Condensing steams temperature profile

Figure 26.7 Temperature profile during condensation of steam...

Description A single jacketed fixed-bed reactor removes the heat of the reaction by producing high-pressure steam. The process is carried out with a large ethylene excess. The flexibility of catalyst staging, reactor temperature profiles, and feed flowrates with EVC s single reactor system, produces maximum throughput with minimal byproducts. After condensation and separation of the reaction products (EDC and water), excess ethylene is compressed and recirculated. 

On the other hand, while chlorides accumulate near the top of the catalyst, they are more mobile and can be detected in significant concentrations, up to 0.05%, at all levels in a deactivated bed. Although reasonable hves of at least two years can often be achieved in the presence of chloride there is more rapid movement of the peak in temperature profile, and the concentration of carbon monoxide in the outlet gas increases more rapidly. Surface chlorides, which are formed by reaction with zinc oxide, are mobile and sinter the catalyst surface. Chlorides are also soluble in condensed steam and can be washed down onto lower, more active catalyst layers. 

As Fig. 4.6 shows, saturated steam at a temperature s is condensing on a vertical wall whose temperature 0 is constant and lower than the saturation temperature. A continuous condensate film develops which flows downwards under the influence of gravity, and has a thickness 5 x) that constantly increases. The velocity profile w(y), with w for wx, is obtained from a force balance. Under the assumption of steady flow, the force exerted by the shear stress are in equilibrium with the force of gravity, corresponding to the sketch on the right hand side of Fig. 4.6... 

A power-law non-Newtonian solution of a polymer is to be heated from 288 K to 303 K in a concentric-tube heat exchanger. The solution will flow at a mass flow rate of 210 kg/h through the inner copper tube of 31.75 mm inside diameter. Saturated steam at a pressure of 0.46 bar and a temperature of 353 K is to be condensed in the armulus. If the heater is preceded by a sufficiently long unheated section for the velocity profile to be fully established prior to entering the heater, determine the required length of the heat exchanger. Physical properties of the solution at the mean temperature of 295.5 K are ... 

A coal-in-oil slurry which behaves as a power-law fluid is to be heated in a double-pipe heat exchanger with steam condensing on the annulus side. The inlet and outlet bulk temperatures of the slurry are 291 K and 308 K respectively. The heating section (inner copper tube of 40 mm inside diameter) is 3 m long and is preceded by a section sufficiently long for the velocity profile to be fully estabhshed. The flow rate of the slurry is 400kg/h and its thermo-physical properties are as follows density = 900 kg/m heat capacity = 2800 J/kg K thermal conductivity = 0.75 W/mK. In the temperature interval 293 < T < 368 K, the flow behaviour index is nearly constant and is equal to 0.52. 

Figures 5.30 and 5.31 give temperature and composition profiles in the two columns. Notice that the temperature in the condenser of the high-pressure column is 407 K and the condenser heat duty is 5.86MW (see Fig. 5.28). The temperature in the base of the low-pressure column is 345 K and the reboiler duty is 14.77 MW. This 62 K temperature differential indicates that these two columns could be heat-integrated the condenser of the high-pressure column serving as a reboUer in the low-pressure column. Since the heat duties are not equal, an additional steam-heated reboiler would be needed in the low-pressure column. An example of heat integration is presented in Section 5.4.

A polymer solution (n of 0.5 K at 90 F of 51 Ibm fT viscosity activation energy of 14,900 Btu/lb mole) is fed into a 1-in. i.d. stainless steel tube (10 ft long) at a mass flow rate of 750 Ibm/h and a temperature of 90 F. The velocity profile is fully developed before the solution enters the heated tube. Heat is supplied by steam condensing at 20 psia. 

Figs. 2 and 3 demonstrate the profiles of steam and oil saturations. Near the injection wells, the saturation of steam increases due to evaporation of the water initially filled the reservoir. In the transition zone with variable temperature in the condensation of steam injected, so in the area of water saturation increases dramatically. 

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