Mixing liquid, batch

Solution calorimetry covers the measurement of the energy changes that occur when a compound or a mixture (solid, liquid or gas) is mixed, dissolved or adsorbed in a solvent or a solution. In addition it includes the measurement of the heat capacity of the resultant solution. Solution calorimeters are usually subdivided by the method in which the components are mixed, namely, batch, titration and flow. 

Three basic fluid contacting patterns describe the majority of gas-liquid mixing operations. These are (1) mixed gas/mixed liquid - a stirred tank with continuous in and out gas and liquid flow (2) mixed gas/batch mixed liquid - a stirred tank with continuous in and out gas flow only (3) concurrent plug flow of gas and liquid - an inline mixer with continuous in and out flow. For these cases the material balance/rate expressions and resulting performance equations can be formalized as ... 

C. Draw-off of the mixed liquids influences tlie location of the impeller. For blending, the preferred impeller location in a Z/T =1.0 Vessel is at the midpoint of liquid depth for a continuous flow process, but may not be for a batch system. 

Fig. 1. Power characteristics of a mixing impeller, single-liquid batch system in an open vessel (R6).

Distillation can be a batch or a continuous operation. Batch distillation is frequently used in the laboratory for determining the chemical composition of mixed liquids, such as hydrocarbons. In the majority of industrial processes, distillation is continuous. In a hatch operation, the charge material is boiled and vapors are removed continuously, condensed, and... 

In a steady state continuous distillation with the assumption of a well mixed liquid and vapour on the plates, the holdup has no effect on the analysis (modelling of such columns does not usually include column holdup) since any quantity of liquid holdup in the system has no effect on the mass flows in the system (Rose, 1985). Batch distillation however is inherently an unsteady state process and the liquid holdup in the system become sinks (accumulators) of material which affect the rate of change of flows and hence the whole dynamic response of the system. 

Well-mixed gas, well-mixed liquid SFBR. In this case the concentrations are spatially invariant, but do depend on time because of the batch liquid phase. For the gas... 

Calcium formate may also be supplied in powder form and in such cases should be added to the dry batch before mixing. Liquid admixtures are generally considered easier to dispense accurately and are more readily dispersable evenly through the mix. 

Thus, the flow patterns established in a mixing tank depend critically on the vessel - impeller configuration, the rheology of the liquid batch and the operating conditions. In selecting the appropriate combination of equipment, care must be taken to ensure that the resulting flow pattern is suitable for the required application. 

Liquid Mixer Ribbon Blenders Littleford Mixers Planetary Mixers High Speed Agitation Mixers Can be controlled to yield very fine grinds/mixes, controlled aeration, controlled heat buildup choice depends on mix viscosity, batch size, compounding ingredients (easy vs. hard to disperse). 

Case 5 Mixed gas, batch liquid, and unsteady state In this semibatch operation, a batch of liquid is taken in a reactor and a stream of gas is passed through it (Figure 11.4d). The problem here is usually one of calculating the time needed for a given conversion in a reactor of known volume. 

Case 5 Mixed gas, batch liquid, and unsteady state 364... 

Figure 6.17.5 Experimental results of epimerization in a fixed bed reactor [presaturated one-liquid flow (POLF) reactor] and in a well-mixed semi-batch stirred tank reactor (STR) [feed 50mol.% ( )-neomenthol, 26% ( )-menthol, and 23% ( )-isomenthol, 1% menthone, 180°C, PH2 = 2MPa, deal = 250-500 pm]. Data from Etzold (2007) and Etzold and Jess (2009).

The screw mixer uses a single- or dual-screw arrangement to mix liquids, solids, or a combination of both. It comes in two basic configurations batch and combination mixer-extruder. 

Solid (or dry) chemicals are sometimes used to prepare solutions for feeding. Many operators prefer to feed chemicals with metering pumps rather than dry feed equipment. Also, mixing liquid chemicals into the process water stream usually is more efficient. A weighted amount (using a continuous dry chemical feeder or a batch preparation approach) of the dry chemical is mixed with water to prepare the desired solution strength. Then the liquid is metered into the process water in the usual way. 

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