JP5013062B2 - Supplying water for boiler feed water - Google Patents

Description

  The present invention relates to a method for supplying make-up water for boiler feed water, and in particular, stores the make-up water as a boiler feed water in a water storage tank, supplies steam from the water storage tank to the steam boiler, and heats the steam generated by heating. The present invention relates to a method for supplying make-up water to a water storage tank in a steam boiler apparatus used in the above.

  2. Description of the Related Art A steam boiler apparatus is known in which makeup water derived from raw water such as tap water and groundwater is stored in a water storage tank as boiler feed water, and the boiler feed water from the water storage tank is supplied to a steam boiler. For example, in the case of a once-through boiler, the steam boiler used in this steam boiler apparatus includes a large number of heat transfer tubes for generating steam by heating boiler water from boiler feed water. Since this heat transfer tube is formed using a non-passivated metal such as carbon steel, corrosion is likely to occur due to the influence of the pH of boiler water and the influence of dissolved oxygen contained in boiler feed water. This corrosion often causes fatal destruction such as opening of holes in the heat transfer tubes, and thus causes the steam boiler to prevent stable operation.

  In addition, the heat transfer tube easily adheres to the hardness contained in the boiler feed water, that is, the scale generated by calcium ions or magnesium ions. This scale lowers the thermal conductivity of the heat transfer tube and hinders smooth heating of boiler water.

  Therefore, in the steam boiler apparatus, in order to suppress corrosion and scale generation in the steam boiler, the makeup water supplied to the water storage tank is usually softened and deoxygenated (for example, Patent Document 1 and Patent). Reference 2). Here, the softening of the makeup water is performed by replacing calcium ions and magnesium ions in the makeup water with sodium ions by treatment of the makeup water using a sodium-type cation exchange resin. On the other hand, the deoxygenation treatment is performed, for example, by passing makeup water through a gas separation membrane.

  By the way, softening the make-up water removes the hardness, so scale generation can be suppressed, and hydrogen carbonate such as sodium hydrogen carbonate is generated due to sodium ions supplied by ion exchange. To do. This bicarbonate is a major component of the acid consumption (pH 4.8) of make-up water, undergoes thermal decomposition in the steam boiler to produce strong alkali, and the pH of the boiler water is within the required range (usually, JIS B8223: the range of 11.0 to 11.8 recommended in 1999), the corrosion of the steam boiler can be suppressed.

  However, since the raw water used as makeup water is tap water or groundwater as described above, the water quality varies depending on geological factors. For example, the hardness concentration of raw water may be high or low depending on the region, and is likely to fluctuate in the same region due to seasonal factors and other factors. For this reason, sodium-type cation exchange resins used for water softening are easy to break through in areas where the hardness concentration of makeup water is high, and a portion of the hardness in makeup water can be removed in a relatively short time. There is a possibility of disappearing. In this case, it becomes difficult to suppress scale formation in the steam boiler, and the proportion of hydrogen carbonate ions present as calcium salt or magnesium salt in the make-up water without being converted to sodium salt increases. Even if it undergoes thermal decomposition, the pH rise is not sufficient, and it becomes difficult for the steam boiler to set the pH of the boiler water within a required range effective for corrosion inhibition.

  On the other hand, since the dissolved oxygen concentration of raw water is affected by temperature, it tends to fluctuate constantly in an environment where the temperature of raw water is likely to fluctuate. In general, makeup water tends to increase the concentration of dissolved oxygen when the water temperature decreases. Therefore, the gas separation membrane is in a high-load state when the temperature of makeup water decreases, and the dissolved oxygen in the makeup water permeates. It becomes easy.

  Therefore, in consideration of the fact that it is difficult to suppress scale generation and corrosion in steam boilers only with softening and deoxygenation of make-up water, steam boiler devices are usually used for various types of boiler water supply. A drug is added (for example, Patent Document 1).

JP 2003-120904 A, paragraphs [0005] and [0025]. JP 2004-19970 A, paragraph [0009].

  However, the addition of chemicals to boiler feed water or the like increases the operating cost of the steam boiler device. Further, since steam water is concentrated in accordance with the generation of steam, steam boilers often drain part of boiler water from the viewpoint of chemical concentration management and dilute boiler water with new boiler feed water. In this case, the boiler water to be drained may cause environmental pollution due to the chemical, and therefore it is necessary to perform an appropriate drainage treatment such as decomposition and separation of the chemical.

  An object of the present invention is to effectively suppress corrosion and scale generation in a steam boiler without adding chemicals to boiler feed water.

  The present invention is to supply water to a storage tank in a steam boiler device that uses steam generated by storing makeup water as boiler feed water in a water storage tank and supplying the boiler feed water from the water storage tank to the steam boiler for heating. It relates to a method for supplying water. In this supply method, one resin unit is selected from a group of resin units including at least two resin units having a sodium type cation exchange resin, and makeup water is supplied by ion exchange of the selected resin unit with a sodium type ion exchange resin. Using a cross-flow type filtration device using a nanofiltration membrane and the process A for removing the hardness content from the water, set the blow amount from the cross-flow type filtration device to a predetermined blow amount, and supply the makeup water from which the hardness content has been removed Step B for filtration treatment, Step C for passing the makeup water filtered in the cross-flow type filtration device at a predetermined flow rate, Step C for removing dissolved oxygen contained in the makeup water, and passage through the oxygen removal device Between the process D for supplying makeup water to the water storage tank, and between the processes A and B, the hardness concentration, acid consumption (pH 4.8) and water temperature of the makeup water are determined. And a constant to step E.

  Here, when the hardness concentration measured in step E exceeds a predetermined concentration, another resin unit is selected in the resin unit group and step A is executed, and the acid consumption (pH 4. When step 8) is less than the predetermined value, the amount of blow from the cross-flow filtration device is set to be less than the predetermined amount in step B, and when the water temperature measured in step E is less than the predetermined temperature, step C The make-up water is passed through the deoxygenating device at a flow rate less than a predetermined flow.

  In such a supply method for boiler feed water, the makeup of the makeup water is removed from the hardness in step A, and subsequently in step B, an ionic component having a corrosion promoting action on steam boilers such as chloride ions and sulfate ions is provided. After being removed by the nanofiltration membrane, dissolved oxygen is removed in Step C. And the supplementary water processed in this way is supplied to a water storage tank in the process D, and is stored. In this series of steps, the makeup water is measured in Step E between Hardness A, Hardness Concentration, Acid Consumption (pH 4.8) and Water Temperature in Step E.

  Here, when the measured hardness concentration exceeds a predetermined concentration, that is, when there is a hardness leak in the makeup water from the resin unit due to breakthrough of the sodium-type cation exchange resin, etc., the resin unit Switch the resin unit to another in the group and execute step A. As a result, in the replenishing water thereafter, the hardness component is removed by the sodium cation exchange resin of the other resin unit in the process A, and the hardness component is more reliably removed.

  In addition, when the measured acid consumption (pH 4.8) is less than a predetermined value, that is, the bicarbonate concentration of the makeup water to be filtered in the cross-flow type filtration device is lowered, the bicarbonate in the nanofiltration membrane When it is predicted that the acid consumption (pH 4.8) of makeup water will further decrease due to the removal of salt, the amount of blow from the cross-flow type filtration device is set to be smaller than the predetermined amount of blow, and step B is performed. Execute. As a result, the replenishing water circulating in the cross-flow type filtration device increases the concentration factor and increases the bicarbonate concentration, so that a large amount of bicarbonate passes through the nanofiltration membrane. As a result, it is possible to suppress the increase in the bicarbonate concentration of the makeup water after the filtration treatment and the decrease in the acid consumption (pH 4.8) of boiler feed water.

  Furthermore, when the measured temperature of the makeup water is lower than the predetermined temperature, that is, when the dissolved oxygen concentration in the makeup water is increased, the flow rate of the makeup water is set to be lower than the predetermined flow rate in Step C. As a result, the make-up water has a longer residence time in the deoxygenation device, and dissolved oxygen is more reliably removed.

  In this supply method, for example, while performing steps A, B, C, D, and E, in the resin unit group, the sodium cation exchange resin of the resin unit other than the resin unit selected for step A is regenerated. . In this way, the resin unit other than the resin unit used for step A can be set in a state in which the ion-exchange capacity of the sodium-type ion exchange resin is increased. When the concentration exceeds a predetermined concentration, the resin unit can be smoothly switched to another in step A.

  In addition, the deoxygenation device used in this supply method is usually of a type in which the retention time of the make-up water becomes long when the flow rate of the make-up water is lowered, for example, a type in which make-up water is passed through the gas separation membrane One type selected from the group consisting of: a type that allows makeup water to pass under a reduced pressure environment, and a type that allows makeup water to pass under a heating environment.

  Since the supply method for boiler feed water according to the present invention includes the above-described steps, corrosion and scale generation in the steam boiler can be effectively suppressed without adding chemicals to the boiler feed water. .

  With reference to FIG. 1, the steam boiler apparatus which can implement the supply method of the supplementary water for boiler feed water which concerns on one Embodiment of this invention is demonstrated. In FIG. 1, a steam boiler device 1 is for supplying steam to a load device 2 which is a steam using facility such as a heat exchanger, a steam kettle, a reboiler, or an autoclave, and includes a water supply device 10 and a steam boiler 20. It is mainly equipped with.

  The water supply device 10 is for supplying boiler feed water to the steam boiler 20, a storage tank 40 for storing boiler feed water, a supply path 50 for supplying makeup water used as boiler supply water to the storage tank 40, and A control device 70 is mainly provided. The water storage tank 40 has a water supply path 41 extending from the bottom to the steam boiler 20. The water supply path 41 communicates with the steam boiler 20, and has a water supply pump 42 for sending the boiler water stored in the water storage tank 40 to the steam boiler 20.

  The supply path 50 has a water injection path 51. This water injection channel 51 is for supplying makeup water to a water storage tank 40 from a raw water tank (not shown) in which raw water supplied from a water source such as tap water, industrial water or groundwater is stored. A pretreatment device 52, a water softening device 53, a preliminary filtration device 54, a cross flow filtration device 55, and a deoxygenation device 56 are provided in this order toward the tank 40. Further, in the water injection channel 51, a hardness sensor 57, an acid consumption (pH 4.8) sensor 58, and a water temperature sensor 59 are disposed between the preliminary filtration device 54 and the crossflow filtration device 55. Further, the water injection channel 51 has a flow rate control valve 60 between the crossflow filtration device 55 and the deoxygenation device 56.

  The pretreatment device 52 is a filtration device filled with activated carbon capable of adsorbing an oxidizing agent such as sodium hypochlorite dissolved in makeup water from the raw water tank, and oxidizes sodium hypochlorite from raw water. It is for removing an agent.

  As shown in FIG. 2, the water softening device 53 includes a resin unit group 61 including two resin units, a first resin unit 61a and a second resin unit 61b. In the water softening device 53, the water injection path 51 is branched into two paths, a first path 51a and a second path 51b, by the switching valve 62, and the first path 51a communicates with the first resin unit 61a. The second path 51b communicates with the second resin unit 61b. The first path 51 a and the second path 51 b merge together at the downstream side of the resin units 61 a and 61 b and extend to the preliminary filtration device 54.

  Here, each resin unit 61a, 61b is filled with sodium-type cation exchange resin. The sodium-type cation exchange resin is for replacing the hardness component contained in the makeup water treated in the pretreatment device 52, that is, calcium ions and magnesium ions with sodium ions, and converting the makeup water into softened water. is there. The switching valve 62 is an electromagnetic valve and is used to select the water injection path 51 as either the first path 51a or the second path 51b.

  In the water softening device 53, the first resin unit 61a and the second resin unit 61b are detachable, and the sodium-type cation exchange resin can be exchanged.

  The preliminary filtration device 54 is for removing solid substances such as suspended substances and dust mixed in the makeup water softened by the water softening device 53, and for filtering and separating the solid matter. A filter medium (not shown) such as a wind filter, a pleated filter or a mesh filter is provided.

  The cross-flow filtration device 55 is for filtering and separating various dissolved components contained in the makeup water treated in the preliminary filtration device 54, that is, various ionic components and low molecular weight substances. As shown in FIG. 2, the pressure pump 80 and a filtration membrane module 81 disposed downstream of the pressure pump 80 are mainly provided. The filtration membrane module 81 includes a treatment liquid channel 82 and a water inlet channel 83. And the concentrated liquid path 84 is connected.

  The filtration membrane module 81 is configured such that when makeup water is introduced from the inlet channel 83, the makeup water filtered out from the treatment liquid channel 82 and the concentrated makeup water from the concentrate channel 84 flow out. Has been. Further, the concentrated liquid path 84 is branched into a drainage path 85 and a reflux path 86, and the reflux path 86 is connected to a water inlet path 83 on the upstream side of the pressurizing pump 80. The drainage channel 85 has a blow control valve 87 for controlling the drainage amount of makeup water, that is, the blow amount.

  The filtration membrane module 81 includes a filtration membrane (not shown) for filtering dissolved components contained in the makeup water. The filtration membrane used here is a nanofiltration membrane. The nanofiltration membrane is formed using a synthetic polymer such as a polyamide-based or polyether-based material that is generally referred to as an NF (Nanofiltration) membrane, and is an AMST (Association of Membrane Separation Technology) standard AMST- 002, “The molecular weight range of the separation target substance used at an operating pressure of 1.5 MPa and showing a removal rate of 90% or more shows 200 to 1,000, and the sodium chloride concentration of the test solution is 500 to 2,000 mg / liter. , A membrane having a sodium chloride removal rate of 5% or more and less than 93% under an evaluation condition of an operating pressure of 0.3 to 1.5 MPa ”. Incidentally, nanofiltration membranes are commercially available from various companies and can be easily obtained.

  In the filtration membrane module 81, the nanofiltration membrane is used in various shapes. That is, the nanofiltration membrane is used in various shapes such as a flat membrane type, a hollow fiber membrane type, a tubular type, and a Nomoris type.

  The treatment liquid path 82 extends from the filtration membrane module 81 and is for supplying makeup water filtered in the filtration membrane module 81 to the deoxygenation device 56.

  The deoxygenation device 56 is for removing dissolved oxygen in the make-up water filtered in the cross-flow type filter device 55, and the deoxygenation capability increases as the residence time of the make-up water passing through increases. For example, a type in which make-up water is passed through a gas separation membrane to remove dissolved oxygen (for example, a form in which make-up water is passed through the inside of the hollow fiber-like gas separation membrane while depressurizing the outside to remove dissolved oxygen. In a variety of types, such as a type that removes dissolved oxygen by passing make-up water under reduced pressure, or a type that removes dissolved oxygen by passing make-up water while heating Is used.

  The hardness component sensor 57 is for measuring the concentration of hardness component contained in the makeup water supplied from the preliminary filtration device 54, and is, for example, a colorimetric type, electrode type or titration type sensor. The acid consumption (pH 4.8) sensor 58 is for measuring the acid consumption (pH 4.8) of makeup water from the preliminary filtration device 54. For example, a colorimetric type, an electrode type or a titration type is used. Sensor. The water temperature sensor 59 is for measuring the temperature of the makeup water supplied from the preliminary filtration device 54, and is, for example, a sensor such as a thermistor, a thermocouple, or a resistance temperature detector.

  The flow rate adjustment valve 60 is an electromagnetic valve, and can arbitrarily adjust the flow rate of makeup water flowing from the crossflow filtration device 55 to the deoxygenation device 56.

  The control device 70 switches the switching valve based on the hardness content information, the acid consumption (pH 4.8) information, and the water temperature information measured by the hardness sensor 57, the acid consumption (pH 4.8) sensor 58, and the water temperature sensor 59, respectively. 62, for controlling the blow control valve 87 and the flow control valve 60.

  The steam boiler 20 is a once-through boiler, and as shown in FIG. 4, an annular storage portion 21 capable of storing boiler feed water supplied from a water supply path 41, and a large number of heat transfer tubes 22 rising from the storage portion 21 (FIG. 4). Only two are shown), and mainly includes an annular header 23 provided at the upper end of the heat transfer tube 22, a steam supply passage 24 extending from the header 23 to the load device 2, and a combustion device 25 such as a burner. The combustion device 25 can radiate combustion gas from the header 23 side toward the storage portion 21 to heat the heat transfer tube 22.

  The heat transfer tube 22 is formed using a non-passivated metal. A non-passivated metal refers to a metal that does not passivate naturally in a neutral aqueous solution, and is usually a metal other than stainless steel, titanium, aluminum, chromium, nickel, zirconium, and the like. Specifically, carbon steel, cast iron, copper, copper alloy, and the like. Carbon steel may be passivated in the presence of a high concentration of chromate ions even in a neutral aqueous solution. This passivation is due to the influence of chromate ions, and the neutral aqueous solution. It's hard to say that it's a natural passivation inside. Therefore, carbon steel belongs to the category of non-passivated metals here. In addition, copper and copper alloys are considered to be metals that are unlikely to corrode due to the influence of moisture due to their noble position in the electrochemical column (emf series), but they are naturally passive in neutral aqueous solutions. Since it does not convert to a non-passivated metal, it belongs to the category of

  Next, the operation method of the above steam boiler apparatus 1 will be described while touching the supply method of boiler water supply water. Here, in the initial state, the control device 70 switches the switching valve 62 to the first path 51a side, and the blow control valve 87 so that the blow amount from the crossflow filtration device 55 becomes the predetermined blow amount X. Further, the flow rate adjustment valve 60 is set so that the flow rate of the makeup water flowing from the crossflow filtration device 55 to the deoxygenation device 56 becomes the predetermined flow rate Y.

  During operation of the steam boiler device 1, makeup water is supplied from the raw water tank to the water storage tank 40 through the water injection channel 51, and this makeup water is stored in the water storage tank 40 as boiler feed water.

  At this time, the makeup water from the raw water tank is first supplied to the pretreatment device 52 through the water injection channel 51, where the oxidant is adsorbed and removed by the activated carbon. Subsequently, makeup water from the pretreatment device 52 flows to the water softening device 53. The makeup water that has flowed to the water softening device 53 flows to the first path 51a via the switching valve 62 and passes through the first resin unit 61a. Thereby, the hardness component contained in the makeup water is ion-exchanged with sodium ions by the sodium-type cation exchange resin, and becomes softened water from which the hardness component has been removed. This softened water contains an acid consumption (pH 4.8) component, that is, a hydrogen carbonate such as sodium hydrogen carbonate, which is generated as a result of supplying sodium ions by ion exchange.

  Incidentally, the sodium-type cation exchange resin used in the water softening device 53 is easily deteriorated due to the influence of the oxidizing agent, and the ion exchange capacity tends to be lowered. In this embodiment, the makeup water supplied to the water softening device 53 is Since the oxidizing agent is removed in the pretreatment device 52, the sodium-type cation exchange resin is hardly deteriorated. Therefore, the water softening device 53 can soften the makeup water stably over a long period of time.

  The make-up water that has become softened in the water softening device 53 is then filtered in the pre-filtering device 54 to remove suspended solids and solids such as dust, and then further filtered in the cross-flow filter 55. It is processed. In the cross-flow filtration device 55, makeup water from the preliminary filtration device 54 is continuously supplied to the filtration membrane module 81 through the water inlet 83 by the pressurizing pump 80. Part of the supplied makeup water passes through the filtration membrane and flows out to the treatment liquid path 82, and the remainder flows out to the concentrated liquid path 84 without passing through the filtration membrane. Further, part of the makeup water that has flowed out to the concentrate channel 84 is blown out of the system via the drainage channel 85, and the remainder is returned to the inlet channel 83 via the reflux channel 86. For this reason, the replenishing water supplied to the filtration membrane module 81 circulates in the apparatus while being partially concentrated.

The makeup water that permeates the filtration membrane is filtered by the filtration membrane. Accordingly, the makeup water is an ion component such as chloride ion (Cl ⁻ ) or sulfate ion (SO ₄ ²⁻ ) (hereinafter “corrosion promoting ion component”) that causes the heat transfer tube 22 of the steam boiler 20 to corrode. May be removed). On the other hand, most of the bicarbonate derived from the water softening device 53 contained in the makeup water and silica derived from the raw water (for example, when the water recovery rate in the cross-flow filtration is 90%, the former is 90% or more, the latter 40% or more) passes through the filtration membrane.

  Incidentally, since the oxidant is removed from the replenishing water from the preliminary filtration device 54 by the pretreatment device 52 and the solid matter is removed by the preliminary filtration device 54, the filtration membrane of the crossflow filtration device 55 is Deterioration due to oxidation hardly occurs, and clogging hardly occurs. Therefore, the crossflow filtration device 55 can stably remove the above-described corrosion promoting ion components from the makeup water over a long period of time.

  The makeup water filtered by the crossflow filtration device 55 flows out of the crossflow filtration device 55 through the treatment liquid path 82, and subsequently deoxygenated by the deoxygenation device 56. Thereby, the dissolved oxygen which accelerates | stimulates corrosion, especially pitting corrosion of the heat exchanger tube 22 of the steam boiler 20, etc. is removed from makeup water.

  As a result, the water supply tank 40 stores the makeup water treated in the deoxygenation device 56, that is, softened water that has been deoxygenated and from which the corrosion-promoting ionic components have been removed, as boiler feed water. This boiler feed water contains bicarbonate and silica that have passed through the filtration membrane of the cross-flow filtration device 55.

  When the water supply pump 42 is operated in a state where makeup water is stored in the water storage tank 40, the makeup water stored in the water storage tank 40, that is, boiler water supply, is supplied to the steam boiler 20 through the water supply path 41. Boiler feed water supplied to the steam boiler 20 is stored as boiler water in the storage unit 21. The boiler water rises in the heat transfer tubes 22 while being heated by the combustion device 25 through the heat transfer tubes 22 and gradually becomes steam. Then, the steam generated in each heat transfer tube 22 is collected in the header 23 and supplied to the load device 2 through the steam supply path 24.

  During operation of the steam boiler device 1 as described above, boiler feed water stored as boiler water in the steam boiler 20 contacts the inner surface of the heat transfer tube 22 and the like. In general, the heat transfer tube 22 or the like made of a non-passivated metal is susceptible to corrosion due to the influence of boiler water. However, in this embodiment, strong alkali generated by pyrolysis of bicarbonate contained in boiler feedwater raises the pH of boiler water, and this pH is a management target for corrosion inhibition recommended in JIS B8223: 1999. Since it is easy to set in a certain range of 11.0 to 11.8 and the boiler feed water is free from dissolved oxygen and corrosion-promoting ion components, the steam boiler 20 is corroded by the heat transfer tube 22 and the like, that is, locally. Pitting corrosion and thinning corrosion, which are serious corrosion, are unlikely to occur. Moreover, since the silica contained in boiler feed water forms a film | membrane in the storage part 21 of the steam boiler 20, and the internal surface of the heat exchanger tube 22, the corrosion inhibitory effect with respect to the steam boiler 20 can be heightened.

  Moreover, in this steam boiler apparatus 1, since the boiler feed water supplied to the steam boiler 20 is softened water from which the hardness has been removed, the heat transfer tube 22 is also restrained from adhering to the scale.

  During the operation of the steam boiler device 1, the hardness component sensor 57, the acid consumption (pH 4.8) sensor 58, and the water temperature sensor 59 are always the hardness component of the makeup water that flows from the preliminary filtration device 54 to the crossflow filtration device 55. Concentration, acid consumption (pH 4.8) and water temperature are each measured. The purpose of measuring the hardness concentration of the makeup water with the hardness sensor 57 is to confirm the treatment status of the makeup water in the water softening device 53, that is, the water softening status. Moreover, the purpose of measuring the makeup water acid consumption (pH 4.8) sensor 58 is to determine the amount of bicarbonate contained in the makeup water from the water softening device 53. Furthermore, the purpose of measuring the temperature of the makeup water with the water temperature sensor 59 is to predict the amount of dissolved oxygen contained in the makeup water. In the makeup water, the lower the water temperature, the higher the solubility of dissolved oxygen and the more dissolved oxygen amount. Therefore, the tendency of the dissolved oxygen amount can be predicted by the water temperature.

  When the hardness concentration of make-up water measured by the hardness sensor 57 exceeds a predetermined concentration Z set in advance, the breakthrough of the sodium-type cation exchange resin (ion exchange capacity) in the first resin unit 61a of the water softening device 53. Therefore, the control device 70 operates the switching valve 62 to switch the water injection path 51 from the first path 51a to the second path 51b. Thereby, the makeup water from the pretreatment device 52 flows to the second path 51b and is supplied to the second resin unit 61b, and is subjected to ion exchange treatment with the sodium-type cation exchange resin.

  While the water injection channel 51 is switched to the second channel 51b, the first resin unit 61a is removed from the water softening device 53, and the sodium-type cation exchange resin is replaced with a new one. In this way, when the hardness concentration of the make-up water measured by the hardness sensor 57 exceeds the predetermined concentration Z set in advance when the second resin unit 61b is used, the controller 70 causes the water injection channel 51 to be set. By switching from the second path 51b to the first path 51a, the first resin unit 61a in which the sodium-type ion exchange resin has been replaced can be subjected to ion exchange treatment of the makeup water. As described above, if the sodium-type cation exchange resin filled in the resin unit other than the resin unit selected in the resin unit group 61 (that is, the resin unit in use) is replaced while not in use, makeup water When the hardness component concentration exceeds a predetermined concentration Z set in advance, the resin unit can be quickly changed to the other one by switching the switching valve 62. Therefore, the makeup water is softened more reliably in the water softening device 53. As a result, in the water storage tank 40, makeup water having a low hardness is stored as boiler feed water. Therefore, the steam boiler 20 can generate scale effectively without adding chemicals to the boiler feed water. To be suppressed.

  When the acid consumption (pH 4.8) of the makeup water measured by the acid consumption (pH 4.8) sensor 58 is less than the predetermined value Q, the makeup water from the water softening device 53 has a bicarbonate amount. It can be determined that there are few. Therefore, the control device 70 controls the blow control valve 87 to set the blow amount of the makeup water circulating in the cross flow filtration device 55 to be smaller than the predetermined blow amount X. Thereby, in the filtration membrane module 81, the amount of newly supplied makeup water decreases and the concentration factor of circulating makeup water increases, so the bicarbonate concentration in the makeup water increases. As a result, the amount of bicarbonate passing through the filtration membrane increases, so that the acid consumption (pH 4.8) of make-up water supplied from the crossflow filtration device 55 to the deoxygenation device 56 can be increased. it can. Therefore, even if a chemical | medical agent is not added with respect to boiler feed water, boiler water becomes easy to be set to the said pH range suitable for suppression of corrosion, and the corrosion of the steam boiler 20 is suppressed.

  When the acid consumption (pH 4.8) of the makeup water measured by the acid consumption (pH 4.8) sensor 58 returns to the predetermined value Q or more, the control device 70 controls the blow control valve 87 to cross-flow. The blow amount from the mold filtration device 55 is returned to the predetermined blow amount X. As a result, the acid consumption (pH 4.8) of make-up water is prevented from excessively rising, and the pH of boiler water is prevented from rising beyond the above range. Progress is also prevented.

  Further, when the water temperature of the make-up water measured by the water temperature sensor 59 becomes lower than the predetermined water temperature T, the amount of dissolved oxygen in the make-up water is increased, and it is expected that the deoxygenation process in the deoxygenator 56 is insufficient. Therefore, the control device 70 controls the flow rate control valve 60 to reduce the flow rate of the makeup water flowing from the crossflow filtration device 55 to the deoxygenation device 56 to be less than the predetermined flow rate Y. As a result, the deoxygenation device 56 has a reduced supply flow rate of the make-up water and a longer stay time of the make-up water, thereby increasing the ability to remove dissolved oxygen from the make-up water. Therefore, the water storage tank 40 is supplied with makeup water with a small amount of dissolved oxygen even when the temperature of the makeup water decreases.

  When the water temperature of the make-up water measured by the water temperature sensor 59 returns to the predetermined water temperature T or higher, the control device 70 controls the flow rate control valve 60 and supplies the make-up water flowing from the crossflow filtration device 55 to the deoxygenation device 56. The flow rate is returned to the predetermined flow rate Y.

  As a result, the water storage tank 40 stores the makeup water from which dissolved oxygen has been removed more reliably as boiler feed water. Therefore, the steam boiler apparatus 1 does not need to add chemicals to the boiler feed water. In addition, the corrosion of the steam boiler 20, particularly the progress of pitting corrosion is effectively suppressed.

Modification (1) In the above-described embodiment, the water softening device 53 replaces the sodium-type cation exchange resin of the resin unit that is not in use. When not in use, it can be regenerated in a state where it is mounted on the water softening device 53.

  In this case, a sodium chloride aqueous solution preparation device is provided in the water softening device 53, and the sodium chloride aqueous solution is supplied from this preparation device into an unused resin unit. Thereby, the hardness component adhering to the sodium-type cation exchange resin is again exchanged with sodium ions, and the sodium-type cation exchange resin has an increased ion exchange capacity with the hardness component.

(2) In the above embodiment, the water softening device 53 uses the resin unit group 61 having the two resin units 61a and 61b, but the resin unit group 61 has three or more resin units. May be.

(3) In the above-described embodiment, the hardness sensor 57, the acid consumption (pH 4.8) sensor 58, and the water temperature sensor 59 are arranged between the preliminary filtration device 54 and the crossflow filtration device 55, and make-up water. Concentration, acid consumption (pH 4.8) and water temperature are measured, but the hardness, acid consumption (pH 4.8) and water temperature of make-up water are measured with the water softening device 53 and the prefiltration device 54. Can also be measured. However, in order to increase the deoxygenation capacity of the deoxygenation device 56, the temperature of the makeup water is preferably measured immediately before the crossflow filtration device 55 as in the above-described embodiment.

(4) In the above-described embodiments, a case where a once-through boiler is used as the steam boiler 20 is taken as an example, but the present invention can be similarly implemented even when another type is used as the steam boiler 20. it can.

1 is a schematic diagram of a steam boiler device that can implement a method for supplying makeup water according to an embodiment of the present invention. Schematic of the water softening device used in the steam boiler device. Schematic of the crossflow type filtration apparatus used in the said steam boiler apparatus. The partial cross section schematic of the steam boiler used in the said steam boiler apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steam boiler apparatus 2 Load apparatus 20 Steam boiler 40 Water storage tank 50 Supply path 53 Water softening apparatus 55 Cross flow type filtration apparatus 56 Deoxygenation apparatus 57 Hardness component sensor 58 Acid consumption (pH 4.8) sensor 59 Water temperature sensor 60 Flow rate adjustment Valve 61 Resin unit group 61a First resin unit 61b Second resin unit 87 Blow control valve

Claims (3)

Supplying the makeup water to the water storage tank in a steam boiler device that stores makeup water as boiler feed water in a water storage tank and generates steam by supplying the boiler feed water from the water storage tank to a steam boiler and heating it. The method of
One resin unit is selected from a resin unit group including at least two resin units having a sodium type cation exchange resin, and the hardness of the replenished water is determined by ion exchange of the selected resin unit with the sodium type ion exchange resin. Removing step A;
Using a cross flow type filtration device using a nanofiltration membrane, setting the blow amount from the cross flow type filtration device to a predetermined blow amount and filtering the makeup water from which the hardness has been removed,
A step C of passing the makeup water filtered in the crossflow filtration device through a deoxygenation device at a predetermined flow rate to remove dissolved oxygen contained in the makeup water;
Supplying the makeup water that has passed through the deoxygenation device to the water storage tank;
Between the step A and the step B, the step E for measuring the hardness concentration, the acid consumption (pH 4.8) and the water temperature of the makeup water,
When the hardness concentration measured in the step E exceeds a predetermined concentration, another resin unit is selected in the resin unit group and the step A is executed, and the acid consumption (pH 4. When 8) becomes less than a predetermined value, the blow amount from the crossflow filtration device is set to be smaller than the predetermined blow amount in step B, and the water temperature measured in step E is lower than the predetermined temperature Pass the make-up water through the deoxygenation device at step C below the predetermined flow rate,
Supply method of makeup water for boiler water supply.   The said sodium-type cation exchange resin of resin units other than the resin unit selected for the process A is reproduced | regenerated in the said resin unit group, performing the process A, B, C, D, and E. The supply method of the makeup water for boiler feed water as described.   The deoxygenation device includes a type that allows the makeup water to pass through a gas separation membrane, a type that allows the makeup water to pass under a reduced pressure environment, and a type that allows the makeup water to pass under a heating environment. The method for supplying boiler water supply water according to claim 1 or 2, wherein the supply water is of one type selected from the group consisting of:

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