MXPA97002470A

MXPA97002470A - Reactor for sludge phase and its

Info

Publication number: MXPA97002470A
Application number: MXPA/A/1997/002470A
Authority: MX
Inventors: Jens Zarnack Uwe; Witt Harro; Beckhaus Heiko
Original assignee: Bayer Ag 51373 Leverkusen De
Priority date: 1994-10-07
Filing date: 1997-04-04
Publication date: 1999-01-11

Abstract

The present invention relates to a reactor (1) for exothermic reactions in the sludge phase, which exhibits as a heat exchanger (2) an annular space covered above and below by the reactive mass, the annular space exhibiting multiple channels of step (21) vertical circular section for the reaction mass and through the cooling agent the annular space between the passage channels for the mass react

Description

REACTOR FOR SLUDGE PHASE AND Sü USE FIELD OF THE INVENTION The reactions in the sludge phase are. reactions in which at least one finely divided solid phase and a liquid phase are involved. BACKGROUND OF THE INVENTION Reactions in the phase of strongly exothermic sludges demand an effective evacuation of the heat of reaction. For this reason, reactors for sludge phases exhibit expensive heat exchanger constructions inside the reaction tank, see for example US-A 3 243 268 or EP-A 263 935. In known reactors for sludge phases the heat exchange is carried out by pumping the mass in reaction by the so-called "Field" heat exchanger tubes or by boiling tubes closed at one end in which the agent for heat transfer and the originating vapor are conducted in countercurrent. In these, the different current velocity of the reactant mass relative to the reactor enclosure and the poor performance of the heat exchanger caused thereby are disadvantageous. The different current velocity of the reactant mass causes backwash zones in the stream, in which the solid components involved in the reaction can settle. It is now proposed, according to the invention, to provide as a heat exchanger a reservoir traversed by the heat transmitting agent essentially only in one direction, REP: 24449 the tank being equipped with a plurality of circular section passage channels for the reaction mass. According to the invention, according to this, the reaction mass is conducted in the changer in the opposite direction, in comparison with the conventional evaporation heat exchangers. DESCRIPTION OF THE INVENTION The object of the present invention is a reactor for sludge phase, for exothermic reactions in the sludge phase, which contains the following elements: a) A reaction tank, b) A heat exchanger in the form of a space annular inside the reaction tank, crossed by the cooling agent and the reaction mass, the annular space being covered below and above by the reaction mass, c) A central free cavity for current inside the annular space for the return current- of the reaction mass, d) A central stirrer that drives the circulation of the reactant mass between the central free cavity for current and the annular space, with the characteristic that the annular space exhibits multiple vertical passage channels of circular section for the mass reactant and the cooling agent passes through the annular space between the passage channels for the reaction mass.

Preferably, the annular space of the heat exchanger is traversed by the reactant mass and agent for heat transfer with essentially the same current direction. In particular, the passage channels for the reactant mass pass through the annular space vertically upwards. In this case, the agitator is preferably arranged in the lower outlet of the central free cavity for current and places at least one of the reaction components in the immediate vicinity of the agitator, so that on the one hand a rapid diffusion of the reaction components - in the reaction mass and, on the other hand, the reaction component fed with the reaction mass is introduced very quickly in the heat exchanger. For the execution of the continuous reaction, an overflow in the reaction tank is provided above the level of the liquid, through which the transformed reaction mass is continuously removable. As the heat transfer agent, an agent which evaporates at the reaction temperature, which is fed in liquid form through the bottom of the annular space of the heat exchanger and is extracted in gaseous form by the head of the annular space of the heat exchanger, is preferably used. heat exchanger. Water is particularly preferably used as a heat transfer agent and the heat exchange is carried out with steam production. The temperature of the coolant is preferably adjusted by maintaining a vapor pressure originating. Reactions involving a gas phase are preferably carried out in the reactor for sludge phases according to the invention. To this end, the agitator is executed in the form of a gasifier agitator or exhibits an additional gasifier element. The slurry reactor with gasifier agitator according to the invention is particularly suitable for carrying out phase hydrogenations of aromatic nitro compounds, with particular preference for the hydrogenation of dinitrotoluenes, with production of the corresponding diamines. The invention is clarified in more detail by virtue of the attached figures 1 and 2: Figure 1 shows a cross-section of the reactor for sludge phases according to the invention. Figure 2 shows a section AA of the cross section of the reactor according to figure 1. The reactor according to figure 1 is composed of a reaction tank 1, which is constituted by three parts that are joined with flanges 11 and 12 The central part of the reaction tank 1 contains the annular heat exchanger 2, which is composed of an annular space closed on all sides and crossed by a plurality of passage tubes 21 which in turn are crossed by the reacting mass in current ascending in the direction of the arrows. In the remaining interstitial space 22 of the annular space 2 is the agent for heat transfer. The return current of the reaction mass is effected, as indicated by the arrows, through the central free cavity for current 3, inside the annular heat exchanger 2. The circulating reactive mass flow is driven by the agitator 4, with central shaft of agitator 41 driven from outside the reactor and blades of agitator 42. Here, the blades of agitator 42 are arranged at the height of the mouth of the central free cavity for stream 3, downwards. In the illustrated embodiment, the axis of the agitator 41 is executed in the form of a hollow shaft and exhibits below the blades of the agitator 42 a gasifier device 43. The gas for the gasification of the reaction mass is sucked out of the gas chamber of the reactor. upper part of the reaction tank 1 through suction holes 44 in the agitator shaft 41. By means of the gas supply connection 45 a predetermined gas pressure is guaranteed. In the preferred use of the reactor according to the invention for the hydrogenation of aromatic nitro compounds, hydrogen is used at a pressure of 10 to 40 bar. Advantageously, the fresh hydrogen feed can be made directly to the reaction mass. The aromatic nitro compound is introduced through the feed line 5, in the immediate vicinity of the agitator blades 42. As the finely divided solid phase, the hydrogenation catalyst, for example noble metals or nickel on particles, is dispersed in the reaction mass. support as carbon, Si? 2, A1203 and so on, or else Raney nickel catalysts. The product is continuously extracted by the overflow 7, so that a constant level of liquid is maintained. The annular space of the heat exchanger is furthermore fed by a circulation of heat exchange agent 6. The heat exchanging agent, preferably water just below the boiling point, is introduced into the heat exchanger from below, in the heat exchanger. The water vapor leaves the heat exchanger at the top, by 62, and is introduced into the steam separator 63. The arrow 64 indicates the derivation of the steam for the recovery of energy. The feed valve 65 for the cooling water is controlled by a level regulator 66 for the height of the water in the steam separator 63. In the preferred use of the reactor according to the invention for the hydrogenation of aromatic nitro compounds, the pressure of the The cooling agent 64 is regulated in such a way that a temperature of 120 to 250 ° C is maintained in the reactor. The numbers in figure 2 designate the same elements as in figure l. The passage tubes 21 are only partly represented. The heat exchanger 2 can exhibit from 100 to 3,000 pipes of passage 21 according to the nominal diameter of the pipes (25-10 mm) and the diameter of the heat exchanger (up to 3 m). It is noted that, regarding this date, the best method known by the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims

CLAIMS 1. Reactor for sludge phases for exothermic reactions in sludge phases, which contains: a) a reaction tank, b) a heat exchanger in the form of an annular space crossed by the heat exchange agent and the reactant mass, which is covered below and above by the reacting mass, c) a central free cavity for current, for the return current of the reactant mass within the annular space, d) a central stirrer that drives the circulation of the reactant mass between the central free cavity for current and the annular space, characterized in that the annular space exhibits multiple vertical passage channels of circular section for the reactive mass and the heat exchanging agent crosses the annular space between the passage channels for the reactive mass.
2. Reactor for sludge phases according to claim 1, characterized in that the agitator is also executed in the form of a gasified agitator.
3. Reactor for sludge phases according to claim 1 or 2, characterized in that the stirrer drives the reactive mass downwards in the central current chamber and causes an upward current in the vertical passage channels. Reactor for sludge phases according to one of claims 1 to 3, characterized in that the stirrer is arranged in the opening of the central cavity free for current and is executed in the form of a loop. Reactor for sludge phases according to one of claims 1 to 4, characterized in that at least one of the reaction components is introduced into the reaction mass in the immediate vicinity of the agitator. Use of the reactor according to one of claims 1 to 5 to carry out hydrogenations in sludge phases. Use according to claim 6 for the hydrogenation of aromatic nitro compounds. Use according to claim 7 for the hydrogenation of dinitrotoluenes. Process for carrying out hydrogenations in the sludge phase with the use of a reactor according to one of claims 1 to 5, characterized in that water is used as the cooling agent and useable steam is produced.