Available online at www.sciencedirect.com
ScienceDirect
Energy Procedia 69 (2015) 1471 – 1478
International Conference on Concentrating Solar Power and Chemical Energy Systems,
SolarPACES 2014
The Badaling 1MW Parabolic Trough Solar Thermal Power pilot
plant
Ershu Xua, Dongming Zhaoa, Hui Xua, Shidong Lic, Zhiqiang Zhangb,ZhiyongWangb,
Zhifeng Wang a
a
Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical Engineering
Chinese Academy of Sciences, Haidian District, Beijing 100190,China
b
Inner Mongolia Power Survey β Design Institute, Xilin South Road 209, Hohhot 010020,China
c
Guangdong University of Petrochemical technology, Guandu Road 2, Maoming, Guangdong525000, China.
Abstract
In order to master the design, integration and operation technology of parabolic trough solar thermal power (PTSTP) plant and
lay a solid foundation for the future development of large-scale PTSTP station, China sets up a research project “National High
Technology Research and Development of China 863 Program (2012AA050603)”during the National “12th Five-Year Plan”,
which aims to establish a 1MW Parabolic Trough Solar Thermal Power pilot plant in Badaling Yanqing. In this paper, it
introduces the collector field arrangement, the composition and the function of 1MW pilot plant in detail.
© 2015
by Elsevier
Ltd. This
is an open
access article under the CC BY-NC-ND license
©
2015Published
The Authors.
Published
by Elsevier
Ltd.
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer review by the scientific conference committee of SolarPACES 2014 under responsibility of PSE AG.
Peer review by the scientific conference committee of SolarPACES 2014 under responsibility of PSE AG
Keywords: Solar thermal power generation, Parabolic trough, Design, Integration
1. Introduction
In the 21st century, the energy and environment problem has been increasingly serious, and become a hot issue in
the field of current international politics and economy. In order to ensure the sustainable supply of energy and
reduce emissions of pollutant, the renewable energy gets more and more attention in the world. During the National
12th Five-Year Plan, it sets up a research project of "The test platform research and demonstration system of
parabolic trough concentrating and power generation system(2012AA050603)"in China 863 Program of "The
research and demonstration of parabolic trough solar thermal power generation technology", which aims to develop
the mass production technology of the parabolic trough solar concentrator and key equipment, establish the MW
1876-6102 © 2015 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer review by the scientific conference committee of SolarPACES 2014 under responsibility of PSE AG
doi:10.1016/j.egypro.2015.03.096
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Ershu Xu et al. / Energy Procedia 69 (2015) 1471 – 1478
parabolic trough solar thermal power generation experiment platform, grasp the design, integration and operation
technology of PTSTP station, and lay a solid foundation for the future large-scale construction of PTSTP plants.
2. The Badaling 1MW Parabolic Trough Solar Thermal Power pilot plant
2.1 The condenser system
The collector system is the subsystem which can represent the characteristic of solar thermal power system. The
total area of collectors in Badaling 1MW parabolic trough solar thermal power plant is 10000m2. It is composed of
three loops, and each loop is 600m long. Two loops lay from east to west, and one loop lay from south to north.
There are two reasons to form this distribution. First, there is limitation in land. Second, as the different arrangement
of loops, we can do some tests to compare the different performance. They use one dimensional tracking mode. The
parabolic trough collector uses a variety of forms, including torque tube collector, torque frame collector and torque
tube with a counterweight collector. The collector is shown in Fig 1[1].The arrangement of three loops is shown in
Fig 2[1]. The main properties are shown in table 1.
Fig.1.The diagram of the collector
Table 1. The performance parameters of the collector
number
parameter
value
number
parameter
value
1
focal distance
1.71m
6
protection wind
speed
13.8m/s
2
heat-absorbing tube
diameter 70mmˈ
length 4060mm
7
operating wind
speed
”PV
3
opening width
5.760m
8
operating
temperature
-40ć ̚ +50ć
4
reflective glass error
˘3mrad
9
hail resistant
The reflective glass will not damage
under the impact of the hail of 20 mm
diameter falling with 20 m/s speed
5
heat-absorbing tube position
error
˘5mm
10
service life
20 years
Ershu Xu et al. / Energy Procedia 69 (2015) 1471 – 1478
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Fig. 2.The collector field of Badaling 1MW parabolic trough solar thermal power pilot plant
2.2 The Badaling 1MW Parabolic Trough Solar Thermal plant
It uses the parabolic trough collector to focus sunlight on the absorber which installs on the focal line in parabolic
trough solar thermal power generation, in order to heat the transfer fluid in the vacuum absorber tube, and then the
heat transfer fluid flows through steam generator to heat water and to produce high temperature and high pressure
steam, and the steam drives turbine generator to generate electricity. Parabolic trough solar thermal power
generation system mainly includes: parabolic trough collector (PTC) system, heat transfer fluid and its circulation
system, steam generator system and power generator system. In order to solve the intermittent problem and
instability problem of solar energy, it is necessary to add the heat storage system to realize continuous power
generation of plant and improve the stability of output electricity[2]. Badaling 1MW parabolic trough solar thermal
power pilot plant is shown in Fig.3. Steam generator system[3], which is heated by heat transfer fluid, consists of
three parts: feed water preheater, steam generator and steam superheater. It uses the natural circulation drum and
horizontal layout, and produces 6.7 tons superheated steam (2.3 MPa, 370 ć) per hour.
The thermal storage system is the combination of high and low temperature subsystems. The high temperature
subsystem is made by two surface heat exchangers, two pumps, and two oil storage tanks. Heat transfer oil is used
as working fluid to store and transfer heat energy, in which the superheated steam(2.5MPa, 380ć) is generated by
using the steam generation flow to the heat exchanger. The majority of the thermal energy (380ć ~ 261.4 ć) is
stored in hot oil tanks. The low temperature subsystem is the steam accumulator (volume of 100m3), which stores
the saturated steam from the exchanger. The saturated water is used as the working mass to store thermal energy.
When solar energy becomes deficient, saturated steam (2.35MPa, 220.7 ć) produced by the steam accumulator is
sent to the exchanger and overheated to 320 ć by the hot oil (350ć) [4-5]DŽSteam turbine uses condensing turbine,
and its power rating is 1.5 MW. The design parameters of Badaling 1MW parabolic trough solar thermal power pilot
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Ershu Xu et al. / Energy Procedia 69 (2015) 1471 – 1478
plant are shown in table 2. It is just a 1MW plant, and the turbine efficiency is low, so it is about 13% from solar to
electric efficiency under solar operation and storage operation. The storage capacity is 1 hour.
Oil pump
heat transfer
fluid tank
Oil pump
steam generating system
Steam turbine
collector
field
thermal storage system
condensor
deaerator
Water pump
Oil pump
Condensate pump
Fig. 3. The diagram of Badaling 1MW parabolic trough solar thermal power pilot plant
Table 2. The design parameter of Badaling 1MW parabolic trough solar thermal power pilot plant[6]
1
The condenser pressure
0.0067
MPa
14
The steam pressure at the outlet of
superheater
3.2
MPa
2
The condensing water temperature
38
°C
15
The temperature at the outlet of
superheater
380
°C
3
Deaerator pressure
0.12
MPa
16
The steam flow at the outlet of
superheater
6500
Kg/h
4
Feed water pressure
4.1
MPa
17
The steam pressure at the inlet of turbine
2.35
MPa
5
Feed water temperature
104
°C
18
The temperature at the inlet of turbine
375
°C
6
The evaporator pressure
3.2
MPa
19
The oil pressure of the conduction oil
filling main
3.0
MPa
7
The evaporator temperature
237.5
°C
20
The oil pressure of the conduction oil
return main
1.5
MPa
8
The pressure after heat exchanger
2.52
MPa
21
The oil temperature at the inlet of
superheater
393
°C
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Ershu Xu et al. / Energy Procedia 69 (2015) 1471 – 1478
9
The temperature after heat exchanger
265
°C
22
The oil pressure at the inlet of
superheater
1.0
MPa
10
The accumulator pressure
2.5
MPa
23
The oil flow at the inlet of superheater
99.4
m3/h
11
The accumulator
240
°C
24
The oil temperature at the inlet of
evaporator
380
°C
temperature
12
The deaerator pressure
0.316
MPa
25
The oil temperature at the inlet of
preheater
317.9
°C
13
The deaerator temperature
230
°C
26
The oil temperature at the outlet of
preheater
296
°C
2.3 The design and calculation method of Badaling 1MW parabolic trough solar thermal plant
In this plant, we use the dynamic matching capacity method to design it. This method is based on the rated
condition, and it checks the potentially dangerous conditions on the condenser system, the steam generator system,
the energy storage system and the electric generator. The flowchart is shown in Fig.4[1].
a) The calculation of the gained effective energy in the PTC field
According to the law of conservation of energy, they are expressed as follows.
Qgained
dH
dt
Qabs Qenvloss Q pipeloss
mc p
dT
dt
Qgained
(1)
Where Qgained is the gained effective energy in the condenser system; Qabs is the solar radiation absorbed by the
receiver tubes in the PTC field; Qenvloss is the heat loss of the vacuum absorber tube; Qpipeloss is the heat loss of pipelines
in the plant; H is the enthalpy of the heat transfer oil; m is the mass flow of the heat transfer oil; c p is the specific
heat capacity of the heat transfer oil; T is the temperature of the heat transfer oil; t is the time.
b) The calculation of the absorbed energy of absorbers in the PTC field
Qabs
( I b , N ˜ cos T ˜ IAM ˜ W ˜ L) ˜ f rowshadow ˜ f endloss ˜ f hce ˜ f field
(2)
Where Qabs is the solar radiation absorbed by the receiver tubes in the PTC field; I b,h is the direct normal
insolation; T is the angle of solar incidence; IAM is incidence angle modifier; W is the width of the collector
aperture; L is the length of heat collection elements; f rowshadow is the performance factor that accounts for mutual
shading of parallel collector rows during early morning and late evening; f endloss is performance factor that accounts
for losses from ends of HCEs; f hce is the HCE efficiency that accounts for losses due to HCE optics and
imperfections; f field is the field efficiency that accounts for losses due to mirror optics and imperfections.
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Ershu Xu et al. / Energy Procedia 69 (2015) 1471 – 1478
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Fig. 4. The flowchart of the dynamic matching capacity method
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Ershu Xu et al. / Energy Procedia 69 (2015) 1471 – 1478
2.4 The steam generator system
The calculated results of each part of the steam generator are shown in table 3, which are in the condition of mass
flow 18kg/s of the heat transfer oil. We have learned David.h’s article[6] in order to better understand the design process.
The evaporation section uses a kettle type heat exchanger, and the overheating and preheating parts use U type heat
exchanger. The outside diameter of heat exchanger pipes is 19.05mm with their thickness of pipes 1.65mm, and the
tube spacing is 23.81mm, and the arrangement of pipes is at a angle of 30 degrees.
Table 3. The calculated results of steam generator
Inlet temperature(ć)
Section
Outlet temperature(ć)
The heat
lode(kW)
The heat exchange
area˄m2˅
The shell
side
The pipe
side
The shell
side
The pipe
side
ˉ
the preheating section
105
310
191.4
297
552
2.9
the evaporation section
191.4
380
230.2
310
3052
22.7
the overheating section
230.
391
370
379.7
518
23.7
3. The purpose OF 1MW Parabolic Trough Solar Thermal Power pilot plant
Although, several research institutes and enterprises in China have done a lot of research in the key equipment of
solar thermal power generation, such as parabolic trough collector and vacuum absorber tube. But until now, there
isn’t a parabolic trough solar thermal power generation system in operation in China, which means we don’t grasp
the design, construction and operation technology of it. The establishment of 1MW parabolic trough solar thermal
power pilot plant will make advances in the following aspects:
According to the alpine climate conditions in Yanqing, it designs parabolic trough solar thermal power plants and
masters the integration technology of system.
It studies the start-up and start-down of parabolic system, and explores the system operation mode in the alpine
climate.
It researches the dynamic characteristics in charge and discharge process of energy storage system, and explores
the ability of thermal storage system to buffer the irradiation fluctuations from the system level.
It explores the heat loss characteristics of collector field, and makes the anti-freezing plans of heat transfer fluid
in parabolic system in the alpine climate.
It researches the hydrodynamic characteristics in parallel with the changing of solar irradiation in collector fields,
and explores the oil control strategy in parallel loops;
It is composed of three loops in 1MW parabolic trough solar thermal power collector system, including two loops
“East-West” and one loop “South–North”. It can use the comparative method to make the real-time test of the
concentrated and thermal characteristics for the south-north and east-west collector field in the same location, and
analysis the dynamic characteristics with different field arrangements.
In solar thermal experimental base of Yanqing, it has established 1MW tower solar thermal power generation
plant. With the establishment of 1MW parabolic trough system, we can make comparative study of tower and
parabolic system in the same place and meteorological conditions. It can research the adaptability to irradiation and
cloud change of tower and parabolic trough system, and analysis their respective advantages in alpine climates, and
then provide technical support for the solar thermal technology route in China.
4. Conclusion
Now, it has result in the shortage of resources and environmental problems in China because of the fossil energy
as the main conventional energy, which has greatly restricted the sustainable development of economic society.
Solar thermal power generation technology will be one of the key technologies to solve the problem of energy and
environment in China. It has been clearly written in “National Medium and Long-term Plan for Science and
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Ershu Xu et al. / Energy Procedia 69 (2015) 1471 – 1478
Technology Development (2006-2020)” by Ministry of Science and Technology in 2006 and “Renewable Energy
Medium and Long-term Development Plan” by National Development and Reform Commission in 2007. Its
establishment of Badaling 1MW parabolic trough solar thermal power experiment system will play an important
role in mastering the design, integration and operation of parabolic system, and lay a technology foundation for the
establishment of large-scale parabolic trough solar thermal power generation system in the alpine climate.
Acknowledgements
This work has been financed by China National Hi-Tech R&D (863 Plan).Project: The experiment platform and
demonstration system for solar thermal parabolic trough system (2012AA050603) and China National Science and
technology plan (973 Plan) project: the large-scale solar thermal power system integration and control strategy
(2010CB227104).
References
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Research and Development of China 863 Program (2012AA050603), August 15th, 2014.
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congress 2007: solar energy and human settlement
[4] Ershu Xu, Qiang Yu, Zhifeng Wang, Chenyao Yang. Modeling and Simulation of 1 MW DAHAN Solar Thermal Power Tower Plant.
Renewable Energy, Vol 36, Issue2, February 2011: 848-857
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