Ammonia in Fly Ashes from Flue Gas Denitrification Process and its Impact on the Properties of Cement Composites

The paper presents the results of research on the properties of fly ashes from the process of flue gas denitrification by selective non-catalytic reduction (SNCR), consisting of dosing urea into the coal combustion chamber. The research was carried out on two types of fly ash: Silica fly ash from flue gas denitrification and ash from a traditional boiler without the flue gas denitrification process. The scope of comparative studies included physicochemical and structural features of ashes, as well as slurries and mortars with the addition of ashes. Fly ash from denitrification, whose ammonia content at the time of sampling was 75 mg/kg at the maximum, was examined. Our own research has shown that fly ash from flue gas denitrification is characterized by a higher value of losses on ignition and ammonia content in comparison to ashes without denitrification. It was shown that the ammonia content in the analyzed range does not limit the use of fly ash as an additive to cement and concrete.

Hybrid technology of reduction of nitrogen oxides (NOx) in exhaust gases; Part 2 – Numerical model of pilot scale regenerative rotary air heater (RAH) retrofited with selective catalyst reduction (SCR) modules

This article exhibits the results of the analysis performed to verify the effectiveness of the hybrid flue gas denitrification system (herein referred to as HDS) which involved the retrofitting for selective catalytic reduction (SCR) material into a regenerative rotary air heater (RAH). A numerical model corresponding to the actual pilot scale RAH operating conditions was developed. The ultimate intent of the numerical model is to provide a platform where the technology can be implemented on full scale air preheaters. The numerical analysis performed on the pilot scale HDS installation showed a 3% decrease in heat exchange efficiency in the exchanger. This decrease was significantly minimized by the use of blades adjusting the distribution of flue gases entering the RAH. This means that the exhaust gas temperature at the exchanger outlet increased by 4°C, which corresponds to an average of 0.3% increase in the boiler outlet loss. It was also recognized that the air temperature was reduced by 8°C, which does not translate into significant changes in boiler performance parameters. other boiler operating parameters in a noticeable way during operation.

Utilization of Fly Ash Contaminated by SNCR Flue Gas Denitrification into Polymer Epoxy Anchor

The paper deals with the possibility of using two different types of fly ash contaminated by flue gas denitrification (Selective Non-Catalytic Reduction (SNCR)) as a filler into the polymer anchor based on epoxy resin. Due to the problematic use of contaminated fly ash in silicate materials, the use of such fly ash in polymer materials seems to be effective because by mixing with polymers such as polyester and epoxy resins, toxic gas ammonia (NH3) does not release. Determination of optimal percentage of filling by the fly ash was performed in order to achieve the best possible physical and mechanical properties of the epoxy anchor material. It was found out that the 45% addition of both used of contaminated fly ashes seems to be the most appropriate, when the polymer anchor material exhibited better tensile properties than reference anchors containing quartz sand Dorsilit. Furthermore, it was found that the optimal addition of contaminated fly ash also positively influenced the maximum anchoring force found in the tug test. Detailed connection of anchor material with anchored bar and concrete was observed on tomography images.

Investigation on an ammonia supply system for flue gas denitrification of low-speed marine diesel

Low-speed marine diesel flue gas denitrification is in great demand in the ship transport industry. This research proposes an ammonia supply system which can be used for flue gas denitrification of low-speed marine diesel. In this proposed ammonia supply system, ammonium bicarbonate is selected as the ammonia carrier to produce ammonia and carbon dioxide by thermal decomposition. The diesel engine exhaust heat is used as the heating source for ammonium bicarbonate decomposition and ammonia gas desorption. As the ammonium bicarbonate decomposition is critical to the proper operation of this system, effects have been observed to reveal the performance of the thermal decomposition chamber in this paper. A visualization experiment for determination of the single-tube heat transfer coefficient and simulation of flow and heat transfer in two structures is conducted; the decomposition of ammonium bicarbonate is simulated by ASPEN PLUS. The results show that the single-tube heat transfer coefficient is 1052 W m 2 °C −1 ; the thermal decomposition chamber fork-type structure gets a higher heat transfer compared with the row-type. With regard to the simulation of ammonium bicarbonate thermal decomposition, the ammonia production is significantly affected by the reaction temperature and the mass flow rate of the ammonium bicarbonate input.