Numerical Investigation of the Effects of Thermo-physical Properties on Tar Intra-particle Secondary Reactions during Biomass Pyrolysis

In this study, a coupled transport and chemical kinetic model was used to simulate the effects of biomass thermo-physical properties on intra-particle secondary reactions during convective-radiative pyrolysis of wood cylinder ( ? in a thermally thick regime. Wood cylinder was modeled as a one-dimensional porous solid. Solid mass conservation equations were solved by first-order Euler Implicit Method. Finite volume method was used to discretize the mass conservation equation for tar and gas, the energy conservation equation and the pressure equation. Tri-Diagonal Matrix Algorithm (TDMA) was used to solve the resulting simultaneous equations. Findings revealed that thermo-physical properties influence the extent of intra-particle secondary reactions, biomass conversion time and product yield distribution. Simulation results also showed that density has the highest influence on intra-particle secondary reactions.Keywords: Biomass, pyrolysis, thermo-physical properties, intra-particle secondary reactions1. Introductio

Effect of Peak Temperature on Biomass Pyrolysis Characteristics in Thermally Thin Regime in a Fixed-Bed Reactor

Effect of reactor peak temperature on biomass pyrolysis in thermally thin regime with a constant heating rate of 30 K/s, reactor pressure of 1 atm and reactor peak temperature ranging from 500 to 1000 oC in a fixed-bed reactor has been numerically investigated. Wood samples  were modeled as two-dimensional porous solids. Transport equations, solid mass conservation equations, intra-particle pressure generation equation and energy conservation equation were coupled and simultaneously solved to simulate the pyrolysis process. First order Euler Implicit Method (EIM) was used to solve the solid mass conservation equations. The transport, energy conservation and intra-particle pressure generation equations were discretized by Finite Volume Method (FVM). The generated set of linear equations was solved by Tri-Diagonal Matrix Algorithm (TDMA). Intra-particle fluid flow velocity was estimated by Darcy’s law. Results showed that increase in reactor peak temperature from 500 to 600 oC slightly increased the degree of volatiles intra-particle secondary reactions and that further increase of the former has no effect on the latter. Increasing reactor peak temperature from 500 to 600 oC also resulted in slight increase in gas and secondary tar yield but some decrease in tar and char yield. Further increase in reactor peak temperature above 600 oC has no effect on products evolution and yields. The highest tar yield (45.31%) was obtained at 500 oC. Keywords: Biomass, pyrolysis, intra-particle secondary reactions, thermally thin regim

Numerical Investigation of the Effect of Reactor Severity on Biomass Pyrolysis Characteristics in Thermally Thick Regime

Effect of reactor peak temperature on biomass pyrolysis in thermally thick regime with a constant heating rate of 30 K/s, reactor pressure of 1 atm and reactor peak temperature ranging from 500 to 1000 oC in a fixed-bed reactor has been numerically investigated. Wood cylinders  were modeled as two-dimensional porous solids. Transport equations, solid mass conservation equations, intra-particle pressure generation equation and energy conservation equation were coupled and simultaneously solved to simulate the pyrolysis process. First order Euler Implicit Method (EIM) was used to solve the solid mass conservation equations. The transport, energy conservation and intra-particle pressure generation equations were discretized by Finite Volume Method (FVM). The generated set of linear equations was solved by Tri-Diagonal Matrix Algorithm (TDMA). Intra-particle fluid flow velocity was estimated by Darcy’s law. Results showed that increase in reactor temperature from 500 to 600 oC and from 600 oC to 700 oC favoured primary tar intra-particle secondary reactions, causing corresponding increase in the release rate and yield of gas and secondary tar. Increase in reactor temperature beyond 700 oC had no significant influence on primary tar intra-particle secondary reactions and on the release rates and yields of volatiles and primary tar. Char yield, however, decreased continually with increase in reactor temperature. The highest gas yield (50.10%) was obtained at 700 oC, primary tar yield (33.91%) at 500 oC and char yield (14.79%) at 500 oC. Keywords: Biomass, pyrolysis, intra-particle secondary reactions, thermally thin regim

Acclimatization and Field Evaluation of Micropropagated Plants of Chrysanthemum Cv.'Arka Swarna'

Chrysanthemum cv.'Arka Swarna' was micropropagated using shoot-tip and nodal microcuttings on MS medium containing 3% sucrose and 0.25% Phytagel® in the absence of externally supplied plant growth regulators, yielding 90-100% rooted plantlets, or in medium containing 1 μM benzyladenine or kinetin yielding 20-32% plantlets within 2-4 weeks of subculture. The stocks were acclimatized employing sachet technique wherein the rooted plantlets (2.5-4 cm) were planted in polythene bags of 5"×9" filled to one-third height with planting mixture. The closed bags with 1-5 plants were incubated under conditions similar to the in vitro stocks. The plantlets recorded 90-100% establishment within 4 weeks. The ex vitro established plants were evaluated in the field a month later by direct planting , or after one month in a field nursery-bed, along with conventional suckers. While field establishment (80-95%) was not significantly influenced by the treatments, micropropagated plants put through the nursery appeared to be the best among the three treatments in vegetative growth, floral characteristics and flower yield, demonstrating advantage of micropropagation over conventional propagation for shy-suckering chrysanthemums

Socioeconomic Status and Comorbidity Burden Influence on Mortality Index in Spinal Neurological Surgery Operations

Background Pre-existing comorbidities are generally thought to increase risk of undergoing surgical procedures Low socioeconomic status (SES) has been correlated with increased comorbidity burden previously Patients with low SES undergoing spinal neurological surgery operations may have existing comorbidities that impact expected surgical outcomes Vizient Inpatient Mortality uses pre-existing comorbidities during an inpatient stay to estimate post-operative expected mortality With increased comorbidity burden, expected mortality in low SES patients may not be accurately represented b

Effects of Pressure and Heating Rate on Products Release Rates and Yields during Biomass Pyrolysis in Thermally Thick Regime

Numerical investigation of the synergetic effects of reactor pressure and heating rate on biomass pyrolysis in thermally thick regime has been carried out. Wood cylinders  were modeled as two-dimensional porous solids. Transport equations, solid mass conservation equations, intra-particle pressure generation equation and energy conservation equation were coupled and simultaneously solved to simulate the pyrolysis process and the accompanying physical phenomena. First order Euler Implicit Method (EIM) was used to solve the solid mass conservation equations. The transport, energy conservation and intra-particle pressure generation equations were discretized by Finite Volume Method (FVM). The generated set of linear equations was solved by Tri-Diagonal Matrix Algorithm (TDMA). Intra-particle fluid flow velocity was estimated by Darcy’s law. Findings revealed that increase in reactor pressure does not significantly affect biomass primary decomposition reactions for all heating rates considered (10, 20, 30, 40 and 50 K/s). In the vacuum region (0.0001 and 0.01 atm), increase in pressure had no significant effect on the release rates and yields of product species at all heating rates. In the pressurized region, increase in pressure (from 10 to 100 atm) inhibited intra-particle secondary reactions. Pressure increase from vacuum to atmospheric and from atmospheric to pressurized condition caused some changes in product distribution. The degrees of intra-particle secondary reactions at atmospheric and pressurized conditions were much higher than at vacuum conditions. Primary tar release rates and yields at atmospheric and pressurized conditions were much lower than at vacuum conditions while gas and secondary tar release rates and yields were higher at atmospheric and pressurized conditions. Intra-particle secondary reactions were more sensitive to change in heating rate at vacuum conditions than at atmospheric and pressurized conditions. Keywords: Biomass, pyrolysis, pressure, heating rate, intra-particle secondary reactions, thermally thick regim

Numerical Investigation of the Effects of Reactor Pressure on Biomass Pyrolysis in Thermally Thin Regime

Effects of reactor pressure [vacuum (0.0001, 0.01 atm), atmospheric (1 atm) and pressurized (10, 100 atm) regions] on primary tar production rate, primary tar intra-particle secondary reactions, and tar and gas release rates during  pyrolysis in thermally thin regime at a heating rate of 30 K/s and final reactor temperature of 973 K have been numerically investigated. Wood cylinder (  was modeled as a two –dimensional porous solid. Transport equations, chemical kinetic models, pressure and energy conservation equations were coupled and used to simulate the pyrolysis process. Solid mass conservation equations were solved by first-order Euler Implicit Method. Finite volume method was used to discretize the mass conservation equation for argon, primary tar, gas and secondary tar, energy conservation equation and pressure equation. Findings showed that pressure increase, either from vacuum to atmospheric or from atmospheric to pressurized region, has no significant effect on the primary decomposition reactions of the sample. Pressure increase within vacuum region (0.0001 to 0.01 atm) and within pressurized region (10 to 100 atm) has no significant effect on primary tar intra-particle secondary reactions, and tar and gas release rates. However, pressure increase from vacuum to atmospheric and from atmospheric to pressurized region increased primary tar residence time within the pyrolyzing solid thereby enhancing intra-particle secondary reactions. Keywords: Biomass, pyrolysis, pressure effect, intra-particle secondary reactions, thermally thin regim

Animal health research and development

A book chapter on veterinary health services in Zimbabwe.Zimbabwe’s veterinary delivery system and research capability have been shaped by the need to prevent, control, manage and/or eradicate animal diseases.202 Although major epidemics like rinderpest, contagious bovine pleuropneumonia and African east coast fever have been eradicated, there is still need to ensure that any reintroduction of these diseases is prevented. The Department of Veterinary Services has the mandate to provide animal health services and has had to put in place special control measures for some of the endemic diseases such as foot and mouth disease, contagious abortion, anthrax, beef measles and salmonellosis. These diseases affect both the export and domestic beef markets. For purposes of foot and mouth disease surveillance and control, the country is divided into foot and mouth disease control zones through a network of cattle and buffalo proof cordon fences. Epidemiological surveillance, monitoring and reporting of specified diseases and pests as of2004 relied on a countrywide network of veterinary infrastructure that comprised the following: eight provincial and 53 district offices; 308 subdistrict animal management and health centres in the smallholder sector and six in commercial fanning areas; one central veterinary laboratory; and three provincial diagnostic laboratories in Bulawayo, Mutare and Masvingo

Comparison of the radiographic and functional outcome in pediatric orthopaedic patients with Gartland type II supracondylar fracture treated by operative versus non operative management

Background: The non-operative method of closed reduction and application of long arm posterior splint and the operative method of closed reduction and percutaneous pinning are both putative management for Gartland II supracondylar fracture. The purpose of this study is to compare which method is superior in the management of this type of fracture thru the comparison of the radiographic as well as the functional outcome. Methods: This study includes 51 pediatric patients undergoing supracondylar fracture treatment. The enrolled participants were randomly allocated to one of the two groups to receive either non operative or operative treatment. Radiographic and functional outcome was assessed post treatment. Results: The operative group exhibited significant superiority versus the non operative group as reflected by the results of the post-treatment radiographs utilizing the anterior humeral line while the Baumann’s angle showed no significant difference between the two groups. Moreover, the operative group demonstrated a better Mayo elbow performance score total per follow up, only in the first 3 months but showed no significant difference thereafter. Conclusions: We therefore conclude that non operative and operative management are both effective treatment for Gartland II supracondylar fracture. The operative group showed significant superiority with results of the anterior humeral line falling mostly at the central one-third of the capitellum. The operative group manifested a better Mayo elbow performance score total only during the first 3 months of follow up