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The paper drying process has the highest level of energy consumption in the pulp and paper production process. Analysis and optimization of the energy system during the paper drying process is critical for improving the energy efficiency of the entire paper mill. In the existing model for the paper drying process, the solution requires accurate boundary conditions such as the air temperature and humidity of the pocket area and the cylinder surface temperature, which are very difficult to obtain in the papermaking process. This can result in significant deviations between the model solution and the actual production process. This paper focuses on the single-tier dryer cylinder-based paper drying process that has been widely used with high-speed papermaking machines in recent years. A mathematical model is proposed based on real-time data. The verification via industrial production demonstrates that the proposed model is reliable for the paper drying process. Based on the simulation results, two optimization operations have been proposed. The energy consumption decreases from 1.51 t steam/t paper to 1.44 t steam/t paper, 4.6% of the steam and 1.26 × 106 RMB can be saved for a medium-scale paper mill with the annual production capacity of 105 t paper.

The Swedish pulp and paper industry (PPI) must increase energy efficiency to remain competitive on the global market, which has experienced entries from countries with cheaper energy and raw material supplies. Interactions among variables for energy use, production, energy management, electricity price and firm characteristics (FC), in different types of mills, i.e., pulp, paper and integrated mills, in Sweden from 2006 to 2015 indicate that correlations among the studied variables were different in different types of mills. This difference between types of mills seemed to originate partly from varying accessibility to production residue that could be used for energy. For all types of mills, variation of electricity prices did not correlate significantly with energy efficiency during the study period. The studied FC were firm's age, number of employees, number of companies in company group, net sales and profit for the year. Energy efficiency was more affected by the variables characterizing energy and production compared to the variables representing FC. This study also suggested presence of possible discrepancies between FC that were perceived as barriers to energy management towards energy efficiency, according to previous studies, and what was shown by the data combining variables representing energy use, production and FC.

In this paper an original and exhaustive mathematical modelling of air impingement drying systems for the production of tissue paper in the Yankee-hoods configurations is reported, which offers the possibility to optimize its energy performance. The model takes into account many detailed operative parameters of the overall drying process with the aim to execute its energy and mass balance and to evaluate its energy performances. The validity of the mathematical model has been assessed by comparison with actual data from an existing tissue paper mill. Finally, the energy performances of two different layouts of the air system have been evaluated and compared. Changing the operative parameters of the drying process, such as air jet temperature and speed and moisture content of the extraction air, it is possible to obtain the same paper production with an energy saving of about 4.5%. In average, the layout with two parallel air circuits assure an energy saving of about 1% with respect to the layout with a single air circuit.

In order to explore hydrothermal carbonization (HTC) behavior of municipal solid wastes (MSW), four typical components, waste textile, wood, paper and food, were employed to perform HTC and co-HTC process. The experiments were conducted at 240 ○C and 90 min with a 1:12 solid/liquid ratio, where blending ratios of 1:3, 1:1 and 3:1 with waste textile were investigated. As expected, the increase of fixed carbon and carbon content improved the fuel potential of hydrochar. The synergistic index (SI) analysis clearly indicated that significant synergistic effects occurred during co-HTC process. Specifically, all the SI values of hydrochar yield from co-HTC of waste textile with wood and paper were negative, while all SI values of hydrochar yield for waste textile with food were positive. Particularly, the SI values of fuel ratio for all hydrochars were positive which suggested co-HTC could promote to enhance the coalification degree of hydrochars. However, the undesirable increment of O content for hydrochars (derived from 75%waste textile-25% waste food and 50%waste textile-50% waste food) decreased the high heating value. The combustion behavior and nth-order kinetic model analysis showed that hydrochars derived from co-HTC rendered a more stable and lasting combustion profile.

The waste biomass has immense opportunities and plenty of potentials to be an efficient source of renewable energy. Initially, native unripe coconut husk (NCH) was used as raw material for fluidized bed gasification. Then NCH was treated with paper and pulp waste water to impregnate metals present in it for getting enhanced H2 yield in fuel gas. Humidified air was used as gasifying medium, which served the purpose of introducing water vapour to take part in the gasification process. Then after, gasification medium was retrofitted with CO2, which enhanced both the higher heating value (HHV), and CO and H2 content in the fuel gas. This research serves the dual benefit of energy generation and waste minimization. HHV of unripe coconut husk was investigated and found to be 20.95 MJ/kg. H2 yield and HHV from impregnated coconut husk (ICH) were obtained as 55.55 vol % and 5.24 MJ/Nm3, respectively at HER 0.1 and gasification temperature of 850 °C in case of fluidized bed gasification. The GC-MS analysis of fuel oil obtained from ICH gasification was done to get the information about high yield of fuel gas as promise product of fluidized bed gasification.

Production of transportation fuels from biorefineries via biomass gasification has been suggested as a way of introducing renewable alternatives in the transportation system with an aim to reduce greenhouse gas emissions to the atmosphere. By co-locating gasification-based processes within heat demanding industries, excess heat from the gasification process can replace fossil or renewable fuels. The objective of this study was to compare the heat integration potential of four different gasification-based biorefinery concepts with a chemical pulp and paper mill. The results showed that the choice of end product which was either methanol, Fischer-Tropsch crude, synthetic natural gas or electricity, can have significant impact on the heat integration potential with a pulp and paper mill and that the heat saving measures implemented in the mill in connection to integration of a gasification process can increase the biomass resource efficiency by up to 3%-points. Heat saving measures can reduce the necessary biomass input to the biorefinery by 50% if the sizing constraint is to replace the bark boiler with excess heat from the biorefinery. A large integrated gasification process with excess steam utilisation in a condensing turbine was beneficial only if grid electricity is produced at below 30% electrical efficiency.

This paper presents a comparison between four gasification-based biorefineries integrated with a pulp and paper mill. It is a continuation of 'Transportation fuel production from gasified biomass integrated with a pulp and paper mill - Part A: Heat integration and system performance'. Synthesis into methanol, Fischer-Tropsch crude or synthetic natural gas, or electricity generation in a gas turbine combined cycle, were evaluated. The concepts were assessed in terms of GHG (greenhouse gas) emissions and economic performance. Net annual profits were positive for all biofuel cases for an annuity factor of 0.1 in the year 2030; however, the results are sensitive to biofuel selling prices and CO2,eq charge. Additionally, GHG emissions from grid electricity are highly influential on the results since all biofuel processes require external power. Credits for stored CO2 might be necessary for processes to be competitive, i.e. storage of separated CO2 from the syngas conditioning has an important role to play. Without CO2 storage, the gas turbine case is better than, or equal to, biofuels regarding GHG emissions. Efficiency measures at the host mill prior to heat integration of a gasification process are beneficial from the perspective of GHG emissions, while having a negative impact on the economy.

Paper mill sludge (PMS) can be efficiently utilized to produce fuels and chemicals. However, wastewater is usually generated during the de-ashing step of the PMS for fibrous materials recovery. Per process requirements, the wastewater stream must be treated which results in an increase in the overall process production cost. Therefore, this research aims at reusing the wastewater produced during the de-ashing step as a substitute for freshwater addition during the conversion of PMS into ethanol. The advantages of this approach include reducing the amount of wastewater produced and enhancing the overall efficiency of the process. It will contribute to the circular economy of zero waste discharges. The results showed that 30% of the process wastewater can be recycled without affecting the enzymatic hydrolysis and ethanol fermentation. Hence, the amount of wastewater that needs to be treated is reduced by 30% resulting in a cost reduction of 22.5%. The results also showed that wastewater recycling minimized the energy demands in the distillation and evaporation units by 1206 kJ/kg. The energy reduction is due to the increase of metals and total soluble solids in the broth stream after fermentation. This process configuration enhanced the process economy, saved energy and managed waste streams.

In this study, through orthogonal experiments design, the influences of ultrasonic pretreatment (frequency, power and treatment time) on co-pyrolysis and catalytic pyrolysis of municipal solid waste and paper mill sludge were explored. The differential thermogravimetry curves became steeper and the peak values were larger after pretreatment, which made the pyrolysis reaction rapidly and the volatile separated out timely. However, the change of pyrolysis characteristics was not obvious after adding MgO. The catalytic effect of MgO increased with the increase of sludge ratio. After pretreatment, the average activation energy of the samples had an overall increasing trend, but the change was small. MgO had a decreasing effect on activation energy, and with the increasing proportion of sludge the degree of reduction became significant. In addition, high ultrasonic frequency had a negative effect on reducing activation energy.

The generated gas bubbles in microfluidic fuel cells (MFCs) cover the active surface area of the electrode and greatly limit the cell performance. In this study, a feasible approach is proposed to effectively accelerate bubbles removal and enhance cell performance by embedding a paper separator in the middle of the microchannel. Visualization of bubble behaviors and the corresponding electrochemical measurements are performed to investigate the effect of bubbles on the cell performance. Periodical process of the bubble growth and removal leads to the fluctuation in the current density of the MFC. The rapid gas removal and the low ohmic resistance are observed after embedding a layer of filter paper in the microchannel, causing improved fuel transfer and smaller ohmic loss. Although the current density fluctuates more frequently, the fluctuation amplitude decreases and the cell performance is enhanced. Compared with the MFC without paper separator, the maximum power density and the limiting current density of the MFC with paper separator is increased by 25.2% and 130%, respectively. Moreover, the cell performance is improved with increasing the flow rate of reactant solution and the peak power density achieves 25.9 mW cm−2 under flow rate of 1500 μL min−1.

This study investigates heat integrated production of FT (Fischer-Tropsch) crude, where excess heat from the FT crude plant is delivered to a typical Scandinavian pulp and paper mill that produces fine paper. The sizes of FT crude plants are quantified, when the amount of excess heat from the FT plant exactly matches the heating demand otherwise satisfied by the bark boiler at the mill, considering a number of development pathways at the mill, including various degrees of steam savings and biorefinery options, such as lignin extraction. Performance of integrated production is compared with that of an FT stand-alone plant on the basis of wood fuel-to-FT crude efficiency, GHG (greenhouse gas) emissions balances and FT crude production cost. The results show that there exists a heat integration opportunity for an FT crude plant ranging from 0 up to 350 MW (LHV) of wood fuel depending on the development pathway for the mill. The results indicate higher overall efficiency and a generally lower production cost for the heat integrated, co-located production. Heat integrated production has a larger potential to contribute to GHG emission mitigation, assuming a future generation of grid electricity emitting equal to or less than an NGCC (natural gas combined cycle) power plant. © 2013 Elsevier Ltd. All rights reserved.

In this study, a pulp and paper mill (PPM) in the SEKA Papermaking Plant in Izmit, Turkey, is analysed through energy and exergy balances. The plant utilises recycled waste paper for papermaking. This type of raw material input makes the process highly sophisticated. The pulping uses strictly mechanical processes, such as digestion, separation by screening and hydrocyclone, and refining. The milling, as an integrated process, provides the final operations necessary to prepare the conditions required for the end-product by stock-preparation, wiring, rolling, and drying by dewatering, pressing, and evaporation. The possibility of making the entire process more thermodynamically efficient is discussed by calculating the energy and exergy losses for all the mechanical and physical sub-processes. The study shows that the energy efficiencies for each of the mechanical and physical steps in the PPM vary between 34% and 97.4%, whereas the exergy efficiencies vary between 30.2% and 94.2%. In conclusion, based on the results from the energy and exergy flow analyses, the exergy output can be improved through more efforts directed primarily to further measurements toward more efficient energy utilisation in the PPM.

The Scandinavian mechanical pulp and paper industry has been facing great challenges during the past decades, mainly because of declining demand for newsprint, and higher prices on raw material and energy. One way of increasing profitability is to produce more value-added products besides the production of pulp and paper. In this study, integration potentials of three possible future biomass gasification-based energy mills with an existing thermo-mechanical pulp (TMP) mill, co-located with a sawmill, have been evaluated. The product gas was utilized for electricity production in a gas turbine, for production of methanol or for production of Fischer–Tropsch (FT) liquids. Integration of the energy mills showed good potential as the TMP mill constitutes a heat sink for which the excess heat from the energy mills can be utilized all year round. However, since there is little excess heat from the TMP mill at the required level to be utilized for biomass drying, for example, heat integration is typically one way. It has also been shown that integration of biomass gasification with a TMP mill results in larger CO2 emissions reduction than stand-alone operation. Still, compared to co-firing biomass in a coal power plant, the energy mills all have lower potentials for CO2 emissions reduction.

Long term annual electricity consumption forecasting is very important for country's energy planning. These forecasts are influenced by several factors (political, technological, social, environmental and economic), and brings with itself a high uncertainty degree in its results and difficulties in the evaluation of such factors over them. A methodology that eases to take into account these factors aiming improve the results and help understanding the electricity consumption annual trajectory till the forecast horizon is, therefore, very much useful and desired. So, we propose a modelling structure using the bottom-up approach to cope with these matters and to evaluate the trajectory of long term annual electricity consumption of a sector of the Brazilian industry up to 2050 considering energy efficiency (EE) scenarios. It is important to emphasize that Brazil is a developing country, and to build a bottom-up approach was a challenge, mainly due to the fact that this model is data intensive. In particular, this modelling was applied in the pulp and paper sector. The main goal was to consider technological diffusion scenarios in EE measures, and show the energy savings achieved. The results point an energy savings in the order of 25% when an actual scenario is considered.

This work analyzed the energy flow of the pulp and paper industry in Taiwan. The potential technology options that were examined focus on how to capture some of the energy currently lost in the processes and then identifying the areas with energy-saving potential that could also have large impacts across a variety of industries. In addition, the energy-saving potential of these options was evaluated. The energy-saving potential of the pulp and paper industry would be around 6939.9 KLOE/M. The greatest energy-saving potential lies with improving energy distribution and equipment efficiency, which would together potentially comprise 86.8% of total energy conservation. This analysis can serve as a benchmark for current pulp and paper making operations, and as a base case for stimulating changes toward more efficient energy utilization in the pulp and paper industry.

In this paper an approach for analysing the potential for implementation of different technology pathways for the European pulp and paper industry (PPI) is presented. The approach is based on detailed technical research and aggregates the knowledge from previous studies to incorporate the whole European PPI. Thus, the potential for different technology pathways can be estimated on a European level whilst still considering important characteristics of individual mills. The usefulness of the approach was exemplified by applying it to a case study of the potential for introduction of carbon capture and storage (CCS) within the European PPI. The results from the case study show that for the European PM, CCS has an up-hill road in order to be a viable, large scale alternative for reduction of CO2 emissions. If CCS is to be introduced in large scale within the European PPI, large biomass-based point sources of CO2 emissions need to be included when planning for CCS infrastructure and also the infrastructure needs to be built out for clusters emitting

This paper evaluates system aspects of biorefineries based on biomass gasification integrated with pulp and paper production. As a case the Billerud Karlsborg mill is used. Two biomass gasification concepts are considered: BIGDME (biomass integrated gasification dimethyl ether production) and BIGCC (biomass integrated gasification combined cycle). The systems analysis is made with respect to economic performance, global CO2 emissions and primary energy use. As reference cases. BIGDME and BIGCC integrated with district heating are considered. Biomass gasification is shown to be potentially profitable for the mill. The results are highly dependent on assumed energy market parameters, particularly policy support. With strong policies promoting biofuels or renewable electricity, the calculated opportunity to invest in a gasification-based biorefinery exceeds investment cost estimates from the literature. When integrated with district heating the BIGDME case performs better than the BIGCC case, which shows high sensitivity to heat price and annual operating time. The BIGCC cases show potential to contribute to decreased global CO2 emissions and energy use, which the BIGDME cases do not, mainly due to high biomass demand. As biomass is a limited resource, increased biomass use due to investments in gasification plants will lead to increased use of fossil fuels elsewhere in the system. Original Publication:Elisabeth Wetterlund, Karin Pettersson and Simon Harvey, Systems analysis of integrating biomass gasification with pulp and paper production - Effects on economic performance, CO2 emissions and energy use, 2011, ENERGY, (36), 2, 932-941.http://dx.doi.org/10.1016/j.energy.2010.12.017Copyright: Elsevier Science B.V., Amsterdam.http://www.elsevier.com/

In hot and dry climatic zones, direct evaporative cooling (DEC) system is used as an economical and efficient alternative to traditional air conditioning systems. The present paper concerns comprehensive experimental investigations and analysis of heat and mass transfer characteristics and thermal performance parameters of a bee-hive construction of corrugated-cellulose papers as a new cooling pad material. The performance parameters used to evaluate the effectiveness of the cooling pad materials are the outlet air temperature and relative humidity, pressure drop, humidifier effectiveness, rate of the evaporated water, sensible cooling capacity, specific cooling capacity (SCC), coefficient of performance (COP), specific water consumption (SWC), and Nusselt and Sherwood numbers. The cooling pad performance was investigated for a wide range of air and water temperatures and flow rates and pad thicknesses. The results show the enhancements of heat and mass transfer coefficients and the performance parameters with rising air temperature and water flow rate to humidifier. High values of the performance parameters (hc = 45 W/m2 oC and hm = 0.23 m/s, e h u m = 0.85 and COP = 170) are obtained compared to the traditional pad materials. Experimental correlations for the evaporative cooler performance parameters in terms of air and water temperatures and flow rates pad thicknesses are presented.

The success of any process improvement study depends on the quality of the available data and the way in which the plant-specific characteristics are incorporated in the applied conceptual models; in the context of process integration studies these issues are directly related to the rules followed during the data extraction stage. Improving energy efficiency in a pulp and paper Kraft mill requires the identification of the most promising heat recovery network retrofit projects. In a retrofit analysis using pinch technology/process integration methods, only the process streams associated to the existing heat exchangers and some outlet streams (such as wastewater/effluent streams and vents) with high potential for heat recovery are usually included, while the energy exchanged through non-isothermal stream mixing (NIM) or direct heat transfer (DHT) is often assumed fixed and is not considered in the analysis. Relaxing this assumption requires extracting more data to represent the DHT design configuration that exists in the plant. However, different data extraction options can be considered to represent the DHT configuration depending on the associated process/operation constraints. This work describes a systematic procedure to extract and analyse the impacts of DHT on the overall energy efficiency of a Kraft process with a specific focus on mixing along the pulp line and in water tanks.

Implementation of absorption heat pumps (AHPs) in a Kraft pulping process was studied using a new methodology for the optimal integration of those devices in a process. Two generic opportunities were identified for an energy and water optimized mill: (i) integration of a double lift chiller in the bleaching chemical making plant to produce chilled and hot water simultaneously, using MP steam as the driving energy and, (ii) installation of a single stage heat pump to concentrate the black liquor and produce useful hot water by upgrading heat from the bleaching effluent and using MP steam as driving energy. The principles of AHPs operation and their efficient integration into a process are described. The simple payback time (SPB) and net present value (NPV) were used to evaluate the interest of such implementations. Considering 63 $/MWh for the steam price, SPB of 2.7 and 1.7 years have been estimated for the two cases.

Power generation by variable renewable energy (VRE) is expected to expand for decarbonization, although it is difficult to ensure stabilization of the energy demand due to fluctuations in the power output from VRE. To accelerate VRE implementation, wind-powered thermal energy systems (WTth-ES), which can provide dispatchable power using wind–thermal energy converter (WECth) and thermal energy storage (TES), have been proposed. In this study, we are tackling the installation of VRE, i.e., wind energy, by TES with WECth compared with wind turbine (WTp) in paper mills to demonstrate the applicability of TES in an industrial sector. Conventional and alternative energy systems in paper mills with TES were mathematically modeled and simulated to analyze the transmittable power output and the greenhouse gas (GHG) emissions by life cycle assessment. With the installation of TES and wind energy, transmittable power could be increased with GHG emissions reduction. However, their excess installation or unbalanced combination resulted in an increase in GHG emissions and a decrease in transmittable power. By comparing the cases, the combination of paper mill, TES, and WECth could convert thermal energy efficiently and mitigate fossil fuel consumption for multiple production of paper and power from the paper mill.

The P&P (pulp and paper) industry in Taiwan is highly energy intensive and there is much product diversification. Taiwan has extremely limited coal and petroleum resources and imports 98% of its energy supply. Increased energy utilization efficiency to reduce energy consumption is necessary for industry in order to implement energy audit recommendations. This work summarizes the energy-saving potential of 118 firms from 2009 to 2013 as determined by on-site energy audits, as well as the energy savings implemented in 2011 by 72 firms in Taiwan's P&P industry, according to data from the on-line Energy Declaration System. It is found that the total of the energy-saving potential and the implemented energy savings are 168.3 and 762.1 TJ, respectively. The results of this study can serve as a reference for current P&P operations and as a base case for stimulating changes in energy utilization.

This paper deals with energy end-use models for pulp, paper, and paperboard mills. The models are consistent with data published in the U.S. Department of Energy's 1991 Manufacturing Energy Consumption Survey (MECS). A graphical framework for depicting these energy flows is presented. Development of these models is a key step in creating energy process-step models for pulp, paper, and paperboard production. The applicability of the modeling approach and framework to other industries is discussed.

The MIND method is used to optimize the operating costs of a pulp and paper mill. The optimization includes studies of the effects of material and energy flows, as well as non-linear relations between them. The results show that it is possible to achieve large savings in the pulp and paper mill simply by changing the operating strategy of the existing equipment units. It is also apparent that the percentage of recycled fibres strongly influences possible savings.

Large kraft paper industries could economically generate 40% more electricity than the present demand by using steam-turbine cogeneration technology. A computer-based model has been used for the economic analysis. A systems approach, referred to as rational-use-of-energy, is proposed to overcome barriers to cogeneration.

Energy conservation is a central concern of the current industrial world, where increasing efficient energy usage is the only way of reducing a high energy demand. In the present study the optimization of a pulp and paper mill with a cogeneration plant has been carried out. The optimization was realized with a methodology which includes exergy, exergoeconomics, thermoeconomics and pinch analysis. The proposed methodology was useful in determining not only the best plant operating conditions but also establishing the components or subsystems with the highest irreversibilities. As a result of the study, operation changes in the recovery boiler, the turbogenerator, the thermal treatment and the deaerator were realized. Due to the higher irreversibility in the actual evaporator line, a new line of evaporators was proposed. Also, an innovative heat recycling technology as to the use of heat transformers was proposed in order to reduce waste heat discharged to the atmosphere. The results obtained with the proposed methodology, which integrates the different optimization methods, allowed reaching higher efficiencies and lower operational costs than those obtained with the optimization methods working separately.

The paper presents the improvement of energy management in a steam system used for corrugated board production. The system consists of a steam boiler (fired with natural gas), steam and condensate pipelines and a corrugated board production installation (steam consumer). In the existing system, the boiler works in unison with an open condensate tank. This tank is responsible for energy losses due to secondary steaming. Therefore, a system of a closed tank has been proposed to eliminate these energy losses. The coefficients of thermal performance and the energy losses in both cases (open and closed tank) are compared. The study shows that the losses of the closed steam system are always lower than those of the open system. The coefficient of performance could be increased by about 8% by the proposed modernization. The recovery of expenses for modernization should be very quick, taking place within a year.

Since the first oil crisis in the seventies, potentials for energy-efficiency improvements in the short and medium term have been studied extensively. Numerous analyses have indicated that energy-efficiency improvements of about 30–50% are technically feasible in industrialized countries over a period of one to two decades [ETSU, 1984; Maier, 1986; Lovins and Lovins, 1991; Beer et al., 1994].

The aim of this paper is to develop a novel method for the retrofit of Heat Exchanger Networks based on Bridge Retrofit analysis. The method identifies Retrofit Bridges that correspond to energy saving modifications using two new proposed tools: The Heat Surplus-Deficit Table and the Modified Energy Transfer Diagram. These tools both allow the identification and quantification of Retrofit Bridges. These tools have been developed following conventional Pinch Analysis tools such as the Composite Curve and Grand Composite Curve. The connection between the conventional Heat Exchanger Network synthesis tools and the proposed retrofit tools is established to improve understanding of the method and relate it to what is currently used in both literature and industry. The method is demonstrated with a simple illustrative example and a more detail paper mill case study. The paper mill incorporates a paper machine and paper recycling plant and is co-located with a Kraft pulp mill in New Zealand. Results from the retrofit method suggest a retrofit design that will achieve an annualised profit of NZD 570,000/y (USD 414,000/y) with a payback of 2.4 y.

This paper presents a comprehensive approach for improved efficiency of a once-through Benson type coal boiler in a coal-fired power plant. In the method, petrographic properties, ultimate analysis and proximate analysis of coal feedstock is firstly determined. In addition, operational parameters, like O2 concentration, coal mass flow, air/fuel ratio and load were varied to establish their impact on both SO2 concentration and NOx reduction. The coal samples are led by inertinite in the range of 34.4 – 47.8 vol% afterward total vitrinite content in the range of 20.3 – 24.4 vol%. Liptinite content occurs in minor proportions of 1.8 – 4.3 vol% range. The optimum conditions for simultaneous reduction of NOx emission and SOx are achieved when the O2 concentration is 3.58% and coal mass flow of 288 tonnes/hr. Reducing coal mass flow from 331 to 288 Tonnes/hr caused high SO2 concentration to reduce from 3862 mg/Nm3 to 2232 mg/Nm3. Moreover, NOx concentration reduced from 350 mg/Nm3 to 310 mg/Nm3 when the air/fuel ratio varied from the lean side to the rich side. The optimum air/fuel ratio of 7.24 resulted in NOx reduction. The highest boiler efficiency of 90.97% was achieved at full load and the O2 concentration of 3.58%.

The practice of injecting a coal/biomass blend can alleviate the pressure on carbon emissions and energy of ironmaking blast furnaces (BFs). In this paper, corn stalks treated by hydrothermal carbonization (HTC) are used as raw materials to eliminate the harm of alkali metals in the ash. The overall performance of individual behavior of the hydrochar, coal, and their blends are analyzed over the raceway with special reference to gas flow, temperature, species, and combustion efficiency. The results show that the hydrochar with higher volatile content is faster to devolatilize, showing a higher CO2 content at the nozzle tip, and reaching a higher burnout in the raceway. The addition of hydrochar to coal can improve the overall flow and combustion performance of the blends. The simulated value is higher than the calculated value, indicating the synergistic effect has existed. When the proportion of the hydrochar is 75% in blends, the synergistic effect is most obvious. The model provides an effective tool for the design of coal/biomass blends.

This paper investigates the performance and emission analyses of a turbo-charged diesel engine fuelled with pre-mixed and post-mixed hybrid biodiesel blends at varying load condition thereby maintaining injection timing, injection pressure and speed constant at 230bTDC, 220 bar and 1500 RPM. The experimental result depicted that post-mixed biodiesel blends (POBD 20) showed higher brake specific energy consumption and exhaust gas temperature by 4.6% and 2.02% than that of diesel while brake thermal efficiency was reduced by 5.68%. However, engine overall performance of post-mixed biodiesel blends (POBD 20) was found to be comparable with diesel and other prepared test fuel blends. Similarly, comparing exhaust emissions, oxides of nitrogen and carbon dioxide were on its higher side by 2.64% and 2.43% than normal diesel fuel. On the contrary, carbon monoxide, hydrocarbon and smoke opacity for POBD 20 were found to be 36.87%, 51.5% and 23.2% lower than conventional diesel fuel. From the above study, it is finally concluded that POBD 20 blend may be used as an alternative optional fuel that can substitute present diesel fuel without much engine modification and exhaust related problems.

The co-gasification of coal and dried sewage sludge (DSS) was conducted using a two-stage gasifier consisting of a fluidized bed gasifier and a tar-cracking reactor. In this study, the effect of the blending ratio of coal and DSS was investigated. Producer gases that were obtained from the tar-cracking reactor filled with active carbon contained high levels of hydrogen (maximum H2: 27.7 vol%) and low tar contents (minimum tar: 0 mg/Nm3). Upon gasification of the coal/DSS blends, the hydrogen content decreased and tar content increased with increasing DSS. Blends with coal/DSS ratios of 70/30 and 50/50 showed a synergetic effect on tar reduction, which could be attributed to the high ash content of the DSS. The gasification of the 70% DSS blend increased the condensed tar yield by only 0.1 wt%, compared to coal gasification. Lastly, a hot filter filled with Fe-impregnated active carbon was applied to completely remove tar from producer gas, which led to the production of a tar-free and hydrogen-rich gas (30 vol%). Furthermore, the Fe-impregnated active carbon reduced the H2S content to 229 ppmv. In summary, it was possible to produce a clean gas from coal and DSS blends in the UOS gasification process.

The energy consumption of an ammonia process plays an important role in the industrial energy consumption. For an ammonia synthesis process using pure oxygen gasification, the energy consumption of cryogenic air separation occupies a large proportion. The purity of the oxygen product from the air separation unit is mostly 99.6% in an ammonia process with pure oxygen gasification. The energy consumption of air separation will decrease significantly, if the purity of the oxygen product is reduced properly, which will lead to the decrease of the energy consumption of the total ammonia process, as the nitrogen element is needed for ammonia synthesis. However, the operating costs of the subsequent units will increase because of the increase of the syngas flow rate. So, there is an optimal oxygen purity that can minimize the energy consumption of the whole ammonia synthesis process. According to temperature, purification technology can be divided into cold and hot technologies. In this work, two different process models for ammonia production from coal with different purification technologies are developed to determine the process energy consumption with different inlet oxygen purity. In the process of ammonia production from coal with cold purification, the reduction of oxygen purity leads to the increase of energy consumption of oxygen compressor, methanol regeneration and refrigeration, and the decrease of nitrogen compressor power consumption. In the process with hot purification, the reduction of oxygen purity leads to the increase of energy consumption of oxygen compressor, preheating and MDEA regeneration, and the decrease of nitrogen compressor power consumption. The relationships between the eight kinds of energy consumption and oxygen purity are linear. Combined with the relationship between oxygen purity and the energy consumption of the air separation unit, the optimal oxygen purity which minimizes the process energy consumption is obtained. In the ammonia production process with cold purification, the optimal oxygen purity is 95%, which can save 10.3% of the energy consumption of the air separation compared with the current process using the 99.6% purity oxygen. While in the ammonia production process with hot purification, the optimal oxygen purity is 96%, which can save 8.4% of the energy consumption of the air separation.

The main objective of the research was to develop a method of biomass grindability determination (Biomass Grindability Index), which would allow for a clear classification of different types of solid biofuels in terms of their milling properties. The objective of the research included also the assessment of the possibility of adaptation of the existing coal grindability determination methods for evaluation of biomass milling. In the course of research, the biomass grindability determination method was modified to obtain the highest possible reliability of the developed index. The scope of laboratory tests being focused on influence of circumferential speed of test mill beaters, particle size distribution of sample, test time, mass and volume of sample. The results of laboratory and industrial tests have shown that the grindability index based on mean particle sizes of feed and product is unreliable. Grindability of different types of biomass, comminuted in beater mills, can be clearly determined by the index expressed as the ratio of energy consumption during the test to the amount of specified product size fraction. During the study laboratory test results obtained for proposed grindability index were compared to other grindability indices determined for utilized in research types of biomass.

In this work, the liquefaction of coal and biomass with direct liquefaction strategy was explored. The point of liquefaction is both to utilize a greater amount of the current coal and biomass assets all the more productively and to create an alternative liquid fuel to oil. Along these lines, the procedure parameters must be resolved to expand the liquefaction efficiency. In addition, it is proposed to do the liquefaction efficiency, particularly in the reactant conditions, to expand the measure of oil. Process parameters were controlled by utilizing Factorial Experimental Design technique in the liquefaction procedures. The solid/liquid ratio was changed as 1/2-1/4, the catalyst concentration was 2–6%, the temperature was 375–400 °C and the duration was 30–90 min. Starting nitrogen pressure was set at 30 bar, stirring speed was 400 rpm, coal/biomass proportion was settled at 1/1. Tetralin as a solvent and MoO3 as catalyst were utilized. Toward the finish of the liquefaction procedure, the total conversions were computed in view of the acquired non-reactive solid (char). As indicated by the outcomes obtained, the most total conversion (81.9%) was acquired at a solid/liquid proportion of 1/2, a catalyst concentration of 2%, a reaction time of 90 min and a reaction temperature of 400 °C. In light of total conversions and elective liquid fuel (oil) in the given conditions, the solid/liquid ratio should be taken as 1/2, the catalyst concentration is 2%, the reaction time is 30–90 min and the reaction temperature is 400 °C. The lowest reaction time found, in this study, is the innovative solution for reducing co-liquefaction cost preferred.

Biodiesel appears as a replenishable and sustainable energy source and can be used a direct replacement to petro-diesel without any major transformations in ongoing diesel engines. This work concentrates on production of Calophyllum Inophyllum biodiesel (CIB) and preparing 10% blend (CIB10) sample to investigate the effects of varying the injection strategies and exhaust gas recirculation (EGR) in common-rail direct injection engine. The experimental results shows that 10% of pilot fuel and 90% main injection strategy (B10@P10-M90) is superior among all others injection strategies with respect to pure diesel. B10@P10-M90 fuel injection strategy produces the maximum efficiency of 35.8% and lowest fuel consumption of 0.25 kg/kWh compared to all the injection strategies. The carbon monoxide (CO) and hydrocarbon (HC) emissions are also found to be quite low compared to all the other test samples including pure diesel. However B10@P10-M90 results in higher average oxides of nitrogen (NOx) emission which is 18.9% higher in contrast to conventional diesel at full load condition. With the implementation of 10% and 20% EGR with B10@P10-M90, the average NOx emissions decreased by 14.4% and 27.6% respectively compared to B10@P10-M90 without any EGR without significant loss in the performance of the existing diesel engine.

Two sugarcane biofuels and mineral diesel fuel are tested under full load conditions, under the same values of performance and under the European Transient Cycle on an engine test bench, without any modifications to the ECU. The target is to compare engine performance and emissions. At full load, engine performance varies due to the variation in LHV. Under the same values of performance, the sugarcane biodiesel-LS9 provides the lowest THC emissions. The higher CN and exhaust gas recirculation of the sugarcane biodiesel-LS9 and the higher H/C ratio of the sugarcane diesel-farnesane compared to the diesel S50 provide a NOx reduction. Neither the increment in bsfc nor the increment of %EGR for the sugarcane biodiesel-LS9 deteriorate the combustion, so its CO emissions are lower. The sugarcane biodiesel-LS9 leads to the lowest NOx and PM specific emissions under transient operation, followed by the sugarcane diesel-farnesane. The THC and CO specific emissions are higher for the biofuels in comparison to the diesel S50. The main reason for these results is the impact of the properties of the biofuels on the ECU response However, both biofuels produce less harmful emissions at idle conditions, which supports their usage to reduce exhaust emissions in urban areas.

In lieu of the fact that modern-day research is saddled with the responsibility of replacing/supplementing fossil fuels with biodiesel for use in diesel engines, the challenge still remains the need to improve the properties of biofuels towards stimulating high engine compatibility and performance. Despite the advances made in improving biofuels such as those sourced from Juliflora with additives, none seems to have addressed the potentials that underly the use of hybrid nano-particles as property-improvers of Juliflora-biofuel for use in diesel engines. This then led to the need to harness the potential use of hybrid CeO2:CuO, MnO2:Al2O3, ZnO:TiO2, and TiO2:Al2O3 in different ratios as a means of determining the best combination for improved fuel properties, high engine performance and reduced emissions. The nanoparticles were produced via sol-gel method and ultrasonicated with the biofuel before being characterized using scanning electron microscopy/atomic force microscopy. Based on the engine-test results, the brake thermal efficiency (BTE) increased from 1.11 to 2.21% for the biodiesel mixed with nanoparticles. Furthermore, the Nitrogen oxide (NOx), hydrocarbon (HC) and carbon monoxide (CO) emissions for the admixed biofuels decreased by 16.29–23.76%, 14.07–17.32% and 5.51–8.27% respectively compared to conventional diesel, thus reducing environmental pollution.

In order to explore the feasibility of suitable drying technology of tomato-paste, four solar drying methods were employed, namely (i) Basic Solar-drying Mode (SDM), (ii) Solar-Geothermal Drying (SGD), (iii) Convective Ventilated Solar Drying (CVD), and (iv) Combination of Ventilation and Geothermal Drying (VHD) and their effect on exergy efficiency, economic and quality attributes were investigated. Results showed that the drying time using different drying methods was 10, 9, 8, and 4.5 h for SDM, SGD, CVD, and VHD, respectively. Proposed model could better describe tomato paste drying behavior among eight tested mathematical models. Highest drying efficiency and specific energy consumption were observed for VHD method as 68.27% and 3.21 kWh/kg, respectively. Highest exergy efficiency was recorded for SGD and VHD as 54%. Payback period values were 0.28, 0.325, 0.3, and 0.169 years for SDM, SGD, CVD, and VHD, respectively. Color analysis revealed that CVD method was more suitable with the lowest total color change of 22.41 and highest brightness of the red color of 1.34. SGD method preserved 73.85% and 59.42% of phenol and flavonoid compounds, respectively, while VHD method preserve the highest flavonoid compounds as 82.24% compared to fresh sample. Geothermal energy combined with ventilation is recommended as a suitable drying method for tomato paste in terms of drying time, energy, exergy efficiency, economic, and quality attribute.

The co-combustion of raw and torrefied biomasses is recognised as environmental friendly energy conversion. Co-combustion of hard coal with raw biomass has been widely investigated in the literature. In contrast, co-combustion with torrefied biomass has been not particularly investigated. This paper shows the investigations of co-combustion of raw, torrefied biomass and biodegradable waste in bubbling fluidized bed combustor. Two kind of biomass sources (i.e. willow (Salix viminalis), olive oil residue) and waste wood from furniture manufacturing were analysed in terms of fuel feeding rate, CO, SO 2 and NO x emission and ash behavior. The part of a raw biomass was torrefied using a rotary kiln reactor. Hence, the combustion performance of raw and torrefied biomass was compared. The impact of torrefaction on the emission of CO, SO 2 and NO x depends on biomass type. In the case of willow the decrease of SO 2 emission was obtained when the raw biomass was substituted by the torrefied biomass. Additionally, ash fusibility from the raw and torrefied biomass was analysed. It was noticed that co-combustion of torrefied biomass caused increase of ash initial deformation temperature (IDT) comparing to co-combustion with a raw biomass.

The targets for renewable energy set by the European Union have resulted in a surge in consumption of wood pellets, and the demand is expected to further increase the next decade. We use economic modelling to assess the impact on global wood-based product markets of gradually increasing wood pellets consumption within the EU. Comparing a scenario wherein consumption is determined exclusively by market forces with one where EU consumption is set to double between 2015 and 2030, we characterize the deviation from the unregulated market equilibrium that would attain. Our results highlight the necessity of assessing market impacts over time, with a sufficient geographical disaggregation. An increased EU demand for wood pellets would, apart from increased EU production, results in increased imports. The main sources are projected to be Russia, Canada, and, particularly, the USA. The results indicate synergies and competition between wood-based products and wood pellets. In general sawmilling stand to gain from increased wood pellets' consumption, while the opposite holds for wood-based panels and most paper grades. Due to the feedstock mix used in production of wood pellets and wood-based products, effects vary over time and among different EU members, as well as between EU and other regions.

Torrefaction can upgrade the properties of biomass by reducing its oxygen content. In this study, the effects of torrefaction pretreatment on four different lignocellulosic biomass materials at three different temperatures (200 °C, 250 °C, and 300 °C) were studied using a Bosio EUP 6/1200 electric furnace. The results of proximate and ultimate analyses showed that the oxygen content is reduced with a higher torrefaction temperature, while the heating values increased, with 260 °C being the optimal temperature for the process. Among the torrefied products, oak waste wood (OWW, torrefied at 200 °C) had the highest solid yield, 93.2%, while the energy yield was 95.7%, fixed carbon (FC) content 11.8%, volatile matter (VM) content 80.9%, ash content 0.8%, and HHV 19.1 MJ/kg. The TGA/DTG experiments confirmed typical thermal properties for all lignocellulosic biomaterials, while the FTIR and XRD patterns for miscanthus and OWW indicate that the molecular chains of cellulose are broken (damaged) at temperatures higher than 300 °C. Porous ovals were observed at all temperatures in all biomass materials using SEM. SEM images showed that at higher temperatures the ovals started to crack, leading to materials with better grindability than the raw materials. Therefore, we conclude that solid biofuels with properties similar to coal can be produced with torrefaction.

Derived from bio-drying of municipal organic wastes (MOWs), biodried products (BPs) are normally accepted as carbon-neutral and renewable energy sources. In this study, torrefaction at different temperatures was conducted for BPs to upgrade their properties as fuels. The results indicated that high temperatures promoted formation of gases and liquids during BPs torrefaction. Among the gaseous products, the CO2 content was significantly higher than those of CO and H2. In the liquid products, including H2O, benzenes and phenols were two typical components, which coincided with organics devolatilization and lignocellulose depolymerization. Furthermore, the fuel properties of torrefied BPs were upgraded with higher fixed carbon contents (21.95%–29.25%) and heating values (15.15–17.98 MJ/kg) due to the elimination of oxygen-containing volatiles. During combustion of torrefied BPs, the devolatilization of organics was diminished, but the decomposition of lignocellulose was enhanced. Moreover, torrefaction promoted the char combustion with lower activation energy values (151.69–207.76 vs. 160.20–215.56 kJ/mol). In addition, torrefaction reduced the emissions of C O/C–O compounds and enhanced the release of CO2, CO and H2O during combustion. However, severe torrefaction decreased energy yields and the potentials of BPs for energy recovery as fuels. Moderate torrefaction (approximately 250 °C) was suggested to be more beneficial for upgrading BPs.

The article presents the results of the experimental studies of the processes of removing moisture from fairly typical and widespread forest combustible materials, and woodworking waste under conditions of their thermal preparation for combustion. Based on the results of the experiments, the main regularities of the drying processes of woody biomass under conditions of radiation-convective heating have been established. The integral characteristics (characteristic times) of the drying process of forest biomass under typical (for this technology) heating conditions have been determined. The experiments were carried out on equipment that provides a low level of error (less than 3.3%) for determining the main characteristics of the biomass dehydration process. The values of the mass rates of moisture removal (Weva) of four promising (for modern and future power engineering) and fairly common types of biomass have been established in the ambient temperature range from 333 to 393 K, which corresponds to the operating modes of the drying equipment of power plants. According to the results of the experiments, it was shown that at relatively moderate ambient temperatures (333≤ Tg ≤ 353 K), the type of wood has a rather significant effect on the characteristics and conditions of the dehumidification process. At the same time, the process of drying wood chips is much faster compared to other types of biomass. As the ambient temperature rises (at 373≤Tg ≤ 393 K), the influence of the type of biomass decreases. As a result of the experiments, a physical model of the process of removing moisture from the bulk layer of biomass was formulated. According to the results of the experiments, it was found that before burning forest biomass in boilers of thermal power plants, it is most advantageous to carry out drying in conditions of relatively moderate (at 333≤Tg ≤ 353 K) ambient temperatures. The studies carried out provide grounds for justifying the use of forest combustible material as fuel (or one of the components of the fuel mixture) at thermal power plants currently operating on coal.

Reserves of fossil fuel are being depleted, and its use to generate energy also affects the environment. Sustainable and clean energy sources, therefore, need to be produced to meet the demands. In this research, combined blended fuels were produced from cottonseed and palm oil methyl esters with petroleum diesel fuel. To achieve the benefits of palm oil biodiesel (high calorific value) and cottonseed oil biodiesel (low kinematic viscosity and acid value), the combined biodiesel blend (C05P15, C10P10, and C15P05) has been tested to assess their effect on engine performance, emissions, and tribological properties. The physicochemical properties of all fuels were measured following ASTM D6751 standard. A single-cylinder, 4-stroke, and the natural aspiration diesel engine were used for engine testing. The experimental results showed that all combined blended fuels have low brake thermal efficiency and emitted fewer hydrocarbons, carbon monoxide, and smoke opacity apart from nitrogen oxides compared with petroleum diesel fuel. Based on results, the combined blended fuel can be used as a substitute fuel in diesel engines without any engine modifications.

This study investigated the influence of torrefaction (300 °C) on the combustion performances of blends of biomass-plastic wastes (Mango branches (MBr), newspaper (Np), LDPE) using thermogravimetric analysis. The torrefied waste blends were co-combusted with coal at a blending ratio of 25 and 50 wt. % to identify possible interactions between the fuels’ components. Synergistic behaviours were noted during combustion of the torrefied MBr-Np blend and the comprehensive combustion index, Dc was 29 % higher than the predicted value. Interestingly, synergistic interactions were perceived during co-combustion of the different wastes with coal. The measured burnout temperatures (TBO) of all torrefied waste-coal blends were lowered by 6–15 %, compared to their predicted values, especially for MBr-Np-coal blends. Synergistic interactions during torrefaction of MBr-Np not only improved the combustion reactivity of the resulting char but also enhanced coal combustion in the blend compared to combustion of torrefied biomass-LDPE-coal blends. It was concluded that synergies during co-combustion of waste char with coal were governed by the waste type, its composition and the interactions that prevailed during torrefaction of the wastes.