National Water Efficient Power Plant

What is Thermal Power Generation?

Thermal power generation is the process of producing electricity by converting heat energy into mechanical energy, which then drives a generator to produce electrical power. This method is widely used in power plants across the world and primarily relies on fossil fuels, nuclear energy, or renewable sources like biomass and solar thermal energy.

Working Principle: 

1. Fuel (coal, gas, or oil) is burned to produce heat.
2. Heat is used to boil water, producing steam.
3. Steam drives a turbine, connected to a generator.
4. The generator converts mechanical energy into electrical energy.

Types of Thermal Power Plants:

1. Coal-based
2. Gas-based
3. Oil-based
4. Combined Cycle

Process Flow Chart of Captive Power Plant

The advantages of Circulating Fluidized Bed Combustion (CFBC) boilers compared to Atmospheric Fluidized Bed Combustion (AFBC) boilers are as under:

CFBC vs AFBC

1. Fuel Versatility: CFBC boilers can efficiently burn a wider range of inferior-grade fuels, including low-grade coal and biomass, making them more adaptable to varying fuel qualities.

2. Higher Efficiency: CFBC technology typically achieves better thermal efficiency compared to AFBC boilers, leading to improved overall performance and reduced fuel consumption.

3. Reduced Unburnt Losses: CFBC systems exhibit lower levels of Loss On Ignition (LOI) and unburnt carbon, ensuring more efficient combustion and minimizing waste.

4. Increased Capacity: CFBC boilers are designed to handle larger capacities, making them suitable for bigger power generation needs and industrial applications.

5. Compact Design: CFBC boilers require less physical space compared to AFBC boilers, making them ideal for installations with spatial constraints.

6. Enhanced Emission Control: CFBC technology allows for better control of emissions, including lower levels of sulfur dioxide (SO₂) and nitrogen oxides (NOx), contributing to improved environmental compliance.

7. Improved Heat Transfer: The fluidized bed in CFBC boilers promotes better heat transfer, leading to more uniform temperature distribution and enhanced efficiency.

8. Lower Bed Temperature: Operating at lower bed temperatures reduces the risk of slagging and fouling, resulting in lower maintenance requirements and longer operational life.

9. Flexibility in Operation: CFBC boilers can operate efficiently under varying load conditions, providing greater flexibility for power generation and industrial processes.

10. Easier Ash Handling: The ash produced in CFBC systems is generally of better quality and easier to handle, allowing for more efficient disposal or utilization.

Advantages (CFBC) in boiler plant:

1. Reliability
2. Scalability
3. Low capital cost
4. High efficiency 
5. Low environmental impact
6. Low water usage due to Air Cooled Condenser (ACC) in Tower Configuration

Importance of Efficiency and Sustainability of Boiler:

Key Features of the power plant:

1. 150TPH CFBC Boiler
2. Air Cooled Condenser 
3. Auxiliary Cooling Tower for oil cooling, generator cooling, feed pump sealing, and bearing cooling
4. Effluent Treatment Plant (ETP)
5. Sewage Treatment Plant (STP)
6. UF, RO & DM 
7. Zero Liquid Discharge (ZLD)

Cooling Systems

Air Cooled Condenser (ACC):

It offers several advantages over water-cooled condensers, especially in environments where water is scarce or where sustainability is a concern. Here are some key benefits:

Water Conservation: Air-cooled condensers do not require water for cooling, making them ideal for regions with limited water resources. This reduces the environmental impact associated with water withdrawal and consumption.

Lower Environmental Impact: By minimizing water usage, air-cooled condensers help protect local water bodies and ecosystems, making them more environmentally friendly.

Reduced Infrastructure Costs: They eliminate the need for cooling towers, water treatment facilities, and extensive piping systems, leading to lower capital and maintenance costs.

Simplified Operations: Air-cooled systems generally have fewer components and lower operational complexity, which can result in reduced maintenance needs and operational downtime.

Less Risk of Contamination: With no standing water, there is a decreased risk of biological growth (like algae and bacteria) and contamination, which can occur in water-cooled systems.

Better Performance in Remote Locations: Air-cooled condensers can be more suitable for remote or arid locations where water supply is not feasible, allowing for more flexible site selection.

Easier Installation: These systems can be easier to install since they do not require the extensive plumbing and support structures associated with water-cooled systems.

Lower Thermal Pollution: Air-cooled condensers release heat directly into the atmosphere rather than into a water body, reducing thermal pollution and its potential impact on aquatic ecosystems.

Overall, air-cooled condensers are a sustainable and efficient choice, particularly in areas where water conservation is critical.

Air Cooled Condenser Descriptions and Benefits:

At Gallantt Ispat Limited power plant, an Air Cooled Condenser (ACC) is used instead of a surface condenser to conserve water. As a result, the water consumption has significantly decreased from 3 m³ per MWh (std) to just 0.5 m³ per MWh, primarily due to the implementation of the ACC system. This not only enhances operational efficiency but also supports sustainable water management.

• Type: Air Cooled Condensers (ACCs) are a type of heat exchanger used to condense steam or vapour into liquid.
• Design: ACCs consist of a series of tubes or coils through which the steam or vapour flows, surrounded by a network of fins to enhance heat transfer.
• Operation: Ambient air is drawn through the fins, cooling the tubes and causing the steam or vapour to condense into a liquid.

Air Cooled Condenser’s (ACC) Benefits:

• Water Conservation: ACCs eliminate the need for large amounts of cooling water, making them ideal for water-scarce regions.
• Low Operating Costs: ACCs have lower operating costs compared to traditional water-cooled condensers, as they don’t require water treatment or pumping.
• Reduced Environmental Impact: ACCs minimize the risk of water pollution and reduce the carbon footprint associated with water treatment and pumping.
• Increased Flexibility: ACCs can be designed to operate in a wide range of ambient temperatures, making them suitable for various applications.
• Reduced Maintenance: ACCs have fewer moving parts and don’t require water treatment, reducing maintenance requirements.
• Compact Design: ACCs can be designed to be more compact than traditional condensers, making them ideal for applications where space is limited.
• Improved Reliability: ACCs are less prone to corrosion and scaling, improving their reliability and lifespan.

Auxiliary Cooling Tower Functions:

• Cooling: Reduces temperature of hot water from condensers or heat exchangers (e.g. Oil Cooler, Generator Cooler, Feed Pump Sealing, Bearing Cooling and Sample Cooler, etc.)
• Heat Rejection: Rejects heat from the system to the atmosphere.
• COC Aux cooling tower: The Cycle Of Concentration (COC) for our auxiliary cooling tower is maintained between 6 and 7. We utilize Narmada water with an inlet TDS of 120 to 130 ppm, while the blow-down water TDS reaches 900 ppm. To enhance performance, we employ amine-based chemicals that are film-forming, neutralizing and dispersing. By maintaining a higher COC, we effectively conserve water.

Cooling Tower Efficiency:

• Optimize Water Flow Rate: Ensure proper water flow rate to maintain efficient heat transfer. 
• Maintain Proper Airflow: Ensure sufficient airflow through the tower to facilitate efficient heat transfer. 
• Cleanliness: Regularly clean the tower and its components to prevent fouling and maintain efficiency.
• Water Treatment: Implement a water treatment program to prevent scaling, corrosion, and biological growth.
• Tower Configuration: Ensure the tower is properly configured to optimize airflow and water distribution.

Waste Water Management Flow Diagram:

Water Treatment Process

1. Pre-Treatment

• Aeration: Oxygen is added to the water to support bacterial growth.
• Biological Treatment: Bacteria break down organic matter.
• Coagulation and Flocculation: Chemicals are added to remove dirt and other suspended particles.
• Sedimentation: Heavy particles settle to the bottom.
• Filtration: Water passes through filters to remove remaining suspended particles.

2. Post-Treatment:

• Ultrafiltration (UF) is a membrane filtration process that uses semi-permeable membranes to remove particles and contaminants from water. The water passes through a semi-permeable membrane with tiny pores (typically 0.01-0.1 μm). UF is used to remove bacteria, viruses, and parasites from water.
• Reverse Osmosis (RO Plant): Water passes through the semi-permeable membrane, which has tiny pores (typically 0.0001 μm). Impurities are rejected by the membrane, while water molecules pass through. RO can remove up to 99% of impurities, including dissolved solids, bacteria, viruses, and parasites.
• Demineralization (DM Plant): A DM Plant is a type of water treatment plant that uses ion exchange resins to remove dissolved solids, minerals, and other impurities from water.

Demineralization (DM PLANT):

Waste Water Treatment Plant

Effluent Treatment Plant: 

An Effluent Treatment Plant (ETP) is a type of wastewater treatment plant that treats industrial effluent (wastewater) to remove pollutants and contaminants before discharging it into the environment. ETPs help protect the environment by removing pollutants and contaminants from effluent. ETPs can help conserve water by treating and reusing effluent.

Application: Gardening and Toilet Flushing

Sewage Treatment Plant (STP)

The sludge treatment plant at Gallantt Ispat efficiently collects all wastewater from the colony and plants and processes it through a series of operations, including settling, clarification, and filtration. The treated water is then reused for irrigation, gardening & toilet flushing significantly conserving freshwater resources. Also used in DRI kiln cooling & rolling mills.

The ECOMax is an electrolytic water treatment system:

Features include automatic scale removal, self-cleaning mechanisms, auto back-wash media filters, automated blowdown, no need for plant shutdown during installation, a user-friendly GUI, and a compact design.

Zero Liquid Discharge (ZLD):

Gallantt Ispat is committed to sustainability through its Zero Liquid Discharge (ZLD) approach, ensuring efficient water management across its power and steel plants. Wastewater is treated in the Effluent Treatment Plant (ETP), allowing it to be recycled and reused for irrigation and landscaping. By repurposing water from plant operations and residential areas for lawn sprinkling and greenery maintenance, Gallantt Ispat actively contributes to water conservation while enhancing the surrounding environment.

Water Recirculation:

• Boiler: Water recirculation > 99%
• Condensing Turbine: > 99% water recirculation rate. High efficiency reduces fuel consumption, resulting in lower operating costs.
• Auxiliary Cooling System: Maintaining low blow-down rates (< 10%). By maintaining optimal temperatures, auxiliary cooling systems can extend the life of equipment, reducing maintenance and replacement costs.

Environmental Impact

Sustainability Initiatives :

Reducing water consumption.
Minimizing effluent discharge.
Contribution to local ecology through gardening reuse.

Summary:

Innovative design features play a crucial role in enhancing efficiency, reliability, and safety in modern power generation and industrial systems. A strong commitment to sustainable operations ensures reduced environmental impact, improved energy efficiency, and compliance with global sustainability goals. Additionally, advanced water treatment and cooling systems are essential for maintaining operational efficiency, preventing scaling and corrosion, and ensuring the long-term sustainability of industrial processes.

Author:

Ashwini Kumar Mishra
Vice President
Gallantt Ispat Limited