Part load operation analysis of a biomass steam generator integrated with a Linear Fresnel solar field

Abstract

Hybrid systems involving the use of biomass and solar energy have been proposed as a promising alternative to reduce greenhouse gas emissions and provide a way to overcome the inherited shortcomings of solar energy, such as intermittent and instability. Nevertheless, some plant components will operate in the off-design condition once solar energy is added to the cycle. In this regard, the objective of this work is to evaluate the performance of an existing biomass steam generator at partial loads, integrated with a Fresnel solar field in fuel-saving mode. The equipment consists of a biomass steam generator with a capacity to produce up to 50 t/h of superheated steam at 420 ℃/45 bar(a) to feed a cogeneration power plant. Measurement data were collected on-site to calculate the boiler efficiency at part loads according to the ASME PTC4 standard. The main components of the boiler were modeled using the OpenModelica® tool and the ThermoSysPro® library. The model accuracy was verified at different loads with the available measurement data and manufacturer datasheets. In conclusion, the implemented model allowed to reproduce the boiler performance in different loads, being able to evaluate the impact of the solar field integration and the hybrid boiler operation.