14 Matching Results

Search Results

Advanced search parameters have been applied.

Low VOC drying of lumber and wood panel products: Progress report No. 3

Description: Studies on the removal of volatile organic compounds (VOC) from wood or wood products were conducted. Steam-induced extraction of VOC from oriented strand board (OSB) was studied using a tube furnace at 130 C which resulted in over 50% removal in 30 minutes. RF treatment of softwood lumber removed up to 68% of VOC in 20 minutes. Studies on the transport of moisture in wood confirmed that transport is greatest in the transverse surface, followed by the tangential and radial faces.
Date: March 1, 1997
Creator: Boerner, J., Su, Wei, Banerjee, Sujit & Shmulsky, R., Thompson, A., Ingram, L., Conners, T.
Partner: UNT Libraries Government Documents Department

High-intensity drying process: Impulse drying. Progress report on modeling of fluid flow and heat transfer in a crown compensated impulse drying roll: The heat transfer problem

Description: Results of this study indicate that under the conditions where the two boundaries are maintained at the same temperature, the viscous heat dissipation within the lubricant, due to viscous drag and inertial effects, plays a major role in the net heat transfer. However, when the inner surface temperature is much greater than that of the shoe, the effect of viscous heat dissipation is reduced significantly. For the conditions analyzed in this study, the regions under the solid part of the shoe, which are associated with a greater lubricant velocity, had a significant influence on the magnitude of the heat transfer from the oil to the roll; because of a greater lubricant thickness for the left-hand sub-channel, the dissipated heat, and net heat transfer under the solid part in the left-hand sub-channel was greater than that for the corresponding region in the right-hand sub-channel. Numerical techniques such as finite difference or finite element analysis should be utilized to determine the thermal performance of the press roll subjected to a temperature dependent viscosity. and other types of boundary conditions. The temperature distributions predicted from such a model should be incorporated in a finite element model to determine the stress distribution within the roll coating for various design and operating conditions.
Date: July 1, 1995
Creator: Orloff, D.; Hojjatie, B. & Bloom, F.
Partner: UNT Libraries Government Documents Department

Development and pilot testing of modular dynamic thermomechanical pulp mill model to develop energy reduction strategies. Final report

Description: With the development of on-line and real-time process simulations, one obtains the ability to predict and control the process; thus, the opportunity exists to improve energy efficiency, decrease materials wastes, and maintain product quality. Developing this capability was the objective of the this research program. A thermomechanical pulp mill was simulated using both a first principles model and a neural network. The models made use of actual process data and a model that calculated the mass and energy balance of the mill was successfully implemented and run at the mill on an hourly basis. The attempt to develop a model that accurately predicted the quality of the pulp was not successful. It was concluded that the key fro a successful implementation of a real-time control model, such as a neural net model, is availability of on-line sensors that sufficiently characterize the pulp.
Date: October 1, 1996
Creator: Coffin, D.W.
Partner: UNT Libraries Government Documents Department

High-intensity drying processes: Impulse drying. Annual report

Description: Experiments were conducted on a sheet-fed pilot-scale shoe press to compare impulse drying and double-felted pressing. Both an IPST (Institute of Paper Science and Technology) ceramic coated and Beloit Type A press roll were evaluated for lienrboard sheet structures having a wide range of z-direction permeability. Purpose was to find ways of correcting sheet sticking problems observed in previous pilot-scale shoe press experiments. Results showed that impulse drying was superior to double felted pressing in both press dryness and in important paper physical properties. Impulse drying critical temperature was found to depend on specific surface of the heated layer of the sheet, thermal properties of the press roll surface, and choice of felt. Impulse drying of recycled and two-ply liner was demonstrated for both Southern Pile and Douglas fir-containing furnishes.
Date: December 1, 1993
Creator: Orloff, D.I. & Phelan, P.M.
Partner: UNT Libraries Government Documents Department

Control of the accumulation of non-process elements and organic compounds in pulp mills with bleach filtrate reuse. Quarterly report, October--December 1996

Description: A portion of each filtrate sample was freeze-dried and the resulting solids were analyzed for ash content. Adsorption experiments with calcium and barium were carried at 70{degrees}C in a temperature controlled incubator under continuous mixing in order to simulate the environment experienced by brownstock as it moves through the Q stage. In the calcium experiments, it was difficult to accurately determine the calcium adsorbed on the pulp by measuring the depletion of calcium in the aqueous phase. Consequently, the technique was modified. In the modified technique, the calcium-adsorbed pulp is acid washed again to release the calcium. The calcium concentration in the washings is measured, and the calcium adsorbed on the pulp is estimated by material balance. Measurement of calcium adsorption on the brownstock pulp fibers from the L-P/Samoa mill have been obtained.
Date: December 31, 1996
Creator: Frederick, W.J.; Laver, M.L. & Rorrer, G.L.
Partner: UNT Libraries Government Documents Department

Control of the accumulation of non-process elements and organic compounds in pulp mills with bleach filtrate reuse. Quarterly report 3, January--March, 1997

Description: Progress during this quarter is described on four tasks. The first task involves the recovery of organic matter from bleach effluents and black liquors, separation of carbohydrates and lignin degradation products, analysis of functional groups, and characterization of carbohydrate polymers. Progress in the second task was made in the selection of model compounds. Several subtasks are complete in Task 3, but the paper summarizes progress made in the determination of the residual hemicellulose content in the pulp samples. Finally, results are given for the measurement of metal adsorption isotherms on wood pulp. Goals for the next quarter are listed.
Date: May 1, 1997
Creator: Frederick, W.J.; Laver, M.L. & Rorrer, G.L.
Partner: UNT Libraries Government Documents Department

Low VOC drying of lumber and wood panel products. Progress report number 6

Description: Twenty five Southern pine boards were machined into 2 x 4 inch pieces. Next, the 8 foot boards were cut in half into matched pairs. One of the two was irradiated with RF, while the other served as a control. Both sets were dried under a conventional temperature-time based schedule. Results and conclusions are: RF pretreatment of lumber does not affect strength; the amount of pinene lost into the headspace during low-VOC RF-treatment of wood approximately corresponds to the amount of material lost from the wood; virtually all the pinene can be removed from the low-VOC reactor with steam, suggesting that pinene can be collected when the small amount of steam released during low-headspace treatment is condensed; temperature and moisture loss profiles for particle at 105 C has been modeled using experimental data at 130 C and 160 C; the VOC-temperature curve from dried particle shows a break at about 156 C, the boiling point of {alpha}-pinene, demonstrating that pinene boil-off occurs beyond this threshold; VOC release from dry particle has been successfully modeled; the transport of VOC from sapwood to the atmosphere for pine is faster than the corresponding movement from heartwood to sapwood; and seasonal variations in pine extractives are small.
Date: January 1, 1998
Creator: Yan, H.; Wild, M.P.; Hooda, U.; Banerjee, S.; Shmulsky, R.; Thompson, A. et al.
Partner: UNT Libraries Government Documents Department

Low VOC drying of lumber and wood panel products. Progress report No. 5

Description: This progress report summarizes three accomplishments in a study of low volatile organic compound (VOC) drying of lumber and wood panel products. A mathematical model for predicting moisture emissions from particle was constructed and is being extended to VOCs. VOCs emissions from drying boards show that VOCs appear to be evenly released from all surfaces. Preliminary results from monthly analyses of loblolly pines indicate that resin acids appear to decrease between March to August, and that no consistent trends are apparent for terpenes. 3 refs., 13 figs., 1 tab.
Date: October 1, 1997
Creator: Wild, P.; Yan, Hui & Banerjee, S.
Partner: UNT Libraries Government Documents Department

Low VOC drying of lumber and wood panel products. Progress report No. 4, annual summary

Description: Heating softwood in a low-headspace environment draws out the VOCs from the wood, without removing the water. The VOCs can be collected from the headspace, and represent a valuable product. The VOC-depleted wood can then be dried conventionally with much reduced emissions. Heating can be accomplished through radiofrequency (RF) or steam. For lumber, steam is inefficient, but brief RF treatment under low-headspace conditions draws out 80% of the VOCs. The power used is quite low, since the RF energy is not used to remove water, but only to maintain the wood at a set temperature. The technology is now at the pre-pilot stage. Either steam or RF can be used for particle, OSB, and veneer, again under low-headspace conditions. Increasing steam temperature facilitates VOC removal. In order to understand the mechanism of VOC release in lumber, the transport of water and VOCs to the surface is being studied as a function of sample size and orientation. Characterization of the terpenes and resin/fatty acids from a control set of trees is underway in order to define the seasonal influence on VOCs.
Date: July 1, 1997
Creator: Boerner, J.; Su, Wei & Yan, Hui
Partner: UNT Libraries Government Documents Department

Low VOC drying of lumber and wood panel products. Progress report No. 7

Description: Green pine blocks (2x1x 1) were dried to different moisture levels at 120 degrees C. They were immersed in D{sub 2}O (greater than 99% isotopic Content) for different periods at room temperature, and were then cut in halves. One piece from each set was then wrapped in plastic, and microwaved at 110 W, for 30 minutes, with the field being cycled to keep the wood surface at 90-100 degrees C. Fibers taken from just inside the wet surface from five regions along the length of the piece were then analysed by mass spectrometry with a direct insertion probe. The m/e profiles of the three isotopic forms of water, namely H{sub 2}O, HOD, and D{sub 2}O, remained unchanged as the wood was heated inside the spectrometer, indicating that they were bound equally strongly to the wood. The water released from the green wood had the same isotopic composition regardless of whether or not the wood was microwaved (Table 1), indicating that the exchangeable protons in wood were not affected by microwaving. However, as the wood progressively dried, the water released from the microwaved wood was of lower isotopic content, which means that microwaving increases access of the exchangeable protons in wood tissue to water. The only exchangeable protons in dried wood are those sited on hydroxyl groups, and the difference in isotopic exchange is the greatest for dried wood. This must mean that as wood dries, internal hydrogen bonding restricts access of D{sub 2}O to the hydroxyl protons. Presumably the energy transferred to water upon microwaving is sufficient to at least partially overcome this barrier. The effect is akin to the hysteresis that occurs for moisture sorption to green and dried wood. Similar isotope exchange work with D{sub 2}O has been previously conducted to determine the accessibility of cellulose to water.
Date: March 1, 1998
Creator: Yan, Hui; Hooda, Usha & Banerjee, Sujit
Partner: UNT Libraries Government Documents Department

High-intensity drying processes: Impulse drying modeling of fluid flow and heat transfer in a crown compensated impulse drying press roll, The lubrication problem. Annual report

Description: Although evaporative drying is currently used to dry paper, research has showed that significant energy savings could be realized with the newer impulse drying technology in drying heavy weight grades of paper. This report analyzes the lubrication problem which arises in modeling impulse drying employing a crown compensated roll. The geometry for the associated steady flow problem is constructed and expressions are derived for the relevant velocity fields, mass flow rates, and normal and tangential forces acting on both the bottom surface of an internal hydrostatic shoe and the inside surface of the crown-compensated roll. Results from the analytical model agreed well with experimental data from Beloit Corp. for the small shoe/roll configuration. The model can be used to predict effect of design and physical parameters on the performance of the press roll (lubricant thickness, pressure distributions, mechanical power required to operate the roll, etc.) and to determine optimal performance under various operating conditions.
Date: August 1, 1994
Creator: Orloff, D.I.; Hojjatie, B. & Bloom, F.
Partner: UNT Libraries Government Documents Department

High-intensity drying processes: Impulse drying. Progress report on furnish evaluations for impulse drying commercialization demonstration

Description: Laboratory and pilot scale experiments were performed to identify potential furnishes and operating parameters for upcoming high-speed pilot scale trials and commercial demonstration of impulse drying of heavy weight grades of paper. Results indicate that hydrodynamic specific surface is highly dependent on sheet formation and prehandling. Mill refined pulp and machine paper were comparable to laboratory prepared samples in regards to permeability and impulse drying. Process variables such as platen surface coating, felt type, felt moisture, and presteaming temperature profiles were investigated. Substantial improvements in sheet smoothness were achieved.
Date: February 1, 1995
Creator: Orloff, D.I.; Phelan, P.M. & Rudman, I.
Partner: UNT Libraries Government Documents Department

Data for model validation summary report. A summary of data for validation and benchmarking of recovery boiler models

Description: One of the tasks in the project was to obtain data from operating recovery boilers for the purpose of model validation. Another task was to obtain water model data and computer output from University of British Columbia for purposes of benchmarking the UBC model against other codes. In the course of discussions on recovery boiler modeling over the course of this project, it became evident that there would be value in having some common cases for carrying out benchmarking exercises with different recovery boiler models. In order to facilitate such a benchmarking exercise, the data that was obtained on this project for validation and benchmarking purposes has been brought together in a single, separate report. The intent is to make this data available to anyone who may want to use it for model validation. The report contains data from three different cases. Case 1 is an ABBCE recovery boiler which was used for model validation. The data are for a single set of operating conditions. Case 2 is a Babcock & Wilcox recovery boiler that was modified by Tampella. In this data set, several different operating conditions were employed. The third case is water flow data supplied by UBC, along with computational output using the UBC code, for benchmarking purposes.
Date: July 1, 1997
Creator: Grace, T.; Lien, S.; Schmidl, W.; Salcudean, M. & Abdullah, Z.
Partner: UNT Libraries Government Documents Department

Black liquor combustion validated recovery boiler modeling, five-year report

Description: The objective of this project was to develop a new computer model of a recovery boiler furnace using a computational fluid dynamics (CFD) code specifically tailored to the requirements for solving recovery boiler flows, and using improved submodels for black liquor combustion based on continued laboratory fundamental studies. The project originated in October 1990 and was scheduled to run for four years. At that time, there was considerable emphasis on developing accurate predictions of the physical carryover of macroscopic particles of partially burnt black liquor and smelt droplets out of the furnace, since this was seen as the main cause of boiler plugging. This placed a major emphasis on gas flow patterns within the furnace and on the mass loss rates and swelling and shrinking rates of burning black liquor drops. As work proceeded on developing the recovery boiler furnace model, it became apparent that some recovery boilers encounter serious plugging problems even when physical carryover was minimal. After the original four-year period was completed, the project was extended to address this issue. The objective of the extended project was to improve the utility of the models by including the black liquor chemistry relevant to air emissions predictions and aerosol formation, and by developing the knowledge base and computational tools to relate furnace model outputs to fouling and plugging of the convective sections of the boilers. The work done to date includes CFD model development and validation, acquisition of information on black liquor combustion fundamentals and development of improved burning models, char bed model development, and model application and simplification.
Date: August 1, 1996
Creator: Grace, T.M.; Frederick, W.J.; Salcudean, M. & Wessel, R.A.
Partner: UNT Libraries Government Documents Department