Inlet air filters

3 Inlet Air Filters. Air used for cooling a reactor will emerge radioactive. The activity is due partially to gasieous atoms naturally occur-ring in air, such as argon, and partially to dust in the air. Not much can be done to reduce the activity from the first, but the latter can be reduced considerably by suitable filtering.  

In the.first considerations of the radioactivity problem of the MTR. cooiing- air system, a filter design similar to that used for- the pile at ORNL was included in the exhaust side of the system. Further consideration of the problem along with economy measures prompted omission of the filters in the exhaust side of the reactor cooling-air system. 

The only fiIters- included in the reactor air-system are the glass wool filters at the inlets to thesystem. A brief description of the processing the air. encounters before entering the reactor is now gi Ven.  

The elimination of the exhaust side filters, from the technical stand-, point,is justified principally by a comparison of the MTR coo ling-air system with that of other reactors. The air systems of the MTR is similar ia the following respects to other reactor systems. 

The major portion.of air entering the reactor has been filtered to some degree. 

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Blowing hot air A typical arrangement is shown in Figure 31.9. The bus duct enclosure is provided with inlet and outlet valves at suitable locations. Hot air is supplied through the inlet valve until the interior of the enclosure is completely dry. The blowing equipment comprises an axial flow fan. a heater unit, an inlet air filter unit, pressure... 

The prime design objeetive of the filter system is to proteet the gas turbine. The performanee of the gas turbine inlet-air filter system has important and far-reaehing influenees on overall maintenanee eosts, reliability, and availability of gas turbines. There are three major results of improper air filtration (1) erosion, (2) fouling of the axial-flow eompressor, and (3) eorrosion of the gas turbine hot-gas path inlets. The importanee of the inlet-air filter, as it relates to eaeh of these three phenomena, ean be appreeiated if... 

The inlet air duct, starting at the roof level of the cubicle, leads to the inlet air flap, inlet air filters, and steam heated heat exchanger coils to heat the inlet air. This heated air is directed through a 1/2 supporting grid and 100 mesh screen on the bottom of the product container. 

Typical impurities contained in air are shown in Table 3.4. Coarse particulate matter will be removed in the inlet air filter before the main air compressor. As the air is compressed and intercooled water is condensed, a significant portion of the water-soluble acid gas contaminants are removed in the condensate. If ambient concentrations of S02 and NOx are high, special alloys may be necessary in the intercoolers. A DCAC is also an efficient scrubber of acid gases. Any acid gases not removed in the coolers will be either adsorbed reversibly in the adsorbers, if in its vapor state, or chemically reacted with the adsorbent, if dissolved in water condensate. Normally, DCACs and separators are designed such that entrained condensate drops are unlikely to enter the adsorbers. 

Polyethylene, polystyrene, and PP fall under the classification of nonhydroscopic resins. These types of polymer resins collect moisture on the surface of the pellet only. The moisture can originate from several potential sources. Such moisture in some cases can be removed very easily by moderate preheating immediately prior to feeding the material into the mold. In some cases it is sufficient to provide vents at the transition from the hopper to the mold cavity. In some situations the moisture can be removed by passing warm air over the material. The equipment utilized to heat air and dry resins is usually very simple, e.g., an inlet air filter, a blower, and a controlled electric heater, as shown in Figure 47.11. 

A schematic diagram,of the reactor cooling-air system is shown by Fig. 8.1.A. The description of the system will in general.follow the air flow path, starting with the inlet air. filters-.a.t. the. reactor faces and ending with the stack. .-iv-. ... 

Gas turbine inlet air cooling to increase density of air to improve the overall efficiency of the combustion cycle as manifested by improvement in the heat rate. It is also noteworthy that eooling will serve to pre-filter and reduce velocity and hence the pressure drop across the inlet air filters providing additional performance improvement. 

The general environment can also affect the parts life of gas turbines. Many plants are located in areas with corrosive or abrasive matter in the atmosphere. Desert sandstorms, saltwater mist, chemical fumes, and airborne fertilizers are examples. However, the effects of these types of environments can be minimized by multistage high-efficiency inlet-air filters and mist eliminators as well as the presence of correct materials and protective coatings in the compressor and turbine. 

Inlet air filter cleaning Outside of heating tubes... 

Sterile Filtration of Gases. Primary appHcations for sterile gas filtration are the sterilization of fermentor inlet air, fermentor vent gas, vents on water for injection tanks, and vacuum break filters during lyophilization. Operational and process considerations apply. Typically, the membrane in gas... 

Evaporation of medium provides a little cooling. The inlet air to particulate filters must not be near saturation because condensation of moisture on the filter medium mobihzes contaminating microorganisms so that their chances of penetration are greatly increased. Sometimes humidified air is used, and the filter unit is heated to prevent condensation. However, this is common only for small equipment where the extra operations are relatively easy to install and maintain. 

HEPA and ULPA filters have been developed. In the CEN EN 1822 1998 test method, the filter s efficiency is determined for the most penetrating particle size (MPPS). Depending on the filter s total level of separation and leakage, the filter is classified as HIO, Hll,.. ., H14 and U15, U16, or U17. HEPA filters are commonly used for inlet air in the pharmaceutical, optical, and food industries. 

For reasons of hygiene, the inlet air should be filtered in two steps. The first filter in the air intake must be at least F5 (EU5) quality but preferably F7 (EU7). The second filter step should be effected by a filter of at least F7 (EU7) but preferably F9 (EU9) quality. If there is only one filter step, the minimum requirement is for F7 (EU7) quality. 

Effective inlet air filtration is required to ensure satisfactory operation of the engine. The location of the unit determines the most appropriate filter system to use. Desert environments where a large amount of sand particles could be expected in the ambient air may use an automatic roll type of filter that allows new filter material to be rolled in front of the inlet without frequent shut-downs to change filters. Arctic or extremely cold locations may use pad type filters, snow hoods to prevent blockage, and exhaust recirculation to prevent icing. Filter assemblies for offshore marine environments may include weather louvers, demister pads, and barrier elements for salt and dirt removal. Screens may be u.sed for insect removal prior to filtration in areas with bug problems. 

In yet another incident a hydraulie hose leaked, and an oil mist was sueked into the air inlet of a diesel engine. It continued to run for three to five minutes after the normal fuel supply was isolated. The air filter on the engine was missing. Had it been present, it would probably have trapped the oil mist [23]. 

Air-conditioning, having the air cooling coil with drip tray under, expansion valve, fan and motor, air filters, inlet and outlet grilles. They may also include dampers and duct connections for return and fresh air, heaters, humidifiers and various controls. 

A vacuum system like that shown in Figure 4-3 will be used,36 since delivery to a single receiver is desired. For this system there will be 100 ft of horizontal pipe and 35 ft of vertical pipe. The pressure drop across the air filter at the air inlet should be about 0.5 in. H20 and that across the receiver should be negligible. The pressure drop across the fabric filter is 4.0 in.H20 and across the receiver is 3 in H20. 

An air inlet area of at least 400 cm2 and a louvered exit of 75 cm2 are recommended for target capacity and physical size of the appliance. The efficient and quiet centrifugal fan unit is popularly used in air conditioners and air purifiers. It costs less than the other fan units of similar size and is easy to install and assemble. A fan with adjustable air deliver rate of 0 to 250 cfm will be used to draw air through the air filter, dehumidifier and purifier units. A smaller fan with air delivery rate of up to 10 cfm is needed for the regeneration... 

Inlet filter. In air compressors filter selection is an important factor in preventing fouling. Most high-efficiency air filters have a triple-stage filtration system. Also these filters often have rain shades to prevent water from entering the filters. Site conditions play a very important part in the selection of the filters. 

Precipitator inlet—6 thimbles, 2 cold traps, 2 glass papers Precipitator outlet—4 thimbles, 1 cold trap, 1 filter paper Stack sample—2 thimbles, 1 trap, 1 glass paper Inlet air—1 thimble and 1 glass paper... 

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