The reaction of CaO with HCl was investigated in a fixed-bed reactor fabricated of quartz glass at high temperatures (600−800 °C). The inlet HCl concentration was 2000 ppm. Two sorbents with mean particle sizes of 163 and 465 μm were obtained by calcination of CaCO3. The reaction rate constant was achieved by a deactivation model. The results show that sorbent S1 with small particle size has the higher reactivity and is insensitive to the reaction temperature. In this study, two sorbents have the highest capacity for binding HCl at 650 °C. The breakthrough time of sorbent S1 with a small particle size is longer than that of S2 with a large particle size. A quantity of CaCl2 is evaporated at high temperatures, and it is one of main causes that the outlet HCl concentration does not increase sharply due to the formation of the CaCl2 product layer. Possible mechanisms are proposed to explain the decrease of the chemical reaction rate with increasing temperature.

No abstract

No abstract

No abstract

No abstract

No abstract

This study investigated experimentally the effects of various operating conditions, such as bed temperature, excess air, fuel property, and the method of temperature control on NO and N2O emissions. All the experiments are conducted in a pilot scale vortexing fluidized bed combustor (VFBC). The cross section of the combustion chamber is 0.64 × 0.32 m2, and the inner diameter of the freeboard is 0.45 m. Rice husk, soybean, and high sulfur subbituminous coal are used as fuels. Silica sand is employed as the bed material. The experimental results reveal that NO emissions increase with excess air and are almost independent of the bed temperature (600–760 °C). In addition, the amount of NO and N2O increases while water is injected into the combustor. The high-volatile fuel appears to form a significant amount of NO and N2O above the bed surface, However, NO emission detected at the outlet of the combustor decreases with the volatile content. Compared with the primary air, the bed temperature is the dominant factor for the trade off NO and N2O. Most of the NO is formed above the bed surface, achieves a maximum value at the position below the inlet of second air, and is reduced considerably within the freeboard. Moreover, the most remarkable feature about them is that N2O emission from combustion can be neglected no matter what the feeding material is.

No abstract