JP2006275410A - Boiler device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit the corrosion generated on a heating tube of a boiler caused by moisture. <P>SOLUTION: This boiler device comprises a boiler water extracting means 3 for extracting boiler water in the boiler 2, and a boiler water adding means 4 for adding the extracted boiler water into the supplied water before supplied to the boiler 2. According to this constitution, the boiler water in which silica as alkaline and corrosion inhibiting component is concentrated, is extracted from the boiler 2 during combustion by the boiler water extracting means 3. The extracted boiler water is added to the supplied water stored in a water supply tank 15 by the boiler water adding means 4, so that the supplied water is adjusted to have water quality capable of inhibiting the corrosion generated on a connecting portion of a lower header 6 of the boiler 2 and each water pipe 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a boiler device capable of suppressing corrosion generated in a heat transfer tube of a boiler or an economizer due to the influence of moisture.

  Boilers such as water tube boilers and round boilers are used as heat sources in various industries, and supply steam to steam-using equipment such as heating equipment, drying equipment, and production equipment. This boiler is provided with heat transfer tubes such as a water tube and a smoke tube in order to heat the feed water and generate steam. Since this heat transfer tube is made of non-passivated metal such as carbon steel, the part in contact with the boiler water is damaged due to the corrosion due to the influence of the boiler water, which is fatal to the life of the steam boiler. May have a negative effect. For this reason, in order to operate the said boiler stably for a long period of time, it is necessary to suppress the corrosion of the said heat exchanger tube effectively.

  Moreover, in the said boiler, the thing of the structure which installed the economizer (water supply preheater) in the flue is used (nonpatent literature 1). The boiler having this configuration has an economic advantage that the amount of fuel used can be reduced because the economizer recovers the latent heat of the exhaust gas and uses it for preheating the feed water. The economizer includes a heat transfer tube for exchanging heat between the water supply and the exhaust gas. However, since the heat transfer tube is formed using a non-passivated metal such as carbon steel, it is in contact with the water supply. May be damaged due to corrosion due to the influence of water supply, which may have a fatal effect on the life of the economizer. For this reason, in order to use the said economizer stably for a long period of time, it is necessary to suppress the corrosion of the said heat exchanger tube effectively.

28th page of “Small-sized once-through boiler” issued by the Japan Small once-through Boiler Association

  By the way, the corrosion of the heat transfer tube is likely to occur in a portion that is continuously in contact with water supply or boiler water. For example, in a once-through boiler that is one form of the water tube boiler, the connecting portion between the heat transfer tube and the lower header tends to corrode easily. Further, the economizer tends to corrode because water is always present in the heat transfer pipe during operation of the boiler. The corrosion of the heat transfer tube generally includes a lot of corrosion promoting components such as sulfate ions, chloride ions or dissolved oxygen in water, and the corrosion tendency increases when there are few corrosion inhibiting components such as silica. This corrosion is liable to cause local corrosion in addition to the thinning corrosion of the heat transfer tube, and this may cause a minute hole to break. Here, the local corrosion is a pitting corrosion that occurs in the thickness direction of the heat transfer tube from the contact surface side of the heat transfer tube and water toward the opposite side of the thickness direction. The heat pipe is damaged in a short period of time.

The boiler is operated so as to maintain the pH of the boiler in a range of 11 to 12 for the purpose of suppressing corrosion of the heat transfer tube formed of a non-passivated metal. Supply water using tap water or groundwater as a water source usually contains an alkali component (bicarbonate or carbonate), and this alkali component is thermally decomposed in the boiler to generate a hydroxide. This hydroxide is concentrated with the generation of steam, and the pH of boiler water rises. And, from the down operation of the blow operation, for example, the blow from the bottom of the lower header (can bottom blow) or the downcomer of the steam separator connected to the lower header so that the pH of the boiler water is in the above range. The concentration ratio is controlled by blowing (separator blow). Therefore, when the water quality contains a sufficient amount of alkali components, corrosion of the heat transfer tube can be suppressed without adding a water treatment agent such as alkaline chemicals to the water supply. In the steam boiler, the dissolved oxygen concentration decreases as the boiler water boils, which contributes to the suppression of corrosion in the heat transfer tube. However, the heat transfer tube has a relatively low water temperature at a portion where the feed water flows, for example, a connection portion between the heat transfer tube and the lower header, so that concentration and boiling are unlikely to occur. For this reason, even if the concentration rate of boiler water is controlled within a predetermined range, pH increase and deoxidation are unlikely to occur, and corrosion may occur.

  On the other hand, in the economizer, the temperature of the feed water that rises due to heat exchange with the exhaust gas is at most about 120 ° C., and the alkali component in the feed water is hardly decomposed and does not concentrate. That is, since the pH of the feed water does not increase in the heat transfer tube, corrosion is more likely to be promoted than the boiler. In addition, since the heat transfer tube is in a pressurized state, boiling of the feed water does not occur, and a decrease in dissolved oxygen concentration does not occur, so that corrosion is easily promoted.

  The problem to be solved by the present invention is to suppress corrosion that occurs in the heat transfer tube of a boiler or an economizer due to the influence of moisture.

  This invention was made in order to solve the said subject, The invention of Claim 1 is the boiler water collection means which collects the boiler water in a boiler, Before supply of the collected boiler water to the said boiler Boiler water adding means for adding to the feed water.

  According to invention of Claim 1, the boiler water collection | recovery means collect | recovers the boiler water with which the silica which is alkaline and a corrosion inhibitory component was concentrated from the boiler during combustion. Then, the collected boiler water is added to the feed water before being supplied to the boiler by the boiler water adding means, and the feed water is adjusted to a water quality capable of suppressing corrosion occurring in the heat transfer tube of the boiler.

  The invention according to claim 2 is an economizer that preheats water supplied to the boiler with exhaust gas from the boiler, boiler water collecting means that collects boiler water in the boiler, and supply of the collected boiler water to the economizer Boiler water addition means for adding to the previous feed water is provided.

  According to invention of Claim 2, the boiler water collection | recovery means collects the boiler water with which the silica which is alkaline and a corrosion inhibitory component was concentrated from the boiler during combustion. And, the collected boiler water is added to the feed water before being supplied to the economizer by the boiler water adding means, and the corrosion that occurs in the heat transfer tube of the boiler and the corrosion that occurs in the heat transfer tube of the economizer, Both are adjusted to a water quality that can be controlled.

  Furthermore, the invention described in claim 3 is characterized in that, in claim 1 or 2, the collected boiler water is added to a water supply tank for storing water supplied to the boiler.

  According to invention of Claim 3, the heated boiler water is mixed with the feed water stored in the said feed water tank. And with the temperature rise of feed water, dissolved oxygen concentration is reduced and it is adjusted to the water quality which can suppress the corrosion which arises in the heat exchanger tube of the said boiler or the said economizer.

  According to this invention, the corrosion which arises in the heat exchanger tube of a boiler or an economizer by the influence of a water | moisture content can be suppressed. As a result, damage to the boiler and the economizer is prevented, and steam can be stably supplied for a long period of time.

  Next, an embodiment of the present invention will be described. The present invention is suitably implemented in a boiler apparatus that generates steam by supplying water to a boiler and heating the boiler water.

(First embodiment)
First, a first embodiment of a boiler device according to the present invention will be described. The boiler apparatus according to the first embodiment mainly includes a boiler, boiler water collecting means, and boiler water adding means.

  The boiler generates steam by heating feed water, and has various structures such as a multi-tube water tube boiler, a single tube water tube boiler, and a round boiler. In particular, among these boilers, a multi-tube water tube boiler is preferably used because it is small in size, requires little installation space, is excellent in boiler efficiency, and is easy to manage and handle.

  The boiler body part, the lower part of the so-called boiler can body, is connected to a water supply tank through a water supply path. On the upstream side of the water supply tank, water treatment equipment for performing predetermined water treatment according to the quality of raw water such as tap water, industrial water, groundwater, for example, soft water equipment, ion exchange equipment, reverse osmosis membrane equipment, nano A filtration membrane device, a deoxygenation device, a water treatment chemical injection device, and the like are connected. That is, the water supply tank is configured to store water supplied by the water treatment device and store the water in the boiler can through the water supply path. On the other hand, the upper part of the boiler can body is connected to a steam separator through a steam supply path, and the lower part of the steam water separator is connected to the lower part of the boiler can body and a downcomer to collect the separated water. It is connected.

  In the first embodiment, the boiler water collection means includes a boiler water collection path and a boiler water collection valve. The boiler water collection path is connected to, for example, the downcomer pipe or the lower part of the boiler can body in order to collect concentrated boiler water from the boiler can body, and the boiler water collection path includes the boiler water collection path. A valve is provided. The boiler water sampling valve is normally controlled to open and close continuously or intermittently during combustion of the boiler.

  Here, the boiler usually discharges a predetermined proportion of boiler water from the boiler can body continuously or intermittently in order to prevent inconvenience such as carry over due to excessive condensation of the boiler water, It is configured to maintain an appropriate boiler water concentration. That is, since the boiler discharges the concentrated boiler water as blow drainage, for example, a boiler water discharge path is connected to the lower part of the downpipe and the boiler can body, and the boiler water discharge path includes a blow valve Is provided. Therefore, in the boiler having such a configuration, the boiler water discharge path is used as the boiler water sampling path as it is without newly providing the boiler water sampling means, and the blow valve is used as the boiler water sampling valve. Can be used as is.

  The boiler water addition means includes a boiler water supply path in the first embodiment. One end of the boiler water supply path is connected to the boiler water collection path from the lower part of the downcomer or the boiler can body. On the other hand, the other end side of the boiler water supply path is connected to the upstream side of the boiler can body, for example, the water supply tank or the water supply path. That is, the boiler water collected from the boiler can body is configured to be supplied to the upstream side of the boiler can body via the boiler water collection path and the boiler water supply path.

Here, when the collected boiler water is supplied into the water supply tank, it is desirable that the water supply stored in the water supply tank and the boiler water are mixed uniformly. For example, the inflow portion of the feed water and the inflow portion of the boiler water are arranged close to each other, and the feed water and the boiler water are uniformly mixed by the water flow of the feed water flowing into the feed water tank. Further, for example, a circulation path is connected to the water supply tank, and the water supply in the water supply tank is circulated by a circulation pump, so that the water supply and the boiler water are uniformly mixed. Further, for example, a stirrer is provided in the feed water tank, and the feed water in the feed water tank is agitated to uniformly mix the feed water and boiler water.

  Further, a water quality meter, for example, a pH meter may be provided in the water supply tank or the water supply path. Based on the detection result of this water quality meter, the amount of boiler water added to the feed water can be adjusted more accurately by controlling the opening and closing of the boiler water sampling valve.

  Hereinafter, the operation of the boiler device according to the first embodiment will be described. First, the water supply stored in the water supply tank is supplied to the boiler can body through the water supply path and stored as boiler water. This boiler water usually contains silica, which is an alkali component such as bicarbonate and carbonate, and a corrosion inhibiting component.

  When the boiler is burned, the boiler water is boiled by heating and steam is generated. This steam is supplied to steam using equipment provided in a facility such as a factory. Here, the alkaline component contained in the boiler water is thermally decomposed by heating to generate hydroxide, and raises the pH of the boiler water. Moreover, the silica contained in the boiler water is concentrated as the steam is generated, and acts to form an anticorrosive film in the boiler can.

  Here, the boiler apparatus maintains the pH of the boiler water at a value capable of suppressing the corrosion of the non-passivated metal forming the boiler can body, specifically, within the range of pH 11 to 12, and carries over. It is operated to maintain electrical conductivity that does not occur (eg, 4000 μS / cm or less). That is, the boiler water sampling valve is controlled to open and close during combustion of the boiler, and alkaline boiler water in a predetermined ratio (for example, an amount corresponding to 10 to 20% of the amount of water supply) is supplied to the boiler can body continuously or intermittently. To discharge from. And the boiler water discharged from the boiler can body and containing the concentrated silica is supplied to the water supply to the boiler through the boiler water collection path and the boiler water supply path by the pressure in the boiler can body. , Mixed to increase the pH and silica concentration of the feed water.

Here, the pH of the feed water mixed with boiler water can suppress the corrosion of non-passivated metal in the lower part of the boiler can body (particularly, in the case of a once-through boiler, the connection part between the heat transfer pipe and the lower header). The value, specifically, the pH is adjusted to be in the range of 9 to 11.5. Moreover, the silica concentration of the feed water mixed with boiler water can form a film on the non-passivated metal in the lower part of the boiler can body (particularly, in the case of a once-through boiler, the connection part between the heat transfer pipe and the lower header). It is adjusted so as to be a predetermined value or more. The feed water whose pH and silica concentration are adjusted is supplied to the boiler can body through the feed water path. Therefore, in this first embodiment, the alkali component and silica in the feed water are collected while being concentrated in the boiler can, and then added to the feed water and repeatedly reused.

  As described above, according to the first embodiment, corrosion that occurs in the heat transfer tube of the boiler due to the influence of moisture can be suppressed. As a result, the boiler is prevented from being damaged, and steam can be supplied stably for a long period of time.

(Second embodiment)
Next, a second embodiment of the steam boiler apparatus according to the present invention will be described. The steam boiler apparatus according to the second embodiment mainly includes a boiler, an economizer, boiler water collecting means, and boiler water adding means. Here, detailed description of the same configuration as that of the first embodiment is omitted, and only a different configuration will be described.

  The economizer is provided in the flue of the boiler, and is configured to exchange heat between the exhaust gas from the boiler and the feed water to the boiler and to preheat the feed water. A water supply inlet of the economizer is connected to the water supply tank through the water supply path. On the other hand, the water supply outlet of the economizer is connected to the lower part of the boiler can body.

  The boiler water collection means includes the boiler water collection path and the boiler water collection valve, as in the first embodiment. The boiler water collection path is connected to, for example, the downcomer pipe or the lower part of the boiler can body in order to collect concentrated boiler water from the boiler can body, and the boiler water collection path includes the boiler water collection path. A valve is provided. The boiler water sampling valve is normally controlled to open and close continuously or intermittently during combustion of the boiler.

  In the second embodiment, the boiler water addition means includes a storage tank, a boiler water supply path, and an addition pump. The storage tank stores boiler water collected from the boiler can body via the boiler water collection path, and one end side of the boiler water supply path is connected to the storage tank. The other end side of the boiler water supply path is connected to the upstream side of the economizer, for example, the water supply tank or the water supply path. The boiler water supply path is provided with the addition pump. That is, the boiler water discharged continuously or intermittently from the boiler can body is stored in the storage tank, and then supplied to the upstream side of the economizer via the boiler water supply path. Has been. The addition pump is controlled to operate continuously or intermittently during combustion of the boiler, that is, when feed water is supplied to the boiler can body.

  Moreover, since the boiler water from the said boiler can body is discharged | emitted in the heated state, you may provide a heat exchanger in the said water supply tank or the said water supply path | route for the objective of collect | recovering the heat of boiler water. In this case, boiler water is supplied from the storage tank to the heat exchanger, and the boiler water supply path is connected so as to supply cooled boiler water to the feed water before being supplied to the economizer. Here, when the said heat exchanger is provided in the said water supply tank, water supply is heated with the heat of boiler water, and deoxygenation of water supply is accelerated | stimulated. Therefore, if comprised in this way, the corrosion by the dissolved oxygen of the heat exchanger tube of the said economizer can be suppressed effectively.

  On the other hand, when not providing the said heat exchanger, it is preferable to comprise so that the boiler water in the said storage tank may be directly supplied to the feed water stored in the said water supply tank. When the boiler water in a heated state is directly supplied to the feed water, the feed water is heated by the heat of the boiler water, and deoxygenation of the feed water is promoted. Therefore, if comprised in this way, the corrosion by the dissolved oxygen of the heat exchanger tube of the said economizer can be suppressed effectively.

  Furthermore, a water quality meter, such as a pH meter, may be provided in the water supply path, as in the first embodiment. Based on the detection result of the water quality meter, the amount of boiler water added to the feed water can be adjusted more accurately by operating the addition pump.

  Hereinafter, the operation of the boiler apparatus according to the second embodiment will be described. First, as in the first embodiment, the steam boiler device continuously or intermittently maintains a predetermined ratio (for example, 10 to 20% of the water supply amount) so as to maintain the pH of the boiler water in the range of 11 to 12. The amount of the alkaline boiler water is discharged from the boiler can body. That is, during the combustion of the boiler, the boiler water collection valve is controlled to open and close to discharge alkaline boiler water from the boiler can body, and the boiler water is supplied to the storage tank through the boiler water collection path. And the boiler water which contains the alkaline and concentrated silica in the said storage tank is mixed with the feed water which flows the upstream of the said economizer, and raises pH and silica concentration of feed water.

  Here, the pH of the feed water mixed with the boiler water is adjusted so as to be a value capable of suppressing the corrosion of the non-passivated metal in the economizer, specifically, in the range of pH 9 to 11.5. Further, the silica concentration of the feed water mixed with boiler water is adjusted to be equal to or higher than a predetermined value capable of forming a film on the non-passivated metal in the economizer. The feed water whose pH and silica concentration are adjusted is supplied to the economizer through the water supply path and then supplied to the boiler can body. Therefore, in this second embodiment, the alkali component and silica in the feed water are collected while being concentrated in the boiler can, and then added to the feed water and repeatedly reused.

  As described above, according to the second embodiment, it is possible to suppress the corrosion generated in the heat transfer tubes of the boiler and the economizer due to the influence of moisture. As a result, the boiler and the economizer are prevented from being damaged, and steam can be stably supplied for a long period of time.

(First Example)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration diagram of the boiler apparatus according to the first embodiment. The boiler device 1 mainly includes a boiler 2, boiler water collecting means 3, and boiler water adding means 4.

  The boiler 2 is a so-called multi-tubular water tube boiler, and is a boiler can body 8 formed by standing a large number of water tubes (heat transfer tubes) 7, 7,... Between an upper header 5 and a lower header 6. It has. The upper header 5 is connected to a steam separator 9 and a steam supply path 10, and the upper portion of the steam separator 9 is connected to a load device (not shown) and a steam pipe 11. The lower part of the steam separator 9 is connected to the lower header 6 and the downcomer 12 in order to collect the separated water. An exhaust cylinder 14 is connected to the flue 13 of the boiler 2 in order to discharge exhaust gas generated by combustion.

  The lower header 6 is connected to a water supply tank 15 by a water supply path 16, and a water supply pump 17 is provided in the water supply path 16. A makeup water supply path 18 is connected to the upstream side of the water supply tank 15, and a water softener 19 and a deoxygenation apparatus 20 are provided in this makeup water supply path 18 in order from the upstream side.

  The water softener 19 is a water treatment device for removing hardness components (calcium ions and magnesium ions) from raw water such as tap water, industrial water, and groundwater, and preventing scale formation in each water pipe 7. On the other hand, the deoxygenation device 20 is a water treatment device that removes dissolved oxygen from raw water and suppresses corrosion in the lower header 6, the water tubes 7, the water supply path 16, and the like.

  A circulation path 21 is connected to the side surface of the water supply tank 15 in order to circulate the stored water supply, and a circulation pump 22 is provided in the circulation path 21. Here, the water supply inlet 23 of the circulation path 21 is connected to the lower part of the water supply tank 15, and the water supply outlet 24 of the circulation path 21 is connected to the upper part of the water supply tank 15. In other words, the water supply in the water supply tank 15 is extracted from the lower part of the water supply tank 15 and then returned to the upper part of the water supply tank 15.

The boiler water collecting means 3 includes a boiler water collecting path 25 and a boiler water collecting valve 26. One end side of the boiler water collection path 25 is connected to the downcomer pipe 12, and the boiler water collection valve 25 is provided in the boiler water collection path 25. On the other hand, the other end side of the boiler water sampling path 25 is connected to a filter unit 27 for cleaning the collected boiler water. Here, the boiler water sampling valve 26 discharges a predetermined proportion of boiler water from the boiler can body 8 continuously or intermittently so as to maintain an appropriate boiler water concentration during combustion of the boiler 2. In this way, the controller (not shown) is controlled to open and close.

  The boiler water addition means 4 includes a boiler water supply path 28. One end side of the boiler water supply path 28 is connected to the filter unit 27. On the other hand, the other end side of the boiler water supply path 28 is connected to a portion adjacent to the water supply inlet 23 in the lower part of the water supply tank 15.

  Hereinafter, the operation of the boiler apparatus 1 according to the first embodiment will be described. First, the raw water flowing through the makeup water supply path 18 is softened by ion exchange in the soft water device 19 and then deoxygenated in the deoxygenator 20. The deoxygenated soft water is supplied to the water supply tank 15 as water supply and stored. The water supply in the water supply tank 15 is supplied via the water supply path 16 by operating the water supply pump 17 and stored as boiler water in the boiler can body 8.

  During the combustion of the boiler 2, boiler water boils by heating the boiler can body 8, and steam is generated. This steam is sent to the steam separator 9 via the steam supply path 10, and after moisture in the steam is separated to increase the dryness, the steam is supplied to the load device via the steam pipe 11. Is done. On the other hand, the water separated by the steam separator 9, that is, the separated water is returned to the boiler can body 8 through the downcomer 12.

  Alkaline components (ie, bicarbonates and carbonates) contained in the feed water are thermally decomposed by heating in the boiler can body 8 to produce hydroxides and concentrate to increase the pH of the boiler water. Let At the same time, silica, which is a corrosion inhibiting component contained in the water supply, is also concentrated. During the combustion of the boiler 2, alkaline boiler water in an amount corresponding to 10 to 20% of the water supply amount is periodically supplied to the boiler water collecting valve so as to maintain the pH of the boiler water in the range of 11 to 12. By controlling opening and closing 26, the boiler can body 8 is discharged. That is, a part of the alkaline boiler water is supplied to the filter unit 27 via the boiler water collection path 25.

  In the filter unit 27, sludge and the like contained in the boiler water is filtered and cleaned. The filtered boiler water is supplied to the feed water tank 15 via the boiler water supply path 28 by the steam pressure in the boiler can body 8. In the feed water tank 15, feed water and boiler water are circulated through the circulation path 21 and mixed uniformly by operating the circulation pump 22. As a result, the feed water to which boiler water is added has an increased pH and silica concentration. Here, the boiler water sampling is performed such that the amount of boiler water added to the feed water is adjusted to a pH range of 9 to 11.5 capable of suppressing corrosion that occurs at the connecting portion between the lower header 6 and each water pipe 7. The valve opening time and valve opening interval of the valve 26 are adjusted.

(Second embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to the drawings. The second embodiment is a modification of the first embodiment. FIG. 2 shows a schematic configuration diagram of the boiler apparatus according to the second embodiment. In FIG. 2, the same reference numerals as those in the first embodiment denote the same members, and detailed description thereof will be omitted.

In the second embodiment, the water supply path 18 extends toward the bottom of the water supply tank 15. That is, the water supply processed by the soft water device 19 and the deoxygenation device 20 is configured to flow into the bottom of the water supply tank 15. Further, the other end side of the boiler water supply path 28 is connected to a portion near the end of the water supply path 18 in the lower part of the water supply tank 15. That is, the feed water flow that flows into the bottom of the feed water tank 15 collides with the flow of boiler water that flows in through the boiler water supply path 28.

  Hereinafter, the operation of the boiler apparatus 1 according to the second embodiment will be described. First, the raw water flowing through the makeup water supply path 18 is softened by ion exchange in the soft water device 19 and then deoxygenated in the deoxygenator 20. The deoxygenated soft water is supplied to the water supply tank 15 as water supply and stored. Then, the water supply in the water supply tank 15 is supplied via the water supply path 16 by operating the water supply pump 17 and stored as boiler water in the boiler can body 8.

  During the combustion of the boiler 2, boiler water boils by heating the boiler can body 8, and steam is generated. This steam is sent to the steam separator 9 via the steam supply path 10, and after moisture in the steam is separated to increase the dryness, the steam is supplied to the load device via the steam pipe 11. Is done. On the other hand, the water separated by the steam separator 9, that is, the separated water is returned to the boiler can body 8 through the downcomer 12.

  Alkaline components (ie, bicarbonates and carbonates) contained in the feed water are thermally decomposed by heating in the boiler can body 8 to produce hydroxides and concentrate to increase the pH of the boiler water. Let At the same time, silica, which is a corrosion inhibiting component contained in the water supply, is also concentrated. During the combustion of the boiler 2, alkaline boiler water in an amount corresponding to 10 to 20% of the water supply amount is periodically supplied to the boiler water collecting valve so as to maintain the pH of the boiler water in the range of 11 to 12. By controlling opening and closing 26, the boiler can body 8 is discharged. That is, a part of the alkaline boiler water is supplied to the filter unit 27 via the boiler water collection path 25.

  In the filter unit 27, sludge and the like contained in the boiler water is filtered and cleaned. The filtered boiler water is supplied to the feed water tank 15 via the boiler water supply path 28 by the steam pressure in the boiler can body 8. In the water supply tank 15, the water supply and the boiler water are uniformly mixed by the collision of the respective water streams. As a result, the feed water to which boiler water is added has an increased pH and silica concentration. Here, the boiler water sampling is performed such that the amount of boiler water added to the feed water is adjusted to a pH range of 9 to 11.5 capable of suppressing corrosion that occurs at the connecting portion between the lower header 6 and each water pipe 7. The valve opening time and valve opening interval of the valve 26 are adjusted.

(Third embodiment)
Next, a third embodiment of the present invention will be described in detail with reference to the drawings. FIG. 3 shows a schematic configuration diagram of the boiler apparatus according to the third embodiment. In FIG. 3, the same reference numerals as those in the first embodiment and the second embodiment denote the same members, and detailed description thereof will be omitted. The boiler device 29 in the third embodiment mainly includes an economizer 30 in addition to the boiler 2, the boiler water collection means 3 and the boiler water addition means 4.

  In the boiler 2, an exhaust gas inlet 31 of the economizer 3 is connected to the flue 13, and an exhaust pipe 14 is connected to the exhaust gas outlet 32 of the economizer 3. In the exhaust gas circulation space 33 in the economizer 3, a heat transfer pipe 34 through which feed water is circulated is arranged for heat exchange with the exhaust gas, and the outlet side of the heat transfer pipe 34 is connected to the lower header 6. ing. The inlet side of the heat transfer tube 34 is connected to the water supply path 16.

A soft water device 19 is provided in the makeup water supply path 18. The water supply tank 15 is provided with a heat exchanger 35 for exchanging heat between the boiler water discharged from the boiler can body 8 and the feed water, and a boiler water inlet of the heat exchanger 35 is provided. 36 is connected to the other end side of the boiler water sampling path 25.

  The boiler water addition means 4 includes the boiler water supply path 28, a storage tank 37, and an addition pump 38 in the third embodiment. Since the storage tank 37 stores boiler water discharged from the boiler can body 8 and cooled by the heat exchanger 35, a boiler water outlet 39 of the heat exchanger 35 and a boiler water recovery path 40 are used. It is connected. The storage tank 37 is connected to a portion of the lower part of the water supply tank 15 adjacent to the water supply inlet 23 by the boiler water supply path 28, and the boiler water supply path 28 includes the addition pump 38. Is provided. The addition pump 38 is controlled by a controller (not shown) so as to operate in conjunction with the feed water pump 24 during combustion of the boiler 2.

  Hereinafter, the operation of the boiler device 29 according to the third embodiment will be described. First, the raw water flowing through the makeup water supply path 18 is softened by ion exchange in the soft water device 19. This soft water is supplied to the water supply tank 15 as water supply and stored. The water supply in the water supply tank 15 is supplied to the economizer 30 via the water supply path 16 by operating the water supply pump 17. This water supply is heat-exchanged with the exhaust gas in the heat transfer pipe 34 and preheated to a predetermined temperature. The preheated water supply is stored as boiler water in the boiler can body 8.

  During the combustion of the boiler 2, boiler water boils by heating the boiler can body 8, and steam is generated. This steam is sent to the steam separator 9 via the steam supply path 10, and after moisture in the steam is separated to increase the dryness, the steam is supplied to the load device via the steam pipe 11. Is done. On the other hand, the water separated by the steam separator 9, that is, the separated water is returned to the boiler can body 8 through the downcomer 12.

  Alkaline components (ie, bicarbonates and carbonates) contained in the feed water are thermally decomposed by heating in the boiler can body 8 to produce hydroxides and concentrate to increase the pH of the boiler water. Let At the same time, silica, which is a corrosion inhibiting component contained in the water supply, is also concentrated. During the combustion of the boiler 2, alkaline boiler water in an amount corresponding to 10 to 20% of the water supply amount is periodically supplied to the boiler water collecting valve so as to maintain the pH of the boiler water in the range of 11 to 12. By controlling opening and closing 26, the boiler can body 8 is discharged. That is, a part of the alkaline boiler water is supplied to the heat exchanger 35 through the boiler water collection path 25. In the heat exchanger 35, the boiler water and the feed water in the feed water tank 15 are subjected to heat exchange, whereby the feed water is heated and dissolved oxygen in the feed water is reduced. And the boiler water cooled with the said heat exchanger 35 is supplied to the said storage tank 37 via the said boiler water collection | recovery path | route 40, and is stored.

  Next, the addition pump 38 is operated while the water supply pump 17 is in operation (that is, during supply of water). The boiler water in the storage tank 37 is supplied to the water supply tank 15 through the boiler water supply path 28 by the discharge pressure of the addition pump 38. In the feed water tank 15, feed water and boiler water are circulated through the circulation path 21 and mixed uniformly by operating the circulation pump 22. As a result, the feed water to which boiler water is added has an increased pH and silica concentration. Here, the amount of boiler water added to the water supply is adjusted to a range of pH 9 to 11.5 that can suppress corrosion occurring at the connecting portion of the heat transfer pipe 34 and the lower header 6 and the water pipes 7 together. Further, the operation time and operation interval of the addition pump 38 are adjusted.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described in detail with reference to the drawings. The fourth embodiment is a modification of the third embodiment. FIG. 4 shows a schematic configuration diagram of the boiler apparatus according to the fourth embodiment. In FIG. 4, the same reference numerals as those in the first embodiment, the second embodiment, and the third embodiment denote the same members, and detailed descriptions thereof are omitted.

  In the fourth embodiment, a boiler water discharge path 41 is connected to the downcomer pipe 12, and a blow valve 42 is provided in the boiler water discharge path 41. In addition, one end side of the boiler water collection path 25 is connected to the bottom of the lower header 6, and the boiler water collection valve 26 is provided in the boiler water collection path 25. Here, the blow valve 42 and the boiler water sampling valve 26 continuously or intermittently supply a predetermined proportion of boiler water to the boiler can body so as to maintain an appropriate boiler water concentration during combustion of the boiler 2. 8 is controlled to open and close by a controller (not shown) so as to be discharged from the inside.

  In the fourth embodiment, the water supply path 18 extends toward the bottom of the water supply tank 15. That is, the water supply processed by the water softener 19 is configured to flow into the bottom of the water supply tank 15. Further, the other end side of the boiler water supply path 28 is connected to a portion near the end of the water supply path 18 in the lower part of the water supply tank 15. That is, the feed water flow that flows into the bottom of the feed water tank 15 collides with the flow of boiler water that flows in through the boiler water supply path 28.

  Hereinafter, the operation of the boiler device 29 according to the fourth embodiment will be described. First, the raw water flowing through the makeup water supply path 18 is softened by ion exchange in the soft water device 19. This soft water is supplied to the water supply tank 15 as water supply and stored. The water supply in the water supply tank 15 is supplied to the economizer 30 via the water supply path 16 by operating the water supply pump 17. This water supply is heat-exchanged with the exhaust gas in the heat transfer pipe 34 and preheated to a predetermined temperature. The preheated water supply is stored as boiler water in the boiler can body 8.

  During the combustion of the boiler 2, boiler water boils by heating the boiler can body 8, and steam is generated. This steam is sent to the steam separator 9 via the steam supply path 10, and after moisture in the steam is separated to increase the dryness, the steam is supplied to the load device via the steam pipe 11. Is done. On the other hand, the water separated by the steam separator 9, that is, the separated water is returned to the boiler can body 8 through the downcomer 12.

  Alkaline components (ie, bicarbonates and carbonates) contained in the feed water are thermally decomposed by heating in the boiler can body 8 to produce hydroxides and concentrate to increase the pH of the boiler water. Let At the same time, silica, which is a corrosion inhibiting component contained in the water supply, is also concentrated. During the combustion of the boiler 2, alkaline boiler water in an amount corresponding to 10 to 20% of the water supply amount is periodically supplied to the blow valve 42 and the boiler water so as to maintain the pH of the boiler water in the range of 11 to 12. The boiler water collection valve 26 is controlled to open and close to discharge from the boiler can body 8. That is, part of the alkaline boiler water is discharged out of the system via the boiler water discharge path 41. Further, a part of the alkaline boiler water is supplied to the heat exchanger 35 via the boiler water collection path 25. In the heat exchanger 35, the boiler water and the feed water in the feed water tank 15 are subjected to heat exchange, whereby the feed water is heated and dissolved oxygen in the feed water is reduced. And the boiler water cooled with the said heat exchanger 35 is supplied to the said storage tank 37 via the said boiler water collection | recovery path | route 40, and is stored.

Next, the addition pump 38 is operated while the water supply pump 17 is in operation (that is, during supply of water). The boiler water in the storage tank 37 is supplied to the water supply tank 15 through the boiler water supply path 28 by the discharge pressure of the addition pump 38. In the water supply tank 15, the water supply and the boiler water are uniformly mixed by the collision of the respective water streams. As a result, the feed water to which boiler water is added has an increased pH and silica concentration. Here, the amount of boiler water added to the water supply is adjusted to a range of pH 9 to 11.5 that can suppress corrosion occurring at the connecting portion of the heat transfer pipe 34 and the lower header 6 and the water pipes 7 together. Further, the operation time and operation interval of the addition pump 38 are adjusted.

The schematic block diagram of the boiler apparatus which concerns on 1st Example of this invention. The schematic block diagram of the boiler apparatus which concerns on 2nd Example of this invention. The schematic block diagram of the boiler apparatus which concerns on 3rd Example of this invention. The schematic block diagram of the boiler apparatus which concerns on 4th Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boiler apparatus 2 Boiler 3 Boiler water collection means 4 Boiler water addition means 29 Boiler apparatus 30 Economizer

Claims (3)

Boiler water collecting means for collecting boiler water in the boiler;
A boiler device comprising boiler water addition means for adding the collected boiler water to feed water before being supplied to the boiler. An economizer for preheating water supply to the boiler with exhaust gas from the boiler;
Boiler water collecting means for collecting boiler water in the boiler;
A boiler apparatus, comprising: boiler water addition means for adding the collected boiler water to feed water before being supplied to the economizer.   The boiler apparatus according to claim 1 or 2, wherein the collected boiler water is added to a water supply tank that stores water supplied to the boiler.

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