Steam flash recovery

Figure 3.2 Flash steam/heat recovery (FSHR) system.

A steam-infusion cooking process, known as hydrothermal cooking (HTC), was developed to produce soymilk continuously from ground full-fat soy flour (Johnson et al., 1981). It was claimed that soymilk processed by the HTC process had less beany flavors because of the much shorter time for lipoxygenase to be active and because steam flashing stripped volatiles. The process also increased recovery of dry matter and protein in the soymilk. 

Reduce steam condensate draining by installing steam traps reduce flashing of steam condensate in condensate headers by condensate cooling separating flash steam install additional steam condensate recovery systems... 

Recrystallization. Solid impure salt, as mined or crudely crystallized by other means, can be upgraded by recrystallization [26]. The process involves addition of solid salt to a circulating brine, which is heated by the injection of steam. Flashing the hot brine under vacuum, after removal of insoluble material by settling and filtration, allows the salt to crystallize from solution. Recovery of the salt releases the brine carrier for recycle to the process. 

The steam flash drum is a device for steam recovery. Flash steam occurs at the drum where steam condensate or boiler blowdown experiences a drop in pressure causing some of the condensate or boiler blowdown to evaporate forming steam and thus produces steam at the lower pressure (Figure 15.11). For low-pressure condensate, flash steam is negligible and thus it is not worth to recover. However, for medium-and high-pressure condensate, it is important to recover flash steam. 

Butyl slurry at 25—35 wt % mbber continuously overflows from the reactor through a transferline to an agitated flash dmm operating at 140—160 kPa (1.4—1.6 atm) and 55—70°C. Steam and hot water are mixed with the slurry in a nozzle as it enters the dmm to vaporize methyl chloride and unreacted monomers that pass overhead to a recovery system. The vapor stream is compressed, dried over alumina, and fractionated to yield a recycle stream of methyl chloride and isobutylene. Pure methyl chloride is recovered for the coinitiator (AlCl ) preparation. In the flash dmm, the polymer agglomerates as a coarse cmmb in water. Metal stearate, eg, aluminum, calcium, or zinc stearate, is added to control the cmmb size. Other additives, such as antioxidants, can also be introduced at this point. The polymer cmmb at 8—12 wt % in water flows from the flash dmm to a stripping vessel operated under high vacuum to... 

The mbber is then separated from its solvent by steam stripping. The viscous cement is pumped into a violently agitated vessel partly full of boiling water. The hexane flashes off and, together with water vapor, passes overhead to a condenser and to a decanter for recovery and reuse after drying. Residual unpolymerized ethylene and propylene appear at the hexane condenser as noncondensibles, and are recovered for reuse after drying. The polymer, freed from its carrier solvent, falls into the water in the form of cmmb. 

C 0.35 Recovery of low level waste heat f space heating, district heating syste Absorption cooling. Recovery of steam condensate and flash steam. Heat pump for evaporation, drying, etc. 3r m. 

The steam/process air heater with multiple coils typifies the kind of application on which recovery of flash steam... 

Flash steam. This will result from the blowdown heat recovery referred to in Section 7.13. Flash steam is introduced into the tank through a dip pipe terminating in a distribution manifold near the bottom of the tank. 

Where high temperatures are required (e.g. for process work) and lower temperatures for space heating, it is desirable to use flash steam recovery from the high-temperature condensate to feed into the low-temperature system, augmented as required by reduced pressure live steam. 

Typically, a FW tank temperature of 180 to 190 °F (82-88 °C) is preferred and can be achieved by the direct application of live steam (from a LP steam supply or from a flash steam recovery system) through a perforated sparge pipe or by indirect heating via steam, gases of combustion, or electrical-resistance heaters. Each temperature rise of 10 °F (5.6 °C) results in at least a 0.3 to 0.4% fuel saving. Tanks should, of course, be properly designed and lagged. 

Further savings can be made by the use of a suitable blowdown (BD) water flash steam and heat recovery (FSHR) system. Such systems are standard equipment on large power boilers but are less common on smaller plant. However, the FS component (and often the HR component as well) can usually be justified for smaller systems because the capital cost payback of such equipment generally is less than 12 months and such systems continue to save fuel and high-quality water year after year. 

Feedwater heaters also may be considered as BOP equipment (with the exception of economizers), especially in utility power plants. Blowdown receivers and flash steam and heat recovery (FSHR) also may be considered BOP equipment. 

Blowdown Water and Flash Steam and Heat Recovery Systems... 

Flash steam and heat recovery systems are almost never fitted into hydronic heating and LP steam boilers because of the very limited discharge of boiler water as blowdown. A schematic drawing of an FSHR system is shown in Figure 3.2. 

Flash steam and heat recovery systems provide a useful and simple means of recovering both heat energy and steam condensate that would otherwise be lost by BD. The capital cost for an average sized industrial boiler house is relatively low, and capital payback periods are usually within 12 to 24 months. 

Flash steam and heat recovery systems perform more efficiently if a continuous source of blowdown is provided. Depending on boiler pressure, the potential BW blowdown recovery is up to 25% of the blowdown volume recovered as flash steam and up to 75% of the heat content recovered. The flash steam can be passed to a LP steam line or sent back to a deaerator or feed tank, where it provides both FW heating and a replacement for MU water. 

Table 3.1 Flash steam recovery from a FSHR system...

The heat exchanger component of a boiler blowdown, flash steam, and heat recovery system (FSHR). 

A reservoir to receive recovered condensate, located at the bottom of a surface condenser. Also any other tank or basin that receives water from flash steam recovery. 

Department of Energy (UK). Fuel Efficiency Booklet 6 Flash Steam and Vapour Recovery. Her Majesty s Stationary Office, UK, 1997. 

Gestra (UK) and Highveld Instrumentation (South Africa). Boiler Blowdown and Flash Steam Recovery Systems. Technical and promotional literature. Gestra Aktiengesellschaft, Germany, 1990. 

FSHR, see Flash steam and heat recovery systems FT boiler designs, development of 30... 

Flash steam recovery might also feature. Condensate or blowdown is fed to the flash drum, as illustrated in Figure 23.26. A material balance gives ... 

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