Cyclone scrubbers

FIG. 17-52 Cyclone scrubbers, (a) Cbemico Air Pollution Control Corp. (h) Diicon Co., Inc. 

Municipal and industrial incinerators Pathological incinerators Industrial waste Odors, hydrocarbons, HCl, dioxins, furans Particulates, smoke, and combustion contaminants Proper charging, acid gas scrubber, baghouse Modified fuel feed, auxiliary fuel and dryer systems, cyclones, scrubbers... 

Zinc Roasting Sintering Calcining Retorts electric arc Particulates (dust) and SO2 Particulates (dust) and SO2 Zinc oxide fume, particulates, SO2, CO Exhaust system, humidifier, cyclone, scrubber, electrostatic precipitator, and acid plant Exhaust system, humidifier, electrostatic precipitator, and acid plant Exhaust system, baghouse, scrubber or acid plant... 

Steel mills Blast furnaces charging, pouring CO, fumes, smoke, particulates (dust) Good maintenance, seal leaks use of higher ratio of pelletized or sintered ore CO burned in waste-heat boilers, stoves, or coke ovens cyclone, scrubber, and baghouse... 

Normal superphosphate Sip4, HF Venturi or cyclonic scrubber... 

Diammonium phosphate Gaseous F, NH, Venturi or cyclonic scrubber with 30% phosphoric acid... 

A wet cyclonic scrubber is a cyclone collector with centrally located, coarse water sprays. These water sprays are usually directed radially outward,... 

Operation Concentration Particle Sizes Gravity Impinge- ment Cyclone Scrubbers Electrical... 

Figure 4-58. Cyclonic scrubber. Courtesy of Chemical Construction Corp.

The term cold end commonly refers to the back-end convection area of the boiler system where an economizer, air-heater, or ID fan may be found, together with the stack and (with high dust-burden flue gases) possibly a cyclone scrubber or electrostatic precipitator. Any fuel treatment applied in this area may be considered to act as a postcombustion additive. 

Cyclone Scrubbers The vessels of cyclone scrubbers are all in the form of cyclones, which provide for compact integral entrainment separation. The gas-liquid contacting section normally uses some sort of spray generator to disperse liquid throughout the gas. Performance is similar to other spray scrubbers. 

Almost all particle-separating devices can be converted into wet scrubbers by adding liquid spraying systems. Three types of commonly used scrubbers are the spray chamber, cyclonic scrubber, and venturi scrubber. Figure 7.18 shows a simple spray chamber in which water is sprayed through a series of nozzles into a settling chamber. The dust-laden gas is fed from the bottom of the chamber and exits from the upper portion of the chamber. 

The collection of particles is achieved in a countercurrent flow between the water droplets and the particulates. In a cyclonic scrubber, water is injected into the cyclone chamber from sprayers located along the central axis, as shown in Fig. 7.19. The water droplets capture particles mainly in the cross-flow motion and are thrown to the wall by centrifugal force, forming a layer of slurry flow moving downward to the outlet at the bottom of the cyclone. Another type of scrubber employs a venturi, as shown in Fig. 7.20. The velocity of the gas-solid suspension flow is accelerated to a maximum value at the venturi throat. The inlet of the water spray is located just before the venturi throat so that the maximum difference in velocity between droplets and particles is obtained to achieve higher collection efficiency by inertial impaction. A venturi scrubber is usually operated with a particle collector such as a settling chamber or cyclone for slurry collection. 

The absorption of gases in wet cyclone scrubbers. Trans. Am. Inst. Chem. Etig., 34 181-198. 

Deodorization. The neutralized/bleached oil is pumped into a deaerator operated under a pressure of 500 Pa to evacuate entrained air. From the deaerator, the oil passes through a shell and tube economizer and is heated to a temperature of 240°C by means of a thermal oil heater. The stripper and deodorizing column operates under a pressure of 600-1000 Pa volatile components such as low-molecular-weight fatty acids, ketones, aldehydes, and other odoriferous substances are stripped off by live steam. The rising vapors laden with volatile components pass through a cyclone scrubber where fresh fatty acid oil is sprayed on top of the vessel to recover outgoing fatty acids. 

Figure 20.6. Wet scrubbers, (a) Wet cyclone scrubber, (b) Spray scrubber, (c) Venturi scrubber, (d) Orifice scrubber.

Particle recovery is currently performed in metallic or porous polymeric baskets this method is satisfactory for bench scale studies whose aim is, in most cases, limited to studying morphology and particle size. At the industrial scale, this solution may prove to be inadequate. Besides such conventional separation techniques as cyclones, scrubbers, and electrostatic precipitators, different approaches were recently explored (183,184). 

Venturi Cyclonic. — This system consists of a venturi followed by a cyclonic spray scrubber. A low-pressure pamp circulates scrubber liquid to the venturi where it becomes atomized and thoroughly mixed with the gas by the extremely high velocity in the throat. Gas from the venturi enters the cyclonic scrubber... 

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