Heat Utilization Research Articles

Study on heat storage characteristics and carbon optimisation in the sintering process

In response to the phenomenon of automatic heat storage during the sintering process of iron ore, heat balance analysis concerning the main chemical reactions and physical heat carried by gas and solid materials was conducted. A unit heat storage model for the sintering process was established. Further, a mathematical model to solve the heat transfer characteristics between different sintering layer units was proposed and established based on temperature–time curves of the gas and solid phases. Using these models, the heat storage of each layer unit was calculated under the condition of uniform carbon allocation. Subsequently, the optimisation of carbon allocation at each layer unit for maximising the utilisation of heat storage was investigated. The heat required for sintering by the layer unit was taken as the constraint, and the maximum utilisation of heat stored in each layer unit was taken as the goal to optimise the carbon allocation in the height direction. The calculation results show that as the unit thickness is 100 mm and the total thickness of the layer is 600 mm, the heat transfer ratio of the upper unit to the lower unit is 34.22%, 30.29%, 14.74%, 9.49%, and 1.17%, respectively. The heat storage and available heat storage rate increase with the increase of layer height, with heat storage ranging from 0.69 × 104 to 5.14 × 104 KJ/t and heat storage rate ranging from 11.63% to 49.37%. After optimising carbon allocation, the unit achieved a maximum carbon reduction of 60.04%, resulting in an overall reduction in carbon allocation of 46.20%. This adjustment aligns more closely with the industrial processes.

Simulation study of R1234ze and its mixed working medium in TEG‐ORC combined cycle

AbstractThermoelectric generation (TEG) and organic Rankine cycle (ORC) technologies both have their respective limitations in recovering waste heat from ships. However, the combination of TEG and ORC is an effective approach to achieve cascaded waste heat recovery and improve heat utilization efficiency. There has been some progress in research on waste heat recovery in maritime applications based on TEG‐ORC combined cycles. The selection of a working medium is a crucial element that directly influences the design and performance of the entire system, but there is limited research on the impact of different working fluids on combined cycle systems. In this study, a simulation model of a TEG‐ORC combined cycle system was established to examine its output potential using two different working fluids R1234ze and a mixture of R245fa/R1234ze. The results demonstrate that compared to employing the R1234ze working medium, the combined cycle system with the mixed working medium achieved a 13% increase in maximum output power, a 102% improvement in optimum thermal efficiency, and a 53% reduction in optimum power production cost. Additionally, the power output distribution in the system utilizing the mixed working fluid was more uniform compared to the system employing a single working medium. This confirms the great potential of using a mixed working fluid in a combined cycle system.

A Study of Heat Recovery and Hydrogen Generation Systems for Methanol Engines

Biofuels are the most essential types of alternative fuels, which currently have significant potential to reduce CO2 emissions compared to fossil fuels. Methanol is a more efficient fuel than petrol due to its physicochemical properties, such as a higher latent heat of vaporization, research octane number, and heat of combustion of the fuel–air mixture. Also, biomethanol is cheaper than traditional petrol and diesel fuel for agricultural countries. The authors have proposed a new approach to improve the characteristics and efficiency of methanol diesel engines by using biomethanol mixed with hydrogen instead of pure biomethanol. Using a hydrogen–biomethanol mixture in modern engines is an effective method because hydrogen is a carbon-free, low-ignition, highest-flame-rate, high-octane fuel. A small quantity of hydrogen added to biomethanol and its combustion in an engine with a heat exchanger increases the combustion temperature and heat release, increases engine power, and reduces fuel consumption. This article presents experimental results of methanol combustion and a hydrogen-in-methanol mixture if hydrogen was retained due to the utilization of the heat of the exhaust gases. The tests were carried on a single-cylinder experimental engine with an injection of liquid methanol and gaseous hydrogen mixtures. The experiments showed that green hydrogen generated onboard the car due to the utilization of heat significantly reduced fuel costs of engines of vehicles and technological installations. It was established a hydrogen gaseous mixture addition of up to 5% by mass to methanol requires a corresponding change in the coefficient of excess air to λ = 1.25. Also, using an additional hydrogen mixture requires adjustment at the ignition moment in the direction of its decrease by 4–5 degrees of the engine crankshaft. Hydrogen gas mixture addition reduced methanol consumption, reaching a maximum reduction of 24%. The maximum increase in power was 30.5% based on experimental data. The reduction in the specified fuel consumption, obtained after experimental tests of the methanol research engine on the stand, can be implemented on the vehicle engines and technological installations equipped with an onboard heat recovery system. Such a system, due to the utilization of heat and the supply of additional hydrogen, can be implemented for engines that work on any alternative or traditional fuels.

Investigation of Engine Exhaust Heat Recovery Systems Utilizing Thermal Battery Technology

Over 50% of an engine’s energy dissipates via the exhaust and cooling systems, leading to considerable energy loss. Effectively harnessing the waste heat generated by the engine is a critical avenue for enhancing energy efficiency. Traditional exhaust heat recovery systems are limited to real-time recovery of exhaust heat primarily for engine warm-up and fail to fully optimize exhaust heat utilization. This paper introduces a novel exhaust heat recovery system leveraging thermal battery technology, which utilizes phase change materials for both heat storage and reutilization. This innovation significantly minimizes the engine’s cold start duration and provides necessary heating for the cabin during start-up. Dynamic models and thermal management system models were constructed. Parameter optimization and calculations for essential components were conducted, and the fidelity of the simulation model was confirmed through experiments conducted under idle warm-up conditions. Four distinct operational modes for engine warm-up are proposed, and strategies for transitioning between these heating modes are established. A simulation analysis was performed across four varying operational scenarios: WLTC, NEDC, 40 km/h, and 80 km/h. The results indicated that the thermal battery-based exhaust heat recovery system notably reduces warm-up time and fuel consumption. In comparison to the cold start mode, the constant speed condition at 40 km/h showcased the most significant reduction in warm-up time, achieving an impressive 22.52% saving; the highest cumulative fuel consumption reduction was observed at a constant speed of 80 km/h, totaling 24.7%. This study offers theoretical foundations for further exploration of thermal management systems in new energy vehicles that incorporate heat storage and reutilization strategies utilizing thermal batteries.

A novel Ca-Ni looping with carbonation heat thermochemical regeneration method for post-combustion CO2 capture: System integration, energy-saving mechanism, and performance sensitivity analysis

Thermal coupling between the calcium looping (CaL) process and chemical looping combustion (CaL-CLC) offers advantages to avoid electricity consumption of air separation, and the CaL-CLC has presented superior performance realizing CO2 capture. However, in these CaL-CLC and CaL configurations for post-combustion CO2 capture, the carbonation heat is recovered for steam generation with a significant temperature difference, leading to considerable irreversible loss. To prevent the temperature mismatch during carbonation heat recovery, this paper proposes the concept of Ca-Ni looping with the carbonation heat thermochemical regeneration method. Additionally, a novel system integrating with a combined cycle is introduced to effectively decarbonize flue gas. Results show that the proposed system has superior performance compared with the reference system based on the Ca-Cu looping method. The specific energy consumption for CO2 avoided (SPECCA) decreased from 2.13 MJ/kg CO2 in the reference system to 1.43 MJ/kg CO2. Exergy analysis indicates that a total 6.3 % exergy destruction reduction is realized by replacing the Cu-based chemical looping combustion with the Ni-based oxidation reaction for calcination heat supply. Furthermore, the energy utilization diagram (EUD) reveals the mechanism of exergy destruction reduction caused by the thermal coupling between reaction processes. Besides, the impact of key operating parameters on the proposed system performance is investigated. Overall, the proposed Ca-Ni looping with carbonation heat regeneration method enhances the utilization of mid-temperature carbonation heat by converting it into high-grade thermal energy suitable for combined cycles, thereby offering a promising alternative for low-energy-consumption CO2 capture.

Cooling Performance of a Nano Phase Change Material Emulsions-Based Liquid Cooling Battery Thermal Management System for High-Capacity Square Lithium-Ion Batteries

This study investigated the application of nanophase change material emulsions (NPCMEs) for thermal management in high-capacity ternary lithium-ion batteries. We formulated an NPCME of n-octadecane (n-OD) and n-eicosane (n-E) with a mass fraction of 10%, whose phase change temperatures are 25.5 °C and 32.5 °C, respectively, with specific heat capacities 2.1 and 2.4 times greater than water. Experiments were conducted to evaluate the thermal control performance and latent heat utilization efficiency of these NPCMEs. The NPCMEs with an n-OD mass fraction of 10% (NPCME-n-OD), particularly reduced the battery pack’s maximum temperature and temperature difference to 41.6 °C and 3.72 °C under a 2 C discharge rate, lower than the water-cooled group by 1.3 °C and 0.3 °C. This suggests that nano emulsions with phase change temperatures close to ambient temperatures exhibit superior cooling performance. Increased flow rates from 50 mL/min to 75 mL/min significantly lowered temperatures, resulting in temperature reductions of 2.73 °C for the NPCME-n-OD group and 3.37 °C for the NPCME-n-E group. However, the latent heat utilization efficiency of the nano emulsions decreased, leading to increased system energy consumption. Also, it was found that the inlet temperature of the NPCMEs was very important for good thermal management. The right inlet temperatures make it easier to use phase change latent heat, while excessively high temperatures may make thermal management less effective.

Effect of air layer on PCMs melting process inside a spherical container: A numerical investigation

Efficient latent heat storage technology is getting significant interest from the researchers, scientist, and engineers who are involved in solar heating and cooling, waste heat utilization, and building energy management applications. The latter materials are employed most frequently in this connection owing to their pronounced energy storage capacity and moderate cost. The present work involves a numerical analysis for the assessment of heat transfer through paraffin wax RT42 when it is fully converted from solid to liquid phase in a spherical container with and without air layer. The interaction of the py-porosity combination was evaluated numerically with the use of ANSYS/FLUENT 16 program. The results show that the presence of a 1 mm thick air layer increased the total melting time by 33.33%, while a 2 mm thick air layer resulted in a 66.67% increase compared to the control without an air layer. In this research, it is clear that air layers play a major role in the delay of the melting of paraffin wax.

PRINCIPLES OF SIMULATION OF ENERGY-EFFICIENT GRANULATION PROCESSES IN A FLUIDIZED BED

The principles of physical and mathematical modeling of inhomogeneous jet-pulsating fluidization in the self-oscillating mode considering the movement of solid granulated particles on the working surfaces of the gas distributing device are investigated. The research tasks include substantiating the method of interaction between the gas phase and granular solids to ensure the implementation of heterogeneous jet-pulsating fluidization in the self-oscillating mode, experimentally determining hydrodynamic parameters to minimize the risk of stagnant zones on the working surface of the gas distributing device and formulating principles for introducing flat gas jets into orthogonal planes through a gas distribution device. The physical model focuses on creating heterogeneous jet-pulsating fluidization which is based on the formation of heterogeneous porosity in the bed of solids within the apparatus chamber. The study highlights the importance of rationally organizing the interaction mode between the gas phase and solids to ensure active circulation of granular material between 3 main technological zones: humidification, active heat exchange and relaxation. This organization enables sufficient mass transfer along the height of the bed and getting a product with the desired properties. Implementing the proposed modeling principles in equipment development will allow increasing the heat utilization coefficient by more than 60 % and will facilitate the implementation of innovative technology. The research contributes to the development of fluidization technology and its application in granulation at temperatures exceeding the melting point of thermolabile components, ensuring efficient use of resources and energy, and enhancing the environmental safety of technological processes. Bibl. 22, Fig. 11.

Multi-objective optimization and influence degree analysis of the thermally integrated HP-ORC carnot battery based on the orthogonal design method and grey relational analysis

Thermally integrated heat pump (HP)-organic Rankine cycle (ORC) Carnot battery is a promising solution for efficient energy storage and waste heat utilization. Firstly, in order to research the influence degree of the operating parameters on the system performance, single-objective optimization is conducted by the orthogonal design method. Then, multi-objective optimization is conducted by combining the grey relational analysis (GRA) and orthogonal design method to assess the comprehensive performance of the system. The importance order and contribution rates of the operating parameters and the optimal operating combinations are determined. Finally, in order to explore the influence mechanism of the parameters on the system performance, the influence of the parameters on the subsystems and the subsystems on the whole system is quantitatively analyzed. The results show that thermal storage temperature difference, waste heat temperature difference and cold source temperature are the most important parameters affecting the comprehensive performance of the whole system. Under the optimal operating conditions, round-trip efficiency, exergy efficiency, energy storage capacity (ESC), energy storage density (ESD) and levelized cost of storage (LCOS) are 47.05 %, 22.66 %, 1943 kW, 2.90 kWh/m3 and 0.38$/kWh, respectively. Compared to the ORC subsystem, the HP subsystem is more important to round-trip efficiency and exergy efficiency.

An efficient carbon-neutral power and methanol polygeneration system based on biomass decarbonization and CO2 hydrogenation: Thermodynamic and economic analysis

This study presents a novel approach to enhance methanol synthesis (MS) efficiency through integration with an MEA-based decarbonized biomass direct-fired power plant (BFPP-CCS). The integration optimizes the utilization of chemical energy from feedstocks by combining exothermic MS reactions with diverse thermal energies, which effectively captures chemical energy through synergistic utilization from MS and various thermal inputs. Gradual methanol conversion maximizes both its chemical and fuel properties. Through such integration, the enhancement of waste heat and purge gas utilization in MS and BFPP carbon capture processes results in a 3.42 MW improvement in power generation and a 26.0 % reduction in associated energy penalties from CCS. Analysis of a 150 kton/yr MS facility and a 35 MW BFPP-CCS demonstrates 2.87 % increase in overall efficiency and reduction in CCS heat consumption by 1.03 GJ/tCO2. Moreover, this integrated approach yields a 33.1 M$ NPV increase and 3.4 years DPP decrease, achieving carbon-neutral power and liquid fuels production. Sensitivity analysis indicates the polygeneration system performs optimally around 250 °C and 60 bar, with a preference for 0.90 MS recycle ratio. Additionally, factors such as carbon recovery rate, electrolysis efficiency, and fixed carbon content in biomass are quantitatively revealed as crucial for maximizing carbon mitigation potential.

Driving industrial symbiosis: Evaluating policy intervention effects on waste heat utilization in local district heating networks

This study aims to quantitatively assess the required policy support level to ensure economic viability for all stakeholders in the context of using industrial waste heat as source of local district heating (DH). Additionally, the research explores the potential of industrial symbiosis to support district-level energy transition in the context of Positive Energy Districts and Smart Cities. The proposed approach combines energy modelling tools, namely the Multi Energy System Simulator (MESS) model and financial concepts (i.e. Cash Flow Analysis, Net Present Value Evaluation) typical of industry’s project evaluation. It is then tested in the area of Bolzano, Italy. The study examines various policy scenarios, including financial incentives and the involvement of district heating operators (DHOs). Initial findings indicate that district heating offers significant cost advantages (up to –23%) over electrified systems. However, industries face challenges meeting standard payback periods without policy intervention in the context of projects using waste heat as a source of DH. A combined scenario involving DHOs handling connection costs with a 60% incentive and industries receiving a 15% Feed-In Premium shows promising results in achieving economic feasibility. The results underscore the critical role of policy support in overcoming barriers. Consequently, it is possible to strengthen cooperation between industries and districts fostering local energy transition. Nonetheless, the achievement of positive energy balance requires a stronger presence of RES particularly on the electricity side. The study highlights the broader implications for similar projects in other regions and the essential role of policy interventions in facilitating such industrial symbiosis.

Numerical analysis on the performance of sodium chloride solution evaporative crystallization system driven by high-temperature heat pump

In the context of sustainable development, heat pump technology is increasingly recognized as a key method for enhancing the efficiency of evaporative crystallization processes. In this study, we propose a high-temperature heat pump evaporative crystallization system to facilitate the recycling of waste heat from secondary steam in low-vacuum and low-temperature evaporative crystallization, thereby achieving the cyclic utilization of condensation heat from secondary steam. The primary objective of this research is to develop a comprehensive mathematical model for the HPC system that investigate its operating performance under varying conditions, with the aim of promoting its practical application. The results demonstrate that by adjusting operating pressures, the temperature of the secondary steam can be controlled, allowing for regulation of the main particle size of the product. Specially, when maintaining the flow rate of the raw material liquid at 90 % of design condition, it is possible to achieve a maximum main particle size of 2.8 mm. Additionally, fluctuations in the flow rate of the raw material liquid significantly impact the cycle rate, with the optimum operating flow rate range identified as 75 % to 110 % of the rated value. The coefficient of performance of the system can achieve 5.85 under design conditions with a concentration of 4 % and flow rate of 310 kg/h. This research provides a theoretical foundation for the practical operation and commissioning of the HPC units.

Energy, Exergy, Exergo-economic and Exergo-environmental analysis of Waste Heat-based Convective Dryer

Food drying is a widely used method of food preservation worldwide, and the utilization of waste heat from exhaust flue gas presents a significant opportunity to reduce the energy consumption of industrial drying processes. This study thoroughly examines the energy and exergy efficiency, sustainability indicators, and various exergo-environmental and exergo-economic parameters to assess the performance of a waste heat-based convective dryer (WHCD). The study found that drying at 70°C performed the best (among 50°C, 60°C and 70°C) for the overall drying process, with a maximum overall exergetic efficiency of 4.89%. The results of exergo-economic analysis revealed that the drying chamber exhibited the highest exergy destruction cost at US$0.01193 per hour, and it was determined that improving the drying chamber was of paramount importance. An exergo-environmental assessment indicates that the proposed dryer effectively mitigates 14.15 tons of over a 20-year lifespan. Sensitivity analysis of the proposed system reveals that the energy efficiency is more sensitive to the food drying temperature than the exergy efficiency. A 33% increase in drying temperature increases the exergy efficiency by 19.37% while reducing the energy efficiency by 37.54%. Hence, adopting the proposed system in industrial settings could significantly enhance energy-efficient and sustainable food drying processes.

Adaptive optimization of thermal energy and information management in intelligent green manufacturing process based on neural network

The study of thermal energy adaptive optimization has important theoretical and practical significance. The deep learning neural network model is used to monitor and analyze the thermal energy data in the manufacturing process in real time. Through the construction of adaptive optimization algorithm, the heat input and output are systematically evaluated and adjusted, and the heat distribution scheme is dynamically optimized according to environmental changes and production needs. At the same time, information management system is introduced to realize data summary, feedback and decision support. The experimental results show that the proposed method can effectively reduce the heat energy loss, optimize the heat energy utilization, and significantly reduce the overall energy consumption compared with traditional management methods. With real-time data updates, the system improves the flexibility and responsiveness of the production process, significantly improving manufacturing efficiency. The thermal energy adaptive optimization method based on neural network provides an effective solution for intelligent green manufacturing, which can not only optimize thermal energy management, but also provide a reference for other resource conservation and environmental protection.

Heat Energy Utilization of a Double-Flash Geothermal Source Efficiently for Heating/Electricity Supply through Particle Swarm Optimization Method

The principal aim of this article is to optimize the thermal and electrical efficiency of a geothermal combined heat and power system through metaheuristic particle swarm optimization (PSO) method. The objective of this research is to conduct a thorough analysis of the incorporation of metaheuristic PSO technique, with a specific emphasis on the potential advantages and obstacles associated with the utilization of metaheuristic approaches in improving the effectiveness of geothermal energy systems. The utilization of a double-flash geothermal system in conjunction with a transcritical carbon dioxide Rankine cycle is utilized for the co-generation of electricity and thermal energy. The research utilized a PSO method to enhance power generation, heating capacity, and overall system efficiency. The PSO algorithm was employed to determine the optimum operational parameters for a pressure level of 820 kPa and a pressure ratio of 1.59, leading to the maximization of power output to 2591.4 kW The PSO algorithm effectively identified the optimal operational parameters as a pressure of 820 kPa and a pressure ratio of 1.59, resulting in the achievement of a peak power output of 2591.4 kW. The methodology has determined that a pressure of 916.4 kPa and a pressure ratio of 1.5 represent the optimal parameters for achieving a maximum heating capacity of 12329.1 kW.

Technical and economic analysis of digitally controlled substations in local district heating networks

Since the 1990s, there has been a noticeable increase in the establishment of local district heating networks in Germany, coinciding with the use of thermal energy from biogas and biomass facilities. Historically, the prioritization of economically efficient heat utilization was subdued due to favorable electricity feed-in tariffs. However, with the expiration of Renewable Energy Sources Act subsidies, operators shifted focus to the operational costs of district heating networks. This study aims to examine the effects of optimizing controllers and valves at district heating substations in single-family homes, utilizing two local district heating networks. The emphasis is on evaluating impacts on operating costs and determining whether the economic and energetic benefits justify implementation. Simulation studies in MATLAB/Simulink Simscape depict both consumers and district heating networks individually, without aggregation. In the most favorable scenario, investing in enhancing substation controllers in single-family homes is projected to yield returns after 13 years. Comprehensive optimization of all substation controls in single-family homes can potentially result in up to 9% savings in thermal energy demand due to reduced heat losses and a corresponding 9% reduction in electrical power consumption for the main pump.

Unlocking the potentials using humidifier-dehumidifier for proton exchange membrane fuel cell waste heat recovery

This study addresses the dual challenges of waste heat dissipation and operational longevity degradation in proton exchange membrane fuel cells (PEMFCs) by proposing a novel hybrid system that integrates PEMFC with a humidifier-dehumidifier (HDH) unit. The primary objective is to enhance the energy efficiency and sustainability of PEMFC systems by leveraging waste heat for freshwater generation. A comprehensive mathematical model based on thermodynamic and electrochemical principles is developed to capture the system’s inherent irreversible losses. The performance metrics, including power density, energy efficiency, and exergy efficiency, are evaluated through systematic computational simulations. The proposed PEMFC/HDH hybrid system achieves a maximum power density of 4.8292 W cm-2 and an energy efficiency of 17.30%, showing a 1.48% improvement over standalone PEMFC systems. Parametric studies reveal that optimizing operating pressure significantly enhances system performance, while factors such as increased PEM thickness and thermodynamic loss composite parameter hinder it. Local sensitivity analysis identifies PEM thickness as the most critical parameter affecting performance. This research pioneers the integration of PEMFC and HDH for cogeneration, offering a viable path for performance enhancement and efficient waste heat utilization. The findings contribute to the strategic design and operational regulation of PEMFC-based hybrid systems for sustainable energy solutions.

Thermal recovery of heavy oil reservoirs: Modeling of flow and heat transfer characteristics of superheated steam in full-length concentric dual-tubing wells

Accurately predicting the flow and heat transfer characteristics of superheated steam (SHS) in the wellbore is essential for efficiently developing heavy oil reservoirs. However, few studies have examined SHS flow in full-length concentric dual-tubing wells (CDTWs). In this paper, firstly, based on fluid dynamics and thermodynamics theories, a mathematical model for SHS flow in vertical and horizontal wellbores is proposed. Then, this model is solved using a finite difference method for spatial discretization and an iterative technique. Finally, model verification, type curve analysis, and sensitivity analysis are conducted sequentially. The results indicate that SHS temperature and pressure are independent variables, and the effect of friction energy on temperature is greater than its impact on pressure. The injection rate has a critical value, and the critical injection rates of the main controlling factors affecting the pressure drop and temperature drop of SHS in the vertical tubing are different. When the injection rate is below the critical value, the gravitational force of the SHS helps maintain high enthalpy. The SHS should be transported to the well bottom as quickly as possible. To enhance the uniform heating effect of the reservoir and improve heat utilization efficiency, a relatively small injection rate, high injection pressure, and low injection temperature are recommended. The uniformity of SHS pressure and temperature distribution in the horizontal annulus positively correlates with the uniformity of the reservoir's heat absorption rate. Achieving more uniform SHS pressure and temperature profiles in the horizontal annulus benefits the uniform heating of the reservoir.

Experimental and numerical study on energy flow characteristics of a plug-in hybrid electric vehicle with integrated thermal management system

A simulation model was developed and validated to explore the energy flow distribution in plug-in hybrid electric vehicles (PHEVs) with integrated thermal management systems (ITMS), using a genetic algorithm to focus on components, subsystems, and the power system. The influence mechanism of temperature and state of charge (SOC) on the energy consumption of the ITMS was subsequently analyzed throughout the driving cycle. The main findings are: (1) Engines possess significantly greater potential for waste heat utilization compared to motors, with the thermal loss of the engine being 9.6 times greater than that of the motor. (2) Although the ITMS improves the engine energy utilization efficiency, considerable room for improvement remains. At -18 °C, the heat loss of the radiator and the heat used by the ITMS account for 14.6% and 7.7%, respectively. (3) A pronounced impact of low temperature and SOC on vehicle energy consumption was identified. Energy consumption increased by a factor of 2.14 as temperature decreased from 48 °C to -18 °C. The total energy consumption at SOC 35 was 1.44 times greater than at SOC 75. These findings offer valuable insights for optimizing energy flow in PHEVs equipped with ITMS.

Performance analysis of a pilot gasification system of biomass with stepwise intake of air-steam considering waste heat utilization

Although the fixed-bed gasifier is widely used because of their simple structure, easy operation, and strong adaptability to biomass type, its economy is weakened by their low bioenergy conversion ability and heat utilization efficiency. Therefore, a novel biomass gasifier with stepwise intake of air–steam is proposed, which also innovatively integrates the concept of multi-stage utilization of waste heat generated during the gasification process into its design. And a pilot system comprising the novel biomass gasifier with a biomass consumption of 30 kg/h has been built. A series of continuous air-steam gasification experiments on pine wood particles shown that, the high-temperature steam in the reduction zone enhanced the ring opening of aromatic hydrocarbons, decarboxylation, dehydroxylation, and the conversion of long-chain to short-chain hydrocarbons, thus increasing the yield of small-molecule gases. The steam reforming reaction played an active role in increasing the hydrogen content, the gasification gas's production and low calorific value. And the relationship among the reaction rates on the surface of char should be VC + H2O＞VC+2H2O＞VC + CO2＞VC+2H2. The minimum input temperature of steam was 350 °C, otherwise more char would be consumed in the oxidation zone to provide heat. The proposed steam-air gasification system achieved optimal performance with an air-to-steam mass ratio (A/S) of approximately 8, a steam temperature of 400 °C, and an air-to-biomass mass ratio (A/B) of 1.2. The average gas production could reach 2.67 m3/kg, with the average low calorific value of 5.1 MJ/m3. The average hydrogen content could reach 20 %, with the average H2/CO ratio of 2. The average effective gasification efficiency could reach 69.72 %. Compared with air gasification, the proposed air-steam gasification was equivalent to the use of 1 kWh of electricity to produce 2.4 kWh of electricity. Combining market research, the price of steam produced by the proposed system was approximately 70 CNY/t less than when using natural gas. This study aims to provide a technical reference for improving the performance of biomass gasification in practical applications.