Zhiqin Wang

Changes in the physicochemical structure and pyrolysis characteristics of wheat straw after rod-milling pretreatment

Pyrolysis is increasingly used for raw biomass conversion. In this study, the effects of rod-milling pretreatment (RMP) on the physicochemical properties and pyrolysis characteristics of wheat straw (WS) was found. The mechanism behind these changes was further analyzed. RMP appreciably reduced the particle size and cellulose crystallinity, and increased the specific surface area and pore volume of WS. Under RMP, with an increasing conversion rate α, the activation energy E was expressed as a para-curve, whereas it was expressed as a tangent curve for samples that underwent hammer-milling pretreatment (HMP). At the same α, the thermal degradation temperature for RMP was lower than that for HMP. The E value clearly decreased with RMP, and increased following a wave-like pattern with increased rod-milling strength (RMS). The lowest E value (118.69 or 108.97 kJ/mol) was obtained with a milling time of 60 min. Hence, RMP is an environmental-friendly and effective method for improving the efficiency of pyrolysis.

Combined different dehydration pretreatments and torrefaction to upgrade fuel properties of hybrid pennisetum ( Pennisetum americanum ×P. purpureum )

Different dehydrating methods combined with torrefaction were investigated to find the underlying mechanism that how dehydration process influence the degree of hornification. Hybrid pennisetum was selected as the experiment material. Oven-dried sample (ODS), crushed dried sample (CDS), and sun-cured dried sample (SDS) were torrefied under the temperature of 275 °C and 300 °C with the duration time of 60 min. The results showed that, changes in elevated carbon content and higher heating value (HHV) and reduced oxygen content of SDS were the most obvious under identical torrefaction conditions. Fuel ratio of SDS was enhanced most under 300 °C. It also had the highest devolatilization index (Di). The combination of sun-cured dried with torrefaction under 300 °C caused lowest degree of irreversible hornification happened during dehydrating process, and different hornification degrees caused by different dehydrating methods effect the enhancement of fuel properties of lignocellulosic biomass material.

Effects of combined pretreatment with rod-milled and torrefaction on physicochemical and fuel characteristics of wheat straw

The mechanism of rod-milling combined with torrefaction as well as its effects on physicochemical and fuel properties of wheat straw were investigated. Rod-milling and hammer-milling samples were torrefied under three temperatures (250, 275, and 300 °C) with a duration time of 30 min. The results indicated that combined rod-milling and torrefaction pretreatment (CRT) significantly elevated carbon content, higher heating value, fuel ratio, and reduced oxygen content and atomic H/C and O/C ratios in wheat straw. Moreover, CRT significantly reduced cellulose crystallinity, and increased the specific surface area and pore volume of wheat straw, which lowered the wheat straws degrading pyrolysis temperature. These peak values appeared under 300 °C. Devolatilization index (Di) was improved by rod-milling pretreatment under identical torrefaction conditions except 275 °C. Therefore, the combination of rod-milling with torrefaction under 300 °C has the advantage of enhancing fuel properties of lignocellulosic biomass materials.

Optimization of Binder Addition and Compression Load During the Pelletization of Wheat Straw Using Response Surface Methodology

Abstract. Densification is required for efficient handling and transportation biomass as feedstock for biofuel production. Binders can enhance the straw pellet strength and improve pellet performance. The present investigation is to optimize binder addition of wheat straw pelletization process by using a single pelleting unit. Response surface methodology was employed by using a four factor five level Central Composite Design with wood residue, bentonite, crude glycerol addition by mass fraction and compression force as process parameters. Pellet tensile strength, specific energy consumption and pellet density were the response variables. The higher heating value, ash content and the cost of the pellet were also considered when optimized binders. The results showed that the developed model fitted the data and was adequate for binder analysis. Wheat straw pelleted with 30% wood residue, 0.80% bentonite and 3.42% crude glycerol addition and 4000 N compressive force was identified as the optimal process parameter with low ash content (6.13%) and high heating value (18.64 MJ t -1 ). Pellet tensile strength, specific energy consumption and pellet density values were 1.14 MPa, 32.6 MJ t -1 and 1094 kg m -3 , respectively. Confirmation tests indicated high accuracy of the model.

Modeling Design and Application of Low-Temperature Plasma Treatment Test Stand for Seeds before Sowing

Stimulation with a low-temperature plasma (LTP) can improve the seed germination and seed adaptability to the environment. This technology has been applied in practice, but the study level of mechanism involved is still limited. Moreover, the treatment devices in using are quite simple. The paper focuses on the modeling design and application of the LTP treatment test stand for seeds before sowing. Numerous experimental LTP treatment on crop seeds and forage grass seeds will be conducted to find out the optimal dose used in the treatment. Another advanced method of this modeling is data collecting and intelligent monitoring system designed in, therefore all key process parameters can be under control during treatment period. At the same time, the modeling design will provide technical support for large-scale manufacturing of seed treatment devices.

Research on the Demand of Alfalfa Harvest Machine in China’s Northern and North-west Regions

Abstract. The harvest machinery is the foundation of mechanized production for alfalfa, the study on the demand of alfalfa harvest machinery can improve the comprehension level of the harvest machinery market situation and the development tendency in China’s northern and north-west regions, and it can lead the scientific research institution or company to develop and improve the harvest machinery. The questionnaire was designed to analyze the consumer behavior in the process of selecting or purchasing the alfalfa harvest machine. Through questionnaire investigation and factor analysis, this paper reduced the influencing factor indexes to accessible factor by using SPSS and built a multivariate linear equation model. Based on the qualitative analysis and quantitative analysis, the advice on the development of alfalfa harvest machine was proposed.

Development of an optimized forage harvest machinery system selection factors analysis model using analytic network process and DEMATEL

Machinery harvest system is one of the most important key links in the whole forage production processing. A model for selecting machines and optimizing machinery matching for harvest system was developed by considering the important factors of environment, social, economic, policy and so on. The factor analysis, evaluation and optimization process was accomplished by using Delphi method, analytic network process (ANP) and DEMATEL. The model was evaluated for three regions with crop of alfalfa. The results showed that this model is possible for different users to select, evaluate and optimized their machinery harvest system.