Steam power plant engineering by Gebhardt George Frederick

Author:Gebhardt, George Frederick. [from old catalog]
Language: eng
Format: epub, pdf
Tags: Steam power plants
Publisher: New York, John Wiley & sons, inc.; [etc., etc.]
Published: 1917-03-25T05:00:00+00:00

STEAM POWER PLANT ENGINEERING

Corresponding to 1.56 sq. ft. per kw. of turbine rating. Surface condensers for large turbines have generally from 1.6 to 1.7 sq. ft. of condensing surface per kw. See Table 93.

Orrok's rule gives for this example

S =

12,368,000

[(87.1 - 70)« = (87.1 - 79.1)«]

40.3 X 80.6 = 11,500 sq.ft.

Taking the heat content of the steam as that of saturated steam at condenser pressure Orrok's rule gives S = 12,650 sq. ft. In fact, Orrok's rule is based on the assumption that the steam entering the condenser is saturated, an assumption which simplifies calculation and which is justifiable in view of the uncertainty of the true values of many of the factors entering into the problem.

TABLE 92.

TEST OF 50,000 SQ. FT. SURFACE CONDENSER, 74TH ST. STATION INTERBOROUGH RAPID TRANSIT CO.

(H. G. Stott and W. S. Finlay, Jr.)

Pressure at throttle, lb. abs 220

Temperature at throttle, deg. fahr 487

Superheat 97

Load, average kw 31,233

Exhaust vacuum, in 28.61

Exhaust pressure, in. abs 1. 39

Corresponding temp. deg. fahr 89.4

Mean temp. diff. (log.) 12.9

Condensate, lb. per hr *. . 357,060

B.t.u. per sq. ft. per hr. per deg. mean temperature difference. . . 490

Air leakage, cu. ft. per min 16.88

Temp, of hot well, deg. fahr 86

Temp, intake water, deg. fahr 70.8

Temp, discharge water, deg. fahr 80.9

Temp, rise, deg. fahr 10.1

Circulating water, gal. per min 64,700

Ratio circulating water to condensate 91

TABLE 93. MODERN SURFACE CONDENSER PROPORTIONS.

The curves in Fig. 318 are based upon equation (209) with U = 300 and afford a simple means for determining the extent of cooling surface

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