JP2009192194A - Boiler system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiler system capable of suppressing a loss of heat and boiler water caused by contamination of a water quality measuring portion. <P>SOLUTION: This boiler system includes a water treatment portion 20 producing supply water by adjusting water quality of raw water, a boiler 1 producing steam by heating the supply water from the water treatment portion 20, a supply water quality measuring portion 4 for measuring one or more of water quality items of the supply water selected from concentrations of all kinds of dissolved salts, hardness, a silica concentration, acid consumption (pH 4.8), a concentration of a chloride ion, and a concentration of a sulfate ion, and a control means 18 calculating a concentrated blow ratio on the basis of a measured value of the supply water quality measuring portion 4 and an allowable value of the boiler water on the water quality items, and adjusting the concentrated blow amount to achieve the concentrated blow ratio. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a boiler system, and more particularly to a boiler system provided with control means for adjusting the amount of concentrated blow of boiler water.

  When the boiler is operated for a long time, the boiler water is concentrated, and the dryness of the steam is lowered due to carryover or the like. Therefore, it is necessary to appropriately replace the boiler water. Therefore, the concentration blow line provided with the concentration blow valve is connected to the boiler, and concentration blow for discharging a part of boiler water with the concentration blow valve being opened is performed at predetermined time intervals.

  However, in the method in which the concentration blow is performed at predetermined time intervals, there is no problem with the quality of the water supplied to the boiler. Loss will occur.

  Moreover, in patent document 1, in order to prevent the said carry over, the electrical conductivity detection sensor for detecting the electrical conductivity of boiler water was provided, and the electrical conductivity of this boiler water reached the set value. In some cases, a concentration blow control method for performing concentration blow is disclosed.

Japanese Utility Model Publication No. 1-170804

  However, in the concentration blow control method described in Patent Document 1, since the water quality item (electrical conductivity) of the boiler water is measured, it is possible to cope with changes in the quality of the feed water supplied to the boiler. However, since the water quality measurement unit (electric conductivity detection sensor) is easily contaminated with concentrated impurities in boiler water, there is a concern that wasteful blow will be performed due to erroneous detection of measured values, resulting in loss of heat and boiler water. There is.

  This invention is made | formed in view of the said situation, The objective is to provide the boiler system which can suppress the loss of the heat | fever and boiler water resulting from the contamination of a water quality measurement part.

That is, the gist of the present invention is as follows.
[1] A water treatment unit that adjusts the quality of raw water to generate feed water;
A boiler for generating steam by heating water supplied from the water treatment unit;
A feed water quality measuring unit for measuring one or more of water quality items selected from the total dissolved salt concentration, hardness, silica concentration, acid consumption (pH 4.8), chloride ion concentration and sulfate ion concentration;
A concentration blow rate is calculated based on a measured value of the feed water quality measurement unit and an allowable value in the boiler water of the water quality item, and control means for adjusting the concentration blow rate so as to be the concentration blow rate is provided. Featured boiler system,
[2] Three groups consisting of carryover related items (total dissolved salt concentration), corrosion related items (chloride ion concentration, sulfate ion concentration) and scale related items (hardness, silica concentration, acid consumption (pH 4.8)) The boiler system according to [1] above, wherein two or more groups are set as measurement target groups, and a feed water quality measurement unit that measures one or more water quality items from each measurement target group is provided.
[3] The water treatment unit includes a water softening device,
A membrane separation device installed downstream of the water softening device,
The boiler system according to [1] or [2], wherein the membrane separation device is any one of a nanofiltration membrane device, a reverse osmosis membrane device, and an electrodialysis device,
[4] The boiler system according to [3], wherein the water softening device is configured such that the ion exchange resin is regenerated by split flow regeneration or countercurrent regeneration.
[5] In the membrane separation device according to [3] or [4], the feed water supplied from one side of the membrane separation device passes the treated water passing through the membrane separation device and the membrane separation device. The concentrated water is divided into non-concentrated water and each is configured to flow out from the other side of the membrane separation device,
One of water quality items selected from the total dissolved salt concentration, hardness, silica concentration, acid consumption (pH 4.8), chloride ion concentration and sulfate ion concentration for any one of the feed water, the treated water and the concentrated water. It has a treated water quality measurement unit that measures the above,
The membrane separation device comprises a boiler system comprising control means for increasing the drainage amount of the concentrated water when the measured value of the treated water quality measurement unit exceeds a predetermined value,
[6] The boiler system according to [5], wherein the feed water quality measurement unit and the treated water quality measurement unit include a colorimetric sensor or an electrode type sensor.

According to the invention of [1], since the quality of the feed water before concentration is measured, it is possible to avoid useless blow due to erroneous detection of the measurement value caused by contamination of the water quality measurement unit, and heat and boiler water. Loss can be suppressed. Moreover, since the concentration blow rate is adjusted in accordance with the quality of the water supply, it is possible to perform the concentration blow that quickly responds to changes in the quality of the water supply.
According to the invention [2], in addition to the above-mentioned effects, the water quality of the feed water is measured by selecting the water quality items that widely consider the cause of the failure of the boiler. Can be reflected.
According to the invention of [3], in addition to the above-mentioned effect, the water softening device removes the hardness in the feed water, and the membrane separator provides chloride ions, sulfate ions, and other ions in the feed water. Since it is removed, it is possible to supply the boiler with high-quality water supply that reduces the cause of the failure of the boiler, thereby reducing wasteful blow.
According to the invention [4], in addition to the above effects, high-purity soft water can be obtained even if the quality of the raw water is poor. Therefore, there is no risk of scale adhesion in the membrane separator, and membrane separation performance is stabilized. As a result, high-quality water supply can be supplied to the boiler, and wasteful blow can be reduced.
According to the invention [5], in addition to the above effects, the quality of treated water, that is, the quality of the feed water to the boiler can be maintained within a predetermined range even when the quality of the feed water flowing into the membrane separation device is deteriorated. . As a result, high-quality water supply can be supplied to the boiler, and wasteful blow can be reduced.
According to the invention [6], in addition to the effects described above, it is possible to measure in real time and accurately the change in the quality of the feed water supplied to the boiler and the change in the quality of the feed water flowing into the membrane separator.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory diagram showing the configuration of an embodiment of the boiler system of the present invention.

  In FIG. 1, a boiler 1 is a known multi-tube once-through boiler provided with a burner 2 that generates steam by heating boiler water. The boiler 1 includes, for example, an annular lower header and an annular upper header, a plurality of heat transfer tubes arranged between these headers, a combustion chamber defined by each of these heat transfer tubes, The burner 2 is arranged at the upper part of the combustion chamber and is configured to heat the boiler water in each heat transfer tube to generate steam.

  A water supply line 3 is connected to the boiler 1. The water supply line 3 is provided with a water supply quality measuring unit 4, a water supply pump 5, and a check valve 6 in order from the upstream side. Further, in the water supply line 3, a water treatment unit (see FIG. 2, which will be described later) that adjusts the quality of raw water and generates water supply upstream of the feed water quality measurement unit 4. Is provided.

  Here, the feed water quality measurement unit 4 can measure one or more water quality items selected from the total dissolved salt concentration, hardness, silica concentration, acid consumption (pH 4.8), chloride ion concentration and sulfate ion concentration. At least one sensor is provided (first embodiment). Among the water quality items, the total dissolved salt concentration means the total evaporation residue (mg / liter) or electric conductivity (mS / m) (25 ° C.) defined in Japanese Industrial Standard JIS B8223: 1999.

  Among the water quality items, the total dissolved salt concentration is related to carryover, the chloride ion concentration and the sulfate ion concentration are related to corrosion, and the hardness, silica concentration and acid consumption (pH 4.8) are related to scale. Therefore, as a second embodiment of the feed water quality measurement unit 4, carryover related items (total dissolved salt concentration), corrosion related items (chloride ion concentration, sulfate ion concentration) and scale related items (hardness, silica concentration, acid consumption) Two or more groups out of three groups (quantity (pH 4.8)) may be set as measurement target groups, and a sensor group capable of measuring one or more water quality items from each measurement target group may be provided.

  Examples of the sensor constituting the feed water quality measuring unit 4 include a colorimetric sensor or an electrode sensor. By using such a sensor, it is possible to accurately measure various water quality items of the water supply in real time.

  Further, a blow line 8 having a concentrating blow valve 7 is connected to the lower portion of the boiler 1 in order to discharge boiler water concentrated with generation of steam to the outside of the system.

  A pressure sensor 9 is provided on the upper portion of the boiler 1. A steam separator 11 is connected to the upper portion of the boiler 1 through a steam extraction line 10. A steam supply line 13 having a steam valve 12 is connected to the upper end of the steam separator 11. The steam separator 11 is connected to the blow line 8 via a downcomer 14.

  A fuel supply line 16 having a fuel supply valve 15 is connected to the burner 2. The burner 2 is controlled to be turned on and off by controlling the fuel supply valve 15 to open and close.

  The feed water quality measuring unit 4, the feed water pump 5, the concentration blow valve 7, the pressure sensor 9, and the fuel supply valve 15 are connected to a control means 18 through a signal line 17. The control means 18 performs combustion control of the boiler 1, water level control of the boiler water, and concentration blow control. In addition, the control unit 18 receives the measurement value of the feed water quality measurement unit 4 via the signal line 17, and the concentration blow amount of the boiler 1 is adjusted based on the measurement value. ing.

In the boiler 1, combustion control is performed based on the detection value of the pressure sensor 9, so that the steam pressure in the upper header is in a range of a predetermined pressure P _{L to} P _H (P _L <P _H ). To be controlled. Specifically, when the detected value of the pressure sensor 9 is lowered to a pressure P _L, the control unit 18 of the burner 2 and combustion state (ON) the fuel supply valve 15 is opened condition, while the said pressure when the detection value of the sensor 9 is increased to a pressure P _H, the control unit 18 has the fuel supply valve 15 so as to the burner 2 combustion stop state as the closed state (OFF). In addition to the on / off control, the combustion control of the boiler 1 is a three-position control that gives a combustion amount in three stages of a high combustion state, a low combustion state, and a combustion stop state according to the steam pressure, or the steam pressure. Proportional control that gives a combustion amount proportional to the pressure may be used.

  Further, the control of the water level of the boiler water is controlled by the control means 18 so that the water level in each heat transfer pipe is maintained within a predetermined range based on the water level detection means (not shown) of each heat transfer pipe. 5 is controlled by on / off control.

  Then, the concentration blow control method of the said boiler 1 is demonstrated. A predetermined concentration blow rate (that is, [concentration blow amount] / [water supply amount]) is set in the control means 18. The predetermined concentration blow rate is set to a value at which the boiler water is not excessively concentrated, thereby preventing carry-over, and no waste boiler water is discharged. Thus, the control means 18 opens the concentration blow valve 7 for a predetermined valve opening time every predetermined combustion time. The predetermined concentration blow rate is a concentration blow rate when a water treatment unit to be described later functions normally and the water quality item of the feed water detected by the feed water quality measurement unit 4 is an allowable value.

  The allowable value of the water quality item can be arbitrarily set and is not particularly limited. For example, a numerical value defined in Japanese Industrial Standard JIS B8223: 1999 can be referred to. That is, when the boiler 1 is operated at a concentration blow rate of 10%, the total evaporation residue (total dissolved salt concentration) is 250 mg / liter, the electrical conductivity (total dissolved salt concentration) is 40 mS / m, and the chloride ion concentration is Allowable values can be 40 mg / liter, 0.1 mg / liter hardness, and 10-80 mg / liter acid consumption (pH 4.8). Further, the allowable value can be 60 mg / liter as the silica concentration and 40 mg / liter as the sulfate ion concentration.

  In the first embodiment of the feed water quality measurement unit 4, as described above, the water quality item selected from the total dissolved salt concentration, hardness, silica concentration, acid consumption (pH 4.8), chloride ion concentration and sulfate ion concentration. One or more of the above are selected, and a boiler system provided with a sensor capable of measuring the selected water quality item in the feed water quality measuring unit 4 is configured to measure the water quality item every predetermined time. When the measured value of the sensor exceeds the allowable value of the water quality item, a concentration blow rate higher than the normal concentration blow rate is set, and the concentration blow rate is set to the newly set concentration blow rate. The opening time of the blow valve 7 is lengthened to increase the concentration blow amount. And the said water quality item is measured for every predetermined time, and when the measured value of the said sensor is less than the allowable value of the said water quality item, it switches to a normal concentration blow rate and normal operation is performed.

  For example, when the chloride ion concentration of the feed water rises due to seasonal changes and the measured value of the chloride ion sensor as the feed water quality measurement unit 4 exceeds the allowable value, the control means 18 The concentration blow amount is increased by increasing the valve opening time of the concentration blow valve 7 so that the concentration blow rate is such that no corrosion occurs and no waste boiler water is discharged. For example, when the measured value of chloride ions exceeds 40 mg / liter, the concentration blow rate is increased from 10% to a concentration blow amount of 20%.

  In the measurement of the water quality item, when measuring a plurality of water quality items, if any one of the detected values exceeds the allowable value of the water quality item, the normal concentration blow rate It is preferable to set a high concentration blow rate and increase the concentration blow amount by extending the valve opening time of the concentration blow valve 7 so as to achieve the newly set concentration blow rate.

  According to the boiler system including the first embodiment of the feed water quality measuring unit 4 described above, the concentrated blow amount is adjusted based on the measurement value of the feed water quality measuring unit 4. Therefore, since the water quality of the feed water before concentration is measured, it is possible to avoid unnecessary blows due to erroneous detection of measurement values due to contamination of the water quality measurement unit, and to suppress heat and boiler water loss. . Moreover, since the concentration blow rate is adjusted according to the quality of the water supply, it is possible to perform the concentration blow that quickly responds to changes in the quality of the water supply.

  Moreover, in the boiler system provided with the second embodiment of the feed water quality measuring unit 4, the carry water related item (total dissolved salt concentration), the corrosion related item (chloride ion concentration, sulfate ion concentration) as the feed water quality measuring unit. And two or more of the three groups consisting of scale-related items (hardness, silica concentration, acid consumption (pH 4.8)) as measurement target groups, and measure at least one water quality item from each measurement target group. Although the sensor group to obtain is provided, by setting it as such embodiment, compared with said 1st embodiment, the water quality change of feed water can be more reliably reflected in a concentration blow.

  In the boiler system provided with the second embodiment of the feed water quality measuring unit 4, a plurality of water quality items are measured. However, in the measurement of the water quality item, even one of the water quality items exceeds the allowable value. When, as in the case of the first embodiment of the feed water quality measuring unit 4, set a concentration blow rate higher than the normal concentration blow rate, so that the newly set concentration blow rate, It is preferable to increase the concentration blow amount by lengthening the valve opening time of the concentration blow valve 7.

  Then, a water treatment part is demonstrated based on FIG. 2 and FIG. FIG. 2 is a schematic explanatory diagram showing the configuration of an embodiment of the water treatment unit constituting the boiler system of FIG. FIG. 3 is a partially enlarged view of the water treatment unit of FIG.

In FIG. 2, the water treatment unit 20 performs treatment of raw water supplied from a raw water tank (not shown) in which raw water supplied from water sources such as tap water, industrial water, and groundwater is stored to generate treated water. The part to do. The water treatment unit 20 includes a water supply line 3 to the boiler 1, and an activated carbon filtration unit 21, a water softening device 22, a prefilter 23, a membrane separation device 24, and a deaeration process connected to the water supply line 3. The portion 25 is provided in this order from the upstream side. And the treated water produced | generated in the said water treatment part 20 is stored by the feed water tank 26, and this stored treated water is supplied to the boiler 1 as feed water.

  The activated carbon filtration unit 21 adsorbs and removes an oxidizing agent derived from sodium hypochlorite dissolved in the water supply. The oxidant may oxidize the ion exchange resin (not shown) of the water softening device 22 disposed on the downstream side of the activated carbon filtration unit 21 and may reduce the ion exchange capacity early. Further, a separation membrane (a nanofiltration membrane, a reverse osmosis membrane, a cation exchange membrane, an anion exchange membrane, etc., which will be described later is shown) constituting the membrane separation device 24 arranged further downstream is oxidized and filtered. There is a risk of declining ability early. Therefore, in order to prevent such early deterioration of capacity due to oxidation, the oxidant is adsorbed and removed to maintain the treatment efficiency of the feed water and stabilize the quality of the treated water.

  The water softening device 22 removes the hardness in the feed water from which the oxidizing agent has been removed, that is, calcium ions and magnesium ions, with an ion exchange resin (not shown). Specifically, the water softening device 22 is configured to replace the hardness contained in the water supply with a monovalent cation such as sodium ion or potassium ion by an ion exchange reaction and convert the water supply to soft water. ing.

  The ion exchange resin constituting the water softening device 22 leaks into the treated water when the adsorption amount for the hardness to be removed reaches a predetermined exchange capacity. Therefore, the ion exchange resin is regenerated by bringing a regenerant (for example, a sodium chloride aqueous solution) into contact with the ion exchange resin before the adsorption amount corresponding to the hardness reaches a predetermined exchange capacity so as to restore the exchange capacity. I have to. In general, this regeneration is roughly divided into cocurrent regeneration, split flow regeneration, and countercurrent regeneration based on the relationship between the flow direction of raw water and the flow direction of the regenerant. Countercurrent regeneration is preferred.

  That is, by configuring the ion exchange resin to be regenerated by the split flow regeneration or the counter current regeneration, even when the dissolved salt concentration in the raw water is high, the hardness component is less likely to leak into the treated water, and high quality. Treated water can be secured, and the amount of regenerant used can be saved compared to the cocurrent regeneration.

  In order to prevent the separation membrane (not shown) constituting the membrane separation device 24 from being clogged with dust and turbidity in the water supply, the prefilter 23 supplies the water softened by the water softening device 22. Preliminary filtration is performed before the membrane separator 24.

  A pump 27 is provided on the upstream side of the membrane separation device 24 to pressurize and supply the softened water to the membrane separation device 24. The membrane separation device 24 is connected to a drain line 28 for draining concentrated water enriched with dissolved salts blocked by a liquid separation membrane described later to the outside of the system. The drain line 28 is connected to the water supply line 3 on the upstream side of the pump 27 by a circulating water line 29 so that a part of the concentrated water is returned to the upstream side of the pump 27. It has become.

  That is, the membrane separation device 24 captures corrosion promoting components that cause corrosion of non-passivated metal bodies that form a plurality of heat transfer tubes and upper and lower headers (not shown) of the boiler 1, and A liquid separation membrane that allows the passage of a corrosion-inhibiting component that contributes to the inhibition of corrosion is provided. Water supplied from one side of the membrane separation device 24 is treated water that passes through the membrane separation device 24, and the membrane separation device 24. And the concentrated water that does not pass through the water, respectively, and flows out from the other side of the membrane separation device 24.

  The membrane separation device 24 is preferably one of a nanofiltration membrane device, a reverse osmosis membrane device, and an electrodialysis device.

  The nanofiltration membrane device includes a nanofiltration membrane element using a nanofiltration membrane (NF membrane, NF: Nanofiltration). The nanofiltration membrane is a synthetic polymer membrane such as polyamide-based or polyether-based, and is a liquid separation membrane that can prevent permeation of particles and polymers (substances having a maximum molecular weight of about several hundreds) smaller than about 2 nm. In addition, the nanofiltration membrane includes an ultrafiltration membrane (UF membrane) capable of separating a substance having a molecular weight of about 1,000 to 300,000 and a substance having a molecular weight of about several tens in terms of filtration function. It is a liquid separation membrane having a function located in the middle of a reverse osmosis membrane (RO membrane) that can be filtered. Incidentally, the nanofiltration membrane element is commercially available from various companies and can be easily obtained.

  The nanofiltration membrane captures corrosion promoting components in the feed water. Here, the corrosion promoting component will be described. The corrosion promoting component is a portion where the corrosion of each of the heat transfer tubes of the boiler 1 is likely to occur, in particular, moisture (here, boiler water) is in contact with the inside, and from the outside. It refers to the one that acts on the inner surface of each of the heat transfer tubes to be heated and promotes the corrosion, and is usually both sulfate ions and chloride ions. Incidentally, both sulfate ions and chloride ions are important as corrosion promoting components. By the way, Japanese Industrial Standard JIS B 8223: 1999 defines various management items and recommended standards regarding the water quality of boiler water of these boilers from the viewpoint of suppressing the corrosion of special circulation boilers including once-through boilers. A reference value for chloride ion concentration is provided. On the other hand, although no mention is made of the sulfate ion concentration in boiler water, the applicant of the present application has studied the relationship between the water quality and corrosion of boiler water for many years. It has been confirmed that it acts on heat transfer tubes.

Moreover, the said nanofiltration membrane permeate | transmits the corrosion inhibitory component in feed water. The corrosion-inhibiting component acts on the inner surface of each heat transfer tube that is susceptible to corrosion of the heat transfer tubes of the boiler 1, in particular, moisture (here, boiler water) is in contact with the inside and heated from the outside. In addition, it refers to a material capable of suppressing corrosion occurring therein, and is usually silica (that is, silicon dioxide (SiO ₂ )). By the way, silica contained in water supply is a component usually contained in tap water, industrial water, groundwater, etc. used as water supply, and is generally recognized as a scale generation component in each heat transfer tube, and as much as possible. It is considered preferable to suppress the concentration. However, as a result of studying the relationship between the water quality of boiler water and corrosion for many years, the applicant of the present application has confirmed that silica contained in boiler water acts on each of the heat transfer tubes as a corrosion inhibiting component.

  Next, the reverse osmosis membrane device will be described. The reverse osmosis membrane apparatus is configured by incorporating a reverse osmosis membrane element using a reverse osmosis membrane (RO membrane, RO: Reverse Osmosis). The reverse osmosis membrane is a liquid separation membrane formed using a synthetic polymer such as polyamide. AMST-002, which is a standard of the Association for the Promotion of Membrane Separation Technology, states that “sodium chloride concentration is 500 to 2,000 mg / liter. And a membrane having a removal rate of sodium chloride of 93% or more under an evaluation condition of an operating pressure of 0.5 to 3.0 MPa ”, which is distinguished from a nanofiltration membrane. Incidentally, the reverse osmosis membrane element is commercially available from various companies and can be easily obtained. Similar to the nanofiltration membrane described above, the reverse osmosis membrane captures corrosion promoting components (ie, chloride ions and sulfate ions) present as ions in the feed water, and also inhibits corrosion inhibiting components in the feed water (ie, Silica) passes through.

  Subsequently, the electrodialysis apparatus will be described. In an electrodialysis apparatus, a cation exchange membrane (not shown), which is a liquid separation membrane, and an anion exchange membrane (not shown) are alternately disposed between electrodes (not shown) via a spacer. It is configured using an electrodialysis tank in which a desalting chamber and a concentration chamber are alternately formed. The electrodialysis device is adapted to remove ionized substances in the feed water in the desalting chamber of the electrodialysis tank while passing non-ionized substances. Therefore, in the electrodialysis apparatus, as with the nanofiltration membrane apparatus and reverse osmosis membrane apparatus, corrosion promoting components (that is, chloride ions and sulfate ions) present as ions in the feed water are captured. The corrosion inhibiting component (that is, silica) in the feed water passes through.

  As shown in FIG. 3, an inverter 30 is connected to the pump 27. The inverter 30 controls the rotational speed of the pump 27 based on a command signal from the control means 18. It has become.

  The drainage line 28 is branched to a first drainage line 28 a and a second drainage line 28 b on the downstream side of the connection point of the circulating water line 29. Each drain line 28a, 28b is provided with a first drain valve 31 and a second drain valve 32, respectively. Of these drain valves 31, 32, the drainage amount of the concentrated water is adjusted mainly by opening and closing the second drain valve 32. Furthermore, a water supply control valve 33 is provided in the water supply line 3 on the downstream side of the membrane separation device 24. The drain valves 31 and 32 and the water supply control valve 33 are opened and closed by the control means 18.

  In FIG. 3, reference signs A to G indicate locations where the treated water quality measurement unit 34 is connected. That is, the treated water quality measurement unit 34 connects the water supply line 3 (position A) between the water softening device 22 and the prefilter 23, and the water supply line connecting the prefilter 23 and the circulating water line 29. Line 3 (position B), the water supply line 3 connecting the circulating water line 29 and the pump 27 (position C), and the water supply line 3 connected to the downstream side of the membrane separator 24 ( (Position D), the drain line 28 (position E) connecting the membrane separation device 24 and the circulating water line 29, and the drain line 28 (downstream from the connection point of the circulating water line 29). Among the circulating water line 29 (position G), it is connected to one or a plurality of places.

  Here, the treated water quality measurement unit 34 measures at least one water quality item selected from the total dissolved salt concentration, hardness, silica concentration, acid consumption (pH 4.8), chloride ion concentration and sulfate ion concentration. A sensor is obtained (first embodiment). Among the water quality items, the total dissolved salt concentration is, as described above, the total evaporation residue (mg / liter) or electrical conductivity (mS / m) (25 ° C.) defined in Japanese Industrial Standard JIS B8223: 1999. ).

  Among the water quality items, the total dissolved salt concentration is related to carryover, the chloride ion concentration and the sulfate ion concentration are related to corrosion, and the hardness, silica concentration and acid consumption (pH 4.8) are related to scale. Therefore, as a second embodiment of the treated water quality measurement unit 34, carryover related items (total dissolved salt concentration), corrosion related items (chloride ion concentration, sulfate ion concentration) and scale related items (hardness, silica concentration, acid) Two or more groups out of three groups (consumption amount (pH 4.8)) may be set as measurement target groups, and a sensor group capable of measuring one or more water quality items from each measurement target group may be provided.

  Examples of the sensor constituting the treated water quality measurement unit 34 include a colorimetric sensor or an electrode sensor. By using such a sensor, it is possible to accurately measure various water quality items of the water supply in real time.

  A detection signal from the treated water quality measurement unit 34 is input to the control means 18. And the said control means 18 opens and closes said 2nd drain valve 32 based on the detection signal from the said treated water quality measurement part 34, and adjusts the drainage amount of concentrated water. In this way, by adjusting the drainage amount of the concentrated water, the quality of the treated water, that is, the feed water to the boiler can be maintained within a predetermined range even if the quality of the feed water flowing into the membrane separation device 24 deteriorates.

  The deaeration unit 25 mechanically removes dissolved oxygen contained in the treated water filtered by the membrane separator 24. The deaeration unit 25 includes a deaeration membrane module (not shown) composed of a plurality of hollow fiber-like deaeration membranes, distributes treated water from the membrane separation device 24 to one side of each deaeration membrane, This is a membrane type deaerator having a well-known configuration for degassing the dissolved oxygen in the treated water by vacuum suction of the side by a vacuum exhaust means such as a vacuum pump.

  Here, the deaeration processing unit 25 sprays treated water into, for example, a spray tower or a packed tower and depressurizes the inside of the tower to exhaust it, or a process into the spray tower or packed tower. It may be a nitrogen substitution type deoxygenation device that sprays water and supplies nitrogen gas into the tower to make contact.

  Subsequently, a water treatment method of the water treatment unit 20 will be described. First, raw water supplied from the raw water tank (not shown) passes through the activated carbon filtration unit 21 as water supplied to the boiler 1 to remove the oxidizing agent. Next, this water supply passes through the water softening device 22 and becomes soft water from which hardness has been removed. When this soft water is passed through the pre-filter 23, dust and turbidity are filtered and purified, and then supplied to the membrane separation device 24.

  In the membrane separation device 24, when the feed water passes through the separation membrane, corrosion promoting components composed of sulfate ions and chloride ions contained in the feed water are captured and removed. On the other hand, silica which is a corrosion inhibiting component contained in the feed water passes through the separation membrane together with the treated water. The treated water from the membrane separation device 24, that is, the soft water from which the corrosion promoting component is removed and containing the corrosion inhibiting component is degassed by the degassing treatment unit 25 and then supplied to the boiler 1 as the water supply tank. 26 is stored.

  As described above, when the water supplied by the water treatment unit 20 is supplied to the boiler 1, soft water containing a corrosion inhibiting component is supplied as boiler water to each of the heat transfer tubes (not shown). . As a result, the corrosion inhibiting component contained in the boiler water acts on the lower end portion of each heat transfer tube, and the corrosion in that portion is inhibited. More specifically, the corrosion-inhibiting component suppresses the thinning corrosion at the contact portion of each heat transfer tube with the boiler water, and also suppresses the generation and growth of pits, resulting in corrosion (particularly pits). The breakage of the heat transfer tube is suppressed. At this time, since the corrosion promoting component is removed from the boiler water by the membrane separation device 24, the above-described corrosion inhibiting action by the corrosion inhibiting component is hardly inhibited by the corrosion promoting component and is effectively exhibited. It becomes like this.

  By the way, in the process of adjusting the quality of the feed water by the membrane separator 24, the first drain valve 31 is normally opened and the second drain valve 32 is closed. Therefore, a part of the concentrated water generated in the membrane separation device 24 is drained from the first drainage line 28 a and the remaining part is returned to the upstream side of the pump 27 via the circulating water line 29.

  And when the detected value of the said treated water quality measurement part 34 exceeds the predetermined value of the said water quality item, the said control means 18 will open the said 2nd drain valve 32, and will increase the drainage amount of concentrated water. As a result, the amount of concentrated water recirculated to the membrane separation device 24 decreases, and the amount of water supplied newly to the membrane separation device 24 increases. As a result, in the membrane separation device 24, the concentration of the water quality item in the feed water mixed with the concentrated water is lowered, so that the concentration on the surface of the separation membrane is lowered and passes through the membrane separation device 24. An increase in the concentration of the water quality item in the treated water is suppressed. Therefore, since the separation membrane can maintain the removal capability of the water quality items, the treated water with stable water quality is continuously supplied to the boiler 1 from the membrane separation device 24. As a result, useless blow can be reduced in the boiler 1.

  The predetermined value of the water quality item can be arbitrarily set and is not particularly limited. For example, a numerical value defined in Japanese Industrial Standard JIS B8223: 1999 can be referred to. That is, when the boiler 1 is operated at a concentration blow rate of 10%, in the treated water from the membrane separation device 24, the total evaporation residue (total dissolved salt concentration) is 250 mg / liter, and the electrical conductivity (total dissolved salts). The concentration may be 40 mS / m, the chloride ion concentration may be 40 mg / liter, the hardness may be 0.1 mg / liter, and the acid consumption (pH 4.8) may be 10 to 80 mg / liter. Further, the silica concentration can be set to 60 mg / liter, and the sulfate ion concentration can be set to 40 mg / liter respectively.

  In the water treatment method, the water supply control valve 33 may be closed while the second drain valve 32 is open. In this way, all the water supplied to the membrane separation device 24 flows to the drainage line 28, so that the concentration of the water quality item in the vicinity of the membrane separation device 24 can be reduced in a short time. At the same time, the flow rate of the feed water flowing to the drain line 28 increases, so that the scale and dirt deposited on the membrane surface are peeled off by the shearing force on the separation membrane surface, thereby eliminating or reducing clogging of the separation membrane. You can also

  Although the present invention has been described based on FIGS. 1 to 3, the present invention is not limited to the embodiment of FIGS. 1 to 3, and can be appropriately changed without departing from the gist of the present invention. . For example, the condensate generated after the steam from the boiler 1 is used in load equipment may be collected in the feed water tank 26 to further reduce heat and water loss in the entire boiler facility. .

It is a schematic explanatory drawing which shows the structure of one Example of the boiler system of this invention. It is a schematic explanatory drawing which shows the structure of one Example of the water treatment part which comprises the boiler system of FIG. FIG. 3 is a partially enlarged view of the water treatment unit in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boiler 4 Feed water quality measurement part 18 Control means 20 Water treatment part 22 Water softening device 24 Membrane separator 34 Treated water quality measurement part

Claims (6)

A water treatment unit that adjusts the quality of raw water to generate feed water;
A boiler for generating steam by heating water supplied from the water treatment unit;
A feed water quality measuring unit for measuring one or more of water quality items selected from the total dissolved salt concentration, hardness, silica concentration, acid consumption (pH 4.8), chloride ion concentration and sulfate ion concentration;
A concentration blow rate is calculated based on a measured value of the feed water quality measurement unit and an allowable value in the boiler water of the water quality item, and control means for adjusting the concentration blow rate so as to be the concentration blow rate is provided. A featured boiler system.   2 out of 3 groups consisting of carryover related items (total dissolved salt concentration), corrosion related items (chloride ion concentration, sulfate ion concentration) and scale related items (hardness, silica concentration, acid consumption (pH 4.8)) The boiler system according to claim 1, further comprising a feed water quality measurement unit that measures at least one group as a measurement target group and measures at least one water quality item from each measurement target group. The water treatment unit includes a water softening device,
A membrane separation device installed downstream of the water softening device,
The boiler system according to claim 1 or 2, wherein the membrane separation device is any one of a nanofiltration membrane device, a reverse osmosis membrane device, and an electrodialysis device.   The boiler system according to claim 3, wherein the water softening device is configured such that the ion exchange resin is regenerated by split flow regeneration or counter current regeneration. The membrane separator according to claim 3 or 4, wherein the feed water supplied from one side of the membrane separator is treated water that passes through the membrane separator and concentrated water that does not pass through the membrane separator. Divided and each configured to flow out from the other side of the membrane separator,
One of water quality items selected from the total dissolved salt concentration, hardness, silica concentration, acid consumption (pH 4.8), chloride ion concentration and sulfate ion concentration for any one of the feed water, the treated water and the concentrated water. It has a treated water quality measurement unit that measures the above,
The said membrane separator is provided with the control means which increases the waste_water | drain amount of the said concentrated water when the measured value of the said treated water quality measurement part exceeds predetermined value.   The boiler system according to claim 5, wherein the feed water quality measurement unit and the treated water quality measurement unit include a colorimetric sensor or an electrode type sensor.

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