Improving of drying time and color of juvenile wood of Tectona grandis in kiln

dry

Róger Moya Roque, TEC

Alexander Berrocal Jimenez; TEC

María Rodríguez, TEC

Brain Bond, VT

Freddy Muñoz, TEC

SWST 2016, Curitiba, Brazil

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• Tectona grandis is a important species in tropical climates for commercial reforestation.

• This species was planted over 4.5 million ha in 52 different countries.

• Teak wood is well known in the international market for its durability, excellent mechanical,

and exceptional esthetical properties.

• On the other hand, Indian Dealer came to different America countries to buy log or block

with lower price. This situation produced that economy of plantation are low, then planter

or different company do no believe in teak plantation.

• Then, the objective of American country is produce dried lumber, therefore the price of

lumber increase.

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But, there is a several problem for reaching more competitive lumber in international market:

• Teakwood has relatively long drying times in relationto other tropical species.

• For example radiata pine is dried from 70-80 hours(Ananias et al, 2012).

• Additionally, the colour of the teakwood from trees grown in plantation condition is lighter than the colour of the wood from trees from natural forests

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the objective for this study is to decrease drying

time of Tectona grandis wood from juvenile fast-

growing plantations, using drying rate with three

different drying schedules. Besides it was evaluate

the effect of electricity consumption and reduction

of drying defects (twist, crook, bow, cup, check

and split).

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Plantation parameter

A second thinning of an 11 year old Tectona grandisplantation. The stand density was 475 trees ha-1, with an average diameter at breast high of 23 cm and total height of 14 m.

Sawing pattern

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Step

Drying schedule standard

(DS-1)

Drying schedule 2

(DS-2)

Drying schedule 3

(DS-3)

NumberDBT/WB

T ºCEMC %

EMC

change

(%)Number

DBT/WBT

ºCEMC %

EMC

change

(%)Number

DBT/WB

T ºC

EMC

%

EMC

change

(%)

Heating1 55/- - - 1 55/- - - 1 55/- - -

2 58/54 14.0 - 2 58/54 14.0 - 2 58/54 14.0 -

Drying

1 60/56 13.8 - 1 60/56 13.8 - 1 58/54 13.8 -

2 60/52 10.0 3.8 1-a 60/54 12.5 1.3 1-a 60/54 12.5 1.5

3 70/58 7.7 2.3 2 60/52 10.0 2.5 2 60/52 10.0 2.5

4 70/55 6.4 1.3 2-a 65/55 8.5 1.5 2-a 65/55 8.5 1.5

5 75/50 3.7 2.7 3 70/58 7.7 0.8 3 70/58 7.7 0.8

3-a 75/58 6.4 1.3 3-a 75/60 6.4 1.3

4 75/55 5.2 1.2 4 80/60 5.0 1.4

5 75/50 3.7 1.5 5 80/55 3.7 1.3

Equaliza

tion75/70 11.0

-75/70 11.0

-80/74 11.0

-

Conditio

ning75/68 11.5

0.575/68 11.5

0.580/75 11.5

0.5

Cooling 35/28 11.5 - 35/- - - 35/- - -6

Endless screw location in lumber stacked in

piles; and (b) nuts and washer in endless screw

for daily adjustment during drying. 7

Moisture content and drying rate

• Six samples were obtained from the centre of six stacked representative boards for each drying method. The target MC indicated in the drying schedule was 12%.

• These samples were placed at different heights in the charge and were weighed each 8 hours to obtain the drying rate and after, to obtain the relationships between drying rate (DR).

)(

)(%)(%)()/(%

hrstsmeasurementwobetweentime

hoursotheratmeasuredMChoursoneatmeasuredMChrsrateDrying hours

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Energy compsumtion and drying defects

• Energy input used during drying The energy used for each drying charge and schedule was determined by measuring the electric power consumption (kWh). The electricity input is defined as the total electrical energy used for drying.

Drying defect evaluation Warp (twist, crook, bow and cup), cracks and splits were measured both before and after drying using. The methodology of Hallock and Malcom (1972), Milota (1996) were used for warp defects and Shmulky and Dahlen (2007) was used to evaluate cracks and splits. The Chilean standard Nch993EO72 was used to determine the Index of quality (IQ) for twist, crook, cup and bow parameters.

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Results

Drying

Schedule

Initial MC

(%)

Final MC

(%)

Drying Time

(h)

Average Drying

Rate

(% hours-1)

DS-

standard 111 (20.1) A 12.58 (8.8) A 125 0.90

DS-2 92 (19.4) B 11.74 (8.0) B 140 0.57

DS-3 106 (18.7) C 12.74 (8.6) A 105 1.03

Initial and final moisture content, drying time and average drying

rate for the three evaluated drying schedules for juvenile wood of

T. grandis.

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Drying rate and Moisture content

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Drying rate and drying time

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Energy consumption

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Drying

ScheduleEvaluation Twist Crook Bow Cup Check Split

Classification

DS-standard Excellent GoodVery

goodVery good Very good

Very

good

DS-2 without

endless screwsVery good Good Good Very good Good Good

DS-2 with endless

screwsVery good Very good

Very

goodVery good Very good

Very

good

DS-3 without

endless screwsVery good Good Good Very good Very good

Very

good

DS-3 with endless

screwsVery good Good

Very

goodVery good Very good

Very

good

Classification of dried-lumber obtained for

different drying Tectona grandis wood.

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• Finally, the best drying treatment for juvenile T.grandis lumber, taking as reference index ofquality for drying defects (“very good” and“excellent”) and drying stresses (low tomoderate), would be the DS-3 without endlessscrews for reduce drying time and for woodquality maintaining.

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Gracias/thank/Obrigado

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