Condensate losses

Figure 27-43 shows the amount of energy available for power by using a fire-tube boiler, an industrial bofler, and subcridcal- and supercritical-pressure boilers. Condensing losses decrease substantially, and regeneration of air and feedwater becomes increasingly important in the most advanced central-station boilers. 

The selection is dictated by economics governing the initial plant cost versus higher turbine output. Usually, the turbine exhaust steam is designed to be slightly superheated, which is desirable, as it allows for heat loss from the steam with minimum condensate losses. At low loads from the turbine, the degree of superheat can rise sharply, well in excess of the normal design conditions, and for this purpose, desuperheaters are often employed to trim the steam temperature at exhaust. 

Improving the energy efficiency to reduce steam demand and hence reduce the wastewater generated by the steam system through boiler blowdown, boiler feedwater treatment and condensate loss (see Chapter 23). 

While the films formed by using common templates such as Brij56 show a strong contraction of the structure upon calcination because of the thermally driven network condensation, loss of the organic template, and/or phase transitions, the PDMS-6-PEO-templated films revealed no contraction of the structure with the c(-spacing for the calcined films remaining unchanged. 

A high reaction temperature reducing both resinification and condensation losses, thereby increasing the yield. 

The loss by furfural reacting with intermediates of the xylose-to-furfural conversion (condensation loss). 

For 200 C as example, the procedure is shown in Figure 132. Curve A, representing the yield of the hypothetical process with resinification as the only loss, is obtained from equation (7) of the preceding chapter, and curve B is an experimental yield curve given in the literature [126] for 200 °C and for an initial xylose concentration of 0.666 mole/liter (100 g/liter). Experimental yield curves for other temperatures and other initial xylose concentrations are amply available in the same reference. The hatched area between the two curves A and B represents the condensation loss. To round the overall picture, the theoretical yield for the temperature considered is shown by the dashed curve C. 

In subchapter 6.2, it was suggested that the condensation loss is due to one or two molecules of furfural reacting with the first intermediate of the xylose-to-furfural conversion, so that the overall rate of the condensation reactions should be... 

Thus, although the new rate constants ka and kb can not be determined, it is readily seen that the condensation loss increases with an increasing initial xylose concentration, so that the actual yield decreases when the initial xylose concentration increases. This is bom out by the experimental yield curves shown in Figure 133, taken from the literature [126]. Hence, a fiir-fural reactor run at a high moisture content gives a better yield than a furfural reactor run at a... 

Figure 132. Graphical Representation of the Condensation Loss at 200 C. Curve A Yield of a process with resinification only.

The condensation loss is represented by the area between the curves A and B. 

To obtain a comprehensive picture of the yield situation, diagrams of the type shown in Figure 132 must be drawn for various temperatures. In this fashion, it is found that the condensation loss decreases markedly with increasing temperatures. This is strong support for the high temperatures advocated in the SUPRATHERM and STAKE processes. 

E3 CONDENSING LOSSES BOILER LOSSES r-i REGENERATIVE FEED HEATING 03 AIR PREHEATER... 

Bis(triiluoromethyl)-l,2,4,5-tetrazine (157) and anisole (156) gave 6-meth-oxy-l,4-bis(trifluoromethyl)phthalazine (158) by a Diels-Alder condensation, loss of N2, and spontaneous oxidation (neat reactants. Teflon-lined autoclave, 140°C, 12h 68% after separation from minor products thioani-sole likewise afforded 6-methylthio-l,4-bis(trifluoromethyl)phthalazine (56%). i "i... 

Biofouling is of great influence on costs and expenses in indnstry A 1999 report by Naval research laboratory indicates that use of antifouling paints conld save up to 10% of the US Navy s annual fuel bill. The same report quotes from another report prepared by the Electric Power Research Institute (EPRI) that more than 75% of condenser loss in fossil-fueled power plants with a capacity of more than 600 MW is due to biological factors, of which 30% were due to macrofouling. Research indicates that barnacles are indeed capable of inducing localized corrosion. 

Once the sample has been pyrolyzed, volatile fragments are swept from the heated pyrolysis/injection port by carrier gas into the GC or GC/MS system. In Py-MS, it is likewise desired to transfer pyrolysis products to the ionization source of the MS without appreciable degradation, condensation loss, or recombination. Designs of Curie-point Py-MS systems have incorporated glass reaction tubes, expansion chambers, heated walls, and positioning of the pyrolysis reactor directly in front of the ion source."... 

Cooling water supply faQine to SO3 condenser Loss of production of SO3 Possibility of high-pressure in SO3 condensation system Release of SO3 vapors from vent scrubber Audio-visual alarm to be activated... 

FE for Condensate Condensate temperature is typically around 200 F. The condensate FEcond can be determined by the difference of condensate temperature and raw water temperature (ambient). FEcond is usually in the range of 100-150 Btu/lb of condensate. Although FEcond is small relative to steam, accumulated loss could be significant for a large amount of condensate loss. Also, condensate loss is costly due to the extra chemicals required to treat makeup water. 

Steam is distributed from the sources of generation to the locations of end users via steam headers and take-off pipes. There could be significant steam and condensate losses due to poor insulation of steam pipes, steam leaks, steam trap losses, condensate losses, venting, and letdown. The total energy loss associated with steam and condensate losses could be in the range of 10-30% of fuel fired in the boilers depending on the steam system design and operation. The losses need to be reflected in the steam balance, which will be discussed in chapter 16. 

Condensate return is only 43% compared with the best practice of 70-80%. Condensate loss is a waste of money (water purchase, pumping, and chemical... 

---