Schmid-Meissner process

The process invented by Schmid and improved and developed by Meissner [40] has since been adopted in many factories. A distinctive feature of the improved method consists in the extensive use of metering devices and rotameters. 

Nitroglycerine is discharged from the separator (17) through an overflow (17a) and passing through injectors (22c) (23c), (24c) it enters in turn the washing columns (22), (23) and (24). 

In the earlier design when the plant was started up, the first nitroglycerine produced may be polluted by slime from the nitrator and separator. It is therefore transferred to a hand washer (17b) to be washed as in batch production. 

In more modem designs there is no slime in the nitrator and separator as the whole installation is constructed of high-grade acid-resistant steel. The washing tank is maintained, however, in order to wash the residue of nitroglycerine remaining in the separator when the installation is shut down. 

To the separator, an overflow for spent acid (18a) is fitted, by means of which the height of the boundary layer between the two liquid phases can be regulated. Spent acid flows down to a pressure-egg (19), from which it is discharged by means of compressed air to a tank (18) (only a part of the pipe is shown) and then to setling tanks as in the combined process, (p. 95). 

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Continuous Schmid-Meissner process for NG DEGN manufg, as used in Germany during WWII Continuous method for manufg PETN) 23)R.Ashcroft et al, BIOS Final Report 833orPB Rept 63877 (1946), Item 2,... 

Urbanski 2 (1965), 99—106 (details of Schmid and Schmid-Meissner process)... 

Continuous methods of nitroglycerine manufacture Schmid process Washing nitroglycerine Schmid-Meissner process Raezyhski process Biazzi process... 

The great advantage of the Schmid-Meissner and the Biazzi processes is the small amount of separated explosive present in the plant at any given time—up to 10% (and 4% respectively) of the output per hour—the remainder of the nitroglycerine in the system is in a safe emulsified form. 

Continuous process for nitrating aromatic com-pds at Brookes Chemicals Ltd, England) 14)Stett-bacher (1933), 158-62 (Continuous processes of A. Schmid J. Meissner schematic view of Schmid -Meissner installation) 15)M.Biazzi, ItalP 322990 (1935) (Continuous process for manuf of NG) (The US patent was filed in 1939 but was not granted until 1948. It is listed here as Ref 26) l6)Thorpe... 

Nitroglycerin. NG was manufd in Switzerland by the continuous methods of Schmid-Meissner and of Biazzi, which were preferred to batch processes (See Vol 3, C501-L ff)... 

Schmid Meissner s Process, It involves continuous miration of glycerine (or other liquids, such as ethyleneglycol or diethyleneglycol), separation of the nitrated product from spent acid, and pumfication by neutralization and washing. 

The aTctual nitration reactions in a continuous process are carried out in the same type of vessels as those used for batch nitrations, with the exceptions that an overflow pipe or weir arrangement is provided for the continuous withdrawal of products and that continuous feed of all reactants is provided. Schematic diagrams of two typical nitrators for continuous operation are shown in Figs. 4-9 and 4-10. Figure 4-9 shows the kind of nitrator designed for the German Schmid-Meissner system. In this apparatus the material to be nitrated is fed into the top of the nitrator and is... 

NG. Batch-wise production of NG is described in Vol 6, G99-102, and continuous methods such as the Schmid t-Meissner and Biazzi processes are discussed in Vol 3, C501 — 505. The Swedish injector process and the Hercules tubular nitrator will be described below, but before doing this we will discuss certain aspects of glycerin nitration that are common to both batch and continuous methods, and then contrast the main features of the batch process vs the continuous process... 

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