Page 234 - Design of Solar Thermal Power Plants

3.9 MAIN POINTS FOR POWER PLANT SITE PLAN 217

2. Concentration field layout. Concentration field has the largest land
coverage in an CSP plant. Normally, area of a heliostat
concentration field is five times the sum aperture area of heliostats.
Land coverage of a parabolic trough concentrator is about three
times the total area of aperture of receiver of a parabolic trough
concentrator.
In general cases, except for the efficiency of concentration field,
fluid transportation-related problems shall also be considered
during the layout of concentration field, especially the layout of
parabolic trough concentration field.
An example of concentration field layout in a 50 MW parabolic
trough power plant is shown below. In terms of parabolic trough
thermal collection, solar radiations are concentrated in the
primary loop and converted into thermal through the collector
consisting of a parabolic trough concentrator with the
concentration ratio of 75 times and a evacuated tube receiver; the
respective heat-transfer medium is synthetic oil with the working

temperature of 400 C. The secondary loop is for oil-water heat
exchange, which produces superheated steam in order to drive
the highly efficient steam turbine to work and generate power. A
solar collector field consists of 160 parallel “thermal collection
loops”; each “thermal collection loop” consists of four rows of
parabolic trough “collector units” with a length of 150 m
(Fig. 3.63) through series combination, which is shown in Fig. 3.64.
Length of thermal collection loop is determined by the solar
irradiation and meteorological conditions of the working site of
collectors. Normally the temperature increase of outlet/inlet

loops of synthetic oil is 105 C.

FIGURE 3.63 A parabolic trough collector unit with a length of 150 M [32].