Heat Exchangers shell side condensation

Design Procedure for Shell-Side Condensers and Shell-Side Condensation with Gas Cooling of Condensables, Fluid-Fluid Convection Heat Exchange... 

Shell-and-tube heat exchangers are also used extensively for condensing duties. Condensers can be horizontally or vertically mounted with the condensation on the tube-side or the shell-side. Condensation normally takes place on the shell-side of horizontal exchangers and the tube-side of vertical exchangers. 

The cooled surface may be of any orientation although vertical and horizontal arrangements are most common. Condensation operations often are carried out inside shell and tube heat exchangers and the condensing vapors may be fed either to the shell side or to the tube side depending on the nature of the fluids involved, their pressure, and their corrosion and fouling characteristics (Webb and McNaught, 1980). 

M. Cumo, Numerical Methods for the Analysis of Flow and Heat Transfer in a Shell-and-Tube Heat Exchanger with Shell-Side Condensation, in Two-Phase Flow Heat Exchangers Thermal-Hydraulic Fundamentals and Design, S. Kakag, A. E. Bergles, and E. O. Fernandes (eds.), pp. 829-847, Kluwer, Dordrecht, Netherlands, 1988. 

The shape of the coohng and warming curves in coiled-tube heat exchangers is affected by the pressure drop in both the tube and shell-sides of the heat exchanger. This is particularly important for two-phase flows of multicomponent systems. For example, an increase in pressure drop on the shellside causes boiling to occur at a higher temperature, while an increase in pressure drop on the tubeside will cause condensation to occur at a lower temperature. The net result is both a decrease in the effective temperature difference between the two streams and a requirement for additional heat transfer area to compensate for these losses. 

Most boiler plants with electrical power generating facilities employ surface condensers. These are shell-and-tube heat exchangers in either one-, two-, or four-pass configurations. Surface condensers typically receive cooling water on the tube-side and steam on the shell-side of the heat exchanger. The LP turbine steam generally is received at the top of the condenser and proceeds through the condenser in a downward flow, while the FW turbine exhaust steam enters at the side. 

In a shell and lube heat exchanger with horizontal tubes 25 mm external diameter and 22 rnm internal diameter, benzene is condensed on the outside by means of water flowing through the tubes at the rate of 0.03 m Vs. If the water enters at 290 K and leaves at 300 K and the heat transfer coefficient on the water side is 850 W/in2 K, what total length of tubing will be required ... 

Horizontal shell-side and vertical tube-side are the most commonly used types of condenser. A horizontal exchanger with condensation in the tubes is rarely used as a process condenser, but is the usual arrangement for heaters and vaporisers using condensing steam as the heating medium. 

If the heat exchange involves desuperheating as well as condensation, then the exchanger can be divided into zones with linear temperature-enthalpy profiles in each zone. Figure 15.12a illustrates desuperheating and condensation on the shell-side of a horizontal condenser. The total heat transfer area is the sum of the values for each zone ... 

The condenser is to be a horizontal exchanger with the condensing stream on the shell-side and the cooling serviced by cooling water. What would be the expected rank order of the three heat exchangers in terms of their overall heat transfer coefficient ... 

Example 1.2. Consider the heat exchanger sketched in Fig. 1.4. An oil stream passes through the tube side of a tube-in-sheU heat exchanger and is heated by condensing steam on the shell side. The steam condensate leaves through a steam trap (a device... 

Gos from the wellhead with its associated condensate is first cooled in the Production Cooler. This cooler is o shell ond tube heat exchanger with the process fluid on the tube side and cooling water on the shell side. 

The liquid system from the production separator, consisting of a condensate/ water mixture, is first coded to ensure thot no gas breakout occurs during the subsequent stages and to reduce the level of dissolved water in the condensate. The Condensate Cooler is o shell and tube heat exchanger with inhibited fresh water on the shell side ond condensote on the tube side. 

When considering the steam side of steam heated reboilers, it is best to think about the reboiler as a steam condenser. The steam, at least for a conventional horizontal reboiler, is usually on the tube side of the exchanger, as shown in Fig. 8.1. The steam is on the tube side, because the shell side was selected for the process fluid. If the reboiler is a thermosyphon, or natural-circulation reboiler, then low-process-side pressure drop is important. For a horizontal reboiler, it is easiest to obtain a low pressure drop for the fluid being vaporized by placing it on the shell side. 

Optimization of the coiled-tube heat exchanger is quite complex. There are numerous variables, such as tube and shell flow velocities, tube diameter, tube pitch, and layer spacing. Other considerations include single-phase and two-phase flow, condensation on either the tube or shell side, and boiling or evaporation on either the tube or shell side. Additional complications come into play when multicomponent streams are present, as in natural gas liquefaction, since mass transfer accompanies the heat transfer in the two-phase region. 

A shell-and-tube heat exchanger has condensing steam at 00°C in the shell side with one shell pass. Two tube passes are used with air in the tubes entering at 10°C. The total surface area of the exchanger is 30 m2 and the overall heat-trartSftr coefficient may be taken as 150 W/m2 °C. If the effectiveness of the exchanger is 85 percent, what is the total heat-transfer rate ... 

A shell-and-tube heat exchanger with one shell pass and two tube passes is used to heat 5.0 kg/s of water from 30°C to 80°C. The water flows in the tubes. Condensing steam at 1 atm is used in the shell side. Calculate the area of the heat exchanger, if the overall heat-transfer coefficient is 900 W/m2 - °C. Suppose this same exchanger is used with entering water at 30°C, U = 900, but with a water flow rate of 1.3 kg/s. What would be the exit water temperature under these conditions ... 

A shell-and-tube heat exchanger with one shell pass and four tube passes is designed to heat 4000 kg/h of engine oil from 40°C to 80°C with the oil in the tube side. On the shell side is condensing steam at 1-atm pressure, and the overall heat-transfer coefficient is 1200 W/m2 °C. Calculate the mass flow of condensed steam if the flow of oil is reduced in half while the inlet temperature and U value are kept the same. 

Shell-side effluent from the reforming exchanger is cooled in a waste-heat boiler, where HP steam is generated, and then flows to the CO shift converters containing two catalyst types one (4) is a high-temperature catalyst and the other (5) is a low-temperature catalyst. Shift reactor effluent is cooled, condensed water separated (6) and then routed to the gas purification section. C02 is removed from synthesis gas using a wet-C02 scrubbing system such as hot potassium carbonate or MDEA (methyl diethanolamine) (7). 

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