| Done any remodeling lately? If you have, you’ve been faced with countless choices regarding design and materials. Even a relatively simple decision such as putting in hardwood flooring requires many considerations. What type of wood? What grade? How about the stain? Should it be factory stained and sealed, or should the flooring be installed by single board, then stained and sealed in place? Ultimately, your decision is based on your requirements with regards to cost, durability, and personal style.
Now imagine the decision making process that is required to produce a medical device. We’ve been discussing this complex process during our series on medical device design utilizing the systems engineering approach, a systemized approach to product development, design, and manufacture that is used within many manufacturing arenas. Its objective is to relate the requirements for manufacture, regulatory compliance, sale, use, and maintenance of the product to specific design criteria for functionality, durability, and safety. By doing so, the systems engineering approach ensures that the product meets or exceeds all requirements. Last time we wrapped up our discussion on the Development stage of systems engineering by discussing field testing of medical devices assembled during Preproduction. Problems encountered during this phase result in a comprehensive review of the device design and instructions. When all issues have been resolved, things move on to the manufacturing phase and full commercial production. During the Production stage, engineers make continual assessments of the manufacturing process and ongoing adjustments are made to the device design and manufacturing protocol as necessary, this due primarily to changing stakeholder requirements regarding cost reduction. In the competitive marketplace, cost reduction is a never-ending quest to maintain profitability in view of changing economic and market conditions, and this must be done without compromising the quality, safety, and effectiveness of the device. For example, suppose a medical diagnostic imaging machine was designed to be fitted with a machined metal gear in one of its mechanisms. The manufacturer specifies that a $10 decrease must be made in production costs so it can continue to be sold at an acceptable profit margin. After reviewing the design, engineers discover that substitution of a molded plastic gear would reduce manufacturing cost per machine by $12. This is a common scenario, as plastic parts are often substituted for metal to save on cost. Plastic versus metal? How can that be an acceptable swap? In many cases, it can be. Mechanical stressors are analyzed, and if the plastic gears meet durability requirements as well as their metal counterpart, they are substituted. During the Preproduction phase these plastic gears are used in both lab and field testing, where they are put through the rigors of real world use. If they perform acceptably, they are made a permanent part of the device’s design and used in commercial production. Next time we’ll continue our look at the Production stage to discover another way that systems engineering can facilitate cost reduction to meet stakeholder requirements. ___________________________________________
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Posts Tagged ‘regulatory compliance’
Coal Power Plant Fundamentals
Sunday, January 23rd, 2011| Several years ago I was asked by power producers within the electric utility industry to write and then present a training course on the subject of coal power plant fundamentals. The finished product was a two day introductory course on the energy transformation process within a coal fired plant.
Since that time my seminar, entitled Coal Power Plant Fundamentals, has been presented to a variety of audiences, including Mirant Corporation, Platte River Power Authority, and Integrys Energy Group, Inc. Audience makeup has been diverse and has included equipment manufacturers, mining companies, power industry consultants, and regulatory agencies. This seminar, which I continue to present today in meeting rooms across the country, covers all major systems in a typical power plant, from coal handling when the coal first enters the plant, to its eventual end destination, the electrical switch yard which facilitates power transmission to customers. My Power Point presentation is embellished with ample illustrations, including photographs that I have taken during the course of my career and diagrams which I created using CAD, or Computer Aided Drawing software, one of which is featured below. In addition to the overhead slides, I provide a 150-page bound book which is distributed to seminar attendees. They use it to both follow along with my lecture and have a source of refresher material to take home with them. I’ve been told that having my illustrations in front of them makes a world of difference towards their understanding of the subject matter. The unique thing about my course is that it focuses on the simplified presentation of complex engineering concepts, much like my blogs do. Of course it always helps to have an engineering background or scientific background of sorts, but I wrote the course to accommodate understanding of the subject matter by individuals without any technical background. Accountants, salespersons, administrative staff, plant operating and maintenance workers, and journalists have all found the course to be easy to follow, interesting, and informative. So how do you get electricity from coal? To answer this question and give you a sampling of my seminar material let’s take a look at Figure 1.
Figure 1 – The Coal Power Plant Energy Transformation Process Following along from left to right, the coal is first burned in order to transform the chemical energy which it contains into heat energy. That heat energy is then absorbed by water inside a nearby boiler, where it is converted into steam. The heat energy in the steam flows through a pipe into a steam turbine where it is again transformed, this time into mechanical energy that enables the turbine shaft to spin. The mechanical energy in the turbine is then transmitted by its shaft, enabling it to turn an electrical generator. And, finally, the mechanical energy is transformed by the generator into electrical energy for our usage. Simple process, right? Well, maybe, maybe not. My illustration certainly helped to simplify things, but there are a lot of details that were purposely omitted so as not to “muddy the waters.” It’s those details which have the potential to make things a lot more complicated, and next week we’ll begin to take a closer look at some of them. _____________________________________________
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Fossil Fuel, From Friend to Foe
Sunday, June 27th, 2010|
Did you ever have someone you considered to be a great friend and then things suddenly went bad between you? One day you’re chums and then the magic fades, soon to disappear? Sound like some marriages you’ve heard about? Well, it wasn’t too long ago that coal was considered to be America’s affordable answer to our fuel needs. It was a friend of grand proportions, there when you needed it. It remains an abundant resource, so abundant in fact that according to the US Energy Information Administration (EIA) we are sitting on coal reserves so vast they can provide us with sufficient energy to get us through the next 250 years at current rates of consumption. It was for these reasons that electric utilities decided decades ago to use coal as the primary source of fuel to generate electricity, and as it stands now just over 50% of our electrical energy is generated by burning coal. So how did coal go from being friend to foe? Well, just as when you’ve known someone for awhile their “baggage” becomes more apparent, it eventually became apparent to Americans that burning coal comes with some nasty baggage of its own, known as byproducts. These unwelcome components of the burning/oxidation process were found in the plumes of smoke that billowed out of power plants’ smokestacks. So just what are these byproducts? Well, some of it is the same stuff that’s left over at the bottom of your barbecue grille after a cookout, and some of it comes with scientific names like sulfur dioxide (SO2), nitric oxide (NO), and nitrous oxide (N2O). Let’s look at these in more detail. Ash is the residue that’s left behind after coal is burned. Fly ash is a type of ash that is made up of some very light particles and it can get carried away by the hot gases coming off the fire in a power plant boiler. Some of those particles manage to leave the smokestack and enter the environment. Sulfur dioxide, or SO2, is formed when the sulfur in coal combines with oxygen in the air during burning. When the SO2 leaves the smokestack, it can combine with moisture in the atmosphere to form acid rain. Most of us know what acid rain is, but for those that don’t, acid rain does things like rust metal, dissolve marble monuments, and in general disrupt the balance of Earth’s eco systems. Nitric oxide, NO, and nitrous oxide, N2O, are chemical compounds composed of nitrogen and oxygen that fall into the group commonly referred to as NOx, pronounced “knocks.” NOx is formed when nitrogen and oxygen in the air combine at the high temperatures released when coal is burned inside power plant furnaces. NOx is bad because its compounds are key ingredients in the formation of both acid rain and smog. Over the last thirty years emissions of these byproducts have come under increasing scrutiny by federal and state regulators in their quest to curb them and their impact on our environment. As a result, electric utilities have had to comply with ever-tightening regulations. To comply, coals with lower sulfur content have been used, often brought in over very long distances from mines in the US and even foreign countries like Columbia. Utilities have also been installing expensive pollution control equipment in their coal fired power plants. But these changes make operations more expensive, eating into the utilities’ profits. Now we may not like the idea of utilities earning a profit, but this is a necessary reality to some extent in order to keep their business solvent. They’re not in it for the fun of it, after all. And I’m sure you guessed by now that the net result of the regulatory agencies’ mandates is that our electric bills just keep escalating. Now much of what lies behind the current unfavorable status of coal powered plants is that when operating on our native soil they have high visibility. We don’t like to be reminded of the negatives that accompany the production of energy. Put that same plant in another faraway country and the byproducts cease to be an issue. It’s happening over there after all, and we don’t have to be confronted with it. We neglect to remind ourselves that the earth’s atmosphere is for the most part a contained unit, and that means that what happens there is happening here, whether there happens to be on the other side of the globe or not. Next week we’ll continue our explorations into coal, examining the impact of the low sulfur variety on electric utility power generation. _____________________________________________
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