Calcination Furnace Research Articles

ASH CONTENT IN SEEDS OF SOME INDUSTRIAL HEMP GENOTYPES

The study analyzed the ash content in the seeds of several hemp genotypes for fiber. The experiment took place within ARDS Lovrin. The biological material was represented by six genotypes of hemp for fiber (FHG), noted in the study FHG1 to FHG6. The seeds were harvested at physiological maturity. From the seed samples of each genotype, laboratory samples were taken to determine the ash content (Ash, %). Ash was determined by calcination (Nabertherm B180 calcination furnace) at 550 °C for 5 hours. The ash content, average values, varied between 3.30±0.33% (FHG1) and 7.05±0.33% (FHG4). The data series for the ash content, average values, presented a normal distribution, according to r = 0.966. Differences between genotypes were registered, under statistical safety conditions at the level of p<0.05 (*) in the case of the FHG4 genotype compared to the FHG6 genotype, and at the level of p<0.001 (***) in the case of the other genotypes. An exception was registered in the case of FHG3 and FHG5 genotypes, where the differences did not show statistical certainty (p = 1.000). In relation to the average at the level of the experiment (Ash_m = 5.07%), positive differences were presented by the genotype FHG4 DAsh = 1.98%, and the genotype FHG6 DAsh = 1.53%. The cluster analysis facilitated obtaining the dendrogram in which the hemp genotypes were associated based on similarity, in relation to the ash content values ​​(Coph.corr. = 0.868). A cluster included genotypes FHG4 and FHG6, which recorded ash content values ​​above the average of the experiment, with the SDI level = 0.450.

Reactivity of Calcined Clays as SCM-A Review.

Calcined mixed clays are one of the most promising alternative supplementary cementitious materials. However, their standardized use is difficult due to the wide range of compositions of the raw materials. The reactivity potential of different clays can hardly be estimated on the basis of simple characteristics so far. This review aims to identify and compile the factors that determine reactivity. At first, an overview of the methods to evaluate reactivity is presented in order to provide a definition of this term. Subsequently, the reactivity-determining factors are compiled and subdivided into the characteristics of the raw material (chemical and mineralogical composition), the parameters of calcination (furnace type, temperature, grain size, retention time, and cooling), and the characteristics of the calcined material (physical properties and amorphous phase). Interrelations are discussed qualitatively. In the second step, a quantitative literature analysis was conducted to quantify correlations between the different factors and reactivity. However, since the characterization methods in the literature are very different, the data can hardly be analyzed quantitatively. Consequently, this paper points out what information is needed to conduct profound, comparable studies to evaluate the reactivity potential of clays.

Development of a spray dryer’s mathematical model for control tasks

The sustainable development paradigm includes the most efficient material and energy resources using in production processes. One of the ways to achieve this goal is creating the effective automated control systems. At the same time, such systems effective functioning is impossible without adequate mathematical models for control objects. Thus, the actual task of this study is to create the control object – a spray dryer -model-, which could be used in the control system.
 It was established that one of the main devices in the sodium tripolyphosphate production is a spray dryer in which the aqueous salts suspension is dried by flue gases. The obtained powdery product which is fed into the calcination furnace. The work investigated convective drying, where the material is in direct contact with the drying agent – furnace gas. To drying process control by the drying agent temperature.
 The existing works analysis showed that the mathematical model developing process of a spray dryer requires in-depth research into the physical nature of processes which taking object's operation’s various factors into account. The object presentation can be carried out with different approaches taking into account various important production factors, but at the same time it should be as close as possible to the nature of process. The development of the spray drying process model is carried out for regulation the moisture at the finished product.
 The beginning of the research is the structural and parametric diagram creation of a spray dryer taking into account all input and output values which allow to determine the control disturbance channels. A material balance based on the moisture and loose matter amount and a gas environment heat balance is compiled. The transfer functions component calculation is carried out using the Kramer method. 
 The presented results of the research make it possible to build and analyse the spray dryer mathematical model taking into account the requirements for the substance moisture content be dried and the control process analysis by the drying agent temperature changing. The transient characteristics of the spray dryer by the disturbance and control channels, which are calculated and presented in the research make it possible to compare the control object behaviour with and without taking heat loss into the environment the assumptions into account.

Mixtures of heavy fuel oil and green hydrogen in combustion equipment: Energy analysis, emission estimates, and economic prospects

The high environmental impact of fossil fuels combined with the rise of carbon dioxide in the atmosphere has made the search for renewable fuels imperative. The study assesses the technical and economic viability of replacing heavy fuel oil (HFO) with green hydrogen (H2) in industrial plants for high temperature generation (>1100 K). The study also estimates the emissions generated by the plants after the fuel switch in terms of particulate matter (PM), SO2, NOx and CO2 emissions. To illustrate the feasibility of this replacement, an assessment of a calcination furnace at a pulp plant in Chile in 2022 was carried out, taking into account two electricity generation scenarios for H2 production by water electrolysis. Replacing HFO with a mixture of H2 + HFO was beneficial in terms of emissions. The financial assessment showed that blending H2 with HFO of up to 20 % is the best solution, considering current fuel prices, and that full substitution of HFO with H2 after 2030 is economically viable.

Counterflow step-type bulk material cooler

Counterflow cooling is extensively used in many industries to recover the heat from hot materials coming out of kiln. The method for calculating a counterflow step-type bulk material cooler is proposed. It is based on a matrix model of heat balance for individual cooling stages. The proposed equation system allows calculating the required number of steps and airing flow rate. The method was used to design a cyclone heat exchanger for an alumina calcination furnace and a counterflow louvered proppant cooler. It allows taking into account the degree of heat transfer incompleteness at individual stages and minimizing air flow for cooling. Examples of industrial introduction are given. The applicability of the method for counterflow heaters calculating is noted. On the basis of the offered method, step counterflow coolers with louvers were developed and introduced. Such devices and calculation methods can be used to heat the material before being fed into the furnace. The use of step-type counterflow heat exchanger makes it possible to utilize the heat of bulk material leaving the furnace and the heat of exhaust gases.

Framework for Monitoring and Control of the Production of Calcined Kaolin

In response to the growing demand for sustainable products and services, the kaolin calcination industry is developing practices that optimise the use of resources. The main challenges include more efficient use of raw materials and a reduction in the energy consumed by the calcination furnace. An opportunity to achieve this lies in the optimisation of the calcination process. This can be done by giving real-time feedback on the quality parameters of the generated calcined kaolin. This study proposes the use of infrared spectroscopy as a monitoring technique to determine the chemical properties of the calcined kaolin product. The basis of the monitoring system is the measurement of the kaolin soluble alumina content as one of the most important quality parameters; this property is an indicator of the over- or under-use of raw materials and energy during the calcination process and can advise the operations regarding the optimisation of the working conditions of the furnace. The implementation of an infrared-based monitoring system would lead to increased efficiency in the production of calcined kaolin.

Solids Flow in a “Particle-in-Tube” Concentrated Solar Heat Absorber

Fluidized particle-in-tube solar absorbers are increasingly investigated both as receivers in a solar power concept or as a receiver/reactor for the thermal decomposition of minerals or for gas–solid reactions such as CO₂ looping concepts and thermo-chemical energy storage. Such applications require a high heat transfer rate from the tube wall to the upflowing suspension of particles and a strict control of the particle residence time. Conversion and heat transfer depend upon the particle mixing, its residence time (RT), and residence time distribution (RTD). Both parameters are hence important in fluidized bed applications. The present research experimentally investigated the use of an Upflow Bubbling Fluidized Bed (UBFB) as a particle-in-tube concentrated solar receiver and/or reactor. The RTD was determined by tracer response and compared with predictions from different models. Both a cascade of stirred tank reactors and a plug flow with dispersion model provide a good fitting of the experimental results. The former is however preferred, with a number of cascade mixing cells between 3 and 4, slightly dependent on both the operating air velocity and the particle circulation rate. The commonly applied ratio of the superficial fluidization velocity and the minimum fluidization velocity of the particles is between 3 and 20, whereas solid circulation fluxes up to 100 kg/m² s are used. Design equations are derived. The results are moreover used in test cases of a concentrated solar power absorber and in the use of a UBFB as solar limestone calcination furnace. The approach can also be applied to processes of, for example, heat absorption or drying provided kinetic data are known.

石灰焼成炉内での廃プラスチックと廃木材の混合ペレットの燃焼性評価

廃プラスチックペレットは，石灰焼成炉において使用されるCOG（コークス炉ガス）の重要な代替燃料の一つである。しかし，廃プラスチックの発生量には限りがある。そこで，廃木材を利用する可能性について検討し，廃プラスチックと廃木材を混合したペレットを開発した。ペレットの燃焼性を明らかにするためラボスケールの試験を実施し，さらに実機の石灰焼成炉への吹込み試験を実施した。廃木材を重量比で10，20，30％混合したペレット（直径6 mm）の燃焼時間は，1000℃において，いずれも約25秒であった。この燃焼時間は，従来から使用している廃プラスチック単独のペレットの燃焼時間と同等であった。次に，廃木材を重量比で10％混合したペレットを実機の石灰焼成炉に吹込んだ。このとき，コークス炉ガスと混合ペレットの両方を吹込んで操業した際に必要であった投入熱量は，コークス炉ガス単独で操業したときの投入熱量と比較して5％減少した。この結果は，従来から使用している廃プラスチック単独のペレットと同様であった。この効果は，ペレットが石灰焼成炉の中の石灰石の近傍で燃焼したことによりもたらされた。これらの結果は，廃木材を重量比で10％混合したペレットが，従来から使用している廃プラスチック単独のペレットと同様にCOGの代替燃料として利用可能であることを示している。

Study of pozzolanic activity of bamboo stem ashes for use as partial replacement of cement

Studies of the use of agricultural wastes or natural resources as cement replacements have increased in recent years. The evaluation of their pozzolanic activity is essential to predict the behavior of modified cementitious materials elaborated with these resources. This work presents a study of the pozzolanic activity of bamboo stem ashes, which were obtained by calcining bamboo stem at 600 °C for 3 h in a calcination furnace. Several methods such as Chapelle test, saturated lime method, thermogravimetric analysis and strength activity index were proposed to evaluate the pozzolanic activity. The results of X-ray fluorescence and X-ray diffraction indicate that bamboo stem ashes are mainly composed of Silica (SiO2) with an amorphous phase. The Chapelle test and the saturated lime method showed the pozzolanic activity of bamboo stem ashes. Finally, at 7 and 28 days, mortars containing 10 % by weight of bamboo stem ashes show a strength activity index greater than 75 % as recommended by ASTM C618.

Cyclone Calcination Furnace

Russia’s first cyclone calcination furnace, with a capacity of 500 tons/day, was built and placed in operation at the Ural Aluminum Plant of the Siberia-Ural Aluminum Company (in Kamensk-Ural’skii). The cyclone furnace took the place of rotary furnace No. 6 in March 2004. Operation of the furnace has shown that it offers the following advantages: a reduction in fuel consumption by a factor of 1.5; a 40% decrease in the emission of hazardous substances; the production of silica with a low (from 5 to 7%) content of the α-phase; an increase in the utilization factor from 0.82 to 0.973; low unit fuel consumption—95.9 kg/ton alumina. The furnace has now been in operation for 10 years without replacement of the lining or major repairs. Its successful use and cost-effectiveness (the capital investment was recouped in 2.5 years) show the need to replace the existing stock of inefficient and worn-out rotary furnaces used for the production of alumina.

Enhanced Coercivity of CaLaCo‐Doped SrM Hexaferrites by Microwave‐Calcination Technique

The effects of microwave calcination (MC) and conventional muffle furnace calcination (CC) on the microstructure and magnetic properties of M‐type hexagonal ferrite Ca0.15La0.39Sr0.46Fe11.7Co0.3O19 were investigated. The phase composition, microstructure, and magnetic properties of calcined materials were examined using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry. Experiments indicated that the MC method can achieve both pure phase, and fine and uniform grains for both calcined and sintered M‐type hexaferrites. MC treatments resulted in a magnetization at 15 kOe of 67 emu/g and an increase in coercivity by 12% over the CC technique. The improved magnetic properties resulting from microwave‐assisted calcination were attributed to the formation of a fine‐grained morphology, which yielded a narrow grain size distribution. The microwave calcinating technique was shown here to possess unique potential for fabrication of high‐performance ferrites and possibly other ceramics.

Modeling of the behavior of liquid radwastes in a rotary calcination furnace

A rotary calcination furnace is used at the first stage of a two-stage facility for immobilizing liquid radwastes and comprises a heated rotary tube inclined at a small angle with respect to the horizontal plane. As they move along the furnace, the wastes fed into it are heated, the liquid phase evaporates, and the solid phase remaining after evaporation undergoes chemical changes (calcination) during subsequent motion. The objective of the present work is to develop a model for determining the size of the heating, evaporation and calcination zones.

Thermo-Chemical Analysis of a Calcination Furnace to Produce Cathode Material for the Secondary Batteries

Lithium secondary batteries have been widely used in the portable electric devices as power source. Recently it is expected that the realm of its applications expands to the markets such as energy storage medium of hybrid electric vehicle (HEV), electric vehicle (EV). Cathode active material is crucial in terms of performance, durability, capacity of lithium secondary batteries. It is urgent to develope the technology for mass production of cathode material to cope with the markets' demands in the near future. In this study, a calcination furnace running in real production line is modelled in 3D, and the thermal flow and gas flow after chemical reaction in the furnace is analyzed through numerical computations. Based on the results, it is shown that large volume of CO2 gas is generated from chemical reaction. High concentration of CO2 gas and it's stagnation is clearly found from the reactant containers in which the reaction occur to the bottom area of the furnace. It is also studied that 15% or more CO2 mol fraction could affect to proper formation of LiCoO2 through TGA-DSC analysis. The solutions to evacuate carbon dioxide from the furnace are suggested through the change of furnace design and operating condition as well. Keywords : Secondary battery, cathode material, calcination furnace, LiCoO2

이차전지 양극활물질 제조용 소성로의 열화학적 해석

리튬 2차전지는 휴대용 전자기기의 전원으로 사용되어 왔다. 최근 하이브리드 자동차, 전기자동차의 에너지 저장매체로써 적용으로 인해 시장 확대가 기대되고 있다. 양극 활물질은 리튬2차전지의 성능, 수명, 용량을 결정하는 물질이며, 급증하는 시장의 수요에 따라 양극 활물질을 대량으로 생산할 수 있는 기술을 개발하는 것이 시급하다. 본 연구에서 실제 양극 활물질(<TEX>$LiCoO_2$</TEX>) 생산라인에서 가동 중인 소성로를 3D 모델링하였고, 수치적 해석을 통해 소성로 내부의 온도와 유동의 방향, 화학적 거동을 밝혀내었다. 결과로써, 생산량 증가로 인해 소성로에서 생성되는 <TEX>$CO_2$</TEX> 농도가 증가하며 정체되는 지점을 확인하였고, TGA-DSC 실험을 통해 <TEX>$CO_2$</TEX>가 몰분율 15%이상에선 <TEX>$LiCoO_2$</TEX>의 적절한 형성에 영향을 주는 현상을 확인하였다. 또한 소성로의 형상변화와 공정조건의 변화를 통해 문제되는 <TEX>$CO_2$</TEX>를 원활히 배출할 수 있는 해결책을 제안하였다. Lithium secondary batteries have been widely used in the portable electric devices as power source. Recently it is expected that the realm of its applications expands to the markets such as energy storage medium of hybrid electric vehicle(HEV), electric vehicle(EV). Cathode active material is crucial in terms of performance, durability, capacity of lithium secondary batteries. It is urgent to develope the technology for mass production of cathode material to cope with the markets' demands in the near future. In this study, a calcination furnace running in real production line is modelled in 3D, and the thermal flow and gas flow after chemical reaction in the furnace is analyzed through numerical computations. Based on the results, it is shown that large volume of <TEX>$CO_2$</TEX> gas is generated from chemical reaction. High concentration of <TEX>$CO_2$</TEX> gas and it's stagnation is clearly found from the reactant containers in which the reaction occur to the bottom area of the furnace. It is also studied that 15% or more <TEX>$CO_2$</TEX> mol fraction could affect to proper formation of <TEX>$LiCoO_2$</TEX> through TGA-DSC analysis. The solutions to evacuate carbon dioxide from the furnace are suggested through the change of furnace design and operating condition as well.

High speed production of YBCO precursor films by advanced TFA-MOD process

YBa 2Cu 3O 7− y (YBCO) long tapes derived from the metal-organic deposition (MOD) method using the starting solution containing trifluoroacetate (TFA) have been developed with high critical currents ( I c ) over 200 A/cm-width. However, high speed production of YBCO films is simultaneously necessary to satisfy the requirements of electric power device applications in terms of cost and the amounts of the tapes. In this work, we developed a new TFA-MOD starting solution using F-free salt of Y, TFA salt of Ba and Cu-Octylate for application to the coating/calcination process and discussed several issues by using the Multi-turn (MT) Reel-to-Reel (RTR) system calcination furnace for the purpose of high throughput without degradation of the properties. The coating system was improved for uniform deposition qualities in both longitudinal and transversal directions. YBCO films using the new starting solution at the traveling rate of 10 m/h in coating/calcination by the MT-RTR calcination furnace showed the values of the critical current density of 1.6 MA/cm 2 as thick as 1.5 μm at 77 K under the self fields after firing at the high heating rate in the crystallization.

Preliminary data on hard metal workers exposure to tungsten oxide fibres

The first personal exposure data for tungsten oxide fibres, in two hard metal manufacturing industries is presented. Occupational exposure was studied by static and personal measurements during tungsten metal production. Three different initial materials were used, ammonium-paratungstate (APT), blue oxide and tungsten trioxide. In both factories, airborne tungsten oxide fibres were detected both in static and personal samples. Fibre exposure varies for different activities. Charging of raw material, changing the hammer, cleaning-work on the cyclone and the micro-filter were found to be among the most high dusty operations. However, as workers use respirators during cleaning operations, these filters could not be related to personal exposure. The calcination of APT to the blue oxide generates fibrous dust. The raw material imported as blue oxide is also fibrous material and both charging it into the calcination furnace and re-charging it into the reduction furnace generates unnecessarily additional dusty periods. A single reduction-stage is, therefore, preferable. Furthermore, the tungsten trioxide raw material is non-fibrous, therefore, calcination of APT to tungsten trioxide and its reduction to tungsten metal is preferable with respect to minimising workers exposure to tungsten oxide fibres.

Use of ultra-microtomy to study phase relationships in industrial alumina particles

Production of smelting grade alumina relies on the transformation at high temperature (1200°C) of aluminium hydroxide (Al2(OH)3) to alumina (A12O3). In this process, a number of poly-morphic transformations occur which are related to the thermal conditions experienced by particles as they pass through a calcination furnace. TEM is required to study the effect of these transformations on the internal morphology of industrial alumina particles. The information from this can then be related to performance within the smelting operation. Cross-sections of whole particles (up to 70μm diameter) can only be obtained by ultra-microtomy of resin-embedded alumina.Samples of aluminium hydroxide and alumina were embedded in resin blocks (EPON or L.R. White - Hard Grade). Ultra-thin sections (∽50nM) were cut from the blocks using a MICRO-STAR diamond knife and an LKB IV ultra-microtome. Sections of particles were examined using a TEM to identify the different forms of alumina present, and characterise their relative distribution in a sample.