SU754374A1 - Method of regulating temperature in zone of feeding raw material into fractional column - Google Patents

Description

The invention relates to methods for automatic temperature control in distillation columns, can be used in the refining, petrochemical, chemical and other industries.

A known method of controlling the temperature in the feed zone of a distillation column, which consists in the fact that the flow of steam into the heat exchanger is changed depending on the temperature at the outlet of the feed stream.

This method does not allow maintaining a constant temperature in the feed zone of the column and, therefore, the quality of the target products.

Closest to the proposed

temperature control method 20

raw materials entering the feed zone of the column, by changing the flow of the coolant in the heat exchanger depending on the temperature on the "control plate". 25

With such a supply of raw materials along with the raw material stream, thermal perturbations are introduced into the nutrient zone of the column, since the temperature of the raw material stream directed into the column may not be 30

2

correspond to the temperature in the feeding zone, which entails the deterioration of the pore-separation ability of the column.

The purpose of this invention is to improve the accuracy of temperature control in the feed zone of the distillation column. This goal is achieved by measuring temperatures in the upper and lower sections of the column, forming signals proportional to these temperatures. These signals are added and fed to the temperature controller as a task to control the temperature in the feed zone of the distillation column.

FIG. 1 - typical temperature profile of a column of clear rectification (n - number of plates; ί - temperature; n * - number of feed plate); Fig.2 shows the analytical dependence of the temperature variation along the height of the column (ι temperature; η is the plate number; "temperature is in the lower section of the column;

- temperature in the upper section of the column; n ^, n2 ~ numbers of plates on which thermocouples are located; n * is the number of the food plate; ι * - temperature in the nutrient section); in fig. 3 device for the implementation of the proposed

754374

method 71 - thermocouples; 2 electric transducers; 3 -

multipliers by a constant coefficient;

4 - the device of the simplest algebraic operations; 5 - isodromic regulator; b - the executive mechanism; 7 - under the heaters of raw materials; 8 - distillation column; T is the flow of raw materials; 11 — a heat carrier flow; FIG. 4-layout of thermocouples on the height of the column of super fine rectification of the ortho-xylene concentrate (1-5 - thermocouples on the plates 12.54.75.103 and 138, respectively, 1 ~ flow of raw materials).

The device works as follows. The temperature profile of the distillation columns, especially the columns of clear and ultra fine rectification, is expressed by the equation of a straight line. The equation of a line passing through the points A and B with coordinates η _{} ι} and π ₂ > ϊ ₂ (Figure 2) has the form:.

η * -η ₍

7 _ / ⁼ 7 7 ~ '. (one)

W R ^{P η} ι

where C is the temperature in the upper section of the column; - temperature in the lower section of the column; η _{ · is the number, ta redox, on which the thermocouple is located in the upper section; η ₂ - the number of the plate on which the thermocouple is located in the lower section of the column; n * number plates of food; ί * - temperature on the food plate.

Expressing from equation (1) ί *, we get:

H ₂ ~ ChNP * -n?

(pg-pl)

(2)

P 'HZ

Denote by -. after 1 - sat,

η ₂ ' ^η ι'

where is a constant factor. Then equation (2) takes the form:

(3)

The implementation of the equation is carried out by the device shown in FIG. 3. Measurement of the temperature at any two trays Hz and f _r at the top and bottom sections of the column, is carried out with thermocouples 1 and 2. Multiplication elektropnevmopreobrazovateley signals proportional

temperature values, on coefficients about and (1 - sat), is performed with the help of a multiplier at a constant factor of 3. Addition of the products obtained is performed on the instrument of the simplest algebraic operations 4,

^This output pulse enters the chamber “task” of the regulator 5. The temperature of the feed stream at the exit of the heater is measured by a thermopa, swarm 1 and electropneumatic converter 2, the output pulse of which enters the variable regulator chamber 5. The latter controls the actuator 6 installed on the line steam supply to the heater

15 raw materials 7.

The operation of the device can be illustrated by the example of an ortho-xylene concentration distillation column, equipped with 148 and 20 strips (FIG. 4). Control thermocouples 1-5 are placed on the plates 12, 54.75,103,138, respectively. According to the proposed method, the temperature is measured on 12 and 138 plates and you-.

2d is the temperature on the power plate; The calculated value is supplied as a reference to the raw material temperature controller.

The implementation of the proposed method

_ will save more than 10 thousand rubles ₇ and also improve the regulation of the column and improve the quality of target products.

'

Claims (1)

Claim The method of temperature control in the zone of raw materials supply to the distillation column, based on stabilizing the temperature of the supplied raw materials with the help of a controller by the signal of deviations from the set temperature in the feed zone of the distillation column, characterized in that To increase the accuracy of temperature control in the feed zone of the distillation column, measure the temperature values in the upper and lower sections of the distillation column, generate signals proportional to these values, summarize these signals and feed the temperature controller to set the temperature in the rectification feed zone columns. 754374 754374 fig.Z 73 / oz / 38 FIG. four