Batch weighing

Example 13.1 shows one reason that binary polycondensations are usually performed in batch vessels with batch-weighing systems. Another reason is... 

Example 13.1 shows one reason why binary polycondensations are usually performed in batch vessels with batch-weighing systems. Another reason is that some polycondensation reactions involve polyfunctional molecules that will crosslink and plug a continuous flow reactor. An example is phenol, which is trifunctional when condensed with formaldehyde. It can react at two ortho locations and one para location to build an infinite, three-dimensional network. This may occur even when the stoichiometry is less than perfect. See Problem 13.3 for a specific example. In a batch polymerization, any crosslinked polymer is removed after each batch, while it can slowly accumulate and eventually plug a flow reactor. 

The quantity of solid fuels used is generally controlled by some form of batch weighing which gives a high consistency. Variations in calorific value are, however, more problematic. They are generally resolved by a combination of blending deliveries and determining the calorific value daily on a representative sample. 

For many applications, volumetric measurement of feedrate is accurate enough and various proprietary feeders are available. Alternatively, some of the types of transfer equipment described in section 17.3.6.2 may give the required accuracy. Proprietary belt weighers are also available. For the highest degree of accuracy, however, batch weighing is recommended. 

Flaskless skip loading via slewing loading conveyor—batch weighs and loads shaft skips directly without the need for shaft side flasks... 

The batch house is solely responsible for the raw materials and cullets. Through cooperation with the Purchasing, the Research and Development, and the Melting Departments, a reliable, inexpensive supply of materials for the melting process is ensured. The computer-assisted calculation of the glass batch, taking the current raw materials analyses into consideration, and automatic batch weighing-in are indispensable aids. 

As with the bulk bag dischargers, the materials used in, and the application of, bulk bag fillers is wide and varied. However, the same proviso holds care must be taken to ensure that the system is adequately designed to take into account the flowability characteristics of the material. Some example materials and applications are the loading of polymer resins into a variety of container sizes the batch weighing of PET the filling of bags in a carousel... 

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