CR Clean Air - Model FS71 - Jet Venturi Fume Scrubbers
The Clean Air, LLC Jet-Venturi Fume Scrubber is a dependable device designed to entrain and scrub large volumes of gases without the use of complicated baffles or moving parts. Motivating fluid, generally water, leaves the nozzle in a hollow cone spray, creating a draft which draws the gases and vapors into the moving stream where they are continuously scrubbed or absorbed. Subsequent separation is accomplished in units specifically designed to meet state and federal pollution requirements or to recover valuable product.
The Jet Venturi Scrubber utilizes a liquid motivated ejector design to entrain contaminated gases, generally without the need for a blower. The relatively high liquid-to-gas ratio, liquid atomization, and open internal design provide effective scrubbing of heavily contaminated gases with minimal maintenance and virtually unlimited turndown capabilities. Its ability to handle wide ranging conditions while removing both toxic gases and particulate matter makes the Jet Venturi one of the most flexible designs available. It is often used as a first stage in a multi-stage pollution control system.
The Jet-Venturi Fume Scrubber is one of the most economical answers to the growing problem of air pollution. It is an efficient means for minimizing smoke and undesirable odors, cleaning and purifying air and other gases as well as reclaiming valuable product which may be exhausting to atmosphere. It can also be used as a concentrator by having the motivating fluid absorb the fume for recirculation until a desired concentration is reached. And the Fume Scrubber can do all this with a minimum of maintenance since there are no moving parts and because it operates at low velocities.
Efficiencies Are High: The efficiency of a Jet-Venturi Fume Scrubber varies with a variety of factors including temperature, liquid-gas ratio. concentration of contaminants, operating pressures, etc. Here are some typical efficiencies of a single stage ejector Venturi Fume Scrubber which give an idea of the high efficiencies which can be achieved:
The Fume Scrubber is also effective for simultaneously removing dust from the gas stream. With 80 psig water pressure, for example. the efficiency would be better than 99% on all particles over 4 microns in size. An efficiency of over 90% at this pressure could be anticipated for all particles over 2 microns in size. Special jet scrubbers are available for submicron size particles.
Separators: Fume scrubbing is just part of the job. The scrubbed non-condensibles must be separated from the contaminated liquid as they are discharged into a separator box. The gas can then be passed to atmosphere or to another fume scrubber in series if higher efficiency is required.
Because of the co-current nature of the Jet Venturi Scrubber. it is necessary to provide a method of separating the gas and liquid streams. Small liquid droplets and mist in the gas stream must simultaneously be reduced to meet state and federal pollution requirements. Separators are individually engineered for each application, incorporating the necessary tanks, entrainment separators, recycling equipment, heating or cooling coils and other components.
Normally all Fume Scrubbers are custom designed for a particular application. By doing this, each Fume Scrubber operates at the optimum efficiency at the design conditions. This would be impossible if each scrubber size were limited to standard dimensions.
Standard units are available, and make sense when conditions are not accurately known. These units are available for quick delivery in all fiberglass reinforced plastic with various capacities. Separator tanks including storage for recycle are also available in these units. For maximum efficiency it is important that the scrubber be carefully sized for the specific application. Here are some of the reasons it is important to let our specialists help you select the Fume Scrubber you need:
- Water Pressure. The higher the pressure the more efficient the unit, especially on dust collection. Whenever a recycle system is involved, it is better to specify a water pressure of 80-100 psig at the nozzle since this will normally result in a smaller unit and lower horsepower requirement than a system based on 40-60 psig. Some processes require large quantities of water whereas others can get by on much less. The optimum pressure and liquid consumption will be recommended for your application.
- Since the unit requires no fan, the exact amount of draft required should be computed if at all possible. This is a controlling factor in terms of both water volume and pressure.
- Systems Components. Jet Venturi Fume Scrubbers are available as individual units for incorporation in your own design or in conjunction with complete package systems designed and engineered by our specialists. Where total design is desired, it is important that we know the requirements for auxiliary equipment such as motors, liquid level controls etc.
- Once-through vs. Recirculating. Depending upon the process or pollutant involved. further treatment may be required. A recycle loop will help to concentrate the contaminant to cut the size of further treatment equipment. Recycle can also be used for the recovery of material being scrubbed. For example, a stream containing air, HCl, water vapor, and C02 can be scrubbed with water to produce an HCl stream which can then be stripped of HCl for recovery.
Example 1 (motive pressure given): Require a scrubber for 800 CFM of contaminated air at 80°F. Pressure drop to the scrubber is 1″ w.c. P. Available water supply is 60 PSIG.
Since the pressure drop to the scrubber is 1″, 1″ w.c. draft will be required.
From the capacity curve, 800 CFM can be handled by an 88 Fume Scrubber. The required horsepower is 2.6.
Example 2 (liquid flow given): Require a scrubber for 9.000 ACFM of air at 1 1/2″ draft with 900 GPM of 10% NaOH solution.
Since the curve for an 88 Fume Scrubber begins to flatten out at about 1,000 CFM, we need a unit with approximately 10 times the capacity.
Since we must use 900 G PM for scrubbing, the required pressure is
From the curve it is obvious we can reduce the motive pressure required by increasing the size of the unit. Taking the same problem as above, we will use a 30 x 30 unit.
Scrubber Sizing: For Example 1 of scrubber sizing, look on separator sizing curve for 800 CFM and draw a line across to the separator curve. A 30″ diameter unit would be required.
For Example 2, the required unit from the curve at 9,000 CFM is a 96″ unit.
Custom Versus Stock Units: For optimum efficiency it is advisable to custom design Fume Scrubbers. When conditions are not accurately known, however, stock units may be the most economical answer. These units are available in inert fiberglass reinforced polyester construction so that they can be used for almost every conceivable condition. Their light weight allows use on roof areas without additional supporting steelwork. Roof mounting frees valuable floor space for other equipment. Separator tanks including storage for recycling are also furnished. Pilot plant test units are available for preliminary tests in your own plant. This may be particularly important if the pollutant is unusual or the actual operating conditions are unknown. Test facilities are also maintained for double checking on specific parameters.
Materials Of Construction: Since the Fume Scrubber has no moving parts or intricate construction, the problems of corrosion and erosion can be overcome much more readily. The choice of materials is almost unlimited. The Scrubber can be made from carbon steel. stainless steel. nickel or any of the non-ferrous alloys. It can be fabricated from fiberglass reinforced polyester (FRP) polyvinyl chloride (PVC), or other plastics, or it may be lined with an endless variety of appropriate material depending upon process need. Since various impurities in the gas flow may alter the resistance of materials to attack, your own experience with other equipment in similar service may prove to be the best judge. When this previous experience is not available, the answer may be found in our extensive case history file.