TO DEFINITION OF LEVEL OF DANGER OF
THE EQUIPMENT
AT THE STAGE OPERATION
A.A.Akusova, A.A.Toporov
Donetsk national technical university
Ïåðåâîä âûïîëíèë:Êàëèíè÷åíêî Ð.Ñ., Ñòàòüè: Àêóñîâà À.À.Ê ÎÏÐÅÄÅËÅÍÈÞ ÓÐÎÂÍß ÎÏÀÑÍÎÑÒÈ ÎÁÎÐÓÄÎÂÀÍÈß ÍÀ ÑÒÀÄÈÈ ÝÊÑÏËÓÀÒÀÖÈß/À.À.Àêóñîâà, À.À.Òîïîðîâ//Äîíåöê, 2010ã.—ñ.ñ.162-163
Work of the chemical equipment is connected with
processing, storage and transportation of various environments, including,
toxic, a fire - and explosive. At the same time frequently technological
processes pass at heats, pressure which can change in the big limits during all
process. All it does the equipment of the chemical enterprises potentially
dangerous. As one of major factors of danger of the chemical equipment is its
strong deterioration arising at joint influence of mechanical loadings and the
corrosion environment of the equipment or its environment.
On a design stage the danger of the equipment arising
at occurrence of emergencies is defined. For the chemical equipment as danger understand basically uncontrollable emission of
energy at failure, i.e. the working environment power potential is considered.
For example, energy of explosion of substances, thermal radiation, toxic
influences. Such understanding of danger allows to define
the greatest possible emission of energy at equipment destruction. The
knowledge of the maximum danger allows to accept a number of measures on its
decrease; calculation of optimum technological parametres
(pressure, temperature, concentration, speed of movement of environments,
etc.), placing, design strengthening.
However such understanding of danger does not allow to define level of danger of the equipment during operation.
For definition of level of danger of the equipment during the set moment of
operation of the equipment it is necessary to consider not only equipment power
potential, but also its technical condition. Ò.å, considering
danger of the equipment, we will allocate two basic aspects which form it: 1)
power potential of the equipment which acts as motive power, danger occurrence;
and 2) function of a condition of the equipment which constrains energy
liberation, i.e. resistance to danger occurrence.
Thus, it is possible to express danger of object
function depending on power potential and a technical condition of object.
Danger = Function energy potential / condition
Function
As condition function it is possible to accept a
residual resource, factor of safety factor of the equipment, failure rate, etc.
it is Sometimes more convenient to use return size of a residual resource —
degree of degradation of the equipment then danger is equal:
Danger — power potential Function * Degree degradation
Thus degradation degree is likelihood size. It is
connected by what to consider all proceeding degradation processes practically
not probably. And as degradation processes have likelihood character since the
factors causing processes are not constant and constantly change in time, ò.å are random
variables. Thus, because of likelihood character of function of degree of
degradation of the equipment, danger of the equipment during the set moment of time, is likelihood size.
The minimum danger of the equipment arises at a normal
operating mode of the equipment and the minimum degree of degradation.
The maximum danger of the equipment arises at
achievement of critical level of degradation of elements of system and the
maximum power potential. I.e. when there comes a limiting condition the
equipment, and the power potential has the greatest value. Such case leads to
failure occurrence, t.i. danger is realised.
However for danger realisation,
t.i emergency occurrence, it is not obligatory
coincidence of all adverse cases (the maximum power potential and degradation
degree). First, the emergency can arise at achievement of degree of degradation
of limiting value, at normal technological indicators, t.i
comes degradation refusal - the refusal caused by natural processes of ageing,
wear process, corrosion and weariness at observance of all established rules
and norms of designing, manufacturing and operation. Secondly, at achievement
of the maximum value of power potential, thus it is not provided at designing
that the equipment can maintain such loadings (it sometimes unfairly
expensively to carry out), t.i there comes
technological refusal. The third case when there is a certain combination of
values of power potential and degradation degree at which there can be an
emergency. For the concrete equipment this combination
probably to count and define critical danger, t.i at
which potential danger passes value in the real.
To factors of resistance of danger, except the service
life, it is possible to carry protection frames and
preventions of emergencies. For the account of their influence it is possible
to allocate them in separate group, for this purpose we enter criterion of
equipment of object protection frames or criterion of additional resistance of
danger. Then danger is equal:
Danger Function energy potential * Degree degradatsii/criterion
Equipment of object protection frames
The criterion of equipment of the equipment protection
frames includes as action for decrease and adjustment of power potential of the
equipment at the expense of automatic control systems in technological parametres, and means on increase of resistance to action energy
potential.
This criterion of additional resistance of danger is
necessary for entering both by consideration of separate object, and at
definition of danger of group of objects. For example,
if protection frames do not concern concrete technological object, and are
protection frames of the whole technological process. It is necessary to define
to that the criterion of resistance in the presence of this or that protection
frame is equal. Calculation it is necessary to make the since the same
protection frames differently influence each equipment for each equipment, for one
they can prevent danger to others only to reduce consequences, thus it is
necessary to consider; the protection frame interferes with occurrence of an
emergency or reduces negative influence; degree of operation of the accident
protection device; influence on resistibility of a part of the equipment or as
a whole; what quantity of all possible breakages influences, etc.
Definition of degree of danger at an operation stage
will allow to supervise level of danger of the equipment and not to suppose
achievement of danger of critical value at which there is a transition of
potential danger to the actual.