Heat Exchangers
Heat Recovery Unit
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 [...]
15Sep2009 | admin | Comments Off | ContinuedFired Heater
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 [...]
15Sep2009 | admin | Comments Off | ContinuedAerial Coolers – #2
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 [...]
15Sep2009 | admin | Comments Off | ContinuedAerial Coolers – #1
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 [...]
15Sep2009 | admin | Comments Off | ContinuedPlate and Frame Exchangers
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 [...]
15Sep2009 | admin | Comments Off | ContinuedDouble Pipe Exchangers
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 [...]
15Sep2009 | admin | Comments Off | ContinuedShell and Tube Heat Exchanger Sizing
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 fluids [...]
15Sep2009 | admin | Comments Off | Continued