Bacteria Generated Fuel
Paper, Order, or Assignment Requirements
Lab Objective
Through this lab exercise, the principle of mass conservation will be demonstrated using an adopted problem-solving methodology and a simple Matlab exercise.
Material
• Matlab 2007 or higher
Lab Assignment
Problem Statement
Research is being done to utilize microbial cells found in common soil or the ocean floor to produce usable fuels, such as propane, from CO2 that has been sequestered from flue gases from power plants (a major source of CO2 emissions). The challenge here to make the process useful is to be able to produce large quantities of propane from these cells at a reasonable cost. In a first attempt to this, a company (GASBUGS INC.) attempts to mass produce propane by employing a simple continuously stirred tank reactor (CSTR). GASBUGS INC. found that keeping the reactor at 25 oC provides conditions in the reactor where the rate of death and growth of cells are equal. On a molar basis, when CO2 (density = 0.00197 g/cm3) is bubbled into the reactor at a flow rate of 1680 L/hr., complete conversion to propane is achieved in 10% excess of water, and no bacteria are lost in the output flow stream.
It is your goal as the production engineering support specialist working for GASBUGS INC. to model this scenario to determine how much feed water is required in mol/hr. and what the daily output of propane is.
Procedure
• Using MATLAB, create a plot that demonstrates/illustrates the impact on propane production as the CO2 gas flow rate is varied from 50% to 200% of the modeled flow rate.
Questions
(1) Is the concentration of the propane higher or lower in the reactor vessel or the product stream? Explain.
(2) What happens to propane production as CO2 flow rate is increased? Explain.
Write a brief technical lab report summarizing the technical facts learned from this lab. The report should be organized to provide the following:
1. Section 1–Introduction: An introductory/summary paragraph describing the type of conservation principle being analyzed and the key elements that will be discussed relating to this principle.
2. Section 2–Lab Results: Includes any diagrams, models, simulations, data summaries, and answers to lab questions.
3. Section 3–Discussion: A section describing the most important characteristics shown or demonstrated via the modeled and collected data. Also include a practical example of how the information learned in this project might help you in operating, troubleshooting, error analysis, or adjusting a system using fuel cells in your home setting, in your training program setting, or in a job setting in the real world.
4. Section 4–Concluding Remarks: A summary statement listing the most positive aspects of the lab and any parts of the lab that were difficult because of equipment problems or unclear instructions. Include areas that might be improved.
HOMEWORK
e 3.27a Hollow-fiber membrane device.
3.5 Hollow-fiber membrane devices are used in a number of applications in bio-engineering and biochemical engineering. A typical unit consists of thousands of small hollow fiber tubes packed in a tubular device (Figure 3.27a). Components within the fibers can be isolated from components outside the fibers based on solubility and/or size restrictions. Some materials can easily diffuse across the membrane between the fibers to the annular space. In this problem, the hollow-fiber membrane device is modeled as an inner tube, representing the membrane fibers, and an outer tube, representing the outer (annular) space.
A hollow-fiber membrane device is operated to concentrate a bacterial suspension. The flow rate of cell suspension into the fibers is 350 kg/min. The inlet cell suspension is comprised of 1.0 wt% bacteria; the rest of the suspension can be considered water. An aqueous buffer solution enters the annular space at a flow rate of 80.0 kg/min. Because the cell suspension in the membrane tubes is under pressure, water is forced from the tubes, across the membrane, and into the buffer. Bacteria in the cell suspension are too large to pass through the membrane, and thus they remain in the membrane tubes throughout the device. The outlet cell suspension is comprised of 6.0 wt% bacteria. Assume that the cells do not grow. Also assume that the membrane does not allow any molecules other than water to pass across it. (Adapted from Doran PM, Bioprocessing Engineering Principles, 1999.)
(a) Determine the mass flow rates of the outlet cell suspension stream and the outlet buffer stream.
(b) Determine the mass flow rate of the water across the membrane.
(c) Determine the mass flow rate of the cells
3.9 Balance the following equations by solving for the appropriate unknowns. Using MATLAB may facilitate the solution to several parts of this problem.
(a) ZrCl4 + aH2O → pZrO2 + qHCl
(b) C6H12O6 + aNH3 + bO2 → pC5H9NO4 + qCO2 + rH2O, RQ = 0.45
(c) CH2O + aO2 + bNH3 → pCH1.8N0.2O0.75 + qH2O + rCO2, RQ = 0.30
(d) C2H5OH + aNa2Cr2O7 + bH2SO4 → pCH3COOH + qCr2(SO4)3 + rNa2SO4 + sH2O
(e) Aerobic (i.e., with O2) growth of S. cerevisiae (yeast) on ethanol. CH1.704N0.149O0.408 is the yeast/biomass.
C2H5OH + aO2 + bNH3 → pCH1.704N0.149O0.408 + qCO2 + rH2O, RQ = 0.66
(f) Anaerobic (i.e., without O2) growth of S. cerevisiae (yeast) on glucose. CH1.74N0.2O0.45 is the yeast/biomass.
C6H12O6 + aNH3 → 0.59 CH1.74N0.2O0.4
