Category: Heat Exchangers

Heat Recovery Unit

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In the interest of energy conversion, process heat can be obtained from a heat recovery unit in which heat is recovered from turbine or reciprocating engine exhaust. In a heat recovery unit, an exhaust gas flows over finned tubes carrying the fluid to be heated. The hot exhaust gas (900°F to 1,200°F) heats the fluid …

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Fired Heater

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Direct-fired combustion equipment is that in which the flame and/or products of combustion are used to achieve the desired result by radiation and convection. Common examples include rotary kilns and open-hearth furnaces. Indirect-fired combustion equipment is that in which the flame and products of combustion are separated from any contact with the principal material in …

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Aerial Coolers – #2

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Process outlet temperature in an aerial cooler can be controlled by louvers, fan variable speed drives, blade pitch or recirculation of process fluid. As the process flow rate and heat duties change, and as the temperature of the air changes from season to season and night to day, some adjustment must be made to assure …

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Aerial Coolers – #1

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Aerial coolers are often used to cool a hot fluid to near ambient temperature. They are mechanically simple and flexible, and they eliminate the nuisance and cost of a cold source. In warm climates, aerial coolers may not be capable of providing as low a temperature as shell-and-tube exchangers, which use a cool medium. In …

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Plate and Frame Exchangers

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Plate-and-frame exchangers are an arrangement of gasketed, pressed metal plates aligned on carrying bars and secured between two covers by compression bolts. The pressed metal plates are corrugated in patterns to provide increased surface area, to direct the flow in specific directions, and to promote turbulence. The plates are gasketed such that each of the …

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Double Pipe Exchangers

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A double-pipe exchanger is made up of one pipe containing the tube fluid concentric with another pipe, which serves as the shell. The tube is often finned to give additional surface area. The double-pipe exchanger was developed to fit applications that are too small to economically apply the requirements of TEMA for shell and tube …

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Shell and Tube Heat Exchanger Sizing

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The required heat duty, film coefficients, conductivity, etc. for a shelland-tube heat exchanger can be calculated using the procedures in Heat Transfer Theory, Approximate U-values are given in Table 2-8. In the basic heat transfer equation it is necessary to use the log mean temperature difference. In Equation 2-4 it was assumed that the two …

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TEMA Glasses and Tube Materials

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TEMA standards provide for two classes of shell and tube exchanger qualities. Class C is the less  stringent and is typically used in onshore applications and where the temperature is above ~20°F. Class R is normally used offshore and in cold temperature service. Table 3-2 shows the most important differences between a Class R and …

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Heat Exchanger Placement of Fluid

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The question always comes up of which fluid to put in the tubes and which fluid to put in the shell. Consider placing a fluid through the tubes when: 1. Special alloy materials are required for corrosion control and high temperatures. 2. Fluid is at high pressures. 3. Fluid contains vapors and non-condensable gases. 4. …

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