Pseudo flue gas

Air and gaseous S02 in the required ratio enter Mixer 6 to mix fully with each other, and the resulting pseudo flue gas is divided into two equal streams to enter Absorber 7. The air flow rate is adjusted by a butterfly valve in the pipeline and measured with a Pitot tube-pressure difference meter and that of S02 by the rotameter 5. The total gas flow rate is also monitored by a wind velocity meter of DF-3 type at the gas outlet of the reactor. For each run, gas-samplings are made at both inlet and outlet of the reactor, and the S02 concentrations in the samples are measured with the Iodine-quantitative method, a standard and authentic method of determining the integral amount of S02 absorbed in the reactor. 

It should be noted that when //s achieves about 90% the concentration of S02 in gas would be low enough (around 240 mg irf3 in this set of experiments). So, it can be considered that for the pseudo flue gas with a composition similar to that used in the experiments, without any other active component like C02, Ca/S = 1.0 is the most reasonable mole ratio, while for practical flue gas, an appropriately higher Ca/S should be employed to account for the additional consumption of Ca by C02. 

The following optimal or feasible conditions and structural parameters were determined liquid to gas flow rate ratio VJVG = 0.85-1.OxlO 3 m3m 3 impinging velocity u0 = 10-15 m-s 1 dimensionless impinging distance S/d0> 4 molar ratio Ca/S = 1.0 for pseudo flue gas without C02 the nozzles were mounted at the outlets of the gas conduits ... 

All the CO resulting from the pseudo solid-solid reaction is conducted, together with entrained char, from the top fluidized section through a constriction, in which the high-velocity gas flow prevents backflow, to a transport combustor, where the CO is burned to C02 with preheated air, along with as much of the char as is called for by heat balance to maintain the endothermic FeO-C reaction. The heated recycled char is separated from the off gas at the top of this transport combustor in a hot cyclone and is returned as a thermal carrier to the lower part of the lowest j igged section, while the hot flue gas from the transport combustor is used to preheat the incoming air in a recuperator. 

We have modified the SNCR reaction mechanism from the previous problem to include the simple mixing description (SNCRmix.mec). Here the entrainment of the reactive components of the flue gas (NO and O2) into the NH3/carrier jet (inverse mixing) is described by the two pseudo reactions,... 

Figure 2-80 shows a typical absorber tray diagram for the absorption of CO2 in MEA solution. Ibis figure is based on actual plant data from a 16 bubble-cap tray absorber treating atmospheric pressure flue gas for CO2 recovery. Because of the low values of solution loading involved, the equilibrium line is almost coincident with the x-axis and is not shown. A pseudo-equilibrium line (dashed) has been drawn to represent actual gas and liquid compositions from each tray. The plate efficiencies in this column vaiy from about 14% in the bottom of the column to slightly over 16% at the top. 

Check gas temperature (Ig). Using 47,900 on the right scale of Fig. 18-6, the flue gas temperature is found to be 1850°F rather than 1800°F assumed. This is satisfactory Pseudo flame temperature (< ). Moving from 30 per cent excess air on the left of Fig. 18-7 to 1850 F and then upward to an air preheat of 400 F (460 — 60), the pseudo flame temperature is 3600°F. 

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