The method of automatic control of the process of obtaining formalin

 

(57) Abstract:

Usage: in the chemical industry for automation systems for the production of formalin. The invention is: to reduce specific consumption of methanol additionally measure the concentration of water, formaldehyde and methanol in commercial formalin, calculate the ratio of the concentrations of formaldehyde and methanol in commercial formalin and regulate the calculated concentration ratio with correction for temperature in the contact device by changing the coolant in spastically. The concentration of water in commercial formalin regulate the change of the flow of water in the wash column. 1 Il., table 1.

The invention relates to the field of automation of production processes and can be used in chemical industry for automation systems for the production of formalin.

There is a method of automatic control of the process of obtaining formalin by regulating the temperature of a contact layer of the device synthesis of modified additional air flow in biperiden spastically pipeline [1]

There is a method of automatic control of the process of obtaining formaline the change of the flow of methanol, regulation cost ratio of methanol and water supplied in spastically with correction for the density of the mixture at the entrance of certainareas, regulation of temperature in the contact device by changing the coolant in spastically and regulation of water flow in the wash column [2]

The known methods have limited ability to reduce specific consumption of methanol as low accuracy maintain the desired concentration of methanol in formaldehyde does not allow carry out the process close to the lower limit of its expenses.

The purpose of the invention, the reduction of specific consumption of methanol.

The use of the proposed method for automatic process control receiving formalin can improve the quality of commercial formalin, in particular to reduce the variance of the concentration of methanol in the product. The technological process can be conducted close to the lower boundary, consumption rates of methanol and thereby reduce its specific consumption.

This objective is achieved in that in the method of automatic control of the process of obtaining formalin, including the regulation of the level spartaaaaaa change feed him IU the h mixture at the inlet of certainareas, regulation of temperature in the contact device by changing the coolant in spastically and regulation of water flow in the wash column, optionally measure the concentration of water, formaldehyde and methanol in commercial formalin, calculate the ratio of the concentrations of formaldehyde and methanol in commercial formalin and regulate the calculated concentration ratio with correction for temperature in the contact device by changing the coolant in spastically. The concentration of water in commercial formalin regulate the change of the flow of water in the wash column.

The drawing shows a block diagram, in accordance with which the proposed method of automatic control.

The pipe 1 serves methanol in the mixer 2, in which the pipe 3 serves also water. Received sportowego mixture in line 4 serves in certainately 5. The pipeline 6 in certainately 5 serves coolant, and the pipeline 7 the air. The mixture of certainparts 5 is displayed on line 8 in the contact device 9. The reacted gases by pipeline 10 is served in the absorber 11, in which the pipe 12 serves also weak formalin. Commodity formalin DN 16 poor formalin. Exhaust gases from absorber 14 to the pipe 17 serves to wash the column 18, in which the pipe 19 serves also water. The residual exhaust gases by pipeline 20 is withdrawn on the torch. The control system includes a sensor 21 level, controller level 22, the actuator 23, a sensor 24, the temperature controller 25 temperature, the actuator 26, the sensor 27 consumption of methanol, the sensor 28 water flow rate sensor 29 density spirtovodnogo mixture, the controller 30 ratio, the actuator 31, the automatic analyzer 32 composition of formalin, the controller 33 of the water content, the actuator 34, the first block averaging 35, block 36 identification, block 37 calculation of the temperature of the contact apparatus, the second block averaging 38, block 39 delay.

The method of automatic control of the process of obtaining formalin is as follows.

Level spirtovodnogo mixture in spartaaaaaa 5 adjust the knob 22 to the signal from the sensor 21, acting on the actuator 23 to the pipe 1. The temperature in the contact device 9 is measured by the sensor 24 and adjust the regulator 25, acting on the actuator 26 to the pipe 6. Sensor 27 measures the flow rate of the methanol sensor 28 serostim 30 ratio, acting on the actuator 31 to the pipe 3. Analyzer 32 composition of formalin determine the concentration of formaldehyde, methanol and water in commercial formalin. Water consumption for irrigation leaching columns 18 regulate the regulator 33 of the water acting on the actuator 34 to the pipe 19. Continuous signal analyzer 32, which contains information about the concentrations of formaldehyde and methanol, is supplied in the first unit 35 of averaging, where the average value of the concentrations of formaldehyde and methanol for a fixed period of time and the formation of a discrete signal. Converted in this way the signal from the block 35 is passed to the block 36 identify where the current ratio is calculated concentrations of formaldehyde and methanol in formaldehyde. This ratio is calculated correction factors and0[n] and a1[n]

ao[n]ao[n-1]+ (1)

a1[n]a1[n-1]+ T[n-1] (2) where n is the number of the quantum control;

T[n-1] is the temperature of the contact apparatus, based on [n-1] quantum control;

Y[n] is the ratio of the concentrations of formaldehyde and methanol in formaldehyde [n] cycle management;

Yassthe specified value cogumelo coefficient and0on [n] and [n-1] ticks of the control, respectively.

a1[n] a1[n-1] values of the correction coefficient and1on [n] and [n-1] ticks of the control, respectively.

The signal from block 36, containing information about adjustment coefficients, enters the block 37 calculation of the temperature of the contact apparatus. Calculation of the temperature of the contact device carried by the formula:

T[n] (3)

The signal from block 37, which contains information about the calculated temperature value of the contact apparatus, is supplied as the reference input to the controller 25 temperature. From the sensor 24, the temperature of the continuous signal in the second block 38 of averaging, where the average value of the current temperature for a fixed period of time and the formation of a discrete signal. In block 39 of the delayed digital signal from the block 38 is delayed by the time required for completion of the transition process when installing a new job controller 25 temperature, and then fed to the input of block 36 identification. In order for the signal from the block 39 delay was entered in block 36 identification simultaneously with the signal of the next measure of control from the first block 35 averaging according to the algorithm (1, 2), production of the surveillance signal in the block 35 is equal to the time averaging of the signal in the block 38. Regulator 25 temperature signal from unit 37 sets the calculated value of the temperature in the contact device 9 by changing the coolant flow rate in certainately 5. Then again measure the concentration of formaldehyde and methanol in formaldehyde, calculate their ratio, adjust the coefficients and0[n] and a1[n] calculate the new temperature value and place it in the contact device 9 change coolant in certainately 5, and thus the regulation is carried out until until the current value becomes equal to Yass.

Technical implementation units 35, 36, 37, 38, 39 of the control system can be implemented on a control microprocessor controllers, for example, on the remikont P-110. As block 39 can be used to block lag ZAP (26), as blocks 35 and 38 blocks of calculating discrete medium DSM (29). Block 37 can be implemented as a series combination units summation SUM (30), and division of CASES (33). As block 36, which implements the algorithm (1, 2), can be used in an appropriate combination of units summation SUM (30), multiplication mult (32), and division of CASES (33).

For ex the ol with a flow rate of Qm=1786 kg/h in the mixer 2, in which the pipe 3 has also filed demineralized water for mixing with a flow rate of Qcm=765 kg/h In the mixer 2 was produced a mixture of methanol and water in the ratio of 70:30. Received sportowego mixture in line 4 was filed in certainately 5, where he carried out its evaporation by heating to a temperature TSP=125aboutWith the heat carrier, which filed spastically 5 via the pipeline 6. In the upper part of certainparts 5 mixed evaporated sportowego mixture with air, which is supplied by the blower through the pipe 7 with a flow rate of Qin=1960 m3/H. the Obtained alcohol-water-air mixture was supplied by a pipe 8 in the contact device 9, in which passerinum catalyst flow the following main reactions:

CH3OH ___ CH2O+H220 kcal/mol

H2+0.5 O2___ H2O+58 kcal/mol

CH3OH+0.5 O2___ CH2O+H2O+38 kcal/mol

The reacted gases by pipeline 10 has applied to the absorber 11, in which the pipeline 12 filed weak formalin. Commodity formalin through the pipeline 13 was taken to the warehouse. In the absorber 14 through the pipeline 15 filed exhaust gases from absorber 11, trubo pipeline 19 have also filed demineralized water for irrigation with a flow rate of Q'or= 570 kg/h Of leaching column 18 of the residual exhaust gases were supplied by a pipe 20 to the torch. Level spirtovodnogo mixture in spartaaaaaa 5 was maintained constant L=50% by measuring sensor 21 ("Sapphire-22" 1) and regulation controller 22 (algoblock RAS (01) ramakanta R-110) level spartaaaaaa the change of the flow of the methanol valve 23 in the pipe 1 into the mixer 2. If a positive deviation in spartaaaaaa from the set Lass= 50% consumption of methanol was reduced with a negative deviation increased. The temperature in the contact device 9 T[n]700aboutWith measured sensor 24 (thermocouple THA) and regulated by the regulator 25 (algoblock RAS (01) R-110) by changing the coolant valve 26 in the pipe 6 in certainately 5. At positive temperature deviation in the contact device from the set Tass=700aboutWith the coolant flow in certainately increased, with a negative deviation decreased. Sensor 27 ("Sapphire-22" 2) on the pipe 1 was measured consumption of methanol Qm=1786 kg/h, the sensor 28 ("Sapphire-22" 3) on the line 3 measured water consumption for mixing of Qcm=765 kg/H. the Relation of these costs are maintained constantly in proportion Q3by changing the water supply to the mixing valve 31 in the pipe 3. If a positive deviation of the ratio of methanol-water from a given ratio of Gass=70/30 flow of water in the mixture was increased, with a negative deviation decreased. If a positive deviation of the density of the alcohol-water mixture from the specifiedass=880 kg/m3the supply of water to the mixture decreased, with a negative deviation increased. The air flow coming through the pipeline 7 in certainately 5 during the experiment remained constant Qin=1960 m3/h as the speed of the blower was not regulated. The water concentration of CH2Oh, methanolm, formaldehydefin commercial formalin was measured after absorber 11 automatic analyzer 32 composition of formalin (automatic chromatograph "Neftekhim-qualified electronic signature certificate"). The amount of water in the formalin was maintained at the specified level (CH2ABOUTass=56%) by controlling the flow of water to the irrigation controller 33 water content (algoblock RAS (01) R-110) change in the supply of water for irrigation leaching columns 18 valve 34 in the pipe 19. If a positive deviation of water content in the formalin from the set SN2Aboutassthat took the ratio of these concentrations before the start of the experiment Yass= Yn= 4,8, initial contact temperature Tbut=700aboutWith was sharply reduced by 10aboutWith up to Tn=690aboutS, i.e. created artificial disturbing effect on temperature T=-10aboutC. Continuous signal analyzer 32 composition of formalin, which contains information about the concentrations of formaldehyde WITHfand methanol WITHmwere entered in the first block averaging 35 (algoblock computing discrete medium DSR (29) P-110), which was the average value of concentrations of formaldehyde WITHfand methanol WITHmfor a fixed period of time1= 30 minutes Converted so from analog to digital signal from the block 35 is received in block 36 of identification, which is a combination of algoblock ramakanta P-110 that implement the algorithms for the calculation of correction factors and0[n] a1[n] (1, 2). In algoblock division TEL (33) was calculated current ratio of the concentrations of formaldehyde and methanol in formaldehyde Y[n] Cf/Sm(n stroke control). On algoblock SUM (30), SUM (30), SUM (30), UMN (32), DEL (33) were calculated value andassorder rapid stabilization of the current ratio at a specified level. The signal from block 36, containing information about adjustment factors were entered in block 37 of the calculation of the temperature. Calculation of the temperature of the contact device carried by the formula (3) Algologie SUM (30) and DEL (33). The signal from block 37, which contains information about the calculated temperature value of the contact apparatus was applied as the reference input to the controller 25 temperature. From the sensor 24, the temperature of the continuous signal received in the second block 38 averaging (algoblock DSR (29) P-110), which was the average value of the current temperature in the contact apparatus T[n] for a fixed period of time2=30 min and the formation of a discrete signal. In block 39 delay (algoblock ZAP (26) R-110) discrete signal from the block 38 was delayed for a time3=1.5 hours needed to complete the transition process when installing a new job controller 25 temperature. In blocks 35 and 381= 2to synchronize the operation of the system, i.e. to the signal from the block 39 delay was entered in block 36 identification simultaneously with the signal of the next measure from the block averaging 35. For the same purpose and programmable limit the second calculated value of the temperature in the contact device 9 by changing the coolant flow rate in certainately 5. If a positive deviation newly calculated temperature of the contact device from the temperature calculated in the previous step of the control flow in certainately decreased, it caused a decrease in the concentration of methanol in the reaction mixture, quenching of the reaction of dehydrogenation of CH3HE>> CH2O+H220 kcal/mol and as a result, the temperature increase of the contact device to the newly calculated. Negative deviation newly calculated temperature from the temperature calculated in the previous step of the control flow in certainately increased, it caused an increase in the concentration of methanol in the reaction mixture, the amplification reactions of dehydrogenation and consequently reducing the temperature of the contact device to the newly calculated. Once this was measured concentrations of formaldehyde WITHfand methanol WITHmin formalin, was calculated their ratio Y[n] adjusted coefficients and0[n] and a1[n] was calculated new value and temperature were installed in the contact device 9 change coolant in certainately 5, and thus the regulation was carried out until pokolenia not given appropriate levels of signals between the units, the value of the current ratio Y[n] correction factors and0[n] a1[n] and the calculated temperature of the contact device, as remikont R-110 is not an indicator, i.e. it has no hardware display internal information. Therefore, the system was controlled using input and output parameters. The input parameters were considered constant: level spartaaaaaa L=50% consumption of methanol Qm= 1786 kg/h water flow to the mixing of Qcm=765 kg/h, the ratio 70:30, density = 880 kg/m3temperature certainareas TSP=125aboutWith the amount of air Qin= 1960 m3/h, consumption of water for irrigation Q'or=570 kg/h, and variables: concentrations of formaldehyde WITHfand methanol WITHmthe temperature of the contact apparatus in the previous stage management T[n-1] To the output parameters was assigned the temperature of the contact device on the n-th quantum control T[n] are the input and output parameters described above for experiment 1 are presented in the table. The table also presents the results of experiments 2 and 3, which were conducted similar to the first, but with other values of the input and output parameters, and to compare data with normally the itzá ratio formaldehyde methanol Y[n] due to the above reasons the calculated manually.

The METHOD of AUTOMATIC control of the PROCESS of OBTAINING FORMALIN, including the regulation of the level spartaaaaaa the change of the flow of methanol, regulation cost ratio of methanol and water supplied in spastically with correction for the density of the mixture at the outlet of certainareas, regulation of temperature in the contact device by changing the coolant in spastically and regulation of water flow in the wash column, wherein, to reduce specific consumption of methanol, optionally measure the concentration of water, formaldehyde and methanol in commercial formalin, calculate the ratio of the concentration of formaldehyde and methanol in commercial formalin and regulate this ratio is calculated concentration with correction for temperature in the contact device by changing the coolant in spastically, and the concentration of water in commercial formalin regulate the change of the flow of water in the wash column.

 

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