Macroeconomics Essay Example | Topics and Well Written Essays - 750 words - 5

Macroeconomics - Essay Example US$1000 per month. Zan gained the required documents and was all set to leave for UAE in a month when his seniors’ opinion on going to UAE for job changed. That was December, 2008 and the global financial crisis had almost just started. His seniors told tragic tales. Many of them had themselves come back to Pakistan. Zan heard from his seniors that the construction companies in UAE were downsizing. Many employees were being fired without prior notification; companies were not following the legal procedure to downsize. The pressure on the regulatory authorities was so tremendous that the fired employees were not getting healthy response from them. The employees who were fortunate enough to survive were to take much greater load than before. As the companies had downsized, the survivors had also been assigned the responsibilities of the fired employees. To make it worse, they had their salaries reduced by a substantial percentage rather than getting them increased in compensation for more work. T he employers obliged them to work at lower salaries; else, they had the option to resign. Zan was very disappointed. He had spent months preparing for going to UAE but all had gone in vain. He decided to continue his job in Pakistan. He had thought before of leaving his company as it had been paying him very less, but now, that the rate of unemployment had gone very high because of the global financial crisis, leaving the company seemed a bad idea. One thing Zan knew for sure was that he needed to continue professional development. Pursing further studies seemed like a good way to achieve that. Therefore, he got admission in Masters course of Construction Management at a local engineering university in Pakistan. A major motivation behind getting admission in this course was to secure a scholarship for higher studies abroad. Since Pakistan is a developing country, where the opportunities of development

Samsung electronics Research Paper Example | Topics and Well Written Essays - 1000 words

Samsung electronics - Research Paper Example Notably, the company was founded in the year 1938 as a trading company. Samsung has since been manufacturing many electronic components. Some of these include lithium-ion, chips, hard drive, flash memory, and semiconductors for its major clients including Sony, Apple, Nokia, and HTC. However, in the recent years, Samsung electronics has since diversified its services into consumer electronics. Currently, Samsung is known as the largest mobile phones and smart phones manufacturer. This latest shift sparked the popularity of Samsung electronics’ Samsung Galaxy (Michell, 2011). Other than the phones, Samsung electronics is also a major tablet computers vendor particularly the Android powered Samsung Galaxy tab. Samsung also manufactures personal computers for commercial purposes. The figure below shows how the prices of the Samsung Galaxy smart phones, Samsung Galaxy tabs and Samsung personal computers have changed in the last two years (Russell and Cohn, 2012). Opportunity cost refers to an activity a firm can undertake as an alternative to its current line of business. For Samsung, two such examples include the motor vehicle industry and home furniture industry. Samsung is considered a firm that produces very high quality products. Consumers have trust in their products. If the firm was to start manufacturing motor vehicles, the same quality would be transferred. This good quality comes at an affordable price. This would mean that even the average consumer would buy a high quality vehicle at an affordable price (Russell and Cohn, 2012). The same case applies to the production of home furniture. Consumers would be willing to pay for getting good service. One scarcity issue faced by Samsung is the overwhelming demand for its products. In the year 2000, it had to issue licenses to various production companies worldwide to manufacture their products under their name. It is very possible to get a Samsung electronic device made in China and a

Direct Sales Approach to Selling Crude Oil in Kazakhstan Essay

Direct Sales Approach to Selling Crude Oil in Kazakhstan - Essay Example From this paper it is clear that  the main refineries in Kazakhstan are Pavlodar, Tyrau and Shymkent. Pavlodar and Shymkent process West Siberian Crude oil. These refineries are located around the oil fields to reduce transport costs. However, not all the oil from the fields is refined in the country. This is because the local refineries do not have sufficient capacity to process all the oil. Kazakhstan transports some of this oil to Russia through pipelines for processing.This essay discusses that the main buyer of Kazakhstan oil is Italy. That is according to a report by Kazakhstan’s Customs Control Committee. Apart from Italy, other consumers of Kazakh oil include China, the Netherlands, France and Austria. China has started investing in Kazakh oil with intentions of increasing its consumption of Kazakh oil. Though Russia refines Kazakh oil, it is not a major consumer of the oil. There are many challenges that companies selling crude oil face. That is due to the rules and regulations set by the authorities to govern the industry. Marketing of crude oil by private companies outside the country is limited. That is because the government allows only one company to do so. The company allowed to trade crude oil outside the country is KazMunayGas Trading AG. This is a subsidiary of the National Company KazMunayGas. The other companies remain only with the country’s refineries as their main customers for crude oil.

Professional Article Review Essay Example | Topics and Well Written Essays - 750 words

Professional Article Review - Essay Example The present study aims to investigate the long term impacts of MPH on ADHD affected children and comparative affect of academic intervention along with other covariates age, sex, IQ etc. The study involved 85 children with ADHD and within the age group of 5-12 years. Baseline assessments included Wide range achievement test-revised (WRAT-R), parent and teacher rating of ADHD symptoms and academic achievement, estimated intellectual ability, OCHS academic and psychosocial ratings, duration of medication and academic support. Post baseline assessments, children were randomly assigned to MPH treatment and placebo group in a double blind trial, the treatment group administered with a gradually rising dose of 5mg/administration to reach a target dose of 0.7mg/Kg body weight. Treatment was followed for 12 months keeping other conditions uniform, and the assessments done at baseline were repeated after the 12 month treatment period. Regression analysis was done to estimate academic performa nce one for each subset of WRAT-R and for parent and teacher ratings with baseline covariates and total treatments as variables. The results indicated that neither medication nor academic interventions could be attributed to significant improvement in academic performance compared to baseline values. Critical Evaluation Studies on ADHD lack evidences of mechanism of associations between academic underachievement and ADHD and stimulants have been recommended based on short term trials showing positive impacts on symptoms in general. However, the authors rightly claim that data for long term and cumulative impact of MPH is unavailable. The procedure followed by the authors is exhaustive involving baseline and post treatment assessments which are both subjective as well as objective. The explanations to the assessments, their design are either complete or are properly referenced, so as to enable repeatability. Both WISC-R and Ontario Child Health Scale (OCHS) are established clinical t ool for IQ assessment of children with learning disabilities and ADHD. Objective ratings make the results easy to conduct and results specific. Crossing over among children from the placebo and treatment groups was allowed but records were maintained. These records helped in estimating the total time of medication which represented cumulative effects of MPH, and the medication status at end of trial was indicative of the current effect. The continuation of additional interventions in form of academic support in addition to randomization of parents to training or self help group along with cross design, ensured that the trial were highly naturalistic. While allowing for naturalistic design lead to lack of control on some important variables however the same was partially overcome by use of multiple regression analysis. The nature of academic support provided to the children was one very important variable. Regression analysis used also helped to overcome the loss in numbers due to cr ossing over during the study. Disparities in the results for objective and subjective assessments indicate that the efficacy of MPH is based on prejudices and is overrated. The author claims that medication does not have

Analysis Assignment Example | Topics and Well Written Essays - 500 words - 2

Analysis - Assignment Example At one time, he addressed some of their concerns in terms of the remuneration that they got as a result of their works, while at another time; he compared them, especially the less intelligent ones with draft animals. Taylor argued that all tasks that an employee was assigned could be organised in such a way that the productivity of the worker would increase and that his scientific theory of management was more effective than the usual ‘initiative and incentive’ method, which was based on increasing productivity by placing responsibility on the worker to figure how to do it. In order to establish the best possible way to carry out a job, Taylor carried out some experiments, which he labelled time studies or as time and motion studies. In these studies, he used a stopwatch to time a worker’s motions in order to determine the most effective way to carry out a job based on the way that took the least time1. The chapter talks about the use of theory in public administration, all the past events have happened because of public administration; several theories regarding public administration have been brought forward, however, there are still others that have not been fully developed, these theories are classified as useful depending on their ability to describe, explain and predict matters regarding public administration. For a theory to be useful, it must have the ability to describe or to depict real life events with some level of thought, in these theories, there must be some explanations to some of the discrepancies in real life. In public administration, theory has been simply defined as a framework that, this definition of theory differs from other definition of theory in other sciences. In public administration, theories are classified depending on their degree, form the nature of its elaboration The author questions whether it is possible to have a useful and

Harriet Jacobs, Slavery, The South, and the Civil War Essay Example for Free

Harriet Jacobs, Slavery, The South, and the Civil War Essay Harriet Jacobs remains one of the most important anti-slavery figures in American history. As a former slave turned author, Jacobs was very influential in shaping public opinion towards an anti-slavery sentiment. Jacobs was born into slavery in 1813. She would eventually escape into freedom in 1835. Her escape route would eventually lead her to Philadelphia where she would not have to worry about being returned to the south. (Most northern cities were sympathetic to escaped slaves) Upon moving to New York City, Jacobs would develop a personal relationship with a publisher named Nathaniel Parker Willis. Perhaps it was this relationship that inspired her to write her seminal work Incidents in the Life of a Slave Girl. Incidents in the Life of a Slave Girl detailed the horrible conditions that women faced in slavery. The stories were first published in the newspaper the New York Tribune. While the articles were well received at first, the graphic depictions of sexual abuse proved controversial and the serial was discontinued. Eventually, Jacobs work was published in book form. The book became an immediate sensation and significantly shaped an anti-slavery sentiment that surely fueled the abolitionist movement. While the north understood slavery was evil, the pure brutality of it was unknown to most. Jacobs work raised a much needed awareness. But why did the south embrace slavery in the way it did? There were a number of reasons why the south was a huge proponent of slavery. The most obvious reason centers on the enormous profits that the southern states were able to amass due to having free labor. In time, the south was eventually overly reliant on  slavery since it was a non-industrialized society. Without the presence of factories, modern machinery, and an industrialized production center, the southern states were reliant on human labor more than the north. And as previously mentioned, free labor in the form of slavery provided the mechanism for this backwards infrastructure. There were many issues that drove the notion of the south succeeding from the union. If there was a â€Å"final straw† that drove the southern states to succeed from the union, it was the election of President Abraham Lincoln. Lincoln had campaigned on an anti-slavery platform. When he was elected, he professed his assertion that no new states entered into the union would be allowed to be slave states. This led to several southern states succeeding from the union and to form the Confederacy. Obviously, President Lincoln sought to quell this succession as soon as possible. However, the tensions exploded on April 12, 1861 when the Confederacy launched an all out assault on the military base Fort Sumter in South Carolina. More than anything else, this was the inciting incident that led to an all out Civil War.   During the initial years of the Civil War, the south was seriously â€Å"hammering† the north as the north could not find a proper strategy to win the war. This situation nearly led to Lincoln’s defeat in re-election. However, Lincoln did win re-election and eventually found the right general in Ulysses S. Grant. Under Grant, the south was defeated and the Emancipation Proclamation was upheld. Slavery was no more in the United States. In the aftermath of the Civil War, the reconstruction of the devastated south began. One goal of reconstruction was to integrate the now freed slaves into society.  However, Lincoln’s assassination undermined reconstruction and African-Americans would remain disenfranchised in the south for an additional 100 years.

Design Of A Sulfuric Acid Production Plant Engineering Essay

Design Of A Sulfuric Acid Production Plant Engineering Essay This project is prepared according to the requirements of chemical engineering department, and its also a preliminary study of sulfuric acid production plant. The project begins with chapter one which includes introduction, definition of sulfuric acid and shows the main uses of sulfuric acid which have made it an important chemical in the world, followed by chapter two which talks about literature, market survey and the history and current processes for production the sulfuric acid also it gives small glimpse of the prices trends of the raw material and product. That is followed by description for various processes to produce sulfuric acid in chapter three, which ends with the selection of the best process which is the double contact process; the description and flow sheet of the selected process are discussed in chapter four. Material and energy balance results are listed in chapter five and the location of the plant is selected in chapter six by comparing different locations, and the best location for the plant (as its set in this report) is Aqaba city. . Finally, material and energy balance details are discussed in the appendix, that includes the used charts and references. CHAPTER ONE INTRODUCTION 1.1 Definition Sulfuric acid is a strong mineral acid with the molecular formula H2SO4. It is a clear, colorless, odorless, viscous liquid that is very corrosive. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. There are another names for sulfuric acid, it is sometimes called oil of vitriol.1 Its chemical formula is Figure (1.1.1): Sulfuric Acid Formula1 1.2 Physical and Chemical properties This table shows the main chemical and physical properties of sulfuric acid Sulfuric acid IUPAC Oil of vitriol Other name H2O4S Molecular formula 98.08 g molà ¢Ã‹â€ Ã¢â‚¬â„¢1 Molar mass Clear, colorless, odorless liquid Appearances 1.84 g/cm3, liquid Density 10  Ã‚ °C, 283  K, 50  Ã‚ °F Melting point 337  Ã‚ °C, 610  K, 639  Ã‚ °F Boiling point Miscible Solubility in water à ¢Ã‹â€ Ã¢â‚¬â„¢3 Acidity(pka) pungent odor Odor Non-flammable Flash point 26.7 cP (20  °C) Viscosity 0.3 Ph Table (1.2.1): physical properties1 1.3 Application and Uses Sulfuric acid is a very important chemical commodity, and indeed, a nations sulfuric acid production is a good indicator of its industrial strength. It is used as electrolyte in lead-acid batteries (accumulators) . It is important in the production of fertilizers such as ammonium sulfate (sulfate of ammonia), (NH4)2SO4, and superphosphate, Ca(H2PO4)2, which is formed when rock phosphate is treated with sulfuric acid. It is used to remove oxides from iron and steel before galvanising or electroplating . Concentrated sulfuric acid is used as a dehydrating agent, that is, to remove water, since it has a tendency to form hydrates such as H2SO4.H2O, H2SO4.2H2O. Sulfuric acid is used in the production of nitroglycerine, an inorganic ester organic nitrate, which is used as an explosive. It is used in petroleum refining to wash impurities out of gasoline and other refinery products. It is used in manufacturing of hydrochloric acid, nitric acid, phosphoric acid, ether, plastics, metal sulfates, cellophane, dyes, drugs, perfumes, disinfectants and even glue.1 This chart shows the distribution of using sulfuric acid Figure (1.3.1): Sulfuric Acid Distribution.1 Specification of raw materials sulfur, S, 16 Name, symbol, number 32.065g ·molà ¢Ã‹â€ Ã¢â‚¬â„¢1 Standard atomic weight Yellow colored lumps, crystals, powder, or formed shape Appearances Lumps 75-115 lbs./ft3 Powder 33-80 lbs./ft3 Bulk Density 388.36  K,à ¢Ã¢â€š ¬Ã¢â‚¬Å¡115.21  Ã‚ °C,à ¢Ã¢â€š ¬Ã¢â‚¬Å¡239.38  Ã‚ °F Melting point 717.8  K,à ¢Ã¢â€š ¬Ã¢â‚¬Å¡444.6  Ã‚ °C,à ¢Ã¢â€š ¬Ã¢â‚¬Å¡832.3  Ã‚ °F Boiling point Insoluble Solubility In Water Solid Physical State 1.819 g ·cmà ¢Ã‹â€ Ã¢â‚¬â„¢3 Liquid density at maps. Table (1.3.1): Physical Chemical Properties of Sulfur.1 CHAPTER TWO LITERATURE AND MARKET SURVEY 2.1 History and Current processes The discovery of sulfuric acid is credited to the 8th century chemist and alchemist, Jabir ibn Hayyan (Geber). The acid was later studied by 9th century Persian physician and alchemist Ibn Zakariya al-Razi (Rhazes), who obtained the substance by dry distillation of minerals including iron(II) sulfate heptahydrate, FeSO4 ·7H2O, and copper(II) sulfate pentahydrate, CuSO4 ·5H2O. When heated, these compounds decompose to iron(II) oxide and copper(II) oxide, respectively, giving off water and sulfur trioxide, which combine to produce a dilute solution of sulfuric acid. 1 This method was popularized in Europe through translations of Arabic and Persian treatises, as well as books by European alchemists, such as the 13th-century German Albertus Magnus.1 There are two major processes (lead chamber and contact) for production of sulfuric acid and it is available commercially in a number of grades and concentrations. The lead chamber process, the older of the two processes, is used to produce much of the acid used to make fertilizers; it produces a relatively dilute acid (62%-78% H2SO4). The contact process produces a purer, more concentrated acid but requires purer raw materials and the use of expensive catalysts. n both processes sulfur dioxide is oxidized and dissolved in water. The sulfur dioxide is obtained by burning sulfur, by burning pyrites (iron sulfides), by roasting nonferrous sulfide ores preparatory to smelting, or by burning hydrogen sulfide gas. Some sulfuric acid is also made from ferrous sulfate waste solutions from pickling iron and steel and from waste acid sludge from oil refineries. 1 2.2 Supply and Demand This table shows the production rates of sulfuric acid (in metric tones) in some countries at different years. Production of sulfuric acid in metric tones Year country 1994 1997 2000 2006 France 2227 2242 2269 1755 Germany 3380 3496 4898 4595 Greece 360 675 688 815 Italy 1228 1590 1043 1616 Spain 2348 2810 2418 3500 United kingdom 1225 1205 1058 447 Sweden 518 630 629 1010 Table (2.2.1): Production Rates of Sulfuric Acid.3 This table shows the production and sales amounts of sulfuric acid and the consumption rate of sulfur in Jordan from 2000 to 2005, these amounts in (ton/year). Sulfur consumption (ton/tear) Ù Sulfuric acid Year Sales (ton/year) Production (ton/year) 370925 43824 1108605 2000 309816 46614 919548 2001 351011 43307 1055208 2002 265865 51445 961208 2003 364301 49661 1102899 2004 346345 48323 1046540 2005 Table (2.2.2)Jordan Production, Sales and Raw Material Consumption.5 2.3 Prices trends of the raw material and product The global sulfuric acid market experienced an unprecedented rise and fall in pricing between fall 2007 and spring 2009. Consumption of sulfuric acid for fertilizers fell steeply in the second half of 2008 due to the collapse in the global economy. The second half of 2009 is expected to experience almost flat to slightly positive growth, anticipating the improvement in market conditions in 2010. Trade is expected to fall globally, except for Southeast Asia, which would continue to depend on imports. As of early spring 2009, the market is continuing to deteriorate as the supply shortage situation has been replaced by product oversupply in almost all regions. And the world sulfuric acid supply trends are shown in the following chart. Figure (2.3.1): World Sulfuric Acid Supply.2 CHAPTER THREE PROCESS SELECTION Process Selection Sulfuric acid is an important raw material used in many industrial processes, such as phosphate fertilizer production and to a much lesser extent for nitrogen and potassium fertilizers, sulfuric acid is produced by catalytic oxidation of sulfur dioxide to sulfur trioxide, which is subsequently absorbed in water to form sulfuric acid. There are no major variations of commercial interests on this mentioned chemistry. There are alternatives as to source of Sulfur dioxide and method of conversion to sulfur trioxide. The two most common methods for the conversion of sulfur dioxide to sulfuric acid are: 1. Lead Chamber Process. 2. Contact Process 3.1 Lead Chamber Process This is an old process and was introduced in Europe in near the middle of 18th century, its used to produce much of the acid used to make fertilizers; it produces a- relatively dilute acid (62%-78% H2SO4).The classic lead chamber process consists of three stages: Glover tower, lead chambers and Guy-Lussac Tower. In this method hot sulfuric dioxide gas enters the bottom of the reactor called a Glover tower where it is washed with nitrous vitriol (sulfuric acid with nitric oxide, NO, and nitrogen dioxide, NO2, dissolved in it) and mixed with nitric oxide and nitrogen dioxide gases. The Glover tower serves two functions: concentration of the chamber acid and stripping of nitrogen oxides from the liquid to the gas. Concentration of the chamber acid (62% to 68% H2SO4) is achieved by the hot gases entering the tower which evaporate water from the acid. Some of the sulfur dioxide is oxidized to sulfur trioxide and dissolved in the acid wash to form tower acid or Glover acid (about 78% H2SO4). The dissolved nitrogen oxides are stripped from the acid and carried with the gas out of the Glover tower into the lead chambers. From the acid tower a mixture of gases (including sulfur dioxide and trioxide, nitrogen oxides, nitrogen, oxygen, and steam) is transferred to a lead-lined chamber where it is reacted with more water. Sulfuric acid is formed by a complex series of reactions; it condenses on the walls and collects on the floor of the chamber. There may be from three to twelve chambers in a series. The acid produced in the chambers, often called chamber acid or fertilizer acid, contains 62% to 68% H2SO4. After the gases have passed through the chambers they are passed into a reactor called the Gay-Lussac tower where they are washed with cooled concentrated acid (from the acid tower); the nitrogen oxides and unreacted sulfur dioxide dissolve in the acid to form the nitrous vitriol used in the acid tower. Remaining waste gases are usually discharged into the atmosphere. Product acid at a concentration of 78% H2SO4  is drawn from the cooled acid stream that is circulated from the Glover tower to the Guy-Lussac tower.   Nitrogen losses are made up with nitric acid which is added to the Glover tower. The major disadvantage includes the limitations in throughput, quality and concentration of the acid produced, also the environmental pollution. Figure (3.1.1): Typical process flow sheet for the lead Chamber. 3.2 Contact Process Because of economic reasons Contact plants are widely used compared to the lead plants, they are classified according to the raw materials charged to them: elemental Sulfur burning, spent sulfuric acid and hydrogen sulfide burning, and metal sulfide ores and smelter gas burning. The contributions from these plants to the total acid production are 81, 8, and 11 percent, respectively. The contact process incorporates three basic operations (stages), each of which corresponds to a distinct chemical reaction. First, elemental sulfur is received in a solid form containing various impurities. The sulfur is melted in the sulfur melter in the presence of hydrated lime which neutralizes any acidity present in the sulfur. This neutralization prevents problems of acid corrosion which would otherwise be encountered. Heat for the melting of the sulfur is supplied from steam coils. The molten sulfur is kept agitated to improve heat transfer, to prevent solids settling on the bottom of the sulfur pits and to prevent a crust forming on top. The dirty sulfur is filtered to remove impurities present and after filtering is transferred to the clean sulfur pit where it is kept molten until it is pumped to the burner. Molten sulfur at a temperature of 130 °C is sprayed into the burner in the presence of warm, dry air. The sulfur burns, forming sulfur dioxide S + O2 â‚ ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚   SO2 à ¢Ã‹â€ Ã¢â‚¬  H = -300 kJ mol-1 The resulting sulfur dioxide is fed to a process unit called a converter, where it is catalytically oxidized to sulfur trioxide (SO3): 2SO2 + O2 â‚ ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  2SO3 ΆH = -100 kJ mol-1 Its apparent that the equation gives a decrease in volume; this reaction would be aided by pressure. High conversions are however, obtainable with catalysts at 400 to 500oC with a small excess of oxygen and the use of pressure. The available methods to maximize the formation of SO3: As this is an exothermic process, a decrease in temperature by removal of the heat will favour the formation of SO3. Increased oxygen concentration. SO3 removal (as in the case of the double absorption process). Increased pressure. Catalyst selection, to reduce the working temperature (equilibrium). Longer reaction time. In the contact processes, the sulfur dioxide is converted to sulfur trioxide by the use of metal oxide catalyst, the characteristics of the used catalyst are: Porous carrier having large surface area, controlled pore size and resistance to process gases at high temperature; in pellet form if used in fixed bed and powdered form if used for fluidized bed. Ex- Alumina, silica gel, zeolites. Active catalytic agent: Preparations are generally kept secret for the competitive reasons but they usually consist of adding water soluble compounds to gels or porous substrates and firing at temperature below the sintering point. Promoter: Alkali and/or metallic compounds added in trace amounts to enhance the activity of the catalytic agent. A catalyst, vanadium pentoxide (V2O5) is used to increase the reaction rate because its relatively immune to poisons, also because of its low initial investment and only 5% replacement per year. It is only effective above its melting point of 400  °C. The greatest conversion of SO2 to SO3 is reached by passing the gas over several catalyst beds, cooling the gas between each pass so that the reaction temperature remains between 400 and 500  °C. As can be seen the figure. The disadvantages of using the V2O5 catalyst are that it must use dilute SO2 input (7-10%), as a catalyst it is less active and requires high oxygen or sulfur dioxide to give economic conversions also it requires larger converters and thus higher initial investment. Finally, the sulfur trioxide is absorbed in to very concentrated sulfuric acid (a 98-99 percent solution of H2SO4 in water), This operation takes place in the absorbing tower where the gas travels up through the tower, counter-current to the acid falling from the top of the tower producing a thick fuming liquid called oleum, the oleum is mixed carefully with water to avoid producing fine mist of sulfuric acid that is difficult to condense and could escape to pollute the air, the sulfur trioxide in the oleum reacts with the water as follows: SO3 + H2O â‚ ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  H2SO4 à ¢Ã‹â€ Ã¢â‚¬  H = -200 kJ mol-1 It is clear that the reaction is exothermic and the absorbing sulfuric acid has to be cooled continuously; the heat is available at a relatively low temperature and is not worth recovering. The efficiency of the absorption step is related to : The H2SO4 concentration of the absorbing liquid. (98.5 99.5%). The temperature range of the liquid (normally 70 -120 0C). The technique of the acid distribution. The raw gas humidity (mist passes the absorption equipment). The mist filter. The temperature of incoming gas. The co-current or countercurrent character of the gas stream in the absorbing liquid. Main disadvantages of the contact process are that concentrated acid (98%) of high purity can be produced directly and that compact plants of quite high capacity have now become rather common place. The contact process can be applied in different techniques; three of those techniques are described in the following sections 3.2.1 Single contact / single absorption process After purification and drying, the SO2 is converted to SO3 using a series of four catalyst beds, containing alkali and V2O5. Afterwards, the SO3 is absorbed in concentrated sulfuric acid and, if necessary, an oleum absorber is installed upstream. SO3 reacts with the water contained in the absorber acid to yield H2SO4. The absorber acid is kept at the desired concentration of approximately 99% w/w by addition of water or dilute H2SO4. The single contact/single absorption process is generally used for gases with an SO2 Content from 3 6 %. New single contact plants are built only for inlet gases with substantial fluctuation of the SO2 content. The investment cost of this technique is low compared to the investment cost of double contact plants. Figure (3.2.1.1): Typical process flow sheet for a single catalysis plant. 3.2.2 Double Contact/ Double Absorption Process The double contact process was implemented to develop the single contact/single absorption process. In this process a primary SO2 conversion of 85 95 % is achieved in the first catalysis stage of the converter before entry into an intermediate absorber, depending on the arrangement of the converter beds and the contact time. What makes the double contact/double absorption process more advantageous is that its ability to feed gases with higher SO2 concentrations than would be possible with the single catalysis process. Which leads to smaller gas volumes and therefore smaller equipment with comparable production capacities. This results in a considerably higher conversion rate, if the residual gas is passed through the following converter beds (usually one or two). The SO3 which is formed in the second catalysis stage is absorbed in the final absorber. In general the process uses gases with an SO2 content of 10 t o11 %. The inlet gas temperature is about 4000C. Gases with lower temperatures require reheating from 50 to 4000C. This is usually carried out with recovered heats from the conversion process. Operating the double contact process at an elevated pressure of 5 bar increases the conversion rate by shifting the conversion equilibrium and favouring the formation of SO3. The disadvantages are higher electricity consumption and, at the same time, less steam production. Higher NOx emissions are caused by higher sulfur combustion temperatures (18000C), but savings of 10 -17 % on investment costs are gained. Figure 3.2.2.1: Typical process flow sheet for a sulfur burning double catalysis plant. 3.2.3 Wet catalysis process The wet catalysis process is applicable to wet SO2 gases. The potential for the formation of sulfuric acid mist might require tail gas treatment. Wet SO2 gases (eg. from the burning of H2S gases or from the catalytic conversion of H2S gases) are directly supplied into the contact tower without previous drying. SO3 formed by the catalytic conversion immediately reacts with the moisture of the gases, thereby forming the acetic acid. The sulfuric acid is condensed in a condenser installed after the contact tower. Factors Sulfuric Acid Production By Lead Chamber process Sulfuric Acid Production By single contact/single absorption process Sulfuric Acid Production By double contact/double absorption process Sulfuric Acid Production By Wet Catalysis process Health and safety hazards involved Less safe, waste gases are discharged to the atmosphere Less amount of SO3 is absorbed so the rest is discharged to the atmosphere A larger amount of SO3 is absorbed A larger amount of SO3 is absorbed Operating cost High operating cost Less operating The least operating cost Less operating cost Raw material SO2, NO, NO2, O2, H2O. Melted sulfur, O2, SO2, SO3. Melted sulfur, H2O, O2, SO2, SO3. Wet SO2 gases, H2S, O2, SO3. Waste products and by products Exhaust gases are discharged to the atmosphere Large amounts of SO2 gas are discharged to the atmosphere Less amounts of SO2 gas are discharged to the atmosphere, less heat released after each successive catalyst bed. A larger amount of SO3 is absorbed Equipment Acid Tower (Glover Tower), Lead Chambers, Reactor (Gay-lussac Tower) Air dryer, burner, waste heat boiler, converter, single absorption column. Air dryer, burner, waste heat boiler, converter, intermediate and external absorption column. Burner, convertor, acid tower. Yield Yields 78% H2SO4 New plants achieve 98 to99 % conversion rates Yields about 98% Yields 70 to 80 % H2SO4   Environmental pollution More gases are discharged to the atmosphere More gases discharged to the atmosphere Less gases discharged to the atmosphere More gases are discharger to the atmosphere Purity of products Low purity Low purity High purity Low purity Table (3.2.1): Process selection Factors Sulfuric Acid Production By Lead Chamber process Sulfuric Acid Production By single contact/single absorption process Sulfuric Acid Production By double contact/double absorption process Sulfuric Acid Production By Wet Catalysis process Health and safety hazards involved 5 5 5 3 Operating cost 6 4 7 5 Raw material 6 5 7 5 Waste products and by products 6 6 7 5 Equipment 7 5 8 6 Yield 5 6 7 9 Environmental pollution 5 5 6 4 Purity of products 6 5 7 9 Total (80) 46 41 54 46 Table (3.2.2): Process Selection According to the discussion and the data presented above we choose the Double Contact/Double Absorption process. CHAPTER FOUR PROCESS DISCRIPTION 4.1 Production of H2SO4 by double contact process The process begins in the burner, in which the melt sulfur is pumped to the burner where it is burnt in an excess of dry air. The gas exiting the burner is maintained at (8 9%v/v) sulfur dioxide and approximately 830 °C due to the heat produced by the exothermic reaction. Sulfurs on burning gives about one third of heat combustion of coal ,and this heat raises the temperature of combustion gases roughly in accordance with the figure (4.1.1) as shown. Figure (4.1.1): Theoretical Flame Temperature.8 This heat is high in temperature and there is plenty of it, consequently it is worth utilizing and the hot gases are led across pipes through which the water passes. The water is heated, steam is raised and the gases are cooled. The sulfur dioxide/air gas mixture is then passed through the stream to converter. The sulfur dioxide is converted to sulfur trioxide by reacting with oxygen over a catalyst. This reaction is described by the equation: 2SO2 + O2 â‚ ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  2SO3 ΆH = -100 kJ mol-1 This reaction occurs in the converter, a four-stage reaction vessel with each stage consisting of a solid catalyst bed through which the gas is passed. The catalyst used is vanadium pentoxide (V2O5), and potassium sulphate dispersed on a silica base which forms a porous support, giving a large surface area for reaction. This reaction is exothermic and its equilibrium constant decreases with increasing temperature (Le Chatelier.s Principle). Figure (4.1.2) shows the percentage conversion of SO2 to SO3 that would be reached at an SO2 concentration of 8% v/v and a range of gas temperatures. However, the reaction rate is also temperature dependent, so that if the temperature becomes too low the equilibrium point will not be reached. In practice, the gas temperature must be maintained between (400 500 °C) to maintain a high reaction rate and also high conversion equilibrium. As the reaction is exothermic, heat is generated across each of the catalyst beds. This heat must be removed between each stage to maintain the optimum reaction temperature into the following stage. The temperature rise through each catalyst bed and the inter-stage cooling is shown in Figure (4.1.2). Figure (4.1.2): The Temperature Rise Through Beds.7 The gas after passing through three catalyst bed goes to the first absorption tower where the Sulfur trioxide is removed. The gas is then reheated to about 420 C, passed through the fourth catalyst bed, then cooled and sent to a second absorption tower. The gas mixture goes to the first and second absorption tower, a packed tower where SO3 is absorbed into a counter-current flow of 98 99% sulfuric acid. The overall reaction can be described by the following equation, where sulfur trioxide reacts with the free water to produce sulfuric acid: SO3 + H2O â‚ ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  Ã¢â€š ¬Ã‚  H2SO4 à ¢Ã‹â€ Ã¢â‚¬  H = -200 kJ mol-1 The circulating sulfuric acid must be maintained at about 98% concentration and temperature is controlled in the desired rang of (70 °C_90 °C) to maximize the absorption efficiency. The acid strength is important because the vapor pressure of sulfur trioxide above sulfuric acid is at a minimum at an acid strength of 98% (see Figure (4.1. 3)). At higher concentrations the increased vapor pressure is caused by SO3 and at lower concentrations the water vapor pressure increases sharply and the resultant acid mist is not readily re-absorbed and escapes to the atmosphere. A stream of sulfuric acid is continuously bled off and cooled through a plate heat exchanger before being passed into the storage tanks. Figure (4.1.3): Relation Between Vapor Pressure and Concentration.7 Figure (4.1.4) : Flow Sheet CHAPTER FIVE ENERGY AND MASS BALANCE 5.1 MASS BALANCE *Drier: Components Amount % H20 1.27 1.3 O2 21.12 23 N2 69.4 75.7 Temperature 25C pressure 1 atm M1 M2 Components Amount % H2SO4 39.4 98 H2O 0.8 2 Temperature 150C pressure 1 atm M3 Components Amount % O2 21.12 23.3 N2 69.4 76.7 Temperature 25C pressure 1 atm M4 Components Amount % H2SO4 39.42 95 H2O 2.1 5 Temperature 150C pressure 1 atm *Burner: M3 Components Amount % O2 21.12 23.3 N2 69.4 76.7 Temperature 26C pressure 1 atm M5 Components Amount % S 3.76 100 Components Amount % SO2 28.16 29 O2 7.04 7 N2 69.4 64 Temperature 830C pressure 1 atm   M6 *Converter: M6 Components Amount % SO2 28.16 29 O2 7.04 7 N2 69.4 64 Temperature 400C pressure 1 atm M7 Components Amount % O2 2.11 2 N2 69.44 66 SO2 8.45 8 SO3 24.64 24 Temperature 450 pressure 1 atm M8 Components Amount % SO2 26.72 26 O2 1.69 1.6 N2 69.44 66.4 SO3 26.72 26 Temperature 450 pressure 1 atm M9 Components Amount % SO2 0.314 6 O2 0.0768 1.5 N2 3.47 66.5 SO3 1.36 26 Temperature 450 pressure 1 atm M10 Components Amount % SO2 0.314 6 O2 0.0768 1.5 N2 3.47 66.5 SO3 1.36 26 Temperature 450 pressure 1 atm M11 Components Amount % SO2 6.08 6 O2 1.54 6 N2 65.97 66.5 SO3 25.84 26 Temperature