Lecture Outline: Principles of Thermodynamics (PDF)

8/14/23 Lecture Outline Principles of Introduction Thermodynamics Fundamental Concepts Properties...

8/14/23 Lecture Outline Principles of Introduction Thermodynamics Fundamental Concepts Properties (Review) Energy 1st Law of Thermodynamics MEEN 4114 Power Plant Design with Renewable Energy Gas Law Equations Lecture 1 Processes Engr. Emmanuelle R. Biglete, MSME, CSSYB Mechanical Engineering Department 1 2 1  8/14/23 Introduction Fundamental Concepts Thermodynamics is the branch of science which treats of SYSTEM is that portion of the various phenomena of energy, and especially of the laws of universe, an atom or a galaxy, or some transformations of heat into other forms, and vice versa. certain quantity of matter, which we specifically wish to study. It is a region enclosed by specified boundaries or The science that includes the study of energy by imaginary but definite mental transformations and relationships among the physical boundaries. properties of substances which are affected by these BOUNDARY is an imaginary partition transformation. that separates the system from the surrounding environment. The science that is devoted to understanding energy in all its forms such as, mechanical, electrical, chemical, and how SURROUNDING is the region outside the boundary or anything not in the energy changes forms. system. 3 4 2  8/14/23 Types of a System A. Open System ü It exchanges energy (heat and work) and matter with the environment. ü is a system where matter and energy pass across its boundaries Examples: Pump, turbine, air conditioner, Hair Blower hair blower, etc. Pump Steam Turbine Air Conditioner 5 6 3  8/14/23 Types of a System B. Closed System ü It exchanges energy (heat and Cylinder work) but not matter with the environment ü is a system where matter does not cross the boundaries. Piston ü energy can pass through boundaries Examples : piston cylinder assembly, air in a Pressure Cooker Mercury Thermometer Air in a Balloon balloon and mercury in a thermometer and pressure cooker 7 8 4  8/14/23 Types of a System MATTER – anything that occupies space and has mass or weight. Solid, Liquid & Gas. C. Isolated System BASIC PROPERTIES OF THERMODYNAMIC SUBSTANCES ü It does not exchange heat, matter or work with the Two general classifications: environment. a. Extensive Property – is one that is dependent on the magnitude of the mass of the substance ü is a system where neither mass b. Intensive Property – is one that is independent of the mass of the substance. nor energy passed through its boundaries. COMMON PROPERTIES A. Intensive Property B. Extensive Examples: Density Mass - thermos , picnic ice chest Pressure Weight Temperature Volume Specific Volume Energy Specific Weight Specific Gravity Specific Internal Energy 9 10 5  8/14/23 PROPERTIES By introducing a gravitational TEMPERATURE is the measure of hotness Force is defined as the mass times the constant, g and coldness of a body. It is a measure Temperature Scale K °C R °F c acceleration. of the average linear kinetic energy of Newton’s Second Law of Motion: “the ma the molecules of the substance, that Steam point (Boiling 373.15 100 671.67 212 acceleration of a body is directly proportional F= is, the total kinetic energy of all the point) gc molecules divided by the number of to the force acting on it and inversely Triple Point of water 273.16 0.01 491.69 32.02 molecules. proportional to its mass. F Temperature Scale Ice point (Freezing 273.15 0 491.67 32 a¥ point) m 1) Absolute Temperature Scale (ex. Kelvin & Rankine) Absolute zero 0 -273.15 0 -459.67 F = ma 2) Arbitrary or Man-made Temperature F= d (mv ) = mæç dv ö÷ + væç dm ö÷ Scale (ex. Celsius & Fahrenheit) Zeroth Law of Thermodynamics dt è dt ø è dt ø gc = ma = ( s ) = 1slug (1 Ft s ) 1kg m 1 m 2 2 The zeroth law of thermodynamics state that “when two bodies are in thermal but, from classical mechanics mass is F 1N 1lb f invariable with velocity equilibrium with a third body, they are in kg m - m kg f x - FPx y - FPy thermal equilibrium with each other and dm gc = 1 = 9.8066 2 = \ =0 s2 - N s -N BPx - FPx BPy - FPy hence are at the same temperature”. dt lb - Ft slug - Ft dv =1 2 = 32.174 2m F =m = ma s - lb f s - lb f dt 11 12 6  8/14/23 PROPERTIES PROPERTIES Density is the mass per unit volume. It is a measure of the size of the molecules For Solid and Liquid : ratio of the weight of substance to the weight of PRESSURE is the force exerted by a ATMOSPHERIC PRESSURE is the pressure and how closely the molecules are spaced fluid per unit area. associated with the atmosphere due equal volume of water. to the weight of air. in a material. W subs. g subs.V subs. F m S.G. = = P= GAUGE PRESSURE is the amount by r= W std. subs. g std. subs.V std. subs. A which pressure differs from V r subs. g o g cV subs. S.G. = atmospheric pressure. This is Specific Weight /Weight Density is the r std. subs. g o g cV std. subs. measured with a gauge that measures weight per unit volume of the material. S.G. = Weight in air the pressure above (or below) Weight in air - Weight in water atmospheric pressure. W mg o g For Ideal Gases ( ratio of molecular VACUUM PRESSURE The gauge pressure g= = =r o V g cV gc weight of the gas to the molecular weight below atmospheric Specific Gravity / Relative Density is of air ) ABSOLUTE PRESSURE. Although there is S.G. = MWg no limit to how high a pressure can be, the ratio of the density of a substance to MWa there is a limit to how low it can be. the density of a standard substance. This point of absolute minimum is the Specific Volume - volume per unit absolute zero pressure (no pressure at S.G. = Density of Substance mass. V 1 all). Absolute pressure is pressure Density of Standard Substance v= = Pabs = Patm + Pgage measured above this zero point. m r Pabs = Patm - Pvacuum 13 14 7  8/14/23 PROPERTIES ENERGY CONCEPTS Pressure Variation with Liquid Column ENERGY For a substance of constant density (such May be defined as the capacity to do work or as a liquid), the pressure at any vertical to cause heat to flow. position due to the self-weight of the substance above the datum is May be defined as that property of a system dependent of the surface area. that changes by an amount equal to the work or heat transferred across the system boundary. kg kg KN P = gh; ; ft 3 L m 2 where : g = specific weight of liquid h = height of liquid 15 16 8  8/14/23 Forms of Energy Stored Energy – Energies stored within the body which goes or dependent upon the flow of the mass. 1. Potential Energy - f(m,z) 2. Kinetic Energy - f(m,v) 3. Internal Energy - f(m,T) - energy stored within a body or substance by virtue of the activity and configuration of its molecules and of the vibration of the atoms within the molecules. 4. Flow Work - f(p,v) -the work by the fluid to overcome the normal stress Transition Energy -These are energies in motion and are not dependent upon the flow of the mass. 1. Heat 2. Work 17 18 9  8/14/23 m m Internal Energy ΔZ dx Internal energy is defined as the energy associated with the random, disordered motion of molecules. datum Potential Energy Kinetic Energy Internal Energy Flow Work 19 20 10  8/14/23 1st Law of Thermodynamics Conservation of Energy First Corollary of the First Law (applied to closed system) The first law of thermodynamics states that the energy cannot be created nor destroyed it can only be changed from one form to another. dQ = dU + dW NF SURROUNDINGS ( - ) HEAT TRANSFER Q + WORK - WORK ( + ) HEAT TRANSFER Q Figure 3.1 Piston – Cylinder Assembly 21 22 11  8/14/23 Application of the First law of Thermodynamics Conservation of Energy Second Corollary of the First Law ( applied to open system ) Point 1 Q = DPE + DKE + DH + WSF Q = DH + WSF Point 2 Turbine Pipe Flow 23 24 12  8/14/23 Application of the FirstD.law of Thermodynamics Nozzle Gas Law Equations Boyles’ Law 1 C V¥ Þ V= Þ C = PV P P Charles’ Law V V ¥T Þ V = aT Þ a= T Boiler Gay Lussac’s Law Nozzle P P ¥ T Þ P = aT Þ a = T Heat Exchanger 25 26 13  8/14/23 Combined Gas Law Equation Thermodynamic Processes Pa Ta Pa P = Þ Ta = T1 2 P1 T1 P1 Va Ta Va = Þ Ta = T2 V2 T2 V2 System 1 V P P1Va PaV2 System Ta = T2 a = T1 a Þ = V2 P1 T1 T2 V (a) State 1 (b) State 2 Process 1-2 P2 V2 P1 V1 = Piston-Cylinder Arrangement T2 T1 27 28 14  8/14/23 Note the following: P P Ideal Processes Constant Constant pressure volume process process v v P T Constant property Constant process temperature reversible process adiabatic process PV n = C v Property (s) 29 30 15  8/14/23 Properties of a Pure Substance Properties of a Pure Substance 31 32 16  8/14/23 Properties of a Pure Substance End of Lecture. If you have any questions, message me through MS Teams. Always state your name, subject, and section. 33 34 17  Introduction to Power Plant Engineering MEEN 4114 Power Plant Design with Renewable Energy Lecture 2 Engr. Emmanuelle R. Biglete, MSME, CSSYB Mechanical Engineering Department Lecture Outline Intro to Power Plant Engineering Power and Energy Conventional vs Non-conventional Sources  Electricity Thomas Edison STM image of Si atoms (1847-1931) Bohr Model Positively Negatively Charge Charge Conventional Current VS Electron Electric Charges The charges are propelled by an electric field. We Current Flow need a source of electric potential (voltage), which pushes electrons from a point of low potential energy to higher potential energy. Introduction to PPE Power plant engineering deals with the study of energy, its sources and utilization of energy for power generation. The power is generated by prime movers such as hydraulic turbines, steam turbines, and diesel engines. Energy : is defined as the capacity to do work and it exists in many forms namely mechanical energy, thermal energy, electrical energy, solar energy, etc. Electricity is the only form energy that is easy to produce, easy to transport, easy to use, and easy to control. Electricity consumption per capita is the index of the living standard of the people in a place. Power and Energy Power and Energy are two important words in power plant engineering. Electricity is now considered as basic necessity with Food, Shelter and Clothing for human being. Power and Energy Power is primarily associated with mechanical work and electrical energy. A power plant is a unit built for production and delivery of a flow of mechanical or electrical energy. It is an assemblage of equipment, permanently located on some chosen site which receives raw energy in the form of a substance capable of being operated in such a way as to produce electrical energy for deliver from the power plant. Power Stations A power station (also referred to as a generating station, power plant, powerhouse or generating plant) is an industrial facility for generation of electric power. At the center of nearly all power stations is a generator, a rotating machine that converts mechanical power into electric power by creating relative motion between a magnetic field and a conductor.  Progress of any nation is measured in terms of per capita consumption of electrical energy (KWH consumed per person per year). Philippines - 699 kWh /person per year India – 806 kWh /person per year China – 3,912 kWh /person per year  Power Generation Scenario in the Philippines (2016) Source: https://www.doe.gov.ph/electric-power/2016-philippine-power-situation-report  Power Generation Scenario in the Philippines Impact Strategy - clearly outlines the purpose of the investment, it is a detailed roadmap to achieve the impact, and provides a long- term vision of how such impact will be achieved as well as how the investment will be measured to determine success of the impact vision Conventional vs Non-conventional Sources of Energy Sources Of Electrical Power Generation A.Conventional Sources Thermal (Coal) Nuclear Natural Gas Diesel B.Non-conventional Sources Hydro Wind Solar- PV Biomass Geothermal  Disadvantages Of Conventional Sources Fossil fuels shall be depleted, forcing us to conserve them and find alternative resources. Toxic, Hazardous gases, Residues pollute the environment. Overall conversion efficiency is very poor. Sources are located at remote places with reference to load, increasing transmission cost. Maintenance cost is high.  Thank you for listening. If you have any questions, message me through MS Teams. State your name, subject, and section. The Variable Load MEEN 4114 Power Plant Design with Renewable Energy Lecture 3 Engr. Emmanuelle R. Biglete, MSME Mechanical Engineering Department Topic Outline Power Distribution Basic Loads and Peak Loads Load Curves Variable Load Factors Tariff Electricity in the Philippines  Economic Aspects in Power Generation Introduction The function of a power station is to deliver power to a large number of consumers. The power station is constructed, commissioned and operated to supply required power to consumers with generators running at rated capacity for maximum efficiency. The fundamental problem in generation, transmission and distribution of electrical energy is the fact that electrical energy cannot be stored. It must be generated (supply) and consumed (demand) when needed. The power demanded by the consumers is supplied by the power station through the transmission and distribution networks. As the consumers’ load demand changes, the power supply by the power station changes accordingly.  Power Distribution GENERATION TRANSMISSION DISTRIBUTION 3 Phase AC Power Generation in the Philippines Monte Oro Grid Resources Corporation, Calaca High Power Corporation, and the State Grid Corporation of China. Electricity Electricity Electricity Electricity Grid Schema  Base Loads and Peak Loads Base load is the minimum level of electricity demand required over a period of 24 hours. It is needed to provide power to components that keep running at all times (also referred as continuous load). Peak load is the time of high demand. These peaking demands are often for only shorter durations. In mathematical terms, peak demand could be understood as the difference between the base demand and the highest demand. Examples of household loads: microwave oven, toaster and television are examples of peak demand, whereas refrigerator and HVAC systems are examples of base demand. This constant power, which is required at all times, is called the base loading. But during a special events, the demand will be more. This short, high demand period is considered to be a peak loading.  Variable Load on Power Station The consumers require their small or large block of power in accordance with the demands of their activities. Thus the load demand of one consumer at any time may be different from that of the other consumer. Effects of variable load: The variable load on a power station introduces many perplexities in its operation. Some of the important effects of variable load on a power station are : 1. Need of additional equipment 2. Increase in production cost  Load Curves The curve showing the variation of load on the power station with respect to time is known as a load curve. Load variations during the whole day (i.e., 24 hours) are recorded half-hourly or hourly and are plotted against time on the graph. The curve thus obtained is known as daily load curve as it shows the variations of load w.r.t. time during the day.  Load Curves The monthly load curve can be obtained from the daily load curves of that month. For this purpose, average values of power over a month at different times of the day are calculated and then plotted on the graph. Types of Load Curves: Residential Load Curve Industrial Load Curve Commercial Load Curve Ideal Load Curve Realized Load Curve  Importance of Load Curves 1. The daily load curve shows the variations of load on the power station during different hours of the day. 2. The area under the daily load curve gives the number of units generated in the day. Units generated/day = Area (in kWh) under daily load curve. 3. The highest point on the daily load curve represents the maximum demand on the station on that day. 4. The area under the daily load curve divided by the number of hours gives the average load on the station on that day. 𝐴𝑟𝑒𝑎 𝑖𝑛 𝑘𝑊ℎ 𝑢𝑛𝑑𝑒𝑟 𝑡ℎ𝑒 𝑑𝑎𝑖𝑙𝑦 𝑙𝑜𝑎𝑑 𝑐𝑢𝑟𝑣𝑒 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐿𝑜𝑎𝑑 = 24 ℎ𝑜𝑢𝑟𝑠 Note: One may use Trapezoidal Rule or Integration to find the area under the curve.  Importance of Load Curves 1. The ratio of the area under the load curve to the total area of rectangle in which it is contained gives the load factor. 2. The load curve helps in selecting the size and number of generating units. 3. The load curve helps in preparing the operation schedule of the station.  Important Terms and Factors Connected load is the sum of continuous ratings of the load consuming apparatus connected to the system. Cold Reserve is that reserve generating capacity which is available for the service but not in the operations. Normally not ready for immediate loading. Period of the cold reserve start-up varies from 2 to 24 hours and more. Units with small start-up time usually have a power-on reserve. For example, we have an idle generator that can be taken into service if demand increases. Hot Reserve is that reserve generating capacity which is operation but not in service. For example, we have a hydroelectric generator of rating say 100 MVA but currently supplies only 70 MVA. In this case we have 30 MVA hot reserve than can be loaded immediately by simply opening the valve to the hydro turbine. Spinning Reserve is that generating capacity which is connected to the grid and ready to take load. Firm Pow er is the power intended to be always available (even under emergency conditions).  Important Terms and Factors Maximum Demand: It is the greatest demand of load on the power station during a given period. In the Load Curve example, the maximum demand on the power station during the day is 6 MW and it occurs at 6 P.M. Maximum demand is generally less than the connected load because all the consumers do not switch on their connected load to the system at a time. The knowledge of maximum demand is very important as it helps in determining the Maximum Demand installed capacity of the station.  Important Terms and Factors Demand Factor: It is the ratio of maximum demand on the power station to its connected load. 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑚𝑎𝑛𝑑 𝐷𝑒𝑚𝑎𝑛𝑑 𝐹𝑎𝑐𝑡𝑜𝑟 = 𝐶𝑜𝑛𝑛𝑒𝑐𝑡𝑒𝑑 𝐿𝑜𝑎𝑑 The value of demand factor is usually less than 1. If the maximum demand on the power station is 80 MW and the connected load is 100 MW, then demand factor = 80/100 = 0.8. The knowledge of demand factor is vital in determining the capacity of the plant equipment.  Important Terms and Factors Average load: The average of loads occurring on the power station in a given period (day or month or year) is known as average load or average demand. 𝐸𝑛𝑒𝑟𝑔𝑦 𝐺𝑒𝑛𝑒𝑟𝑎𝑡𝑒𝑑 𝑖𝑛 𝑎 𝑔𝑖𝑣𝑒𝑛 𝑡𝑖𝑚𝑒 𝑖𝑛𝑡𝑒𝑟𝑣𝑎𝑙 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐿𝑜𝑎𝑑 = 𝑇ℎ𝑒 𝑔𝑖𝑣𝑒𝑛 𝑡𝑖𝑚𝑒 𝑖𝑛𝑡𝑒𝑟𝑣𝑎𝑙  Important Terms and Factors Load factor: The ratio of average load to the maximum demand during a given period is known as load factor. The load factor may be daily load factor, monthly load factor or annual load factor if the time period considered is a day or month or year, respectively. Load factor is always less than 1 because average load is smaller than the maximum demand. The load factor plays key role in determining the overall cost per unit generated. The higher the load factor of the power station, the lesser will be the cost per unit generated.  Important Terms and Factors Diversity factor: The ratio of the sum of individual maximum demands to the maximum demand on power station is known as diversity factor. A power station supplies load to various types of consumers whose maximum demands generally do not occur at the same time. Therefore, the maximum demand on the power station is always less than the sum of individual maximum demands of the consumers. Obviously, diversity factor will always be greater than 1. The greater the diversity factor, the lesser is the cost of generation of power.  Important Terms and Factors Plant capacity factor: It is the ratio of actual energy produced to the maximum possible energy that could have been produced during a given period. Thus if the considered period is one year, The plant capacity factor is an indication of the reserve capacity of the plant. A power station is so designed that it has some reserve capacity for meeting the increased load demand in future. Therefore, the installed capacity of the plant is always somewhat greater than the maximum demand on the plant.  Important Terms and Factors Plant use factor: It is ratio of kWh generated to the product of plant capacity and the number of hours for which the plant was in operation Suppose a plant having installed capacity of 20 MW produces annual output of 7.35 × 106 kWh and remains in operation for 2190 hours in a year. Then, Reserve Factor: It is ratio of the plant capacity to the maximum load. 𝑃𝑙𝑎𝑛𝑡 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝐿𝑜𝑎𝑑 𝑓𝑎𝑐𝑡𝑜𝑟 𝑅𝑒𝑠𝑒𝑟𝑣𝑒 𝑓𝑎𝑐𝑡𝑜𝑟 = = 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐿𝑜𝑎𝑑 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝐹𝑎𝑐𝑡𝑜𝑟 Reserve Overpeak: It is the excess load from the plant capacity to meet maximum demand. 𝑅𝑒𝑠𝑒𝑟𝑣𝑒 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 = 𝑃𝑙𝑎𝑛𝑡 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 − 𝑃𝑒𝑎𝑘 𝐿𝑜𝑎𝑑  Important Terms and Factors Load Duration Curve: When the load elements of a load curve are arranged in the order of descending magnitudes, the curve thus obtained is called a load duration curve. Cheat Sheet 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑚𝑎𝑛𝑑 𝐷𝑒𝑚𝑎𝑛𝑑 𝐹𝑎𝑐𝑡𝑜𝑟 = 𝐶𝑜𝑛𝑛𝑒𝑐𝑡𝑒𝑑 𝐿𝑜𝑎𝑑 𝑃𝑙𝑎𝑛𝑡 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝐿𝑜𝑎𝑑 𝑓𝑎𝑐𝑡𝑜𝑟 𝑅𝑒𝑠𝑒𝑟𝑣𝑒 𝑓𝑎𝑐𝑡𝑜𝑟 = = 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐿𝑜𝑎𝑑 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝐹𝑎𝑐𝑡𝑜𝑟 Example 1 A power plant is represented by an average daily load given by the following coordinates. This is carried by one 13000-kW steam turbo-generating unit. Time Load, Time Load, Time Load, Time Load, kW kW kW kW 12 AM 220 1 AM 220 7 AM 300 1 PM 500 7 PM 900 2 AM 200 8 AM 410 2 PM 620 8 PM 870 3 AM 190 9 AM 560 3 PM 670 9 PM 850 4 AM 180 10 AM 590 4 PM 760 10 PM 720 5 AM 180 11 AM 610 5 PM 1000 11 PM 600 6 AM 200 12 PM 605 6 PM 930 12 AM 380 Determine the following: a. Load Curve b. Load Factor c. Capacity Factor  Example 2 A power station supplies the following loads to the consumers. x10 Estimate the ff: a) Load Factor b) Load Factor for a 30MW stand-by Power Plant in excess of 70MW c) Use Factor of the Stand-by unit Example 3 The peak load on a power plant is 60MW. The loads having the maximum demands of 30MW, 20MW, 10MW, and 14MW are connected to the plant. The capacity of the power plant is 80MW and the annual load factor is 0.5. Estimate: a) Average Load b) Energy Supplied per year c) Demand Factor d) Diversity Factor Example 4 A power station allocates a reserve power of 8,900 kW above the peak load throughout its annual operation. Based on the records, the factors for the station are as follows: Load factor = 59% Capacity factor = 42% Plant use factor = 45% Calculate the following: a. Peak load, kW b. Average load, kW c. Operating hours per year d. Hours not in service per year  Tariff The rate at which electrical energy is supplied to a consumer is known as tariff. Although tariff should include the total cost of producing and supplying electrical energy plus the profit, consideration has to be given to different types of consumers (e.g., industrial, domestic and commercial) while fixing the tariff. Please open the url below for the detailed discussion of your Meralco bill. https://www.youtube.com/watch?v=di08h6bObyw https://www.youtube.com/ watch?v=di08h6bObyw  Tariff Objectives of tariff: Like other commodities, electrical energy is also sold at such a rate so that it not only returns the cost but also earns reasonable profit. Therefore, a tariff should include the following items : (i) Recovery of cost of producing electrical energy at the power station. (ii) Recovery of cost on the capital investment in transmission and distribution systems. (iii) Recovery of cost of operation and maintenance of supply of electrical energy e.g., metering equipment, billing etc. (iv) A suitable profit on the capital investment.  Tariff The electrical energy produced by a power station is delivered to a large number of consumers. The consumers can be persuaded to use electrical energy if it is sold at reasonable rates.  Tariff Factors Affecting Electricity Tariff: Types of Load – The load is mainly classified into three types, i.e., domestic, commercial, or industrial. The tariff of the electric energy varies according to their requirement. Maximum demand – The cost of the electrical energy supplied by a generating station depends on the installed capacity of the plant and kWh generated. Increased in maximum capacity, increased the installed capacity of the generating station. The time at which load is required – If the maximum demand coincides with the maximum demand of the consumer, then Power the Factor – ratio additional of is required. And if the plant maximum demand of the consumers occurs Working power during (kW) tohours, the load factor is off-peak improved, and no extra plant capacity is Apparent Power needed. (kVA) Thus, the overall cost per kWh generated is reduced. The power factor of the load – The power factor plays a major role in the plant economics. The low power factor increases the load current which increases the losses in the system. Thus, the regulation becomes poor. For improving the power factor, the power factor correction equipment is installed at the generating station. Thus, the cost of the generation increases.  Electricity in the Philippines Source : Meralco  Electricity in the Philippines 1. The government doesn't subsidize energy. Several neighboring countries -- Thailand, Indonesia, Malaysia, Korea and Taiwan -- all have lower tariffs because of government subsidies. 2. It's expensive to produce energy in the Philippines. 3. Challenging geography. Because the Philippines is made up of thousands of islands, it does not have a unified electricity grid and there are several providers. The bigger the grid the cheaper the cost" which can be spread out among more customers. 4. Ineffective plants. When some plants don't work well, it is necessary to have a reserve plant, which means additional costs. The higher your reserve margin the higher the total cost of supply. The reserve margin of the Philippines is probably around 20% but should actually be between 33% to 35%.  End of Lecture. If you have any questions, please message me through MS Teams. State your name, subject, and section.  Fuels MEEN 4114 Power Plant Design with Renewable Energy Lecture 4 Engr. Emmanuelle R. Biglete, MSME, CSSYB Mechanical Engineering Department Lecture Outline Definition Types of Fuels Coals Crude Oil Fractional Distillation Gaseous Fuels Properties of Fuels  Fuels → Is any substance, natural or artificial, which upon combustion releases heat energy. Classification of Fuels: 1. Solid Fuels- such as coal, coke, wood, charcoal, bagasse, coconut shells, rise husks, and briquetted fuels (compressed blocks) 2. Liquid Fuels- such as crude oil, and its distillates (gasoline, alcohol, kerosene, diesel, bunker, and other oils) 3. Gaseous Fuels- such as natural gas, artificial gas, blast furnace gas, liquefied petroleum gas (LPG), methane, acetylene, propane, butane, etc. 4. Atomic Fuels- such as uranium- 233, uranium-235, and plutonium-239. It has the higher energy density of all fuel sources.  Coal → Is a flammable, hard, and combustible sedimentary rock used as a solid fossil fuel. It is essentially carbon and also contains hydrogen, sulfur, oxygen, and nitrogen. It is mined through underground or surface mining. The higher the grade of coal, the cleaner is gets and more versatile in its uses. Types of Coal Coke- grey, hard, and porous fuel with a high carbon content and few impurities which is a product of destructive distillation. The coal is heated to about 4000C without the presence of oxygen. It can be used for steel making by addition of a caking additive. Petcoke  Destructive Distillation Coke + Hot Steam = Water Gas (CO and H2) 60% C Unreacted vapors PRODUCTS: Coal Gas – used for industrial fuels (methane, hydrogen, CO, and other gaseous hydrocarbons) Ammoniacal Liquor – fertilizers Coal Tar – dyes, insecticides, medicines Coke  Coal Mining Coal Mining is the term that encompasses the physical extraction or removal of coal from the earth’s surface. Thermal Coal - coal is used for power generation Coking or Metallurgical Coal – for steel manufacturing (good quality coke) GENERAL TYPES OF MINING: Surface Mining Surface Mining – form of mining in which soil and the rock covering the mineral deposits are removed. It is carried out when the deposits are found closer to the surface. It accounts for 40% of coal production in the world. Up to 50m. Underground Mining– is carried when mineral deposits are located at a distance far beneath the ground to be extracted with surface mining. From 50m to 100m. Underground Mining Coal Mining Methods Applications Application  Solid Fuel Composition Proximate analysis- parameters include moisture, volatile matter, ash content, and fixed carbon. Ultimate analysis- is dependent on quantitative analysis of various elements present in the coal sample such as carbon, hydrogen, sulfur, oxygen, and nitrogen. Other Types of Solid Fuels Rice Husks Coal Briquettes Bagasse  Crude Oil Crude oil is a liquid fuel located underground. It is the chief source of transportation fuels. It has between 50% to 97% of oil, hydrocarbons, and between 6-10% of nitrogen, oxygen, and sulfur. Oil is called a fossil fuel because of its origins. The intense pressure heated them over millions of years. It first became a waxy substance called kerogen. It became liquid oil after more pressure and heat.  Crude Oil Drilling Drilling rigs use a drill stem and a drill bit to grind down through the overlaying rock to get to the oil and gas below. Drill rigs run 24 hours a day, 7 days a week. Cost to drill : (2010 average) Vertical well ~$450,000 + Horizontal well ~$937,607 +  Drilling Methods Horizontal Drilling A horizontal well is drilled vertically until the kick-off point is reached. At this point the well is angled until it meets the targeted producing formation. The wellbore is then drilled horizontally through this reservoir. Horizontal wells provide for a greater drainage area than a conventional vertical well and therefore are generally more productive. Vertical Drilling A hole drilled vertically into the earth usually cased with metal pipe for the production of oil or gas. Prior to 2006, most wells were drilled vertically but new drilling and completion techniques have made horizontals wells economic. Directional Drilling The technique of drilling at an angle. These wells are drilled for a number of reasons: to develop an offshore lease from one platform; to reach a zone beneath land where drilling cannot be done (beneath a railroad or lake).  Vertical Horizontal Drill Pipes Drill Bits Directional  Types of Drilling Rigs Land Rigs Marine Rigs Marine Rigs  Petroleum Refining Process LPG Naphtha Hydrotreating Aromatics Benzene Crude Oil Bunker OPEC (44% oil Plant Toluene (HDS AND HDN) production, 81.5% Xylene and Reforming Naphtha - oil reserves Blending MOGAS (Gasoline) Crude Oil Tank Kerosene/ Jet Fuel KERO Treating JET FUEL Diesel Hydro DIESEL treating Catalytic Propylene Cracking PROPYLENE Recovery Crude Atm. Distillation Vacuum Distillation Vacuum Distillation Thermal Treating Bottoms Cracking PETCOKE For Heavy Oil  The Middle East contains 45–60% of the world’s petroleum reserves The field was estimated to contain proved reserves totaling 58.32 billion barrels of oil equivalent, including 48.25 Ghawar billion barrels of liquids reserves as at December 2018. Ghawar: * World’s largest oil field (280x40km) * 60-65% of KSA production to date * 6% of global production to date * 6% of modern production  Fractional Distillation → technique used to separate components of crude oil for liquid fuels Crude oil is fed into a furnace and heated gases without the presence of air (oxygen). Most of the oil is converted into a vapor and naptha rises up the tower (column). As the vapor rises up the tower it begins to gasoline cool. Heavier ‘fractions’ of crude oil condense first in the lower parts of the tower. kerosene The lightest fractions condense at the top of the tower. Some fractions (1 to 4 carbons remain as gases) diesel Each fraction is removed from the tower as it condenses. lubricants fuel oil residue Fractional Distillation The bubble caps found inside a fractional distillation tower help separate the crude oil vapor into distinct fractions. Heavy fractions that have reached their condensation temperatures will hit the bubble cap, condense and drip down to the pans below. These fractions are then removed from the tower. Lighter fractions remain as vapor will hit the cap but continue to rise up to the next higher layer of bubble caps.  Vacuum Distillation Vacuum distillation is the distillation of liquids performed at a pressure lower than atmospheric pressure to take advantage of the fact that reducing the pressure lowers the boiling point of liquids. It is a part of the refining process that helps to produce petroleum products out of the heavier oils left over from atmospheric distillation. Commonly used Hydrocarbon Fractions  Cracking Cracking is the process to break up large hydrocarbon molecules into smaller and more useful bits. This is achieved by using high pressures and temperatures without a catalyst, or lower temperatures and pressures in the presence of a catalyst.  Gaseous Fuels Manufactured Fuel Gas Are those produced through an artificial gas, usually gasification, at a known location known as gasworks. 1. Biogas – It is a mixture of methane and carbon dioxide. It is a renewable form of energy. 2. Producer Gas – a combustible mixture of nitrogen, CO2 , CO, and hydrogen, generated by passing air with steam over burning coke or coal in a furnace and used as fuel. Natural Gas Petroleum Gas - LPG It is a non-renewable energy The main composition of LPG are hydrocarbons containing three or four carbon atoms. It can easily be condensed, packaged, stored, and utilized.  Natural Gas Natural gas is a mixture of hydrocarbons which are multiple combinations of carbon and hydrogen atoms. It has the cleanest combustion profile of all fossil fuels (carbon dioxide and water vapor as products). Natural gas forms organically over millions of years from decomposing plants and animal matter that is buried in sedimentary rocks layers. Once formed, the gas tends to migrate through the pore spaces, fractures, and fissures in the sediments and rocks. Methane is the primary component of natural gas. Gas Seepage Composition of a Natural Gas  Dry and Wet Natural Gas Dry Natural Gas Wet Natural Gas Almost complete methane It contains LNGs (Ethane, Butane) Less than 85% Methane It remains after all liquified hydrocarbons and LNGs are separated from the methane and sold non-hydrocarbon impurities are removed as individual compounds. It is typically used in heating and cooling LNGs such as butane can be used in systems and for electrical power generation. refrigeration and freezing systems. CNG (20-25MPa)  Heating Value/ Calorific Value Heating Value – quantity of heat produced by the combustion of fuel under specified condition per unit weight or unit of volume. It is the energy content of a fuel. HHV (Higher Heating Value) – accounts for the energy carried by the superheated water vapor. The products of combustion of fuel with H2 content producing vapor in superheated state and will usually leave the system, thus carrying with it the energy represented by the superheated water vapor. -It is the heating value obtained when the water in the products of combustion is in the liquid state. LHV (Lower Heating Value) – is found by deducting the heat needed to vaporize the mechanical moisture and the moisture found when fuel burns from HHV. -It is the heating value obtained when the water in the products of combustion is in the vapor state. Properties of Fuels 1. API and Baume Gravity Units - a standard to express the specific weight of oils. 141.5 140 °𝐴𝑃𝐼 = − 131.5 °𝐵𝑎𝑢𝑚𝑒 = − 130 𝑆𝐺 𝑎𝑡 15.6°𝐶 𝑆𝐺 𝑎𝑡 60°𝐹 2. Specific Gravity at temperature, T SGt = ([email protected])[1- 0.00072(t -15.6)] SGt = ([email protected])[1- 0.0004(t - 60)] (T in degree C) (T in degree F) 3. Higher Heating Value Dulong’s Formula for Solid Fuels HHV = 33,820 C + 144,212 (H2 – O2/8) + 9,304 S kJ/kg ASME Formula for Petroleum Products HHV = 41,130 + 139.6 ( 0API) kJ/kg Bureau of Standards Formula: HHV = 51,716 – 8793.8 (SG)2 kJ/kg HHV = 42,450 + 93(Be’ + 10) at 15.60C (for fuel oil) kJ/kg  Properties of Fuels Heat required to vaporize the moisture in the 4. LHV of Solid Fuels products LHV = HHV – 9H2 (2442) kJ/kg Where: H2 = 26 – 15*(SG at 15.6C) (in %) 5. For Liquid Fuels HHV = 31,405C + 141,647H kJ/kg LHV = 43,385 + 93 ( 0Baume - 10) kJ/kg 6. For Gasoline HHV = 41,160 + 93(0API) kJ/kg LHV = 38,639 + 93( 0API) kJ/kg 7. For Kerosene HHV = 41,943 + 93(0API) kJ/kg LHV = 39,035 + 93( 0API) kJ/kg  Properties of Fuels 8. For Fuel Oils HHV = 41,130 + 139.6( 0API) kJ/kg LHV = 38,105 + 139.6(0API) kJ/kg 9. Viscosity – the measure of the resistance of fuel to flow. 10. Pour Point – the lowest temperature at which the fuel will flow when it is chilled without disturbance. Pour points range from 32 °C to below −57 °C (90 °F to below −70 °F). 11. Fire point – the temperature at which fuel burns (sustained combustion) upon exposure to ignition source. 12. Ignition Quality – the ability of a fuel to ignite spontaneously.  Flammable vs Combustible 13. Flash Point – the maximum temperature of which a fuel emit vapor that will ignite.  Compositional Analysis Gravimetric analysis/ Mass analysis- is a technique through which the amount of a compound can be determined through the measurement of the mass percentage of each component. The mass fraction of the gas i is defined as: mi xi = m Volumetric analysis/ Molal analysis- is a technique through which the amount of a compound can be determined through the measurement of the volume/ mole percentage of each component. The mole fraction of the gas i is defined as: ni yi = n ni RT Vi P = ni = = yi V nRT n P  Fuel Properties Sample Problem 1 A logging firm in Isabela operates a Diesel electric plant to supply its electric energy requirements. During a 24-hour period, the plant consumed 250 gallons of fuel at 800F and produced 2700 kW-hrs. Industrial fuel used is 300API and was purchased at P3.00 per liter at 600F. Determine the overall efficiency of the plant? Sample Problem 2 (a)623 cubic meters of a fuel gas are passed through a meter at 0.35 kg/cm2 ga., 9.4 degree C, Barometer, 755 mm Hg. Find the commercial sales volume of this gas. (b)The tank contains 214 m3 of fuel oil at 11.7 degree C, SG = 0.945. Find the volume and weight of this quantity of oil measured at 15.6 degree C. Sample Problem 3 A cylindrical oil tank 2.4 m x 6 m long is filled to the neck with fuel oil which is checked at 21o Be’ at 31oC. Estimate the heat stored in this tank in kJ.  End of Lecture. If you gave any questions, message me through MS Teams. State your name, subject, and section.  9/27/23 Coal-fired Power Plants MEEN 4114 Power Plant Design with Renewable Energy Lecture 5 Engr. Emmanuelle R. Biglete, MSME, CSSYB Mechanical Engineering Department 1 Lecture Outline Coal Scenario in the Philippines General Layout of a Thermal Power Station Coal-fired Power Plants Merits and Demerits Combustion Stoichiometry of Coal Sequence of Operation Major Components Vapor Cycles and Modifications Cogeneration Plants Sample Problems on Vapor Cycles and Coal Combustion 2 1  9/27/23 Sources Of Electrical Power Generation A.Conventional Sources üThermal (Coal) Nuclear Natural Gas Diesel B.Non-conventional Sources Hydro Wind Solar- PV Biomass Geothermal Tidal 3 Coal Statistics in the Philippines 4 2  9/27/23 Layout of a Thermal Power Plant A thermal power plant is a power station in which the working fluid is steam. 5 Coal-Based Thermal Power Plant Basics Coal is a natural resource and is imported from Indonesia, India or China. Coal powder is fired in boiler that converts water into steam at high temperature and pressure. This steam is injected over the blades of steam turbine (prime mover) in a controlled way and hence, the rotor of 3 PH AC generator rotates. Mechanical energy is converted into electrical energy at rated voltage(10-30KV). 6 3  9/27/23 Coal-Based Thermal Power Plant Basics Used steam is cooled down to water using cooling towers and condensers. This preheated water is again injected in boiler tubes to convert back to steam. Flue gases are passed into atmosphere and fine particles of ash are collected through Electrostatic Precipitator. Ash(40% of coal weight) is collected and transported to cement plants as additives. 7 Merits of Coal Thermal Plant It is a time-tested process, less space required as compared to Hydro-based station and less hazardous than Nuclear power plant. Less initial cost as compared to other conventional process of power generation. Comparatively inexpensive to buy on the open market due to large reserves and easy accessibility. Easily combustible and burns at low temperatures. Coal is cheap and available in abundance at present (easier to mine). A fossil-fueled power station can be built almost anywhere as long as there are large quantities of fuel. 8 4  9/27/23 Demerits of Coal Thermal Plant Calorific value (kcal/kg) of coal is low and large ash content. Atmospheric pollution is very high. Transportation of coal to plant and transmission of generated power to load center involves large expenses. It is non-renewable and fast depleting. Coal dust is an extreme explosion hazard. Mining of coal leads to irreversible damage to the adjoining environment. Panian Mine, Semirara Island, PH Open-pit Mine in South Cotabato, PH 9 Combustion of Coal Facts: when C is burned, it becomes flue gas H2 mole (a unit for the amount of substance) C all products of combustion should be N2 released on the stack or chimney hot molecules are lighter O2 S Assumptions: Air is assumed to contain no water vapor (dry air) a. Combustion of Carbon, C Nitrogen is inert (with few exceptions) C + O2 → CO2 1moleC +1moleO2 →1moleCO2 ⎡ lb ⎤ ⎡ lb ⎤ ⎡ lb ⎤ 1mole ⎢12 ⎣ mole ⎥⎦ C +1mole ⎢16 ⎣ mole ⎥⎦ (2) O2 →1mole⎢⎣44 ⎥CO2 mole ⎦ 12lbC + 32lbO2 → 44lbCO2 (12lbC + 32lbO2 → 44lbCO2 )1 12 2 2 1 lb of C requires 2 lbs of O2 to produce 3 lbs of CO2 3 3 10 5  9/27/23 Combustion of Coal b. Combustion of Hydrogen, H2 (2) H 2 + O2 → (2) H 2O 2molesH 2 +1moleO2 → 2molesH 2O ⎡ lb ⎤ ⎡ lb ⎤ ⎡ lb ⎤ 2moles ⎢1 ⎣ mole ⎥⎦ (2) H 2 +1mole⎢⎣16 ⎥( 2 ) O2 → 2mole ⎢⎣18 ⎥ H 2O mole ⎦ mole ⎦ 4lbH 2 + 32lbO2 → 36lbH 2O (4lbH 2 + 32lbO2 → 36lbH 2O)1 4 à 1 lb of H2 requires 8 lbs of O2 to produce 9 lbs of H2O c. Combustion of Sulfur, S S + O2 → SO2 1moleS +1moleO2 →1moleSO2 ⎡ lb ⎤ ⎡ lb ⎤ ⎡ lb ⎤ 1mole ⎢12 ⎣ mole ⎥⎦ S +1mole ⎢16 ⎣ mole ⎥⎦ (2) O2 →1mole⎢⎣64 ⎥ SO2 mole ⎦ 32lbS + 32lbO2 → 64lbCO2 (32lbS + 32lbO2 → 64lbCO2 )1 32 à 1 lb of S requires 1 lb of O2 to produce 2 lbs of SO2 11 Combustion of Coal Generalization: O 2 lbO2 lbO2 lbO2 𝑙𝑏𝑂! (oxygen-fuel ratio) = 2 +8 +1 −1 F 3 lbC lbH 2 lbS 𝑙𝑏𝑂! For a given gravimetric analysis of coal, O 2 lbO2 ⎛ lbC ⎞ lbO2 ⎛ lbH 2 ⎞ lbO2 ⎛ lbS ⎞ 𝑙𝑏𝑂! 𝑙𝑏𝑂! =2 ⎜C ⎟+8 ⎜ H2 ⎟ +1 ⎜S ⎟ −1 𝑂 F 3 lbC ⎝ lbfuel ⎠ lbH 2 ⎝ lbfuel ⎠ lbS ⎝ lbfuel ⎠ 𝑙𝑏𝑂! 𝑙𝑏𝑓𝑢𝑒𝑙 2 ⎛ lbO2 ⎞ ⎛ O ⎞ lbO2 ⎛ lbO2 ⎞ = 2 ⎜C ⎟ + 8⎜ H 2 − 2 ⎟ +1⎜ S ⎟ 3 ⎝ lbfuel ⎠ ⎝ 8 ⎠ lbfuel ⎝ lbfuel ⎠ Supplying air instead of pure oxygen, Air Component Gravimetric Analysis Volumetric Analysis Oxygen 23.1% 21% Nitrogen 76.9% 79% 12 6  9/27/23 Combustion of Coal ⎛ ⎞ A ⎡ O lbO2 ⎤⎜ 1 ⎟ =⎢ ⋅ ⎥⎜ ⎟ F ⎣ F lbfuel ⎦⎜ 0.231 lbO2 ⎟ ⎝ lbair ⎠ ⎛ ⎞ ⎡ 2 ⎛ lbO ⎞ ⎛ O2 ⎞ lbO2 ⎛ lbO2 ⎞⎤⎜ 1 ⎟ 2 = ⎢2 ⎜ C ⎟ + 8⎜ H 2 − ⎟ +1⎜ S ⎟⎥⎜ ⎟ 3 ⎣ ⎝ lbfuel ⎠ ⎝ 8 ⎠ lbfuel ⎝ lbfuel ⎠⎦⎜ 0.231 lbO 2 ⎟ ⎝ lbair ⎠ lbair ⎛ O ⎞ lbair lbair A / Ft = 11.5 (C ) + 34.63⎜ H 2 − 2 ⎟ + 4.33 ( S ) lbfuel ⎝ 8 ⎠ lbfuel lbfuel If the ultimate analysis of the coal is not available: HHV (kJ / kg) A / Ft = 3117 13 Combustion of Coal ⎛ ⎞ A ⎡ O lbO2 ⎤⎜ 1 ⎟ =⎢ ⋅ ⎥⎜ ⎟ F ⎣ F lbfuel ⎦⎜ 0.231 lbO2 ⎟ ⎝ lbair ⎠ ⎛ ⎞ ⎡ 2 ⎛ lbO ⎞ ⎛ O ⎞ lbO2 ⎛ lbO2 ⎞⎤⎜ 1 ⎟ 2 = ⎢2 ⎜ C ⎟ + 8⎜ H 2 − 2 ⎟ +1⎜ S ⎟⎥⎜ ⎟ ⎣ 3 ⎝ lbfuel ⎠ ⎝ 8 ⎠ lbfuel ⎝ lbfuel ⎠⎦⎜ 0.231 lbO2 ⎟ ⎝ lbair ⎠ lbair ⎛ O ⎞ lbair lbair A / Ft = 11.5 (C ) + 34.63⎜ H 2 − 2 ⎟ + 4.33 ( S ) lbfuel ⎝ 8 ⎠ lbfuel lbfuel If using Material Balance: 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑓𝑢𝑒𝑙 + 𝑢 𝑂! + 3.76𝑁! → 𝑤𝐶𝑂! + 𝑥𝑆𝑂! + 𝑦𝑁! + 𝑧𝐻! 𝑂 If the ultimate analysis of the coal is not available: HHV (kJ / kg) A / Ft = 3117 14 7  9/27/23 Sample Problems Sample Problem 1 A coal from Indonesia which has an ultimate analysis (by mass) as 61.40% C, 5.79% H2, 25.31% O2, 1.09% N2, 1.41% S, and 5% ash (non-combustibles) is burned with 25% excess air in an industrial boiler. Assuming complete combustion and that the pressure in the boiler smoke stack is 1 atm, calculate the following: (a)the mass of air required per unit mass of coal burned. (b)Gravimetric analysis of dry and wet flue gas (per kg of flue gas) (c)the apparent gas constant of the product gas neglecting the ash content and (d)the minimum temperature, in 0C, of the combustion products before liquid begins to form in the chimney. Assume 100 kg of coal. 15 Typical Coal Fired Thermal Plant 22 8  9/27/23 Typical Coal Fired Thermal Plant 23 Main Components of a Coal-fired PP 1. Coal Conveyor – is a belt type arrangement that are used to move coal efficiently. 2. Pulverizer – increases the combustion efficiency of coal. 3. Boiler – is a device used to create steam by applying heat energy to water. 4. Superheater – After the steam is conditioned by the drying equipment inside the steam drum, it is piped from the upper drum area into the tubes inside an area of furnace known as the superheater. 5. Economizer – are mechanical devices to reduce energy consumption such as preheating a fluid. 6. Reheater 7. Steam Turbine – mechanical device that extracts thermal energy from pressurized steam, and converts into rotary motion. 8. Generator – Converts mechanical energy into electrical energy 9. Condenser – condense the steam to its liquid state by cooling it 10. Deaerator – removes air and other dissolved gases from the feedwater to steam-generating boiler. 24 9  9/27/23 Energy Conversion 25 Coal Handling Coal arriving by train can be stocked for later use or taken straight to the coal bunkers. It is crushed to pieces less than 5 cm. The crushed coal is sent by belt conveyors to a storage pile. The coal mills grind the larger pieces to fine powder and mix them with primary combustion air which transports the coal to the furnace and preheats the coal to drive off excess moisture content. Reclaimer and Coal Silo Conveyors Pulverizer Mill 26 10  9/27/23 Coal Preparation 27 Pulverized Coal Burners Factors Affecting Performance: Characteristics of fuel used. Particle size of pulverized coal. Mixing of air and fuel. Proportions of primary and secondary air. Volatile matter content in coal. Furnace design. 28 11  9/27/23 29 Boiler System The boiler is fed with Heavy Types of Boiler: Fuel Oil and Light Diesel Oil to 1. Water-tube Boiler ignite the coal in the boiler. 2. Fire-tube Boiler 30 12  9/27/23 Economizer An economizer extracts heat from the flue gas and uses it in heating feed water. This use of economizer results in saving coal consumption and higher boiler efficiency. 31 Air Path and Preheaters External fans are provided to give sufficient air for combustion. Air preheaters may be of three types: Plate type Tubular type Regenerative type The induced draft fan assists the FD fan by drawing out combustible gases from the furnace to avoid backfiring through any opening. Plate type Tubular type Regenerative type 32 13  9/27/23 Superheaters and Reheaters Reheaters are also steam boilers in which heat is added to high-pressure steam after it has given some of its energy in the expansion in the intermediate-pressure turbine. A Superheater is a component of a steam generating unit in which steam, after it has left the boiler drum, is heated above its saturation temperature. 33 Water Demineralizing Treatment Plant Since there is continuous withdrawal of steam and continuous return of condensate to the boiler, losses due to blowdown and leakages have to be made to maintain a desired water level in the boiler steam drum. 34 14  9/27/23 Feedwater Heater Advantages of feedwater heater: 1. Feedwater heating improves efficiency. 2. The dissolved oxygen and carbon dioxide which would otherwise cause boiler corrosion are removed. 3. Thermal stresses due to cold water entering the boiler drum are avoided. 4. Quantity of steam produced by the boiler is increased. 5. Some other impurities carried by the steam and condensate, due to corrosion of boiler and condenser are precipitated outside the boiler. Types: Open FWH Closed FWH Steam Trap 35 Steam Turbine 4.1 Mpa 320C 500C 36 15  9/27/23 Generator A synchronous generator is used to generate power by connecting the shaft of the turbine to the shaft of the generator which cuts the magnetic flux producing emf. The generated voltage will generally 10 to 25 kV max. The generated voltage is stepped up by connecting step up transformer and is transmitted and is also used for auxiliary purposes. 37 Condenser Condensers refers to shell and tube heat exchangers or surface condensers installed at the outlet of every steam turbine in thermal power stations of utility companies. Surface Condenser (Shell and Tube Type) 38 16  9/27/23 Ash Handling Plant The Ash from the boiler is collected in two forms: 1. Bottom Ash (Slurry) - the coarse, granular, incombustible by-product of coal combustion that is collected from the bottom of furnaces. 2. Fly Ash - is a fine powder that is a byproduct of burning pulverized coal in electric generation power plants. Fly ash is a pozzolan, a substance containing aluminous and siliceous material that forms cement in the presence of water Clinkers Fly Ash 39 Stack Gas and Cleanup Electrostatic precipitators use charged energy to remove dust and other contaminants from a gas. It is important to match the polarity and type of charge to bind to and remove the pollutants from the gas. The plate is a sheet of metal that is charged with a specific type of charge. These plates are designed to run parallel with the piping so that the gas will pass through by the plates and the plates will remove the dust or contaminate. Plate Electrostatic Precipitator A chimney is an external structure made up of building materials, clay, or metal that isolates hot toxic gases or smoke from a boiler or incinerator. A stack is a large pile larger at the bottom than the top. 40 17  9/27/23 Stack Gas and Cleanup Scrubbers are air pollution control devices that use liquid to remove particulate matter or gases from an industrial exhaust or flue gas stream. This atomized liquid (typically water) entrains particles and pollutant gases in order to effectively wash them out of the gas flow. Tallest flue gas stack - 419.7m 41 42 18  9/27/23 43 44 19  9/27/23 45 Working block diagram of thermal power plant 46 20  9/27/23 The Simple Ideal Rankine Cycle © The McGraw-Hill Companies, Inc.,1998 47 Rankine Cycle: Actual Vapor Power Deviation and Pump and Turbine Irreversibilities (a) Deviation of actual vapor power cycle from the ideal Rankine cycle. (b) The effect of pump and turbine irreversibilities on the ideal Rankine cycle. 48 21  9/27/23 Variations on the Ideal Rankine Cycle Effect of Lowering Condenser Pressure on the Effect of Increasing Boiler Pressure on the Ideal Ideal Rankine cycle Rankine cycle 49 Thermal Efficiency – How to enhance it? Thermal efficiency can be improved by manipulating the temperatures and/or pressures in various components. (a) Lowering the condensing pressure (lowers TL, but decreases quality, x4 ) (b) Superheating the steam to a higher temperature (increases TH but requires higher temp materials) (c) Increasing the boiler pressure (increases TH but requires higher temp/press materials) T 3 (c) increase pressure T 3 2 (b) Superheating 2 1 4 2 1 4 T 1 4 s (a) lower pressure(temp) Low quality 2 high moisture content s Red area = increase in W net 1 Blue area = decrease in W net s 50 22  9/27/23 Ideal Regenerative Rankine Cycle with Open Feedwater Heater 51 Ideal Regenerative Rankine Cycle with Closed Feedwater Heater 52 23  9/27/23 A Steam Power Plant With One Open and Three Closed Feedwater Heaters 53 Cogeneration Plants (CHP) The production of more than one useful form of energy (such as process heat and electric power) from the same energy source is called cogeneration. Cogeneration plants produce electric power while meeting the process heat requirements of certain industrial processes. The faction of energy that is used for either process heat or power generation is called the utilization factor of the cogeneration plant. 54 24  9/27/23 Cogeneration Plants (CHP) Applications: District Heating Pulp and paper mills Refineries Chemical Plants 55 An Ideal Cogeneration Plant Utilization Factor 𝑁𝑒𝑡 𝑤𝑜𝑟𝑘 𝑜𝑢𝑡𝑝𝑢𝑡 + 𝑃𝑟𝑜𝑐𝑒𝑠𝑠 ℎ𝑒𝑎𝑡 𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑒𝑑 𝜖" = 𝑇𝑜𝑡𝑎𝑙 ℎ𝑒𝑎𝑡 𝑖𝑛𝑝𝑢𝑡 𝑊"#$̇ + 𝑄%̇ 𝜖! = 𝑄&"̇ 56 25  9/27/23 Engineering Equation Solver (EES) Starting with EES version 10.364, keywords Steam, Water, Steam_IAPWS, and R718 all use the Steam_IAPWS property correlation. Steam_IAPWS implements high accuracy thermodynamic properties of water substance with the 1995 Formulation for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use, issued by The International Association for the Properties of Water and Steam (IAPWS). This correlation replaced the 1984 formulation of Haar, Gallagher, and Kell (NBS/NRC Steam Tables, Hemisphere Publishing Co., 1984) which is implemented in substance STEAM_NBS. The new formulation is based on the correlations of Saul and Wagner (J. Phys. Chem. Ref. Data, 16, 893, 1987) with modifications to adjust to the International Temperature Scale of 1990. The modifications are described by Wagner and Pruss (J. Phys. Chem. Ref. Data, Vol. 31, No. 2, 387, 2002). This correlation provides accurate results for temperatures between 273.15 K and 1273.15 K at pressures up to 1000 MPa. The formulation allows extrapolation of properties to 5000 K. Water also provides steam properties, but they use less accurate correlations which require significantly less computational effort. Use Steam or Water for the properties of ice at temperatures below 0 C based on ice property information from Hyland and Wexler, Formulations for the Thermodynamic Properties of the Saturated Phases of H2O from 173.15 K to 473.15 K, ASHRAE Trans., Part 2A, Paper 2793, 1983. Enthalpy and entropy values are referred to 0 for saturated liquid at 0 C. Example: 57 Sample Problem 2 Draw the flow diagram of a Rankine vapor cycle steam power plant. Steam engine drives 150-kW generator of 90% electrical efficiency. Steam rate, 6.7 kg/bhp-hr. Steam pressure, 10.55 k𝑔/𝑐𝑚' ga, 55.6C superheat; exhaust to condenser at 15.2 cm Hg abs. Feedwater enters the boiler as saturated liquid with a motor-driven boiler feed pump. Find the (a)Rankine efficiency, (b)brake thermal efficiency, and (c)combined efficiency. 58 26  9/27/23 Sample Problem 3 Consider a reheat-regenerative Rankine cycle with one open feedwater heater. The boiler pressure is 10 MPa, the condenser pressure is 15 kPa, the reheater pressure is 1 MPa, and the feedwater pressure is 0.6 MPa. Steam enters both the high- and low-pressure turbines at 500C. The turbines and pumps are 88% and 85% efficient, respectively. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a)the fraction of steam extracted for regeneration, and (b) the thermal efficiency of the cycle. 62 Sample Problem 4 Consider a cogeneration power plant modified with regeneration. Steam enters the turbine at 6 Mpa and 4500C and expands to a pressure of 0.4 MPa. At this pressure, 60% of the steam is extracted from the turbine, and the remainder expands to 10 kPa. Part of the extracted steam is used to heat the feedwater in an open feedwater heater. The rest of the extracted steam is used for process heating and leaves the process heater as a saturated liquid at 0.4 Mpa. It is subsequently mixed with the feedwater leaving the feedwater heater, and the mixture is pumped to the boiler pressure. Assuming the turbines and pumps are isentropic, (a)determine the mass flow rate of steam through the boiler for a net power output of 15 MW. If 5% of the steam extracted is used for process heating, (b)what is the energy used for this? 64 27  9/27/23 End of Lecture