for an inert substance, in particular an inert gas or an inert liquid. In the figures, this receiver is a flushing means tank 8. A flushing line 18 leads from the tank 8 to the outlet of the reactor 1. This flushing line 18 is closed using a third shut-off device 9 which is likewise connected to the controls and which is preferably spring-opening. The flushing line 18 preferably opens out into the discharge line 15, but upstream of the second shut-off device 5 in the flow direction of the product.

[0071] In the intake of the reactor 1, a collecting line 19 branches off which is closed using a fourth shut-off device 10. This fourth shut-off device 10 is also connected to the controls. It is spring-opening.

[0072] The third and fourth shut-off devices are preferably likewise redundant.

[0073] The collecting line 19 leads to a collecting container 12. An inert substance, preferably an inert liquid, is located in the collecting container 12. It may be the same substance as that located in the flushing means container 8 or another substance. In particular, the flushing means container 8 may be filled with an inert gas and the collecting container 12 with an inert liquid.

[0074] Means for mixing 11 are preferably available in the collecting tank 12 such as, for example, a jet pump and/or a nozzle and/or a tube hole distributor.

[0075] If data from the means for monitoring safety, which are not shown, should reveal that there is a risk of the chemical reaction in the reactor 1 following an unregulated course, the controls close the first and all second shut-off devices 3, 3, 5 and thereby separate the reactor 1 from the intake 2, 2 and outlet 15, in particular from the dwell time reactor 13.

[0076] The controls also open the third and fourth shut-off device 9, 10. Flushing means, i.e. the inert liquid or the inert gas, are fed under pressure into the reactor 1 and flow through said reactor in the opposite direction to the main flow direction of the reactor 1. In this case, the flushing means forces the reaction mixture out of the reactor 1 to the collecting tank 12. Here it is distributed via the mixing means 11 and mixed relatively quickly with the second inert substance already located in the collecting tank.

[0077] During this process, the reactor is also pressure-relieved or vented. This takes place through the opening of the third and fourth shut-off devices 9, 10. Any excess of inert substance can be removed via the line 20. Normally, the overflow is discharged into the atmosphere via an excess gas burner or via a scrubber. The excess may, however, also be removed for the purpose of cleaning or also for scrubbing.

[0078] The chemical reaction is thereby efficiently and reliably interrupted and damage can be avoided.

[0079] In the embodiment according to FIG. 1, the reactor 1 is depicted with three horizontal tube sections 1. Flushing therefore takes place with the vertical tubes. This arrangement is suitable as an inert flushing means both with the use of liquids or gas.

[0080] In the embodiment according to FIG. 2, the reactor 1 is vertically aligned. The intake is located at the bottom, the outlet at the top. The flushing means are introduced into the reactor 1 from the top downwards. This is particularly advantageous when a gas is used as the inert flushing means, as through this arrangement the gas forces the liquid reaction mixture downwards towards the intake and into the collecting tank 12 and the emptying of the reactor takes place even more quickly in case of an emergency. This vertical embodiment may also be formed with a plurality of series-connected tube sections 1, wherein the tube sections in this case are preferably stacked on top of one another, so that the outlet of the lower tube section 1 in each case lies below the intake of the upper tube section 1.

[0081] The embodiment according to FIG. 3 is a variant of the embodiment according to FIG. 1. This variant can also be used in the embodiment according to FIG. 2. It has been shown in the systems described above that very large gas volume streams can occur in a decomposition, so that the collecting line 19 as well as the outlet line 140 have to be chosen to be quite big. During the flushing procedure however the volumes are relatively small. This can be a problem, when the reacting fluid remains in the collecting line 19 and as well as in the outlet line 140 after the first safety valve 14 and when then it comes to a decomposition.

[0082] In the embodiment according to FIG. 3, the outlet line 140 of the first safety valve 14 is therefore connected to the collecting line 19. The collecting line 19 is preferably as short as possible and it has an incline. The collecting line 19 guides the reacting fluid into the collecting container 12 and dilutes it before a decomposition can take place. The collecting container 12 therefore forms a quench container. In case that it still comes to a decomposition, the decomposing gas can be discharged through the removal line 20.

[0083] The method according to the invention and the device according to the invention allow safe and efficient interruption of a chemical process in a continuously operating reactor, in particular a tube reactor.