SHELL AND TUBE HEAT EXCHANGER PRESENTED BY Kushal Khadakkar (Mechanical Engg.) 3Rd Year (0506ME091018)
INTRODUCTION- A shell and tube heat exchanger is a class of Heat exchanger designs. It is the most common type of heat exchanger in oil refineries and other large chemical processes, and is suited for higher-pressure applications. As its name implies, this type of heat exchanger consists of a shell (a large pressure vessel) with a bundle of tubes inside it. One fluid runs through the tubes, and another fluid flows over the tubes (through the shell) to transfer heat between the two fluids. The set of tubes is called a tube bundle, and may be composed by several types of tubes: plain, longitudinally finned, etc.
CONFIGRATION- A shell-and-tube exchanger consists of a large-diameter pipe (on the order of 12 nominal to 24 nominal and larger), inside a number of tubes is placed (ranging from about 20 to over 1000 tubes!). One fluid is directed through the tubes, and another inside the shell but outside the tubes
WORKING- If any two fluids, of different starting temperatures, flow through the heat exchanger. One flows through the tubes (the tube side) and the other flows outside the tubes but inside the shell (the shell side). Heat is transferred from one fluid to the other through the tube walls, either from tube side to shell side or vice versa. The fluids can be either liquids or gases on either the shell or the tube side Shell TubesBaffle
TYPE OF SHELL & TUBE HEAT EXCHANGER-1) U – TUBE HEAT EXCHANGER
OPERATING CONDITIONS:- Maximum pressure Shell 300 bar (4500 psia) Tube 1400 bar (20000 psia) Temperature range Maximum 600oC (1100oF) or even 650oC Minimum -100oC (-150oF) Fluids Subject to materials Available in a wide range of materials Size per unit 100 - 10000 ft2 (10 - 1000 m2) Can be extended with special designs/materials
Selection of tube material:- 1 :- The tube material should have good thermal conductivity. 2:- The tube material also should be compatible with both the shell and tube side fluids for long periods under the operating conditions 3:- The material should be corrosion less 4:- The material should be prefered should be copper alloy, stainless steel carbon steel, non-ferrous copper alloy , Inconel , nickel , Hastelloy and titanium.
1:- Inside film coefficient changes with the 0.8 power of the number of tube passes2:- Pressure drop changes with the 2.8 power of the number of tube passes Example: Npasses hi p, psi 1 100 0.2 2 174 1.4 4 303 9.7 6 419 30.2 8 528 67.6
1:- Shell fluid velocity is inversely proportional to the baffle pitch (distance between baffles)2:- ho increases with velocity to the 0.6 power3:- p increases with velocity to the 2.8 power P, inches ho p, psi 6 500 100.0 8 421 44.7 10 368 23.9 12 330 14.4 18 259 4.6
USE OF SHELL & TUBE EXCHANGER:- 1:- Cooling of Hydraulic Fluid and oil in engines 2:- Transmissions and hydraulic power packs 3:- Water heating with steam 4:- Condensate cooling 5:- Boiler feed water preheating 6:- Cooling tower trim cooling 7:- Glycol cooling 8:- Oil cooling