Advanced Process Control of a cement plant grate cooler

The present work describes an Advanced Process Control solution applied to a cement plant grate cooler. The grate cooler is located downstream of a clinker rotary kiln with the purpose of suitably cooling the clinker. Clinker is cooled through the action of multiple cold air fan units as it is transported by the clinker rotary kiln. A Model Predictive Control strategy was designed in order to minimize the electrical energy consumption of the cold air fan units while guaranteeing the necessary heat recovery for the kiln and the preheater. At the same time, clinker quality constraints are taken into account. The designed controller has been installed on the real plant, obtaining satisfactory results in terms of kiln tertiary air increase and of kiln combustion improvement. In particular, a major process stabilization has been achieved, proven by a significant reduction of the standard deviation related to the pressure of cooler grate.

I. Introduction

Cement industry plays a key role in many countries. The cement industry requires a lot of thermal and electrical energy: clinker rotary kilns and clinker grate coolers are examples of energy-intensive processes [1]. In the last decades, increasingly stringent specifications for reducing environmental impact and improving energy efficiency have been a driving force for significant innovations in the cement production process, both from a management and automation perspective [2]. In this context, Advanced Process Control (APC) systems are playing a significant role due to their ability of optimizing industrial plants without necessarily requiring hardware modifications [3]–[6]. In these fields, the digitalization is assuming a key role: Big Data and Artificial Intelligence can represent strategic drivers in the Industry 4.0 context [7]–[9].