US20150047580A1 - Separatorless boiler - Google Patents

Separatorless boiler Download PDF

Info

Publication number
US20150047580A1
US20150047580A1 US14/384,640 US201314384640A US2015047580A1 US 20150047580 A1 US20150047580 A1 US 20150047580A1 US 201314384640 A US201314384640 A US 201314384640A US 2015047580 A1 US2015047580 A1 US 2015047580A1
Authority
US
United States
Prior art keywords
water
water level
steam
detection
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US14/384,640
Other languages
English (en)
Inventor
Koichi Masuda
Takanori Tanaka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Miura Co Ltd
Original Assignee
Miura Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Miura Co Ltd filed Critical Miura Co Ltd
Assigned to MIURA CO., LTD. reassignment MIURA CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MASUDA, KOICHI, TANAKA, TAKANORI
Publication of US20150047580A1 publication Critical patent/US20150047580A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D5/00—Controlling water feed or water level; Automatic water feeding or water-level regulators
    • F22D5/26—Automatic feed-control systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B21/00—Water-tube boilers of vertical or steeply-inclined type, i.e. the water-tube sets being arranged vertically or substantially vertically
    • F22B21/02—Water-tube boilers of vertical or steeply-inclined type, i.e. the water-tube sets being arranged vertically or substantially vertically built-up from substantially straight water tubes
    • F22B21/04—Water-tube boilers of vertical or steeply-inclined type, i.e. the water-tube sets being arranged vertically or substantially vertically built-up from substantially straight water tubes involving a single upper drum and a single lower drum, e.g. the drums being arranged transversely
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D5/00—Controlling water feed or water level; Automatic water feeding or water-level regulators
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/7287—Liquid level responsive or maintaining systems
    • Y10T137/7306—Electrical characteristic sensing

Definitions

  • the present invention relates to a boiler with a small amount of retained water in a can body.
  • the present application claims priority based on Japanese Patent Application No. 2012-060540 filed in Japan on Mar. 16, 2012 which is incorporated herein.
  • a boiler having a can body structure in which an upper header and a lower header are connected by many water pipes heated by a burner and water levels in the water pipes are lower than upper ends of the water pipes when combustion of the burner is stopped as in Patent Document 1
  • the water levels in the water pipes are excessively high, boiling in the water pipes becomes vigorous, many water droplets are discharged from the upper header together with steam, and it is impossible to obtain steam with high dryness.
  • the water levels in the water pipes are excessively low, dryness at an outlet of the can boy increases, though problems such as overheating and deformation of upper portions of the water pipes caused by heat of the combustion occur.
  • a combustion load of the boiler changes, the water levels change as well. Therefore, it is very difficult to achieve water levels with which high dryness can be obtained and the overheating does not occur.
  • the dryness in the boiler with the small amount of retained water is also influenced by concentration of water (can water) in the water pipes. If the can water is concentrated due to evaporation, an amount of water droplets associated with the steam increases due to foaming of the can water and therefore the dryness further reduces, though the water levels are the same.
  • the prior-art boiler includes a separator. Steam with low dryness flows into the separator from the upper header and what is called steam-water separation for removing moisture in the steam with the low dryness is carried out in the separator. Then, steam with high dryness is supplied from the separator to a load side.
  • the separator included in the structure disclosed in Patent Document 1 is difficult to manufacture and has many parts to be inspected after the manufacture, the structure including the separator involves high cost. On the other hand, if the structure does not include the separator, steam with desired dryness cannot be obtained.
  • the present invention has been made based on the above circumstances and its objects are to provide a separatorless boiler not including a separator and to provide a separatorless boiler with a small amount of retained water, with which desired dryness can be obtained, overheating of water pipes can be prevented, and a risk of corrosion of a can body can be reduced.
  • a separatorless boiler including: a can body which is formed by connecting an upper header and a lower header with many water pipes heated by a burner and in which water levels in the water pipes when combustion of the burner is stopped are lower than upper ends of the water pipes; a water supply means for supplying water for the boiler into the can body; and a control means which has an external water level detecting means, disposed outside the can body, communicating respectively with an internal space of the upper header and an internal space of the lower header through communication pipes, and having electrodes to detect an external water level in the can body, and which controls actuation of the water supply means according to the detected water level by the external water level detecting means,
  • control means carries out a first control for controlling actuation of the water supply means so that the water level in the can body lowers when the detected water level by the external water level detecting means exceeds a first set water level and a second control for controlling actuation of the water supply means so that the water level in the can body rises when the detected water level becomes lower than or equal to a second set water level lower than the first set water level,
  • the first set water level is set to a dryness limit water level
  • a height of the upper header is set so that dryness of steam flowing out of the upper header becomes higher than or equal to set dryness as a result of the first control
  • the second set water level is set to a water level which is higher than or equal to an overheating limit water level and which causes a circulation ratio of can water by the downcomer pipe to be higher than or equal to a set value.
  • the first set water level is set to the dryness limit water level and the height of the upper header is set so that the dryness of the steam flowing out of the upper header becomes higher than or equal to the set dryness as a result of the first control, it is possible to maintain the predetermined dryness, though the boiler does not include a separator.
  • the second set water level is set to the water level which is higher than or equal to the overheating limit water level and which causes the circulation ratio of the can water by the downcomer pipe to be higher than or equal to the set value, it is possible to maintain the predetermined circulation ratio of the can water by means of circulation of the can water through the downcomer pipe while preventing overheating of the water pipes.
  • the first set water level and/or the second set water level are/is adjusted according to one or a plurality of pressure in the can body, a temperature of supplied water, and a degree of concentration of the can water.
  • detection of the first set water level and the second set water level is carried out by a common electrode
  • determination of the first set water level by the control means is carried out based on detection of presence of water by the electrode or a lapse of a first set time since the detection of the presence of the water
  • determination of the second set water level is carried out based on detection of absence of water by the electrode or a lapse of a second set time since the detection of the absence of the water.
  • an effect of being able to maintain the predetermined dryness by adjusting the respective set times and/or an effect of being able to maintain the predetermined circulation ratio while preventing the overheating of the water pipes are/is exerted.
  • the external water level detecting means includes a first electrode for detecting the first set water level and a second electrode for detecting the second set water level
  • determination of the first set water level by the control means is carried out after detection of presence of water by the first electrode or a lapse of a third set time since the detection of the presence of the water
  • the determination of the second set water level is carried out based on detection of absence of water by the second electrode or a lapse of a fourth set time since the detection of the absence of the water.
  • an effect of being able to maintain the predetermined dryness by using the first electrode and the second electrode of the external water level detecting means and/or an effect of being able to maintain the predetermined circulation ratio while preventing the overheating of the water pipes are/is exerted.
  • the separatorless boiler with the small amount of retained water, in which the desired dryness can be obtained, the overheating of the water pipes is prevented, and the risk of corrosion of the can body can be reduced.
  • FIG. 1 is a schematic block diagram of a vertical section showing a structure of a boiler according to embodiment 1 of the present invention.
  • FIG. 2 is a flowchart for explaining a control procedure in embodiment 1.
  • FIG. 3 is a flowchart for explaining another control procedure in embodiment 1.
  • FIG. 4 is a schematic block diagram of a vertical section showing a structure of a boiler according to embodiment 2 of the present invention.
  • FIG. 5 is a diagrammatic illustration of an external water level detecting device of a boiler according to embodiment 3 of the present invention.
  • FIG. 6 is a schematic block diagram of a vertical section showing a diagrammatic structure of a boiler according to embodiment 4 of the present invention.
  • a boiler not including a separator (referred to as “separatorless boiler” and hereafter simply referred to as “boiler”) 10 according to embodiment 1 of the present invention will be described based on FIG. 1 .
  • the boiler 10 includes a can body 20 , a burner 30 which can be switched between high combustion and low combustion, fireproof material 40 , an external water level detecting device 50 , a water supply pump 60 , and a controller 70 .
  • the can body 20 includes a can body cover 21 , a lower header 22 , water pipes 23 , and an upper header 24 as its main components.
  • the can body cover 21 is formed by forming a plate material into a cylindrical shape and covers the water pipes 23 to isolate the water pipes 23 from outside.
  • the lower header 22 is formed in a hollow ring shape, a water supply pipe 80 is connected to the lower header 22 , and water for the boiler is supplied into the lower header 22 through the water supply pipe 80 .
  • a main drain pipe 81 is also connected to the lower header 22 and a main drain valve 82 is provided to the main drain pipe 81 . By opening this main drain valve 82 , can water existing in an internal space 22 A of the lower header 22 can be discharged outside.
  • the can water refers to the water for the boiler and introduced into the can body 20 (the lower header 22 , the water pipes 23 , and the like).
  • the water pipes 23 are pipe-shaped members respectively communicating with the lower header 22 and the upper header 24 and storing the can water. By heating the water pipes 23 by combustion of the burner 30 , the can water in the water pipes 23 boils.
  • the respective water pipes 23 extend along a vertical direction in FIG. 1 .
  • the many water pipes 23 are disposed.
  • An arrangement of the water pipes 23 includes an outer water pipe row 23 A disposed along a first circumference at a distance of a first radius from a radial center of the can body 20 and an inner water pipe row 23 B disposed along a second circumference at a distance of a second radius smaller than the first radius from the radial center of the can body 20 .
  • the water pipes 23 are not limited to those having the two rows, i.e., the outer water pipe row 23 A and the inner water pipe row 23 B and may include only one row or three or more rows.
  • the upper header 24 is formed into a hollow ring shape similarly to the above-described lower header 22 .
  • a hollow space inside the upper header 24 is referred to as an internal space 24 A.
  • the internal space 24 A communicates with opening portions 23 s of the water pipes 23 while communicating with an opening portion 83 s of a main steam pipe 83 through which the steam flows out.
  • the hollow space inside the lower header 22 is referred to as the internal space 22 A.
  • the structure of the can body 20 in embodiment 1 is formed by vertically connecting the lower header 22 and the upper header 24 with the many water pipes 23 .
  • a vertical dimension of the upper header 24 in embodiment 1 is set to be larger than those of the lower header 22 and the prior-art upper header 24 so that dryness of the steam becomes higher than or equal to set dryness in combination with a water level control (first control) for maintaining the dryness (described later).
  • first control water level control
  • the internal space 24 A of the upper header 24 has the larger vertical dimension than the internal space 22 A of the lower header 22 so as to perform the steam-water separating function.
  • the large vertical dimension of the internal space 24 A of the upper header 24 in this manner means a long distance of a flow path from the opening portions 23 s of the water pipes 23 positioned in a bottom face of the upper header 24 to the opening portion 83 s of the main steam pipe 83 connected to a top face of the upper header 24 .
  • the increase in the distance of the flow path between the two opening portions results in performance of the steam-water separating function.
  • the vertical dimension of the internal space 24 A is about the same as a vertical dimension of an internal space 22 A of the lower header 22 .
  • the vertical dimension of the internal space 24 A is much larger than that of the lower header 22 .
  • the internal space 24 A of the upper header 24 has such a height as to obtain a distance (time) necessary for a liquid droplet having a diameter of tens of micrometers and included in the steam to settle by gravitation against the rising steam and, as a result, to separate from the steam. If a rising speed of the steam is about 0.1 to 0.5 m/sec, for example, the height of the internal space 24 A required to obtain the desired dryness (set dryness) is 200 mm at the minimum.
  • the slower the speed of the rising steam and the greater the height of the internal space 24 A the higher the performance of the steam-water separation becomes, in general.
  • the height of the internal space 24 A is 200 mm or smaller, the time for the water droplets to separate from the steam is insufficient and the desired dryness of the steam cannot be obtained at an outlet (the opening portion 83 s ) of the can body 20 .
  • the height of the internal space 24 A is 700 mm or greater, the desired dryness can be obtained irrespective of a degree of concentration.
  • the degree of concentration of the can water it is possible to obtain the desired dryness, even if the height of the internal space 24 A is between 200 mm and 700 mm. Therefore, if the height of the internal space 24 A is 700 mm or greater, the dimension is excessively large, weight increases, and the structure is not compact, which is disadvantageous in terms of cost.
  • the above-described vertical dimension of the internal space 24 A of the upper header 24 needs to be greater than or equal to a dryness height threshold or greater than the dryness height threshold.
  • the dryness height threshold refers to a threshold of the vertical dimension of the internal space 24 A for obtaining the desired dryness of the steam (steam-water mixed fluid described later) discharged from the internal space 24 A.
  • the dryness height threshold is obtained by experiments or the like.
  • a baffle plate 25 is provided in the hollow ring-shaped internal space 24 A of the upper header 24 .
  • the baffle plate 25 is provided in the internal space 24 A so that its plate face direction is parallel to a direction perpendicular to the vertical direction.
  • the steam and the moisture included in the steam will be referred to as “steam-water mixed fluid” in the following description
  • the moisture may flow straight into the opening portion 83 s of the main steam pipe 83 together with the steam.
  • the baffle plate 25 is provided in the internal space 24 A, the flow of the steam-water mixed fluid is intercepted by the baffle plate 25 between the opening portions 23 s and the opening portion 83 s . In this way, the moisture included in the steam-water mixed fluid does not flow straight and the moisture in the steam bonds when the steam collides with the baffle plate 25 and then the moisture drops.
  • the baffle plate 25 forms a flow path extending means for extending a flow path through which the steam-water mixed fluid flows.
  • the baffle plate 25 has a function of further enhancing the performance of steam-water separation.
  • the baffle plate 25 is provided to form a ring shape.
  • the baffle plate 25 is provided almost throughout an annular area in the internal space 24 A.
  • a clearance A is provided between an outer peripheral side of the baffle plate 25 and the inner wall 24 c .
  • an inner peripheral side of the baffle plate 25 is attached at a plurality of circumferential positions to the inner wall 24 c by welding or the like. Therefore, at portions of the inner peripheral side of the baffle plate 25 and the inner wall 24 c and not attached to each other by welding or the like, clearances B exist. The clearances B are smaller than the clearance A.
  • a baffle plate 25 inclined downward from an inner peripheral side toward an outer peripheral side may be provided, for example. Also in this case, it is preferable to provide a clearance similar to the above-described clearance A between the outer peripheral side of the baffle plate 25 positioned at a lowest position and an inner wall 24 c and clearances similar to the above-described clearances B may be provided between the inner peripheral side of the baffle plate 25 and the inner wall 24 c . Moreover, a baffle plate 25 inclined downward from an outer peripheral side toward an inner peripheral side may be provided.
  • the baffle plate 25 may be formed into an arc shape, instead of being formed into the ring shape existing almost throughout the annular area of the internal space 24 A.
  • the baffle plate 25 exists at a portion of the annular area of the internal space 24 A.
  • a notch portion may be formed on an outer peripheral side or an inner peripheral side of an end portion of the arc.
  • the baffle plate 25 is positioned at an upper position in the internal space 24 A of the upper header 24 . Therefore, the moisture in the steam-water mixed fluid when it reaches the baffle plate 25 is reduced more due to drop by gravitation or collision with the inner wall 24 c when the baffle plate 25 is at the upper position than when the baffle plate 25 is at a lower position. If the steam-water mixed fluid with the reduced moisture collides with the baffle plate 25 , the steam-water mixed fluid does not flow straight toward the opening portion 83 s and therefore it takes time to reach the opening portion 83 s . As described above, by providing the baffle plate 25 at the upper position in the internal space 24 A, the steam-water separating performance of the baffle plate 25 is further enhanced.
  • the baffle plate 25 is provided at the upper position in the internal space 24 A.
  • a structure in which the baffle plate 25 is provided at a position of the dryness height threshold described in the above first embodiment, i.e., at a point of the threshold of the vertical dimension of the internal space 24 A is also preferable depending on a way of practicing.
  • an upper limit position where the baffle plate 25 is provided is set to such a height that the moisture staying on an upper face of the baffle plate 25 is not entangled (drawn) again in the steam flowing out of the opening portion 83 s .
  • the upper limit position of the attached position of the baffle plate 25 is set to a position at a predetermined distance from a ceiling face of the internal space 24 A.
  • an upper end side of a downcomer pipe 84 communicates with a lower portion of the internal space 24 A of the upper header 24 .
  • the downcomer pipe 84 is for returning the can water (the can water is often concentrated) existing in the internal space 24 A into the lower header 22 . Therefore, a lower end side of the downcomer pipe 84 communicates with the internal space 22 A of the lower header 22 .
  • a concentrated drain pipe 85 is connected to the downcomer pipe 84 and a concentrated drain valve 86 is provided to the concentrated drain pipe 85 . By opening the concentrated drain valve 86 , the concentrated can water can be discharged to the outside.
  • an electric conductivity measurement sensor not shown for measuring electric conductivity by measuring electric conductivity of the can water existing in the downcomer pipe 84 .
  • the burner 30 is provided to an upper portion of the can body 20 .
  • the burner 30 is positioned in a ring-shaped ring hole (not provided with a reference numeral) in the upper header 24 and forms a flame in an inner side (hereafter referred to as “combustion chamber 21 A”) surrounded with the water pipes 23 inside the can body cover 21 .
  • combustion chamber 21 A an inner side
  • fuel and air for combustion are supplied to the burner 30 .
  • the fireproof material 40 is provided to a lower portion of the can body 20 .
  • the fireproof material 40 closes the lower portion of the can body 20 (a portion (water pipe drawn portions) where the lower sides of the water pipes 23 are positioned and the inner side of the portion) to thereby form a radially center side of the inner water pipe row 23 B into the combustion chamber 21 A.
  • the fireproof material 40 is also provided to a portion (water pipe drawn portions) where upper sides of the water pipes 23 are positioned on an upper side inside the can body cover 21 .
  • the external water level detecting device 50 is for detecting a water level of the can water introduced into the can body 20 (the lower header 22 , the water pipes 23 , and the like).
  • the external water level detecting device 50 includes a water level control cylinder 51 and a plurality of electrodes, i.e., a first electrode 52 M and a second electrode 52 S.
  • the first electrode 52 M is for controlling the water level during high combustion and the second electrode 52 S is for controlling the water level during low combustion.
  • the water level control cylinder 51 is made of conductive metal and formed into a substantially cylindrical shape with sealed opposite ends.
  • a lower end of a communication pipe 87 a is connected to an upper end portion of the water level control cylinder 51 and an upper end of the communication pipe 87 a is connected to the internal space 24 A of the upper header 24 .
  • An upper end of a communication pipe 87 b is connected to the lower end portion of the water level control cylinder 51 and a lower end of the communication pipe 87 b is connected to the internal space 22 A of the lower header 22 .
  • the upper end portion and the lower end portion of the water level control cylinder 51 respectively communicate with the water pipes 23 through the upper header 24 and the lower header 22 and therefore the same water level as that of the can water introduced into the water pipes 23 is achieved in the water level control cylinder 51 .
  • a water supply pump 60 is connected to the lower header 22 by the water supply pipe 80 and starts to supply water to the lower header 22 when actuated by control by the controller 70 .
  • a check valve 89 is provided to the water supply pipe 80 between the lower header 22 and the water supply pump 60 to prevent the supplied can water from flowing back from the lower header 22 side to the water supply pump 60 side.
  • Detection signals from various sensors such as the external water level detecting device 50 are input to the controller 70 and the controller 70 governs actuation of drive portions of the burner 30 , the water supply pump 60 , and the like in response to the detection signals and based on a water level control procedure stored in advance.
  • the water level control procedure includes a high combustion water level control procedure and a low combustion water level control procedure.
  • the high combustion water level control procedure (an example of which is shown in FIG. 2 ) is formed to carry out a first control for turning off (stopping) the water supply pump 60 so that the water level in the can body 20 lowers when the detected water level by the first electrode 52 M of the external water level detecting device 50 exceeds a high combustion first set water level H1 and a second control for turning on (driving) the water supply pump 60 so that the water level in the can body 20 rises when the detected water level becomes equal to or lower than a high combustion second set water level H2 which is lower than the high combustion first set water level H1.
  • the high combustion first set water level H1 is set to a water level (high combustion dryness limit water level) over which the set dryness cannot be maintained during the high combustion.
  • a height of the upper header 24 is set so that dryness of the steam flowing out of the upper header 24 becomes equal to or higher than the set dryness as a result of the first control.
  • the high combustion second set water level H2 is set to a water level which is higher than or equal to a water level (high combustion overheating degree limit water level) under which the water pipes overheat and which causes a circulation ratio of the can water by the downcomer pipe 84 to be higher than or equal to a set value (set circulation ratio).
  • set circulation ratio is set to the same value during the high combustion and the low combustion, it may be set to different values.
  • determination of the high combustion first set water level H1 by the controller 70 is carried out after a lapse of a high combustion first set time T1H since detection of presence of the water by the first electrode 52 M and determination of the high combustion second set water level H2 is carried out after a lapse of a high combustion second set time T2H since detection of absence of the water by the first electrode 52 M.
  • the low combustion water level control procedure (an example of which is shown in FIG. 3 ) is formed to carry out a first control for turning off the water supply pump 60 so that the water level in the can body 20 lowers when the detected water level by the second electrode 52 S of the external water level detecting device 50 exceeds a low combustion first set water level L1 which is higher than the high combustion first set water level H1 and a second control for turning on the water supply pump 60 so that the water level in the can body 20 rises when the detected water level becomes equal to or lower than a low combustion second set water level L2 which is lower than the low combustion first set water level L1 and higher than the high combustion second set water level H2.
  • the low combustion first set water level L1 is set to a dryness limit water level during the low combustion.
  • the height of the upper header 24 is set so that dryness of the steam flowing out of the upper header 24 becomes equal to or higher than the set dryness during the low combustion as a result of the first control.
  • the low combustion second set water level L2 is set to a water level which is higher than or equal to the overheating degree limit water level and which causes the circulation ratio of the can water by the downcomer pipe 84 to be higher than or equal to the set value.
  • determination of the low combustion first set water level L1 by the controller 70 is carried out after a lapse of a low combustion first set time T1L since detection of presence of the water by the second electrode 52 S and determination of the low combustion second set water level L2 is carried out after a lapse of a low combustion second set time T2L since detection of absence of the water by the first electrode 52 S.
  • the circulation ratio is defined as (evaporation amount+downcomer water amount)/(supplied water amount).
  • the evaporation amount is an amount of steam flowing out of the upper header and the downcomer water amount is an amount of can water (circulating water) flowing down thorough the downcomer pipe.
  • the circulation ratio increases as the downcomer water amount increases.
  • the second control is for increasing the circulation ratio of the can water and timing of control of the water supply pump 60 so that the water level in the can body 20 rises, i.e., timing of determination that the water level in the can body 20 has lowered to the second set water level after the first control is when the water level has lowered to a target circulation ratio set water level.
  • the target circulation ratio set water level is a water level higher than the overheating limit water level for preventing overheating of the water pipes 23 .
  • the target circulation ratio set water level is a water level set in order to obtain the set circulation ratio as described above and the circulation ratio is 2 or lower in a through flow boiler.
  • the target circulation ratio is properly set in the following range.
  • a lower limit of the set circulation ratio is set based on a corrosion risk due to pH and dissolved oxygen concentration in the can body 20 .
  • An upper limit of the set circulation ratio is set based on a dryness limit, because it is difficult to control the dryness limit water level when the circulation ratio is excessively high.
  • the circulation ratio is 2 or lower for the highly corrosive water as in the through flow boiler, for example, the corrosion risk increases. Therefore, it is preferable that the circulation ratio is set to as high a value as possible, the value being over 2 and lower than or equal to a limit value.
  • the water supply pump 60 is actuated to supply the can water into the water pipes 23 to a predetermined height and the burner 30 is caused to burn, the can water in the water pipes 23 boils and the steam including the water droplets (liquid droplets) flows from the opening portions 23 s of the water pipes 23 into the internal space 24 A of the upper header 24 .
  • the inflow changes according to the water level by the first control. Then, the steam flows toward an outlet (opening portion 83 s ) of the can body 20 while air bubbles produced by boiling and the water droplets rolled up due to bumping are entrained in the steam.
  • the vertical dimension of the upper header 24 is set to such a height as to obtain the distance (time) necessary for the water droplet (liquid droplet) having a diameter of tens of micrometers and included in the steam to settle by gravitation against the rising steam and, as a result, to separate from the steam.
  • the necessary vertical dimension needs to be changed depending on the rising speed of the steam. In the embodiment, if the rising speed of the steam is about 0.1 to 0.5 m/sec, for example, the vertical dimension of the internal space 24 A is 200 mm to 700 mm.
  • the upper header 24 has a larger vertical dimension of the internal space 24 A than the upper header 24 in the prior art. In this way, it is possible to increase a length of the path (a length of the flow path) through which the steam-water mixed fluid flows from the opening portions 23 s of the water pipes 23 to the opening portion 83 s of the main steam pipe 83 . As a result, a major part of the moisture included in the steam adheres to the inner wall of the upper header 24 or is dropped by the action of gravitation and therefore removed from the steam.
  • the baffle plate 25 exists in the internal space 24 A of the upper header 24 , the steam-water mixed fluid does not flow straight toward the opening portion 83 s in the internal space 24 A of the upper header 24 and therefore it takes longer for the fluid to reach the opening portion 83 s .
  • the steam-water mixed fluid which tries to flow straight along the vertical direction from the opening portions 23 s of the water pipes 23 toward the opening portion 83 s of the main steam pipe 83 or the steam-water mixed fluid which tries to flow in a state close to the straight flowing state goes around to avoid the baffle plate 25 in flowing toward the opening portion 83 s of the main steam pipe 83 due to the existence of the baffle plate 25 .
  • the steam-water mixed fluid from which the major part of the moisture is removed as described above reaches an area above the baffle plate 25 or after the moisture in the steam is removed again to some extent above the baffle plate 25 , the steam-water mixed fluid reaches the opening portion 83 s of the main steam pipe 83 .
  • the desired dryness of the steam is achieved and the steam is sent through the main steam pipe 83 to a supply destination which requires supply of heat.
  • step SN the water supply pump 60 is turned on in S 2 . Then, the water level in the can body 20 rises.
  • the high combustion second set time T2H by the time the water supply pump 60 is turned off is set with high concentration in the high combustion in mind. To put it more concretely, if a degree of concentration increases, the dryness decreases and therefore it is necessary to lower the water level. Therefore, it is preferable to adjust the second set time T2H so that the set time is shorter when the degree of concentration is higher depending on the degree of concentration of the can water.
  • the degree of concentration can be detected by a concentration sensor (not shown) for detecting a combustion time or the degree of concentration of the can water.
  • the water level in the low combustion operation of the boiler 10 is controlled based on a control procedure in FIG. 3 .
  • the control in the low combustion operation is different from that in the high combustion in that the dryness, the overheating degree of the water pipes, and the circulation ratio are controlled while the high water level is obtained overall by using the second electrode 52 S for the low combustion, because boiling of the can water is gentle.
  • a flow of the control is similar to the control procedure in FIG. 2 and will not be described, because S 1 , S 2 , S 3 , and S 4 in FIG. 2 respectively correspond to S 11 , S 12 , S 13 , and S 14 in FIG. 3 .
  • the boiler 10 in embodiment 1 having the above-described structure, even if the structure does not include the separator, it is possible to send the steam of the desired dryness (set dryness) to the supply destination by means of the upper header 24 and the above-described water level control.
  • the boiler 10 does not have the separator and attached members such as a pipe line for connecting the separator and the upper header 24 and therefore it is possible to cut cost related to materials of the separator and the attached members and cost required for manufacture of the separator and the attached members.
  • the vertical dimension of the internal space 24 A of the upper header 24 is set to be larger than those of the lower header 22 and the prior-art upper header 24 .
  • the length of the path (the length of the flow path) through which the steam-water mixed fluid flows from the opening portions 23 s of the water pipes 23 to the opening portion 83 s of the main steam pipe 83 .
  • the major part of the moisture included in the steam adheres to the inner wall of the upper header 24 or is dropped by the action of gravitation and therefore can be removed.
  • the vertical dimension of the upper header 24 larger than those of the lower header 22 and the prior-art upper header 24 , it is possible to allow the steam-water separating function to be exerted satisfactorily.
  • the baffle plate 25 is provided in the internal space 24 A of the upper header 24 . Therefore, the steam-water mixed fluid collides with the baffle plate 25 and the existence of the baffle plate 25 reduces the rising speed of the steam-water mixed fluid in the internal space 24 A. As a result, the water droplets (liquid droplets) in the steam-water mixed fluid can be removed and the dryness of the steam can be increased. In other words, by disposing the baffle plate 25 , it is possible to remove the moisture more satisfactorily from the steam-water mixed fluid.
  • the second set water levels H2 and L2 are set to the target circulation ratio set water levels which are higher than the heating limit water level for preventing the overheating and therefore the overheating of the water pipes can be prevented and the water level control can be carried out at the predetermined circulation ratio.
  • the supplied water of low pH and the can water of high pH and supplied into the lower header 22 through the downcomer pipe 84 mix with each other in proper proportions, which can maintain appropriate pH in the can body 20 and reduce the risk of corrosion.
  • the low-temperature supplied water and the high-temperature can water it is possible to obtain high temperature distribution throughout the can water, which can reduce the risk of corrosion due to dissolved oxygen.
  • the detection of the first set water level and the second set water level is carried out by the common electrodes 52 M and 52 S
  • the determination of the first set water level by the controller 70 is carried out after the lapse of the set time since the detection of the presence by the electrodes 52 M and 52 S
  • the determination of the second set water level is carried out after the lapse of the set time since the detection of the absence of the water by the electrodes 52 M and 52 S.
  • the determination of the first set water level may be carried out immediately after the detection of the presence by the electrodes 52 M and 52 S or the determination of the second set water level may be carried out immediately after the detection of the absence of the water by the electrodes 52 M and 52 S.
  • a target circulation ratio set water level may be adjusted according to any one or a plurality (two or three) of pressure in a can body, a temperature of supplied water, and a degree of concentration of can water (water in the can body).
  • the higher pressure in the can body is advantageous to maintenance of the dryness but is disadvantageous to maintenance of a predetermined circulation ratio and prevention of overheating.
  • the higher temperature of the supplied water and the higher degree of concentration of the can water are disadvantageous to maintenance of the dryness but are advantageous to maintenance of the predetermined circulation ratio and prevention of the overheating.
  • the target circulation ratio set water level is raised when the pressure in the can body increases and is lowered when the temperature of the supplied water to the can body or the degree of concentration of the can water increases.
  • the first set water level and the second set water level are raised as the pressure in the can body increases and as the temperature of the supplied water or the degree of concentration of the can water drops (reduces).
  • the pressure is detected by a pressure sensor 90 for detecting the pressure (pressure of steam) in the can body 20 and the temperature is detected by a temperature sensor 100 for detecting the temperature of the supplied water in a water supply pipe 80 .
  • the first set time and the second set time are adjusted according to the detected pressure and the detected temperature. To put it concretely, timing of turning on of a water supply pump 60 is advanced (the first set time is shortened) and timing of turning off of the water supply pump 60 is delayed (the second set time is prolonged) as the pressure in the can body 20 increases and the temperature of the supplied water drops to thereby raise the water level.
  • a table in which the target circulation ratio set water level changing according to changes in the pressure in the can body and the temperature of the supplied water is stored in memory for example.
  • the target circulation ratio set water level corresponding to the detected pressure in the can body and the detected temperature of the supplied water is read from the table and a water level control by using the target circulation ratio set water level is carried out.
  • the degree of concentration of the can water can be detected at a lower portion of a downcomer pipe, for example.
  • a first set water level and a second set water level are detected by separate electrodes in embodiment 3.
  • a high combustion first electrode 52 M of an external water level detecting device 50 a first electrode 52 M 1 for detecting a high combustion first set water level H1 and a second electrode 52 M 2 for detecting a high combustion second set water level H2 are provided.
  • Determination of the first set water level H1 by a controller 70 is carried out after detection of presence of water by the first electrode 52 M 1 or after a high combustion third set time since the detection of the presence of the water and determination of the second set water level H2 is carried out after detection of absence of water by the second electrode 52 M 2 or after a lapse of a high combustion fourth set time since the detection of the absence of the water.
  • a low combustion second electrode 52 S of the external water level detecting device 50 a first electrode 52 S 1 for detecting a low combustion first set water level L1 and a second electrode 52 S 2 for detecting a low combustion second set water level L2 are provided.
  • Determination of the low combustion first set water level L1 by the controller 70 is carried out after detection of presence of water by the first electrode 52 S 1 or after a low combustion third set time since the detection of the presence of the water and determination of the low combustion second set water level L2 is carried out after detection of absence of water by the second electrode 52 S 2 or after a lapse of a low combustion fourth set time since the detection of the absence of the water.
  • the boiler 10 in embodiment 4 of the invention will be described based on FIG. 6 .
  • the invention can be similarly applied to a boiler having a structure in which a plurality of water pipes 23 are disposed in a rectangular parallelepiped arrangement as in a boiler 10 shown in FIG. 6 .
  • structures which are different from those in embodiment 1 will be mainly described and components corresponding to those in embodiment 1 will be provided with the same reference numerals and will not be described.
  • the boiler 10 shown in FIG. 6 has a can body 20 including a rectangular parallelepiped lower header 22 , a similarly rectangular parallelepiped upper header 24 , and a group of water pipes having the plurality of water pipes 23 disposed to stand vertically between both the headers 22 and 24 from a viewpoint of space saving.
  • a group of water pipes forming the can body 20 adjacent ones of the water pipes 23 disposed on opposite outer sides in a longitudinal direction are respectively connected by connecting members (not shown) to form a pair of water pipe walls (not shown). Therefore, the can body 20 has a rectangular parallelepiped compartment formed by the lower header 22 , the upper header 24 , and the pair of water pipe walls. This compartment corresponds to the combustion chamber 21 A in each of the above-described embodiments and is formed so that a flame from the burner 30 provided on one end side in the longitudinal direction flows toward an exhaust gas outlet 103 while carrying out a combustion reaction.
  • a downcomer pipe 84 similar to that in each of the above embodiments is provided in the boiler 10 shown in FIG. 6 .
  • the upper header 24 in which the concentrated can water stays and the lower header 22 into which new water for the boiler is supplied are connected by the downcomer pipe 84 so that the can water in the upper header 24 naturally circulates.
  • a control of a water level of the boiler 10 shown in FIG. 6 is carried out in the same way as in embodiment 1 described above and will not be described specifically.
  • the baffle plate 25 is used as a flow path extending means in the above-described embodiments.
  • the flow path extending means is not limited to the baffle plate 25 .
  • a labyrinth mechanism may be provided in the internal space 24 A of the upper header 24 or the internal space 24 A of the upper header 24 may be finely divided into small compartments with an inlet and an outlet positioned away from each other so as to extend the flow path through which the steam-water mixed fluid flows.
  • a fine-mesh filter may be disposed for the steam-water separation.
  • detection of the water level by the external water level detecting device 50 may be carried out not by using electrodes but by using a water level sensor (e.g., a differential pressure sensor) which can change a set water level.
  • a target circulation ratio set water level itself may be changed and a water supply pump 60 may be turned on when the water level lowers to the changed target circulation ratio set water level.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
US14/384,640 2012-03-16 2013-02-27 Separatorless boiler Abandoned US20150047580A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2012-060540 2012-03-16
JP2012060540A JP5534253B2 (ja) 2012-03-16 2012-03-16 セパレータレスボイラ
PCT/JP2013/055202 WO2013136988A1 (ja) 2012-03-16 2013-02-27 セパレータレスボイラ

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2013/055202 A-371-Of-International WO2013136988A1 (ja) 2012-03-16 2013-02-27 セパレータレスボイラ

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US14/959,833 Continuation US20160084496A1 (en) 2012-03-16 2015-12-04 Separatorless boiler

Publications (1)

Publication Number Publication Date
US20150047580A1 true US20150047580A1 (en) 2015-02-19

Family

ID=49160904

Family Applications (2)

Application Number Title Priority Date Filing Date
US14/384,640 Abandoned US20150047580A1 (en) 2012-03-16 2013-02-27 Separatorless boiler
US14/959,833 Abandoned US20160084496A1 (en) 2012-03-16 2015-12-04 Separatorless boiler

Family Applications After (1)

Application Number Title Priority Date Filing Date
US14/959,833 Abandoned US20160084496A1 (en) 2012-03-16 2015-12-04 Separatorless boiler

Country Status (5)

Country Link
US (2) US20150047580A1 (ja)
JP (1) JP5534253B2 (ja)
CN (1) CN103842723B (ja)
CA (1) CA2867455C (ja)
WO (1) WO2013136988A1 (ja)

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4294199A (en) * 1979-10-26 1981-10-13 Combustion Engineering, Inc. Steam generating magnetohydrodynamic diffuser
US4793800A (en) * 1986-01-30 1988-12-27 Lochinvar Water Heater Corporation Gas water heater/boiler
JPH0658503A (ja) * 1992-06-11 1994-03-01 Miura Kenkyusho:Kk 多管式貫流ボイラの缶体構造
JPH06147407A (ja) * 1992-10-30 1994-05-27 Ishikawajima Harima Heavy Ind Co Ltd 多管式貫流ボイラの水位制御方法
JPH06288813A (ja) * 1993-03-31 1994-10-18 Samuson:Kk 水位電極棒の異常判定方法
JPH07145906A (ja) * 1993-11-26 1995-06-06 Ebara Boiler Kk 多管式ボイラの給水装置
JPH09269102A (ja) * 1996-03-29 1997-10-14 Samson Co Ltd 高速起蒸型ボイラ
US20070221355A1 (en) * 2006-03-08 2007-09-27 Miura Co., Ltd. Electrode rod for detecting water-level, method of detecting water-level, method of controlling water-level in a boiler, and method of controlling water-level in a steam separator
JP2009180422A (ja) * 2008-01-30 2009-08-13 Miura Co Ltd ボイラ
JP2010169356A (ja) * 2009-01-26 2010-08-05 Chubu Electric Power Co Inc 電気ボイラ
US20140345545A1 (en) * 2011-12-22 2014-11-27 Miura Co., Ltd. Boiler

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2681640A (en) * 1949-10-28 1954-06-22 Michell Albert Mcilvaine Boiler construction
JPS6060503U (ja) * 1983-09-29 1985-04-26 三浦工業株式会社 多管式貫流ボイラ−
JPH01111902U (ja) * 1988-05-26 1989-07-27
CN2384107Y (zh) * 1999-08-13 2000-06-21 江苏双良锅炉有限公司 具有双水位控制的贯流蒸汽锅炉
JP2002147708A (ja) * 2000-11-16 2002-05-22 Miura Co Ltd ボイラの給水制御方法

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4294199A (en) * 1979-10-26 1981-10-13 Combustion Engineering, Inc. Steam generating magnetohydrodynamic diffuser
US4793800A (en) * 1986-01-30 1988-12-27 Lochinvar Water Heater Corporation Gas water heater/boiler
JPH0658503A (ja) * 1992-06-11 1994-03-01 Miura Kenkyusho:Kk 多管式貫流ボイラの缶体構造
JPH06147407A (ja) * 1992-10-30 1994-05-27 Ishikawajima Harima Heavy Ind Co Ltd 多管式貫流ボイラの水位制御方法
JPH06288813A (ja) * 1993-03-31 1994-10-18 Samuson:Kk 水位電極棒の異常判定方法
JPH07145906A (ja) * 1993-11-26 1995-06-06 Ebara Boiler Kk 多管式ボイラの給水装置
JPH09269102A (ja) * 1996-03-29 1997-10-14 Samson Co Ltd 高速起蒸型ボイラ
US20070221355A1 (en) * 2006-03-08 2007-09-27 Miura Co., Ltd. Electrode rod for detecting water-level, method of detecting water-level, method of controlling water-level in a boiler, and method of controlling water-level in a steam separator
JP2009180422A (ja) * 2008-01-30 2009-08-13 Miura Co Ltd ボイラ
JP2010169356A (ja) * 2009-01-26 2010-08-05 Chubu Electric Power Co Inc 電気ボイラ
US20140345545A1 (en) * 2011-12-22 2014-11-27 Miura Co., Ltd. Boiler

Also Published As

Publication number Publication date
WO2013136988A1 (ja) 2013-09-19
JP5534253B2 (ja) 2014-06-25
US20160084496A1 (en) 2016-03-24
CA2867455A1 (en) 2013-09-19
CN103842723B (zh) 2015-09-09
JP2013194950A (ja) 2013-09-30
CA2867455C (en) 2015-06-23
CN103842723A (zh) 2014-06-04

Similar Documents

Publication Publication Date Title
JP5534251B2 (ja) ボイラ
JP5534243B2 (ja) ボイラ
CA2867455C (en) Separatorless boiler
JP4374623B1 (ja) 液位検出器
JP6424534B2 (ja) ボイラ
CN207298890U (zh) 锅炉装置
CN202835324U (zh) 一种锅炉
WO2010023774A1 (ja) 液位検出器
JP5556870B2 (ja) ボイラ
JP3009793B2 (ja) 多管式貫流ボイラの水位制御方法
US4579086A (en) Vertical tube boiler
CN202835316U (zh) 一种锅炉
JP2015031467A (ja) ボイラシステム
WO2014038248A1 (ja) ボイラ
JP2019138477A (ja) 給水への薬注装置を持ったボイラ
JP2010078589A6 (ja) 液位検出器
JP2023149764A (ja) ボイラ水位の検出装置
JP2004251487A (ja) 貫流ボイラ
GB2145803A (en) Vertical tube boiler
WO2010032512A1 (ja) 給水制御装置
JPH03236502A (ja) ボイラの水位制御方法
JPH07318004A (ja) 上部管寄せを複数持った多管式貫流ボイラー
JP2000283403A (ja) 脱気装置

Legal Events

Date Code Title Description
AS Assignment

Owner name: MIURA CO., LTD., JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MASUDA, KOICHI;TANAKA, TAKANORI;REEL/FRAME:033725/0032

Effective date: 20140909

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION