• Ntpc Turbine Operation Manual

At present 54.09% or 93918.38 MW (Data Source CEA, as on ) of total electricity production in India is from Coal Based Thermal Power Station. A coal based thermal power plant converts the chemical energy of the coal into electrical energy. This is achieved by raising the steam in the boilers, expanding it through the turbine and coupling the turbines to the generators which converts mechanical energy into electrical energy. Introductory overview In a coal based power plant coal is transported from coal mines to the power plant by railway in wagons or in a merry-go-round system. Coal is unloaded from the wagons to a moving underground conveyor belt. This coal from the mines is of no uniform size. So it is taken to the Crusher house and crushed to a size of 20mm.

From the crusher house the coal is either stored in dead storage( generally 40 days coal supply) which serves as coal supply in case of coal supply bottleneck or to the live storage(8 hours coal supply) in the raw coal bunker in the boiler house. Raw coal from the raw coal bunker is supplied to the Coal Mills by a Raw Coal Feeder.

The Coal Mills or pulverizer pulverizes the coal to 200 mesh size. The powdered coal from the coal mills is carried to the boiler in coal pipes by high pressure hot air. The pulverized coal air mixture is burnt in the boiler in the combustion zone. Generally in modern boilers tangential firing system is used i.e. The coal nozzles/ guns form tangent to a circle. The temperature in fire ball is of the order of 1300 deg.C.

The boiler is a water tube boiler hanging from the top. Water is converted to steam in the boiler and steam is separated from water in the boiler Drum. The saturated steam from the boiler drum is taken to the Low Temperature Superheater, Platen Superheater and Final Superheater respectively for superheating. The superheated steam from the final superheater is taken to the High Pressure Steam Turbine (HPT).

In the HPT the steam pressure is utilized to rotate the turbine and the resultant is rotational energy. From the HPT the out coming steam is taken to the Reheater in the boiler to increase its temperature as the steam becomes wet at the HPT outlet.

After reheating this steam is taken to the Intermediate Pressure Turbine (IPT) and then to the Low Pressure Turbine (LPT). The outlet of the LPT is sent to the condenser for condensing back to water by a cooling water system.

This condensed water is collected in the Hotwell and is again sent to the boiler in a closed cycle. The rotational energy imparted to the turbine by high pressure steam is converted to electrical energy in the Generator. Diagram of a typical coal-fired thermal power station Principal Coal based thermal power plant works on the principal of Modified Rankine Cycle. Components of Coal Fired Thermal Power Station:. Coal Preparation i) Fuel preparation system: In coal-fired power stations, the raw feed coal from the coal storage area is first crushed into small pieces and then conveyed to the coal feed hoppers at the boilers. The coal is next pulverized into a very fine powder, so that coal will undergo complete combustion during combustion process. Live Storage (boiler room storage): storage from which coal may be withdrawn to supply combustion equipment with little or no remanding is live storage.

This storage consists of about 24 to 30 hrs. Of coal requirements of the plant and is usually a covered storage in the plant near the boiler furnace. The live storage can be provided with bunkers & coal bins.

Bunkers are enough capacity to store the requisite of coal. From bunkers coal is transferred to the boiler grates. Dead storage- stored for future use. Mainly it is for longer period of time, and it is also mandatory to keep a backup of fuel for specified amount of days depending on the reputation of the company and its connectivity. There are many forms of storage some of which are –.

Stacking the coal in heaps over available open ground areas. But placed under cover or alternatively in bunkers. Allocating special areas & surrounding these with high reinforced concerted retaking walls. Boiler and auxiliaries. A Boiler or steam generator essentially is a container into which water can be fed and steam can be taken out at desired pressure, temperature and flow. This calls for application of heat on the container.

For that the boiler should have a facility to burn a fuel and release the heat. The functions of a boiler thus can be stated as:-. To convert chemical energy of the fuel into heat energy. To transfer this heat energy to water for evaporation as well to steam for superheating. The basic components of Boiler are: -. Furnace and Burners.

Steam and Superheating a. Low temperature superheater b. Platen superheater c. Final superheater. Economiser It is located below the LPSH in the boiler and above pre heater. It is there to improve the efficiency of boiler by extracting heat from flue gases to heat water and send it to boiler drum.

Advantages of Economiser include 1) Fuel economy: – used to save fuel and increase overall efficiency of boiler plant. 2) Reducing size of boiler: – as the feed water is preheated in the economiser and enter boiler tube at elevated temperature. The heat transfer area required for evaporation reduced considerably. Air Preheater The heat carried out with the flue gases coming out of economiser are further utilized for preheating the air before supplying to the combustion chamber.

It is a necessary equipment for supply of hot air for drying the coal in pulverized fuel systems to facilitate grinding and satisfactory combustion of fuel in the furnace. Reheater Power plant furnaces may have a reheater section containing tubes heated by hot flue gases outside the tubes. Exhaust steam from the high pressure turbine is rerouted to go inside the reheater tubes to pickup more energy to go drive intermediate or lower pressure turbines. Steam turbines Steam turbines have been used predominantly as prime mover in all thermal power stations. The steam turbines are mainly divided into two groups: -. Impulse turbine. Impulse-reaction turbine The turbine generator consists of a series of steam turbines interconnected to each other and a generator on a common shaft.

There is a high pressure turbine at one end, followed by an intermediate pressure turbine, two low pressure turbines, and the generator. The steam at high temperature (536 ‘c to 540 ‘c) and pressure (140 to 170 kg/cm2) is expanded in the turbine. Condenser The condenser condenses the steam from the exhaust of the turbine into liquid to allow it to be pumped. If the condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of the cycle increases. The functions of a condenser are:- 1) To provide lowest economic heat rejection temperature for steam.

2) To convert exhaust steam to water for reserve thus saving on feed water requirement. 3) To introduce make up water. We normally use surface condenser although there is one direct contact condenser as well. In direct contact type exhaust steam is mixed with directly with D.M cooling water. Boiler feed pump Boiler feed pump is a multi stage pump provided for pumping feed water to economiser. BFP is the biggest auxiliary equipment after Boiler and Turbine. It consumes about 4 to 5% of total electricity generation.

Cooling tower The cooling tower is a semi-enclosed device for evaporative cooling of water by contact with air. The hot water coming out from the condenser is fed to the tower on the top and allowed to tickle in form of thin sheets or drops. The air flows from bottom of the tower or perpendicular to the direction of water flow and then exhausts to the atmosphere after effective cooling. The cooling towers are of four types: - 1.

Natural Draft cooling tower 2. Forced Draft cooling tower 3. Induced Draft cooling tower 4. Balanced Draft cooling tower. Fan or draught system In a boiler it is essential to supply a controlled amount of air to the furnace for effective combustion of fuel and to evacuate hot gases formed in the furnace through the various heat transfer area of the boiler.

This can be done by using a chimney or mechanical device such as fans which acts as pump. I) Natural draught When the required flow of air and flue gas through a boiler can be obtained by the stack (chimney) alone, the system is called natural draught. When the gas within the stack is hot, its specific weight will be less than the cool air outside; therefore the unit pressure at the base of stack resulting from weight of the column of hot gas within the stack will be less than the column of extreme cool air. The difference in the pressure will cause a flow of gas through opening in base of stack.

Also the chimney is form of nozzle, so the pressure at top is very small and gases flow from high pressure to low pressure at the top. Ii) Mechanized draught There are 3 types of mechanized draught systems 1) Forced draught system 2) Induced draught system 3) Balanced draught system Forced draught: – In this system a fan called Forced draught fan is installed at the inlet of the boiler. This fan forces the atmospheric air through the boiler furnace and pushes out the hot gases from the furnace through superheater, reheater, economiser and air heater to stacks. Induced draught: – Here a fan called ID fan is provided at the outlet of boiler, that is, just before the chimney. This fan sucks hot gases from the furnace through the superheaters, economiser, reheater and discharges gas into the chimney. This results in the furnace pressure lower than atmosphere and affects the flow of air from outside to the furnace. Balanced draught:-In this system both FD fan and ID fan are provided.

The FD fan is utilized to draw control quantity of air from atmosphere and force the same into furnace. The ID fan sucks the product of combustion from furnace and discharges into chimney. The point where draught is zero is called balancing point. Ash handling system The disposal of ash from a large capacity power station is of same importance as ash is produced in large quantities. Ash handling is a major problem. I) Manual handling: While barrows are used for this. The ash is collected directly through the ash outlet door from the boiler into the container from manually.

Ii) Mechanical handling: Mechanical equipment is used for ash disposal, mainly bucket elevator, belt conveyer. Ash generated is 20% in the form of bottom ash and next 80% through flue gases, so called Fly ash and collected in ESP. Iii) Electrostatic precipitator: From air preheater this flue gases (mixed with ash) goes to ESP. The precipitator has plate banks (A-F) which are insulated from each other between which the flue gases are made to pass. The dust particles are ionized and attracted by charged electrodes.

The electrodes are maintained at 60KV.Hammering is done to the plates so that fly ash comes down and collect at the bottom. The fly ash is dry form is used in cement manufacture. Generator Generator or Alternator is the electrical end of a turbo-generator set. It is generally known as the piece of equipment that converts the mechanical energy of turbine into electricity. The generation of electricity is based on the principle of electromagnetic induction. SUBJECT- SCALEBAN:: History created at NTPC by installing our patented product in 500MW power plant to achieve ZERO DISCHARGE WITH ZERO SCALING in cooling water system.

Dear Sir, We are proud in all our modesty to inform your good self that we have successfully commissioned the ‘SCALEBAN’ in the 500MW power plant of one of the leading and most reputed power producer of the world i.e. NTPC at their Dadri (U.P.) unit (Please find attached photographs for the same). The installation in the other 500MW power plant will be done in the month of October 2014 during the proposed maintenance shutdown of the concerned power plant. You will be pleased to note that M/s NTPC limited have placed an order for the supply of Scaleban equipment for the condenser and auxiliary system of 500MW X 2Nos power plant at Dadri (U.P.) on 06thNovember 2013.

M/s NTPC limited has installed Scaleban equipment in their power plant with an objective to operate the cooling tower at a very high COC level of 15 with zero scaling in condenser and other heat exchangers. Currently, they are operating the cooling tower at 2.5COC and yet facing a severe problem of scale deposition in the system. This is the biggest achievement in the history of Scaleban equipment, as the most reputed power producer of the country has joined hands with us to establish the sustainable, most efficient and cost effective solution for zero discharge with zero scaling. NTPC, after gaining confidence in our technology through in depth study of theoretical aspects and in situ analysis of the performance of the equipment at our client site has joined us in our mission to conserve water with zero scaling. The prevailing situation is quite alarming and dictates to the power industry to switch over to the sustainable & efficient means of the water conservation with zero scaling to achieve zero liquid discharge. The industry is very well familiar with the prevalent losses in productivity and profitability due to zero discharge norms and scale deposition in condensers & other heat ex-changers. It is evident that conventional methods for stopping scale deposition in heat ex-changer surfaces are not efficient enough to target this specific problem of the industry.

Also the conventional methods available to achieve zero liquid discharge (ZLD) are very costly to establish and operate and so we are encouraged to present our revolutionary technology to help the industry stakeholder to get Scale free condenser/heat ex-changer and to design most efficient, cost effective and sustainable solution for Zero Liquid Discharge (ZLD). The cooling tower can be operated at very high COC of 15 to 20 as against 3 to 5 of conventional methods. Operations at higher COC will lead to minimization of blow down to almost negligible. There is lot of water conservation involved with use of Scaleban Technology. Practically, uses of Scaleban equipment can conserve water to the tune of more than 25% to 30%. Consumption of fresh water can be brought down by 100% as RO reject and ETP treated water can be directly utilized in cooling tower as make up water instead of soft water.

Ntpc Turbine Operation Manual

Thus Scaleban has initiated a march towards establishment of a cost effective, most efficient and sustainable solution for the achievement of zero liquid discharge with water conservation and zero scaling. Most importantly, Scaleban provides guaranteed zero scale condition in the condenser and other heat exchangers for a period of 20 years without use of Soft water and anti scalant chemicals. Scale free condensers leads to constant vacuum and specific steam consumption maintained in specified ideal range.

The product is manufactured by State of the Art technology which keeps the product a step ahead of all the other kind of water treatment technologies available in market. Scaleban with no reject of water is the maintenance free mechanical equipment and does not require any energy input for its operation. We have proved ourselves in the conservation of water to the tune of more than 25% and also in increasing industry productivity and profitability for our (150+) valuable clients across India. Both, water and energy are the main area of concern for the industries now a days and no one in the world is able to create them; “conserving them is the only way to create them”.

Scaleban can proudly claim the maximum conservation of water and energy on account of use of this revolutionary equipment as compared with any other technology available in the world. Scaleban is awaiting a Patent Number from Office of Controller General of Patents, Designs and Trademarks (Intellectual Property India), Mumbai, Government of India, pending our application number 2335/MUM/2009 dated 7th October 2009. One of the most apt and brisk synopsys of a thermal power plant i have ever read. The two diagrams at the start of modified rankine cycle and the plant over view are the highlights.

Great work sir. You have proved a valid point again that simple logics are more important than unrequired expertise. I would be very impressed if u could also add on super critical technology and once through boilers which use a seperator rather than the conventional circulation type boilers. Also some some point missing are gland steam cooler and also a note on water technology. But all together great work. The Delhi government is toying with the idea of permanently shutting down the Rajghat power plant close by june this year. The plant was earlier closed during the Commonwealth Games to remove the polluting unit in the heart of the city, and provide to residents a recreational area in its place.The power station, situated in northeast Delhi, is one of the coal-based power plants of Indraprashta Power Generation Co.

(IPGCL) and has a generation capacity of 135 MW.The power plant was commissioned in 1989 and supplied 135 MW. The Delhi State Industrial and Infrastructure Development Corporation (DSIIDC) had been asked to prepare a blueprint for “adaptive reuse”, and the agency presented its proposal in front of Chief Minister Sheila Dikshit and other officials on Wednesday. Dikshit has given in-principle approval to the project, which will require several clearances before it can begin. It will now be presented to the DDA and the DUAC. The project will take about 3 to 4 years to be implemented.“Cost of the project is close to Rs 600 crore. It will be a self financing project as power plant equipment will be sold off and also the office space developed inside the plant will be rented out.

Rajghat power plant is spread over 46 acre and as per the DSIIDC proposal, 26 acre will be turned into a city forest. The ash pond inside the plant will be enlarged and converted into a waterbody.

The soil there is contaminated due to ash depositing here over the years so it would be cleaned before work starts.The existing waterbody, which is used by the power plant, will be retained and redeveloped. The plan is to have the forest and the waterbody close to the Salimgarh Fort so that the area can be developed as a tourist spot.

The area where coal handling was done will be converted into a garden and the main building of the plant will be converted into office space. “We will not touch the outer structure or the envelope of the building. 3l toyota diesel engine. The only changes will be in the interior of the building. Also, demolishing the existing structure will cost more than retrofitting it,” said the official. This is the second power plant site that the government is redeveloping – retrofitting of the Indraprastha Power plant is already underway. Its equipment has already been auctioned.