Mixing Apparatus for fluids

Process Design A Group 2 Recovery and make up ofNaOH solution.

Manroshan Singh Suresh Nallan ShaikarPang Wei Chuan Irfan Hisham Stacey Sim2Manroshan Singh Suresh Nallan ShaikarPang Wei Chuan Irfan Hisham Stacey Sim Process Design A Group 2 Recovery and make up ofNaOH solution.

Project DescriptionTo design a process facility to supply 40 wt% NaOH solution at 45C, at 1.5 to 2 m3/hr, to an aluminium extraction plant. Solid NaOH flakes will be delivered to and a dilute solution will be made up ready to supply to the aluminium plant. Spent caustic solution (approximately 6 to 7 wt% NaOH at 5 to 6 m3/hr) will be returned to and must be concentrated up through a series of evaporators. The reprocessed NaOH solution is to be concentrated via three evaporators; the first raises the concentration from 6.5 w/w% to 9 w/w%, the second from 9 w/w% to 15 w/w% and the third and final evaporator from 9 w/w% to 40 w/w%. Standard utilities available on site are cooling water at 10C, and also saturated steam at 1 and 10 bar.Step Design ProcessConcept

ProductFlow Diagram

Material and Energy BalanceMixing Tank

Evaporator 1 (6.5%w.w to 9%w.w)Mass balance FLVNaOH0.22750.22770H2O3.27252.30230.97Total3.52.530.97Energy balanceFSLVQin769.363317.80300Qout001496.6892590.476Total4087.1634087.1657Evaporator 2 (9%-15%)Mass balance FLVNaOH0.22770.25350H2O2.30231.43651.13Total2.531.691.13Energy balanceFSLVQin1496.692590.4800Qout001098.432988.73Total4087.174087.168Evaporator 3(15%-40%)Mass balance FLVNaOH0.25350.3160H2O1.43650.4741.32Total1.690.791.32Energy balanceFSLVQin1098.42988.72500Qout00654.33432.88Total4087.1254087.189Heat ExchangerF2F3F1F410Mass flow rate (hot)=100kg/sMass flow rate (cold)=75kg/sCp=4.2kJF1-Temperature=100oCF2-Temperature=93.05oCF3-Temperature=83.14oCF4-Temperature=60oCQ in =7081.2Q out=7081.2Mixing Apparatus for fluidsA Container (carbon steel) and A Mixing Device or Impeller (stainless steel)Set by ratio

16/08/2012Mixing: Theory and Equipment11Baffled containers should be used. In such case impeller can be mounted vertically at the center.

0.8m3m2m1.2m0.8m2mPropellers16/08/2012Mixing: Theory and Equipment12It consists of number of blades, generally 3 bladed design is most common for liquids. Blades may be right or left handed depending upon the slant of their blades.

Two are more propellers are used for deep tank.

Advantages of propellers: Used when high mixing capacity is required.Effective for liquids which have maximum viscosity of 2.0 pascals.sec or slurry up to 10% solids of fine mesh size.

Disadvantages of propellers: Propellers are not normally effective with liquids of viscosity greater than 5pascal.second, such as glycerin castor oil, etc.,13

Axial component or longitudinal or vertical: Acts in the direction parallel to the impeller shaft. Adequatelongitudinal pattern is best used to generate strong vertical currents particularly when suspending solids are present in a liquid.

14Impeller typeFlow componentPropellersAxialTurbinesAxial or tangential or bothPaddlesRadial and tangential Paddles with pitchRadial, tangential and axial

BafflesUsed to prevent vortexingBaffle width: 0.166mBaffle off the wall distance: 0.044 to 6 baffles is the standard

Control and Safety16Evaporator 117IntroductionDimensionsProf. R. Shanthini 05 June 2012

Types of evaporators Vertical Falling Film Evaporators: The tube length is typically 6 m to 11 m, but can be as short as 1.5 m to 3 m (for example, in deep vacuum applications).

Diameters are typically 20 mm to 64 mm.

20ds = 0.812mH = 8md = 1mdt = 0.0603mds = 0.762mTube pitch = 0.077mSteam inCastic soda inWater vapour outCastic soda outWater vapour outEvaporatorVapor outFeed inSteam in (Saturated vapor)Product outCondensate out (Saturated Liquid)Vapor SeparatorHeat ExchangerVacuum for non condensableCondensor unitCoolant InCoolant outEvaporator 2

Forward Feeding

Steam feed and solution feed comes from the same side(parallel)Temperatures of evaporators decrease along evaporators.Pressure decreases along the three evaporators (from 1 bar to lower)Better if the feed is hot.Falling Film evaporators

DimensionsUnit(m)Height9(m)Outer Diameter1.3(m)Inner Diameter1.2(m)Thickness0.1(m)Number of tubes1201= Feed stream2= Inlet Steam feed3= Outlet Steam feed4= Loss5= concentrated feed(outlet) AdvantagesSpecificationsMaterial and running costVolume of shell (outer)=4.315396m3Volume of shell (inner)=3.800306m3Volume of shell=0.51509m3Density of carbon steel =7820kg/m3Mass=4028.006kgCost per kg=3.0085RMVolume of tube (outer)=0.022846m3Volume of tube (inner)=0.015708m3Volume of tube =0.007138m3Density of stainless steel=7780kg/m3Mass=55.53569kgCost per kg=24.3415RMCostCost of shell is considerably cheaper due to economical reasons.- Tube is higher because stainless steel is usedStainless steel has a higher heat conductivity to transfer the heat better.Tube has a lesser density to save weight.

Calculation of CostTotal cost of carbon steel =12118.26RMTotal cost of stainless steel =1351.822RMOverall cost =13470.08RMPower required =3317.803kJ/s=11944091kW/hCostFirst 200=21.84360CentsNext 100=33.43340CentsNext 300=51.615480CentsNext 300=54.616380CentsTotal900=39560Cents Cost for the first 900 kW/h = RM395.60Remaining power required=11943191kW/hCost for 1 kWh=57.1centsCost after 900=6.82E+08cents=6.82E+08centsOverall cost =6819562RM=6.82milRMTotal running cost for 1 month: RM6.82 millionEvaporator 3Vertical Falling-film EvaporatorDimensions of third effect

8.5m0.8653m0.05mArea of heat transfer obtained is 168.17m2.Number of tubes is found to be 126.Heat transfer per tube is 0.137m2Safety and Precautions

A machine for transfering fluid by accelerating the fluid radially outwardA collection chamber in the casing converts much of the Kinetic Energy into Head or Pressure.Centrifugal PumpCentrifugal Impellers

Eye of the ImpellerWater EntranceImpeller VanesDiameter of the ImpellerThickness of the impellerThicker the Impeller - More WaterLarger the diameter - More PressureIncrease the Speed - More Water and PressureHeat Exchanger-HX01What is HX01How It Works?

Why shell-and-tube?

Dimensions

Construction baffleTubesShellCentrifugal PumpTo induce flow or raise pressure of a liquid.From heat exchanger to storage tank.

ConclusionMixing Tank - from