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TNT MANUFACTURE^371

All nitrators are provided with regulators controlling the supply of cooling
water. According to A. B. Bofors, the raw material consumption per 1000 kg TNT

is as follows:

toluene

nitric acid (99%)

sulphuric acid (100%)

supplied in the form of 95%

sulphuric acid and oleum

450 kg

1000 kg

1850 kg

A flow sheet and general view of the Bofors plant is given in Fig. 88 and 89

respectively. A general lay-out is given below (Fig. 101).

Swedish-Norwegian Chematur and Norsk Spraengstoffindustri method

This method [22] patented in Sweden in 1953 employs stepwise nitration of

mono- and/or di-nitrotoluene to trinitrotoluene in a series of counter-current units,

each unit consisting of a nitrator and a separator.

The principle of the design of the unit is given in Fig. 90. Nitrator N consists

of a U-vesselwith two legs or shanks (1) and (2) joined by pipe (6). The components

of the reaction are introduced through inlets (4) and (5). Liquid can be kept in circu-

lation from leg (1) to leg (2) and back by the turbine-wheel (8) on the driving-shaft (7).

By regulating the speed of the turbine (8) and adopting suitable proportions for pipes

(3) and (6) it is possible to keep the liquid at a higher level in leg (2) than in leg (1). Sepa-

rator S communicates with the nitrator through pipe (9). The separator is shaped

as a rectangular box (10) with distributor (II) for the mixture coming from the reactor,

an outlet (12) for the separated light component and an outlet (13) for the heavy

component. At some distance from the inlet and between the levels of the outlets
for the separated components there is also another outlet (14) for partly separated

emulsion. This outlet has adjustable plates (15) and (16) to make it possible to adjust

the opening of the outlet with reference to its level in the separator. The partly

separated emulsion is led back to the reactor through pipe (18) and regulating valve (17).

To control the temperature of the reaction mixture the unit is equipped with heat

exchangers (19) and (20). The separator may also have a heat exchanger jacket not

shown in the diagram.

The unit is operated in the following way. The reactants are introduced through

inlets (4) and (5), mixed with the help of turbine (8) and circulated through pipe system

(1), (3) and (6) chemical reaction and physical exchange being simultaneously effected.

They are continuously transported to the separator in the form of an emulsion.
In the separator the components are separated, the light component (nitro com-

pounds) rising to the surface and flowing off continuously through outlet (12). The

heavier component (spent acid) sinks to the bottom and is removed continuously

through outlet (13). In the area between the separated components the partly sepa-

rated emulsion is withdrawn and led to mixing part of the reactor. This transport
is possible because the level of the liquid in the separator through leg (2) is higher