INSTALLATION AND DEMONSTRATION OF THREE LARGE SOLAR THERMAL COLLECTORS FIELDS SUPPLYING INDUSTRIAL PROCESSES HEAT

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1 INSTALLATION AND DEMONSTRATION OF THREE LARGE SOLAR THERMAL COLLECTORS FIELDS SUPPLYING INDUSTRIAL PROCESSES HEAT Radko Brock 1, Roberto Fedrizzi 1, Dirk Pietruschka 2 Francesco Orioli 3, Robert Söll 4, Reiner Stauss 5 1 EURAC, Viale Druso 1, Bolzano, Italy, Tel: , radkoalexander.brock@eurac.edu 2 ZAFH-NET, Schellingstraße 24, Stuttgart, Germany, Tel: , dirk.pietruschka@hft-stuttgart.de 2 3 SOLTIGUA, via Roma 54, Gambettola FC, Italy, Tel: S.O.L.I.D, Puchstrasse 85, 8020 Graz, Austria, Tel: SOLERA GmbH, Fuhrmannstraße 9, Geislingen- Binsdorf, Germany, Tel.: / Abstract InSun is a European FP7 project coordinated by ZAFH-NET, with EURAC as a research partner and Soltigua, Solid, Solera, Berger Fleischwaren and Lácteas Cobreros as industrial partners. Within this project solar heat, generated on roof or ground mounted collectors, will be used to substitute conventional produced heat at different temperature levels. In three demonstration plants MW class solar fields with concentrating (Fresnel and parabolic trough) and flat plat collectors are installed to supply heat to different production processes at different climatic conditions. The design, construction, system integration, optimized control and a detailed system monitoring are covered within the project. The experience gained in heat implementation for different production processes and the monitoring data will be used for intensive market deployment activities to support the development of this young and innovative technology. 2. Introduction Previous work such as task 33 has shown that 28% of any consumed energy in EU25 is taken by the industry. 2/3 of this demand is for heating purposes. 60% of the heat demand is used at medium temperature level with a maximum of 250 C and 30% of it are used in low temperature range below 100 C. The temperature levels reached by solar thermal collectors are limited by about 100 C to 130 C for non-concentrating flat plat (FPC) or vacuum tube (VTC) collectors. For higher temperature levels up to 250 C concentrating collectors like Parabolic Trough Collectors (PTC) and Linear Fresnel collector (LFC) are required (1). Branches with highest suitability for solar thermal collector application are the food and drink industry as well as textile-, pulp- and paper industry (2) (3). However, the main problem faced by engineers when dealing with large solar thermal collectors fields delivering heat to industrial processes is that a reliable performance of the production process is still much more important for the manufacturers than energy savings reached. As a consequence only proven and standardized solutions are often considered with payback times not longer than 3 to 5 years. Apart from the cost issue, the reliability of large solar collector fields in industrial applications needs to be demonstrated. Therefore, the main objective of the InSun project is to demonstrate the reliability, efficiency and quality of three large scale industrial applications with process heat supply at different temperature levels in different climatic conditions. The solar collector technologies demonstrated range from improved flat-plate collectors for process heat up to 95 C, to tracked concentrating collectors (Linear Fresnel Collectors and Parabolic Trough Collectors) to supply medium temperatures

2 between 160 and 250 C (4). Within the InSun project the research focus will be on the analysis and optimization of the integration process of the solar systems, on the performance monitoring and on the control optimization of the solar thermal systems in combination with the industrial processes involved. Additionally, the development of marketing strategies within the InSun project aims to fasten the market deployment of this highly efficient and innovative technology. 3. The Project InSun 3.1 The consortium The project consortium consists of two research institutes, three collector producers and three demonstration partners that will host and integrate the solar collector fields in their production sites, respectively processing cooked ham, bricks and milk powder. Being the project mostly demonstration related, full scale systems each with a peak power higher than 1 MW will be installed and analyzed. 3.2 The research tasks: Research tasks focus on the analysis and optimization of the integration process of the solar systems into the industrial processes and on the combined performance of the solar systems together with the industrial processes involved. Detailed monitoring data of the three systems will be used to analyze and improve the combined system control and to demonstrate the performance of the three different collector types and their specific application at different seasonal conditions. 3.3 The process data collection: The first part of the project is the elaboration of process requirements and their impacts on the design and integration of the solar systems. Dynamic simulation tools are used for the solar system design optimization under consideration of the dynamics of the industrial processes involved.. A detailed process analysis will be carried out for each site to highlight general energy saving potentials between heat sinks and heat sources of the production process involved. 3.4 The monitoring and control of the systems To increase the reliability of large scale solar thermal systems covering a high fraction of the process heat (>20%) a permanent and automated monitoring system is needed. Therefore, internet based monitoring and analysis tools will be developed. These prototypes will be implemented in the demonstration systems and combined with innovative simulation based fault detection and predictive control tools. Table 1. Details about the demonstration plats Installation plant Austria Spain Italy Company Berger Schinken Laco Soltigua Production Ham Milk products Bricks Collector Area 1200 m² 2000 m² 2600 m² Collector type FPC PTC LFC Absorber Type Flat Tubular Tubular Motion Stationary Single axis Single axis Max. temperature 90 C C 250 C Solar Thermal Power 600 kw 1 MW 1.2 MW

3 4. The Solar fields on site Within the InSun project three kinds of collector technologies will be installed for different industrial processes and climatic conditions in Europe. Table 1 gives an overview on the three demonstration sites, the industrial processes involved and the planned collector systems. 4.1 The collectors technologies FPC (Flat Plate collectors) Flat plate collectors are the most spread collectors, because the production is quite simple and cheap. In General flat plate collectors consist out of an absorber, where the solar radiation is absorbed. The heat generated is taken up by a heat transfer medium, which is pumped through pipes attached to the backside of the absorber. The heat transfer medium (water, water glycol, and thermo oil or water steam) transfers the heat either directly to the production process or to a hot water storage. The glass as transparent cover is used to reduce the convection losses from the absorber plate by a horizontal air layer between the glass and the absorber plate. The glass layer also reduces radiation losses as the glass is transparent to short wave radiation and (emitted by the sun) and nearly opaque to long wave thermal radiation (emitted by the absorber). The backside and the sides of the collector is usually insulated to reduce heat losses to the ambient. FPC are commonly mounted in a permanently fixed position (4). Figure 1. Flat Plate Collector (FPC) (5) PTC (Parabolic through collectors) Temperatures far higher compared to FPC can be reached with concentrating collectors. A mirror reflects and concentrates the solar radiation to a relatively smaller absorber. PTC consists mainly of a mirror and an absorber tube. It is a single axis tracking system, which means it is following the sun in one direction and can be mounted either east-west or north south direction. Therefore it needs a continues and accurate tracking adjustment to compensate the changes in the sun s position (4).

4 Figure 2. Parabolic through concentrators (6) LFC (linear Fresnel collector) This technology relies on linear mirror strips which concentrate the sun s radiation to a fixed absorber. It can be seen as a broken-up parabolic through collector field but flat type, which will make it less cost intensive. These mirrors are single axis tracking and focusing the radiation to one single line, where the heat is absorbed. The absorber itself is fixed (4). To compensate the inaccuracy of concentration caused by the flat mirror stripes, a CPC concentrator is mounted on the backside of the absorber tube, which concentrates and reflects the part of the solar radiation which does not meet the focal line to the backside of the absorber tube. Figure 3. Frenel collector (7)

5 4.2 The Three demonstration plants The solar collector systems are planned to be installed at the following demonstration sites with different industrial processes: Austria: Berger Fleischwaren GmbH Fleischwaren Berger GmbH is a company located in Sieghartskirchen, Lower Austria with about 380 employees. The Production is approximately tons of meat and sausage products per day. Solar field details: For the processing of the delivered feed stock / raw material coming from the abattoirs, Berger plans to install solar flat plate collectors with an overall area of ca. 1,200m² on the south oriented roof of one production hall, which corresponds to a potential energy supply of 4,466 kwh/d. The produced thermal energy shall be mainly used for feed water preheating for steam boiler and the surplus heat shall be used for increasing the supply temperature within the heating water system up to 60 C. The feed water of the vapor vessel shall be preheated up to 95 C. For this, a preheating of the fresh water to 30 to 35 C before reverse osmosis and a feed water heating up to 95 C after reverse osmosis (3 m³/h hot water demand) is required. The steam is internally required for process heating specifically for ham cooking. The hot water is required for drying the air conditioning systems specifically in the climatic chamber and the maturation room for production of long-lasting sausages. The implementations at Berger concentrate on centralized water and steam production facilities that can be found in almost any industrial production site that uses thermal energy. Therefore, the system analyzed at Berger can be easily transferred to other sites and offers a high replication potential. Expected energy yield and CO2-savings: The heating capacity of the m² solar collector field is approximately 650kW. The solar system is expected to deliver 600 MWh per year heating energy to the production process, which corresponds to a high specific collector yield of 500 kwh/m²a. This will reduce the heating oil demand of Berger by about 120,000 liters per year and reduces the CO2 emissions by approximately 318 tons per year. Figure 4. Hydraulic scheme of the planned solar system installation at Berger Fleischwaren GmbH

6 4.2.2 Italy: Laterizi Gambettola SRL (SOLTIGUA) The company Laterizi Gambettola SRL located in Gambettola, Italy, manufactures several types of clay brick, including highly insulating hollow clay blocks for external walls of buildings.. The manufacturing process involves a number of operations where heat is required, from brick extrusion, where hot water/steam is used to increase the raw material ductility, to wet brick drying and brick cooking. The Production process: The raw material is first processed and mixed, then it is extruded and the wet bricks go into the dryers. The total average consumption of the dryers is 2.2 MW at temperature levels of 200 to 260 C. Afterwards, the dry products are positioned on the kiln chariots and are then fired in the kiln. The kiln typically works 24 hours for 7 days per week and is shut off only for yearly maintenance. In the kiln a temperature of more than 900 C must be reached in order to complete the firing of the clay bricks. The high temperature is obtained with gas burners, which heat the air directly in the oven. The average thermal power consumption is roughly 4.5 MW. Total energy consumption on a typical year is around 41.8 GWh, 70% of which are used in the kiln and 30% in the dryers. Solar field details: Fresnel collectors with a 2,640m² field size will be used to reach a total planned capacity of 1.2 MW at a steam outlet temperature of 180 C. Steam will be produced by two collectors fields working in parallel, both directly (Direct Steam Generation) and indirectly (by a thermal oil solar circuit). In this way the two techniques will be compared and strong/weak points will be highlighted. The solar integration will take place mostly with a steam to air heat exchanger, by increasing up to 160 C the temperature of the ambient air used in the dryer, which will allow for more efficient operation and therefore for energy savings. Expected energy yield and CO2-savings: The heating capacity of the 2,640 m² solar collector field is 1,264 kw. The solar system working at 200/240 C is expected to deliver 1,200 MWh per year heating energy to the production process, which corresponds to a high specific collector yield of 450 kwh/m²a. This will reduce the gas demand of Laterizi Gambettola SRL by about 140,000 m³ per year and reduces the CO2 emissions by approximately 300 tons per year. Back up NG burner Solar field Control 180 C, 2000 kg/h Heat exchanger Air flow rate m³/h att ambient T out Production Process Figure 5. Layout of the solar heat implementation at SOLTIGUA Italy

7 4.2.1 Spain: Lácteas Cobreros S. A. Lacteas Cobreros S.A. is a company with over 20 years experience within the dairy and the transport industry (own transport fleet) and it is located in Castrogonzalo, Spain. The company has 45 employees. The production plant has enough capacity to cover all needs required by the cheese and dairy manufacturers. The production volume is over 4,000,000 liters of milk per month. Produced products are different kind of cheese (goat, sheep) in different versions and different kind of milk products (powder milk, concentrated milk, UHT goat milk and milk in bulk). The production process: The milk is brought by trucks and stored in l storage barrel. Afterwards it is pre treated and split for various milk products. Inside the dryer is an atomizer, which is heated with the hot air (185 C) provided by a steam-air heat exchanger. The quantity of the dried milk is 2,000 liter milk per hour. The highest energy consumption is required for the milk drying process with approximately a gas consumption of 35,000 kwh per day. The continuous process has permanent thermal power demand of approximately 1.5 MW for 24 hours a day. The following schematic shows the production and main flows. Steam production Solar field T_Solar=200 C Solar assisted steam production Burner for steam production Incoming goods Production Process Products Steam network Supply of 300t -370t milk/day 2 Storages (50t milk) Pre treatment Dry milk production (1.5 MW, 185 C) Ready for dry milk transportation Milk production Ready for milk transportation Cheese production Cold storage Ready for cheese transportation Figure 6. Solar assisted steam generation at Láctas, Spain Solar field details: The planned solar field will be installed on some larger surrounding ground area of the property of Lácteas Cobreros. The parabolic trough collectors with 2,040 m² total collector area will be operated with thermo oil at approximately 200 C collector outlet temperature. The hot thermo oil will be feed in an indirect steam generator to supply steam to the existing steam network supplying the steam to air heat exchanger heating up the drying air to 185 C. In times without milk drying the heat is fed into the steam network to supply heat for milk pasteurization, for washing processes and washing machines. Expected energy yield and CO2-savings: The heating capacity of the 2,040 m² solar collector field is 1 MW. The expected heating energy yield is approximately 1,064 MWh/year, which corresponds to a specific collector yield of 520 kwh/m²a. This will reduce the gas demand of Lácteas Cobreros by about m³ per year and reduces the CO 2 emissions by approx. 284 tons per year.

8 5 Conclusion / Outlook The detailed analysis of the production processes at the three demonstration sites focuses on one hand on potentials for energy savings through internal heat recovery and through changes in the heat supply of some of the production processes involved. On the other hand, the process analysis delivers detailed load profiles of the different heat sinks, which are extremely important for the control design and the size of heat storages of the solar system. However, also changes in the production could help to increase the solar energy yield but are often extremely difficult to implement. Within InSun this intensive analysis phase will be completed by end of 2012 and will help to improve the solar system design and the integration into the production processes involved. The first complete solar collector systems will be installed between end of 2012 and mid of Therefore, first monitoring data will be available starting from 2013 and will be published on the project web page ( 6 Acknowledgements The research leading to these results has received funding from the European Union's Seventh Framework Programme FP7/ under grant agreement n ENER/FP7/296009/InSun References 1. C. Vannoni, R. Battisti, S. Drigo. Potential for solar heat in industrial processes. s.l. : IEA- SHC programme and Task IV of the IEA SolarPACES programme, CIEMAT, C.Lauterbach, S.J.Rad, B. Schmitt, K. Vajen. Feasibility assessment of Solar Process Heat Applications. Kassel: ISES Solar World Conference 2011, C. Vannoni, R. Battisti, S. Drigo. Potential for solar heat in industrial processes. s.l. : CIEMAT task 33, Kalogirou, Soteris A. Solar Energy Engineering Processes and Systems. s.l. : Elsevier Inc., SOLID Smirro Soltigua C. Faber, A. anthrakidis, M. Lanz, M. Rusack, F. Weis, M. Adam, S. Schramm. Bariers to Solar Process Heat Applications. Kassel: ISES Solar World Conference 2011, 2011.