Biomass Boilers Research Papers - Academia.edu (original) (raw)

This paper presents a methodology to optimize the size (electric power) of a cogeneration plant based on a biomass-fired Organic Rankine Cycle and connected to an existing district heating network, maximizing profitability. First, a model to determine the hourly thermal energy demand profile of a location in Spain has been derived, from open access meteorological data included in Spanish building regulations. Partial load model of an organic Rankine plant has also been obtained to increase the operation hours. These tools have been applied to two locations in Spain with different climatic severities, calculating the optimal size of the plant. The business model does not include subsidies. Calculations show that for population between 10,000 and 20,000 inhabitants the size of the plant ranges from 2 to 9 MWe and the internal rate of return ranges from 6% to 18%. The coverage of the thermal energy demand ranges from 40% to 80%. Regarding the trigeneration mode, it is concluded that cooling is only worth in locations with high summer severity and in full load operation mode, being the optimal size of the plant smaller in trigeneration mode than in cogeneration.

- by María Uris
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- Engineering, Mechanical Engineering, Environmental Science, Energy

A methodology of assessing a cogeneration system on a ship is proposed. Given the mass flow rate of exhaust gas and cooling seawater and the inlet temperatures of the gas and seawater, the net power of this system can be obtained through an iterative method. The parameters of mass flow rate of exhaust gas, heat transfer area of boiler and condenser and outlet temperature of the gas from the boiler are considered. In the heating process, the boiler tubes contain superheated, saturated and subcooled sections. It is shown that the dimensionless saturated area of the boiler increases with exhaust mass flow rate, whereas the superheated region tends to decrease on increasing the mass flow rate of flue gas at a fixed exhaust temperature. As for the subcooled portion, no significant change is observed. The power consumption of the working fluid circulating pump increases as the exit exhaust temperature from the boiler decreases. In addition, the more net work the turbine produces, the lower is the outlet temperature of the working fluid in the condenser for a fixed mass flow rate of exhaust gas. The net output of the cogeneration system is larger for a larger mass flow rate and a smaller exit temperature of the exhaust. Finally, an experiment is conducted to validate the proposed model.

Micro-cogeneration (micro-combined heat and power) is a technology that simultaneously produces decentralized thermal and electrical energy with a power of less than 50 kWel. This technology consists of using the waste heat generated by a thermodynamic process to meet the heating and hot water demands of buildings. The use of biomass as a fuel offers important advantages: use of a renewable energy, carbon neutrality, availability, and low cost. Furthermore, the analysis and optimization of hybrid energy systems, which include existing micro-cogeneration systems powered by renewable energy, is a scientific challenge needing experimental characterization of such micro-cogeneration systems. In this context, a biomass Stirling micro-CHP unit (μCHP), was tested to characterize its energy performance. A dynamic model based on these experimental investigations was developed to evaluate its thermal power output and energy efficiencies. The dependence of the nominal load on the water flow ra...

- by Stefan-Dominic Voronca
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- Engineering, Renewable Energy, Process Engineering, Physical sciences

- by josé Ignacio Linares
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- Engineering, Mechanical Engineering, Environmental Science, Energy
- by Sudharshan Raman
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- Materials Science, Metallurgy, Corrosion, Thermal Spray Coatings

The concern for Global Warming and Climate change had already made a social impact in the planet earth & corporate strategy on mitigating plan need to be adopted to restore ecological balance & our sustainability. While any economic growth is associated with Industrial developments , which will trigger a new concern to the environment , innovative adoption of various energy efficient processes will ensure better Carbon foot print. In India for any sustained growth the requirement of Power will always increase & new Power Stations need to be set up. While setting up Power stations considerations need to be given for selecting appropriate technology, size & selection of energy efficient process and equipment, optimize the combustion process .Role of analysers for measurement and control plays a major role to optimize the process operation & reducing fuel and energy wastages. Further selection of the appropriate technology for analyser , proper installation practices & control strategy based on the analysis and its response time are the key considerations for successfully implementing automatic combustion Control. This paper aims to describe the challenges in the selection of the appropriate gas analysers for the measurement based on the various technological versions , the analysis of the result & implementation of control to improve Carbon Foot Print .

- by SUGATA BANDYOPADHYAY
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- Environmental Science, Combustion, Waste Management, Process Engineering

The drying behavior of banana slices was studied in a combined heat and power dryer system at 4 engine load levels (25%, 50%, 75%, and 100%) and at three levels of drying product thickness (3, 5, and 7 mm) with the constant airflow velocity of 1 m/s. Results from the mathematical modeling showed that the Midilli et al. model gave the best fit to the experimental data. The present study confirms the importance of heat recovery to improve the system energy consumption and efficiency. Energy efficiency of this dryer was from 11% to 20% higher than that of electricity efficiency. Also, the specific energy consumption varied between 409 and 957 kWh/kgwater. The lowest value of energy consumption and highest value of energy efficiency were observed at 75% engine load and 3 mm thickness of sample.

- by Barat Ghobadian
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- Environmental Science, Chemistry

A 7 MWth combined heat and power plant (CHP) based on an organic Rankine cycle (ORC) with 5.3 MWth and 1 MWel nominal output is analyzed. A district heating system serves as heat sink; the entire system is heat-led. Two examples for winter and summer operation are shown. The observed characteristics of the condenser are compared to results of a theoretical model. Variable mass flows, temperature levels (72 °C–95 °C) and temperature spreads result in varying condensation temperatures and pressure levels in the condenser (90 mbar to 150 mbar). High mass flows on the secondary side and related low temperature spreads improve the heat transfer and increase the condensation rate in the condenser. The monitoring data support the findings of a steady-state condenser model. As a consequence, advantageous load profiles according to the pressure characteristic of the system can be reached. Live steam pressure, pressure difference across the turbine, and flow rate increase. The effect on the e...

- by Ursula Eicker
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- Mechanical Engineering, Aerospace Engineering, Water, Stress
- by Dagnija Blumberga
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- Elsevier

The paper analyses low grade heat recovery problem for modern woodfuel cogeneration plant. The woodfuel flue gas, behind the condensing economizer, still contains a considerable amount of heat, main part of which is the latent one. To recover this low grade heat, the heat pump technology can be used, which is related with additional consumption of energy (electric, mechanical or heat). Another technique that could be applied is a heat regeneration when flue gas heat, mostly latent, is transmitted to air blown towards burning chamber. Therefore, the analysed heat recovery system operates mainly like mass regenerator which contains only blowers that use some electric energy. The regenerator consists of two cyclically operating columns with packing material. Energetic analysis demonstrates that 13% of additional heat can be produced utilizing this low grade heat. The economic valuation shows that investment in a heat recovery system is quite effective; the payback time is about four years.

- by Algimantas Balčius
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- Environmental Science, Thermal Science

The installation of a biomass-fired Organic Rankine Cycle (ORC) unit coupled to a heat storage system (HSS) in an existing district heating (DH) system is proposed and analyzed from both energetic and economic point of view. A real DH system is considered as case study, and the optimal layout configuration is investigated varying the size of the components. The analysis is carried out tuning the heat demand dataset obtained from real data of a different existing DH systemwith a 6-min time step and ten years of operation. The heat demand is used to match the production from different generation units. The overall efficiency of the system, the primary energy savings related to CHP production, as well as the pay back time of the investment are evaluated. Calculations show that for the considered case study the maximum size of the HSS that gives noticeable advantages is 150 m/MWth. The optimal configuration is different when considering energetic or economic criteria. Moreover, the curr...

Low enthalpy geothermal based Combined Cooling, Heating and Power (CCHP) system for building is expected can increase energy efficiency and reduce carbon dioxide emission. The aim of this study is to assess techno-economic performances of a CCHP for hotel building in tropical countries with total energy demand of 7.64 MW. The fresh geothermal fluid was divided by 15% to power generation system of Organic Rankine Cycle (ORC) and the waste heat merged with the rest fresh geothermal to absorption refrigeration system and heating systems. Cycle Tempo and COMSOL are used to simulate CCHP system and a borehole of hot sedimentary aquifer (HSA), respectively. The simulation results indicate that total CCHP system efficiency is 36.61% consist of ORC efficiency and absorption cycle efficiency are 12.77% and 57.88%, respectively with emission reduction of 1.4 ton CO2 eq. per year compare to conventional grid electricity. The best business scheme was BOO with financial incentives, which were ta...

- by Heru Prasetio
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The use of biomass for decentralized energy production has undergone a significant development the last years. The fact that this fuel is CO 2-free provides many advantages in European and world aims for sustainable energy sources. Biomass trigeneration is a relatively new concept, which has the potential to improve the bioenergy economics for areas with warm climate, for which traditional biomass cogeneration was unfeasible. This concept can be applied with various energy conversion technologies, two of which are investigated in this paper: ORC and gasification. Both technologies are applied for a specific case study. The technological and financial comparison of the two technologies shows that gasification offers improved yield for the investment, mainly due to the higher electrical efficiency factor. However, attention should be placed to the increased investment risk of gasification projects, which could be an aversive factor for some investors.

- by E. Kakaras
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- Energy Conversion, Economic analysis, Case Study, Organic rankine cycle

Foreseeing a promising future of utilizing bio-energy, more and more small-scale biomass power plants are recently built. Biomasses with high moisture content such as sludge or Empty Fruit Bunch are often used as fuel in small-scale power plant without proper drying. These highly moist biomasses reduce the efficiency of the boiler but on the other hand drying the biofuel is also an energy intensive process. This paper aims to investigate how drying would affect the overall energy efficiency while proper heat integration in between the drying and power plant is under consideration. A 12.5 MW biomass power plant that burns EFB with 60 wt% moisture is used as a base case. Two types of dryer, Hot Air Dryer (HAD) and Superheated Steam Dryer (SSD), are proposed for the drying process. These two dryers require heat at different temperature levels to provide a better chance for heat integration. Material and energy balance models of the dryers and boilers are derived in this paper and the steam power plant model is constructed in Aspen Plus. The results of this study show that with proper drying and heat integration, the overall efficiency can be improved by more than 5%, when compared to process without drying.

- by Adetoyese Oyedun
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- Mechanical Engineering, Civil Engineering, Biomass, Energy

Combining the economics and the environmental and social aspects of bioenergy chain implementation is a difficult task, particularly for wood fuel production. Multiple aspects, such as financial analysis, technology development, natural resource exploitation and avoided environmental pollution, must be considered simultaneously. Thus, decision support models seem to be the proper tools for the overall definition of strategies in the wood energy sector. The objective of this study has been to develop a partial equilibrium model able to quantify the socioeconomic and environmental effects of policy, technology and best biomass allocation scenarios on the forest residue chain. The model, based on multi-objective linear programming and spatial analysis, considers the financial benefits/losses and the potential trends of three compartments: sawmills, forest enterprises and energy plants. In addition, the model computes avoided emissions for bioheat and bioelectricity production and introduces an impact indicator for the road transport of biomass. Model outputs are defined using a multi criteria approach. The main results stress the importance of both environmental parameters and the implementation of organic Rankine cycle technology for the optimization of the entire bioenergy chain. The model was tested in an Italian Alpine region (province of Trento).

Aviel Verbruggen teaches energy and environmental economics and policy at the University of Antwerp in Belgium. Since the 1970s, he has studied cogeneration issues in district heating, building, industrial, and gas network applications,... more

KCl-induced high-temperature corrosion behavior of four HVAF-sprayed Ni-based coatings (Ni21Cr, Ni5Al, Ni21Cr7Al1Y and Ni21Cr9Mo) under KCl deposit has been investigated in ambient air at 600°C up to 168 h. The coatings were deposited onto 16Mo3 steel-a widely used boiler tube material. Uncoated substrate, 304L and Sanicro 25 were used as reference materials in the test environment. SEM/EDS and XRD techniques were utilized to characterize the as-sprayed and exposed samples. The results showed that the small addition of KCl significantly accelerated degradation to the coatings. All coatings provided better corrosion resistance compared to the reference materials. The alumina-forming Ni5Al coating under KCl deposit was capable of forming a more protective oxide scale compared to the chromia-forming coatings as penetration of Cl through diffusion paths was hindered. Both active corrosion and chromate formation mechanisms were found to be responsible for the corrosion damages. The corrosion resistance of the coatings based on the microstructure analysis and kinetics had the following ranking (from the best to worst): Ni5Al [ Ni21Cr [ Ni21Cr7Al1Y [ Ni21Cr9Mo.

- by Reza Jafari
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- Materials Engineering, Mechanical Engineering, Microstructure, Thermal Spray Coating

h i g h l i g h t s Analysis of a wood-biomass ORC unit in an existing DH system. Parametric study with optimization on ORC size and heat storage system size. Simulation of heat demand from a dataset of a similar DH system in operation. Different optimal configurations when considering energetic or economic criteria. The Italian incentive still not encourages system layouts with higher efficiency.

Power generation from biomass based renewable energy technologies is a promising option in retrofitting our dependence in conventional power generation processes. The development of any society is not possible without sustainable energy and access to energy creates that environment that allows the world to thrive. Electricity access especially in developing regions of the world is of particular interest. This work provides results on electricity efficiency, the economic feasibility and environmental impact of biomass based power technologies in small scale setting using Aspen Plus software. The power generation processes analysed on standalone basis include - micro gas turbine, gas turbine, steam turbine, Stirling engine and internal combustion engine. Some of the processes are optimized in the design to suit the specific climate and available wood waste stream in Nigeria is considered in this work. Simulation results indicate that gas engines power technologies gave a better electr...

- by Godswill Megwai
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- Text

Biomass combustion is mainly used for heat production in a wide range of units. Few research studies have been carried out to investigate the overall performance of small-scale residential heating systems when replacing coal with biomass in these units. Sheffield University (SUWIC) has carried out an extensive series of experimental tests at a small-scale residential heating plant. Various tests were conducted on two units: a wood pellet fired boiler and a coal fired boiler. In addition, mathematical modeling work using FLIC and FLUENT codes was carried out in order to simulate the overall performance of the small-scale biomass and coal-fired heating systems. The main objective of this study was to investigate the changes to the overall performance of the plant (e.g., combustion characteristics and emissions) when replacing coal with wood pellets. The concentrations of CO, NO x , particulate matter, and SO 2 in the flue gases were measured. Emission factors for both boilers were also compared. FLIC code integrated with FLUENT was employed to model the combustion process of wood pellets and coal in both boilers. The measured emission data were used in the development and validation of the modeling work. The modeling work helped to demonstrate the relationship between the fuel combustion behavior and pollutants formation in the residential boilers. Results showed that pollutant emissions from both boilers were within relative emission limits whereas pollutant emission factors for the wood pellet-fired boilers were lower than for the coal-fired boiler. The modeling analysis showed that the high CO emissions from the coal-fired boiler were attributed to the less mixing intensity and low residential time of flue gas in the furnace. For small-scale residential boilers, biomass with a high volatile fraction could be an ideal solid fuel to get higher combustion efficiency and low pollutant emissions. This study has provided valuable information that can be used to help improve future furnace design and retrofit existing small-scale heating systems to reduce overall emissions.

- by Richard Bradford
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- Engineering, CHEMICAL SCIENCES, Energy and Fuels

- by Richard Bradford
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- Engineering, CHEMICAL SCIENCES, Energy and Fuels

Hybridisation of district heating systems can contribute to more efficient heat generation through cogeneration power plants or through an increase in the share of renewable energy sources in total energy consumption while reducing negative aspects of particular energy source utilisation. In this work, the performance of a hybrid district energy system for a small town in Croatia has been analysed. A mathematical model for process analysis and optimisation algorithm for optimal system configuration have been developed and described. The main goal of the system optimisation is to reduce heat production costs. Several energy sources for heat production have been considered in 8 different simulation cases. Simulation results show that the heat production costs could be reduced with introduction of different energy systems into an existing district heating system. Renewable energy based district heating systems could contribute to heat production costs decrease in district heating systems up to 30% in comparison with highly efficient heat production technologies based on conventional fuels.

- by Henrik Lund
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- by Reza Jafari
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- Microstructure, Thermal Spray Coating, Corrosion Engineering, Corrosion

This paper describes the development of a small-scale system designed to generate electricity from low temperature heat (e.g., solar energy). The system operates on the Rankine cycle and uses n-pentane as the working¯uid. A prototype system has been designed, constructed and tested. It is capable of delivering 1.5 kW of electricity with a thermal eciency of 4.3%. Laboratory test results and a cost estimate for the prototype unit are presented in the paper. 7

- by saffa riffat
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- Mechanical Engineering, System Design, Cost Estimation, Solar Energy

- by Neven Duic
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This article is focused on technical and economic evaluation of more than 6-years experiences of operating the Waste Heat Recovery technology-the manner and system of flue gas processing generated in the combustion process in heat & power plants, cogeneration units, etc., which burn the gaseous fuel, primarily natural gas, or methane, biogas, geothermal gas, or other gaseous mixtures containing hydrogen. The solution proposes a more effective and non-traditional use of gaseous fuel for heating, the flue gases of which are processed in order to extract additional utilisable heat, with potential elimination of CO 2 from them. Deploying of the heating plant in an island regime (OFF-GRID) enables definition of the benefits brought by the 3 years of operational experience and presents visions for the future offering the possibility to utilise the support energy services at the municipal as well as regional level.

The paper presents results of techno-economic analysis of using wood residues from wood industry for CHP (combined heat and power). The aim was to determine the economic feasibility of CHP in Serbia in the light of newly adopted feed in tariffs. In the first part, costs of electricity production are calculated for five different types of CHP technology which could meet the needs of wood industry in Serbia. In the second part of the paper, sawmill wood processing and pellet production were taken into consideration. First, we found that the installation of CHP in small capacity sawmills (about 10,000 m 3 /year) is not economically justified. The main reasons are high investments in micro CHP (up to 100 kW el ) per kW of power. Second, the approximate electricity production costs in the potential CHP installations in pellet factory with capacity about 50,000 tonne per year is only slightly lower than the offered purchase price. However, advancement in CHP technologies and increase of the number of implemented projects should lead to a drop of equipment prices. Regardless of the price increase of raw materials and labour, this drop will have a significant impact on the reduction of total costs of electricity generation with CHP becoming more attractive to investors.

- by Gradimir Danon
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- Mechanical Engineering, Energy, Interdisciplinary Engineering

- by Godswill Megwai
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- Text

Generally, a CHP plant coupled with district heating is considered more efficient than traditional local heating systems from an economic and environmental point of view. This is certainly true for municipal waste CHP plants but for plants fuelled by natural gas the important developments intervened in these last years regarding both boilers (premixed and modulating burners, condensing boilers, etc.), mechanical vapour compression and absorption heat pumps can change the traditional view. At the same time also district heating plants improved. Therefore it is worth to analyse the whole matter comparing advantages and disadvantages of the different alternatives with their wide differentiation among them. The paper reports on the analysis of major district heating natural gas based technologies (vapour and gas turbines, internal combustion engine, combined cycles); the cost of the heat power produced in these plants is compared to the cost of producing the same quantity of electrical energy by a reference GTCC-Gas Turbine Combined Cycle (actually the most efficient technology for pure electrical production) and the cost of heat production by modern local heating technologies using natural gas as fuel (condensing boilers, electrical, gas engine and absorption heat pumps). Regarding energy efficiency and polluting emissions, modern local heating turns out to be more efficient than district heating for most CHP technologies. However, it is not the same from the economic point of view, because in Italy natural gas used by cogeneration plants is subjected to a taxation much lower than local heating technologies.

- by Marco Noro
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The use of biomass for decentralised energy production has undergone a significant development the last years. The fact that this fuel is CO 2 -free provides many advantages in European and world aims for sustainable energy sources. Biomass trigeneration is a relatively new concept, which has the potential to improve the bioenergy economics for areas with warm climate, for which traditional biomass cogeneration was unfeasible. This concept can be applied with various energy conversion technologies, two of which are investigated in this paper: ORC and gasification. Both technologies are applied for a specific case study. The technological and financial comparison of the two technologies shows that  * Corresponding author: Tel: +30-210 7722383 Fax: +30-210 7723571 email address: arent@central.ntua.gr (A. Rentizelas) gasification offers improved yield for the investment, mainly due to the higher electrical efficiency factor. However, attention should be placed to the increased investment risk of gasification projects, which could be an aversive factor for some investors.

- by Athanasios Rentizelas
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- Energy Conversion, Economic analysis, Case Study, Organic rankine cycle

- by Athanasios Rentizelas and +1
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- Energy Conversion, Economic analysis, Case Study, Organic rankine cycle

Within the scope of a comprehensive study and two development and demonstration projects, various technologies in the power range of up to 2 MWel for small-scale biomass-fired CHP plants have been investigated, evaluated and compared considering technical as well as economic aspects. Such plants should normally be operated on a heat-controlled basis in order to achieve a high overall efficiency and should run for more than 5,000 annual full load operating hours to ensure economical operation. Two of the technologies examined are very promising and innovative: the Organic Rankine Cycle (ORC) process and the Stirling engine process. The ORC process represents an economically interesting technology for small-scale biomass-fired combined heat and power plants in a power range between 400 and 1,500 kWel. A newly developed ORC technology with a nominal electric capacity of 1,000 kW was implemented in the biomass CHP plant Lienz (A) in the framework of an EU demonstration project. This pla...

- by Ingwald Obernberger
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The importance of optimal sizing of renewable microgeneration systems is addressed. A hybrid system made up of solar and micro-CHP devices is considered. Both Photovoltaic and high concentration PV technologies are analysed. Optimal sizing enhances savings in dwelling sector applications. Electricity grid constraints can have the potential CO 2 emissions reduction.

- by Massimiliano Renzi and +1
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- Mechanical Engineering, Interdisciplinary Engineering, Applied Thermal Engineering

- by Marija Mandic
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- Mechanical Engineering, Energy, Interdisciplinary Engineering

More than seventy district heating (DH) plants based on biomass are operating in South Tyrol (Italy) and most of them supply heat to residential districts. Almost 20% of them are cogenerative systems, thus enabling primary energy savings with respect to the separate production of heat and power. However, the actual performance of these systems in real operation can considerably differ from the nominal one. The main objectives of this work are the assessment of the energy performance of a biomass boiler coupled with an Organic Rankine Cycle (i.e., ORC) generator under real operating conditions and the identification of its potential improvements. The fluxes of energy and mass of the plant have been measured onsite. This experimental evaluation has been supplemented with a thermodynamic model of the ORC generator, calibrated with the experimental data, which is capable to predict the system performance under different management strategies of the system. The results have highlighted that a decrease of the DH network temperature of 10 °C can improve the electric efficiency of the ORC generator of one percentage point. Moreover, a DH temperature reduction could decrease the main losses of the boiler, namely the exhaust latent thermal loss and the exhaust sensible thermal loss, which account for 9% and 16% of the boiler input power, respectively. The analysis of the plant has pointed out that the ORC pump, the flue gases extractor, the thermal oil pump and the condensation section fan are the main responsible of the electric self-consumption. Finally, the negative effect of the subsidisation on the performance of the plant has been discussed.

- by dario prando
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- Organic rankine cycle, CHP, Biomass Boilers
- by Panayiotou Pambos
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- Energy Conversion, Economic analysis, Case Study, Organic rankine cycle

Biomass plays an important role in the world primary energy supplies, currently providing 14% of the world’s primary energy needs and being the fourth largest contributor following coal, oil and natural gas. Over the past decade, domestic biomass heating has received more governmental and public supports than ever before in many developed countries, such as the UK. Although biomass combustion releases some combustion pollutants, biomass is renewable and produces little net CO2 emissions to the atmosphere. Owing to the low sulphur and low nitrogen contents of many biomass materials, substituting biomass for fossil fuels, particularly coal, can reduce SOx and NOx emissions. This study investigated flue gas emissions, particularly carbon monoxide and nitrogen oxides, of a
domestic biomass boiler under various operating conditions. The biomass boiler used in this study satisfies the current EU regulation (EN 303-05) on emissions of domestic biomass boilers. Emissions of the boiler had been measured not only under normal combustion conditions, but also under ‘idle’ combustion conditions when the boiler was not in but was ready for full operation. The experimental results are analysed and presented in this paper.

- by Hao Liu
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- Biomass Boilers