SU1058569A1 - System of automatic control of rectifying tower unit - Google Patents

Abstract

THE AUTOMATIC CONTROL SYSTEM OF THE UNIT RECTIFICATION COLUMNS, containing pressure regulators connected to the valves on the supply lines of the upper rec-. of condensation columns to condensers, product level regulators in reflux tanks associated with flow controllers connected to flow sensor and valves on the pumping lines of reflux tanks, valve on the supply line of the top product from the first column to the middle The second column is different from the fact that, in order to reduce the energy consumption for the process, the system additionally contains a series of square root extractor and inverting adder, and the flow sensor and a liquid coat. It is connected with the first reflex tank into the second column, connected with the input of the square root unit, and the output of the inverting adder with the valve on the supply line of the top product from the first column to the middle of the second column.

Description

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The invention relates to systems for the automatic control of blocks of distillation columns, and can be used in the automation of technological processes in the oil refining industry, for example, clear distillation units for gasoline fractions or gas fractionation plants.

A known system for automatic control of a distillation column unit, comprising an analyzer and a flow sensor on the line. Pumping the liquid fraction from the reflux tank to the second column, a composition regulator associated with a computing unit, the input of which is connected to the flow sensor of the target product leaving the second column, and the output is with the temperature controller of the product of the first column 1,

Closest to the invention by its technical essence and the result achieved, the tattoo is an automatic control system for a unit of distillation columns containing pressure regulators connected to valves on the supply lines of the top products of the distillation columns to condensers, level regulators of products in reflux tanks, associated with flow regulators connected to flow sensors and valves on the lines of open "liquid fractions from reflux tanks, valve on the supply line of the top product from the first ring are in the middle of the second column h,

However, when using the automatic control system, an excessive amount of irrigation is used, which is brought to the required temperature due to the consumption of additional energy resources (for example, water).

This is due to the fact that the vapor and liquid phases are introduced into the middle part of the second distillation column in arbitrary amounts.

The aim of the invention is to reduce the energy costs of the process.

The goal is achieved by the fact that. a system containing pressure regulators connected to valves on the supply lines of the top products of the distillation columns to condensers, level controllers of products in reflux tanks connected to flow regulators connected to flow data and valves on the pumping lines of liquid . factions from reflux tanks, valve on. supply lines of the top product from the first column to the middle of the second column, additionally contains a series-connected unit

extracting the square root and an inverting adder, the flow sensor of the liquid fraction coming from the first reflux tank into the second column is connected to the input of the square root extractor unit, and the output of the inverting adder with a valve on the supply line of the top product from the first column to the middle of the second column.

The drawing shows a block diagram of an automatic control system of a distillation column unit.

The automatic control system contains the raw material pipeline 1, the first distillation column 2, the first condenser 3, the first reflux tank 4, the pump 5, the second distillation column 6, the second condenser 7, the second reflux tank 8, pipeline 9, the first reboiler 10, the second reboiler 11, the first level regulator 12, the first regulator of the inlet 13, the setting device 14, the first level sensor 15, the first flow sensor 16, the valve 17 located at the outlet of the pump 5, pipeline 18, the first regulator Daileni 19, the second pressure regulator 20, valve 2 valve n 22, a first pressure sensor 23 second pressure sensor 24, the dial 25 and 26, the block 27 the square root, the inverting adder 28, valve 29, conduit 30, a second level sensor 31, the second regulating layer Torr. 32, setpoint 33, second flow controller 34, second flow sensor 35 and valve 36, with the exhaust of the first and second level sensors 15 and 31 connected to the first inputs of the first and second level controls 12 and 32, respectively, the second inputs to setting points 14 and 33, and the outputs from the first and second flow controllers 13 and 34, the output of the first flow sensor 16 are connected via the first flow control valve 13 to the valve 17 and through the square root extractor and inverting adder 28 to the valve 29 and the outlets of the first and second pressure sensors 23 and 24 are connected through The first and second pressure regulators 19 and 20 with valves 21 and 22.

The automatic control system works as follows.

The wide gasoline fraction (for example, NC-180 °) enters the raw material pipeline 1 into the first distillation column 2. The distillate vapors formed in it pass the first condenser 3, where it condenses with and enters the first reflex tank 4, from which it appears as a liquid ( fraction NK-85 °) pump 5 is fed into the middle of the second distillation column 6. Some distillate vapors

From the first distillation column 2 is also directly supplied to the middle of the second distillation column 6. The distillate vapors of the second distillation column 6 pass the second condenser 7, where they condense and enter the second reflux tank 8, from which they are fed as a liquid (fraction IR-62). The heating of the second distillation column 6 and pumped out as a target product through the pipeline 9. Heat supply in the lower part of the first and second distillation columns 2 and B. is provided with the aid of the first and second reboilers 10 and 11 respectively. Liquid products from reboilers 10 and 11 — the NK-180 ° fraction and the 62-85 fraction, respectively, are pumped out from the unit as target products.

Maintaining the level of fluid in the first reflux tank 4 is provided by the first level regulator 12, the output of which affects the setting of the first flow regulator 13 of the NK-85 fraction; setting the first level controller 12 is formed by the operator using the setting device 14, measuring the liquid level is performed by the first setting level 15, the flow measurement of the HK-85 ° fraction is measured by the first flow sensor 16; the output signal of the flow regulator 13 acts on the valve 17 located on the pipeline l8 of the feed of the NK-85 ° fraction to the second distillation column 6.

The pressure in the distillation columns 2 and 6 is maintained by the first and second pressure regulators 19 and 20, respectively, by acting on valves 21 and 22, the pressure is measured using the first and second pressure sensors 23 and 24, and the formation of the tasks by means of the setting devices 25 and 26

Maintaining the correlation of vapor and liquid flows at the inlet of the second distillation column 6 is provided as follows.

The output of flow sensor 16 is provided to the input of square-root emitter unit 27, which provides linearity of the flow characteristic.

In the square root extraction unit 27, the liquid flow rate Q in the pipe 18 is calculated by the formula

Go

- flow coefficient, which accounts for the uneven distribution of velocities over the flow cross-section J

SQ is the cross-sectional area of the aperture of the first flow rate sensor 16; p is the density of the liquid

flow;

Rp is the pressure drop across the diaphragm measured by the first flow sensor 16. Since the density of the fluid flow p varies under real conditions, the flow rate Q is uniquely determined by the output signal of the first flow rate sensor 16.

The output, linear with respect to the measured flow rate, the signal of unit 27 is fed to the negative input of the inverting adder 28 and then to the valve 29 located on the pipe 30 for supplying distillate vapor to the second distillation column 6. The inverting adder 28 realizes the function

RO OUT

BX7

where Pg (,, and Pgj, output and input

the signals of the inverting adder 28; RO - reference signal. The use of the inverting adder 28 allows the variation of the steam flow rate through conduit 30 to be directly proportional to the flow rate of the fluid flow via conduit 18, despite the fact that the valve 29, according to safety conditions, is air closed.

Thus, when the flow rate of the liquid flow through the pipeline 18 changes, the valve 29 stroke is proportional to it, and since the pressure before and after the valve 29 is stabilized by the regulators 19 and 20, the flow rate of the steam flow through the pipeline 30 changes in proportion to the flow rate of the liquid flow pipeline 18.

The level control in the second reflux tank 8 is carried out as follows. The output signals of the setting device 33 and the second level sensor 31 are fed to the inputs of the second level controller 32, the output of which, in turn, affects the setting input of the second flow controller 34; The signal from the second flow sensor 35 also arrives at the input of the latter, the output signal of the second flow regulator determines the position of the valve 36. There are fluctuations

steam and liquid phase costs

at the inlet of the second distillation column, the distillation amount fluctuates on average from t 0.523 to + 10%. Accordingly, the amount supplied to the column

irrigation fluctuates by 18%. Job

51058569 6

With excessive irrigation leads to this system provides a reduction in energy costs in the amount of energy consumption for carrying out 80 1398380 kcal / h. Using the process.

Claims (1)

AUTOMATIC CONTROL SYSTEM OF RECTIFICATION COLUMN BLOCK, containing pressure regulators connected to valves on the supply lines of the upper products -. casing columns into condensers, product level regulators in reflux tanks, associated with flow controllers connected to flow sensors and valves on the lines for pumping liquid fractions from reflux tanks, a valve on the supply line of the upper product from the first column to the middle of the second column, characterized in that , in order to reduce energy costs for the process, the system further comprises a series-connected square root extraction unit and an inverting adder, and the liquid flow sensor tailcoat The flow coming from the first reflux tank to the second column is connected to the inlet of the square root extraction unit, and the output of the inverting adder is connected to the valve on the supply line of the top product from the first column to the middle of the second column. J □ o C & S