Company: Fertinagro
Sector: Agrochemical
Product: NPK fertilizer
Production Capacity: 150 kt/y
Lay-out description
The process consists on two main different steps:
- 1st Granulation. Solid material is blended with binding agents in order to form a rounded compact granule by physical and chemical process. This is the most important step as it is needed to start the chemical reaction between binding agents that provoke the good conditions to make a good granulate in the narrowest range of particle size which avoid fines a coarses that stay in a recycling steady state. Parameters as particle size of raw materials, rotational rate of granulator or viscosity of binding agents are a key for good granulation.
- 2nd Drying. In this step the moisturised granulated mass is dried with hot air with a different thermal profile. Critical parameters in this step are particles size distribution on feeding and thermal profile.
The plant is controlled by several nodes of a DCS equipment from Emerson, Delta V.
Secondarily there is a minor consumption of steam in granulator to increase temperature in granulator.
Efficiency can be improved on the heat exchange within the rotatory dryer by optimization of thermal profile and contact surface with granules.
Economical savings are expected on energy if two points are controlled:
- Particle size. The less coarse product in feeding the best for heat transfer as ratio surface/volume would be maximising. Fines below spec of final product are no good as recycle will be increased and needed to be dried again involving overcost.
- Thermal profile. The optimal situation should be the highest hot air inlet temperature with the lowest exhausted air temperature. It means the best heat exchange coefficient
Water, sulphuric acid and steam are used as binders. Changing ratios on them, parameters as viscosity of binding blend can be optimised. Temperature on granulator will be also controlled in this way.
No wastes appear on this production.
Environmentally is a clean process in which only CO2 coming from burning natural gas is produced. Taking into account that final product is the nutrient for growing plants with photosynthetic function, it means that CO2 footprint will be improved.