Visual Experimental Analysis of the Residence Time of Flexible Biomass Particles in a Baffled Rotating Cylindrical Tube

Abstract

Drying of biomass or biofuels is a major issue during pretreatment because of a high initial moisture content, which results in low energy efficiency and combustion temperature and high emission of hydrocarbons. As the motion behaviors of biomass fuels play an important role in the drying process, it is of great significance to investigate the motion of biomass. In this study, visualization experiments on the motion of flexible nonspherical biomass particles in a baffled rotating cylindrical tube were performed. The residence time of biomass particles was obtained and analyzed by taking into account gas velocity, mass flow rate of flexible biomass, initial moisture content of biomass particles, slope and rotational speed of the cylindrical tube, and other parameters under several operational conditions. The results indicated that the mean residence time of flexible biomass increased with the increase in the mass flow rate and initial moisture content and decreased with the increase of the cylindrical tube’s rotational speed and slope and the velocity of the gas phase. Despite the quite small sliding friction coefficient between the tube’s inner wall and biomass particles, a larger slope could lead to stronger sliding friction force in the axial direction when these biomass particles moved to the bottom of the tube. Mean residence time is observed to decrease significantly and gradually decrease with the increase in rotational speed from 6 to 9 rpm and from 9 to 18 rpm, respectively. In addition, the mean residence time increased from 78.5 to 99.4 s when the inlet mass flow rate increased from 60 to 240 kg/h without the gas phase, but it increased from 57.4 to 78.5 s within the same range of the inlet mass flow rate at a gas velocity of 0.3 m/s.

Experimental Study on the Agglomeration Behavior of Elongated Biomass Particles in a Lifting Tube

“…With the realization of mankind that the use of traditional energy sources has had a serious impact on the environment and climate change, the use of clean energy has received increasing attention from countries around the world. − As a kind of green, low-carbon, and clean energy, biomass can be widely used in industry, life, transportation, and other fields. − In biomass energy, the pneumatic conveying device is an efficient gas–solid reaction and heat and mass transfer equipment, which has many advantages, such as fast gas–solid transfer speed, high contact efficiency, and high utilization of raw materials and equipment. − Therefore, pneumatic conveying devices are widely used in the conversion process of biomass energy, which makes an essential contribution to the development of the clean energy industry. − After nearly 70 years of fundamental theoretical research and technological development, pneumatic conveying devices are now widely used in many industries, such as the chemical industry, energy, food processing, material processing, environmental protection, and so on. − Some of the advantages of pneumatic conveyors are the low number of moving parts, flexible setup, and fully enclosed transportation, all of which create environmentally safe applications . It serves not only as an alternative for transporting pellet materials between locations or blending different pellet types but also facilitates the prefabrication of biomass pellets, offering functionalities such as moisture content control, sorting, feed, and mixing. − In the realm of contemporary engineering applications, there is a prevailing preference for dilute-phase conveying, which proves to be the most economical mode due to the inherent ease of cleaning and maintenance associated with the equipment compared to concentrated-phase conveying systems .…”

“… 1 − 3 As a kind of green, low-carbon, and clean energy, biomass can be widely used in industry, life, transportation, and other fields. 4 − 6 In biomass energy, the pneumatic conveying device is an efficient gas–solid reaction and heat and mass transfer equipment, which has many advantages, such as fast gas–solid transfer speed, high contact efficiency, and high utilization of raw materials and equipment. 7 − 9 Therefore, pneumatic conveying devices are widely used in the conversion process of biomass energy, which makes an essential contribution to the development of the clean energy industry.…”

Effect of baffle structure on the dynamic transportation behavior of s‐liked biomass fuels in a rotating drum

“…RTD is always treated as an important index of describing the transportation behavior of particles within the rotating drum. [32][33][34] The method of RTD has been widely applied in variety of continuous single or multi phases flow systems. 35,36 To understand the transportation behavior inside industrial facilities, RTD is commonly estimated and serves as an important property for guidance of efficient operation design and the improvement of system process.…”