EQUIPMENT DESIGN: BASIC CONCEPTS GOALS. ◆ Definitions and Concepts ◆ Types of Design Design Methodology /2499 Equipment desi
8/24/99 Equipment Design 1 EQUIPMENT DESIGN: BASIC CONCEPTS GOALS: u Definitions and Concepts u Types of Design u Design Methodology
EQUIPMENT CHARACTERIZATION Input Output Streams Streams Operating size Parameters Parameters /2499 Equipment desi
8/24/99 Equipment Design 2 Input Streams Output Streams Operating Parameters Size Parameters EQUIPMENT CHARACTERIZATION
DEFINITIONS ◆ EOUIPMENT RATING E Given the input streams, operating parameters, and size parameters, determine the eguipment performance and output streams ◆ EOUIPMENT SIZING E Given the input streams and the performance specifications, estimate the economically important size parameters using approximate methods ◆ EOUIPMENT DESIGN: E Produce a design in enough detail to guide the fabrication of the item ofequipment /2499 Equipment desi
8/24/99 Equipment Design 3 DEFINITIONS u EQUIPMENT RATING: ð Given the input streams, operating parameters, and size parameters, determine the equipment performance and output streams u EQUIPMENT SIZING: ð Given the input streams and the performance specifications, estimate the economically important size parameters using approximate methods u EQUIPMENT DESIGN: ð Produce a design in enough detail to guide the fabrication of the item of equipment
Equipment Design Methodology Determine Performance Operational Specifications Constraints Choose Equipment Try First Type and Design Parameters Perform Rating Calculations Iterate sfy Specs R Constraints Yes Done /2499 Equipment desi
8/24/99 Equipment Design 4 Equipment Design Methodology Set Performance Specifications Determine Operational Constraints Choose Equipment Type and Design Parameters Perform Rating Calculations Satisfy Specs & Constraints? No Iterate Yes Done Try First
EXAMPLE #l: REFLUX DRUMI PROBLEM: Design a reflux drum for a distillation column o For a residence time of 15 minutes when half full, That has a length to diameter ratio L/d=3.0 and ◆ Is horizontal. OPERATING CONDITIONS o Flow rate out of drum is 5, 000 Kg/hr Flow is 100% Ethanol SG=0.7891 8/24/99 Equipment desi
8/24/99 Equipment Design 5 EXAMPLE #1: REFLUX DRUM PROBLEM: Design a reflux drum for a distillation column u For a residence time of 15 minutes when half full, u That has a length to diameter ratio L/D = 3.0, and u Is horizontal. OPERATING CONDITIONS: u Flow rate out of drum is 5,000 Kg/hr u Flow is 100% Ethanol (SG = 0.789)
REFLUX DRUM From Overhead Condenser D Reflux to Column Distillate /2499 Equipment desi
8/24/99 Equipment Design 6 From Overhead Condenser Reflux to Column Distillate D L REFLUX DRUM
DESIGN CALCULATIONS o Holdup =(5000 kg/hr)(0.25 hr)=1250 kg ◆Deiy=(0.789(100kgm)=789kg/m3 ◆ome=(2)(1250kg)789kgm)=3.17mp3 To simplify the size calculations, neglect the holdup in the dished heads of the drum) ◆ Volume=3.1416①D2)L(butL=3.0D,so) ◆D=3.7/3)/3.1416)S0, ◆D=0.695 m andL=2.09m /2499 Equipment desi
8/24/99 Equipment Design 7 u Holdup = (5000 kg/hr)(0.25 hr) = 1250 kg u Density = (0.789)(1000 kg/m3 ) = 789 kg/m3 u Volume = (2)(1250 kg)/(789 kg/m3 ) = 3.17 m3 (To simplify the size calculations, neglect the holdup in the dished heads of the drum.) u Volume = 3.1416 (D2 ) L (but L = 3.0 D, so) u D3 = 3.17/(3)/(3.1416) So, u D = 0.695 m and L = 2.09 m. DESIGN CALCULATIONS
EXAMPLE #2 FLASH DRUM PROBLEM: Design a flash drum that is To flash a stream that is 60 mol% ethylene and 40 mol% water at a flow rate of 800 kmovhr, o To produce a vapor that is 99% ethylene 9 At a fractional recovery ofethylene of% The flash drum is a vertical pressure with an L/D=4.0 OPERATING CONSTRAINTS Low entrainment of water in the vapor o 10 minute holdup of liquid when drum is 1/2 full 8/24/99 Equipment desi
8/24/99 Equipment Design 8 EXAMPLE #2: FLASH DRUM PROBLEM: Design a flash drum that is u To flash a stream that is 60 mol% ethylene and 40 mol% water at a flow rate of 800 kmol/hr, u To produce a vapor that is 99% ethylene u At a fractional recovery of ethylene of 99 % u The flash drum is a vertical pressure with an L/D = 4.0. OPERATING CONSTRAINTS: u Low entrainment of water in the vapor u 10 minute holdup of liquid when drum is 1/2 full
FLASH DRUM VAPOR FEED he Cooling LIOUID /2499 Equipment desi
8/24/99 Equipment Design 9 VAPOR LIQUID Heating or Cooling FEED FLASH DRUM
DESIGN PROCEDURE BASIC DESIGN VARIABLES: Pressure p and heat Duty Q Guess values for P and o. Do the adiabatic flash calculation to determine v, l and their compositions and temperature o Ifthe performance specifications are satisfied, proceed to size the drum i not iterate on P and g o Size drum to satisfy entrainment, liquid holdup and LD constraints /2499 Equipment desi
8/24/99 Equipment Design 10 DESIGN PROCEDURE uBASIC DESIGN VARIABLES: Pressure P and Heat Duty Q.. u Guess values for P and Q. Do the adiabatic flash calculation to determine V, L and their compositions and temperature u If the performance specifications are satisfied, proceed to size the drum. If not iterate on P and Q. u Size drum to satisfy entrainment, liquid holdup and L/D constraints