CC BY
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Section 9. Technical sciences
полиуретанового адгезива для восстановления неподвижных соединений подшипников возможно отверждение этого адгезива при температуре 20 оС.
С увеличением температуры испытаний физико-механические свойства полиуретанового ад-
гезива снижаются. Однако даже при температуре 100 оС они достаточно высоки и поэтому могут быть использованы для восстановления постелей коренных подшипников блоков цилиндров двигателей.
Список литературы:
1. Кричевский М. Б. Применение полимерных материалов при ремонте сельскохозяйственной техники. М.: Росагропромиздат. 1988. 143 с.
2. Санжаровский А. Т. Физико-механические свойства полимерных и лакокрасочных покрытий. М.: Химия, 1978, 184 с.
3. Беляев Н. М. Сопротивление материалов. М.: Наука, 1976, 608 с.
4. Омельченко С. И. Сложные олигоэфиры и полимеры на их основе. Киев: Наук. Думка. 1976, 216 с.
5. Каблов В. Ф. Исследование структуры свойств совмещенных эластомерных и олигомерных систем. Авто-реф. дис. канд. тех. наук. Л., 1976, 24 с.
Poltavtsev Vladimir Ivanovich, Kemerovo state agricultural Institute, D. T. N., Professor, faculty of engineering E-mail: determinism@rambler.ru
The structure of the flow and the response function of the cell with three-phase fluidized bed
Abstract: Set out the reasons and ways to create mathematical models of typical second generation (WTMM). They are based on the principle of circulation and technological limb response tracers. Parameters of the model is the degree of circulation %. Changing \ smoothly translates circulation model in the model of ideal mixing and displacement.
Keywords: ice, pellets, fluidization, fluidized bed, water.
We introduce the notion of a technological limb response on the basis of:
a) the final dimensions of the granular particles used as tracers;
b) the finite size of the molecules of any substance;
c) the final sensitivity analysis methods.
As tracers taken peresulfirovanny cation exchanger
KU-2-8. In an industrial apparatus revealed that after 2 hours 17 minutes in the first section of tracers available. For an ideal mixing model is assumed: the volume of section 0.04 m 3 of cation flow 0,346 m 3/h, the volume of flow tracers 0.01 ion exchanger bed porosity of the particles 0.34. The removal of the last particle tracers at these rates 1.92 hour.
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Fig. 1. Scheme of physical and ideal circulation model for one stage (cell) of three-phase fluidized-bed: 1 — the meeting point of the incoming flow and circulation; 2 — the point of separation of these flows; 3 — passive part of a three-phase fluidized-bed; 4 — the active part.
The structure of the flow and the response function of the cell with three-phase fluidized bed
Box in FIG. 1 is a circulator. It is used by us as a multistage mass-transfer apparatus. For model circulator kept well-known relationship [1]:
— The volume equal to the volume of the whole model stage plug flow;
— The volume of the zone of recirculating flow is
zero.
In order to construct a mathematical model of the circulator introduce the following logical conditions:
1. Time of one cycle of circulation is defined as:
At
V
(1)
The continuous flow of incoming material can be represented as the sum of an infinite series of such portions. Accordingly, the signal is an infinite sum of rectangles. The continuous flow of incoming material can be represented as the sum of an infinite series of such portions. Accordingly, the signal is an infinite sum of rectangles.
3. The initial concentration of tracers traditionally determined as the ratio of the volume of the signal-to-volume model. Thus:
=и
(3)
and corresponds to one round-trip time of the particle tracers.
2. Step signal square П-shaped with constant intensity and vertical start and end and duration Дт:
u = Q -At (2)
Circulation model response to the main stage on IW has a delay equal to the time of one cycle of circulation. Graphically, the response of the model presented in Figure 2.
Fi. 2. Type of cell response to the П-shaped signal
Can be clearly seen that at point 1 is equal to the response delay Дт, and its concentration corresponds C0 she will remain in the range of 1-2. Subsequently, the concentration of the response falls in steps until the release of the last particle tracers.
In other words — the amount of the step signal (the value of its portion) changes from the initial to the final, the appropriate volume of a single particle. At each interval of the particle each time portions have the same phase interaction.
From the diagram (Figure 2) and the expressions (1) — (2) are counting the quantity of each portion in locations 2, ..., m:
Uj = Q -At
U = Q -At(1 - C )
U3 = Q - At(1 - C )2 (4)
U = Q - At(1 - Co )
From the expression (4) to identify features of the process of circulation: — the residence time of the particles in the volume level can be calculated as the sum of the periods of cyclicity;
— For each portion of the outgoing tracers known for its residence time;
— The initial number of tracers is crushed into pieces up to a single particle.
Mathematical analysis of the system (4) shows:
— ОДт factor in all the expressions remains constant;
— The difference in parentheses on the value is less
than 1.
Therefore, each line of the system is a member of infinitely decreasing geometric progression:
a + aq + aq +... + aq +... (5)
where: a = ОДт and q < |1 |.
Sum of a geometric progression is:
s = (6)
1 - q
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Section 9. Technical sciences
Substituting the values of the variables in (6), we obtain:
QAt = V
1 -(1 - C )
(7)
The physical meaning of this expression is contained in the following. To the incoming flow Q is presented in the form of an infinite sequence of signals portioned duration At (Figure 2). Therefore, a step number 1, 2, ..., m — 1, m; represents a portion of the residual signals in the corresponding time interval. The sum of these portions is equal to the volume of material V in the cell.
Circulation model based on the expression (1) — (3) gives:
— time delayed response;
— The composition of the portion in the volume of the cell;
— Residence time of each portion. Note that the physical concentration of tracers into each time slot in each portion constant. But his focus on the entire volume of the cell — the variable (dotted line in the diagram of FIG. 2).
Diagram system and (4) show that each portion of material entering into the circulation cell rpspadaetsya apart with each cycle. Therefore, the flow of material from the cell contains the sum of the departed parts, ie has been uneven continental structure. Volume of each side is equal to:
Лц = Q -At-Co
Ли = Q-At-Co (1 - C )
Ли, = Q-At-С, (1 - Co )2 (8)
Ли = Q-At-C (1 -C )"
m ^ o \ o /
Denote Q At C0 as “a” and the previous (1 — C0) = q then obtain a geometric progression, which is equal to the sum of terms:
Q AtC
1 -( -c )
= u
(9)
Equation (9) shows that the flow Q coming out of the cell during At is the sum of parts gone, and the composition of the cell volume and its response are subject to the law of geometric progression.
Fig.3. The composition of the cell response Aum
Note the features of each of the Au which has the
m,
same interaction time, as her portion um The parent. Their mathematical difference is in the factor C that
0 so
naturally the following expression:
Áv = C ■и (10)
Any amount of material entered as a stream of Q during the At into the cells, break up into a chain of “m” units. For each subsequent portion of the exponent of cofactor (1 — C0) is incremented by 1.
These portions of the effluent create pieces that are the initial portions of the second stage for many of the sectional unit. Of them in the cells of the second stage of the chain generated by portions ofa geometric progression.
We substitute the expression (3) values of the variables of the formulas (1) — (2). We obtain the relation:
C =
QAt Q
= 4
(11)
AtQ. Q.
We denote it as a variable % because flow ratio hraktirizuet intensity of the circulation process. There is a duality — the formal equality of the initial concentration of tracers and flow ratio.
The reason for its occurrence — binding concentration tracers for the duration of the cycle of circulation. Prior to this work the amount of tracers in the pulse assigned arbitrarily.
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The structure of the flow and the response function of the cell with three-phase fluidized bed
These relationships characterize the first stage of Parameters N and % form a two-parameter model ofthe
mass-transfer apparatus with a number of stages N. partitioning process with perfect circulation and recycle.
Fig. 4. Respon-se circu-lation model in the ran-ge Ç = 1 — 0.0 ...
Striving to % limits 0 and 1 smoothly translates circulation model (Figure 4) in the model of ideal mixing and displacement (respectively). When % values of 0.01 and less response graph circulation model is indistinguishable from the graph model of ideal
mixing.
In the graphs (Figure 4) is depicted successively:
% = 1, the ideal displacement, the response delay time C equal to the mean residence time of the particles;
% = 0,5, assumes the character of the exponential response, the delay time B of 0.5 mean residence time of the particles;
% = 0,1, distinguishable part of the response delay time A;
% = 0,01, the response corresponds to the model of ideal mixing, part of the response, and the delay time are indistinguishable;
In the latter case, the theoretical curve coincides with the ideal mixing points graphics process at a ratio of circulation flow inlet and one air lift 100. Therefore, the processes in which the flow of circulation (in whatever
way — mechanical or pneumatic — he may be created) exceeds total input more than 10 times, it is possible with high accuracy as a process of ideal mixing.
Using a circulation pattern in the form of Figure 2 and systems (4) and (8) is inconvenient because even for the 1st stage formed a pile of information. For the 2nd and further steps information may be used only in a piecewise form. Therefore, the model will reflect in a matrix scheme that allows each stage to give a complete device information in a compressed form (Figure 5).
Scheme for circulation model shows that its response contains a number of consecutive terms. Response is delayed by Дт (range 0-1) and forms a one-dimensional linear array. His probation is denoted by a thick line. The index is part of a changing response to the natural numbers. Columns contain one term.
Factor (1 — %) contains in the exponent difference between the sum of the index and the number of stages. Therefore, for clarity, it is shown with 0-values for the first term.
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Section 9. Technical sciences
The numbei/ г Л of terms y © © © ©
О CM CO ■Sf
UO 1 The mngni- |_j \ w OCO t и OO l h-t uo I
и
lude of the '
oo U/O <jy~> (AO
L4 f-J fcJ tí tí
<3 % <1 <]
<3 a> Of a* CÍ
II Ü It 4 Ü
Pan Number 'S cLT> к
Index ^ 2 4 5
Interval X 2 3 4 5 —i>
Fig. 5, the matrix structure of the response of a circulation model.
Conclusions:
1 The notion of a technological limb portions of the residence time of the solid phase in a continuous process.
2 Incoming represented as a finite sum of such portions, the number of terms which limited value streams entering and airlift and the magnitude of the volume of a single grain.
3 Any portion included in any stage, crushed by a circulation of up to a single particle, and a portion is reflected mathematically П-shaped signal over a time interval interval circulation.
4 Ingredients stages and heterogeneous response model and its components corresponds to a geometric progression, the sum of which gives the volume in portions stage, and in parts — volume response stage.
5 Parameters of the model: the number of steps and the intensity of the circulation within the parameters of the real process.
6 The algorithm for calculating the model presented in the form of a matrix, the dimension of which corresponds to the number of steps.
References:
1. Kafarov V. V. Methods of Cybernetics in Chemistry and Chemical Technology. - M.: Chemistry, 1971.
Sazykin Vasily Georgievich Kuban State Agrarian University, Professor, Faculty of Energy E-mail: powel@mail.ru Kudryakov Alexander Georgievich Kuban State Agrarian University, Associate Professor, Faculty of Energy E-mail: agk61@inbox.ru
The problems of worn-out equipment in the energy sector
Abstract: The article deals the causes of the appearance of worn-out electrical equipment, clarifies terminology. Invited scientific direction of the electrical geriatrics on the issues of extending the life of electrical equipment. Keywords: worn-out electrical equipment, causes of the appearance, electrical geriatrics.
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