Waste-heat recovery device

Preheater vibration. Air preheaters or any type of waste-heat recovery device designed for horizontal flow across vertical tubes, may be subject to vibration produced by the velocity of gas across the tube banks. The velocity produces a vortex-shedding wave pattern that could correspond to the natural harmonic frequency of the tube bank. If the natural harmonic frequency is reached, excessive vibration of the tubes will occur. Redesign of the internal baffle system by inserting dummy baffles can stop the vibration. 

Air preheaters, or any type of waste-heat recovery devices that are designed for horizontal flow of fuel gas across vertical tubes, are subject to vibration produced by the velocity of the gas across the tube banks. 

Waste heat Heat from a process that is surplus to requirement this heat may be supplied to a heat recovery device for use in another part of the plant or process. 

The exhaust gases are generally discharged into dust and fume knockdown equipment to avoid contamination of the atmosphere. Gas-cleaning equipment includes cyclones, settling chambers, scrubbing towers, and electrical precipitators. Heat-recovery devices are utilized both within and outside the kiln. These result in an increase in kiln capacity or a decrease in fuel consumption. Waste-heat boilers, grates, coil systems, and chains are used for this purpose. 

When the last two sentences are related to heat transfer within heat recovery devices (instead of within furnaces), the low volume and velocity do present concerns with oxy-fuel firing. Heat recovery equipment with larger flow passage cross sections can benefit more from the triatomic gas radiation with oxy-fuel firing. A good example of this is the double-pipe stack or radiation type recuperator. However, they must have parallel flow at the recuperator s waste gas entrance to prevent overheating there. 

When hot raw gas is to be cooled directly or if it has already been cooled in a waste-heat recovery system, it will normally be treated in a wet scrubber. Wet scrubbers are devices that utilize gas/ liquid contacting to cool the gas stream, condense high-boiling hydrocarbons, dissolve some constituents, and separate particles from gas streams. There are many different wet scrubber designs, but all utilize similar mechanisms. 

The use of thermoelectric materials (TMs) and devices (TDs) for heating, cooling, and power generation at modest maximum temperatures (e.g., 200 C) has occurred for decades now. Further developments of compositions usable to 500°C are actively underway at many companies, universities, and federal research laboratories because achieving that capability would enable the exploitation of many additional waste-heat-recovery power-producing situations. 

To overcome such hurdles, special devices have been proposed and tested, which are based on internal heat recovery of waste heat through the adoption of Swiss roll geometries, such as those reported in Figure 12.7 [52]. 

National Emission Standards for Closed Vent Systems, Control Devices, Recovery Devices and Routing to a Fuel Gas System or a Process National Emission Standards for Equipment Leaks—Control Level 1 National Emission Standards for Equipment Leaks—Control Level 2 Standards National Emission Standards for Oil-Water Separators and Organic-Water Separators National Emission Standards for Storage Vessels (Tanks)—Control Level 2 National Emission Standards for Ethylene Manufacturing Process Units Heat Exchange Systems and Waste Operations... 

An expander is a mechanical device for converting part of the energy of a process stream into useful mechanical work, thus causing decreases in both the temperature and pressure of the process fluid. There are two areas of application for expanders—power recovery and refrigeration. In power recovery, the usual objective is to generate electrical power from waste heat, while in refrigeration (or liquefaction) the objective is to cool the process fluid, and the work produced is of secondary importance. 

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