Supervised by : Dr. mohammad fahim Eng. Yousef ali Yaqoub bader ali

agenda Heat exchanger design Alkylation reactor design Pump design

Heat exchanger design Heat exchanger are component that allow the transfer of heat from one fluid to another fluid without direct contact between them. The heat is transferred from the hot fluid to the metal isolating the two fluids and then to the cooler fluid.

Types of heat exchanger

Shell and tube heat exchanger Floating head heat exchanger type:

:Heat load Q h = M h Cp (T 1 -T 2 ) where: Q h = heat load in the hot side (KW) M h = mass flowrate of hot fluid (Kg/h) Cp = heat capacity of hot fluid (kJ/kg o C) T 1 = inlet temperature ( o C) T 2 =outlet temperatue ( o C)

Log mean temperature: ∆T lm =(T1-t2)-(T2-t1) / ln((T1-t2)/(T2-t1)) where: ∆T lm = log mean temperature differace T 1 = inlet shell side fluid temoerature ( o C) T 2 = outlet shell side fluid temerature ( o C) t 1 = inlet tube side temoerature ( o C) t 2 = outlet tube side temerature ( o C)

Temperature correction factor Ft: Take one shell pass ; two tube or more even tube pass. ∆Tm = F t ∆T lm where: ∆Tm = true temperature difference F t = the temperature correction factor ∆T lm = log mean temperature differace

Heat transfer area A= Q / U ∆T m where: A = provisional area (m 2 ) Q = heat load (kW) U = overall heat transfer coefficient (W/m 2 o C) U is assumed

Bundle diameter : D s = D b + Bundle diametrical clearance (from fig.). D b = (d o )*( N t / K 1 )^ (1/n 1 ) Where: D b =bundle diameter (mm) d o = outer diameter (mm) N t : number of tubes K 1 & n 1 are constant Assume inner, outside diameters of the tubes

Tube layout Take triangular pitch Pt=1.25d0 take No. passes for tubes = 8

:Inside coefficient hi

Types of baffles: Type: single segmental. Choose baffle spacing (L b )= (D s /5)

Shell side coefficient h s = k f * j h *Re *Pr^(1/3) / d e Where: de=equivalent diameter. jh=heat transfer factor.

Over all heat transfer coefficient: Where: Uo: overall heat transfer coefficient hi: inside heat transfer coefficient ho: outside heat transfer coefficient do: outer diameter di: inner diameter Kw: wall thermal conductivity

Pressure drop (tube side): Δ P t = N p [ 8j f (L/d i )(µ/µ w )^(-m) +2.5 ] ρ u t ²/2 where : Δ P t = tube side pressur drop (N/m²)(pa) N p = number of tube side passes u t = tube side velosity (m/s) L = length of one tube

Pressure drop (shell side): Δ P s = 8j f (D s /d e )(L/L b )( ρ u s ^2/2)(µ/µ w )^(-0.14) where : L : tube length L b : baffle spacing

Thickness calculation: t =(Pr i /(SE J -0.6P))+C c where: t = shell thichness (in) P = Maximum allowable internal pressure (psig) r i = internal raduis of shell before allowance corrosion is added (in) E J = efficincy of joients S = working stress (psi) C c = allowance for corrosin (in)

Reactor design Chemical reactors are vessels designed to contain chemical reactions. Batch No flow of material in or out of reactor Changes with time Continuous Flow in and out of reactor Continuous Stirred Tank Reactor (CSTR) Plug Flow Reactor (PFR) Steady State Operation

Fixed bed catalytic rector design Main reaction: C 6 H 6 + C 2 H 4 → C 6 H 5 CH 2 CH 3 Liquid phase alkylation of benzene to ethylbenzne (exothermic reaction). Limiting reactant : Ethylene

Fixed bed catalytic rector design Design equation: Rate law: Concentration:

Fixed bed catalytic rector design The change in the number of moles per mole of A reacted is :

Fixed bed catalytic rector design Volume of cylindrical part of reactor: Length and diameter of cylindrical part of reactor: (assume L/D)

Fixed bed catalytic rector design Volume of spherical head: V= (4/3)*( Л )*(D/2)³ Total volume of the reactor: V (total)= Volume of spherical head + Volume of cylindrical part of reactor

Fixed bed catalytic rector design Assume space between two bed. Height of the reactor: H= length of cylindrical part of reactor +(2*space between bed) Area of the reactor: A=V (total)/H

Fixed bed catalytic rector design Reactor thickness: t =(Pr i /(SE J -0.6P))+C c where: t = shell thickness (in) P = Maximum allowable internal pressure (psig) r i = internal radius of shell before allowance corrosion is added (in) E J = efficiency of joints S = working stress (psi) C c = allowance for corrosion (in)

Pump design Pump is a device that move fluid from low level to high level.

Pump design Actual head of pump : P1 (Initial pressure) P2 (Final pressure). ρ is the density. g (Gravity). ha is the head of pump.

Pump design Water horse power: Q (volumetric rate). Pf is the water horse power (hp).

Pump design Overall efficiency : WHP is the horse power (hp). BHP is the brake horse power (hp)