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Condensing steams stirred tank heating

Exercise Stirred Tank Heated with Condensing Steam... [Pg.212]

Consider the stirred-tank heating system of Section 2.4.1 with constant holdup and a steam heating coil. We assume that the thermal capacitance of the hquid condensate is negligible compared to the thermal capacitances of the tank liquid and the wall of the heating coil. This assumption is reasonable when a steam trap is used to remove the condensate from the coil as it is produced. As a result of this assumption, the dynamic model consists of energy balances on the liquid and the heating coil wall ... [Pg.24]

When we developed the model for the stirred tank heater, we ignored the dynamics of the heating coil. Provide a slightly more realistic model which takes into consideration the flow rate of condensing steam. [Pg.103]

How we model the stirred tank heater is subject to the actual situation. At a slightly more realistic level, we may assume that heat is provided by condensing steam and that the coil metal is at the same temperature as the condensing steam. The heat balance and the Laplace transform of the tank remains identical to Chapter 2 ... [Pg.103]

In many cases, the heat flow (Q) to the reactor is given in terms of the overall heat transfer coefficient U, the heat exchange area A, and the difference between the ambient temperature, Ta, and the reaction temperature, T. For a continuous flow stirred tank reactor (CFSTR) in which both fluid temperatures (i.e., inside and outside the exchanger) are constant (e.g., condensing steam), Q is expressed as... [Pg.434]

An endothermic reaction A — R is performed in three-stage, continuous flow stirred tank reactors (CFSTRs). An overall conversion of 95% of A is required, and the desired production rate is 0.95 x 10 3 kmol/sec of R. All three reactors, which must be of equal volume, are operated at 50°C. The reaction is first order, and the value of the rate constant at 50°C is 4 x 10-3 sec-1. The concentration of A in the feed is 1 kmol/m3 and the feed is available at 75°C. The contents of all three reactors are heated by steam condensing at 100°C inside the coils. The overall heat transfer coefficient for the heat-exchange system is 1,500 J/m2 sec °C, and the heat of reaction is +1.5 x 108 J/kmol of A reacted. [Pg.440]

Starch is dispersed in the paper mill in large stainless steel tanks by injection of steam or by heat transfer from a steam-heated jacket. The tanks are stirred and equipped with baffles to prevent formation of a single vortex at the agitator shaft. A minimum heating time of 20 minutes at 95°C is normally required. Steam injection dilutes the starch paste by condensate, which must be considered for concentration control. Pastes that are prone to retrogradation are held at a temperature above 91°C or quickly cooled to 66°C to prevent amylose formation. Attention to storage temperature and water balance is an essential requirement for the effective use of starch in a paper mill. [Pg.674]

A stirred tank shall be heated with condensing steam at pressure. It is filled with mass Ml of a liquid, which is at starting temperature Tlo- The heat transfer area is A. The tank wall thickness is. The tank wall has a heat conductivity of its heat capacity is insignificant (Fig. 4.3-10). [Pg.212]

A dilute solution at 20° C is added to a well-stirred tank at the rate of 180 kg/hr. A heating coil having an area of 0.9 is located in the tank and contains steam condensing at 150° C. The heated liquid leaves at 120 kg/hr and at the temperatiure of the solution in the tank. There is 500 kg of solution at 40° C in the tank at the start of the operation. The overall heat-transfer coefficient is 342 kg/hr °C and the heat capacity of water is 1 k cal/kg °C. Calculate the outlet temperature after 1 hr. (See Figure 1.7.)... [Pg.24]

Steam (or some other heating medium) can be condensed within a coil or jacket to heat liquid in a stirred tank, and the inlet steam pressure can be varied by adjusting a control valve. The condensation pressure Pg then fixes the steam temperature Tg through an appropriate thermodynamic relation or from tabular information such as the steam tables (Sandler, 2006) ... [Pg.24]

A steam coil is immersed in a stirred heating tank. Saturated steam at 7.50 bar condenses within the coil, and the condensate emerges at its saturation temperature. A solvent with a heat capacity of 2.30 kJ/(kg-°C) is fed to the lank at a steady rate of 12.0 kg/min and a temperature of 25 C. and the heated solvent is discharged at the same How rate. The tank is initially filled with 760 kg of solvent at 25°C, at which point the flows of both steam and solvent are commenced. The rate at which heat is transferred from the steam coil to the solvent is given by the expression... [Pg.571]

Five thousand pounds of oil initially at bO F is being heated in a stirred (perfectly mixed) tank by saturated steam which is condensing in the steam coils at 40 psia. If the rate of heat transfer is given by Newton s heating law,... [Pg.642]


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