Page 1 Pocket Guide to Chemical Engineering by Carl R. Branan â€¢ ISBN: 0884153118 â€¢ Pub. Date: November 1999 â€¢ Publisher: Elsevier Science & Technology Books Page 2 Pocket Guide to Chemical Engineering by Carl R. Branan â€¢ ISBN: 0884153118 â€¢ Pub. Date: November 1999 â€¢ Publisher: Elsevier Science & Technology Books Introduction This pocket guide contains selected rules of thumb and shortcut design methods meant to travel into the field as well as the office, even when the "office" is a hotel room. It contains updates on certain fast-moving technology and new material not found elsewhere. Miniaturization and easy retrieval of information are stressed. Those on the go can produce reasonable results quickly when using this book as a basic source. Carl Branan E1 Paso, Texas Page 3 Pocket Guide to Chemical Engineering by Carl R. Branan â€¢ ISBN: 0884153118 â€¢ Pub. Date: November 1999 â€¢ Publisher: Elsevier Science & Technology Books Introduction This pocket guide contains selected rules of thumb and shortcut design methods meant to travel into the field as well as the office, even when the "office" is a hotel room. It contains updates on certain fast-moving technology and new material not found elsewhere. Miniaturization and easy retrieval of information are stressed. Those on the go can produce reasonable results quickly when using this book as a basic source. Carl Branan E1 Paso, Texas 1 Fluid Flow GENERAL Two of the most useful and basic equations are 2 U Ah=~ 2g (1-1) Au 2 AP (V) + ~ + AZ + E=0 (1-2) 2g where Ah = head loss in feet of flowing fluid u - velocity in ft/sec g = 32.2 ft/sec 2 P = pressure in lb/ft 2 V = specific volume in ft3/lb Z = elevation in feet E = head loss due to friction in feet of flowing fluid Page 4 Pocket Guide to Chemical Engineering by Carl R. Branan â€¢ ISBN: 0884153118 â€¢ Pub. Date: November 1999 â€¢ Publisher: Elsevier Science & Technology Books Introduction This pocket guide contains selected rules of thumb and shortcut design methods meant to travel into the field as well as the office, even when the "office" is a hotel room. It contains updates on certain fast-moving technology and new material not found elsewhere. Miniaturization and easy retrieval of information are stressed. Those on the go can produce reasonable results quickly when using this book as a basic source. Carl Branan E1 Paso, Texas 1 Fluid Flow GENERAL Two of the most useful and basic equations are 2 U Ah=~ 2g (1-1) Au 2 AP (V) + ~ + AZ + E=0 (1-2) 2g where Ah = head loss in feet of flowing fluid u - velocity in ft/sec g = 32.2 ft/sec 2 P = pressure in lb/ft 2 V = specific volume in ft3/lb Z = elevation in feet E = head loss due to friction in feet of flowing fluid 2 Pocket Guide to Chemical Engineering In Equation 1-1 Ah is called the "velocity head." This expression has a wide range of utility not appreciated by many. It is used "as is" for 1. Sizing the holes in a sparger 2. Calculating leakage through a small hole 3. Sizing a restriction orifice 4. Calculating the flow with a pitot tube With a coefficient it is used for 1. Orifice calculations 2. Relating fitting losses 3. Relief valve sizing 4. Heat exchanger tube leak calculations For a sparger consisting of a large pipe having small holes drilled along its length, Equation 1-1 applies directly. This is because the hole diameter and the length of fluid travel passing through the hole are similar dimensions. An orifice, on the other hand, needs a coefficient in Equation 1- 1 because hole diameter is a much larger dimension than length of travel (say ~ in. for many orifices). Orifices will be discussed under "Metering" later in this chapter. For compressible fluids one must be careful that when sonic or "choking" velocity is reached, further decreases in downstream pressure do not produce additional flow. This occurs at an upstream to downstream absolute pressure ratio of about 2:1. Critical flow due to sonic velocity has practically no application to liquids. The speed of sound in liquids is very high. See "Sonic Velocity" in this chapter. Page 5 Pocket Guide to Chemical Engineering by Carl R. Branan â€¢ ISBN: 0884153118 â€¢ Pub. Date: November 1999 â€¢ Publisher: Elsevier Science & Technology Books Introduction This pocket guide contains selected rules of thumb and shortcut design methods meant to travel into the field as well as the office, even when the "office" is a hotel room. It contains updates on certain fast-moving technology and new material not found elsewhere. Miniaturization and easy retrieval of information are stressed. Those on the go can produce reasonable results quickly when using this book as a basic source. Carl Branan E1 Paso, Texas 1 Fluid Flow GENERAL Two of the most useful and basic equations are 2 U Ah=~ 2g (1-1) Au 2 AP (V) + ~ + AZ + E=0 (1-2) 2g where Ah = head loss in feet of flowing fluid u - velocity in ft/sec g = 32.2 ft/sec 2 P = pressure in lb/ft 2 V = specific volume in ft3/lb Z = elevation in feet E = head loss due to friction in feet of flowing fluid 2 Pocket Guide to Chemical Engineering In Equation 1-1 Ah is called the "velocity head." This expression has a wide range of utility not appreciated by many. It is used "as is" for 1. Sizing the holes in a sparger 2. Calculating leakage through a small hole 3. Sizing a restriction orifice 4. Calculating the flow with a pitot tube With a coefficient it is used for 1. Orifice calculations 2. Relating fitting losses 3. Relief valve sizing 4. Heat exchanger tube leak calculations For a sparger consisting of a large pipe having small holes drilled along its length, Equation 1-1 applies directly. This is because the hole diameter and the length of fluid travel passing through the hole are similar dimensions. An orifice, on the other hand, needs a coefficient in Equation 1- 1 because hole diameter is a much larger dimension than length of travel (say ~ in. for many orifices). Orifices will be discussed under "Metering" later in this chapter. For compressible fluids one must be careful that when sonic or "choking" velocity is reached, further decreases in downstream pressure do not produce additional flow. This occurs at an upstream to downstream absolute pressure ratio of about 2:1. Critical flow due to sonic velocity has practically no application to liquids. The speed of sound in liquids is very high. See "Sonic Velocity" in this chapter. Fluid Flow 3 Still more mileage can be obtained from Ah - u2/2g when using it with Equation 1-2, which is the famous Bernoulli equation. The terms are 1. The PV change 2. The kinetic energy change or "velocity head" 3. The elevation change 4. The friction loss These contribute to the flowing head loss in a pipe. Howev- er, there are many situations where by chance, or on pur- pose, u2/2g head is converted to PV or vice versa. We purposely change u2/2g to PV gradually in the fol- lowing situations: 1. Entering phase separator drums to cut down turbu- lence and promote separation 2. Entering vacuum condensers to cut down pressure drop We build up PV and convert it in a controlled manner to u2/2g in a form of tank blender. These examples are dis- cussed under appropriate sections. PIPING PRESSURE DROP A handy relationship for turbulent flow in commercial steel pipes flowing full is: AP F -- Wl.8~to.2/20,000d4.Sp (~-3)Read More

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