Module 1

[Audio] Hello . Please accept greetings from STARKEN Academy. We are planning to provide basic knowledge related to the Natural Gas distribution business , with more focus on the practical aspects which will equip you with necessary information and knowledge of this business . This course is designed by experts having vast experience of various areas of City Gas Distribution business. The focus of the course material is to provide more realistic learning in a simple way..

[Audio] To begin with , kindly go through the basic hydrocarbon series given in the slide. It covers the chemical formula and name of the hydrocarbons..

[Audio] Now Let's first understand what is natural gas. Natural gas is mixture of gases naturally occurring beneath earth's surface . It is mixture of many gases but predominant are hydro carbon gases. The natural gas used commercially through pipelines is majority of Methane. Natural gas is taken out from earth's sub surface by drilling holes in earth till the source of natural gas. Source of gas can be on land or in deep seas. Modern drill rigs are used to drill holes..

[Audio] There are many types of Natural gases known with different terminologies. When gas is present along with liquid hydrocarbons, it is known as associated gas. When the gas is free of liquids, it is known as dry gas. When natural gas is containing harmful gases like hydrogen sulphide , it is known as sour gas. Harmful gases are removed by various techniques like hot and cold flaring or scrubbing etc. Dry gas without harmful gases ready for use is known as sweet gas..

[Audio] Apart from natural gas , there are many more gases used for various applications by different industries. It is useful to know about some of them. Let's know about them. First is LPG : The next one is Synthetic Gas : Next is Substitute gas : LNG : Next is Natural Gas liquids (NGL) Last one is Dissolved Gases.

[Audio] Now let's see important properties of few hydrocarbon gases. You can refer the table given in the slide to study important properties and compare them with each other. As can be seen in the table , Methane is the lightest of the gases . Since natural gas is predominantly methane , It is lighter than air also which allows it to mix with air very easily and effectively . Combustion efficiency of natural gas is very good compared to other fuels. Being lighter than air makes it safer to use as it disperses away in the atmosphere in case of leakages..

[Audio] Here , we would like to share some important technical information which will be helpful for some of the topics which we will cover later in this course. It is suggested that you should keep these information in your mind as ready reckoner..

[Audio] After learning about basics of Natural Gas , we move to very important laws based on which gas engineering is developed. These laws are Boyle''s Law , Chaarles Law and universal gas law. The Boyle's law explains the relationship between the Pressure and Volume at constant temperature. It states that if temperature remains constant , volume of gas reduces in proportion to the increase in pressure. Many formulas for designing gas pipeline and other calculations are based on this important theory. Similarly, the Charles law states that if pressure remains constant , the volume of gas increases in proportion to the temperature of gas..

[Audio] Now as we have learnt about Boyle's and Charles gas laws, we pay attention to the universal gas law derived from these two laws and it also includes some other important parameters. You are requested to study the equation given on the slide and understand the relationship between some important parameters. Proper understanding of this equation will be very useful in the subsequent course material we are going to learn ..

[Audio] Now let's move our attention to one of the very important property of Natural Gas . It is the gas density. Density of Natural gas at standard conditions is the weight of the gas in kg per volume of the gas in meter cube at standard condition. Depending upon the presence of various hydrocarbons in gas , density of the natural gas will vary. Density will be more if proportion of higher hydrocarbons is more. Specific gravity of natural gas is ratio of natural gas density to the air density and is unit less..

[Audio] To understand calculation of gas density in a proper way , we will calculate density of a particular quality of natural gas. As you can see in the slide , first we need to calculate molecular weight contribution of each hydro carbon. From that , molecular weight of the gas is derived. Taking this value of molecular weight and values of temperature , pressure and compressibility factor at standard conditions , density is calculated . Density of Air at standard condition is 1.16 Kg per meter cube . By dividing the air density with the air density , specific gravity of the gas is calculated..

[Audio] Now we will know some important points related to the next very important aspect of gas engineering and that is combustion of Natural Gas. Please look at the diagram in the slide. For combustion to take place , fuel , oxygen and source of heat is required. When these three elements are shown in form of a triangle, it is known as combustion triangle. Oxygen is introduced in form of air as air contains 21 % of oxygen by weight. For combustion to take place , these three elements in right proportion are required. The ratio of amount of air and fuel ,at which the fuel burns completely and no shortage of oxygen is there for combustion , is known as stoichiometric ratio. When fuel and air mixture burns , Carbon Dioxide and water vapours are generated. Insufficient air can produce harmful gases like carbon monoxide and nitrogen oxide..

[Audio] To understand the concept of stoichiometric mixture for methane , we have one example and its calculation in the slide. Air is represented by 21% oxygen and 79% nitrogen on weight basis. Weight of air required for burning methane is calculated and from that the Air to Fuel ratio by volume is also calculated. Please go through the example carefully and do your own calculation of Ethane for practice..

[Audio] Now we will learn about the calorific value of natural gas. This is one of the most important properties of the natural gas and used to estimate natural gas requirements for various applications. Calorific value for any gas is basically the units of heat energy liberated by complete combustion of gas at standard conditions. It is generally expressed in Kilo Calorie per meter cube. There are two types of calorific values. One is net calorific value – NCV and the other is gross calorific value – GCV as explained in this slide. Gross Calorific Value for Natural Gas is generally 5 to 10 % higher as per its composition. Net calorific value is considered for energy calculations ..

[Audio] In this section, we will learn basic things about the gas burners. Gas burner is a device which facilitates combustion by making proper mixture of fuel and air and then releasing the mixture correctly to the source of ignition to ensure that heat of combustion is available for utilisation. When air is mixed with the natural gas before combustion is known as primary gas. The air which is available for burning in the combustion region is known as secondary air. Air is mixed with gas naturally or it is provided by fan or blower in case of higher capacity burners. Quantity of gas required to activate stoichiometric combustion is ensured by controlling the gas pressure..

[Audio] Now we will describe key components of a gas burner. This will help you to understand gas burners more closely. As you can see in the drawing , the main components of a gas burner are Gas Jet , hole for primary aeration , mixing tube , burner ports and gas coke or gas valve. Gas jet ensures proper release of gas to mixing tube through hole of calculated diameter. The primary hole drilled in the mixing tube allows estimated quantity of primary air to enter in the mixing tube. Mixing tube is a long tube which is designed to ensure proper mixing of fuel and air. Burner ports are the ports drilled in the burner through which mixture of gas and air is released to combustion region. Gas Coke or gas valve is the device which controls the gas quantity..

[Audio] In this slide , you can see three types of burners classified on the basis of method of aeration. As shown in the figure , the first burner is fully aerated burner where total quantity of air is provided with the gas and there is no secondary air. The next burner is partially aerated burner where total air is provided by both primary and the secondary air. The third type of burner is non-aerated burner , where total quantity of air is provided as secondary air. There is no primary air mixed with the gas. Depending upon the type of aeration , we get the flame characteristics as shown in the figures..

[Audio] We will now learn about the two basic parameters of gas burners which ultimately determines the burner performance. The first parameter is the primary aeration. Primary aeration determines the flame characteristics. The other parameter is port loading. It is the total heat energy provided divided by the total port area. To get good flame characteristics , port loading shall be maintained at around 20,000(BTU/Hr)/Sq.inch or 7.78 Kilo Calorie per hour pr square millimetre. More or less than required primary aeration or port loading results in flame lifting , flash back , yellow tipping or improper ignition..

[Audio] To understand the primary calculations for simple burner design, an illustration is given in this slide. This will make you all understand basics of burner design , though, complex burner designs involve many more calculations. Kindly go through the illustration and try to make calculations yourself. It shows practical aspects of deciding nos. of ports of a burner..

[Audio] Now we will go through varieties of gas burners. 4 types of burners are described in this slide. The first type of burner is the ring type of burner , generally used in house holds and restaurants. The next one is the multi jet multi port burners used in commercial application. This type of burners can give high heat output with lower gas pressure. The next one is the simplest kind of gas burner known as Bunsen burne with single jet and single port having low heat output and used by jewellers and researchers. The last type is high capacity burners used in industrial applications with very high requirement of heat. They are generally equipped with control system and arrangement for injecting higher quantities of primary air using blowers..

[Audio] Till now we have learnt about the natural gas and its combustion. Before ending this module of the course , we would like to describe the basic gas value chain. As you can see , the gas value chain has three streams. The first one is associated with gas production known as upstream. Depending upon the gas field characteristics , such facilities can contin gas conditioning and compression for further commercial dealings. The next stream is called midstream which either involves gas processing and transportation by pipelines to the next commercial sale or liquefaction to make LNG and transportation by cryogenic ships. The gas transported by pipelines or in form of LNG are further filtered or evaporated for commercial sale and this stream is known as downstream..

[Audio] Before we end this first module of the entire course , we would like to make you aware of the versatility of Natural Gas as fuel by describing its variety of usages in different sectors. You can go through the list of applications given in the slide and make your own list of natural gas usages which is not covered in this list. We think that by now you must have learnt the basics of Natural gas and its combustion. We will cover various areas of the City Gas Distribution ( part of downstream ) business in more depth in the coming modules of this course. The coming modules will give you required knowledge of the city gas distribution business in a simple , practical and effective way. So let's meet in the next modulewhich will be on network planning and design..