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BIA-Brukerstyrt innovasjonsarena

Exploiting multi scale simulation and control in developing high efficiency fertilizer technologies

Alternative title: Multiskala simulering og regulering for utvikling av høyeffektive mineralgjødsel teknology

Awarded: NOK 4.8 mill.

Mineral fertilizer is a necessity to produce enough food for all people on earth, but with finite resources it has become critical to produce the products with least amount of resources, especially with the lower carbon footprint. The project focuses on 'particulation' which is the last part of the fertilizer production process where the granules are manufactured, as this over 50 year old technology has not been optimised or improved using the newest digital technologies. The reason for this is that his part of the process is not trivial and consists of complex physical and chemical processes. The project tackles the improvement using two mathematical methods. The first approach is to develop a mathematical model of the ?particulation? that will improve the control strategy ultimately stabilising the process to increase production at lower energy input. The second approach is to model the behaviour of solid/liquid/gas interaction through mass and heat transfer. The developed model will be used to virtually simulate the existing production and test any proposed modifications without the need to modify or stop the existing production. The final goal is to implement the new knowledge to improve operation of the production processes. In addition to the modelling there has been visits to Yara's plants for competence exchange. A method for improved operation has been developed. Results based on simulations looks promising and work to test this in a plant is ongoing. In addition, it has been developed models that can simulate detailed flow behaviour in the particulation process. The new control strategies have been developed. A unique granulation model that includes heat and mass transfer with particle population balance has been developed. Validation of the granular dynamics in the model is being validated with experimental results from plant data.

The granulation circuit model of the recycle loop. a) Model developed that predicts the dynamic oscillation behaviour of the real system b) Implementation of control models to stop the occulting behaviour c) Found the best method to dampen the oscillating behaviour using new control strategy on process equipment, theoretically leading to an easier retrofitting in the plant environment. CFD modelling a) Multiphase model developed that includes Gas/liquid/Solid phases. b) Solid particle growth dynamics included c) Scaled up to industrial scale d) Allows for simulation of the detailed behaviour inside the granulation drum that will allow for 'virtual' testing of new ideas and concepts.

The overall idea is to enable cost effective production and deliver consistent product quality for granulated fertilizers. Granulation is the last part of fertilizer production where a slurry or melted fertilizer is pelletized into the final product. The most economical granulation technologies require a large recycle stream that has two major implications: 1) The utilization of the granulation unit is relatively low since a significant part of the outflow from the granulator is not meeting product specifications and needs to be recycled. 2)Granulation loops (granulator unit plus separating granules into different sizes, crushing and recycling) are difficult to operate. The recycling will in some cases lead to an oscillating behavior. Both of these points lead to a reduction in production capacity. In Yara, we see a significant potential for improvement of fertilizer production if we could 1) reduce the particle size distribution out of the granulator (when designing new or by modifications) and/or 2) remove/reduce oscillations in existing granulation plants. The development of granulation technology has previously been done mainly by practical experience from previous plants. The project will utilize recent developments within CFD modelling to extend state of the art within simulation of the granulation process including the fundamental mechanisms. Results from this research will be used to improve the design of granulators. In addition, modern control theory and dynamic simulations will be used to improve operation of existing plants. This work is partly building on a recent innovation in Yara for improved control of granulation plants that demonstrates a significant potential for improvement. The results will be implemented in Yara's plants and will also be published in scientific journals.

Funding scheme:

BIA-Brukerstyrt innovasjonsarena