• Resources Recycling
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• v.18 no.3
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• pp.55-61
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• 2009

Dewatering process to remove water from pigment sludge was important in the diverse aspects of the improvement of product quality, curtailment of the drying cost and the transportation. It was difficult to dewater pigment particles with the mechanical forces because the size was fine under $5{\mu}m$. Thermal filter press dewatering equipment composed of squeezing plate and a fixed heating plate was developed to improve the dewaterability of pigment the sludge as supplying the heat from the fixed heating plate to the cake. Several tests that estimate the dewaterability for pigment sludge as with or without squeezing process and the difference of dewatering time was conducted with this equipment. Dewaterability of thermal dewatering under squeezing process was increased about 20% compared with non squeezing process. Under squeezing process, thermal dewatering tests changing dewatering time with 70 and 80 minute were conducted respectively. The water content of cake was more reduced at dewatering time of 80 minute compared with 70 minute, and dewatering velocity was also decreased, which caused the productivity of thermal filter press to drop. It was observed that clogging of filter cloth didn't almost occur because the liquid was discharged from cake layer easily. In this research, it was resulted that the squeezing process and long dewatering time were effective to improve the dewaterability of pigment sludge. So, this thermal filter press equipment was useful for dewatering the fine particle sludge like pigment.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1016-1023
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• 2006

The water content of dewatered cake produced from belt press dewatering equipment was about 75 wt% which was some high to handle it, so the equipment contained a limit at the economical and environmental aspect. The thermal dewatering equipment built as an alternative to overcome several problems was set up at the sludge treatment field and estimated some feasibility as comparison with the dewatering performance of belt press. First, dewatering properties of waterworks sludge was analyzed by monthly. The sludge of a water shortage season contained a high organic content which led to be difficult to dewater the cake, the other side the sludge of rainwater season was ease to dewater because of low organic content. According to the results to analysis the water content of dewatered cake produced from two equipments on the base of the seasonal dewatering properties, the water content of dewatered cake produced from thermal dewatering for sludge of water shortage season was $41.6{\sim}48.3$ wt% and $71{\sim}84$ wt% from belt press. In the case of rainwater season, the water content of dewatered cake produced from thermal dewatering was $34{\sim}37.7$ wt% and $57{\sim}70$ wt% from belt press. It was understood that thereduction of water content of cake by thermal dewatering was larger than belt press. The economical aspect for two equipments was evaluated on considering the reduction of cake treatment amount as the decrease of water content of cake. When putting the cost index of thermal dewatering into 100, belt press was 121. This meant that thermal dewater was more economical than belt press by about 20% in the side of construction and operation. In conclusion, thermal dewatering equipment was estimated by producing the low water content dewatered cake as well as being operated with low coat.

• Resources Recycling
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• v.15 no.3 s.71
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• pp.38-45
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• 2006

The thermal filter press dewatering(TFPD) technology to improve the dewaterability through increasing the inner vapor pressure, lowering the filtration viscosity and forming the porosity easily within cake as applying the heat at the sludge layer was developed in this study. The hot water with temperature of $95^{\circ}C$ and pressure of $1.2kg_f/cm^2$ was supplied to the heating plate equipped between filter plates with plate size of $470{\times}470mm$ and material of polypropylene. Sludge was dewaterd by supplying pressure of $5kg_f/cm^2$ and then by squeezing pressure of $15kg_f/cm^2$. As a results of estimating the characteristics of thermal dewatering to consider the initial water content and organic content to be influenced by a period of water shortage and rainwater, the dewatered cake water content was about 35 wt% and dewatering velocity was $4DSkg/m^2{\cdot}hr$ under the rainwater period, and the dewatered cake water content was about 50 wt% and dewatering velocity was $1.5DSkg/m^2{\cdot}hr$ in the case of sludge of water shortage season. These results was superior to the mechanical dewatering performance with water content of 70wt% and dewatering velocity of $0.9DSkg/m^2{\cdot}hr$. On the base of the results of TFPD, energy consumpted to deal with DS(Dry Solid) of 1kg was estimated by 300 kJ. It was analyzed that the energy consumption of TFPD was decreased about one third with comparison to the dryer system. Dewatering velocity of this technology was faster than the one of mechanical dewatering equipment and it was easier to product low water content cake. Therefore, this technology was recognized that dewaterability was predominant because of the fast of dewatering velocity and production of low water content cake, and also this known as economical efficiency was excellent because of low energy consumption in comparison with dryer.

• Resources Recycling
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• v.15 no.4 s.72
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• pp.36-43
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• 2006

There was some difficulty dewatering properties due to small porosity diameter of cake, when pigment sludge contained fine particle was formed by cake under the dewatering. It was difficult to dewater the sludge with fine particles with the conventional mechanical dewatering method. This study was to improve the dewatering rate as discharging the water from porosity of cake easily, supplying the low heat to the cake layer. Thermal dewatering equipment of piston type to keep up constant temperature on the cake was set up and relative experiment was conducted for sludge of 200 g with fine pigment particle. As test results. filtration of 176.8 g, cake weight of 19.4 g, cake thickness of 4.2 mm was measured, and it was analyzed that the water content of cake was 47 wt% and dewatering velocity, which moaned the residual d교 sloid amount per dewatering area, was $2.1DS\;m^{2}{\cdot}cycle$. This results showed that filtration increased, cake weight and thickness decreased and dewatering velocity increased against mechanical dewatering method. And water content of cake decreased about 30%, so the result which dewatering rate improved was drew generally. The reason is that the inner vapor pressure working at the cake porosity increased as applying the low heat to the cake layer, which lead to discharge the water from porosity easily. Therefore, this study was estimated by the useful technology for sludge reduction.

• Solar Energy
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• v.15 no.3
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• pp.29-38
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• 1995

The heat-storage characteristics accompanied by exothermic reaction at the regeneration of $Ca(OH)_2$ in tile heat-storage mode of a chemical heat pump system using a $Ca(OH)_2/CaO$ reversible thermochemical reaction was examined in a lab-scale unit. In this heat-storage mode, the particle bed of CaO could be regenerated by heating the $Ca(OH)_2$ packed bed to the higher temperature at which the equilibrium pressure in the reactor is greater than the water vapor pressure in the condenser. The results are i) the dehydration, thermal decomposition, rate of $Ca(OH)_2$ was higher at the lower part of particle bed than at the upper part, ii) in the reactor, the dehydration was proceeded along radial and axial direction, from inner part to the outer part, which explains heat transfers from the center to wall and from the tenter to lower or upper part of reactor.

• Bulletin of Korea Environmental Preservation Association
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• s.376
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• pp.44-47
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• 2008

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.885-888
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• 1999

This study was carried out to determine the reaction kinetic constant of the dehydration - thermal decomposition of $Na_2B_4O_7{\cdot}10H_2O/Na_2B_4O_7{\cdot}5H_2O$ and to investigate the durability during the repeated use of a chemical heat-storage material and the reproducibility of reaction system. The order of the dehydration reaction was 1st-order. The reaction rate was directly proportional to a partial pressure difference of water steam. The kinetic constant was 0.27 and the reproducibility of dehydration reaction for a kinetic constant and a reaction order was excellent. The activity variation in the durability test of a chemical heat-storage material was within range of ${\pm}5%$ during the repeatedly use in several times.

• The KSFM Journal of Fluid Machinery
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• v.7 no.2 s.23
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• pp.35-40
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• 2004

A generation rate of sludge in Korea had increased dramatically about $200\%$ for a decade. A requirement for high efficiency dewatering system being possible to produce the low water content cake have suggested due to the appearance of commercial and social problems about handling of dewatered cake. The conventional dewatering system with mechanical compression device was not suitable to produce the low water content cake and didn't cope with lots of requirements. Therefore, this paper was to develop the high efficient filter press with the compressive and heating forces through the heating plate to be built between membrane fillet plates. It is possible to produce the low water content cake and improve the dewatering rate, so this equipment positively coped with several types of problems related to the sludge dewatering. The plate heated by heat transfer materials such as steam, hot water and thermo-oil made the sludge make the residual moisture within the cake to discharge easily and to improve the dewatering efficiency of equipment. The pilot scale experiment with 500kg of cake production showed that the dewatering efficiency determined by the final water content and dewatering velocity was improved $30\%$ more than the conventional dewatering equipment.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.278-283
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• 2003

A generation rate of sludge in Korea had increased dramatically about 200 % for a decade. A requirement for high efficiency dewatering system being possible to produce the low water content cake have suggested due to the appearanceof commercial and social problems about handling of dewatered cake. The conventional dewatering system with mechanical compression device was not suitable to produce the low water content cake and didn'tcope with lots of requirements. Therefore, this paper was to develop the high efficient filter press with the compressive and heating forces through the heating plate to be built between membrane filter plates. It is possible to produce the low water content cake and improve the dewatering rate, so this equipment positively coped with several types of problems related to the sludge dewatering. The plate heated by heat transfer materials such as steam, hot water and thermo-oil made the sludge make the residual moisture within the cake to discharge easilyand to improve the dewatering efficiency of equipment. The pilot scale experiment with 500kg of cake production showed that the dewatering efficiency determined by the final water content and dewatering velocity was improved 30% more than the conventional dewatering equipment.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.34-39
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• 2017

The recent gradual increase in the energy demand is mostly met by fossil fuel, but the research on and development of new alternative energy sources is drawing much attention due to the limited fossil fuel supply and the greenhouse gas problem. This paper assesses the feasibility of producing fuel energy from a dewatered sewage sludge by microwave-induced pyrolysis with sludge char and graphite receptor. Both receptors produced gas, char, and tar in order from product amount. The gas produced for the sludge char receptor contained mainly hydrogen and methane with a small amount of light hydrocarbons. The graphite receptor generated higher gravimetric tar and generated higher light tar. Through the results, the product gas from the microwave processes of wet sewage sludge might be possible as a fuel energy. But the product gas has to be removed the condensable PAH tars.