ΕΛΛΗΝΙΚΗ ΔΗΜΟΚΡΑΤΙΑ Ανώτατο Εκπαιδευτικό Ίδρυμα Πειραιά Τεχνολογικού Τομέα Ξενόγλωσση Τεχνική Ορολογία Ενότητα: Coal,oil and gas Παναγιώτης Τσατσαρός Τμήμα Μηχανολόγων Μηχανικών ΤΕ
Άδειες Χρήσης Το παρόν εκπαιδευτικό υλικό υπόκειται σε άδειες χρήσης Creative Commons. Για εκπαιδευτικό υλικό, όπως εικόνες, που υπόκειται σε άλλου τύπου άδειας χρήσης, η άδεια χρήσης αναφέρεται ρητώς. Χρηματοδότηση Το παρόν εκπαιδευτικό υλικό έχει αναπτυχθεί στα πλαίσια του εκπαιδευτικού έργου του διδάσκοντα. Το έργο «Ανοικτά Ακαδημαϊκά Μαθήματα στο Ανώτατο Εκπαιδευτικό Ίδρυμα Πειραιά Τεχνολογικού Τομέα» έχει χρηματοδοτήσει μόνο την αναδιαμόρφωση του εκπαιδευτικού υλικού. Το έργο υλοποιείται στο πλαίσιο του Επιχειρησιακού Προγράμματος «Εκπαίδευση και Δια Βίου Μάθηση» και συγχρηματοδοτείται από την Ευρωπαϊκή Ένωση (Ευρωπαϊκό Κοινωνικό Ταμείο) και από εθνικούς πόρους.
1. Σκοποί ενότητας... 4 2. Περιεχόμενα ενότητας... 4 3. Coal, Oil and Gas... 5 3.1 How it works... 5 3.2 Advantages... 5 3.3 Disadvantages... 5 3.4 Is it renewable?... 6 3.5 Clean coal technology: How it works... 6 3.5.1 CARBON CAPTURE AND STORAGE... 6 3.5.2 Coal Preparation... 6 3.5.3 Gasification... 7 3.6 Removing pollutants... 7 3.6.1.1 Sulphur dioxide (SO2)... 7 3.6.1.2 Nitrogen oxides (NOx)... 7 3.6.1.3 Particulates emissions... 7 4. Practice and Exercise: Making deductions... 8
1. Σκοποί ενότητας The aims of this unit are to: Provide authentic text and vocabulary specific to the needs of students of Mechanical Engineering Encourage students to combine their knowledge of English with their technical knowledge Teach students how to describe processes Help students differentiate between advantages and disadvantages of a system Encourage students to make deductions 2. Περιεχόμενα ενότητας Power generation: Coal, Oil and Gas (fossil fuels) Advantages and disadvantages to using fossil fuels Clean coal technology: mode of operation carbon capture and storage, gasification, removal of pollutants
3. Coal, Oil and Gas Coal, oil and gas are called "fossil fuels" because they have been formed from the organic remains of prehistoric plants and animals. 3.1 How it works Coal is crushed to a fine dust and burnt. Oil and gas can be burnt directly. The main bit to remember: The steam that has passed through the power station's turbines has to be cooled, to condense it back into water before it can be pumped round again. This is what happens in the huge "cooling towers" seen at power stations. Burning coal produces sulphur dioxide, an acidic gas that contributes to the formation of acid rain. This can be largely avoided using "flue gas desulphurization" to clean up the gases before they are released into the atmosphere. This method uses limestone, and produces gypsum for the building industry as a by-product. However, it uses a lot of limestone Crude oil (called «petroleum")is easier to get out of the ground than coal, as it can flow along pipes. This also makes it cheaper to transport. Natural gas provides around 20% of the world's consumption of energy, and as well as being burnt in power stations, is used by many people to heat their homes. It is easy to transport along pipes, and gas power stations produce comparatively little pollution. 3.2 Advantages Very large amounts of electricity can be generated in one place using coal, fairly cheaply. Transporting oil and gas to the power stations is easy. Gas-fired power stations are very efficient. A fossil-fuelled power station can be built almost anywhere, so long as you can get large quantities of fuel to it. 3.3 Disadvantages Basically, the main drawback of fossil fuels is pollution.
Burning any fossil fuel produces carbon dioxide, which contributes to the "greenhouse effect", warming the Earth. Burning coal produces more carbon dioxide than burning oil or gas. It also produces sulphur dioxide, a gas that contributes to acid rain. We can reduce this before releasing the waste gases into the atmosphere. Mining coal can be difficult and dangerous. Strip mining destroys large areas of the landscape. Coal-fired power stations need huge amounts of fuel, which means trainloads of coal almost constantly. In order to cope with changing demands for power, the station needs reserves. This means covering a large area of countryside next to the power station with piles of coal. 3.4 Is it renewable? Fossil fuels are not a renewable energy resource. Once we've burned them all, there isn't any more, and our consumption of fossil fuels has nearly doubled every 20 years since 1900. This is a particular problem for oil, because we also use it to make plastics and many other products. 3.5 Clean coal technology: How it works When burned, coal is the dirtiest of all fossil fuels but a range of technologies are being used and developed to reduce the environmental impact of coal-fired power stations. Collectively, they are known as clean coal technology (CCT). 3.5.1 CARBON CAPTURE AND STORAGE Despite the improving efficiency of coal-fired power stations, CO2 emissions remain a problem. Carbon capture and storage (CCS) involves capturing the carbon dioxide, preventing the greenhouse gas entering the atmosphere, and storing it deep underground. A range of approaches of CCS have been developed and have proved to be technically feasible. They have yet to be made available on a large-scale commercial basis because of the costs involved. 3.5.2 Coal Preparation Coal arriving at a power plant contains mineral content that needs to be removed before it is burnt. A number of processes are available to remove unwanted matter and make the coal burn more efficiently.
Coal washing involves grinding the coal into smaller pieces and passing it through a process called gravity separation. One technique involves feeding the coal into barrels containing a fluid that has a density which causes the coal to float, while unwanted material sinks and is removed from the fuel mix. The coal is then pulverized and prepared for burning. 3.5.3 Gasification Coal gasification plants are favored by some because they are flexible and have high levels of efficiency. The gas can be used to power electricity generators, or it can be used elsewhere, i.e. in transportation or the chemical industry. In Integrated Gasification Combined Cycle (IGCC) systems, coal is not combusted directly but reacts with oxygen and steam to form a "syngas" (primarily hydrogen). After being cleaned, it is burned in a gas turbine to generate electricity and to produce steam to power a steam turbine. Coal gasification plants are seen as a primary component of a zero-emissions system. However, the technology remains unproven on a widespread commercial scale. 3.6 Removing pollutants Burning coal produces a range of pollutants that harm the environment: Sulphur dioxide (acid rain); nitrogen oxides (ground-level ozone) and particulates (affects people's respiratory systems). There are a number of options to reduce these emissions: 3.6.1.1 Sulphur dioxide (SO2) Flue gas desulphursation (FGD) systems are used to remove sulphur dioxide. "Wet scrubbers" are the most widespread method and can be up to 99% effective. A mixture of limestone and water is sprayed over the flue gas and this mixture reacts with the SO2 to form gypsum (a calcium sulphate), which is removed and used in the construction industry. 3.6.1.2 Nitrogen oxides (NOx) NOx reduction methods include the use of "low NOx burners". These specially designed burners restrict the amount of oxygen available in the hottest part of the combustion chamber where the coal is burned. This minimizes the formation of the gas and requires less post-combustion treatment. 3.6.1.3 Particulates emissions
Electrostatic precipitators can remove more than 99% of particulates from the flue gas. The system works by creating an electrical field to create a charge on particles which are then attracted by collection plates. Other removal methods include fabric filters and wet particulate scrubbers. 4. Practice and Exercise: Making deductions Finish up the following sentences with information from the text: 1. In order to avoid the formation of acid rain.. 2. Before gases are released into the atmosphere..... 3. Getting crude oil out of the ground is easier. 4. Crude oil is cheaper to transport because. 5. Natural gas is not only.. but also. 6. The greenhouse effect is created due to...... 7. Mining coal is difficult and dangerous as well as... 8. Reserves are needed so that.. 9. CO2 emissions remain a problem although. 10. Before coal is burnt, its. 11. Gravity separation means unwanted material 12. Syngas is formed by coal.. 13. The environment is harmed by. 14. Gypsum is composed of.. 15. The formation of gas is minimized by....