Thermochemical Treatment Process Research Articles

Enhancing the processes of thermochemical treatment of oil

Enhancing the processes of thermochemical treatment of oil

Development of Carbonization and a Relatively High-Temperature Halogenation Process for the Removal of Radionuclides from Spent Ion Exchange Resins

This study investigated a two-step thermochemical treatment process consisting of carbonization and halogenation for the removal of radionuclides from spent cation-exchange resin (CER). Based on a thermal analysis of cation-exchange resins, we propose a two-step thermochemical treatment process involving the conversion of spent CER into pyrocarbon and then the removal of radioactive elements from the carbonized CER by converting them volatile halides at very high temperatures. The proposed process mainly consists of a carbonization and halogenation reactor, a UHC (unburned hydrocarbon) combustor, and wet scrubber. A step-by-step experimental and numerical optimization study was conducted with the carbonization and halogenation reactor and the UHC combustor. The optimum operating conditions could be established based on the results of a thermal analysis of the CER, a nonisothermal kinetic analysis, a numerical modeling study of a plug flow reactor (PFR)-type combustor, and a thermodynamic equilibrium analysis of a system consisting of a mix of carbonized CER and halogenation gas. The results of this study present detailed design of a novel multifunctional reactor and operating conditions of a bench-scale carbonization and halogenation process. Basic performance tests using CER doped with nonradioactive Co and Cs, indicated as Cs-137/134 and Co-60/58, were conducted under the optimized conditions. The results of these tests showed that the novel thermochemical process proposed in this study is a viable process that effectively removes radioactive elements from spent CER.

Thermo-Chemical Treatment for Carcass Disposal and the Application of Treated Carcass as Compost

A mechanized thermo-chemical treatment system was developed to treat the undecomposed carcass and remediate livestock burial sites. Animal carcasses were thus processed via crushing, mixing, and treatment with quicklime treatment, heat treatment (200–500 °C), and mixing with sawdust. The machinery was applied to two sites where 16,000 chickens and 418 pigs had previously been buried in fiber-reinforced plastic storage bins. No dioxins were detected in the gas discharged during processing, and the concentration of total volatile organic compound, toluene, ethylbenzene, xylene, and styrene were 430.3, 139.0, 18.3, 21.4, and 10.4 μg/m3, respectively, which were below the air pollutant emission standards issued by the Korean Ministry of Environment. Korean standards stipulating the use of treated carcasses as compost (C, N, and P content, heavy metal concentration, Escherichia coli, and Salmonella) were met, but the germination index value was less than 70, not satisfying the criteria. Plant height, leaf length, leaf width, and dry weight of lettuce grown in soil amended with treated carcass product were significantly lower than those grown in low nutrient soil due to the poor germination index of the treated carcass. These results indicate that a composting process is required before the use of the treated carcass as a fertilizer. The addition of zeolite retarded the elution of ammonia from the carcasses and its efficiency was about 87.9%. It is expected that the mechanized thermo-chemical treatment process developed in this study could replace other technologies for the remediation of livestock burial sites.

Modelling of the cylindrical geometry cooling process based on the solution of the inverse problem

Processes of thermo-chemical treatment, such as nitriding, are used to create a surface layer of high mechanical values. When the nitriding process, often consisting of a multi-stage heating and soaking, is ended, elements being under treatment are cooled. The cooling rate depends on the massiveness and geometry of the given element. Too fast cooling can result in the formation of high temperature gradients, which leads to the element damage. This paper presents numerical analysis of a cylinder cooling. The non-linear, unsteady inverse problem for the heat equation was solved. Test examples were chosen based on experimental research conducted in the furnace for thermo-chemical treatment.

Comparative Analysis of the Behaviour of Marine Litter in Thermochemical Waste Treatment Processes

Plastic in the ocean, especially plastic on the ocean surface is not only researched intensively but also photos and reports rise awareness of the challenge in the general public. While research is concerned with the fate of marine litter in the environment, recycling of these materials after collection is rarely addressed, mainly because there is neither considerable data on composition nor a suggested process to do so. This study is the first to analyse and evaluate chemical recycling (pyrolysis, gasification) and energy recovery (incineration) of marine litter. Two heterogenous marine litter samples from Sylt and Norderney, North Sea, Germany, were analysed, consisting of six different material groups. Agricultural mulch foil was used as reference material. The thermochemical treatment processes were reproduced by thermogravimetric analysis. Furthermore, pyrolysis trials on a semi-technical scale were conducted and the residues were analysed by proximate, ultimate and X-ray fluorescence analysis. The results indicate that heterogeneous and weathered material mixtures can be treated by thermochemical processes. Finally, the pyrolysis condensates are discussed as substrate for biotechnological upcycling. In summary, we present a comprehensive approach from the material characterisation of marine litter to the analysis of three different thermochemical treatment processes and the possibility to use the generated pyrolysis condensate for subsequent upcycling. The data collected form the basis for the evaluation and application of possible treatment options for the collected marine litter.

Влияние механоактивации порошковой смеси на структуру и свойства бороалитированных малоуглеродистых сталей

Introduction. Boro-aluminizing is one of the most effective ways to improve the performance properties (corrosion resistance, heat and wear resistance) of low-carbon steels. Solid-phase methods of thermochemical treatment (TCT) are carried out from saturating mixtures based on powder materials. Preliminary mechanical activation of these powders is one of the ways to improve the properties of the resulting diffusion layer. The purpose of this work is to determine the effect of preliminary mechanical activation of the powder mixture on the structure and properties of the boro-aluminized layer on the surface of low-carbon steels. Methods: The paper considers the results of research on the preliminary mechanical activation of the saturating mixture in the TCT of low-carbon steels (for example, St3 and 3Kh2V8F) based on powdered boron and aluminum carbide. The results of experiments on preliminary mechanical activation of the saturating mixture are shown, and the dependence of the particle size of the initial mixture on the duration of mechanical activation is established. Samples of steels with a diffusion layer after TCT are obtained. It is found that the process temperature has a significant effect on the thickness of the layers obtained. With an increase in temperature from 950 ° C to 1050 ° C on St3 steel samples, the layer thickness increases from 120 to 150 μm, on 3Kh2V8F steel samples – 105 and 140 μm with a holding time of 2 h and 4 h, respectively. The microstructure of the obtained samples is investigated; dependence diagrams of the microhardness distribution on the depth of diffusion layers are shown. The distribution of Al over the depth of the resulting boro-aluminized layer is established. As additional studies, the saturation capacity of the mixture after a single application in the TCT process is studied. Results and discussions. The principal possibility of using mechanical activation in TCT to obtain diffusion layers with specified strength characteristics is established. An increase in the duration and temperature of TCT in mechanically activated mixtures leads to an increase in the aluminum content in the layer.

ЗАДАЧИ УПРАВЛЕНИЯ ПРОЦЕССОВ ДИНАМИЧЕСКОГО ОТСТОЯ НЕФТЯНОЙ ЭМУЛЬСИИ

A systematic analysis of the state of the art in the methods for enhancing processes of thermochemical treatment of oil is carried out. A new method and a new system for controlling the process of dynamic settling of oil emulsion (OE) is developed, which allows increasing the efficiency of managing the process of dynamic settling by more accurately measuring the degree of phase separation, while avoiding the process of “flooding”. The mechanism of formation of an electrical double layer around emulsified water droplets (EWD) and the interaction energy of these droplets as a distance function is shown. An adequate mathematical model of hindered settling of EWD is proposed. It is shown that OE and intermediate emulsion layer (IEL) can be broken down by using microwave radiation. By virtue of this, the authors develop a new method, algorithm and system for automatic measurement of the water cushion level and the thickness of the İEL in settlers based on measuring the optical density of oil.

Life cycle and End-of-Life management options in the footwear industry: A review.

It is well recognized globally that the footwear industry contributes to a large waste stream throughout its life cycle. This article reviews the literature pertaining to the life cycle of footwear products and their End-of-Life (EoL) management strategies. The review discusses critical aspects of the footwear industry, commencing with a background on the growth and consumption of footwear products across the globe. The review provides an overview of the environmental impacts of different footwear materials across their life cycles. In this regard, leather materials are given intense focus due to their poor environmental performance. The review further examines proactive and reactive approaches to footwear waste management, whilst additionally exploring the challenges facing EoL footwear recovery. Finally, pyrolysis is examined as a thermochemical treatment process with value due to its potential to recover materials from post-consumer footwear. The significant findings in this review paper are as follows: (a) leather footwear materials have the most detrimental environmental impacts across their life cycle; (b) there is limited scientific literature on thermochemical processes (particularly pyrolysis) as waste recovery options for post-consumer footwear; and (c) several challenges face the recovery of post-consumer footwear products, including inefficient reverse logistics, mixed product recycling and difficulties establishing a value recovery chain. This review paper recommends further research on pyrolysis as a potential post-consumer footwear recovery option. Exploring the viability of new avenues for footwear waste recovery is significant due to its potential to divert this waste stream from landfills and allow a progression toward a more circular economy.

Resource-saving optimal control of energy-intensive process of work part thermochemical treatment

Paper discusses approach to the resource-saving optimal control algorithms development, which includes problem oriented mathematical modeling of the process, determination of the tolerance limits for controlling action changes and condition of thermochemical treatment process as a subject under control, optimality criteria formalization and determination. Specified and solved critical problems for resource-saving optimal control of energy-intensive thermochemical process of work parts treatment on the maximum accuracy and speed of operation criteria. Alternance optimization method was used for optimal control problems solution, which allows to determine not only interval of constancy size but also maximum achievable control accuracy in every subset of intervals. Analytical mathematical model of vacuum carburizing in an acetylene atmosphere with variable coefficients of mass transfer was developed, which takes into consideration different mechanisms of carbon mass transfer from the atmosphere into the work part surfaces at the saturation and diffusion stages. Dependences of the carburization accuracy on the optimal control parameters were constructed. Influence of the technological constraints on the control quality was analyzed. Suggested approach demonstrated high energy efficiency.

Impervious and influence in the liquid fuel production from municipal plastic waste through thermo-chemical biomass conversion technologies - A review

Plastic waste is an environmental burden substance, which poses a high threat to the society during disposal. Rather than disposal, recycling of this waste to liquid fuel gains importance owing to its high utility. Among various techniques, thermo-chemical recycling techniques hold more benefits in generating high value added liquid fuels. In this review, the details of municipal plastic waste generation are provided with a brief description of the plastic waste management option and importance of recycling is explained. The overview of the thermo-chemical treatment focusing on the pyrolysis, gasification and hydrocracking process was elaborated. Catalysts mediated pyrolysis have wide-open their prospective for the generation of bio-oil, hydrocarbons, syngas and deterioration of undesired substances. Generally, advance development of enthusiastic catalysts for the synthesis of bio-oil would be vital for scaling up the pyrolysis process to succeed in commercial manufacture of biofuels from waste plastics. Overall rate treatment depends on operating parameter which determines the process efficiency and product yield. Hence, critical assessment of various parameter that has remarkable effect in the thermo-chemical treatment process was documented in detail. Moreover, endorsements of liquid fuel production, economic viability, and energy requirement of the treatment process, were delivered to attain effectual plastic wastes management.

Развитие математических моделей пластических сред для ресурсосберегающих технологий металлических систем

Развитие техники выдвигает более сложные задачи, эффективное решение которыхсвязано с уточнением математических моделей изучаемых процессов пластического формоизменения металлических систем (металлов, сталей, цветных сплавов) различных химических составов и технологий получения (традиционный слитковый передел, порошковое производство, наноструктурные материалы). Для построения решения используется интегрирование дифференциальных уравнений, описывающих физические процессы, происходящие при пластическом течении или вариационный подход, основанный на построении исходного функционала, но в том и другом случае точность математического моделирования процесса будет зависеть от принятой математической модели среды. В работе рассмотрены этапы развития различных моделей пластических сред, от простейшей жесткопластической модели, не учитывающей изменение свойств материала, к более сложным – вязко пластической модели, учитывающей появление вязкости при повышении температуры обработки и дилатирующей модели, которая позволяет учитывать изменение плотности материала и тем самым прогнозировать деформационное разрушение. Правильное использование математических моделей пластических сред дает возможность повысить точность расчета технологических режимов, сокращая тем самым время на освоение выпуска новой продукции и может быть применено для разработки технологических процессов получения изделий методами аддитивных технологий на основе лазерного спекания и сплавленияпорошковых сплавов, технологий термопластической обработки и процессов упрочняющейхимико-термической и термической обработок металлических систем различных химических составов.

S-Phase Layer Development on 316 LVM Using Low Temperature Hybrid Thermochemical Treatment Process

This investigation focuses on the improvement of surface properties of medical grade austenitic stainless steel (AISI 316LVM). The aim is to develop a homogenous supersaturated hard layer of expanded austenite (s-phase) at the surface of AISI 316LVM using low temperature hybrid thermochemical heat treatment process. The s-phase layer produced by this process is able to improve the surface properties of AISI 316LVM, overcoming its drawback of low surface hardness and wear resistance, without impairing the corrosion resistance of the steel. During the heat treatment process, ammonia (NH3) and methane (CH4) gasses were introduced into the furnace with temperatures of 425°C and 475°C, at 6 and 12 hours with gas composition of 75% of NH3, 10% of CH4, and 15% of Nitrogen (N2). Characterization on the microstructure showed the formation of the S-phase layer with variation of thickness according to parameters used. The S-phase formation was confirmed with phase analysis using XRD. Besides, the surface hardness also significantly increased from 210.9 HV to 1170.0 HV. In conclusion, low temperature hybrid heat treatment process is able to produce a homogenous hard s-phase layer.

Analysis of the heat transfer for processes of the cylinder heating in the heat-treating furnace on the basis of solving the inverse problem

This paper presents results of experimental test concerning heating of a cylinder in the furnace for heat and thermochemical treatment. Tests were conducted for heating up to temperature of 550 °C, what corresponds to nitriding processes. Calculation model including Chebyshev polynomials enabling determination of temperature distribution in the cylinder is presented.Two variants of calculation model were examined; they differ in terms of the assumed boundary condition. Analysis of regularization of the solution to the inverse problem done by the change of time step (self-regularization) was made. Based on the solution of the non-linear inverse problem for the heat equation and on the gas temperature measurement read from the furnace retort, temperature distributions on the boundary of the cylinder, combined radiation convection heat transfer coefficients (CHTC) and heat flux on the surface of the cylinder were calculated. Due to a great variability of temperature for the processes under consideration, the calculation model includes the variation of the heat conduction coefficient and of the specific heat of the material the cylinder is made of depending on temperature change. Five heating processes differing in parameters of heating rate were analysed. Impact of measurement errors on distributions of temperature on the edge of the cylinder and of the CHTC was determined. Obtained temperature distributions in the element were verified by a check measurement. Maximal error of the obtained results did not exceed 0.5%. Data presented herein give practical knowledge enabling supervising the temperature distribution in the cylindrical element being processed. These problems are of crucial meaning for processes of heat and thermochemical treatment due to formation of proper surface and subsurface layers.

Identification of thermochemical pathways for the energy and nutrient recovery from digested sludge in wastewater treatment plants

Abstract There are several restrictions and limitations on the emissions and disposal of materials and pollutants related to wastewater treatment plants (WWTPs) emphasizing improvement of current processes and development of new methods. Process integration is one way to use all fractions of waste for improved efficiency. WWTPs produces sludge which is usually anaerobically digested to produce biogas and a byproduct called digestate. Digestate is an organic material that contains macro and micronutrients such as nitrogen, phosphorous, and potassium and also contains heavy metals. Digestate is mainly used for agricultural applications because of the presence of nutrients. However, digestate also contains energy in the form of carbon and hydrogen which can be harnessed through various processes and integrated with nitrogen recovery process. This study aims to recover the energy and nutrients from digestate through thermochemical treatment processes. Combustion, pyrolysis, and gasification are assessed and compared in this work. An ammonia stripping method is assumed to recover nitrogen from digestate. The thermochemical processes are heat integrated with ammonia stripping through modeling and simulation. Results show that almost half of the energy present in digested sludge is required for its drying. Moreover, nitrogen recovery also requires much energy. The combustion and gasification of digested sludge give better results than pyrolysis. The heat integration becomes feasible when the auxiliary biogas is also burned along with products from the thermochemical treatment of sludge.

A Versatile Converter of Liquid Hydrocarbons for the Production of Reducing and Carbonization Atmospheres

Abstract We herein report the results of our investigation into the modes of catalytic partial oxidation (CPOX) of liquid fuels and air mixtures to yield endothermic (endo) gas on a pilot-scale installation containing ~ 0.45 cm3 catalytic bed. This endothermic gas serves as a protective atmosphere in thermochemical steel treatment processes. Seven liquid hydrocarbons (LHs) are investigated, namely isooctane, 91 RON (research octane number) and 95 RON gasoline, diesel, kerosene, jet fuel, and naphtha. All experiments are performed using our previously developed reactor, where the reactions of natural gas/air mixtures were previously studied. In the present study, we report that the LH conversion products reached an equilibrium state similar to that of methane and natural gas conversion with an atomic C/O ratio of ~ 1.0 in the mixture. Furthermore, working regimes between 850 and 950 °C are examined as typical reaction conditions for industrial endo gas generators, and in all cases, the required gas quality is achieved. However, we found that gasoline and diesel are the most suitable LH feedstock for endo gas generation.

EVALUATION OF THE MECHANICAL PROPERTIES OF DIFFUSION LAYER IN THE PROCESS OF MICROARC STEEL VANADATION

Traditional processes of thermochemical treatment of steel have a longer duration, so there are proposed the new methods of intensification of diffusion saturation with high-energy impacts on the material surface. In the process of micro-arc alloying the steel product is immersed in a container filled with powder of coal, and is heated by passing electric current. In a powder environment, microdischarges are formed, which are concentrated around the product and create an area of gas discharge with the formation of a carbonaceous gas environment, which enables carburizing of steel. The application of coating containing diffusant allows forming coating of a carbide type due to simultaneous carbon diffusion into alloying elements. The influence of micro-arc surface alloying of steel with vanadium on mechanical properties of diffusion coatings is studied, and the primary mechanism of steel hardening at microarc alloying is revealed. Cylindrical samples of 20 steel were used; the source diffusant was a powder of ferrovanadium. Current density on the sample surface was 0.3 A/cm2, total duration of the process was 3 min. The mechanical properties of coatings were evaluated by means of indentation using pyramidal indenter, at loads of 2.5 mN, 20 mN and 100mN. The diffusion layer with thickness of 170 – 180 μm consists of a base with hardness of 8 – 9 GPa, containing mild etching inclusions of up to 5 μm with microhardness of 21 – 25 GPa. The base of the layer represents an α-solid solution of vanadium in iron, and inclusions are carbides of VC0.863 type. By atomic force microscopy it was established, that the surface relief is defined by single, relatively large carbide particles with a size of up to 3 μm, and by plural nano-sized carbide particles, which act as the strengthening phase, providing high microhardness of the coating. By method of indentation of the hardened layer cross section using different loads hardening effect of the carbide particles is proven. Estimation of possible mechanisms of hardening have shown that the greatest contribution to diffusion layer hardening is made by dispersion component significantly increasing the yield stress of α-solid solution of iron in comparison with the initial state, which is 38 times greater than the contribution of solid-solution hardening.

Hydrothermal Carbonization of Biosolids from Waste Water Treatment Plant

The high moisture content of biosolid from a wastewater treatment plant limits its use for agriculture and energy applications. This limitation could be obviated by hydrothermal carbonization, which requires less energy compared to other thermochemical treatment processes, and results in stabilized solid hydrochar product. The present study examined this option by hydrothermally treating the biosolid at three temperatures (180, 200 and 220 °C) for 30 min, and at 200 °C for 15, 30 and 60 min. An increase of 50% in the heating value of the biosolid was obtained after this carbonization. A reduction in the nitrogen concentration in hydrochar was noted with an increase in phosphorus concentration, but potassium concentration remained largely unchanged. Additionally, the carbon to nitrogen ratio in the hydrochar product was higher than the biosolid that makes it suitable for agriculture applications. The chemical oxygen demand of the process water was in the range of 83,000 to 96,000 mg/L. The study thus provides insight into high-value products that can be generated by the hydrothermal carbonization of biosolids.

Modeling of Emulsion Formation and Breaking in Thermochemical Oil Treatment Process

Nanotechnology comprises oil treatment processes because they occur on the nano-scale and involve interaction of charged mono- and polyvalent ions found in the interacting oil and reservoir water A mathematical model for thermochemical dehydration of oil is proposed considering the specific features (nano-scale effects) of oil emulsion formation and breaking. Procedures for estimating the effectiveness of the intermediate emulsion layer and analytical expressions for determining the residence time of oil emulsions in settlers of thermochemical oil treatment facilities are proposed.

Impact of Two Hydrothermal Carbonization Filtrates on Soil Greenhouse Production

Hydrothermal carbonization (HTC) is a thermochemical treatment process that allows for the conversion of wet biomass slurries to new liquid and solid products. A majority of the research to date has focused on the solid HTC product (hydrochar). Less attention has been paid to the utilization of the HTC filtrate, which comprises the larger mass fraction of the process.

Methods of data mining for modelling of low-pressure heat treatment

Purpose: This paper addresses the methods of the modelling of thermal and thermochemical processes used in computer-aided design, optimization and control of processes of thermal and thermochemical treatment in terms of obtaining real-time results of the calculations, which allows for observation of how an item changes during its treatment to respond immediately and to determine the parameters of a corrective process should any irregularities be detected. The main goal of the literature review was to develop a methodology for the design of functional and effective low-pressure processes of thermal and thermochemical treatments using effective calculation methods. Design/methodology/approach: A detailed analysis was conducted regarding the modelling methods with low-pressure carburizing and low-pressure nitriding. Findings: It was found the following criteria of methods selection of heat treatment modelling should be applied: data quality, data quantity, implementation speed, expected relationship complexity, economic and rational factors. Practical implications: Because of its non-equilibrium nature and transient states in the course of the processes computational support is particularly required in low-pressure thermochemical treatments. The primary goal of the simulation is to predict the course of the process and the final properties of the product, what ensures the repeatability of the process results. Originality/value: It was presented a synthetic presentation of modelling methods, in particular methods of artificial intelligence; it was also analysed the possibilities and risks associated with methods.