CN109407637B - Control method based on accurate positioning purging of gas heat exchanger of power plant DCS - Google Patents
Control method based on accurate positioning purging of gas heat exchanger of power plant DCS Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000010926 purge Methods 0.000 title claims description 95
- 238000007664 blowing Methods 0.000 claims abstract description 40
- 239000004071 soot Substances 0.000 claims abstract description 27
- 239000000428 dust Substances 0.000 claims abstract description 5
- 238000005259 measurement Methods 0.000 claims description 7
- 230000008021 deposition Effects 0.000 claims description 3
- 230000014759 maintenance of location Effects 0.000 claims description 2
- 238000010408 sweeping Methods 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 5
- 238000011217 control strategy Methods 0.000 abstract description 2
- 238000006073 displacement reaction Methods 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 12
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 7
- 239000003546 flue gas Substances 0.000 description 7
- 230000003111 delayed effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/418—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM]
- G05B19/4184—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM] characterised by fault tolerance, reliability of production system
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/32—Operator till task planning
- G05B2219/32015—Optimize, process management, optimize production line
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/02—Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
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Abstract
The invention discloses a gas heat exchanger accurate setting method based on a power plant DCS systemThe control method of the position blowing comprises a DCS system, a rotary gas-gas heat exchanger, a soot blowing device and a stepping control system, wherein a stepping control strategy is added in the DCS system of the power plant, so that the moving trolley of a soot blowing execution mechanism can accurately move, and a nozzle is aligned to each heat exchange element to perform steam vertical blowing; reference step S of machine to nozzle diameter due to soot blowing execution
The method has the advantages that a plurality of heat exchange elements cannot be directly blown in one blowing cycle, the method is adopted to circulate for X times in one time period and carry out X-1 times of integral displacement on blowing points, the full-vertical blowing of each point in the whole plane is realized, the design and positioning blowing time is adjustable, and the blowing strength control of each point in the whole plane is realized. The invention provides flexible and various blowing modes, effectively improves the blowing effect of the heat exchange element on accumulated dust blockage, and ensures the reliable operation of equipment.
Description
Technical Field
The invention relates to the field of coal-fired power generation, in particular to a control method for accurate positioning purging based on a power plant DCS system gas heat exchanger.
Background
At present, most of coal-fired power generating units in China are based on DCS (distributed control systems, DCS for short), air preheaters and raw desulfurization flue gas, the Gas-Gas heat exchanger for purifying flue Gas generally adopts a rotary Gas-Gas heat exchanger GGH (Gas Heater, the function of the GGH is to heat the desulfurized purified flue Gas by using the original flue Gas, so that the temperature of the flue Gas reaches above the dew point, the corrosion to a flue inlet and a chimney is reduced, the diffusivity of pollutants is improved, the temperature of the flue Gas entering an absorption tower is reduced, the technical requirement for corrosion prevention in the tower is reduced, the blockage of the heat exchanger is caused to increase due to the fact that dust and the like in tail flue Gas are retained on a heat exchange element during heat exchange, the differential pressure is increased, the steam adopted at present is used for on-line purging, and the control system is designed only from the aspect of soot blowing steam coverage, so that part of the heat exchange element cannot be effectively purged, and the blockage problem is caused. The design fully considers the conditions of various types of roadsters of the on-site soot blowing actuating mechanism, realizes the full-vertical purging method of the heat exchange element, and has very important significance for improving the purging effect.
Disclosure of Invention
The invention is designed to solve the technical problems and provides a control method for accurately positioning and purging a gas heat exchanger based on a power plant DCS.
The technical scheme adopted by the invention for solving the technical problems is as follows:
as shown in fig. 1, the blowing steam from the nozzle to the heat exchange element forms a blowing fan, the blowing effect is preferably the blowing part facing to the nozzle diameter range, because the reference step distance of the adopted sports car is larger than the diameter of the nozzle, some heat exchange elements are not directly blown, and the fixed point blowing has certain limitation, therefore, the accurate positioning purging is realized by adopting the X-time circulation purging mode in one time period, the method is that when the second to the Xth times of purging, the first step of advancing or retreating the roadster of the purging device is increased by S X1/X compared with the first step of the previous cycle, the steps from 2 to Nth move forward or retreats according to the reference step distance S, and so on, after a period of time, each heat exchange element in the plane can receive vertical purging of steam after X times of purging, and the times of purging X are related to the reference step pitch and the diameter of the nozzle of the sports car.
The design comprises the following steps:
and (I) a virtual feedback design is adopted to realize stepping and stepping backward stop.
Based on the DEVICE function of the DCS system, after a forward or backward command is sent, a feedback signal is sent after an execution mechanism moves in place or moves back, the DEVICE stops after receiving the in-place signal, and based on the function, a virtual in-place signal is designed in the forward or backward process, so that the step or step-back control of the soot blower sports car in the process is realized.
And (4) designing virtual feedback. The virtual feedback adopts an advance or retreat instruction to generate a virtual signal as a feedback signal after the delay time t through the delay module, and the delay time t is shown as follows.
t＝T-t2 (1)
t>t1 (2)
Wherein T is reference step S travel time, a control step or step back command of an operator module of the DCS system sends out '1', after T1 time, the contactor is closed to connect a sports car power supply, the command simultaneously passes through a delay module and generates a virtual feedback signal at delay time T, after the signal is received by a feedback pin of the operator module, the operator module outputs a command '1' to be reset to '0', the contactor is opened to disconnect the sports car power supply, the duration of the process is T, and the time T is obtained by testing the interval time from the closing of a relay contact on a DCS output DO board to the opening of the contactor to disconnect the power supply, and the unit is second; t1 is the time length from the time when the contactor closing instruction is sent to the time when the contactor is closed, and the unit is second; t2 is the time length from the generation of the virtual feedback to the disconnection of the contactor, and the unit is second; t1 and t2 are both actual measurement values.
And (II) accurate positioning purging design.
1. Reference step calculation
After the DCS instruction is sent out through actual measurement, the shortest time for switching on the contactor reliably and then switching off the contactor is the reference step pitch travel time T, and the travel of the running vehicle after the time T is the reference step pitch S.
(1) Reference step travel time T: t is the reference step S travel time, 1 is sent out from a control stepping or stepping reversing instruction, after T1 time, the contactor is closed and connected with the sports car power supply, the instruction is received by the operator module after virtual feedback is generated at delay time T through the delay module, after the instruction 1 is reset to 0, the contactor is opened and disconnected with the sports car power supply, the duration of the process is T, and the time T is obtained by testing the interval time from the closing of the relay contact on the DCS output DO terminal board to the opening of the contactor for controlling the opening of the power supply.
(2) Calculating a reference step distance S: the moving stroke of the running vehicle of the soot blowing execution device after the reference step pitch stroke time T can be measured in a field.
2. Precision purge control design
In order to realize vertical purging of the whole GGH heat exchange element, the design is to perform purging in a period of time by X times of circulation, wherein the purging in the X times of circulation is shown as follows.
X＝S/￠－1 (3)
Wherein X is the number of purging cycles within a certain period of time; s is a reference step pitch, and the unit is mm; phi is the diameter of the nozzle, and the unit is mm;
the stepping or stepping back mode is as follows:
the first purging is to step or retreat each step according to the reference step S until the end is limited.
During the second purging, the first step distance is S + S1/X, and the reference step distance S is kept from the second step to the Nth step until the end is limited; and S + S1/X is the travel of the sports car after the sports car stops running after the delay time t + t/X generates virtual feedback.
During the third purging, the first step distance is S + S × 2/X, and the reference step distance S is kept from the second step to the Nth step until the end limit is reached; and S + S2/X is a walking stroke of the sports car stopping running after the delay time t + t 2/X generates virtual feedback.
In the same way, when purging for the X time, the step distance is S + S (X-1)/X, and the reference step distance S is kept from the second step to the Nth step until the end is limited; wherein, S + S (X-1)/X is a walking stroke of the sports car which stops running after the delay time t + t (X-1)/X generates virtual feedback; and after the purging is finished, the purging is finished in the time period.
According to the control method for accurately positioning and purging the gas heat exchanger based on the power plant DCS, the reference step S is the travel of the sports car of the soot blowing execution device after the minimum step travel time T, and the reference step S is determined by the moving speed of the adopted sports car and the set delay time T for generating virtual feedback.
(III) variable purge time control of residence per step
The fixed value of each point purging time is the time of a circle of rotation of the rotary GGH gas-gas heat exchanger (the time is obtained through field actual measurement), in order to ensure the purging effect, a retention purging time multiple setting device is designed, the operator is provided with a fixed value 1 for increasing the fixed point purging time according to the change multiple of the blockage condition caused by actual dust deposition, and the purging intensity is enhanced.
According to the control method of the gas heat exchanger purging system based on the power plant DCS, after the soot blowing system is automatically controlled, purging is carried out for X times within a period of time, and purging can also be carried out for X times manually.
The invention has the advantages that the invention is suitable for the roadster control of various soot blowing systems to carry out accurate fixed point and carry out full vertical steam soot blowing of heat exchange elements, the control scheme considers the roadster control precision, provides selection of various soot blowing modes, provides a flexible and reliable mode for operators, provides support for improving the operation management level and has important significance for improving the safe, economical and stable operation of the unit.
Drawings
FIG. 1 is a control diagram of changing the number X of blowing points of the GGH heat exchanger into 2.
FIG. 2 is a schematic view of the soot blower carriage step back control configuration of the present invention.
FIG. 3 is a diagram of a delay time control configuration for the stride run of the present invention.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
As shown in fig. 2, the control method based on the purging system of the gas heat exchanger of the power plant DCS system of the present invention includes the following steps:
and (I) generating virtual feedback after delay to realize step back stop.
1. Control strategy
And (4) designing virtual feedback. The virtual feedback adopts an advance or retreat instruction to generate a virtual signal as a feedback signal after the delay time t through the delay module, and the delay time t is shown as follows.
t＝T-t2 (1)
t>t1 (2)
Wherein T is reference step S travel time, a control step or step back command of an operator module of the DCS system sends out '1', after T1 time, the contactor is closed to connect a sports car power supply, the command simultaneously passes through a delay module and generates a virtual feedback signal at delay time T, after the signal is received by a feedback pin of the operator module, the operator module outputs a command '1' to be reset to '0', the contactor is opened to disconnect the sports car power supply, the duration of the process is T, and the time T is obtained by testing the interval time from the closing of a relay contact on a DCS output DO board to the opening of the contactor to disconnect the power supply, and the unit is second; t1 is the time length from the time when the contactor closing instruction is sent to the time when the contactor is closed, and the unit is second; t2 is the time length from the generation of the virtual feedback to the disconnection of the contactor, and the unit is second; t1 and t2 are both actual measurement values.
2. Examples of the embodiments
As shown in fig. 2, after receiving a forward control instruction, the sootblower roadster moves to an end position, starts purging, purges for one purging period (the purging duration of the sootblower roadster is related to a set multiple), a pin "DMd 2" of a 001 module receives a step-back request and sends a step-back instruction, a 003 delay module receives the instruction information, the delay time of the 003 delay module is controlled by a 002 module, and after a delay time t, a virtual feedback signal is generated and sent to a feedback pin "FB 2" of the 001 module after being processed by 004 and the module, a 005 pulse module, 006 or the module, so as to reset a stop instruction, and a step-back instruction sending to a step-back instruction resetting process is completed; after a purging period, 001 receives the step-back requirement again and sends a step-back instruction, and so on; when the signal 001 receives the signal that it has actually moved back to the bit, one cycle of purging is complete.
And (II) accurate positioning purging design.
1. Reference step calculation
After the DCS instruction is sent out through actual measurement, the shortest time for switching on the contactor reliably and then switching off the contactor is the reference step pitch travel time T, and the travel of the running vehicle after the time T is the reference step pitch S.
(1) Reference step travel time T: t is the reference step S travel time, 1 is sent out from a control stepping or stepping reversing instruction, after T1 time, the contactor is closed and connected with the sports car power supply, the instruction is received by the operator module after virtual feedback is generated at delay time T through the delay module, after the instruction 1 is reset to 0, the contactor is opened and disconnected with the sports car power supply, the duration of the process is T, and the time T is obtained by testing the interval time from the closing of the relay contact on the DCS output DO terminal board to the opening of the contactor for controlling the opening of the power supply.
(2) Calculating a reference step distance S: the moving stroke of the running vehicle of the soot blowing execution device after the reference step pitch stroke time T can be measured in a field.
2. Precision purge control design
To achieve vertical purging of the entire GGH heat exchange element 22, the present design performs X cycles of purging over a period of time, as shown below.
X＝S/￠－1 (3)
Wherein X is the number of purging cycles within a certain period of time; s is a reference step pitch, and the unit is mm; phi is the diameter of the nozzle 21 in mm.
The stepping or stepping back mode is as follows:
the first purging is to step or retreat each step according to the reference step S until the end is limited.
During the second purging, the first step distance is S + S1/X, and the reference step distance S is kept from the second step to the Nth step until the end is limited; and S + S1/X is the travel of the sports car after the sports car stops running after the delay time t + t/X generates virtual feedback.
During the third purging, the first step distance is S + S × 2/X, and the reference step distance S is kept from the second step to the Nth step until the end limit is reached; and S + S2/X is a walking stroke of the sports car stopping running after the delay time t + t 2/X generates virtual feedback.
In the same way, when purging for the X time, the step distance is S + S (X-1)/X, and the reference step distance S is kept from the second step to the Nth step until the end is limited; wherein, S + S (X-1)/X is a walking stroke of the sports car which stops running after the delay time t + t (X-1)/X generates virtual feedback; and after the purging is finished, the purging is finished in the time period.
According to the control method for accurately positioning and purging the gas heat exchanger based on the power plant DCS, the reference step S is the travel of the sports car of the soot blowing execution device after the minimum step travel time T, and the reference step S is determined by the moving speed of the adopted sports car and the set delay time T for generating virtual feedback.
Examples
As shown in fig. 3, the number of times of purging in the present embodiment has been determined to be X-3, based on the reference pitch and the aperture of the nozzle 21.
(1) The first sootblowing cycle (X ═ 1).
The first step is delay time selection. The step pitch of the first purging cycle is moved according to the reference step pitch for purging, so that the delay time of the first step is designed to be the same as that of other steps, and the method for implementing the method comprises the following steps: when the operation signal is effective for selecting the steam soot blowing and the program control, the 2 signals are output to be 1 after passing through the 102 and module and are sent to the 104 pulse counting module, when the 104 module receives the signal for the first time, the output pin Y of the 104 module outputs 1, the values are respectively sent to the 105, 106 and 107 comparison modules, the 105 comparison module meets the condition of output 1, the output pin Z1 of the 108 multi-selection module is sent, the delay time of the first step of the first purging cycle is selected to be 0.5, and the delay time is sent to the 109 selection module X1 pin.
Before the sports car starts the first step of the first cycle, the delay time t of the first step is sent to a delay module for generating virtual feedback, and the implementation method comprises the following steps: the steam soot blowing and program control are carried out, when the operation signal is valid, the operation signal is output to be 1 through the 102 and module, the operation signal and the in-place valid signal of the front end limit switch are sent to the 113 pulse counting module to output 1 through the 110 pulse module, the 111 and module and the 112 pulse module, the judgment condition of the 119 comparison module is that the output pin D is 1, the output pin D is sent to the pin Z of the 109 selection module, the 109 selection module selects the value 0.5 of the pin X1 to be sent to the 101, and then the output pin is sent to the delay time pin of the delay module generating the virtual feedback, namely, the delay time of the first step of the delay module is preset in advance.
The delay time from the second step to the Nth step is set, and the implementation method comprises the following steps: after a first-step control instruction is sent out, the signal generates a reset signal through a 115 pulse counting module, a 117 comparison module and a 118 delay setting module and is sent to a 113 pulse counting module, the counting is set to be 0, the 119 comparison module condition is not met, an output pin of the signal is 0 and is sent to a 109 selection module, the value of an output pin Y of the 109 selection module is 0.5 of the value of the pin X2 of the module, namely after first-step stroke control is completed, the delay time of a reference step pitch stroke is sent to a 002 delay module in fig. 2 through a 101 module before a second step is started, and the next step retreating stroke is taken as a reference stroke; when the first soot blowing cycle is stepped back to the end position (intermediate limit switch signal), the pulse count module of the back command 115 is reset in preparation for selecting the delay time of the second step for the next cycle.
(2) The second sootblowing cycle (X ═ 2).
The first step is delay time selection. The first step of the second purge cycle is purged by a movement of S X1/X more than the first step of the first purge cycle, whereby the delay time of the first step is increased by t/X accordingly, by: when the operation signal is valid, the 2 signals are output to be 1 after passing through the 102 and module and are sent to the 104 pulse counting module, when the 104 module receives the signals again, the output of the output pin Y is changed to be 2, the values are respectively sent to the 105, 106 and 107 comparison modules, the 106 comparison module meets the condition of output 1, the signals are sent to the 108 multi-selection module pin Z2, and the delay time of the first step of the second purging cycle is selected to be 0.625 and sent to 109 selection module X1 pins.
Before the first step of the second cycle of starting moving of the sports car, the delay time t of the first step is sent to a delay module for generating virtual feedback, and the implementation method comprises the following steps: when the steam soot blowing and the program control are carried out again, the operation signal is effective and is output to '1' through the 102 and module, the in-place effective signal of the operation signal and the front end limit switch is sent to the 113 pulse counting module to output to '1' through the 110 pulse module, the 111 and module and the 112 pulse module, the pin 'Z' of the 109 selection module is sent after the 119 comparison module judges that the condition meets the condition that the output pin 'D' is 1, the value 0.625 of the 109 selection module pin 'X1' is sent to 101 and then is sent to the delay time pin of the delay module generating the virtual feedback, namely, the delay time of the first step of the backstepping is preset in advance.
The delay time from the second step to the Nth step is set, and the implementation method comprises the following steps: after a first-step control instruction is sent out, the signal generates a reset signal through a 115 pulse counting module, a 117 comparison module and a 118 delay setting module and is sent to a 113 pulse counting module, the counting is set to be 0, the 119 comparison module condition is not met, an output pin of the signal is 0 and is sent to a 109 selection module, the value of the output pin Y of the 109 selection module is 0.5 of the value of the pin X2 of the module, namely after first-step stroke control is completed, the delay time of a reference step pitch stroke is sent to a 002 delay module in fig. 2 through a 101 module before a second step is started, and the next step retreating stroke is taken as a reference stroke; when the second soot blowing cycle is stepped back to the end position (intermediate limit switch signal), the pulse count module of the back command 115 is reset in preparation for selecting the delay time of the second step for the next cycle.
(2) The third sootblowing cycle (X ═ 3).
The first step is delay time selection. The first step of the third purge cycle is purged at a rate of more than the first step of the second purge cycle by a ratio of S X1/X, i.e., the first step of the third purge cycle is purged at a rate of more than the first step of the first purge cycle by a ratio of S X2/X, and therefore, the delay time of the first step is increased by a ratio of t X2/X, which is performed by: when the 3 rd selection is used for steam soot blowing and program control, the operation signal is valid, the 2 signals are output to be 1 after passing through the 102 and module and are sent to the 104 pulse counting module, when the 104 module receives the signals again, the output of the output pin Y is changed into 3, the values are respectively sent to the 105, 106 and 107 comparison modules, the 107 comparison module meets the condition of outputting 1, the signals are sent to the 108 multi-selection module pin Z3, and the delay time of the first step of the third blowing cycle is selected to be 0.75 and is sent to 109 selection module X1 pins.
Before the first step of the third cycle of starting moving of the sports car, the delay time t of the first step is sent to a delay module for generating virtual feedback, and the implementation method comprises the following steps: when the steam soot blowing and the program control are carried out again, the operation signal is effective and is output to '1' through the 102 and module, the in-place effective signal of the operation signal and the front end limit switch is sent to the 113 pulse counting module to output to '1' through the 110 pulse module, the 111 and module and the 112 pulse module, the judgment condition of the 119 comparison module is that the output pin 'D' is 1, the output pin 'D' is sent to the pin 'Z' of the 109 selection module, the value 0.75 of the module pin 'X1' selected by the 109 is sent to the 101 and then is sent to the delay time pin of the delay module generating the virtual feedback, namely, the delay time of the first step of the backstepping is preset in advance.
The delay time from the second step to the Nth step is set, and the implementation method comprises the following steps: after a first-step control instruction is sent out, the signal generates a reset signal through a 115 pulse counting module, a 117 comparison module and a 118 delay setting module and is sent to a 113 pulse counting module, the counting is set to be 0, the 119 comparison module condition is not met, an output pin of the signal is 0 and is sent to a 109 selection module, the value of the output pin Y of the 109 selection module is 0.5 of the value of the pin X2 of the module, namely after first-step stroke control is completed, the delay time of a reference step pitch stroke is sent to a 002 delay module in fig. 2 through a 101 module before a second step is started, and the next step retreating stroke is taken as a reference stroke; when the third soot blowing cycle is stepped back to the end position (intermediate limit switch signal), the pulse counting module of the back command 115 is reset to prepare for selecting the delay time of the second step for the next cycle.
After the cycle is finished, a module pin D is compared with a module pin D of 1 and a soot blowing program control blowing end signal of 107 is effectively calculated by a module and 103, the signal is sent to a pulse counting module pin Rst of 104, and the module outputs Y of 3, and the signal is reset and is then set to 0.
The cycle will be executed again when soot blowing for the next time period is started.
(III) variable purge time control of residence per step
1. Purge strength control
The method mainly comprises the following steps of increasing the purging time: the fixed value of each point purging time is the time of one circle of rotation of the rotary gas-gas heat exchanger (the time is obtained through field actual measurement), in order to ensure the purging effect, a time multiple setter is designed, the time is changed according to the blockage condition caused by actual dust deposition for operators, the fixed point purging time is increased (normally designed to be a fixed value 1), and the time can be changed in the purging process so as to enhance the purging intensity of any area.
2. Examples of the embodiments
The time setting method comprises the following steps: according to fig. 2, the operator can set the 015 setting module by setting the purge time multiple by operating the screen, and multiplying the value by the 013 multiplication module as the delayed set time of the 016 delayed set module.
This time is used as a judgment for restarting the retirement instruction. The implementation method comprises the following steps: the returned step-back instruction is low level '0', the signal is high level '1' through the 012 non-module, the signal is sent to the 016 delay setting module, the delay time of the 016 delay setting module is purging time, when the delay setting time condition is met, the high level signal is sent out to the 001 operation module as a step-back signal after passing through 017 or modules, 018 or modules, so that the 001 operation module sends the step-back instruction again.
The present invention is not limited to the above-mentioned preferred embodiments, and any other products similar or identical to the present invention, which can be obtained by anyone based on the teaching of the present invention, fall within the protection scope of the present invention.
Claims (3)
1. A control method based on accurate positioning purging of a gas heat exchanger of a power plant DCS system comprises a distributed control system DCS, a rotary gas-gas heat exchanger, a soot blower and a stepping control system, wherein a sports car drives a nozzle (21) to move, and the nozzle (21) is purged by aiming at a heat exchange element (22); the method is characterized in that: a stepping control system is added in a distributed control system DCS of a power plant to control a roadster in a rotary gas-gas heat exchanger to accurately move, so that a nozzle (21) is aligned to each heat exchange element (22) to perform steam purging, and the vertical steam purging is performed on the heat exchange elements of the whole rotary gas-gas heat exchanger, wherein the full-vertical purging of each point in the whole plane is realized by adopting a mode of circulating for X times in a time period and integrally shifting a purging point for X-1 times, and the X-time circulating purging is as shown below;
wherein X is a blow over a certain period of timeThe number of sweeping cycles; s is a reference step pitch, and the unit is mm;
nozzle diameter in mm;
the stepping or stepping back mode is as follows:
the first purging is to step or retreat each step according to the reference step S until the tail end is limited;
during the second purging, the first step distance is S + S1/X, and the reference step distance S is kept from the second step to the Nth step until the end is limited; the S + S1/X is a travel route of the sports car after the sports car stops running after virtual feedback is generated after the delay time t + t/X;
during the third purging, the first step distance is S + S × 2/X, and the reference step distance S is kept from the second step to the Nth step until the end limit is reached; wherein, S + S2/X is a walking stroke of the sports car stopping running after the delay time t + t 2/X generates virtual feedback;
in the same way, when purging for the X time, the step distance is S + S (X-1)/X, and the reference step distance S is kept from the second step to the Nth step until the end is limited; wherein, S + S (X-1)/X is a walking stroke of the sports car which stops running after the delay time t + t (X-1)/X generates virtual feedback; after the purging is finished, the purging is finished in the time period;
the virtual feedback adopts an advance or retreat instruction to generate a virtual signal as a feedback signal after a delay time t through a delay module, wherein the delay time t is as shown below;
t＝T-t2 [1]
t>t1 [2]
wherein T is reference step S travel time, a control step or step back command of an operator module of the DCS system sends out '1', after T1 time, the contactor is closed to connect a sports car power supply, the command simultaneously passes through a delay module and generates a virtual feedback signal at delay time T, after the signal is received by a feedback pin of the operator module, the operator module outputs a command '1' to be reset to '0', the contactor is opened to disconnect the sports car power supply, the duration of the process is T, and the time T is obtained by testing the interval time from the closing of a relay contact on a DCS output DO board to the opening of the contactor to disconnect the power supply, and the unit is second; t1 is the time length from the time when the contactor closing instruction is sent to the time when the contactor is closed, and the unit is second; t2 is the time length from the generation of the virtual feedback to the disconnection of the contactor, and the unit is second; t1 and t2 are both actual measurement values.
2. The control method based on accurate positioning and purging of the gas heat exchanger of the power plant DCS system according to claim 1, characterized by comprising the following steps: the reference step S is the travel of the sports car of the soot blowing executing device after the minimum step travel time T, and is determined by the moving speed of the adopted sports car and the delay time T for generating virtual feedback.
3. The control method based on accurate positioning and purging of the gas heat exchanger of the power plant DCS system according to claim 1, characterized by comprising the following steps: the staying and purging time of each step is controlled by a stepping control system, and the duration is variable; the fixed value of each point of purging time is the time for the rotary gas-gas heat exchanger to rotate for one circle, the stepping control system is provided with a retention purging time multiple setter, and operators can change the multiple according to the blockage condition caused by actual dust deposition, and increase the fixed point purging time so as to enhance the purging intensity.
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