kajaaniMCA
i
– Installation, Operating & Service - 1.1 - W4610201 V2.5 EN
1.B. Measurement Principle
Microwaves are a form of electromagnetic radiation.
Their propagation velocity is dependent on the medium
in which they travel. The propagation velocity is calcu-
lated using the following formula:
v = c / e
r
where c = velocity of light in vacuum;
ε
r
= dielectric constant of the medium.
Microwaves travel considerably more slowly in
water than in wood fibers. Thus the quantity of wood
fibers – i.e. consistency – can be determined by measur-
ing the propagation time of microwaves through the
pulp stock. Kajaani MCA
i
measures the propagation
time of microwaves between the transmitter antenna
and the receiver antenna. This measurement method
has several advantages: it is independent of pulp type
and pulp flow rate, and only requires single-point
calibration.
1. Introduction
1.A. The kajaaniMCA
i
Consistency Analyzer
The kajaaniMCAi is an in-line consistency analyzer
based on microwave technology. The kajaaniMCAi
measures pulp consistency based on the propagation
velocity of microwaves. Due to this measurement prin-
ciple, the analyzer can be used on a very large conduc-
tivity and temperature range. In addition, the measure-
ment is independent of pulp type and flow rate.
The kajaaniMCAi is available in two different sen-
sor types: MCAi -F & MCAi-FS (Fork type), and
MCAi -FT (Flow Through type). The sensor is always
delivered with a Display Unit which can be used to
perform the most important operations (e.g. sampling).
The portable Communicator terminal, with additional
functions, is available as option.
Fig. 1.2. Measurement principle of the kajaaniMCAi.
Transmitter
Receiver
Reference line
Transmitter
antenna
Receiver
antenna
Pulp
Fig. 1.1. Construction of the kajaaniMCAi-FT.
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