Environmental Impacts of Coal Based Thermal Power Plants

A Captive thermal power plant is usually defined by the type of fuel used to heat the water and create system. A fossil-fuel power plant is one that burns fossil fuels such as coal, natural gas or petroleum to produce electricity. A thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankine cycle.

Air Pollution:

• Burning coal releases massive amount of Toxic materials such as Mercury and Arsenic
• Coal based thermal power plants are responsible for 21% of the green house gas emission.
• Thermal power plant using coal releases 11 million tons of sulphur dioxide into the air

Water Pollution:

• Decrease in DO (Dissolved Oxygen) Levels
• Increase in Toxins
• Loss of Biodiversity
• Ecological Impact
• Increases Metabolic Rate
• Migration

Land Pollution:

• Change in Climate patterns
• Environmental Impact
• Effect on Human health
• Distraction for tourist
• Effect on Wildlife

Due to these harmful impacts of Thermal power plant, Coal storage sheds are the suitable solution to address the issues listed above. With the help of coal storage sheds, these problems can be eradicated easily without damaging the environment. These sheds also protect from spontaneous combustion of coal and installation of this structure does not impact the productivity of the plant.

About Hindustan Alcox

We at Hindustan Alcox are the leading coal storage shed manufacturer in India. We provide practical solutions to these above challenges, in most efficient and cost reducing ways and satisfy our clients with the best available solutions in storage and handling of any type of bulk storage.

Read Also – Coal – It’s Storage and Uses

Coal – It’s Storage and Uses

Coal is used as one of the fossil fuel which is combustible black/brown hard rock usually found in coal beds. Coal is composed of 65-95% carbon with quantities of other elements such as hydrogen, nitrogen, sulphur and oxygen. Extracted from the ground by coal mining, coal is the biggest source of energy for the worldwide electricity generation. In simple terms, there exist four types of coal – peat, lignite (brown coal), bituminous and anthracite (highest quality coal). Coal formation has occurred over long period of time, often under high pressure of overburden at elevated temperature.

Coal Storage

The key purpose of coal storage is to provide reserves for power plant and factories. Storage for coal is important for many reasons to ensure smooth operation of power plants and industries utilizing coal, to also allow the management to take advantage of seasonal market conditions in prices of coal. During coal storage, the coal stored has the tendency to combine with oxygen of air and during this process coal degrades its heating value and ignition quality. Due to oxidation the coal may ignite spontaneously.

Coal Storage shed is the most efficient method to prevent the coal from this problem. The significance of coal storage sheds is to produce efficient industrial result from coal by avoiding problems faced in coal stacking like oxidation of coal, spontaneous combustion, self heating of coal and many more.

 Uses of Coal

• Coal is used in captive thermal power plants for generating electricity
• Coal is indirectly used to make steel in the steel industry
• Coal is also an important ingredient in the production of specialist product such as activated carbons, carbon fibre and silicon metals.

 About Hindustan Alcox Limited

One of the premier and well-versed entity as coal shed manufacturer in India, Hindustan Alcox Limited has a vast experience of 30 years in creating Coal storage shed. We customize and engineer our projects with the best available solution in storage and handling of any type of bulk storage.

READ ALSO – Why To opt for Steel Frame Construction

Coal Based Thermal Power Plant: Advantages & Disadvantages

At present 75.43% of the total installed captive and non-captive power generation in India is constituted by Thermal power plants. A Captive Thermal Power Plant converts the heat energy of coal into electrical energy. Coal is burnt in the boiler which converts water into steam. The expansion of steam in turbine produces mechanical power which drives the alternator coupled to turbine. Captive Thermal Power Plants contribute maximum to the generation of Power for any country. Coal, oil and natural gas are considered as primary sources of energy in thermal generating stations.

Coal is the most favorable source of energy as coal provide usable energy at a cost of between 12% to 15% compared to oil and natural gas, and coal prices are also relatively stable. But the problems of coal storage are the biggest challenge faced in the thermal power plant which includes:

• Risk of spontaneous combustion
• Weathering
• Possibility of loss and deterioration during storage

To overcome these problems, coal sheds are being used to protect the coal storage from these kinds of problems which results in significant losses.

Advantages of coal based Thermal Power Plant:

• They can answer to rapidly changing loads without difficulty
• A chunk of the steam generated can be used as a process steam in different industries.
• Steam engines and turbines can work under 25% of overload continuously
• Fuel used is not very costly
• Economical in production cost in comparison with that of diesel power stations.

Disadvantages of coal based Thermal Power Plant:

• Maintenance and operation cost are high
• A large amount of water is required
• Great difficulty experienced in coal handling
• Unavailability of good quantity coal
• Maximum of heat energy lost
• Problems of ash removing

About Hindustan Alcox

With long –term experience of over 30 years, Hindustan Alcox limited identifies and eliminates unnecessary energy losses from the processes by providing the best choice for covering coal stockpiles under Coal storage shed. Alternatively, coal storage can also be done under dome structure sheds (like Coal dome, petcoke dome).

Read More – Types of Space Frames

Coal Gasification: Best practice to generate clean power from coal

Coal Gasification:

Coal Gasification is a process that can turn coal into clean power, chemicals, hydrogen & transportation fuels that can be further used to generate electricity or steam. These coal gasification systems are introduced in captive thermal power plants with advanced technologies to reduce the cost and increase the efficiency.

Coal Gasifiers convert hydrocarbons into a synthesis gas (syngas) at elevated pressures & temperatures and can be used to create many products such as electric power, chemical feedstock, liquid fuels, hydrogen, synthetic gas.

Why Coal Gasification is best practice to generate clean power from coal storage?

Coal Gasification is usually considered as best practice to generate clean energy from coal storage. The aim of coal gasification is to generate power which is an important consideration in the future of hydrogen fueled electricity generation.

Providing numerous opportunities for pollution control, especially with respect to emissions of sulfur, nitrous oxides, and mercury, coal gasification also increases the resource availability for power generation. Followings are the main advantages that persists with a coal power plant integrated with coal gasification:-

• Environmental Performance
• Maximizing power or efficiency
• Long life
• Reduced Volume of solid wastes
• Free from dust & noise pollution

Coal Storage Sheds

With long-term experience of 30 years, Hindustan Alcox Limited identifies and eliminates unnecessary energy losses from the processes by providing the best choice for covering coal stockpiles under Coal storage shed. Alternatively, Coal Storage and handling can also be done under dome structure sheds (like Coal dome, petcoke dome).

Hindustan Alcox Limited, New Delhi – Coal Gasification Specialist

Coal Storage Domes integrated with Coal Gasification: An Ideal Storage Solution

Coal Storage:

Spontaneous Combustion

For a fruitful outcome of thermal Power Plants, the business of industrial coal storage for large quantities is on top priority for maintaining the product Integrity. Open stockpiles leave materials subject to degradation during storage. In addition, there are environmental concerns with controlling dust and runoff from these coal stockpiles.

Coal Storage Domes integrated with Coal Gasification:

Coal storage

Conversion of coal by the chemical processes to produce a mixture of combustible gas or fuel gas or syngas is termed coal gasification Coal Gasifiers generally entails the controlled oxidation of the coal to convert it into desired gaseous products. The emphasis of coal gasification is to meet stringent emission control requirements.

Bulk storage dome structures are highly durable and strong. If we talk about strength and average building life of dome structures, then their life is longer and strength is more than any other type of stacker reclaimer sheds in Space frame industry. Coal storage domes with coal gasification has its own advantages. These include:

• Simple foundation requirements.

• Rapid construction regardless of weather.

• Condensation is virtually eliminated.

• Better environmental and fugitive dust control.

• Environment Friendly.

Dome Structural system provides a unique solution to the bulk storage industry. Remained committed towards sustainability and improving the local economies, the coal dome manufactured by Hindustan Alcox Limited are strong, durable, environmentally sound and adaptable. Over Last 20 Years, Our capabilities as a “prime industrial shed manufacturer” include building the Bulk storage dome shell for providing turnkey solutions all over the world.

• Hindustan Alcox Limited, New Delhi

  (Coal Storage Sheds Manufacturer in India)

Coal Storage: Performance Requirements for Maximum efficiency

Coal Storage:

Spontaneous Combustion in Coal storage Plants

Coal is a fossil fuel just like oil and natural gas. In thermal power plants, coal storage or petcoke storage (as the most exploited solid fuel) at large scale is preferred for the production of electric energy. A good preparation of coal before its combustion increases the homogeneity and efficiency of the fuel, reduces transportation costs and its displacement inside the plant produces less dust and reduces the emission of sulphur oxides. Besides, Preventive measures should be taken at every stage during the transport and bulk storage, in order to reduce any environmental impact, so that it became easier to maximize plant efficiency without any interference of any outside or environmental effects.

 

Performance Requirements for Maximum efficiency:

The large investment in a thermal power plant should be protected in best pos­sible way by maintaining the quality of resources (like coal, petcoke, lignite etc) and by uplifting the performance of their handling system. The coal handling system and equipment should perform satisfactorily to meet the guaranteed performance for maximum efficiency as stated here under:

1. Efficient operation in thermal power plants means the careful use of fuels and other consumables resources includ­ing in-house consumption of electricity. High availability requires strong focus on maintenance, which in turns contribute as one of the factors in producing maximum efficiency.

 

2. Stacker or reclaimer should be stable under a specified design condition and meet all the specified requirements. During unfavorable environmental conditions, the stacker or reclaimer should reclaim the coal in a way to avoid generation of well compacted, damp and sticky coal.

 

3. Sulphur content in fuel always had an adverse effect on overall plant efficiency. ‘Corrosive acids formation’ and ‘heat loss in boiler’ can be evaded by properly supervising and removing the sulphur content in coal.

 

4. Condition based maintenance uses intelligent measurements and assessments. These can include oil quality, differential pressure measure­ments, vibration readings and many more. By such applications, maintenance and renewal of plant components can be done exactly when needed.

 

5. Fuel quality of coal, which is generally quoted in terms of its gross calorific value (GCV) along with its moisture and ash content impacts on whole plant operational efficiency. Assessing fuel quality and choosing fuel of maximum gross calorific value and less moisture & ash content improves combustion and power generation as well.

 

6. Variation in the ambient temperature tends to affect plant performance and load capability of gas turbines along with the performance of cooling system. Hence, it is better to maintain the ambient temperature near a specific threshold during plant operation for maximum power output.

 

Using long-time experience of 30 years, It has been challenge for Hindustan Alcox Limited to identify and eliminate unnecessary energy losses from the processes by providing the best choice for covering coal stockpiles under Coal storage shed. Alternatively, Coal Storage and handling can be done under dome structure sheds (like Coal dome, petcoke dome).

 

– Hindustan Alcox Limited, New Delhi

(Coal storage shed manufacturer)

Role of Coal Gasification In various industries

Introduction to Coal Gasification / IGCC technology:

IGCC stands for “Integrated Gasification combined cycle”. The preliminary conversion into a gaseous fuel originated is named as SynGas / Synthesis Gas. Synthetic gas is an intermediate source for generation of hydrogen, ammonia, methanol, & other synthetic hydrocarbon fuels. For electricity generation, synthetic gas is not only used as fuel of internal combustion engines due to its combustible nature, but also plays an important role in keeping the plant eco- friendly.

During Coal storage at a large scale, for harnessing coal’s energy more cleanly and efficiently, a number of different ways attempted in order to motivate environmental concerns. Among them, the technology comes out to be most successful is coal gasification, where instead of burning the fossil fuel, it is chemically transformed into synthetic natural gas or syngas.

What is the Need:

Till now, the main objective of Conventional Thermal Power Plant was to increase the efficiency by means of increased temperature and pressure in the steam, which in turn generate an efficient power outcome. But today the need is to get more efficient power production along with keeping the outside eco friendly. With the technical advancement in working methodology, the upgraded thermal power plants are now capable to generate power using Coal Gasifiers in purpose to increase efficiency of the plant.

Coal Storage

Advantages of using the Coal Gasifiers:

• Clean Energy Conversion: From an economic and energy security perspective, coal gasification is proved the most successful process to dealt with clean energy conversion, since instead of opening the intermediate poisonous gases up to exploitation, coal gasification helps to access these resources cleanly.

 

• Environment Friendly: Addressing the atmospheric problems resulting from burning coal and getting least affected by these poisonous gases is one of the top priority objectives of coal gasification. This Environment friendly feature of coal gasification is also the key to achieve near-zero emissions from gasification-based power generation.

• Enhanced Power Generation & Reduced Resource Consumption:In coal based thermal power plants, synthetic gas collected during the coal gasification is used as fuel of internal combustion engines due to its combustible nature, which in turn not only participate in enhancing power generation but also reduces the resource consumption.

• Easy Installation and Maintenance: Coal Gasifiers, which are the main source to carry out coal gasification are installed in conjunction with coal bunkers. As far as their fixing and maintenance is concerned, these coal gasifiers are very simple to install and to maintain for the long term.

Coal Storage Shed

To supplement the eco friendly nature of the energy, Hindustan Alcox Limited provides world-class structures to cover spans up to 150m and any length. These sheds provide economical solution for such storage needs.

– Hindustan Alcox Limited, New Delhi

(Coal storage Shed Manufacturers in India)

Coal Storage: Problem of Spontaneous Combustion & Its Prevention

Coal, a non-renewable combustible material composed of carbon and hydrocarbons, whose combustible quality can be used for electricity generation and for some other necessities. Although stacking of coal is done in open shed areas, there are also covered shed areas or completely closed coal dome or silo.

 

Spontaneous Combustion

Spontaneous Combustion of Coal ?

Many issues have been encountered in bulk storage but in case of storing coal, self-combustibility comes as a special case & need careful treatment. The Spontaneous Combustion of coal in the coal storage is serious issue now a days due to global warming and other exothermic processes in coal stockpiles such as microbial metabolism, oxidation at low temperature, absorption & desorption of water by virtue of differences between real and equilibrium moisture content in coal and air. Spontaneous combustion usually begins as “hot spots” deep inside the coal/petcoke storage. They appear when coal absorbs oxygen from the air & heat generated by oxidation initiated the fire.

 

Key Causes of Spontaneous Coal Fires

The risk from spontaneous combustion or coal fire persists where significant amount of coal are in use or storage. The following mentioned points have been the contributing causes of spontaneous coal fires:

• New piles of coal added on top of old coal stockpiles creating segregation of particle sizes and become the major cause of heating.
• Too few temperature probing techniques or sensors installed in bunkering of coal resulting an extension in the time period before the fire was detected.
• Equipments’ failure to fight the coal fires (such as drag chain conveyer).
• Ineffective use of “Carbon dioxide fire suppression system” in plant area
• Delay in the application of water.
• Inadequate training of personnel, improper implementation of policies, & procedures prevented proper decision-making, including the knowledge to immediately overcome the coal fire.
• Long-term retention of coal in coal handling procedures also increases the probability of increase in temperature.

 

Preventing  Spontaneous Combustion in coal stockpiles-

Coal storage sheds

Preventing spontaneous combustion involves attention to many different factors, are as follows:

• Sulphur in coal liberates ample heat when they oxidize. Hence, strategies like “Know your Coal” & “Storing coal with low sulphur content” are helpful in evading spontaneous combustion in the plant area.
• Air circulation within a coal stockpile should be avoided up to possible extent since this supports increase in temperature in the stockpile.
• Use coal as quickly as feasible. The longer large coal stockpiles are allowed to sit, the more spontaneous combustion process dominates and increase the chances of coal fires.
• Do Proper inspection, test & maintenance of installed fire protection equipments on site.
• Following the “first in, first out” rule in coal stocking and stacking under petcoke dome or storage shed reduces the chances for hot spots in stockpiles by dissuading heat buildup for portions of stockpiles, which remain undisturbed for a long term.

 

–   Hindustan Alcox Limited, New Delhi

Prediction of Spontaneous Combustion & Its Prevention in Coal Storage & Handling

What is Spontaneous Combustion?

Spontaneous Combustion

The oxidation reaction that occurs without an external heat source is known as spontaneous combustion or self-heating in coal storage & handling. The process changes the internal heat profile of the coal within the layers, leading to a rise in temperature. This can eventually lead to ignite open flame and burning of the material. During its bulk storage, Spontaneous combustion can occur at any stage of transport, storage & handling of coal in captive thermal power plants. Factors responsible for instigating the self-heating of coal are as follows:

• Internal Factors –
  • Coal Composition & its Rank
  • Particle Size of Coal
  • Moisture & Sulphur Content in Coal
  • Weak caking properties
  • High reactivity

• External Factors –
  • Environmental Conditions (like Oxygen Concentration, Temperature, Humidity, Pressure etc)
  • Stockpiling Method
  • Handling Procedure & Ventilation

 

Prediction of Spontaneous Combustion in Coal Storage & Handling-

bulk storage

Spontaneous combustion or Self-heating in Coal or petcoke storage can be detected early in its development stage, i.e. before any obvious smoke and/or flame. Hot spots can be detected by infrared monitoring instruments or photography. Routine surveying of stockpiles using infrared scanning devices gives us excellent prediction in the situations where spontaneous combustion may be likely to occur. Efflorescence caused by the decomposition of pyrites and sublimation of sulphur is a strong indication of self-heating in coal stockpiles.

Spontaneous Combustion is also readily recognizable by their distinctive smell. Oxidation of the coal causes a release of large volumes of noxious and flammable gases, which themselves may represent a hazard, & the risk of explosion.

 

Precautions to avoid Spontaneous Combustion in Coal Storage & Handling-

In every case of spontaneous combustion, there is a build-up period of gases and heat before any flame arises. Following are the precautions that should be taken before maturity of spontaneous combustion of coal.

 

• Gas monitoring in workplace: The prevention of spontaneous combustion heavily depends on the monitoring of gases and conditions, which indicate that a problem is developing. Usage of gas detection systems in thermal power plants detects the major gases of concern – CH4, O2, CO and CO2.

 

• Electronic controls & self-checking systems: Automatic as well as manual calibration and checking should also be performed at regular basis, as one of the precaution to avoid Spontaneous Combustion in Coal storage plants.

 

• Flow nozzles: The rate and volume of airflow are required to monitor and calculate the volumes and concentrations of gases in coal stockpiles, which can be carried out with the usage of flow vessel at the site.

 

 

One of the premier and well-versed entity as coal shed manufacturer in india, Hindustan Alcox Limited has a vast experience of 20 years in creating Coal dome & Coal storage shed. Being the best choice for covering coal stockpiles for the most challenging environment, this barrel vault sheds and dome structure are also helpful in getting healthy prediction of spontaneous combustion & in taking appropriate precautions to avoid self-heating of coal during its storage and handling.

 

–    Hindustan Alcox Limited, New Delhi

(Coal Storage Shed manufacturer in India)

Impacts on Public & Environment by Coal Storage & Handling

Coal storage

Nowadays, Intermediate coal storage or lignite storage is common practice with indirect coal preparation systems. A constant feed from coal mines either to the coal mill or to the burners of a kiln system is a prerequisite for safer coal operations. The captive thermal power plants where coal is kept before burning also emit large quantities of carbon dioxide (CO₂ ), the “greenhouse gas” which are largely responsible for climate change. Depending on different factors like geology, demographics & climate, the public health and environmental effects caused by power plant may also vary from place to place. Followings are the major impacts on public & environment by coal storage & handling:

• Respiratory Effects: Inhalation effect from coal storage & handling is the biggest concern, which causes breathing problems not only to the people at the site but also to people living nearby the coal-based power plants.

 

• Impact on water bodies: At the coal-based thermal power plant, screening of coal is done to remove the impurities from the coal and the waste is placed in waste piles. If rain comes, rain percolates through these waste piles containing harmful soluble components and elevates Total Dissolved Solids (TDS) in local water bodies. This runoff is also acidic and contains heavy metals. In this way, Coal storage harms land, surface waters, groundwater and even air.

 

• Impact to the land:  Affect to the land from coal storage and handling cause drastic changes in the local area nearby by deteriorating land fertility and inculcating harmful chemicals. Damage to plants, animals and humans occurs from the destruction and removal of habitat & environmental contamination.

 

 

Using coal storage sheds over open stockpiles will be very much beneficial in reducing the above mentioned impacts on public & environment by coal storage & handling. We at Hindustan Alcox Limited specializes in manufacturing coal storage sheds with long span steel structure having span of up to 150 m & height of up to 40 m. Along with these longitudinal sheds, we also built dome type structural storage sheds. These coal dome and lignite dome, engineered by Hindustan Alcox Limited is one of the best choices to cover stockpile for the purpose to benefit the environment.

 

 

• – Hindustan Alcox Limited, New Delhi (Coal Storage Sheds Manufacturer India)