Thermal Waste Research Articles

Model of Residence Time Distribution, Degree of Mixing and Degree of Dispersion in the Biomass Transport Process on Various Grate Systems

Biomass includes diverse raw materials of plant or animal origin that are biodegradable. It also constitutes a significant fraction of municipal waste burned in waste incineration plants. Grate technology is one of the more commonly used technologies in the thermal conversion of biomass. The mass transport of material on the grate is a complex issue. The article presents a model for determining selected mass flow parameters on the grate, primarily the distribution of residence time, degree of mixing, and dispersion. The model is a description of mechanical mass transport on the grates of thermal waste conversion devices and represents the kinetics of the processes occurring on the grate. It allows for the design of the details of the specific movement of the material particles on the grates depending on their size and density. In addition, experimental tests of flow parameters realized on a laboratory stand simulating the operation of the grate are presented. Tests were conducted on different types of grates and with selected types of biomass materials. They included variants of the operating parameters of the grates, such as the speed and pitch of the grates an their inclination, simultaneously with the fulfillment of the 1:1 scale condition of the size of the laboratory stand to the actual size of the industrial grate (its section). A general trend can be seen in the mean residence time of the material on the grate, which is higher in the case of a reciprocating grate. The degree of dispersion is mainly influenced for moving and reciprocating grates by the inclination angle of the grate. The analysis of the test results made it possible to clarify the mechanism of material mass transport on different types of grates. It is also proposed to use the results in modeling the process of biomass combustion in grate chambers as well as their design and operation.

Evaluation of Multi-Functional Variable Refrigerant Flow System With Thermal Energy Storage and Photovoltaic-Based Distributed System for Net-Zero Energy Home Design

Abstract Efficient heating and cooling systems and renewable energy sources are crucial for effectively designing net-zero energy homes (NZEHs). The study proposes using a multi-functional variable refrigerant flow system with hydraulic heat recovery (MFVRF-H2R) to reduce heating, ventilating, and air-conditioning (HVAC) and hot water energy usage, offering a practical approach to enable NZEH solutions. Photovoltaic (PV)-based on-site power generation is utilized to achieve zero energy performance in residential buildings. A building energy simulation study is conducted to assess the effectiveness of the combined systems in various climate conditions. To develop the simulation model, the US National Institute of Standards and Technology (NIST)’s net-zero energy residential test facility is used as the benchmark for NZEH baseline models. The MFVRF-H2R system is incorporated into the NZEH baseline to propose a more-energy-efficient design with heat recovery technology. eQUEST and post-processing calculations are used to simulate NZEH performance, comparing whole-building energy end-use and PV capacity for the baseline and alternative models with MFVRF-H2R. Results demonstrate that the proposed variable refrigerant flow (VRF)-based NZEH design can provide potential energy savings of up to 32% for cooling energy under various climate zones. Moreover, the NZEH design with the proposed MFVRF-H2R can achieve up to a 90% reduction in domestic hot water usage compared to an NZEH design without VRF heat recovery technology. The study suggests that the MFVRF-H2R system can provide practical and realistic solutions for making HVAC energy-efficient by minimizing thermal waste and reusing it for other thermal parts of the building, such as hot water applications. Consequently, this study highlights the effectiveness of the MFVRF-H2R system in designing NZEHs while considering heat recovery and renewable energy technologies.

Comprehensive Chemical Cleaning of Flue Gases of Thermal Waste Treatment Plants Using a Catalytic Filter

The efficiency of integrated gas emissions treatment in thermal waste treatment units from dust particles and fossil sour traces of SO2, HCl and HF, as well as volatile organic compounds (VOCs) and dioxins at 300–400 °C of the gas mixture with a ceramic gas filter with aluminosilicate fibers added with catalytic MgCr2O4. The efficiency of sorption purification of tail gases from SO2, HCl and HF during the test period was 79–90 %, which depended on the supply of slaked lime to the catalytic filter to prevent catalyst deactivation. Thermal mode of chemical refining (300–400 °C) provided effective catalytic purification from VOCs, CO, and dioxins in combination with the chemisorption recapture of catalytic poisons and dust, preventing neither sorbent degradation nor damage to the catalyst.

Nano-engineering enabled heat pipe battery: A powerful heat transfer infrastructure with capability of power generation

Low-grade electronic waste heat lower than 100 °C widely exists in information technology equipment. Waste heat from data centers is particularly concerning. A micro heat engine (or Carnot battery) that is suitable for the direct recovery of low-grade waste heat during the cooling of electronic devices is promising. In this study, a novel looped heat pipe battery (LHPB) was proposed to achieve the aforementioned function. By absorbing heat through the evaporator of the proposed LHPB, the working fluid was transformed into high-speed vapor and blasted the generator rotor sealed in the LHPB condenser, which directly converted waste heat into electricity. The proposed LHPB can realize excellent thermal management and effective waste heat recovery simultaneously. The experimental results revealed that under the heat load of 150 W with a rated 12 V fan cooling, the device can maintain the temperature of the heat source at 72 °C, and the maximum output electrical power is 6.19 mW. The nominal power usage effectiveness is lower than 1.01. Even though the generated electrical power is still low in the present form, this pioneering study might open novel avenues for electronic cooling and waste heat recovery.

Investigation and simulation of parabolic trough collector with the presence of hybrid nanofluid in the finned receiver tube

The present study discusses the thermal performance of the receiver tube, which contains a wall with various fin shapes in the parabolic trough collector. Inserted fins and bulge surfaces of the inner wall of the receiver tube increase the turbulent fluid flow. In pursuance of uniform distribution of heat transfer, various fin shapes such as square-shape, circle-shape, triangle-shape, and combined square-circle shapes were inserted, examined, and compared. A study of the temperature differences and fluid flow is meaningful for this project therefore finite volume method was used to investigate heat transfer. Also, hybrid Nano-Fluid AL2O3CuO, TiO2Cu, and Ag-MgO were applied to increase thermal diffusivity. When the combined square-circle-shaped fin was inserted, the thermal peak of fluid flow in the receiver tube was lower than the other studied fin shapes by almost 1%. Besides, the hybrid nano-fluid Ag-MgO Syltherm-oil-800 has lower thermal waste in comparison to others by more than 3%.

Simulink modelling of Combined Cycle Gas Turbine (CCGT) power plant for performance analysis

A gas-fired plant and a steam-fired plant make up a combined cycle power station. The purpose of this research is to build a CCGT power plant and investigate the interaction between fuel and airflow using a simulink model. A mathematical model is used to predict how the CCGT power plant system will react. The goal of a turbine is to extract as much energy as possible from the working fluid and convert it into usable work. A large amount of heat energy from the gas turbine exhaust is wasted but has a lot of potential energy. The term total energy approach describes a system's capacity to use all of the energy at its disposal. To generate as little energy waste as possible, every watt of heat energy in a power system is supposed to be used to produce work, steam, or heat air or water. The creation of a mixed-cycle power plant is the most efficient and cost-effective way to accomplish this objective. The concept and early development of the mixed cycle were centred on the utilisation of thermal power plant waste heat. The temperature of the gas turbine exhaust can vary from 450°C to 650°C depending on the pressure ratio and turbine input temperature. It is wasteful to discard this energy into the environment. This wasted heat energy could be used to generate steam in the steam heat recovery generator (HRSG). By employing the Rankine cycle to expand the steam generated by the HRSG in a steam turbine, additional power may be created. One name for this configuration is a gas/steam mixed-cycle power plant. A gas turbine's exhaust temperature must be higher than 570°c. For the steam cycle to function properly and for the combined cycle efficiency to remain high.

ТЕРМОХИМИЧЕСКАЯ РЕКУПЕРАЦИЯ ТЕПЛОТЫ В ГАЗОТУРБИННОЙ УСТАНОВКЕ

Natural gas every year wins an increasing share in the global fuel balance. Countries where cheap natural gas is available are seeking to increase the efficiency of its use in order to increase the volume of its use. One of the most promising methods for increasing the efficiency of natural gas is the heat recovery of gas waste. The subject of the study is a gas turbine plant due to the fact that the number of power plants with gas turbines tends to increase. In this paper, options for increasing the efficiency of using natural gas in gas turbines at a constant flow rate are investigated. Variants of implementation of thermochemical heat recovery of gas wastes based on steam reforming of methane and thermal heat recovery of gas wastes based on steam generation are considered. The results of a study based on a mathematical model of a gas turbine plant using thermal and thermochemical waste gas heat recovery are presented.
 A constructive calculation of the methane steam reforming reactor has been carried out. The design and regime parameters of the heat exchanger are determined. A 3D-model of the conversion reactor has been developed, which provides high gas density and the possibility of thermal elongation of heat exchange tubes

A multi-period design method for the steam and power systems coupling solar thermal energy and waste heat recovery in refineries

It is imperative to reduce carbon emissions by comprehensively utilizing renewable energies and waste heat in refineries. However, the intermittent supply of solar thermal energy, the periodic changes of waste heat, and the variable demands of steam and electricity in refineries hinder optimal design and stable operation of the steam and power systems. In this work, an optimal design method for coordination of solar thermal energy and waste heat to produce steam and electricity in refineries was proposed, which features a multi-period mathematical programming model to synchronously determine the economy, the optimal capacity configuration, and the power scheduling scheme for the steam and power system. The influence of the serial and parallel structures of solar thermal energy supply, the model processing method for continuity of energy storage among different subperiods, and parametric analysis on the results were analyzed and discussed in detail. The results show that the cost of the solar thermal collectors and the energy storage system accounts for the significant proportion of the investment cost of the system. The cost of solar thermal collectors accounts for the largest proportion of the investment cost of the system, which is about 60% in the case study. The parallel structure of solar thermal energy supply can significantly reduce the total cost of the system. The coordination of solar thermal energy and waste heat recovery can jointly meet the steam demand to ensure the stability of the energy supply of the system. The comprehensive interactions and coordination between the solar steam generation systems, waste heat systems, energy storage systems, and demands are analyzed. The battery is necessary for short-time energy storage, whereas thermal energy storage should be used for either long-term or short-term energy storage. These results provide fundamental support for the optimal design of the steam and power systems in refineries by the comprehensive utilization of solar thermal energy and waste heat.

Carbon Dioxide Utilization Using Chlorella Microalgae

The problem of the excessive CO2 emitted into the atmosphere is one of the significant problems for the modern world and ecology. This article examines the dynamics of carbon dioxide absorption from thermal power plants, TPP, and waste gases by three types of microalgae, the most typical for the Russian Federation: Chlorella kessleri, Chlorella vulgaris, and Chlorella sorokiniana. The exhaust gases of the TPP contain up to 39% carbon dioxide. In this work, the rate of absorption of carbon dioxide from model exhaust gases with a CO2 content of up to 39% was studied. As a result of the study, a species of microalgae (Chlorella vulgaris) was identified, characterized by the maximum rate of absorption of CO2 = 0.412 g/L·day and the maximum volume of CO2 utilized in 1 day = 8.125 L. The conducted research proved the possibility of utilizing a large content (up to 39%) of carbon dioxide from the exhaust gases of the TPP with the help of microalgae of the genus Chlorella. A scheme for the utilization of CO2 with the help of microalgae is also proposed, which meets the principles of a circular economy (closed cycle).

Occurrence and formation of environmentally persistent free radicals in incineration and their impact on soil and water

Incineration is a thermal waste treatment technique that can be understood as a controlled combustion process with the primary objective of volume reduction of waste mass. Combustible waste including gaseous, aqueous, muddy, molten, and solid waste is typically deal with incineration at temperature ranges from 750 to 1200 °C. End products of incineration include a considerable amount of particulate matter (PM) and pollutants. Particulate matter released from the incineration process plays an important role in forming environmentally persistent free radicals (EPFRs) which are the most toxic and stable substance emitted from the incinerator. Other major compounds released during the incineration process are dioxins, polychlorinated biphenyls, polychlorinated naphthalene, chlorinated benzenes, and polycyclic aromatic hydrocarbons (PAH). Although incineration is significantly used to control the waste crisis but emissions of toxic substances from an incinerator have various health impacts on the environment and humans. Long exposures to these hazardous compounds lead to respiratory and cardiovascular diseases. These toxic compounds participate in various redox activities as well as metal complexation events and deteriorate the physiochemical parameter of soil and water. The aim of the present study is to summarize the existing knowledge regarding the formation of harmful compounds released during waste incineration and major environmental challenges associated with them.

Assessing the environmental impact of waste management: A comparative study of CO2 emissions with a focus on recycling and incineration

In waste management, the assessment of CO2 emissions offers the possibility to evaluate and compare the environmental impact of different waste treatment processes. Here, we compare the performance of waste incineration with alternative thermal treatment scenarios and recycling scenarios to the primary production of materials to analyze the respective CO2 emissions. The aim is to determine whether thermal and material recycling of waste results in (net) CO2 surpluses or reductions, thus, showing whether it makes sense for climate ambitions to recover waste, thermally or materially. A case study of an internationally active waste management company in Austria is analyzed, conducting a life cycle assessment of its thermal and material waste recycling. On thermal waste treatment the core of the analysis is the comparison with primary energy sources. Using waste as an energy source, especially in cement plants and the paper industry, has proven to be an effective technology for reducing CO2 emissions. We also find current practices in material recycling to be of lower CO2 emissions than alternative primary material supply. Scaling results to the national level we find that for the case of Austria current waste management practices have the potential to save an equivalent of 2.6% of Austria's total CO2 emissions (all sectors) for thermal fractions and an equivalent of 1% for material recycling.

Selection of a Multicriteria Method for Selecting Independent Variables for Forecasting the Energy Potential of Municipal Waste—A Case Study in Poland

The study examined the usefulness of selected classification methods and independent variable selection (conditional attributes) for building a model based on rough set theory (RST). The aim of the study was to estimate the local indicator of municipal waste generation and the energy potential of the waste, which could be utilized in thermal waste treatment facilities. The research was conducted on a group of 2451 municipalities in Poland which differed from each other in terms of administrative type (urban, urban–rural, and rural municipalities). These municipalities were described using 4 qualitative variables and 27 quantitative variables available in statistical reports. Using five submethods of variable classification, sets of features characterizing them in terms of the amount of municipal waste produced were extracted from the collected data. Purposeful selection of conditional attributes for modeling the unitary municipal waste accumulation index allows for reducing the number of decision variables without compromising the quality of the model. During the analysis, the number of conditional attributes was reduced from 31 to 3 for urban municipalities, 5 for urban–rural municipalities, and 7 for rural municipalities. The analysis results showed that the developed models exhibited mean absolute error (MAE) values ranging from 30 kg·(per·year)−1 to 52 kg·(per·year)−1, while the mean absolute percentage error (MAPE) ranged from 9% to 21%. By utilizing municipal waste for energy purposes, an average of approximately 160 kWh·(per·year)−1 for rural municipalities and around 270 kWh·(per·year)−1 for urban municipalities can be obtained.

Investigating mechanical and durability aspects of concrete incorporating Wollastonite and bottom ash

The use of natural resources and carbon dioxide emission is a major environmental issue, particularly in the manufacturing of cement plants where emissions are high and contribute to global warming. This has led to a need for alternative resources to decrease cement consumption. The use of natural sand in construction is also a problem due to its limited availability and high cost. The study suggests that Wollastonite, a natural mineral, and Bottom ash, thermal power plant waste, can replace cement and sand respectively in concrete. The current study aims to evaluate the mechanical properties (such as compression, flexural, and abrasion resistance) and durability property (permeability) of concrete by using Wollastonite and Bottom ash as replacements for cement and sand. Seven concrete mixes were prepared with varying levels of Wollastonite and Bottom ash replacement, and their mechanical properties were tested. The study found that replacing cement with 10% of Wollastonite and sand with 10% of Bottom ash can enhances the mechanical and durability performance of concrete. Bottom ash has the ability to be used in concrete at a particular amount to improve its qualities.

Повышение эффективности пиролизной переработки твердых коммунальных отходов

The disposal of waste by direct combustion method is prohibited in the Russian Federation due to the negative impact on the environment. An alternative option is solid waste pyrolysis technology, which allows not only to significantly reduce the amount of waste that requires disposal, but also to obtain various types of energy carriers. Existing installations allow recycling waste with humidity up to 30–35 %. An increase of humidity over 40 % requires additional energy sources for the drying process. To increase the efficiency of waste recycling by pyrolysis, it is necessary to improve the technology and to design an energy-efficient waste disposal plant. The use of the heat of combustion products in the heat exchanger to heat the air going into the drying chamber will increase the range of processing of wet waste. To determine the efficiency of the furnace for thermal waste disposal, the method of material and thermal balance is used. It allows determining the efficiency of the installation and selecting its operating mode with its maximum value. The paper proposes a new design of a waste disposal furnace with separate drying and pyrolysis chambers, as well as a mathematical model based on the equations of thermal and material balance. The design feature of the installation allows you to organize the controlled drying of wet waste and reduce losses with combustion products by using a heat exchanger for air heating. The proposed installation allows the waste recycling process to be carried out at a relative humidity of 0 to 60 % without additional energy sources. The efficiency of the waste varies from 61,5 to 80 % when the plant is operating on dry waste and from 42 to 62 % when operating on wet waste.

Business Roundup

BUSINESS Business Roundup ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2023, 101 (11), p 13April 3, 2023Cite this:C&EN 101, 11, 13AbstractLyondellBasell Industries and EEW Energy from Waste will explore a partnership to extract and recycle plastics from thermal waste streams. The arrangement could include presorting facilities at existing EEW incineration plants. SK Geo Centric plans to build an ethylene acrylic acid plant in Lianyungang, China. The plant will have 50,000 metric tons per year of capacity for the adhesive copolymer resin when it goes on line in 2028. H.I.G. Capital , a private equity firm, has sold Elekeiroz, a Brazilian maker of plasticizers and oxo alcohols, to the Brazilian specialty chemical maker Oswaldo Cruz Química. Kraton is expanding styrene-butadiene-styrene block copolymer capacity at its plant in Belpre, Ohio. The 24,000-metric-ton-per-year expansion will go on line in 2025. Evonik Industries is set to increase production capacity for its activated nickel powder catalysts by 25% via expansions at plants in Hanau, Germany, and Dombivli, India. The company says the move is aView: PDF | Full Text HTML

The role of additives in improving the flammability and calorific value of leather shavings and the binding of chromium compounds in ash

Leather processing companies are struggling with the problem of increasing costs of post-production waste disposal. Therefore, the issue of thermal waste disposal at the plant and the use of generated heat in the production process is becoming more and more popular. Leather waste on its own does not allow for autothermal combustion despite the sufficient higher heating value (HHV). Therefore the Authors proposed to improve the flammability of the fuel by adding a small amount of wood sawdust to leather waste and produce premixed pellets. Six such samples were incinerated in a laboratory-scale reactor, which enables the simultaneous measurement of characteristic temperatures, exhaust gas analysis and sample mass loss rate. Research has shown that even a small addition of sawdust enables a stable combustion process and does not cause the formation of sinters. In addition, studies of the ash showed that in the case of chromium-containing waste, a large part of it remained in the ash in the form of Cr2O3. Nevertheless, very fine ash causes the small fraction chromium to be carried with the flue gas stream, therefore controlled agglomeration of the ash structure would be advisable in the final installation. Emission analysis showed high and moderately high NOx and SO2 emissions, decreasing with the increase in the amount of sawdust addition in the sample. Research has shown that leather waste is not a burden, but can be an attractive and safe source of energy for the company, while improving waste management in a circular economy.

Physical Separation: Reuse Pollutants and Thermal Energy from Water

Conventional sewage treatment based on biological and chemical methods have made historical contributions to humans. However, it breaks the biogeochemical cycles of carbon, nitrogen, and phosphorus and cannot remove hazardous materials including viruses and nano/microplastics. Therefore, we rethought the conceptual revolution of principles of sewage treatment in the 1890s, that is, “the replacement of a philosophy that saw sewage purification as the prevention of decomposition with one that tried to facilitate the biological processes that destroy sewage naturally”. We proposed a promising sewage treatment system based on physical separation, which mainly consists of the source separators and the insoluble-pollutants separators, soluble-pollutants separators, and the wastewater heat recovery devices in wastewater treatment plants. By using the promising system, the carbon in wastewater will be recovered by sending biosolids directly into the soil after removing the hazardous materials and organic toxicity. The nitrogen and phosphorus in wastewater will be sent back into the soil or be used for hydroponics rather than be mineralized. The thermal energy in wastewater will be recovered and reused, and the hazardous materials will be removed. As a result, the promising system will turn the wastewater treatment system with high resource and thermal energy waste and high energy consumption into a no-chemicals, green factory. At present, nonetheless, it is still urgent to develop more advanced insoluble-pollutants separators and soluble-pollutants separators with high separation efficiency and low energy consumption, especially volume separators. Because the volume separators (e.g., functionalized sand filters) have the potential for replacing the surface separators (e.g., membranes).

Development and characterisation of an alginate and expanded graphite based composite for thermochemical heat storage

Thermochemical heat storage is one of the most attractive technologies to store heat from solar thermal energy or waste heat from industrial processes for its high energy density and long-term storage capability. This research presents a novel expanded graphite/alginate polymer matrix encapsulated with hydrated salts as highly efficient thermochemical heat storage materials. Through the simple synthesis method, the composite material can be sized and shaped to fit multiple applications, and be easily scaled where needed. Through the reversible hydration and dehydration reaction, the incorporated CaCl2 salt can store and release heat. Thermal energy from solar thermal generators or low grade waste heat sources (< 200 °C) is appropriate for the dehydration of CaCl2. A salt loading value of 84% has been achieved with visible porosity maintained. Static heat is used to study the charge reaction, whereas a flow of humid air through a packed bed is used to study the discharge reaction where temperature uplifts between 10–14 °C were observed. A vermiculite/CaCl2 composite is used as a comparison in both reactions. Additionally, bulk density, surface porosity, surface area, moisture sorption and thermal conductivity are considered. The results show that the novel composite materials developed in this study can achieve better packing density and comparable energy density comparing to the conventional vermiculite/CaCl2 composite, but with higher thermal conductivity leading to enhanced energy efficiency.Graphical

A Review on Research and Technology Development of Green Hydrogen Energy Systems with Thermal Management and Heat Recovery

This paper presents a review of recent research and development progress on green hydrogen energy systems and associated thermal management and waste heat recovery technologies. First, hydrogen production methods are briefed. Second, various electrolysis systems used for carbon free hydrogen production from renewable and nuclear resources are discussed. Then, hydrogen utilization using proton-exchange fuel cells is scrutinized. Next, hydrogen energy systems integrated with metal hydride energy storage are elaborated. A focus of this review is on thermal management and process intensification technologies for hydrogen energy systems and integrated metal hydride hydrogen storage technologies. Various process and heat transfer enhancement techniques for heat removal and utilization are presented. Advanced cooling technologies for hydrogen energy systems such as two-phase and boiling for cooling, microchannels for heat removal, CO2 air conditioner and using nanofluids for heat removal are discussed. Finally, heat recovery technologies in green hydrogen energy systems are summarized. This review has also identified future research and technology development needs for green hydrogen energy utilization, thermal management, and heat recovery systems.

Determination of the fuel composition during operation to optimise the combustion behaviour

Waste as fuel in thermal waste treatment is characterised by a heterogeneous and fluctuating composition. In addition to familiar fractions such as paper, plastics and textiles, new fractions are appearing. Materials such as composites and insulating materials, carbon fibre-reinforced plastics and electrical waste have problematic properties from an incineration point of view. If the composition of the fuel mixture is available, however, these can be counteracted.For the inline determination of the waste composition a calculation method consisting of two sequential models was developed. First, the extended online balancing allows to calculate the elementary waste composition (C, H, O), the water and ash content, lower calorific value and mass flow of the waste. Afterwards these results can be used in the so-called numerical fraction model to determine the fractional composition.Theoretical validation has already proven that the model delivers reliable results in wide areas. First results of the experimental validation of the models are presented in this paper. For the investigations, synthetic fuel mixtures were produced from several mono-fractions and burnt on the backward acting grate of a grate firing pilot plant. The recorded measurement data, such as the flue gas composition and the volumetric flows of flue gas and supply air, is used as input data for the models. For validation, a comparison with the composition known from fuel analyses was made.