SU1341211A1 - Device for checking parameters of converter process - Google Patents

Abstract

This invention relates to the field of controlling an oxygen converter process. The purpose of the invention is to determine the decarburization rate in the converter bath. The essence of the invention is that the device, by means of a set of blocks and connections between them, calculates the decarburization rate (V |.) According to the following formula: V (.0.169 ".) JP, f, - 0.536-K-4, where. and v |. - respectively, the volume of the caisson and the lifting duct; P, is the amplitude of gas pressure oscillations in the gas duct; f, is the frequency of gas pressure fluctuations in the gas duct; K is the proportionality coefficient determining the flow rate of air drawn into the gas duct; tff is the vacuum in the lower part of the caisson. The value of JP is determined by a set of elements: pressure sensor 1, amplifier 4, differentiation unit 12, delay unit 18, adder 19. The value 0.536-K-rfJ, is determined by pressure sensor 21, multiplication unit 24. The value of f is determined by pressure sensor 1, amplifier 4, filter 5, AGC block 6, mixer 7 with local oscillator 8, filter 9, amplifier 10, detector P. 1 Cp. f-ly, 2 ill. c & (L

Description

one

FIELD OF THE INVENTION The invention relates to ferrous metallurgy, in particular to the management of an oxygen converter process. The purpose of the invention is to determine the decarburization rate in the bath of the converter.

FIG. I shows a diagram of the device j in FIG. 2 is a logic block diagram.

The device (Fig. 1) contains a first pressure sensor 1 connected to a sampling device 2 installed in a duct 3, connected via a preamplifier 4, a low-pass filter 5, an automatic gain control unit 6 to a mixer 7, which is also connected to the local oscillator 8 The output of the mixer 7 is connected via a band-pass filter 9, an amplifier 10 with a detector I. The pre-amplifier 4 is connected through a differentiation unit 12 to a logic unit 13 and directly to the first and second blocks 14, 15 of the memory. The second input of the first memory block 14 They are connected via the first AND block 16 to the first output of the logic unit 13, and the second input of the second memory block 15 is connected via the second AND block 17 to the second output of the logic block 13. The second inputs of the first and second AND blocks 16, 17 are connected through the block 18 delays with the third output of the logic unit 13. The outputs of the first memory block 14 and the second memory block 15 are connected via a first adder 19 to a first multiplication unit 20, which is also connected to detector P. A second pressure sensor 21 connected to a sampling device 22 installed in the gap between converter mouth 23 and the gas duct 3 is connected via a second multiplying unit 24 to the second adder 25, the second input of which is coupled to the output of the first multiplying unit 20, and output - with the indication unit 26. Logic unit 13 (FIG. 2) contains interconnected dual-channel signaling unit 27 and comparison unit 28, the first and second outputs of the signaling unit 27 being the first and second outputs of the logic unit, and the output of the comparison unit 28 is its third output.

As pressure sensors 1 and 21, standard Sapphire-22DI pressure gauges can be used.

ten

15

 . 25 12112

amplifiers, blocks of memory can be made on the basis of devices for sampling and storing analog signals of IC KR1100SK2, blocks And and delays - on standard blocks of computing equipment, the remaining blocks can be made on the basis of standard blocks AKESR.

The decarburization rate of the liquid bath is characterized by the presence of pulsation. The pulsating nature of the decarburization process leads to a change in the pressure of the gases in the cavity of the converter, which is transmitted through the gas exhaust path.

According to the first law of thermodynamics.

,

(one)

where jq is the amount of heat reported

working body, J; whether - the change in internal energy

working fluid, J. On the other hand, the heat dissipation in the system during one cycle of oscillations can be defined as

.Q -. , (2)

where q is the specific heat of combustion

fuels (for gaseous under normal conditions of J / m);

V - mass fuel consumption, kg / s; f - pressure oscillation frequency

gas, Hz.

According to the theory of classical statistics of Maxwell, the change in the internal energy of a gas can be determined by the formula

whether - i .R-JT, (3) f. d

where m is the mass of gas, Krj

 - molar mass of gas, kg / mol; i - taking into account the vibrational number of degrees of freedom of motion of one gas molecule; LT - change in gas temperature, K; R is a universal gas constant, equal to 8314 J / kmol-K. In describing the state of real gases at low pressures and high temperatures, as is the case in the oxygen-converting process, the Mendeleyev – Clapeyron equation can be used:

PV

PC,

(four)

31341

where lR is the amplitude of pressure fluctuations

gas, Pa;

V is the gas volume, m. Using relations (l) - (4), we obtain the expression for the amplitude of gas pressure fluctuations:

AP-rvTf

(five)

In the oxygen-converting process, the formation of gas during the purge takes place in the retort and gas duct. The length of the path at which complete molar mixing of the converter gas with the drawn in air occurs is approximately ten times the diameter of the converter neck. Therefore, the most reliable amplitude-frequency characteristic of the exhaust gases is controlled in the upper part of the lifting duct,

Considering that during the converter purging only carbon-containing gases CO and COj are released, the expression (5) can be converted:

. .

one

2q ..r from 12 to Oso

one

Uso

with d d t:

(6) 30

35

“2

e yP, JP2 - amplitudes of gas pressure oscillations in the upper

part of the lifting duct and the partial pressure of carbon dioxide from the burning of carbon monoxide. Pa;

 - the volume fraction of carbon dioxide from the combustion of converter gases; q is the specific heat of combustion of carbon monoxide from

burn out converters

45

gases under normal conditions, - equal to 127 105 J / m;

carbon mass flow rate of the bath or its decarburization rate, 50 kg / s;

the degree of oxidation of carbon to CO in the cavity of the converter, defined as the volume fraction of carbon monoxide 55 in 1g converter gases;

taking into account the number of degrees of freedom

0

5 o

211

the movement of one molecule of carbon dioxide is equal to 8;

V, V |. - the volume, respectively, of the caisson and the lifting duct,

f is the frequency of gas pressure oscillations in the upper part of the lifting duct, Hz.

The value of v is defined as the ratio of the values of carbon dioxide consumption from the combustion of converter gases K-, the sum of consumption of carbon-containing converter gases and sucked air, which is assumed to be proportional to the negative pressure in the lower section of the caisson:

 Tso

(7)

25

thirty

35

-

45

50

55

where K is the proportionality coefficient, which determines the flow rate of air drawn in under normal conditions, depending on the vacuum in the lower section of the caisson, (c.Pa); "/ P - vacuum in the lower section

caisson. Pa.

Solving expressions (6) and (7) with respect to the value of V, we get:

, 169-10 () P, - f, -0,

The device works as follows.

Since the start of the purge, the signal on gas pressure in the duct 3, sensed by sensor 1, is amplified in preamplifier 4. The signal then passes through a low-pass filter 5, which selects a spectrum of frequencies corresponding to the resonant frequency of the free gas duct. From the output of the low-frequency filter, the signal is fed to the input of the automatic control unit 6 of force j at the output of which a constant amplitude signal with a resonant frequency spectrum is obtained. The mixer 7 receives a signal from the output of the automatic gain control unit 6 and the signal produced by the local oscillator 8. The frequency difference of these signals passes through a band-pass filter 9, is amplified by the amplifier 10 and is converted by the frequency detector 11 into a signal, proportional to

national frequency of pressure fluctuations in the gas duct. The signal from preamplifier 4 enters differentiation unit 12, from the output of which to the first input of the first channel and the second input of the second channel of the signaling unit 27 and to the first input of the comparison unit 28. At the same time, a reference voltage equal to zero (s) is applied to the second input of the first channel and the first input of the second channel of the signaling unit 27. If the signal at the first input of one of the channels of the signaling unit 27 exceeds the signal supplied to its second input, then a signal corresponding to unity (otherwise, zero) appears at the channel output. Thus, at the first output of logic block 13, a single signal appears when the signal at its input is above zero, and zero if the signal at the input is below zero. At the second output of logic unit 13, a single signal appears when the signal at its input is below zero, and S left, if the signal at the input is higher than zero. A single signal at the output of comparator unit 28 (the third output of logic unit 13) appears only when the input signal coincides with the zero reference signal and through the delay unit 18 arrives at the second inputs of the first 16 and second 17 blocks I. The presence of two single signals at the inputs of the first And 16 allows you to receive a single signal from its output, which is fed to the second input of the first memory block 14 and allows recording of the signal from the preamplifier 4 to the first input of the first memory block 14. Similarly, the presence of single signals at the inputs of the second block AND 17 permits the recording of the signal from the preamplifier 4 to the second memory block 15. Consider the case when the gas pressure value in the flue reaches a maximum value. At this moment, the signal from preamplifier 4 to differentiation unit 12 reaches its maximum value, and from the output of differentiation unit to logic unit 13 a signal equal to zero arrives. From the third output of the logic block to the block 18 of the delay receives a single signal. With

five

21 I

when the pressure value passes through the maximum value, the signal arriving at differentiation unit 12 decreases, and from the output of differentiation unit to logic unit 13 a signal arrives below zero, which leads to the appearance of a zero signal at the first output of logical unit Q and unit second exit. Thus, after the delay time, the first and second inputs of the first block AND 16 receive, respectively, zero and single signals, and the inputs of the second block, AND 17, single signals, which permits a new value corresponding to the maximum gas pressure in the second block 15 to be recorded. gas duct. Similarly, upon reaching the minimum value of the pressure, single signals appear at the inputs of the first AND 16 block, which allows fixing in the first

g block 14 of the memory value corresponding to the minimum pressure of gases in the flue duct. The voltage from the outputs of the first 14 and second 15 memory blocks is summed up in the first adder 19. From the last output, the voltage proportional to the amplitude of gas pressure fluctuations in the upper part of the lifting duct enters the first multiplication unit 20, which also receives the voltage from the detector eleven,

35 proportional to the frequency of pressure fluctuations in flue gases. A numerical factor proportional to the expression 0.5-0, 169-10 (V t- + Vr) is set as the constant doubler in the first adder 25. Thus, the voltage supplied to the second adder 25 is proportional to the expression O, 169 -Y () f. Gas pressure signal at the exit from

5, the converter from the sensor 21 is fed to the second multiplication unit 24, in which the product of 0.536K s / p is calculated, which enters the second adder 25. The decarburization rate is calculated 50 in the adder 25 according to expression (8) and fixed by the indication unit 26.

Example. Determination of the decarburization rate in a 130-ton conter with oxygen blowing from the top and afterburning of converter gases. Dp of this converter installation value of the coefficient of proportionality, 93 (s. Pa), geometric

0

713412

factors equal V -37 m, m-. The values of the variables measured at the time the 50% of the total amount of oxygen to be melted into the bath are equal to f 5 Hz in the region of the resonant oscillations of the gas; , 72 () Pa. The magnitude of the vacuum in the lower section of the caisson is c / p 20 Pa. After substituting data into expression (8), we get:

, 169 10 (37 + 209) 0, 72 10 5- -0.536-0.93-20 4.97 (kg / s).

ten

A test of the layout showed that the use of a decarburization rate determination device in the converter bath allows the process to be controlled with higher accuracy (the number of heats within the specified limits increases from 5 to 7% from the first roll), which reduces the cost of steel and improves its quality.

Claims (2)

1. A device for monitoring parameters of a converter process, comprising a series-connected preamplifier, a low-pass filter, an automatic gain control unit, a mixer connected to the local oscillator, a band-pass filter, an amplifier and a detector, an indication unit, characterized in that whith decarburization in bath envelope 0 g Q five 0 18 It is equipped with two pressure sensors, a differentiation unit, a logic unit, a delay unit, two AND blocks, two memory blocks, two adders and two multiplication blocks, the preamplifier being connected through the differentiation unit with the logic unit and directly memory, the second inputs of which are connected through the first and second blocks AND, respectively, with the first and second output of the logic block, while the second inputs of the first and second blocks AND are connected via a delay block with tert the output of the logic block, and the outputs of the first and second memory blocks are connected via the first adder to the first multiplication unit, the second input of which is connected to the detector output, and the output of the first multiplication unit is connected to the second adder, the second input of which through the second multiplication unit is connected to the second a pressure sensor and an output with an indication unit; the output of the first pressure sensor is connected to a preamplifier. 2. A device according to claim 1, characterized in that the selective element of the first pressure sensor is installed in the duct. and a selective pressure sensor of the second pressure sensor is installed in the gap between the converter throat and the gas duct. fi 2 Compiled by A.Abrosimov Editor M.Tsitkina Tehred M.Hodanich 4402/31 Circulation 549Subscribe VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 Projector P.Iilipenko