Page 12 - Design of Solar Thermal Power Plants

1.1 GENERAL PRINCIPLES OF SOLAR THERMAL POWER PLANT DESIGN 5

3. For solar collectors within the same power plant, the same type of
collector with the same output parameters should be used;
generator units within the same power plant should also use the
same parameters. For a parabolic-trough-and-tower mixed-CSP
plant, the parabolic trough system should be used as the preheater
with the tower used for the superheated part.
4. When designing the concentration field, the influences of sun beam
shading and blocking between the reflectors on concentration
efficiency shall be considered; attention should also be paid to the
land use rate and future expansion needs of the concentration field
and thermal storage system. Normally the land coverage of a
parabolic trough concentration field is about 2.5 times that of the
total aperture area of the concentrators, whereas the land coverage
of a solar tower concentration field is 4e6 times that of the total
aperture area of the heliostats and also related to the height of tower.
In some countries, land quotas are quite complex.

1.1.3 Heat Transfer Fluid of the Receiver
Water/steam, synthetic oil, air, or molten salt can be selected as the heat
transfer fluid. The working medium of a steam turbine is water/steam.
For a CSP plant that uses steam as the corresponding working medium,
water pretreatment equipment must use desalinated water; otherwise,
permanent damage may be caused to the reverse osmosis water system.

1.1.4 Schedule Capacity of the Power Plant and Number of
Installed Units

New power plants can be designed and constructed all at once or in
sections according to incremental load speed based on scheduled capac-
ity. Due to the comparatively large investment, the concentration field
corresponding to a power plant can be designed all at once but con-
structed in sections. The major loop for synthetic oil, the design and
construction of the parabolic trough collector field, and the height of the
receiver tower in the tower power plant shall be configured to match the
intended ultimate capacity of the power plant. A large-scale collector field
can be divided into different thermal collection modules, the thermal fluid
output of which will flow into the thermal storage unit. In the thermal
collection system that directly produces steam, the steam will be dis-
charged to the main pipe of the power plant.
The number of condensing power turbines shall not exceed four in one
plant. For a power tower plant with an installed capacity of less than
100 MW, no more than one receiver corresponding to the concentration
field shall be installed [1]. For a large-capacity tower power plant, the