Heat exchange equipment temperature range

For the safety reason, new pilot plants are often equipped with inert cooling/heating fluids in reactor jackets and condensers. Aromatic compounds and mixtures thereof and silicones are widely used as heat exchange fluids. The range of operating temperatures desired generally dictates the choice of heat exchange fluid. Aromatic heat... 

Internal heat exchange is realized by heat conduction from the microstructured reaction zone to a mini channel heat exchanger, positioned in the rear of the reaction zone [1,3,4], The falling film micro reactor can be equipped, additionally, with an inspection window. This allows a visually check of the quality of film formation and identification of flow misdistribution. Furthermore, photochemical gas/liquid contacting can be carried out, given transparency of the window material for the band range of interest [6], In some cases an inspection window made of silicon was used to allow observation of temperature changes caused by chemical reactions or physical interactions by an IR camera [4, 5]. 

As discussed in Section 2.3.1.2, SEDEX [103, 104] and SIKAREX [106] instruments are also used isothermally. In the case of the SIKAREX, the temperature of the sample is held by a heating coil at constant temperature by establishing a constant rate of heat exchange to the jacket (held about 50 to 100°C below the sample temperature). By measuring the electrical input, a negative copy of the reaction heat profile is obtained. Typical sensitivity of the equipment is 0.5 W/kg operating with a sample size of 10 to 30 g and in a temperature range of 0 to 300°C. 

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. 

The problem of gas side deposition is present in a wide range of industries where particulate matter is carried either intentionally or unintentionally in a gas stream. Difficulties due to fouling can be manifest in dryers, gas lines, reactors and combustion equipment as well as heat exchangers involved in gas processing. The examples cited above indicate that the temperature range over which deposition can be encountered is extremely wide, covering temperatures from ambient to well in excess of 1000°C. 

Fig. 17.15 shows how the friction factor increased with time in a "sample" finned tube heat exchanger exposed to an air flowing through laden with calcium carbonate particles the apparatus shown in Fig. 17.14. It may be regarded as a typical curve obtained in the laboratory apparatus. During the experiments water at temperature in the range 10 - 90°C was passed through the tubes. The equipment allowed thermal performance and pressure drop to be measured. From Fig. 17.15 it can be seen that the friction factor rises asymptotically to a level 50%...

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