STEAM BOILER Thermodynamics OBJECTIVES To examine the relationship between pressure and temperature in a saturated steam with a constant volume. Identify the working mechanism of a steam boiler. INTRODUCTION In thermodynamics we can learn energy transfer. Using this experiment, we can also understand the main properties of saturated steam for an overheated moment. . Energy can be referred to heat and work and this transferring happens when the system undergoes a certain number of steps which is knows as a process. . This Marcet boiler has been developed in order to investigate the relationship between pressure and the temperature of saturated steam which is in equilibrium with water. The Marcet boiler is also equipped with a thermometer, barometer and safety valve. THEORY Marcet boiler is used Review the relationship between pressure and the temperature of saturated steam. there are three factors we discussed. • • • Volume (V) Absolute pressure(P) Absolute Temperature(T) PV=nRT Where, P =Absolute pressure V =Volume n =Amount of substance (moles) R = Ideal gas constant (8.314 J / (mol·K) T =Absolute temperature K(Kelvin) Reading No: 01 02 03 04 05 06 07 08 Steam Pressure (kg/ cm2) 4.3 4.5 4.7 4.9 5.1 5.3 5.5 5.7 Temperature (℃) 109.1 109.7 110.6 114.2 118.8 124.1 128.5 133.8 DISCUSSION 1. An introduction to boilers and type of boilers. Types of boilers In the industry, there are different types of boilers and its use for different applications. Mainly there are two types of boilers. 1) Fire tube boilers or (Shell and tube boilers) 2) Water tube boilers The boiler is the device which can generate the steam with high pressure. The boiler is an enclosed vessel that provides a means for combustion and transfer heat to water until it becomes hot water or steam. The hot water steam under pressure is then usable for transferring. The heat to a presses The heating surface is any part of the boiler hot gasses of combustion are an one side and water on other. Any part of the boiler metal that actually contributes to making steam is heating surface. The amount of heating surface of a boiler in expressed in square meters. The larger heating surface a boiler has the more efficient it becomes. The boiler system is made up of feed water system, steam system and fuel system. The feed water system provides water to the boiler and regulates it automatically to meet the steam demand. The steam system collects and controls the steam provides in the boiler. Steam is directed through a piping system to the point of use. The fuel system includes all equipment used to provide fuel to generate the necessary heat. The equipment’s requires in the fuel system. There are two general types of boilers. There are fire tube and water tube. Boilers are classified as high pressure or law pressure and steam boiler or hot water boiler. A fire tube boiler is a type of boiler in witch hot gasses pass from a fire through one or more tubes running through a sealed constrainer of water. The heat of the gasses is transferred through the walls of the tubes by thermal conditions, heating the water and ultimately creating steam. There are different types of fire tube boilers. They are Cornish boiler, Lancashire boiler, Locomotive boiler etc. A water tube boiler is a type of boiler in witch water circulates in tubes heated extremely by the fire. Fuel is burned inside the furnace, creating hot gas which heats water in the steam generating tubes. There are some design variations in water tube boilers. They are D type boiler, M-type boiler, Low water content boiler etc. Types of boilers In the industry, there are different types of boilers and its use for different applications. Mainly there are two types of boilers. 1) Fire tube boilers or (Shell and tube boilers) 2) Water tube boilers 2. Explain the operation of a boiler Boiler design is the process of the designing boilers used for various purposes. Simply boiler is device which is produced the steam. The main function of a boiler is to heat water to generate heated steam. The boiler is a closed vessel where water is stored inside. The kinetic energy produced by the steam use to perform the required work. Steam produced in a boiler can be used for a variety of proposes including space heating , sterilization, drying, humidification and power generation. The temperature or condition of steam required for these application is difference, so boiler designs vary accordingly. The main compliments at the boiler system include the feed water heaters, delegators, feed pumps, economizers, superheats, condenser and condensate pumps. In addition there are sets of controls to monitor water and steam flow, fuel flow and chemical composition of the air and steam. The feed water systems in composed of two sources of water that deliver water to the boiler to be converted into steam. The feed water consists of the condenser return water and treated make up water. Feed water heaters extract the west heat from the spent steam to per heat the boiler feed water. Preheating the boiler feed water increases the boiler efficiently by decreasing the energy required to heat the water to steam. Boiler feed water often contains dissolved oxygen. The desecrator mechanically removes the oxygen by passing steam through the feed water heater. The economizer is the last component of the feed water system. The economizer extracts heat from the exhaust gas to heat the steam to further improve boiler efficiently. Feed water entries the boiler through the economizer and rises as the steam to the steam drum, where the water and steam are separated. The lover drum, called the mud drum, is tank at the bottom of the boiler that regulates water distribution and collects sentiment or corrosion products for later removal. Safety of the boilers Safety measures are very important things for any kind of machines. The boiler is a major part of the steam system. And also some kind of dangerous part of the system. Because boilers are operating in high temperature and high pressure. If there may be some safety issues, it will be dangerous. Because it has a risk of explosion, high pressure steam, moving parts, hot surfaces and etc. so, boiler operator is a very responsible man and must be well trained person. He has some safety measures which should be followed to prevent dangerous accidents. Recommended water level should be maintained. Recommended temperature and the pressure should be maintained Safety valves should be always checked before starting the machine. Water which is used to generate steam, must be treated. Because, the impurities in raw water might cause corrosion and efficiency of the machine. The operator must wear safety cloths. The manufacturer’s instructions should be strictly followed. 4. Relationship between the pressure and temperature of saturated steam In the theoretical explanation, PV=nRT is the equation for ideal gases. According to the ideal gas law, specific volume for a specific quantity of gas, the pressure is directly proportional to the temperature. So the slop (𝑑𝑃𝑑𝑇) should be constant. But in the real life, the real gases does not obey for the ideal gas low and the pressure is not directly proportional to the temperature. In the real gas, (𝑃+n^2/𝑉^2)(𝑉−𝑛𝑏)=𝑛𝑅𝑇 gives the relationship with pressure and temperature. Where, P = measured pressure V = volume of container n = moles of gas R = gas constant T = temperature The phenomena of increasing pressure with temperature can be explained as, when the heat energy is supplied to water, the water practical move faster and therefor more steam partials are generated. As the boiler is a closed vessel, as more as steam is generated inside the vessel, steam must generate more pressure. Considering the results obtained from the practical. 5. Introduction to Steam plants Steam power plant is the power station which generate the electricity by using steam. Steam or Thermal power plant are becoming a future trends in the modern world. In the steam power plants, mostly used coal as an energy to generate the steam. Boiler is the device which is used to generate the steam. We can basically say that in Steam/Thermal power plants heat is being converted in to electrical power. In most parts of the world turbines are steam driven. What basically happens in these kind of plants is Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankin cycle CONCLUSION: In this lab session, the theory of the thermodynamics, theories applicable situations and the relationship between pressure and the temperature and about boilers was understood and got practical experience. Furthermore, we got idea about industrial applications of boilers and their functionalities, and safety measures and etc.