*** JUST ANSWER QUESTION 8 ***

Purpose: To construct a process flow simulator for the material balances of an entire (simplified) chemical plant. Description: Methanol (CH 3 OH) is synthesized in a two-step process. First, steam and methane (CH 4 ) react in the steam reforming reactor (SRR) to produce a product called syngas. It is a mixture of H 2 and CO with a byproduct of CO 2 and unreacted H 2 O and CH 4 . This method is the most common process industrially to produce large quantities of hydrogen. The water is removed from the SRR outlet in a series of condensers and the remaining syngas is then fed into a reactor-separator process to produce methanol in the methanol synthesis reactor (MSR). The outlet of the MSR is fed to a flash separator to remove water and methanol while the unreacted gases (H 2 , CO, CO 2 ) are partially purged and then recycled back into the feed to the MSR. Finally, the water and methanol removed by the flash separator are fed into distillation columns to produce the final product. Additional details on the process are found in the question descriptions below and in the attached process flow diagrams. Method: You will work alone to solve a series of inter-connected problems, all relating to the same chemical process. You are required to set up/solve all calculations using computer tools. Problems that are connected to the complete process balance are marked with *. The other problems are side quests that provide additional understanding of the process, but do not modify the process flow rates. Please complete the following problems: 1. The methanol synthesis plant will produce 4.3x10 5 metric tons of methanol per year and will operate 350 days per year (24 hrs/day when operating). Assuming 100% efficient conversion of the methane feedstock to methanol, what is the required feed rate of methane (in SCMH) and steam (in kg/h)? 2. Natural gas is also used to fuel the burners to provide heat for the Steam Reformer Reactor (SRR). Five percent excess air at 1 atm pressure is fed at a temperature of 30 C and 70% relative humidity. a. What is the average molecular weight of the air? b. Why does the average molecular weight of the humid air differ from that of dry air? c. What is the flow rate of air (in kmol and m 3 ) into the burners per kmol of methane burnt? 3. Assuming a basis of 1 kmol/hr of methane fed to the burners to provide heat to the SRR, answer the following questions: a. What is the flow rate of each species (in kmol/hr) in the effluent stream leaving the burners? The same process conditions apply in this problem as in #2 (e.g., humidity and temperature). b. What is the volumetric flow rate of the effluent streams out of the burners and into the stack (in m 3 /hr)? c. What is the specific gravity of the gas (density/air density) that travels into the stack relative to the ambient air (30 C, 70% R.H.)? Why does this parameter matter when deciding what temperature to expel the stack gas? 4. *Methane is fed to the SRR at a rate of 1600 kmol/hr, and steam is fed at a ratio of 3:1 to methane. Assume that the SRR progresses to its equilibrium composition. Both the SRR and WGS reactions are occurring simultaneously at a temperature of 855 C and pressure of 1.6 MPa inside the reactor. a. *Determine the flow rates of the outlet stream of the SRR for the base case 3:1 ratio of steam to methane. Report these flow rates into the material balance summary table in the template. Additionally, report the extents of reaction for the steam reforming reaction and water gas shift reaction. b. Resolve part (a) but for the following steam to methane ratios: 1:1, 2:1, 3:1, and 4:1. Plot the flow rates of CO and H 2 (in kmol/hr) as a function of the steam to methane ratio to summarize your results. 5. *Assume that CO, CO 2 , H 2 , and CH 4 are insoluble in water: a. What is the dew-point temperature of the product stream from the SRR at 1.6 MPa? b. If this stream is cooled to 35 C at a pressure of 1.6 MPa, what is the rate of water removal (kg/h) c. *Report the flow rates of the stream exiting the condensers with the water partially removed into the material balance summary. 6. For this problem, assume that there is no reactor-separator loop for the MSR. a. What are molar flow rates out of the MSR assuming equilibrium conversion at 250 C and 7.5 MPa? Consider both the MSR and WGS shift reactions occurring simultaneously. b. What are the CO and H 2 conversions at equilibrium? 7. *For this problem, you will balance the MSR reactor-separator loop using the outlet of the condensers (#5c) flow rates as the feed to the process. Assume single-pass conversions of 15% and 10% for CO and CO 2 ? The flash separator perfectly isolates the gasses (CO, CO 2 , CH 4 ) from the condensable components (CH 3 OH, H 2 O). The recycle ratio is 6.8 (so 1 part fresh feed to 6.8 parts of recycled material based on the total flow rates of these streams on a molar basis, but you wont necessarily know the composition yet!). This recycle ratio results in a feed of 7.8 times the fresh feed to the MSR process as listed in the process flow diagram. The use of a tear stream will aid in balancing this process. Report the flow rates of the liquids produced in the process and the purge stream.

8. *The liquids produced in the MSR reactor-separator loop enter a distillation column to recover 95% of the methanol in a top stream that is 99.85 wt.% methanol. a. *What are the flow rates of the top and bottom stream components in kmol/hr? b. What is the annual production rate of methanol (following the production schedule set in #1) and what percent of the specified 4.3x10 5 metric tons of production was obtained?

*** JUST ANSWER QUESTION 8 ***