JPH05126304A - Device to monitor attachment of scale to heat exchanger - Google Patents

Abstract

PURPOSE:To carry out an elaborate scale removal by judging whether or not scale is much attached particularly near a plurality of heat exchanging tubes in a supply water heater, etc. CONSTITUTION:Respective output signals of process measurement sections 44, 45-1-45-n, 46, 47, 48 at supply water inlet and outlet, extraction steam inlet, and drain outlet and inlet are inputted to a performance operation section 49, and there operation is carried out in order to evaluate the heat exchanging performance for each group of heat exchanging tubes 31. The output signals of the performance operation section 49 as the results of the calculations are inputted to a judgement section 51. To the judgement section 51 the output signal of a pressure difference operation section 43 and also the load signals 50 of an electric power plant, etc., are inputted, and from the judgement section 51 the result 52 of scale skin formation judgement is outputted. And the spots where scale attaches are judged by this. With this arrangement it is possible to carry out an especially elaborate scale removal work for the heat exchanging tubes 31 near the spot where scale attaches.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger scale adhesion monitor, and more particularly to an inner surface of a heat exchange tube of a heat exchanger such as a feed water heater installed in a condensate of a power plant or a water supply system, The present invention relates to a device for monitoring the presence or absence of scale adhered to the outer surface or the straightening cylinder.

[0002]

2. Description of the Related Art Japanese Patent Application No. 2-120682 "Heat Exchanger Scale Adhesion Monitoring Device" is a device for monitoring the presence or absence of scale adhesion on a heat exchanger such as a feed water heater installed in a condensate of a power plant or a water supply system. Is proposed. This conventional technique includes various process measurement units, a differential pressure calculation unit, a performance calculation unit, and a determination unit, and the differential pressure of the feed water pressure at the inlet and outlet of the heat exchanger and the heat exchange performance of the heat exchanger. By monitoring both of these, the place where the scale adheres is determined.

[0003]

According to the above-mentioned prior art, it is possible to determine whether the scale is attached to the inner surface, the outer surface, or the straightening tube portion of the heat exchange tube. further,
Not only whether the scale has adhered to the inner or outer surface of the heat exchange tube or the straightening tube section, but also where the scale adheres to the inlet, outlet or middle section of the heat exchange tube. In other words, it is possible to determine up to which of the drain cooling section, the superheat low temperature section, and the condensing section in the feed water heater the scale of the heat exchange tube is attached.

However, although a large number of heat exchange tubes are installed in the heat exchanger, according to the conventional method, approximately any of these many heat exchange tubes is particularly scaled. It was not possible to judge whether or not a large amount of film was attached. However, when removing the scale film adhering to the heat exchange tube, the heat exchange tube installed in the central part or the peripheral part of the many heat exchange tubes, or in the middle part. It is effective to know how much scale film is adhered to, because the heat exchange tube in the vicinity can be particularly carefully removed to remove the scale film.

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and to install the heat exchanger tubes at a central portion, a peripheral portion or an intermediate portion of a large number of heat exchange tubes in a feed water heater. Another object of the present invention is to provide a heat exchanger scale adhesion monitor capable of monitoring whether or not a large amount of scale film adheres to the heat exchange tube.

[0006]

[Constitution of the invention]

In order to achieve the above object, the heat exchanger scale adhesion monitoring apparatus of the present invention is basically a variety of heat exchanger tubes divided into groups. The process measuring section, the differential pressure calculating section, the performance calculating section, and the determining section are provided to monitor both the differential pressure of the feed water pressure at the inlet and outlet of the heat exchanger and the heat exchange performance of the heat exchanger, The presence / absence of adhesion and the scale adhesion location can be determined as to whether it is the inner surface or the outer surface of the heat exchange tube or the water supply flow path part such as a flow straightening tube other than the heat exchange tube. Further, in the present invention, a large number of heat exchange tubes installed in the heat exchanger are conveniently divided into several groups, and various process measurements for monitoring the heat exchange performance for each group. A unit is provided, and the performance calculation unit calculates and monitors the heat exchange performance of each group of heat exchange tubes.

Next, the basic structure of the present invention will be described with reference to FIG. In FIG. 1, in order to monitor the differential pressure between the water supply inlet and the water outlet of the water supply heater, a water supply inlet pressure measuring unit 41 is provided at the water supply inlet unit 23, and a water supply outlet pressure measuring unit 42 is provided at the water supply outlet unit 27. They are attached respectively, and the output signals of these measuring units 41 and 42 are guided to the differential pressure calculating unit 43. Since there is turbulence in the flow of water supply near the inlet-side water chamber 25 and the outlet-side water chamber 26, the closer to the inlet-side water chamber and the outlet-side water chamber, the closer to the water-supply pressure inlet pressure measuring unit 4
1 and the pressure of the water supply outlet pressure measuring unit 42 has large pulsation. Therefore, the water supply inlet pressure measuring unit 41 and the water supply outlet pressure measuring unit 42 are installed at positions sufficiently separated from the inlet side water chamber 25 and the outlet side water chamber 26 so that the pulsation can be measured small.

On the other hand, in order to monitor the heat exchange performance of the feed water heater, the feed water inlet process measuring unit 44 is provided at the feed water inlet 23.
However, at the outlet of the heat exchange tube 31 of the outlet side water chamber 26, a plurality of water supply outlet process measuring units 45-1, ... 45-n are provided.
However, the extraction steam inlet process 28 is connected to the extraction steam inlet process 28.
6, a drain outlet process measuring unit 47 is attached to the drain outlet 29, and a drain inlet process measuring unit 48 is attached to the drain inlet 36. It should be noted that each of the water supply outlet process measurement units 45-1, ... 45-n is preferably attached to a measurement point where an average state value of each group of a large number of heat exchange tubes can be measured. The output signals of these process measurement units 44 to 48 are the performance calculation unit 49.
The calculation signal for evaluating the heat exchange performance is performed for each group of heat exchange tubes, and the resulting output signal of the performance calculation unit 49 is input to the determination unit 51. The determination unit 51 includes an output signal of the differential pressure calculation unit 43,
The load signal 50 of the power plant or the like is also input, and the determination unit 51
Outputs a scale film formation determination result 52.

The determination unit 51 supplies the load water differential pressure value calculation result and the heat exchange performance evaluation calculation result for each group of heat exchange tubes of the heat exchanger, as well as a load signal of the power plant or a signal in place of this. The feed water flow rate signal 50 flowing into the heat exchanger is input as the feed water differential pressure value and the heat exchange performance evaluation calculation result are corrected by the load or the feed water flow rate value at that time. 2 is used to determine in which part of the heat exchanger the scale film is formed in an excessive thickness, or in which group of heat exchange tubes is formed in an excessive thickness by the decision logic of FIG. The determination unit 51 outputs the result of the determination.

The state of scale adhesion to a large number of heat exchange tubes is not always uniform, and even in an example of a heat exchanger in an actual thermal power plant, the heat exchange tubes in the outer peripheral portion, particularly in the vicinity of where the extracted steam flows in. Especially with a lot of scale adherence, or especially in the center,
In addition, various characteristics were observed in the scale adhesion condition depending on the power generation plant or the kind of installation conditions of the heat exchanger, such as the ones that are almost uniformly adhered to all the heat exchange tubes. Therefore, in the present invention, a large number of heat exchange tubes are conveniently and empirically divided into several groups for each heat exchange tube that are considered to have the same characteristics in the scale adhesion state, and heat exchange is performed for each group. The process measured values before the supplied water is sufficiently mixed are measured by the respective water supply outlet process measuring units 45-01 to 45-n.

As described above, since the feed water, the extraction steam or the drain flowing into the heat exchanger is in a sufficiently mixed and uniform state, the feed water inlet process measuring section 44 and the extraction steam inlet process measuring section 46. The value measured by the drain inlet process measuring unit 48 is an average value. On the other hand, regarding the drain that flows out from the heat exchanger, focusing on the temperature as an example, the one near the heat exchange tube with high heat exchange performance has a relatively low temperature and the one near the heat exchange tube with low heat exchange performance. Although the temperature of the drain is locally non-uniform as the temperature is relatively high, the drain outlet 2
Since it is sufficiently mixed and has a uniform temperature by the time it flows to 9, the measured value by the drain outlet process measuring section 47 shows an average value.

Regarding the feed water flowing out from the heat exchange tube, focusing on the temperature as an example, the feed water temperature flowing out from the one having a high heat exchange performance is relatively high, and the feed water temperature flowing out from the one having a low heat exchange performance is Relatively low. Therefore, using these measurement results, the performance calculation unit 49 performs calculation for evaluating the heat exchange performance of the heat exchange tubes for each group. The determination unit 51 uses the result to determine not only in which part of the heat exchanger the excessive thickness is generated, but also in which group of the heat exchange tubes the excessive thickness is generated. You can judge up to what you did.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a more specific structural example and operation of the above-described first embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a detailed diagram of the configuration block diagram shown in FIG. In the figure, the output signal P of the water supply inlet pressure measuring unit 41
₁ and the output signal P ₂ of the water supply outlet pressure measurement unit 42 are input to the differential pressure calculation unit 43 configured by the subtraction unit 55,
The output signal ΔP is input to the subtraction unit 59-3 of the determination unit 51. The feed water inlet temperature detecting unit 44-1 is used as the feed water inlet process measuring unit 44, and the drain outlet temperature detecting unit 47-1 is used as the drain outlet process measuring unit 47. These output signals ΔT ₂ are subtracted by the subtracting unit of the determining unit 51. 59-2 is input.

Further, the example shown in FIG. 3 is an example in which the present invention is applied to a feed water heater in which heat exchange tubes are divided into six groups, and the extraction steam inlet process heating unit 46 is used as the extraction steam inlet process water heating unit. The output signal P _{3 from the} internal pressure detector 46-2 is used to determine the saturation temperature (t
₁ ) It is input to the calculation unit 56, and its output signal t ₁ is input to the subtraction units 57-1 and 57-11 to 57-16. As the water supply outlet process measuring unit 45, the water supply outlet temperature detecting units 45-01 to 45-06 are used, and their output signals t ₂ and t _{21 to} t ₂₆ are also subtracting units 57-1 and 57-11 to 57-1.
6 is input. This subtraction unit 57-1, 57-11 to 5
The output signals ΔT ₁ and ΔT _{11 to} ΔT ₁₆ of 7-16 are sent to the determination unit 5.
1 is input to the subtraction units 59-1, 59-11 to 59-16. The load signal (or the feed water flow rate signal to the feed water heater) 50 (L) of the power plant is ΔT _1L , Δt of the determination unit 51.
_{1L1 to} ΔT _1L6 reference value calculation units 58-1 and 58-11
58-16, and these output signals ΔT _1L , ΔT
_{1L1 to} ΔT _1L6 are also subtraction units 59-1, 59-11 to 59-
16, respectively.

Further, subtraction units 59-1, 59-11 to 59-
The 16 output signals A ₁ , A _{11 to} A ₁₆ correspond to the alarm setting units 69-1 to 69-3 and 69-11 to 69-3, respectively.
1, 69-12 to 69-32, ... and 69-16 to 6
9-36, and as a result, ON-OFF output signals a _{1 to} a ₃ , a _{11 to} a ₃₁ , a _{12 to} a ₃₂ , ... A _{16 to} a ₃₆
Is input to the determination logic unit 70. On the other hand, the alarm setting units 69-4 to 69-6 and 69-7 to 69-9 input b _{1 to} b ₃ and c _{1 to} c ₃ to the determination logic unit 70. The judgment logic unit 70 judges, by the judgment logic of FIG. 4, in which part and in which group of the heat exchange tubes the scale film is formed with an excessive thickness, and the judgment result 52 is judged. It outputs as an output signal of 51.

Next, the operation of the above embodiment will be described. As mentioned above, the pressure difference between the inlet and outlet of the feed water heater is
Monitoring is performed by detecting the differential pressure between the inlet side pressure signal P ₁ and the outlet side pressure signal P ₂ . Further, as one method of monitoring the heat exchange performance of the feed water heater, "the difference between the saturation temperature of the pressure inside the feed water heater at the extraction steam inlet and the feed water outlet temperature"
And "difference between drain outlet temperature and feedwater inlet temperature" are both monitored, and when the difference exceeds a specified value, it is considered that the heat exchange performance is deteriorated. The “feed water heater internal pressure at the extraction steam inlet”, the “drain outlet temperature” and the “feed water inlet temperature” are average values that are sufficiently mixed, but in the present embodiment, further As described above, the “water supply outlet temperature” uses the water supply outlet temperature of each group of heat exchange-like tubes.

By the way, when considering heat exchange tubes having different heat exchange performances, or considering each group, it is natural that the heat exchange performances are the same if the feed water flow rate is the same. For high heat exchange tubes, the rise in feedwater temperature within the tube should be large, while the fall in bleed steam and drain temperatures around the tube should be large. On the other hand, for a heat exchange tube having a low heat exchange performance, the rise of the feed water temperature in the tube should be small, while the fall of the extraction steam and drain temperature around the tube should be small. Therefore, in order to monitor the heat exchange performance of each or each group of heat exchange tubes, the extraction steam and drain temperature around each tube and the feed water inlet temperature and flow rate to each tube should be monitored. It is a translation that must also be measured.

That is, when only the outlet feed water temperature of the heat exchange tube is measured, for example, if the scale locally adheres to the inner surface of the tube excessively, the heat exchange performance of the tube hardly changes. Since the flow rate of feed water flowing through the outlet decreases, the outlet feed water temperature may rise. By the way, in the present embodiment, average values are used for the extraction steam, the drain temperature, and the feed water inlet temperature, and therefore the “difference between the drain outlet temperature and the feed water inlet temperature (hereinafter referred to as ΔT _2L )” is monitored. ..

Meanwhile, "(hereinafter referred to as [Delta] T _1L and ΔT _1L1 ~ΔT _1L6) bleed difference between the saturation temperature and the feed water outlet temperature of the feed water heater vessel pressure at the steam inlet" in each group of a heat exchanger tube for So-called convenient values are also monitored. The above values when the scale film of magnetite is generated in a normal state, that is, the load of the power plant (or the flow rate of feed water to the feed water heater), ΔT _2L and ΔT _1L of the feed water heater, and each group of heat exchange tubes obtained beforehand by theoretical calculations or actual operational data the relationship between ΔT _1L1 ~ΔT _1L6 for each. Then, this relational expression is _expressed by ΔT _1L , ΔT _1L1 to ΔT _1L6 reference value calculation unit 58-
1, 58-11 to 58-16 and the ΔT _2L reference value calculation unit 58-2 are stored, and the load signal (or the feed water flow rate signal to the feed water heater) 50 is input to the load signal in the load. _{ΔT 1L, ΔT 1L1 ~ΔT 1L6,} ΔT 2L
Then, with respect to these values (standard values), a method of monitoring how much ΔT ₁ , ΔT ₁₁ to ΔT ₁₆ and ΔT ₂ calculated from the measured values have come is adopted.

On the other hand, generally, the heat exchange performance of the heat exchange tube does not increase with time, but remains constant or decreases. Moreover, whether or not the total performance of the feed water heater has deteriorated is determined by ΔT ₁ and ΔT calculated from average values.
Since it is judged according to _2, the heat exchange performance of each group of heat exchange tubes can be checked by monitoring whether the convenient value has changed (that is, the deviation from the reference value has exceeded the specified value). The deterioration can be monitored. The above determination logic is shown in FIG.

Further, in the present embodiment, as shown in FIG. 5, the outlets 31a of the heat exchange tubes to the outlet side water chamber 26 of the water chamber portion 21 are conveniently divided into six groups, each of which is divided into six groups. The outlet temperature of the water supply outlet temperature detection unit 45-01
˜45-06. Further, in order to measure the average temperature for each group as much as possible, by partitioning the vicinity of the outlet of the heat exchange tube with the dividing plate 301 for each group, in the vicinity of the water supply outlet temperature detecting unit, The water supply between other groups is difficult to mix, and the water supply between groups is easy to mix.

In the present embodiment, the heat exchange tubes are divided into six groups in the case of the structure and installation conditions used in the embodiments, for example, the heat exchange tubes in the vicinity of the flow of the extracted steam are scaled. The film is easy to attach, etc.
Items that are as similar as possible based on empirical, structural, and installation judgments are classified as the same group. Further, in this embodiment, the determination logic unit 70 uses the determination logic of FIG. 4 not only to determine whether or not the scale coating is attached to the feed water heater with an excessive thickness and the scale coating deposition site, but also which group. It is also determined whether or not scale is attached to the heat exchange tube, and the result is output.

According to the above-mentioned embodiment, in a large number of heat exchange tubes, whichever of the heat exchange tubes is divided into several groups for convenience, the scale film has an excessively large thickness. Since it is possible to determine whether or not the heat-exchange tube adheres to the heat exchange tube, it is sufficient to give particular attention to the corresponding one when cleaning for removing the scale of the heat exchange tube, and the effect is great.

Next, another embodiment of the present invention will be described with reference to FIGS.
Will be described. As a method of monitoring the heat exchange performance of the heat exchanger, there is a method of monitoring the heat transmission coefficient K of the heat exchange tube other than the above-mentioned embodiment, and the present invention can be applied to this method. In the present embodiment, as shown in FIG. 6, the average heat transmission coefficient for the entire feed water heater is considered for convenience without dividing into the drain cooling section, the condensation section, and the superheat reduction section. The method was adopted. A block diagram of this structure is shown in FIGS. 7 and 8. Also in the present embodiment, the outlet 31a of the heat exchange tube to the outlet side water chamber 26 of the water chamber 21 is conveniently provided separately from the water outlet temperature detector 89 of the water heater as in the embodiment of FIG. The temperature of each outlet is also measured by the water supply outlet temperature detectors _{89-1 to 89-n} , and the measurement results t _{89-1 to} t _89-n are obtained. Note that these measurement results t _89-1 ~
t _89-n are average values, the some are almost identical value as the measurement result t ₈₉ by the feed water outlet temperature detecting unit 89, and those from the t ₈₉ of high temperature, or a mean that some cold ones. Then, the average heat transfer coefficient of the entire feed water heater is calculated using t ₈₉ and t ₈₁ , t ₈₅ , t _86, Wf, P and the like.

On the other hand, regarding the presence / absence of a change in the heat transmission coefficient for observing the presence or absence of the scale film on the heat exchange tubes of each group, t ₈₁ , t ₈₅ , t ₈₆ , Wf,
Although an averaged measured value is used for P, as for the water supply outlet temperature, each temperature of the measurement results t _{89-1 to} t _89-n of the heat exchange tube outlet for each group is
Considering it as an average temperature at the water supply outlet, a convenient heat transmission coefficient is calculated. And, this value is different from the heat transfer coefficient in the normal state of the feed water heater (the state where the scale film is attached to the heat exchange tube with an appropriate thickness), depending on how much the heat exchange tube belongs to which group of heat exchange tubes. A method is used to determine whether the scale film adhesion is abnormal.
Since the same device as in FIG. 3 is used for monitoring the differential pressure between the inlet and outlet of the feed water heater, the description thereof will be omitted.

The temperature detecting unit 81 as the extraction steam inlet process measuring unit obtains the extraction steam inlet temperature t ₈₁ to the feed water heater. As the water supply outlet process measuring unit, the temperature detecting unit 89 obtains t ₈₉ which is an average temperature and the outlet water chamber 26
To the feed water outlet temperature near the outlet 31a of the heat exchange tube for each group to
89-n is also measured to obtain t _89-1 to t _89-n . The temperature detector 85 as the drain outlet process measuring unit obtains the drain outlet temperature t ₈₅ from the feed water heater. Obtaining a feed water inlet temperature t ₈₆ to the feed water heater by the temperature detector 86 as a feed water inlet process measurement unit. Further, the flow rate detector 90 obtains the feed water inlet flow rate Wf to the feed water heater, and the feed water inlet pressure detector 44-2 obtains the feed water pressure P.

The above-mentioned temperature signals and the like thus obtained are input to the performance calculator 49. In this case, the temperature signals t ₈₁ and t ₈₉ are input to the subtraction unit 95-10 that constitutes the performance calculation unit, and the subtraction result ΔT ₈₁ = t ₈₁ −t ₈₉ is output. The temperature signals t ₈₁ and t _89-1 are input to the subtraction unit 95-11, and the subtraction result ΔT _81.1 = t ₈₁ −t _89-1 is output. The temperature signals t ₈₁ and t _89-2 are input to the subtraction unit 95-12,
The subtraction result ΔT _81.2 (= t ₈₁ −t _89-2 ) is output. Similarly, the temperature signals t ₈₁ and t _89-n are input to the subtraction unit 95-1n and the subtraction result ΔT _81-n (= t ₈₁ −t _89-n )
Is output. Further, the temperature signals t ₈₅ and t ₈₆ are input to the subtraction unit 95-5, and the subtraction result ΔT ₈₅ (= t ₈₅ −t ₈₆ ) is output.

Of the above outputs, ΔT ₈₁ and ΔT
₈₅ is input to the logarithmic average temperature difference calculation unit 96-40, and the logarithmic average temperature difference calculation result ΔTm ₁₀ = (ΔT ₈₁ −ΔT ₈₅ ) /
log (ΔT ₈₁ / ΔT ₈₅ ) is output. Further, ΔT _81-1 and ΔT ₈₅ are input to the logarithmic average temperature difference calculation unit 96-41,
The calculation result ΔTm ₁₁ = (ΔT _81-1 −ΔT ₈₅ ) / log
(ΔT _81-1 / ΔT ₈₅ ) is output. Also ΔT _81-2 and Δ
T ₈₅ is input to the logarithmic average temperature difference calculation unit 96-42, and the calculation result ΔTm ₁₂ = (ΔT _81-2 −ΔT ₈₅ ) log (ΔT
_81-2 / ΔT ₈₅ ) is output. Similarly, ΔT
_81-n and ΔT ₈₅ are input to the logarithmic average temperature difference calculation unit 96-4n, and the calculation result ΔTm _1n = (ΔT _81-n −ΔT ₈₅ ).
/ Log (ΔT _81-n / ΔT ₈₅ ) is output. On the other hand, the enthalpy computing units 97.10 to 97 that constitute the performance computing unit 49.
-1n and 97-4 are stored, and the water supply pressure P and the temperature signal t ₈₉ described above are input to the enthalpy calculation unit 97-10, and the enthalpy h ₈₉ is output as the calculation result.

The feed water pressure P and the temperature signal t _89-1 are input to the enthalpy calculating unit 97-11, and the enthalpy h _89-1 is output as the calculation result. Further, the feed water pressure P and the temperature signal t _89-2 are input to the enthalpy calculation unit _97-12 , and the enthalpy h _89-2 is output as the calculation result. Similarly, the feed water pressure P and the temperature signal t _89-n
Is input to the enthalpy calculation unit 97-1n, and the enthalpy h _89-n is output as the calculation result. Further, the feed water pressure P and the temperature signal t ₈₆ is input to the enthalpy calculation unit 97-4, as the calculation result, the enthalpy h ₈₆ is output.

Next, the above-mentioned feed water inlet flow rate Wf and h ₈₉ , Δ
Tm ₁₀ and h ₈₆ are input to the heat transmission coefficient calculation unit 98-40,
The calculation result K ₁₀ = Wf × (h _89-1 −h ₈₆ ) / (A ₀ ×
ΔTm ₁₀ ) is output. Also, Wf, h _89-1 , ΔT
m ₁₁ and h ₈₆ are input to the heat transmission coefficient calculation unit 98-41, and the calculation result K ₁₁ = Wf × (h _89-1 −h ₈₆ ) / (A ₀ × Δ
Tm ₁₁ ) is output. Also, Wf, h _89-2 , _{ΔTm 12} ,
h ₈₆ is input to the heat transmission coefficient calculation unit 98-42, and the calculation result K ₁₂ = Wf × (h _89-2 −h ₈₆ ) / (A ₀ × ΔT
m ₁₂ ) is output. Similarly, Wf, h _89-n , Δ
Tm _1n and h ₈₆ are input to the heat transmission coefficient calculation unit 98-4n,
The calculation result K _1n = Wf × (h _89-n −h ₈₆ ) / (A ₀ ×
ΔTm _1n ) is output. Here, A ₀ is the heat transfer area of the feed water heater. K ₁₀ is the average value of the heat transmission coefficient of the entire feed water heater. Further, K ₁₁ , K _{12 to} K _1n are convenient heat transmission coefficients of the heat exchange tubes for each group.

These calculation results K ₁₀ , K _{11 to} K _1n are subtracted by the subtraction units 100-40 and 100-41 which constitute the determination unit 51.
It is input to each of 100-4n. Meanwhile, the determination unit 51
_Reference value calculation unit 9 for each of K _10L , K _{11L to} K _1nL
9-40, 99-41, 99-4n may be the load (or the flow rate of the feed water flowing into the feed water heater) in the normal state of the feed water heater (the state where the scale film adheres to an appropriate thickness). ) Heat transmission coefficient K _10L , K _11L ~ K
_{1 nL} is calculated by theoretical values or data measurement in an actual machine, and these values are stored. Then, the load signal 50 of the power plant is input to the K _10L , K _{11L to} K _1nL reference value calculation units 99-40, 99-41 to 99-4n, and the output signals K _10L and K _{11L to} K corresponding to the load signals. _1nL
As a reference value, the subtraction units 100-40, 100-
41 to 100-4n.

The subtraction results B ₄₀ , B _{41 to} B _4n are input to the alarm setting units 101-10 to 101-2n, and as a result, ON-OFF output signals d _{10 to} d ₃₀ , e.
₁₁ to e _n2 is obtained, these ON-OFF signal is input to the decision logic unit 102, by where judgment logic of FIG. 9, it can be determined whether the generated excessive thickness which site scale membrane is At the same time, it is possible to determine in which group of the heat exchange tubes the scale film is formed with a particularly excessive thickness.

Therefore, even if this method is used, the same effect as this embodiment can be obtained. In the above embodiment, in order to determine to which group of the heat exchange tubes of each group the scale film is particularly attached, for example, in the present embodiment of FIG. 3, the extraction steam inlet water supply is used. saturation temperature of the output signal P ₃ of the heater vessel pressure detecting unit 46-2 (t
_The method of monitoring the difference between ₁ ) and each of the water supply outlet temperatures t _{21 to} t ₂₆ of the heat exchange tubes for each group was adopted. Depending on the structure, type, and installation conditions of the heat exchanger of the power plant, each load of the power plant, the feed water outlet temperature, and the saturation temperature of the extraction steam inlet feed water heater internal pressure (t ₁ )
There is also a relationship with and close to a certain proportional relationship.

In such a heat exchanger, the saturation temperature (t ₁ ) of the extraction steam inlet feed water heater internal pressure is not obtained, but only the feed water outlet temperature of the heat exchange tubes of each group is measured. However, this measured value is compared with the value collected at the same measurement point when the power plant is under the same load when the feed water heater is in a normal state (the scale film is adhered to an appropriate thickness on the whole). When the difference exceeds the specified value (when the size of the deviation exceeds the specified value)
Even if it is determined that the scale film is particularly adhered to the heat exchange tubes of the corresponding group, it can be easily monitored and the same effect can be obtained.

That is, this modification will be described below with reference to FIG. The temperature detector 45-0 is used instead of the input signals ΔT ₁₁ to ΔT ₁₆ to the subtraction units 59-11 to 59-16.
Input the output signals of 1 to 45-06. On the other hand, ΔT _1L1 ~
In the ΔT _1L6 reference value calculation units 58-11 to 58-16, instead of storing the relationship between ΔT _{1L1 to} ΔT _1L6 and the load of the power plant when the feedwater heater is in a normal state, the feedwater heater is normal. In this state, the relationship between the water supply outlet temperature at the heat exchange tube outlet and the load of the power plant for each group is stored.

If the load signal 50 of the power plant is input in such a configuration, the ΔT _1L1 to ΔT _1L6 reference value calculation units 58-11 to 58-16 _perform heat exchange for each group for the corresponding load of the power plant. The reference value of the water supply outlet temperature at the tube outlet for use is the subtraction unit 59-11 to 5-5 described above.
9-16, and as a result, it is possible to monitor how much the measured value of the feed water outlet temperature at the heat exchange tube outlet deviates from the reference value for each group.

In the above embodiment, as a method for judging which of the heat exchange tubes of each group the scale film is particularly attached, in FIG. 3, the inside of the extraction steam inlet feed water heater is shown. The difference between the pressure saturation temperature (t ₁ ) and the feed water outlet temperature of the heat exchange tubes for each group, and in FIGS. 7 and 8, the heat exchange tubes for each group were calculated for convenience. The heat transmission coefficient is judged by whether the difference from the standard value at the corresponding load of the power plant or the like exceeds a predetermined specified value (whether the deviation exceeds the specified value). However, instead of this method, compare these values for the heat exchange tubes for each group with the corresponding average value of the entire feed water heater, and apply if there is a large difference between the two It may be determined that the scale film is particularly excessively attached to the heat exchanger tube of the group. An example of the decision logic for this method is shown in FIG. 10 using the components of FIG.

In the embodiment of FIG. 3, the groups of heat exchange tubes are divided as shown in FIG. 5, but it is not always necessary to divide them in this way. Also, the number of groups is not limited to six. Further, in the present embodiment, as shown in FIG. 5, a dividing plate is provided for each group for separation, but the dividing plate may not necessarily be provided depending on the type, structure, or installation condition of the heat exchanger. In some cases, it is possible to measure the value of the outlet temperature of the water supply, so it is not always necessary to provide a dividing plate.

Further, in the present embodiment, one water supply outlet temperature detecting unit is provided for each group, but a plurality of water supply outlet temperature detecting units is provided for each group and the average value for each group is set. The same effect can be obtained by calculating the water supply outlet temperature and monitoring it using other values.

[0040]

As is apparent from the above description, according to the present invention, in addition to the determination of scale film adhesion, heat exchange tubes having a large number of heat exchangers are conveniently divided into several groups. Since it is possible to determine whether the scale film is excessively adhered to the heat exchange tube of, it is possible to perform the heat exchange tube in the vicinity particularly carefully when removing the scale film, which is extremely effective. Target.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a basic configuration according to the present invention.

FIG. 2 is a diagram showing a decision logic according to the present invention.

FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 4 is a diagram showing a decision logic according to an embodiment of the present invention.

FIG. 5 is a perspective view showing the structure of an outlet feed water temperature measuring unit in the outlet side water chamber of the feed water heater in one embodiment of the present invention.

FIG. 6 is an explanatory view showing the states of the temperature of feed water, heated steam, saturated steam, and drain in each part of the feed water heater.

FIG. 7 is a view showing a feed water heater scale adherence monitoring device according to another embodiment of the present invention.

FIG. 8 is a block diagram showing a monitoring circuit of the monitoring device of FIG.

FIG. 9 is a decision logic diagram in the embodiment according to FIG.

FIG. 10 is a diagram showing another example of a determination logic diagram.

[Explanation of symbols]

 21 Water Chamber Part 22 Water Supply Heater Body 23 Water Supply Inlet 24 Rectifying Tube 25 Water Supply Inlet 26 Water Supply Outlet 28 Extraction Inlet 29 Drain Outlet 31 Heat Exchange Tube 36 Drain Outlet 41 Water Inlet Pressure Measuring Unit 42 Water Outlet Pressure measuring unit 44 Water supply inlet process measuring unit 45 Water supply outlet process measuring unit 46 Extraction steam inlet process measuring unit 47 Drain outlet process measuring unit 48 Drain inlet process measuring unit

Claims (1)

[Claims] 1. A heat exchanger scale attachment for monitoring the presence or absence of scale attachment to the inner surface, outer surface of a heat exchange tube that constitutes a heat exchanger such as a feed water heater installed in a power plant, or a flow straightener. In the monitoring device, the process measurement unit that measures the process value such as the condensate or feedwater temperature of the power plant in each section of the heat exchange tubes divided into multiple groups, and the feedwater pressure at the inlet and outlet of the heat exchanger A differential pressure calculation unit for calculating the differential pressure of
The heat exchange tube comprises a performance calculation unit for calculating the heat exchange performance for each group, and a determination unit for determining the scale film formation determination result, wherein the determination unit is the internal pressure of the extraction steam inlet feed water heater. Determine from the difference between the saturation temperature of the output signal of the detection unit and the water supply outlet temperature of the heat exchange tubes for each group, or calculate the heat transmission coefficient of the heat exchange tubes for each group, and use this calculated value and power generation. A heat exchanger scale adhesion monitoring device, characterized in that the judgment is made based on a difference from a reference value at a corresponding load of a plant or the like.