40 research outputs found
Espèces condensables issues de torréfaction de biomasses lignocellulosiques : caractérisation aux échelles laboratoire et pilote
Get PDFTorrefaction is mild thermal treatment carried out between 200 and 300 °C, in an inert atmosphere, improving properties of biomass, in order to use it as a biocombustible. This study focuses on the characterisation of the condensable species released during torrefaction, at laboratory and pilot scale. In the laboratory, some samples of pine, ash wood, miscanthus and wheat straw were torrefied at 250, 280 and 300 °C in a fixed bed reactor. The condensable species were analysed by GC-MS, GC-GC and HPLC-MS. Around a hundred of species were identified, including around twenty were quantified and represented 77 % of the condensable species. At pilot scale, a continuous reactor was designed, improved and characterised to treat several kg.h-1 of biomass. A multi-step recovery system for the condensable species was developped. Torrefaction experiments showed that the condensed fractions had different chemical compositions.La torréfaction est un traitement thermique opéré entre 200 et 300 °C en atmosphère inerte améliorant certaines propriétés de la biomasse, afin d’utiliser celle-ci comme biocombustible. Nos travaux portent spécifiquement sur la caractérisation des espèces condensables produitesen torréfaction, aux échelles laboratoire et pilote. En laboratoire, des échantillons de pin, frêne, miscanthus et paille de blé ont été torréfiés à 250, 280 et 300 °C en réacteur à lit fixe. Les espèces condensables ont ensuite été analysées par GC-MS, GC-GC et HPLC-MS. Cette analyse a permis d’identifier une centaine d’espèces, dont une vingtaine, quantifiée, représente 77 % des condensables. À l’échelle pilote, un réacteur continu a été conçu, amélioré et caractérisé pour torréfier quelques kg.h-1 de biomasse. Un système de récupération multi-étagée des condensables a été développé. Des essais de torréfaction ont montré que les fractions condensées présentent des compositions chimiques différentes
Detailed identification and quantification of the condensable species released during torrefaction of lignocellulosic biomasses
Get PDFTorrefaction is a mild thermal pretreatment which improves biomass properties and releases condensable species. Condensable species released during torrefaction of pine, ash wood, miscanthus and wheat straw at 250, 280 and 300 °C were investigated. A fixed-bed reactor was used for the laboratory scale experiments. A micro-GC, Karl Fischer titrator and GC-MS were used to analyse incondensable gases, water and other condensable species, respectively. The overall mass balance ranged from 96 to 103 wt.%. The quantification rate of condensable species was on average 77 wt.%. In addition to the major species usually reported in the literature – water, acetic acid, 2-propanone,1-hydroxy- – we show that large amounts of some anhydrosugars were produced. Additionally, 85 condensable species were identified. Among these species, many terpenes and terpenoids in pine were identified by adsorption on SPME fibre. Finally, the influence of temperature and of the nature of biomass on the yields of condensable species was highlighted
TồNG HợP Và NGHIÊN CứU ẢNH HƯởNG CủA GIá TRị PH PHảN ỨNG LÊN Sự HìNH THàNH HạT NANO ZNS BằNG PHƯƠNG PHáP HóA ƯớT
No full textCác hạt nano ZnS đã được tổng hợp bằng phương pháp hóa ướt trong dung môi nước với sự tham gia của dung dịch đệm ở nhiệt độ phòng. ảnh hưởng của pH và loại dung dịch đệm đã được nghiên cứu bằng lý thuyết; thông qua thực nghiệm tổng hợp hạt nano ZnS, giá trị pH tối ưu của phản ứng đã được xác định thông qua phổ nhiễu xạ tia X và tính chất quang của vật liệu
Giáo trình phương pháp dạy học đại cương môn tin học : Sách dành cho Cao đẳng Sư phạm
No full text215 tr. ; 24 cm
