CN100368779C - Safety on-line monitor for water circulation of boiler - Google Patents
Safety on-line monitor for water circulation of boiler Download PDFInfo
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- CN100368779C CN100368779C CNB2005101066543A CN200510106654A CN100368779C CN 100368779 C CN100368779 C CN 100368779C CN B2005101066543 A CNB2005101066543 A CN B2005101066543A CN 200510106654 A CN200510106654 A CN 200510106654A CN 100368779 C CN100368779 C CN 100368779C
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Abstract
The present invention relates to a safety on-line monitoring instrument for boiler water circulation. The present invention is characterized in that the instrument comprises a high-pressure valve (a) and an instrument valve (a) on a pipeline of a boiler steam dome are connected with a differential pressure transmitter (a); a high-pressure valve (b) of a lower connecting box of the boiler steam dome is connected with instrument valves (b, c) which are connected in parallel, wherein the instrument valve (b) is connected with the differential pressure transmitter (a), and the instrument valve (c) is connected with a pressure transducer (a); a high-pressure valve (c) on a speed detecting pipe on a water screen pipe of the boiler steam dome is connected with instrument valves (e, f) which are connected in parallel, wherein the instrument valve (e) is connected with a pressure transducer (b), and the instrument valve (f) is connected with a differential pressure transmitter (b); the high-pressure valve (a) on the pipeline (a) of the boiler steam dome is connected with an instrument valve (g) which is connected with the differential pressure transmitter (b); the differential pressure transmitters (a, b) and the pressure transmitters (a, b) are electrically connected with respective resistors for measuring pressure; a thermoelectric couple on the boiler steam dome is electrically connected with a resistor for measuring temperature, and the resistors for measuring pressure and the resistor for measuring temperature are all electrically connected with a data acquisition unit and a computer. The safety on-line monitoring instrument for boiler water circulation has the advantages of automatic monitoring, exact failure diagnosis, etc.
Description
Technical Field
The invention relates to the field of measurement, in particular to a boiler water circulation safety online monitor.
Background
With the development of boilers to high capacity, ultrahigh parameter or supercritical parameter, the working conditions in the boiler process of the boiler are increasingly worsened, and the failure rate is very high. At present, most of water circulation supervision work in China still stays at the stages of manual meter reading and manual data analysis. Due to the fact that data collection is discontinuous and analysis and control are not timely, the water circulation state of the boiler cannot be accurately and timely reflected, trend prediction is difficult to make, phenomena such as stagnation, backflow, overtemperature and pulsation of a water wall pipe of the boiler cannot be found, serious accidents such as pipe explosion and leakage of the water wall of the boiler occur, and the boiler is forced to stop, so that economic loss is caused.
Disclosure of Invention
The invention aims to solve the technical problem of providing a boiler water circulation safety online monitor which can automatically monitor and accurately diagnose faults.
The technical scheme for solving the technical problem is as follows: the utility model provides a boiler water cycle safety on-line monitor which characterized in that: a pipeline 3a of a boiler drum 8 is connected with a differential pressure transmitter 6a through a high-pressure valve 4a and an instrument valve 5a which are connected to the pipeline 3a, a lower header 19 of a downcomer 20 of the boiler drum 8 is connected with instrument valves 5b and 5c which are connected in parallel through a high-pressure valve 4b which is connected to the lower header 19, the instrument valve 5b is connected with the differential pressure transmitter 6a, the instrument valve 5c is connected with a pressure transmitter 7a, the instrument valve 5a is connected with the instrument valve 5b through an instrument valve 5d, a speed measuring pipe 2 is installed on a water wall pipe 1 of the boiler drum 8, the speed measuring pipe 2 is connected with instrument valves 5e and 5f which are connected in parallel through a high-pressure valve 4 which is connected to the pipeline 3b, the instrument valve 5e is connected with the pressure transmitter 7b, the instrument valve 5f is connected with the differential pressure transmitter 6b, the instrument valve 5a is connected with the instrument valve 5b through the instrument valve 5d, the high-pressure valve 4a which is connected with the steam drum 8 pipeline 3a is connected with an instrument valve 5g, the instrument valve 5g is connected with the pressure transmitter 6b, the differential pressure transmitter 5g is connected with a data collector 5b, the pressure data collector 5a is electrically connected with a, the pressure data collector 12 and the data collector 12 a of the pressure data collector 12, the pressure data collector 12 and the pressure data collector 12 are electrically connected with the pressure data collector 12 and the pressure data collector 12. The speed measuring pipe 2 consists of a speed measuring rod 14, a full-pressure eduction pipe 15 and a static-pressure eduction pipe 16 which are connected with the speed measuring rod 14, wherein a full-pressure hole 17 and a static-pressure hole 18 are arranged in the speed measuring rod 14, the full-pressure hole 17 of the speed measuring rod 14 is communicated with the full-pressure eduction pipe 15, and the static-pressure hole 18 of the speed measuring rod 14 is communicated with the static-pressure eduction pipe 16.
The boiler water circulation safety on-line monitor can determine water circulation parameter measuring points according to the arrangement of a water circulation loop of a specific boiler, and adopts a speed measuring pipe and a thermocouple to measure the circulating flow rate and the circulating temperature; a pressure transmitter and a differential pressure transmitter are adopted to measure pressure and differential pressure, and then water circulation on-line monitoring and fault diagnosis are realized through computer data acquisition. The method has the advantages of automatic monitoring, accurate fault diagnosis and the like, and can be widely used for online monitoring and fault diagnosis of water circulation safety of large natural circulation boilers, once-through boilers and circulating fluidized bed boilers in the industries of electric power, metallurgy, petrifaction, heat supply and the like.
Drawings
FIG. 1 is a schematic view of a boiler water circulation safety on-line monitor.
FIG. 2 is a schematic view of the connection relationship of the boiler water circulation safety on-line monitor.
FIG. 3 is a schematic view of the connection structure of the velocity tube and the water wall tube.
FIG. 4 isbase:Sub>A schematic sectional view taken along line A-A in FIG. 3.
FIG. 5 is a graph of mass flow rate versus critical quality for constant boiler heat load and operating differential pressure.
FIG. 6 is a schematic sectional view of a boiler bank of tubes connected to a drum vapor-containing space.
FIG. 7 is a graph of the full differential pressure flow characteristics of heated tubes of a boiler.
FIG. 8 is a plan view of the boiler stations.
Detailed Description
The invention will be further elucidated by means of an embodiment shown in the drawing.
Referring to fig. 1, the boiler water circulation safety on-line monitor is characterized in that a pipeline 3a of a boiler drum 8 is connected with a differential pressure transmitter 6a through a high-pressure valve 4a and an instrument valve 5a which are connected to the pipeline 3a, a lower header 19 of a downcomer 20 of the boiler drum 8 is connected with instrument valves 5b and 5c which are connected in parallel through a high-pressure valve 4b which is connected to the lower header 19, the instrument valve 5b is connected with a differential pressure transmitter 6a, the instrument valve 5c is connected with a pressure transmitter 7a, the instrument valve 5a is connected with an instrument valve 5b through an instrument valve 5d, a speed measuring pipe 2 is installed on a water wall pipe 1 of the boiler drum 8, the speed measuring pipe 2 is connected with instrument valves 5b through a high-pressure valve 4 which is connected to the pipeline 3b, the instrument valve 5e and 5f which are connected in parallel, the instrument valve 5e is connected with the pressure transmitter 7b, the instrument valve 5f is connected with the differential pressure transmitter 6b, the instrument valve 5a is connected with the differential pressure transmitter 5b through the instrument valve 5d, the instrument valve 5g is connected with a, the differential pressure transmitter 5b, the data collector 5g is electrically connected with a, the data collector 12 and the data collector 12, the data collector 12 and the data collector 12 are connected with the data collector 12 and the data collector 12 of the data transmitter 5b, the data collector 12 and the data collector 12. The high-pressure valves 4a, 4b and 4c, the instrument valves 5a, 5b, 5c, 5d, 5e, 5f, 5g and 5h, the thermocouple 9, the temperature measuring resistor 10, the pressure measuring resistor 11, the data acquisition unit 12 and the computer 13 are all commercially available products. Data collector 12 adopts IMP3595 data collection system; 3051Rosemount is adopted for the pressure transmitter 7; differential pressure transmitter 6 employs a 3051Rosemount.
Referring to fig. 2, the USB interface of the computer 13 is connected to data processing software, the data processing software is connected to alarm software, and the alarm software is connected to the display. Data processing software and alarm software are programmed according to automated control techniques and computer data processing techniques, and are well known to those skilled in the art.
Referring to fig. 3 and 4, the tachometer tube 2 is composed of a tachometer bar 14, a full pressure outlet tube 15 connected to the tachometer bar 14, and a static pressure outlet tube 16. In this embodiment, the full pressure extraction tube 15 and the static pressure extraction tube 16 are welded to the spindle 14 to form an integral structure. A full pressure hole 17 and a static pressure hole 18 are arranged in the speed measuring rod 14, the full pressure hole 17 of the speed measuring rod 14 is communicated with a full pressure leading-out pipe 15, and the static pressure hole 18 of the speed measuring rod 14 is communicated with a static pressure leading-out pipe 16. During installation, the rod end of the speed measuring rod 14 of the speed measuring tube 2 extends into the boiler water wall tube 1 and is welded with the tube wall of the boiler water wall tube 1.
Circulation flow rate W 0 Measured using a tachometer tube 2. Because the speed measuring tube 2 can only measure the speed of the single-phase fluid, the W is measured 0 In the process, the velocity measuring tube 2 is arranged at the inlet of the water wall tube 1 and at the lower end of the downcomer 20 to ensure that the velocity measuring tube 2 measures the flow velocity of the single-phase fluid. The basic principle of the tachometer tube 2 is as follows: when a fluid flows through a cylindrical object, the distribution of pressure along the circumference of the cylindrical object is different, the surface facing the flow direction is full pressure, and the surface opposite to the flow direction is static pressure, and the pressure difference Δ P (dynamic pressure) between the two points is proportional to the kinetic energy of the fluid:
if a speed measuring tube 2 with a full pressure hole 17 and a static pressure hole 18 is inserted into the tube along the front and the back of the fluid flow, the flow speed of the fluid can be calculated according to the pressure difference delta P between the front and the back of the speed measuring tube 2:
mu is a flow coefficient, and the mu value of the speed measuring tube 2 is calibrated on a calibration system of the speed measuring tube 2 before the speed measuring tube 2 is installed. The secondary element of the speed measuring tube 2 does not adopt a double-tube differential pressure gauge, but adopts a differential pressure transmitter. Downcomer resistance Δ p xj Effective pressure head S of water wall YX SLH Effective pressure head S of mixed steam water outlet pipe YX YC The static pressure difference between the two ends of the measured pipe is measured by a differential pressure transmitter and then converted into resistance or effective pressure head.
Determination of the minimum circulation flow rate:
to ensure the safety and reliability of the boiler water circulation circuit, each loop pipe must have a certain mass flow rate ρ w to sufficiently cool the loop pipe, so that the flow rate of each water wall tube 1 cannot be lower than the minimum mass flow rate. The minimum allowable mass flow rate pw is determined subject to maximum local heat load without DNB (off nucleate boiling).
Referring to FIG. 5, there is a jump in the relationship between mass flow rate and critical mass dryness when the boiler heat load and operating differential pressure are constant. When the mass flow rate is lower than the platform, the dryness (maximum allowable dryness) deviating from the nucleate boiling is related to the mass flow rate, when the mass flow rate is higher than the platform, the dryness deviating from the nucleate boiling is unrelated to the mass flow rate, the critical dryness is greatly improved, and the mass flow rate corresponding to the platform is the minimum mass flow rate. To ensure safe and reliable operation of the boiler water cycle, the flow rate in each tube must be greater than the minimum mass flow rate by a certain percentage, typically greater than 10%, and the cycle flow rate w 0 And the mass flow rate pw is:
in the formula, w 0 Circulation flow rate, ρ w mass flow rate, ρ' saturation water density.
For the same cycleA loop circuit, the saturation water density rho' is a fixed value, so when the mass flow rate rho w reaches the minimum value, the circulation flow rate w 0 A minimum value is also reached so that the operating conditions of the boiler water cycle can be monitored by monitoring the cycle flow rate w 0. For a natural circulation boiler, the circulation flow rate w 0 Is generally specified to be 0.3m/s, while different boilers allow a minimum mass flow rate ρ 'w due to a large difference in the saturation water density ρ' caused by a difference in the operating pressure difference 0 As the saturation water density ρ' varies. The natural circulation boiler, hydrodynamic force has self-compensating characteristic, so despite the high heat load of the heat receiving strong pipe, the mass flow rate, that is, the circulation flow rate is also high, so the film boiling phenomenon does not necessarily occur in the heat receiving strong pipe, and the poor circulation phenomenon is likely to occur in the circulation loop and the water wall pipe which are heated weakly due to the low circulation flow rate. Therefore, in the water circulation on-line monitoring system of the natural circulation boiler, the circulation flow speed w of the weak water wall tube needs to be monitored in real time 0 At a circulation flow rate of low to minimum circulationAnd giving an alarm when the flow rate is increased by a certain margin.
Circulation stagnation and verification thereof:
when the common operating pressure difference Δ p of the tube panels * ＞Δp tz Then the cycle stall does not occur. For safety and reliability, a certain safety margin, typically 5%, must be left, i.e. when the verified tube meets the following conditions, no stagnation occurs.
In the formula: Δ p of * -operating differential pressure, [ Pa ], of the panel or bundle to which the tube to be checked belongs]；
Δp tz Checking the differential pressure of the tube in the state of circulation stagnation, [ Pa ]]。
In the case of water circulation tests or field monitoring, Δ p * Measured by measuring means, so that the configuration of the program section is predetermined according to the boilerFinding Δ p from parameters or the like tz The value of (c).
The stagnation pressure difference of the weakest heated tube of the tube panel is as follows:
namely:
Δp tz ＝h rq ρ′g+(h 1 +h 2 +Λ+h n )[(1-_ tz )ρ′+_ tz ρ″]g +h rh [(1-_ c )ρ′+_ c ρ″]g [Pa] (1-3)
collecting delta p * And Δ p tz Compared with the formula (1-2), whether the boiler water circulation is stagnated or not is checked.
And (3) checking the free water level:
referring to fig. 6, when the tube bank is directly connected to the drum steam space, the free water level must be checked. When the free water level is higher than the highest point of the pipe row, the free water level does not appear, so that the pressure difference delta rho of the steam-water mixture column at the part higher than the water surface of the drum needs to be calculated h The part below the water level of the drum is the same as the method of stagnation checking. It is clear that the void fraction of this portion of the soda water mixture is still the void fraction of the vapor bubbles through the still water layer c So its differential pressure is:
h[(1-_ c )ρ′+_ c ρ″]g [Pa] (1-4)
however, it is also considered that the steam column in the drum will offset a part of the pressure difference, so this part of the pressure difference should be:
Δp h ＝h[(1-_ c )ρ′+_ c ρ″]-hρ″g[Pa] (1-5)
and (5) after simplification, obtaining:
Δp h ＝h(1-_ c )(ρ′-ρ″)g [Pa] (1-6)
this means that Δ p is divided when verifying whether a free water level will occur tz In addition, Δ p must be added h . At the same time, a certain safety margin is considered, so that the conditions that the free water level does not appear are as follows:
circulating backflow and checking:
in the tubes with uneven heating in parallel in the tube panels or convection tube bundles of the water wall of the boiler, the tubes with weak heating may have stagnation and also may have circulating backflow, that is, the working medium in the tubes originally designed as the water wall tubes does not flow upwards but flows downwards.
Referring to FIG. 7, when the parallel tube panels or bundles are at a higher operating pressure differential Δ p 1 * When the running-in is carried out,the horizontal line and the backflow side characteristic curve have no intersection point, and circulation backflow cannot occur. If the boiler water wall is heated unevenly, the pressure difference delta p is operated at a lower value 2 * Run down, then
The horizontal line of (2) and the characteristic curve under the positive and negative flows of the heated weak pipe have three intersection points of A, B, C, and therefore, circulation backflow can occur. Obviously, if the pressure difference Δ p can be used for joint operation of the tube panels or tube rows * After the pressure difference value delta p of the weakest heated pipe of the pipe panel or the highest point of the backflow characteristic curve of the pipe to be verified is obtained dl max The backflow check can be performed. If it is not
And with a safety margin of 5%, it can be considered that the conditions under which the backflow does not occur in the tube are:
referring to fig. 8, the boiler water circulation safety online monitor of the present invention can determine a plurality of water circulation measurement points to perform online monitoring and fault diagnosis on water circulation safety according to the arrangement of water circulation loops of a specific boiler. The embodiment is the application of the boiler water circulation safety on-line monitor to the water circulation safety on-line monitor under the condition of peak load regulation and low load of a 200MW unit power station boiler. A HG-670/140-7 type boiler designed and manufactured in a monitored Harbin boiler plant is provided with a 200MW steam turbine generator unit, the boiler is arranged in an inverted U shape, membrane water-cooled walls are fully distributed around a hearth, a front screen superheater is arranged above the hearth, a rear screen superheater is arranged at the outlet of the hearth, and a convection superheater, a reheater, an economizer and an air preheater are arranged in horizontal and tail convection flues according to the flow direction of flue gas. The boiler adopts single-section evaporation and centralized downcomer. The main design parameters are as follows:
rated evaporation capacity: 670T/H
Superheated steam pressure: 13.72MPa
Temperature of superheated steam: 540 deg.C
Reheat steam flow rate: 579T/H
Reheat steam inlet pressure: 2.696MPa
Reheat steam outlet pressure: 2.5MPa
Reheat steam inlet temperature: 323 deg.C
Reheat steam outlet temperature: 540 deg.C
Water supply temperature: 240 ℃ C
Boiler water circulation safety on-line monitoring project:
circulation flow rate W 0 The determination of (A) is one of the most important items in the boiler water circulation safety online monitoring. By the pair of circulation flow rates W 0 The measurement of (2) can be understood as being differentUnder the heating condition, whether the water flow in the water wall cooling pipe has circulation stagnation or backflow or not is determined by measuring W 0 The cause of poor circulation cannot be found. Therefore, in measuring W 0 At the same time, the resistance Δ p of the downcomer must be determined xj Effective pressure head S of water wall YX SLB Effective pressure head S of mixed steam water outlet pipe YX YC . In addition, boiler operating parameters such as boiler load, drum level, drum pressure, flue gas temperature, superheated steam pressure, combustion conditions, and furnace temperature field are also measured.
Circulation flow rate W 0 Measured using a tachometer tube 2. The method is as described above.
The measuring point arrangement of the boiler water circulation safety on-line monitor comprises the following steps:
referring to fig. 8, in the figure: 1 # Front wall first 3 loop 1 st pipe, 2 # First 1 st pipe of first side wall loop, 3 # First side wall 5 loop 2 nd pipe, 4 # First 1 st pipe of first side wall loop, 5 # Rear wall first 3 loop 1 st pipe, 6 # Rear wall A3 rd pipe of loop 3, 7 # Rear wall A3 loop 5Root canal, 8 # Rear wall first 1 loop 1 st pipe, 9 # Rear wall second 3 loop 6 th pipe, 10 # Rear wall second 3 loop 4 th pipe, 11 # Rear wall second 3 loop 2 nd pipe, 12 # Second side wall 5 loop 1 st pipe, 13 # Second side wall 5 loop 2 nd pipe, 14 # Second side wall 1 loop 1 st pipe, 15 # Front wall second 3 loop 1 st pipe, 16 # Rear wall A3 loop water supply 1 st pipe, 17 # The 3-way water supply of the 2 nd pipe of the back wall A.
The selection of the measuring point must determine a specific measuring point position according to the distribution and the operation condition of the boiler water circulation loop.
The four walls of the boiler furnace are composed of membrane water-cooled walls welded by fin tubes, the width of the furnace is 13660mm, the depth is 11660mm, and the height is 38500mm.
The circulation loops of the water walls are respectively 6 loops of the front water wall and the rear water wall, and the circulation loops of the water walls on the two sides are respectively 5 loops, so that the total number of the loops is 22.
The boiler adopts 5 large-caliber centralized downcomer pipes which are made of No. 20 steel pipes with 426 multiplied by 36 mm. Two centralized downcomers near the center of the boiler are vertically downward from the steam drum, and 14 distributed downcomers are used for supplying water to a 1 st loop in front of the front water-cooled wall and the side water-cooled wall; two centralized sewer pipes close to two sides of the boiler are bent backwards, and 14 distributed sewer pipes are used for supplying water to a 1 st loop behind a rear water-cooled wall and a side water-cooled wall; the other two centralized downcomers are also vertically downward from the steam drum, and 16 distributed downcomers are used for supplying water to the water cooling walls on the two sides. The dispersion sewer pipe is made of No. 20 steel with a diameter of 159X 14 mm.
When the boiler operates under peak load regulation, the heat load in the boiler is lower than that under the rated working condition, the water-cooled wall is heated weakly, and for a natural circulation boiler, the phenomena of poor circulation, circulation stagnation and flow arrival can occur in a circuit which is heated weakly, so that the water-cooled wall pipe explosion accident is caused.
According to the purpose of water circulation monitoring, the reliability of water circulation in spike-adjusting low-load operation is mainly researched. Therefore, the measuring point arrangement of the boiler water circulation safety on-line monitor emphasizes the circuit with the worst reliability and the pipe with the worst reliability. According to the circulation loop distribution of the boiler, the loops with the worst reliability comprise eight loops, namely a front wall A3, a side wall A1, a side wall A5, a rear wall A3, a rear wall B3, a side wall B5, a side wall B1 and a front wall B3 which are heated worst. The least reliable tube in these eight circuits is the tube that is heated the weakest near the four corners. Therefore, measuring tubes are arranged in the four corners of the eight loops, and the specific measuring point positions are shown in the table 1.
TABLE 1 concrete positions of measuring points
| |
|
Rear wall B3 | 8978 th zxft 8978 th pipe |
| |
Root canal of 1 | |
8978 th zxft 8978 th pipe |
| |
8978 th zxft 8978 th pipe | |
Root canal of 1 |
| |
1,3,5 root canal | Front wall B3 | Root canal of 1 |
| |
Root canal of 1 | |
|
Can see by table 1, the 1 st root canal of all selecting in front wall first 3, front wall second 3, second side wall 1 and the 1 st return circuit of first side wall is as surveying buret, and second side wall 5, first side wall 5 select 1 st and 2 nd as surveying buret, and back wall first 3 selects 1,3,5 as surveying buret, and back wall second 3 selects 2,4,6 as surveying buret. For comparison, the 1 st tube of the rear wall armor 1 loop was selected as the measuring tube. Therefore, the water wall has nine loops, 15 measuring points and 15 speed measuring tubes 2. In addition, a rear wall armor 3 loop is selected, a speed measuring pipe 2 is arranged on the dispersion sewer pipe to measure the flow speed in the sewer pipe, the dispersion sewer pipe has 2 measuring points in total, and 2 speed measuring pipes 2 are arranged on the dispersion sewer pipe.
According to the installation requirement of the speed measuring tube 2, the installation position of the speed measuring tube 2 has enough distance to the local resistance, for example, dn represents the inner diameter of the tube, the rear part of the header is more than or equal to 5dn, the rear part of the elbow is more than or equal to 3dn, and the front part of the elbow is more than or equal to 2dn. Therefore, the distance between the speed measuring tube 2 arranged on the water wall tube and the lower header is more than or equal to 300mm, and the distance between the speed measuring tube in the dispersed sewer tube and the lower header is more than or equal to 600mm. Measurement of Δ p xj ，S YX SLB ， S YX YC When the static pressure measuring points are arranged on the steam pocket, the upper header and the lower header, the static pressure measuring points are not required to be punched at the inlet and the outlet of the pipe fittings of the steam pocket and the header, and holes are required to be punched on a hole plug on the steam pocket, a communicating pipe of the water level meter and a hand hole, a plug and a drain pipe on the header. The pressure taking point on the steam drum in the test is led out from the pressure taking point of the steam drum in the main control chamber, and the pressure taking point on the lower header is opened on the dispersed water supply pipe. The pressure taking point on the upper header is arranged on the steam-water outlet pipe.
Measuring points of working medium temperature are arranged on the dispersed sewer pipes of the front wall armor 3 and the rear wall armor 3, and a nickel lode-nickel silicon armored thermocouple is installed.
The pressure measurement points are taken on the static pressure measurement points of the upper header and the lower header.
The monitoring process of the boiler water circulation on-line monitor comprises the following working conditions:
1. and (5) water circulation operation condition when the boiler is started.
2. And (3) water circulation operation under 100% electric load constant-pressure operation.
3. The circulating operation condition of the water blowing ash water is thrown under the operation of 100 percent of electric load and constant pressure.
4. And (4) water circulation operation under the condition of 70% electric load constant-pressure operation.
5. The circulating operation condition of the water blowing dust water is thrown under the operation of 70 percent of electric load constant pressure.
6. And (3) the circulating operation condition of the water blowing ash water is thrown under the sliding pressure operation of 70 percent of electric load.
7. Water circulation operation under 50% electric load sliding pressure operation.
8. And (3) the circulating operation condition of the water blowing ash water is thrown under the sliding pressure operation of 50 percent of electric load.
9. And (3) water circulation running condition under 40% of electric load sliding pressure (oil injection) running.
10. And (3) water circulation running condition under 30% of electric load sliding pressure (oil injection) running.
In addition, the on-line monitoring is carried out under two working conditions of water circulation with continuous load rising and continuous load falling. After the furnace is shut down, a series of work such as measuring point hole drilling, speed measuring pipe 2 installation, pressure transmission pipe connection, secondary instrument installation and the like are carried out according to a water circulation measuring point arrangement diagram.
The velocity tube 2 is calibrated before installation, and the differential pressure of the velocity tube 2 is measured by a Rosemount3051 differential pressure transmitter 6. The pressure difference of the downcomer, the effective pressure heads of the water wall tube and the steam-water outlet tube are also measured by a Rosemount3051 differential pressure transmitter 6. The upper and lower header pressures are measured by 1151HP pressure transmitter 7. The temperature is measured by a nickel lode-nickel silicon sheathed thermocouple 9.
After all the measuring points and the instruments are installed, a hydraulic test is carried out to check whether each welding point has a water leakage phenomenon, and after the hydraulic test, the boiler water circulation safety online monitor can be put into operation.
When the soot blower blows the front wall, recording a front wall measuring point; when the soot blower blows the side wall, recording the measuring points of the side wall is carried out, and the like is carried out until all four walls are blown.
The basic standard for judging whether the natural water circulation is reliable is to judge whether all the water-cooled wall tubes can be ensured to be cooled, so that when the natural water circulation reliability is monitored on line, whether all conditions which can cause the water-cooled wall tubes not to be cooled normally occur is monitored on line, if the conditions do not occur, the water circulation is normal or reliable, and one of the heaviest conditions is to monitor whether the water circulation flow rate is too low, and whether stagnation and flow occur on line. If the water circulation flow rate is too low, stagnation and flow occurs, indicating that the water circulation is abnormal or unreliable.
In order to truly reflect the reliability of the instrument when the peak load of the unit is regulated, the detection working condition is carried out according to the actual operation working condition. More than 70% of the electric loads are operated at constant voltage; the electric load below 70% is operated by adopting sliding pressure, and the electric load below 50% is oil-fed to assist combustion.
The water circulation safety online monitoring instrument can monitor the water circulation safety of the 200MW unit power station boiler under various working conditions, and can see that:
1. when the water-throwing soot blower is operated at a constant pressure with 100 percent of electric load and 70 percent of electric load, the water circulation is basically not influenced; the instrument has no alarm.
2. The water circulation working condition of 70% electric load sliding pressure operation is better than that of constant pressure operation; the instrument has no alarm.
3. The 50% electric load is operated in sliding pressure, although the circulating flow velocity is slightly fluctuated, the lowest value of the fluctuation is far larger than the circulating flow velocity threshold value with poor water circulation reliability, and enough flow is still provided for cooling the water wall pipe, so that the overtemperature of the pipe wall is not caused; the instrument presents a warning prompt.
5. The 40% electric load is operated in a sliding pressure mode, the circulating flow rate has large fluctuation, the lowest value of the circulating flow rate is slightly smaller than the circulating flow rate with poor water circulation reliability, and the long-term operation is not suitable; the instrument gives an alarm discontinuously.
6. The 30% electric load is operated in a sliding pressure mode, the circulating flow rate fluctuates, and the water circulation reliability of most of circulating loops is poor, so that the operation is not suitable; the instrument alarms continuously.
Claims (2)
1. The utility model provides a boiler water cycle safety on-line monitor which characterized in that: comprises a first pipeline (3 a) of a boiler steam drum (8) connected with a first differential pressure transmitter (6 a) through a first high pressure valve (4 a) and a first instrument valve (5 a) connected on the first pipeline (3 a), a lower header (19) of a downcomer (20) of the boiler steam drum (8) is connected with second and third instrument valves (5 b and 5 c) connected in parallel through a second high pressure valve (4 b) connected on the lower header (19), the second instrument valve (5 b) is connected with the first differential pressure transmitter (6 a), the third instrument valve (5 c) is connected with the first pressure transmitter (7 a), the first instrument valve (5 a) is connected with the second instrument valve (5 b) through a fourth instrument valve (5 d), install on boiler drum (8) water wall pipe (1) and test the speed pipe (2), the third high-pressure valve (4 c) of connecting on second pipeline (3 b) and the fifth of parallel connection, sixth instrument valve (5 e, 5 f) are connected tests the speed pipe (2), fifth instrument valve (5 e) are connected with second pressure transmitter (7 b), sixth instrument valve (5 f) are connected with second differential pressure transmitter (6 b), first instrument valve (5 a) are connected with second instrument valve (5 b) through fourth instrument valve (5 d), first high-pressure valve (4 a) and seventh instrument valve (4 a) on boiler drum (8) first pipeline (3 a) The door (5 g) is connected, the seventh instrument valve (5 g) is connected with the second differential pressure transmitter (6 b), the seventh instrument valve (5 g) is connected with the sixth instrument valve (5 f) through the eighth instrument valve (5 h), the first and second differential pressure transmitters (6 a, 6 b), the first and second pressure transmitters (7 a, 7 b) are electrically connected with respective piezoresistors (11), the respective piezoresistors (11) are electrically connected with the data collector (12), a thermocouple (9) installed on the boiler steam pocket (8) is electrically connected with a temperature measuring resistor (10), the temperature measuring resistor (10) is electrically connected with the data collector (12), and the data collector (12) is electrically connected with the computer (13).
2. The boiler water cycle safety on-line monitor of claim 1, wherein: the speed measuring tube (2) consists of a speed measuring rod (14), a full-pressure eduction tube (15) and a static pressure eduction tube (16), wherein the full-pressure eduction tube (15) and the static pressure eduction tube (16) are connected with the speed measuring rod (14), a full-pressure hole (17) and a static pressure hole (18) are arranged in the speed measuring rod (14), the full-pressure hole (17) of the speed measuring rod (14) is communicated with the full-pressure eduction tube (15), and the static pressure hole (18) of the speed measuring rod (14) is communicated with the static pressure eduction tube (16).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005101066543A CN100368779C (en) | 2005-02-03 | 2005-09-23 | Safety on-line monitor for water circulation of boiler |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200520028266.3 | 2005-02-03 | ||
| CN200520028266 | 2005-02-03 | ||
| CNB2005101066543A CN100368779C (en) | 2005-02-03 | 2005-09-23 | Safety on-line monitor for water circulation of boiler |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1786673A CN1786673A (en) | 2006-06-14 |
| CN100368779C true CN100368779C (en) | 2008-02-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005101066543A Expired - Fee Related CN100368779C (en) | 2005-02-03 | 2005-09-23 | Safety on-line monitor for water circulation of boiler |
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| CN (1) | CN100368779C (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102287617B (en) * | 2011-09-20 | 2013-09-11 | 河北省电力建设调整试验所 | Device and method for measuring continuous pollution discharge flow rate of power plant boiler steam dome |
| CN103595041B (en) * | 2013-11-25 | 2015-06-03 | 广东电网公司电力科学研究院 | Monitoring method for rapid load reduction of power plant set |
| CN105222115B (en) * | 2014-06-16 | 2017-08-25 | 艾默生过程管理电力水利解决方案公司 | Control method and control system for fossil-fuel boiler |
| CN104732627A (en) * | 2015-01-27 | 2015-06-24 | 中国石油化工股份有限公司 | Control scheme optimization method of steam pocket safety interlocking system |
| CN106642061A (en) * | 2016-12-28 | 2017-05-10 | 湖南坤宇网络科技有限公司 | Early warning method for boiler separate cylinder failures based on decision tree system |
| CN107327827A (en) * | 2017-08-25 | 2017-11-07 | 哈尔滨哈锅锅炉容器工程有限责任公司 | A kind of large-scale steam-water dual-purpose type boiler |
| CN109521813B (en) * | 2018-11-13 | 2023-08-29 | 中国大唐集团科学技术研究院有限公司火力发电技术研究院 | System and method for stably controlling concentration ratio of circulating water of thermal power plant |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN86201253U (en) * | 1986-03-06 | 1986-11-12 | 东北电力试验研究院 | Water level-checking and measuring device for hot sleeve pressure container-type boiler |
| US5058288A (en) * | 1990-04-21 | 1991-10-22 | Man Gutehoffnungshutte Aktiengesellschaft | Plumb bob device for determining the bed height of bulk material in a shaft furnace |
| CN1506665A (en) * | 2002-12-12 | 2004-06-23 | 陈延平 | Measurement method of true value of water level in boiler steam packet and water level gauge |
| CN2788020Y (en) * | 2005-02-03 | 2006-06-14 | 东北电力学院 | Safety on-line monitoring instrument for boiler water circulation |
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2005
- 2005-09-23 CN CNB2005101066543A patent/CN100368779C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN86201253U (en) * | 1986-03-06 | 1986-11-12 | 东北电力试验研究院 | Water level-checking and measuring device for hot sleeve pressure container-type boiler |
| US5058288A (en) * | 1990-04-21 | 1991-10-22 | Man Gutehoffnungshutte Aktiengesellschaft | Plumb bob device for determining the bed height of bulk material in a shaft furnace |
| CN1506665A (en) * | 2002-12-12 | 2004-06-23 | 陈延平 | Measurement method of true value of water level in boiler steam packet and water level gauge |
| CN2788020Y (en) * | 2005-02-03 | 2006-06-14 | 东北电力学院 | Safety on-line monitoring instrument for boiler water circulation |
Non-Patent Citations (1)
| Title |
|---|
| 电站锅炉水循环安全在线监测和报警系统. 周云龙，洪文鹏，宋景东，关月波，张玲.锅炉技术，第32卷第3期. 2001 * |
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| Publication number | Publication date |
|---|---|
| CN1786673A (en) | 2006-06-14 |
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