DD288318A5 - PIPE REACTOR FOR THE CONTINUOUS PERFORMANCE OF CHEMICAL REACTIONS UNDER PRESSURE IN FLUIDER PHASE - Google Patents

Abstract

The invention relates to a tube reactor for the continuous performance of chemical reactions under pressure in the fluid phase, which require intensive mixing, for example, several heterogeneous liquid phases in the reactor. For this purpose, the product flow in the equipped with static mixers 7 reaction tube 5 by pairwise synchronously oppositely acting pulse generator 1, 2 equally large pulse volume low-frequency longitudinal vibrations superimposed, which allows intensive mixing with high material and Waermeuebergaengen. Fig. 1 {tubular reactor; chemical reactions, continuous; Print; Static mixer; pulse; longitudinal vibrations; fluids; Phase; Intensive mixing; Pulse volume}

Description

Explanation of the essence of the invention

The object of the invention is to provide a tubular reactor for the continuous implementation of chemical reactions in the fluid phase under pressure, in which allow the formation and arrangement of the vibration generating means an improved mixing effect and a simple design and manufacturing technology favorable design of the reactor.

According to the invention, this object is achieved in that arranged in pairs synchronously oppositely acting pulse generator with the same large pulse volume and are effective in front of and behind the equipped with static mixer elements pipe section.

By erfindungsgemäUe training of the tubular reactor surprising advantages are achieved in the continuous implementation of chemical reactions under pressure in the fluid phase. The arrangement of pairwise synchronously oppositely acting pulse generators equal pulse volume causes an almost complete reduction of the work-related strong pressure fluctuations according to the prior art. Despite high local turbulence, a nearly ideal plug flow is achieved with intensive mixing of the reactor contents transversely to the flow direction. The energy expenditure otherwise required in the case of damped oscillations for the compression work is eliminated. The pulse energy introduced into the reaction system is utilized to a very high degree for the mixing process. During the entire course of the reaction, a nearly constant mixing effect in the reactor is achieved. The intensive mixing of the reaction components thus achieved causes a very good mass and heat exchange. This results in connection with the full utilization of the reactor volume due to the hydraulic operating condition to particularly high space-time yields. The hydraulic state in the reactor also guarantees a high degree of safety, as in the case of Havana-related pressure increase by removing very small amounts of liquid there is the possibility of rapid pressure relief and thus the restoration of a safe state. Since the mode of vibration generation completely excludes the formation of pressure waves and the occurrence of pressure fluctuations and prevail throughout the reactor practically same, extremely good mixing conditions, the reactors can be shortened in their length and made of a material substantially lower pressure resistance.

The technical-economic production costs for the tubular reactor can thus be considerably reduced. The abovementioned advantages therefore make it possible to design a reactor according to the invention cost-effectively, with regard to materials and production technology, with comparatively short overall lengths and optimum adaptation to the requirements of the respective chemical reaction.

embodiment

The invention will be explained below with reference to several examples. In the accompanying drawing show

Fig. 1: a tubular reactor according to the invention in a schematic representation

Fig. 2: a variant of the pipe reactor according to the invention with several to a tube bundle

summarized pipes in a schematic representation and Fig. 3: a further embodiment of the tubular reactor according to the invention m> t two series-connected reaction tube in a schematic representation.

As shown in FIG. 1, the tube reactor consists of a reaction tube 5 with static mixer elements 7 arranged therein. The reaction tube can consist of one or more tube sections (FIG. 3). As static mixer elements, the proven in practice static mixer, such as Kenics mixer or ISG mixer can be used. Depending on the specific reaction conditions, a pipe section has a length of 0.1 to 10 m at 5 to 300 mm in diameter. Each em beginning and at the end of a pipe section are arranged in pairs synchronously opposite acting pulser 1.2 with the same size pulse volume. As a pulse generator, for example, piston pumps, diaphragm pumps or other vibrating displacer can be used. Since the tubular reactor shown in Figure 1 consists only of a pipe section, the pulse generator 1,2 are connected to the entry side 14 and to the discharge side 15 of the reactor. The reactor furthermore has metering devices 9, 10, via which the reaction components are supplied in the required amounts to the reaction tube 5. The metering devices 9,10 are arranged directly on the entry side 14. On the discharge side 15 of the reactor, there are an emptying member 12 and a Notentspannungsorgan 13. About the pressure in the reactor chamber regulating En.tleerungsorgan 12, the reaction product is discharged and by the Notentspannungsorgan 13, if necessary, the reaction pressure can be lowered quickly. The reactor is provided with a heating / cooling jacket 16, in the cavity of which a heat transfer medium circulates, depending on the type of reaction, whether endothermic or exothermic, to heat or cool. In the variant shown in Figure 2, a plurality of reaction tubes 5, which are equipped analogously as in Figure 1 with static mixer elements 7, combined to form a tube bundle. This is surrounded by a common heating / cooling jacket 16, in the cavity of which circulates a heat transfer medium. At the entry side 14 of the reaction tubes 5, these are connected via a corresponding distributor system 18 with the metering devices 9, 10 for the reaction components. At the discharge side 15 of the reaction tubes 5 is a manifold 19 with the emptying member 12 for the reaction product and the Notentspannungsorgan 13. Each before and behind the pipe section forming a reaction tubes 5, the pulse generator are connected 1.2. For economic reasons, it is advantageous to use only one pulser pair for the entire system.

FIG. 3 shows a tube reactor which consists of two separate tube sections 20, 21, which are arranged side by side and connected in series. The pipe sections 20, 21 correspond in their construction to the pipe-type reactor according to FIG. 1. The two pipe sections 20, 21 are connected via a line system 22, in which the emergency release device 13 is arranged. In addition, the pipe section 21 is still connected to a further metering device 11, via which a further component can be supplied.

The mode of action of the tubular reactor used to carry out chemical reactions under pressure in the fluid phase is as follows.

In the start-up phase, the tube reactor is first charged with an inert liquid or with one of the reaction components. According to another variant of the operation, the tubular reactor is completely filled, so that no gas cushion can form in it. Thereafter, the reaction components are fed gas-free by means of the metering device 9,10 in the required ratio. As soon as the intended system pressure is reached, the pressure regulating emptying member 12 opens as components are metered into the reactor, forming a continuous stream of product. This is superimposed by means of the two synchronously opposite with equal pulse volume pulse generator 1,2 a low-frequency longitudinal vibration whose amplitude along the whole provided with static mixer elements 7 pipe section is practically the same size. In this way, a mixing of equal intensity of the reactor contents is effected in this pipe section. Nevertheless, the characteristic of a plug flow through the reactor is maintained.

After displacement of the inert liquid and after reaching a constant ratio of all components in the reactor this has reached its steady state. The intensive mixing of the reactor contents ensures an extraordinarily good mass and heat exchange at almost isothermia of the reaction mixture transverse to the flow direction. In the following, the operation of the invention will be explained by a few examples.

Example 1: Preparation of 4-nitraniline

The preparation of 4-nitraniline takes place in a reactor according to FIG. 3, consisting of two 8 m long double mantcl reaction tubes 5, β filled with perforated disks as static mixer elements 7, 8 with a total volume of 30I. Mittete two Dosiervorrichtuhgen 9,10 are fed continuously in the start-up phase with ammonia solution completely filled reactor 63.6 l / h 30% aqueous ammonia solution and 8.4 l / h of molten 1-chloro-4-nitrobenzene. As metering devices high pressure piston pumps are used. By circulating in the heating / cooling jacket 16,17, superheated as in the phase transition liquid / vapor pressure water located in the pipe section 20, a reactor temperature of 240 degrees C and in the pipe section 21, a reactor temperature of 255 degrees C. By means of the pulse generator 1, 2, 3, 4, the reactor contents are mixed in undamped longitudinal oscillations of a frequency of 1.5 Hz. As pulser 1,2,3,4 high pressure diaphragm pumps are used. By means of emptying member 12, a system pressure of 16.0 MPa is set. The reaction mixture is discharged by means of the emptying member 12 and worked up in a conventional manner. After reaching steady-state operating conditions, 8.8 kg of 4-nitraniline are obtained every hour.

Example 2: Preparation of methyl mono and methyl diglycol ethers

In a provided over the entire solution with Kenics static mixer elements 7 reaction tube 5 according to Figure 1 of 8 m length and with a working volume of 20I by means of two dosing devices 9,10 every hour 5, oil and 0.741 ethylene oxide against a set by means of an emptying member 12 system pressure fed from 12.0MPa. The reaction temperature is maintained at 208 to 210 degrees C by superheated pressurized water in the heating / cooling jacket 16. The pulse generators 1,2 offset the reactor contents in undamped longitudinal vibrations with a frequency of 1.0 Hz. As pulser 1.2 Hochdruckmemberanpumpen be used. After reaching steady-state operating conditions 12 reaction mixture is removed by the emptying member, which contains no more ethylene oxide. After separation of the excess methanol, which passes through the methanol metering 9 again used, the reaction mixture is worked up in a known manner distillato ν. There are obtained 1.08 kg / h of reaction products which correspond in composition 84 to 86% methyl monoglycol ether, 10 to 12% methyl diglycol ether and about 3% higher ethoxylated products.

Example 3: Preparation of N, N-dimethylaniline

In an analogous manner as described in Example 2 tubular reactors are fed by metering 9.10 per hour 3.8 kg aniline, 4.2 kg of methanol and 0.4 kg of concentrated sulfuric acid against the set by means of emptying 12 system pressure of 8.5 MPa. The reaction temperature is 235 degrees C. The reaction mixture leaves the reactor via the emptying member 12 and is worked up in a manner known per se. Ν, Ν-Dimethylaniline is obtained in 94% yield.

Claims (1)

-1- 288 31P claim: Tubular reactor for the continuous performance of chemical reactions under pressure in fluid phase, consisting of one or more pipes which can be combined with counterpressure-operated metering devices and a drainage system regulating the system pressure, wherein the or the tubes of the reactor are internally equipped with static mixer elements and provided with means, which set the reaction Gamisch in oscillations, characterized in that arranged in pairs synchronously oppositely acting pulse generator (1,2,3,4) with the same large Impulsvol'jmen and in each case in front of and behind the static mixer elements (7,8) equipped pipe section are effective. For this 3 pages drawings field of use The invention relates to egg. , λ tubular reactor for conducting chemical reactions under pressure in fluid phase and is used for example in ammonolysis, oxyethylation, alkylation, cyanethylation and saponification reactions. Characteristic ies known prior art It has long been known, for carrying out chemical reactions in fluid phase, to use reactors with special mixing devices in order to achieve intensive mixing of the reaction components or of the reaction mixtures. Thus, for example, vibrating perforated disks, other disc-shaped profiled internals, vibration and pulsation columns are known (DE-OS 1767271, DE-OS 1767596, DE-OS 2221734, EP 221849). In the journal Chem. Techn. 26.1974.9, pp 554-557 a device is described in which locally turbulent flows are generated by the change of compression and relaxation of the liquid space located above the gas chamber and arrangement of baffled baffles. Pre-scrubbed type devices are not suitable for conducting chemical reactions under fluid-phase pressure. Their application is limited to material and / or heat exchange processes. An intensive mixture of fluid phases was made possible by the development of so-called static mixers. They are very diverse in their embodiments and differ with the same effectiveness by necessary number of stages, pressure loss and more or less complicated production technology (Chem. Ing. Techn. 52 [1980], 4, pp. 285-291). Due to their principle of action, however, they require relatively high flow velocities which, in accordance with the respective process duration, in particular in the case of a rapidly remixing phase, require very long mixing distances and thus very large tube lengths. An apparatus for producing aromatic nitroamino compounds has already been proposed. The reactions to nitranilines by ammonolysis of Halogennitroaromaten with ammonia or a kuakettigen aliphatic mono- or diamine in fluid phase carried out under pressure and elevated temperature. The device consists of a sloping tubular reactor with a feed opening and an emptying organ regulating the system pressure in the reactor. The tubular reactor can be combined from several individual tubes into one system. The tubes of the reactor are provided with an outer jacket space in which a heat transfer medium circulates. At least in the first third of the reaction tube Statikmischerelomente known design are arranged. The reaction tube is connected to a pulse generator, for example a piston pump without valves. Thereby, the reaction components or the reaction mixture can be vibrated at a frequency of 5 to 3000 per minute at a small amplitude. In practice, it has been found that this type of vibration generation is associated with a variety of disadvantages. Regardless of whether consciously, as is familiar to those skilled in the art, with a gas cushion, for example a wind tank, or without such a work, there is a pronounced vibration damping. This inevitably leads to a loss of introduced pulse energy. The unavoidable formation of pressure waves forces a relatively massive design of the reactor, which in turn adversely affects the economy. The biggest disadvantage, however, lies in the uneven mixing characteristics in the reactor. Due to the rapid decrease of the discontinued by the pulsator Schwingungsampütude from its maximum to zero in the longitudinal direction of the reactor tube in this direction, the mixing effect also decreases steadily to zero, that is, it is effective only on a section of the reactor. As a result, no very high space-time yields are achieved in the reaction procedure. Object of the invention The aim of the invention is to reduce the technical-economic production costs for the tubular reactor and the energy consumption, to reduce the safety risk and to increase the Haum time yield.