CN101149616A - Propylene oxidation unit DCS control system in crylic acid device - Google Patents
Propylene oxidation unit DCS control system in crylic acid device Download PDFInfo
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Abstract
This invention discloses a kind of propylene oxidize unit DCS automation system in the crylic acid device which sets up the fresh propylene enter material flux automation system, the fresh air enter material flux automation system, vapor flux automation system, circle off-gas flux automation system, and sets up a minim water analyzer, oxygen content analyzer, propylene content analyzer, the control house setting up a DCS makes the output information of fresh propylene flux into the DCS as the main momentum signal and makes the vapor, fresh air, circle off-gas into the reactor flux signal and then into the DCS as the momentum signal all of them above composes the flux mixture ratio control system and the output signals of every analyzer enter the DSC and take part in the calculus; the merits of this invention are that uses the propylene material well and matches the vapor, the use level of oxygen, the use level circle off-gas reasonably and in the operation state concludes catalyst, temperature, pressure and so on the same state used in reactor that can reduce the manufacture cost and increase the yield and enhance the outcome 0.5 to 2 percent and ensure the operate security.
Description
Technical field
The present invention relates to the technological process automatic control system in a kind of acrylic acid production.
Background technology
The propylene two-step oxidizing process is produced acrylic acid technology, mainly is to be raw material with propylene, air, issues angry phase oxidation reaction in the catalyzer condition.Oxidizing process is finished in two steps, at first is that propylene oxidation generates acryl aldehyde, and the further oxidation of acryl aldehyde generates acrylic acid.Reaction equation is as follows:
CH
2＝CH-CH
3+O
2→CH
2＝CH-CHO+H
2O+0.34MJ(80kCal)
CH
2＝CH-CHO+1/2O
2→CH
2＝CH-COOH+0.25MJ(60kCal)
Because this process is the strong oxidation reaction of heat release, temperature of reaction is higher, for satisfying catalyst performance and production-scale requirement, need keep higher material concentration.Therefore, propylene and oxygen mixture are operated in the scope near explosion limits, if can not strictly control each technological parameter, there is the potential danger of blast at any time in system.In addition, high performance catalyzer also has comparatively strict restriction to the raw material proportioning, and when having only the raw material proportioning to reach best proportioning point, catalyst performance just can farthest be brought into play.Therefore, the control of the precision process of course of reaction has determined the security and the economy of a whole set of technology.
In acrylic acid production device in the past, examined control device restriction, the raw material proportioning in the production run is by operating personnel's manual adjustments, controls each input concentration in a metastable scope; To influence the proportioning parameters calculated in order reducing, generally not adopt the reaction end gas circulation technology, but, suppress the generation of blast by in reaction mass, directly adding the concentration of the method conditioned reaction gas of water vapour.But too much water vapour adds steam consumption is increased, also directly influenced the serviceable life of catalyzer, cause rear portion acrylic acid refining system separation costs to increase.
At this problem, present acrylic acid oxidation technology is improved, and the first will be circulated back to reactive system through the reaction end gas after burning with the many employings of course of reaction, substitutes part steam and regulates density of propylene as the diluents of course of reaction; Another process route be with reaction end gas without burning disposal, be recirculated directly back to reactive system, this technology had both reclaimed propylene, and had eliminated because of the influence of CIU operation fluctuation to oxidation reaction process, operated more steady.
Summary of the invention
The objective of the invention is to overcome the deficiency of prior art,, provide the automatic control system of propylene oxidation unit in the cover acrylic acid production at will directly not looping back the most up-to-date techniques route of reactive system through the reaction end gas of burning disposal.
Because the increase of entrained composition in recycled offgas and the tail gas, impact the also corresponding increase of factor of reaction ratio and reaction blast area scope, need to introduce the computing of more technological parameter participation system, the performance variable that relates to is regulated 23 of technology by open steam and is increased to 33, consider the corrected parameter of introducing, the technological parameter that participates in calculating reaches 60 more than.Therefore, in the DCS configuration process of device, take into full account the mutual relationship between each parameter, and each parameter is to the influence mode and the degree of technological process, these relations are established with the explicit mathematical expression formula, the DCS system just can realize the plant automatic control of process of multiplex (MUX) accurately, reposefully like this, guarantee course of reaction steadily, orderly function.
The acrylic acid technological process is produced in the propylene two-step oxidation: steam, recycled offgas, fresh air enter mixer M-2 again and fully mix with the fresh propylene charging, as the first reactor R-1 charging after advancing premixer M-1 mixing.In the first reactor R-1, propylene and airborne oxygen carry out oxidation reaction and generate third rare aldehyde.First reactor outlet gas enters second reactor and continues the generation oxidation reaction with after the fresh air that replenishes mixes in the second reactor R-2 entry mixers M-3, makes third rare aldehyde further be converted into acrylic acid.The control system of this technological process is characterised in that:
Be provided with FC-1006 fresh propylene feed rate automatic control system, its flow detecting element, variable valve are located on the fresh propylene pipeline of first reactor (R-1) entry mixers M-2, the flow transmitter output signal of FC-1006 system is advanced pulpit DCS and is participated in the proportioning computing as master variable as the active amount signal of flowrate proportioning system;
Be provided with FC-1004 fresh air feed rate automatic control system, its flow detecting element, variable valve are located at fresh air and advance on the pipeline of premixer M-1, the flow transmitter output signal of FC-1004 system as the flowrate proportioning system from one of momentum signal, advance pulpit DCS, participate in computing;
Be provided with FC-1009 steam flow automatic control system, its flow detecting element, variable valve are located at steam and advance on the pipeline of premixer M-1, the flow transmitter output signal of FC-1009 system, as the flowrate proportioning system from one of momentum signal, advance pulpit DCS, participate in computing;
Be provided with FC-1021 recycled offgas automatic flow control system, its flow detecting element, variable valve are located at recycled offgas and advance on the pipeline of premixer M-1, the flow transmitter output signal of FC-1021 system, as the flowrate proportioning system from one of momentum signal, advance pulpit DCS, participate in computing;
Be provided with FC-1012 fresh air feed rate automatic control system, its flow detecting element, variable valve are located on the fresh air pipe of the second reactor R-2 entry mixers M-3, the flow transmitter output signal of FC-1012 system as the flowrate proportioning system from one of momentum signal, advance pulpit DCS, participate in computing;
The variable valve of FC-1006 system receives the output signal of FC-1006 system among the DCS;
The variable valve of FC-1004, FC-1009, FC-1012, FC-1021 system receives the DCS output signal work that results in automatically;
Be provided with AI-1003 water microanalysis instrument, detect the liquid water content of fresh air, its output signal is delivered to DCS in the pulpit;
Be provided with AI-1006 oxygen content analyser, detect the oxygen content of circulating air, its output signal is delivered to DCS in the pulpit;
If AI-1007C
3Content analyzer, the C of detection recycled offgas
3Content, its output signal is delivered to DCS in the pulpit;
More than three kinds of analyser detection signals input DCS participate in proportionings and calculate, can accurate more steam regulation, the inlet of air, recycled offgas, result of calculation can reflect actual proportion relation more.
Characteristics of the present invention are according to the actual feed rate of propylene, automatically be equipped with steam, air, the recycled offgas of fixed ratio, automatically regulate in real time according to the actual feed rate of propylene owing to realized steam, air, recycled offgas flow, reduced artificial interference, operation safe is stable.
By adopting advanced DCS control system, under equal catalyzer and same operation condition, it is about 0.5～2% to improve the acrylic acid yield, and economic benefit is very considerable.
Description of drawings
Fig. 1 is the propylene oxidation unit schematic flow sheet.
Fig. 2 transmits, calculates and concern synoptic diagram for signal of the present invention.
Fig. 3 be in the production run operating point at DCS System Monitor display image.
Fig. 4 is in startup procedure, operating point variation track image.
Fig. 5 is in docking process, operating point variation track image.
" one is anti-", " two is anti-" are the abbreviation of first reactor, second reactor among the figure.
Reactor blast area boundary line
--------reactor suffocates and distinguishes the lower limit line
* operating point
Embodiment
Below in conjunction with the drawings and specific embodiments the present invention is made detailed description further.
To produce 80000 tons of acroleic acid device propylene oxidation units per year is example, adopts DCS control, sets forth situation of the present invention.
Steam is measured flow through orifice plate, differential pressure transmitter; Air is measured flow through Annubar, differential pressure transmitter; Recycled offgas is measured flow through orifice plate, differential pressure transmitter, and the three advances premixer M-1 altogether, and fresh propylene is gone into entry mixers M-2 after flow measurement, advance mixer M-2 with fresh propylene again after the mixing, advances the first reactor R-1 again; Reaction gas behind first reactor reaction is gone into entry mixers M-3, replenishes and enters the second reactor R-2 after the air mixed and carry out further oxidation reaction with second reactor after measuring flow through Annubar, differential pressure transmitter.
One, fundamental operation and adjusting
1. proportioning computing
Signal transmission and calculation process in the DCS running of the present invention, as shown in Figure 1.
(1) basic calculating
This process is with the table measurement of discharge of each burst charging, the following computing formula of parameter substitution such as component concentration of on-line analysis instrument, gets each the component actual flow that enters reactor up till now.
One anti-propylene flow rate calculation B1=B+E*V/1000kg/h
One flow rate calculation H=C+D*A/ (the 1000+A)+E*Y/1000kg/h that turns one's coat
One anti-air mass flow is calculated I=D*1000/ (1000+A)+E*Z/1000kg/h
One anti-indifferent gas flow calculates J=E (1-Y-Z-V)/1000kg/h
Two anti-air mass flows are calculated K=F*1000/ (1000+A) kg/h
(2) proportioning is calculated
Each component charging of reactor should be followed strict proportion relation in this technology, and the charging proportioning that provides as certain catalyzer supply merchant is:
PP∶H
2O∶O
2 1ST∶INT∶O
2 2ND＝1∶1∶1.7∶2.4∶0.5
Wherein:
PP---the first reactor inlet propylene amount
H
2O---the first reactor inlet quantity of steam
O
2 1ST---the first reactor inlet amount of oxygen
INT---the first reactor inlet circulation inertia tolerance (not comprising air, propylene and water)
O
2 2ND---the second reactor inlet amount of oxygen
This ratio is each the feed component mol ratio that requires, when carrying out the calculating of charging proportioning, at first the assumed load by device calculates required propylene feed amount " W1 " (carrying the propylene amount comprising circulating air), calculates an anti-steam flow, an anti-air mass flow, an anti-recycled inert gaseous stream amount and two anti-air mass flows respectively according to desired proportion relation again.Wherein:
One anti-steam flow calculates: M=(W1/MWPP) * 1.0*MWMP kg/h
One anti-air mass flow is calculated: N=(W1/MWPP) * 1.7/0.21*MWA kg/h
One anti-circulating air flow calculates: O=(W1/MWPP) * 2.4*MWINT kg/h
Two anti-air mass flows are calculated: P=(W1/MWPP) * 0.5/0.21*MWA kg/h
After calculating each composition flow rate that enters reactor, just can calculate the flow setting value of each charging control system of reactor by following relational expression:
One anti-steam control system FC-1009 flow set R=M-(H-C) kg/h
One anti-air control system for air FC-1004 flow set S=(N-E*Z/1000) * (1000+A)/1000kg/h
One anti-circulating air control system FC-1021 flow set T=O/ (1-(Y+Z+V)/1000) kg/h
Two anti-air control system for air FC-1012 flow set U=P* (1000+A)/1000kg/h
Symbolic interpretation such as table 1:
Table-1
| Symbol | Symbolic significance | The source | Unit | Remarks |
| A | Air humidity | Measured value | g/kg | Butt |
| B | Fresh PP to M-2 | Measured value | kg/h | ＊1) |
| C | MPS to M-1 | Measured value | kg/h | ＊1) |
| D | Air is to M-1 | Measured value | kg/h | ＊1) |
| E | Circulating air is to M-1 | Measured value | kg/h | ＊1) |
| F | Air is to M-3 | Measured value | kg/h | ＊1) |
| B1 | To an anti-actual propylene flow | Calculated value | kg/h | |
| H | To an anti-actual discharge | Calculated value | kg/h | |
| I | To an anti-actual air flow | Calculated value | kg/h | Butt |
| J | To an anti-actual indifferent gas flow | Calculated value | kg/h |
| K | To two anti-actual air flows | Calculated value | kg/h | Butt |
| W1 | The actual production load | Calculated value | ％ | |
| Q | Device is the propylene flow at full capacity | Design load | kg/h | |
| M | To the flow setting value of turning one's coat | Calculated value | kg/h | |
| N | To an anti-air mass flow setting value | Calculated value | kg/h | |
| O | To an anti-indifferent gas flow setting value | Calculated value | kg/h | |
| P | To two anti-air mass flow setting values | Calculated value | kg/h | |
| W | FC-1006 propylene flow setting value | Input value | kg/h | |
| R | FC-1009 steam flow setting value | Calculated value | kg/h | |
| S | FC-1004 air mass flow setting value | Calculated value | kg/h | |
| T | FC-1021 circulating air flow setting value | Calculated value | kg/h | |
| U | FC-1012 two anti-air mass flow setting values | Calculated value | kg/h | |
| Y | The circulating air water cut | Calculated value | g/kg | ＊2) |
| Z | Circulating air contains air capacity | Calculated value | g/kg | ＊3) |
| V | Circulating air C 3Content | Calculated value | g/kg | ＊4) |
Annotate:
1) through temperature, the revised flow of pressure compensation.
2) the circulating air saturated humidity is calculated by following formula:
Y＝Y1＊Y2/Y3＊1000
Symbolic significance
Moisture rate (saturated) V/V of Y1---circulating air under 60 ℃ of temperature
Y2---molecular weight water kg/kmol
Y3---circulating air mean molecular weight kg/kmol
3) circulating air contains air capacity and is calculated by following formula
Z＝Z1/100/Z2＊Z3/Z4＊1000
Symbolic significance
Z1---O in the circulating air
2Concentration mol%
Z2---O in the air
2Concentration V/V
Z3---air mean molecular weight kg/kmol
Z4---circulating air mean molecular weight kg/kmol
4) circulating air contains C
3Amount is calculated by following formula
V＝V1＊10
-6＊V2/V3＊1000
Symbolic significance
V1---C in the circulating air
3Concentration ppm
V2---C
3Mean molecular weight (in pure propylene) kg/kmol
V3---circulating air mean molecular weight kg/kmol
Two, operating point calculates
1. operating point calculates
Operating point of the present invention is meant the reactant concentration composition of reactor feed, promptly is coordinate points (XO with the coordinate representation of " propylene-oxygen " concentration
2, YPP).Calculate by following formula:
The propylene flow:
FP＝FPX＊Kp/MWP kmol/h
Air mass flow:
FA＝F1AIR＊K1a＊1/(1+HA/1000)/MWA kmol/h
The MPS flow:
FMPS＝FMPSX＊Km/MWMP kmol/h
The circulating air flow:
FRG＝Frc＊Kr/MWRG kmol/h
Carry the propylene flow in the circulating air:
FC3＝FRG＊C3A＊10
-6 kmol/h
Discharge in the soft air:
FAW＝FA＊MWA/MWWT＊(HA/1000) kmol/h
The total molar flow of reaction feed:
FTOTAL＝FP+FA+FMPS+FRG+FAW kmol/h
Propylene volumetric molar concentration (mol%)
XPP＝((FP+FC3)/FTOTAL)＊100 mol％
Oxygen volumetric molar concentration (mol%)
XO
2＝((FA＊0.21+FRG＊AOXG)/FTOTAL)＊100mol％
The correlation parameter statement sees Table 2.
Table-2
| Parameter | Table number | Unit | Purposes/remarks |
| Measured value | |||
| FPX | FI-1006/FC-1007 | kg/h | The propylene flow |
| F1air | FI-1004/FC-1003 | kg/h | To the M-1101 air mass flow |
| FMPSX | FI-1009/FI-1010 | kg/h | Steam flow |
| Frc | FI-1021/FI-1022 | kg/h | Circulating air is to the M-1101 flow |
| AOXG | AI-1006A | mol％ | Circulating air O 2Content |
| PRI | PI-1015A | kPaG | Reactor R-1101 top pressure |
| F2air | FI-1012/FI-1011 | kg/h | Air is to the M-1103 flow |
| HA | AI-1002 | g/kg | Air humidity (water/dry air) |
| C3A | AI-1007 | PPm | Circulating air C 3Content |
| Mean molecular weight | |||
| MWP | Propylene | ||
| MWA | Air | ||
| MWWT | Water | ||
| MWMP | Steam | ||
| MWRG | Circulating air | ||
| MWINT | Indifferent gas in the circulating air (not comprising water, air and C3) | ||
| Flow-compensated parameter | |||
| Kp | FI-1006 flow temperature and pressure compensation coefficient | ||
| K1a | FI-1004 flow temperature and pressure compensation coefficient | ||
| Km | FI-1009 flow temperature and pressure compensation coefficient | ||
| Kr | FI-1021 flow temperature and pressure compensation coefficient | ||
2. (X-axis is O according to the current coordinate points that calculates
2, Y-axis is PP), utilize the real-time Presentation Function of DCS, in the control terminal monitor, demonstrate the residing position of operating point, make operating personnel monitor current mode of operation at any time, avoid operating point to enter blast area or the catalyzer district that suffocates.DCS monitor picture displayed as shown in Figure 3.
Three, DCS is controlled at the practical application in driving, ordinary production and the docking process automatically
Because this technology is that gas phase oxidation directly takes place for propylene and airborne oxygen, the Reactor inlet place exist blast area and oxygen lack suffocate the district (referring to figure-3), practical operation point all will face serious safety problem in case enter above any zone, particularly in device start-stop car process, the factor that influences process is more, system plays pendulum, therefore must special start-stop car and normal running control program be set according to above-mentioned operation relation, make the DCS system control start-stop car and normal running process automatically, avoid the interference of human factor, guarantee process safety.
1. drive to operate
Drive to prepare and preliminary operation:
A) start air compressor, air is introduced first, second oxidation reactor respectively.
B) start hot melt salt well heater, make reactor be preheated to set point of temperature.
C) feed the middle pressure steam of ormal weight to first reactor.
D) start DCS driving program, click " LOAD " and enter the load up pattern.
E) at this moment, program will be adjusted FC-1009 to 8593kg/h, FC-1004 to 10362kg/h automatically.
F) after FC-1009 and FC-1004 flow reach setting (operating point moves to driving trajectory starting point place, and stable), can begin to carry out the DCS operation of driving automatically.
Under load up " load " pattern, we have designed comparatively strict Load lifting trajectory for operating point, as shown in Figure 4, drive by this track, and its process is safe.
According to driving track shown in Figure 4, further derive operating point coordinate and corresponding each feed composition of reactor on a series of trajectories, result such as table 3.
During the load up operation, only need input propylene load, the DCS system can adopt interpolating method to calculate corresponding steam, air, circulating air and two anti-air mass flows according to the pairing discharge relation of table 3.
0～20% load section should promote rapidly, this be because this procedure segment operating point away from blast area, inert constituent (water vapour) ratio is higher, operates comparatively safe.And, because under low load condition, acrylic acid solution is rarer at the bottom of the quench tower, the refining difficulty that reclaims, the long increase that means waste of load up time.In addition, when the propylene load was lower than 20%, the exothermic heat of reaction amount was less, and temperature of reaction is difficult to keep.
In 20～40% load sections, the increasing degree of each propylene load is little, treat other related streams plume amount meet the requirements of proportioning and each technological parameter stable after, can promote load continuously.Its objective is keeping operating point not to be separated from the wheel paths basis, increase inventory as far as possible fast, make the thermal discharge of course of reaction reach the level of keeping the reactive system temperature, can reduce the growing amount of rare acrylic acid solution simultaneously.
When propylene load rise to 〉=67.5% after, the circulating air action button will appear switching in charging control screen, should confirm that recycle compressor smooth starting and operation are normal this moment, continue to promote operational load to 70% simultaneously, observe steam flow FC-1009, air mass flow FC-1004, circulating air flow FC-1021 and two anti-air mass flow FC-1012 and reach setting value and stable, this moment, shown proportion relation should satisfy:
PP∶H
2O∶AIR1∶INT∶AIR2＝1∶3.4∶8.095∶0∶2.381
Operating point should be positioned at the upper extreme point place (density of propylene reaches 8.0%v) of the trajectory that goes into operation in the respective picture.
After confirming that all conditions satisfies, click " ADD INT " button, program is changed over to switch the circulating air pattern, DCS will carry out operation from circulating air to first reactor that introduce under this pattern.Carry out when switching the circulating air pattern, program will not accept to change the operation (will import the close of propylene load) of fresh propylene inlet amount, and this moment, unique parameter of controlling was the circulating air flow, and with C entrained in the circulating air
3Composition flow rate (according to online infrared analysis result) is increased in the propylene flow (B1 value) automatically; Contained saturation water (20.6045%v) is added in the anti-actual discharge (H value), and in the medium mole of an anti-steam calculated value (M value) reduction circulating air the actual flow of inert constituent (not comprising water, air and C3 component), according to the setting value of R=M-(H-C) formula synchronous change FC-1009, thus the feeding amount of minimizing middle pressure steam; Under the situation that an anti-air calculated value (N value) remains unchanged, oxygen content calculated signals by online oxygen analyzer goes out the air mass flow in the circulating air, it is added in the anti-actual air flow (I value), one anti-air mass flow setting value will be by S=(N-E*Z/1000) * (1000+A1)/1000 formula synchronous change, makes to enter an anti-air capacity and a propylene feed amount ratio and keep constant.
Start under 70% operational load when switching the circulating air pattern, program will be 2.4: 1 molar ratio relation according to end some indifferent gas and propylene proportioning, calculate the inert gas total amount that will increase:
O＝B1/MWP*2.4*MWINT
In the formula: MWP---propylene molecules amount, 42.063
MWINT---indifferent gas mean molecular weight, 28.455
B1---propylene load, 70% load corresponding propylene feed amount down are 5608.6kg/h.
Therefore:
O＝5608.6/42.063*2.4*28.45461＝9106(kg/h)
And circulating air total flow (FC-1021 setting value):
T＝5608.6/42.063*2.4/RGINTB/100*RGMW＝13755kg/h
In the formula:
RGINTB---the percent by volume of inert constituent in the circulating air, 61.409563%
The mean molecular weight of RGMW---circulating air, 26.396.
Draw in the circulating air process, need close observation reaction conditions (bed temperature, temperature of molten salt etc.) and recycle compressor running status, note simultaneously not changing the circulating air flow significantly, avoid departing from of operating point, influence reaction process.
Move abnormal situation at switching the recycle compressor that may occur in the circulating air process, this module provides the function of the circulating air that decreases gradually, program will be by opposite process synchronous change FC-1009 of aforementioned increase circulating air and the setting of FC-1004, switch reposefully and fall added circulating air, and keep operating point stable.
In the startup procedure, each strand of reactor feed rate changes, reactor feed is formed and each feed component mole proportion relation sees Table 3.
2. normal running
When the ratio (mol ratio) of the indifferent gas of drawing-in system and propylene actual load reach 〉=2.38 the time, normal manipulation mode " NORMAL " button will appear in the charging control panel.Before click " NORMAL " button makes operation change the ordinary production pattern over to, must confirm that reaction conditions and each flow reach setting value and held stationary.After switching " normal running " pattern, following proportion relation is followed in the set-up and calculated strictness of M, N, O, P value:
PP∶H
2O∶AIR1∶O2∶AIR2＝1∶1∶8.095∶2.4∶2.381
Like this, DCS changes program over to normal manipulation mode.
3. shut-down operation
When device needs orderly shutdown, the device operational load progressively is reduced to below 60% (still carries out normal manipulation mode).The purpose of load down is fully to reduce system's stock, comprises surge tank inner propene, the polymerization inhibitor of having prepared; And the quantity of steam that adds in the minimizing shut-down process.
Similar with startup procedure, we have also designed strict parking trajectory for docking process.Basic imagination is: under the constant situation of the circulating air of keeping the system of entering and two anti-air mass flows, feed excessive water vapour to first reactor inlet, make operating point move to the blast area outside rapidly, thereby possess the condition of excision propylene feed along the parking trajectory.
When operational load≤60%, shut-down operation pattern " SHUTDOWN " button will appear in the charging control panel, and can change shut-down operation this moment over to.During shut-down operation, operating point will change according to track shown in figure below.
After carrying out " SHUTDOWN " operation, DCS will calculate automatically by current operating point and arrive the quantity of steam of setting that stops the required adding of PP feed points (30% load point on the track that goes into operation) (calculate simultaneously and replenish an anti-amount of fresh air).Stop the H of PP feed points
2O/PP=5.95, the computing formula of adding quantity of steam is:
ADH
2O＝(5.95-1)×B1/MWP×MWH
2O
For guaranteeing that operating point moves in strict accordance with track shown in Figure 5, corresponding increase enters the flow of an anti-fresh air when increasing the healthy tendency flow, and the air mass flow added value is calculated with following formula:
ADAIR＝(8.9-8.095)×B1/MWP×MWAIR
When different load point stopped, required initiate steam, air capacity saw the following form 4
Table-4
| Load point % | Increase quantity of steam kg/h | Increase air capacity kg/h |
| 60 | 10191.8 | 2653.523 |
| 57.5 | 9767.1 | 2542.959 |
| 55 | 9342.4 | 2432.396 |
| 52.5 | 8917.8 | 2321.832 |
| 50 | 8493.1 | 2211.269 |
| 45 | 7643.8 | 1990.142 |
| 40 | 6794.5 | 1769.015 |
| 35 | 5945.2 | 1547.888 |
After starting the shut-down program, import the quantity of steam that each step will add by dialog box, program will calculate required total step number according to the steam total flow that will increase, progressively finish the adding (program will increase corresponding air capacity automatically) of steam by clicking " next step ", make operating point move to place of safety (oxygen content is lower than the least concentration 11.2% that produces blast), thereby possess the condition of cutting off propylene feed.
When stopping propylene feed, should feed low-pressure nitrogen to the propylene line simultaneously.When treating that the propylene flow is designated as " 0 ", manually stop circulating air, top, absorption tower quenched water, middle pressure steam successively; After the oxidation reaction actuator temperature drops to setting, manually stop two anti-and anti-air feeds, thereby implement device safety, steadily stop.
Table-3 reactive systems go into operation inlet amount and proportion relation table
| The R-1 import | The R-2 import | Raw materials components mole ratio | Input concentration | |||||||||||
| Operational load | PP | AIR-1 | MP | Circulating air | AIR-2 | PP∶O 2∶H 2O∶O 2(2nd)∶INT | mol％ | |||||||
| ％ | kmol/h | kmol/h | kmol/h | kmol/h | kmol/h | PP | O 2 1ST | H 2O | O 2 2nd | INT | PP | O 2 | H 2O | INT |
| 100.0 | 189.31 | 1412.1 | 34.3 | 744.4 | 453.5 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 97.5 | 184.58 | 1376.8 | 33.4 | 725.8 | 442.2 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 95.0 | 179.85 | 1341.5 | 32.6 | 707.2 | 430.9 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 92.5 | 175.11 | 1306.2 | 31.7 | 688.6 | 419.5 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 90.0 | 170.38 | 1270.9 | 30.8 | 670.0 | 408.2 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 87.5 | 165.65 | 1235.6 | 30.0 | 651.4 | 396.8 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 85.0 | 160.91 | 1200.3 | 29.1 | 632.8 | 385.5 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 82.5 | 156.18 | 1165.0 | 28.3 | 614.2 | 374.2 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 80.0 | 151.45 | 1129.7 | 27.4 | 595.5 | 362.8 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 77.5 | 146.72 | 1094.4 | 26.6 | 576.9 | 351.5 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 75.0 | 141.98 | 1059.1 | 25.7 | 558.3 | 340.1 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 72.5 | 137.25 | 1023.8 | 24.8 | 539.7 | 328.8 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 70.0 | 132.52 | 988.5 | 24.0 | 521.1 | 317.5 | 1.00 | 1.700 | 1.000 | 0.500 | 2.400 | 8.00 | 13.605 | 8.00 | 19.21 |
| 70.0 | 132.60 | 997.9 | 67.2 | 468.4 | 317.5 | 1.00 | 1.700 | 1.243 | 0.500 | 2.157 | 8.00 | 13.605 | 9.95 | 17.26 |
| 70.0 | 132.68 | 1007.3 | 110.4 | 415.6 | 317.5 | 1.00 | 1.700 | 1.486 | 0.500 | 1.914 | 8.00 | 13.605 | 11.89 | 15.32 |
| 70.0 | 132.76 | 1016.2 | 151.1 | 366.0 | 317.5 | 1.00 | 1.700 | 1.714 | 0.500 | 1.686 | 8.00 | 13.605 | 13.72 | 13.49 |
| 70.0 | 132.85 | 1025.6 | 194.4 | 313.3 | 317.5 | 1.00 | 1.700 | 1.957 | 0.500 | 1.443 | 8.00 | 13.605 | 15.66 | 11.55 |
| 70.0 | 132.93 | 1035.0 | 237.6 | 260.6 | 317.5 | 1.00 | 1.700 | 2.200 | 0.500 | 1.200 | 8.00 | 13.605 | 17.61 | 9.60 |
| 70.0 | 133.01 | 1044.4 | 280.8 | 207.8 | 317.5 | 1.00 | 1.700 | 2.443 | 0.500 | 0.957 | 8.00 | 13.605 | 19.55 | 7.66 |
| 70.0 | 133.09 | 1053.9 | 324.0 | 155.1 | 317.5 | 1.00 | 1.700 | 2.686 | 0.500 | 0.714 | 8.00 | 13.605 | 21.49 | 5.72 |
| 70.0 | 133.17 | 1062.7 | 364.7 | 105.5 | 317.5 | 1.00 | 1.700 | 2.914 | 0.500 | 0.486 | 8.00 | 13.605 | 23.32 | 3.89 |
| 70.0 | 133.26 | 1072.1 | 408.0 | 52.7 | 317.5 | 1.00 | 1.700 | 3.157 | 0.500 | 0.243 | 8.00 | 13.605 | 25.27 | 1.94 |
| 70.0 | 133.34 | 1081.6 | 451.2 | 0 | 317.5 | 1.00 | 1.700 | 3.400 | 0.500 | 0.000 | 8.00 | 13.605 | 27.21 | 0.00 |
| 67.5 | 128.58 | 1042.9 | 451.3 | 0 | 306.1 | 1.00 | 1.700 | 3.526 | 0.500 | 0.000 | 7.92 | 13.469 | 27.94 | 0.00 |
| 65.0 | 123.81 | 1004.3 | 464.7 | 0 | 294.8 | 1.00 | 1.700 | 3.769 | 0.500 | 0.000 | 7.77 | 13.215 | 29.30 | 0.00 |
| 62.5 | 119.05 | 965.7 | 464.8 | 0 | 283.5 | 1.00 | 1.700 | 3.920 | 0.500 | 0.000 | 7.68 | 13.062 | 30.12 | 0.00 |
| 60.0 | 114.29 | 927.1 | 480.1 | 0 | 272.1 | 1.00 | 1.700 | 4.217 | 0.500 | 0.000 | 7.51 | 12.771 | 31.68 | 0.00 |
| 57.5 | 109.53 | 888.4 | 480.1 | 0 | 260.8 | 1.00 | 1.700 | 4.400 | 0.500 | 0.000 | 7.41 | 12.597 | 32.60 | 0.00 |
| 55.0 | 104.77 | 849.8 | 480.2 | 0 | 249.4 | 1.00 | 1.700 | 4.600 | 0.500 | 0.000 | 7.30 | 12.413 | 33.59 | 0.00 |
| 52.5 | 100.00 | 811.2 | 480.3 | 0 | 243.8 | 1.00 | 1.700 | 4.819 | 0.512 | 0.000 | 7.19 | 12.218 | 34.63 | 0.00 |
| 50.0 | 95.24 | 782.5 | 480.4 | 0 | 234.3 | 1.00 | 1.722 | 5.060 | 0.517 | 0.000 | 7.01 | 12.076 | 35.48 | 0.00 |
| 45.0 | 85.72 | 727.2 | 480.5 | 0 | 219.1 | 1.00 | 1.778 | 5.622 | 0.537 | 0.000 | 6.63 | 11.784 | 37.26 | 0.00 |
| 40.0 | 76.19 | 654.7 | 480.6 | 0 | 201.9 | 1.00 | 1.801 | 6.325 | 0.557 | 0.000 | 6.29 | 11.325 | 39.78 | 0.00 |
| 35.0 | 66.67 | 582.1 | 480.8 | 0 | 181.0 | 1.00 | 1.830 | 7.229 | 0.570 | 0.000 | 5.90 | 10.801 | 42.66 | 0.00 |
| 30.0 | 57.15 | 509.6 | 480.9 | 0 | 158.1 | 1.00 | 1.869 | 8.433 | 0.581 | 0.000 | 5.45 | 10.195 | 46.00 | 0.00 |
| 25.0 | 47.62 | 435.2 | 481.1 | 0 | 144.8 | 1.00 | 1.915 | 10.120 | 0.638 | 0.000 | 4.94 | 9.462 | 50.00 | 0.00 |
| 20.0 | 38.10 | 362.6 | 481.2 | 0 | 131.4 | 1.00 | 1.995 | 12.650 | 0.725 | 0.000 | 4.32 | 8.618 | 54.64 | 0.00 |
| 0.0 | 0 | 362.6 | 481.2 | 0 | 131.4 | 0.00 | 9.007 | 57.11 | 0.00 | |||||
Claims (2)
1. propylene oxidation unit DCS control system in the acroleic acid device, steam, recycled offgas, fresh air advance premixer M-1 mix after, enter mixer M-2 again and fully mix, as the first reactor R-1 charging with the fresh propylene charging.In the first reactor R-1, propylene and airborne oxygen carry out oxidation reaction and generate third rare aldehyde.First reactor outlet gas enters second reactor and continues the generation oxidation reaction with after the fresh air that replenishes mixes in the second reactor R-2 entry mixers M-3, makes third rare aldehyde further be converted into acrylic acid.The control system of this technological process is characterised in that:
Be provided with FC-1006 fresh propylene feed rate automatic control system, its flow detecting element, variable valve are located on the fresh propylene pipeline of first reactor (R-1) entry mixers M-2, the flow transmitter output signal of FC-1006 system is advanced pulpit DCS and is participated in the proportioning computing as master variable as the active amount signal of flowrate proportioning system;
Be provided with FC-1004 fresh air feed rate automatic control system, its flow detecting element, variable valve are located at fresh air and advance on the pipeline of premixer M-1, the flow transmitter output signal of FC-1004 system as the flowrate proportioning system from one of momentum signal, advance pulpit DCS, participate in computing;
Be provided with FC-1009 steam flow automatic control system, its flow detecting element, variable valve are located at steam and advance on the pipeline of premixer M-1, the flow transmitter output signal of FC-1009 system, as the flowrate proportioning system from one of momentum signal, advance pulpit DCS, participate in computing;
Be provided with FC-1021 recycled offgas automatic flow control system, its flow detecting element, variable valve are located at recycled offgas and advance on the pipeline of premixer M-1, the flow transmitter output signal of FC-1021 system, as the flowrate proportioning system from one of momentum signal, advance pulpit DCS, participate in computing;
Be provided with FC-1012 fresh air feed rate automatic control system, its flow detecting element, variable valve are located on the fresh air pipe of the second reactor R-2 entry mixers M-3, the flow transmitter output signal of FC-1012 system as the flowrate proportioning system from one of momentum signal, advance pulpit DCS, participate in computing;
The variable valve of FC-1006 system receives the DCS output signal work of FC-1006 system among the DCS;
The variable valve of FC-1004, FC-1009, FC-1012, FC-1021 system receives the DCS output signal work that results in automatically.
2. according to propylene oxidation unit DCS control system in the described acroleic acid device of claim 1, it is characterized in that:
Be provided with AI-1003 water microanalysis instrument, detect the liquid water content of fresh air, its output signal is delivered to DCS in the pulpit;
Be provided with AI-1006 oxygen content analyser, detect the oxygen content of circulating air, its output signal is delivered to DCS in the pulpit;
If AI-1007C
3Content analyzer, the C of detection recycled offgas
3Content, its output signal is delivered to DCS in the pulpit;
More than three kinds of analyser detection signals input DCS participate in proportionings and calculate, can accurate more steam regulation, the inlet of air, recycled offgas, result of calculation can reflect actual proportion relation more.
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| CNB2007100562899A CN100565400C (en) | 2007-10-29 | 2007-10-29 | Propylene oxidation unit DCS control system in the acroleic acid device |
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| CNB2007100562899A CN100565400C (en) | 2007-10-29 | 2007-10-29 | Propylene oxidation unit DCS control system in the acroleic acid device |
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| CN101149616A true CN101149616A (en) | 2008-03-26 |
| CN100565400C CN100565400C (en) | 2009-12-02 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102269986A (en) * | 2010-09-15 | 2011-12-07 | 中国石油天然气股份有限公司 | Automatic control system for copper catalyst preparation of acrylamide device |
| CN103508473A (en) * | 2013-07-24 | 2014-01-15 | 青海锂业有限公司 | Automatic control method for purification and removal of magnesium in lithium carbonate production |
| CN104437270A (en) * | 2014-11-14 | 2015-03-25 | 中国石油集团东北炼化工程有限公司吉林设计院 | Acrylic acid reaction system |
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- 2007-10-29 CN CNB2007100562899A patent/CN100565400C/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102269986A (en) * | 2010-09-15 | 2011-12-07 | 中国石油天然气股份有限公司 | Automatic control system for copper catalyst preparation of acrylamide device |
| CN102269986B (en) * | 2010-09-15 | 2013-04-24 | 中国石油天然气股份有限公司 | Automatic control system for copper catalyst preparation of acrylamide device |
| CN103508473A (en) * | 2013-07-24 | 2014-01-15 | 青海锂业有限公司 | Automatic control method for purification and removal of magnesium in lithium carbonate production |
| CN103508473B (en) * | 2013-07-24 | 2015-05-13 | 青海锂业有限公司 | Automatic control method for purification and removal of magnesium in lithium carbonate production |
| CN104437270A (en) * | 2014-11-14 | 2015-03-25 | 中国石油集团东北炼化工程有限公司吉林设计院 | Acrylic acid reaction system |
| CN107576373A (en) * | 2017-08-17 | 2018-01-12 | 浙江邦业科技股份有限公司 | A kind of synthesis ammonia system raw gas flow accuracy of detection judges and antidote |
| CN113426196A (en) * | 2021-07-06 | 2021-09-24 | 大庆中蓝石化有限公司 | Liquid recovery system is cut to nonene apparatus for producing high-pressure apparatus |
| CN113426196B (en) * | 2021-07-06 | 2022-12-27 | 大庆中蓝石化有限公司 | Liquid recovery system is cut to nonene apparatus for producing high-pressure apparatus |
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