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Recent Advances in Biomass Drying for Energy Generation and Environmental Benefits
Published in Shusheng Pang, Sankar Bhattacharya, Junjie Yan, Drying of Biomass, Biosolids, and Coal, 2019
Shusheng Pang, Yanjie Wang, Hua Wang
The rotary dryer, as shown in Figure 1.2, is one of the most commonly used technologies in woody biomass drying (Pang, 2014; Pang and Mujumdar, 2010). It is effective for handling both sawdust and chips (Xu and Pang, 2008; Krokida et al., 2007; Zabaniotou, 2000). In the co-current rotary dryer, the wet material and the hot air enter the dryer from one end, and the dried material and the humid air exit from the other end. On the other hand, with the counter-current configuration, the wet material and the hot air enter the dryer from opposite ends and move inside the drum in opposite directions. In this way, the dried material can have much lower mc than that of the co-current rotary dryer because the driest solids in the counter-current rotary dryer are exposed to the gas with the highest temperature. However, in the counter-current configuration, the fire risk is much higher than it is in the co-current rotary dryer as the dry material is in direct contact with high-temperature drying air (Li et al., 2010). A commercial rotary dryer for drying wood sawdust is shown in Figure 1.2a as a schematic diagram and in Figure 1.2b as an actual dryer in use. Furthermore, a novel rotary dryer, namely roto-aerated dryer, is also available now, and has higher efficiency, greater efficacy, larger processing capacity, and shorter residence time than conventional rotary dryers (Silverio et al., 2015).
Drying of Foods
Published in Susanta Kumar Das, Madhusweta Das, Fundamentals and Operations in Food Process Engineering, 2019
Susanta Kumar Das, Madhusweta Das
Rotary dryer is a slightly inclined (about 5°) heavy drum, usually made of mild steel that rotates on gears at slow speed. The internal surface is fitted with flights (louvers) those receive the material and carry it in the direction of rotation of the drum (vide Figure 14.5). When the flight reaches an angular position that exceeds the angle of repose of the material, the flight is no longer able to hold the materials. The materials fall at the bottom. Thus, this repeated lifts and falls (continuous turning of the materials) leads to faster drying. Simultaneously, the materials proceed from the high end to the low end. The hot air flow is co-current or counter-current. This type of dryers is suitable for drying granular materials such as cereals, pulses, spices and waste materials from food industries. In some typical designs, internal steam pipes are laid (all along the length) at the periphery of the drum. Thus, the material receives conduction heat from these pipes over and above the convection heat from the airflow.
Thermal Desorption
Published in David J. Wilson, Ann N. Clarke, Hazardous Waste Site Soil Remediation, 2017
Richard J. Ayen, Carl R. Palmer, Carl P. Swanstrom
A rotary dryer consists of a large, heated rotating cylinder. It is similar in design to rotating kilns and calciners and is sometimes given these names in the generic sense. Contaminated soil is fed into one end of the cylinder and is conveyed to the other end by the rotation and inclination of the cylinder. As the feed material progresses down the cylinder, it is heated, releasing the organic contaminants and water contained in and on the soil. These vapors are transported to the gas treatment system and the decontaminated soil exits from the dryer to the product handling system.
Heat transfer enhancement in rotary drum dryer by incorporating jet impingement to accelerate drying rate
Published in Drying Technology, 2021
Makatar Wae-hayee, Kirttayoth Yeranee, Wasu Suksuwan, Ameen Alimalbari, Somchai Sae-ung, Chayut Nuntadusit
In a direct rotary dryer as presented in Figure 1(a), the hot gases/air are directly blown into the drum to contact the wet feed, and drying occurs mostly during the free fall of feed from the flights.[12–14] The flow of the hot air/gases can be co-current or counter-current relative to movement of the moist solids. In the case of co-current flow, heat-sensitive feed is moved along with the high-temperature gases/air since initially the evaporation of surface moisture rapidly cools the temperatures. In contrast, in the case of counter-current operation, the solid material flows against the inlet gases/air, and this configuration gives the higher thermal efficiently of the two alternatives.[13] However, in both these operating modes of the direct rotary dryer, the most important heat transfer mechanism is convection between hot gases/air and particles.
Drying process study of hydrothermal carbonized biomass
Published in Drying Technology, 2022
Daniel A. Sánchez, Luis A. Díaz-Robles, Francisco Cubillos, Jaime Gómez, Alejandro Reyes, Fidel Vallejo, Ernesto Pino-Cortés
Although the thermochemical and densification treatments applied to the biomass produce a solid carbonized product (hydrochar) with improved properties, a later drying process must be carried out, because the matter at the reactor outlet is in a saturation state. To achieve this goal, a dynamic system was considered that prevents case hardening, with an indirect source of heat transfer to avoid the combustion of the material to be dried, reducing the risk of fire and making it as energy efficient as possible. The indirect rotary dryer has an intermediate surface that operates without direct contact between the wet matter and the heat source.
Energy viability of industrial drying of wood chips
Published in Biofuels, 2023
Flávio José Simioni, Martha Andreia Brand, Debora Cristina Bianchini
A rotary dryer can be efficient under suitable operating conditions to achieve higher evaporation rates and can handle large, heterogeneous particles. This is important because the biomass milling step often used to reduce size of the particles increases the energy consumption of the process. Rotary drum dryers are the flagship of the drying industry due to their large capacity, efficiency and versatility in adapting to different usage situations [50].