Reverse Osmosis and Maple…Syrup that is

August 16 2005 Nina 72
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As a chemical engineer working for Maplesoft, I thought it would be nice to highlight Maple’s broad capabilities in solving simple and complex problems as related to my specific expertise. Living in the Waterloo Region my whole life has been a privilege. I grew up with an excellent tradition of Santa Claus Parades in the winter, Oktoberfest in the fall, the Greek Food Festival in the summer and the Elmira Maple Syrup Festival in the spring. What a magical place to live! As a young child in elementary school, we would take frequent trips to the local sugarbush and get ‘schooled’ in the art of maple syrup production…the old world way with multiple boilers and big, clumsy mixers. Of course, maple syrup production has come along way since the good ol’ days. You might be surprised to hear that today, many major manufacturing facilities use complicated, multi-stage filtration processes and reverse osmosis equipment to produce maple syrup. Reverse Osmosis is traditionally used for the desalination of salt water, but when applied to the process of maple syrup production, reverse osmosis is the process in which the water content of maple sap is reduced. This is done by forcing sap under pressure across membranes that contain pores just small enough that they restrict the passage of sugar and large molecules, but large enough to pass water molecules. These are referred to as semipermeable membranes. Transport phenomena govern this process, which ultimately concentrates the sap to produce this sweet nectar. Sounds a little more complicated than the traditional method still used in the sugarbush I used to visit as a child, but it actually uses less energy. Reverse osmosis removes a substantial portion of the water from the sap, before it enters the evaporator, thereby reducing evaporator fuel costs and boiling time. One particularly important aspect of reverse osmosis is the determination of the concentration of permeate and product (concentrate) streams. Normally, when a particular semipermeable membrane is used, a calibration curve is generated to aid in the determination of the concentration of a desired stream. Since many concentration determination methods are quite costly and time consuming, a relatively simple metric is chosen, and a relationship between this metric and the concentration is developed and plotted against each other in order to determine the concentration of a particular sample, without actually measuring it. When desalinating water, conductivity is the measured variable plotted versus concentration, as conductivity readings are very simple to obtain. For maple syrup production, the measured variable commonly used is the refractive index of the syrup. The refractive index is determined using a refractometer. Each refractometer reading corresponds to a given sugar concentration. These values are specially calibrated for maple syrup. By determining the refractive index of the syrup, you can determine what the percentage of sugar is in the syrup. The proper calibration of such instruments is integral to the accurate determination of concentration. Maple syrup in particular must be at a very specific concentration to prevent it from crystallizing in your cupboard before you get a chance to empty the bottle. I have included a Maple 10 document that takes in a data set, calculates a calibration curve, and plots it with respect to the desired parameter. I have also provided a sample of data for the calibration of a refractometer for the measurement of sugar content in a solution. I am working on modeling the actual production process using Maple 10 as well. Stay tuned… Here is the worksheet referred to in the post: View 1_CalibrationCurve.mw on MapleNet or Download 1_CalibrationCurve.mw
View file details And the data file: Download 1_RIvsBRIX.txt
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