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Using COSS membership functions “inlet steam pressure” shown in Fig. 1.8.,
analogy degree of products with values of steam pressure 1.1 and 1.5, and analogy
degree of products with values of steam pressure 6.1 and 6.6 were calculated.
Further results are obtained:
ρ
=
0
,
34
,
ρ
=
0
82
. According to [35],
1
5
6
,
6
,
6
these results are consistent with the experience of experts.
Example 2.9.
Fuzzy control of technological process of coal beneficiation by a
separation method. The separation method has been widely spread in coal
preparation industry throughout the world thanks to it simplicity, cheapness and
universality. From the automation point of view, separation process is complicated
enough due to absence of adequate mathematical model and presence of a number
of difficult-to-control variations (load, granulometric, fractional and chemical
composition of a raw product), and also lack of operative analysis methods of
prepared product and wastes.
Hydraulic separation is a process of separation of raw mixture components in
vertically pulsing stream of water having an alternating velocity. According to a
classical trend of the separation theory, the separation coefficient during coal
beneficiation in the jolting machine is the relative difference in fall final velocities
depending particle size, density and medium density. Raw coal is loaded on a
sieve of work bay. Piston or compressed air initiates vertical oscillations of water.
A mixture of coal, breed and intermediate fractions, which locates on the sieve
(bed), is entered alternately in loosened and condensed conditions by pulsing
water stream. Due to press of portions of loaded raw material and also due to
movement of transport water arriving to the machine with a raw material and
under-sieve water, the whole bed moves in a horizontal direction being
simultaneously stratified on heavy and light products. The lower layers of bed
consisting of heavy products are removed from the jolting machine through a
discharge unit which located on ends of each stage of the jolting machine. The
prepared product or a concentrate together with water are discharged through a
decanting edge.
The parameters influencing separation process are either hydrodynamic or
technological. The hydrodynamic parameters are those initiating oscillation
conditions of medium and fluidization of bed (flow rate of under-sieve water and
air flow rate are of especially great importance). Technological parameters are
connected with quality of prepared coal, i.e. their fractional and granulometric
composition.
The coal beneficiation fuzzy control model for a separation method is
developed by the laboratory of fuzzy techniques of Institute of an automation and
electrometry of the Siberian branch of the Russian Academy of Sciences.
The control scheme proposed has two hierarchy levels. Lower level consists of
technological process parameter regulators (unloading of heavy fractions, air and
water supply). Operation mode of these regulators is set by a top-level fuzzy
controller based on the information on structure of raw working mixture and
operative control data (of fractional analysis, indications of ash gauge, etc.). The
bed level regulator is implemented as two-input fuzzy controller. A bed height
error signal (difference between set value and actual value) and a bed height error
