Nitroglycerine nitrating temperature

Originally 2% of water were added to the spent acid and this prevented the separation of nitroglycerine at temperatures from 10 to 15°C. Nevertheless in 1906 a tank filled with this dilute spent acid exploded while being transported. Further experiments showed that nitroglycerine can separate from acid diluted in that way if its temperature falls below 10°C. Addition of 5% water was therefore introduced, to prevent separation of nitroglycerine even at a temperature of 0°C. At the present time this procedure is widely used with new methods of nitration including continuous processes. 

The most reliable method of determining the quality of glycerine is the laboratory nitrating test. This should be carried out under conditions that correspond as closely as possible to those prevailing in the plant. During the laboratory nitration, temperature, the rate of separation of the nitroglycerine and the add layers, the contact surface of phases and so on should be recorded. 

Nobel invented a radically new design of nitrator for the manufacture of nitroglycerine. Originally it was made of sheet lead and equipped with a cooling coil supplied with water, (Fig. 15, p. 65) and later a water-cooled jacket made of wood was added (Fig. 28). In later versions of the Nobel nitrator the cooling jacket was omitted in favour of a four-fold cooling coil with which it was easier to control the nitration temperature. 

The Mikolajczak process is usually safer than nitroglycerine manufacture. It is necessary, however, to maintain a low nitrating temperature and to use acid free from oxides of nitrogen which favour oxidation reactions. Local overheating should be carefully avoided, because dilute acid is specially prone to produce oxidation processes. 

The relation between the chemical stability and nitrating temperature observed by Ropuszynski [29] in the instance of nitroglycerine (p. 43) and nitroglycol (p. 148) has been also confirmed with dinitrodiglycol. Diglycol nitrated at a higher temperature demonstrates improved stability owing to its lower content of residual acids. The relevant data are shown in Table 23. 

The reason why wet nitroglycerin starts the autocatalytic reaction later than dry nitroglycerin at the same temperature is not explainable herein. There may, however, exist some difference, in the mode of the decomposition reaction during the induction period of the autocatalytic reaction of nitrate esters, betw een the liquid water which may be present in wet nitroglycerin at temperatures near 55 °C and the aqueous vapor which may be present in wet collodion cotton at temperatures near 80 X. ... 

The stability of nitroglycerine is related to the trace impurity in the nitration process and the reaction temperature [x, 33], especially the impurities of trace metals and alkali metals in the processes of nitration and water-washing. Nitroglycerine obtained at relatively high temperature, before stability treatment in the common approach of washing by water and sodium carbonate solution, contains litde residue acids. The relationship between nitration temperature and stability is shown in Table 5.35. 

Control of exudation depends mainly on the suitable choice of the nitrocellulose used. Some lack of uniformity in this product is certainly desirable. This offers no serious difficulty, although it is necessary to ensure a constant watch on manufacturing processes to see that quality is maintained. In other gelatine explosives, particularly those containing ammonium nitrate, exudation can be induced by slow chemical reaction. The addition of alkalis, for example, can liberate ammonia which in turn can react with nitrocellulose and cause it to lose its power of binding nitroglycerine. Such effects are accelerated at high temperatures and under wet conditions and it is usual practice to test all explosives under such adverse conditions before they are put on the market. 

Originally, nitroglycerine was manufactured by batch process. This represented a significant hazard because literally tons of product and spent acid were maintained for several hours at elevated temperatures. In an attempt to reduce the hazard, the operation was changed from batch to continuous, a process in which the glycerine and nitrating mixture were separately fed into a reaction chamber. In this way, the residence time was reduced to several seconds, which obviously resulted in a safer operation. 

Cambrite—an ammonium nitrate explosive modelled on the German Car-bonits (see Table 124). It contained a small quantity of nitroglycerine, potassium or sodium nitrate and a considerable amount of carbonaceous material (e.g. wood meal, charcoal etc.). This material was added to prevent the complete combustion of the carbon included in the explosive (to carbon monoxide only), to reduce the heat of explosion and, in consequence, the temperature of the explosion. 

As can be seen, the gelatinous explosives of the Nobelite type, safe in the presence of methane, contain a small amount of calcium nitrate solution. Calcium nitrate was added to Nobelites to reduce the temperature of the flame of explosion. After World War I, small quantities of calcium nitrate in the form of a concentrated aqueous solution were added to the milled nitroglycerine powder (from the post-war surplus) used as a rock explosive. This was done to counteract dustiness e.g. Nitro-glycerinpulver 1 explosive had the following composition ... 

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