JP6091020B2 - Boiler, marine steam turbine propulsion system equipped with the same, ship equipped with the same, and boiler control method - Google Patents

Description

  The present invention relates to a boiler such as a marine boiler, a marine steam turbine propulsion system including the same, a ship including the same, and a boiler control method.

A boiler is used to supply main steam required by a demand destination such as a steam turbine. Generally, a boiler is a burner that burns in a furnace, an evaporator that is heated by combustion gas generated by the burner to generate steam, and steam that is led from the evaporator is superheated by the combustion gas to generate superheated steam. And a superheater to be generated. And according to the improvement of the thermal efficiency of a customer, the main steam made into higher pressure at higher temperature may be requested | required with respect to a boiler. For example, in a marine boiler that supplies main steam to a steam turbine that drives a propulsion propeller of a marine vessel, a marine reheat boiler that includes a reheater is employed (see Patent Document 1). In such a marine reheat boiler, the main steam temperature and the main steam pressure are increased with respect to a conventional marine boiler that does not include a reheater. For example, in a marine reheat boiler, the main steam temperature at the outlet of the superheater increases from 515 ° C. to 560 ° C., and the main steam pressure increases from 6 MPa to 10 MPa as compared to the conventional marine boiler.
On the other hand, the temperature and pressure of the main steam supplied from the boiler are adjusted by detecting the outlet temperature of the superheater and lowering the steam temperature on the way. In the following Patent Document 2, although the configuration of an exhaust heat recovery boiler that does not include a furnace is disclosed, a configuration in which the steam temperature is lowered by a spray desuperheater is disclosed.

JP 2012-167859 A JP 2006-125760 A

As described above, when the main steam generated in the boiler is heated, the metal temperature (metal material temperature) of the heat transfer tube constituting the superheater rises, and a low alloy steel is adopted for the heat transfer tube corresponding to the high temperature. It is necessary to upgrade the metal material. However, when the metal material of the heat transfer tube is upgraded, the cost increases. Therefore, in order to increase the temperature of the superheated steam without upgrading the metal material of the heat transfer tube, the superheater during operation is obtained so that the desired main steam temperature can be obtained while suppressing the metal temperature of the heat transfer tube. It is required to properly manage the metal temperature.
Patent Document 2 discloses that the main steam temperature at the outlet of the superheater is obtained and the flow rate of the spray desuperheater and the feed water flow rate are controlled. However, the main steam temperature at the outlet of the superheater is obtained and feedback control is performed. Therefore, when the boiler load fluctuates, a control delay occurs, and the metal temperature of the superheater may exceed the allowable value.
Further, in Patent Document 1, the heat transfer area of the superheater is increased in order to cope with an increase in the main steam temperature, the superheater is divided into a primary superheater and a secondary superheater, and the primary on the upstream side of the steam flow. By installing a superheater on the furnace side and installing a secondary superheater downstream of the steam flow behind the primary superheater with respect to the furnace, the temperature of the secondary superheater is prevented from rising due to radiation from the furnace. Yes. However, even if such a configuration is adopted, since the superheater is composed of a primary superheater and a secondary superheater to form a long steam path, the main steam temperature at the outlet of the superheater is set as described above. If feedback control is performed, control delay occurs, the temperature and pressure of the main steam become unstable, and in some cases, the metal temperature of the heat transfer tube may exceed the allowable value.

  The present invention was made in view of such circumstances, and a boiler capable of appropriately managing the temperature of the superheater by avoiding as much as possible the control delay of the main steam temperature at the superheater outlet, It is an object of the present invention to provide a marine steam turbine propulsion system provided with the same, a vessel provided with the same, and a boiler control method.

In order to solve the above-described problems, the boiler of the present invention, a marine steam turbine propulsion system provided with the same, a vessel provided with the same, and a boiler control method employ the following means.
That is, a boiler according to the present invention includes a burner that performs combustion in a furnace, an evaporator that generates steam by combustion gas generated by the burner, and the evaporator that is disposed closer to the furnace than the evaporator. A superheater that generates superheated steam by superheating the steam generated in step (2), and steam that is taken out from the steam takeout part at a midpoint of the superheater when returning the steam to the steam return part of the superheater. A steam temperature adjusting means for adjusting the temperature; a control unit for controlling the steam temperature adjusting means; and a first steam temperature downstream of the steam flow from the steam return part of the superheater and at a midway position of the superheater A first temperature sensor for measuring the superheater outlet temperature relationship information defining a relationship between a superheater outlet temperature, which is a steam temperature at the outlet of the superheater, and the first steam temperature. , The superheater outlet temperature related information and Based on the measurement result of the first temperature sensor, the superheater outlet temperature and controls the steam temperature regulating means so that the target value.

The superheater outlet temperature after being superheated by the superheater is controlled so as to be a target value according to a request from a user such as a steam turbine. In order to obtain this target value, steam temperature adjusting means for adjusting the steam temperature in the middle of the superheater is used. That is, after adjusting the temperature of the steam taken out from the steam take-out section in the middle of the superheater, this steam is returned from the steam return section to the superheater so that a desired superheater outlet temperature can be obtained.
In order to set the superheater outlet temperature as the target value, only the superheater outlet temperature is detected and the flow rate of the steam flowing to the slow heater is adjusted, depending on the distance between the superheater outlet and the steam temperature adjusting means. Control delay may occur. Therefore, in the present invention, the superheater outlet temperature relation information that defines the relationship between the superheater outlet temperature and the first steam temperature downstream of the steam return portion and in the middle of the superheater is obtained. Based on the information on the outlet temperature of the heater and the measurement result of the first temperature sensor, the steam temperature adjusting means is controlled so that the outlet temperature of the superheater becomes the target value. Accordingly, the superheater outlet temperature can be set to a desired value without causing a control delay as compared with the case where the temperature is adjusted using only the superheater outlet temperature.
The superheater outlet temperature relation information may be a database in which the relationship between the superheater outlet temperature and the first steam temperature is determined in advance by a test, or the superheater outlet temperature and the first steam temperature obtained in advance by a test. A function derived from the relationship may be used.
In addition, since the temperature is controlled by obtaining the first steam temperature in the middle position of the superheater instead of the superheater outlet, and the temperature is limited on the upstream side of the superheater outlet, the temperature of the superheater is excessive. Can be avoided. Thereby, the metal temperature of a superheater can be controlled below a predetermined value, and the soundness of a superheater can be ensured without using a high-grade material for a superheater.

  The boiler according to the present invention further includes a second temperature sensor that measures the superheater outlet temperature, and the control unit sets the superheater outlet temperature to a target value based on a measurement result of the second temperature sensor. The steam temperature adjusting means is controlled as described above.

  Based on the superheater outlet temperature measured by the second temperature sensor, by controlling the steam temperature adjusting means so that the superheater outlet temperature becomes the target value, the superheater outlet temperature is further finely adjusted and accurately controlled. can do.

Further, in the boiler according to the present invention, the superheater is installed on the upstream side of the steam flow and on the downstream side of the steam flow of the primary superheater, and the primary heater is connected to the furnace. A secondary superheater installed behind the superheater, and the first steam temperature measured by the first temperature sensor is a steam temperature between the primary superheater and the secondary superheater. is, the steam temperature adjusting means is characterized Rukoto provided in the primary superheater.

  By installing a secondary superheater on the rear side of the primary superheater with respect to the furnace, the secondary superheater was made less susceptible to radiation from the furnace than the primary superheater. This reduces the influence of radiation on the secondary superheater, where the steam flow is downstream of the primary superheater and the metal temperature (the temperature of the metal material constituting the heat transfer tube of the superheater) is likely to rise due to the steam. Thus, the metal temperature of the secondary superheater can be made lower than the allowable temperature. In the present invention, since the primary steam temperature between the primary superheater and the secondary superheater is controlled by the control unit, the temperature of the secondary superheater downstream of the primary steam temperature is set. It can be managed appropriately.

  Furthermore, in the boiler according to the present invention, the steam temperature adjusting means includes a heat sink that lowers the temperature of the introduced steam, and a flow adjuster for the heat sink that adjusts the flow rate of the steam flowing through the heat sink. ing.

In order to lower the steam temperature in the middle of the superheater, a slow heatr is used. Then, after the steam temperature is lowered by a desired amount by flowing a predetermined amount of steam to the slow heatr by the flow rate adjusting means for the slow heatr, the desired superheater outlet is returned by returning the steam from the steam return part to the superheater. The temperature will be obtained.
In addition, as a slow heat device, the structure which flows a vapor | steam in the heat exchanger tube provided in the water in the water drum used for an evaporator is used, for example.

  Furthermore, in the boiler according to the present invention, the steam temperature adjusting means includes a steam introduction path that guides the steam from the steam outlet to the slow heat exchanger, and a steam return path that returns the steam from the slow heat generator to the steam return section. And a slow-heater bypass path that connects the steam introduction path and the steam return path so as to bypass the slow-heater, and the flow adjuster for the slow-heater is provided in the slow-heater bypass path And a second flow rate adjusting valve provided on the upstream side of the junction of the steam return path and the slow heat exchanger bypass path.

The steam led from the superheater to the steam introduction path flows to the heat sink and the heat sink bypass path. The steam that has flowed to the heat sink flows through the steam return path after being reduced in temperature by the heat sink. On the other hand, the steam that has flowed to the heat sink bypass path joins with the steam that has been reduced in temperature by the heat sink at the junction of the steam return path without being reduced in temperature by the heat sink.
The flow rate of the steam flowing into the slow heat bypass path is regulated by the first flow rate regulating valve. When the opening degree of the first flow rate adjustment valve is increased, the bypass flow rate that bypasses the heat sink increases, and the decrease in the steam temperature after merging at the merging portion of the steam return portion is suppressed. On the other hand, when the opening degree of the first flow rate adjustment valve is reduced, the bypass flow rate for bypassing the heat sink is reduced, and the temperature drop of the steam temperature after joining at the joining part of the steam return part is increased.
The flow rate flowing through the heat sink to the joining portion of the steam return portion is adjusted by the second flow rate adjusting valve. When the opening degree of the second flow rate adjustment valve is increased, the flow rate passing through the heat sink increases, and the temperature drop of the steam temperature after joining at the joining part of the steam return part is increased. On the other hand, when the opening degree of the second flow rate adjustment valve is reduced, the flow rate passing through the heat sink decreases, and the temperature drop of the steam temperature after joining at the joining part of the steam return part is suppressed.
Thus, by adjusting the opening degree of the first flow rate adjustment valve and the second flow rate adjustment valve, it is possible to control the steam temperature after joining at the joining part of the steam return part.
Further, since the first flow rate adjustment valve is adjustable not in the fixed opening like the fixed orifice but in the opening adjustment, the temperature adjustment range can be expanded. For example, it is possible to cope with an increase in superheated steam temperature due to a change in heat absorption due to aging deterioration of the furnace. That is, even when the second flow rate adjustment valve is fully opened, the steam temperature can be controlled by increasing the opening of the first flow rate adjustment valve. Thereby, the metal temperature of the superheater downstream from the steam return portion can be reliably kept lower than the allowable value.

  Furthermore, in the boiler according to the present invention, the minimum opening of the first flow rate adjusting valve is a predetermined opening larger than zero.

If the opening of the first flow rate adjustment valve is set to 0 and the valve is fully closed, steam will not flow into the slow heat bypass path, and all the steam guided from the steam outlet of the superheater will flow into the heat sink. The steam temperature is excessively lowered by the heater, so that a lot of drain water is generated, and there is a possibility that the drain water flows into the second flow rate adjusting valve and a malfunction occurs. In addition, when a large amount of steam flows into the slow heat generator, a large pressure loss occurs in the slow heat generator, and the steam pressure in the superheater upstream of the steam extraction portion may increase excessively. And the steam pressure of the steam drum on the upstream side of the steam take-out part rises excessively, and there is a risk that the steam will spout from the safety valve provided in the steam drum.
Therefore, in the present invention, by setting the first opening of the first flow rate adjustment valve to a predetermined opening larger than 0, all the steam guided from the steam outlet of the superheater flows into the slow heater. I decided to prevent it. Thereby, while preventing generation | occurrence | production of drain water by the temperature fall of the vapor | steam in a slow heat device, the stable driving | operation is attained by avoiding the raise of the pressure loss in a slow heat device.
In addition, although the minimum opening degree of a 1st flow regulating valve may be a fixed value, it is good also as changeable according to driving | running conditions, such as an integrated driving | running time, considering aged deterioration of a boiler.

  The marine steam turbine propulsion system of the present invention includes a steam turbine that drives a propulsion device that generates thrust in water, and the boiler according to any one of the above that supplies steam to the steam turbine. It is characterized by.

  Since any one of the above boilers is used as steam for driving a steam turbine that drives a propeller such as a propeller, a desired superheater outlet temperature can be obtained, and stable navigation is possible.

  Moreover, the ship of this invention is equipped with said marine steam turbine propulsion system, It is characterized by the above-mentioned.

  Since the marine steam turbine propulsion system is provided, a marine vessel capable of stable navigation can be provided.

In addition, the boiler control method of the present invention includes a combustion gas generation step for generating combustion gas, a steam generation step for generating steam by the generated combustion gas, and superheated steam generated by superheating the generated steam. A superheated steam generation step for generating steam, and a superheated steam slow heat step for removing steam from a midway position of the superheater and returning the steam to the superheater after passing through a slow heat reducer that lowers the temperature of the steam; The flow rate adjusting step for the slow heatr that adjusts the flow rate of the steam flowing to the slow heatr by the flow rate adjusting means for the slow heatr, and the first steam after the superheated steam slowing step and in the middle of the superheater A first steam temperature measuring step for measuring temperature, a superheater outlet temperature relation information defining a relationship between a superheater outlet temperature, which is a steam temperature at the outlet of the superheater, and the first steam temperature, and the first steam. Measurement results in temperature measurement process Based on the bets, and a superheater outlet temperature control process in which the superheater outlet temperature to control the slow heat absorber flow rate adjusting means so that the target value, the superheater is disposed upstream of the vapor stream A primary superheater, and a secondary superheater installed downstream of the primary superheater and installed behind the primary superheater with respect to the furnace, and the superheated steam slowing step The steam is returned to the primary superheater .

  ADVANTAGE OF THE INVENTION According to this invention, the control delay of the main steam temperature of a superheater exit can be avoided, and the temperature of a superheater can be managed appropriately.

1 is a schematic configuration diagram illustrating a marine steam turbine propulsion system according to an embodiment of the present invention. It is the perspective view which showed the partial expansion of the primary superheater shown by FIG. It is the schematic block diagram which showed the principal part around the superheater of FIG. It is the control block diagram which showed the main steam temperature control performed by a control part. It is the figure which showed the metal temperature of the heat exchanger tube of a superheater.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a marine steam turbine propulsion system 1 applied to a marine vessel. A marine steam turbine propulsion system 1 includes a propulsion propeller (propulsion unit) 3 that generates thrust in water, a steam turbine 5 that applies rotational force to the propeller 3, and a boiler that supplies superheated steam that is main steam to the steam turbine 5. 7.

  The steam turbine 5 includes a high-pressure turbine 9, an intermediate-pressure turbine 11, a low-pressure turbine 13, and a reverse turbine 15. The high-pressure turbine 9 and the intermediate-pressure turbine 11 are connected via a common first rotating shaft 17. The low pressure turbine 13 and the reverse turbine 15 are connected via a common second rotating shaft 21. The first rotating shaft 17 and the second rotating shaft 21 are arranged in parallel, and their output destinations are connected by a speed reducer 23. The propeller 3 is connected to the speed reducer 23 via a propeller shaft 25.

The boiler 7 is designed to be compact so that it can be installed in a ship, and is a marine reheat boiler provided with a reheater 57.
The boiler 7 includes a main furnace 27 and a reheating furnace 29. The main furnace 27 includes a hollow furnace 31, a main burner (burner) 33 installed at the top of the furnace 31, a front bank tube 35 through which water flows, an overheater 37, and an evaporator 38. Is provided.

  The wall portion of the furnace 31 is constituted by a water-cooled wall pipe (not shown) through which water flows. The main burner 33 is supplied with fuel from a fuel source (not shown) through a main burner fuel pipe 47. The main burner fuel pipe 47 is provided with a main burner fuel flow rate adjustment valve 49 for adjusting the amount of fuel supplied.

  The evaporator 38 includes a plurality of heat transfer tubes 39 extending in the vertical direction, a water drum 41 that is connected to the lower side of the evaporation tube group 39 and stores water therein, and an evaporation tube group. And a steam drum 43 connected to the upper side of 39.

  The reheating furnace 29 extends in the vertical direction on the downstream side of the evaporation tube group 39 of the main furnace 27 and is configured to serve as a passage for combustion gas generated by the combustion of the main burner 33. A reheating burner 51 is provided at the lower part of the reheating furnace 29. Fuel is supplied to the reheating burner 51 from a fuel source (not shown) through a reheating fuel pipe 53. The reheating fuel pipe 53 is provided with a reheating fuel flow rate adjustment valve 55 for adjusting the amount of fuel supplied. In the upper part of the reheating furnace 29, a reheater 57 having a heat transfer tube through which steam flows is provided.

  The superheater 37 includes a primary superheater 59 and a secondary superheater 61, and is configured in two rows with respect to the combustion gas flow. Each of the primary superheater 59 and the secondary superheater 61 includes a large number of heat transfer tubes 59a and 61a that are bent in an inverted U shape so that the U-turn portion is positioned above. The primary superheater 59 is disposed on the downstream side of the furnace 31 with respect to the front bank tube 35, and is disposed on the upstream side of the furnace 31 with respect to the secondary superheater 61. In the steam flow, a primary superheater 59 and a secondary superheater 61 are connected in series, with the primary superheater 59 on the upstream side and the secondary superheater 61 on the downstream side.

Below the primary superheater 59, a first header 59b and a second header 59c connected to the lower end of the heat transfer tube 59a are provided.
As shown in FIG. 2, the first header 59b and the second header 59c are provided with a plurality of partition plates 59d for partitioning the interior at predetermined intervals, and the headers 59b and 59c are partitioned into a plurality of rooms. . The heat transfer tubes 59a are connected so that steam flows alternately between the room in the first header 59b and the room in the second header 59c. Thereby, the vapor | steam guide | induced in the 1st header 59b flows into the 2nd header 59c via the heat exchanger tube 59a, and after that, it flows through each room | chamber in each header 59b and 59c alternately one after another. .
In this specification, the path | route of the heat exchanger tube which flows a vapor | steam from one header to the other header is called a pass. According to this definition, two paths are shown in FIG. Further, as shown in FIG. 3, the primary superheater 59 is provided with six paths from the first path I to the sixth path VI.

Below the secondary superheater 61, as shown in FIG. 1, the 1st header 61b and the 2nd header 61c connected to the lower end of the heat exchanger tube 61a are provided. Like the first superheater 59 shown in FIG. 2, the secondary superheater 61 is provided with a partition plate 61d (see FIG. 3) in each header 61b, 61c, and a room in the first header 61b. The heat transfer tubes 61a are connected so that steam circulates alternately between the chambers in the second header 61c. As shown in FIG. 3, the secondary superheater 61 is provided with four paths from the seventh path VII to the tenth path X.
In the present embodiment, the primary superheater 59 has six paths and the secondary superheater 61 has four paths. However, the present invention is not limited to this, and the number of other paths is not limited. May be.

  As shown in FIG. 3, the steam guided from the steam drum 43 to the primary superheater 59 via the steam supply path 44 flows through the primary superheater 59 through six paths. The steam after that is guided to the secondary superheater 61, and after four passes in the secondary superheater 61, is guided to the high-pressure turbine 9 (or the reverse turbine 15) via the superheater outlet pipe 63.

  As shown in FIG. 1, the superheater outlet pipe 63 guides the main steam to the first main steam pipe 65 that guides the main steam to the high-pressure turbine 9 and the reverse turbine 15 at the branch point 64. The second main steam pipe 67 is branched. The first main steam pipe 65 is provided with a first on-off valve 66, and the second main steam pipe 67 is provided with a second on-off valve 68. Main steam is supplied to either the high-pressure turbine 9 or the reverse turbine 15 by selectively opening and closing the first on-off valve 66 and the second on-off valve 68 by a control unit (not shown). Although not shown, a steam control valve for adjusting the steam flow rate is provided between the first on-off valve 66 and the high-pressure turbine 9 and between the second on-off valve 68 and the reverse turbine 15. The output of the steam turbine 5 is adjusted by the control unit.

When the first on-off valve 66 is selected, after the main steam is supplied to the high-pressure turbine 9, the outlet steam of the high-pressure turbine 9 is introduced into the upstream end portion above the reheater 57, and the main burner 33 Reheating is performed by the residual heat amount of the combustion gas generated by the combustion and the combustion gas of the reheat burner 51. The reheat steam reheated by the reheater 57 is introduced into the intermediate pressure turbine 11 from the downstream end portion below the reheater 57. The outlet steam of the intermediate pressure turbine 11 is supplied to the low pressure turbine 13 and is driven to rotate, and then sent to the condenser 69. The water liquefied by the condenser 69 is supplied to the boiler 7.
On the other hand, when the second on-off valve 68 is selected, the main steam is supplied to the reverse turbine 15, and the steam after rotationally driving the reverse turbine 15 is sent to the condenser 69.
Due to the operation of the steam turbine 5, the rotational force is transmitted to the propeller shaft 25 via the speed reducer 23, and the propeller 3 is rotated.

  Next, the steam flow centered on the superheater 37 will be described with reference to FIG. In the figure, the configuration of the main part around the superheater 37 is shown. The primary superheater 59 includes six paths from the first path I to the sixth path VI. The secondary superheater 61 includes four paths from the seventh path VII to the tenth path X.

  Steam in the steam drum 43 of the evaporator 38 (see FIG. 1) is led to the inlet of the first header 59b of the primary superheater 59 through the steam supply path 44. The steam supply path 44 is provided with a flow meter 46 that detects the steam flow rate F. As the flow meter 46, for example, a differential pressure type flow meter is used. The load of the boiler 7 is grasped by the steam flow rate F obtained by the flow meter 46.

  The main steam temperature T2, which is the superheated steam temperature of the secondary superheater 61, is detected by a main steam temperature sensor (second temperature sensor) 70 provided at the outlet of the first header 61b of the secondary superheater 61. The output of the main steam temperature sensor 70 is transmitted to a control unit (not shown). The installation position of the main steam temperature sensor 70 is not the outlet portion of the first header 61b, but may be another position as long as the superheated steam temperature after being heated by the secondary superheater 61 can be detected. For example, you may provide in the superheater exit piping 63. FIG.

  An intermediate steam temperature sensor (first temperature sensor) 72 is provided in the intermediate connection pipe 71 that connects the primary superheater 59 and the secondary superheater 61. The intermediate steam temperature sensor 72 measures the intermediate temperature T1 at the midpoint of the steam flowing through the superheater 37. The output of the intermediate steam temperature sensor 72 is transmitted to a control unit (not shown). In the present embodiment, the intermediate temperature T1 is the outlet temperature of the primary superheater 59, that is, the inlet temperature of the secondary superheater 61.

  The first header 59b after passing through the fourth path IV of the primary superheater 59 is provided with a steam outlet 59e and connected to the upstream end of the steam introduction path 74a of the steam temperature adjustment line (steam temperature adjusting means) 74. Has been. The first header 59b on the upstream side of the fifth path V of the primary superheater 59 is provided with a steam return portion 59f and connected to the downstream end of the steam return path 74b of the steam temperature adjustment line 74. The entire amount of steam is led from the steam outlet 59e to the steam temperature adjustment line 74 from the primary superheater 59, and the whole amount of steam led to the steam temperature adjustment line 74 is returned to the primary superheater 59 from the steam return portion 59f. It is like that.

  The steam temperature adjustment line 74 is provided with a slow heat generator 76 that lowers the steam temperature downstream of the steam introduction path 74a and upstream of the steam return path. The slow heat unit 76 includes a heat transfer tube disposed in the water in the water drum 41. The steam flowing in the heat transfer tube is cooled from the outside of the heat transfer tube by the water in the water drum 41.

  The steam temperature adjustment line 74 is provided with a bypass path (slow heat bypass path) 78 through which steam flows so as to bypass the heat sink 76. The bypass path 78 is provided with a first steam flow rate adjusting valve 80 that adjusts the steam flow rate. The valve opening degree of the first steam flow rate adjusting valve 80 is controlled by a control unit (not shown).

  A steam return path 74b on the downstream side of the slow heat generator 76 is provided with a second steam flow rate adjusting valve 81 for adjusting the steam flow rate on the upstream side of the junction 78a with the bypass path 78. The valve opening degree of the second steam flow rate adjustment valve 81 is controlled by a control unit (not shown).

By controlling the opening degree of the first steam flow rate adjusting valve 80 and the second steam flow rate adjusting valve 81 by the control unit, the ratio of the steam flow rate to flow to the slow heater 76 is determined and guided from the primary superheater 59. The amount of steam cooling is controlled. Specifically, the steam cooling amount increases as the ratio of the steam flow rate flowing to the slow heat generator 76 increases.
As described above, in this embodiment, the steam between the fourth path IV and the fifth path V of the primary superheater 59 is taken out and the steam temperature is adjusted.

  Based on the main steam temperature T2 obtained by the main steam temperature sensor 70, the intermediate steam temperature T1 obtained by the intermediate steam temperature sensor 72, the steam flow rate F obtained by the flow meter 46, etc. Control the main steam temperature. The control unit includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized. The program is preinstalled in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Etc. may be applied. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

Next, the main steam temperature control by the control unit will be described with reference to FIG.
The control unit includes a first control function (superheater outlet temperature related information) R1 related to the main steam temperature T2 and the intermediate steam temperature T1, a second control function R2 related to a preceding signal given to both the steam flow rate adjusting valves 80, 81, A predetermined memory includes a third control function R3 related to an opening degree command given to the first steam flow rate adjustment valve 80 and a fourth control function R4 related to an opening degree command given to the second steam flow rate adjustment valve 81.
Instead of these control functions R1 to R4, a control map including a digitized database may be used.

  The first control function R1 represents the relationship of the expected temperature of the intermediate steam temperature T1 corresponding to the main steam temperature T2. That is, when the boiler 7 is set to a predetermined load, an expected temperature of the intermediate steam temperature T1 necessary for obtaining a desired main steam temperature T2 is obtained in advance from the results of tests and simulations. For example, when the boiler 7 has a rated load, in order to set the target main steam temperature to 560 ° C., the relationship that the predicted temperature of the intermediate steam temperature T1 is 480 ° C. is obtained. Further, the first control function R1 changes the expected temperature of the intermediate steam temperature T1 according to the load of the boiler 7. Specifically, as shown in the figure, when the boiler load is lower than a predetermined value, that is, the steam flow F (STM FLOW (T / H)) obtained by the flow meter 46 is lower than the predetermined value. When the steam flow is low, the expected temperature of the intermediate steam temperature T1 is constant, and when the boiler load is larger than a predetermined value, that is, when the steam flow F obtained by the flow meter 46 is larger than the predetermined value, the steam flow F increases. Accordingly, the predicted temperature of the intermediate steam temperature T1 is reduced. The reason why the predicted temperature of the intermediate steam temperature T1 is lowered when the steam flow rate F is large in this way is that the large steam flow rate F means that the boiler load is large, and the primary superheater 59 and the secondary superheater. This is because the temperature of the vessel 61 is considered to be increasing, so that the proper metal temperature is maintained by lowering the intermediate steam temperature T1.

  The second control function R2 gives a preceding signal to the opening degree commands of both the steam flow rate adjusting valves 80 and 81. For example, as shown in the figure, when the steam flow rate F increases, a large preceding signal is given to speed up the operation of both the steam flow rate adjusting valves 80 and 81 to improve the followability of the steam temperature. Further, the preceding signal is rapidly increased after the steam flow rate F exceeds a predetermined value, so that the initial operation of the control is accelerated and the fluctuation of the steam temperature is suppressed.

  The third control function R3 is a function that gives an opening degree command for the first steam flow rate adjustment valve 80. The first steam flow rate adjusting valve 80 determines the steam flow rate that bypasses the heat sink 76, and more steam bypasses the heat sink 76 (see FIG. 3) as the opening degree increases. This suppresses the temperature drop of the steam. On the contrary, when the opening degree of the first steam flow rate adjusting valve 80 decreases, more steam is guided to the slow heat generator 76, and the temperature drop of the steam increases. Therefore, as shown in the figure, the third control function R3 is such that the opening command value decreases as the given control output value increases (that is, the temperature difference with respect to the target temperature increases toward the high temperature side). It is a descending function. The third control function R3 maintains a predetermined opening of 10% without setting the opening command value to 0% even when the control output value increases. In addition, the minimum opening degree set to 10% can be changed as necessary in consideration of, for example, deterioration of the boiler 7 over time. Further, in the opening degree command value of the first steam flow rate adjusting valve 80, 100% means fully open and 0% means fully closed.

  The fourth control function R4 is a function that gives an opening degree command for the second steam flow rate adjustment valve 81. The second steam flow rate adjusting valve 81 determines the flow rate of steam flowing to the slow heat generator 76 (see FIG. 3). As the opening degree increases, more steam flows through the slow heat generator 76, and the temperature of the steam decreases. Enlarge. On the other hand, when the opening degree of the second steam flow rate adjustment valve 81 decreases, the amount of steam guided to the slow heat generator 76 decreases and the temperature decrease of the steam is suppressed. Therefore, as shown in the figure, the fourth control function R4 is such that the opening command value increases as the given control output value increases (that is, the temperature difference with respect to the target temperature increases toward the high temperature side). It is a function that rises to the right. Further, in the fourth control function R4, when the control output value is 0 (that is, when the target temperature and the current temperature match), the opening degree command is set to 0%, and the steam does not flow to the slow heatr 76. Like that. On the other hand, when the control output value exceeds a predetermined value, the opening degree command becomes 100%. As for the opening degree command value of the second steam flow rate adjustment valve 81, 100% means full open, and 0% means full close, like the first steam flow rate adjustment valve 80.

  The first steam flow rate adjusting valve 80 and the second steam flow rate adjusting valve 81 use valves of the same capacity, and the third control function R3 and the fourth control function R4 are set so that the total opening becomes 100% at each control output value. Is set. Thereby, the steam flow rate returned again after being taken out from the primary superheater 59 by the steam temperature adjustment line 74 (see FIG. 3) becomes constant, and stable control can be realized. However, as shown in the third control function R3, when the control output value is large, the opening command value does not become 0% (the opening command value is constant within 10% of the minimum opening). This is not the case.

  The intermediate steam temperature T1 from the intermediate steam temperature sensor 72 is input to the first comparison calculation unit 85 as the current value PV1. Further, the target value SP <b> 1 given from the first adder 87 is input to the first comparison calculation unit 85. In the first comparison operation unit 85, PID control is performed so that the current value PV1 asymptotically approaches the target value SP1, and a PID control output value is given to the second adder 88. In addition, it is not limited to PID control in the 1st comparison calculating part 85, For example, PI control may be sufficient.

The main steam temperature T2 from the main steam temperature sensor 70 is input to the second comparison calculation unit 86 as the current value PV2. Moreover, the main steam target temperature determined in the range of 550 degreeC-560 degreeC, for example is input into the 2nd comparison calculating part 86 as target value SP2. The second comparison calculation unit 86 performs PID control so that the current value PV2 asymptotically approaches the target value SP2, and a PID control output value is given to the first adder 87. In addition, it is not limited to PID control in the 2nd comparison calculating part 86, For example, PI control may be sufficient.
Further, the first adder 87 receives an expected temperature of the intermediate steam temperature T1, which is an output value from the first control function R1. Accordingly, in the first adder 87, a value corresponding to the deviation of the current value PV2 of the main steam temperature T2 from the main steam target temperature SP2 from the second comparison calculation unit 86 and the main steam given by the first control function R1. The predicted temperature of the intermediate steam temperature T1 corresponding to the target temperature is added, and this added value is set as the target value SP1 of the first comparison calculation unit 85.

  The second adder 88 is given a preceding signal from the second control function R2 in addition to the PID control output value from the first comparison operation unit 85. The output from the second adder 88 as these added values is given as a control output value to each of the third control function R3 and the fourth control function R4, and the opening command value is set to the first steam flow rate adjusting valve 80. And the second steam flow rate adjusting valve 81.

According to this embodiment mentioned above, there exist the following effects.
A first control function R1 defining the relationship between the main steam temperature T2 and the intermediate steam temperature T2 between the primary superheater 59 and the secondary superheater 61 is obtained, and the first control function R1 and the intermediate steam are obtained. Based on the measurement result of the temperature sensor 72, the first steam flow rate adjusting valve 80 and the second steam flow rate adjusting valve 81 are controlled so that the main steam temperature T2 becomes a target value. As a result, the main steam temperature can be set to a desired value without causing a control delay as compared with the temperature adjustment using only the main steam temperature T2 that is the most downstream of the steam flow.

Further, instead of the main steam temperature T2 at the outlet of the secondary superheater 61, the intermediate steam temperature T1 between the primary superheater 59 and the secondary superheater 61 is obtained to control the temperature, and the upstream side of the steam flow Therefore, it is possible to avoid a situation in which the temperatures of the superheaters 59 and 61 become excessively high. Thereby, the metal temperature of the superheaters 59 and 61 can be controlled to a predetermined value or less, and the soundness of the superheaters 59 and 61 can be ensured.
Further, by installing a secondary superheater 61 on the rear side of the primary superheater 59 with respect to the furnace 31, the secondary superheater 61 is less susceptible to radiation from the furnace than the primary superheater 59. did. Thus, the metal flow of the secondary superheater 61 is reduced by reducing the influence of radiation on the secondary superheater 61 in which the steam flow is downstream of the primary superheater 59 and the metal temperature is likely to rise due to the steam. The temperature can be made lower than the allowable temperature.
The metal temperature of such superheaters 59 and 61 will be described with reference to FIG. In the figure, the metal temperatures of the primary superheater 59 and the secondary superheater 61 are shown. In the figure, the horizontal axis indicates the position in the flow direction of the steam flowing through the superheaters 59, 61, and the vertical axis indicates the metal temperature of the heat transfer tubes 59a, 61a of the superheaters 59, 61 and the steam flowing through the superheaters 59, 61. Indicates the temperature. As shown in the figure, the first path I to the sixth path VI are the primary superheater 59, and the seventh path VII to the tenth path X are the secondary superheater 61. The upper line in the graph indicates the metal temperature, and the lower line indicates the steam temperature.
As can be seen from the figure, the metal temperature in the first pass I sharply decreases after increasing on the upstream side, and then increases again. This rapid temperature drop is such that the heat transfer tube 59a has an inverted U-shape (see FIG. 2), is radiated at the position on the furnace 31 side, tends to be relatively hot, and has turned back in a direction away from the furnace 31. This is because the position is less susceptible to radiation and tends to be relatively cold. A similar trend is shown in the second pass II to the sixth pass VI. This is because the primary superheater 59 is disposed closer to the furnace 31 than the secondary superheater 61. Therefore, in the seventh pass VII to the tenth pass X, since it is not easily affected by radiation, a rapid temperature drop in the same pass is not seen, and the metal temperature shows a value close to the steam temperature. .
On the other hand, since the primary superheater 59 is on the upstream side of the steam flow, the steam temperature is sufficiently lower than the metal temperature.
As can be seen from the figure, the steam temperature decreases between the fourth pass IV and the fifth pass V. This is because the steam temperature is lowered by the heat sink 76 (see FIG. 3). As a result, the metal temperature in the fifth pass V is lower than that in the fourth pass IV although the metal temperature on the downstream side of the fourth pass is set to the highest temperature. In this way, by reducing the steam temperature by the slow heater 76 in the middle of the primary superheater 59 that is affected by radiation such as between the fourth pass IV and the fifth pass V. The heat transfer tube 59a can be controlled so as not to exceed the allowable temperature of the material constituting the heat transfer tube 59a.
Since the secondary superheater 61 is not easily affected by radiation, the metal temperature does not increase significantly unlike the fourth pass of the primary superheater 59. Therefore, a metal material similar to that of the heat transfer tube 59a of the primary superheater 59 can be used as the heat transfer tube 61a of the secondary superheater 61, and it is not necessary to use a high-grade material, leading to an increase in cost. Absent.

  In addition to the control based on the intermediate steam temperature T1 obtained by the intermediate steam temperature sensor 72, based on the main steam temperature T2 measured by the main steam temperature sensor 70, the main steam temperature is set to the target value. The control is performed using the two comparison arithmetic unit 86 (see FIG. 4). Thereby, the main steam temperature T2 can be further finely adjusted and accurately controlled.

  In addition, as shown in FIG. 3, instead of providing a fixed orifice in the bypass path 78 to obtain a fixed opening, a first steam flow rate adjusting valve 80 is provided so that the valve opening can be adjusted. For example, it is possible to cope with an increase in superheated steam temperature due to a change in heat absorption due to aging deterioration of the furnace. That is, even if the second steam flow rate adjustment valve 81 has a 100% opening degree, the steam temperature can be controlled by increasing the opening degree of the first steam flow rate adjustment valve 80. Thereby, the metal temperature of the superheaters 59 and 61 on the downstream side of the steam return portion 59f can be reliably kept lower than the allowable value.

  In addition, by setting the minimum opening of the first steam flow control valve 80 to 10%, which is a predetermined opening greater than 0%, all the steam guided from the steam outlet 59e of the primary superheater 59 is loosened. The flow into the heater 76 was prevented. Accordingly, it is possible to prevent the drain water from being generated due to the temperature drop of the steam in the slow heat generator 76 and to avoid the possibility that the drain water flows into the second steam flow rate adjustment valve 81 and causes a malfunction. Further, when a large amount of steam flows into the gradual heater 76, a large pressure loss occurs in the gradual heater 76, and the steam pressure of the primary superheater 59 on the upstream side of the steam extraction portion 59e, and hence the steam pressure of the steam drum 43. As a result, it is possible to avoid the risk that the steam rises excessively and the steam is ejected from the safety valve provided in the steam drum 43, and a stable operation is possible.

  In the above-described embodiment, a marine reheat boiler has been described as an example of the boiler 7. However, the present invention is not limited to this, and is a marine boiler that does not include a reheater or a land boiler that is not limited to marine use. There may be.

DESCRIPTION OF SYMBOLS 1 Steam turbine propulsion system 3 Propeller 5 Steam turbine 7 Boiler 9 High pressure turbine 11 Medium pressure turbine 13 Low pressure turbine 15 Reverse turbine 17 1st rotating shaft 21 2nd rotating shaft 23 Reducer 25 Propeller shaft 27 Main furnace 29 Reheating furnace 31 Furnace 33 Main burner (burner)
35 Front bank tube 37 Superheater 38 Evaporator 39 Evaporation tube group 41 Water drum 43 Steam drum 44 Steam supply path 46 Flow meter 47 Main burner fuel piping 49 Main burner fuel flow control valve 51 Reheating burner 53 Reheating fuel Pipe 55 Reheating fuel flow rate adjustment valve 59 Primary superheater 61 Secondary superheater 63 Superheater outlet pipe 64 Branch point 65 First main steam pipe 70 Main steam temperature sensor (second temperature sensor)
71 Intermediate connection pipe 72 Intermediate steam temperature sensor (first temperature sensor)
74 Steam temperature adjustment line (steam temperature adjustment means)
74a Steam introduction path 74b Steam return path 76 Slow heat generator (steam temperature adjusting means)
78 Bypass path (Slow heatr bypass path)
80 1st steam flow rate adjustment valve (flow rate adjustment means for heat sink)
81 Second steam flow rate adjustment valve (flow rate adjustment means for heat sink)
85 First comparison operation unit 86 Second comparison operation unit 87 First adder 88 Second adder

Claims (7)

A burner that burns in the furnace,
An evaporator that generates steam from the combustion gas generated by the burner;
A superheater that is disposed closer to the furnace than the evaporator and that generates superheated steam by superheating the steam generated by the evaporator;
Steam temperature adjusting means for adjusting the steam temperature when returning the steam taken out from the steam take-out part in the middle of the superheater to the steam return part of the superheater;
A control unit for controlling the steam temperature adjusting means;
A first temperature sensor that measures a first steam temperature downstream of the steam flow from the steam return portion of the superheater and in the middle of the superheater;
With
The steam temperature adjusting means includes a heat sink that lowers the temperature of the introduced steam,
A flow rate adjusting means for a slow heat regulator that adjusts the flow rate of the steam flowing through the slow heat device;
With
The superheater is installed on the upstream side of the steam flow, installed on the downstream side of the steam flow of the primary superheater, and installed behind the primary superheater with respect to the furnace. A secondary superheater,
With
The steam temperature adjusting means is provided in the primary superheater,
The control unit includes superheater outlet temperature relationship information that defines a relationship between a superheater outlet temperature that is a steam temperature at the outlet of the superheater and the first steam temperature, the superheater outlet temperature relationship information, and The boiler, wherein the steam temperature adjusting means is controlled based on a measurement result of the first temperature sensor so that the superheater outlet temperature becomes a target value. The steam temperature adjusting means bypasses the heat sink, a steam introduction path for guiding steam from the steam take-out section to the heat sink, a steam return path for returning steam from the heat sink to the steam return section, and the heat sink A slow-heater bypass path that connects the steam introduction path and the steam return path,
The flow adjuster for the heat sink is a first flow control valve provided on the upstream side of a junction between the first flow control valve provided in the heat sink bypass path and the steam return path and the heat sink bypass path. 2 flow rate adjustment valve,
The boiler according to claim 1, wherein a minimum opening degree of the first flow rate adjusting valve is a predetermined opening degree larger than zero. A second temperature sensor for measuring the superheater outlet temperature;
3. The control unit according to claim 1, wherein the control unit controls the steam temperature adjusting unit based on a measurement result of the second temperature sensor so that the outlet temperature of the superheater becomes a target value. boiler. The first steam temperature measured by the previous SL first temperature sensor may be any of claims 1 to 3, characterized in that it is a steam temperature between the secondary superheater and the primary superheater The boiler described in 1. A steam turbine that drives a thruster that generates thrust in water;
The boiler according to any one of claims 1 to 4 , wherein steam is supplied to the steam turbine;
A marine steam turbine propulsion system comprising: A marine steam turbine propulsion system according to claim 5 is provided. A combustion gas generation process for generating combustion gas;
A steam generation step of generating steam by the generated combustion gas;
A superheated steam generation step of superheating the generated steam and generating superheated steam in a superheater;
A superheated steam slow heating step of removing steam from a midway position of the superheater and returning the steam to the superheater after passing through a slow heat reducer that lowers the temperature of the steam;
A flow rate adjusting step for the slow heat generator that adjusts the flow rate of the steam flowing to the slow heat device by the flow rate adjusting means for the slow heat device;
A first steam temperature measuring step of measuring a first steam temperature at a midpoint of the superheater after passing through the superheated steam slow heating step;
Based on the superheater outlet temperature relationship information that defines the relationship between the superheater outlet temperature, which is the steam temperature of the superheater outlet, and the first steam temperature, and the measurement result of the first steam temperature measurement step, A superheater outlet temperature adjusting step for controlling the flow rate adjusting means for the slow heater so that the superheater outlet temperature becomes a target value;
Equipped with a,
The superheater is installed on the upstream side of the steam flow, installed on the downstream side of the steam flow of the primary superheater, and installed behind the primary superheater with respect to the furnace. A secondary superheater,
With
A boiler control method , wherein steam is returned to the primary superheater in the superheated steam slow heating step .

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