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Flue-gas heat recovery

Electrostatic precipitators (ESP) and wet gas scrubbers (WGS) are widely used to remove particulates from the FCC flue gas. Both can recover over 80% of filtrable solids. An ESP (Figure 10-6) is typically installed downstream of the flue gas heat recovery (prior to atmospheric discharge) to minimize particulate concentration. If both low particulate and low SO requirements are to be met, a wet gas scrubber such as Belco s (Figure 10-7) should be considered. If SO removal... [Pg.328]

The cooler part of the combustion air preheater - the tail end of the flue-gas-heat-recovery train - is more likely to corrode due to sulfur dioxide (S02) condensing from the flue gas. In this area, cast iron or glass will resist the acid attack. Carbon steel preheater tubes, joined with 1.5 to 2 meters of SS 304 tubes at the cold end of the tube sheet, can ensure reasonable service life. Typically, the flue gas temperature to the stack is maintained above the dew point of S02 to prevent condensation. During startup and shutdown, condensation of S02 will occur88. [Pg.71]

Improved Flue-Gas Heat Recovery. The majority of the heat losses in cracking furnaces is contained in the flue gas which leaves the furnace. Today s cracking furnaces with integrated waste heat recovery are designed for thermal efficiencies between 90 and 93%, which correspond to flue-gas outlet temperatures of about 130° to 180°C. A further decrease of the flue-gas outlet temperature usually is not economic, as the heat-transfer surface of the upper bundles becomes too large because of the small mean logarithmic temperature difference. [Pg.171]

The gasification process is based on atmospheric pressure gasification with wet gas clean-up. The bagasse is dried to 10 % moisture in a dryer and fed to the gasifier. The gases pass through a gas clean-up system and are fed to the gas turbine to produce electricity. Steam, produced in the turbine flue gas heat recovery boiler, powers a steam turbine and the low pressure steam from the steam turbine is sent to the sugar mill to meet part of the mill s steam requirement. [Pg.836]

Fluidized beds represent the other end of the spectrum in terms of solids loading (this subject is covered in the chapter on heat transfer in fluidized and packed beds). The very considerable enhancement of heat transfer coefficients, up to a factor of 20 compared to pure gas flow at the same flow rate, has led to applications in such areas as flue gas heat recovery. [Pg.830]

The SMR-based technologies typically have a somewhat higher capital cost because the SMR furnace with its high alloy tubes and large flue gas heat recovery section is inherently more expensive than the ATR or POX technologies which are refractory lined carbon steel vessels without external flue gas heat recovery. [Pg.340]

The policy for waste heat recovery from the flue gas varies between incinerator operators. Incinerators located on the waste producer s site tend to be fitted with waste heat recovery systems, usually steam generation, which is fed into the site steam mains. Merchant incinerator operators, who incinerate other people s waste and... [Pg.300]

Assessments of control, operabiHty and part load performance of MHD—steam plants are discussed elsewhere (rl44 and rl45). Analyses have shown that relatively high plant efficiency can be maintained at part load, by reduction of fuel input, mass flow, and MHD combustor pressure. In order to achieve efficient part load operation the steam temperature to the turbine must be maintained. This is accompHshed by the use of flue gas recirculation in the heat recovery furnace at load conditions less than about 75% of fiiU load. [Pg.435]

Selection of the high pressure steam conditions is an economic optimisation based on energy savings and equipment costs. Heat recovery iato the high pressure system is usually available from the process ia the secondary reformer and ammonia converter effluents, and the flue gas ia the reformer convection section. Recovery is ia the form of latent, superheat, or high pressure boiler feedwater sensible heat. Low level heat recovery is limited by the operating conditions of the deaerator. [Pg.353]

A more obvious energy loss is the heat to the stack flue gases. The sensible heat losses can be minimized by reduced total air flow, ie, low excess air operation. Flue gas losses are also minimized by lowering the discharge temperature via increased heat recovery in economizers, air preheaters, etc. When fuels containing sulfur are burned, the final exit flue gas temperature is usually not permitted to go below about 100°C because of severe problems relating to sulfuric acid corrosion. Special economizers having Teflon-coated tubes permit lower temperatures but are not commonly used. [Pg.229]

A PFBC boiler is visually similar to an AFBC boiler. The combustor is made of water-wall tubing, which contains the high-temperature environment, but the whole assembly is placed within a pressure vessel. Unlike an AFBC unit, there is no convection pass, as the flue-gas temperature must be maintained at boiler temperature to maximize energy recovery by the expansion turbine. There is an economizer after the turbine for final heat recoveiy. A simplified schematic is presented in Fig. 27-49. An 80-MWe demonstration plant, operating at 1.2 MPa (180 psia), began operation in 1989 with a power producdion intensity of 3 MWe/m (1 MWe/3.5 fU). By 1996, five units of this size had been construcded, and a 320-MWe unit is planned to commence operation in 1998. [Pg.2400]

When cooling combustion flue gas for heat recovery and efficiency gain, the temperature must not be allowed to drop below the sulfur trioxide dew point. Below the SO3 dew point, very corrosive sulfuric acid forms. The graph in Figure 1 allows determination of the acid dew point us shown in Example 1. [Pg.336]

For PM control from combustion sources, the tlue gas enters a coagulation area (e.g., ductwork, a chamber, or a cyclone) to reduce the number of ultrafine particles, and then a gas conditioner to cool the gas to a suitable temperature and saturation state. This is generally accomplished by means of a waste heat recovery heat exchanger to reduce the temperature of the flue gas or by spraying water directly into the hot flue gas stream. [Pg.445]

The flue gas exits the cyclones to a plenum chamber in the top of the regenerator. The hot flue gas holds an appreciable amount of energy. Various heat recovery schemes are used to recover this energy. In some units, the flue gas is sent to a CO boiler where both the sensible and combustible heat are used to generate high-pressure steam. In other units, the flue gas is exchanged with boiler feed water to produce steam via the use of a shell/tube or box heat exchanger. [Pg.17]


See other pages where Flue-gas heat recovery is mentioned: [Pg.152]    [Pg.17]    [Pg.334]    [Pg.500]    [Pg.50]    [Pg.113]    [Pg.201]    [Pg.203]    [Pg.3]    [Pg.5]    [Pg.179]    [Pg.228]    [Pg.152]    [Pg.17]    [Pg.334]    [Pg.500]    [Pg.50]    [Pg.113]    [Pg.201]    [Pg.203]    [Pg.3]    [Pg.5]    [Pg.179]    [Pg.228]    [Pg.23]    [Pg.678]    [Pg.679]    [Pg.691]    [Pg.238]    [Pg.438]    [Pg.450]    [Pg.3]    [Pg.13]    [Pg.130]    [Pg.90]    [Pg.268]    [Pg.422]    [Pg.217]    [Pg.225]    [Pg.1085]    [Pg.2382]    [Pg.2388]    [Pg.152]    [Pg.1257]    [Pg.1178]    [Pg.1210]    [Pg.410]   
See also in sourсe #XX -- [ Pg.17 ]




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