Scrubber function

One approach to bleach production in a chlor-alkali plant is to combine it with the emergency vent scrubber function by installing multiple towers in series. The duty of the first tower is to scrub chlorine from normal vent flows under controlled conditions. The temperature is limited to 30-40°C by cooling a recirculating liquor stream around the tower. The flow rate is large enough to prevent excessive increase in liquor temperature in the tower. The chlorine flow assumed in setting the liquor recirculation rate is the sum... 

FIG. 14-118 Aerodynamic cut diameter for a single-sieve-plate scrubber as a function of bole size, bole-gas velocity, and froth density, F, g/cm. To convert meters per second to feet per second, multiply by 3.281 to convert grams per cubic centimeter to pounds per cubic foot, multiply by 62.43. [Calveti, J. Air Pollut. Control Assoc., 24, 929 (1974).]... 

Wet scrubbers rely on a liquid spray to remove dust particles from a gas stream. They are primarily used to remove gaseous emissions, with particulate control a secondary function. The major types are venturi scrubbers, jet (fume) scrubbers, and spray towers or chambers. Venturi scrubbers consume large quantities of scrubbing liquid (such as water) and electric power and incur high pressure drops. Jet or fume scrubbers rely on the kinetic energy of the liquid stream. The typical removal efficiency of a jet or fume scrubber (for particles 10 g. or less) is lower than that of a venturi scrubber. Spray towers can handle larger gas flows with minimal pressure drop and are therefore often used as precoolers. Because wet scrubbers may contribute to corrosion, removal of water from the effluent gas of the scrubbers may be necessary. 

Vessel is scrubber or small trap, is not a process component, and adequate protection is provided by downstream PSL or design function (e.g., vessel is gas scrubber for pneumatic. safety system or final scrubber for flare, relief, or vent system). 

Typical BW antifoam emulsion products include SAG 10 and SAG 30 (10 and 30% milky white emulsions, each with a viscosity of 2,000 cS at 25 °C) from Union Carbide Corporation. These same products also are used for food processing (under FDA 21CFR 173.340), for petroleum processing (as amine scrubbers, gas-oil separators, etc.), and as functional chemicals (antifreezes, hydraulic fluids, cutting oils, etc.). 

Total enclosure may be in the form of a room with grilles to facilitate air flow this functions as a hood and operates under a slight negative pressure with controls located externally. Entry is restricted and usually entails use of comprehensive personal protective equipment. Ancillary requirements may include air filters/scrubbers, atmospheric monitoring, decontamination procedures and a permit-to-work system (see page 417). 

As an indicator of conditions, the process treats 5 g s-1 of chlorine, which for the purposes of the simulation was assumed to be steady arisings, although in practice there was significant variation as a function of time and specific plant operations. There was a recirculation vessel in addition to the column sump and the combined inventory was approximately 5 m3, approximately half of which was discharged and replaced at the blow-down and make-up period. The recirculation rate to the scrubber... 

Figure 2 is a plot of the correction parameter C as a function of magnesium concentration and pH. Note that for the typical range of limestone scrubber inlet liquor pH, 5.2 to... 

A DCS is also used to control Area 400. The DCS monitors and controls the cycling of the TRBPs, the preheaters, the GPCR reactors, the scrubbers, and the product gas handling system. Each of these subsystems is controlled with a series of control loops tied to the individual control functions through input devices linked to output devices via control algorithms within the DCS. 

In the attempt to minimize odour emission, Olfactometric measurements of total odour strength give useful informations about the odour reducing efficiency of different processes as a function of parameters like dosage of chemicals in scrubbers, humidity and temperature in packed filters, flow rates, etc. 

Fig. 13. Zeta potential of the main back-end materials as a function of the pH (ionic strength = 10" mol/liter). PVA is the polymer used in the scrubber brushes its zeta potential is very similar to that of silicon oxide.

But despite the need and tile invention. Cottrell had considerable difficulty over a number of years in gaining acceptance of the electrical precipitator by industry. Today, and for a number of decades past, the electrostatic precipitator has been a major device for combatting air pollution. Since the precipitator functions only against particulates, numerous other items of air pollution control equipment, such as absorbers, scrubbers, and biters, are required and are described elsewhere in this volume. 

The apparatus consists of a simple vacuum manifold similar to that shown in Fig. 4. The vacuum manifold should be fabricated from nickel or Monel metal, with silver-soldered or Swagelok connections. Valves should be of Monel metal, and the traps and scrubber, the function of which is to remove hydrogen fluoride vapor from the C103 F product, may be constructed conveniently of poly(chlorotrifluoroethylene) (Kel-F) tubing. A nickel cylinder of 500-ml. or 1-1. capacity serves as a reaction vessel, and a 500-ml. Monel bulb or similar vessel may be used as a product receiver. The scrubber (about 1-in. o.d.) is charged with pellets of sodium fluoride prepared in a separate operation by heating sodium... 

FIG. 14-128 Superheated high-pressure hot-water requirements for 99 percent collection as a function of particle size in a two-phase eductor jet scrubber. To convert gallons per 1000 cubic feet to cubic meters per 1000 cubic meters, multiply by 0.134. [Gardenier, J. Air Pollut. Control Assoc., 24, 954 (1974).]... 

Wet scrubbing uses liquid droplets to remove fine dust in a gas stream. In all types of wet scrubbing, the basic cleaning mechanism involves the attachment of particles to the droplets. The function of the droplets in scrubbers is similar to that of spherical fibers in filtration. Likewise, the primary collection mechanisms in scrubbing are similar to those in filtration, i.e., inertial impaction, interception, and diffusion [e.g., Fan, 1989]. Secondary collection mechanisms include thermophoresis due to temperature gradients, coagulation of particles due to particle electrification, and particle growth due to liquid condensation. 

Figure 3 shows percent SO2 remaining in the scrubbed gas as a function of alkali/acid gas stoichiometric ratio at steady-state. The numbers beside each point are chloride concentration in the scrubber liquor. From an examination of this figure, it does not appear that chloride concentration has any significant effect on SO2 removal in the range studied. 

Figures 2 and 3 are the subroutines produced by the ECES program generator to describe the activity coefficients and activity of water in SUBROUTINE ACAL and the chemical and ionic equilibria, electroneutrality,and elemental balances in SUBROUTINE FCAL. These subroutines were developed for the ammonia-carbon dioxide scrubber described in Appendix I. The IF conditions are used to eliminate particular functional equations if for seme reason particular ionic species are absent from a stage. This occurs for instance on the stages above the stage where NaOH is added for pH control. Since Na+ is not volatile, any equilibria or elemental balances involving this species are not valid above the caustic feed stage.

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