US3034867A

US3034867A - Continuous trinitrotoluene manufacture

Info

Publication number: US3034867A
Application number: US564073A
Authority: US
Inventors: Samuelsen Eirik
Original assignee: Chematur AB
Current assignee: Chematur AB
Priority date: 1955-03-23
Filing date: 1956-02-07
Publication date: 1962-05-15
Anticipated expiration: 1979-05-15
Also published as: NL95140C; CH350638A; FR1147136A; DE1048875B; NL205079A; BE546349A

Description

May 15, 1962 E. SAMUELSEN 3,034,867

CONTINUOUS TRINITROTQLUENE MANUFACTURE Filed Feb. 7, 1956 2 Sheets-She et 1 E. SAMUELSEN CONTINUOUS TRINITROTOLUENE MANUFACTURE May 15, 1962 2 Sheets-Sheet 2 Filed Feb. '7, 1956 3,934,857 Patented May 15, 1962 3,034,867 CONTINUOUS TRINITROTOLUENE MANUFACTURE Eirik Samuelsen, Gullaug, Norway, assignor to Aktiebolaget Chematur, Stockholm, Sweden, a corporation of Sweden, and Norsk Spraengstoiindustri A/ S, Oslo,

Norway, a corporation of Norway Filed Feb. 7, 1956, Ser. No. 564,973 Claims priority, application Sweden Mar. 23, 1955 Claims. (Cl. 23-266) This invention relates to the nitration of toluene and nitrotoluenes, and particularly to the manufacture of trinitrotoluene by continuous operation.

It has heretofore been proposed to manufacture trinitrotoluene by continuous operation in a series of nitrators and separators, as represented, for example, by the United States patent to Holley and Mott, No. 1,297,170, to Hock, No. 2,475,095, and to Norell, No. 2,594,675.

In all of these older proposals the mixture from a reaction vessel or nitrator is continuously fed to a separator in which nitrobody is separated from acid; the former being fed to the next nitrator in the series and the latter to a preceding nitrator and so on. In such systems the hold-up time in the nitrator will be of the same order for the toluene or nitrobody as for the nitrating acid.

It has now been found that when the nitrating acid is given a longer hold up time in comparison with the toluene or nitrobody in the nitrators several advantages over older processes are obtained. The nitration will be more complete in each step and a higher yield of trinitrotoluene will be obtained. Such a difference in holdup time can be arrived at simply by returning part of the separated acid to the nitrator.

The object of the present invention is, generally stated, to provide new and improved apparatus for continuous trinitrotoluene manufacture in a series of nitrators and separators in which the hold-up times of the reaction phases may be chosen at will.

Another object of this invention is the provision of such apparatus by which the volume of the separator can be made smaller than usual, thus reducing the quantities of explosives in operation i.e. obtaining greater safety in operation.

A further object is the provision of an apparatus by which the feed-back is accomplished by gravity.

Other objects will become apparent to those skilled in the art when the following description is read in connection with the accompanying drawings.

In accordance with the present invention, generally stated, partially separated emulsions are fed back from the separators to the nitrators, i.e. part of the emulsions introduced into the separators are brought back to the nitrators after that part of the disperse-phase or nitrobody has separated. It is desirable to feed back a quantity amounting at least to the half part of the total quantity of the saparated products, i.e. nitrobody and acid, which are leaving the separator. Normally the return current will be larger, say 5-15 or more times, the summary of the saparated products leaving the separator. With a large return current of partly separated emulsion, it is possible to bring down the quantities of unreacted toluene or nitrobody in the reaction products leaving the separators to negligible amounts. With a large return current only the larger drops or the more easily separated particles in the emulsion separate and go into the homogenous phase of outgoing nitrobody. The smaller drops or particles in the emulsion, which necessarily must have a longer time to separate, are returned to the nitrator to enter into a new mixing operation. The separator can thus be made smaller and proportioned after the times necessary to separate the desired part of the emulsions.

The apparatus according to the invention consists of a system of nitrator-separators, equipped with mixing devices, cooling devices, inlets and outlets for acids, nitrobody etc. as in other continuous toluene nitrating systems, and with means by which partly separated emulsion can be fed back to the nitrator. It is preferable to hold the level of the nitrobody in the separator above the level in the attached nitrator, to permit the partly separated emulsion to flow to the nitrator by gravity. The transport of emulsion from the nitrator to the separator can be performed with the help of a pump or the like. It is also possible to design the nitrator in such a way that a pumping efiect from the mixing device is obtained. The suction or the pumping effect from a mixing propeller-or turbine can thus be used. The nitrator can also be made in the form of an U-vessel with propeller or turbine in one leg. The liquid in the other leg will thus give a higher level to be used for transport of emulsion to the separator.

Referring now to the drawings for an illustrative embodiment of the invention FIGURE 1 shows a nitrator 1 with attached separator 2. The nitrator 1 is equipped with mixing propeller 3, driven 'by an electrical motor 4, cooling coils 5, inlets 6 and 7 for toluene or nitrobody respectively nitrating acid. The outlet 8 of the nitrator is connected to the inlet 9 of the separator. Through inlet 10 supplementary acid can be introduced. a lattice, sieve or net work 11 to distribute the incoming emulsion. There is also a pipe 12 to withdraw partly separated emulsion to the pump 13 and back to the nitrator 1 through pipe 14 and inlet 15. The amount of partly separated emulsion can be regulated by a valve 16. Separated nitrobody is continuously overflowing at the liquid level of the separator through outlet 17 and separated acid through an outlet 18 from the bottom of the separator. The nitrator as well as the separator can be modified in many ways. Instead of using a nitrator of ordinary shape as illustrated in FIG. 1, it can for instance be given the shape of an U-pipe as will be described in the following example. The separator can have a conical inlet to get a good distribution of the emulsion Without net work and the like. The outlet 12 for partly separated emulsion can have an adjustable prolongation for instance in the shape of a telescopic tube to make it possible to regulate the outlet in vertical as well as horizontal directions. The outlet can also be arranged in one or more of the sides of the separator. It is possible to give the separator vessel the form of a parallelepiped or a lying cylinder with more or less conical ends or of a standing cylinder with tangential inlet for the emulsion.

In FIGURE 2 there is shown a combination of two apparatus units, each consisting of nitrator and separator. In a complete apparatus for the manufacture of trinitrotoluene out of toluene at least three apparatus units are needed, one unit for each step of nitration. Normally 5-8 or more units are used as the reaction than are easier to control and higher output is obtained. The principle of a complete series of units will however be easily understood already from a combination of two apparatus units.

The nitrators 1c, 1d are in this case formed as U-tubes with propeller or turbine 30, 3d in one leg 19c, 19d communicating with the other leg 2%, 20d through bottom pipe 21c, 21d. At the upper part of the legs there is an

overflow pipe

22c, 22d. With the propeller 3c, 3d in function the liquid will rise in the

leg

20c, 20d thus creating sufficient liquid level in the

separators

2c, 2d to transport partly separated emulsion back to the nitrators without an extra pumping device.

Toluene or separated nitrobody from a preceding unit In the separator there is K 3 in the apparatus series is continuously introduced in the nitrator through inlet 60 and is reacted with separated acid coming from separator 2d through pipe 23d and introduced through inlet 70. Extra acid (supplementary acid) may be added through inlet 10c, 10d. Part of the circulating reaction mixture is removed through outlets 8c and conducted to the separator through inlet 9c. The reaction mixture partly separates in the separator; the separated nitrobody being led to the next nitrator 1d through overflow-outlet 17c and inlet 6d of the said apparatus. The separated acid is led through outlet 18c through overflow-pipe 230 to the preceding nitrator, or in the case of nitrator 1c being the first one in the unit series, to a spent acid tank or to a denitrator. Partly separated emulsion, the quantity being regulated by valve 16c, flows back to the nitrator 1c through pipe 120 and 140 respectively, and inlet c.

In the nitrator 1d and separator 2d the operation principle is the same. In the case where this unit is the last in the unit series, trinitrotoluene is withdrawn from the separator 2d through outlet 17d and fresh nitrating acid, or the components of nitrating acid, introduced into the nitrator through inlets 7d and 10d. Separated acid is removed from separator 2d through overflow-outlet 18d and conducted through pipe line 23d to the nitrator 10.

In a series of units it will be found that feed-back of partly separated emulsion has special advantages over feed-back of separated components. The whole system will be easier to control as the change of the conditions in one unit will not influence the other units. This is easily understood from the fact that the streams of separated products overflowing from the outlets of the separator are of the same size even if the proportions of nitrobody and acid, respectively, the hold up time of the phases are changed in the nitrators.

The hereinbefore described apparatus constituting the claimed subject matter of this application is intended for operation in accordance with a new and improved method of operation forming the claimed subject matter of my copending application, divided from this application and filed Sept. 14, 1961, under Serial No. 142,999.

I claim:

1. Apparatus for nitration of toluene and nitrotoluenes in a series of units each consisting of reactor and separator, the outlet from the reactor connected with the inlet of the separator, feeding means to feed nitrobody and nitrating acid in countercurrent through the system, the separator having an outlet between the top and bottom thereof for partly separated emulsion of nitrobody and acid, and recycling means to return partly separated emulsion of nitrobody and acid from said outlet from the separator to reactor in at least one unit of the series.

2. Apparatus according to claim 1 for nitration of toluene and nitrotoluenes to trinitrotoluene in a series of units each consisting of reactor and separator, in each unit the nitrator having a mixing device adapted to feed reaction mixture to the separator and partly separated emulsion from the separator to the reactor.

3. Reactor-separator unit consisting of a reactor, with mixing device, the outlet from the reactor connected with the inlet of the separator, the separator having an outlet near the top, an outlet at the bottom ascending to the proximity of the top outlet level, and a third outlet bettween the top and the bottom level, this intermediate outlet connected with the reactor, feeding means to feed mixture from the reactor to the separator and mixture from the intermediate outlet of the separator to the reactor.

4. Apparatus according to claim 3 wherein the mixing device in the reactor is adapted to feed mixture from the reactor to the separator and from the intermediate outlet of the separator to the reactor.

5. Apparatus according to claim 3, for nitration of toluene and nitrotoluenes to trinitrotoluene in a series of reactor-separator units each consisting of a unit as set forth in claim 3,

References Cited in the file of this patent UNITED STATES PATENTS 1,124,496 Maire Jan. 12, 1915 1,241,017 Quartieri Sept. 25, 1917 1,297,170 I-Iolley et a1 Mar. 11, 1919 1,638,045 Livingston et a1. Aug. 9, 1927 2,363,834 Crater June 30, 1942 2,370,558 Mares Feb. 27, 1945 2,402,180 Papazoni June 18, 1946 2,475,095 Hoek July 5, 1949 2,594,675 Norell Apr. 29, 1952 2,729,549 Roman et al. Jan. 3, 19.56 2,761,768 Diels et a1. Sept. 4, 1956

Claims

1. APPARATUS FOR NITRATION OF TOLUENCE AND NITROTOLUENES IN A SERIES OF UNITS EACH CONSISTING OF REACTOR AND SEPARATOR, THE OUTLET FROM THE REACTOR CONNECTED WITH THE INLET OF THE SEPARATOR, FEEDING MEANS TO FEED NITROBODY AND NITRATING ACID IN COUNTERCURRENT THROUGH THE SYSTEEM, THE SEPARATOR HAVING AN OUTLET BETWEEN THE TOP AND BOTTOM THEREOF FOR PARTLY SEPARATED EMULSION OF NITROBODY AND ACID, AND RECYCLING MEANS TO RETURN PARTLY SEPARATED EMULSION OF NITROBODY AND ACID FROM SAID OUTLET FROM THE SEPARATOR TO REACTOR IN AT LEAST ONE UNIT OF THE SERIES.