JP2008039224A - Structure of constant pressure once-through boiler and operating method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To specify a part where output pressure of the primary superheater of a constant pressure once-through boiler is suddenly increased, and to provide countermeasures therefor. <P>SOLUTION: In the start bypass system of a once-through boiler and an operating method therefor, cleaning timing or replacement timing for a resistor tube 22, or cleaning timing or replacement timing for a primary superheater bypass valve 23 is predicted on the basis of a deviation of pressure in each of tubes measured by a pressure gauge 35 in the outlet of the primary superheater 13 and a pressure gauge 36 between the resistor tube 22 and the primary superheater valve 23, or a deviation of pressure in each of tubes measured by the pressure gauge 36 between the resistor tube 22 and the primary superheater bypass valve 23 and a pressure gauge 37 in the outlet of the primary superheater bypass valve 23. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a superheater bypass system for a constant pressure once-through boiler, and more particularly to a constant pressure once-through boiler for predicting the renewal time and chemical cleaning time of piping while monitoring the degree of increase in pressure loss in the piping of the superheater bypass system. It relates to the configuration and its operation method.

FIG. 3 shows a startup bypass system diagram of a conventional constant pressure once-through boiler.
Condensate from a condenser (not shown) is deaerated by the deaerator 1, and then the feed water discharged by the boiler feed pump 2 is adjusted in flow rate by the feed water flow rate adjustment valve 4 on the outlet side and provided in the feed water pipe 7. It enters the economizer 10 of the boiler body 100 through the feed water flow meter 8 and the high pressure heater 9. The pump outlet stop valve 5 is provided to separate the upstream and downstream from the stop valve 5 so that the pickling solution does not flow downstream from the stop valve 5 when pickling the pipe. Provided for. The boiler feed pump 2 is driven by a motor, and a feed water flow rate adjustment valve 4 is provided at the outlet of the pump 2. A pump 3 driven by a steam turbine (not shown) is disposed in parallel with the pump 2 at the outlet of the deaerator 1, and the outlet of the pump 3 has the same function as the pump outlet stop valve 5. A stop valve 6 is provided.

  Moreover, the boiler main body 100 is comprised from the economizer 10, the water cooling wall 11, the cage wall 12, the primary superheater 13, the secondary superheater 18, etc., The steam produced | generated with the boiler main body 100 is used with a steam turbine.

  Further, when the boiler is started, a fluid consisting of water and / or steam is passed through the flash tank 26 using the startup bypass system and circulated to the condenser and deaerator 1 until the steam condition to be supplied to the steam turbine is satisfied. Driving is performed.

  Among the startup bypass systems of conventional constant pressure once-through boilers, the primary superheater 13 bypass system is a primary superheater provided with a primary superheater bypass pipe 20, a register tube bypass valve 21, a register tube 22, a primary superheater bypass valve 23, and the like. The bypass system of the secondary superheater 18 includes a secondary superheater bypass pipe 24, a secondary superheater bypass valve 25, a secondary superheater warming pipe 27, and a secondary superheater warming valve 28. It is comprised by the secondary superheater bypass system B which installed etc.

  In the startup bypass system, the fluid circulates in each bypass system A and B until the superheat condition in the primary superheater 13 and the secondary superheater 18 is satisfied. Although not shown in the figure, when a higher-order superheater higher than the tertiary superheater is installed in the steam pipe on the downstream side of the secondary superheater 18, the fluid is maintained until the higher-order superheated steam condition at the time of starting is satisfied. A high-order superheater bypass system that circulates is provided.

  Further, water and / or steam is supplied from the flash tank 26 to the condenser via a condenser supply pipe 31 provided with a flash tank level control valve 32. Further, water and / or steam is supplied to the deaerator 1 from a deaerator supply pipe 29 (including a deaerator level control valve 30) branched from the condenser supply pipe 31.

  A primary superheater inlet thermometer 33 is provided in the inlet pipe of the primary superheater 13, and a primary superheater outlet thermometer 34 is provided in the primary / secondary superheater communication pipe 14. The primary / secondary superheater communication pipe 14 is provided with a superheater stop valve 15, and the superheater stop valve bypass pipe 16 is provided with a superheater pressure reducing valve 17.

  If the final superheater is the secondary superheater 18 at the start-up of the once-through boiler, steam turbine ventilation and subsequent turbine insertion (electricity will be added to the power system after steam turbine ventilation) Until the outlet steam condition of the secondary superheater 18 is established, a fluid composed of water and / or steam is circulated in the primary superheater bypass system A and / or the secondary superheater bypass system B as follows. That is, until the outlet steam condition of the primary superheater 13 is established, the fluid is circulated through the flash tank 26 using the primary superheater bypass system A. When the outlet steam condition of the primary superheater 13 is established, the primary superheater bypass is established. While the system A is closed and the secondary superheater bypass system B is used to circulate the steam to the flash tank 26, the water supply and condensate circulation operations are performed with the minimum water supply amount.

  As described above, the start-up bypass systems A, B, etc., start from boiler water filling and boiler pressure increase, and supply water or condensate from the flash tank 26 through the bypass systems A, B to the condenser between the turbine aeration and turbine entry. It is a system that collects and circulates.

  Until the inlet temperature condition of the primary superheater 13 is established, as the first stage, the primary superheater bypass system A is used to circulate the entire minimum amount of water supply. A resistor tube 22 is provided to prevent noise and erosion of the primary superheater bypass valve 23 generated by flowing a fluid. The register tube 22 is provided such that a fluid bypassing a part of the primary superheater bypass pipe 20 flows around, and a register tube bypass valve 21 is installed in the primary superheater bypass pipe 20 bypassing the register tube 22. Yes. Then, until the inlet temperature of the primary superheater 13 reaches a specified value, the operation of flowing the entire amount of the minimum water supply amount through the register tube 22 with the register tube bypass valve 21 closed is performed.

  The register tube 22 has a configuration in which about five pipes having an inner diameter of about 24 mm and a length of about 15 m are arranged in parallel, and water is supplied into each pipe of the register tube 22 with a high differential pressure of 10 Mpa or more. Unlike a normal flow field, it becomes a high-speed flow field.

  In addition, the primary superheater bypass system A shown in FIG. 3 is not provided with a device for measuring the temperature / pressure of the fluid, and monitoring of the pressure / temperature of the fluid of the primary superheater bypass system A supplies steam to the steam turbine. It is only performed by an inlet thermometer 33, an outlet thermometer 34, and a primary superheater outlet pressure gauge 35 installed at the inlet and outlet of the primary superheater 13 on the mainstream side.

Controlling the flow rate of steam flowing through the superheater bypass system by the main steam pressure in the superheater is disclosed in Patent Documents 1 and 2 and the like.
JP 2000-320801 A JP-A-6-213404

  In the system provided with the start-up bypass device for the constant-pressure once-through boiler shown in FIG. 3, the outlet pressure of the primary superheater 13 having a proven operation has a tendency to increase as the operation of the boiler continues. As previously known, since the outlet pressure of the primary superheater 13 tends to increase over time, the opening degree of the primary superheater bypass valve 23 is changed over time in order to keep it equal to the initial value. In response, it was enlarged. However, a phenomenon in which the outlet pressure of the primary superheater 13 suddenly rises after a decade has passed since the start of operation has occurred, and the pressure control of the primary superheater bypass system A has become impossible. It was.

  For this reason, in the conventional countermeasure, when the opening degree of the primary superheater bypass valve 23 reaches the control upper limit value, the feed water flow rate flowing to the primary superheater bypass system A must be reduced, and then the primary superheater bypass valve 23 again. Even if the degree of opening was increased again, the upper limit of control was exceeded, making it impossible to cope with it, and the bypass system had to be cut off and pickled with a strong acid such as sulfuric acid. Such a problem has also occurred in the secondary superheater bypass system B and higher superheater bypass systems.

  Then, the subject of this invention is specifying the location where the rapid rise of the outlet pressure of the superheater of a constant pressure once-through boiler generate | occur | produces, and providing the countermeasure.

The above-described problems of the present invention can be achieved by the following solution means.
That is, the invention of claim 1 consists of a heat transfer tube panel in which water or steam flows inside, a water cooling wall (11) constituting the peripheral wall of the boiler furnace, and a heat transfer tube panel in which water or steam flows inside, A gauge wall (12) that constitutes the peripheral wall of the flue that is a flow path through which combustion gas generated by the combustion of fuel in the boiler furnace is discharged toward the chimney disposed downstream of the furnace, and superheated steam inside A primary superheater (13) provided in the flue, and a heat transfer pipe through which superheated steam flows, and is provided in at least two flues downstream of the primary superheater (13). A high-order superheater including a secondary superheater (18) and a heat transfer tube panel through which water flows, and a node provided in a flue downstream of the high-order superheater including the secondary superheater (18) Constant pressure with charcoal (10) A flow boiler, a condenser for condensing the steam obtained in the once-through boiler after being used as a load target, and water saving from the condenser (10), water cooling wall (11), gauge After sequentially supplying to the wall (12), the primary superheater bypass system (A) for bypassing from the inlet of the primary superheater (13) to the condenser, and the superheated steam from the outlet of the primary superheater (13) In a constant pressure once-through boiler configuration including a high-order superheater bypass system including a secondary superheater bypass system (B) that is bypassed from the inlet of the secondary superheater (18) to the condenser, the primary superheater bypass system ( A) is provided with a register tube (22), its bypass valve (21) and a primary superheater bypass valve (23) from the upstream side, in the pipe of the economizer (10) inlet or the primary superheater (13) outlet. Pressure gauge to measure pressure (42 or 35 A pressure gauge (36) for measuring the pressure in the pipe (20) between the register tube (22) and the primary superheater bypass valve (23), and a pipe at the outlet of the primary superheater bypass valve (23) ( 24) A pressure gauge (37) for measuring the internal pressure, and a pressure gauge (43, etc.) for measuring the pressure in the outlet and inlet piping of the secondary superheater (18) and higher, respectively. It is a constant pressure once-through boiler configuration.

  Invention of Claim 2 is the operation method of the constant pressure once-through boiler structure of Claim 1, Comprising: (a) The pressure gauge (42 or 35) of the said economizer (10) entrance or primary superheater (13) exit ) And the pressure gauge (36) between the register tube (22) and the primary superheater bypass valve (23), or (b) the register tube (22) and the primary superheater bypass. Cleaning time of the register tube (22) based on the deviation of the pressure in each pipe measured by the pressure gauge (36) between the valves (23) and the pressure gauge (37) at the outlet of the primary superheater bypass valve (23) Or it is the operation method of the constant pressure once-through boiler configuration that predicts the replacement time or the cleaning time or replacement time of the primary superheater bypass valve (23).

  Invention of Claim 3 is an operation method of the constant pressure once-through boiler structure of Claim 1, Comprising: The pipe | tube (24) through which the vapor | steam of the inlet and outlet of a high-order superheater more than the said secondary superheater (18) distribute | circulates. , 19 etc.) The cleaning time of the high-order superheater bypass valve of the secondary superheater (18) or more based on the deviation of the pressure in each pipe measured by a pressure gauge (35, 43, etc.) that measures the pressure in the secondary superheater (18, etc.) This is an operation method of a constant pressure once-through boiler configuration for predicting the replacement time.

(Function)
As shown in FIG. 3, the primary superheater bypass system A of the constant pressure once-through boiler is provided with a resistor tube 22 that bears a resistance of 10 Mpa or more. However, the tube diameter of the resistor tube 22 is very thin, Since the flow is a high-speed flow of about 50 m / s unlike a normal flow field, the pressure loss is greatly influenced by the scale adhesion, particularly the surface roughness.

  Further, in the primary superheater bypass system A shown in FIG. 3, the water state and the steam state flow are generated by the boiler starting process. Therefore, the scale and steam of the water system are formed on the pipe inner surfaces such as the register tube 22 and the primary superheater bypass valve 23. The scale of the system adheres. Since these scale adhering sites are sites where chemical cleaning cannot be performed, the scales cannot be removed when attached to the boiler.

  Since the water scale is a porous scale, it is not only difficult to measure by non-destructive inspection, but also because the scale adhesion site of the primary superheater bypass system A cannot be subjected to chemical cleaning. It cannot be predicted. Furthermore, even if it is found by a sample survey that the surface roughness of the scale, which is the cause of the uncontrollability of the primary superheater bypass valve 23 found by the present invention, is obtained, this scale surface roughness should be accurately measured. Therefore, it is difficult to predict and monitor the update time of the register tube 22 or the chemical cleaning time.

  In addition, since the pressure monitoring instrument is not installed in the conventional primary bypass system A shown in FIG. 3, it is difficult to determine the specific portion where the pressure loss increases and to measure the amount of increase in the pressure loss.

  Incidentally, FIG. 2A is a graph showing a change in the pressure loss of the register tube 22 with respect to the operating history (elapsed operating time) of a specific boiler. As shown in this graph, the increase in the pressure loss of the register tube 22 is shown. The trend has risen sharply from a certain point. The cause of this abnormal pressure rise was investigated during boiler periodic inspection, but it was confirmed that there was no clogging of the register tube 22 or the primary superheater bypass valve 23 or a reduction in the inner diameter of the tube due to excessive scale adhesion. However, it was confirmed that the inner surface of the register tube 22 has a surface roughness (unevenness) of 20 to 50 μm. In addition, the space | gap exists in the inside of the said adhesion scale layer, and it was confirmed that this scale is a porous type water scale.

  Moreover, in FIG.2 (b), the graph which shows the average surface roughness of the register | resistor tube 22 with respect to the operation history (operating time progress) of a specific boiler is shown.

  The present inventor has found that the abnormal increase in the pressure inside the register tube 22 is caused by the surface roughness of the scale attached to the pipe such as the register tube 22 from the comparison between the data shown in FIG. 2A and the data shown in FIG. I found out that it was.

  By the way, the boiler from which the graphs shown in FIGS. 2 (a) and 2 (b) are obtained is an oil-fired boiler, and at the start of operation at the left end of the figure, continuous operation is performed to supplement the base load of power consumption. The number of times the boiler is started and stopped is about once a month. At this time, the pressure loss of the register tube 22 and the average surface roughness of the adhesion scale in the tube tend to gradually increase to the right over time in both FIGS. 2 (a) and 2 (b).

  However, the energy situation changed from the middle of the operating history graphs shown in FIGS. 2 (a) and 2 (b), and nuclear power generation became the base load as power generation energy, and oil-fired boilers that use expensive oil are Or it is used for peak load according to the season. For this reason, boilers for thermal power generation are now subject to DSS (Daily Start Daily Stop) that repeats starting and stopping every day from a state where starting and stopping are repeated on weekends, and further, rapid load change operation in response to time peaks. It was. FIG. 2C is a graph showing the relationship between the number of times of starting and stopping the thermal power generation boiler and the operating history.

  The time when the boiler for the thermal power generation starts to suddenly increase the number of times of starting and stopping due to the change of the situation of the power plant shown in FIG. 2C, the time when the pressure loss of the register tube 22 shown in FIG. It was found to be consistent with

  It has become clear that pressure loss is related to the number of boiler start / stop times shown in FIG. 2 (c) (in recent years, the number of boiler start / stop times has increased significantly). This is probably because the fluid flowing through the primary superheater bypass system A sometimes used is in a water state, and the scale component contained in the water state fluid is likely to adhere to the register tube 22.

  FIG. 2 (d) shows a graph for determining whether the valve is abnormal or normal from the relationship between the actual opening of the start valve of the boiler for thermal power generation and the calculated opening of the start valve.

  In addition, the horizontal axis of Fig.2 (a)-(c) represents the operating time for 20-30 years, and Fig.2 (a)-(d) has each shown approximate data.

  As shown in FIGS. 2 (a) to 2 (d), it is confirmed that the increase in the number of times the boiler is started and stopped is closely related to the amount of scale adhered in the pipe of the primary superheater bypass system A and the surface roughness of the scale. Furthermore, it has also been found that the cause of the pressure loss in the piping of the primary superheater bypass system A is that the boiler operation of the power plant has changed.

  As described above, the increase in the outlet pressure of the primary superheater 13 of the constant pressure once-through boiler is caused by the scale adhesion in the register tube 22 in the primary superheater bypass system A. The increase in fluid pressure loss due to the scale adhesion in the register tube 22 It was found that the outlet pressure of the primary superheater 13 increased, and further, it was found that the surface roughness of the scale in the register tube 22 was one of the causes of pressure loss.

  As can be seen from the present invention, for example, when the inner diameter of the register tube 22 is 24 mm, an average surface roughness of 25 μm occurs when a uniform thickness scale adheres to the tube with a thickness of 1 mm and due to the scale adhesion. Pressure loss is almost the same.

  If the pressure loss in the register tube 22 can be specified based on the above knowledge, it can be replaced only. However, in the primary superheater bypass system A, there is a primary superheater bypass valve 23 in addition to the resistor tube 22 as a cause of the pressure loss increase. It is conceivable that the pressure loss increases due to damage to the primary superheater bypass valve 23.

  Therefore, in order to detect an increase in pressure loss in the primary superheater bypass valve 23, the primary superheater bypass valve inlet pressure gauge 36 newly provided in the present invention and the pressure gauge 37 at the outlet of the primary superheater bypass valve 23 are provided. (The pressure gauge 37 is provided in the flash tank 26, and it is possible to detect the pressure loss of the flash tank 26 so that the outlet pressure of the primary superheater bypass valve 23 is known). . Of course, a pressure gauge (not shown) is newly provided on the outlet side of the primary superheater bypass valve 23 separately from the pressure gauge 37 provided in the flash tank, and the differential pressure between the pressure gauge 36 and the primary superheater bypass valve inlet pressure gauge 36 is calculated. You may do it.

  In the present invention, as shown in FIG. 1, the pressure at the inlet of the primary superheater bypass valve 23 is measured with a pressure gauge 36 to identify whether the pressure increase factor site is the register tube 22 or the bypass valve 23. In addition, by measuring the flow rate, pressure distribution, and temperature data of the primary superheater bypass system A, the pressure loss value and surface roughness value of the register tube 22 at the specified flow rate are confirmed by calculation processing based on the data shown in FIG. If these are statistically processed over time, the increase characteristic of pressure loss and the increase characteristic of surface roughness can be monitored, and the update time or chemical cleaning time of the register tube 22 can be predicted.

  Such a problem of pressure loss in the superheater bypass system also occurred in the bypass system of the high-order superheater of the secondary superheater 18 or higher, but according to the present invention, the high-order superheater bypass valve of the secondary superheater 18 or higher is used. It is now possible to predict when to clean or replace.

  According to the present invention, in starting up a constant pressure once-through boiler, it is possible to confirm and monitor the increasing tendency of pressure loss due to the time scale adhesion of the primary superheater bypass system and the higher superheater bypass system. In addition, it is possible to predict and monitor and optimize the register tube renewal or chemical cleaning time, thereby reducing maintenance costs.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 (a) shows a steam system diagram of the constant pressure once-through boiler of this embodiment, and FIG. 1 (b) shows a control device for the steam system of FIG. 1 (a). The same members as those in the steam system diagram of the conventional constant pressure once-through boiler shown in FIG.
The equipment of the steam system of the boiler is a deaerator 1, a boiler feed pump 2, a high-pressure heater 9, a boiler body 100 (a economizer 10, a water cooling wall 11, a cage wall 12, a primary superheater 13, and a secondary superheater 18). , A steam turbine (not shown), a condenser (not shown), a flash tank 26, and the like.

  The flow rate of the feed water discharged from the boiler feed pump 2 is adjusted by the feed water flow rate adjustment valve 4 and the pump outlet stop valve 5 on the outlet side, and enters the economizer 10 of the boiler body 100 through the feed water flow meter 8 and the high pressure heater 9. .

  The water supplied to the boiler body 100 receives and evaporates at the economizer 10, the water cooling wall 11, and the cage wall 12 to become steam and becomes a necessary steam temperature through the primary superheater 13 and the secondary superheater 18. Supplied to the steam turbine.

  When the boiler is started, circulation operation to the condenser and deaerator 1 is performed through the flash tank 26 using the start bypass system until the steam condition to be supplied to the steam turbine is satisfied. The startup bypass system is provided with a primary superheater bypass system A and a secondary superheater bypass system B. As an initial step of operation, until the inlet temperature of the primary superheater 13 reaches a specified temperature, the cage wall 12 and Through the primary superheater bypass system having the primary superheater bypass pipe 20 provided between the inlets of the primary superheater 13, the circulation operation of the entire minimum amount of water supply is performed.

  In this initial operation state, the superheater stop valve 15 provided in the primary / secondary superheater communication pipe 14, the superheater pressure reducing valve 17 provided in the superheater stop valve bypass pipe 16, and the secondary superheater bypass pipe are provided. The secondary superheater bypass valve 25 provided at 24 is operated in a fully closed state.

  In the start-up bypass operation, the primary superheater bypass system A is composed of a register tube bypass valve 21, a register tube 22, a primary superheater bypass valve 23 and the like from the flow path before the primary superheater 13 to the flash tank 26, and the cage. The minimum amount of water supplied from the wall 12 passes through the bypass pipe 20, and the entire amount passes through the register tube 22, and the outlet pressure of the primary superheater 13 is controlled and adjusted to be constant by the primary superheater bypass valve 23. Supplied.

  When the minimum amount of water supply passes through the register tube 22, the inlet pressure of the primary superheater bypass valve 23 is lowered by the pressure loss of the register tube 22 to ensure the opening degree of the bypass valve 23.

  When the inlet temperature of the primary superheater 13 reaches a predetermined value, the register tube bypass valve 21 is opened, then the secondary superheater bypass valve 25 is opened, and the operation of the secondary superheater bypass system B is started. And the operation to establish the steam conditions necessary for the turbine is performed.

  There is a primary superheater outlet pressure gauge 35 on the upstream side of the secondary superheater bypass valve 25 provided in the secondary superheater bypass pipe 24 of the secondary superheater bypass system B. A pressure gauge 36 is installed at the inlet of the primary superheater bypass valve 23 of the primary superheater bypass system A. Further, the control device 38 shown in FIG. 1B is provided with a monitoring device 39, and the signals of the pressure gauges 35 and 36 are input to the monitoring device 39 together with the signals of the measuring device described below to monitor the water vapor system. Do.

  The control device 38 includes a feed water flow meter 8, a primary superheater inlet thermometer 33, a primary superheater outlet thermometer 34, a primary superheater outlet pressure gauge 35, a primary superheater bypass valve inlet pressure gauge 36, a flash tank pressure. Various signals such as the opening degree of the total 37 and the primary superheater bypass valve 23 are input, and the pressure loss characteristic of the register tube 22 together with the primary superheater outlet pressure gauge 35 and the primary superheater bypass valve inlet pressure gauge 36, the primary superheater The opening characteristic of the bypass valve 23 is evaluated, and as shown in FIG. 2, the update / chemical cleaning timing and the pressure increase factor part of the register tube 22 and / or the primary superheater bypass valve 23 are predicted and judged, A monitoring device 39 and a CRT 40 to be displayed are installed.

  The register tube 22 of the primary superheater bypass system A is provided in order to prevent pitting caused by high-speed and high-pressure fluid passing through the primary superheater bypass valve 23. If pressure loss increases due to the formation of a scale of the type, a predetermined bypass flow rate can be obtained even if the opening degree is increased in order to distribute a predetermined bypass flow rate from the primary superheater bypass valve 23. Therefore, the opening degree of the primary superheater bypass valve 23 cannot be controlled.

  In general, the opening / closing control of the fluid flow rate adjustment opening / closing valve provided in the pipe through which the fluid flows is performed in an opening / closing control with an upper limit of 70% to 80%. Is a dangerous area with virtually no tolerance for fluid flow control. Therefore, in this embodiment, an increase in pressure loss due to the scale adhesion with time in the primary superheater bypass system A is detected, and when the pressure loss reaches a predetermined value, work such as chemical cleaning excluding the scale in the register tube 22 is performed. And the opening degree of the primary superheater bypass valve 23 is increased so that a predetermined bypass flow rate is obtained.

The detection of the increasing tendency of the pressure loss due to the temporal scale adhesion of the primary superheater bypass system A is performed as follows.
In the first stage of startup of the boiler, water supplied to the boiler flows through the economizer 10, the water cooling wall 11 and the cage wall 12, and returns to the original water supply system through the primary superheater bypass system A. At this time, since the secondary superheater bypass system B is not used, the superheater stop valve 15, the superheater pressure reducing valve 17 and the secondary superheater bypass valve 25 provided on the outlet side of the primary superheater 13 are all closed. As already mentioned.

  At the time of this boiler start-up, while the fluid containing water and steam circulates through the primary superheater bypass system A, the fluid from the cage wall 12 does not flow to the primary superheater 13, so the fluid pressure in the primary superheater 13 Since there is no loss, the pressure value at the primary superheater outlet pressure gauge 35 also detects the pressure at the inlet of the primary superheater 13.

  Therefore, the pressure loss of the primary superheater bypass system A, more precisely the pressure loss up to the upstream side of the primary superheater bypass valve 23, is detected by the primary superheater bypass valve inlet pressure gauge 36 and the primary superheater outlet pressure gauge 35. It can be understood by calculating the differential pressure between the primary superheater outlet pressure gauge 35 and the primary superheater bypass valve inlet pressure gauge 36.

  In addition, as a method of detecting the pressure loss in the pipe of the register tube 22, as described above, in addition to the method of calculating the differential pressure between the primary superheater outlet pressure gauge 35 and the primary superheater bypass valve inlet pressure gauge 36, Instead of the primary superheater outlet pressure gauge 35, a pressure gauge 42 provided at the inlet of the economizer 10 may be used. However, in this case, it is necessary to grasp the predetermined pressure loss in the economizer 10, the water cooling wall 11, and the cage wall 12.

  If the register tube 22 that causes an increase in pressure loss in the primary superheater bypass system A can be identified, it is preferable to replace it. However, the cause of the pressure loss increase in the primary superheater bypass system A is the register tube 22. In addition, there is a primary superheater bypass valve 23. It is conceivable that the pressure loss increases due to damage to the primary superheater bypass valve 23.

  Therefore, in order to detect an increase in pressure loss in the primary superheater bypass valve 23, in this embodiment, a difference between the newly provided primary superheater bypass valve inlet pressure gauge 36 and the downstream flash tank pressure gauge 37 is used. It can be detected by pressure. Of course, a pressure gauge (not shown) is newly provided on the outlet side of the primary superheater bypass valve 23 separately from the flash tank pressure gauge 37, and the pressure difference between the pressure gauge and the primary superheater bypass valve inlet pressure gauge 36 is calculated. good.

  Also, normally, when there is an increase in the differential pressure during the operation of the boiler for several days to several months, each time, the valve is opened as described above, but only the valve is opened and closed. If the pressure difference cannot be eliminated, the resistor tube 22 is pickled or replaced or the primary superheater bypass valve 23 is replaced. Therefore, the degree of the differential pressure for determining the pickling time or replacement time of the register tube 22 or the replacement time of the primary superheater bypass valve 23 is appropriately set for each plant.

  Further, by collecting the data of the differential pressure every day, (1) the differential pressure between the primary superheater outlet pressure gauge 35 and the primary superheater bypass valve inlet pressure gauge 36 and / or (2) the primary superheater bypass valve. Since the degree of increase in the differential pressure between the inlet pressure gauge 36 and the flash tank pressure gauge 37 can be known, the piping of the bypass system A is connected during the next periodic inspection period of the boiler (the periodic inspection is performed for about two weeks). Separate and pickle or replace.

  In addition, the primary superheater bypass system A is originally supplied into the furnace until the steam condition from the furnace outlet (cage wall 12 outlet in FIG. 1) can be supplied to the primary superheater 13. Therefore, there is no need to provide an instrument such as a pressure gauge in the primary superheater bypass system A because the fluid to be circulated is bypassed to the condenser (not shown) side upstream of the primary superheater 13. Therefore, it is not necessary to install the primary superheater bypass valve inlet pressure gauge 36 as in the present embodiment. However, in the present embodiment shown in FIG. 1, the primary superheater is added to the primary superheater bypass system A shown in FIG. By simply installing the bypass valve inlet pressure gauge 36, it is possible to predict that the scale adheres to the inside of the pipe and the surface roughness affects the flow of the pipe fluid as pressure loss. . Therefore, the pressure loss of the inner wall surface of the register tube 22 and / or the primary superheater bypass valve 23 can be accurately measured.

  In addition, at least one of the register tubes 22 is periodically withdrawn, its internal surface roughness is measured, and compared with the previous measurement value of the internal surface roughness, the deviation is a predetermined value (depending on the water used). If the deviation is larger than the predetermined value, replacement or cleaning is performed immediately, and a new or cleaned register tube 22 is replaced. You may return it to its original state.

  Further, based on the deviation between the measured value of the steam pressure of the pressure gauge 35 and the measured value of the steam pressure in the outlet steam pipe 19 of the secondary superheater 18 by the pressure gauge 43, the cleaning time or replacement time of the secondary superheater bypass valve 24 Can be predicted. Similarly, although not shown, a high-order superheater bypass valve (not shown) of the secondary superheater 18 or higher is based on the pressure deviation in the steam piping at the inlet and outlet of the high-order superheater of the secondary superheater 18 or higher. It is also possible to predict the cleaning time or replacement time.

  Since the present invention can predict the reverse and cleaning time of the bypass system at the start of the constant pressure once-through boiler, the boiler operation performance has improved significantly compared to the conventional one, so that it can be applied to the actual machine of the constant pressure once-through boiler to achieve a great effect. Can do.

It is a starting bypass system diagram of the constant pressure once-through boiler of one example of the present invention. The graph (FIG. 2 (a)) which shows the change of the pressure loss of a register tube with respect to the operating history (operating time progress) of the specific boiler of the boiler provided with the starting bypass system of FIG. 1, the operating history (operating time of the specific boiler) Graph showing the average surface roughness of the register tube with respect to the progress) (FIG. 2B), a graph showing the relationship between the number of start / stop of the thermal power generation boiler and the operation history (FIG. 2C), thermal power generation It is a graph (Drawing 2 (d)) for judging abnormalities and normality of a valve from the relation between the actual opening of a starting valve of a boiler, and the calculation opening of a starting valve. It is a systematic diagram which shows the starting bypass apparatus of the conventional constant pressure once-through boiler.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Deaerator 2 Motor drive feed pump 3 Turbine drive feed pump 4 Feed water flow control valve 5 Pump exit stop valve 6 Pump exit stop valve 7 Feed pipe 8 Feed water flow meter 9 High-pressure heater 10 Eco-restrictor 11 Water cooling wall 12 Cage wall 13 Primary superheater 14 Primary / secondary superheater communication pipe 15 Superheater stop valve 16 Superheater stop valve bypass pipe 17 Superheater pressure reducing valve 18 Secondary superheater 19 Outlet steam pipe 20 Primary superheater bypass pipe 21 Register tube bypass valve 22 Register tube 23 Primary superheater bypass valve 24 Secondary superheater bypass pipe 25 Secondary superheater bypass valve 26 Flash tank 27 Secondary superheater warming pipe 28 Secondary superheater warming valve 29 Deaerator supply condensate pipe 30 Deaerator level control valve 31 Condenser supply condensate piping 32 Flash tank level control valve 33 Primary superheater inlet Thermometer 34 Primary superheater outlet thermometer 35 Primary superheater outlet pressure gauge 36 Primary superheater bypass valve inlet pressure gauge 37 Flash tank pressure gauge 38 Control device 39 Monitoring device 40 CRT 42 Eco-restrictor inlet pressure gauge 43 Secondary superheater Outlet pressure gauge 100 Boiler

Claims (3)

It consists of a heat transfer tube panel through which water or steam flows, and a water cooling wall that constitutes the peripheral wall of the boiler furnace,
It consists of a heat transfer tube panel through which water or steam flows, and the flue wall that is the flow path through which the combustion gas generated by the combustion of fuel in the boiler furnace is discharged toward the chimney located downstream of the furnace A gauge wall that constitutes,
Consisting of a heat transfer tube through which superheated steam flows, a primary superheater provided in the flue,
A high-order superheater comprising a heat transfer tube through which superheated steam flows, and including at least a secondary superheater provided in a flue downstream of the primary superheater;
A constant-pressure once-through boiler comprising a heat transfer tube panel through which water flows, and having a economizer provided in a flue downstream of a high-order superheater including the secondary superheater;
A condenser that condenses the steam obtained in the once-through boiler after being used as a load target, and water supplied from the condenser is sequentially supplied to the economizer, water cooling wall, and gauge wall, and then the primary overheating. A primary superheater bypass system that bypasses the condenser inlet to the condenser;
In a constant pressure once-through boiler configuration comprising a high-order superheater bypass system including a secondary superheater bypass system for bypassing superheated steam from the outlet of the primary superheater to the condenser from the inlet of the secondary superheater,
The primary superheater bypass system includes a register tube, its bypass valve and a primary superheater bypass valve from the upstream side, a pressure gauge for measuring the pressure in the pipe of the economizer inlet or the primary superheater outlet, and the register tube A pressure gauge that measures the pressure in the piping between the primary superheater bypass valve, a pressure gauge that measures the pressure in the piping at the outlet of the primary superheater bypass valve, and a higher superheater that is higher than the secondary superheater A constant pressure once-through boiler configuration characterized in that pressure gauges for measuring the pressure in the outlet and inlet pipes are provided. An operation method of the constant pressure once-through boiler configuration according to claim 1,
(A) Deviation of pressure in each pipe measured by the pressure gauge at the economizer inlet or the primary superheater outlet and the pressure gauge between the resistor tube and the primary superheater bypass valve, or (b) the resistor tube and the primary The cleaning time or replacement time of the register tube or the cleaning time of the primary superheater bypass valve based on the deviation of the pressure in each pipe measured by the pressure gauge between the superheater bypass valve and the pressure gauge at the outlet of the primary superheater bypass valve Or the operation method of the constant pressure once-through boiler structure characterized by predicting replacement time. An operation method of the constant pressure once-through boiler configuration according to claim 1,
The higher order higher than the secondary superheater based on the deviation of the pressure in each pipe measured by a pressure gauge that measures the pressure in the pipe through which the steam at the inlet and outlet of the higher superheater higher than the secondary superheater flows. A method for operating a constant pressure once-through boiler configuration, wherein the cleaning time or replacement time of a superheater bypass valve is predicted.

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