Silicon granulate is produced in a fluidized bed reactor having a fluidized bed region fluidized by a gas flow and heated by a heating apparatus. Seed particles and a feed gas including hydrogen and silane and/or halosilane is continuously supplied, and elemental silicon is deposited on the seed particles to form the silicon granulate, which is discharged as a continuous product stream from the reactor. The fluidized bed temperature affects the quality and formation of the product stream, which may be determined as the temperature of an offgas stream from the fluidized bend region. The temperature, as a responding variable may be determined and controlled by means of the mass and energy balance of a defined scheme.

The present invention relates to improving a performance of a production plant, in particular, in chemical industry. To this end, a method for determining a reactor performance for a catalytic reactor or reactor system is provided, the method comprising the steps of:providing reactor data indicative of a property of the catalytic reactor or the reactor system,providing catalyst configuration data indicative of a property of at least one catalyst present in the catalytic realtor or reactor system,providing a reactor model associated with the least one catalyst, the reactor model being configured for determining a catalytic reaction within the catalytic reactor or reactor system based on the reactor data and the catalyst configuration data,determining the reactor performance using the reactor data, the catalyst configuration data and the reactor model, andproviding the determined reactor performance for the provided catalyst configuration.