Jacketed vessel

Jacketed evaporators are used when the product is very viscous, the batches are small, good mixing is required, ease of cleaning is important, or glass-lined equipment is required. 

Jacket ciOAire -can be one of many designs as shown on Para. UA-104 (ASME Code) 

ContirHiOus spiral baffle—welded to inner vess 

Jacketed Vessel fabricated fram patterned plates 

HALF PIPE coil jacket with fabrication details- 

When liquids are to be evaporated on a small scale, the operation is often accomplished in some form of jacketed tank or kettle. This may be a batch or continuous operation The rate ofheat transfer is generally lower than for other types of evaporators and only a limited heat transfer area is available. The kettles may or may not be agitated. 

The spacing between the jacket and vessel wall will depend on the size of the vessel, but will typically range from 50 mm for small vessels to 300 mm for large vessels. 

The pitch of the coils and the area covered can be selected to provide the heat transfer area required. Standard pipe sizes are used ranging from 60 to 120 mm outside diameter. The half-pipe construction makes a strong jacket capable of withstanding pressure better than the conventional jacket design. 

Factors to consider when selecting the type of jacket to use are listed below  

Cost in terms of cost the designs can be ranked, from cheapest to most expensive, as  

Heat transfer rate required select a spirally baffled or half-pipe jacket if high rates are required. 

Chilton s vessel was only 0.3 m in diameter and fitted with a single paddle of 150 mm length, and that Cummings and West used a 0.45 m vessel with two turbine impellers, agreement between their results is remarkably good. The group is again used 

Brown el have given data on the performance of 1.5 m diameter sulphonators and nitrators of 3.4 m capacity as used in the dyestuffs industry. The sulphonators were of cast iron and had a wall thickness of 25.4 mm the annular space in the jacket being also 25.4 mm. The agitator of the sulphonator was of the anchor type with a 127 mm clearance at the walls and was driven at 0.67 Hz. The nitrators were fitted with four-biaded propellers of 0.61 m diameter driven at 2 Hz. For cooling, the film coefficient hh for the inside of the vessel was given by  

The film coefficients for the water jacket were in the range 635-1170 W/m K for water rates of 1.44 9.23 1/s, respectively. It may be noted that 7.58 1/s corresponds to a vertical velocity of only 0.061 m/s and to a Reynolds number in the annulus of 5350. The thermal resistance of the wall of the pan was important, since with the sulphonator it accounted for 13 per cent of the total resistance at 323 K and 31 per cent at 403 K. The change in viscosity with temperature is important when considering these processes, since, for example, the viscosity of the sulphonation liquors ranged from 340 mN s/m at 323 K to 22 mN s/m at 403 K. 

In discussing equations 9.207 and 9.208 Fletcher has summarised eoirelations obtained for a wide range of impeller and agitator designs in terms of the constant before the Reynolds number and the index on the Reynolds number as shown in Table 9.11. 

Retreating-blade turbine with three blades, jacketed and baffled vessel, Re = 2x lO to 2 X 10  

In many applications, it is not practicable to install cooling coils inside a tank, and heating of the contents of the vessel is achieved using condensing steam 

For a steam jacketed tank (360 mm in diameter) fitted with baffles, Hage-dorn and Salamone [1967] measmed the rates of heat transfer to water, glycerol and aqueous carbopol solutions over wide ranges of conditions (0.36 n 1 35 Re 6.8 x 10 Pr 2.4 x 10 ). They measured temperatures at various locations in the vessel and suggested the following general form of heat transfer correlation  

In conclusion, it should be emphasised that most of the cmrently available information on heat transfer to non-Newtonian fluids in stirred vessels relates to specific geometrical arrangements. Few experimental data are available for the independent verification of the individual correlations presented here which, therefore, must be regarded somewhat tentative. Reference should also be made to the extensive compilations [Edwards and Wilkinson, 1972 Poggermann et al., 1980 Dream, 1999] of other correlations available in the literature. Although the methods used for the estimation of the apparent viscosity vary from one correlation to another, especially in terms of the value of ks, this appears to exert only a moderate influence on the value of h, at least for shear-thinning fluids. For instance, for n = 0.3 (typical of suspensions and polymer solutions), a two-fold variation in the value of ks will give rise to a 40% reduction in viscosity, and the effects on the heat transfer coefficient will be further diminished because Nu x Thus, an error of 100% 

A polymer solution is to be heated from IS C to 27°C before use as a thinner in a wall paint. The heating is to be carried out in a stainless steel vessel (1 m diameter) fitted with an anchor agitator of diameter equal to 0.9 m which is rotated at 100 RPM. The tank which is filled up to 0.8 m depth is fitted with a helical coil (helix diameter 0.8 m) made of 25 mm od and 22 mm id copper tube (total external heat transfer area of 2 m ). Hot water at a mean temperature of 45°C (assumed to be approximately constant) is fed to the coil at a rate of 30 kg/min. 

The thermal conductivity, heat capacity and density of the polymer solution can be taken as the same as for water. The values of the power-law constants are n = 0.36 and m = 26 — 0.0566 T Pa -s ) in the range 288 T 323 K. Estimate the overall heat transfer coefficient and the time needed to heat one batch of hquid. 

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Commonly used heat-transfer surfaces are internal coils and external jackets. Coils are particularly suitable for low viscosity Hquids in combination with turbine impellers, but are unsuitable with process Hquids that foul. Jackets are more effective when using close-clearance impellers for high viscosity fluids. For jacketed vessels, wall baffles should be used with turbines if the fluid viscosity is less than 5 Pa-s (50 P). For vessels equipped with cods, wall baffles should be used if the clear space between turns is at least twice the outside diameter of the cod tubing and the fluid viscosity is less than 1 Pa-s (10... 

Manufacture. Phosphoms pentachloride is manufactured by either batch or continuous processing. In the former, the phosphoms trichloride usually dissolves in carbon tetrachloride before being treated with chlorine. A mixture of ca one part of phosphoms trichloride to one part of carbon tetrachloride is introduced to a water-jacketed vessel that contains an efficient stirrer and a tight cover with a redux condenser. The chlorine is passed into the vessel below the Hquid level, and crystals of phosphoms pentachloride form in the Hquid. When the reaction is completed, the suspension of crystals of phosphoms pentachloride in the carbon tetrachloride is drawn out of the vessel and the crystals are filtered and then dried by circulating hot water through the jacket of the filter. The clarified carbon tetrachloride is returned to the reaction vessel. 

Coil-in-Tank or Jacketed Vessel Isothermal Heating Medium... 

Use inherently safer equipment (e.g., jacketed vessels instead of tube heat exchangers)... 

The work of Uhl [22] gave particular emphasis to viscous materials in Jacketed vessels, and the correlating equations are ... 

See Figures I0-93A and I0-93B as limited examples of reaction and other process vessels that require heat transfer for proper processing. Markovitz reports improved heat transfer for the inside of jacketed vessels when the surface has been electropolished, which gives a fine, bright surface. 

Fig. E.6.1. Diagram of jacketed vessel with impeller location.

Equipment, The reactor was 1.523 liter, 316 stainless steel cylindrical, jacketed vessel equipped with two multiblade, paddle-type agitators. Tracer studies showed the reactor was well-mixed. A thermocouple measured temperature and was recorded continuously. Feed tanks, tubing, pumps and valves were made of stainless steel and had teflon seals. 

Associated with the special jacketed vessels mentioned above some attempt is being made to simulate production plant geometries for better correlated dispersion and nucleation. 

Softened water is often used for washing containers before filling with liquid or semi-solid preparations and for cooling systems. Unless precautions are taken, the microbial count in a cooling system or jacketed vessel will rise rapidly and if faults develop in the cooling plates or vessel wall, contamination of the product may occur. 

A solution of NaOH in water is prepared by diluting a concentrated solution in an agitated, jacketed, vessel. The strength of the concentrated solution is 50 per cent w/w and 2500 kg of 5 per cent w/w solution is required per batch. Calculate the heat removed by the cooling water if the solution is to be discharged at a temperature of 25°C. The temperature of the solutions fed to the vessel can be taken to be 25°C. 

Reactors, columns and other vessels are usually designed as special items for a given project. In particular, reactor designs are usually unique, except where more or less standard equipment is used such as an agitated, jacketed, vessel. 

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