JP2007263841A - Device for monitoring steam quality of boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for monitoring steam quality of boiler capable of measuring the amount of organic impurities in steam accurately, in a short time. <P>SOLUTION: This device is equipped with a cooler 10 for cooling supply steam S1 from the boiler 2 into condensed water G, a spectrophotometer 20 for measuring the absorbance of the condensed water G with respect to light of a prescribed wavelength, and an operation means 21 for calculating the amount of organic impurities in the supply steam S1, by using the absorbance measured by the spectrophotometer 20. Since the amount of organic impurities in the supply steam S1 is determined via the operation means 21, by changing the supply steam S1 into condensed water G, and by measuring the absorbance of the condensed water G by the spectrophotometer 20, measurement can be performed in a short time. Since the calculation errors of the amount of organic impurities by the operation means 21 can be reduced by experiment or the like, accuracy of the calculated amount of organic impurities in the supply steam S1 can also be kept high. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a boiler steam quality monitoring device that measures the amount of organic impurities contained in boiler supply steam and monitors the quality of the supply steam.

  Since water treatment agents are added to boiler feed water, etc., organic impurities such as these water treatment agents and their thermal decomposition products accumulate on the boiler side. Organic impurities did not concentrate in the boiler water, and they were not often mixed into the steam by carryover.

  However, in recent years, small-sized once-through boilers that are relatively inexpensive and capable of unattended operation have become widespread, and almost all of the boiler feedwater has been vaporized, so that organic impurities tend to be included in the steam. It is coming. In addition, conventionally, heating and sterilization of products are often performed indirectly through a heat exchanger that uses steam. However, in recent years, it has become common that steam is blown directly into products. ing. For these reasons, in factories that use boilers such as those mentioned above, it is necessary to monitor the quality of steam and to take some measures, such as not using steam if the amount of organic impurities in the steam is large. Yes.

  For this reason, in recent years, the quality of steam from boilers has also been evaluated. For example, Patent Document 1 discloses a boiler condensate system monitoring device that condenses steam from a boiler and monitors the quality of the steam using the condensed water. In this boiler condensate system monitoring device, the quality of steam is monitored by immersing a test piece in condensed water of steam supplied from the boiler and observing the degree of corrosion of the test piece.

  However, in the above boiler condensate monitoring system, the test piece corrosion includes not only corrosion due to organic impurities, but also corrosion due to pH values and corrosion due to dissolved oxygen. There is a problem that it is not clear whether organic impurities of a certain level are contained, and the observation result tends to be subjective and lacks accuracy. In addition, the above apparatus has a problem that it takes time to obtain a result.

On the other hand, the amount of organic impurities in the steam can be known clearly and accurately (with high accuracy) by measuring the total organic carbon (TOC) concentration in the condensed water of the steam using a commercially available TOC meter.
JP-A-8-28803

  However, even a commercially available TOC meter has a problem that it takes 3 to 4 minutes for one measurement, and the amount of organic impurities in the vapor cannot be immediately known. For this reason, when a commercially available TOC meter is used for steam monitoring, it is not possible to immediately check the quality of the steam at the position immediately before the use point of the steam on the production line. There was a disadvantage that a time gap occurred between them. For this reason, even if the quality of the steam is confirmed, there is an inconvenience that it is not clear whether or not the quality of the steam that has been used is maintained.

  In view of the above, an object of the present invention is to provide a steam quality monitoring apparatus for a boiler that can accurately measure the amount of organic impurities in steam within a short time.

  The invention according to claim 1 of the present invention includes a cooler that cools steam for supplying boiler to condensate, a spectrophotometer that measures the absorbance of the condensed water with respect to light of a predetermined wavelength, and the spectrophotometer. And an arithmetic means for calculating the amount of organic impurities in the supply vapor using the absorbance measured by the above-described method.

  In this invention, the relationship between the organic impurity concentration (for example, TOC concentration) of the condensed water and the absorbance of the condensed water with respect to the predetermined wavelength of light is obtained in advance, and the absorbance of the condensed water with respect to the predetermined wavelength of light is determined. If known, using this absorbance, the calculation means can calculate the organic impurity concentration of the condensed water.

  That is, in the present invention, the condensed water of the boiler supply steam from the cooler is irradiated with light of a predetermined wavelength by a spectrophotometer, the absorbance of the condensed water is measured, and the absorbance is used to calculate the calculation means. Calculates the organic impurity concentration (for example, TOC concentration), thereby measuring the amount of organic impurities in the supply steam.

  Here, the organic impurities in the vapor, that is, the water treatment agent containing the organic acid, its salt or saccharide brought into the boiler, or the thermal decomposition product thereof has a functional group that absorbs light. It has absorption characteristics with respect to several wavelengths, and has the property of absorbing light in the ultraviolet region, as with general organic components. Further, when a colored water treatment agent is used, the organic impurities in the vapor have a property of absorbing light in the visible region. On the other hand, the light absorption characteristics of the condensed water change depending on the organic impurity concentration (for example, TOC concentration) for each wavelength of light, so the organic impurity concentration (for example, TOC concentration) of the condensed water and the predetermined concentration of the condensed water are determined. There is a certain relationship with the absorbance of light of a wavelength.

  According to a second aspect of the present invention, in the case of the first aspect, the measurement wavelength of the spectrophotometer is 190 to 780 nm.

  In the present invention, light in the ultraviolet region and visible region having a wavelength of 190 to 780 nm is used. This is because the organic impurities in the vapor have a characteristic of absorbing any of these lights.

  According to a third aspect of the present invention, in the case of the first or second aspect, the spectrophotometer cell is a flow cell capable of continuously measuring the absorbance by flowing the condensed water. It is characterized by that.

  According to the first aspect of the present invention, when the supply steam of the boiler is condensed water, and the absorbance of the condensed water is measured by a spectrophotometer, the organic in the supply steam is obtained via the arithmetic means. Since the amount of system impurities is determined, it does not take time until the determination, and the amount of organic impurities in the supply steam can be easily measured in a short time. Moreover, according to this invention, the relationship between the organic impurity concentration (for example, TOC concentration) of condensed water used for calculating the amount of organic impurities and the absorbance of the condensed water with respect to light of a predetermined wavelength is Since it can be clarified by experiment, the accuracy of the calculated amount of organic impurities in the supply steam can be kept high. Therefore, according to the present invention, for example, a factory worker can immediately check the quality of steam immediately before the point of use, and can reliably use only high-quality steam, preventing troubles caused by the quality of the steam. can do.

  According to invention of Claim 2 of this invention, the quantity of the organic type impurity in vapor | steam can be known easily using the light of an ultraviolet region and visible region.

  According to the third aspect of the present invention, the amount of organic impurities in the steam can be known from moment to moment, and the operator can always use only high-quality steam, and troubles caused by the quality of the steam. Can be reliably prevented.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a steam quality monitoring apparatus according to an embodiment of the present invention.

  The steam quality monitoring device 1 measures the amount of organic impurities in the supply steam S1 generated at the boiler 2, for example, at a temperature of 150 ° C., and monitors the quality of the supply steam S1. As shown in FIG. 1, the steam quality monitoring device 1 is provided immediately before the supply valve 4 that sends the supply steam S1 to the steam use facility 3 in the supply steam line L1. The steam quality monitoring device 1 includes a steam sampling unit Y1 and a measurement unit Y2. The boiler 2 may be a round boiler, a water tube boiler, a once-through boiler, or other special boilers, and the pressure of the supply steam S1 may be any of low pressure, medium pressure, and high pressure.

  The steam sampling unit Y1 supplies the condensed water G of the supply steam S1 to the measurement unit Y2 at a predetermined temperature and flow rate. The steam sampling unit Y1 includes a cooler 10, a steam pipe L2 that connects the cooler 10 and the supply steam line L1, a condensed water pipe L3 that connects the cooler 10 and the measurement unit Y2, and a steam pipe L2. Check valve 11, shut-off valve 12, pressure gauge 13 provided, thermometer 14 provided in the condensed water pipe L 3, flow meter 15, flow rate adjustment valve 16, and cooling provided at the cooling water inlet to the cooler 10 It is comprised from the water quantity adjustment valve 17, the controller 18, and predetermined wiring.

  The cooler 10 is a heat exchanger that cools the supply steam S <b> 1 with the cooling water R and converts it into condensed water G. The shutoff valve 12 is an electromagnetic valve that opens and closes in response to a signal from the pressure gauge 13. The controller 18 controls the valve opening degree of the cooling water amount adjusting valve 17 based on the temperature signal of the condensed water G from the thermometer 14 and controls the valve of the flow rate adjusting valve 16 based on the flow signal from the flow meter 15. Control the opening.

  Here, the flow rate of the condensed water G is, for example, 120 mL / min, preferably 30 to 200 mL / min, and more preferably 50 to 150 mL / min. Moreover, although the temperature of the condensed water G is 20 degreeC, for example, it is preferable that it is 10-40 degreeC, and it is more preferable that it is 20-30 degreeC.

  The measurement unit Y2 measures the absorbance of the condensed water G, and determines the amount of organic impurities in the supply steam S1 from the absorbance via the TOC concentration. The measurement unit Y2 includes a spectrophotometer 20 that measures the absorbance of the condensed water G with respect to light of a predetermined wavelength, an arithmetic unit 21 that calculates the TOC concentration of the condensed water G from the absorbance of the condensed water G, and a calculation. The recorded TOC concentration or a value obtained by converting the TOC concentration into the amount of organic impurities in the steam is displayed and recorded as the amount of organic impurities in the supply steam S1. Note that the TOC concentration can be regarded as the organic impurity concentration of the condensed water G, whereby the amount of organic impurities in the supply steam S1 can be known.

  The spectrophotometer 20 is an ultraviolet / visible spectrophotometer that measures the absorbance of a sample using light in the ultraviolet and visible regions having a wavelength of 190 to 780 nm. The spectrophotometer 20 does not need to use light of all wavelengths in the ultraviolet and visible regions, for example, using a plurality of or one light having a predetermined wavelength (specifically, light in the ultraviolet region having a wavelength of 250 nm) Since it is only necessary to measure the absorbance of the condensed water G as a sample, the measurement takes only a few milliseconds. For this reason, the spectrophotometer 20 uses a flow cell in a cell holding a sample, that is, a cell capable of continuously measuring absorbance while flowing the sample without making it stand still. In addition, the condensed water G which flowed out from the flow cell is discharged | emitted outside through the discharge pipe L4.

  Next, the relationship between the absorbance of the condensed water used in the calculator 21 and the TOC concentration will be described. Carryover occurs due to boiler load fluctuations and can water concentration, and organic impurities in boiler water, that is, water treatment agents (including organic acids, their salts or sugars) brought into the boiler, and their thermal decomposition products. Is mixed in the steam.

  Organic impurities in water treatment agents and vapors composed of these pyrolysis substances have functional groups that absorb light (such as color-forming groups and auxiliary color groups with multiple bonds), so there are several wavelengths of light Have absorption properties. In addition, like general organic components, this organic impurity absorbs light in the ultraviolet region and transitions from a bond orbit in the ground state to an antibonding orbital with high energy, so it absorbs light in the ultraviolet region. Have Further, when a colored water treatment agent is used, this organic impurity has a property of absorbing light in the visible region. Therefore, when the steam of the boiler is condensed into a liquid (condensed water) and irradiated with light in the ultraviolet region or a specific visible region, light absorption occurs for each wavelength, and the degree of light absorption is expressed as absorbance. It can be measured with a spectrophotometer. On the other hand, this absorbance also varies depending on the concentration of organic impurities in the condensed water, for example, the TOC concentration.

  FIG. 2 is a graph showing the relationship between the TOC concentration, the wavelength of light in the ultraviolet region, and the absorbance, which were examined with respect to the condensed water of steam. This graph is obtained by an actual boiler experiment using the TOC concentration as a parameter. In this graph, it can be seen that the absorbance increases as the TOC concentration increases and the wavelength decreases.

  In the boiler experiment, an oxygen scavenger mainly composed of organic acids (Daiclean TL404 manufactured by Kurita Kogyo Co., Ltd.) as a water treatment agent was added to the makeup water of the experimental boiler at a rate of 180 mg / L. Then, the blowdown amount of boiler water from the experimental boiler was set to 0, the organic impurity concentration in the boiler water was increased, carryover was generated in the experimental boiler, and the organic impurity amount in the steam was increased. And while measuring the organic impurity density | concentration in the condensed water of the vapor sampled in batch as TOC density | concentration with the TOC meter, the light absorbency of this condensed water was measured with the spectrophotometer. In this case, since the scanning speed when taking the wavelength spectrum was 100 nm / min, it took about one and a half minutes to measure the absorbance of one sample. A spectrophotometer manufactured by Hitachi (U-2810 type) was used, and a TOC meter manufactured by SIERVERS (TOC analyzer portable type) was used.

  FIG. 3 is a graph showing the relationship between the TOC concentration of condensed water and the absorbance of condensed water with respect to light having a wavelength of 250 nm, for example. This graph is obtained from the TOC concentration and the absorbance with respect to the wavelength of 250 nm in FIG. 2, and shows that the absorbance and the TOC concentration are in a proportional relationship. Of course, the relationship between the absorbance and the TOC concentration can also be expressed for light of other wavelengths in the ultraviolet region from FIG.

  Therefore, the computing unit 21 calculates the TOC concentration of the condensed water G from the absorbance measured by the spectrophotometer 20 based on the relationship between the absorbance and the TOC concentration. Note that the relationship between the absorbance and the TOC concentration for a plurality of wavelengths may be examined, and the calculator 22 may output, for example, an average value of the TOC concentrations calculated based on these.

Below, the effect of the steam quality monitoring apparatus 1 is demonstrated.
The supply steam S1 from the boiler 2 is led from the supply steam line L1 to the steam sampling unit Y1 via the steam pipe L2. This supply steam S1 is cooled by the cooling water R in the steam sampling unit Y1 and converted into condensed water G. In this case, the temperature of the condensed water G at the outlet of the cooler 10 is measured by the thermometer 14, and the cooling water that the controller 18 flows into the cooler 10 through the cooling water amount adjusting valve 17 so that this temperature becomes the set temperature. Control the flow rate of R. Further, the flow rate of the condensed water G at the outlet of the cooler 10 is measured by the flow meter 15, and the supply steam S <b> 1 that the controller 18 flows into the cooler 10 through the flow rate adjustment valve 16 so that this flow rate becomes the set flow rate. To control the flow rate. Therefore, the condensate G is continuously supplied to the measurement unit Y2 side at the set temperature (20 ° C.) and the set flow rate (120 mL / min) as a result of the control of the flow rate adjustment valve 16 and the cooling water amount adjustment valve 17 by the controller 18. Sent.

  Here, when the pressure of the supply steam S1 falls to a predetermined set value, such as when the boiler 2 stops operating, the shutoff valve 12 is closed by a signal from the pressure gauge 13 that measures the pressure in the steam pipe L2. Then, the measurement operation on the measurement unit Y2 side is stopped. Further, when the pressure of the supply steam S1 rises above a predetermined set value, such as when the boiler 2 starts operation, the shutoff valve 12 is opened by a signal from the pressure gauge 13, and measurement operation on the measurement unit Y2 side is started. . The check valve 11 prevents the backflow of condensed water G and the like from the steam sampling unit Y1 side when the pressure on the boiler 2 side becomes negative.

  The condensed water G sent to the measurement unit Y2 is measured for absorbance by light of a predetermined wavelength (for example, light in the ultraviolet region having a wavelength of 250 nm) while passing through the cell (flow cell) of the spectrophotometer 20, and then discharged. It is discharged from the pipe L4. In this case, since the flow rate and temperature of the condensed water G sent to the spectrophotometer 20 are maintained at a constant condition, the measurement result for the condensed water G and the quality of the supply steam S1 are always in a constant relationship, and the condensed water G From the measurement result, the quality of the supply steam S1 can be accurately determined.

  The calculator 21 calculates the TOC concentration of the condensed water G based on the absorbance measured by the spectrophotometer 20, and the recorder 22 converts this TOC concentration or the amount of organic impurities in the vapor. The value is displayed and recorded as the amount of organic impurities in the supply steam S1.

  As described above, in the steam quality monitoring apparatus 1, if the supply steam S1 of the boiler 2 is the condensed water G, the absorbance of the condensed water G is measured, and then a predetermined calculation is performed, the supply steam S1 Since the amount of organic impurities is determined, it takes no time until the determination, and the amount of organic impurities in the supply steam S1 can be easily measured in a short time. Moreover, in this vapor quality monitoring apparatus 1, the relationship between the TOC concentration of condensed water used for calculating the amount of organic impurities and the absorbance with respect to light of a predetermined wavelength of the condensed water is sufficiently clarified by experiments. Therefore, the amount of organic impurities in the supply steam S1 can also be calculated with high accuracy.

  Therefore, the operator can immediately confirm the quality of the supply steam S1 immediately before the point of use of the steam use facility 3 and open the supply valve 4, so that only the high-quality steam is reliably ensured on the steam use facility 3 side. It is possible to prevent the trouble caused by the quality of the steam.

  Moreover, in this steam quality monitoring apparatus 1, the condensed water G can be continuously flowed to the measurement unit Y2 side, and the quality of the supply steam S1 that changes from time to time can be displayed continuously in a short time. For this reason, for example, if the quality of the supply steam S1 used is lowered, the worker can immediately close the supply valve 4 to stop the supply of the supply steam S1 to the steam use facility 3, By using only high-quality steam, troubles caused by the quality of the steam can be reliably prevented.

  Furthermore, in this vapor quality monitoring apparatus 1, since it is sufficient to use a spectrophotometer that has fewer components than a TOC meter and does not use a carrier gas or a reaction reagent, compared to the case where a TOC meter is used, The maintenance of the apparatus is easy, and the TOC concentration can be measured easily and quickly. Therefore, the steam quality monitoring device 1 can be easily installed and can be easily installed at any place where steam can be collected to monitor the quality of the steam.

  The measurement unit Y2 may be provided with an alarm device that issues an alarm when the TOC concentration is higher than the set value.

  Moreover, you may perform the organic type impurity density | concentration of the condensed water G by methods other than TOC density | concentration measurement.

It is a figure which shows the equipment arrangement | positioning of the steam quality monitoring apparatus of the boiler which concerns on one embodiment of this invention, and the flow of water, steam, and a signal. It is a diagram which shows the relationship between the TOC density | concentration regarding the condensed water of a vapor | steam, the wavelength of the light in an ultraviolet part, and a light absorbency. It is a diagram which shows the relationship between the light absorbency of condensed water with respect to the light of wavelength 250nm, and a TOC density | concentration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steam quality monitoring apparatus 2 Boiler 10 Cooler 20 Spectrophotometer 21 Calculator (calculation means)
G Condensed water S1 Supply steam

Claims (3)

A cooler that cools steam for supplying boiler to condensate, a spectrophotometer that measures the absorbance of the condensed water with respect to light of a predetermined wavelength, and the supply using the absorbance measured by the spectrophotometer A boiler steam quality monitoring apparatus, comprising: an arithmetic means for calculating the amount of organic impurities in the steam. 2. The boiler steam quality monitoring apparatus according to claim 1, wherein a measurement wavelength of the spectrophotometer is 190 to 780 nm. The boiler steam quality monitoring apparatus according to claim 1 or 2, wherein the spectrophotometer cell is a flow cell capable of continuously measuring the absorbance while flowing the condensed water.

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