Stirred tank cooling water

A cascade of three continuous stirred-tank reactors arranged in series, is used to carry out an exothermic, first-order chemical reaction. The reactors are jacketed for cooling water, and the flow of water through the cooling jackets is countercurrent to that of the reaction. A variety of control schemes can be employed and are of great importance, since the reactor scheme shows a multiplicity of possible stable operating points. This example is taken from the paper of Mukesh and Rao (1977). 

A water-cooled, continuous stirred-tank reactor is used to carry out the following exothermic parallel reactions... 

The tank is initially filled to its 40 percent level with pure reactant B at a concentration Cgo Maximum cooling-water flow is begun, and reactant A is slowly added to the perfectly stirred vessel. 

The rates of heat transfer between the fermentation broth and the heat-transfer fluid (such as steam or cooling water flowing through the external jacket or the coil) can be estimated from the data provided in Chapter 5. For example, the film coefficient of heat transfer to or from the broth contained in a jacketed or coiled stirred-tank fermentor can be estimated using Equation 5.13. In the case of non-Newtonian liquids, the apparent viscosity, as defined by Equation 2.6, should be used. 

A fermentation broth contained in a batch-operated stirred-tank fermentor, 2.4m in inside diameter D, is equipped with a paddle-type stirrer of diameter (L) of 0.8 m that rotates at a speed Af = 4s -. The broth temperature is maintained at 30 °C with cooling water at 15°C, which flows through a stainless steel helical coil that has a 50 mm outside diameter and is 5 mm thick. The maximum rate of heat evolution by biochemical reactions, plus dissipation of mechanical energy input by the stirrer, is 51000 kcal h , although the rate varies with time. The physical properties of the broth at 30 °C were density p = 1000 kg m " , viscosity p = 0.013 Pa s, specific heat Cp = 0.90 kcal kg °C , and thermal conductivity K = 0.49 kcal h m °C = 0.000136 kcals m °C . ... 

Equipment systems are available that will, periodically during the day or week, activate two pumps to add a prescribed volume of each of these two chemicals into a mixing tank. The tank contents are stirred, HOBr is produced, and the tank contents are then pumped to the cooling water system. Such systems can also incorporate bromine monitors and chart recorders, plus other dosing and control items. 

The reactor to be used is a 4m3 stainless steel stirred tank following DIN-Standards [20]. It is equipped with a indirect heating cooling system using a monofluid (water-diethylene glycole mixture) circulating in a heat exchanger... 

A 2.5 m3 stainless steel stirred tank reactor is to be used for a reaction with a batch volume of 2 m3 performed at 65 °C. The heat transfer coefficient of the reaction mass is determined in a reaction calorimeter by the Wilson plot as y = 1600Wnr2KA The reactor is equipped with an anchor stirrer operated at 45 rpm. Water, used as a coolant, enters the jacket at 13 °C. With a contents volume of 2 m3, the heat exchange area is 4.6 m2. The internal diameter of the reactor is 1.6 m. The stirrer diameter is 1.53 m. A cooling experiment was carried out in the temperature range around 70 °C, with the vessel containing 2000 kg water. The results are represented in Figure 9.16. 

S3] A process for the oligomerization of ethylene for the production of linear a-olefins had to be developed in stirred tank reactor assuming isothermal conditions and was executed in the kinetic regime. The latter was assured by increasing the rotational speed of the impeller until the rate of reaction did not increase further. The autoclave reactor was heated by an external blanket and supplied with cooling water circulation through an internal coil. 

Continuous stirred tank reactors. The simplest method of cooling a CSTR is shown in Fig. 4.14. Here we measure the reactor temperature and manipulate the flow of cooling water to the jacket. Using a jacket for cooling has two advantages. First, it minimizes the risk of leaks and thereby cross contamination between the cooling system and the pro-... 

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