TABLE OF CONTENTSTITLEPAGE1.0 INTRODUCTION.22.0 THEORY..5 3.0 ABSTRACT104.0 RESULT...114.1 CALCULATION124.2 DISCUSSION.185.0 CONCLUSION....226.0 REFERENCES....23 7.0 APPENDICES.24

1.0 INTRODUCTIONMethanol is one of the raw material needed in production of petrochemical products. Methanol is also the lowest number of organic compound that belongs in alcohol family. Compare to its relative ethanol, methanol is very poisonous, and may harm human even with small amount. With its annual production of 40 Million tons, Methanol has a steady need in the global market.For this project, Haldor Topsoe large scale Methanol Production Plant is used as the base for developing a new kind of Methanol Production plant. Boiling water reactor will be used as a reference in developing a new reactor that can achieve higher conversion rate.To do so, several calculations discussion is needed. This is where Chemical Reaction Engineering comes to life. Chemical reaction kinetics is calculated and discussed. Points like reaction constant, reaction order, activation energy, reactor volume, and residence time distribution is calculated in order to come up with a new reactor design.The process that had been selected for the production of methanol is the synthesis of methanol by using natural gas. The synthesis of methanol by using natural gas involved a few methods such as, one-step reforming, two step reforming, and auto thermal reforming. In this project, the production of methanol is concentrated on the one-step reforming which includes only one single reaction which isCO2 + 3 H2 CH3OH + H2OOne-step reforming in order words is the synthesis of gases which will produce the tubular steam reforming alone without the usage of oxygen, O2. This process is basically using CO2 that contained in natural gas or any CO2 that available at low cost from other resources. This process is started in Iran in 2004. (Petersen, 2006). This process also been conducted under isothermal condition.

Reactor Uses And Process Flow Diagram (PFD)

Figure 1 : Methanol Production by one-step reformerBased on the process flow diagram above, the synthesis of methanol between carbon dioxide and hydrogen is conducted in methanol reactor to produce the desired product, methanol and water. There are two types of reactors which are suitable synthesis of methanol for this type of process which are :a) Adiabatic reactorb) Boiling water reactor (BWR)Based on the efficiency and ease for temperature control, boiling water reactor (BWR) had been chosen for this project. In the BWR, it consists of shell and tube heat exchanger with catalyst on the tube side. This reactor will operate at intermediate temperatures in order to ensure the proper reaction rate. BWR is complex in design and sometimes cost relatively in high investment, but its advantages shown that the usage of this reactor in a methanol plant is worth even at the high investment cost. Other than that, this reactor also gives isothermal nature inside it, and result in a very high conversion compared to the amount of catalyst installed. This is done by controlling the pressure of the circulating boiling water, thus the temperature of the reaction is controlled and optimized, (Trondheim, 2010).Boiling water reactor (BWR), used in the methanol plant is consists of a few which made up the main reactor BWR. One of the reactors which is important in the designing of main methanol reactor BWR is continuous stirred tank reactor (CSTR). The principle of CSTR include, it is operated under steady state and usually operated quite a well mixed. Apart from that, CSTR is modeled as having no spatial variations in concentrations, temperature or reaction rate throughout the vessel.

2.0 THEORYReactor DesigningThere are many types of reactor to choose from. Each and every of it has their own advantages and disadvantages.Batch Reactor

Figure 2:Application:1) Small scale production.2) Pharmaceutical and fermentation.Advantages:1) Easy to clean.2) High conversion per volume.3) Flexibility of operation-same reactor.Volume:

Continuous Stirred Tank Reactor

Figure 3Application:1) A production where agitation is required.2) Continuous production.Advantage:1) Easy to clean.2) Good temperature control.3) Low operating cost.Volume:

In terms of conversion,

Reactor sizing also can be calculated by measuring the area of the graph of vs X

Plug Flow Tank Reactor

Application:1) A production of large scale.2) Production with fast reactions and high temperature.3) Both homogenous and heterogeneous reaction.4) Continuous production.Advantages:1) High conversion per volume.2) Low operating cost and good heat transfer.Volume:

In terms of conversion,

Thus,

Reactor sizing also can be calculated by measuring the area under the graph of vs X

For chemical reaction kinetics, there are a few part that need to be consider in this reaction for production of methanol. In this project, a few parts of chemical reaction kinetics that have to be consider are; reaction rate constant, k, rate law, residence time.Rate lawRate law is defined as an algebraic equation that is solely function of the properties of the reacting materials and reaction condition.For example, algebraic for of the rate law for ra for the reactionA + B productTherefore, the rate law for this type of reaction is:ra = k [CA] [CB]Meanwhile k in this equation is reaction rate constant. Somehow, in any equation of rate law, the value of k can be determined if the concentration values for both reactants are given. Meanwhile, the residence time distribution (RTD) is defined as the amount of the fluid elements is taken inside the reactor. It is been calculated by using this kind of equation:RTD = ..(1)..(2)In this project, the activation energy of the reaction is also been solved by using this equation:ln =

3.0 ABSTRACTThe objectives for this project in chemical reaction engineering is to determine and doing some calculations regarding chemical reaction kinetics for instance, rate law and its order, rate constant, activation energy and residence time distribution. Other than that, the basic design assumption for suitable reactor also had been done in this project for production of methanol. In this production of methanol, the selection process that had been chosen is production of methanol between the reaction of carbon dioxide, CO2 and hydrogen, H2. The reaction that had been chosen is under single reaction and is conducted in isothermal condition. The reactor use for this reaction is boiling water reactor (BWR) that consist of a few type of reactors and the reaction is in one step reforming process. For production of methanol, a few types of methanol reactor can be used such as boiling water reactor (BWR), quench reactor and adiabatic reactor. Boiling water reactor (BWR) had been chosen among three of the reactor because of its characteristics which is more suitable to perform the production of methanol in isothermal condition and its selectivity which is very high.For result and discussion part in this project, the information and experimental data had been selected to do some calculation regarding the production. The data selected in a journal, patent and book include the inlet and outlet flow rate for the production, temperature range for the production, reaction rate constant, the order of reaction, density and molecular weight of the reactant and others information and important data that need to be considered in order to develop the basic design of the reactor.

4.0 RESULT In production of methanol, the reaction for the synthesis of methanol is from carbon dioxide, CO2 and hydrogen, H2. The reaction for this synthesis is as follow :CO2 + 3 H2 CH3OH + H2O`The limiting reactant for this reaction is hydrogen, H2 and the excess reactant for this reaction is carbon dioxide, CO2.

4.1 CALCULATIONIn our research, weve obtained experimental data of the Methanol Reactor. Given are the molar flowrate of in and out:RunMolar Flow Rate in (mole/hour)Molar Flow Rate out (mole/hour)

14.15183.9182

24.15504.0552

34.15024.0413

44.15024.0549

54.15094.0227

From the given flow rates, weve calculated the concentration of the H2 and CO2 as follows sample calculation:Flow rate out = 3.9182 mol /hourH2 mole fraction = 0.6364 mol H2/molMolar mass of H2 = 2.00 g/molDensity of H2 = 89.9 g/m3

These calculation is further continued with CO2 and all 5 flow rates, below are the result:

RunsMolar Flowrate outMole fraction H2Mole fraction CO2Concentration H2Concentration CO2

13.91820.63640.36360.0222470.022261

24.05520.63430.36570.0222470.022261

34.04130.63550.36450.0222470.022261

44.05490.63470.36530.0222470.022261

54.02270.63480.36520.0222470.022261

As you can see, the concentration is the same for each run, we also calculated the concentration based on molar flow rate in, it also, gave the same concentration. Thus, this concentration is acceptable.From these concentrations, further calculation can be made. One of it was sizing of the reactors. In order to calculate the sizing of the reactor, below equation is used:

To do this, value of reaction constant, k, is needed. Below are the values of k for each five runs conductedRunsReaction Constant, k

124.04

275.51

334.67

448.42

534.67

Without further ado, below are the sample calculation for reactor sizing:Molar Flowrate H2 out = 2.4935 mol/hourMolar Flowrate H2 in = 2.64221 mol/hourReaction constant, k = 24.04Concentration of H2 = 0.022247 mol/m3

Further calculation is continued with all five runs, below are the result of the calculation:

RunsFAoFAConversion, XConcentration H2Reaction Constant, k (s-1)Volume, m3

12.642212.4935420.9437352470.02224724.044.662427

22.635522.5722130.9759807460.02224775.511.531201

32.637452.5682460.9737603010.02224734.673.329757

42.634132.5736450.9770372510.02224748.422.389206

52.634992.5536100.9691151320.02224734.673.310781

From the results, 4th run have the highest conversion rate which is 0.977. While its reactor volume was 2.39 m3. This is the best flow rate and reactor volume to have in order to achieve the highest conversion rate.For reaction kinetic section ;CO2 + 3 H2 CH3OH + H2OLimiting reactant : H2Excess reactant: CO2Meanwhile the rate law obtained for this type of reaction is as follow:

Rate Law-ra = k [CO2] [H2]3Reaction orderBased on the data information obtained from a journal written by L. C. Grabow and M. Mavrikakis, the order of reaction for this type of reaction obtained based on calculation is 1.34 which means the reaction is in the first order of reaction. Furthermore, the data obtained for the reaction constant for this production of methanol is in the unit of s-1 which proved the reaction equation that had been chosen for this production of methanol is in the first order of reaction. For the first order of reaction, the graph is appear like below ;

Residence time:The residence time is calculated by using formulae belowRTD = ..(1)..(2)For this situation, the first formulae is usedRTD = Based on above calculation, the volume of reactor and the total flowrate for this production obtained are;

Therefore,The volumetric flowrate is calculated based on the molar flowrate and the result based on the calculation is as follow ;VolFCo2VolFH2

0.0336050850.05878099

0.0338252240.05863218

0.0336752830.058675241

0.0337491930.058601378

0.0337456450.058620497

0.1686004320.293310287

The total flow rate for both CO2 and H2 is equal to 0.461910718 m3/hRTD = = 10.09378 h-1/0.1683 min-1 Activation Energy:The activation energy for this reaction is been calculated based on the temperature range obtained from the data in the journal ;ln k =ln A -

The value of A is obtained from the graph,Temperature (K)Reaction Constant, k1/Temperatureln k

47824.040.002092053.17971911

48775.510.0020533884.324265098

49634.670.0020161293.54587476

51448.420.0019455253.879912952

52334.670.0019120463.54587476

From the graph, the equation of line obtained isy = 0.0288x + 3.6087Therefore the value of ln A obtained is 3.60873.17971911=3.6087- E = -1704.81 J/mol The value is appear in negative because the production of methanol is an exothermic reaction.

4.3 DISCUSSIONReactor sizingIn order to calculate the reactors volume, flow rates of in and out of the reactor is needed. Weve obtained data on flow rates in and out of the methanol reactor from Sunggyu, L, Methanol Synthesis Technology. RunMolar Flowrate in (mole/hour)Molar Flowrate out (mole/hour)

14.15183.9182

24.15504.0552

34.15024.0413

44.15024.0549

54.15094.0227

From these data, concentration of H2 and CO2 is calculated in order to determine the reaction rate of the whole process. By performing simple unit changing calculation, the concentration of H2 and CO2 is obtained.RunsMolar Flowrate outMole fraction H2Mole fraction CO2Concentration H2Concentration CO2

13.91820.63640.36360.0222470.022261

24.05520.63430.36570.0222470.022261

34.04130.63550.36450.0222470.022261

44.05490.63470.36530.0222470.022261

54.02270.63480.36520.0222470.022261

From above table, we can see that the concentration of H2 and CO2 is the same for each run. This is acceptable since the manipulated variable is the flowrate of the inlet, not on the concentration (Sunggyu, L, Methanol Synthesis Technology). Conversion rate, X, is also calculated to determine which run has the highest conversion rate. Below are the obtained data.RunConversion Rate, X

10.943735247

20.975980746

30.973760301

40.977037251

50.969115132

Reaction rate is determined by multiplying the reaction constant, k with the concentration of H2 for each run. What about concentration CO2? Is neglected since CO2 is and excess component in the whole process. Below are the reaction rates of each runs.RunReaction Rate, -rA

10.534816

21.679867

30.771301

41.077197

50.771301

With obtained reaction rate, reactor volume can be obtained by using the Plug Flow Reactor volume equation. This is because, inside the reactor model, plug flow tank is used rather than continuous stirred tank as methanol is more suitable produce inside a plug flow reactor (Sunggyu, L, Methanol Production Technology). Below are the obtained volume for each run.

RunReactor Volume, m3

14.662427

21.531201

33.329757

42.389206

53.310781

As the conclusion, 4th run has the highest reaction conversion rate, which is 0.997. Also, it has decent reactor volume which is 2.389 m3. High conversion rate and small volume is what we needed and we had achieved it.For the calculation of reaction kinetics in this production of methanol, reaction kinetics that need to be considered are rate law, reaction constant, residence time, activation and order of reaction. As mentioned in previous chapter, the rate law that can be built from the equation is as followed:CO2 + 3 H2 CH3OH + H2OBased on unit of reaction constant that is obtained, this reaction is the first order of reaction. The limiting reactant for the reaction is hydrogen, H2 and the excess reactant is carbon dioxide, CO2 because the proportion of hydrogen. H2 used in this production is in the lowest proportion compared to carbon dioxide, CO2. Carbon dioxide, is one of the abundance and high percentage of gas in the air. So, the rate law obtained from this equation is:-ra = k [CO2] [H2]3For the rate constant for this production, the datas obtained is according to the temperature range from in the reactor at 478 K to 523 K. This is because the production of methanol is conducted in total of five runs at different temperature and flow rate. Therefore, the reaction constant is different in each run. Meanwhile for the residence time distribution, the RTD that is obtained from this production is 10.09378 h-1 or 0.1683 min-1 which means the time taken for the reactant to reside on the reactor is at that value. For the obtaining the value of activation energy for this production of methanol, since the temperature is already obtained for each run, the data of temperatures and the data of reaction constant, k is been is used to plot the graph of ln k against 1/T in order to obtained the value of ln A which is the intercept from the equation of straight line obtained from the graph. The value of ln A obtained based on the equation :y = 0.0288x + 3.6087Thus, the value is 3.6087. The value then is substitute into the equation to find the activation energy of this production. The value of activation energy obtained from this production of methanol is -1704.81 J/mol. The activation energy for this production is in negative value since the production is an exothermic reaction.

5.0 CONCLUSIONBased on this production of methanol, it can be concluded that this production is exothermic reaction. The production of methanol is conducted in one step reforming in the boiling water reactor (BWR) where the data for this production is taken for five run at the range of temperatures from 478 K to 523 K. The reason data is taken for five run with different temperatures, pressures, reaction constant and flow rate is one of the way in order to find the value of reaction kinetics in the production of methanol. The limiting of reactant for this production is hydrogen, H2 meanwhile the excess reactant is carbon dioxide, CO2. The volume of reactor gain is 4662.42 L. The activation energy and the residence time distribution (RTD) gained from this production based on the datas and calculation are -1704.81 J/mol and 10.09378 h-1 or 0.1683 min-1 respectively. Apart from that, with the value of molar flow rate for inlet and outlet, the value of concentration is also been determined.

6.0 REFERENCESFrom journal:1. Trondheim, Theopilus. A, (June, 2010), Control Structure Design for Methanol Process, Faculty of Natural Sciences and Technology Department of Chemical Engineering, Norwegian University of Science and Technology.2. Daaniya Rahman, (2012), Kinetic Modeling Of Methanol Synthesis From Carbon Monoxide, Carbon Dioxide, And Hydrogen Over A Cu/ZnO/Cr2O3 Catalyst, San Jose State University.3. Sivashunmugam Sankarnarayanan and Kannan Srinivasan, (July 12, 2012), Carbon dioxide-A potential raw material for the production of fuel, fuel additives and bio-derived chemicals, CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar, India.4. Petersen. K.A., Nielsen. C.S., Dybkjr. I., and Perregaard. J., (nd), Large Scale Methanol Production from Natural Gas, Haldor Topsoe.From books:1. Sungyu Lee, (1990), Methanol Synthesis Technology, CRC Press. 2. Harold Kung and Wu-Hsun Cheng, (1994), Methanol Production and Use, Marcel DekkerFrom website:1. Jiang C.J., Trimm D.L., Wainwright M.S. (1993). Kinetic mechanism for the reaction between methanol and water over a Cu-ZnO-Al2O3 catalyst. Retrieved from http://www.sciencedirect.com/science/article/pii/0926860X9380081Z 2. Bowker, M,. Houghton, H,. and Kenneth,W.C,. (1991). Mechanism and kinetics of methanol synthesis on zinc oxide. Retrieved from http://pubs.rsc.org/en/content/articlelanding/1981/f1/f19817703023#!divAbstract

7.0 APPENDICES

16