ASH UTILISATION IN NTPC DADRI

Submitted in partial fulfilment for the degree of Bachelors of Business Administration

Under guidance of

Mrs Renu

SUBMITTED BY:

Ruchi Verma

0281341706

IDEAL INSTITUTE OF MANAGEMENT AND TECHNOLOGY,DELHI

ACADEMIC YEAR: 2006-2009

CERTIFICATE

This is to certify that Ruchi Verma of BBA has done this project under my supervision. She has taken interest and shown sincerity in completion of her project file of “ASH UTILIZATION IN NTPC DADRI” to my full satisfaction.

Mrs. RENU

INTRODUCTION :

From time immemorial ,great Indian philosophers , thinkers & saints have emphasized the need for conserving natural resources & using them wisely . But , with the leaps that science has taken in the modern times , and coupled with man’s greed for power , prosperity and prestige , man has done untold damage to the environment. He has used development as a means to exploit nature to its maximum , not caring a bit for the damage it has done & is doing to the humanity. The damage that has been done to the ecosystem & biological diversity is impossible to assess .

Fortunately , it is now being realized all over the world that man’s greatest need at this hour is to save the planet & it’s inhabitants . People have now realized that progress in science & technology should keep pace with sustainable development. Emphasis should be laid on minimum consumption so that we leave a healthy & joyful life for our future generations .

Industrial discharges are important cause of pollution as the pollutants introduced by the industries are at such high levels that the ecosystem cannot dissipate them or decompose them .

Industries thus have a paramount role in rethinking their processes , evaluating the impact on the environment & coming up with innovative techniques to mitigate the damage being made .

OBJECTIVE :

Amongst the various type of industries operating , thermal power plants are considered to be a major source of environment hazard .

In our country , NTPC Ltd. is the biggest power major , thus with this view in mind , it was decided to carry out our study at NTPC , to assess

The environment issues / challenges being confronted

The existence of a well defined environment policy

The implementation of it’s strategies to achieve the desired environmental goals .

To carry out the study , a visit was made to Dadri plant of NTPC , which is treated as a model plant as far as environment management is considered . During the visit attention was concentrated on ASH as a pollutant and thus primarily focussing on the ash generation , its collection , disposal & other utilization practices .

ENVIRONMENT MANAGEMENT

Harmony between man and environment is the essence of healthy life and growth. Therefore, maintenance of ecological balance and a pristine environment has been of utmost importance to the Union Ministry of Power (MoP). NTPC being the leading organization under the ministry in the areas of power generation, has been taking various measures discussed below for mitigation of environment pollution due to power generation.

Environment Policy & Environment Management System

Driven by its commitment for sustainable growth of power, NTPC has evolved a well defined environment management policy and sound environment practices for minimising environmental impact arising out of setting up of power plants and preserving the natural ecology.

National Environment Policy: At the national level, the Ministry of Environment and Forests had prepared a draft Environment Policy (NEP) and the Ministry of Power along with NTPC actively participated in the deliberations of the draft NEP.

The NEP 2006 has since been approved by the Union Cabinet in May 2006.

NTPC Environment Policy: As early as in November 1995, NTPC brought out a comprehensive document entitled "NTPC Environment Policy and Environment Management System". Amongst the guiding principles adopted in the document are company's proactive approach to environment, optimum utilisation of equipment, adoption of latest technologies and continual environment improvement. The policy also envisages efficient utilisation of resources, thereby minimising waste, maximising ash utilisation and providing green belt all around the plant for maintaining ecological balance.

Environment Management, Occupational Health and Safety Systems:

NTPC has actively gone for adoption of best international practices on environment, occupational health and safety areas. The organization has pursued the Environmental Management System (EMS) ISO 14001 and the Occupational Health and Safety Assessment System OHSAS 18001 at its different establishments. As a result of pursuing these practices, all NTPC power stations have been certified for ISO 14001 & OHSAS 18001 by reputed national and international Certifying Agencies.

Pollution Control Systems

While deciding the appropriate technology for its projects, NTPC integrates many environmental provisions into the plant design. In order to ensure that NTPC comply with all the stipulated environment norms, various state-of-the-art pollution control systems / devices as discussed below have been installed to control air and water pollution.

Electrostatic Precipitators: The ash left behind after combustion of coal is arrested in high efficiency Electrostatic Precipitators (ESPs) and particulate mission is controlled well within the stipulated norms. The ash collected in the ESPs is disposed to Ash Ponds in slurry form.

Flue Gas Stacks: Tall Flue Gas Stacks have been provided for wide dispersion of the gaseous emissions (SOX, NOX etc) into the atmosphere.

Low-NOX Burners: In gas based NTPC power stations, NOx emissions are

controlled by provision of Low-NOx Burners (dry or wet type) and in coal fired stations, by adopting best combustion practices.

Neutralisation Pits: Neutralisation pits have been provided in the Water

Treatment Plant (WTP) for pH correction of the effluents before discharge into Effluent Treatment Plant (ETP) for further treatment and use.

Coal Settling Pits / Oil Settling Pits: In these Pits, coal dust and oil are removed from the effluents emanating from the Coal Handling Plant (CHP), coal yard and Fuel Oil Handling areas before discharge into ETP.

DE & DS Systems: Dust Extraction (DE) and Dust Suppression (DS) systems have been installed in all coal fired power stations in NTPC to contain and extract the fugitive dust released in the Coal Handling Plant (CHP).

Cooling Towers: Cooling Towers have been provided for cooling the hot Condenser cooling water in closed cycle Condenser Cooling Water (CCW) Systems. This helps in reduction in thermal pollution and conservation of fresh water.

Ash Dykes & Ash Disposal Systems: Ash ponds have been provided at all coal based stations except Dadri where Dry Ash Disposal System has been provided.

Ash Ponds have been divided into lagoons and provided with garlanding

arrangements for change over of the ash slurry feed points for even filling of the pond and for effective settlement of the ash particles.

Ash in slurry form is discharged into the lagoons where ash particles get settled from the slurry and clear effluent water is discharged from the ash pond. The discharged effluents conform to standards specified by CPCB and the same is regularly monitored.

At its Dadri Power Station, NTPC has set up a unique system for dry ash collection and disposal facility with Ash Mound formation. This has been envisaged for the first time in Asia which has resulted in progressive development of green belt besides far less requirement of land and less water requirement as compared to the wet ash disposal system.

Ash Water Recycling System: Further, in a number of NTPC stations, as a proactive measure, Ash Water Recycling System (AWRS) has been provided. In the AWRS, the effluent from ash pond is circulated back to the station for further ash sluicing to the ash pond. This helps in savings of fresh water requirements for transportation of ash from the plant.

The ash water recycling system has already been installed and is in operation at Ramagundam, Simhadri, Rihand, Talcher Kaniha,

Talcher Thermal, Kahalgaon, Korba and Vindhyachal. The scheme has helped stations to save huge quantity of fresh water required as make-up water for disposal of ash.

Dry Ash Extraction System (DAES): Dry ash has much higher utilization

potential in ash based products (such as bricks, aerated autoclaved concrete blocks, concrete, Portland pozzolana cement, etc.). DAES has been installed at Unchahar, Dadri, Simhadri, Ramagundam, Singrauli, Kahalgaon, Farakka, Talcher Thermal, Korba, Vindhyachal, Talcher Kaniha and BTPS.

Liquid Waste Treatment Plants & Management System: The objective of industrial liquid effluent treatment plant (ETP) is to discharge lesser and cleaner effluent from the power plants to meet environmental regulations. After primary treatment at the source of their generation, the effluents are sent to the ETP for further treatment. The composite liquid effluent treatment plant has been designed to treat all liquid effluents which originate within the power station e.g. Water Treatment Plant (WTP), Condensate Polishing Unit (CPU) effluent, Coal Handling Plant (CHP) effluent, floor washings, service water drains etc. The scheme

involves collection of various effluents and their appropriate treatment centrally and re-circulation of the treated effluent for various plant uses.

NTPC has implemented such systems in a number of its power stations such as Ramagundam, Simhadri, Kayamkulam, Singrauli, Rihand, Vindhyachal, Korba, Jhanor Gandhar, Faridabad, Farakka, Kahalgaon and Talcher Kaniha. These plants have helped to control quality and quantity of the effluents discharged from the

stations.

Sewage Treatment Plants & Facilities: Sewage Treatment Plants (STPs) sewage treatment facilities have been provided at all NTPC stations to take care of Sewage Effluent from Plant and township areas. In a number of NTPC projects modern type STPs with Clarifloculators, Mechanical Agitators, sludge drying beds, Gas Collection Chambers etc have been provided to improve the effluent quality. The effluent quality is monitored regularly and treated effluent conforming to the prescribed limit is discharged from the station. At several stations, treated effluents of STPs are being used for horticulture purpose.

Environmental Institutional Set-up

Realizing the importance of protection of the environment with speedy development of the power sector, the company has constituted different groups at project, regional and Corporate Centre level to carry out specific environment related functions. The Environment Management Group, Ash Utilisation Group and Centre for Power Efficiency & Environment Protection (CENPEEP) function from the Corporate Centre and initiate measures to mitigate the impact of power project implementation on the environment and preserve ecology in the vicinity of the projects. Environment Management and Ash Utilisation Groups established at each station, look after various environmental issues of the individual station.

Environment Management During Operation Phase

NTPC's environment friendly approach to power has already begun to show results in conservation of natural resources such as water and fuel (coal, oil & gas) as well as control of environmental pollution. As already mentioned earlier, NTPC has chalked out a set of well defined activities that are envisaged right from the project conceptualisation stage so that during the entire life cycle of the power plant, NTPC is

fully compliant with various environment regulations and a pristine environment and ecological balance is maintained in and around its power station and

townships. Following is brief description of some of the measures taken during the operation phase of the stations. Performance enhancement and up-gradation measures are undertaken by the organisation during the post operational stage of the stations. These activities have greatly helped to minimise the impact on environment and preserve the ecology in and around its power projects. These measures have been enumerated as follows.

Monitoring of Environmental Parameters: A broad based Environment Monitoring Programme has been formulated and implemented in NTPC. All pollutants discharged from the power plant such as stack emission, ash pond effluent, main plant effluent, domestic effluent and Condenser Cooling Water (CCW) effluent are monitored at

the stipulated frequency at the source itself and at the points of discharge. In addition to the above, ambient air, surface water and ground water quality in and around NTPC plants are regularly monitored to assess any adverse impacts as a result of operation of the power plant.

On-Line Data Base Management: In order to have better control on pollution and to achieve effective environment management in and around NTPC stations, it is imperative to have an on-line, reliable and efficient environment information system on the plant operational and environmental performance parameters at all three levels i.e generating Stations, Regional Headquarters and Corporate Centre. In consideration of the above, a computerized programme, namely "Paryavaran Monitoring System" - PMS, which could provide

reliable storage, prompt and accurate flow of information on environmental performance of Stations was developed and installed in NTPC. This software facilitates direct transfer of environment reports and other environment related information from stations to the Regional Headquarters and Corporate Centre. The PMS has already been

implemented at Corporate Centre, the Regional Headquarters and most of the Stations. This system has helped in achieving continuous improvement in NTPC’s environment performance through improved monitoring and reporting system by using the trend analysis and advanced data management techniques.

Environment Reviews: To maintain constant vigil on environmental compliance, Environmental Reviews are carried out at all operating stations and remedial measures have been taken wherever necessary. As a feedback and follow-up of these Environmental Reviews, a number of retrofit and up-gradation measures have been undertaken at different stations.

Such periodic Environmental Reviews and extensive monitoring of the facilities carried out at all stations have helped in compliance with the environmental norms and timely renewal of the Air and Water Consents.

Upgradation & Retrofitting of Pollution Control Systems: In order to keep pace with the changing norms and ensure compliance with statutory requirements in the field of pollution control, NTPC keeps an open mind for Renovation and Modernisation (R & M) and Retrofitting and Upgradation of pollution monitoring and control facilities in its existing stations. It is important to mention that such modifications/retrofit programs not only helped in betterment of environment but also in resource conservation.

High efficiency Electro-Static Precipitators (ESPs) of the order of 99.5% and above have been provided at NTPC stations for control of stack particulate emissions. However, the ESPs of a number of stations were built prior to the promulgation of the Environment (Protection) Act, 1986 and notification of emission control standards under this Act. Remedial measures have already been taken up and implemented to improve the efficiency of the existing ESPs at various NTPC stations. ESP performance enhancement programme by adopting advanced microprocessor based Electrostatic Precipitator Management System (EPMS) was installed at its power stations at Singrauli, Ramagundam, Korba, Farakka, Rihand, Vindhyachal and Unchahar. Additional ESPs were retrofitted in the older power stations, namely at Badarpur and Talcher Thermal. As a result of the above retrofits, the emission of Suspended Particulate Matter (SPM) has been brought down appreciably at the above stations and is maintained within the present statutory limit of 150 mg/Nm3. In new projects, the ESPs have been designed for a

maximum permissible outlet dust emission of 50 mg/Nm3 to meet the likely stringent emission norms in the near future.

Resources Conservation

With better awareness and appreciation towards ecology and environment, the organization is continually looking for innovative and cost effective solutions to conserve natural resources and reduce wastes. Some of the measures include:

__ Reduction in land requirements for main plant and ash disposal areas in

newer units.

__ Capacity addition in old plants, within existing land.

__ Reduction in water requirement for main plant and ash disposal areas

through recycle and reuse of water.

__ Efficient use of Fuel (Coal, Natural gas and Fuel oil) and

__ Reduction in fuel requirement through more efficient combustion and

adoption of state-of-the-art technologies such as super critical boilers

Waste Management

Various types of wastes such as domestic wastes, hazardous wastes,

Bio-Medical wastes get generated in power plant areas, plant hospital and the townships of projects. The wastes generated are a number of solid and hazardous wastes like used oils & waste oils, grease, lead acid batteries, other lead bearing wastes (such as garkets etc.), oil & clarifier sludge, used resin, used photochemicals, asbestos packing, e-waste, metal scrap, C&I wastes, electricial scrap, empty cylinders (refillable), paper, rubber products, canteen (bio-degradable) wastes, buidling material wastes, silica gel, glass wool, fused lamps & tubes, fire resistant fluids etc. These wastes fall either under hazardous wastes category or non-hazardous wastes category as per classification given in Government of India’s notification on Hazardous Wastes (Management and Handling) Rules 1989 (as amended on 06.01.2000 & 20.05.2003). Handling and management of these wastes in NTPC stations have been discussed below.

Municipal Waste Management: Domestic or municipal waste is generated in households at townships. This waste is segregated into bio-degradable and non biodegradable wastes at source itself in different colored containers and thereafter the two types are

disposed separately. Bio-degradable waste is spread uniformly in identified low lying areas and thereafter it is covered with soil for use later as manure after composting. The segregated non bio-degradable waste is disposed off separately in other identified low lying areas and is spread out

uniformly.

Hazardous Waste Management: NTPC being a proactive organization, the

handling and disposal of hazardous wastes are done as per the Hazardous Wastes (Management & Handling) Rules 1989 (as amended in 2003) guidelines issued by Government of India for the treatment, storage and disposal of hazardous wastes.

Scientific study on management and handling of hazardous wastes was carried out at a few NTPC stations to adopt the best practices so that there is a complete compliance with statutory requirements. In NTPC sataione, the Hazardous Wastes (Recyclable) are sold / auctioned to registered recyclers / refiners. The other hazardous wastes such as the activated carbon resins, used drums (hazardous) chromium (Cr-III electrolytes, used petro-chemicals, asbestos packings, used torch

batteries, ribbon, toners / cartridges, mixed wastes (waste oil, water & cotton) filters, earth contaminated with synthetic oil (FQF) glass used & sodium silicate, lamps & tubes etc. fall under the category of Hazardous Wastes (Non-Recyalable).

These wastes are small in quantity and are stored in properly identified locations.

As per the notification, hazardous wastes (non-recyalable) are to be sent to State Pollution Control Board (SPCB) approved common treatment storage and disposal facility (TSDF).

Bio-Medical Waste Management:

Hospital (or Bio-medical) wastes get generated from hospitals and they include urine bags, human anatomical wastes, plaster of paris waste, empty plastic bottles of water & glucose, blood & chemical mixed cotton, blood & urines tubes etc. these wastes are segregated and are placed in buckets of different colors as per the notification for Bio-Medical Waste (Management & Handling) Rules. The segregated bio-medical wastes are either disposed through the SPCB approved agency or they are treated in autoclaves before disposal into bio-medical waste disposal pits. The treated bio-medical waste is spread uniformly and covered with 10 cm thick soil in bio-medical waste disposal

pits.

Land Use / Bio-diversity

As a policy, NTPC lays special emphasis on land use and Bio-diversity by way of development of green belts, energy plantations, reclamation ofabandoned Ash Ponds and EIA and ecological monitoring in the project areas and its surroundings.

Reclamation of Abandoned Ash ponds: The reclamation of abandoned ash pond sites is a challenging task. NTPC has reclaimed temporary ash disposal areas at some of its projects namely Ramagundam, Talcher Thermal, Rihand, Singrauli and Unchahar through plantation and converted these sites into lush green environments. Extensive plantations have also been undertaken on dry ash mound at NTPC-Dadri. It is planned to reclaim all the abandoned ash disposal areas by plantation.

Green Belts, Afforestation & Energy Plantations: What’s more, in a concerted bid to counter the growing ecological threat, NTPC is

undertaking afforestation programmes covering vast areas of land in and around its projects. Appropriate afforestation programmes for plant, township and green belt areas of the project have been implemented at all projects.

In order to enhance green cover in the areas around our projects, as a responsible corporate citizen, NTPC till date has planted more than 18 million trees at its projects throughout the country. The afforestation has not only contributed to the aesthetics but also has been serving as a 'sink' for the pollutants released from the station and thereby protecting the quality of ecology and environment in and around the projects. Thrust has also been given to bio-diesel plantation and around 4.8 lakh energy plants including Pongamia and Jatropha have already been planted. A pilot project for extraction of seeds from these bio-diesel plants has also been set

up.

Ecological Monitoring & Scientific Studies

NTPC has been a leader in the industrial sector of India in undertaking scientific studies related to thermal power generation. NTPC has pioneered several scientific studies in collaboration with national/ international institutions to develop an environmental databank e.g. Detailed Geohydrological Studies to understand the impact of ash pond leachate on ground water and Ecological Impacts Monitoring through Remote Sensing Data have been carried out at its operating stations as

discussed below.

Environment Impact Asssement Studies: Environmental Impact Assessment (EIA) Studies are inevitably undertaken to evaluate potential negative impacts as well as to formulate Environmental

Management Plans to overcome the identified impacts. Based on the recommendations of Environmental Impact Assessment Study and Environmental Management Plan (EMP) and the conditions stipulated in the clearances from Ministry of Environment and Forests and State Pollution Control Boards,

These studies consists of impact assessment in the area of the land use, water use, socio-economic aspects, soil, hydrology, water quality, meteorology, air quality, terrestrial and aquatic ecology and noise. These studies are conducted before starting the construction as well as after operation of the plant and gives comprehensive status of the environment as existed before construction as well as in the post operational stages of the project. The EIA involves stage-by-stage evaluation of various parameters which affect the environment. Based on EIA study, wherever required, specific scientific studies are also conducted to scientifically assess the likely impact of the pollutants on the sensitive flora and fauna in the surroundings, as also, to take preventive and mitigatory measures, wherever required.

Apart from project specific EIA studies, Regional Environmental Assessment studies have been conducted for Integrated Development of Singrauli, Korba and Ramagundam areas. Such studies are of first of their kind in India and probably very few such studies have been undertaken in other countries.

Socio-economic Studies: Detailed socio-economic studies are undertaken to establish the socio-economic status of project affected persons and rehabilitation and resettlement plans are drawn in consultation with the state government.

Rehabilitation and resettlement options include land for land (subject to

availability), limited jobs with NTPC and contractors and self employment schemes.

In addition, NTPC also undertakes community development activities in the

surrounding villages.

Ecological Monitoring Programme: NTPC has undertaken a comprehensive

Ecological Monitoring Programme through Satellite Imagery Studies covering an area of about 25 Kms radius around some of its major plants. The studies have been conducted through National Remote Sensing Agency (NRSA), Hyderabad at its power stations at Ramagundam, Farakka, Korba, Vindhyachal, Rihand and Singrauli.

These studies have revealed significant environmental gains in the vicinity areas of the project as a result of pursuing sound environment management practices. Some of these important gains which have been noticed are increase in dense forest area, increase in agriculture area, increase in average rainfall, decrease in waste land etc.

In general, the studies, as such, have revealed that there is no significant adverse impact on the ecology due to the project activities in any of these stations. Such studies conducted from time to time around a power project have established comprehensive environment status at various post operational stages of the project.

Geo-hydrological Studies: NTPC has conducted several geo hydrological studies of the ash disposal areas at its projects (Singrauli, Rihand, Vindhyachal, Korba, Farakka and Talcher) through reputed institutions like Indian Institutes of Technology, Roorkee;

Indian Institutes of Technology, Mumbai, Centre for Studies on Man and Environment, Calcutta. All these studies conclude that the leaching of heavy metals from ash occurs only under pH 4 or below. In practice, the pH of the

ash water is either neutral or alkaline (7 or above) and hence the leaching of heavy metals is highly unlikely.

Use of Waste Products & Services -Ash Utilization

Ash is the main solid waste which is put into use for various products and services.

NTPC has adopted user friendly policy guidelines on ash utilisation.

In order to motivate entrepreneurs to come forward with ash utilisation schemes, NTPC offers several facilities and incentives. These include free issue of all types of ash viz. Dry Fly Ash / Pond Ash / Bottom Ash and infrastructure facilities, wherever feasible. Necessary help and assistance is also offered to facilitate procurement of land, supply of electricity etc from Government Authorities.

Necessary techno-managerial assistance is given wherever considered necessary.

Besides, NTPC uses only ash based bricks and Fly Ash portland pozzolana cement (FAPPC) in most of its construction activities. Demonstration projects are taken up

in areas of Agriculture, Building materials, Mine filling etc. The utilisation of ash and ash based products is progressively increasing as a result of the concrete efforts of these groups.

Advanced / Eco-friendly Technologies

NTPC has gained expertise in operation and management of 200 MW and 500 MW

Units installed at different Stations all over the country and is looking ahead for higher capacity Unit sizes with super critical steam parameters for higher efficiencies and for associated environmental gains. At Sipat, higher capacity Units of size of 660 MW and advanced Steam Generators employing super critical steam parameters have already been implemented as a green field project.

Higher efficiency Combined Cycle Gas Power Plants are already under operation at all gas-based power projects in NTPC. Advanced clean coal technologies such as Integrated Gasification Combined Cycle (IGCC) have higher efficiencies of the order of 45% as compared to about 38% for conventional plants. NTPC has initiated a techno-economic study under USDOE / USAID for setting up a commercial scale demonstration power plant by using IGCC technology. These plants can use low grade coals and have higher efficiency as compared to conventional plants.

With the massive expansion of power generation, there is also growing awareness among all concerned to keep the pollution under

control and preserve the health and quality of the natural environment in the vicinity of the power stations. NTPC is committed

to provide affordable and sustainable power in increasingly larger quantity. NTPC is conscious of its role in the national endeavour of

mitigating energy poverty, heralding economic prosperity and thereby contributing towardsIndia’s emergence as a major global

economy. ASH UTILISATION SCENARIO OF INDIA

65% of the total installed power generation is coal-based

230 - 250 million MT coal is being used every year

High ash contents varying from 30 to 50%

95 million MT of ash generated every year

Ash generation likely to reach 170 million MT by 2010

Presently 65,000 acres of land occupied by ash ponds

Ash utilisation is one of the key concerns at NTPC. The Ash Utilisation Division, set up in 1991, strives to derive maximum usage from the vast quantities of ash produced at its coal-based stations. The division proactively formulates policy, plans and programme for ash utilisation. It further monitors the progress in these areas and works at developing new fields of ash utilisation.

The quality of ash produced conforms to the requirements of IS 3812. The fly ash generated at NTPC stations is ideal for use in cement, concrete, concrete products, cellular concrete, lightweight aggregates, bricks/blocks/tiles etc. This is attributed to its very low loss on ignition value. To facilitate availability of dry ash to end-users all new units of NTPC are provided with the facility of dry ash collection system. Partial dry ash collection systems have also been set up at the existing stations where these facilities did not exist earlier. Augmentation of these systems to 100% capacity is presently in progress.

As the emphasis on gainful utilization of ash grew, the usage over the years also increased. From 0.3 million tons in 1991-1992, the level of utilization during 2007-08 stood at over 23.686 million tons.

The various channels of ash utilization currently include use by a number of Cement, Asbestos-Cement products & Concrete manufacturing Industries, Land Development, Roads & Embankments, Ash Dyke Raising, and Building Products.

Area wise break-up of utilisation for the year 2007-08 is as under:

Area of UtilisationQuantity (in Million Tons)

Land Development6.935

Cement & Concrete8.694

Roads/Embankments2.277

Ash Dyke Raising 3.886

Bricks 0.140

Mine Filling 0.946

Others 0.808

Total 23.686

NTPC has adopted user friendly policy guidelines on ash utilisation. These include actions identified for:

Ash Collection & Storage System

Facilities & Incentives to Users

Direct Department Activities

Administrative & Financial Aspects.

Major Initiatives Taken By NTPC Towards Ash Utilisation

NTPC continually strives to evolve innovative and diverse means of Ash Utilisation to further broaden the scope. Prominent among the methods devised so far are:

Dry Flyash Extraction Systems

Use in cement & concrete

Use in Ash based products including setting up of

Ash Technology Park

Land Development/Wasteland Development, Roads & Embankments, Raising Ash Dykes'

Mine filling / Stowing

Agriculture

Fly Ash Mission Activities

NTPC Guide For Users Of Coal Ash

NTPC, Ash Utilisation Division has brought out a booklet titled 'NTPC Guide for users of coal ash for distribution amongst prospective entrepreneurs and users of ash.Other Promotional literature printed for distribution includes brochures titled:

Ash a Resource

Eco-Friendly Bricks for new Millennium

Fly ash based Portland Pozzolana Cement

Coal ash Environment friendly material for fills, Embankments and Road pavement construction

TYPES OF COAL ASH

Three categories of ash available from thermal power stations.

Dry Fly Ash : Collected from different rows of Electro-Static-Precipitators in dry form. Used for manufacture Portland Pozzolana Cement, Cement concrete & Mortar, Lime fly ash bricks, Building blocks, Aerated Concrete Blocks, etc.

Bottom Ash : Collected at the bottom of boiler furnace characterized by better geo-technical properties. Good material for fill, road and embankment construction.

Pond Ash : Fly ash and Bottom ash are mixed together with water to form slurry-which is pumped to the Ash Pond Area, ash gets settled and excess water is decanted. This deposited ash is Pond ash; it’s being used as filling material including embankment and road construction. Selected pond ash can be used for manufacture of building products like lime fly ash bricks/blocks.

USES OF COAL ASH

Construction of embankments and fills.

Construction of road in base and sub-base course.

Manufacture of Portland pozzolana cement.

Cement concrete and mortar as a partial replacement of cement.

Manufacture of bricks/blocks, aerated concrete blocks, light weight aggregate.

Back filling of open cast mines and stowing of under-ground mines.

Filling as flowable fill material.

Agriculture as soil amendment/source of essential plant nutrients.

Manufacture of alum. Paint, ceramics and other high value items.

Coal Ash in Fills & Embankment

Principal Advantages

Lower density than earth resulting in lower over burden pressure.

Lower settlement, lower transportation cost as compared to earth.

Advantageous in weak/clayey sub-soils.

Hardly any measureable settlement over time due to low compressibility.

Speed of construction is faster as it can be compacted in wide range of moisture content.

Work can be taken up even in rainy season due to quick draining properties of loose ash.

Assured availability free of cost.

Eco-friendly since it replaces soil taken from agriculture lands.

Road Construction

Bottom ash can be used directly in sub-base course.

Fly ash and pond ash stabilized with soil/lime/cement or with moorum can be used in sub-base and base course material.

Fly ash can be used as partial replacement of cement & fine aggregate in rigid pavement.

Fly ash is can be used as a filler material bituminous concrete used in base/wearing course.

Manufacture of Portland Pozzolana Cement

Fly ash is widely utilized in manufacture of fly ash based Portland Pozzolana Cement (FAPPC) conforming to IS-1489.

Portland Pozzolana Cement (FAPPC) is equivalent to 33 grade of Ordinary Portland Cement (OPC) on the basis of 3, 7 and 28 days compressive strength.

FAPPC has following advantages over OPC :-

» Improved workability

» Reduced heat of hydration

» Increased Sulphate resistance

» Reduced Alkali-Aggregate Reaction

» Reduced porosity & uniform matrix structure

» Increased corrosion resistance

» Greater long term strength

Use in Fly ash lime bricks

Fly ash is utilized in manufacture of fly ash-lime bricks.

Fly Ash Lime bricks have better crushing strength than clay-bricks.

Fly Ash Lime bricks are more resistant to salinity and water.

CPWD has incorporated in their specification for use of these bricks in all types of constructions.

These bricks are widely used in NTPC and different parts of the country.

Fly Ash Lime bricks are becoming popular in Delhi too.

Use of Fly Ash in Cement Concrete

Fly ash can be utilized in cement concrete and mortar as an ingredient/partial replacement of cement and sand.

Use of fly ash in cement concrete improves the properties of concrete which inter-alia include:-

» Greater long term strength

» Improves workability

» Increased durability

» Reduction in cost of concrete

Replacement of Ordinary Portland Cement may vary from 15 to 35% or even higher percentage in mass concrete.

IS 456 : Code of practice for plain and reinforced concrete allows the use of fly ash as a partial replacement of Ordinary Portland Cement and sand.

In developed countries such as USA, UK etc; Fly ash is extensively used in manufacture of cement concrete.

Fly ash has been used in foundations, walls, floors, concrete fire proofing of Sears Towers, the world’s one of the tallest building in USA and construction of channel link between England and France.

Fly ash from NTPC’s power stations has been tested and found suitable for use in cement concrete and mortar.

Light Weight Aerated Concrete Block

Fly ash is utilized in manufacture of Light Weight Aerated Concrete products such as blocks, panels, reinforced slabs, etc.

The products are much lighter than conventional materials.

Bulk density of product ranges from 500 kg/m3 to 1800 kg/m3 depending upon requirement.

The use of the blocks in housing construction can results nearly 40% of dead load reduction, 50% saving in construction time and about 80% saving in consumption of mortars in comparison to conventional brick work.

These products provide better thermal insulation and sound absorption property as compare dto conventional works.

Use in Control Low Strength fill Material (CLSM)

Large quantity of fly ash (90-95%) and small quantity of Ordinary Portland Cement (5-10%) is mixed with sufficient quantity of water so as to make flowable fill material termed as Controlled Low Strength Material (CLSM).

CLSM is ideal fill material for use in restricted areas where placing and compaction is very difficult such as back filling of narrow trenches utilities structure such as mines, tunnels, tanks and trenches in road pavement cut for laying of utilities etc. It can also be utilized in control of undesirable growth of elephant grass.

CLSM provides various advantages which are :-

» Easy to produce, can be filled with minimal efforts.

» No compaction and no curing required.

» Fill all voids and spaces, no settlement after final set, can be dug back later when required.

» Different strength can be designed depending upon the requirement.

» Low unit weight, reduced labour cost and thus cost effective.

Other Areas of Utilization

Fly ash is used in manufacture of Asbestos cement products.

Fly ash can be used in large quantity in back filling of open cast mines and stowing of underground mines.

It can be utilized in Agriculture as soil amendment to modify pH of soil, soil conditioner to improve physicochemical properties of soil and as source of essential plant nutrient.

It can be utilized in manufacture of Alum, Paints, Ceramics and other high value items.

ECO BRICK

A new environment friendly building material conforming to the provisions of IS: 12894 issued by Bureau of Indian Standards.

Process

Eco-Bricks are made by precision machines with semi-dry mix of high quality fly ash, sand and lime/cement.

The excellent pozzolanic property of fly ash in presence of lime/cement and moisture makes Eco-Brick more strong and durable.

The brick manufactured in this process keeps on gaining strength continuously for a long time and ultimately it becomes very strong.

Moulding/ Pressing

Hydraulic presses or vibratory presses are used for moulding ensures uniform size of all bricks / blocks.

Curing

These moulded bricks/ blocks are dried for about 24-48 hours in shade and then suitably water/ steam cured.

Dry Shrinkage

The average drying shrinkage does not exceed 0.15 percent which is within limit as per IS specifications.

Efflorescence

The rating of efflorescence for the Eco-bricks when tested as prescribed by IS:3495 (Part- 3): 1976 is ‘nil` though as per IS:12894, it can be ‘moderate`.

Water Absorption

The water absorption of Eco-bricks is less than 20% for bricks of Class designation 7.5. The water absorption for the Eco-bricks of class designation 10 or 12.5 is less than 15%.

Availability

The Eco-bricks are available round the year unlike clay bricks, which aren’t manufacture during monsoon period.

Advantages of Using ECO- BRICK

As the size of Eco- bricks is uniform with smooth / plain surfaces, the requirement of mortar for the brick masonry works is about 25% less than the requirements for clay brick walls.

The thickness of plaster required is 6 to 10mm in place of 12 to 18 mm for clay brick walls.

The external walls made with Eco-bricks having absorption less than 15% can be left un-plastered thus giving a pleasant look and savings in plastering cost and yearly maintenance cost of building.

The Eco-bricks are lighter than clay bricks and thus saves cost of construction.

The Eco-bricks are environment friendly bricks as it saves

» Degradation of agriculture land required for clay bricks

» Land required for ash disposal.

SALIENT FEATURES OF NTPC - DADRI (ASH HANDLING PLANT)

STATION CAPACITY - 840 MW

COAL CONSUMPTION - 3.66 Million T / Year

ASH GENERATION - 1.5 Million T / Year

ASH DISPOSAL - Dry Ash System

DRY ASH SYSTEM - Vac. Extraction & Pr.

Transportation

WATER REQMT. FOR - 20 % By Weight

ASH CONDITIONING

ASH MOUND AREA - 375 Acres

CHEMICAL COMPOSITION OF FLY ASH

Silica, SiO2 64.57 %

Allumina, Al2O3 24.08%

Ferric Oxide, Fe2O3 6.4%

CaO 0.84-2 %,

MgO 0.84%

P2O5 0.15%

SO3 0.05%

Na2O 0.36%

Potassium Oxide 0.55%

C 0.05%

pH 8.10

Bulk Density 0.81 gm/ml

Salient features of installed system

Extraction & transportation of fly ash in complete dry form.

System having provision to store selected grade of ash in separate Silo (Silo-3).

Complete re-circulation of water for Bottom ash handling system.

Unloading & Transportation of conditioned ash from Silos & decanted bottom ash from Hydro bins on to belt conveyors.

Construction of Ash Mound in a systematic manner.

FLY ash system

BASICS OF A THERMAL POWER PLANT

The core components of a thermal power plant cycle are

Boiler

Turbine

Electric Generator

The thermal power plants employ steam turbines to run the generators. The steam required is obtained from a boiler . A boiler is a closed vessel in which water is put in tubes & heated until the water converts into steam at the required pressure . Coal is burnt in the bottom of the boiler & its heat is used to convert water into steam . The

steam is passed in the turbine to rotate it & the generator at required speed & generate power.

Efforts are made to enhance the cycle efficiency by maximum utilization of heat in the system by installing components like Economizers , Air pre heaters , Feed water heaters & Super heaters . The function of an economizer is to recover some of the heat which is being carried away in the flue gases through the chimney . The heat extracted is used to heat the feed water being fed to the boiler for steam generation , thus economizing the fuel requirement .

Air Pre heaters (APH)are components placed in the flue gas path before chimney & are used to further extract heat from the flue gas to heat the air required for combustion in the burners of the boiler.

The steam produced in the water tubes is still in the unsaturated form , which is dangerous for the turbine . Hence the steam is converted into super heated form in a superheater , installed in the boiler , by using the heat of the flue gases .

The combustible products are in the form of

1) bottom ash

2) Flue gas.

The bottom ash is removed through bottom ash system by adding water & transforming it in slurry form , for ease to be transported at the desired location .

The flue gas of fly ash is removed from the boiler through high chimneys. The ash / dust in the flue gas is extracted through various equipments like Electro static precipitator(ESP), cyclone separator etc. In an ESP , the gas contaminated by dust is passed into a chamber , where the dust particles are negatively charged & then on passing through an electric field , the dust particles are attracted to the positively charged collecting plates , thus preventing the dust to go out to the atmosphere through the chimney.

Fly Ash System

The fly ash is evacuated from fly ash hoppers & transported to Ash storage silos in two steps:

From the ESP & APH Hoppers to Buffer Hoppers thro’ VACUUM SYSTEM.

From Buffer Hoppers to Ash Storage Silos thro’ PRESSURE SYSTEM.

FLY ASH REMOVAL SYSTEM

Mixed Fly Ash Evacuation

SILO UNLOADING SYSTEM

SILO UNLOADING SYSTEM

Complete Recirculation of Waterin Bottom Ash Hopper Evacuation System

LP Water :

LP Pump taking suction from Surge Tank

» Bottom Ash Hopper make-up

» Seal Trough make-up

» Economizer flashing to Coarse Ash Tank

Over Flow Pump:

Recycle the LP water to Settling Tank

HP Water:

• HP Pump taking suction from Surge Tank

» Evacuate Bottom Ash & Coarse Ash and send to Hydrobin

» Hydrobin overflows to Settling Tank

» Settling Tank overflows to Surge Tank

Ash Management in Ash Mound Area

• Ash can be dumped in three different areas in ash mound depending upon system availability & weather conditions.

• Ash is dumped in “PERMANENT ASH MOUND AREA” normally.

During Rainy Season or System Non-Availability Ash is Dumped in “TEMPORARY ASH STORAGE AREA”

from where it is reclaimed to “Permanent Ash Mound Area” thro’ Reclaimer.

In case of Non-Availability of Systems for Permanent & Temporary Ash Mound Areas; Ash is transported to “EMERGENCY STOCK PILE” from where it is reclaimed with the help of “MOBILE EQUIPMENTS”.

ZONEWISE CONSTRUCTION SEQUENCE OF ASH MOUND

MOBILE EQUIPMENTS DEPLOYED FOR CONSTRUCTION OF ASH MOUND

DOZER D-355 1 NOS.

DOZER D-155 3 NOS.

DOZER D-50 2 NOS.

MOTOR GRADER 1 NO.

VIBRATORY COMPACTOR 2 NO.

PAY LOADER 1 NO.

HYD. EXCAVATOR 1 NO.

DUMPERS 2 NOS.

WATER BOWSERS 3 NOS.

Art. Dump truck 2 Nos.

Vacuum Truck 1 No.

Fork Lifter 1 No.

Hydra 1 No.

Two Tonne Dumper 1 No.

Pipe layer(for conv. shifting) 1 No.

Tractors 2 Nos.

Omega crane 1 No.

WORKSHOP M/Cs AT ASH MOUND

Lathe 1 No.

Shearing M/c 1 No.

Radial Drilling M/c 1 No.

Pillar Drilling M/c 2 No.

Hydraulic Press 1 No.

Hack Saw M/c 1 No.

SPECIES OF SHRUBS & TREES PLANTED ON ASH MOUND

SHRUBS - BOUGAINVILLAEA, GUDHAL , PILI KANER ,JHOUN , INDIGO (Neel) , DEDONIA

TREES - DALBERGIA - SISOO , BOTTLE-BRUSH, CASURINA , SHOO-BABOOL , RAMASAN, KACHNAR , RUBBER , FICUS-BENJAMINA , GULLAR , PILKHAN , BARGAD , PIPAL , BOMBAX, SIRUS , TICTONA-GRANDES (TEAK ) , POPELUS ,JAMUN , AMLA, IMLI, CAMPHAR

Salient Features of Ash Mound

Total Land Area 500 Acres.(Approx.)

Actual Ash Mound Area 375 Acres.(Approx.)

Finished Area at Mound Top 140 Acres.(Approx.)

Final Height of Ash Mound 55Meters.

Ash Volume 530 Lakh CuM.

Drainage Blanket Thickness 1.0 Meters.

Gradient of Slide Slopes 1:4 & 1:4.5

Capacity of Temp. Stock Yd. 1,90,000 CuM.

Capacity of Emergency Yd. 10,500 CuM.

Ash Utilization

ADVANTAGE OF DRY ASH DISPOSAL SYSTEM

LESS REQUIREMENT OF LAND

LESS WATER REQUIREMENT

ELIMINATES UNDERGROUND WATER AND SURROUNDING WATERWAYS POLLUTION

FACILITATE LARGE SCALE UTILISATION OF ASH

PROGRESSIVE RESTORATION OF ASH DISPOSAL SITE AS USEFUL LAND

CONCLUSION