Calculating the heights of a standard series of scrubbers working with complete evaporation of the irrigating liquid

Abstract

The paper discusses a hollow sprayer scrubber and cooler involving complete evaporation of the irrigating liquid. It is shown to be possible to use an empirical model to calculate the geometrical parameters. Technical characteristics are given of a standard series of scrubbers of SOI type with complete evaporation of irrigating liquid.Calculations have been performed [1, 2] on the evaporation time for a polydisperse flow of droplets (diameter of the large droplets d d , mass proportion not more than 10%, equal to 553 µm) in a hollow scrubber based on three mathematical models (empirical, iterative, and simplified), and values have been obtained for the necessary active height * (Table 1) in relation to the initial parameters of the evaporative cooling, gas temperature at the inlet to the apparatus 750°C, at the outlet 400°C, mean gas speed in apparatus 4.5 m/sec, and initial water content 0.35 kg/kg of dry gas.We consider the evaporative cooling in a standard scrubber (Fig. 1), in which there are mechanical sprayers of centrifugal type (nozzle diameter 4 mm) working at a pressure of 0.68 ± 0.01 MPa. For these devices at this pressure, the diameter of the large droplets constituted by mass not more than 10%, is 314 µm, i.e., almost half of that assumed in calculations in [1,2]. Use has been made in [1, 2] of calculation models, and the height of a scrubber has been determined required to provide complete evaporation, and the evaporation time.The calculations have been performed for the air-water system with the following initial parameters: gas temperature at the inlet 750°C, and that at the outlet 400°C; mean gas speed in apparatus 4.5 m/sec; initial water content 0.35 kg/kg of dry gases; and initial temperature of irrigating liquid (water) 20°C. Table 2 gives the results.Calculations from the iterative model (Fig. 2) show that as the size of the large droplets is reduced from 553 to 314 µm, the time needed for the droplets to attain the floating velocity is approximately 0.1 sec, which is much less than was obtained in [1, 2] (about 0.4 sec). In the standard apparatus, the smaller droplet diameter means that the evaporation is much more rapid.At the same time, the practical data were analyzed, ** which had been obtained on testing a plant for destruction of wastes by incineration, in which the hollow scrubber (Fig. 3) was installed before the sleeve filter.The water pressure ahead of the sprayers was up to 2.5 MPa, and the size of the mass-largest drops (10%) was approximately 151 µm.

Analysis of Flue Gas Condenser Operation

“…The simultaneity and interaction of all these processes in combination with various factors influencing the amount of energy produced − all this adds complexity when designing the required equipment and defining its parameters [4][5][6]. This explains the great variety of devices intended to raise the efficiency of energy resources.…”