Granulator monitoring

We conclnde that aconstic chemometrics provide the process operators with useful information which can be nsed to rnn the process with fewer critical and work intensive shutdowns. 

All experiments were set np so as to be realistic scenarios with respect to multivariate statistical process control (MSPC). The pilot plant grannlator is operated exactly as the industrial scale counterpart, but most of the experiments inclnded mnch more severe variation than will usually be found in an otherwise stable industrial production sitnation of similar duration (e.g. it is normally not necessary to change nozzle types, or to change prodnct types within snch short intervals). 

An independent issne is that all the most important parameter validations are both based on identical 10-segment cross-validations as well as proper test sets. The prediction results for granule moisture content have here been displayed in a time-dependent fashion, which is most relevant for the industrial process operators. 

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Fluidized bed granulation monitoring of a fertilizer product (urea) in a semi-industrial pilot plant (SIPP), illustrating the main features and benefits. 

The above-mentioned on-line spectroscopic techniques have involved granulation monitoring for particle size assessments and end-point control however there are other concerns involved with wet granulation which include polymorphic transformations or solvate formation that can affect end product quality. ... 

Effusivity Combines thermal conductivity, density, and heat capacity X Mixing, blending, granulation monitoring... 

Acoustic methods Active or passive X Solid, semisolid, and high viscose sample High shear granulation monitoring Crystallization monitoring... 

Pry, W.C. Stagner, W.C. Wichman, K.C. Computer-interfaced capacitive sensor for monitoring the granulation process 1 granulation monitor design and application. J. Pharm. Sci. 1984, 73, 420-421. 

Staniforth, J.N. Quincey, S.M. Granulation monitoring in a planetary mixer using a probe vibration analysis technique. Int. J. Pharm. 1986, 32, 177-185. 

Corvari V, Fry WC, Seibert WL, Augsburger LL. Instrumentation of a hi - ar mixer evaluation and comparison of a new capacitive sensor, a watt meter, and a strain-gage torque sensor for wet granulation monitoring. Pharm Res I992 9( 12) 1525-33. 

Elastase release from dense granules is monitored with a nonfluorescent substrate containing a coumarin derivative. When the substrate is cleaved, fluorescent aminomethylcoumarin is released. 

The hydration state of risedronate sodium was monitored continuously in a fluidized bed dryer and correlated to data on the physical stability of tablets made from the monitored material [275]. The final granulation moisture was found to affect the solid-state form, which in turn dictated the drug s physical stability over time. The process of freeze-drying mannitol was monitored continuously with in-line Raman and at-line NIR spectroscopies [276]. The thin polymer solvent coatings, such as poly(vinyl acetate) with toluene, methanol, benzene, and combinations of the solvents, were monitored as they dried to generate concentra-tion/time profiles [277]. 

In this chapter we illustrate development of acoustic chemometrics for process monitoring in the chemical engineering realm with a feasibility survey of the application potential for industrial applications. Earlier studies [3-7] describe the initial small- to medium-scale pilot experiments behind this approach, collectively giving a broad introduction to the application of acoustic chemometric for liquid flow in pipelines [3,7], industrial granulation processes [7-9,11] and similar process technological regimens. Since a full introduction to acoustic chemometrics has been published elsewhere [3-7], only an operational summary is provided in this chapter. 

The acoustic chemometric approach can also be used to monitor industrial production processes involving particles and powders and to provide a complementary tool for process operators for more efficient process control, or to monitor particle movement in a fluidized bed [7] for example. Below we illustrate the application potential by focusing on two applications process monitoring of a granulation process and monitoring of ammonia concentration. 

Granulation of urea [13] is a complex process that has to be controlled by experienced process operators in order to avoid critical shutdown situations. The parameters most often used for monitoring granulation processes are measured by classical univariate sensors, such as temperature, pressure and flow. However, these standard process measurements carry only little or no relevant information, or are only indirectly related to, for example particle size, clogging of the reactor, or the accumulation of a solids layer on the bottom plate. The response from these sensors often comes with quite a substantial delay time. 

Monitor the overall granulator process state, to detect critical situations and to visualize these situations as early warnings in an operator-friendly fashion (lump formation and clogging of the bottom plate are the most important mishaps in the industrial production setting). 

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