Ductwork, cost

The most common type of air preheater on new units is the rotating wheel. On retrofits, heat pipes or hot-water loops are often more cost-effective because of ductwork costs or space limits. 

It is of prime importance to keep air and gas leakage from ductwork at a minimum, as it represents increased fan running cost and the waste of treated air. Leakage into extract ductwork reduces the efficiency of the collection system. 

The orifice plate is simple to manufacture and has a relatively low cost. It does, however, create a quite large permanent pressure loss when installed in the ductwork. The venturi is smoothly shaped with a low permanent pressure loss but requires more space and is more expensive. The nozzle is a compromise betw een the orifice and the venturi. All three devices are standardized flow meters with very detailed descriptions of their geometry, material, manufacturing, installation, and use. -... 

Generally, adsorption, absorption, and biofilter units require more space than compact incinerators and condensers. If the plant room is restricted, a local roof-mounted system may be the best alternative. However, roof structural reinforcement may be required even for small and lightweight units. Consideration must be given to the effects of noise and vibration. Small adsorption systems, such as adsorption canisters, require an additional central regeneration unit on site, or they must be regenerated or disposed of off site. A central regeneration unit may require long runs of costly ductwork." ... 

Duct design The process of sizing ductwork to ensure the optimum performance in initial costs, running costs, and the distribution of air in a duct distribution system. The design techniques may be... 

Hoods usually have a light built into a sealed opening, making it explosion-proof for use with flammables. Fans used for flam-mables must also be explosion-proof. Those used for corrosive fumes must be made of material resistant to such fumes. The ductwork must also be corrosion resistant, a matter often overlooked. Built-in exhaust fans make installation and servicing easy, but some tend to be noisy. Remotely installed fans are generally quieter and may serve more than one hood. The chief problem with fans is that they are often improperly serviced. Lubrication and belt tightness must be checked as specified by the manufacturer, or costly repairs will result. 

The feasibility of detection-based defensive strategies also depends on how the detectors are deployed and how they are actually used. Deployment considerations include the number and placement of detectors, whether in open spaces or in HVAC ductwork. In this respect, airport terminals are likely to be more difficult to protect by this strategy than are aircraft, owing to the vastly greater air volume and necessarily greater physical spacing between detectors in terminals. To the extent that more than one type of independent detection or verification system is needed to achieve acceptable POD and PFA, the system costs are multiplied. 

Cost of air conditioning. Price includes compressor, motor, starter, controls, cooler, condenser, and refrigerant. Does not include cooling tower, pumps, foundations, ductwork, and installation costs. 

Cost of ductwork. Price is for shop-fabricated ductwork with hangers and supports installed. 

Op. Cit., EPA Air Pollution Control Cost Manual (6th ed.), Section 2, Chapter 1 Hoods, Ductwork, and Stacks. ... 

The most common sorbent is hydrated lime, but other sorbents can also be used. The sorbent is usually injected directly into existing ductwork, and so the amount of space required is negligible compared with that of other flue-gas desulfurization processes. This makes dry sorbent injection a very low-cost option. 

VRLA will also require cooling to some degree through fans and ductwork to be consistent, this mass and cost should be factored into the energy density of VRLA. 

Wet scrubber wet cyclone or centrifugal scrubber, c/s, including housing and spray excluding fan, ductwork and instrumentation. FOB cost = 50000 at inlet gas flow rate = 10 Nm /s with n = 0.68 for the range 0.5-35 Nm /s. L-rM ... 

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