Case study about how AKO installed his AKOTRACE® Electrical Heat Tracing Solution at Gemasolar, optimizing the plant's general performance.

1. Case Study
GEMASOLAR
SPECIAL AKOTRACE® ELECTRICAL HEAT-TRACING SOLUTION FOR
GEMASOLAR
PROJECT SHEET
TEMPORARY JOINT VENTURE: SENER- COBRA
PROMOTER: TORRESOL ENERGY
CSP TECHNOLOGY: Tower CSP with direct molten salts.
LOCATION: Fuentes de Andalucía (+37° 32’ 3.24”, -5° 18’ 47.59”)
HEAT TRACING SYSTEM TECHNICAL DATA:
- Electrical heat-tracing system turnkey solution
- 10 engineers and 40 fitters
- 12 km of mineral insulation heating cable
- 400 active circuits
- Over 1400 control i/o
- 1 MW electrical power in 4 power distribution cabinets
- 7 months of execution
BACKGROUND
Torresol Energy is the owner of the first commercial plant in the world to apply
central tower CSP technology and thermal storage in molten salts. Some of the
features that make this plant singular and unique in the world are:
- Nominal rated electrical power: 19.9 MW
- Estimated net electrical power: 110 GWh/ year
- Solar field: with 2,650 heliostats in 185 hectares
- Thermal storage system: the hot salt storage tank allows an autonomy
of power generation of up to 15 hours without solar supply.
SENER has carried out the project engineering and it has been built by a Temporary Joint Venture made up of SENER
and COBRA.
This plant is a demonstration that two of the different factors that central tower CSP technologies have compared to other
CSP technologies and other renewable energies: the capacity for adjusting production to consumption demand.
The longer operating time of the plant in the absence of solar radiation and improved efficiency in the use of heat from the
sun make Gemasolar’s production much higher than what other technologies can reach in a facility with the same power
and it can modulate power generation and adjust it to peak hours outside solar radiation times and produce electrical
energy 24 hours a day for most of the year.
The technological difference supplied by this plant is basically the incorporation of a new thermal storage system
in molten salts which allows producing electricity in the absence of solar radiation.
Heat collected by the salts (capable of reaching temperatures over 500 ºC) is used to generate steam and, with this, produce
electric energy. Excess heat accumulated during the hours of sunshine is stored in the hot salt tank.
Given the technology used, Tower CSP with molten salts, one of the most critical systems in the project is the electrical
heat-tracing system to maintain and heat the molten salt circulation circuit.
To answer this technical challenge, SENER and COBRA contracted AKO as a partner to provide its electrical heat-tracing
solution, AKOTRACE®.
www.ako.com

2. Case Study
GEMASOLAR
PROJECT CHALLENGES
Technical requirements, although largely already resolved by AKO in many projects
executed in solar thermal plants with parabolic trough and salt accumulation techno-
logy, added important differences such as:
- Process working and maximum material temperatures
- Heating times and remounting of process areas, such as the receiver
and the drainage circuits
- Tracing of critical points such as valve bonnets, pump heads and
upright pipes
- Availability and robustness of the control system
- Installation of circuits inside the tower and distribution of the power
cabinets, due to space limitations and atmospheric conditions
AKO SOLUTION
The scope of the AKO solution has been the execution of the turnkey electrical heat-tracing system, AKOTRACE®. AKO’s
strategic commitment to this project has been personally promoted by José Luis Bescós, General Manager of AKO: “It
has been a big technical and project and resource management challenge for AKO. We have learned a lot. We are proud of
the end result and of having taken part in our customer’s emblematic project”.
Part of the solutions during the basic engineering process were based on R&D activities, led by the Tracing Applications
Manager, Joaquim Pagá: “We had to resolve not only theoretically but also empirically certain aspects we consider key for
the success of the project testing in our AKOTRACE® Laboratory. Therefore, in addition to AKO’s internal knowledge, we
have turned to some partners from the science area who have helped us in both the mathematical modelling of thermody-
namic processes and in the properties of certain materials”.
This has allowed us to guarantee the performance of certain tracing circuits of critical points in the laboratory, both in tem-
perature and in maximum times of reaching the set point, minimising at all times the thermal stress the mineral insulation
cable is subjected to by improving our control algorithm. As, Joaquim Pagá, explaine:“in R&D we have been fully involved
in the start up of the system to check or adjust the foreseen performance”
In the AKOTRACE® solution it is worth mentioning that we have chosen different key technical characteristics for this
project:
- Mineral insulation cable with laser welding
- K thermocouple type probes with double redundancy
- Special construction and refrigeration for the panels inside the tower
- Additional safety temperature control protections
- Specific design of heaters for singular points
- Connection redundancy and system manageability from DCS
All in an execution time of 7 months. Both the installation and start-up process have also been a big challenge for the
project industrialisation team, led by Rafael Delgado, Director of AKO’s Project Business Unit: “The Temporary Joint
Venture’s demands during the installation and start-up have been very high. Not in vain, not only the heat-tracing system
is critical, but it is also one of the last systems to be installed and that is totally necessary for the plant’s product start up
timings. Also, as foreseeable in this type of innovative projects, improvements have been introduced during the execution,
both by engineering and by AKO, that we have included in the planning”.
www.ako.com

3. Case Study
GEMASOLAR
RESULTS
The plant was officially opened on 4 October, although it has been operating since
May 2011. The results obtained from the introduction of our AKOTRACE®.solution in
such an emblematic project are:
- Introduction of improvements in basic engineering and R&D in the form of
technical and technological solutions.
- Assurance of the criticality of the system with an efficient investment
- Response in time to new technological challenges that have arisen
- Execution times adjusted to works building planning
- Training of the plant’s staff on the correct operation of the heat-tracing
system
- Transparent integration with the plant’s management system to make plant
maintainability easier
The execution of this projects rounds off the level of experience and knowledge
required due to its criticality in heat-tracing systems of concentration solar ther-
mal plants with salt accumulation
ABOUT AKO
Over 30 years of innovation and with 130 people team of in-house professionals AKO Electromecànica, S.A.L. is a Spanish
company leader in the Regulation and Control of Temperature with Electrical Heat Tracing Solutions for Thermo-Solar Power
Plants, that offers comprehensive support from project design and manufacturing, to technical assistance, to the System
commissioning (turnkey projects) and after-sales service. Electrical Heat Tracing System AKOTRACE® based the heating
cable technology, providing advantages and savings on energy and the overall cost of the installation, with a reliable and
secure management, ensuring the health, safety and respect for the environment.
www.ako.com