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Title:
METHOD AND ARRANGEMENT FOR DRYING A BIOMASS PILE
Document Type and Number:
WIPO Patent Application WO/2017/093901
Kind Code:
A1
Abstract:
Arrangement for drying an oblong biomass pile (1). The arrangement comprising an air-pocket device (2), which is arranged at the top of the pile, wherein the air-pocket device is in air-through contact with the top of the pile, at least one motor-fan (3), which is arranged on top of the air-pocket device (2), which fan (3) blow air (7) out from the air-pocket device, such that moisture are removed from the air-pocket, and a water protected flexible cover (5a, 5b), which cover at least the upper part of the chip pile, preferably more than half the height of the chip pile from the top, wherein at least some parts of the pile are not covered, such that air can pass from the outside of the pile and move upwards through the top of the pile to the air-pocket device.

Inventors:
MANNINEN TEEMU (FI)
Application Number:
IB2016/057197
Publication Date:
June 08, 2017
Filing Date:
November 30, 2016
Export Citation:
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Assignee:
STORA ENSO OYJ (FI)
International Classes:
F26B9/10; F26B3/32
Domestic Patent References:
WO2012155145A22012-11-15
WO1990007685A11990-07-12
WO2010040900A12010-04-15
WO1989000185A11989-01-12
Foreign References:
FI10575U12014-08-15
DE4436209A11996-04-04
Other References:
PARI, L. ET AL.: "Poplar Wood chips storage: effect of particle size and breathable covering on drying Dynamics and biofuel quality", BIOMASS AND BIOENERGY, vol. 81, July 2015 (2015-07-01), pages 282 - 287, XP029269188, ISSN: 0961-9534
BEDANE, A.H. ET AL.: "Simulation of temperature and moisture changes during storage of woody biomass owing to weather variability", BIOMASS AND BIOENERGY, vol. 35, no. 7, July 2011 (2011-07-01), pages 3147 - 3151, XP055387313, ISSN: 0961-9534
See also references of EP 3384220A4
Attorney, Agent or Firm:
MAGNUSSON, Ulf (Group IPBox 9090, Karlstad, SE)
Download PDF:
Claims:
C L A I M S

1. Arrangement for drying an essentially oblong biomass pile (1), characterized in that the arrangement

comprising :

- a lengthwise air-pocket device (2), which is

arranged at the top of the pile, which device creates an air-pocket throughout the upper part of the oblong chip pile, wherein the air-pocket device is in air-through contact with the top of the pile,

- at least one motor-fan (3), which is arranged on top of the air-pocket device (2), which fan (3) blow air (7) out from the air-pocket device, such that moisture and/or versatiles from the pile are removed from the air-pocket, and

- a water protected flexible cover (5a, 5b), which cover at least the upper part of the chip pile, preferably more than half the height of the chip pile from the top, wherein at least some parts of the pile are not covered, such that air can pass from the outside of the pile and move upwards through the top of the pile to the air-pocket device .

2. Arrangement according to claim 1, characterized in that the cover (5a) is covering the upper part of the pile (1) and more than half of the pile, but the lower part of the pile is uncovered, wherein air (6) can pass through the uncovered pile and into the pile.

3. Arrangement according to claim 1, characterized in that the cover (5b) is covering the pile and comprising one or several holes, wherein air (6) can pass through the holes into the pile.

4. Arrangement according to any of claims 1-3,

characterized in that the oblong air-pocket device (2) is covered with an insulating cover (4) .

5. Arrangement according to any of claims 1-4,

characterized in that the oblong air-pocket device is located on the top of the pile, and covered by chips and bark .

6. Arrangement according to any of claims 1-5,

characterized in that the oblong air-pocket device is a horizontal half cut air pipe with a diameter of 400-1000 mm, preferably about 800 mm.

7. Arrangement according to any of claims 1-6,

characterized in that several motor-fans are located throughout the oblong air-pocket device, wherein the distance between the motors are maximum 20 meter.

8. Arrangement according to any of claims 1-7,

characterized in that the motor fan capacity on each motor is about 2300 m3 air/h on a free run.

9. Arrangement according to any of claims 1-8,

characterized in that the size of the chip pile is about 4-6m x 10-20m x 50-100m (height x width x length) .

10. Arrangement according to any of claims 1-9,

characterized in that the arrangement also comprising equipment for monitoring temperature, moisture and VOC .

11. Method for drying biomass, wherein the method comprising the steps of:

- forming an oblong pile (1) of the biomass, wherein the pile has an height of 4-6 m, a width of 10-20 m and a predetermined length,

- placing a lengthwise air-pocket device (2) at the top of the oblong pile, which device creates an air-pocket throughout the upper part of the oblong chip pile,

- protecting the pile with a cover (5a, 5b),

- leaving at least some areas of the pile unprotected, in order to let air pass into the pile, and

- blowing air out from the air-pocket device.

Description:
Method and arrangement for drying a biomass pile

Technical field

The invention relates to an arrangement and a method for drying a biomass pile. Biomass in this context is wood chips, bark or a sludge mix of bark.

Prior Art - Problem

A problem when drying a biomass pile is to efficiently remove the moisture from the biomass and volatile compounds. Various solutions have been disclosed in the prior art demonstrating various solutions to enhance replacement of the air in the pile by using fresh air replacement systems, suction pipes or tubes in the pile etc. These solutions are, however, quite complicated and requires high investment costs.

Another problem of using suction pipes is that the point of suction is very limited. Another problem is if the suction pipe is very long, the risk of re-condensation increases. Thus, there is a need to improve the removal of moisture and other volatile gases. Figure 1 discloses is a schematic view of a prior art of a normal solution used to remove moisture from a wood chip pile. Fresh air is introduced at the bottom of the pile and hot air is removed from the pile at the top of a long suction pipe.

Summary of the invention

The arrangement in accordance with the invention

comprising :

- a lengthwise air-pocket device, which is arranged at the top of the pile, which device creates an air-pocket throughout the upper part of the oblong chip pile, wherein the air-pocket device is in air-through contact with the top of the pile,

- at least one motor-fan, which is arranged on top of the air-pocket device, which fan blow air out from the air-pocket device, such that moisture and/or versatiles from the pile are removed from the air-pocket, and

- a water protected flexible cover, which cover at least the upper part of the chip pile, preferably more than half the height of the chip pile from the top, wherein at least some parts of the pile are not covered, such that air can pass from the outside of the pile and move upwards through the top of the pile to the air-pocket device.

The method in accordance with the invention comprising the following steps:

- forming an oblong pile of the biomass, wherein the pile has an height of 4-6 m, a width of 10-20 m and a

predetermined length,

- placing a lengthwise air-pocket device at the top of the oblong pile, which device creates an air-pocket throughout the upper part of the oblong chip pile,

- protecting the pile with a cover,

- leaving at least some areas of the pile unprotected, in order to let air pass into the pile, and

- blowing air out from the air-pocket device.

Detailed description of the invention

In the following, the invention will be described further with reference to the drawings, wherein: Figure 2 discloses a first embodiment of an arrangement for drying a biomass pile in accordance with the

invention . Figure 3 discloses a second embodiment of an arrangement for drying a biomass pile in accordance with the

invention .

It has surprisingly been found that the method and arrangement for drying an essentially oblong biomass pile, in accordance with the invention, enhances the drying capacity and reduces the risk of self-ignition in respect of prior art. In accordance with the invention, the biomass pile 1 is formed with specific dimensions. The height (h) of the pile is in the range 4-6m and the width (w) is in the range 10-20 m, preferably about 15 m. These dimensions have shown to be the most effective when it comes to effectiveness of the de-moisturizing of the pile. The length of the pile are not that crucial, but longer than 100 m is normally not practical.

On top of the oblong pile 1 is a lengthwise air-pocket device 2 arranged, which creates an air-pocket 2

throughout the upper part of the oblong biomass pile, wherein the air-pocket device is in air through contact with the pile. Preferably, the oblong air-pocket device 2 is a half cut air pipe with a diameter of 400-1000 mm, preferably about 800 mm.

One or several motor fans 3, dependent on the length of the pile/air-pocket device, are arranged on top of the air-pocket device 2, which fans 3 blowout hot air 7 from the air-pocket device 2, such that moisture and/or versatiles from the pile 1 are removed from the air- pocket. The distance between two adjacent motor fans are not more than 20 m. The capacity of each motor fan is about 2300 m 3 air/h on a free run.

The effectiveness of the drying capacity is increased if the oblong air-pocket device 2 is insulated. This may be done by covering the outside of the air-pocket device with chips and/or bark. However, a preferred solution is to cover the air-pocket device with an insulated,

flexible cover 4, such as a flexible plastic foam cell 4. Thus, the moist air and gas removal unit is free from a suction pipe as needed in prior art.

Fig. 2 discloses a first embodiment of the invention, wherein a water protected, flexible cover 5a, e.g. a tarpaulin, is covering the upper and mid-section of the biomass pile 1. The cover 5a protects the pile from rain and moisture. The lower part of the pile is free from covering so that air 6 can pass through the pile and move upwards to the air-pocket device 2 above the pile 1, such that the biomass in the pile dries. The accumulated gas and moisture from the pile is blown out 4 via the motor fan 3.

Fig. 3 discloses a second embodiment of the invention wherein a water protected, flexible cover 5b, e.g. a tarpaulin, is covering the whole pile from the top and down to the bottom of the pile. The cover 5b protects the pile from rain and moisture. Holes 8 are arranged through the cover 5b at the lower region of the pile 1. Air 6 passes through the holes and into the pile, wherein the air move upwards to the air-pocket device 2 above the pile 1, such that the biomass in the pile dries. The accumulated gas and moisture from the pile is blown out 4 from the air-pocket via the motor fan 3. A major benefit with this embodiment is that the cover 5b also protects the pile in connection to the ground. This results in that the pile is protected from water that might flow against the pile such as i.e. melt water, rivers, flood etc .

The flexible, cover 5a, 5b helps the warm air inside the pile to move upwards to the top of the pile and also to keep the pile dry and warm.

The temperature in the biomass pile during drying is quite high because of biological action within the pile. For example a winter day in Finland with -11°C outside, the temperature about 1 meter down in the pile is about +60°C.

In order to optimize the drying capacity of the pile, the arrangement also comprising equipment for monitoring temperature, moisture and VOC . The invention allows the harvesting and plantain season to be radically changed due to shorter drying time of the energy biofuel.

Logistic advantages, the heating value rises in material because of higher density and less amount of moisture. Tests of wood chips has shown that the humidity content in this system will go from 45-65% down to about 20-30%. It takes about 3 months for a pile in accordance with the invention to dry from 45-65% down to 20-30%. The energy content of wood chips with a humidity content of 65% is as low as 1.4 MWh/ton chips, while the energy content of wood chips with a humidity content of 25% is as high as 3.8 MWh/ton chips. The energy content in a truck load is 65.5 MWh/truck at 65% and 143.9 MWh/truck at 25%.

As can be seen from the table below, the density of the chips rises when the biomass dries. This is because the volume of the biomass shrinks during drying.

In the foregoing, the invention has been described on the basis of some specific embodiments. It is appreciated, however, that other embodiments and variants are possible within the scope of the following claims.