Анализ компоновки и режимов работы технологического участка фильтрации, сушки, обжига и доизмельчения продукта комбинированного окисления

In this paper, utilization of Victorian brown coal in a drying–pyrolysis process to make products is techno-economically assessed. The pyrolysis process is coupled with the drying and briquette making processes in order to improve the overall efficiency and quality of the products. The pyrolysis process led to the production of char, liquid oil, and hydrogen-rich noncondensable gases. A steady-state Aspen Plus simulation model was developed that provides estimated mass and energy balances for the overall system. The effect of a change in the heating mode and heating medium of the dryer on the overall energy and overall product yields was examined. Additionally, the effect of a change in the pyrolysis gas composition and coal initial moisture was studied. Results revealed that the rotary drum dryer with hot flue gas as a heating medium showed the best performance in terms of the final yields of the pyrolysis products and CO2 emission rate. In the best case scenario, when hot flue gas is used directly in a rotary drum dryer, approximately 55% of the total gas produced from the pyrolysis process is needed to burn in a separate boiler to provide heat for the whole system. The shorter residence time in the pyrolysis reactor results in a lower calorific value gas with less hydrogen but more CO2 produced, which in turn increases the consumption of gas to be burnt to provide heat for the whole system. The wet coal initial moisture is another important factor affecting the energy required for the dryer and hence the total energy consumption. A coal with a higher moisture content needs more coal gas to be burnt and releases more CO2. The cash flow analysis indicated the net present value (NPV) of $52.8 million for a plant with a capacity of 70.6 t/h raw coal based on the first quarter of 2015 pricing, with a internal rate of return of 25% and the payback period of 5.1 years under the best case scenario.

Drying is a critical stage in tobacco shred processing. The study focuses on the design of a rotary drum drying system with four independent temperature control zones in order to solve the problems of traditional rotary drum dryers: coarse temperature control, excessive energy consumption, and inconsistent product quality. By establishing a segmented dynamic temperature control strategy, precise adaptation to the multi-stage characteristics of the drying process was achieved. Taking tobacco shred drying as the research object, an orthogonal experimental approach was employed to systematically analyze the effects of seven factors—such as drum zonal wall temperature and hot air parameters—on the drying performance. The findings indicate that convective heat transfer from hot air is the dominant drying mechanism, with a-contribution rate exceeding 80%. Heat conduction from the drum wall shows notable spatial heterogeneity. The wall temperatures in Zones 2 and Zone 3 account for 6.59% and 4.88% of the influence on moisture content variation, respectively, which are substantially higher than that of Zone 4 (0.45%). By increasing the wall temperatures of the middle and front zones (Zones 2 and Zones 3) to 115–130 °C and applying low-temperature control (95–105 °C) to the tail zone (Zone 4), drying efficiency can be improved; and the risk of over-drying at the tail end is reduced, thus achieving both energy optimization and quality assurance. These findings provide new perspectives for improving drying equipment to enhance energy utilization and achieve precise control of the final moisture content.

The purpose of this study was to investigate experimentally the effects of impinging jets installed in a conventional rotary dryer for heat transfer enhancement. The metal drum had as insert a jet tunnel at the centerline, and the jets were arranged in an in-line configuration on the jet tunnel. A jet-to-jet (S) and a jet-to-target (H) distances were fixed at S/d = 6 and H/d = 4, respectively. Jet velocity (Vj ) was set at Vj = 5, 10 and 15 m/s, while jet temperature (Tj ) was 70, 80 or 90 °C. Drum rotation speed (N) was also investigated at N = 0.5, 1, and 3 rpm. The conventional rotary dryer was examined at the same mass flow rate of hot air to compare with the case having impinging jets. All experiments were conducted by batch drying 5 kg of fresh chilies for 8 hours. Results showed that installing jets gave more effective heat transfer, which accelerated water removal over that with the conventional rotary dryer, and the moisture contents were greatly reduced. On using impinging jets, the jet temperature had more influence on heat transfer enhancement than the jet velocity. In comparison, the effect of drum speed was small.

An overfilling indicator for wet overflow ball mills

While traditional disposal of solid waste from the global wine industry causes significant environmental burden and hazards, a range of value-added by-products can be produced from the grape marc. This review focuses therefore on crucial sustainability-enhancing technologies for pomace dewatering and separation, which constitute a mandatory stage in obtaining storage-stable by-products and final value-added commodities. A number of dryers and separators were considered for pre-treatment of wet grape marc and analysed in terms of their design characteristics, functionality, feasibility, throughput and efficiency. A multi-criteria decision analysis was carried out to compare, rank and select the equipment which is most suitable for the purpose. It was found out that the rotary drum dryer and the drum screen separator with internal blade rotor are the best candidates to fulfil the technology requirements, while the flowsheet that includes an initial separation followed by drying of the resulting fractions is a rather attractive option. Valorising grape waste worldwide contributes substantially to achieving the United Nations Sustainable Development Goals for responsible consumption and production, mitigating climate change, caring for health and well-being, preserving land life and combating hunger.

In this present research work, fruit and vegetable waste (FVW) sourced from the commercial market is transformed to solid fuels. Solid biomass fuel for commercial heating is produced using agricultural wastes. This in turn reduces the effect of environmental issues. Enough investigations are seen in the literature for Anacardium occidentale kernels, and no study is seen for materials Brassica oleracea leaves, Moringa oleifera pods, Citrullus lanatus lunds and Annona squamosa seeds and are considered for testing and evaluation in the present study. The amount of moisture contents of residues was dried in rotary drum dryer using sun parabolic dish collector coupled with U-type air heater (1000 W). The dried loose biomasses are powdered into grains ( 94.5%) and tumbling test (> 95%). Less costs of FVW pellets, for the fuel use in boilers and incinerators, etc., provide as a potential and eco-friendly fuel for energy generation.

Convective sludge drying by rotary drum dryer using waste steam for palm oil mill effluent treatment

Life cycle assessment of low-temperature thermal desorption-based technologies for drill cuttings treatment

Decomposition of tire and rubber in subcritical and supercritical water was investigated using a batch reactor. The influence of temperature and residence time was studied. Oil yield, gas yield, and residual solid were measured and analyzed. The results showed that tire and rubber could be pyrolyzed in subcritical and supercritical water at temperatures between 380 and 410 °C, and pressure from 19 to 28 MPa. The oil yield increased with residence time to its maximum and decreased quickly afterward. The oil yield maximum was 19.70 wt% at 410 °C at a residence time of 30 min and a pressure of 28 MPa. The gas yield increased with residence time and temperature. The gas yield maximum was 44.71 wt% at 410 °C with a residence time of 50 min and a pressure of 28 MPa. The primary components of the gas products were methane, acetylene, and hydrogen. More than 60 kinds of components in the pyrolytic oil were detected by GC/MS, including aromatic hydrocarbons, alkanes, olefins, and their derivatives.

The solids mean residence time in a rotary dryer is influenced by several variables such as dryer dimensions and solids characteristics. One of these characteristics, usually not taken into account in correlations proposed to estimate the mean residence time, is the solids feed moisture content. Although it is well known that the solids moisture content has a major impact on the ability of the solids to move along the rotary dryer, it does not enter as a parameter in available correlations. In this investigation, numerous experiments were performed in a pilot-scale rotary dryer to study the influence of solids moisture content and drying gas temperature on the mean residence time. Sand employed in cement makeup was used to perform these experiments. Results show that the mean residence time for a moisture content in the range of 8% to 12% is four times higher than for dry solids. The moisture content and the drying gas temperature influence significantly the shape of the residence time distribution curve.

Modelling the dynamics of solids transport in flighted rotary dryers

The influence of mechanochemical activation on the rheological properties and strength development of geopolymer

The predictions of the models of Matchett and Baker (1988) Saeman and Mitchell (1954) and Friedman and Marshall (1949) for the solids residence time in rotary dryers have been compared with both pilot-scale and industrial-scale data. A countercurrent pilot-scale dryer of 0.2m diameter and 2m long has been used with air velocities up to 1.5 ms−1 to measure the residence times of sorghum grain, The average discrepancy for the solids residence time between the predictions and the experiments that were carried out in the pilot-scale rotary dryer is — 10.4% Compared with the models of Friedman and Marshall (1949) and Saeman and Mitchell (1954) for the pilot-scale data obtained here, the Matchett and Baker model is more satisfactory for predicting the solids residence time in this pilot-scale dryer. It has also been found that the model of Matchett and Baker describes the industrial data of Saeman and Mitchell (1954) than the correlation of Friedman and Marshall (1949).

Rubber is widely used in situations involving cyclic loads, and the influence of temperature on rubber properties is particularly pronounced under cyclic loading. In this study, mechanical property tests and crack propagation tests of carbon black-filled hydrogenated nitrile butadiene rubber were conducted at four different operating temperatures. Based on the results of the crack propagation tests, the temperature-dependent characteristics of the Paris-Erdogan parameters and strain energy density were clarified. The Paris-Erdogan parameters were successfully expressed as a function of temperature. The strain energy density, on the other hand, exhibited the property of being strongly influenced by factors of strain, loading frequency, and others, while the temperature dependence was weak. On this basis, the unified fatigue crack growth kinetic model was constructed at multiple temperatures. The model results can match the experimental data well, particularly at temperatures of 60 °C and 80 °C. Finally, the fatigue life prediction model at different temperatures was constructed by combining the fatigue life test results. The results indicate a correlation between crack propagation characteristics and fatigue life predictions across different operating temperatures, with the predictions agreeing well with the measured life. The models can be used to analyze early fracture behavior or fatigue life prediction of rubber at different operating temperatures and minimize the need for extensive product testing prior to the manufacture of rubber products.

Mechanistic modeling and simulation of grinding iron ore pellet feed in pilot and industrial-scale ball mills