• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2005년도 춘계학술대회
• /
• pp.561-564
• /
• 2005

Gasification has been regarded as a very important technology to decrease environmental pollution and to obtain higher efficiency. The gasification process converts carbon containing feedstock into a synthesis gas, composed primarily of CO and $H_2$. And the synthesis gas can be used as a source for power generation or chemical material production. Through more than nine years, IAE developed and upgraded several gasification/melting pilot plant system, and obtained a good quality synthesis gas. This paper illustrates the gasification characteristics and operation results of two 3 ton/day synthesis gas production facilities. One is entrained-bed slagging type coal gasifier system which is normally operated in the temperature range of $1,400\~1,450^{\circ}C,\;8\~10$ bar pressure. And the other is fixed-bed type gasification/melting furnace system using MSW and industrial wastes as a feedstock.

• Asian-Australasian Journal of Animal Sciences
• /
• 제19권4호
• /
• pp.526-532
• /
• 2006

The aim of this study was to evaluate the chemical composition, in vitro DM degradability, ME and OMD of alfalfa-maize silage mixtures in comparison to pure maize and alfalfa silages, and to test the existence of associative effects of ensiling alfalfa forage with whole-crop maize using the in vitro gas production technique. Ensiling alfalfa with whole-crop maize had a significant (p<0.001) effect on chemical composition, pH, in vitro DM degradability, OMD and estimated ME values of mixtures. DM content of the resultant silages significantly increased with increasing proportion of whole-crop maize in the mixtures, whereas the pH value, crude protein (CP), acid detergent fibre (ADF) and ash contents of mixtures decreased due to the dilution effect of whole-crop maize which was low in CP, ADF and ash. The pH values of all alfalfa-maize silage mixtures were at the desired level for quality silage. Gas production of alfalfa-maize silage mixtures at all incubation times except 12 h increased with increasing proportion of whole-crop maize. When alfalfa was mixed with whole-crop maize in the ratio 40:60, ME and OMD values were significantly (p<0.001) higher than other silages. Maximum gas production ($A_{gas}$) ranged from 65.7 to 78.1 with alfalfa silage showing the lowest maximum gas production. The results obtained in this study clearly showed that maximum gas production increased with increased percentage of whole-crop maize in the silage mixtures (r = 0.940, p<0.001). It was concluded that ensiling alfalfa with whole-crop maize improved the pH, OMD and ME values. However, trials with animals are required to see how these differences in silage mixtures affect animal performance.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제15권1호
• /
• pp.34-45
• /
• 2007

In order to reduce the compression power and to use the overall energy contained in LNG effectively, a combined cycle is devised and simulated. The combined cycle is composed of two cycles; one is an open cycle of liquid/solid carbon dioxide production cycle utilizing LNG cold energy in $CO_2$ condenser and the other is a closed cycle gas turbine which supplies power to the $CO_2$ cycle, utilizes LNG cold energy for lowering the compressor inlet temperature, and uses the heating value of LNG at the burner. The power consumed for the $CO_2$ cycle is investigated in terms of a solid $CO_2$ production ratio. The present study shows that much reduction in both $CO_2$ compression power (only 35% of the power used in conventional dry ice production cycle) and $CO_2$ condenser pressure could be achieved by utilizing LNG cold energy and that high cycle efficiency (55.3% at maximum power condition) in the gas turbine could be accomplished with the adoption of compressor inlet cooling and regenerator. Exergy analysis shows that irreversibility in the combined cycle increases linearly as a solid $CO_2$ production ratio increases and most of the irreversibility occurs in the condenser and the heat exchanger for compressor inlet cooling. Hence, incoming LNG cold energy to the above components should be used more effectively.

• Asian-Australasian Journal of Animal Sciences
• /
• 제16권8호
• /
• pp.1151-1157
• /
• 2003

The surfactant Tween 80 was evaluated for its ability to influence cumulative gas production, cellulose digestion, and enzyme activities by mixed ruminal microorganisms grown on barley grain or Orchardgrass hay. The addition of Tween 80 at a level of 0.10% significantly (p<0.05) decreased the cumulative gas production rate from both barley grain or Orchardgrass hay substrates. However, 0.05% Tween 80 did not affect gas production rates compared to the control treatment. The addition of 0.05% Tween 80 to cultures growing on barley grain resulted in a significant increase in cellulase (90.01%), xylanase (90.73%) and amylase (487.25%) activities after 30 h incubation. Cultures utilizing Orchardgrass hay had a significant increase in cellulase (124.43%), xylanase (108.86%) and amylase (271.22%) activities after 72 h incubation. These increases in activities were also observed with cultures supplemented with 0.10% Tween 80 throughout all the incubation times tested. These results indicated that the addition of 0.05% Tween 80 could greatly stimulate the release of some of key enzymes without decreasing cell growth rate in contrast to trends reported with aerobic microorganism. Our data indicates potential uses of the surfactant Tween 80 as a feed additive for ruminant animals.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2002년도 추계학술대회 논문집
• /
• pp.119-123
• /
• 2002

Liquefied Natural Gas(LNG) continues to attract modern gas industries as well as domestic markets as their main energy source in the recent years. This is mainly because LNG is inherently cleaner and more energy efficiency than other fuels. Offshore LNG production plant is of interest to many oil producing companies all over the world. This article discuss about the production process encountered while developing such a production facility. Typical offshore oil and gas processing required for oil stabilization and other optional units that can be added to the facilities. The production process can broadly be divided into five major units namely, (i) Oil Stabilization unit, (ii) Gas Treatment unit, (iii) Methane Recovery unit, (iv) Distillation unit and (v) LNG Liquefaction unit. The process simulation was carried out for each unit with a given wellhead composition. The topside facilities of offshore LNG production plant will be very similar to the process adopted in offshore processing platform along with the typical onshore LNG production plant. However, the process design problems associated with FPSO motion to be taken care of while developing floating LNG production plant.

• 에너지공학
• /
• 제16권2호
• /
• pp.58-63
• /
• 2007

최근 신 고유가 시대를 맞이하여 천연가스를 이용한 합성석유 제조기술 개발의 중요성이 점차로 부각되고 있는 상황이다. GTL(Gas-to-Liquids) 공청은 현재의 고유가 상황에서 경쟁력 있는 사업 분야를 제공 할 것으로 분석되고, GTL 제품은 환경오염물질이 거의 없어 21 세기의 환경규제 강화 추세에 효과적으로 대응할 수 있는 청정연료이다. GTL 공정은 크게 천연가스의 주성분인 메탄의 리포밍 반응을 거쳐 합성가스 ($CO+H_{2}$)를 제조하는 단계, 이 합성가스로부터 FT 합성반응을 통하여 액체 합성원유를 제조하는 단계, 합성원유를 개질하는 단계 (수첨분해/수첨이성질화)로 이루어진다. 본 총설에서는 GTL 기술의 개요와 세계적인 개발 동향을 천연가스 reforming 기술과 FT 합성유 제조 기술에 중점을 두고서 소개하고자 한다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제27권1호
• /
• pp.36-45
• /
• 2014

The objective of this study was to determine the effects of protein sources and roughage (R) to concentrate (C) ratio on in vitro fermentation parameters using a gas production technique. The experimental design was a $2{\times}5$ factorial arrangement in a completely randomized design (CRD). Factor A was 2 levels of protein sources yeast fermented cassava chip protein (YEFECAP) and soybean meal (SBM) and factor B was 5 levels of roughage to concentrate (R:C) ratio at 80:20, 60:40, 40:60, 20:80, and 0:100, respectively. Rice straw was used as a roughage source. It was found that gas production from the insoluble fraction (b) of YEFECAP supplemented group was significantly higher (p<0.05) than those in SBM supplemented group. Moreover, the intercept value (a), gas production from the insoluble fraction (b), gas production rate constants for the insoluble fraction (c), potential extent of gas production (a+b) and cumulative gas production at 96 h were influenced (p<0.01) by R:C ratio. In addition, protein source had no effect (p>0.05) on ether in vitro digestibility of dry matter (IVDMD) and organic (IVOMD) while R:C ratio affected the IVDMD and IVOMD (p<0.01). Moreover, YEFECAP supplanted group showed a significantly increased (p<0.05) total VFA and $C_3$ while $C_2$, $C_2:C_3$ and $CH_4$ production were decreased when compared with SBM supplemented group. In addition, a decreasing R:C ratio had a significant effect (p<0.05) on increasing total VFA, $C_3$ and $NH_3$-N, but decreasing the $C_2$, $C_2:C_3$ and CH4 production (p<0.01). Furthermore, total bacteria, Fibrobacter succinogenes, Ruminococcus flavefaciens and Ruminococcus albus populations in YEFECAP supplemented group were significantly higher (p<0.05) than those in the SBM supplemented group while fungal zoospores, methanogens and protozoal population remained unchanged (p>0.05) as compared between the two sources of protein. Moreover, fungal zoospores and total bacteria population were significantly increased (p<0.01) while, F. succinogenes, R. flavefaciens, R. albus, methanogens and protozoal population were decreased (p<0.01) with decreasing R:C ratio. In conclusion, YEFECAP has a potential for use as a protein source for improving rumen fermentation efficiency in ruminants.

• Asian-Australasian Journal of Animal Sciences
• /
• 제21권9호
• /
• pp.1278-1285
• /
• 2008

Measurement of gas produced during in vitro fermentation was used to investigate the fermentation characteristics and interactions of rice straw, wheat straw or maize stover mixed with alfalfa or clover at proportions of 100:0, 75:25, 50:50, 25:75 and 0:100, respectively. Cumulative gas production was recorded at 2, 4, 8, 12, 16, 24 and 48 h of incubation, and the Gompertz function was used to describe the kinetics of gas production. In vitro dry matter and organic matter disappearances (IVDMD and IVOMD) were determined after 48 h incubation. The rate of gas production of clover was higher (p<0.05) than that of rice straw, wheat straw, maize stover and alfalfa when straws and hays were incubated separately. Increasing the proportion of alfalfa in the straw-alfalfa mixtures increased (p<0.05) the rates, but not the maximum volume of gas production. However, both rate and the maximum volume of gas production were increased (p<0.01) as the proportions of clover increased in the straw-clover mixtures. The cumulative gas production at 48 h, IVDMD and IVOMD showed no consistent interaction effects between different mixtures of cereal straws and hays. The extent of interactive effects was affected by the types of cereal straw, legume hay and their proportions in the mixture. The appropriate combination for the mixture of rice straw or maize stover with leguminous hays was 75:25 and 25:75, respectively. The better combination occurred at a proportion of 50:50 for the mixture of wheat straw and alfalfa. We conclude that the suitable proportion of low-quality straw and high quality legume hay combination should be considered in the ration formulation system of ruminants according to the extent of positive interactive effects.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 추계학술대회 초록집
• /
• pp.151.1-151.1
• /
• 2010

Natural gas hydrates (NGH) provide 170 gas volumes per unit volume of the medium and are easier to make with moderate pressure and temperature (40 bar at 3 C). Once they form, their preservation temperature is 20 C at 1 bar, which is much milder than the LNG preservation. In case of using the NGH, The small and medium sized gas well has advantages for development because of NGH's these characteristics. According to the cost evaluation report of Gudmundsson in Norway and the research of MES in Japan, the gas well that uses the NGH has a cost saving effect about 10~20% compared LNG. The effect depends on distance and production. However, cost saving and efficiency of liquefaction process is increased by the development of LNG liquefaction technology. Therefore, these factors have to be reflected in economic analysis. The purpose of this research is to compare the cost of Gas Supply Chain according to the transport type, distance and gas reserves. Especially, we consider not only the cost of facility but also the total cost (production cost, transport cost, etc).

• 한국석유지질학회지
• /
• 제14권1호
• /
• pp.36-44
• /
• 2008

비재래형 탄화수소 자원의 하나인 치밀저류층 내의 천연가스는 중요한 탐사개발 대상이 되고 있다. 치밀가스 저류층은 가스를 배태하고 있는 저류암으로서 투수율이 0.1 md 미만인 저류층을 말한다. 치밀가스 저류층은 광범위하게 두꺼운 층으로 산출되며, 재래형의 가스 집적체와는 달리 과대압력이나 저압력의 비정상적인 압력상태로 나타나는 것이 특징이다. 재래형 가스가 구조트랩이나 층서트랩에서 산출되는 것에 비하여 치밀가스는 이들 트랩들과는 무관하게 산출되고 있다. 치밀저류층에서 가스를 생산하기 위해서는 수압파쇄(hydraulic fracturing)와 같은 인공 자극법에 의해서만 가능하다. 치밀가스 저류층의 최적 생산지역을 스위트 스폿이라고 하며, 생산성을 높이기 위해서는 지질학적 자연균열 상태를 이해하여야 한다. 친환경 연료자원으로 주목을 받고 있는 치밀가스는 탐사기술과 회수방법이 발전함에 따라서 상업적으로 생산되고 있다. 자연균열대를 가로지르는 방향으로 수평시추나 경사시추를 수행할 때 생산성을 극대화할 수 있다. 실제로 미국과 캐나다 등에서는 치밀저류층에서 많은 양의 가스를 생산하고 있으며, 생산량은 해마다 증가하고 있다. 특히, 미국의 치밀사암층에서 생산되는 가스의 경우 1990년에 미국의 총 가스 생산량의 11.1%를 차지하였지만 2005년에는 총 가스 생산량의 24.1%를 차지하고 있다. 국내 대륙붕에서도 치밀가스의 존재 가능성이 제시되고 있으며 이를 개발하기 위해서는 기존의 재래형 가스자원의 탐사 및 개발의 파라다임을 완전히 바꾸는 것이 필요하다.