CN116272254A - Automatic control method for pressure swing adsorption process - Google Patents
Automatic control method for pressure swing adsorption process Download PDFInfo
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- CN116272254A CN116272254A CN202310328921.XA CN202310328921A CN116272254A CN 116272254 A CN116272254 A CN 116272254A CN 202310328921 A CN202310328921 A CN 202310328921A CN 116272254 A CN116272254 A CN 116272254A
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
- B01D53/0454—Controlling adsorption
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- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
- B01D53/047—Pressure swing adsorption
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Abstract
The invention provides an automatic control method of a pressure swing adsorption process, which comprises the following steps: automatically adjusting the adsorption time: calculating the adsorption time according to the device load, thereby controlling the duration of the adsorption process; automatic tower cutting: determining a control valve corresponding to the adsorption tower in the current process, and judging the adsorption tower as a fault tower and cutting off the fault tower when the actual pressure deviation in the adsorption tower does not meet the set pressure deviation requirement and the control valve corresponding to the adsorption tower in the current process gives out fault alarm; automatically adjusting and regulating a valve: according to the load change of the device, the lower limit of the opening value of the regulating valve corresponding to the boosting procedure, the reverse discharging procedure and the flushing procedure is regulated in real time; automatically adjusting the analysis gas: and according to the device load and the pressure value of the reverse air release buffer tank when the reverse air release procedure is finished, calculating the set pressure of the analysis air buffer tank according to the reverse air release quantity stored in the reverse air release buffer tank, and outputting analysis air according to the calculated set pressure. The automation degree of the pressure swing adsorption process is improved.
Description
Technical Field
The invention relates to the technical field of pressure swing adsorption processes, in particular to an automatic control method of a pressure swing adsorption process.
Background
Along with the development and large-scale application of the gas pressure swing adsorption technology, higher requirements are also put forward on the automation degree of pressure swing adsorption control. The pressure swing adsorption process is a set of sequential control process with high automation degree, most of control is automatically realized by a control system, but when the device has abnormal faults or large fluctuation, a great deal of intervention control by operators is needed to ensure the normal and stable operation of the device.
Therefore, in the existing pressure swing adsorption process, for the conditions of large flow fluctuation and abnormal faults, the automation degree of the control system is insufficient, automatic adjustment is difficult to achieve through a program, operators are required to judge through experience, the efficiency is insufficient, the accuracy is low, the pressure swing adsorption process system is difficult to switch to a normal working state in time, and the stability is poor.
Disclosure of Invention
The invention aims to at least solve one of the technical problems that in the prior art, the automation degree of a pressure swing adsorption process control system is insufficient, automatic adjustment is difficult to realize through a program, operators are required to judge through experience, the efficiency is insufficient, the accuracy is low, the pressure swing adsorption process system is difficult to switch to a normal working state in time, and the stability is poor.
Therefore, the invention provides an automatic control method for the pressure swing adsorption process.
The invention provides an automatic control method of a pressure swing adsorption process, which comprises an adsorption process, a decompression process, a forward discharge process, a reverse discharge process, a flushing process and a boosting process, and comprises the following steps:
automatically adjusting the adsorption time: calculating adsorption time according to the device load, and controlling the duration of the adsorption process by using the calculated adsorption time;
automatic tower cutting: determining a control valve corresponding to the adsorption tower in the current process, and judging the adsorption tower as a fault tower and cutting off the fault tower when the actual pressure deviation in the adsorption tower does not meet the set pressure deviation requirement and the control valve corresponding to the adsorption tower in the current process gives out fault alarm;
automatically adjusting and regulating a valve: according to the load change of the device, the lower limit of the opening value of the regulating valve corresponding to the boosting procedure, the reverse discharging procedure and the flushing procedure is regulated in real time;
automatically adjusting the analysis gas: and according to the device load and the pressure value of the reverse air release buffer tank when the reverse air release process is finished, the set pressure of the analysis air buffer tank is calculated according to the reverse air release quantity stored in the reverse air release buffer tank, and the analysis air is conveyed to the reformer according to the calculated set pressure.
The automatic control method of the pressure swing adsorption process according to the technical scheme of the invention can also have the following additional technical characteristics:
in the above technical solution, the method for calculating the adsorption time according to the device load includes:
wherein T is Actual practice is that of The current adsorption time; t (T) Design of Adsorption time corresponding to full load of raw material gas designed for the process; f (F) Design of Full-load flow of raw material gas designed for the process; f (F) Actual practice is that of Is the average flow rate of the raw material gas in an adsorption period; k (K) T Is a time coefficient.
In the above technical solution, automatically adjusting the adsorption time further includes adjusting a time coefficient according to the quality of the product gas.
In the above technical solution, the method for calculating the actual pressure deviation includes: when the adsorption tower enters another process from one process, the pressure value P1 in the adsorption tower is obtained, and the pressure value P2 in the adsorption tower is obtained once every a period of time, so that the actual pressure deviation delta P is obtained Actual practice is that of ＝|P2-P1|；
The set pressure deviation is an alarm pressure deviation value in each process set according to the actual running condition;
and when the actual pressure deviation value is larger or smaller than the set pressure deviation value, the adsorption tower gives a pressure alarm.
In the above technical solution, the control valve corresponding to the adsorption tower in the adsorption process includes: an adsorption tower air inlet valve, an adsorption tower air outlet valve and an adsorption tower one-average/final lift valve;
the control valve corresponding to the adsorption tower in the depressurizing step and the pressurizing step comprises: an air inlet valve of the adsorption tower, an air outlet valve of the adsorption tower, an average/final lift valve of the adsorption tower and an average/three average valve of the adsorption tower;
the control valve corresponding to the adsorption tower in the flushing process comprises: the adsorption tower washes admission valve, adsorption tower and washes discharge valve and adsorption tower reverse discharge valve.
In the technical scheme, after the automatic tower cutting, faults are processed, then the pressure in the fault tower is reduced to the pressure value of the adsorption tower in the reverse discharging process, and the reverse discharging process is executed, so that recovery after the tower cutting is realized.
In the above technical solution, in the automatic adjustment adjusting valve, the adjusting valve related to the boosting procedure includes an adsorption tower one-average/final-rise adjusting valve, and the calculating method of the lower limit of the opening value of the adsorption tower one-average/final-rise adjusting valve is as follows:
E1_L＝(K1*F1)/(KT*K)+K2-K4；
the regulating valve related to the reverse discharging procedure comprises a reverse discharging regulating valve and a pressure regulating valve behind a reverse discharging buffer tank, wherein the calculating method of the lower limit of the opening value of the reverse discharging regulating valve comprises the following steps:
D_L＝(K5*F1)/(K2*K)+K6；
the calculation method of the lower limit of the opening value of the pressure regulating valve behind the reverse-discharging buffer tank comprises the following steps:
N_L＝(K9*F1)/(K2*K)+K10；
the adjusting valve corresponding to the flushing procedure comprises a flushing adjusting valve, and the calculating method of the lower limit of the opening value of the flushing adjusting valve comprises the following steps:
PP_L＝(K7*F1)/(K2*K)+K8；
k is a flow value corresponding to 1.0% of valve output change; k1, K5, K7 and K9 are flow correction coefficients; k (K) T Is a time coefficient; k2, K4, K6, K8 and K10 are valve output trim values; f1 is the average flow of feed gas over one cycle.
In the above technical solution, the calculation method for analyzing the set pressure of the gas buffer tank includes:
wherein N is 1 The reverse air release amount is stored for the reverse air release buffer tank; n (N) 2 The actual pressure value of the reverse-venting buffer tank at the end of the reverse-venting procedure; n (N) 3 The ideal pressure value of the reverse-venting buffer tank is obtained when the reverse-venting process is finished; n (N) 4 For adjusting the coefficients; t (T) A Cycle time for adsorption; SP (service provider) 1 The SP value of the upper period.
In the above technical solution, further includes:
automatic pressure regulation of the reverse air release buffer tank: and opening the analysis air pressure regulating valve to the lower limit of the opening value of the analysis air pressure regulating valve within T seconds when the reverse discharging process starts to operate, and automatically regulating the opening of the analysis air pressure regulating valve according to the analysis air pressure set value after the T seconds when the reverse discharging process starts to operate.
In the above technical solution, further includes:
the regulating valve is automatically switched: and (3) respectively adding a standby valve to the first average/final lift regulating valve, the reverse discharge regulating valve and the flushing regulating valve of the adsorption tower, judging whether the regulating valve fails according to a valve detection signal and whether actual pressure deviation in the adsorption tower meets the set pressure deviation requirement when the output value of the regulating valve does not meet the set value requirement, and switching to the corresponding standby valve when the regulating valve fails.
In summary, due to the adoption of the technical characteristics, the invention has the beneficial effects that:
the full-automatic control of the pressure swing adsorption process can be basically realized, the stable conversion of the pressure swing adsorption under different working conditions can be completed without personnel interference in the whole process of the pressure swing adsorption, the participation degree of operators is reduced, the working efficiency is improved, the error rate is reduced, and the stable operation of the pressure swing adsorption process is ensured.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic diagram of a valve arrangement for a pressure swing adsorption process in one embodiment of the invention;
FIG. 2 is an enlarged view of a portion of FIG. 1 at A;
FIG. 3 is a partial enlarged view at B in FIG. 1;
fig. 4 is a partial enlarged view at C in fig. 1.
The correspondence between the reference numerals and the component names in fig. 1 to 4 is:
1. a raw material gas buffer tank; 2. an adsorption tower; 3. c, smoothly discharging the gas tank; 4. a reverse-venting buffer tank; 5. a desorption gas mixing tank; 6. a feed gas overpressure vent control valve; 7. an air inlet valve of the adsorption tower; 8. flushing an exhaust valve of the adsorption tower; 9. an adsorption tower reverse discharge valve; 10. an exhaust valve of the adsorption tower; 11. an adsorption tower I average/final lift valve; 12. two/three average valves of the adsorption tower; 13. flushing an air inlet valve of the adsorption tower; 14. four average/sequential discharge valves of the adsorption tower; 15. an adsorption tower I average/final lift regulating valve; 16. a flush regulating valve; 17. a forward discharging valve of the forward discharging gas tank; 18. an adsorption tower working pressure regulating valve; 19. the product gas overpressure relief regulating valve; 20. a reverse discharge regulating valve; 21. analyzing the air pressure regulating valve; 22. an analysis gas overpressure relief regulating valve; 23. and a pressure regulating valve of the analysis air outlet device.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as described herein, and therefore the scope of the present invention is not limited to the specific embodiments disclosed below.
The following describes a pressure swing adsorption process automatic control method provided according to some embodiments of the present invention with reference to fig. 1 to 4.
Some embodiments of the present application provide a pressure swing adsorption process automation control method.
The pressure swing adsorption process mainly comprises an adsorption process, a decompression process, a forward-discharge process, a reverse-discharge process, a flushing process and a boosting process, wherein the adsorption process is that raw material gas enters an adsorption bed of an adsorption tower 2 at normal temperature and high pressure, and impurities are adsorbed by using an adsorbent to obtain hydrogen as a product; the pressure reducing process is to recycle the dead space hydrogen of the bed layer through one or more pressure equalizing and reducing processes; the reverse discharge procedure is to decompress the adsorbent against the adsorption direction to obtain partial regeneration; the flushing procedure is to flush the product hydrogen to reduce the partial pressure of impurities, so that the adsorbent is regenerated finally; the pressure boosting procedure is to boost the pressure of the adsorption tower 2 to the adsorption pressure through one or more pressure equalizing and boosting processes of the product gas, so as to prepare for the next adsorption.
In one embodiment, the pressure swing adsorption process comprises thirteen process steps of adsorption, one average drop, two average drops, three average drops, four average drops, sequential discharge, reverse discharge, flushing, four average drops, three average drops, two average drops, one average drop and final product hydrogen drop, wherein one average drop, two average drops, three average drops and four average drops are four pressure reducing processes arranged in sequence, and four average drops, three average drops, two average drops and one average drop are four pressure increasing processes arranged in sequence; the final boost is the last boost process, namely four equal boost. Schematic diagrams of the valve arrangement in the process are shown in fig. 1 to 4, which include:
feed gas buffer tank 1: for stabilizing the pressure of the feed gas;
adsorption tower 2: for adsorbing impurity gases in the feed gas;
forward air release tank 3: for collecting a part of the product gas and for flushing the magazine gas in the adsorption column 2;
reverse air release buffer tank 4: the device is used for collecting magazine gas with higher pressure and delivering the magazine gas out under reduced pressure;
and a desorption gas mixing tank 5: the device is used for collecting magazine gas after the forward-discharge gas tank 3 washes the adsorption tower 2;
feed gas overpressure vent control valve 6: the method is used for overpressure emptying of the raw material gas, protecting the raw material gas buffer tank 1 and avoiding the excessive high pressure of the raw material gas;
adsorption tower inlet valve 7: the raw material gas enters a cut-off valve of the adsorption tower 2;
the adsorption tower washes the exhaust valve 8: an exhaust shutoff valve for flushing regeneration of the adsorption tower 2;
adsorption tower reverse discharge valve 9: a cut-off valve for reverse discharge of the adsorption tower 2;
adsorption tower vent valve 10: a cut-off valve for the product gas out of the adsorption tower 2;
adsorption column one-average/final-rise valve 11: a cut-off valve for first pressure equalizing and final pressure boosting of the adsorption tower 2;
adsorption tower two-way/three-way valve 12: a cut-off valve for the second pressure equalizing and the third pressure equalizing of the adsorption tower 2;
adsorption tower washes admission valve 13: an intake shutoff valve for flushing regeneration of the adsorption tower 2;
adsorption tower four-way/forward valve 14: a cut-off valve for equalizing pressure of the adsorption tower 2 for the fourth time and equalizing pressure of the gas into the forward-discharge tank 3;
adsorption column one-average/final-rise regulating valve 15: a control regulating valve for pressure regulating action of the adsorption tower 2 in the uniform pressure increasing and final pressure increasing processes;
flushing control valve 16: the flushing pressure is regulated in the flushing process of the adsorption tower 2, so that the pressure is stabilized in a certain pressure range;
forward bleed valve 17: when the adsorption tower 2 is put down, the gas is discharged into a needed down-discharging tank 3;
adsorption tower operating pressure regulating valve 18: regulating the pressure of the adsorption tower 2 in the adsorption process;
product gas overpressure relief regulating valve 19: in the working process of the adsorption tower 2, when the product air pressure exceeds a pressure set value, regulating the pressure and performing air defense;
reverse discharge regulating valve 20: the adsorption tower 2 is a process of reducing the pressure in the tower to a certain pressure against the adsorption direction after the completion of the forward process, and the adsorbed impurities begin to be desorbed from the adsorbent at the moment;
analytical air pressure regulating valve 21: placing the reverse deflation regulating pressure into a desorption gas mixing tank;
resolving gas overpressure relief regulating valve 22: when the pressure of the analysis gas buffer tank exceeds a set value, regulating the pressure and diffusing;
analysis air outlet device pressure regulating valve 23: and adjusting the stable conveying device of the analysis gas.
The pressure swing adsorption process is taken as an example, and the automatic control method of the pressure swing adsorption process in some embodiments is described below.
The first embodiment of the invention provides an automatic control method of a pressure swing adsorption process, which comprises the steps of automatically adjusting adsorption time, automatically cutting a tower, automatically adjusting an adjusting valve and automatically adjusting analysis gas.
Wherein, the automatic adjustment of the adsorption time is to calculate the adsorption time according to the load of the device, and the duration of the adsorption process is controlled by using the calculated adsorption time. Specifically, the method for calculating the adsorption time according to the device load is as follows:
wherein T is Actual practice is that of The current adsorption time; t (T) Design of Adsorption time corresponding to full load of raw material gas designed for the process; f (F) Design of Full-load flow of raw material gas designed for the process; f (F) Actual practice is that of Is the average flow rate of the raw material gas in an adsorption period; k (K) T Is a time coefficient.
In some embodiments, automatically adjusting the adsorption time further comprises automatically adjusting a time coefficient based on the quality of the product gas. Namely, when the impurity content in the product gas is larger than the set value, the time coefficient K can be properly reduced T Thereby shortening the adsorption time and improving the purity of the product gas; otherwise, the purity of the product is too high, and the time coefficient K can be properly increased T Thereby prolonging the adsorption time and improving the recovery rate of the device. After each time of adjusting the adsorption time, a certain time is needed to be waited for to reflect the change in the product gas, thusIn automatically adjusting the time coefficient K T After that, a certain time is required to wait for the next adjustment. In addition the time coefficient K T The upper and lower limits should be set in order to prevent the sorbent from penetrating when the analyzer is out of order.
The automatic tower cutting mode is to determine a control valve corresponding to the adsorption tower 2 in the current process, and when the actual pressure deviation in the adsorption tower 2 does not meet the set pressure deviation requirement and the control valve corresponding to the adsorption tower 2 in the current process gives out fault alarm, the adsorption tower 2 is judged to be a fault tower, and the fault tower is cut off.
The actual pressure deviation calculating method comprises the following steps: when the adsorption tower 2 enters another process from one process, obtaining the pressure value P1 in the adsorption tower 2, and taking the pressure value P2 in the adsorption tower 2 once every a period of time, namely when the running time is longer than the set deviation alarm judging time, wherein the deviation alarm judging time is set by an operator, and in some embodiments, the deviation alarm judging time is set to be 10-20 seconds; the actual pressure deviation deltap Actual practice is that of = |p2—p1|; the value of P2 is updated continuously along with the increase of the running time, and the actual pressure deviation is changed along with the increase of the running time.
Set pressure deviation ΔP Setting up The alarm pressure deviation values in the working procedures are set according to actual running conditions; in some procedures when delta P Actual practice is that of >ΔP Setting up When the pressure alarm occurs in the adsorption tower 2; in other steps, when ΔP Actual practice is that of <ΔP Setting up When the pressure alarm occurs in the adsorption tower 2.
The automatic tower cutting function is the most important part in the automatic adsorption process, and aims to cut off the operation of the adsorption tower 2 corresponding to the fault valve in order not to influence the quality of the product gas and the stability of the device when the control valve of one adsorption tower 2 is in fault.
The failure of the control valve is mainly divided into the following three types:
(1) An open failure, i.e. the valve is not open when it should be.
(2) A shut-off failure, i.e. the valve is not closed when it should be.
(3) The return signal is not corresponding to the valve open and close state, but the return signal of the valve is not changed due to the valve action.
Only the 'return fault' in the three faults can not have any influence on the device, and other two fault phenomena can have certain influence on the pressure of the device, so that whether the fault exists can not be truly judged only by the return detection of the valve, and the pressure alarm is needed to be added to confirm that the valve is in the fault.
The following analysis was performed for the states of the adsorption tower 2 in different steps:
(1) Adsorption process
The opening and closing operations of the control valve corresponding to the adsorption tower 2 in the adsorption step mainly include: an adsorption tower inlet valve 7 is opened, an adsorption tower outlet valve 10 is opened, and an adsorption tower one-average/final-lift valve 11 is closed.
And (3) fault analysis:
a) When the air inlet valve 7 of the adsorption tower is opened and fails, the pressure of raw material air can be increased, the pressure of the adsorption tower 2 can be reduced, the pressure of the product air can be reduced, and the pressure difference between the front and the rear of the device is increased;
b) When the exhaust valve 10 of the adsorption tower fails, the pressure of raw material gas is increased, the pressure of the adsorption tower 2 is increased, the pressure of a product is reduced, and the pressure difference between the front and the rear of the device is increased;
c) When the adsorption tower one-average/final-rise valve 11 fails, the raw material gas pressure will be reduced, the adsorption tower 2 pressure will be reduced, the product gas pressure will be reduced, and the pressure difference change before and after the device is not great.
The automatic tower cutting judging method comprises the following steps:
a) When DeltaP Actual practice is that of >ΔP Setting up When pressure alarm occurs, and if any valve of the tower has fault alarm, the program automatically cuts off the tower;
b) When the adsorption tower air inlet valve 7 or the adsorption tower air outlet valve 10 fails and the pressure difference before and after the pressure swing adsorption device is larger than a set alarm value (according to different device loads and different set values), the program automatically cuts the tower.
(2) Pressure reducing step/pressure increasing step (Yi)
The opening and closing operations of the control valve corresponding to the adsorption tower 2 in the depressurization step/the pressurization step mainly include: guan Xifu tower inlet valve 7, closing adsorption tower exhaust valve 10, closing adsorption tower second average/third average valve 12, and opening adsorption tower first average/final lift valve 11.
And (3) fault analysis:
a) When the first average/final rising valve 11 of the adsorption tower is opened, the corresponding pressure of the adsorption tower 2 is not changed, namely the pressure is not increased when the adsorption tower is uniformly raised, and the pressure is not reduced when the adsorption tower is uniformly lowered;
b) When the air inlet valve 7 or the air outlet valve 10 of the adsorption tower is closed and fails, the pressure of the uniformly-rising adsorption tower 2 is too low, so that the product air pressure is quickly reduced, the pressure of the uniformly-rising adsorption tower 2 is also quickly increased, and the uniformly-falling adsorption tower 2 is increased after being reduced in a short time;
c) When the second/third equalizing valve 12 of the absorption tower is closed and fails, the pressure of the absorption tower 2 is not increased or is increased slowly, and the pressure of the absorption tower 2 which is evenly reduced is rapidly reduced;
the automatic tower cutting judging method comprises the following steps:
when DeltaP Actual practice is that of >ΔP Setting up If the pressure value of the rising pressure of the adsorption tower 2 is not reached or the pressure value of the falling pressure is not reached, a pressure alarm is generated, and if any valve of the tower fails, the program automatically cuts off the tower.
(3) Other pressure equalizing (two-average, three-average, four-average), forward-discharge, reverse-discharge and final-lift processes
The other pressure equalizing, forward discharging, reverse discharging and final lifting processes are basically the same as the tower cutting mode of the first uniform process, and when the valve fails, the pressure of the adsorption tower 2 can be influenced to a certain extent, and the difference is that when delta P is that Actual practice is that of <ΔP Setting up And when the valve alarms, the program automatically cuts off the fault tower.
(4) Flushing process
The opening and closing operations of the control valve corresponding to the adsorption tower 2 in the flushing step mainly include: the adsorption tower flushing air inlet valve 13 is opened, the adsorption tower flushing air outlet valve 8 is opened, and the adsorption tower reverse discharge valve 9 is closed.
And (3) fault analysis:
a) When the adsorption tower flushing air inlet valve 13 is opened and fails, the pressure of the adsorption tower 2 is reduced, but because the pressure of the adsorption tower 2 is close to the analysis air pressure (about 0.05MPa of the reverse discharge end pressure), the pressure reduction amplitude of the adsorption tower 2 is not obvious, if one adsorption tower 2 is flushed by one forward discharge air tank, the pressure can be quickly increased after the regulating valve 16 is flushed, and the pressure of the forward discharge air tank is not reduced;
b) When the flushing exhaust valve 8 of the adsorption tower fails, the pressure of the adsorption tower 2 can rise, which is equivalent to equalizing pressure with the forward-discharging gas tank;
c) When the reverse discharge valve 9 of the adsorption tower fails, the reverse discharge is just started, the pressure is about 0.05MPa, the pressure of the other adsorption towers 2 which do reverse discharge is about 0.2MPa, and the reverse discharge regulating valve 20 and the flushing regulating valve 16 are in a small opening state at the moment, so that the reverse discharge gas of the adsorption towers 2 in the reverse discharge state enters the adsorption towers 2 through the reverse discharge main pipe, the pressure of the adsorption towers 2 can be increased, the opening degree of the reverse discharge regulating valve 20 and the flushing regulating valve 16 is gradually increased along with the increase of the running time, the pressure of the final adsorption towers 2 is also reduced, the analysis effect is influenced to a certain extent, and the analysis air flow rate also has great fluctuation, so that the temperature of the conversion furnace is influenced.
The automatic tower cutting judging method comprises the following steps:
a) When DeltaP Actual practice is that of >ΔP Setting up When pressure alarm occurs, and if any valve of the tower has fault alarm (mainly judging that the adsorption tower washes the exhaust valve 8), the program automatically cuts off the tower;
b) ΔP after flushing the regulator valve 16 Actual practice is that of >ΔP Setting up At the same time, if the tower adsorption tower flushing air inlet valve 13 fails, the program automatically cuts off the tower.
In some embodiments, after the tower cutting is completed, in order to restore the operation of the adsorption tower 2 after the fault is removed, the program automatically selects a proper step sequence to restore the adsorption tower 2 according to the pressure value of the removed adsorption tower 2, and in some cases, when the pressure is high, it is difficult to find the proper step sequence; therefore, after automatic tower cutting, faults are processed firstly, then the pressure in the fault tower is reduced to be close to the pressure value of the adsorption tower 2 in the reverse discharge process, recovery after tower cutting is realized, and the reverse discharge process is performed after recovery of the adsorption tower 2, so that pressure fluctuation of the whole system is minimum.
The automatic adjusting valve is realized by adjusting the lower limit of the opening value of the adjusting valve corresponding to the boosting procedure, the reverse discharging procedure and the flushing procedure in real time according to the load change of the device.
Specifically, when the load of the device changes, the speeds of final lifting, reverse discharging and flushing correspondingly change, so that the opening value of the lower limit of the device needs to be adjusted in a small range to realize more stable operation.
Wherein, the adjusting valve related to the boosting procedure comprises an adsorption tower one-average/final-rise adjusting valve 15, and the calculation method of the lower limit of the opening value of the adsorption tower one-average/final-rise adjusting valve 15 is as follows:
E1_L＝(K1*F1)/(K T *K)+K2-K4；
the regulating valve related to the reverse discharging procedure comprises a reverse discharging regulating valve 20 and a pressure regulating valve behind the reverse discharging buffer tank 4, and the calculating method of the lower limit of the opening value of the reverse discharging regulating valve 20 is as follows:
D_L＝(K5*F1)/(K2*K)+K6；
the calculation method of the lower limit of the opening value of the pressure regulating valve behind the reverse air release buffer tank 4 comprises the following steps:
N_L＝(K9*F1)/(K2*K)+K10；
the adjusting valve corresponding to the flushing process comprises a flushing adjusting valve 16, and the method for calculating the lower limit of the opening value of the flushing adjusting valve 16 comprises the following steps:
PP_L＝(K7*F1)/(K2*K)+K8；
wherein K is the flow value (unit: NM 3/H) corresponding to 1.0% change in valve output, i.e. K1=1 and K T When=1, the valve flow increases by X% for every X times the feed gas increase;
k1, K5, K7 and K9 are flow correction coefficients; KT is a time coefficient; k2, K4, K6, K8 and K10 are valve output trim values; f1 is the average flow of feed gas over one cycle.
The method of automatically adjusting the analysis gas is to calculate the set pressure of the analysis gas buffer tank according to the device load, the pressure value of the reverse gas buffer tank 4 at the end of the reverse gas release procedure and the reverse gas release amount stored in the reverse gas buffer tank 4, so that the analysis gas is delivered to the reformer according to the calculated set pressure.
In some embodiments, to enable the resolved barometric pressure adjustment to be quickly adjusted as the load changes, the resolved barometric pressure control is divided into two modes, local and remote. In the in-situ mode, a pressure value is set by the operator through single loop regulation, such that the desorption gas pressure of the de-reformer is controlled to be in the vicinity of this pressure value. The set value is not adjusted according to the load of the device and can only be manually input by an operator. In the remote mode, the set pressure is automatically adjusted according to the load of the device in such a way that
Wherein N is 1 The reverse ventilation volume stored for the reverse ventilation buffer tank 4; n (N) 2 Is the actual pressure value of the reverse-venting buffer tank 4 at the end of the reverse-venting procedure; n (N) 3 Is the ideal pressure value of the reverse-venting buffer tank 4 at the end of the reverse-venting procedure; n (N) 4 For adjusting the coefficients; t (T) A Cycle time for adsorption; SP (service provider) 1 The SP value of the upper period.
In other embodiments, the automatic control method further comprises automatic pressure adjustment of the reverse-vented buffer tank 4, since reverse venting and flushing are started simultaneously, so that there is a large amount of resolving gas in the initial stage, the influence on the resolving gas pressure adjusting valve 21 is large, and the adjusting loop is changed into the following control scheme: in T seconds when the reverse discharging procedure starts to run, the analysis air pressure regulating valve 21 is in a manual state and is opened to the lower limit of the opening value; after T seconds from the start of the reverse run, the analysis air pressure adjusting valve 21 is in an automatic control state, and the opening degree thereof is automatically adjusted according to the analysis air pressure set value, so that the analysis air pressure is in a steady state (the deviation between the maximum value and the minimum value can be controlled within 0.002 MPa).
In other embodiments, the automatic control method further comprises automatic switching of the regulating valve, specifically, in normal production, if a common regulating valve fails, the common regulating valve can be controlled by opening a certain opening degree through a bypass. However, the first-stage/final-stage regulating valve 15, the reverse discharge regulating valve 20 and the flushing regulating valve 16 of the adsorption tower are automatically controlled by a program and are all in a changing state at all times, and if a certain opening degree is fixed by a hand valve when the valve fails, the stability of the device and the analysis effect of the adsorbent are greatly affected. Therefore, a standby valve is added to each of the three valves, and a valve opening feedback detection signal is added, if one running regulating valve fails, the program automatically judges and switches to the standby valve, and meanwhile, an alarm appears on an operation picture to prompt an operator to repair in time.
For the adsorption tower one-average/final-rise regulating valve 15, when the output value OP of the adsorption tower one-average/final-rise regulating valve 15 is at the final-rise process>OP Setting up When (operator input), if the valve opening signal is not displayed and the pressure of the adsorption tower 2 in the final rising state is not changed (i.e., ΔP Actual practice is that of <ΔP Setting up ) Judging the open fault of the regulating valve, and automatically switching the program to a standby valve; in the first step, if the valve open signal is always present and the pressure of the adsorption tower 2 reaches or exceeds the first end pressure (set by the operator) in a short time (set by the operator), the control valve is judged to be out of order, and the routine is automatically switched to the backup valve.
In the reverse discharge control valve 20, the output value OP of the control valve is set at the time of the reverse discharge process>OP Setting up If the valve-opening signal of the regulator valve is not displayed and the pressure of the adsorption column 2 is not changed (i.e., Δp Actual practice is that of <ΔP Setting up ) Judging the valve to be opened and fault, and automatically switching the program to a standby valve; when the output value OP of the regulating valve<OP Setting up At this time, if the valve-opening signal is present, and the pressure of the adsorption tower 2 is rapidly reduced (i.e., Δp Actual practice is that of >ΔP Setting up ) If the valve is judged to be closed, the program is automatically switched to the standby valve.
In the flushing process, the output value OP of the regulating valve 16 is>OP Setting up If the valve open signal is not displayed and there is no change in the forward bleed tank pressure (i.e., ΔP Actual practice is that of <ΔP Setting up ) Judging that the flushing regulating valve 16 is opened and fault, and automatically switching the program to a standby valve; when the output value OP of the regulating valve<OP Setting up If the valve-open signal of the regulating valve is present and the forward bleed tank pressure is rapidly reduced (i.e., ΔP Actual practice is that of >ΔP Setting up ) If the valve is judged to be open, the program is automatically switched to the standby valve.
In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. An automatic control method for a pressure swing adsorption process, the pressure swing adsorption process comprises an adsorption process, a decompression process, a forward discharge process, a reverse discharge process, a flushing process and a boosting process, and is characterized by comprising the following steps:
automatically adjusting the adsorption time: calculating adsorption time according to the device load, and controlling the duration of the adsorption process by using the calculated adsorption time;
automatic tower cutting: determining a control valve corresponding to the adsorption tower in the current process, and judging the adsorption tower as a fault tower and cutting off the fault tower when the actual pressure deviation in the adsorption tower does not meet the set pressure deviation requirement and the control valve corresponding to the adsorption tower in the current process gives out fault alarm;
automatically adjusting and regulating a valve: according to the load change of the device, the lower limit of the opening value of the regulating valve corresponding to the boosting procedure, the reverse discharging procedure and the flushing procedure is regulated in real time;
automatically adjusting the analysis gas: and according to the device load and the pressure value of the reverse air release buffer tank when the reverse air release process is finished, the set pressure of the analysis air buffer tank is calculated according to the reverse air release quantity stored in the reverse air release buffer tank, and the analysis air is conveyed to the reformer according to the calculated set pressure.
2. The automatic control method of pressure swing adsorption process according to claim 1, wherein the method for calculating the adsorption time according to the device load is:
wherein T is Actual practice is that of The current adsorption time; t (T) Design of Adsorption time corresponding to full load of raw material gas designed for the process; f (F) Design of Full-load flow of raw material gas designed for the process; f (F) Actual practice is that of Is the average flow rate of the raw material gas in an adsorption period; k (K) T Is a time coefficient.
3. The method of claim 2, wherein automatically adjusting the adsorption time further comprises adjusting a time factor based on the quality of the product gas.
4. The automatic control method of a pressure swing adsorption process according to claim 1, wherein the actual pressure deviation calculating method comprises the following steps: when the adsorption tower enters another process from one process, the pressure value P1 in the adsorption tower is obtained, and the pressure value P2 in the adsorption tower is obtained once every a period of time, so that the actual pressure deviation delta P is obtained Actual practice is that of ＝|P2-P1|；
The set pressure deviation is an alarm pressure deviation value in each process set according to the actual running condition;
and when the actual pressure deviation value is larger or smaller than the set pressure deviation value, the adsorption tower gives a pressure alarm.
5. The automatic control method for pressure swing adsorption process according to claim 1, wherein the control valve corresponding to the adsorption tower in the adsorption process comprises: an adsorption tower air inlet valve, an adsorption tower air outlet valve and an adsorption tower one-average/final lift valve;
the control valve corresponding to the adsorption tower in the depressurizing step and the pressurizing step comprises: an air inlet valve of the adsorption tower, an air outlet valve of the adsorption tower, an average/final lift valve of the adsorption tower and an average/three average valve of the adsorption tower;
the control valve corresponding to the adsorption tower in the flushing process comprises: the adsorption tower washes admission valve, adsorption tower and washes discharge valve and adsorption tower reverse discharge valve.
6. The automatic control method of pressure swing adsorption process according to claim 1, wherein after automatic tower cutting, the fault is processed first, then the pressure in the fault tower is reduced to the pressure value of the adsorption tower in the reverse-discharge process, and the reverse-discharge process is performed to realize recovery after tower cutting.
7. The automatic control method of pressure swing adsorption process according to claim 1, wherein the adjusting valve related to the pressure increasing process in the automatic adjusting valve comprises an adsorption tower one-average/final-rise adjusting valve, and the calculation method of the lower limit of the opening value of the adsorption tower one-average/final-rise adjusting valve is as follows:
E1_L＝(K1*F1)/(KT*K)+K2-K4；
the regulating valve related to the reverse discharging procedure comprises a reverse discharging regulating valve and a pressure regulating valve behind a reverse discharging buffer tank, wherein the calculating method of the lower limit of the opening value of the reverse discharging regulating valve comprises the following steps:
D_L＝(K5*F1)/(K2*K)+K6；
the calculation method of the lower limit of the opening value of the pressure regulating valve behind the reverse-discharging buffer tank comprises the following steps:
N_L＝(K9*F1)/(K2*K)+K10；
the adjusting valve corresponding to the flushing procedure comprises a flushing adjusting valve, and the calculating method of the lower limit of the opening value of the flushing adjusting valve comprises the following steps:
PP_L＝(K7*F1)/(K2*K)+K8；
k is a flow value corresponding to 1.0% of valve output change; k1, K5, K7 and K9 are flow correction coefficients; KT is a time coefficient; k2, K4, K6, K8 and K10 are valve output trim values; f1 is the average flow of feed gas over one cycle.
8. The automatic control method of pressure swing adsorption process according to claim 1, wherein the calculation method for resolving the set pressure of the gas buffer tank is:
wherein N is 1 The reverse air release amount is stored for the reverse air release buffer tank; n (N) 2 The actual pressure value of the reverse-venting buffer tank at the end of the reverse-venting procedure; n (N) 3 The ideal pressure value of the reverse-venting buffer tank is obtained when the reverse-venting process is finished; n (N) 4 For adjusting the coefficients; t (T) A Cycle time for adsorption; SP (service provider) 1 The SP value of the upper period.
9. The method for automatically controlling a pressure swing adsorption process according to claim 1, further comprising:
automatic pressure regulation of the reverse air release buffer tank: and opening the analysis air pressure regulating valve to the lower limit of the opening value of the analysis air pressure regulating valve within T seconds when the reverse discharging process starts to operate, and automatically regulating the opening of the analysis air pressure regulating valve according to the analysis air pressure set value after the T seconds when the reverse discharging process starts to operate.
10. The method for automatically controlling a pressure swing adsorption process according to claim 1, further comprising:
the regulating valve is automatically switched: and (3) respectively adding a standby valve to the first average/final lift regulating valve, the reverse discharge regulating valve and the flushing regulating valve of the adsorption tower, judging whether the regulating valve fails according to a valve detection signal and whether actual pressure deviation in the adsorption tower meets the set pressure deviation requirement when the output value of the regulating valve does not meet the set value requirement, and switching to the corresponding standby valve when the regulating valve fails.
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