Combustion flue gases

The characterization of PIC (products of incomplete combustion) from the combustion of wood treated with pentachlorophenol (penta) is more widely documented in the open literature than creosote alone. However, both products are similar in chemical composition and likely result in comparable forms and concentrations of PIC. Literature reported studies on the combustion of these chemicals and wood treated by them, and the PIC generated are based upon optimal conditions. Optimal conditions are defined as those in which the fuel burns at the designed heat release rate with nominally 160% excess air and a low level (< 100 ppm) of carbon monoxide (CO) emissions in combustion (flue) gases. 

Economizers improve boiler thermal efficiency by recovering heat from the combustion flue gases exhausted from the steam boiler section. The recovered heat is used to heat colder streams (heat sinks), before ultimate discharge of the waste gas to atmosphere. This recovered heat displaces the need to bum additional fuel to heat these same streams. 

Processes 7 to 9 in Table III have the common feature of producing sulphur as the end product. They are therefore overall reduction processes. The Cat-Redox and CO/SO2 systems are both direct conversions to elemental sulphur. The latter has a particular advantage of being able to accept effluent gas streams at temperatures of 750 F or higher thus avoiding the need for any cooling of combustion flue gases before clean-up. The Alkalized Alumina Process, however, involves concentration and catalytic... 

Electron beam processing of combustion flue gases, IAEA-TECDOC-428, 1987. 

Sakamoto, I. Mizusawa, K. Kashiwagi, M. In Electron beam processing of combustion flue gases, IAEA-TECDOC-428, 201, 1987. 

Similar "open-cycle" scoping studies using waste SO2 from combustion flue gases and SO2 produced from sulfur show equivalent economic potential. The latter, of course, would have a higher sulfuric acid production cost because the sulfur feedstock would have an acquisition cost that must be included in the economics. Nevertheless, the cost of sulfuric acid, when tempered by the revenue obtained from the sale of hydrogen, can be extremely attractive. The reverse is also true. 

The oxidation of NO and N02 is of industrial importance for cleaning combustion-flue gases. Transition metal ion-exchanged zeolites have been shown (51) to be highly active catalysts for this reaction. The relative activities are shown in Fig. 10, from which it can be seen that equilibrium conversions of NO to N02 can be achieved with Cu2 + X at reaction temperatures as low as 350"C. Kinetic studies showed that the reaction rates were fractional order in both NO and 02. The following reaction mechanism was therefore proposed, for example, with Cu2 + X,... 

In non-immersed systems such as dust particles in flowing dr streams, van der Waals forces will operate leading to adhesion and since there are no barriers, prevention of fouling is extremely difficult. In gas streams where there are reacting species and possibly changes in phase such as in combustion flue gases, the situation is extremely complex. 

Catalyst regeneration off-gas Bottom and fly ash, gasifier gas, solid waste disposal Combustion flue gases... 

This chapter has provided a range of mathematical models that can be used to characterize the effects of minor components on membrane performance. However, the quantity of good experimental data that can be used to fit these models remains quite limited. Good characterization of membrane performance in both pre-combustion and post-combustion flue gases will require accurate experimentally based determination of parameters such as Flory-Huggins interaction parameters, Langmuir constants and plasticization potentials. 

Combustion flue gases travel downward parallel to the tubes and pass through tunnels at the radiant section floor into the convection section where a high level of heat recovery is obtained assuring maximum fuel efficiency and optimum operating economics. 

Particular attention is given to separation SO2 and NOx from power station exhausts. Environmental regulations pertaining to emissions from stationary fossil fueled power sources have focused on SO2 because it was implicated as an important component in acid deposition. Nitrogen oxides, including NO and NO2, have also been implicated as precursors to acid precipitation, whereas N2O is considered a potentially important greenhouse gas. Activated carbon is used as an adsorbent for the removal of SO2, and also as a catalyst for the reduction (and hence removal) of NOx from combustion flue gases. 

The specific surface area of Darco FGD carbon, manufactured by American Norit, was 502 m /g. FGD is a gas-phase carbon and has heen used for removal of vapor-phase mercury from combustion flue gases. It had a mass median particle size of 15 pm. Compared with ICDACs, commercial Darco FGD carbon had a higher ash content (32.1 wt.%) and lower total sulfur content (0.98 wt.%). FGD carbon contained less microporosity, about 17 % of the total porosity than those of the ICDACs (44 to 74 %). 

Ellison, W., 1993, Regulations on Air Pollution Control, International Atomic Energy Agency Research Co-ordination Meeting and Seminar on Radiation Processing of Combustion Flue Gases, Warsaw-Zakopane, Poland, May 24-28. 

Indirectly gas-fired rotary kilns e.g. for the production of powders or in cases where combustion flue gases are harmful to the catalyst material ... 

Fly ash Coal combustion fly ash a by-product of coal-fired power generation and comprises the fine ash fraction that is carried along with the combustion flue gases. Fly ash is a highly heterogeneous, partially amorphous material with a variable composition that depends on the coal fuel properties. Depending on its quality, it is used as supplementary cementitious material. 

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