• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.81-88
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• 2015

바이오매스는 유망한 신재생 에너지이다. 바이오매스는 액체 및 기체 연료로 전 환 할 수 있고, 다양한 공정을 통해 열 및 전력을 생산시키는데 사용된다. 바이오매스 가스화 공정은 바이오매스를 일산화탄소, 이산화탄소, 수소 및 메탄으로 이루어진 합성 가스로 전환시키는 기술이다. 바이오매스를 이용한 합성 가스 생산 및 활용은 세계적으로 늘어나는 에너지 필요성을 충족시킬 수 있는 대체에너지이다. 현재, 바이오매스 가스화의 주요 원료는 목질계 우드 칩을 주로 사용하고 있지만, 일반적으로 우드칩의 경우 수분을 다량 함유하고 있기 때문에 가스화 공정을 위해서는 별도의 건조처리를 필요로 한다. 우드칩의 건조에는 많은 에너지가 소요되고, 다량의 우드칩 건조에는 시간과 기상 및 공간적인 환경에 영향을 받는다. 본 연구에서는 미건조 우드칩의 가스화 공정을 위하여 미건조 우드칩에 숯을 각각 10, 30, 50 % 비율로 혼합하여 실험을 수행하였고, 실험결과 생산된 합성가스의 CO 농도 는 숯의 비율에 따라 14.9 ~ 25.6 % 증가되는 경향을 나타내었지만, 반대로 $CO_2$ 및 $CH_4$ 농도는 감소하였다. 이에 따라 합성가스 생산을 위한 미건조 우드칩과 숯의 최적혼합비율은 약 30 %로 판단되며, 발열량은 $1285.7kcal/Nm^3$, Gas yield는 $2.3Nm^3/kg$ 로 나타났다. 이에 적절한 숯의 혼합사용은 미건조 우드칩의 직접적인 가스화에 도움이 될 것으로 사료되며, 바이오매스 건조 공정에 필요한 에너지를 절약할 수 있을 것으로 판단된다.

• Clean Technology
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• v.23 no.2
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• pp.121-132
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• 2017

The increase of greenhouse gases and the concern of global warming instigate the development and spread of renewable energy and hydrogen is considered one of the clean energy sources. Hydrogen is one of the most elements in the earth and exist in the form of fossil fuel, biomass and water. In order to use hydrogen for a clean energy source, the hydrogen production method should be eco-friendly and economic as well. There are two different hydrogen production methods: conventional thermal method using fossil fuel and renewable method using biomass and water. Steam reforming, autothermal reforming, partial oxidation, and gasification (using solid fuel) have been considered for hydrogen production from fossil fuel. When using fossil fuel, carbon dioxide should be separated from hydrogen and captured to be accepted as a clean energy. The amount of hydrogen from biomass is insignificant. In order to occupy noticeable portion in hydrogen industries, biomass conversion, especially, biological method should be sufficiently improved in a process efficiency and a microorganism cultivation. Electrolysis is a mature technology and hydrogen from water is considered the most eco-friendly method in terms of clean energy when the electric power is from renewable sources such as photovoltaic cell, solar heat, and wind power etc.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.874-882
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• 2019

In this study, the gasification characteristics of four types of unused woody biomass and one waste wood in a lab-scale bubbling fluidized bed gasifier (Diameter: 0.11 m, Height: 0.42 m) were investigated. Effect of equivalence ratio (ER) of 0.15-0.3 and gas velocity of $2.5-5U_0/U_{mf}$ are determined at the constant temperature of $800^{\circ}C$ and fuel feeding rate of 1 kg/h. The silica sand particle having an average particle size of $287{\mu}m$ and olivine with an average particle size of $500{\mu}m$ were used as the bed material, respectively. The average product gas composition of samples is as follows; $H_2$ 3-4 vol.%, CO 15-16 vol.%, $CH_4$ 4 vol.% and $CO_2$ 18-19 vol.% with a lower heating value (LHV) of $1193-1301kcal/Nm^3$ and higher heating value (HHV) of $1262-1377kcal/Nm^3$. In addition, it was found that olivine reduced most of C2 components and increased $H_2$ content compared to silica sand, resulting in cracking reaction of tar. The non-condensable tar decreases by 72% ($1.24{\rightarrow}0.35g/Nm^3$) and the condensable tar decreases by 27% ($4.4{\rightarrow}3.2g/Nm^3$).

• Journal of Energy Engineering
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• v.19 no.4
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• pp.240-245
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• 2010

In this study, characteristics of wood pellet gasification was studied using a Two Stage Gasifier which is consisted of pyrolysis reactor and ultra high temperature reformer. The average yields of $H_2$, $CH_4$, CO, $CO_2$ were 16.7, 11.3, 37.2, 26.6 L/mim, conversion rate from biomass to gas was 65% in pyrolysis reactor and gas yields in reformer were 55.4, 0.8, 120.8, 56.8 L/mim, respectively. The hydrogen flow rate from reformer is obtained 360.1 L/hr. The most of $CH_4$ was decomposed from 12.3 to 0.3 vol.% while $H_2$ is from 18.2 to 23.7 vol.% in reformer by methane dry reforming, Boudouard reaction, oxidation and/or steam reforming. The amount of $H_2O$ generated by hydration reaction from reformer was 1111.8 g, its accelerated conversion of $CH_4$ to other products. The conversion rate from $CH_4$ to other Compounds was 97.2%. Cold gas efficiency was 53.2%.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.10
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• pp.573-577
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• 2015

There are difficulties in removing wood tar wastewater coming from the power plants that use wood-based fuels due to its intermittent occurrences and severe changes in the amount and concentration. This study investigated the treatment characteristics through physicochemical treatment, an improved method from the existing ones using bag filters and activated carbons to treat wood tar wastewater. In the case of chemical properties of wood tar wastewater, the content of phenols was found to be more than two times higher than that of guaiacols and carbohydrates. Installation is done to ensure that NaOH and PAC are injected automatically according to the change of pH, and then pH, turbidity and SS of the final treated water were examined. The results were 5.9, 12.6 NTU and 15.1 mg/L respectively, which confirmed the possibility of the treated water as circulation water of power plants. In the physical treatment process using a conventional bag filter, removal efficiency of chemicals was about 20%, but the treatment efficiency was improved to show chemical removal efficiency of about 80% through flocculation and sedimentation.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.2
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• pp.131-140
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• 2010

Zero waste clean city was visualized by designing the environmental fundamental facilities such as automated waste collection and bio-energizing system of domestic waste, which was categorized into food and combustible waste from urban area. The biomass circulation position was applied to the domestic waste collection position combined with bio-energizing system in the zero waste clean city. Bio-energizing system consisted of bio-gasification, bio-fuel and bioenergy-circulation process. Food wastes were treated by bio-gasification with anaerobic digestion, and combustible wastes were made of bio-fuel with pyrolysis/drying. Biogas and bio-fuel was utilized into the electric generation or boiler heat in bioenergy-circulation process. The emission of carbon dioxide(CO2) and construction fee of the environmental fundamental facilities related with domestic waste was estimated in the existing city and zero waste clean city, assuming the amount of food waste 35 ton/day, combustible waste 20 ton/day from domestic area. Consequently, 2.7 times lower carbon dioxide emission and 15% construction fee of the environmental fundamental facilities related with domestic waste were obtained from the zero waste clean city by comparing with existing city.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.63-68
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• 2011

As an effective utilization of biomass, organic wastes and coal, attention has been made to use syngas to a reciprocating engine to generate power. However, significant component variation of syngas depending upon origin and gasification conditions, and its lower heating value than that of LPG and CNG can create difficulties in stable engine operation. Thus it is necessary to address these issues in order to successfully develop power generation engines. As a primary step to resolve these problems, effects of H2 content variation in syngas on engine performance and emission characteristics were discussed in this study. The results show that as H2 % in syngas increases, more stable combustion was achieved with retarded MBT spark timing and engine efficiency becomes maximum with syngas of 10% H2. In addition, NOx emission increased while THC emission decreased as H2 % rises in the syngas.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_1
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• pp.149-159
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• 2022

Biomass is material that is comprehensive of carbonaceous materials from plants, crops, animals, and algae. It has been used as one of heating fuel since the beginning the emergence of human beings. Since biomass is regarded as carbon-neutral energy source, it has recently been attracting attention as an energy source that can replace fossil fuels. The most widely applied field is distributed power generation, and a method of generating electric power by driving an internal combustion engine with syngas produced by gasifier is chosen. While the composition of the syngas produced in gasifiers changes depending on the air flowing into the reactor, commercialized gasifiers so far do not control the air flowing into the reactor. When the inner pressure in reactor increases, the air sucked into the reactor is reduced. That change of amount of air makes the composition of syngas varied. Those variations of composition of syngas cause the incomplete combustion hence the power output of engine drops, which is a critical weakness of the gasification technology. In this paper, to produce the uniformly composed syngas, PID control is applied. The result was shown when the amount of air into the reactor is supplied with the constant amount using PID control, the standard deviation of caloric values of syngas is around 2[%] of its average value. Meanwhile the gasifier without PID control has the standard deviation of caloric values is around 7[%]. Therefore, Adopting PID control to supply constant air to the gasifier is highly desirable.

• Journal of the Korean Society of Combustion
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• v.15 no.1
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• pp.43-49
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• 2010

Co-combustion of syngas in an existing boiler can be one of the options for replacing conventional fossil fuel with alternative fuels such as waste and biomass. This study is aimed to investigate effects of syngas cocombustion on combustion characteristics and boiler efficiency. An experimental study was performed for a pilot-scale furnace with 4 oil burners. Tests were conducted with mixture-gas as a co-combustion fuel and heavy oil as a main fuel. The mixture-gas was composed of 15% CO, 7% $H_2$, 3% $CH_4$ and 75% $N_2$ for simulating syngas from air-blown gasification. And LHV of the mixture-gas was 890 kcal/$Nm^3$. Temperature distribution in the furnace and flue gas composition were measured for various heat replacement ratio by the mixture gas. Heat loss through the wall was also carried out through heat & mass balance calculation, in order to obtain informations related to boiler efficiency. Experimental results show that similar temperature distribution and flue gas composition can be obtained for the range of 0~20% heat replacement by syngas. NOx concentration is slightly decreased for higher heat replacement by the syngas because fuel NOx is decreased in the case. Meanwhile, heat loss is a bit decreased for higher heat replacement by the syngas, which implies that boiler efficiency can be a bit decreased when syngas co-combustion is applied to a boiler.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.850-859
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• 2012

Devolatilization is an important mechanism in the gasification and pyrolysis of woody biomass, and has to be accordingly considered in designing a gasifier. In order to describe the devolatilization process of wood particle, there have been proposed a number of empirical correlations based on experimental data. However, the correlations are limited to apply for various reaction conditions due to the complex nature of wood devolatilization. In this study, a simple model was developed for predicting the devolatilization of a wood particle in a fluidized bed reactor. The model considered the drying, shrinkage and heat generation of intra-particle for a spherical biomass. The influence of various parameters such as size, initial moisture content, heat transfer coefficient, kinetic model and temperature, was investigated. The devolatilization time linearly increased with increasing initial moisture content and size of a wood particle, whereas decreases with reaction temperature. There is no significant change of results when the external heat transfer coefficient is over 300 $W/m^2K$, and smaller particles are more sensitive to the outer heat transfer coefficient. Predicted results from the model show a similar tendency with the experimental data from literatures within a deviation of 10%.