Drying product temperature

The functional relationship between product temperature, on the one hand, and shelf temperature and chamber pressure, on the other hand, is affected by many factors including the size and design of the lyophilizer, the characteristics of the product, and the time evolved since the start of primary drying. With a sucrose formulation in vials, we have observed a maximum primary drying product temperature rise of -i-5°C when the shelf temperature was varied from -15 to -i-30°C, whereas a pressure variation from 30 to 250 microbars generated an increase of around -i-2.5°C. With a lactose formulation in ampoules lyophilized in a larger freeze-dryer equipped with a plate-type condenser, the effect of pressure was found to be predominant -i-6.5°C for a pressure move from 50 to 300 microbars, versus -t-l°C for a shelf temperature move from 0° to 25°C. 

Minimum pressure at the end of secondary drying Maximum temperature of the condenser Temperature range of the product at the end of freezing Maximum primary drying product temperature Product primary drying time... 

Dissolve 10 g. of chloro- 2,4-dinitrobenzenet in 50 ml. of dioxan in a 250 ml. conical flask. Dilute 8 ml. of hydrazine hydrate with an equal volume of water and add this slowly with shaking to the dioxan solution, keeping the temperature between zo " and 25°. Heat under reflux for 10 minutes to complete the reaction and then add 5 ml. of ethanol and heat again for 5 minutes. Cool and filter oflF the orange 2,4-dinitrophenylhydra-zine. Recrystallise the dry product from ethyl acetate m.p. 200° (decomp.). Yield, 7 g. 

In a 500 ml. bolt-head flask provided with a thermometer (reaching almost to the bottom) and a calcium chloride (or cotton wool) guard tube, place 100 g. of a-bromo-wo-valerj l bromide and 50 g. of dry, finely-divided urea. Start the reaction by warming the flask on a water bath the temperature soon rises to about 80°. Maintain this temperature for about 3 horns the mass will liquefy and then resolidify. Transfer the sticky reaction product to a large beaker containing saturated sodium bicarbonate solution, stir mechanically and add more saturated sodium bicarbonate solution in small quantities until effervescence ceases. Filter at the pump, suck as dry as possible and dry the crude bromural upon filter paper in the air. RecrystaUise the dry product from toluene. Alternatively, recrystaUise the moist product from hot water (ca. 700 ml.). The yield of pure brommal, m.p. 154-155°, is 28 g. 

Process Requirements. Typical inside dry-bulb temperatures and relative humidities used for preparing, processing, and manufacturing various products, and for storing both raw and finished goods, are Hsted in Table 1. In some instances, the conditions have been compromised for the sake of worker comfort and do not represent the optimum for the product. In others, the conditions Hsted have no effect on the product or process other than to increase worker efficiency. 

MPD-1 fibers may be obtained by the polymeriza tion of isophthaloyl chloride and y -phenylenediamine in dimethyl acetamide with 5% lithium chloride. The reactants must be very carefully dried since the presence of water would upset the stoichiometry and lead to low molecular weight products. Temperatures in the range of 0 to —40° C are desirable to avoid such side reactions as transamidation by the amide solvent and acylation of y -phenylenediamine by the amide solvent. Both reactions would lead to an imbalance in the stoichiometry and result in forming low molecular weight polymer. Fibers are dry spun direcdy from solution. 

Dmm-dried products ate more affected by heat than spray-dried products. Drying ia a vacuum chamber decreases the temperature and thus the heat effect on the product, although the atmospheric dryers are used more widely. 

Dmm-dried products, mostly nonfat, make up only 5—10% of dried milk products. Because of the high temperature and longer contact time, considerable proteia denaturation occurs. Dmm-dried products ate identified as high heat dry milk and as such have a lower solubHity iadex, lower proteia nitrogen content, and a darker color. 

Iron Browns. Iron browns are often prepared by blending red, yellow, and black synthetic iron oxides to the desired shade. The most effective mixing can be achieved by blending iron oxide pastes, rather than dry powders. After mixing, the paste has to be dried at temperatures around 100°C, as higher temperatures might result in the decomposition of the temperature-sensitive iron yellows and blacks. Iron browns can also be prepared directiy by heating hydrated ferric oxides in the presence of phosphoric acid, or alkaU phosphates, under atmospheric or increased pressure. The products of precipitation processes, ie, the yellows, blacks, and browns, can also be calcined to reds and browns. 

Boric acid crystals are usually separated from aqueous slurries by centrifugation and dried in rotary driers heated indirecdy by warm air. To avoid overdrying, the product temperature should not exceed 50°C. Powdered and impalpable bode acid are produced by milling the crystalline matedal. 

Spray Drying and Agglomeration. Most instant coffee products are spray-dried. Stainless steel towers with a concurrent flow of hot ak and atomized extract droplets are utilized for this purpose. Atomization, through pressure nozzles, is controUed based on selection of the nozzles, properties of the extract, pressures used, bulk density, and capacity requkements. Low inlet ak temperatures (200—280°C) are preferred for best flavor quaHty. The spray towers must be provided with adequate dust coUection systems such as cyclones or bag filters. The dried particles are coUected from the conical bottom of the spray drier through a rotary valve and conveyed to bulk storage bins or packaging lines. Processors may screen the dry product to... 

Monomer conversion (79) is followed by measuring the specific gravity of the emulsion. The polymerization is stopped at 91% conversion (sp gr 1.069) by adding a xylene solution of tetraethylthiuram disulfide. The emulsion is cooled to 20°C and aged at this temperature for about 8 hours to peptize the polymer. During this process, the disulfide reacts with and cleaves polysulfide chain segments. Thiuram disulfide also serves to retard formation of gel polymer in the finished dry product. After aging, the alkaline latex is acidified to pH 5.5—5.8 with 10% acetic acid. This effectively stops the peptization reaction and neutralizes the rosin soap (80). 

Screw conveyor and mdii ect rotaiy. Indirect type, continuous operation Applicable with dry-product recirculation Appbcable with dry-product recirculation Generally requires recirculation of dry product. Little dusting occurs Chief advantage is low dust loss. Web suited to most materials and capacities, particularly those requiring drying at steam temperature Low dust loss. Material must not stick or be temperature-sensitive Not applicable Not appbcable Not appbcable... 

In a typical process a jacketed still fitted with a stirrer and reflux condenser in charged with 240 parts 37% w/w (40% w/v) formalin and the pH adjusted to 8.0-8.5 using sodium carbonate solution with the aid of a pH meter. One hundred and twenty six parts of melamine (to give a melamine formaldehyde ratio of 1 3) are charged into the still and the temperature raised to 85°C. The melamine goes into solution and forms methylol derivatives. For treatment of fabrics, paper and leather this product may be diluted and cooled for immediate use. It may also be spray dried to give a more stable product. Cooling the solution would yield crystalline trimethylolmelamine, which may be air dried but which is less soluble in water than the spray-dried product. 

Wet ESPs add to the complexity of a wash system, because of the fact that the resulting slurry must be handled more carefully than a dry product, and in many cases requires treatment, especially if the dust can be sold or recycled. Wet ESPs are limited to operating at stream temperatures under approximately 80 to 90°C (170 to 190°F), and generally must be constructed of noncorrosive materials (EPA, 1998 Flynn, 1999). 

Water, 15% hydrochloric acid, 10% sodium bicarbonate and finally water. The solvent was stripped off. The residual oil was mixed with 300 ml of 28% aqueous ammonia for 1 hour. The ammonia and water were vacuum distilled at a temperature of 40°C or less. Then 300 cc of carbon tetrachloride was added and the solution dried with sodium sulfate. The solution was cooled at 0°C and then filtered. The crystals were washed with cold carbon tetrachloride and vacuum dried. The yield was 57 g of dried product having a melting point of 55°C to 56.5°C. 

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