Graphite Electrodes Production and Optimization Practices

Graphite Electrodes Production and Optimization Practices Graphite electrodes are used in both DC and AC electric arc furnaces. Companies who use electric arc furnaces have to cover the cost of these consumable electrodes during production, so optimizing the usage of graphite electrodes is a money-saving opportunity. This paper aims to discuss the production process of graphite electrodes as well as industry practices that are used to enhance the life of electrodes. To produce a graphite electrode, carbon is required. The carbon source for graphite electrodes comes from the petroleum industry as a by-product from the oil refining process. In the refining of crude oil, hydrocarbon chains are cracked in coking units and the resulting fuels are then separated as kerosene, gasoline, and diesel. As chains of hydrocarbons are being cracked in this process, pure carbon becomes deposited on the sidewalls of the coking units. The carbon on the sidewalls accumulates up to a certain point when it is the ground out of the unit. This carbon is called petroleum coke, or petcoke. This is the carbon source for graphite electrodes. After the petcoke is obtained from the oil refinery, it is blended with pitch to make a plastic-like material. (Making a UCAR ® Graphite Electrode) This blend of petcoke and pitch is then extruded through a circular die and cut off in sections. It is then baked at a temperature of above 800 degrees Celsius for a period of one to two weeks. After baking, the electrode is impregnated with more pitch to increase the density of the electrode which lowers electrical resistance and makes it stronger. The electrode is then re-baked at a slightly lower temperature to drive off volatiles found in the pitch. Finally, the electrode is heated to a temperature of about 3000 degrees Celsius to recrystallize the carbon into graphite. This final heating is called graphitization. Graphitization is very important in electrode manufacturing because it provides better mechanical strength and also improves electrical conductivity. The final step in electrode production is machining. The electrodes are machined to specific tolerances. This is especially important at the ends of the electrodes where the joints connect. (D. Klein) A good connection between joints is necessary for mechanical and electrical properties of the electrode. Electrode consumption takes on two forms: Continuous consumption and discontinuous consumption. (Richard J. Fruehan) Continuous consumption contributes 90% of total electrode consumption while discontinuous consumption only accounts for 10%. Even though discontinuous consumption accounts for far less than continuous consumption, discontinuous consumption can also account for furnace downtime which can cost a lot of money. So even though it is a small percentage, it is worthwhile to try to prevent it for the sake of productivity. In continuous consumption, the tip and sidewalls oxidize and the mass of the electrode is reduced. Tip consumption is a function of current and angle. Higher currents and steeper tip angles both yield faster oxidation rates of electrodes. (A. Lefort) Higher currents increase the temperature of the electrode which favors a faster oxidation rate. The steeper the tip angle, the closer the electrode needs to be to the steel bath to arc. Steel is more likely to splash onto the electrode if it is closer to the bath. One way to reduce the oxidation rate of electrodes is to cool them. Water cooled electrodes have been shown to reduce the oxidation rate of the sidewalls by 40% and the tip by 50%. One issue with water cooled electrodes is the flow rate of the water. If the flow rate is too high, water will pour into the furnace and increase the heat loss. The loss of heat can end up costing more than the money saved from reducing electrode consumption, so this is an important factor to conside r in this process. In discontinuous consumption, one of the most obvious techniques to prevent electrode breakage is simply to not ram the electrodes into the steel scrap. Graphite is a soft, brittle material and steel scrap is pretty hard and durable. If these two materials come head-to-head, the steel wins. Another method of discontinuous consumption is tip spalling. (A. Lefrank) This is more prevalent in DC furnaces than in AC furnaces because the DC electrodes see higher temperatures and therefore higher thermal stresses. The temperature gradient can be significant in the tip of a DC electrode and the thermal expansion of graphite can cause enough stress on the tip to break off small pieces. (J. E. Surma) Normally, the arc in a DC furnace will move about randomly, but occasionally the arc will sit in one spot, heating up that portion of the electrode tip creating thermal stresses that cause the tip to spall. Arc deflection control is a practice that has been implemented so when the arc becomes fixa ted on one spot, it will essentially â€Å"push† the arc out from that spot to get it to move about in a random fashion once more. Another practice to prevent the discontinuous consumption of electrodes is to ensure proper torque is applied when installing new electrode segments. The vibrations from the furnace and electromagnetic forces due to the flow of electricity give electrodes a good shaking. This can jostle the segments loose from their joints. This is mainly a problem in DC furnaces because AC furnaces are designed to ensure that the electromagnetic forces work to their advantage. In AC furnaces, the phase sequence is counterclockwise, so the forces on the electrodes due to the electromagnetism of the system only ever tightens the electrode joints. Below is a chart of recommended torque according to electrode diameter from SGL Carbons website and an AC furnace schematic of forces due to phase sequence. One final practice that helps prevent the failure of electrode joints is to turn off the water spray for a few minutes after the addition of another electrode segment. (Richard J. Fruehan) The temperature gradient is much steeper when the water spray operation is active. This thermal gradient can cause a problem when it reaches the joint because of the thermal expansion of graphite. Even if the electrode was tightened with the proper amount of torque, the effects of temperature on the electrode joint is enough to loosen it. This coupled with the furnace vibrations could be enough to cause the electrode joint to fail. In conclusion, graphite electrodes are an essential part of electric arc furnace steelmaking. Since they are consumable, any way to improve the life and efficiency of an electrode saves money in the steelmaking industry. Practices such as water cooling electrodes and optimizing current and tip angle are effective ways of reducing the oxidation of electrodes while taking care not to impact the scrap during melting, ensuring proper torque during installation, and turning off the water spray while adding another segment all help reduce breakage and joint failure. Works Cited: A. Lefort, M. J. Parizet, S. E. El-Fassi and M. Abbaoui. Erosion of Graphite Electrodes. J. Phys. D: Appl. Phys. 26 (1993): 1239-1243. A. Lefrank, W. J. Jones, and R. G. Wetter. DC Steelmaking Conditions and Electrode Performance. Electric Furnace Conference Proceedings 53. Warrendale: Iron and Steel Society, 1995. 337-346. D. Klein, K. Wimmer. DC Electrodes A Key Factor for Progress in EAF Production. Metallurgical Plant and Technology International 18:4 (1995): 54-63. Graphite and Carbon Electrodes. 6 December 2009 . J. E. Surma, D. R. Cohn, D. L. Smatlak, P. Thomas, P. P. Woskov, C. H. Titus, J. K. Wittle, R. A. Hamilton. Graphite Electrode DC Arc Technology Development for Treatment of Buried Wastes. Waste Management 93 Symposia. Tuscon, 1993. Making a UCAR ® Graphite Electrode. 2007. 6 December 2009 . Richard J. Fruehan, Ph.D. The Making, Shaping and Treating of Steel 11th Edition. Richard J. Fruehan, Ph.D. The Making, Shaping and Treating of Steel 11th Edition. Pittsburgh: The AISE Steel Foundation, 1998. 562-574.

Therapeutic Diet Teaching Plan: Gluten Free Diet

Celiac disease is a genetic disease which affects almost one percent of the U. S. population. Surprisingly enough, almost 95% of people with celiac disease are either misdiagnosed or undiagnosed. Having celiac disease means that one’s immune system is attacking any gluten that has been ingested causing damage to the small intestine. The damage done to the small intestine will prevent absorption of necessary vitamins, minerals, and other nutrients. The only way to treat celiac disease is by removing all gluten from one’s diet. Celiac disease can be difficult to diagnose.The symptoms are generally gas, bloating, diarrhea, weight loss, and fatigue. Many people suffering from these symptoms tend to self-prescribe solutions such as Pepto-Bismol or other such remedies for common indigestion. The only way to get an accurate diagnosis is from an antibody test done via a simple blood test. If necessary, a small intestine biopsy can be performed as well to provide a more concrete confirmation of the presence of the disease. The unfortunate reality is that there is no pharmaceutical treatment available. The only solution is to go â€Å"gluten-fee. Once gluten has been consumed, the individual will have to live with the consequences until the body has been able to rid itself of the gluten. Although the symptoms might seem bearable enough to continue consuming gluten products, there are a number of serious side effects to that decision. A person afflicted with celiac disease that goes untreated will likely suffer from infertility, some cancers, and most definitely malnutrition. Caring for a newly diagnosed celiac patient requires educating that patient on a number of topics. The first topic being that celiac disease is not short term.It will require a lifelong lifestyle change that can be difficult for a number of people. Also, as celiac can be asymptomatic and is genetic in nature, relatives (if not already) should also be tested for the disease. Once the in itial shock has been allowed to sink in, presentation of diet options need to be completed as treatment should begin as immediately as possible. It is important to know what â€Å"gluten† is. Gluten is found in wheat, rye, and barley. Any food item containing any of the previously listed items will no longer be consumable for a patient with celiac. Gluten â€Å"hides† in all sorts of different food items.Reading labels will have to become a part of the grocery shopping experience. Even foods like chicken, which might carry the assumption of being gluten free, have to be purchased with caution as chickens are injected with wheat fillers to provide the meat with more flavor. It should not be assumed that packages claiming to be â€Å"gluten free† are. The only way to be sure is to read the label and note the ingredients. Also, food items that are processed on equipment which also handle wheat items should be eaten with caution. The most obvious attack to a celiac diet is that on the carbohydrate food group.Seemingly all bread items are no longer available including but not limited to: pizza, bagels, bread, pasta, and cakes. However, the good news is that with the rise in population of those afflicted with celiac, breads and other such carbohydrate products are being made with flaxseed and/ or brown rice. Instead of focusing on finding foods with a wheat base, one can look for breads made with rice, corn, potatoes, soybeans, or tapioca. Although eating foods from the dairy group can be troublesome when immediately beginning treatment for celiac, these foods can be added back into the diet after a few weeks.It is okay to eventually eat cheese and milk. Most ice creams will need to be avoided as they most likely will contain gluten, especially those sporting fancy added toppings such as Oreos and/or cookie dough. There are a few other food items to take into consideration when planning gluten free meals. Processed and breaded meats along with b readed vegetables need to be avoided. Most canned soups, salad dressings, and soy sauce will contain gluten. Sadly, the vast majority of desserts will no longer be able to be enjoyed.Although, one can now find on the shelves of some grocery stores boxed mixes for items such as brownies and cookies. Of course, being a product of wheat and barley, beer is also no longer consumable. The gluten free diet will take getting used to. It can be extremely difficult to give up foods (pizza, for example) that have become personal favorites. It can be made even more frustrating by the fact that symptoms generally take several weeks to go away. However, once the symptoms are gone, the freedom from pain and discomfort will bring much more happiness than a piece of toast.

Purchasing Essay Topics on 1960s

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Western Michigan University Acceptance Rate, SAT/ACT Scores, GPA

Western Michigan University is a public research university with an acceptance rate of 81%. Located in Kalamazoo, Michigan, WMU is part of the Michigan Association of State Universities. Business and health fields are the most popular undergraduate majors, but for its strengths in the liberal arts and sciences, Western Michigan University was awarded a chapter of the prestigious Phi Beta Kappa Honor Society. Academically talented students might consider joining the Lee Honors College. In athletics, the WMU Broncos compete in the NCAA Division I Mid-American Conference (MAC). Considering applying to Western Michigan University? Here are the admissions statistics you should know, including average SAT/ACT scores and GPAs of admitted students. Acceptance Rate During the 2017-18 admissions cycle, Western Michigan University had an acceptance rate of 81%. This means that for every 100 students who applied, 81 students were admitted, making WMUs admissions process somewhat competitive. Admissions Statistics (2017-18) Number of Applicants 17,051 Percent Admitted 81% Percent Admitted Who Enrolled (Yield) 22% SAT Scores and Requirements Western Michigan University requires that all applicants submit either SAT or ACT scores. During the 2017-18 admissions cycle, 82% of admitted students submitted SAT scores. SAT Range (Admitted Students) Section 25th Percentile 75th Percentile ERW 500 600 Math 490 590 ERW-Evidence-Based Reading and Writing This admissions data tells us that most of Western Michigans admitted students fall within the  bottom 29% nationally  on the SAT. For the evidence-based reading and writing section, 50% of students admitted to Western Michigan scored between 500 and 600, while 25% scored below 500 and 25% scored above 600. On the math section, 50% of admitted students scored between 490 and 590, while 25% scored below 490 and 25% scored above 590. Applicants with a composite SAT score of 1190 or higher will have particularly competitive chances at WMU. Requirements Western Michigan University does not require the SAT writing section or SAT Subject tests. Note that Western Michigan participates in the scorechoice program, which means that the admissions office will consider your highest score from each individual section across all SAT test dates. ACT Scores and Requirements WMU requires that all applicants submit either SAT or ACT scores. During the 2017-18 admissions cycle, 33% of admitted students submitted ACT scores. ACT Range (Admitted Students) Section 25th Percentile 75th Percentile English 20 25 Math 18 26 Composite 20 26 This admissions data tells us that most of Western Michigans admitted students fall within the  top 48% nationally  on the ACT. The middle 50% of students admitted to WMU received a composite ACT score between 20 and 26, while 25% scored above 26 and 25% scored below 20. Requirements WMU does not require the optional ACT writing section. Note that Western Michigan superscores ACT results; your highest subscores from multiple ACT sittings will be considered. GPA In 2018, the average high school GPA of Western Michigan Universitys incoming freshmen class was 3.4, and over 44% of incoming students had average GPAs of 3.5 and above. These results suggest that most successful applicants to WMU have primarily high B grades. Admissions Chances Western Michigan University, which accepts more than three-quarters of applicants, has a somewhat selective admissions process. If your SAT/ACT scores and GPA fall within the schools average range, you have a strong chance of being accepted. However, Western Michigan also uses a  holistic admission  approach that considers academic achievement in  rigorous coursework, strength of high school program, and trends in grades. Potential applicants should have a minimum of four years of English; three years of math; three years of natural science (including 2 with lab component), and two years of the same foreign language. WMU is also interested in learning about you and your interests outside of the classroom. Be sure to include information regarding  extracurricular and leadership activities and employment in your application. Students with particularly compelling stories or achievements can still receive serious consideration even if their grades and test scores are outside Western Michigans average range. Find out how you compare to accepted students, see the real-time graph, and calculate your chances of getting in with a free Cappex account. If You Like Western Michigan University, You May Also Like These Schools Central Michigan UniversityBowling Green State UniversityPurdue UniversityBall State UniversityOhio State University All admissions data has been sourced from the National Center for Education Statistics and Western Michigan University Undergraduate Admissions Office.