SU412902A1 - - Google Patents

Description

one

The invention relates to methods for controlling the concentration of a comonent in the product of a column.

A known method for automatically regulating the process of rectification by changing the flow rate of the lower product depending on the composition and consumption of the raw material and controlling the concentration of the heavy component in the distillate yg by affecting the flow rate of irrigation in order to maintain the desired concentration of iridesses in the products.

However, the known method does not allow to optimize the process by the profit criterion, since it does not take into account the economic factors of production.

It has been established that if the dependence of the irrigation flow rate is

, a, But + and, y + a, Lp

where f, D, B, R - the cost of raw materials, distillate,

residue and irrigation. I, L - the concentration of light and heavy components, and, if the energy costs are approximated by the expression

E r (R + D),

where g is the heat of evaporation, and if the product is selected in accordance with the material balance, then for the case when the lower product B is more expensive and the upper D is cheaper, the concentration of heavy components in the optimal distillate is given by

/ WALT 1 wholesale (LP-LO -},

where / С is a constant value depending on the prices of products and energy and on the statistical coefficients QO, ai, «2 and as.

g wholesale ..

LB is equal to the maximum allowable concentration for a given grade of a more expensive product.

In the proposed method, in order to optimize the process according to the profit criterion, the concentration of the heavy key component in the distillate is adjusted with a correction for the concentration of the light component in the feedstock and the concentration of the light component in the residue.

The drawing shows the implementation of the proposed method.

Information on the composition and consumption of raw materials in the form of signals from the chromatograph 1 and the flow meter 2 enters the computing device 3, into which a signal is manually entered proportional to the maximum allowable concentration of the light component in the residue. Calculate unit 3 using information on the composition of the raw material and the amount of the signal entered manually, formally signaling the system 4 to control the composition of the top product, adding information about the consumption of raw material to them and form the task to the controller 5 for the remainder consumption.

Example. The column, which has 60 plates, divides the amount of butane into grade I isobutane, 25 rubles each. per ton and brand B butates at 35 rubles. per ton.

The cost of steam is calculated on the condition that the price of steam is 6.22 rubles. for 1 Gcal.

Based on the above ratios, K-2 is obtained.

Raw materials contain 37% isobutane.

The maximum content of isobutia in B. grade butane is 5%.

Then get

- / 2 (0.37-0.05) 0.15. : 1 - 0.05

If the concentration of the impurity is increased, the energy costs will decrease, however, even if the cost of the more expensive butane is lower. If 11 Koiuieinpation of butane in isobutane is used to reduce and thereby increase the selection of butane, then the energy consumption (pair) will increase faster. Thus, the calculated concentration is optimal.

Subject invention

The method of automatic regulation of the rectification process by changing the consumption of the lower product depending on the composition and consumption of the raw material and controlling the concentration of the heavy component in the distillate by the impact of the oronspi consumption, which, in order to optimize

according to the criterion of profit, the regulation of the concentration of the heavy component in the distillate is carried out with a correction for the concentration of the light component in the raw materials and a given concentration of the light component in

the rest.

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