DRYING AND STORAGE TECHNIQUES AND THEIR STRATEGIES FOR WOOD CHIPS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: MCINTIRE-STENNIS
• Reporting Frequency: Annual
• Accession No.: 1001585
• Project Start Date: Dec 2, 2013
• Project End Date: Sep 30, 2016
• Program Code: [(N/A)]- (N/A)

Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853

Performing Department
Biological & Environmental Engineering

Non Technical Summary
Drying is a major and challenging step in the pre-treatment of biomass for many used. Biomass feed stocks are mostly wet and need to be dried from 30 to 60 moisture content to about 10 to 20 % moisture content. Large scale bio-energy plants use direct-rotary dryers and steam drying techniques but are expensive. Willow is a mature crop and there have been best practices that have been developed but the logistics of storage and drying willow are limited particularly for the smaller scale and specialty applications.= . The drying of grain is well simulated and grain conditioning technology has been well developed. These techniques and devices have been adapted to large scale bioenergy systems. However, the cost of equipment to condition (dry) can be very high. "For this reason, fuel driers are almost never found in facilities of smaller size. The typical residence furnace is less than 100,000 Btu and some use wood as a fuel. Wood can be obtained in a variety of sizes (logs, chips, pellets, etc.) and is dried and processed in variety of ways and over different lengths of time. There is a need to study the handling, drying and storage of wood chips as they might be used in a relatively "closed" system (production, processing and use near each other). At water heating system for two buildings will be used as a good representation of such a system as well as other smaller scale systems.

Animal Health Component

70%

Research Effort Categories

Basic

20%

Applied

70%

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
204	0670	2020	70%
402	0650	2080	30%

Knowledge Area
204 - Plant Product Quality and Utility (Preharvest); 402 - Engineering Systems and Equipment;

Subject Of Investigation
0670 - Short rotation woody crops, including holiday trees; 0650 - Wood and wood products;

Field Of Science
2020 - Engineering; 2080 - Mathematics and computer sciences;

Keywords

biomass

energy

wood chip drying

willow chip storage

wood chip physical properties

engineering design

Goals / Objectives
1. Create a model for thermodynamic parameters of moist air at constant pressure for specific geographic locations, for a calendar year and on hourly basis. Model will determine amount of water that can be removed for any time period during the year for a given ventilation period and include the possibility of the use of heated air. The cost of removing the water under difference circumstances will also be calculated using estimated cost for fuel. 2. Collect data on pressure drop over a control volume of wood chips at airflows typically used for drying throughout the year. Chips samples will come from different harvesting techniques. 3. Collect data for chips from different harvesting techniques 1) to determine storage volume and changes in density over time, 2) to determine pile temperature and moisture content during drying and storage. 4. Collect data on the deterioration of energy content of wood and the development of mold as a function of storage temperatures, storage time and drying rate. Wood samples will come from different harvesting techniques. 5. Test different drying/storage durations for drying willow on an annual basis that could satisfy the needs of Cornell Boiler in Geneva. We will test storage/times variations relative to the harvest time. There will be a short(3-5 weeks) storage/ drying time (just in time burning relative to harvest) with heated air, medium (2-3 months) storage/drying time with heated and ambient air and long (4-12 months) storage/drying time with ambient air. 6. Findings during these studies will be reported in peer reviewed journals and made available through websites at Cornell and Penn State as well as appropriate conferences.

Project Methods
1. We will develop an Excel and Matlab model for drying wood chips based weather data and elevation from any location. Geneva NY will be our test case for the model but the model will also be used in Energy Courses in BEE particularly BEE4010. Economic analysis will be incorporated into the model based that is based on the energy used to heat air and operate fans to aerate the chip piles. Cost of energy will be determined. 2. We expect to collect chips harvested from different harvesters (at least one row and two row), for different growth times (at least two to four years) and different locations of the north east. 3. Chips will be analyzed for size (sieve and image processing technique), density, energy content, moisture content and biological activity during the drying processes. 4. Airflow versus pressure drop for fixed volumes of chips will be determined and compared to airflow in stacked piles. This data to be put in the form of a Shedd's Chart typical for grain drying and used to determine fan specifications. Chip characteristics will be correlated with these data also. (Behlen Manufacturing Company Columbia NE, 2013; Junan, W. and Hongwei, Z. 1998). 5. Three drying and storage processes will be used for the Geneva boiler: a) Fresh chips dried in hopper for 3 weeks and used immediately- so called Just in time drying of chips with heated and ambient air; b) drying and storage of chip piles with heated and ambient for different durations r, c) drying and storage of chips with ambient air for different durations. From these unique drying events we will be able compare results to those predictions from our weather model and airflow/pressure drop estimates.

Progress 12/02/13 to 09/30/16

Outputs
Target Audience:Biomass producers and processors. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The willow fired boiler is a well known project and is visited by a wide variety of interested parties and provides great opportunities for training and professional development. The ability to provide interested parties an examination of the operation of the facility on-line provides significant educational opportunities. It is possible to provide research opportunities for testing different control algorithms and testing of different biomass products. This project has been used as a demonstration project and case study for student for students in BEE4010 Renewal Energy Systems and BEE4500 Bioinstrumentation course which are taught in the spring semester. How have the results been disseminated to communities of interest?We have reported on the model for thermodynamic properties to multistate group. We have plans to report on the project at the summer meetings of the ASABE and submit peer review articles to ASABE or other bioenergy journals. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We have developed a model using thermodynamic parameters of moist air at constant pressure for specific geographic locations which can use or average values over different time periods or actual daily/hourly values for environment parameters. The model determines the amount of water that can be removed for any time period during the year according to the environmental values for the specified ventilation periods. If it is possible to heat the ventilating air, the impact of the heated air on the ventilation air can be calculated and the increase in water removal calculated. The cost of removing the water under difference circumstances will also be calculated using estimated cost for fuel. It is also possible to theoretically test different control strategies using the model. This will require some calibration or estimation of the temperature change of the ventilation air as a function of the "water to air" heat transfer.Initial control strategies, with ambient air only, turned the fan on only if outside ambient air is above a fixed temperature (>32F). With heated air, the fan was turned on when ambient air temperature (>32) and the return temperature of the heating fluid was greater than 128F. With ambient air control the time when the ventilation system is turned on a We have designed a method to collect pressure drop over a control volume of wood chips at airflows that might be used to dry chips. We have not tested of this technique as there was significant and unknown compaction of the wood chips as they were loaded into the barn and the air flow though out the piles was variable. Our attempts to measure air flow was part of our initial instrumentation package and may have provided some but limited data on air flow through the pile at midpoint of the ventilation pipe and to one side. We will have collected chip samples from 3 different harvesters and sorted them into 8 different sizes with sieves. We developed imaging methods for measuring chip dimensions and variability by measuring and width and length of the side with the largest area. Design and implementation of first stage of instrumentation to collect pile data had a late start and a considerable amount of the pile was frozen making installation of instrumentation into the pile impossible. The harvesting schedule was variable throughout the project (early Jan to late April. A redesigned instrumentation system with limited measurements was implemented that was compatible with Cornell's facility group and will provide long term (years) access to all the data, via a priority on-line system, associated with the pile, ventilation system and the boiler data. Energy content data has been collected on wood samples of 8 varieties of shrub willow. The energy content shows very little difference between these varieties of shrubwillow. It appears that drying the willow chip faster reduces the amount of mold based upon data from the April harvest and use of heated air. 5. We were had three periods to dry chips: a) Starting Jan 2014 with limited instrumentation and only ambient air; b) Starting in late spring 2015 with instrumentation and only ambient air; c) Starting in late spring 2016 with instrumentation and ambient air and the ability to heat air. We were able to dry the chips in all cases to 20% or less moisture content. I in 2015 we had few measurements. In 2015 and 2016, we had all our measurements and the ability to heat the air in 2016. In 2015, we were able to dry chips with ambient air and have a data set to compare to our model for thermodynamic parameters of moist air at the storage barn location. Air flow measurements and other characteristics indicated that our air distribution system is in need of changes in order to redistribute the air to various ventilation tubes that are beneath the pile and run across the pile from front to back. We were challenges to distribute temperature sensors from the top to the bottom of the pile and know reliably their depth once the pile has been established in the storage barn after harvest. We were able to correct this for 2016. We never found a reliable methodology to sample deep into the pile and know reliably our sampling position.

Publications

Progress 10/01/14 to 09/30/15

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The willow fired boiler is well known project and is visited by a wide variety of interested parties and provides great opportunities for training and professional development. The ability to provide interested parties an opportunity to examine in person or on-line the operation of the facility provides significant educational opportunities. It is possible also to provide research opportunities for testing different control processes and materials in the biomaterial areas. How have the results been disseminated to communities of interest?The willow fired boiler is well known project and is visited by a wide variety of interested parties and provides great opportunities for training and professional development. The ability to provide interested parties an opportunity to examine on-line the operation of the facility provides significant educational opportunities. It is possible to provide research opportunities for testing different control process and materials testing. This project has been used as a demonstration project and case study for students in BEE 4010 Renewal Energy System course. This course is taught each spring. What do you plan to do during the next reporting period to accomplish the goals?1. We will provide a heated air system with which to ventilate the chip pile. 2. We will compare the results of our ventilation and heated air system to the predicted drying estimated by the thermodynamic model. 3. We will develop control algorithms for our ventilation and heated air control and the necessary hardware and measurement system needed to implement such an algorithm. 4. We will examine the air flow pressure drop over control volumes of willow chips with respect to compaction. 5. We monitor chip flow rate into and energy output from the boiler and integrate this with energy model for the drying of the chips.

Impacts
What was accomplished under these goals? 1. We did a redesign our instrumentation system due to challenges in the first year's harvesting season. We revisited the design and have implemented a new design which has limited pile measurements but will be compatible with Cornell's Facility group. This design was implemented and provides data on chip input (volume/time) to the boiler and boiler output (BTU). The design also monitors relative humidity (ambient and above the pile), pile temperatures (limited in depth into pile), CO sensing above the pile, various air flow sensors in the air distribution system. The entire measurement system has secure on-line access via the internet. 2. We are challenged to distribute temperature sensors from the top to the bottom of the pile and know reliably their depth once the pile has been established in the storage barn after harvest. Likewise we are challenged to find a reliable methodology to sample deep into the pile and know reliably our sampling position. We continue to attempt different techniques. 3. We were able to dry chips with ambient air and have a data set to compare to our model for thermodynamic parameters of moist air at the storage barn location. Air flow measurements and other characteristics indicated that our air distribution system is in need of changes in order to redistribute the air to various ventilation tubes that are beneath the pile and run across the pile from front to back. 4. The flow rate of the wood chips to the boiler has been measured and can be correlated with the energy output of the boiler which will allow for variety of efficiency parameters to be determined. 5. We have determined energy content of wood chips at harvest and have collected samples from the pile at the end of harvest to determine if there is any significant difference in energy content.

Publications

Progress 12/02/13 to 09/30/14

Outputs
Target Audience: Nothing Reported Changes/Problems: Professor Bartsch as retired however will be recruited for advice as the project continues. A visiting engineer working with Dr. Smart has taken on some of the responsibilities that Dr. Bartsch had performed. Our instrumentation development caused us to lose some opportunities with last years' drying experiments but we have resolved these. The opportunity to examine in more detail the boiler inputs and outputs is one we are looking at adding so that we can have an instrumented system from pile to boiler outputs that will be available on-line. What opportunities for training and professional development has the project provided? The willow fired boiler is well known project and is visited by a wide variety of interested parties and provides great opportunities for training and professional development. How have the results been disseminated to communities of interest? We have reported on the model for thermodynamic properties to multistate group. What do you plan to do during the next reporting period to accomplish the goals? 1. we will develop control algorithms for our ventilation control and compare the predicted drying estimated by the thermodynamic model to the actual results achieved will drying with ambient air at predetermined times. 2. We will examine the air flow pressure drop over control volumes of willow chips with different characteristics. 3. We will include control functions for turning on and off the fans and test the pile monitoring instrumentation. We will also look at monitoring the flow rate of the wood chips to the boiler and moisture content of the wood chips. We will also monitor the boiler output as part of this process. 4. We will monitor the loss of energy content during the drying process.

Impacts
What was accomplished under these goals? 1. We have created a model for thermodynamic parameters of moist air at constant pressure for specific geographic locations, for a calendar year and on hourly basis. Model determines amount of water that can be removed for any time period during the year for a given ventilation period and include the possibility of the use of heated air. The cost of removing the water under difference circumstances can also be calculated using estimated cost for fuel. 2. We will have collected chip samples from different harvesters. We have not run tests to relate air flow and pressure drop. 3. Design and implementation of first stage of instrumentation to collect pile data had a late start and when it was ready a considerable amount of pile was frozen making installation of instrumentation into the pile impossible. The harvesting schedule and our ability to implement the instrumentation was not a good fit. We have revisited the design and have implemented a new design which has limited measurements but will be compatible with Cornell's facility group. We will have similar access to all the data associated with the pile via a priority on-line system that is also connected to the boiler. This system will be available for year two tests. 4. Energy content data has been collected on wood samples of 8 varieties of shrub willow. The energy content shows very little difference between these varieties of shrub willow. 5. Drying was done with ambient air over a 4-6 month period.

Publications