JP2007315696A - Diagnosis device and diagnosis method for air preheater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diagnosis device and a diagnosis method for an air preheater easily diagnosing an air leaking situation in the air preheater, with respect to a boiler facility not equipped with an exhaust gas property measuring means suited for monitoring air leakage in the air preheater. <P>SOLUTION: In the diagnosis device for the gas type air preheater 10 attached to the boiler facility 30, the diagnosis device for the air preheater is characterized in that the consumed energy of an air flow side ventilator 21 installed at the combustion air system side of the gas type air preheater, and the consumed energy of a gas flow side ventilator 22 installed at an exhaust gas system side are provided as inputs, and on the basis of the estimation of a ventilation amount of the air flow side ventilator and the estimation of a ventilation amount of the gas flow side ventilator, the estimate of a leaking air amount in the air preheater is outputted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a diagnostic device and a diagnostic method for an air preheater attached to a boiler facility, and particularly to provide a device and a method for easily grasping the amount of leaked air.

  In many boiler facilities such as thermal power plants, in order to improve combustion efficiency, an air preheater that preheats combustion air by using residual heat of flue exhaust gas is installed.

  FIG. 8 shows a preheating method for combustion air in a general boiler facility. Combustion air is supplied by the forced air blower 21, preheated by the air preheater 10, and then introduced into the furnace of the boiler 30.

  On the other hand, the combustion exhaust gas from the boiler 30 is discharged from the chimney 35 after passing through the air preheater 10 and the dust collector 34 by the action of the sweep fan 22. There is also a boiler facility that employs a ventilation system that does not have the sweeper 22.

  There are several modes for controlling the boiler ventilation system. Among them, a representative one is that the combustion air flow is controlled by the vane provided in the forced air blower 21 based on the load command value or the measured value of the fuel supply amount of the fuel supply amount meter 41, and the pressure in the furnace is- Based on the measured value of the furnace pressure gauge 42, the combustion exhaust gas flow is controlled by a damper provided in the sweep fan 22 so that the atmospheric pressure is kept below about 10 mmAq.

  The excess air ratio of the combustion air is adjusted based on the measured value of the combustion exhaust gas oxygen concentration of the oxygen concentration meter 43 provided near the outlet of the economizer 32 in the boiler 30.

  In a relatively large boiler facility, a rotary regeneration type air preheater 10 as shown in FIG. 9 is often used as the air preheater 10. In this regenerative air preheater 10, the heat accumulator rotor 13 supported by the rotor shaft 12 disposed at the center of the casing 11 rotates at 2 to 3 rpm, and the heat accumulator is heated while the high-temperature exhaust gas flow passes. The heat exchange takes place by releasing heat while the cold air stream passes. Reference numeral 14 denotes a sector plate.

  The rotary air preheater 10 has a high merit in that the amount of heat transfer per unit volume is large, but on the other hand, there is a gap between the casing 11 and the outer circumferential direction and the radially outward direction of the heat accumulator rotor 13. It is difficult to completely seal and separate the exhaust gas flow side and the air flow side due to the rotation mechanism, and as a result, a part of the high pressure side air flow tends to leak to the exhaust gas flow side. ing.

  In general, the amount of leaked air slightly increases with the progress of boiler facility operation as shown in FIG. 10 due to deterioration of the seal portion, deformation of components, and the like, and the leakage rate may reach several ten percent. As the amount of air leaked from the air preheater 10 increases, the combustion air temperature generally decreases and the driving power of the ventilation facility increases, so the efficiency of the boiler facility decreases.

  Further, the increase in the exhaust gas flow rate causes a decrease in the dust collection efficiency of the dust collector 34. In a boiler facility equipped with a device (not shown) for heating the combustion air before preheating with the air preheater 10, the heating is performed. Part of the heat is lost.

  The capacity of equipment installed in the ventilation system such as a ventilator is generally selected with a certain allowance in consideration of air leakage in the air preheater 10, but excessive air leakage restricts the ventilation control system. There is also a possibility of limiting the boiler output.

  As described above, if the abnormality of the rotary air preheater is left unattended and the operation of the boiler equipment is continued, various adverse effects may occur. In the operation of boiler equipment, it is required to manage fluctuations in the amount of leaked air in the air preheater 10 to estimate and predict the deterioration of the seal part and to take appropriate measures such as adjusting and refurbishing the air preheater. It is done.

  As a method to cope with this, a plurality of oxygen concentration measuring means are attached to the flue, and the oxygen concentration of the combustion exhaust gas flow on both the inlet side and the outlet side of the air preheater is monitored to prevent air leakage in the air preheater. A method for grasping the situation is known.

Further, Patent Document 1 includes exhaust gas property analyzing means provided on both the inlet side and the outlet side of the rotary air preheater, means for calculating the leakage air rate, and means for estimating the degree of damage to the air preheater. An air preheater performance diagnostic device is shown. In order to grasp the fluctuation of the amount of leaked air in the air preheater, it is effective to monitor the combustion exhaust gas properties on both the inlet side and the outlet side of the air preheater.
Japanese Patent No. 2703548

  By the way, it is often the case that the old boiler equipment or the like is not originally equipped with a plurality of exhaust gas property measuring means suitable for monitoring air leakage in the air preheater described above. In such a boiler facility, in order to appropriately grasp the state of leakage in the air preheater, a new exhaust gas property measuring means will be added.

  However, in general, installation and adjustment of a measuring instrument for exhaust gas properties requires specialized techniques and often requires labor. For example, the measurement of the exhaust gas property performed in a place where the air leaked by the air preheater and the exhaust gas are not sufficiently mixed is not an appropriate measurement for grasping the air leakage state.

  The present invention has been made in consideration of the above-described points, and the situation of air leakage in the air preheater is not provided for boiler equipment that does not have exhaust gas property measuring means suitable for monitoring air leakage in the air preheater. It is an object to provide a diagnostic device and a diagnostic method for an air preheater that can easily diagnose the above.

  In order to achieve the above object, the present invention provides the following apparatus and method.

First, as a diagnostic device,
In the diagnostic device for the gas air preheater attached to the boiler equipment,
Energy consumption of the air flow side ventilator installed on the air system side of the gas air preheater, and energy consumption of the gas flow side ventilator installed on the exhaust gas system side are given,
Providing an air preheater diagnostic device, which outputs an estimated value of the amount of leaked air in the air preheater,
Next, as a diagnostic method,
In the diagnostic method of the gas air preheater attached to the boiler equipment,
Measure the energy consumption of the air flow side ventilator installed on the air system side of the gas air preheater and the energy consumption of the gas flow side ventilator installed on the exhaust gas system side,
A method of diagnosing an air preheater, characterized by calculating an estimated value of the amount of leaked air in the air preheater,
Is to provide.

  As described above, according to the present invention, the amount of leaked air is obtained by using the energy consumed by the air flow side ventilator and the gas flow side ventilator in the gas air preheater. I can grasp it.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As in the conventional apparatus described with reference to FIG. 8, the air preheater 10 is provided in the middle of the combustion air flow path and the combustion exhaust gas flow path for the boiler 30, and the ventilator 21 and the exhaust provided in the air flow path. Supply and exhaust are performed by the ventilator 22 provided in the gas flow path. These ventilators 21 and 22 are provided with pressure gauges 61 and 62. The air preheater 10 is provided with four thermometers 71-74.

Example 1-3 A diagnostic device 80 of the air preheater 10 corresponding to the boiler equipment as described above will be described by Example 1 and Example 2.

  Further, according to the third embodiment, a diagnostic method for an air preheater for boiler facilities that do not have permanent meters 51 and 52 for measuring energy consumption (power consumption, current consumption, etc.) of the ventilators 21 and 22 will be described. To do.

  A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the diagnostic device 80 of the air preheater 10 determines the power consumption of the push ventilator 21 and the measured value of the pusher ventilator 21 in order to obtain the energy consumption of the push ventilator 21 and the sweep ventilator 22. The ventilation control signal 46, the measured value of the power meter 52 that measures the power consumption of the sweep ventilator 22, and the sweep ventilation control signal 47 are collected.

  Next, the processing operation of the air preheater diagnosis device 80 will be sequentially described according to steps S1 to S5 shown in FIG.

Step S1: Calculation of Estimated Value of Ventilator Air Volume From the measured power values L _F and L _{I of the} push ventilator 21 and the sweep ventilator 22, the air volume Q and the power consumption L of the ventilators 21 and 22 illustrated in FIG. 3A The estimated values Q _F and Q _I of the passing air volume of the forced draft fan 21 and the sweep ventilator 22 are obtained using the respective characteristic curves indicating the relationship between

When the power meters 51 and 52 are current meters that measure the current consumption of the forced draft fan 21 and the sweep ventilator 22, respective characteristic curves showing the relationship between the air volume Q and the current consumption I of the ventilators 21 and 22 are shown. The estimated values Q _F and Q _I of the passing air volume of the forced draft fan 21 and the sweep ventilator 22 can be similarly obtained.

  Here, especially when the ventilation control method is based on the vane control of the ventilators 21 and 22, the air volume Q and the consumption of the ventilator illustrated in FIG. 3B from the measured value of the power consumption L of the corresponding ventilator and the ventilation control signal U. An estimated value of the passing air amount Q of the ventilators 21 and 22 is obtained using a characteristic curve group indicating a relationship with the electric power L.

Further, the measured values P _F and P _I of the differential pressure between the pusher 21 and the sweeper 22 and the ventilation control signals U _F and U _I are collected, and the air volume Q of the fans 21 and 22 illustrated in FIG. Using the characteristic curve group indicating the relationship with the static pressure difference P, the estimated values Q _F and Q _I of the passing air volume of the forced draft fan 21 and the sweep draft fan 22 may be obtained.

  In addition, the characteristic characteristic data of each ventilator acquired at the time of a normal test can be interpolated and used as the characteristic curve of the ventilator.

Step S2: Calculation of Estimated Value of Leakage Air When the air leakage of the air preheater 10 increases, generally, the air volume of the forced air blower 21 increases from the amount of combustion air supplied to the boiler 30 and the sweep air blower 22 Since the air volume increases from the amount of combustion exhaust gas from the boiler 30, the leakage air quantity ΔQ of the air preheater 10 is estimated by the following equation.

The smaller of the two estimated values of the leaked air amount obtained from the estimated values Q _F and Q _I of the passing air flow rate of the forced draft fan 21 and the sweep ventilator 22, and the common air flow rate for the forced draft fan 21 and the sweep ventilator 22. Only the increase is extracted so that the leaked air amount ΔQ is not overestimated.

Here, Q _F0 and Q _I0 are the reference air volume of combustion air and the reference air volume of combustion exhaust gas, respectively, and can be estimated as follows using the fuel supply amount F.

であり、ｍは空気過剰率、ｃ，ｈ，ｓ，ｏ，ｎ，ｗはそれぞれ燃料単位量に含まれる炭素、水素、硫黄、酸素、窒素、水分の重量とする。 here,

Where m is the excess air ratio, and c, h, s, o, n, and w are the weights of carbon, hydrogen, sulfur, oxygen, nitrogen, and moisture contained in the fuel unit amount, respectively.

Step S3: Calculation of Estimated Value of Increased Power Consumption From the estimated value ΔQ of the increase in leaked air amount, the characteristic curve (FIG. 3A) showing the relationship between the air volume Q of the ventilators 21 and 22 and the power consumption L is used again. Then, as shown in FIG. 3D, estimated values ΔL _F and ΔL _I of the increase in the power consumption of the forced draft fan 21 and the sweep draft fan 22 are obtained.

Step S4: Recording and Display of Estimated Leakage Air Value Power consumption L _F , L _{I of} the push ventilator 21 and the sweep ventilator 22, leak air amount ΔQ of the air preheater 10, the push ventilator 21 and the sweep ventilator 22 respectively The estimated values ΔL _F and ΔL _I of the increase in power consumption are recorded in time series and displayed in a graph or the like.

In addition to the above, the temperature measurement values of the thermometers 71, 72, 73, 74 installed at the inlets and outlets of the air preheater 10 on the combustion air side and the combustion exhaust gas side are collected. When the amount of leaked air increases in the air preheater 10, the performance of the air preheater 10 as a heat exchanger generally decreases. Therefore, the temperature efficiencies ф _a and ф _g calculated by the following equations are recorded and displayed in time series. By doing so, the fluctuation of the heat exchange characteristics of the air preheater is also monitored.

Step S5: In Search of prediction curve ^{_{y = k 1 x 2 + k}} 2 x + k 3 of the air leakage rate in view the air preheater 10 and the calculation of the leakage air amount prediction curve is displayed graphically and the like. Here, the coefficients k ₁ , k ₂ , and k ₃ are obtained by solving the following equation group from the estimated value sequence y _i of the air leakage rate in the air preheater 10 and the corresponding time sequence x _i .

  FIG. 4 shows the estimated value of the air leakage rate, the estimated value of the increase in power consumption of the forced draft fan 21 and the sweep draft fan 22, the record data of the temperature efficiency of the preheated air in the air preheater 10, and the prediction curves thereof. It is an output example.

  The function of the diagnostic device 80 of the air preheater 10 can also be realized by incorporating it into the existing boiler monitoring equipment. It can also be provided as part of a program for processing for monitoring.

  According to the first embodiment, the diagnostic device 80 of the air preheater 10 is provided that grasps the state of air leakage in the air preheater 10 based on the measurement values that can be acquired without newly installing an exhaust gas property measuring device. be able to. By outputting the estimated value of the increase in power consumption in the ventilator, a repair plan for the air preheater 10 in consideration of the energy cost due to the air leakage of the air preheater 10 becomes possible.

  By calculating the temperature efficiency of the combustion air side and the combustion exhaust gas side in the air preheater 10, the heat exchange performance of the air preheater 10 can be monitored. Further, by displaying the prediction curve of the leaked air amount in the air preheater 10, it is possible to grasp the expected increase in the leaked air amount.

  FIG. 5 shows a second embodiment of the present invention. In addition, the same code | symbol is used for the component same as Example 1. FIG.

  In FIG. 5, the diagnostic device 80 of the air preheater 10 includes the measured value of the power meter 51 that measures the power consumption of the forced draft fan 21 and the pushed draft control signal 46, and the power that measures the consumed power of the sweep ventilator 22. The measured value of the meter 52 and the sweep ventilation control signal 47, the measured value of the fuel supply amount meter 41, and the measured value of the oxygen concentration meter 43 are collected.

  Here, the oxygen concentration meter 43 is installed in the flue 32 upstream of the boiler 30 or the air preheater 10 shown in FIG. 5, and is usually installed for adjusting the excess air ratio of the combustion air. A densitometer can be used.

  The processing of the air preheater diagnosis device 80 of the second embodiment can be performed by the same processing as the steps S1 and S3 to S5 in the first embodiment, and only the processing of the step S2 will be described below.

と比較して明らかに異なる（小さい）場合に、空気予熱器１０における漏洩空気量の推定値ΔＱを次式で求める。

Step S2: Calculation of Estimated Value of Leakage Air Volume The measured value (O ₂ ) of the exhaust gas oxygen concentration is a calculated value of the oxygen concentration calculated from the estimated value Q _F of the passing air volume of the forced air blower 21 and the boiler fuel supply amount F.

When it is clearly different (small) compared to, the estimated value ΔQ of the amount of leaked air in the air preheater 10 is obtained by the following equation.

であり、ｃ，ｈ，ｓ，ｏ，ｎ，ｗは、それぞれ燃料単位量に含まれる炭素、水素、硫黄、酸素、窒素、水分の重量とする。 here,

Where c, h, s, o, n, and w are the weights of carbon, hydrogen, sulfur, oxygen, nitrogen, and moisture contained in the fuel unit amount, respectively.

  According to the second embodiment, there is provided the diagnostic device 80 for the air preheater 10 that grasps the state of air leakage in the air preheater 10 based on measurement values that can be acquired without newly installing an exhaust gas property measuring device. be able to.

  FIG. 6 shows a third embodiment of the present invention. In the third embodiment, the power meter 51 and the power meter 52 are temporarily installed, and the power consumption of the push-in ventilator 21 and the power consumption of the sweep ventilator 22 are measured. When the supply power of the ventilator motor is a three-phase three-wire system, the power can be measured even if the power meter is configured using two power meters as shown in FIG. If the power meter 51 and the power meter 52 are provided with a function of transmitting measurement values wirelessly, wiring work and the like are simplified.

  The portable information terminal 81 receives radio signals transmitted from the power meter 51 and the power meter 52 and collects power consumption data of the push ventilator 22 and the sweep ventilator 23. In the portable information terminal 81, the estimated value of the amount of leaked air in the air preheater 10 is calculated using the characteristic curves of the forced draft fan 22 and the sweep ventilator 23 in the same manner as the processing described in the first embodiment. Furthermore, the function similar to the diagnostic apparatus of the air preheater in Example 1 or Example 2 can also be expanded by collecting other instrument signals and the like.

  Compared with the case where measurement is performed by providing a plurality of combustion exhaust gas property measuring means in the vicinity of the air preheater 10, the measurement of the power consumption of the forced draft fan 21 and the sweep ventilator 22 is often easily realized. According to the diagnostic method of the air preheater 10 of Example 3, the air leakage situation of the air preheater 10 can be easily diagnosed.

The figure which shows the installation condition of the diagnostic apparatus of the air preheater in 1st Example of this invention. The figure which shows the diagnostic process step in the 1st Example shown in FIG. The figure which shows the relationship of the air volume-power consumption of the ventilator in 1st Example shown in FIG. The figure which similarly shows the relationship between the air volume of a ventilator and power consumption. The figure which similarly shows the relationship of the air volume-static pressure difference of a ventilator. The figure which similarly shows the relationship between the air volume of a ventilator and power consumption. The figure which shows an example of the display screen output in a 1st Example. The figure which shows the installation condition of the diagnostic apparatus of the air preheater in 2nd Example of this invention. The figure which shows the diagnostic method of the air preheater in the 3rd Example of this invention. The figure which shows an example of the measuring method of the power consumption of the motor of the ventilator in a 3rd Example. The block diagram which shows the pre-heating system and ventilation control system of the conventional boiler equipment. The block diagram of the rotary air preheater in the conventional boiler equipment. The figure which shows an example of the change of the amount of leakage air in the conventional air preheater.

Explanation of symbols

10: Air preheater 21: Pushing ventilator
22: sweep aerator 30: boiler 31: combustion air duct 32: economizer 33: combustion exhaust gas duct (flue)
34: Dust collector 35: Chimney 41: Fuel supply meter 42: Furnace pressure meter 43: Oxygen concentration meter 44: Pushing air flow control setting device 45: Sweep air flow control setting device 46: Pushing air flow control signal 47: Sweep air flow control signal 51 , 52: Power meter 61, 62: Pressure meter 71, 72, 73, 74: Thermometer 80: Air preheater diagnostic device 81: Portable information terminal

Claims (8)

In the diagnostic device for the gas air preheater attached to the boiler equipment,
The energy consumption of the air flow side ventilator installed on the combustion air system side of the gas air preheater and the energy consumption of the gas flow side ventilator installed on the exhaust gas system side are given as inputs,
An estimated value of the amount of leaked air in the air preheater is output based on the estimation of the ventilation amount of the air flow side ventilator and the estimation of the ventilation amount of the gas flow side ventilator. Diagnostic device.   The air preheating according to claim 1, wherein a ventilation control signal is given as an input in addition to the energy consumption of the air flow side ventilator, and a ventilation control signal is given as an input in addition to the energy consumption of the gas flow side ventilator. Device diagnostic equipment.   In place of the energy consumption of the air flow side ventilator, the differential pressure and the ventilation control signal of the air flow side ventilator, and in place of the energy consumption of the gas flow side ventilator, the differential pressure of the gas flow side ventilator and The air preheater diagnosis apparatus according to claim 1, wherein a ventilation control signal is given as an input.   The diagnostic apparatus for an air preheater according to claim 1, wherein, in addition to the input, a boiler fuel supply amount and an oxygen concentration of a gas system upstream of the air preheater are input.   In addition to the input, an inlet temperature and an outlet temperature to the gas air preheater on the air system side, and an inlet temperature and an outlet temperature to the gas air preheater on the gas system side are input. The diagnostic apparatus for an air preheater according to any one of claims 1 to 4.   6. The diagnostic apparatus for an air preheater according to claim 1, wherein an estimated value of an amount of energy loss caused by an increase in the amount of leaked air is output in addition to the estimated value.   The diagnostic apparatus for an air preheater according to any one of claims 1 to 6, wherein a prediction curve of the leaked air amount is displayed. In the diagnostic method of the gas air preheater attached to the boiler equipment,
Measure the energy consumption of the air flow side ventilator installed on the air system side of the gas air preheater and the energy consumption of the gas flow side ventilator installed on the gas system side,
A method for diagnosing an air preheater, comprising: calculating an estimated value of a leakage air amount in the air preheater.

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