Abstract

An alternative to a rotary dryer for biomass is a bed dryer. In this type of dryer, the wood particles are stationary, and the air passes upward through them. Compared with rotary dryers, bed dryers may be more economical to operate on a small scale. The present work investigated drying biomass in a fixed bed dryer.

The drying characteristics of wood biomass were measured using a thin-layer drying technique at inlet gas conditions of 50°C to 200°C and 0.3 to 0.9 m/s. The drying behavior was modeled using a one-parameter Newton model. The thin-layer model was then used in a deep bed model to predict drying times and moisture profiles in the bed. Drying times based on the model at depths up to 23 cm were within −22 to +12 percent, and typically within ±4 percent, of the experimental results.

A drying zone ranging from 0.13 to 0.18 m in depth moves up the bed as drying occurs. The biomass is wet above and dry below this zone, resulting in considerable variability in moisture content within the bed. The material in an industrial dryer would need to be mixed or a dryer would need to be designed with stages if a uniform moisture content among the particles was an important criterion.

Abstract

Air emissions can be a limiting factor in obtaining the required permits to operate a plant when biomass is dried prior to further processing. Aged ponderosa pine, fresh ponderosa pine, Douglas-fir, and juniper were rotary dried to final moisture contents of 10 to 25 percent. The drum of the dryer was heated to temperatures of 200°C to 425°C. Total hydrocarbon emissions and the emission of various compounds were measured. While wood type strongly influenced emission levels, they were not strongly correlated with temperature or final moisture content. Total hydrocarbon emissions ranged from 0.10 to 0.25 g·kg⁻¹ of ovendry biomass for aged material to 6.9 g·kg⁻¹ for fresh material. Ethanol emissions averaged 7,621 and 2,591 mg·kg⁻¹ for the fresh pine and the Douglas-fir, respectively, compared with less than 30 mg·kg⁻¹ for the aged material. Acetic acid emissions were also greatest for the fresh pine.

Abstract

In forest biomass recovery operations from harvest residues, processing equipment can work most productively if they can work without interference or waiting on trucks. A deterministic simulation model was developed to estimate the economic effect of truck–grinder interference in forest biomass processing and transport operations on steep terrain. Truck–machine interference can occur in situations where the grinder is waiting for trucks or vice versa. We analyzed how the number of available trucks and road characteristics affect grinder utilization and biomass delivery cost. Three cases based on different road characteristics were designed and applied to actual operations in order to illustrate how particular road features in relation to the spatial location of the grinder can affect the economics of the operation. An economic model was also developed to estimate the waiting cost of trucks and machinery due to truck–machine interferences. Grinder location in relation to available truck turnaround, turnouts, truck turning-around time, truck positioning time, and distance traveled on each road surface have a significant effect in forest residues processing and transport economics at the operational level. After the optimization was performed, the grinder utilization rate on a harvest unit with highly constrained road access reached 60 percent using six trucks. Waiting cost represented 15.15 percent of total grinding cost. On the medium constrained road access harvest unit, maximum grinder utilization reached 77 percent using five trucks. A loop road case resulted in a grinder utilization rate of 81 percent using five trucks.

Abstract

The objective of this research was to develop baseline information regarding the structure and performance of Ohio's logging industry. Questionnaires were distributed on-site at logger chapter meetings across the state. Multivariate clustering was used to group similar types of firms based on responses to 15 productivity and cost variables. Three clusters were identified: Local Mill Suppliers, Product Merchandisers, and Volume-Dependent Producers. The clusters were largely homogeneous as far as the overall makeup and administration of their companies. Clusters did differ regarding haul distance, pieces of equipment owned, and equipment age. Volume-Dependent Producers, while not significantly larger in size statistically, viewed the productivity, present, and future cost variables more pessimistically than the other clusters. The key variable of concern across clusters was the cost of consumables, primarily fuel, paralleling more recent findings in other states.

Abstract

The recent economic crisis has greatly affected how companies conduct business. To be competitive, companies had to make changes to their product lines, distribution channels, marketing, and overall business strategies. This study was conducted to describe and analyze the log supply component of the hardwood forest products distribution chain and to investigate changes over the past 5 years. State forestry utilization and marketing specialists were interviewed to gain a regional overview of log distributions systems, followed by a survey that resulted in 57 responses from log distributors/brokers/wholesalers from 24 states. Results indicated that, on average, respondents received the majority of their logs from gatewood purchases, and the majority of logs purchased went directly into the sawmill market. From 2007 to 2011, logs sold to sawmill and veneer markets decreased by 6 and 7 percent, respectively, and logs sold to export markets increased by 30 percent. Respondents indicated that increasing fuel and trucking costs, followed by logger shortages, had the greatest negative impact on business operations. In contrast, increasing log exports had the greatest positive impact. Most respondents indicated that although current economic conditions have affected the way they conduct business, they have been able to find ways to adapt. Services such as providing log delivery, bucking logs to desired lengths, and procuring hard-to-obtain species helped companies in the log business remain competitive.

Abstract

The building sector is increasingly identified as being energy and carbon intensive. Although the majority of emissions are linked to energy usage during the operation part of a building's life cycle, choice of construction materials could play a significant role in reducing greenhouse gas emissions and other environmental end-point damages. Increasing the use of wood products in buildings may contribute to the solution, but their environmental impacts are difficult to assess and quantify because they depend on a variety of uncertain parameters. The present cradle-to-gate life-cycle analysis (LCA) focuses exclusively on a glued-laminated wood product (glulam) produced from North American boreal forests located in the province of Quebec, Canada. This study uses primary data to quantify the environmental impacts of all necessary stages of products' life cycle, from harvesting the primary resources, to manufacturing the transformed product into glulam. The functional unit is 1 m³ of glulam. This is the first study based on primary data pertaining to Quebec's boreal forest. Quebec's boreal glulam manufacturing was compared with two other LCAs on glulam in Europe and the United States. Our results show that Quebec's glulam has a significantly smaller environmental footprint than what is reported in the literature. From an LCA perspective, there is a significant advantage to producing glulam in Quebec, compared with the European and American contexts. The same holds true in regard to the four end-point damage categories.

Abstract

The effects of rainfall exposure on panel integrity were investigated for oriented strandboard and plywood. Both panel materials experienced substantial increases in moisture content and thickness with limited rainfall exposure and these were coupled with decreases in flexural properties. The results showed that even short-term rainfall exposure was detrimental to the properties of both materials and emphasized the importance of protecting these materials during construction.

Abstract

This research examined oil from the neem tree (Azadirachta indica A. Juss.) for its potential as an eco-friendly wood preservative. In contrast to expectations from the literature, according to which neem oil should be effective against insects and fungi, neem oil performed poorly as a preservative for Pinus radiata D. Don wood, which suffered significant mass losses in the bioassays. Using standard experimental procedures from the wood preservation industry, concentrations of 0.01, 0.1, 1.0, 2.5 and 5.0 percent neem oil in white spirit were bioassayed against five species of decay fungi. Additionally, concentrations of 0.01, 0.1 and 1.0 percent neem oil were bio assayed against two species of termites. It is concluded that neem oil can only be useful as a wood preservative if new, optimized formulations are sought, probably exploiting synergy with cobiocides.

Abstract

Lateral shear resistance capacities of face-to-face single-staple and one-row vertically aligned multistaple joints in three oriented strandboards (OSB) were investigated and compared. Experimental results from testing single-staple joints indicated that the face strand orientation of OSB materials had no significant effect on their staple holding capacity in resisting lateral shear loads. The OSB-III with a density of 35.19 pounds per cubic foot (pcf; 563 kg/m³) had a significantly higher lateral shear resistance capacity than OSB-II, with a density of 29.12 pcf (466 kg/m³). Results of multistaple joints indicated that there was no significant difference in lateral shear load resistance capacities between OSB-II and OSB-III joints. The lateral shear load resistance capacity of multistaple joints increased significantly as the number of staples increased from two to four in increments of one. Two alternative power equations were suggested to estimate the lateral shear load resistance capacity of face-to-face one-row vertically aligned multistaple joints in OSB. One equation requires knowing the lateral shear resistance load of single-staple joints in an OSB material, and the other one requires knowing the density of the OSB material constructing the joints.

Abstract

This study examines the withdrawal load and energy capacity of three types of nail fasteners that are commonly used to attach sheathing to framing members: 8d common, annular ring shank, and helical shank. A baseline set of data was collected for single nails in accordance with test methods defined in ASTM D1761. Tests were performed until complete withdrawal occurred in order to quantify the total withdrawal energy. The average peak loads from testing were within 7 to 8 percent of predicted values. The annular and helical nails had much higher peak load capacity as expected, and the withdrawal energy was also greater. A new device was developed in order to subject multiple nails to withdrawal loading simultaneously. Reinforced sheathing was used to transfer load from the hydraulic actuator to the nails, which is more representative of actual structural response where there is load sharing among the nails. This device allowed direct comparison with the single nail results. Further, it also allowed the examination of a “stitched” nailing pattern, where fasteners are driven at alternating angles of ±60° measured from the framing member face. It was found that the stitched pattern resulted in 42 percent higher peak load capacity per fastener for 8d common nails, but for the helical and annular nails, peak load was similar to that achieved with a normal 90° drive angle. Withdrawal energy was 24 to 48 percent higher for all nail types using the stitched pattern.