Energy volumetric feed rate

Ideal Continuous Stirred Tank Reactor In an ideal CSTR, reactants are fed into and removed from an ideally mixed tank. As a result, the concentration within the tank is uniform and identical to the concentration of the effluent. The mass and energy conservation equations for an ideal constant-volume or constant-density CSTR with constant volumetric feed rate V may be written as... 

The space velocity, often used in the technical literature, is the total volumetric feed rate under normal conditions, F o(Nm /hr) per unit catalyst volume (m X that is, PbF o/W. It is related to the inverse of the space time W/F g used in this text (with W in kg cat. and F q in kmol A/hr). It is seen that, for the nominal space velocity of 13,800 (m /m cat. hr) and inlet temperatures between 224 and 274 C, two top temperatures correspond to one inlet temperature. Below 224 C no autothermal operation is possible. This is the blowout temperature. By the same reasoning used in relation with Fig. 11.5.e-2 it can be seen that points on the left branch of the curve correspond to the unstable, those on the right branch to the upper stable steady state. The optimum top temperature (425°C), leading to a maximum conversion for the given amount of catalyst, is marked with a cross. The difference between the optimum operating top temperature and the blowout temperature is only 5°C, so that severe control of perturbations is required. Baddour et al. also studied the dynamic behavior, starting from the transient continuity and energy equations [26]. The dynamic behavior was shown to be linear for perturbations in the inlet temperature smaller than 5°C, around the conditions of maximum production. Use of approximate transfer functions was very successful in the description of the dynamic behavior. 

Assume the reaction takes place in an isothermal PFR operating at con- stant pressure (1 atm) and constant temperature of 1100 K. The feed to the reactor consists of a mixture, of ethane and NO with a molar ratio of 95% ethane and 5% NO, The inlet, volumetric flow rate is 600 cm /s. Predict the reactor volume required for 98% of the ethane to react, and determine the activation energy for ketf-... 

An exothermic reaction that obeys a second-order rate expression (r = kC ) is to be accomplished in a cascade of three identical stirred tanks operating in series. To (approximately) balance the heat loads on the various reactors, each of the reactors will be operated at a different temperature. These temperatures are to be selected in a manner such that the rates of reaction are to be the same in each reactor. To minimize losses of the organic solvent during operation, it will be necessary to operate the third reactor at 140°C. At this temperature the reaction rate constant is equal to 500 L/(mol h). If the effluent from the third reactor corresponds to 99% conversion and if the volumetric flow rate to the cascade is equal to 1.8 m /h when the concentration of A in the feed stream is 1.5 M, how large must each of the reactors be If the activation energy for the reaction is 20 kcal/g-mol, at what temperatures should the first and second reactors be operated ... 

Choose a feed rate that gives a constant volumetric rate of production of biomass. Situations when this strategy might be chosen include both those in which the requirement for dissipation of the thermal energy produced by the reaction might place a constraint on the rate at which products are formed and those in which the resulting level of substrate may be insufficient to meet requirements for cell maintenance. 

The energy performance of a dryer and a drying process is characterized by various indices such as volumetric evaporation rate, surface heat losses, steam consumption, unit heat consumption, and energy (thermal) efficiency. Of all these indices, the energy efficiency / is most frequently quoted in technical specifications. It commonly relates the energy used for moisture evaporation at the solids feed temperature ( , ) to the total energy supplied to the dryer ( ,) ... 

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