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This paper presents methodologies and equipment for SI-traceable inline measurements of water content (a critical quality parameter) in solid biofuels. Inline measurement systems for water content are commonly used at CHP plants, providing continuous real-time data. However, the accuracy of these systems is in most cases unsatisfactory, mainly because the systems are not calibrated representatively for the relevant material, and until now, calibrations traceable to the SI system have not been available. To provide reliable and accurate inline water content data, new procedures and equipment for calibrating measurement systems were developed. Two reference methods for the determination of water content were developed; one measures the airflow and dewpoint of desorbed water in the air passing a test sample, while the other uses a P2O₅-sensor. Additionally, a transfer standard based on a cavity resonance sensor was developed for fast onsite calibration of the inline sensor at the power plant. This new instrument allows for quick and accurate measurements. The transfer standard is made metrologically traceable to the primary measurement standards. The entire system was demonstrated by calibrating an inline microwave-based (MW) sensor at the CHP plant of VERDO in Randers, Denmark. Thus, a complete metrological traceability chain was established from an industrial to a primary standard. [ABSTRACT FROM AUTHOR]

This work is focused on the energy recovery potential of olive-oil industry wastes in the region of Tizi Ouzou (north of Algeria). A theoretical modelling and simulation study of a small-scale CHP plant fuelled with olive pomace and olive tree pruning is carried out. The power plant proposed is composed of a downdraft gasifier, an externally fired gas turbine reaching an optimum electric power of 75.8 and 170.22 kW of thermal power. The electric efficiency achieved is 18.56% and the CHP efficiency is 60.26% for olive tree pruning gasification. The simulation results showed a satisfactory syngas lower calorific value (4.12–4.39 MJ/kg) and a gasification efficiency of 78.3–79.8%. The economic analysis of the plant shows a feasible payback period between 5 and 6 years with an interesting Profitability Index and Internal Rate of Return above 20% for both biomasses considered. Finally, the electrical energy generated with the plant proposed can cover the annual consumption of more than 46,000 inhabitants in Tizi Ouzou province.

This work is focused on the energy recovery potential of olive-oil industry wastes in the region of Tizi Ouzou (north of Algeria). A theoretical modelling and simulation study of a small-scale CHP plant fuelled with olive pomace and olive tree pruning is carried out. The power plant proposed is composed of a downdraft gasifier, an externally fired gas turbine reaching an optimum electric power of 75.8 and 170.22 kW of thermal power. The electric efficiency achieved is 18.56% and the CHP efficiency is 60.26% for olive tree pruning gasification. The simulation results showed a satisfactory syngas lower calorific value (4.12–4.39 MJ/kg) and a gasification efficiency of 78.3–79.8%. The economic analysis of the plant shows a feasible payback period between 5 and 6 years with an interesting Profitability Index and Internal Rate of Return above 20% for both biomasses considered. Finally, the electrical energy generated with the plant proposed can cover the annual consumption of more than 46,000 inhabitants in Tizi Ouzou province. [ABSTRACT FROM AUTHOR]

The urgency of the work is conditioned by the need to improvethe management methods of the operation modes of the power plant by creating software tools for predicting the performance of equipment when the conditions of its operation change. In this regard, the aim of the study is to carry out a detailed calculation research of such modes using uniquecomputational mathematical models based on the actual turbine power characteristics. Following tasks were set to achieve it: first, to calculate the limits of change for the main energy and economic indicators in real operating conditions on the example of the turbines T-50-130 of the Kirov CHP-4; secondly, to identify and describe the possible resources to increase the efficiency of the operation of the cogeneration turbine plants under conditions of variable heat and electric load schedules. The received results testifythat at today's prices for energy carriers, additional power generation by the thermal cycle of CHP plants is economically feasible during all day. The low economic efficiency of some common methods of generating peak power is shown, in particular, by changing the degree of opening the sliding grids in the low-pressure section. The proposed approach can be implemented and used to optimize the operation of CHP plants in the Russian wholesale electricity and capacity market. The results of the study make it possible to conclude that most steam turbine CHP plants have significant reserves for saving fuel and energy resources, which can be realizedby optimizing turbine operationmodes.

The combustion of biomass is a process that is increasingly used for the generation of heat and energy through different types of wood and agricultural waste. The emissions generated by the combustion of biomass include different kinds of macro- and micropollutants whose formation and concentration varies according to the physical and chemical characteristics of the biomass, the combustion conditions, the plants, and the operational parameters of the process. The aim of this work is to evaluate the effect of biomass moisture content on the formation of volatile organic compounds (VOCs) during the combustion process. Wet and dry poplar chips, with a moisture content of 43.30% and 15.00%, respectively, were used in a cogeneration plant based on a mobile grate furnace. Stack’s emissions were sampled through adsorbent tubes and subsequently analyzed by thermal desorption coupled with the GC/MS. The data obtained showed that, depending on the moisture content of the starting matrix, which inevitably influences the quality of combustion, there is significant variation in the production of VOCs.

The sugar yield achieved during pretreatment of lignocelluloses has an impact on the economic outcome of biorefineries. Chemical and physiochemical pretreatment methods were evaluated and compared to determine the most favorable pretreatment method for the commercial co‐production of succinic acid and electricity in a sugarcane lignocellulosic biorefinery. Nine methods were identified and simulated in Aspen Plus®. All the pretreatment methods were profitable except organosolv and wet oxidation. Steam explosion (STEX), sulfur dioxide (SO2), catalyzed STEX, and ammonia fibre expansion (AFEX™) resulted in the highest succinic acid yields, with 45.7, 43.5 and 33.4 kg succinic acid per 100 tonnes of dry feedstock, respectively, and they are recommended for commercial application. However, due to the high cost of enzymatic hydrolysis (46.23 million US$), the AFEX™ pretreatment method was the most expensive scenario at 385.7 million US$ total capital cost with an internal rate of return (IRR) of 22.81%. This may be compared with 384.2 million US$ for STEX pretreatment, which resulted in the most profitable biorefinery scenario with an IRR of 28.04%. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

This paper focuses on modeling the performance of a small-scale combined heat and power (CHP) plant fueled with corn stover pieces (CSP) as very potential biomass resource in Egypt. The developed power plant can be used to satisfy the heat and electricity needs. The proposed power plant performance is simulated using the professional Cycle-Tempo® software. The power plant is divided into three stages; the gasification unit (downdraft fixed bed gasifier and air supply system), gas cleaning and cooling units and the micro-turbine (MT) as an electrical generation unit. In the first stage, the CSP feedstock is converted to producer gas at atmospheric pressure with a reaction temperature about 1028.6 °C, using air as a gasifying agent. The efficiency of gasification process at a regulated air–biomass ratio of 1.5 kg/kg is 77.92% with calorific value (LHV) of 3.87 MJ/kg. Cleaning and cooling stage used to dispose the undesirable gas constitutes such as; tar, flying ash, and etc. The clean gas is passing through the MT as power generator for CHP applications with turbine inlet temperature of 850 °C. Ultimately, the simulation revealed that the CHP overall efficiency of this developed plant is 63.21% providing an electrical power of 94.81 kWel and thermal power of 187.55 kWth. [ABSTRACT FROM AUTHOR]

The paper considers the make-up water heating capability and conditions in the built-in tube bundles when cooling water is concurrently piped through the main turbine condenser bundles. Based on the analysis of experimental and calculated data, a technique is proposed for estimating heat fluxes entering the condenser when the turbine plant operates in the heat production mode. It is shown that, for efficient operation of the built-in bundle as part of the condensing system, all heat fluxes coming in addition to the wheelspace should be directed into the regenerative heating zone under the built-in condenser bundles through special water distribution devices, and the inlet zone itself should be separated from the condenser chamber by enclosing shields. The calculation studies were carried out using a mathematical condenser model of a cogeneration steam turbine plant with built-in condenser bundles. The studies were performed on the model of a turbine plant T-50-12.8 for three seal levels of the low-pressure sliding grid and different make-up water flows and temperatures. The conducted researches made it possible to determine the heat distribution in the condenser between the condenser bundles in different turbine operating modes and to reveal the absence of pressure constraints in the condenser and make-up water temperature constraints at the outlet of the built-in bundle. Based on the turbine plant T-50-12.8 mathematical model, thermal efficiency calculations were performed using the built-in make-up water condenser bundles when the main bundles operate in the cooling mode. It is shown that the heat economy of the turbine plant operating in the considered regimes in the heat production mode with the make-up water flows close to the nominal make up 70% and more of the condenser heat load. [ABSTRACT FROM AUTHOR]

The energy requirement pattern of world is growing up and developing technology. The available sources, while exhausting and not friendly to the environment, are highly used. Looking at partial supply and different options of environment problems associated with usage, renewable energy sources are getting attention. MSW (Municipal solid waste) composition data had been collected from 1997 to 2009, in Benghazi Libya, to evaluate the waste enthalpy. An incinerator with capacity of 47,250 kg/h was confirmed to burn all the quantity of waste generated by the city through the next 15 years. Initial study was performed to investigate energy flow and resource availability to insure sustainable MSW required by the incinerator to work at its maximum capacity during the designated period. The primary purpose of the paper is to discuss the design of Rankin steam cycle for the generation of both power (PG) and combined heat power (CHP). In the power generation case, the system was found to be able to generate electrical power of 13.1 MW. Including the combined heat power case, the results showed that the system was able to produce 6.8 million m3/year of desalinated water and generate 11.33 MW of electricity. In conclusion, the CHP designed system has the greatest potential to maximize energy saving, due to the optimal combination of heat production and electricity generation.

In this paper according to the calculation of chips productivity needs for gasification in the demo CHP plant for co-generation: electricity and heat, chippers were analyzed due to: the type of mobility, running for chipping and the method of delivering chips to temporary yard. The plant was planned to generate electricity power up to 200kWelec. First, in consideration were taken the chippers with medium capacity, which mainly served for chipping brushwood and leaves that remain after harvest plantations on mostly flat terrain and parks. Later, the comparative characteristics of the world's three largest manufacturers of machinery for the production of wood chips significantly larger amounts (up to 30m3/h) were given. These chippers were particularly suitable for the higher density of crops and stationed yard, in which brushwood would be brought and chip. At the end, the types of convective dryers were analyzed that could be successfully used for drying wood chips (drum and pneumatic dryer) and based on the calculation proposed the types of dryers that were available in the local market.

District heating networks are considered as convenient systems to supply heat to consumers while reducing CO2 emissions and increasing renewable energies use. However, to make them as profitable as possible, they have to be developed, operated and sized carefully. In order to cope with these objectives, simulation tools are required to analyze several configuration schemes and control methods. Indeed, the most common problems are heat losses, the electric pump consumption and the peak heat demand while ensuring the comfort of the users. In this contribution, a dynamic simulation model of all the components of the network is described. It is dedicated to assess some energetic, environmental and economic indicators. Finally, the methodology is used on an existing application test case namely the district heating network of the University of Liège to study the pump control and minimize the district heating network heat losses. [ABSTRACT FROM AUTHOR]

It was aimed to design a novel RVPSA (Rapid Vacuum Pressure Swing Adsorption) unit for CO 2 concentration and recovery in order to achieve the aggressive CO 2 capture target, i.e. 95+% CO 2 purity and 90+% CO 2 recovery at the same time, applied to an existing 10 MW th biomass-fuelled CHP plant. Biomass-fuelled CHP plants are deemed carbon-neutral on the grounds of the net CO 2 addition to the atmosphere as a result of its operation being practically zero, ignoring the CO 2 emissions involved in the ancillary processes, such as soil enhancement, biomass transport and processing, etc. Furthermore, integrating the biomass-fuelled CHP plant with carbon capture, transport and storage enables carbon-negative energy generation, as its net effect is to recover some CO 2 in the air and then store it underground through this plant operation. By the way, a RVPSA process features more efficient utilisation of the adsorbents in the column, leading to much higher bed productivity than a conventional adsorption process. Such a high bed productivity makes it easier to scale up this adsorption process for its application to industrial post-combustion capture. A two-stage, two-bed RVPSA unit was designed and simulated to capture CO 2 from the biomass-fuelled CHP plant flue gas containing 13.3% CO 2 mole fraction. Effects of operating conditions such as the Purge-to-Feed ratio (P/F) and desorption pressure on the specific power consumption were investigated in detail. It was found that the integrated two-stage RVPSA unit was capable of achieving the following overall performances: CO 2 recovery of 90.9%, CO 2 purity of 95.0%, bed productivity of 21.2 mol CO2 /kg/h and power consumption of 822.9 kJ/kg CO2 . The productivity of the RVPSA unit designed in this study was 20-30 times higher than those of the conventional CO 2 capture VPSA processes. [ABSTRACT FROM AUTHOR]

The development of heat metering has promoted the development of statistic models for the prediction of heat demand, due to the large amount of available data, or big data. Weather data have been commonly used as input in such statistic models. In order to understand the impacts of direct solar radiance and wind speed on the model performance comprehensively, a model based on Elman neural networks (ENN) was adopted, of which the results can help heat producers to optimize their production and thus mitigate costs. Compared with the measured heat demand, the introduction of wind speed and direct solar radiation has opposite impacts on the performance of ENN and the inclusion of wind speed can improve the prediction accuracy of ENN. However, ENN cannot benefit from the introduction of both wind speed and direct solar radiation simultaneously. [ABSTRACT FROM AUTHOR]

District heating networks are considered as convenient systems to supply heat to consumers while reducing CO 2 emissions and increasing renewable energies use. However, to make them as profitable as possible, they have to be developed, operated and sized carefully. In order to cope with these objectives, simulation tools are required to analyze several configuration schemes and control methods. Indeed, the most common problems are heat losses, the electric pump consumption and the peak heat demand while ensuring the comfort of the users. In this contribution, a dynamic simulation model of all the components of the network is described. It is dedicated to assess some energetic, environmental and economic indicators. Finally, the methodology is used on an existing application test case namely the district heating network of the University of Liège to study the pump control and minimize the district heating network heat losses.

The present paper describes an energy efficiency project (and relevant authorities proceedings) related to a 100 MWe CHP located within an industrial facility in Italy (COD 1996). The CHP plant supplies steam and electricity to the industrial process, whilst the extra electric-energy generation is sold to the grid. Main project target was to increase the global operating and economic indicators by: • Modifying the plant in order to cope with different thermal needs from the industrial process; Obtaining the incentives named TEE – Titoli di Efficienza Energetica , related to the CAR scheme; • Reducing CO 2 emissions (“Quote CO 2” ). • Increasing the CHP global efficiency; As several European CHP plants are nowadays facing operation/performance limitations due to different actual thermal loads (typically lower) compared to the design ones; the project has hence the aim to combine the need of a plant retrofit and the eligibility for the CAR incentives, providing a financial support to the retrofit, which corresponds, in project case, to a PBT of less than 2 years. The project and iterations with GSE are still ongoing. [ABSTRACT FROM AUTHOR]

Highlights: [•] We analyzed the potential for energy savings in district heated buildings. [•] Measures that reduce more peak load production give higher primary energy savings. [•] Efficient appliances increase heat demand but give net primary energy savings. [•] Efficient appliances give the largest net primary energy savings. [ABSTRACT FROM AUTHOR]

Highlights: [•] An integrated industrial site with sawmill, pellet plant and CHP plant is studied. [•] Different material and energy flow connections among the plants are explored. [•] Up to 18% of sawmill biomass output can be saved. [•] Heat and biomass prices strongly affect the economic result. [Copyright &y& Elsevier]

Production of electricity and heat in cogeneration in high power efficiency conditions strictly depends on Combined Heat and Power (CHP) plant's basic equipment availability. Related to this, a study on forecast reliability of determinant subsystems, in producing combined heat and power, meaning - steam boilers, steam turbines and electric generators, was made. The study that concluded with the presented results has been made in CHP plant Oradea considering a few, presumable operating schemes, three for summer and two for winter period. For each of these five variants, Reliability Block Diagram (RBD) has been prepared, then there were determined the reliability and availability of each subsystem considering their maintainability and different time periods assigned for corrective maintenance. [ABSTRACT FROM AUTHOR]

Abstract: Generation of near CO2 free energy (electricity and heat) in existing large co-generation technologies can be achieved by partial substitution of fossil fuels with biomass commonly regarded as CO2-neutral fuel. Co-firing of biomass with fossil fuels aims at reduction of greenhouse gases (GHG) emissions and non-renewable fuel resources depletion. Life cycle analysis was carried out for hard coal and two biomass sorts of different origin (willow chips and residual wood chips) requiring a diverse approach for their upstream inventory of non-renewable energy resources depletion and GHG emission. These fuels are co-combusted in a combined heat and power plant (CHP plant) for generation of electricity and heat. As in the case of cogeneration process, it was necessary to allocate the harmful effects between both energy carriers. Allocation of the burdens basing on the principle of the avoided process has been proposed. The empirical correlations concerning the electricity consumption of boiler auxiliaries'' and boiler energy efficiency along with the increasing share of biomass in the fuel blend were applied in the calculations. The functional unit chosen to compare the results was 1 TJ of heat. Sensitivity analysis was carried out to bring the final conclusions and recommendations. Both environmental burdens (non-renewable resources depletion and the greenhouse effect) are dependant on the share of biomass in the combusted blend. It was proved, that the partial substitution of coal with biomass (in the considered range of 0–20% on the thermal basis) leads to the decrease of the total life-cycle non-renewable energy resources depletion and cumulative GHG emissions for generation and supply of 1 MJ of heat (functional unit) and 1 MWh of electricity generated during multifunctional process of combined heat and power generation. Residual biomass shows its advantages over dedicated energy crops (on the example of willow biomass). Additionally, it has been proved, that the share of operational component dominates in the total system burdens concerning the regarded life cycle. [Copyright &y& Elsevier]

Abstract: This paper studies allocation of fuel costs and CO2-emissions to heat and power in a CHP plant producing heat to an integrated pulp and paper mill and electricity to the liberalized electricity markets (or to the mill by the market price). The CHP plant and the mill are considered to be two separate economical units and both the mill and the CHP plant perspectives are discussed. Fuel costs and CO2-emissions are allocated using the energy, exergy and market based methods. The CHP plant purchases black liquor and bark from the mill. It also purchases oil from the markets to cover the whole fuel demand of the plant. The results indicate that the marked based method can be recommended as a “neutral” cost allocation method, because with that, the energy producer is not collecting extra margins from selling steam. This means that heat pricing is cost based. The results also indicate that depending on the emission factor and efficiency of alternative energy production form, the marked based method or the exergy method allocate the lowest CO2-emissions to heat. Therefore, the use of market based method for allocating costs and CO2 emissions can be recommended in order to use one single approach in both. [Copyright &y& Elsevier]

Abstract: In this study, we analyze the impact of ventilation heat recovery (VHR) on the operation primary energy use in residential buildings. We calculate the operation primary energy use of a case-study apartment building built to conventional and passive house standard, both with and without VHR, and using different end-use heating systems including electric resistance heating, bedrock heat pump and district heating based on combined heat and power (CHP) production. VHR increases the electrical energy used for ventilation and reduces the heat energy used for space heating. Significantly greater primary energy savings is achieved when VHR is used in resistance heated buildings than in district heated buildings. For district heated buildings the primary energy savings are small. VHR systems can give substantial final energy reduction, but the primary energy benefit depends strongly on the type of heat supply system, and also on the amount of electricity used for VHR and the airtightness of buildings. This study shows the importance of considering the interactions between heat supply systems and VHR systems to reduce primary energy use in buildings. [Copyright &y& Elsevier]

Abstract: In this study we explore the effects of end-use energy efficiency measures on different district heat production systems with combined heat and power (CHP) plants for base load production and heat-only boilers for peak and medium load productions. We model four minimum cost district heat production systems based on four environmental taxation scenarios, plus a reference district heat system used in Östersund, Sweden. We analyze the primary energy use and the cost of district heat production for each system. We then analyze the primary energy implications of end-use energy efficiency measures applied to a case-study apartment building, taking into account the reduced district heat demand, reduced cogenerated electricity and increased electricity use due to ventilation heat recovery. We find that district heat production cost in optimally-designed production systems is not sensitive to environmental taxation. The primary energy savings of end-use energy efficiency measures depend on the characteristics of the district heat production system and the type of end-use energy efficiency measures. Energy efficiency measures that reduce more of peak load than base load production give higher primary energy savings, because the primary energy efficiency is higher for CHP plants than for boilers. This study shows the importance of analyzing both the demand and supply sides as well as their interaction in order to minimize the primary energy use of district heated buildings. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents the possibility of integration of the Corex process, blast furnace, CO2 removal installation and metallurgical combined heat and power (CHP) plant. Such an integration has significant advantages from the technical and environmental points of view. As the Corex export gas (after CO2 removal) is a highly valuable reducing agent, it is proposed to use it as a reducing gas injected to the thermal reserve zone of the blast-furnace process. Such an application leads first of all to a saving of coke. Besides the reduction of the consumption of coke, also the consumption of blast, high-purity oxygen, the amount and lower heating value (LHV) of blast-furnace gas as well as many other parameters are changed. CO2 separation is realized by physical absorption, which has been chosen and analysed as the most appropriate technology in similar applications. Higher LHV of the Corex gas obtained by CO2 removal provides the possibility of its utilization in the gas-and-steam CHP plant. Such a possibility has been also tested by means of energy and economical analyses. [Copyright &y& Elsevier]

Abstract: To meet utility demands some industrial units use onsite utility system. Traditionally, the management of such type of industrial units is carried out in three sequential steps: scheduling of the manufacturing unit by minimizing inventory, estimating the utility needs of manufacturing unit and finally operation planning of the utility system. This article demonstrates the value of an integrated approach which couples the scheduling of manufacturing unit with operational planning of the utility system. A discrete-time mixed integer linear programming (MILP) model is developed to compare traditional and integrated approaches. Results indicate that the integrated approach leads to significant reduction in energy costs and at the same time decreases the emissions of harmful gases. [Copyright &y& Elsevier]

The combustion of biomass is a process that is increasingly used for the generation of heat and energy through different types of wood and agricultural waste. The emissions generated by the combustion of biomass include different kinds of macro- and micropollutants whose formation and concentration varies according to the physical and chemical characteristics of the biomass, the combustion conditions, the plants, and the operational parameters of the process. The aim of this work is to evaluate the effect of biomass moisture content on the formation of volatile organic compounds (VOCs) during the combustion process. Wet and dry poplar chips, with a moisture content of 43.30% and 15.00%, respectively, were used in a cogeneration plant based on a mobile grate furnace. Stack's emissions were sampled through adsorbent tubes and subsequently analyzed by thermal desorption coupled with the GC/MS. The data obtained showed that, depending on the moisture content of the starting matrix, which inevitably influences the quality of combustion, there is significant variation in the production of VOCs. [ABSTRACT FROM AUTHOR]

The paper investigates cases of separate and combined heat and power generation, providing data for comparison of their energy efficiency. It was shown that the official translation of the Directive of the European Parliament and of the Council 2004/8/EC from February 11, 2004 into the Lithuanian language has used the incorrect concept of "thermofication" instead of "cogeneration". The paper shows various possibilities for the use of cogeneration technologies presented in Annex I of the Directive, on the "power capacity vs. electric efficiency" axes. The paper provides data on companies producing microturbines and discusses possibilities to use microturbines in various fields of economic activity. [ABSTRACT FROM AUTHOR]