Demo 3 – RAR
Process: Boiling and sugar crystallization
DNI: 1667 kWh/m2
Space opportunities: a 40 m x 100 m ground space is available for the installation of a solar system.
RAR Açúcar is a company dedicated to the refining and selling of sugar. It was established in Oporto in 1962 following the merger of nine small sugar refinery units from the northern region of Portugal. The concentration of activities into one single production unit, together with ongoing investments in technology, has allowed the company to increase its production capacity and efficiency.
The plant uses fuel oil and natural gas as fuel both for the cogeneration of power and heat in a counter-pressure turbine and for the production of steam in dedicated boilers. Out of the overall fuel consumption, natural gas accounts for 37% and fuel oil for 63%.
The current installation consists of 3 boilers, fed with natural gas and heavy fuel oil. Also, there is a counter pressure turbine, having a nominal electricity production of 3 MW through the expansion of steam at 1 bar and 125°C. Finally, one gas turbine of 5 MWel and a waste heat boiler of 10 t/h at 400°C and 24 bar. The steam used in the sugar process is all at a pressure of 1 bar and 125ºC. The crystallization process accounts for a significant part of the total heat demand of the plant.
Linear Fresnel with vacuum receiver – direct steam generation system
Heat Transfer Fluid: Saturated Steam
Net Aperture Area: 690 m2
Gross Area: 926 m2
Peak power: 415 kW
Gross heat production per year: 448 MWhth
Number of modules: 30
Yearly global efficiency: 40%
CO2 savings: 143.7 tCO2eq
Solar fraction: 4% average for cristallization, 76% thermal demand during weekends
Annual sugar production increase: 1%
Heating cost: 2,92 c€/kWh
Expected payback: 10 year