• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.2
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• pp.72-78
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• 2006

Effect of organic loading rate on digester performance was evaluated under the conditions of same surface area/reactor volume ratio and different reactor diameter. At the low loading rate of $0.4\;kg\;COD/m^3{\cdot}d$, high rate of organic removal could be obtained regardless of reactor diameter. It can be estimated that reactor configuration can not affect reactor performance at the low loading rate. However, different performance depending on reactor diameter was observed at the organic loading rate of $6\;kg\;COD/m^3{\cdot}d$. That is, volatile acid accumulation and low COD removal efficiency was observed in reactor having 6.4 cm diameter, while volatile acid was not accumulated at all and high COD removal efficiency was observed in reactor having 3 cm diameter. Such a difference of reactor performance depending on reactor diameter can be explained that sludge bed can be fluidized by evolved gas bubble in narrow reactor while sludge bed can not be fluidized by evolved gas bubble only in wide reactor. At a high organic loading rate of $20\;kg\;COD/m^3{\cdot}d$, it can be judged that there is no relation between reactor configuration and reactor performance because all reactors showed very low COD removal efficiencies regardless of reactor diameter. Sludge bed fluidization is one of the most important factors in achieving efficient start-up of anaerobic digester. Narrow and tall type reactor is favorable condition for making sludge bed fluidization at a constant surface area/reactor volume ratio. Thus, it can be judged that reactor configuration and sludge bed fluidization have great influence to reactor performance.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.746-751
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• 2006

In this study, drying and carbonization experiment was conducted in a fluidized bed reactor according to the variations in gas velocity, particle size, and reactor temperature. As a result, the weight loss rates of sludge by drying in the fixed bed and fluidized bed type dryer showed that drying in the fluidized bed was about 6 times faster than drying in the fixed bed, and the weight loss rates of sludge by carbonization in the fixed bed and fluidized bed type reactor showed that carbonization in the fluidized bed was about 4 times faster than drying in the fixed bed. This implies that carbonization in the fluidized bed was completed within 10 minutes. Although the amount of char decreased with the increase of carboniration temperature, the amount of char became similar at upper 873K. Also, the amount of char decreased with increasing gas velocity. Consequently, it could be efficient that slow fluidization should be maintained within the range of fluidization in case of fluidized carbonization of sewage sludge at 873K.

• Journal of the KSME
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• v.35 no.7
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• pp.620-637
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• 1995

이 글에서는 유동층소각로와 관련된 기술적 사항을 정리하고자 한다. 일부 교과서적인 내용이 서술되어 있으나, 자세한 이론적 고찰보다는 현상적인 이해에 중점을 두고, 실제 유동층 소각로와 관련된 분야에서 연구를 수행하는 연구자들과의 토론 및 설계시 고려하여야 할 사항들을 간략히 포함한다. 일반적으로 유동층은 효울적인 화학반응로로서 주로 이용되고 있으나, 이 글에서는 환경 및 에너지분야와 일정한 관계가 있는 폐기물 소각로 및 석탄연소로로서의 유동층의 응용에 초점을 맞추고 있다. 우선 환경 및 에너지산업의 현황을 이해함으로써 유동층의 핵심적 역할 담당 가능성을 밝힌다. 그리고 소각로의 종류 및 유동층의 역사와 응용에 대하여 각략히 설명 한다. 여타의 소각로와는 다른 특성인 기포유동특성 및 유동화에 대하여 논함으로써 유동층에 대한 기본현상을 파악한다. 유동층 소각로의 중요한 기능인 공해물질의 노내처리에 대하여 논 의하고, 기포유동층보다 효율적인 순환유동층 및 가압유동층의 특성과 역할을 소개한다. 그리고 유동층 소각로의 예로 일본의 폐기물소각로 및 하수슬러지 소각로개발 현황을 소개한다. 최종 적으로는 유동장 소각로의 실제 설계과장에 대하여 간략히 해설한다.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.846-853
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• 2017

Cold bed and $30kW_{th}$ pilot bed tests using circulating fluidized bed (CFB) were conducted to apply oxy-fuel technology for waste sludge combustion as a carbon capture and storage technology. In cold bed test, the minimum fluidization velocity ($u_{mf}$) and superficial velocity for fast fluidization was determined as 0.120 m/s and 2.5 m/s, respectively. In the pilot test, air and oxy-fuel combustion experiments for waste sludge were conducted using CFB unit. The flue-gas temperature in 21~25% oxy-fuel combustion was higher than that of air and up to 30% oxy-fuel combustion. In addition, the concentration of carbon dioxide was more than 80% with the oxygen injection range from 21% to 25% in oxy-fuel CFB waste sludge combustion.

• Clean Technology
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• v.23 no.1
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• pp.80-89
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• 2017

The bubbling fluidized bed (BFB) reactor with a diameter of 0.1 m and a height of 1.2 m was used for experimental study of co-firing and emission characteristics fueled by sewage sludge (SS) and wood pellet (WP). The facility consists of a fluidized bed reactor, feeding system, cyclone, condenser and gas analyzer, The mean particle diameter and minimum fluidization velocity are $460{\mu}m$ and $0.21ms^{-1}$ respectively. SS produced from Korea and WP from Canada were examined. The various mixing ratios of WP were 20, 50, and 80% based on HHV. The equivalence ratio of 1.65, reactor temperature of $800^{\circ}C$, air flow rate of $100Lmin^{-1}$, and fluidization number of 4 were fixed in the BFB experiment. In TGA, the range of combustion temperature of SS was wider than that of WP. It represents that the combustibility of WP is higher than that of SS. The BFB reactor temperature was maintained between 800 and $900^{\circ}C$. CO emission of SS was high because of lower combustibility. $NO_X$ and $SO_X$ formation of SS were higher than that of WP since high nitrogen and sulfur contents of SS. CO, $NO_X$, and $SO_X$ formation were suppressed as the mixing ratio of WP was increased. The slagging and fouling tendencies show high in all test conditions.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.3
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• pp.27-33
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• 2012

According to the statistics of the Ministry of Environment, the emission of sewage sludge is increased by 7~9% yearly. In the future, it will be increased continuously because of extension of sewage disposal plants, high class treatment for removing nitrogen and phosphorus. Until now, we have depended on reclamation for lots of quantity and some part has been treated by ocean emission. But, direct reclamation of organic waste will be prohibited and even ocean emission will be prohibited now, so the treatment of sludge is put on emergency alert. Bio-gas can be produced by applying anaerobic digestion method for the recycling or refuse derived fuel can be conducted by applying carbonization method. However, the process is difficult, causes bad smell and makes it the second waste, so it cannot be practical method in fact. This study applied a fluidized bed combustor for sewage sludge treatment technologies that can actually take advantage of key technologies in order to verify its purpose is to demonstrate selected. If applying the fluidized bed combustor, it can be easily utilized as the replaced resource of energy(fuel) in the countries whose energy resources are insufficient, like our country. Especially, if applying only original strengths of the fluidized bed combustor sufficiently, the sewage sludge can be treated simply, eco-friendly, sanitarily and economically. Particularly, it is verified as the energy technology suitable for government's green growth policy.

• Clean Technology
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• v.20 no.4
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• pp.390-397
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• 2014

This study was performed to investigate the effects of fluidizing media on $N_2O$ production in fluidized bed incineration of sewage sludge. The fluidized media were prepared in a form of 2 mm bead by mixing zeolite powders in our lab. Sand having 0.4 mm of the mean size showed 0.44 m/s of minimum fluidization velocity ($U_{mf}$), while the prepared zeolite media 0.5 m/s. When the ratio of fluidizing media height to the inside diameter of the incinerator (bed aspect ratio) increased from 1.4 to 3.1, it was found that $U_{mf}$ of the zeolite media was varied from 0.5 m/s to 0.7 m/s. Under the operation conditions in 1.79 of excess air ratio, $909^{\circ}C$ of bed temperature and ca. 1.65 m/s of superficial velocity, as the weight of fluidizing meadia was increased, $O_2$ concentration in the flue gas was slightly decreased, and $CO_2$ increased. Above 6 kg of fluidizing media weight (1.98 of bed aspect ratio), it was observed that $N_2O$ concentration was significantly reduced, which might result from the decomposition of $N_2O$ on the zeolite media rather than transformation of $N_2O$ to NOx. On the other hand, in a variation of the zeolite media mixing ratio to sand and bed temperature at a constant total bed height, significant difference was exhibited in $N_2O$ emission concentration according to the temperature. Considering the operation temperature in the incineration, the effective calcination temperature of the zeolite media was suggested to be around $900^{\circ}C$.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.05a
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• pp.567-572
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• 2003

하수슬러지로부터 재활용 가스 에너지를 얻을 수 있다. 슬러지 가스화의 공정 개발을 위해서는 초기에 휘발분이 방출되는 열분해 단계의 거동이 매우 중요하다. 열분해 생성물(가스, 타르, 촤 등)의 수율은 열분해 조건(가열속도, 체류시간, 온도, 압력, 가스분위기)뿐만 아니라 연료입자의 물리적 구조에 따라 좌우된다. 석탄의 경우에는 열분해과정에서 휘발분의 수율에 대한 상관식들이 많이 제시되었다.(중략)

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.371-376
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• 2008

• Journal of Environmental Health Sciences
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• v.32 no.2 s.89
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• pp.179-185
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• 2006

Effect of organic loading rate on UASB performance was evaluated under the renditions of some surface area/reactor volume ratio and different reactor diameter. At the low leading rate of 0.4 kg $COD/m^3{\cdot}d$, reactor performance was not affected by reactor diameter. At the organic loading rate of 6 kg $COD/m^3{\cdot}d$, however, volatile acid accumulation and low COD removal efficiency is observed in reactor having 6.4 cm diameter, while volatile acid is not accumulated at all and high COD removal efficiency is observed in reactor having 3 cm diameter. Such a difference of reactor performance depending on reactor diameter can be explained that sludge bed can be fluidized by evolved gas bubble in narrow reactor, while sludge bed ran not be fluidized by evolved gas bubble only in wide reactor. At a high organic loading rate of 20 kg $COD/m^3{\cdot}d$, it can be judged that there is no relation between reactor configuration and reactor performance because all reactors showed very low COD removal efficiencies regardless of reactor diameter. Narrow and tall type reactor is favorable condition for making sludge bed fluidization at a constant surface area/reactor volume ratio. Thus, it can be judged that reactor configuration and sludge bed fluidization have great influence to reactor performance.