Introduction:
The transition to sustainable energy sources is critical in addressing environmental concerns and ensuring energy security. Biomass, derived from organic materials such as bhima bamboo, Napier grass, rice husk, mustard husk, soy husk, and wheat straw, presents a viable alternative to coal in boiler applications.
Advantages of Biomass over Coal:
Renewable Resource
Biomass is derived from renewable materials, making it a sustainable energy source. Unlike coal, which depletes finite natural resources, biomass can be replenished through agricultural practices. Large boilers, such as those rated at 100 TPH, 66 bar, and 485°C, based on biomass, are already operational and running successfully.
Carbon Neutrality
Biomass is often considered carbon-neutral because the carbon dioxide emitted during combustion is offset by the CO2 absorbed during the growth of the plants. This significantly reduces overall greenhouse gas emissions compared to coal.
Waste Utilization
Many biomass materials, such as Napier grass wheat straw, and Bhima bamboo are agricultural by-products. Utilising these waste materials for energy production reduces landfill waste and contributes to a circular economy.
Energy Independence
The local sourcing of biomass can enhance energy security and reduce dependence on imported fossil fuels.
Economic Benefits
Investing in biomass technology can create local job opportunities in agriculture, harvesting, and processing, stimulating rural economies
Challenges Associated with Biomass Technology
Supply Chain Management: Establishing a reliable and efficient supply chain for biomass feedstock is essential to ensure consistent fuel availability for boiler operations.
Energy Density: Biomass generally has a lower energy density compared to coal, which can lead to higher transportation and storage costs.
Combustion Characteristics: Biomass fuels may exhibit different combustion properties, requiring modifications to existing boiler systems to optimise performance and reduce emissions. For instance, maintaining superheater steam temperatures above 485°C poses challenges due to fouling and deposit formation as hard scale in the superheater. To mitigate this, steam and sonic horns may be operated. Travelling grate boilers are typically used for biomass.
Government Support and Schemes
India:
The Indian government has initiated several schemes to promote biomass utilisation, including the National Bioenergy Mission and various subsidies for biomass-based power generation projects. Programs like the Pradhan Mantri Ujjwala Yojana also encourage cleaner cooking fuel alternatives, indirectly supporting biomass use.
In West Africa, initiatives from organisations such as the Global Environment Facility (GEF) and partnerships with NGOs aim to promote sustainable biomass energy solutions. While specific subsidies may be limited, international funding opportunities are available for projects that enhance biomass utilisation.
Overview
Boiler Installation: A company can plan to install boilers to produce steam for power generation. The fuel will primarily consist of Napier grass, bamboo chips and other biomass materials such as wheat straw, mustard husk straw, soya straw etc. The technology can involve spreader stoker boilers/travelling grate boilers with auxiliary systems including fans, electrostatic precipitators (ESP), and feed pumps. The steam pressure can be 66 Bar, with a temperature of 480°C. Additional heat recovery systems such as economisers and air preheaters will be implemented to optimise efficiency.
Electrostatic Precipitator (ESP) for Biomass-Fired Boiler
An electrostatic precipitator (ESP) is essential for controlling suspended particulate matter (SPM) emissions from biomass-fired boilers, ensuring compliance with global pollution standards.
Key Functions
- Particulate Matter Removal-ESPs achieve over 99% efficiency in capturing SPM, keeping emissions within regulatory limits.
- SOx Control-Lime is dosed to neutralize sulfur oxides (SOx) by converting them into calcium sulfite, effectively reducing emissions.
- NOx Control-Selective Non-Catalytic Reduction (SNCR) technology utilizes ammonia to convert nitrogen oxides (NOx) into nitrogen and water vapour, minimizing NOx emissions.
Compliance
Continuous monitoring systems ensure real-time tracking of emissions, maintaining compliance with world standards for air quality. Regular maintenance of the ESP is crucial for optimal performance.
The integration of an ESP with SOx and NOx control measures ensures that biomass-fired boilers operate within the stringent limits of global pollution standards, promoting cleaner air and sustainability.
Steam Turbine Generating Set
Steam generated from biomass boilers will be directed to a steam turbine generator (STG) to produce 4 power typically at 11 kV and 50 Hz frequency. The STG will include auxiliary systems like a lubricating and control oil system, low-voltage and neutral grounding (LAVT and NGR), gland vent, steam condensing system, and connected high-pressure (HP) and low-pressure (LP) heaters.
Cooling Tower System
After power generation, the steam will be condensed, and the feed water will be reused in the boilers. An induced draft cooling tower system will be installed, equipped with circulating water pumps to supply water to the condenser and cool the steam back to liquid form. The cooling water will maintain inlet temperatures at 32°C and outlet temperatures at 42°C.
RO/DM Plant
The water used in the power plant will be demineralized to remove hardness and total dissolved solids (TDS). The requirement for approximately 5% makeup water will be fulfilled by an X m³/hr RO/DM plant, which will include processes for pre-treatment, reverse osmosis, ultrafiltration (UF), and demineralization. Storage of demineralized water will be in X m³ tanks.
Fuel Preparation Plant
The biomass fuel will be conveyed via belt conveyors to the bunker and then to the boilers for firing. Napier grass will be processed in cutters to achieve a size suitable for firing in the boilers, specifically less than 20 mm. The processed material will be stored in boiler bunkers for efficient firing.
Ash Handling System
Ash from boilers will be conveyed to silos using wet methods and pneumatic systems for further disposal. Fly ash will be utilized in cement production or brick making, while bed ash can be used as a landfill.
RCC Chimney
A 50-meter high and 4-meter diameter RCC chimney will be constructed for the waste heat recovery boiler to release flue gases. The chimney will be equipped with measurement devices to monitor suspended particulate matter (SPM), sulfur oxides (SOx), and nitrogen oxides (NOx) to ensure compliance with pollution control standards. A common RCC chimney, 100 meters tall and tapering in diameter, will also be constructed to accommodate flue gases from the two fired boilers. Continuous emissions monitoring systems (CEMS) will be installed to measure SPM, SOx, and NOx.
Electrical Evacuation and Distribution System
The power generated at the generator terminals will be evacuated and distributed to auxiliary systems and the plant through transformers and switchgear. The plant will utilize a low-tension (LT) distribution system for operational requirements.
Distribution Control System
A centralized distribution control system (DCS) will manage the plant operations using advanced logic for all sections. Field instruments will connect to field control systems, further communicating through a computer system and control software. Control and protection systems for the generator will be installed within the turbine generator building.
Piping Systems
Steam from all boilers will be supplied to a common steam distribution header, which will then supply the STG for power generation. After condensation in the turbine generator, feed water will be stored in a deaerator for reuse in the boilers, maintaining closed circulation. Makeup water will be sourced from the RO/DM plant. Additional piping will include cooling water, auxiliary cooling, and air piping for instrument control.
TG Building and Equipment Foundations
The civil package will encompass a turbine generator (TG) building that includes electrical evacuation systems, a control room, and office spaces. Facilities for the air compressor and the DM plant will also be required. The foundations for the boilers, STG, and all other equipment will be part of the civil package.
Additional packages will include overhead travelling (EOT) cranes, air compressors, an air conditioning system, and a fire-fighting system, integral to the complete power plant (CPP)
Fuel Utilization for Local Livelihood Improvement and Environmental Sustainability:
The transition from coal to biomass for electricity production presents a transformative opportunity for a nation, fostering local livelihoods while enhancing environmental sustainability. By establishing biomass (Napier grass-fired boiler) plants, communities can harness locally available organic materials such as agricultural residues and waste, creating jobs and stimulating economic growth.
This shift not only reduces reliance on coal, thus lowering greenhouse gas emissions and air pollution but also promotes sustainable agricultural practices as farmers can benefit from the sale of their biomass waste. Guinea can improve energy access for rural populations, thereby elevating living standards and empowering communities. This integrated approach not only supports the environment but also ensures a resilient and sustainable energy future for the country.
In summary, the use of Napier grass for biomass energy in a nation offers a holistic approach to enhancing local livelihoods. By creating jobs, diversifying income, and fostering community resilience, this initiative not only meets immediate energy needs but also lays the groundwork for long-term economic and social benefits, positioning the country as a potential model for sustainable development.
Conclusion
The integration of biomass into boiler systems represents a significant step towards a sustainable, renewable energy future, moving away from coal reliance. While challenges such as supply chain management, and combustion characteristics are to be addressed, the environmental, economic, and social benefits of biomass technology highlight its potential. Investing in this transition not only supports energy security but also promotes local economies and waste reduction initiatives.
Author:
Mr. Ashwini Mishra
Vice President
Gallantt Ispat Limited
Your insightfull article on the integration of biomass into boiler systems is amazing. It articulately highlights the necessary shift towards a more sustainable, renewable energy future while moving away from coal reliance. The challenges outlined regarding supply chain management and combustion characteristics are present, yet the environmental, economic, and social benefits truly underscore the potential of biomass technology.
The article also delves into critical details concerning boilers, turbines, and other power plant sections, offering a comprehensive view for those interested in implementing biomass solutions. I highly encourage you to read it if you haven’t already.
I kindly request that everyone share and repost this informative piece article widely within your networks. It’s a fantastic resource for anyone looking to support energy security, bolster local economies, and promote waste reduction initiatives through biomass technology.