CN103170233B - Method for improving reliability and availability of limestone-gypsum flue gas desulfurization system - Google Patents
Method for improving reliability and availability of limestone-gypsum flue gas desulfurization system Download PDFInfo
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- CN103170233B CN103170233B CN201310071483.XA CN201310071483A CN103170233B CN 103170233 B CN103170233 B CN 103170233B CN 201310071483 A CN201310071483 A CN 201310071483A CN 103170233 B CN103170233 B CN 103170233B
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Abstract
The invention discloses a method for improving the reliability and the availability of a limestone-gypsum flue gas desulfurization system. The desulfurization system is composed of a DCS control apparatus and a desulfurization apparatus; the DCS control apparatus is connected with the detection/control points of the desulfurization apparatus through I/O interfaces in a one-to-one correspondence mode, inputs the analog/switch value condition signal of the desulfurization apparatus, and outputs the analog/switch value control signal of the desulfurization apparatus; a '3+1' sensor detection technology of an important analog/switch value input signal is provided against the desulfurization system reliability decrease caused by the blocking of desulfurization reactants to a sensor; an important switch value output signal adopts an independent-channel isolation output assembly and output signal feedback confirm technology, and simultaneously interlock/protection and detection station sensors are independently arranged; and the comprehensive application of the above technologies improves the reliability of the desulfurization system. An emergent degraded running program is started when the partial failure of the desulfurization apparatus appears, and the application of an auto disturbances rejection controller is combined to improve the availability of the apparatus.
Description
technical field
The present invention relates to a kind of wet method limestone-gypsum flue gas desulfurizing method that improves, refer to especially base oneself upon existing thermoelectricity wet method limestone-gypsum flue gas desulfurizing device, improve desulphurization system reliabilty and availability control technology.
background technology
Nineteen ninety-five, the SO of China
2discharge capacity leaps to the first in the world, up to 2,370 ten thousand tons; 90% of coal-fired contribution total emission volumn, 54% in discharge capacity is derived from again Thermal Power Generation Industry; Developed country goes through century-old environmental problem and is concentrated into 20 years concentrated breaking out in China, occurs serious SO
2the atmosphere pollution such as acid rain, fine grained flue dust and ozone, and progressively develop into the national pollution except minority area, Tibet, environment situation is unprecedentedly severe; The Economic Development Mode that surmounts environmental bearing capacity is hard to carry on, has also deviated from the vision of the friendly type of built environment, conservation-minded society.Nineteen ninety-five " The Law of the People's Republic of China on the Prevention and Control of Atmospheric Pollution " of revision points out: thermal power plant and other large and medium-sized enterprise of in acid rain control district and sulfur dioxide pollution control zone, discharging sulfur dioxide, belong to grassroot project and can not adopt low-sulfur coal, must build supporting desulfurization, dust arrester or take other to control the measure of sulfur dioxide (SO2) emissions, dedusting, belong to built enterprise and control sulfur dioxide (SO2) emissions, dust suppression without should adopting of low-sulfur coal, country encourages enterprise to adopt advanced desulfurization, dedusting technology." anti-therapy " embody be national will, representative be that the people thirsts for the heartfelt wishes of " blue sky and white cloud ".Within 2003, promulgate " fossil-fuel power plant atmospheric pollutant emission standard " (GB13223-2003); Since then, state's laws, the large system of national standard two have been brought in the reduction of discharging smelting dirt of Thermal Power Generation Industry into, sail that there are laws to abide by, have the governed fast railway of standard into.
Nineteen ninety-five, 1.6 hundred million kilowatts of the installed capacitys of China's thermoelectricity, reach 6.03 hundred million kilowatts for 2009; SO
2discharge capacity is but down to 2214.4 ten thousand tons in 2009 from 2,370 ten thousand tons of peak values of nineteen ninety-five.Although SO
2total emission volumn only slightly declines, and assesses but be placed under the background that the same period, economic total volume doubled, and this is a marvelous huge achievement beyond doubt; Wherein Thermal Power Generation Industry plays a pivotal role! 2009, thermoelectricity flue gas desulfurization installation surpassed 4.0 hundred million kilowatts, accounts for 70% of coal Denso machine total capacity, thermoelectricity discharge SO
29480000 tons, be down to 42.81% of total release, the target that 1 year in advance Eleventh Five-Year Plan up to standard end electric power total emission volumn is 951.7 ten thousand tons.In July, 2007, general office of National Development and Reform Committee corrects [2007] No. 1570 literary compositions of ring money together with general office of State Environmental Protection Administration to send out, and has printed and distributed " carrying out the pilot work scheme of flue gas desulfurization franchise operation about thermal power plant "; 2010, national desulphurization denitration industry and enterprise add up to 70～80; 6,000,000,000 yuan of annual value of production, increase by 10% in 2009 on year-on-year basis.
The flue gas desulfurization research of developed country starts from twentieth century sixties, develop complete industrialization Desulfurization Techniques in Coal Burning Power Plants the seventies, what take the lead in applying FGD (Flue gas desulphuration) device is Japan, and the thermoelectricity sulfur removal technology of developed country's main flow is wet method limestone-gypsum method.The imported technology of the flue gas desulfur device of domestic thermoelectricity based on Europe, the U.S. and Japan, the supporting two cover desulfurizers of the Chongqing 2 × 360MW of industrial group of Introduced from Japan Mitsubishi Heavy Industries Ltd of Luo Huang power plant unit in 1992, equipment investment, up to 3,660 ten thousand dollars, have been started the beginning of China's thermoelectricity Introduced From Abroad desulfur technology; The introduction, digestion, the absorption that last 20 years, innovate, except the import of still needing of minority key equipment, China has had device fabrication, the system integration, the operation maintenance technology of thermoelectricity wet method limestone-gypsum desulfurizer at present again; The desulfur technology of introducing on basis is innovated again, also obtains original achievement.Thermoelectricity coal desulfurization both can, before burning in (gas/liquid of coal washing or coal etc.), burning (capturing sulfur briquette and CFBC etc.), also can be implemented (high energy electron active oxidation method, charged dry powder gunite, limestone-gypsum method etc.) after burning; Up to now, the prevailing flue gas desulfurization being still after burning in thermoelectricity coal desulfurization field.Flue gas desulfurization after burning can be further subdivided into wet, half-dried and dry method three classes, wet method limestone-gypsum doctor treatment accounts for 85% left and right of global FGD device, be the sulfur removal technology that technology is the most ripe in the world at present, application achievement is maximum, operation conditions is the most stable, industrialized history run reaches more than 30 years; The thermoelectricity Techniques of Desulfurization for Burning Coal of China is synchronizeed with international, ends in December, 2011, puts into operation, in the flue gas desulphurization project of building and signed a contract, and wet method limestone-gypsum desulfurization proportion reaches more than 90%.In a word, expected reasonable time in, wet method limestone-gypsum flue gas desulfurizing is undoubtedly the absolute leader in market.
The investment of thermoelectricity wet method limestone-gypsum desulfurizer is several hundred million easily, and device operation needs to consume a large amount of high manpower and materials of valuable electric energy, price paid; Effect of how bringing into play to greatest extent desulfurizer is Thermal Power Generation Industry, desulfurization specialized company and a related scientific research personnel difficult problem urgently to be resolved hurrily.6 years service datas of comprehensive our factory 4 × 600MW unit wet method limestone-gypsum desulfurizer, be not difficult to find that the actual operating state of desulfurizer and design objective are far apart, especially the high availability index of the high reliability of automation control system, desulfurizer is barely satisfactory: when desulfurizer puts into operation, control system is normal, along with the passing of running time, the quality of control system go from bad to worse; Often be forced to cut manual mode--the operation of manual control desulfurizer, the desulfurizer of even stopping transport--thermoelectricity smoke directly ventilating atmosphere.Analyze the fault data that gathers over the years, be not difficult to find major failure point neither desulfurizer, also noncontrol system main frame (DCS); And in the time obtaining desulfurizer operational factor, occurred problem, cannot guarantee to gather the high reliability of crucial operational factor sensor, and effective execution of control system output order, wherein the reliability of the crucial switching value of control system output is particularly important.Analysis shows: sensor self is also reliably, and the final root of fault is pointed to Cabase compound (lime/lime stone) and SO
2product after reaction desulfuration--gypsum dirt, black dirt, calcium sulfite and crystal of calcium sulfate, calcium-based desulfurization reactant has stopped up sensor, and this is the inherent shortcoming of wet type calcium-based desulfurization technique; The thermal coal kind of power plants is numerous and diverse, sulfur content is higher, and the coal shortage in recent years taking place frequently causes thermal power plant's " famine is not selected coal ", has occurred on certain degree out of control if the defect of developed country's wet type calcium-based desulfurization technique is still in controllable state, China; The external technology " not acclimatized " of introducing, must carry out secondary development for the specific national conditions of China, guarantee desulphurization system highly reliable and high available.
Further analyze and show: the crucial actuator of control device--the reliability that is mainly some switching value actuator signal has much room for improvement, and the reliability that improves above-mentioned switching value actuator signal contributes to the reliability of desulphurization system to attain a yet higher goal.Meanwhile, the widely used PID controller of industrial quarters, in the face of non-linear, large dead time object, is controlled quality often not ideal enough; The substitute of research and development PID controller is necessary.
The raising of quality of the life, traditional FGD security intension (inherently safe of FGD system and boiler unit safety) is necessary to grow with each passing hour, and increases the content of Environmental security on former security intension basis.Therefore, once there is local fault in FGD, should simply not stop transport desulfurizer, gas bypass discharging directly into atmosphere; As long as condition license, FGD should maintain degraded running, and take measures to do everything possible up to standard or approach qualified discharge, improve the availability of FGD device.
The improvement design of basing oneself upon wet flue gas desulfurization technique has obtained certain effect.The improvement that research work that what something lost was shaken is is confined to desulfurizing agent, the improvement of desulfuration spray tower structure, the real-time monitoring of coal-firing units gas desulfurization, do not relate to the method that improves wet method limestone-gypsum flue gas desulfurizing system reliability and availability, the present invention is intended to fill this class.At present, more representational intellectual property Summary on research results is as follows:
Patent of invention " desulfurizing method of exhaust gas and device " (patent No. ZL01118582.1), proposes to utilize electrolytic chlorination sodium solution to produce sulfur method and the device of NaOH as desulfurizing agent.
Patent of invention " a kind of spray column for flue gas desulfurization and operation method thereof " (patent No. ZL 200710123020.8), the method that proposes to remove the cylindrical spray column of sulfur dioxide in flue gas and remove sulfur dioxide in flue gas by described spray column.
Patent of invention " wet desulfurizer for thermal power plant and sulfur method thereof " (application number 201010555685.8), proposes in saturated absorption liquid, to add adipic acid, the SO of power-plant flue gas while realizing coal type change
2concentration qualified discharge, and the operation of the economical and energy saving of desulphurization system.
Patent of invention " control method wet method smoke desulfur for elecric power plant " (patent No. ZL200510095411.4), the operation number of units (recycle slurry liquid measure) that proposes adjustment absorption tower circulating pump realizes the automation control of flue gas desulphurization system, adjusts the method for the movable vane angle control booster fan of booster fan.
Patent of invention " coal-firing units gas desulfurization is monitored and information management system in real time " (patent No. ZL 200710025402.7), the digital management of the overall process such as propose collection, transmission, processing, calculating, analysis, issue by heat-engine plant desulfurized system online data, share, build a set of online monitoring system based on Web structure, real-time communication, heat-engine plant desulfurized facility operation is implemented to long-acting management.
Above-mentioned benefiting our pursuits, has proposed the improvement of desulfurizing agent, the improvement of desulfuration spray tower structure, the real-time monitoring of coal-firing units gas desulfurization, has certain reference value, still has limitation but explore achievement; Therefore, be necessary based on wet method limestone-gypsum flue gas desulfurizing technique, on the basis of existing achievement in research, do deep research and innovation, improve the reliabilty and availability of wet method limestone-gypsum flue gas desulfurizing system.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, a kind of method that improves limestone-gypsum flue gas desulfurizing system reliability and availability is provided.
The method that improves limestone-gypsum flue gas desulfurizing system reliability and availability is to adopt the desulphurization system being made up of DCS control device and desulfurizer, the main frame of control device is that the I/A Series DCS of FOXBORO company controls dress, DCS control device is detection/control point corresponding being connected one by one with desulfurizer through I/O interface, simulation/switching value working condition signal of input desulfurizer, simulation/switching value control signal of output desulfurizer;
Desulfurizer comprises lime stone bunker, wet ball mill, slurries cyclone, ball mill slurries recycling tank, lime stone slurry case, absorption tower, spray equipment, gypsum dewatering equipment, chimney lime stone slurry circulating pump, oxidation fan, demister; Lime stone bunker, wet ball mill, slurries cyclone, lime stone slurry case, absorption tower, chimney are connected in turn, slurries cyclone bottom, ball mill slurries recycling tank, wet ball mill are connected in turn, top, absorption tower is provided with demister, spray equipment, lime stone slurry circulating pump is connected with bottom, absorption tower through spray equipment, and gypsum dewatering equipment, oxidation fan are connected with bottom, absorption tower;
SO in flue gas
2in absorption tower, remove, the former flue gas that boiler generates through booster fan enter that absorption tower, baffling upwards fully contact with sprayed slurry, flue gas is cooling and reach capacity by slurries, the SO in flue gas
2, SO
3, HCL, HF acid ingredient be absorbed, the more two-layer zigzag demister of flowing through is removed contained droplet; Washing and purify after flue gas derive from absorption tower, by clean flue from smoke stack emission; Bottom, absorption tower stock tank collects the bisulfite HSO that reaction generates
3 -, HSO
3 -the air oxygen that oxidized blower fan blasts changes into SO
4 2-, SO
4 2-with Ca
2+reaction generates calcium sulfate CaSO
4, CaSO
4crystallization is gypsum CaSO
42H
2o, the pH value of bottom stock tank maintains between 5.2-5.6; A slurries part that contains gypsum, dust and impurity enters gypsum dewatering equipment through plaster slurry pump, and all the other slurries return to absorption tower cycling and reutilization; Flushing water equipment in absorption tower is regularly implemented to rinse, and prevents that gypsum, dust and other solids in droplet from stopping up the pipeline on absorption tower;
Flue gas through booster fan, flue, enter desulfurizer under the guiding of import and export/by-pass damper, and by-pass damper is arranged on flue collector; Once desulfurizer breaks down, by the switching of import and export/by-pass damper, eliminate the impact of fault on boiler operatiopn; When boiler startup and desulfurizer break down, import and export baffle door is closed, and opens by-pass damper door, and untreated flue gas directly enters chimney and enters atmosphere;
The lime stone of particle diameter 0.1～20mm enters wet ball mill and adds water and grind to form the slurries that solid contents is 30% left and right, slurries suitable granularity are delivered to lime stone slurry case by slurries cyclone, and the slurries of isolated coarsegrain enter ball mill slurries recycling tank, return to wet ball mill; Slurries in lime stone slurry case are sent to absorption tower by lime stone slurry delivery pump, regulate the limestone slurry liquid measure or the absorption tower that enter absorption tower to discharge concentration of slurry, can make absorption tower stock tank pH value maintain between 5.2-5.6, guarantee dissolving and the SO of lime stone
2efficient absorption;
The dihydrate gypsum slurries that in absorption tower, desulphurization reaction generates are sent into gypsum dewatering equipment through plaster slurry pump, first dewatered by the gypsum hydrocyclone of gypsum dewatering equipment, cyclone underflow slurries flow into gypsum slurries distributor box, vacuum belt dewaterer dehydration, last dehydrated gypsum is delivered to gypsum warehouse storage by multipoint mode unloader, cyclone overflow simultaneously flows into cyclone spill box, certainly flow to return water tank;
DCS control device amounts to 5526 I/O points of configuration; Desulfurization duct is established 78 I/O points, and important AI point is gas approach temperature point, former flue gas pressures measuring point; Important DI point is the on off state of inlet baffle; Important DO point is by-pass damper, inlet baffle, outlet damper; The pressure-measuring-point that the important AI point of booster fan is booster fan; DCS Fieldbus Components FBM adopts the fieldbus FCM10E connected mode of redundancy, realizes the collection of desulphurization control device input/output signal, A/D, D/A conversion, troubleshooting and photoelectricity isolation; Relay cabinet is realized the isolation of desulphurization control device digital output signal, and power distribution cabinet is realized the distribution of control system; The input signal of the important simulation/switching value of control device adopts " 3+1 " sensor method, important switching value output signal adopts passage independently to isolate the method for output precision, feedback acknowledgment output signal, and interlocking/protection simultaneously and detection measuring point sensor carry out independent setting; Key control loop adopts automatic disturbance rejection controller, when local fault appears in desulfurizer, start emergent degraded running program.
The method that the important analog signals measuring point of described control device adopts " 3+1 " analog quantity to detect is: take the inlet pressure of booster fan as example, the first pressure sensing transmitter, the second pressure sensing transmitter, the 3rd pressure sensing transmitter, the 4th pressure sensing transmitter gather the inlet pressure of booster fan, and sensor location is at the front end of booster fan entrance, arrange in vertical direction with flue gas travel line; The enforcement logic of sensor is as follows: the 4th pressure sensing transmitter with protective cover is in holding state, other 3 pressure sensing transmitter examinations, and testing result is by " three get all " output; The detection error absolute value of and if only if 3 pressure sensing transmitters
while being greater than preset value E, warning, testing result is by " three get in " output, after operator confirms, standby the 4th pressure sensing transmitter protective cover start detection that comes off; Take the 4th pressure sensing transmitter as benchmark, proceed to " two get all " output together with the median of the detected value of standby sensor and other 3 pressure sensing transmitters.
The method that the important switching value signal of described control device measuring point adopts " 3+1 " sensor to detect is: the state of each important switching value is all installed the collection of 4 pressure sensing transmitters, the 4th pressure sensing transmitter with protective cover is in holding state, other 3 pressure sensing transmitter examinations; The switching value gathering is when consistent, by " three select three " regular output switch amount signal, when inconsistent, by " three select two " regular output switch amount signal, warning, after operator confirms, standby the 4th pressure sensing transmitter protective cover start detection that comes off; Take the 4th pressure sensing transmitter as benchmark, reject inconsistent sensor, proceed to new " three select three " or " three select two ".
The output signal of the described important switching value of control device adopts passage independently to isolate the method for digital output assembly, feedback acknowledgment output signal.
The sensor of described interlocking/protection measurements and detection measuring point adopts the independent method arranging.
When local fault appears in described system, abandon the method for simple stoppage in transit desulfurizer, gas bypass discharging directly into atmosphere, alternative solution comprises the steps:
1) switch power coal--use the low-sulfur clean coal, up to standard as far as possible or approach qualified discharge of high price instead, every limited low-sulfur clean coal coal bunker of unit configuration reserves conventionally, the emergent need in short-term during for desulfurizer fault;
2) when low-sulfur clean coal is difficult to support, trigger removal of load (Run Back) mechanism, unit load promptly drops to SO according to the speed of 30MW/MIN to unit
2while not exceeding standard, manually finish to stop, guarantee the safe and reliable operation of boiler unit, maintain the use of the basic function of desulphurization system simultaneously; After relevant spot check is confirmed, pull on load up value and generate electricity.
The present invention is by " 3+1 " sensor detecting of important analog signal, " 3+1 " sensor detecting method of important switching signal; Important switching value output signal adopts passage independently to isolate the method for output precision, feedback acknowledgment output signal, and the sensor of interlocking/protection measurements and detection measuring point adopts independent method to set up; Degraded running when local fault appears in desulfurizer, and adaptive capacity, control performance are better than the putting into operation of automatic disturbance rejection controller of PID; The integrated application of described method, has improved the reliabilty and availability of desulphurization system.
Accompanying drawing explanation
Fig. 1 improves wet method limestone-gypsum flue gas desulfurizing method flow chart;
Fig. 2 is layout drawing and the section of structure of booster fan inlet pressure analog quantity (AI) sensor;
Fig. 3 A is the logic chart of booster fan inlet pressure analog quantity (AI) " 3+1 " sensor;
Fig. 3 B is the logic chart of smoke inlet baffle plate switching value (DI) " 3+1 " sensor;
Fig. 4 is the driving figure of booster fan inlet pressure analog quantity (AI) " 3+1 " sensor;
Fig. 5 is that booster fan inlet pressure analog quantity detects, the control logic figure of interlocking/protection sensor;
Fig. 6 is import baffle plate, outlet damper, by-pass damper high-reliability output (DO) circuit diagram;
Degraded running schematic diagram when Fig. 7 is desulphurization system partial failure;
Fig. 8 is booster fan inlet pressure Active Disturbance Rejection Control schematic diagram.
The specific embodiment
As shown in Figure 1, the method that improves wet method limestone-gypsum flue gas desulfurizing system reliability and availability is to adopt the desulphurization system being made up of DCS control device and desulfurizer, the main frame of control device is that the I/A Series DCS of FOXBORO company controls dress, DCS controls and fills the 13 detection/control points through I/O interface and desulfurizer corresponding being connected one by one, simulation/switching value working condition signal of input desulfurizer, exports simulation/switching value control signal of desulfurizer;
Desulfurizer comprises lime stone bunker 1, wet ball mill 2, slurries cyclone 3, ball mill slurries recycling tank 4, lime stone slurry case 5, absorption tower 6, spray equipment 7, gypsum dewatering equipment 8, chimney 9 lime stone slurry circulating pumps 10, oxidation fan 11, demister 12; Lime stone bunker 1, wet ball mill 2, slurries cyclone 3, lime stone slurry case 5, absorption tower 6, chimney 9 are connected in turn, slurries cyclone 3 bottoms, ball mill slurries recycling tank 4, wet ball mill 2 are connected in turn, 6 tops, absorption tower are provided with demister 12, spray equipment 7, lime stone slurry circulating pump 10 is connected with 6 bottoms, absorption tower through spray equipment 7, and gypsum dewatering equipment 8, oxidation fan 11 are connected with 6 bottoms, absorption tower;
SO in flue gas
2in absorption tower, remove, the former flue gas that boiler generates through booster fan 60 enter that absorption tower 6, baffling upwards fully contact with sprayed slurry, flue gas is cooling and reach capacity by slurries, the SO in flue gas
2, SO
3, HCL, HF acid ingredient be absorbed, the more two-layer zigzag demister 12 of flowing through is removed contained droplet; Flue gas after washing and purification is derived from absorption tower, discharges from chimney 9 by clean flue; Bottom, absorption tower stock tank collects the bisulfite HSO that reaction generates
3 -, HSO
3 -the air oxygen that oxidized blower fan 11 blasts changes into SO
4 2-, SO
4 2-with Ca
2+reaction generates calcium sulfate CaSO
4, CaSO
4crystallization is gypsum CaSO
42H
2o, the pH value of bottom stock tank maintains between 5.2-5.6; A slurries part that contains gypsum, dust and impurity enters gypsum dewatering equipment 8 through plaster slurry pump, and all the other slurries return to absorption tower cycling and reutilization; Flushing water equipment in absorption tower is regularly implemented to rinse, and prevents that gypsum, dust and other solids in droplet from stopping up the pipeline on absorption tower;
Flue gas through booster fan 60, flue, enter desulfurizer under the guiding of import and export/by-pass damper, and by-pass damper is arranged on flue collector; Once desulfurizer breaks down, by the switching of import and export/by-pass damper, eliminate the impact of fault on boiler operatiopn; When boiler startup and desulfurizer break down, import and export baffle door is closed, and opens by-pass damper door, and untreated flue gas directly enters chimney 9 and enters atmosphere;
The lime stone of particle diameter 0.1～20mm enters wet ball mill 2 and adds water and grind to form the slurries that solid contents is 30% left and right, slurries suitable granularity are delivered to lime stone slurry case 5 by slurries cyclone 3, and the slurries of isolated coarsegrain enter ball mill slurries recycling tank 4, return to wet ball mill 2; Slurries in lime stone slurry case 5 are sent to absorption tower by lime stone slurry delivery pump, regulate the limestone slurry liquid measure or the absorption tower that enter absorption tower to discharge concentration of slurry, can make absorption tower stock tank pH value maintain between 5.2-5.6, guarantee dissolving and the SO of lime stone
2efficient absorption;
The dihydrate gypsum slurries that in absorption tower, desulphurization reaction generates are sent into gypsum dewatering equipment 8 through plaster slurry pump, first dewatered by the gypsum hydrocyclone of gypsum dewatering equipment 8, cyclone underflow slurries flow into gypsum slurries distributor box, vacuum belt dewaterer dehydration, last dehydrated gypsum is delivered to gypsum warehouse storage by multipoint mode unloader, cyclone overflow simultaneously flows into cyclone spill box, certainly flow to return water tank;
DCS control device amounts to 5526 I/O points of configuration; Desulfurization duct is established 78 I/O points, and important AI point is gas approach temperature point (being for No. Tag 10HTA10 CT001 ~ 003), former flue gas pressures measuring point (being for No. Tag 10HTA10 CP001 ~ 003); Important DI point be inlet baffle on off state (No. Tag for opening: 10HTA10 AA101 ZO, close: 10HTA10 AA101 ZC); Important DO point is that by-pass damper (is opened order No. Tag: 10HTA20 AA101 VO, 10HTA20 AA101 VC), inlet baffle (opens order No. Tag: 10HTA10 AA101 VO close No. Tag, order:, close order No. Tag: 10HTA10 AA101 VC), outlet damper (open order No. Tag: 10HTA30 AA101 VO, close order No. Tag: 10HTA30 AA101 VC); The pressure-measuring-point (being for No. Tag 10HTC10 CP001 ~ 004) that the important AI point of booster fan is booster fan.DCS Fieldbus Components FBM adopts the fieldbus FCM10E connected mode of redundancy, realizes the collection of desulphurization control device input/output signal, A/D, D/A conversion, troubleshooting and photoelectricity isolation; Relay cabinet is realized the isolation of desulphurization control device digital output signal, and power distribution cabinet is realized the distribution of control system; The input signal of the important simulation/switching value of control device adopts " 3+1 " sensor method, important switching value output signal adopts passage independently to isolate the high reliability technology of output precision, feedback acknowledgment output signal, interlocking/protection is independently set and detects measuring point sensor; Key control loop adopts automatic disturbance rejection controller, when local fault appears in desulfurizer, start emergent degraded running program.
The output signal of the described important switching value of control device adopts passage independently to isolate the method for digital output assembly, feedback acknowledgment output signal.
The sensor of described interlocking/protection measurements and detection measuring point adopts the independent method arranging.
When local fault appears in described system, abandon the method for simple stoppage in transit desulfurizer, gas bypass discharging directly into atmosphere, alternative solution comprises the steps:
1) switch power coal--use the low-sulfur clean coal, up to standard as far as possible or approach qualified discharge of high price instead, every limited low-sulfur clean coal coal bunker of unit configuration reserves conventionally, the emergent need in short-term during for desulfurizer fault;
2) when low-sulfur clean coal is difficult to support, trigger removal of load (Run Back) mechanism, unit load promptly drops to SO according to the speed of 30MW/MIN to unit
2while not exceeding standard, manually finish to stop, guarantee the safe and reliable operation of boiler unit, maintain the use of the basic function of desulphurization system simultaneously; After relevant spot check is confirmed, pull on load up value and generate electricity.
As shown in Figure 2, by 4 pressure sensing transmitters--the first pressure sensing transmitter 20, the second pressure sensing transmitter 30, the 3rd pressure sensing transmitter 40, the 4th pressure sensing transmitter 50(3051TA of Rosemount INC. (US) 12001 West 78th Street Prairie, Minnesota 55344 U.S.A. absolute pressure sensing transducer, be respectively 10HTC10 CP001 ~ 004 No. Tag) gathering the inlet pressure of booster fan, pressure sensing transmitter is distributed in the front end of booster fan 60 entrances, arranges in vertical direction with flue gas travel line; 3051TA pressure sensing transmitter integrates pressure sensor, signal to be processed and isolation diaphragm, the be respectively ± 0.15%F of verification range-1000～1000Pa, overall performance and precision that gauge pressure and absolute pressure are measured and ± 0.075%FS; 3051TA possesses stainless steel and Hastelloy C alloys R process isolation diaphragm, filling liquid are made up of silicone oil and inert oil, and the process that optional DIN matches with Autoclave is connected.When work, pressure is passed to filling liquid by the isolation diaphragm of high and low pressure side, and filling liquid reaches pressure on the pressure-sensitive diaphragm of center sensor again; Pressure-sensitive diaphragm is the flexible member of a tensioning, and its displacement is 0.004 inch (0.1 millimeter) with pressure variation, maximum displacement; The capacitor plate of both sides detects the position of pressure-sensitive diaphragm, and between pressure-sensitive diaphragm and capacitor plate, the difference of electric capacity is converted to corresponding curtage signal output.
As shown in Figure 3A, the important analog signals measuring point of described control device adopts " 3+1 " analog quantity detection technique, and each analog quantity is all installed the collection of 4 pressure sensing transmitters; Take the inlet pressure of booster fan as the enforcement logic of example, pressure sensing transmitter (abbreviation sensor) as follows: the 4th pressure sensing transmitter 50 (No. Tag as 10HTC10 CP004) with protective cover is in holding state, other 3 pressure sensing transmitters (being for No. Tag 10HTC10 CP001 ~ 003) examinations, testing result is carried out Sigsel output by " three get all " mode; The detection error absolute value of and if only if 3 sensors
while being greater than preset value E, warning, testing result is carried out Sigsel1 output by " three get in ", after operator confirms, standby the 4th pressure sensing transmitter 50 protective covers start detection that comes off; Take the 4th pressure sensing transmitter 50 as benchmark, proceed to " two get all " mode together with the median of the detected value of standby sensor and other 3 pressure sensing transmitters and carry out Sigsel2 output.In figure, T data processing block is handover module.
As shown in Figure 3 B, the acquisition process of important measuring point switching value signal and the acquisition process of important measuring point analog signals are followed same theory, and the technological means of employing is exactly the same; (No. Tag for opening: 10HTA10 AA101 ZO, pass: 10HTA10 AA101 ZC), the collection of 4 pressure sensing transmitters is also installed for the on off state of inlet baffle; The 4th pressure sensing transmitter with protective cover is in holding state, other 3 pressure sensing transmitter examinations; The switching value gathering is when consistent, by " three select three " regular output switch amount signal, when inconsistent, by " three select two " regular output switch amount signal, warning, after operator confirms, standby the 4th pressure sensing transmitter protective cover start detection that comes off; Take the 4th pressure sensing transmitter as benchmark, reject inconsistent sensor, proceed to new " three select three " or " three select two ".
As shown in Figure 4, in the time that in Fig. 3 A, signal processing block AL Output rusults is 1, through selecting logic to select, enable the pressure sensing transmitter under holding state; Drive relay to start magnetic valve and pneumatic operated valve, pneumatic operated valve is opened the protective cover of standby pressure sensing transmitter in positive interaction mode (being that protective cover comes off), inputs the former pressure sensing transducer signal in holding state; Take the 4th pressure sensing transmitter 50 as benchmark, proceed to " two get all " output together with the median of the detected value of standby sensor and other 3 pressure sensing transmitters.
As shown in Figure 5, figure a is that booster fan pressure sensor detects logic SAMA figure, the numerical value of inlet pressure measuring point feedback signal processing block Sigsel reads and shows at I place, flow through again restricted area and operator manually input setting value A carry out reading displayed and comparison, then superimposed with the feed-forward signal of boiler load, jointly produce with it a PID conditioning signal, control the propeller regulating mechanism of booster fan, make booster fan gas approach force value maintain setting value; Figure b is alarm signal logic chart, and the detection of pressure simulation amount is carried out signals collecting by three sensors, in the time being greater than 1000Pa and be less than-400Pa, being respectively high and reporting to the police and low warning; C figure is interlock protection logic SAMA figure, and wherein PB is interlocking resetting signal.Obviously, the sensor of interlocking/protection and detection measuring point is independent setting.
As shown in Figure 6, the fastener model adopting is the field bus FB M242 assembly of the I/A Series DCS of FOXBORO company, FBM242 digital output assembly adopts passage independently to isolate output, fastener external signal fault can not have influence on inner passage, and by equipment such as auxiliary reclay drive motor, valves, the working power of auxiliary reclay provides by exporting fastener.All auxiliary reclays at least provide two secondary SPDT contacts, DSO to have multiple output type, are applicable to respectively the modes such as relay output, colelctor electrode output.Protection action triggers is carried out after logical operation in DCS system through DO fastener; to FBM242 fastener output trip signal; order about the normally opened contact closure of relay by FBM242 internal logic circuit, thereby drive 380V motor to carry out corresponding switch machine work to the switch of import baffle plate, outlet damper, by-pass damper.Meanwhile, a DI switching value is set (No. Tag for opening: DIN1012304 XO, pass: DIN1012304 XC) read in DCS, access public terminal oC and terminal NO, in the time sending signal, detection voltage readings is 0V at output signal normally opened contact place; If do not send signal, detection voltage readings is 48V, to guarantee that signal really sends.Fieldbus is a kind of single main website bridging line serial data communication bus, uses synchronous communication standard.All on-site signals and the isolation of control electronic circuit, adopt transformer coupled and photoelectricity dual resisteance to analog input/output signal, and Qie Mei road A/D and D/A conversion independently, guarantee that fault is to systematic influence minimum.
As shown in Figure 7, on traditional FGD security intension (inherently safe of FGD device and boiler safety) basis, increase Environmental security: once local fault appears in FGD, abandon the solution of simple stoppage in transit desulfurizer, gas bypass discharging directly into atmosphere; Improve the availability of FGD device.First, switching power coal--use the low-sulfur clean coal of high price instead, do everything possible up to standard or approach qualified discharge, every unit configures the limited low-sulfur clean coal coal bunker of reserves conventionally, the need of meeting an urgent need in short-term during for desulfurizer fault; The second, when low-sulfur clean coal is difficult to support, trigger removal of load (Run Back) mechanism, unit load promptly drops to SO according to the speed of 30MW/MIN to unit
2while not exceeding standard, manually finish to stop, guarantee the safe and reliable operation of boiler unit, maintain the use of the basic function of desulphurization system simultaneously; After relevant spot check is confirmed, pull on load up value and generate electricity.
As shown in Figure 8, booster fan pressure has the features such as strong nonlinearity, parameter time varying, large inertia large dead time, close coupling, strong jamming, and the effectiveness of PID controller is barely satisfactory; This patent adopts automatic disturbance rejection controller, and active disturbance rejection had both retained PID " based on error concealment error ", the easy marrow of Project Realization, has improved again four large shortcomings of PID control strategy:
(1) directly get the error between setting value and output valve, usually make initial control make system action occur overshoot too greatly, cause the closed-loop system that PID controls to produce the contradiction between rapidity and overshoot.
(2) realization of differential signal needs to improve.On-the-spot differential signal adopts difference or lead network conventionally, and this mode is very large to noise amplification, makes differential signal distortion and can not use.
(3) forming PID controlled quentity controlled variable by ratio, differential and the integration of error signal, is the linear combination between them, and this combination is difficult for solving the contradiction of rapidity and overshoot, not necessarily optimum.
(4) effect of integration is mainly to eliminate steady-state error, but its introducing also brings a lot of side effects, as has increased the unstability of system, also easily causes integration saturated.
The core of automatic disturbance rejection controller technology is that the not modeling of system is dynamically all ascribed to " the total disturbance " to system and estimates and recompense with the unknown outer effect of disturbing.Automatic disturbance rejection controller is made up of three parts: Nonlinear Tracking Differentiator (TD), its effect is the differential signal that arranges transient process and provide process: extended state observer (ESO), its effect is the estimated value that provides Obj State variable estimated value and system model and disturb real-time summation effect outward, and the compensating action of this real-time estimated value makes controlled device turn to " integrator tandem type ": utilize nonlinear state Error Feedback (NLSEF) to control the object that is changed into " integrator tandem type ".
The second order automatic disturbance rejection controller algorithm of booster fan pressure is as follows:
Wherein
,
?
>
Wherein
for booster fan pressure set points,
with
for output error correcting gain,
,
respectively to arrange transient process
estimation with system
between error and differential thereof,
controlled quentity controlled variable gain compensation,
for index,
to distinguish
the boundary of size.
Claims (3)
1. one kind is improved the method for wet method limestone-gypsum flue gas desulfurizing system reliability and availability, it is characterized in that desulphurization system is made up of DCS control device and desulfurizer, the main frame of DCS control device is the I/A Series DCS control device of FOXBORO company, DCS control device (13) is detection/control point corresponding being connected one by one with desulfurizer through I/O interface, simulation/switching value working condition signal of input desulfurizer, simulation/switching value control signal of output desulfurizer;
Desulfurizer comprises lime stone bunker (1), wet ball mill (2), slurries cyclone (3), ball mill slurries recycling tank (4), lime stone slurry case (5), absorption tower (6), spray equipment (7), gypsum dewatering equipment (8), chimney (9), lime stone slurry circulating pump (10), oxidation fan (11), demister (12); Lime stone bunker (1), wet ball mill (2), slurries cyclone (3), lime stone slurry case (5), absorption tower (6), chimney (9) are connected in turn, slurries cyclone (3) bottom, ball mill slurries recycling tank (4), wet ball mill (2) are connected in turn, top, absorption tower (6) is provided with demister (12), spray equipment (7), lime stone slurry circulating pump (10) is connected with bottom, absorption tower (6) through spray equipment (7), and gypsum dewatering equipment (8), oxidation fan (11) are connected with bottom, absorption tower (6);
SO in flue gas
2in absorption tower, remove, the former flue gas that boiler generates enters absorption tower (6) through booster fan (60), and baffling upwards fully contacts with sprayed slurry, and flue gas is cooling and reach capacity by slurries, the SO in flue gas
2, SO
3, HCl, HF acid ingredient be absorbed, the more two-layer zigzag demister (12) of flowing through is removed contained droplet; Flue gas after washing and purification is derived from absorption tower, discharges from chimney (9) by clean flue; Bottom, absorption tower stock tank collects the bisulfite HSO that reaction generates
3 -, HSO
3 -the air oxygen that oxidized blower fan (11) blasts changes into SO
4 2-, SO
4 2-with Ca
2+reaction generates calcium sulfate CaSO
4, CaSO
4crystallization is gypsum CaSO
42H
2o, the pH value of bottom stock tank maintains between 5.2-5.6; A slurries part that contains gypsum, dust and impurity enters gypsum dewatering equipment (8) through plaster slurry pump, and all the other slurries return to absorption tower cycling and reutilization; Flushing water equipment in absorption tower is regularly implemented to rinse, and prevents that gypsum, dust and other solids in droplet from stopping up the pipeline on absorption tower;
Flue gas through booster fan (60), flue, enter desulfurizer under the guiding of import and export/by-pass damper, and by-pass damper is arranged on flue collector; Once desulfurizer breaks down, by the switching of import and export/by-pass damper, eliminate the impact of fault on boiler operatiopn; When boiler startup and desulfurizer break down, import and export baffle door is closed, and opens by-pass damper door, and untreated flue gas directly enters chimney (9) and enters atmosphere;
The lime stone of particle diameter 0.1～20mm enters wet ball mill (2) and adds water that to grind to form solid contents be 30% slurries, slurries suitable granularity are delivered to lime stone slurry case (5) by slurries cyclone (3), and the slurries of isolated coarsegrain enter ball mill slurries recycling tank (4), return to wet ball mill (2); Slurries in lime stone slurry case (5) are sent to absorption tower by lime stone slurry delivery pump, adjusting enters limestone slurry liquid measure or the absorption tower on absorption tower and discharges concentration of slurry, can make absorption tower stock tank pH value maintain between 5.2-5.6, guarantee dissolving and the SO of lime stone
2efficient absorption;
The dihydrate gypsum slurries that in absorption tower, desulphurization reaction generates are sent into gypsum dewatering equipment (8) through plaster slurry pump, first dewatered by the gypsum hydrocyclone of gypsum dewatering equipment (8), cyclone underflow slurries flow into gypsum slurries distributor box, vacuum belt dewaterer dehydration, last dehydrated gypsum is delivered to gypsum warehouse storage by multipoint mode unloader, cyclone overflow simultaneously flows into cyclone spill box, certainly flow to return water tank;
DCS control device amounts to 5526 I/O points of configuration; Desulfurization duct is established 78 I/O points, and important AI point is gas approach temperature point, former flue gas pressures measuring point; Important DI point is the on off state of inlet baffle; Important DO point is by-pass damper, inlet baffle, outlet damper; The pressure-measuring-point that the important AI point of booster fan is booster fan; DCS Fieldbus Components FBM adopts the fieldbus FCM10E connected mode of redundancy, realizes the collection of DCS control device input/output signal, A/D, D/A conversion, troubleshooting and photoelectricity isolation; Relay cabinet is realized the isolation of DCS control device digital output signal, and power distribution cabinet is realized the distribution of DCS control device; The input signal of the important simulation/switching value of DCS control device adopts " 3+1 " sensor method, important switching value output signal adopts passage independently to isolate the method for output precision, feedback acknowledgment output signal, and interlocking/protection simultaneously and detection measuring point sensor carry out independent setting; Key control loop adopts automatic disturbance rejection controller, when local fault appears in desulfurizer, start emergent degraded running program.
2. a kind of method that improves wet method limestone-gypsum flue gas desulfurizing system reliability and availability according to claim 1, it is characterized in that the method that the described important switching value signal of DCS control device measuring point adopts " 3+1 " sensor to detect is: the state of each important switching value is all installed the collection of 4 pressure sensing transmitters, the 4th pressure sensing transmitter with protective cover is in holding state, other 3 pressure sensing transmitter examinations; The switching value gathering is when consistent, by " three select three " regular output switch amount signal, when inconsistent, by " three select two " regular output switch amount signal, warning, after operator confirms, standby the 4th pressure sensing transmitter protective cover start detection that comes off; Take the 4th pressure sensing transmitter as benchmark, reject inconsistent sensor, proceed to new " three select three " or " three select two ".
3. a kind of method that improves wet method limestone-gypsum flue gas desulfurizing system reliability and availability according to claim 1, is characterized in that the output signal of the described important switching value of DCS control device adopts passage independently to isolate the method for digital output assembly, feedback acknowledgment output signal.
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| CN105467954B (en) * | 2015-11-20 | 2018-09-18 | 华北电力大学（保定） | A kind of method and device of desulfurization method of limestone-gypsum ORP and pH double controls |
| CN106000007B (en) * | 2016-07-06 | 2019-04-26 | 福建龙净环保股份有限公司 | A kind of simulation system and analogy method in wet desulphurization flow field |
| CN107158907A (en) * | 2017-06-29 | 2017-09-15 | 大连好月亮环保科技有限公司 | Oxidation plus wet absorption flue gas desulfurization and denitrification integral method and its device |
| CN110585888A (en) * | 2019-10-25 | 2019-12-20 | 四川德胜集团钒钛有限公司 | Flue gas desulfurization system of sintering machine |
| CN111175182A (en) * | 2020-01-08 | 2020-05-19 | 华电内蒙古能源有限公司包头发电分公司 | Method for measuring density of desulfurized limestone slurry of thermal power plant |
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