4.1 Introduction:
Manufacturing of cement is energy-intensive process. Recent changes in global
economics have increased pressure on manufacturing processes to produce a
high quality and consistent product in the most economical way. Against this, the
current demands for optimized throughput has often been to the detriment of
efficiency.
Production efficiency of the clinker grinding section is highly related to the tight
control of product (cement) fineness in order to avoid the over grinding in the
process. Due to the fast dynamics from the separator speed changes in particle
size, frequent measurement of size distribution has become a necessity to achieve
desired process efficiency. Particles that are too fines (<2 m diameter) leads to
the cement curing exothermically, setting too fast and cracking. Large particles
(>32 m typically) may not be fully hydrated, reducing the strength of the final product.
On-Line particle size analyzer has been installed before cement silo feeding
bucket elevator which gives
- In depth information of product quality in size distribution
- The possibility of using high level control system (Expert system) for improving
the productivity and optimizing the specific power consumption
4.2 System Description:
On-Line PSD system has following three main parts
- In line Sampling system
- Analyzer and its electronics
- Computer Software module for data collection, analysis & reporting
4.3 Working Principle:
The primary measurement is carried out by a laser diffraction system. The particles
passing through a laser beam will scatter light at an angle that is directly related
to their size. As the particle size decreases, the observed scattering angle increases
logarithmically.
The observed scattering intensity is also dependent on particle sizes and diminishes, to
a good approximation, in relation to the particle’s cross-sectional area. Large
particles therefore scatter light at narrow angles with high intensity laser diffraction,
whereas small particles scatter at wider angles but with low intensity.
4.4 System Configuration
A typical analyzer system consists of:
- A laser, to provide a source of coherent, intense light of fixed wavelength
- A sample presentation system to ensure that the material under test passes
through the laser beam as a homogeneous stream of particles in a known,
reproducible state of dispersion