• Journal of Korean Society of Water and Wastewater
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• v.38 no.3
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• pp.155-164
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• 2024

There are two primary sludge drying methods such as the direct heating microwave method and the indirect heating steam one. In this study, the drying treatment facility at sewage treatment plant A applied both of these drying methods. The research aimed to investigate the optimal operation approach for the drying facility, considering the input sludge and the moisture content data after the drying process. Moisture content and removal rate data were executed at the research facility from January 2016 to December 2018. First, the microwave, a direct heating drying method, performed intensive drying only on the outer surface of the sludge by directly applying heat to the sludge using far infrared rays, so effective sludge drying was not achieved. On the other hand, the steam method of the indirect heating method used steam from a gas boiler to maximize the utilization of the heat transfer area and reduce energy of the dryer, resulting in an effective sludge drying efficiency. The sludge moisture content brought into the sludge drying facility was about 80%, but the moisture content of the sludge that went through the drying facility was less than 10% of the design standard. Therefore, the steam method of the indirect heating method is more effective than the microwave method of the previous direct heating method and is more effective for maintenance It has proven that it is an efficient method of operating construction facilities.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.65-73
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• 2018

This study was carried out for 20 days in a bio-drying batch reactor under the blowing conditions of 0.75, 1.00, 1.25, and $1.50L/min{\cdot}kg$ in order to optimize the operating conditions for the bio-drying of food wastes. The decomposition rate of organic matter during the bio-drying operation period was analyzed using modified Gompertz model. The maximum organic degradation (P) was 2.31, 2.52, 2.27 and 1.88 kg at air flow rates of 0.75, 1.00, 1.25 and $1.50L/min{\cdot}kg$, and the maximum organic degradation rate was 0.33, 0.45, 0.28, and 0.18 kg/day at 1.00, 1.25 and $1.50L/min{\cdot}kg$, respectively, showing excellent organic decomposition efficiency at a air flow rate of $1.00L/min{\cdot}kg$. The lag growth phase time (${\lambda}$) of the bio-drying reactor was 2.10, 1.48, 1.15, and 1.06 days at 0.75, 1.00, 1.25 and $1.50L/min{\cdot}kg$, respectively. The water removal rate in the operation of bio-drying reactor of food waste increased with the increase of air flow rate from the early stage of bio-drying to the middle stage, and the highest water removal rate was observed at the air flow rate of $1.00L/min{\cdot}kg$ at the end of bio-drying. The optimum air flow rate condition of bio-drying reactor was $1.00L/min{\cdot}kg$.

• Korean Journal of Medicinal Crop Science
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• v.22 no.4
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• pp.255-261
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• 2014

Cosmetic activities of the leaves of Curcuma longa L. were compared according to different drying methods, to expand the use of the by-products of Curcuma longa L. The highest extraction yield of 29.4% was obtained from vacuum drying process (VD), whose value was very close to 29.2% from freeze drying process (FD). Relatively lower extraction yield were observed as 24.5% and 25.3% from the raw leaf (RL) as control and hot air drying process (HD). The cytotoxicity was observed lower FD and VD than RL and HD. It shows that cytotoxicity was closely related to cosmetic activities such as tyrosinase and melanin inhibition activities by showing much better cosmetic activities of the extracts from both FD and VD than those from the RL and HD. It was interesting that was differences of the cosmetic activities and cytotoxicity between FD and VD, which implies that VD method should be a more efficient process than FD method in terms of drying time and operation costs: 6 hours vs 24 hours and 3-5 times higher extraction costs in drying. It was observed that VD is more excellent dry method than others. This result could be utilized to effectively dry other soft plant biomass.

• Resources Recycling
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• v.6 no.1
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• pp.40-46
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• 1997

Sludgc d~sposal has been a major challenge in the wastewater treatment. Drying is operation which is separated fromsewage sludge to solid and liquid by heating. Drying needs to pretreatment process for effective "thation, incinerationand dispaal The objective of this work was to the drying dewatered sewage sludge by microwave heating, and tocompare the experimental rcsults with thcorctical rcsults. Microwave drylng is fast and has a high efficiency. In thepresent \ark, an unsteady state analysis of one dunensional drying, with microwave heating, is carried out. In drying ratecurve, moisture movement at falling rate period occured by dfision. A good agreement was abtamed between the modcland the experimental results using the slab sample of 0.2cm thickness. 0.2cm thickness.

• Korean Journal of Food Science and Technology
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• v.19 no.3
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• pp.200-205
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• 1987

A microcomputer-based on-line monitoring and controlling system was built and applied to the dehycration operation. Drying conditions-drying temperatures and air velocities-were successfully controlled by the control deveices incorporated on/off realy and thyristor, and with the high language program. Drying variables-temperature in drier and weight loss of radish slice were accurately measured and acquisited. The computer-based drying system effectively saved the man power required to measure and record data during the drying period and also made possible to conduct the process undisturbed for long period. The drying rate curves of radish at various drying conditions were obtained from automatic data analyzing program. And also the computer programmed control made possible to investigate the effect of air velocity change during the drying period. The dynamic change of air velocity of from one to another level could be performed and affected markedly the drying rate at first stages of drying, but no significant effect were found in falling rate period.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2004.04a
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• pp.117-126
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• 2004

This paper presents a linear model for heat transfer processes in the drying cylinders and the web in papar mill. The PDE model, functions include steam temperatures, wet temperatures, moisture constents, reel speed and basis weight were derived from operation data. The changes of wet temperatures and moisture contents in the drying cylinders and wets could be described. The Transfer function can be obtained through the state space model derived from the linearized PDE model. Stability of the drying cylinder model for paper plants and analysis of characteristics of process responses for changes in input variables are investigated.

• Journal of Environmental Science International
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• v.10 no.1
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• pp.59-64
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• 2001

The effect of major operating parameters in spray drying sorber(=SDS) for automatic control for the simultaneous removal of acidic and organic gaseous pollutants from solid waste incinerator was performed. The field experiment was carried out in pilot scale test for the quantification of major operating parameters of hydrophilic and the hydrophobic pollutants. The removal efficiencies of $SO_2$and HCI in the 5wt% slurry condition were being increased with the increase of the stoichiometric ration which is the molecular ratio of lime to the pollutant concentration, and with the decrease of inflow flue gas temperature in the pilot SDS reactor. The removal efficiency along the height of spray drying sorber was closely related to the temperature profile, and more than 90% of total removal efficiency was achieved in an absorption region. For the removal of acidic gas the optimum operating condition considering the economics and a stable operation is the 5wt% of slurry concentration, 1.2 of stoichiometric ratio and 25$0^{\circ}C$ of inflow flue gas temperature. For the organic gases of benzene and toluene the removal efficiencies were 20-60% which is much lower than that of acidic gas. The best removal efficiency was obtained at 1.5 of stoichiometric ratio and 25$0^{\circ}C$ of inflow flue gas temperature. The organic\`s removal efficiency along the height of spray drying sorber was quite different from that of acidic gas, that is, more than 60% of the total removal efficiency for benzene and 90% of the total removal for toluene were achieved in the dried adsorption region, which was formed at the lower or exit part of the reactor.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.2
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• pp.74-84
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• 2005

The objectives of this study was to investigate the improvement of thermal kinetics for disposal of sewage sludge using thermal wind drying. The operational parameters varied are the temperature of $130{\sim}170^{\circ}C$ and evaporation velocity WD. Important parameters effect on thermal kinetics for evaporation of water in sewage sludge studied include the drying time, water content of sewage sludge, solids amount of sewage sludge(TS%) by the varied temperature. The saturation point of water evaporation was observed at the drying time of 60 min in conditions of drying temperature $170^{\circ}C$ and drying time of 120 min by drying temperature $130^{\circ}C$ and WD=0.95 m/s. Operation at drying temperature of $170^{\circ}C$ led to higher rate of evaporation than those 130, $150^{\circ}C$ at WD=1.0 m/s and WD=1.0 m/s was higher than WD=0.5 m/s at drying temperature of $130^{\circ}C$.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2003.11a
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• pp.249-271
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• 2003

The purpose of the present study is to identify the drying cylinder model in paper plants and to analyze characteristics of process responses for changes in input variables. The model developed in this work is based on actual plant operation data and the steam pressure applied to the cylinder behaves as one the main variables. It is found that heat transfer coefficients from the condensate to the canvas could be represented as empirical relations based on heat conductivities and operation date. The effectiveness of the cylinder model is demonstrated by the measured moisture contents and web temperature. Using transfer functions derived from the cylinder model stability of the drying process is analyzed.

• Journal of Fisheries and Marine Sciences Education
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• v.22 no.4
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• pp.501-507
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• 2010

The ceramic contained paint was made to replace the lead sinker for gill-net with coated lead sinker. The ceramic contained paints were coated in various conditions on the lead sinker with 19g of weight and the optimal coating condition was studied. The adaptability of the coated lead sinker was checked through the anti durability test and fishing operation with gill-net. The case of "Main material 70 wt% + Urethane thinner 30 wt% (Main material 700 $m{\ell}$ + Thinner 300 $m{\ell}$)" showed the best in the coating characteristics depending on the combination ratio of the ceramic paint contained. The coated lead sinker dried at $100^{\circ}C$ inside oven was superior to the drying in the room temperature in its surface glossiness and anti durability and faster drying time than the one dried in normal temperature. The quadruple layers of coating on lead sinker with 4 times of dipping and drying application showed the super anti durability in the coating characteristics depending on the frequency of dipping. When press is applied to the coated lead sinker, the coated layer is not detached from the sinker. In addition, the coated lead sinker was not damaged or peeled at the fishing operation about 2 months in various depths within 50m and by the materials at the bottom (sand, stone and gravel stone) and it was in good condition.