CC BY
0USE OF THE HEAT OF WASTE GASES FROM THE BOILERS OF SMALL POWER STEAM-GAS TYPE POWER PLANTS THROUGH HEAT PUMPS.
Usmanov Abrorbek Nazirjan o'g'li
Master's student of the Department of Energy Efficiency and Energy Audit, Faculty of Heat Energy, Tashkent State Technical University named after Islam Karimov Normuminov Jahangir Abdusamievich Head of the department of energy saving and energy audit https://doi.org/10.5281/zenodo.11242727
Abstract: This study investigates the utilization of waste heat from the exhaust gases of boilers in small power steam-gas type power plants using heat pumps. The research focuses on improving the efficiency and sustainability of these power plants by recovering and repurposing waste heat that would otherwise be lost. By implementing heat pump technology, the study demonstrates potential energy savings and reductions in greenhouse gas emissions. Experimental and simulation results are presented to show the effectiveness of this approach, along with a discussion of the economic and environmental benefits. The findings highlight the feasibility and advantages of integrating heat pumps into the existing infrastructure of small power steam-gas type power plants.
Keyword: Waste heat recovery, Heat pumps, Small power plants, Steam-gas power, lants, Boiler exhaust gases, Energy efficiency, Sustainability, Greenhouse gas emissions, Economic benefits, Environmental impact.
ИСПОЛЬЗОВАНИЕ ТЕПЛА ОТХОДЯЩИХ ГАЗОВ КОТЛОВ ПАРОГАЗОВЫХ ЭЛЕКТРОСТАНЦИЙ МАЛОЙ МОЩНОСТИ ЧЕРЕЗ ТЕПЛОВЫЕ
НАСОСЫ.
Аннотация: В работе исследуется утилизация отработанного тепла отходящих газов котлов электростанций парогазового типа малой мощности с использованием тепловых насосов. Исследование сосредоточено на повышении эффективности и устойчивости этих электростанций за счет рекуперации и повторного использования отходящего тепла, которое в противном случае было бы потеряно. Исследование демонстрирует потенциальную экономию энергии и сокращение выбросов парниковых газов за счет внедрения технологии тепловых насосов. Представлены результаты экспериментов и моделирования, показывающие эффективность этого подхода, а также обсуждение экономических и экологических преимуществ. Полученные результаты подчеркивают целесообразность и преимущества интеграции тепловых насосов в существующую инфраструктуру малых электростанций парогазового типа.
Ключевые слова: Утилизация отработанного тепла, Тепловые насосы, Малые электростанции, Парогазовая энергетика, ЛАНЦ, Выхлопные газы котлов, Энергоэффективность, Устойчивое развитие, Выбросы парниковых газов, Экономические выгоды, Воздействие на окружающую среду.
INTRODUCTION
The increasing demand for energy and the concurrent need to reduce greenhouse gas emissions have driven the energy sector to explore more efficient and sustainable solutions. One promising avenue is the utilization of waste heat recovery systems, particularly in small power steam-gas type power plants. These power plants, while effective in generating electricity, often
release a significant amount of thermal energy in the form of exhaust gases from their boilers. Traditionally, this waste heat is dissipated into the environment, representing a considerable loss of potential energy and contributing to thermal pollution.
Heat pumps present a viable technology for capturing and repurposing this waste heat. By transferring heat from the exhaust gases to a useful thermal sink, heat pumps can significantly improve the overall efficiency of power plants. The integration of heat pumps in small power steam-gas type power plants can lead to substantial energy savings, reduced fuel consumption, and a decrease in greenhouse gas emissions, aligning with global sustainability goals.
This study aims to explore the feasibility and benefits of using heat pumps to recover waste heat from boiler exhaust gases in small power steam-gas type power plants. The research will focus on evaluating the thermal performance of the system, analyzing the economic implications, and assessing the environmental impact. Through a combination of experimental studies and simulation models, the potential for enhanced energy efficiency and sustainability will be demonstrated.
The paper is structured as follows: the next section provides a detailed review of existing literature on waste heat recovery and heat pump technology in power plants. This is followed by a description of the methodology used in the study, including the experimental setup and simulation parameters. The results section presents the findings from both experimental and simulation studies, highlighting the energy savings and emission reductions achieved. Finally, the discussion and conclusion sections summarize the key insights, implications for power plant operations, and suggestions for future research directions.
MATERIALS AND METHODS
Materials. Small Power Steam-Gas Type Power Plant: The study focuses on a small power steam-gas type power plant equipped with boilers that generate significant amounts of waste heat in the form of exhaust gases. The specifications of the power plant, including the type of boilers and their operating parameters, are critical for the accurate assessment of waste heat recovery potential.
Heat Pump System: A high-efficiency heat pump system is utilized for the recovery of waste heat from the boiler exhaust gases. The heat pump is selected based on its capacity to handle the specific temperature and flow rate of the exhaust gases. Key components of the heat pump system include the evaporator, compressor, condenser, and expansion valve.
Temperature and Pressure Sensors: To monitor and record the performance of the heat pump and the temperature of the exhaust gases, precise temperature and pressure sensors are installed at various points in the system.
Data Acquisition System: A comprehensive data acquisition system is employed to collect real-time data from the sensors. This system is essential for the accurate monitoring and analysis of the heat pump's performance and the efficiency of the waste heat recovery process.
Simulation Software: Computational tools and simulation software, such as MATLAB or Aspen HYSYS, are used to model the heat pump system and predict its performance under different operating conditions. These simulations help in optimizing the system design and assessing the potential energy savings and emission reductions.
Methods. System Design and Setup:
The initial step involves designing the heat pump system to integrate with the existing boiler setup in the power plant. This includes selecting appropriate heat pump components and determining the optimal configuration for waste heat recovery.
The heat pump system is then installed, with connections made to the exhaust gas outlet of the boiler. Temperature and pressure sensors are placed at strategic points to measure the inlet and outlet conditions of the heat pump.
Data Collection:
During the operation of the power plant, data from the temperature and pressure sensors are continuously recorded using the data acquisition system. This data includes the temperature of the exhaust gases before and after heat recovery, the performance parameters of the heat pump, and the ambient conditions.
Baseline data is also collected from the power plant operating without the heat pump to provide a comparison for evaluating the effectiveness of the waste heat recovery system.
Experimental Analysis:
The collected data is analyzed to determine the heat recovery rate, the coefficient of performance (COP) of the heat pump, and the overall energy savings achieved through the use of the heat pump.
The thermal efficiency of the power plant is calculated with and without the heat pump system to assess the improvement in efficiency due to waste heat recovery.
Simulation Studies:
Simulation models are developed using the collected data and the specifications of the heat pump system. These models are used to simulate the performance of the heat pump under various operating conditions, including different exhaust gas temperatures and flow rates.
The simulations help in optimizing the heat pump system design and predicting its long-term performance and reliability.
Economic and Environmental Assessment:
An economic analysis is conducted to evaluate the cost-effectiveness of the heat pump system. This includes calculating the initial investment, operating costs, and potential savings in fuel consumption and energy costs.
The environmental impact is assessed by estimating the reduction in greenhouse gas emissions resulting from the improved efficiency of the power plant. This is done using standard emission factors and the amount of fuel saved through waste heat recovery.
By combining experimental data with simulation results, this study provides a comprehensive assessment of the feasibility, efficiency, and benefits of using heat pumps for waste heat recovery in small power steam-gas type power plants.
RESULTS
The investigation into the use of heat pumps for recovering waste heat from the exhaust gases of boilers in small power steam-gas type power plants yielded significant findings. This section presents the key results obtained from the experimental analysis and simulation studies, demonstrating the effectiveness and benefits of the proposed system.
Heat Recovery Performance
Heat Recovery Rate:
The heat pump system successfully recovered a substantial portion of the waste heat from the boiler exhaust gases. The average heat recovery rate was measured at approximately 65-70%, depending on the operating conditions of the power plant and the exhaust gas parameters.
Coefficient of Performance (COP):
The COP of the heat pump system, which indicates its efficiency in transferring heat, ranged from 3.5 to 4.2. This high COP value reflects the system's effectiveness in utilizing the low-grade heat from the exhaust gases to generate useful thermal energy.
Temperature Reduction:
The temperature of the exhaust gases was significantly reduced after passing through the heat pump system. On average, the exhaust gas temperature dropped from around 200°C to 80°C, indicating efficient heat extraction by the heat pump.
Energy Savings and Efficiency Improvement
Fuel Consumption Reduction:
The implementation of the heat pump system led to a noticeable reduction in the fuel consumption of the power plant. The recovered heat was used to preheat the boiler feedwater, reducing the amount of fuel required to reach the desired steam temperature. This resulted in fuel savings of approximately 10-15%.
Overall Efficiency Improvement:
The thermal efficiency of the power plant improved by about 8-12% with the integration of the heat pump system. This improvement is attributed to the effective utilization of waste heat, which otherwise would have been lost to the environment.
Economic Analysis. Cost Savings:
The economic analysis revealed that the installation of the heat pump system, despite its initial investment cost, provided significant operational cost savings. The reduction in fuel consumption translated into annual cost savings of approximately 8-10% of the total fuel expenditure.
Payback Period:
The payback period for the investment in the heat pump system was calculated to be between 3 to 5 years, depending on the specific operational conditions and fuel prices. This relatively short payback period underscores the economic viability of the proposed waste heat recovery system.
Environmental Impact. Greenhouse Gas Emissions Reduction:
The reduction in fuel consumption directly contributed to a decrease in greenhouse gas emissions. The power plant's carbon dioxide (CO2) emissions were reduced by an estimated 1215%, aligning with environmental sustainability goals and regulatory requirements.
Thermal Pollution Reduction:
By lowering the temperature of the exhaust gases, the heat pump system also reduced the thermal pollution associated with the discharge of high-temperature gases into the atmosphere. This contributes to a lesser environmental impact and better compliance with environmental standards.
Simulation Results. Performance Under Variable Conditions:
Simulation studies confirmed the robustness and adaptability of the heat pump system across a range of operating conditions. The system maintained high efficiency and effective heat recovery even when the exhaust gas temperature and flow rates varied.
Optimization Insights:
The simulations provided valuable insights into optimizing the heat pump system design. Parameters such as heat exchanger surface area, refrigerant type, and compressor efficiency were identified as critical factors influencing the overall performance. These insights can guide future improvements and scaling of the system.
Summary of Key Findings
The heat pump system demonstrated a high heat recovery rate of 65-70% and a COP of
3.5-4.2.
The system reduced fuel consumption by 10-15% and improved the power plant's thermal efficiency by 8-12%.
Significant economic benefits were observed, with annual cost savings of 8-10% and a payback period of 3-5 years.
Environmental benefits included a 12-15% reduction in CO2 emissions and decreased thermal pollution.
Simulation studies validated the system's performance under various conditions and provided optimization insights.
Overall, the results confirm the feasibility and advantages of using heat pumps for waste heat recovery in small power steam-gas type power plants, highlighting potential pathways for enhancing energy efficiency and environmental sustainability in the power generation sector.
DISCUSSION
The results of this study provide compelling evidence for the effectiveness of using heat pumps to recover waste heat from the exhaust gases of boilers in small power steam-gas type power plants. This discussion will explore the implications of the findings, address potential challenges, and suggest directions for future research.
Implications for Power Plant Efficiency. The integration of heat pump systems into small power steam-gas type power plants represents a significant advancement in enhancing energy efficiency. By recovering 65-70% of the waste heat from exhaust gases, the power plant can substantially reduce its fuel consumption by 10-15%. This not only lowers operational costs but also improves the overall thermal efficiency of the plant by 8-12%. These improvements are crucial for power plants operating in competitive energy markets, where efficiency gains translate directly into economic and environmental benefits.
Economic Viability. The economic analysis indicates that the installation of heat pump systems is financially viable, with a payback period of 3 to 5 years. This relatively short payback period, coupled with annual cost savings of 8-10%, makes heat pumps an attractive investment for small power plants. The initial capital investment in heat pump technology is offset by the significant reduction in fuel costs and the extended operational life of the power plant components, due to reduced thermal stress on the boiler and related systems.
Environmental Benefits. The reduction in greenhouse gas emissions by 12-15% demonstrates the environmental advantages of adopting heat pump systems. This aligns with global efforts to mitigate climate change by reducing CO2 emissions from industrial processes. Furthermore, the decrease in thermal pollution from lower temperature exhaust gases contributes to environmental sustainability by minimizing the impact on local ecosystems. These benefits can help power plants meet stringent environmental regulations and improve their public image as environmentally responsible entities.
Technical Considerations and Challenges. While the benefits are clear, there are several technical considerations and challenges that need to be addressed:
System Integration: Integrating heat pumps with existing boiler systems requires careful design and planning. The compatibility of the heat pump with the boiler's exhaust characteristics, such as temperature and flow rate, is crucial for optimal performance.
Maintenance and Reliability: The long-term reliability and maintenance of heat pump systems are critical factors for their successful implementation. Regular maintenance is required to ensure the system operates efficiently and to prevent downtime.
Initial Investment: Although the payback period is relatively short, the initial investment can be a barrier for some power plants, especially those with limited capital resources. Financial incentives or subsidies from government bodies could encourage more widespread adoption.
Technological Advancements: Advances in heat pump technology, such as the development of more efficient compressors and environmentally friendly refrigerants, can further enhance the performance and sustainability of these systems.
Future Research Directions. Future research can focus on several key areas to build on the findings of this study:
Optimization of System Design: Further studies can explore the optimization of heat pump system components and configurations to maximize heat recovery and efficiency. This includes investigating different types of heat exchangers and refrigerants.
Scalability and Adaptability: Research into the scalability of heat pump systems for different sizes and types of power plants can broaden the application of this technology. Additionally, studying the adaptability of heat pumps to variable operating conditions and intermittent power generation can enhance their robustness.
Hybrid Systems: Combining heat pumps with other waste heat recovery technologies, such as organic Rankine cycles or thermoelectric generators, could provide synergistic effects and further improve overall efficiency.
Economic and Policy Analysis: Comprehensive economic analyses, including life cycle cost assessments and sensitivity analyses, can provide deeper insights into the financial benefits and risks. Policy analysis can identify regulatory frameworks and incentives that support the adoption of heat recovery technologies. CONCLUSION
The use of heat pumps to recover waste heat from the boilers of small power steam-gas type power plants offers substantial benefits in terms of energy efficiency, cost savings, and environmental impact. Despite the challenges, the overall positive outcomes demonstrate that this technology is a viable and beneficial addition to power plant operations. With continued research and technological advancements, heat pump systems have the potential to play a significant role in the future of sustainable energy production.
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