Air amount control device enabling on-site checking of sticking phenomenon, and coal-fired power plant air supply system comprising same

Abstract

The present invention provides an air amount control device enabling the immediate on-site checking of whether a failure has occurred therein. In addition, the immediate determining of a failure for only one air amount control device suspected to have a failure is possible, and an operator may immediately determine a failure in an air amount control device suspected to have a failure, even without an operation room controlling so that signal air is inputted to the air amount control device.

Description

An air volume control device capable of on-site checking of stuck phenomena and an air supply system of a coal-fired power plant including the same

[0001] The present invention relates to an air volume control device for supplying air (e.g., auxiliary air) to a furnace of a boiler for a coal-fired power plant and an air supply system for a coal-fired power plant including the same.

[0002] The furnace of a coal-fired power plant is supplied with pulverized coal and an oxidizer. The oxidizer can be used to ensure complete combustion of the pulverized coal. The oxidizer can be air or pure oxygen. In this specification, the oxidizer and air are collectively referred to as "air," and should be interpreted appropriately according to the context.

[0003] An air volume control device is a device that controls the air volume to ensure that an appropriate amount of air is supplied. The amount of air supplied is controlled using an air volume control device.

[0004] The air volume control device consists of a cylinder, a positioner, and other components. The end of the cylinder rod is connected to an air control plate. The positioner connected to the cylinder operates the cylinder in response to a controlled signal, thereby variably adjusting the linear movement of the cylinder rod. The linear movement of the cylinder rod controls the opening of the air control plate (not shown).

[0005] Because the air volume control device is installed on the outer wall of the furnace, it is easily exposed to foreign substances such as high temperatures, ash, moisture, and dust. This can cause the air volume control device to malfunction.

[0006] To detect a malfunction in an air volume control device, an input signal is input from the operator's cabin to the air volume control device, causing the cylinder to operate. The operator measures the linear travel distance of the cylinder rod in response to the input signal to determine if there is a malfunction. However, in the air supply system of a thermal power plant, a single input signal controls multiple air volume control devices. Therefore, to detect a malfunction in a single air volume control device, all of the devices must be controlled according to the input signal.

[0007] For the reasons described above, detecting a malfunction in an air volume control device requires inputting a signal air stream from the driver's cabin, making on-site inspection impossible. Furthermore, since a single signal air stream is supplied to multiple air volume control devices, determining a malfunction requires supplying signal air to not only the suspected malfunctioning air volume control device but also other connected air volume control devices, making it inefficient.

[0008] In addition, since it is impossible to determine the failure of the air volume control device from the driver's cabin, the operator must periodically check the condition of the air volume control device, but it is difficult for the operator to check all of the air volume control devices in more than 100 locations.

[0009] The purpose of the present invention is to provide an air volume control device that can immediately check for failure on site.

[0010] The purpose of the present invention is to provide an air volume control device capable of immediately determining a failure of only one air volume control device suspected of failure.

[0011] The purpose of the present invention is to provide an air volume control device that allows an operator to immediately determine the failure of an air volume control device suspected of being defective, even without controlling the signal air for inspection to be input to the air volume control device from the operation room.

[0012] The purpose of the present invention is to provide an air volume control device in which a feedback spring is protected by a covering tube to prevent foreign substances such as dust from entering the interior of the air volume control device, while allowing immediate on-site confirmation of failure.

[0013] The purpose of the present invention is to provide an air supply system for a coal-fired power plant that can monitor from a driver's cabin and immediately determine which air volume control device needs to be inspected in order to check for malfunctions in air volume control devices installed in multiple locations.

[0014] The present invention provides an air supply system for a coal-fired power plant that can solve the problem that, in the environment of a coal-fired power plant, an air volume control device is exposed to foreign substances such as high temperature, ash, moisture, and dust because it is installed on the outer wall of the furnace, and the cylinder rod of the air volume control device is stuck and does not move, and the existing method of determining and inspecting a failure is ineffective, and therefore, it is practically impossible for a worker to check the stuck state of more than 100 air volume control devices, and thus a problem of a broken air volume control device being left unattended.

[0015] The present invention provides an air volume control device. In an air volume control device including a cylinder and a positioner according to an embodiment, the cylinder includes a housing forming a cylinder chamber; a piston dividing the cylinder chamber into a first cylinder chamber and a second cylinder chamber and reciprocating within the cylinder chamber; and a cylinder rod coupled to the piston, wherein the positioner generates movement of the cylinder rod in proportion to an input signal, and includes a first cylinder chamber communication port communicating with the first cylinder chamber; and a second cylinder chamber communication port communicating with the second cylinder chamber, and includes a first three-way valve provided in a path connecting the first cylinder chamber communication port and the first cylinder chamber, one side of which is open to the atmosphere; and a second three-way valve provided in a path connecting the second cylinder chamber communication port and the second cylinder chamber, one side of which is open to the atmosphere.

[0016] In an embodiment, the positioner comprises: a signal air input port which is a path through which signal air is introduced as the input signal; a signal pressure chamber which is connected to the signal air input port and includes a first diaphragm which is displaced by the signal air; a nozzle whose back pressure changes by the displacement of the first diaphragm; a pressure air supply port which is a path through which pressure air is introduced; a first communication passage, a second communication passage, and a third communication passage having an orifice which communicate with the pressure air supply port; a spool valve which includes a first spool which opens and closes the first cylinder room communication port, and a second spool which opens and closes the second cylinder room communication port, and which changes the path through which the pressure air moves to either the first cylinder room communication port or the second cylinder room communication port by a change in the back pressure of the nozzle; a supply chamber which is connected to the first communication passage and is closed by the first spool and the second spool; A first supply pressure chamber in communication with the second communication passage and in which a third diaphragm connected to one end of the spool valve is located; a second supply pressure chamber in communication with the third communication passage and in which a fourth diaphragm connected to the other end of the spool valve is located; and a feedback spring having one end connected to the first diaphragm and the other end connected to the cylinder rod may be included.

[0017] In an embodiment, the positioner may further include a covering tube that surrounds the feedback spring and protects the feedback spring from the outside.

[0018] The present invention provides an air supply system for a coal-fired power plant. According to an embodiment, the air supply system for a coal-fired power plant includes a plurality of air volume control devices that share an input signal from a single signal air supply source and share a supply of pressurized air from a single pressure air supply source; and a control unit that controls the air pressure of the signal air and the pressurized air.

[0019] The present invention provides an air supply system for a coal-fired power plant. According to one embodiment, the air supply system for a coal-fired power plant includes an air volume control device that receives signal air from a signal air supply source and receives pressurized air from a pressurized air supply source according to an input signal, wherein the air volume control device includes a cylinder and a positioner, wherein the cylinder includes a housing forming a cylinder chamber; a piston that divides the cylinder chamber into a first cylinder chamber and a second cylinder chamber and reciprocates within the cylinder chamber; and a cylinder rod coupled to the piston, wherein the positioner generates a displacement of the cylinder rod in proportion to an input signal, which is an electrical signal in a range of a first value and a second value, and the air supply system further includes a displacement measuring device configured to generate an electrical signal according to the displacement of the cylinder rod and output the generated electrical signal as a feedback signal; and a display unit that visually displays the feedback signal of the displacement measuring device.

[0020] In an embodiment, the input signal and the feedback signal may be current values ​​in the range of 4 mA to 20 mA.

[0021] In an embodiment, the electrical signal applied as the input signal may be converted into signal air, which is air pressure, and applied to the positioner.

[0022] In an embodiment, the display unit may be placed in the driver's cab.

[0023] In an embodiment, in the air supply system, the air volume control devices are installed in multiple locations, and the air volume control devices are provided in a plurality of groups, with multiple groups forming a group, and one input signal is applied to each group to be configured to interwork with each other, and the displacement measuring device is provided for each air volume control device, and the display unit can display the input signal applied to each group and the feedback signal output from each of the displacement measuring devices provided for each air volume control device.

[0024] In an embodiment, if the input signal and the feedback signal are different beyond the error range, an alarm may be displayed on the display unit.

[0025] According to one embodiment of the present invention, the air volume control device can be immediately checked for malfunction on site.

[0026] According to an air volume control device according to one embodiment of the present invention, it is possible to immediately determine whether a single air volume control device suspected of being defective is defective.

[0027] An air volume control device according to one embodiment of the present invention allows an operator to immediately determine a malfunction of an air volume control device suspected of malfunctioning, even if the control room does not control the signal air for inspection to be input to the air volume control device.

[0028] According to an air supply system of a coal-fired power plant according to one embodiment of the present invention, in checking for malfunctions in air volume control devices installed in multiple locations, it is economical because it is possible to monitor from the driver's cabin and immediately determine which air volume control device requires inspection.

[0029] According to an air supply system of a coal-fired power plant according to one embodiment of the present invention, inspection of an air volume control device can be performed effectively, so that the problem of a malfunctioning air volume control device being left unattended is reduced, thereby enabling stable operation of a boiler.

[0030] According to an air supply system of a coal-fired power plant according to one embodiment of the present invention, even if the control room does not control the signal air for inspection to be input to the air volume control device, the operator can immediately determine the failure of the air volume control device suspected of being defective.

[0031] The effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by those skilled in the art to which the present invention pertains from this specification and the attached drawings.

[0032] Figure 1 is a schematic diagram showing a thermal power generation system according to one embodiment.

[0033] Figure 2 is a plan view showing a wind box (50) installed in a furnace (20) according to one embodiment.

[0034] Figure 3 is a schematic drawing of an air supply system according to one embodiment.

[0035] Figure 4 is a plan view of an air volume control device (100) according to one embodiment of the present invention.

[0036] Figure 5 is a front view of an air volume control device (100) according to one embodiment of the present invention.

[0037] FIG. 6 is a drawing explaining the structure of an air volume control device (100) according to one embodiment of the present invention.

[0038] Figure 7 is a first usage state diagram of an air volume control device (100) according to one embodiment of the present invention.

[0039] Figure 8 is a second usage state diagram of an air volume control device (100) according to one embodiment of the present invention.

[0040] Figures 9 and 10 are operation status diagrams during field inspection of an air volume control device (100) according to one embodiment of the present invention.

[0041] Figure 11 is a schematic diagram of an air volume control device (100) according to one embodiment of the present invention.

[0042] Figures 12 and 13 are front and plan views showing an air volume control device (100) provided with a distance change measuring device (600) for a fault monitoring system.

[0043] Figure 14 illustrates an air supply system according to an embodiment of the present invention.

[0044] Figure 15 is a screen configuration of a display unit (810) according to an embodiment of the present invention.

[0045] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the attached drawings. The configuration of the device and the control method described below are only intended to illustrate embodiments of the present disclosure and are not intended to limit the scope of the present disclosure. Reference numerals used throughout the specification represent identical components.

[0046] Certain terms used in this specification are for convenience of explanation only and are not intended to limit the illustrated embodiments.

[0047] For example, expressions such as "same" and "same as" not only indicate a strictly identical state, but also indicate a state in which there is a difference in tolerance, or the degree to which the same function is obtained.

[0048] In this specification, when a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components in between. Conversely, when this specification refers to a component as being "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0049] In this specification, it should be understood that terms such as “include” or “have” are intended to specify only the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0050] For example, expressions indicating relative or absolute arrangements such as “in which direction,” “along which direction,” “parallel,” “perpendicular,” “centered,” “concentric,” or “coaxial” not only strictly indicate such arrangements, but also indicate a state of relative displacement with an angle or distance that allows for tolerance, or the degree to which the same function is obtained.

[0051] The use of terms such as "first," "second," and "third" before the components mentioned below is intended solely to avoid confusion regarding the components they refer to, and has no bearing on the order, importance, or dominant-subordinate relationship between the components. For example, an invention can be implemented that includes only a second component without a first component.

[0052] As used herein, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0053] Also, in this specification, the term 'and / or' includes a combination of multiple listed items or any item among multiple listed items. In this specification, 'A or B' can include 'A', 'B', or 'both A and B'.

[0054] Figure 1 is a schematic diagram illustrating a thermal power plant system according to one embodiment. The thermal power plant system will be described with reference to Figure 1.

[0055] The thermal power generation system produces electricity using steam generated in a boiler (10).

[0056] The furnace (20) is a space where a flame (F) is formed. Fuel and an oxidizer can be supplied to the furnace (20) to form the flame (F). The fuel can be coal. The coal can be pulverized coal. An oxidizer can be additionally supplied to aid combustion of the coal. The oxidizer can be air. The oxidizer can be pure oxygen. In this specification, the oxidizer and air are collectively referred to as "air," and the word "air" should be appropriately interpreted depending on the context.

[0057] The fuel supply unit (30) is configured to supply fuel to the furnace (20). The fuel of the fuel supply unit (30) is supplied to the furnace (20) through the fuel nozzle (32). The fuel supply unit (30) and the fuel nozzle (32) are connected by a fuel supply pipe (31). The fuel supply pipe (31) is a pipe connecting the fuel supply unit (30) and the fuel nozzle (32). The fuel supply pipe (31) may be composed of a plurality of pipes. Each fuel supply pipe (31) may be connected to each fuel nozzle (32). The fuel supply pipe (31) forms a path from the fuel supply unit (30) to the fuel nozzle (32). For convenience of explanation, the drawing represents a first fuel supply pipe (31a), a second fuel supply pipe (31b), a third fuel supply pipe (31c), and a fourth fuel supply pipe (31d). The fuel supply pipe (31) can be appropriately installed at the required location.

[0058] The air supply unit (40) is configured to supply air to the furnace (20). Air is supplied to the furnace (20) through the air nozzle (42). The air supply pipe (41) forms a path from the air supply unit (40) to the air nozzle (42). The air supply pipe (41) is a pipe connecting the air supply unit (40) and the air nozzle (42). The air supply pipe (41) may be composed of a plurality of pipes. Each air supply pipe (41) may be connected to each air nozzle (42). In the drawing, a first air supply pipe (41a), a second air supply pipe (41b), a third air supply pipe (41c), and a fourth air supply pipe (41d) are represented. The air supply pipe (41) may be appropriately provided at necessary locations. A supply amount control device (100) is installed in the air supply pipe (41). The air volume control device (100) adjusts the opening amount of the air supply pipe (41). The supply volume control device (100) will be described in detail later.

[0059] The fuel nozzle (32) and the air nozzle (42) may be provided in the form of a windbox. FIG. 1 illustrates two windboxes (50). Referring further to FIG. 2, the windboxes (50) are provided at each corner of the furnace (20). The windboxes (50a, 50b, 50c, 50d) at each corner may be configured in the form of an assembly separated into upper, middle, and lower parts. Each assembly may include a plurality of fuel nozzles (32) and a plurality of air nozzles (42).

[0060] In the embodiment, a flame (F) in the furnace (20) heats water in the superheater (51) to generate saturated steam. The steam from the superheater (51) is provided to a high-pressure turbine (61).

[0061] Steam used in the high-pressure turbine (61) is recovered and reheated in the reheater (52). The configuration and number of superheaters (51) and reheaters (52) are not specific and may be modified according to the configuration of a general thermal power generation system.

[0062] In the embodiment, steam supplied from the reheater (52) is transmitted to the medium-pressure turbine (62) and each low-pressure turbine (63) used. The generator (70) produces electricity through these.

[0063] In the embodiment, the steam used in the low-pressure turbine (63) is finally condensed in the condenser (80). The condensate is supplied to the economizer (53) of the boiler (10). The economizer (53) is connected to the superheater (51).

[0064] The flue gas treatment device (90) removes harmful substances from the flue gas discharged from the boiler (10). The chimney (95) discharges the flue gas from which the harmful substances have been removed to the outside.

[0065] Fig. 3 is a schematic diagram illustrating an air supply system according to one embodiment. The air supply system will be described with reference to Fig. 3.

[0066] The air supply system (1000) is a system for supplying air to the furnace (20). It is a system until air is supplied from the air supply unit (40) to the air nozzle (42). An air volume control device (100) is installed in the air supply pipe (41). The air volume control device (100) controls the air supply amount of each air nozzle (42). In the embodiment, four air volume control devices (100) are configured to be interlocked with each other. The interlocking points of the air volume control devices (100) can be appropriately adjusted according to the design, but for equipment efficiency, a plurality of air volume control devices (100) are operated in conjunction with a single signal.

[0067] In the embodiment shown in the drawing, each of the air volume control devices (100) connected to the 1-1 air nozzle (42aa), the 1-2 air nozzle (42ab), the 1-3 air nozzle (42ac), and the 1-4 air nozzle (42ad) shares one signal air. The signal air is an embodiment of an input signal for controlling the air volume control device (100). The 1-1 signal air pipe (211a), the 1-2 signal air pipe (212a), the 1-3 signal air pipe (213a), and the 1-4 signal air pipe (214a), which are branched from one signal air supply source (210a), are connected to each of the air volume control devices (100). In addition, each of the air volume control devices (100) connected to the first-first air nozzle (42aa), the first-second air nozzle (42ab), the first-third air nozzle (42ac), and the first-fourth air nozzle (42ad) share a single pressure air. The first pressure air pipe (221a), the second pressure air pipe (222a), the first-third pressure air pipe (223a), and the first-fourth pressure air pipe (224a), which are branched from a single pressure air supply source (220a), are connected to each of the air volume control devices (100).

[0068] In addition, in the expressed embodiment, each of the air volume control devices (100) connected to the 2-1 air nozzle (42ba), the 2-2 air nozzle (42bb), the 2-3 air nozzle (42bc), and the 2-4 air nozzle (42bd) shares one signal air. The 2-1 signal air pipe (211b), the 2-2 signal air pipe (212b), the 2-3 signal air pipe (213b), and the 2-4 signal air pipe (214b), which are branched from one signal air supply source (210b), are connected to each of the air volume control devices (100). In addition, each of the air volume control devices (100) connected to the 2-1 air nozzle (42ba), the 2-2 air nozzle (42bb), the 2-3 air nozzle (42bc), and the 2-4 air nozzle (42bd) shares a single pressure air (220b). The 2-1 pressure air pipe (221b), the 2-2 pressure air pipe (222b), the 2-3 pressure air pipe (223b), and the 2-4 pressure air pipe (224b), which are branched from a single pressure air supply source (220b), are connected to each of the air volume control devices (100).

[0069] Adequate air supply is important for stability within the furnace (20). For example, proper distribution and supply of air during fuel ignition and at low load are important for stability within the furnace (20). In addition, proper air supply is important for achieving optimal combustion across full loads. Furthermore, the distribution of primary and secondary air has a significant impact on the formation of nitrogen oxides. Generally, reducing the amount of air after the fuel nozzle, combined with the increased amount of air above the fuel nozzle, reduces the formation of nitrogen oxides. This principle is to suppress the combustion rate before the heat is transferred to the water wall before the peak temperature is reached. Once the peak temperature is reached, the formation of NOx is reduced compared to when it is not restricted. The distribution of secondary air also affects the diffusion of pollutants.

[0070] The optimal air distribution ratio is basically determined by the combustion characteristics of the fuel, and is also affected by the mixing combustion rate and the flame shape within the furnace. The air supply system (1000) modulates the air volume control device (100) to position the differential pressure between the set wind box (50) and the furnace (20). The fuel supply control device (not shown) and the air volume control device (100) must be closed before starting, and open after starting to modulate in proportion to the combustion rate.

[0071] Fig. 4 is a plan view of an air volume control device (100) according to an embodiment of the present invention. Fig. 5 is a front view of an air volume control device (100) according to an embodiment of the present invention. The exterior of the air volume control device (100) according to an embodiment will be described with reference to Figs. 4 and 5.

[0072] An air volume control device (100) according to an embodiment of the present invention includes a positioner (300) and a cylinder (400). The cylinder (400) is driven by the control of the positioner (300) of the air volume control device (100) to adjust the opening amount of an air control plate (not shown) connected to a cylinder rod (410).

[0073] The positioner (300) may include a first pressure gauge (311) and a second pressure gauge (321). The first pressure gauge (311) is a pressure gauge for measuring the pressure of signal air supplied from a signal air supply source. The second pressure gauge (321) is a pressure gauge for measuring the pressure of pressurized air supplied from a pressurized air supply source.

[0074] The positioner (300) may include a feedback unit (390). The feedback unit (390) is connected to the cylinder rod (410) through a feedback connection unit (391). One end of the feedback connection unit (391) is connected to the feedback unit (390), and the other end is connected to the cylinder rod (410). When the cylinder (400) is driven, the linear movement of the cylinder rod (410) is stopped at a point where the pulling force of the feedback spring (see FIG. 6) installed inside the feedback unit (390) and the force generated by the signal air are balanced.

[0075] The feedback section (390) can be protected by a feedback section covering tube (392). The feedback section covering tube (392) is a corrugated tube made of heat-resistant rubber material. The feedback section covering tube (392) surrounds the feedback section (390). Here, the heat-resistant rubber material includes a fluorine rubber material and a silicone rubber material.

[0076] The cylinder rod (410) can be protected by a shaft cladding tube (412). The shaft cladding tube (412) surrounds the cylinder rod (410). The cylinder rod cladding tube (412) is a corrugated tube made of heat-resistant rubber.

[0077] The feedback control unit cladding (392) and the cylinder rod cladding (412) prevent foreign substances from entering the cylinder (400) or the positioner (300) when the feedback unit (390) and the cylinder rod (410) move linearly and return to their original state.

[0078] The ruler (395) is a configuration in which graduations are marked to measure the linear movement distance of the cylinder rod (410) and the feedback unit (390). The indicator (396) moves relative to the ruler (395). The indicator (396) is connected to the feedback connection unit (391). The indicator (396) moves according to the movement of the feedback connection unit (391). Since the feedback connection unit (391) connects the feedback unit (390) and the cylinder rod (410), the indicator (911) moves according to the linear movement of the cylinder rod (410). The opening amount may be indicated in % units on the ruler (395).

[0079] The positioner (300) is provided with a signal air input port (312). The signal air input port (312) is connected to a signal air supply pipe (see FIG. 3). Signal air enters the interior of the positioner (300) through the signal air input port (312). The positioner (300) receives signal air through the signal air input port (312).

[0080] The positioner (300) is provided with a pressure air supply port (322). The pressure air supply port (322) is connected to a pressure air supply pipe (see FIG. 3). Pressure air enters the interior of the positioner (300) through the pressure air supply port (322). The positioner (300) receives pressure air through the pressure air supply port (322).

[0081] The first pipe (341) connects the first cylinder room communication port (361, see FIG. 6) of the positioner (300) and the first cylinder room (421, see FIG. 6) of the cylinder (400). A first three-way valve (510) is installed in the first pipe (341). The point indicated by the chain line is a position that can be adjusted by the operator when checking the air volume control device (100) using the first three-way valve (510).

[0082] The second pipe (342) connects the second cylinder room communication port (362, see FIG. 6) of the positioner (300) and the second cylinder room (422, see FIG. 6) of the cylinder (400). A second three-way valve (520) is installed in the second pipe (342). The point indicated by the chain line is a position that can be adjusted by the operator when checking the air volume control device (100) using the second three-way valve (520).

[0083] Fig. 6 is a drawing illustrating the structure of an air volume control device (100) according to an embodiment of the present invention. The structure of the air volume control device (100) according to the embodiment will be described with reference to Fig. 6.

[0084] A positioner (300) of one embodiment is described.

[0085] A flow path is provided inside the positioner (300). A spool valve (350) is located inside the positioner (300). The spool valve (350) controls the flow path. The spool valve (350) has a first spool (351) and a second spool (352) positioned with a first neck (355a) therebetween. The first neck (355a) has a smaller diameter than the first spool (351) and the second spool (352). A second neck (355b) is located on the opposite side of the first neck (355a) with respect to the first spool (351). A third neck (355c) is located on the opposite side of the first neck (355a) with respect to the second spool (352). A third diaphragm (333) and a fourth diaphragm (334) are fixed to each end of the spool valve (350). The third diaphragm (333) is fixed to the end of the second neck (355b). The fourth diaphragm (334) is fixed to the end of the third neck (355c).

[0086] The positioner (300) is provided with a signal air input port (312) and a pressure air supply port (322).

[0087] The signal air input port (312) is connected to the signal air supply source (210a). The signal air input port (312) is connected to the signal air supply source (210a) through a signal air supply pipe (211a). The signal air transmitted through the signal air supply source (210a) is supplied to the interior of the positioner (300) through the signal air input port (312).

[0088] The signal air introduced through the signal air input port (312) is introduced into the signal pressure chamber (313). The signal pressure chamber (313) is a space closed by the first diaphragm (331) and the second diaphragm (332). The cylinder rod (410) moves in proportion to the air pressure of the signal air input into the signal pressure chamber (313).

[0089] The connecting member (393) is connected to one end of the feedback member (390). The connecting member (393) is coupled to the first diaphragm (331) and the second diaphragm (332). The feedback member (390) according to the embodiment is a coil spring. Hereinafter, the feedback member (390) is referred to as a feedback spring (320). The force resulting from the movement of the connecting member (393) is transmitted to the feedback spring (320). The force of the feedback spring (320) is transmitted to the connecting member (393).

[0090] When the interior of the signal pressure chamber (313) is filled with the pressure of the signal air, displacement occurs in the first diaphragm (331) and / or the second diaphragm (332). Accordingly, displacement also occurs in the connecting member (393).

[0091] The pressure air supply port (322) is connected to the pressure air supply source (220a). The pressure air supply port (322) is connected to the pressure air supply source (220a) through a pressure air supply pipe (221a). Pressure air delivered from the pressure air supply source (220a) through the pressure air supply port (322) is supplied to the interior of the positioner (300).

[0092] The flow path connected to the pressure air supply port (322) branches into a first communication path (323a), a second communication path (323b), and a third communication path (323c). That is, the pressure air introduced through the pressure air supply port (322) is supplied by branching into the first communication path (323a), the second communication path (323b), and the third communication path (323c).

[0093] The first communication passage (323a) communicates with the supply room (324) which is blocked by the first spool (351) and the second spool (352).

[0094] The second communication passage (323b) communicates with the third diaphragm chamber (325a) which is closed by the third diaphragm (333).

[0095] The third communication passage (323c) communicates with the fourth diaphragm chamber (325b) which is closed by the fourth diaphragm (334). An orifice (323ca) is provided in the third communication passage (323c).

[0096] The supply pressure chamber (325) is a concept that includes a third diaphragm chamber (325a) and a fourth diaphragm chamber (325b). The third diaphragm chamber (325a) may be referred to as a first supply pressure chamber. The fourth diaphragm chamber (325b) may be referred to as a second supply pressure chamber.

[0097] The first cylinder communication port (361) is opened and closed by the first spool (351). When the spool valve (350) moves in the A direction and the first spool (351) opens the first cylinder communication port (361), the first communication path (323a) and the first cylinder communication port (361) are connected.

[0098] The second cylinder communication port (362) is opened and closed by the second spool (352). When the spool valve (350) moves in the B direction and the second spool (352) opens the second cylinder communication port (362), the first communication path (323a) and the second cylinder communication port (362) are connected.

[0099] The nozzle (370) is connected to the fourth diaphragm (334). The nozzle (370) is connected to the spool valve (350). The nozzle (370) is coupled to the spool valve (350) and / or the fourth diaphragm (334). This coupling includes both direct coupling and indirect coupling. The spool valve (350) can move dependently upon the movement of the nozzle (370). The nozzle (370) can move dependently upon the movement of the spool valve (350).

[0100] The nozzle (370) may face the connecting member (393). The nozzle (370) penetrates the wall (325ba) forming the fourth diaphragm chamber (325b). A seal may be provided at the interface between the wall (325ba) and the nozzle (370). The nozzle (370) may slide along the wall (325ba).

[0101] The first exhaust chamber (381) is formed in the space between the first diaphragm (331) and the nozzle (370). The first exhaust chamber (381) communicates with the first exhaust port (381a). The first exhaust chamber (381) communicates with the atmosphere through the first exhaust port (381a). The first exhaust chamber (381) and the fourth diaphragm chamber (325b) communicate with each other through the nozzle (370). The pressure fluid supplied to the fourth diaphragm chamber (325b) is introduced into the first exhaust chamber (381) through the nozzle (370). The pressure fluid introduced into the first exhaust chamber (381) is discharged to the outside through the first exhaust port (381a).

[0102] The second exhaust chamber (382) is formed in the space between the third diaphragm (333) and the first spool (351). The second exhaust chamber (382) communicates with the second exhaust port (382a). The second exhaust chamber (382) communicates with the atmosphere through the second exhaust port (382a).

[0103] The third exhaust chamber (383) is formed in the space between the fourth diaphragm (334) and the second spool (352). The third exhaust chamber (383) communicates with the third exhaust port (383a). The third exhaust chamber (383) communicates with the atmosphere through the third exhaust port (383a).

[0104] A cylinder (400) is provided with a first cylinder chamber (421) and a second cylinder chamber (422) inside a cylinder housing (401). The first cylinder chamber (421) and the second cylinder chamber (422) are partitioned by a piston (430). The volumes of the first cylinder chamber (421) and the second cylinder chamber (422) change depending on the movement of the piston (430).

[0105] The piston (430) is connected to the cylinder rod (410). According to the embodiment, the cylinder rod (410) is installed facing the second cylinder chamber (422).

[0106] The first side port (421a) communicates with the first cylinder room (421). The first side port (421a) communicates with the first cylinder room communication port (361) through the first pipe (341). A first three-way valve (510) is provided in a path communicating between the first side port (421a) and the first cylinder room communication port (361). A first path of the first three-way valve (510) is connected to the first cylinder room communication port (361), a second path is connected to the first side port (421a), and a third path is connected to the atmosphere.

[0107] The secondary port (422a) communicates with the second cylinder room (422). The secondary port (422a) communicates with the second cylinder room communication port (362) through the second pipe (342). A second three-way valve (520) is provided in a path communicating between the secondary port (422a) and the second cylinder room communication port (362). A first path of the second three-way valve (520) is connected to the second cylinder room communication port (362), a second path is connected to the secondary port (422a), and a third path is connected to the atmosphere.

[0108] Fig. 7 is a diagram illustrating a first use state of an air volume control device (100) according to one embodiment of the present invention. The first use state will be described with reference to Fig. 7.

[0109] In the first use condition, 1 kgf / cm with signal air 2 (Maximum signal air pressure according to the embodiment) is supplied with air pressure of 5 kgf / cm. 2 Air pressure is supplied. The side of the first three-way valve (510) leading to the atmosphere is closed. The side of the second three-way valve (520) leading to the atmosphere is closed.

[0110] The signal air fills the signal pressure chamber (313). When the signal pressure chamber (313) is filled with the air pressure of the signal air, the first diaphragm (331) is displaced by the generated force. The gap with the nozzle (370) changes due to the displacement of the first diaphragm (331). The nozzle (370) back pressure changes due to the change in the gap between the first diaphragm (331) and the nozzle (370). The generated force of the fourth diaphragm (334) overcomes the generated force of the third diaphragm (333) due to the nozzle (370) back pressure. The spool valve (350) moves in the A direction due to the generated force of the fourth diaphragm (334). When the spool valve (350) moves, the first spool (351) opens the first cylinder communication port (361). The flow path of the supply room (324) is formed by the first cylinder room communication port (361). The flow path of the supply room (324) is closed by the second cylinder room communication port (362).

[0111] Pressurized air flows into the first cylinder chamber (421) through the first cylinder chamber communication port (361). The first cylinder chamber (421) is filled with the air pressure of the pressurized air. The air pressure of the pressurized air pushes the piston (430) in the B direction. The air in the second cylinder chamber (422) is exhausted. The air in the second cylinder chamber (422) is exhausted, and the cylinder rod (410) moves in the B direction according to the movement of the piston (430).

[0112] The movement of the cylinder rod (410) is transmitted to the feedback spring (320) by the feedback connection (391), and the cylinder rod (410) moves until it is parallel to the force generated by the first diaphragm (331). As a result, a displacement of the cylinder rod (410) proportional to the input signal air occurs.

[0113] Fig. 8 is a second usage state diagram of an air volume control device (100) according to one embodiment of the present invention. The second usage state will be described with reference to Fig. 8.

[0114] In the second use condition, 0.2 kgf / cm with signal air 2 (Minimum signal air pressure according to the embodiment) is supplied with air pressure of 5 kgf / cm.2 Air pressure is supplied. The side of the first three-way valve (510) leading to the atmosphere is closed. The side of the second three-way valve (520) leading to the atmosphere is closed.

[0115] The signal air fills the signal pressure chamber (313). When the signal pressure chamber (313) is filled with the air pressure of the signal air, the first diaphragm (331) is displaced by the generated force. The gap with the nozzle (370) changes due to the displacement of the first diaphragm (331). In addition, the generated force of the third diaphragm (333) due to the air pressure of the compressed air moves the spool valve (350) in the B direction. When the spool valve (350) moves, the second spool (352) opens the second cylinder room communication port (362). The flow path of the supply chamber (324) is formed by the second cylinder room communication port (362). The flow path of the supply chamber (324) is closed by the first cylinder room communication port (361).

[0116] The pressurized air flows into the second cylinder chamber (422) through the second cylinder chamber communication port (362). The second cylinder chamber (422) is filled with the air pressure of the pressurized air. The air pressure of the pressurized air pushes the piston (430) in the A direction. The air in the first cylinder chamber (421) is exhausted. The air in the first cylinder chamber (421) is exhausted, and the cylinder rod (410) moves in the A direction according to the movement of the piston (430).

[0117] The movement of the cylinder rod (410) is transmitted to the feedback spring (320) by the feedback connection (391), and the cylinder rod (410) moves until it is parallel to the force generated by the first diaphragm (331). As a result, a displacement of the cylinder rod (410) proportional to the input signal air occurs.

[0118] FIGS. 9 and 10 are operation status diagrams during on-site inspection of an air volume control device (100) according to an embodiment of the present invention. The operation of the air volume control device (100) during on-site inspection will be described with reference to FIGS. 9 and 10.

[0119] As an example of the operating condition, 0.6 kgf / cm with signal air2 (The median value of the signal air according to the embodiment) is supplied as air pressure. The pressure air is 5 kgf / cm 2 The air pressure is supplied. In this case, the pressurized air is supplied through the first cylinder room communication port (361) and the second cylinder room communication port (362) so that the air pressures of the first cylinder room (421) and the second cylinder room (422) are equal. That is, the pressurized air is supplied by distributing it through the first cylinder room communication port (361) and the second cylinder room communication port (362) so that the air pressures of the first cylinder room (421) and the second cylinder room (422) are equal. For example, if the air pressure of the first cylinder chamber (421) is lower than the air pressure of the second cylinder chamber (422), pressurized air is supplied to the first cylinder chamber (421) by the balance of the generating force of the first diaphragm (331), the back pressure of the nozzle (370), the force of the feedback spring (320), etc. For example, if the air pressure of the second cylinder chamber (422) is lower than the air pressure of the first cylinder chamber (421), pressurized air is supplied to the second cylinder chamber (422) by the balance of the generating force of the first diaphragm (331), the back pressure of the nozzle (370), the force of the feedback spring (320), etc. As a result, the air pressures of the first cylinder chamber (421) and the second cylinder chamber (422) become equal (omitted from the drawing).

[0120] In the above-described state, if a failure of the air volume control device (100) is suspected on site, the first three-way valve (510) and the second three-way valve (520) can be switched once each by the worker. Hereinafter, FIG. 9 describes the operation when checking the air volume control device (100) by adjusting the first three-way valve (510), and FIG. 10 describes the operation when checking the air volume control device (100) by adjusting the second three-way valve (520).

[0121] Figure 9 shows a state in which the atmospheric side of the first three-way valve (510) is open and the first cylinder chamber communication port (361) side is closed. That is, the first cylinder chamber (421) is in communication with the atmosphere. The side of the second three-way valve (520) that leads to the atmosphere is closed.

[0122] 0.6 kgf / cm2 as signal air according to the embodiment 2 (Intermediate value of signal air according to the embodiment) is supplied as air pressure, and 5 kgf / cm is supplied as pressure air. 2 With the air pressure supplied, the first cylinder chamber (421) and the second cylinder chamber (422) are each supplied with 5 kgf / cm 2 The air pressure of the first cylinder chamber (421) is balanced. At this time, when the first cylinder chamber (421) is opened, the internal air of the first cylinder chamber (421) is exhausted, and the internal pressure is converted to atmospheric pressure. As the first cylinder chamber (421) is exhausted, the air pressure of the second cylinder chamber (422) becomes dominant, and the piston (430) moves in the A direction. Accordingly, the spool valve (350) moves in the B direction, and the second spool (352) opens the second cylinder chamber communication port (362). The flow path of the supply chamber (324) is formed as a path to the second cylinder chamber communication port (362). The flow path of the supply chamber (324) is closed as a path to the first cylinder chamber communication port (361). The pressurized air flows into the second cylinder chamber (422) through the second cylinder chamber communication port (362). The second cylinder chamber (422) is filled with compressed air. The compressed air pressure can further push the piston (430) in the A direction.

[0123] The cylinder rod (410) can move in the A direction depending on the operating status of the first three-way valve (310) regardless of the signal air. For example, the speed of movement in the A direction can be controlled depending on the speed of switching the first three-way valve (310). If the air volume control device (100) is broken due to environmental conditions such as high temperature, ash, moisture, and dust, the cylinder rod (410) does not move properly in the A direction. Therefore, the operator can immediately determine the failure of the air volume control device (100) by observing the movement of the cylinder rod (410).

[0124] Meanwhile, after inspection, when the atmospheric side of the first three-way valve (510) is closed and the first cylinder communication port (361) side is opened, the cylinder rod (410) returns to a position proportional to the signal air.

[0125] Fig. 10 shows a state in which the first three-way valve (510) is closed on the atmospheric side and the first cylinder room communication port (361) side is open, similar to the state of use described in Fig. 7. On the other hand, the atmospheric side of the second three-way valve (520) is open and the second cylinder room communication port (362) side is closed.

[0126] 0.6 kgf / cm2 as signal air according to the embodiment 2 (Intermediate value of signal air according to the embodiment) is supplied as air pressure, and 5 kgf / cm is supplied as pressure air. 2 With the air pressure supplied, the first cylinder chamber (421) and the second cylinder chamber (422) are each supplied with 5 kgf / cm 2 The air pressure of the second three-way valve (520) is balanced. At this time, when the atmospheric side of the second three-way valve (520) is opened, the internal air of the second cylinder chamber (422) is exhausted, and the internal pressure of the second cylinder chamber (422) is converted to atmospheric pressure. As the second cylinder chamber (422) is exhausted, the air pressure of the first cylinder chamber (421) becomes dominant, and the piston (430) moves in the B direction. Accordingly, the spool valve (350) moves in the A direction, and the first spool (351) opens the first cylinder chamber communication port (361). The flow path of the supply chamber (324) is formed as a path to the first cylinder chamber communication port (361). The flow path of the supply chamber (324) is closed as a path to the second cylinder chamber communication port (362). Pressurized air flows into the first cylinder chamber (421) through the first cylinder chamber communication port (361). The first cylinder chamber (421) is filled with the air pressure of the pressurized air. The air pressure of the pressurized air can further push the piston (430) in the B direction.

[0127] The cylinder rod (410) can move in the B direction depending on the operating status of the second three-way valve (520) regardless of the signal air. For example, the speed of movement in the B direction can be controlled depending on the speed of switching the second three-way valve (520). If the air volume control device (100) is broken due to environmental conditions such as high temperature, ash, moisture, and dust, the cylinder rod (410) does not move properly in the B direction. Therefore, the operator can immediately determine the failure of the air volume control device (100) by observing the movement of the cylinder rod (410).

[0128] Meanwhile, after inspection, when the atmospheric side of the second three-way valve (520) is closed and the second cylinder communication port (362) side is opened, the cylinder rod (410) returns to a position proportional to the signal air.

[0129] As described above, the example of switching the flow path using the first three-way valve (510) and the second three-way valve (520) was described.

[0130] However, in interpreting the scope of the claims of the present invention, the first three-way valve (510) should be interpreted as not only a single valve, but also as a plurality of components that perform the functions of opening the first cylinder chamber (421) to the atmosphere and closing the first cylinder chamber communication port (361) and should be interpreted as an equivalent entity. Of course, in the case of implementing the invention using the first three-way valve (510), since path switching is convenient, there is the effect of preventing operator errors.

[0131] In addition, when interpreting the scope of the claims of the present invention, the second three-way valve (520) is not limited to a single configuration, but should be interpreted as an equivalent entity by grouping multiple configurations when it performs the function of opening the second cylinder chamber (422) to the atmosphere and closing the second cylinder chamber communication port (362). Of course, when implementing the invention using the second three-way valve (520), it is advantageous in that it is possible to prevent operator errors because path switching is convenient.

[0132] Fig. 11 is a schematic diagram of an air volume control device (100) according to an embodiment of the present invention. The air volume control device (100) will be described with reference to Fig. 11. Instrument air is supplied to the positioner after moisture and / or oil are removed by a mist separator. In the embodiment, the positioner (300) is configured such that the air pressure of the signal air is 0.2 kgf / cm. 2 When the pressure air flows to OUT2, the air pressure of the signal air is 1 kgf / cm 2 When the boiler (10) is in operation, the pressurized air is normally supplied by distributing it to OUT1 and OUT2. At this time, when switching to path 3 for inspection, path 1 is blocked and the cylinder moves to the side with lower pressure. Paths 2 and 4 also operate on the same principle as paths 1 and 3.

[0133] According to the air volume control device (100) according to an embodiment of the present invention, it is possible to immediately check for a malfunction of the air volume control device (100) on site. If a malfunction of the device is suspected, the malfunction can be confirmed by switching the air path using the first three-way valve (510) and the second three-way valve (520). The first three-way valve (510) and the second three-way valve (520) according to the embodiment may be provided as ball valves.

[0134] Since the air volume control device (100) is installed on the outer wall of the furnace (20), it is exposed to foreign substances such as high temperature, ash, moisture, and dust, so it may rust or become deformed, resulting in a failure of the device. However, in the past, it was necessary to adjust the air pressure of the signal air using the control unit (a concept including the input unit and the display unit) in the driver's room to move the cylinder rod (410). In other words, the failure could not be immediately confirmed on site. However, according to an embodiment of the present invention, since the same effect as adjusting the air pressure of the signal air to the maximum and minimum values ​​only by operating the valve on site is obtained, the failure of the air volume control device (100) can be immediately identified on site.

[0135] In addition, in the past, even if only one air volume control device (100) was suspected of being faulty, the signal air pressure of all air volume control devices (100) sharing the signal air had to be changed as described in FIG. 3, but according to an embodiment of the present invention, only the suspected air volume control device (100) can be checked with a simple operation.

[0136] FIG. 12 and FIG. 13 are front and plan views showing an air volume control device (100) provided with a displacement measuring device (600) for a fault monitoring system.

[0137] In an embodiment, the displacement measuring device (600) may be a Linear Variable Displacement Transducer (LVDT). The displacement measuring device (600) measures the distance change according to the forward and backward movement of the cylinder rod (410). The displacement measuring device (600) outputs the distance change as an electrical signal. The output electrical signal is used as a feedback signal to determine whether the air volume measuring device (100) is operating normally according to the input signal. The range of the electrical signal output by the displacement measuring device (600) is set to have a first value to a second value, which is the same range as the input signal for generating the displacement of the cylinder rod (410). When a normal displacement occurs in the cylinder rod according to the electrical signal, which is the input signal, the normal electrical signal of the displacement measuring device output according to the normal displacement is set to output the same value as the electrical signal, which is the input signal. Accordingly, since in an ideal normal state the feedback signal is output with the same value as the input signal, it is possible to intuitively determine whether the displacement of the cylinder rod (410) has occurred appropriately in response to the input signal. Meanwhile, a power source for the displacement measuring device (600) may be connected to the displacement measuring device (600), and its representation in the drawing is omitted.

[0138] Figure 14 illustrates an air supply system according to an embodiment of the present invention. A system operator may reside in the driver's cabin (800). The system operator may operate an input unit (810) installed in the driver's cabin (800). Furthermore, the system's operating status can be checked through a display unit (820).

[0139] The air volume control device (100) is provided in a plurality of units as a group. In the embodiment, it is expressed that four air volume control devices (100a, 100b, 100d, 100d) are provided in a group. The air volume control devices (100) can be installed at the corners of the furnace (20), and a layer can form a group. A plurality of groups of air volume control devices can be provided. In this specification, one group is illustrated and described for concise explanation. Each of the air volume control devices (100a, 100b, 100d, 100d) constituting a group can be driven in conjunction with one input signal (S1). The input signal (S1) can be input from the driver's cabin through the input unit (810). In the embodiment, the input signal (S1) is an electrical signal. The maximum value of the input signal (S1) can be defined as a first value, and the minimum value can be defined as a second value. In an embodiment, the input signal (S1) may be a current value in the range of 4 mA to 20 mA. The input signal (S1) is converted into signal air (S2) and applied to each air volume control device (100). The input signal (S1) may be converted into signal air (S2) through a pneumatic converter (900). In an embodiment, when 12 mA, which is an intermediate value between the maximum and minimum values, is applied as the input signal (S1), the signal air (S2) may be converted into 0.6 kgf / cm2, which is an intermediate value of the signal air described above, and applied to the positioner (300).

[0140] In the embodiment, the displacement measuring device (600) outputs a current value according to the position of the cylinder rod (410, see FIG. 13) of the air volume control device (100) as a feedback signal and transmits the same to the driver's cab. The displacement measuring device (600) is installed in each air volume control device (100). The feedback signals (P1, P2, P3, P4) measured by each displacement measuring device (600a, 600b, 600c, 600d) in each air volume control device (100a, 100b, 100d) are transmitted to the driver's cab (800). The feedback signals (P1, P2, P3, P4) are displayed on the display unit (820).

[0141] In the driver's cabin (800), by monitoring the feedback signals (P1, P2, P3, P4) output from the displacement measuring device (600), it is possible to monitor whether the air volume control device (100) is operating normally. If the current value of the displacement measuring device (600a) is outside the error range, it is possible to recognize in the driver's cabin (800) that the air volume control device (100a) needs to be inspected. In the driver's cabin, the necessity of inspecting the air volume control device (100a) can be conveyed to the field worker, and the presence or absence of a malfunction can be confirmed on site.

[0142] Fig. 15 illustrates a screen configuration of a display unit (810) according to an embodiment of the present invention. The display unit (810) may be configured as a monitor. The display unit (810) according to the embodiment displays input signals and feedback signals input to each air volume control device (100). In the screen configuration according to the embodiment, only two groups of air volume control devices (100), namely the first group and the second group, are illustrated as examples, but dozens of groups may be displayed on the display unit (810). The embodiment will be described with reference to the drawings.

[0143] The display unit (810) indicates that a first input signal (S1-1) is input to the air volume control devices (100a, 100b, 100c, 100d) forming the first group. In addition, a state in which a second input signal (S1-2) is input to the air volume control devices (100e, 100f, 100g, 100h) forming the second group is indicated.

[0144] The display unit (810) displays feedback signals (P1 to P8) according to the displacement of each air volume control device (100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h). As an example for explanation, the error range of the feedback signal is set to +-5%. Considering the error range, the feedback signal (P1) is normally in the range of 11.4 mA to 12.6 mA. The feedback signal (P1) of the air volume control device (100a) is output as 8.0 mA. This is outside the error range and requires inspection. The driver in the driver's cab can recognize that the air volume control device (100a) requires inspection by looking at the feedback signal (P1).

[0145] If a feedback signal exceeds the error range, a notification may be provided to ensure driver awareness. The notification may be a visual notification displayed via the display unit (810). In an embodiment, the notification may be displayed in a different color than when the signal is in a normal state. In the illustrated embodiment, the feedback signal is displayed in blue when in a normal state, and in red when it exceeds the error range.

[0146] It is also possible to check whether the air volume control device (100) is malfunctioning by applying an input signal for inspection from the driver's cabin (800). In the past, an input signal for inspection was input from the driver's cabin, and a worker working on site had to measure the linear movement distance of the cylinder rod corresponding to the input signal to determine whether there was a malfunction. However, according to an embodiment of the present invention, an input signal for inspection is applied from the driver's cabin (800), and a feedback signal is observed to identify an air volume control device (100) requiring inspection among air volume control devices (100) installed in multiple locations.

[0147] According to an embodiment of the present invention, a thermal power generation system monitors the failure of an air volume control device from the operator's cabin, thereby identifying a location where a failure is suspected and requiring inspection. Furthermore, the presence of a malfunction in the air volume control device at a location suspected of failure can be confirmed on-site. According to an embodiment of the present invention, since the presence of a malfunction in the air volume control device can be confirmed on-site, efficient fault detection is possible.

[0148] The above description is merely an illustrative illustration of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention. Therefore, the embodiments described in the present invention are not intended to limit the technical idea of ​​the present invention, but rather to illustrate it, and the technical idea of ​​the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

Claims

1. In an air volume control device including a cylinder and a positioner, The above cylinder, A housing forming a cylinder chamber; The above cylinder chamber is divided into a first cylinder chamber and a second cylinder chamber, and a piston that reciprocates inside the cylinder chamber; and including a cylinder rod coupled with the piston, The above positioner, It causes movement of the cylinder rod in proportion to the input signal, A first cylinder room communication port communicating with the first cylinder room; and Includes a second cylinder room communication port communicating with the second cylinder room, A first three-way valve, one side of which is open to the atmosphere, i) opens a path connecting the first cylinder room communication port and the first cylinder room and closes the atmosphere side, or ii) opens a path between the first cylinder room and the atmosphere side and closes the first cylinder room communication port; and A second three-way valve having one side connected to the atmosphere, i) opening a path connecting the second cylinder room communication port and the second cylinder room and closing the atmosphere side, or ii) opening a path between the second cylinder room and the atmosphere side and closing the second cylinder room communication port; An air volume control device including:

2. In paragraph 1, The above positioner, A signal air input port, which is a path through which signal air flows in as the above input signal; A signal pressure chamber connected to the signal air input port and including a first diaphragm displaced by the signal air; A nozzle in which the back pressure changes by the displacement of the first diaphragm; A pressure air supply port, which is the path through which pressure air flows in; A first communication passage, a second communication passage, and a third communication passage having an orifice formed therein that communicate with the above-mentioned pressure air supply port; A spool valve including a first spool for opening and closing the first cylinder communication port, and a second spool for opening and closing the second cylinder communication port, and changing the passage through which the pressurized air moves to either the first cylinder communication port or the second cylinder communication port by a change in the back pressure of the nozzle; A supply room communicating with the first communication passage and closed by the first spool and the second spool; A first supply pressure chamber in communication with the second communication passage and having a third diaphragm connected to one end of the spool valve; A second supply pressure chamber communicating with the third communication passage and having a fourth diaphragm connected to the other end of the spool valve; and An air volume control device including a feedback spring, one end of which is connected to the first diaphragm and the other end of which is connected to the cylinder rod.

3. A plurality of air volume control devices according to the first clause, which share and receive input signals from one signal air supply source and share and receive pressurized air from one pressure air supply source; and Including a control unit that controls the air pressure of the signal air and the pressure air, Air supply system of a coal-fired power plant.

4. In an air supply system of a coal-fired power plant, including an air volume control device that receives signal air from a signal air supply source and supplies pressurized air from a pressurized air supply source according to an input signal, The above air volume control device includes a cylinder and a positioner, The above cylinder, A housing forming a cylinder chamber; The above cylinder chamber is divided into a first cylinder chamber and a second cylinder chamber, and a piston that reciprocates inside the cylinder chamber; and including a cylinder rod coupled with the piston, The above positioner, It generates displacement of the cylinder rod in proportion to an input signal, which is an electrical signal in the range of a first value to a second value, The above air supply system, A displacement measuring device configured to generate an electrical signal in proportion to the displacement of the cylinder rod in the range of the first value to the second value and to output the generated electrical signal as a feedback signal; and Including a display unit that visually displays the feedback signal of the displacement measuring device, The above positioner, A first cylinder room communication port communicating with the first cylinder room; and Includes a second cylinder room communication port communicating with the second cylinder room, The above air volume control device, A first three-way valve, one side of which is open to the atmosphere, i) opens a path connecting the first cylinder room communication port and the first cylinder room and closes the atmosphere side, or ii) opens a path between the first cylinder room and the atmosphere side and closes the first cylinder room communication port; and A second three-way valve having one side connected to the atmosphere, i) opening a path connecting the second cylinder room communication port and the second cylinder room and closing the atmosphere side, or ii) opening a path between the second cylinder room and the atmosphere side and closing the second cylinder room communication port; Air supply system of a coal-fired power plant including.

5. In paragraph 4, In the first paragraph, The above air volume control device is installed in multiple locations, The above air volume control devices are provided in multiple groups, and one input signal is applied to each group to be interlocked. The above displacement measuring device is provided for each of the air volume control devices, A display unit is placed in the driver's cabin. In the above display, The input signal applied to each of the above groups and the feedback signal output from each of the displacement measuring devices provided to each of the air volume control devices are visually displayed. Air supply system of a coal-fired power plant.

6. In paragraph 5, The air supply system of a coal-fired power plant, wherein the above input signal and the above feedback signal are current values ​​in the range of 4 mA to 20 mA.

7. In paragraph 5, An air supply system of a coal-fired power plant in which an alarm is displayed on the display unit when the above input signal and the above feedback signal are different beyond the error range.

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