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Kuwait University College of Engineering & Petroleum Depatment of Chemical Engineering. Production of Synthesis Gas From Natural Gas By Steam Reforming. Supervised By: Prof. Mohamed Fahim Eng. Yusuf Ismail Equipments Designed Done By Hessa Al-Sahlawi. Table Of Content;.
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Kuwait University College of Engineering & Petroleum Depatment of Chemical Engineering Production of Synthesis Gas From Natural Gas By Steam Reforming Supervised By: Prof. Mohamed Fahim Eng. Yusuf Ismail Equipments Designed Done ByHessa Al-Sahlawi
Table Of Content; -Introduction of Absorber. -Design Of Absorber. -Introduction Of Compressor. -Design Of Compressor. -Introduction Of Separator. -Design Of Separator. -Introduction Of Heat Exchanger. -Design Of Heat Exchanger.
1.Absorber Design: When the two contacting phases are a gas and a liquid , this operation is called Absorption . In our design we use Packed Column for CO2 absorber; the objective of the CO2 absorber is to remove CO2 from the effluent gas using Methyl-diethanolamine (MDEA) solvent
-Packed Bed: Packed Towers are used for continuous countercurrent contacting of gas and liquid in absorption as well as for vapor – liquid contacting in Distillation. -Type of Packing: Common types of packing which are dumped at random in the tower as shown
Selection of solvent: The essential elements of solvent selection criterion are feed gas characteristics (composition, pressure, temperature, etc.) and the treated gas specifications (i.e. the process requirements). -Design Parameter; Diameter , height and cost.
Design procedure of Packed Bed Absorber 1.Define fluid flow rates & Collect together the fluid physical properties required: density, viscosity, surface tension. 2.Define the equilibrium and Operating line.
3.get (m) slope of Equilibrium line. 4. get NOG From figure by calculate y1/y2 & m Gm/Lm 5.Calculate the column diameter by Calculate the Vw*. - Calculate . Lw: liquid flow rate, kg/hr ρL: liquid density,kg/m3 Vw: vapor flow rate, kg/hr ρv :vapor density, kg/m3 FLv: liquid-vapor flow factor
- Design for pressure 20 mmH2O/m packing . - From the Figure get K4 & K4 Flooding (Pressure drop interfere with high Correction factor ).
-Column Area Required = Gm/V*w Where; Gm: gas mass flow rate (kg/s) -Column Diameter=(4/π)*Area Column 6. Estimate the HOG then get Z ( Height ) estimate. USE CORNELL`S METHOD: -Get K3 (Percentage flooding Correction factor) -Get ψh (HGFactor) from Figure -Get φh (HL Factor)from Figure
- Assume HOG ( Height of heat transfer ) then Z=HOG*NOG -Then Calculate HL & HV ( height of liquid and gas respectively) Where Sc: is the Schmidt number (μ/D*ρ), μ (Viscosity ) ,D (diffusivity) , ρ (Density) -then Calculate; 7.Calculate Thickness: t=(Pri/(SEJ-0.6P))+Cc
8.Calculate Cost -Calculate Cost of packing by table: -Calculate Cost of Column by www.match.com
2.Compressor Design: Objective To increase the pressure of the feed from 14.7 psia to 18 psia Choosing the compressor type. Choosing the compressor type from figure
1.Calculate the compression factor (n) using the following equation: Where, P1,2 : is the pressure of inlet and outlet respectively (psia) T1,2 : is the temperature of the inlet and outlet respectively (R) 2. Calculate the work done in Btu/lbmol by: Where, R is the ratio of the specific heat capacities (Cp/Cv) 3. Calculate the horse power, Hp using the following equation: Hp=W*M Where, M is the molar flow rate in lbmol/s
4. Calculate the efficiency of the compressor using the following equation: Where , Mw :is the molecular weight of the gas in the stream CP :is the specific heat capacity (Btu/lb◦ F ) 5. Calculate the cost of the compressor from www. Match . com
3.Separator Design: -Separators are mechanical devices for removing and collecting liquids from natural gas. -There are Two type of two phase Separator a. Vertical Separator b. Horizontal Separator. in our project the separator was Horizontal
Design procedure of Horizontal Separator 1.calculate the settling velocity of the liquid droplet using the following equation :- Where: Ut=Settling velocity (m/s) ρL= density of liquid ρV; density of vapor 2- assume there is no demister 3-calculate the actual settling velocity in m/s Where: Ua=actual settling velocity (m/s)
4- Calculate the minimum vessel diameter. - Take hv( height of the vessel) =0.5 Dv (Diameter) & Lv (length of vessel) /Dv=4 -Cross Section Area for Vapor = π*Dv²/4 *0.5 -Vapor Velocity Uv= Volumetric / Cross Section Area for Vapor. - Vapor Resistance time = hv/Uv -Actual Vapor Resistance time = vessel length / Vapor velocity - Then For Satisfactory Separation required residence time = Actual - Then Get Minimum vessel diameter(Dv) & Length of Vessel 5- assume 10 min hold – up. 6-Determine the volume held in vessel using the above information's Volume = Area of Column * Length 7-Hold Up Time = Liquid Volume (m3) /Liquid volumetric Flow rate(m3/s)
8-Calculate the thickness of the separator using the following equation: t=(Pri/(SEJ-0.6P))+Cc 9- Calculate The Cost: From www.Match.com
4.Heat Exchanger Design: -Heat exchanger is a device designed to transfer heat from one fluid (liquid or gases) to another where the two fluids are physically separated. - In our design we assumed that the Heat Exchanger which used is a shell and tube heat exchanger. -the chose for shell and tube because it has a lot of advantage : 1- easy to clean. 2-The configuration gives a large surface area in a small volume. 3-Can be constructed from a wide range of materials.
Design procedure of shell and tube heat exchanger: Assumptions: 1- Use shell and tube heat exchanger, two shell and Multiple tube passes. 2- Assume the outer, the inner diameter and the length of the tube. ******************************** 1. Heat Load (Kw) 2.Log mean Temperature. Where -T1: Inlet shell side fluid temperature (˚C). -T2: Outlet shell side fluid temperature (˚C). -t1: Inlet tube side temperature (˚C). - t2:Outlet tube temperature (˚C).
4.Calculate the two dimensionless temperature ratios: R = (Thi - Tho) /(tco – tci) S = (tco - tci)/(Thi - tci) From Figure we get Ft Where ; Ft is temperature correction factor 5. Calculate True temperature difference ∆Tm= Ft *∆T lm 6.Choose U from table depending on the type of flows in shell and tube side U: Over all heat transfer coefficient
7. Calculate provisional area : 8.Assume inlet tube diameter, outlet tube diameter, and tube length. 9. Calculate area of one tube Where: L: Tube length ( m) do: outlet diameter (mm) 10.Calculate Number of tubes = provisional area / area of one tube. 11.Calculate bundle diameter Db = Do (Nt /K1)^(1/n1) Where: Db: bundle diameter (mm). Do: tube outer diameter (mm). Nt: number of tubes. K1 and n1 are constant from table .
12. From Figure determine bundle diametrical clearance. 13. Calculate shell diameter Ds = Db + Dc Where: Db : bundle diameter( mm) ( Dc : clearance diameter( mm
14-For Tube side coefficient calculate: - Mean temperature =((t1+t2)/2) - Tube cross sectional area A= (π/4)*di Tubes per pass = (Nt/Np) where Np: number of the tubes passes. -Total Flow area=(Tubes per pass * A*10-6) Where: A : Tube cross sectional area , m2 - mass velocity = (m/ Total Flow area) Where: m : mass Flow rate Tube side , kg/s - Linear velocity = (mass velocity/ ρ) Where: ρ : Tube Flow density , kg/m3
hi = ((4200*(1.35+0.02*t)*ut0.8)/di0.2) Where: hi : Tube inside coefficient , W/m^2.˚c t : Mean temperature , ˚C ut : Linear velocity , m/s di : Tube inside diameter , mm **The coefficient can also be calculated by: hi =( kf*jh*Re*Pr0.33 / di ) Where: kf : Thermal conductivity , W/m.˚c jh : Factor obtained from Figure di : inside diameter , mm Re = (u*di*ρ/μ) Pr = (Cp*μ/ kf) μ : viscosity , mNs/m2
15-For Shell side coefficient calculate: - baffle spacing lB = (Ds/5) - Tube pitch (Triangular Pitch)= 1.25 * do - As = ((pt – do)*DslB/pt) Where: As : Cross Flow area , m2 pt : tub pitch lB : baffle spacing , m -Gs = (Ws / As) Where: Ws : Fluid flow rate on the shell side , kg/s - Equivalent diameter= (1.1/do)*(pt2-0.917do2) - Mean Shell side temperature = (T1+T2/2) - hs = (kf*jh*Re*Pr(1/3)/de) Where: jh : determine from the Figure by choosing buffle percent.
16- Calculate over all coefficient 1/Uo= (1/ho)+(1/hod)+(doln(do/di)/(2kw))+(do/di) (1/hid)+(do/di)(1/hi) Where: Uo: the overall coefficient , W/m^2.oC ho: outside fluid film coefficient, W/m^2oC hi: inside fluid film diameter hod : outside dirt coefficient (fouling factor) hid: inside dirt coefficient, W/m^2.oC kw: thermal conductivity of the tube wall material di : tube inside diameter, m do : tube out side diameter, m
17-Calculate pressure drop for: - Tube side: ∆Pt = Np(8*jf*(L/di)+2.5)*(ρut2/2) Where: ∆Pt : tube side pressure drop , psia Np : number of tube side passes ut : tube side velocity , m/s L : length of one tube , m jf : From Fig
- Shell side : ∆P = 8*jf*(Ds/de)*(L/lB)*(ρ*us2/2) Where: ∆P : shell side pressure drop , psia Ds : shell diameter , m lB : baffling spacing , m jf : From Fig
18-Thickness: (t) = ((Pri)/(SEj-0.6P)) + Cc Where : P: maximum internal pressure, psia ri: inside radius of shell, m Ej: efficiency of joints as a fraction(Ej=0.85 for spot examined welding) S: maximum allowable stress, = 13700 Pisa Cc: allowance for corrosion, m = 0.125