Pressure Switch Air

Flexible Air Pollution Control Technologies

There are many various types of VOC control technologies in today’s market, but most of them are not right for your application. Knowing the various principals behind each of the technologies will help you choose the technology that’s right for your waste-gas application. As Global concerns are increasing at a rapid pace, and with more pressure being placed on governmental authorities to create and enforce regulations that require often higher destruction rates and improved capture procedures of air pollutants. Many industries around the world and air pollution control equipment manufacturers are developing better technologies to meet these growing domestic and international regulations while providing improvements in air pollution control investment and the associated operating costs.

A diversity of pollution control equipment is currently available, but many manufactures fail at many technologies and have themselves trapped into splitting technologies into separate equipment. Pioneering technologies and system controls are now available to alter the basic thermal oxidizer equipment arrangement and create many distinctive types of air pollution control technologies.

Equipment modifications to your existing equipment should be simple, inexpensive and should be able to be completed in the field within a few days. It is significant to understand the options, benefits, and potential shortcoming of the different air pollution control equipment types.

Thermal Oxidation

These applications are most often used to convert organic hydrocarbons into carbon dioxide (CO₂) and water (H₂O). By increasing the thermal temperature of the waste-gas process stream breaking of the hydrogen-carbon bonds occurs, this process allows new bonds to be created such as CO₂ and H₂O.

Closed Thermal oxidizers characteristically are designed with a 0.7 sec or greater total residence time. Residence chamber time is the instance when the waste process stream is enclosed within the heated area and is critical for proper mixing. Often oxidizer designs fail to complete the proper mixing in the retention time frame and additional fuel must be burned to meet the permitted values.

Regenerative Thermal Oxidizer

Regenerative systems are thermal oxidizers operate at high temperatures, between 1400°F to 2,300°F. These systems use structured ceramic stoneware or other heat exchange media to retain the generated thermal energy. In most designs, the media is mounted in vertical or horizontal columns. The process air stream is passed through a column of ceramic media as it enters the regenerative thermal oxidizer.

The waste-stream is heated to the oxidation temperature within the combustion chamber and if the process stream doesn't have ample VOCs a burner assists in bringing sufficient temperature to the combustion chamber.

Typical temperatures of VOC waste streams of hydrocarbons range from 1400°F to 1600°F, however higher temperatures and retention times are required for halogenated hydrocarbons 1800°F to 2300°F. The waste air stream then exits the oxidizer through a second media column. The second column preserves or stores energy from the super heated air stream. By continued valve cycling the waste-gas air stream switches between the heat sink columns or heat recovery beds, by this process the incoming air stream is heated by the heat sink media, which in the previous cycle accepted the heat from the waste-gas air stream exiting the combustion chamber.

When the heat recovery bed starts to lose radiant heat to the incoming air stream, the valves cycle and becomes the other heat recovery bed becomes the acceptor of energy or heat, continued repeating of the valve cycle assures minimum heat lose. For greater heat retention within the heat recovery chambers the valve cycle rate is increased. The principle is simple and proven.

Regenerative thermal oxidizers can be designed with one, two, or three heat recovery beds or columns. Some of the regenerative equipment characteristics are moderate capital equipment prices with high thermal efficiency. Destruction is high typically 98%-99% with lower energy costs. Loss through radiation is slightly higher due to the large surface area, however radiant heat loss can be controlled by the use of high density 12lb. or higher ceramic fiber insulation. Most applications include lower VOC Control levels with higher waste-gas flows. Systems can be designed skid mounted for quick and effective installation, start-up and training times.

RTO systems have materialized as the leading air pollution control technology because of their very high heat recovery, which produces an outstanding operating cost advantage in comparison to other technologies while maintaining high flexibility for many types of waste gas processes. Typically these systems are larger, requiring greater installation work, unless the system is skid mounted.

Development efforts have focused on compact, modular and cost-effective Regenerative Thermal Oxidizers for the VOC Abatement. These systems can be modular skid mounted and designed to ship as completed assemblies with width dimensions that will comply with commercial trucking laws without special shipping considerations or wide-load road permits.

Regenerative Thermal Oxidizers can be completely pre-assembled, including all control systems, piping, conduit and electrical wiring. This pre-assembly minimizes the installation costs and efforts while maximizing quality control over the product. Oxidizers that are pre-assembled may take onrun conditions, control systems check out and calibration preceding shipment, diminishing equipment operation and control failures at the plant site. This allows for a shorter installation, startup and training times without the threat of equipment failure.

Regenerative Thermal Oxidizers are currently designed with minimal captured volume for design destruction efficiency 98% without the capturing of the VOCs being exhausted during any valve switch period. Most regenerative systems are constructed to accept optional VOC capture vessels called puff chambers when destruction efficiency requirements exceed 98%. The equipment design will permit regenerative oxidizers to be upgraded in the field with insignificant costs and time.

Regenerative Catalytic Oxidizers

Regenerative Catalytic oxidizer is similar in design to the regenerative thermal oxidizer. The addition of catalyst media to either the center of the media or the top of the media beds allows lower operating temperatures 400°F to 800°F. Depending on component design, Regenerative Catalytic Systems may also can be operated as a Regenerative Thermal Oxidizer after catalyst degradation.

Systems have small or no NOx formation, low levels of CO emission, very low operating costs with high thermal efficiency. Caution must be used not to foul or plug the catalyst heat bed and more stringent PLC control must be used. These systems have higher capital costs due to the catalytic media but reduce the energy consumption up to 50%.

Catalytic Oxidizers

Catalytic oxidizers are alternatives to other high temperature thermal oxidizers. These systems oxidize waste gas streams into carbon dioxide and water. Their successful operation is limited to a more controlled range of applications than other thermal oxidizers. But, catalytic oxidizing systems offer significantly lower fuel consumption, operating costs and reduced CO and NOx emissions.

The two essential parts of the equipment are; pre-heat section which is designed to achieve a temperature uniformity of the preheated waste stream, and the catalyst bed, where the greater part of the oxidation reaction takes place. The oxidation of most hydrocarbons with the catalysts occurs very quickly in the range of 400°F -900°F. With most thermal oxidizers, the hydrocarbon oxidation reaction requires a high temperature, 1,200°F -1,600°F.

Catalytic oxidizers are restricted to applications in which the waste stream has lower particulate loading or media poisons; which can cause reductions in the effectiveness of the catalyst. Typical poisons are principally silicon and phosphorus, which cover the catalyst; halogens harm the active metal coating; and sulfur, may reduce the activity of some catalysts.

Attrition, deposition, coking can cause the media surface to become damaged and replacement is necessary.

Solvent Recovery Systems

Adsorption technology is the physical attachment of VOC ions and molecules onto the surface of another. The essential principle of adsorption when pertaining to plant waste gas emission control is when the volatile organic compound within the process air stream passes through a bed of very high surface area solid which usually consist of the following materials; activated carbon, silica gel, or molecular sieve material.

Once the empty spaces within the adsorption material are filled with VOCs to capacity, the waste gas process stream is then diverted to a second adsorption container while the original container removes the VOC bonding by passing high pressure stream or by raising the temperature within the adsorption container by thermal induction releasing highly concentrated VOCs. The highly concentrated volatile organic compounds within the air stream passes through a condenser and a distillation column whereby it is separated and recovered from the VOC laden process stream condensate. Alternative solutions to applying use of a condenser and distillation column is to exhaust the saturated VOCs to a thermal oxidizer during non-peak times, when the thermal oxidizer is not heavily used and can operate with higher VOC levels.

Higher investment capital is required with moderate energy cost. Destruction efficiencies range from 95-98% with higher maintenance costs from replacement or regeneration of adsorption material. Additional distillation is necessary to separate several solvents with the potential to reuse or sell the solvent.

Right Technology for the Operation

Which one of the listed technologies may best be applied for your application? Your answer can be difficult depending on the method you take in the evaluation process. The best approach is to find a vendor that offers an evaluation of your waste gas process stream and production requirements and to make recommendations for the best technology. Most vendors will offer a free evaluation to assist you. Some of the information is required to make the right decision are listed below:

A.      Total number of emitting sources

B.      Annual hours for each of the emitting sources

C.      Form each source the flow rate, SCFM or M³

D.      Total (lb/hr or kg/hr) of VOC material from each listed source

E.       Composition of the process stream (VOCs, particulates, silicon)

F.       Energy costs

G.     Regulatory requirements for your facility

After collection of the data, a request for quotation (RFQ) can be sent to selected vendors. A vendor should have the appropriate technologies in its product mix and is willing to stand behind their equipment.

Guidelines for a Correct Equipment Purchase

When evaluating the options, include operating, installation, training, plant control, and equipment capital costs. Capital and operating costs should be based on the actual utility costs, operational times and annual operating schedules of the plant. Ask for a document presenting all the features for the proposed equipment to ensure you are making a correct comparison. Request a production schedule for the system to ensure that the facility can meet any of your regulatory requirements. Working with proper data, applying utility costs, facility limitations, regulatory requirements and plant operating schedules all comprise important roles in determining the correct abatement equipment. Working with a vendor can greatly assist in making the right product choice.

For more information about air pollution control equipment and VOC abatement, please visit our website: American Environmental Fabrication & Supply or call Scott Manes +1 (918) 708-1253 Ext. 4001

my well only runs 10-12 seconds, then shuts off? I tried adjusting the pressure switch.?

I also bought a new pressure switch, checked the air pressure.
The bladder tank holds pressure when no water is being used, it is only 2 years old. I checked the air pressure in the tank by turning of power, draining the water out of tank and checking with tire guage. It is 28psi. , pump kicks on at 30. When using water (shower) the pressure goes down to 30, pump starts and only runs for 12 seconds then off. It never gets to 50 psi to trip pressure switch. I adjusted the shut off nut and no luck. If i run multiple sources of water(shower, washer) The pressure will drop to 0 and the pump doesn't always kick on right away. Then it randomly kicks on and repeats the cycle. Thanks

Make sure your tank isn't leaky. Another sign that might be the case is if the pressure at the faucet goes way down before the pump kicks in.

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