초록

○ 연구결과
1) 주요 수종별 산림 폐 바이오매스 자원의 공급량 추정
2) 농가에서 직접 이용가능한 소규모 고효율의 발효열교환장치 개발
3) 폐 바이오매스의 종류별, 혼합비별 발효 프로세스 구명

Abstract ▼

Ⅳ. Results of Project and Suggestion for Application
Forest biomass of Quercus mongolica, Pinus densiflora, Pinus koraiensis, Larix kaemferi and Pinus rigida was estimated. Fermentation process with agricultural and forest biomass was obtained. Fermentation-heat exchanger for those biomass uses w

Ⅳ. Results of Project and Suggestion for Application
Forest biomass of Quercus mongolica, Pinus densiflora, Pinus koraiensis, Larix kaemferi and Pinus rigida was estimated. Fermentation process with agricultural and forest biomass was obtained. Fermentation-heat exchanger for those biomass uses was developed and analyzed for the cost. Fermentation of those products as bio-fertilizers was investigated.
1. Supply and utilization technology of forest waste biomass
Forest biomass accumulation in Korea is increasing now, and a large quantity of forest waste biomass such as thinned logs has been produced annually. Biomass and annual net production of five most common tree species - Quercus mongolica, Pinus densiflora, Pinus koraiensis, Larix kaemferi and Pinus rigida were investigated.
In Mt. Wolak, Chungbuk, biomass accumulation of 35-year-old Quercus mongolica stand in north slope was 104.2 ton/ha in stem (53.1 ton/ha in sapwood, 51.1 ton/ha in heartwood), 18.5 ton/ha in bark, 26.4 ton/ha in living branches, and 8.2 ton/ha in leaves, totally 198.8 ton/ha for above ground, and 41.4 ton/ha for below ground at 300m above sea level. annual net production was 6.1 ton/ha/yr for stems, 0.9 ton/ha/yr, 1.6 ton/ha/yr and 8.1 ton/ha/yr for barks, living branches, and leaves respectively. Total above ground annual net production was 16.8 ton/ha/yr while below ground annual net production was 4.4 ton/ha/yr. Total annual net production in Q. mongolica was 21.2 ton/ha/yr.
Biomass of 5 ton/ha, which was as much as 3-year-growth, would be produced if 20% of pruning is applied. Above biomass of 16ton/ha, which was as much as 1-year-growth, would be produced if 10% of thinning is applied.
In Mt. Jungwang, Kangwon-do, biomass accumulation of 60∼0-year-old Q. mongolica stand was 137.5 ton/ha in stems (65.8 ton/ha in sapwood, 71.7ton/ha in heartwood), 16.3 ton/ha in barks, 54.3 ton/ha in living branches and 3.8 ton/ha in leaves, and totally 211.9 ton/ha above the ground while 40.7ton/ha bellow the ground. Total biomass accumulation in north slope was 212.3ton/ha at 1000m above sea level. annual net production was 6.5 ton/ha/yr in stems, 0.7 ton/ha/yr in barks, 3.3 ton/ha/yr in living branches, and 4.1ton/ha/yr in leaves. Thus, total above ground annual net production was 14.5ton/ha/yr while below ground annual net production was 2.8 ton/ha/yr in north slope. Estimated annual net production was 14.2 ton/ha/yr. Total biomass in north slope was greater than that in south slope. It seemed that it was because there was larger portion of leaves and branches that function important roles in photosynthesis and sapwood transporting water in north slope than in south slope.
In Mt. Wolak, Chungbuk, biomass accumulation of 45-year-old Pinus densiflora stand was 187.0 ton/ha in stems, 61.3 ton/ha in branches and 31.7 ton/ha in leaves. The total of 280.4 ton/ha above the ground was shown at 300m above sea level, in eastern slope. Estimated annual net production was 17.0 ton/ha/yr. Compared to 35-year-old Q. mongolica stand in Mt. Wolak, biomass production of P. densiflora stand was abundant while annual net production was similar. It was because of great leaf biomass of P. densiflora stand. Biomass of 6 ton/ha, which was as much as 4-year-growth, would be produced if 10% of pruning is applied. Above ground biomass of 28 ton/ha, which was as much as 2-year-growth, would be produced if 10% of thinning is applied.
In Mt. Wolak, Chungbuk, biomass accumulation of 45-year-old Pinus koraiensis stand was 26.6 ton/ha in stems, 4.3 ton/ha in barks, 0.2 ton/ha in 1-year-old branches, 8.6 ton/ha in branches, 1.3 ton/ha in 1-year-old leaves and 6.1 ton/ha in 2-year-old leaves. The total of 47.0 ton/ha above the ground except for dead branches was shown at 380m above sea level, in eastern north slope. Annual net production was 3.0 ton/ha/yr in stems, 0.4 ton/ha/yr in barks, 0.2 ton/ha/yr in 1-year-old branches, 101 ton/ha/yr in branches, and 1.3ton/ha/yr in 1-year-old leaves. Thus total above ground annual net production was 6.0 ton/ha/yr while below ground annual net production was 2.8 ton/ha/yr in north slope. Dead branches and trees were produced by severe competition, which needs urgent pruning and thinning. Biomass of 2.6 ton/ha would be produced if 30% of pruning is applied. Above biomass of 9.4 ton/ha would be produced if 20% of thinning is applied. About 8 years after pruning or 1∼year after thinning was required to recover its annual net production. But more vigorous growth was expected because it was just at young stage.
In Mt. Wolak, Chungbuk, 30-year-old Larix kaemferi plantation stand was the area in south slope (520m from sea level) where thinning of 20% was applied in 1996. Biomass accumulation of L. kaemferi stand was 286.8 ton/ha in stems, 68.7 ton/ha in branches and 31.1 ton/ha in leaves, and the total was 386.6 ton/ha above the ground. Annual net production was 18.1 ton/ha/yr in stems, 5.5 ton/ha/yr in branches, and 31.1 ton/ha/yr in leaves. Total above ground annual net production was 54.7 ton/ha/yr. L. kaemferi stand was just after young stand stage, and annual leaf production was high. Natural pruning occurs commonly in L. kaemferi stand, and pruning above 10m in height was too difficult. Biomass of 58 ton/ha, which was as much as 1-year-growth, would be produced if 20% of thinning is applied.
Mt. Taehwa in Kyeonggi-do is the site where 36-year-old Pinus rigida plantation stand was not thinned at all in western north slope (250m from sea level). Thus, many dead branches and trees were occurred. Biomass accumulation of P. rigida stand was 243.7 ton/ha in stems, 32.8 ton/ha in barks, 76.3 ton/ha in branches, 23.4 ton/ha in dead branches, 5.5 ton/ha in 1-year-old leaves, 9.6 ton/ha in 2-year-old leaves, and 1.84 ton/ha in cones, The total was 396.8 ton/ha above the ground except for dead branches. Annual net production was 24.5 ton/ha/yr in stems, 2.6 ton/ha/yr in barks, 8.3ton/ha/yr in branches, 5.5 ton/ha/yr in 1-year-old leaves, and 1.84 ton/ha/yr in cones. Estimated total above ground annual net production was 42.8 ton/ha/yr. P. rigida is shade-intolerant species, and is well pruned naturally. However biomass production by pruning was quite small. On the other hand, biomass of 74 ton/ha, which was as much as 1∼-year-growth, would be produced if 20% of thinning is applied because P. rigida grew very well.
In summary, the largest quantity of biomass seemed to be obtained in 36-year-old P. rigida plantation and 30-year-old L. kaemferi plantation by thinning. 24-year-old P. koraiensis plantation needed both of pruning and thinning. 35-year-old Q. mongolica stand seemed to produce biomass of 20ton/ha by 10% thinning. A careful thinning and pruning is needed to P. densiflora stand because of its slow growth.
2. Optimum fermentation technology of agricultural and forest waste biomass
According to recent high oil price, worldwide interests in alternative energy resources instead of fossil fuels have been focused, and above all utilization of plant biomass for energy is especially highlighted. Lignocelluloses resources are the most abundant source on the earth, and are obtainable as the original biomass on the land and residues or by-products, and even as municipal solid wastes. Recently the use of lignocellulose resources as a source for fuel and heat energy production becomes more attractive.
In this study, fermentation characteristics of agricultural and forest waste biomass for production of heat energy were focused to be used in agricultural farm households. Fermentation process was examined in terms of different raw-materials and their mixture with different ratios. Eventually the optimum fermentation condition through careful investigation on various factors, such as raw-materials, moisture contents, fermenting aids, and practical measurement of hot-water temperature during fermentation were investigated. In addition, reutilization of fermentation residues, the effect of these organic biocomposts on the seed, plant growth and soil temperature were discussed.
Fermenting aids were urea, lime, and bioaid. Moisture contents of fermenting substrates were adjusted by 55-60%.
1) Fermentation process of softwood and hardwood beds during winter season shows almost similar temperature patterns. Temperature increased in first and second weeks to be about 42∼8℃, and then maintained approximately around 50℃. Later it gradually decreased. Maintenance period around 50℃ was longer in hardwood (10-14 days) than in softwood (8-12days).
2) Fermentation process during summer season showed different results. Bed temperature abruptly increased for hardwood than softwood, and then slowly decreased and maintained approximately around 42-52℃ for one month.
During fermentation in summer season, bed temperatures abruptly increased in hardwood (74℃ on 5th day after piling) than softwood (64℃ on 14th day after piling), and afterward slowly decreased and maintained to 42∼2℃ for one month.
In the case of grasses and hardwood, almost similar temperature patterns was shown during fermentation process. Bed temperature quickly increased up to 38℃ at upper part, while 80℃ at mid- and lower- parts on the second day after piling, and then rapidly decreased to 30℃ on the sixth day.
3) The results of substrates and their mixtures with different ratios on fermentation process were as follows; hardwood bed showed highest
temperature (high temperature of 65∼4℃, average temperature of 40∼0℃) followed by hardwood: softwood mixture (highest temperature were 58∼0℃ with average temperature of 35∼5℃) and hardwood: grass mixture bed (highest temperature approximately 58∼0℃ and average temperature of 50∼"55℃), respectively.
In particular, increased application of fermenting aids, with 15 kg from 10 kg urea and 20 kg from 15 kg bioaid, has resulted in high temperatures of 80∼0℃ (average temperature of 50∼0℃, and with 20∼0 days of maintaining periods).
In conclusion, the best fermenting results were obtained from hardwood only and hardwood: softwood (50:50) beds (high temperatures of 60∼0℃, more or less 40℃ low temperature with average temperature of 50∼0℃ and 20∼0days of maintaining periods). Optimum additives per ton of substrates were 15kg of urea, 20 kg of bioacid, and 10 kg of lime.
4) The results of fermenting substrate moisture content shows that 55% was the optimum for highest temperature among three moisture content treatments 45%, 55% and 65%. The low (45%) and high (65%) moisture content of substrates have shown lower temperature compared to 55% moisture content of substrates.
5) The temperature of hot-water tank installed in fermenting bed of hardwood:grass (50:50) showed very different temperature patterns according to measurement positions. In general, measurement of mid- and upper-parts showed higher temperature than lower and surface parts during 45-day fermentation process. The temperature of initial fermenting stage was 40∼0°C, and that of later stage, 32∼0℃. Average temperature of the tank ranged approximately 30∼5℃.
6) Further utilization of fermenting residues from hardwood sawdust and grass was examined whether those could be an organic soil conditioner for growth of radish and tree seedlings.
The results of chemical analysis for fermenting residues were almost same in all residues of hardwood, softwood and grasses, 20.7∼8.6% of high organic matter, 0.88∼.41% nitrogen, pH = 6.75 and C/N ratio = 25∼0, except higher concentration of Ca in hardwood and potassium in grass.
No harmful effect was discovered on germination and positively affected plant growth, such as radish and softwood and hardwood seedlings. Also fermenting residues did not affect soil temperature change, but increased daily soil temperature fluctuation, such as small increase in the early morning, a small decrease in the mid-day or afternoon (2:00pm), and increased in the early evening (6:00 pm). This compensating effect became higher with increasing contents of organic residues.
3. Development of heat exchanger for biomass fermentation
Waste heat recovery system was studied numerically and experimentally. In the present study, heat exchangers for biomass fermentation were developed as a waste heat recovery system. The developed heat exchanger is a system to supply the hot water using fermentation of waste biomass. Heat exchanger systems were designed specially to obtain the optimum heat exchanging performance.
For the experiments, various biomass materials were examined to obtain the best heat recovery. Sawdust of softwood, hardwood and grasses were used for the present experimental study. Eight biomass heat recovery systems were designed. The developed heat exchangers kept farm households warm by providing. They were concentrated to improve the overall efficiency of their heat capture system. One obvious way to minimize heat loss at the atmosphere was to build the piles in a circular fashion, which offered less surface area for a given volume. Furthermore, such an approach promised to simplify both the assembly and the tearing down of the heaps. The basis of the present cylindrical compost pile was similar to some sort of tower built from steel frame, which will hold the inner brush in place. One example incorporates a retainer 2 m in diameter and 1.5 m tall. Once the tower has been filled with brush clippings, polyethylene helical (0.03 m I.O) and plate
type(0.2 m IO) pipe line were installed to recover the heat from biomass
fermentation. The intake and exhaust ends of the pipes should be connected to
form a closed loop running to and from the building being heated.
The fermentation process of biomass dump was maintained for maximum 3
months with HX 8 (Plate Type). While composting goes on, the bacterial
activity within a biomass dump produces a considerable amount of heat,
averaging about 50-65°C. Thus, it was possible to tap a significant source of
thermal energy by intertwining heat exchanging pipes throughout the interior
of the stack. The current heat recovery system could recover over daily
average usage (16,500 kcal/day). The optimum state of biomass heat exchanger
was obtained from HX 8 (plate type). The composition of HX was 90 % of
wood sawdust and 10 % of grasses. If waste logs obtained from thinning may
reach diameters of up to 50 cm, then heavy duty machinery may be needed to
chip the wood. Though the shavings may be as much as an 2 cm long, the
ideal thickness is about 5 mm.
The present developed heat exchanger with 1 ton of those biomass could
heat a room, and produce hot water for at least 3 months.

목차 Contents

• 표지 ... 1
• 제출문 ... 2
• 요약문 ... 3
• SUMMARY ... 13
• CONTENTS ... 22
• 목차 ... 23
• 제1장 연구개발과제의 개요 ... 24
• 1) 기술적인 측면 ... 25
• 2) 경제.산업적 측면 ... 26
• 3) 사회.문화적 측면 ... 27
• 제2장 국내외 기술개발 현황 ... 28
• 1) 국내 기술 현황 ... 28
• 2) 국외 기술 현황 ... 28
• 제3장 연구개발수행 내용 및 결과 ... 30
• 제1절 산림 폐 바이오매스 자원의 현황과 공급 방안 ... 30
• 제2절 산림 폐 바이오매스의 최적 발효 기술 개발 ... 94
• 제3절 발효열 이용 열교환기 개발 ... 113
• 제4절 산림 폐 바이오매스 자원의 발효 후 활용 방안과 경제성 분석 ... 203
• 제4장 목표달성도 및 관련분야에의 기여도 ... 217
• 1. 산림 폐 바이오매스 자원의 공급 및 활용 기술 개발 ... 217
• 2. 산림 및 농산 폐 바이오매스의 최적 발효 기술 개발 ... 218
• 3. 발효열 이용 열교환기 개발 ... 218
• 제5장 연구개발결과의 활용계획 ... 220
• 제6장 연구개발과정에서 수집한 해외과학기술정보 ... 222
• 제7장 참고문헌 ... 224
• 끝페이지 ... 235