Linear programming is a technique used to determine the best (or optimal) solution to a problem where there are a number of competing and usually interrelated choices. The technique requires that each restriction on the problem being modeled be formulated as a linear equation. The model consists of a set of linear equations with more unknowns than equations and thus there are many possible solutions. In order to determine the best of these solutions, it is necessary to decide which criteria will be used to determine the best. Once the criteria (usually maximum profit or minimum cost) is chosen, an equation is set up giving the amount each variable (or activity) contributes to the criteria. The linear program then determines which solution will maximize or minimize this criteria. The LP described in this write up was written to determine the best process and set of process conditions for converting steam exploded Aspen wood into a variety of chemical feedstocks. The LP is designed to maximize profit based on the sales value of the chemicals produced, the cost of raw materials and the processing costs incurred. The model is restricted by the raw material availability, the utility and chemical requirements of each process step, the capacity of each process step and the market requirements for each chemical produced. This report will give a detailed description of the model structure, will discuss the validity of the data used in the model as well as future requirements, will discuss the running of the model on the computer and will discuss analysis of the LP solution.
The three most abundant wood species from the province of Newfoundland were assessed for waferboard potential. This work was fully supported by the Department of Forestry and Agriculture of Newfoundland.
Approximately 70% of all wood used goes into residential (50%) and non-residential (17%) construction. In the United States, by the turn of the century the volume of lumber used for these applications will exceed 100 billion bd.ft., of which 15 billion board feet will be 2"x8" and larger dimension lumber. This is the high priced end of the wood products spectrum. Consumption in Canada will be approximately one-tenth of this.
Elimination of saw kerf through the compression slicing process has initiated research into the optimization of the compression slicing parameters. Five of these parameters have been selected for study in the 1979-1980 federal fiscal year, through a contract given to Forintek Canada Corp. by Environment Canada. These parameters are the following: 1) Find an alternative to tires or pads for lateral pressuriza tion, 2) Study knife profile to reduce checking damage, 3) Study knife tensioning to reduce checking damage, 4) Study methods of reducing knife friction, 5) Study the dustribution of stresses in the knife when tensioning and slicing. Following is a detailed description of the work done during the 1979-1980 federal fiscal year on each of these compression slicing parameters.
Wood drying is an essential step in the manufacture of most wood products to minimize the development of defects such as warp and checking. Kiln-drying under controlled conditions of temperature and humidity is the most widely used method for removing moisture from wood and achieving a low, uniform moisture. Many topics relevant to lumber drying are discussed in this manual: wood structure and wood-moisture relationships, drying methods, kiln types and instrumentation, treatment of logs and lumber prior to drying, kiln schedules and drying defects. Graphic data tables dealing with wood properties and wood-moisture relationships at various temperature are provided for hardwoods and softwoods utilized in Eastern Canada.
Reprinted in 1993 - no longer available in print format
Overall properties of poplar waferboard can be considerably upgraded by the massive use of an inexpensive resin binder derived form ammonium-based spent sulphite liquor (SSL). Further improvement on waferboard quality can be achieved by the combination of higher resin content and thinner wafers. Low-density waferboard also can be produced to meet CSA 0188 requirements by using aligned wafers. This inexpensive SSL binder, however, requires a longer press time and prefers a higher platen temperature to cure. A new waferboard plant, designed and built to fully exploit both technical and economical advantages of this binder system, would be ideal. For some existing waferboard plants it may be necessary to slightly modify their production line in order to adopt this new binder system. Great savings on resin cost can be realized by substituting the expensive petrochemical-based phenolic resin with the renewable and inexpensive sulphite liquor binder. Economically and technically speaking it is entirely possible to produce a new type of better waferboard at a lower cost.
Electrical methods of assessing the moisture content (MC) of wood are commonly employed by the wood-using industries. These methods make use of such electrical properties of wood as its electrical resistance, dielectric constant, and radio frequency power loss which vary with MC. Moisture meters using the relationship between MC and resistance are known as the resistance-type; those which use the relationship between MC and dielectric constant are the capacitance-type; and the meters using the relationship between MC and radio frequency power loss are the RF power-loss-type. In the lumber industry of eastern Canada the resistance-type meter is used almost exclusively.
The concept of removing moisture from a humid drying chamber by means of condensation (dehumidification) originated a long time ago, but it was not until about 1960 that a European manufacturer took the idea and developed the first modern dehumidification drying unit. Now there are installations in numerous countries throughout the world. North America certainly presents a very lucrative market, but since the first appearance of the equipment in 1972 there has been continual debate on the advantages and disadvantages of dehumidification drying. The lumber industry required facts and unbiased opinions, and to fulfill this need the Eastern Forest Products Laboratory engaged in a program of research to evaluate dehumidification drying systems for Canadian application. Specific data on drying times, energy consumption and drying costs from actual installations, are required to properly assess the advantages and disadvantages of dehumidification drying.