Reactor Design

This is the powerpoint file of the reactor design that was assigned to me during my final year design project. I solved the rate equations in MATLAB to calculate the reactor volume.

1. Hashim Khan (DDP-SP13-BEC-53) Supervisor Dr. Maria Mustafa

2. Abstract Core objective of this project is to design and develop a profitable biodiesel production plant. Relying on the conventional mass and energy balances we can estimate the real life construction of this plant. Most diesel engines can run on cooking oil once they are warm, but cooking oil is not sufficiently volatile to start a cold diesel engine. A base catalyzed trans-esterification, using methanol as the alcohol and NaOH as the catalyst, converts fats and oils to the methyl esters of the three individual fatty acids. With molecular weights about a third of the original triglyceride, these methyl esters are more volatile and work well in diesel engines. The mixture of fatty acid methyl esters is called biodiesel.

3. Equipment Design AFTER ALL the preliminary work has been completed, the detailed design work is initiated. Equipment can be designed in its final form and full specification sheets prepared for each item. Process flowsheet and equipment list can be checked and amended. Cost estimates can also be revised to account for any significant changes from the preliminary design specifications.

4. Reactor Design The rectors we are using are CSTR jacketed vessels. We are using two of them in series . Our total conversion is 99% while per reactor conversion is 90 %. We are to design the two reactors. Reactor design mainly involves: Volume calculation Height/Diameter Impeller Design & Type Selection Thickness calculation P&I Diagram We will use reaction kinetics to calculate the reactor volume…

5. Why CSTR? Liquid phase reaction. Provides optimal mixing. The reactors can be operated at temperatures between -6.66 and 232 °C and at pressures up to 7 atm. Relatively cheap to construct. Also relatively easy to clean and maintain. Ease of control of temperature in each stage, since each operates in a stationary state; heat transfer surface for this can be easily provided hence it is relatively easy to maintain good temperature control with a CSTR. Can be readily adapted for automatic control in general, allowing fast response to changes in operating conditions (e.g., feed rate and concentration). With efficient stirring and viscosity that is not too high, the model behavior can be closely approached in practice to obtain predictable performance.

6. Assumptions & Approximations: Well mixed All reactants enter at the same time Steady State No extra side reactions Isothermal operation

7. Reactor Type CSTR Units Temperature 60 / 333 Total Conversion 99 Residence Time 1 Number Of Reactors 2 ----------- Configuration Series ----------- Molar Flow Of Oil ( ) 1.355 Volumetric Flow Rate Of Oil ( ) 1.35 Cao 1.0 Material of Construction SS Type 304 ----------- Reactor Type CSTR Units Temperature 60 / 333 Total Conversion 99 Residence Time 1 Number Of Reactors 2 ----------- Configuration Series ----------- 1.355 1.35 Cao 1.0 Material of Construction SS Type 304 ----------- Reactor Details Lets look at the provided information…

8. Reactions According to the literature the transesterification reactions takes place in three steps. That basically means that there are multiple reactions associated with this process.

9. Rate Constants (mole/dm^3*seconds) Values k1 .049 k2 .102 k3 .218 k4 1.280 k5 .239 k6 .007 k7 7.84e-05 k8 1.58e-05 Rate Constants Lets look at the provided information…

10. Rate Law We Know  

11. CSTR Volume Calculation The above mentioned differential equations were used to model the reaction rate through which the volume of the CSTR was calculated… as we know… Or  

12. Newer Version

13. Results After we solve the given ODEs for time t = 1 hour. We get volume of both the reactors. Now keeping the height to diameter ratio as 1.5 we can calculate the diameter and the height of the reactors. Properties CSTR Units Reactor 1 (V) 5.3 Reactor 2 (V) Residence Time 1 Properties CSTR Units Reactor 1 (V) 5.3 Reactor 2 (V) Residence Time 1

14. Diameter Of Reactor 1 Calculation of diameter keeping the ratio as (h/d = 1.5) =  

15. Diameter Of Reactor 2 Calculation of diameter keeping the ratio as (h/d = 1.5) =  

16. Impeller Type Mixing vessels fitted with some form of agitator are the most commonly used type of equipment for blending liquids and preparing solutions. Mixing occurs through the bulk flow of the liquid and, on a microscopic scale, by the motion of the turbulent eddies created by the agitator. Bulk flow is the predominant mixing mechanism required for the blending of miscible liquids and for solids suspension. Turbulent mixing is important in operations involving mass and heat transfer; which can be considered as shear controlled processes. The most suitable agitator for a particular application will depend on the type of mixing required, the capacity of the vessel, and the fluid properties, mainly the viscosity.

17. Properties CSTR Units Reynold's Number 6200 Dimensionless Capacity Of The Vessel Residence Time 1 hour Diameter 1.8 Height 2.5 rpm 1750 rpm Fluid Viscosity 0.0161 Properties CSTR Units Reynold's Number 6200 Dimensionless Capacity Of The Vessel Residence Time 1 hour Diameter 1.8 Height 2.5 rpm 1750 rpm Fluid Viscosity 0.0161 Reactor 1

18. Properties CSTR Units Reynold's Number 6200 Dimensionless Capacity Of The Vessel Residence Time 1 hour Diameter 1 Height 1.4 rpm 1750 rpm Fluid Viscosity 0.016 Properties CSTR Units Reynold's Number 6200 Dimensionless Capacity Of The Vessel Residence Time 1 hour Diameter 1 Height 1.4 rpm 1750 rpm Fluid Viscosity 0.016 Reactor 2

19. Impeller Type Reactor 1 In the light of the data provided we use the turbine type impeller… Properties CSTR Units Reynolds Number 6200 Dimensionless Capacity Of The Vessel Residence Time 1 Hour Fluid Viscosity 0.016 Properties CSTR Units Reynolds Number 6200 Dimensionless Capacity Of The Vessel Residence Time 1 Hour Fluid Viscosity 0.016

20. Impeller Type Reactor 2 In the light of the data provided we use the turbine type impeller… Properties CSTR Units Reynolds Number 6200 Dimensionless Capacity Of The Vessel Residence Time 1 Hour Fluid Viscosity 0.016 Properties CSTR Units Reynolds Number 6200 Dimensionless Capacity Of The Vessel Residence Time 1 Hour Fluid Viscosity 0.016

21. Impeller Diameter Reactor 1 For turbine agitators, impeller to tank diameter ratios of up to about 0.6 are used, with the depth of liquid equal to the tank diameter. Properties CSTR Units Impeller Diameter (ID) ? Vessel Diameter (VD) Ratio (ID/VD) .6 Dimensionless Impeller Diameter (D) .3 Properties CSTR Units Impeller Diameter (ID) ? Vessel Diameter (VD) Ratio (ID/VD) .6 Dimensionless Impeller Diameter (D) .3

22. Impeller Diameter Reactor 2 For turbine agitators, impeller to tank diameter ratios of up to about 0.6 are used, with the depth of liquid equal to the tank diameter. Properties CSTR Units Impeller Diameter (ID) ? Vessel Diameter (VD) Ratio (ID/VD) .6 Dimensionless Impeller Diameter (D) .6 Properties CSTR Units Impeller Diameter (ID) ? Vessel Diameter (VD) Ratio (ID/VD) .6 Dimensionless Impeller Diameter (D) .6

23. Material of Construction We are using carbon steel because it does not let the oil stick as well as is suitable for the protecting against the corrosiveness of the caustic. Our process parameters are as such are not extreme. A mere 60 °C is required to maintained in the reactor. While the steam were providing has a temperature of 141 °C and is at 2.74 bar pressure. A very suitable option hence also recommended in our primary literature is Type 304 (the so-called 18/8 stainless steels). These are widely used and widely available steels. A simple jacket can withstand pressures up to 10 bar therefore we can simply use a simple jacket construction around our vessel.

24. Material of Construction Parameter Value Units Temperatur e 60 / 333 (Vessel) °C / °K 141 / 414 (Jacket) °C / °K Pressure 103 / 1 bar (Vessel) 274 / 2.74 bar (Jacket) Parameter Value Units Temperatur e 60 / 333 (Vessel) °C / °K 141 / 414 (Jacket) °C / °K Pressure 103 / 1 bar (Vessel) 274 / 2.74 bar (Jacket)

25. Material of Construction Parameter Value Units R-1 Volume 5.3 R-2 Volume 1 R-1 Diameter 1.8 R-1 Height 2.5 R-2 Diameter 1 R-2 Height 1.4 Impeller Type For Both Turbine Dimensionless R-1 Impeller Dia. 1.08 R-2 Impeller Dia. .6 Parameter Value Units R-1 Volume 5.3 R-2 Volume 1 R-1 Diameter 1.8 R-1 Height 2.5 R-2 Diameter 1 R-2 Height 1.4 Impeller Type For Both Turbine Dimensionless R-1 Impeller Dia. 1.08 R-2 Impeller Dia. .6

26. END