The characteristics of fluidized bed catalytic combustion for sludge treatment have been studied in a pilot scale of fluidized bed combustor. 1.0wt% Pt of catalyst supported on the spherical alumina was mixed with the spherical pure alumina as a bed material. Sewage sludge, heating value of which is 3,440 kcal/kg, was used as a waste sample in the experiment. Through the experiments, the various characteristics such as a bed temperature profile and flue gas(CO, SO2) concentration profile were investigated and the catalyst mixing ratio and sample feed rate were applied as experimental parameters. The experimental results showed that bed temperature was maintained more highly and flue gas concentration decreased with the increase of the catalyst mixing ratio, and bed temperature was maintained more highly also and flue gas concentration increased with the increase of the sample feed rate. The combustion efficiency of fluidized bed catalytic combustion of the sludge increased with the increase of the catalyst mixing ratio and sample feed rate and reached more than 96%.

By the end of 2012, the recycled proportion of domestic waste tires was 287,330 ton (93.9%) of the amount of waste tires discharged (305,877 ton). The waste tires have been reused for heat supply, material recycling and other purposes; the proportions are 50.1%, 20.7% and 23.1%, respectively. In the case of heat supply, waste tires are supplied to cement kiln (104,105 ton, 68%), RDF manufacture facilities (47,530 ton, 31%) and incinerators (1,923 ton, 1%). Recently, there has been an increase in the use of waste tires at power generation facilities as an auxiliary fuel. Thus, physico-chemical analysis, such as proximate analysis, elemental analysis and calorific value analysis have been carried out to evaluate potential of waste tires as an auxiliary fuel in Korea. The LHV (Lower Heating Value) of waste tires is approximately 20% higher than that of coal, at an average of 8,489 kcal/kg (7,684 ~ 10,040 kcal/kg). Meanwhile, the sulfur content is approximately 1.5wt. %, and balance of plant (e.g. pipe line, boiler tube, etc.) may be corroded by the sulfur. However, this can be prevented by construction and supplementation with refractories. In this study, TDF (Tire Derived Fuel) produced from waste tires was co-combusted with coal, and applied to the CFB (Circulating Fluidized Bed) boiler, a commercial plant of 100 tons/day in Korea. It was combined with coal, ranging from 0 to 20wt. %. In order to determine the effect on human health and the environment, gas emission such as dioxin, NOx, SOx and so on, were continuously analyzed and monitored as well as the oxygen and carbon monoxide levels to check operational issues.

Fossil fuel combustion generates large amount of green house gas and it was considered major emission source causingglobal warming. For reducing green house gas, renewable energy resources have been emerged as an alternative energy.Among those resources, waste has been considered major resource as one of renewable energy, but it has been not utilizedsufficiently. In Korea, there are lots of efforts to utilize sewage sludge as one of renewable energy resources due to wasteto energy project of government. In this paper, sewage sludge was utilized as main fuel in order to recover heat energysource using oxy-fuel combustion in 30KWth circulating fluidized bed (CFB) pilot plant. Firstly, basic characteristics ofsewage sludge were analyzed and fuel feed rate was calculated by stoichiometry oxygen demand. For producing 30kwthermal energy in pilot plant, the feeding rate of sewage sludge was calculated as 13kg/hr. In oxy-fuel combustion, oxygeninjection rate was ranged from 21% to 40%. Fluidized material was more suitably circulated in which the rate of U/Umfwas calculated as 8 at 800oC. Secondly, Temperature and pressure gradients in circulation fluidized bed were comparedin case of oxy and air combustion. Temperature gradients was more uniformly depicted in case of 25% oxygen injectionwhen the value of excess oxygen was injected as 1.37. Combustion efficiency was greatest at the condition of 25% oxygeninjection rate. Also, the flue gas temperature was the highest at the condition of 25% oxygen injection rate. Lastly,combustion efficiency was presented in case of oxy and air combustion. Combustion efficiency was increased to 99.39%in case of 25% oxygen injection rate. In flue-gas composition from oxy-fuel combustion, nitrogen oxide was ranged from47ppm to 73ppm, and sulfur dioxide was ranged from 460ppm to 645ppm.

The advantage of CFBC(Circulating fluidized bed combustor) is that it can apply to various fuel sources including the lower rank fuel and remove SOx by means of direct supply of limestone to the combustor without additional desulfation facility. In this paper, we denote characteristics of fly and bed ash to reuse finer limestone usually abandoned(used spec[Coarse LS] 0.1mm under 25%, new spec[Fine LS] 0.1mm under 50%). According to the results, the chemical composition of fly ash was as follows; SiO2 40.8%, Al2O3 31.9%, CaO 10.7%, K2O 4.46% in the case of coarse limestone and SiO2 41.1%, Al2O3 31.3%, CaO 10.9%, K2O 4.66% in the case of fine limestone. The chemical composition of bed ash was as follows; SiO2 54.2%, Al2O3 33.1%, CaO 1.56%, K20 4.34% in the case of coarse limestone and SiO2 53.8%, Al2O3 32.6%, CaO 2.21%, K2O 4.45% in the case of fine limestone. It showed that there was no significant change in chemical composition. And it is conformed that there was no significant change in particle size and shapes.

It has been studied that combustion and the production of air pollution of anthracite - bituminous coal blend in a fluidized bed coal combustor. The objects of this study were to investigate mixing characteristics of the particles as well as the combustibility of the low grade domestic anthracite coal and imported high calorific bituminous coal in the fluidized bed coal combustor. They were used as coal samples ; the domestic low grade anthracite coal with heating value of 2,010㎉/㎏ and the imported high grade bituminous coal with heating value of 6,520㎉/㎏. Also, the effects of air flow rate and anthracite fraction on the reaching time of steady state condition have been studied. The experimental results are presented as follows. The time of reaching to steady state was affected by the temperature variation. The steady state time was about 120 minute at 300scfh which was the fastest. It has been found that O_2 and CO_2 concentration were reached steady state at about 100 minute. It has been found that O_2 concentration decreased and CO_2 concentration increased as the height of fluidized bed increased. It was found that splash zone was mainly located from 25㎝ to 35㎝ above distributor. Also, as anthracite fraction increased, the mass of elutriation particles increased, and CO_2 concentration decreased. As air flow rate increased, O_2 concentration decreased and CO_2 concentration increased. Regardless of anthracite fraction and flow rate, the uncombustible weight percentage according to average diameter of elutriation particles were approximately high in the case of fine particles. As anthracite fraction and air flow rate increased, elutriation ratio increased. As anthracite fraction was increased, exit combustible content over feeding combustible content was increased. Regardless of anthracite fraction, size distribution of bed material from discharge was almost constant. Over bed temperature 850℃ and excess air 20%, the difference of combution efficiencies were little. It is estimate that the combustion condition in anthracite-bituminous coal blend combustion is suitable at the velocity 0.3m/s, bed temperature 850℃, the excess air 20%.