Basic Calculations for a Power Plant

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Basic Calculations for a Power PlantPlantCalculating the Coal Quantity Written by: johnzactruba • Edited by: Lamar Stonecypher Published Oct 15, 2009 • Related Guides: Electricity How to make quick estimate of the coal required for running a power plant? This article describes a simple method. Very often, the Power engineer is required to perform some basic calculations regarding the key parameters of a power plant. Most important is the quantity and cost of fuel that is required.This article gives the simple calculation method. (A detailed calculation required in the context of a contract, tender, performance repor,t or a legal document may require more accurate input data.) We take the example of a 100 MW Coal Fired Power Plant.

Energy Content in Coal The basic function of the power plant is to convert energy energ y in coal to electricity. Therefore, the first thing we should know is how much energy there is in coal. Energy content of coal is given in terms of KiloJoules (kJ) per Kilogram (kg) of coal as the Gross calorific value (GCV) or the Higher Heating value (HHV) of coal. This value can vary from 10500 kJ/kg to 25000 kJ/kg depending on the quality and type of the coal. You should have an idea of the type of coal, or the source or mine from where the the plant gets the coal. Published data about the sources, mines, regions or the procurement data gives an idea about the HHV of coal. For this example we use a HHV of 20,000 kJ/kg. Best heat transfer www.dynovacn.com Top manufacturer, great price Hugh stocks, ordering now!

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Efficiency Energy conversion takes place in two stages. 

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The first part of the conversion is efficiency of the boiler and combustion. For this example we take 88 % on an HHV basis that is the normal range for a well-optimized power plant. Second part is the steam cycle efficiency. Modern Rankine cycle, adopted in coal fired power plants, have efficiencies that vary from 32 % to 42 %. This depends mainly on the steam parameters. Higher steam perssure and temperatures in the range of 600 ° C and 230 bar have efficiencies around 42 %. We assume a value of 38 % for our case. The overall conversion efficiency then is (38% x 88%) 33.44 %.

Heat Rate Heat rate is the heat input inpu t required to produce one unit un it of electricity. (1 kw hr) 

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One Kw is 3600 kJ/hr. If the energy conversion is 100 % efficient then to produce one unit of electricity we require 3600 kJ. After considering the conversion efficiency in a power p ower plant we require an heat input of (3600 / 33.44% ) 10765 kJ/ kw hr.

Coal Quantity 

Since coal has a heat value of 20,000 kJ/kg, for producing one kw.hr we require (10765 / 20000) 0.538 kg of coal. This translates to (0.538 x 100 x 1,000) 53800 kg/hr (53.8 T/hr) of coal for an output of 100 MW.

Coal Cost Basic cost of coal depends on the market conditions. Transportation costs, regional influences and government taxes are also part of the cost. Coal trader’s web sites give base prices in the international market.   

We take a coal price of around 65 $ / Ton. The cost of coal consumed by 100 MW power plant is (53.8 x 65) 3497 $ /hr A 100 MW unit produces 100,000 units of electricity. So the cost of coal per unit of electricity is (3497/100,000) 3.5 cents per unit.





Coal Fired Thermal Power Plant: The Basic Steps and Facts Written by: johnzactruba • Edited by: Lamar Stonecypher Updated Sep 8, 2011 • Related Guides: Carbon Dioxide | Steam | Electricity This article explains the basics of the working of a coal fired thermal power plant.

More than half of the electricity generated in the world is by using coal as the primary fuel. The function of the coal fired thermal power po wer plant is to convert the energy available in the coal to Electricity. Coal power plants work by using several steps to convert stored energy in coal to usable electricity that we find in our home that powers our lights, computers, and sometimes, back into heat for our homes. image provided by the Tennessee Valley Authority

How Coal Power Plants Produce Electricity The conversion from coal to electricity takes place in three stages. Stage 1

The first conversion of energy takes place in the boiler. Coal is burnt in the boiler furnace to





The second stage is the thermodynamic process. 1. The heat from combustion of the coal boils water in the boiler to produce p roduce steam. In modern power plant, boilers produce steam at a high pressure and temperature. 2. The steam is then piped to a turbine. 3. The high pressure steam impinges and expands across a number of sets of blades in the turbine. 4. The impulse and the thrust created rotates the turbine. 5. The steam is then condensed and pumped back into the boiler to repeat the cycle. Stage 3

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Ads by Google In the third stage, rotation of the turbine rotates the generator rotor to produce electricity based of Faraday’s Principle of electromagnetic induction. Check out this series describing the layout of thermal power plants. plants.

Key Facts About Coal-Fired Electricity Production In practice to effect these three stages of conversion, many systems and sub systems have to be in service. Also involved are different technologies, like combustion, aerodynamics, heat transfer, thermodynamics, pollution control, and logistics. As an example consider these facts for typical coal fired power plant of capacity 500 MW. 

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Around 2 million tons of coal will be required each year to produce the continuous power. Coal combustion in the boiler requires air. Around 1.6 million cubic meter of air in an hour is delivered by air fans into the furnace. The ash produced from this combustion is around 200,000 tons per year. Electrostatic precipitators capture almost all of this ash without dispersing this to the atmosphere. Pollutants from coal power plants like carbon dioxide, sulphur dioxide, and nitrogen oxide can also affect the environment. Thermal power plants are the biggest producers of Carbon Dioxide.





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Heat transfer from the hot combustion gases to the water in the boiler takes place due to Radiation and convection. The Electrical generators carry very large electric currents that produce heat and are be cooled by Hydrogen and water. The steam leaving the turbine is condensed and the water is pumped back for reuse in the boiler. To condense all the steam it will require around 50,000 cubic meter per hour of cooling water to be circulated from lakes, rivers or the sea. The water is returned to the source with only an increase of 3 to 4 degrees centigrade to prevent any effect to the environment. Apart from the cooling water the power plant also requires around 400 cubic meter me ter per day of fresh water for making up the losses in the water steam cycle.

Details of Generating Electricity from Coal These are some of the facts to highlight the complexities of the working of a Coal Fired Power Plant generating Electricity. For more details, discover how coal is blended to the right mix to maximize energy production or learn about the specific caloric energies of coal and how moisture in the coal can affect a power plant's efficiency. Also learn how the coal is prepared to be fired in the boiler. boiler. You may also learn about the parts of a thermal power plant and site selection.

General Layout of a Thermal Power Plant Written by: Ricky • Edited by: Lamar Stonecypher Published Jan 22, 2009 • Related Guides: Generating Electricity





Introduction With the world on a development spree, there is shortage of power in most places whilst the demand seems to be in a never ending upward spiral. There are several answers to this challenge such as the nuclear power plants, but the conventional thermal power plants also play an equally important role in this power equation. Learn about these power plants in this article.

General Layout of the Plant Though each plant is unique in itself in terms of specific features and functionalities, still there is a broad outline to which all thermal power plants confirm to and in this article we will study about the general layout of a typical power plant. There are four main circuits in any thermal power plant and these are 1. Coal & Ash Circuit – this circuit deals mainly with feeding the boiler with coal for combustion purposes and taking care of the ash that is generated during the combustion process and includes equipment and paraphernalia that is used to handle the transfer and storage of coal and ash. 2. Air & Gas Circuit – we know that air is one of the main components of the fire triangle and hence necessary for combustion. Since lots of coal is burnt inside the boiler it needs a sufficient quantity of air which is supplied using us ing either forced draught or induced draught fans. The exhaust gases from the combustion are in turn used to heat the ingoing air through a heat exchanger before being let off in the atmosphere. The equipment which handles all these processes fall under this circuit. 3. Feed Water & Steam Circuit – this section deals with supplying suppl ying of steam generated from the boiler to the turbines and to handle the outgoing steam from the turbine by cooling it to form water in the condenser so that it can be reused in the boiler plus making good any losses due to evaporation etc. 4. Cooling Water Circuit – this part of the thermal power plant deals with handling of the cooling water required in the system. Since the amount of water required to cool the outgoing steam from the boiler is substantial, subs tantial, it is either taken from a nearby water source so urce such as a river, or it is done through evaporation if the quantity of cooling water available is limited. Operation and Maintenance www.armstronginternational.com Reach energy cost reduction goals and improve utility efficiency.

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The above breakdown of the plant would give you a clear idea about the components of the plant but a complete picture shown below would be more useful in getting an idea how these circuits are integrated together to form the complete power powe r plant.

References Image of Power Plant Layout: Arora, S.C. & Domkundwar, S. (1993) A Course in Power Plant Engineering. Delhi: Dhanpat Rai & Sons.

Proper Site Selection for a Thermal Power Plant





an optimum mix of the requirements for the settings to be feasible for long term economic justification of the plant.

The Requirements for the Site As the name implies the power plant is meant for generating power which obviously means that it will consume huge quantities of fuel. The exact quantity would depend on the size of the plant and its capacity but it is a general fact that ample quantities of o f fuel must be available either in the vicinity or it should be reasonably reason ably economical to transport the fuel till the power plant. Since most thermal power plants use coal (they can use other fuels as well) it must be ensured that sufficient coal is available round the clock. Just to give you a rough idea a power plant with 1000 MW capacity approximately would require more than ten thousand tons of coal per day hence the necessity for continuous supply and storage capability of coal in the power station. Tailored BriquetteMachine www.cbmjx.com/Briquette-Machine Wood, Charcoal, Agro & Forest Waste For Making Briquettes & Pallets

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As we saw in the previous p revious article of this series, large amount of water is required for cooling purposes in the power plant hence it is better if such a source is available nearby in the form of rivers etc. Apart from these major requirements there are also other requirements which are equally important such as the availability of skilled people to work for the plant and good transport facilities in the vicinity. Hence we see that setting up a thermal power plant requires a lots of factors to be considered simultaneously.

Basic Calculations for a Power Plant

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