SU1281515A1 - Device for automatic control of ammonia synthesis process - Google Patents

Abstract

The invention relates to devices for automatically controlling the process of ammonia synthesis, can be used in the mineral fertilizer industry and improves the productivity of the process by preventing and eliminating emergency conditions. The device contains meters 2, 3 and 4 of the flow rate of the fresh mixture in the synthesis column, the flow rate for the upper and cold bypass, first

Description

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of which is connected with the divider (D) 13, and the other two with the second adder 12, meter 5 of the ammonia concentration in the mixture at the inlet of the synthesis column connected to one of the inputs of the second logic element 26, the other input of which is connected to D via a multiplier 18 -ChZ, the hot spot temperature former 6, associated with the field temperature meters 33 directly, through the bias element i O and the first adder 11 - with the third logic element 27, and through the first logic element 25 - with the indicator 16 connected by its output to one of the entrance From the first setter 22, the other inputs of which are connected to the inputs of the indicator 17 and the selective control unit 20, meter 7

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 the temperature of the mixture at the outlet of the ammonia evaporator, connected through regulator 8 to the valve 9 to supply liquid ammonia to the evaporator and to one of the inlets of the former 14 to concentrate ammonia in the circulating gas, the other inlet to the meter 29 of the mixture. The output of the imaging unit 14 through the matching element 15 is connected to the second input of the multiplier 18. The inputs of the second setting device 24 are connected to the outputs of the block 20 and the first setting device 22, and the output of the setting device 24 is connected via a limiter 21 to another input of the regulator 8. The temperature regulator 30 in the zone the reaction is connected with its input to the temperature gauge 32, and the output to the cold bypass valve 31. 1 il.

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The invention relates to devices for automatically controlling the process of ammonia synthesis and can be used in the mineral fertilizer industry in automating the operation of an ammonia synthesis column.

The purpose of the invention is to increase the productivity of the process by automatically warning and eliminating emergency conditions.

The drawing shows a functional diagram of the proposed device.

The device for controlling the mode of the process object 1 (the synthesis column and the ammonia evaporator are shown in the drawing) contains meters 2, 3 and 4, respectively, the flow rate of the fresh mixture into the synthesis column, the top bypass flow of the synthesis column and the cold bypass flow meter, the ammonia concentration 5 in the mixture at the inlet of the synthesis column, a shaper 6 is a hot spot temperature, a mixture temperature meter 7 at the outlet of an ammonia evaporator, a mixture temperature controller 8 at the outlet of the ammonia evaporator, a valve 9 and liquid ammonia in the evaporator element 10 biasing lane

ABOUT

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11 and second 12 adders, divider 13, shaper 14 of ammonia concentration in circulating gas, matching element 15, first 16 and second 17 indicators, multiplier 18, third adder 19, selective control unit 20, limiter 21, first setting unit 22 , fourth adder 23, second setter 24, first 25, second 26, third 27, fourth 28 logic elements, mixture pressure meter 29 after ammonia evaporator, temperature controller 30 in the reaction zone, cold bypass valve 31, temperature meter 32 in the reactor zone and and meters 33 t temperature floor columns.

The device works as follows.

Using meters 2, 3 and 4, the flow rates of the fresh mixture (F) are determined by the upper bypass of the column (V) and the cold bypass of the column (Vg). Using the second adder 12, the sum of Vj -bVg is determined. According to the meter 2 and the second adder I2, the ratio of the flow rate of the fresh mixture to the sum of the costs for the upper bypass of the column and for the cold bypass is formed using the splitter 13.

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Using the meter 5, the value x of the ammonia concentration at the point after the flow of the upper bypass of the synthesis column with the flow of the fresh mixture is shifted. Using a hot spot temperature generator 6, a hot spot temperature value t is formed equal to the highest temperature of the reaction at various points, and this value is fed to the inputs of the first logic element 25 and displacement element 10, the inputs of the first adder 1I, the fourth logic element 28 and selective adjustment unit 20. Using the output signal of the imager 6, the displacement element 10 is used to generate the value t corresponding to the phase-shifted temperature point of the point, and this value is fed to the inputs of the first adder 11 and the selective control unit 20. With the aid of the meter 29, the mixture pressure P is formed after the ammonia evaporator, which is fed to the inlet of the former 14. With the aid of the meter 7, the mixture temperature t is formed at the outlet of the ammonia evaporator, this quantity. served to the second input of the shaper I4 and to the input of the regulator 8. Using the shaper 14, the concentration of ammonia in the circulating gas after the ammonia evaporator is formed

х b + Ь t + Ь „t -t-b Р, 1 о 1 U g c 3

where are the coefficients.

The output value of the driver 14 is fed to the input of the matching element 15, where by compensating the delay .j through the channel the temperature t formed by the meter 7, the concentrations formed by the meter 5, form the value X - the concentration of ammonia in the stream V immediately before mixing the flow of Vo with the flow of adjacencies a mixture F. The characteristic of matching element 15 is set depending on the delay t. Therefore, in the limiting case, the element 15 can be an amplifying element with a unit gain factor, for example, when t o or in the system

Ie implemented on the basis of computing techniques 1 p1 quantization).

Noah Technician 1 at T L (UL - time

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Using the multiplier 18 form according to the divider 13 n according P F p

th element 1 5 the value of x g, -; G (x).

According to the shaper 6 and the element 10 form in the first adder 11 the difference between the temperature t and its phase-shifted value t, thus get the value (t-t). Using the first logic element 25, the temperature t is compared with the lower allowable limit H ,. If t H, a signal D is outputted at the input of the first indicator-16 and the inputs of the first setting unit 22 and the selective control unit 20, and with the help of the indicator 16 the dangerous state of the column is signaled.

With the help of the third logic element 27, the output signal (tt) of the first adder 11 is compared with the set threshold value t .. If t, a signal M is delivered to the input of block 20, to the input of the first setter 22 and to the input of the first indicator 16, while With the help of indicator 1b, the dangerous state of the column is signaled.

The first indicator 16 is turned on if there is at least one of the signals on any of the inputs and turns off when there are no signals on both inputs.

Using the fourth logic element 28, the temperature t is compared with the spacing formed in the fourth adder 23 between the set upper limit (B.) over this temperature and the constant K., - If, the third logic element 27 is turned on, otherwise the latter is turned off . Using the control loop containing the meter 7, the controller 8 and the valve 9 maintain the temperature t corresponding to the task for t supplied from the second setter 24 through the limiter 21 to the reference chamber of the regulator 8. At the same time, using the limiter 21, the reference signal is compared (3 t), supplied from the second setter 24, with the lower limit allowed Hi. The output signal of limiting l bodies 21 is equal to the larger signal from

values corresponding to 3 t. and h t.

 542

The second master 24 has a memory. With the disappearance of the signals at the inputs of the setting device 24, the task for t introduced earlier is maintained at its output. In the first setting unit 22, a temperature reference t is formed, corresponding to the normal operation of the column, which is fed to the second input of the second setting unit 24. The first setting unit 22 functions only in the absence of signals D and M | when the latter is detected, the first setting unit 22 is turned off and to the first input The second unit 24 is supplied with a signal generated in the selective regulation unit 20. In turn, the latter are only put into operation if there is a dangerous situation at the facility (the appearance of signals D or M, or D and M).

In the second logic element 26 form according to the meter 5 and

 R

multiplier 18 value x - x, which is compared with the limit x, corresponding to the passage of liquid amine

miak in the column. If the difference is, n

greater than x, produces a signal N, with which the second indicator 17 is turned on (liquid ammonia overrun alert), as well as by giving the signal N to the input of block 20 and the input of the first unit 22 blocking the perception by unit 20: And the unit 22 D and M 1 (i.e., the signal N cancels the signals ID and M and provides the possibility of the required changes of the 3t task using the setting device 22). The selective control unit 20 produces a temperature target t when the temperature t is above the limit H, + K ,, formed in the third cy of matte 19 and supplied to the input of block 20 (K is some constant), and while eliminating the dangerous decrease of the difference (tt -). Then, from the two tasks on t, the smaller one is selected and given to the first input of the second setter 24. In the normal process mode, the temperature t is controlled by varying the mixture supply through the cold bypass of the column, using the control loop, which includes the temperature controller 30 a reaction zone, a temperature gauge 32 in the reaction zone, and a cold bypass valve 31.

The use of the proposed device provides significantly

56

higher quality of temperature control in the synthesis column, which leads to a significant increase in the stability of the synthesis unit as a whole and an increase in its efficiency.

Claims (1)

Invention Formula An apparatus for automatically controlling the ammonia synthesis process, containing a meter and a temperature controller in the reaction zone of the synthesis column, the outlet of which is connected to the cold bypass valve, from the mixture temperature meter at the ammonia evaporator outlet, connected through its regulator to the liquid ammonia supply valve evaporator, temperature field meters of the column, two adders and a multiplier, characterized in that, in order to improve the performance of the process by automatically preventing and eliminating a variable modes, it additionally contains fresh mix flow meters into the synthesis column, top and cold bypass mixes of the synthesis column; ammonia concentration meter in the mixture at the synthesis column inlet; hot spot temperature former; displacement element; divider; ammonia concentration generator in the circulating gas , matching element, first and second indicators, third and fourth adders, selective adjustment unit, limiter, first and second setters, first, second, third and fourth logs The elements and the pressure meter of the mixture after the ammonia evaporator, while the mixture flow meters for the upper and cold bypass are connected to the first and second inputs of the second adder, the output of which is connected to the first divider input connected by its second input to the fresh mixture flow meter, and by the output to the first input of the multiplier, the temperature meters of the column are connected to the inputs of the hot spot temperature former, the output of which is connected in parallel to the input of the element; displacement and to the first inputs of the first and fourth logic elements, the first adder and the selective control unit connected to its 712 named by the second input with the output of the third adder, and the output with the first input of the second unit, the output of the displacement element is connected in parallel to the second input of the first adder and the third input of the selective control unit, the output of the first logic element is connected in parallel with the first inputs of the first indicator and the first setter and the fourth input of the selective control unit, the second input of the fourth logic element is connected with the output of the fourth adder, and the output is connected to the first input of the third logic edge ementa, its second input connected with the output of the first adder, the output of the third logic element is connected in parallel to the fifth input of the selective control and to the second inputs of the first setpoint and a first indicator, the multiplier output is connected to a first input of the second logic element. 158 the second input is connected to the ammonia concentration meter in the mixture at the synthesis column inlet, and the output is connected in parallel to the second indicator, to the third input of the first unit and the sixth input of the selective control unit, the mixture pressure meter after the ammonia evaporator is connected to the first input of the ammonia concentration generator the circulating gas, connected by its second inlet to the mixture temperature meter at the outlet of the ammonia evaporator, and the output through the matching element to the second inlet, multiply The output of the first setter is connected to the second input of the second setter, the output of which is connected to the second controller of the mixture temperature regulator at the outlet of the ammonia evaporator through a limiter, and the output of the temperature meter in the reaction zone is connected to the temperature controller in the reaction zone.