УДК 621:681

N.R.YuSUPBEKOV *, Sh.M.GULYaMOV, A.O. ATAULLAYeV, B.M.TEMERBEKOVA (TAShGTU, Republic of Uzbekistan)

CALCULATION OF STABILITY OF PRODUCTION

The method of calculation of stability of production in difficult chemical and technological complexes and the installations, considering the block diagram of communications of accumulative and technological knots is stated.

Let's address to a problem of calculation of stability of technological process [1, 2] on the example of inorganic group of productions of JSC Navoiazot which consists of the shops making ammonia, weak nitric acid and ammonium nitrate. In turn, shops share on turn because of territorial dissociation and technological distinctions of the same shops. For example, the first and vtokry productions of ammonia let out a product of one quality therefore their division is caused by only the territorial and administrative reasons. Shops of weak nitric acid No. 5 and No. 25 make nitric acid of different concentration. Liquid ammonia исполь¬зуется in shop of nitric acid No. 25 also goes on shipment

Gaseous ammonia from the general collector is used in shops No. 5, 3 and 23.

Production of liquid and gaseous ammonia is connected by a sokotnosheniye:

(1)

where т — coefficient, time-dependent years, conditions of water condensers, temperatures of reverse water etc.

M size for planning is established by production department of the enterprise.

The collector of gaseous ammonia can be considered as a peculiar warehouse, to the top and which bottom level there correspond maximum and minimum admissible pressure of gaseous ammonia, and to the current level - pressure at present to time.

For calculation of amount of ammonia in a collector (that corresponds to the current level of filling of accumulative knots), and also minimum and maximum admissible amounts of ammonia in a collector we use formulas

(2)

where - the specific weight of ammonia under normal conditions; T - ammonia temperature, °К; - collector volume; - maximum and minimum admissible pressure in a collector; - the current pressure in a collector.

Size depends on ammonia temperature in a collector, - is set by production regulations. The collector is considered in mathematical model of a warehouse as accumulative knot with parameters

By consideration of inorganic group of shops of studied object the following regularities of change of loadings are revealed. Shops of ammonium nitrate and weak nitric acid change the load of new value for 10÷15 min., that is in relation to the considered period almost instantly. After change of an entrance stream in shops of nitric acid and ammonia on an entrance to office of conversion of ammonia productivity of office of absorption of shop № 5 changes through 50÷60 min., and shops № 25 — in 70 min. after the beginning of change of loadings. It is enough this time to bring concentration of acid in absorbing columns to procedural values. Change of output streams after establishment of concentration happens within 10 min., that is values of output streams of shops No. 5 and № 25 change in relation to entrance streams with temporary shift 55 min. and 70 min. according to.

After change of loading of shops of saltpeter No. 3 and No. 23 on a consumption of ammonia on an entrance to devices ITN the consumption of the ammonium nitrate arriving on granulyatsionny towers, will start changing through 25÷30 min. and lasts 5÷7 min. Change of output streams of these shops про¬исходит at the same time with change of a consumption of saltpeter on granulyatsionny towers, that is for 5÷7 min.

Thus, for shops № 5, 25, 23 and 3 dynamic characteristics are determined by channels "the entrance-day off по¬токи" by value of time of pure delay (these temporary shifts are equal respectively 55 min., 1 hour 10 min., 25 min. and 25 min.).

Operational overloads of ammoniac productions are carried out by change of loadings of gas compressors. Operating parameter in this case is the converted gas. Speed of change of loading is defined by the dispatcher depending on a concrete production situation.

At creation of model of a technological complex the following assumptions are accepted:

— warehouses of liquid ammonia, ammoniac productions of I and II turns are united in one accumulative knot;

— ratios of production of gaseous and liquid ammonia on an interval of a usage time of the decision are constant and don't depend on loading size;

— weight functions on loading productivity channels and the current account coefficients calculated on the moment, are considered as constants and are set in the form of a set of ordinates on each channel;

— volumes of C₃ and C₂₃ stores are rather great, and possibility of their overflow is absent (these stores in model aren't considered).

Structural communications between shops and accumulative knots are presented by the following matrix from 6 columns and 4 lines:

	shop 1	shop 5	shop 3	shop 26	shop 25	shop 23
К	0,830	-0,450	-0,220	0,830	-0,033	-0,220
С5	0,000	1,000	-0,790	0,000	0,000	0,000
А=СЖА	0,170	0,000	0,000	0,170	-0,110	0,000
С25	0,000	0,000	0,000	0,000	1,000	-0,790

It is a matrix contains information on values of coefficient of recalculation of production - wow technological knot in a product - wow accumulative knot. The sign "+" means receipt in accumulative knot, a sign "-"-production consumption from it.

Weight functions on channels "loading of gas compressors-production of ammonia on shops №1 and 25" are set in the form of a set from 11 ordinates. - vector of tasks for output in technological knot on time interval (it is set by the dispatcher or production department of the enterprise). Task example: = (240; 720; 330; 300; 240; 140).

Here tasks for output in technological knots in an order corresponding to an order of a matrix are presented . Similar to the dispatcher it is set - a vector of possible speeds (rate) of change of loadings of technological knots. Record example:

For this model vectors maximum () and minimum () admissible stocks in accumulative knots have the following values: = (50; 1; 100; 100); = (500; 3; 1500; 1000).

Let's enter the following designations: - a vector of the greatest possible productivities (grows out of the solution of a problem of calculation of the current capacities of technological knots); - vector of minimum admissible values of productivity of technological knots (it is set by production schedules); - vector of the current productivities and levels of filling of accumulative knots (the primary processing of entrance information (PPEI) grows out of the solution of a task).

For calculation of stability of technological and accumulative knots the following expressions are used:

(3)

where

Here: - measure of stability of knot in a timepoint (time during which level of filling with production of knot will reach one of the borders in the absence of impacts on the related technological knots); and - maximum and minimum admissible borders of filling of a warehouse production; - the size of a plan target to technological knot on a planning interval T; - the greatest possible development of knot at the maximum involvement of all resources available for it during the whole period - loading at the maximum attraction of all available resources during the T period; - time when it is necessary to begin transition to maksikmalny loading that process didn't leave stability area (stability of knot at the moment at loading - for an interval - shift of the beginning of change of development in relation to the beginning of change of loading - for an interval - transition time from development before development for an interval with the moment; ; - speed of change of development from to .

If in a timepoint the knot has filling level , and difference between entrance and output streams in accumulative knot (i.e. balance on a warehouse) is equal , depending on a sign of this difference the accumulative knot will or be filled (at > 0), or to be devastated (at < 0).

At achievement in accumulative knot , the upper bound of filling technological knots, developing production , won't be able to continue the work as they will have no place to give the production.

At achievement in knot of the lower bound of filling, the technological knots using this production, won't be able to continue the work because of absence at them one of types of resources. In both cases the continuity of technological process is broken that at the continuous production technology means an emergency situation.

The first composed in the last expression corresponds to the stock of time caused by a reserve of power, and the second and third members - the amendment on the speed of an increment of development and on development shift in relation to loading.

As the size estimating a condition of production as a whole, pays off

(4)

As a result of the solution of a task to the dispatcher table listing with a set of sizes of stability of technological and accumulative knots is given.

Results of the decision are used as the output data for an optimizing problem of coordination of loadings. At the same time results of the decision have independent value. The problem can be solved and is autonomous; so, for example, the dispatcher uses results of the decision for an assessment of possibility of performance by separate production divisions of plan targets, definitions on production bottlenecks.

Setting various values of parameter , the dispatcher loses production situations on model. For calculation of optimum trajectories of loadings of technological knots as basic data it is possible to accept the following information: current values of entrance and output streams : ; the current values of levels in accumulative knots ; the greatest possible productivities of technological knots on an interval ; conditional and constant data - weight functions on channels "entrance - day off streams", plan targets on an interval ; maximum and minimum possible levels of filling , ; possible speeds of change of loadings of technological knots.

Almost all basic data have character of forecasts. Possible speeds of change of loadings of technological knots are set by the dispatcher before calculation depending on a technological mode of production divisions.

List of references

1 . N.R.Yusupbekov, R.A.Aliyev, F.T.Adilov, Sh.M.Gulyamov Analytical information technologies of automation of productions. // ТашГТУ, Tashkent, 2002-196s.

2 . Mukharamov F.S. etc. To a question of criteria of management in quick and dispatching systems. // On Saturday. : Automation of chemical productions. M: NIITEHIM, вып. 2, 1980. – page 14-17.