Freezing prevention control device, air intake duct facility, gas turbine facility, and freezing prevention method

Abstract

This freezing prevention control device comprises: a freezing condition parameter detector capable of detecting a freezing condition parameter indicating whether or not there is a condition in which ice may adhere to a filter in an air intake duct; a pressure difference meter capable of detecting a pressure difference which is a difference between a pressure on an upstream side of the filter and a pressure on a downstream side of the filter in the air intake duct; and a control device body capable of instructing one of a heating state for heating the filter and a non-heating state for not heating the filter to a filter heating device capable of heating the filter according to the freezing condition parameter and the pressure difference.

Description

Anti-freeze control device, intake duct equipment, gas turbine equipment, and anti-freeze method

[0001] The present disclosure relates to a technique for suppressing freezing of a filter disposed in an intake duct. This application claims priority to Japanese Patent Application No. 2023-215548, filed on December 21, 2023, the contents of which are incorporated herein by reference.

[0002] An example of an intake duct system that introduces outside air into a gas turbine or the like is disclosed in Patent Document 1 below. This system includes an intake duct, a filter disposed in the intake duct, and a filter heating device that heats the filter. A thermometer detects the temperature of the outside air that flows into the intake duct. A hygrometer detects the humidity of the outside air that flows into the intake duct. When the temperature of the outside air that flows into the intake duct becomes lower than the dew point temperature and the humidity of the outside air becomes a predetermined humidity, the filter heating device introduces high-temperature air upstream of the filter to heat the filter. When the temperature of the outside air detected by the thermometer becomes equal to or higher than the dew point temperature, the filter heating device stops heating the filter.

[0003] Japanese Patent Application Laid-Open No. 2015-190452

[0004] In the technology described in Patent Document 1, as described above, when the temperature of the outside air flowing into the intake duct falls below the dew point temperature and the humidity of the outside air reaches a predetermined level, the filter is heated by the filter heating device. However, even when the temperature of the outside air flowing into the intake duct falls below the dew point temperature and the humidity of the outside air reaches the predetermined level, there may be little or no ice formed on the actual filter. In this case, heating the filter by the filter heating device would result in unnecessary consumption of heating energy.

[0005] In addition, in the technology described in Patent Document 1, as described above, when the temperature of the outside air flowing into the intake duct reaches or exceeds the dew point, the filter heating device stops heating the filter. However, even when the temperature of the outside air flowing into the intake duct reaches or exceeds the dew point, ice adhering to the filter may not completely melt and may still remain. In this case, if the filter heating device stops heating the filter, the heating energy consumed up until the heating was stopped will be wasted.

[0006] Therefore, an object of the present disclosure is to provide a technique that can reduce the consumption of heating energy for a filter.

[0007] An anti-freeze control device as one aspect for achieving the above object is applied to the following intake duct equipment. The intake duct equipment includes an intake duct having an intake port capable of drawing in outside air and an intake outlet through which the outside air drawn in from the intake port flows out, a filter arranged in the intake duct, and a filter heating device capable of heating the filter. The anti-freeze control device controlling the filter heating device includes a freeze condition parameter detector capable of detecting a freeze condition parameter indicating whether or not ice is likely to form on the filter, a pressure differential meter capable of detecting a pressure difference between an upstream pressure in the intake duct that is closer to the intake port than the filter and a downstream pressure that is closer to the intake outlet than the filter, and a control device main body capable of instructing the filter heating device to either a heating state in which the filter is heated or a non-heating state in which the filter is not heated, based on the freeze condition parameter and the pressure difference.

[0008] For example, consider a case where the filter heating device is instructed to be in either a heated state or a non-heated state based solely on the freezing condition parameter. Even if the outside air flowing into the intake duct satisfies the freezing condition parameter, there may be little ice on the actual filter. In this case, heating the filter with the filter heating device results in unnecessary consumption of heating energy. Also, even if the outside air flowing into the intake duct no longer satisfies the freezing condition parameter, there may still be ice remaining on the filter without completely melting. In this case, stopping the filter heating with the filter heating device will waste the heating energy that had been consumed up until the heating was stopped.

[0009] Next, consider a case where either a heated state or a non-heated state is indicated based solely on the pressure difference between the upstream and downstream sides of the filter. Sometimes, dust adheres to the filter, causing a large pressure difference. In this case, heating the filter with a filter heating device results in unnecessary consumption of heating energy. Furthermore, even if ice adhering to the filter melts as a result of heating the filter with a filter heating device, the freezing condition may still be satisfied. In this case, ice begins to adhere to the filter again, causing a large pressure difference. Therefore, the filter heating device repeatedly heats and unheats the filter within a short period of time, resulting in a large consumption of heating energy.

[0010] On the other hand, in this aspect, the filter heating device is instructed to enter either a heated state or a non-heated state depending on the freezing condition parameter and the pressure difference. Therefore, in this aspect, the filter can be heated when the freezing condition is met and the filter is clogged with ice, resulting in a large pressure difference between the upstream and downstream sides of the filter. Also, in this aspect, filter heating can be stopped when the freezing condition is not met and the filter is not substantially clogged with ice, resulting in a small pressure difference between the upstream and downstream sides of the filter.

[0011] Therefore, in this aspect, the filter heating device can be put into a heating state at an appropriate time period and into a non-heating state at an appropriate time period, thereby reducing the consumption of energy for heating the filter.

[0012] An air intake duct facility according to one aspect for achieving the above object includes the anti-freeze control device according to the above aspect, the air intake duct, the filter, and the filter heating device.

[0013] One embodiment of gas turbine equipment for achieving the above object includes the intake duct equipment according to the embodiment and a gas turbine. The gas turbine includes a compressor capable of compressing outside air from the intake duct to generate compressed air, a combustor capable of burning fuel in the compressed air to generate combustion gas, and a turbine capable of being driven by the combustion gas. The filter heating device includes a compressed air line capable of directing a portion of the compressed air generated by the compressor to a side upstream of the filter in the intake duct, and a compressed air valve provided in the compressed air line. The control device main body issues an open instruction to the compressed air valve as an instruction for the heated state, and issues a close instruction to the compressed air valve as an instruction for the non-heated state.

[0014] An anti-freezing method as one aspect for achieving the above object is applied to the following intake duct equipment. The gas turbine equipment includes an intake duct having an intake port capable of drawing in outside air and an intake port through which the outside air drawn in from the intake port flows out, a filter disposed in the intake duct, and a filter heating device capable of heating the filter. The anti-freezing method for suppressing freezing of the filter includes the following steps: a freezing condition parameter detection step for detecting a freezing condition parameter indicating whether or not ice is likely to form on the filter; a pressure difference detection step for detecting a pressure difference between an upstream pressure in the intake duct that is closer to the intake port than the filter and a downstream pressure in the intake duct that is closer to the intake port than the filter; and a control step for instructing the filter heating device to select one of a heating state in which the filter is heated and a non-heating state in which the filter is not heated, based on the freezing condition parameter and the pressure difference.

[0015] In this aspect, similar to the antifreeze control device of the above aspect, it is possible to reduce the consumption of energy for heating the filter.

[0016] In one aspect of the present disclosure, it is possible to reduce the consumption of heating energy for a filter disposed in an intake duct.

[0017] Fig. 1 is a schematic configuration diagram of a gas turbine facility in an embodiment according to the present disclosure. Fig. 2 is a functional block diagram of an anti-freeze control device in a first embodiment according to the present disclosure. Fig. 3 is a graph showing the relationship between the flow rate of outside air and a reference pressure difference in the first embodiment according to the present disclosure. Fig. 4 is a flowchart showing the operation of the anti-freeze control device in the first embodiment according to the present disclosure. Fig. 5 is a functional block diagram of an anti-freeze control device in a second embodiment according to the present disclosure. Fig. 6 is a functional block diagram of an anti-freeze control device in a third embodiment according to the present disclosure.

[0018] Various embodiments according to the present disclosure will be described below with reference to the drawings.

[0019] [Embodiment of Gas Turbine Facility] Hereinafter, a gas turbine facility according to this embodiment will be described with reference to FIGS. 1 to 3. FIG.

[0020] As shown in FIG. 1 , the gas turbine facility in this embodiment includes a gas turbine GT and an intake duct facility 40 .

[0021] The gas turbine GT includes a compressor 10 capable of compressing outside air A to generate compressed air Acom, a plurality of combustors 20 that burn fuel F in the compressed air Acom to generate combustion gas G, a turbine 30 driven by the high-temperature, high-pressure combustion gas G, and an intermediate casing 25.

[0022] The compressor 10 includes a compressor rotor 11 rotatable about an axis Ar, a compressor casing 12 covering the compressor rotor 11, a plurality of compressor stator vane rows 13, an intake air regulator 14, and an intake casing 15. The turbine 30 includes a turbine rotor 31 rotatable about the axis Ar, a turbine casing 32 covering the turbine rotor 31, a plurality of turbine stator vane rows 33, and an exhaust casing 35. Hereinafter, the direction in which the axis Ar extends will be referred to as the axial direction Da, one side in the axial direction Da will be referred to as the axial upstream side Dau, and the other side in the axial direction Da will be referred to as the axial downstream side Dad. The circumferential direction centered on the axis Ar will simply be referred to as the circumferential direction Dc. The direction perpendicular to the axis Ar will be referred to as the radial direction Dr, and the side of the radial direction Dr approaching the axis Ar will be referred to as the radially inner side Dri, and the opposite side will be referred to as the radially outer side Dro.

[0023] The compressor 10 is disposed on the axial upstream side Dau with respect to the turbine 30. The compressor rotor 11 has a compressor rotor shaft 11s that extends in the axial direction Da about the axis Ar, and a plurality of compressor rotor blade rows 11b attached to the compressor rotor shaft 11s. The plurality of compressor rotor blade rows 11b are aligned in the axial direction Da. Each compressor rotor blade row 11b is composed of a plurality of rotor blades aligned in the circumferential direction Dc. One of a plurality of compressor stator vane rows 13 is disposed on the axial downstream side Dad of each of the plurality of compressor rotor blade rows 11b. Each compressor stator vane row 13 is attached inside the compressor casing 12. Each compressor stator vane row 13 is composed of a plurality of stator vanes aligned in the circumferential direction Dc. The intake air amount regulator 14 has a plurality of inlet guide vanes 14v and a driver 14d that can change the orientation of each inlet guide vane 14v. The plurality of inlet guide vanes 14v are arranged on the axially upstream side Dau of the plurality of compressor rotor blade rows 11b. The plurality of inlet guide vanes 14v are arranged side by side in the circumferential direction. The intake casing 15 is arranged axially upstream of the plurality of inlet guide vanes 14v and is connected to the end of the compressor casing 12 on the axially upstream side Dau. This intake casing 15 can efficiently guide outside air A into the compressor casing 12.

[0024] The turbine rotor 31 has a turbine rotor shaft 31s extending in the axial direction Da centered on the axis Ar, and a plurality of turbine rotor blade rows 31b attached to the turbine rotor shaft 31s. The plurality of turbine rotor blade rows 31b are aligned in the axial direction Da. Each turbine rotor blade row 31b is composed of a plurality of rotor blades aligned in the circumferential direction Dc. One of the plurality of turbine stator blade rows 33 is arranged on the axial upstream side Dau of each of the plurality of turbine rotor blade rows 31b. Each turbine stator blade row 33 is attached inside the turbine casing 32. Each turbine stator blade row 33 is composed of a plurality of stator blades aligned in the circumferential direction Dc. The exhaust casing 35 is arranged axially downstream Dad of the plurality of turbine rotor blade rows 31b and is connected to the end of the turbine casing 32 on the axial downstream side Dad.

[0025] The intermediate casing 25 is disposed between the compressor casing 12 and the turbine casing 32 in the axial direction Da. An end of the intermediate casing 25 on the axial upstream side Dau is connected to an end of the compressor casing 12 on the axial downstream side Dad. An end of the intermediate casing 25 on the axial downstream side Dad is connected to an end of the turbine casing 32 on the axial upstream side Dau. The multiple combustors 20 are attached to the intermediate casing 25 and lined up in the circumferential direction Dc.

[0026] The exhaust casing 35 is connected to a chimney 39 via, for example, an exhaust duct. Note that a heat recovery boiler that generates steam by utilizing the heat of the exhaust gas from the turbine 30 may be installed in the exhaust duct.

[0027] The compressor rotor 11 and the turbine rotor 31 are positioned on the same axis Ar and are connected to each other to form a gas turbine rotor 1. To this gas turbine rotor 1, for example, a rotor of a generator GEN is connected.

[0028] The intake duct equipment 40 includes an intake duct 41, a filter 44 arranged in the intake duct 41, a filter heating device 45 capable of heating the filter 44, and an anti-freeze control device 50 that controls the filter heating device 45.

[0029] The intake duct 41 includes an intake duct main body 42 and a louver 43. The intake duct main body 42 includes an intake port 42i through which outside air A can be drawn and an intake outlet 42o through which the outside air A drawn in through the intake port 42i flows out. The intake outlet 42o of the intake duct main body 42 is connected to the intake casing 15 of the compressor 10. Therefore, the outside air A that flows into the intake duct main body 42 flows into the compressor casing 12 via the intake casing 15. A louver 43 is provided within the intake duct main body 42, positioned along the intake port 42i. The louver 43 serves to prevent large debris, snow, and the like contained in the outside air A from flowing into the intake duct main body 42.

[0030] The filter 44 is disposed inside the intake duct main body 42 so as to block the flow path inside the intake duct main body 42. The filter 44 serves to capture foreign matter that has flowed into the intake duct main body 42. Here, with the filter 44 as the reference, the side of the intake port 42i is defined as the upstream side Du, and the side of the intake outlet 42o is defined as the downstream side Dd.

[0031] The filter heating device 45 includes a compressed air line 46 that can guide a portion of the high-temperature compressed air Acom generated by the compressor 10 to Du, upstream of the filter 44, in the intake duct 41, and a compressed air valve 47 that is provided in the compressed air line 46. The compressed air line 46 is connected to the intermediate casing 25. Thus, the compressed air line 46 can guide a portion of the compressed air Acom that is discharged from the compressor 10 and flows into the intermediate casing 25, into the intake duct 41. In the filter heating device 45, when the compressed air valve 47 is open, the high-temperature compressed air Acom is guided to Du, upstream of the filter 44, and the filter 44 is heated by the compressed air Acom. Therefore, the filter heating device 45 is in a heating state (ON) when the compressed air valve 47 is open, and in a non-heating state (OFF) when the compressed air valve 47 is closed.

[0032] The anti-freeze control device 50 outputs an ON instruction signal to the compressed air valve 47 of the filter heating device 45 to instruct the heating state (ON) and an OFF instruction signal to instruct the non-heating state (OFF).

[0033] Various embodiments of the antifreeze control device and the antifreeze method will be described below.

[0034] First Embodiment of Antifreeze Control Device and Antifreeze Method As shown in FIGS. 1 and 2 , an antifreeze control device 50 in this embodiment includes a freezing condition parameter detector 51, a pressure differential meter 55, and a control device main body 60.

[0035] In this embodiment, the freezing condition parameter detector 51 includes a thermometer 52 capable of detecting the temperature of the outside air A and a hygrometer 53 capable of detecting the humidity of the outside air A. Both the thermometer 52 and the hygrometer 53 are provided in the intake duct main body 42 at a position Du upstream of the filter 44. Therefore, the thermometer 52 can detect the temperature of the outside air A at a position Du upstream of the filter 44. Furthermore, the hygrometer 53 can detect the humidity of the outside air A at a position Du upstream of the filter 44.

[0036] The pressure differential gauge 55 has a first pressure gauge 56 and a second pressure gauge 57. The first pressure gauge 56 is provided in the intake duct main body 42 at a position Du upstream of the filter 44, and can detect the pressure of the outside air A at a position Du upstream of the filter 44 in the intake duct main body 42. The second pressure gauge 57 is provided in the intake duct main body 42 at a position Dd downstream of the filter 44, and can detect the pressure of the outside air A at a position Dd downstream of the filter 44 in the intake duct main body 42.

[0037] In this embodiment, the anti-freeze control device 50 has a third pressure gauge 58 and a downstream thermometer 59 in addition to the freezing condition parameter detector 51 and the pressure differential gauge 55. The third pressure gauge 58 can detect the pressure of the outside air A at a position Dd downstream of the second pressure gauge 57 in the intake duct main body 42. The downstream thermometer 59 can detect the pressure of the outside air A at a position Dd downstream of the filter 44 in the intake duct main body 42.

[0038] The control device main body 60 can control the filter heating device 45 based on various parameters detected by the freezing condition parameter detector 51, pressure differential meter 55, third pressure meter 58, and downstream thermometer 59 described above.

[0039] As shown in FIG. 2, the control device main body 60 includes a pressure difference calculator 61, a flow rate calculator 62, a pressure difference determiner 63, a freezing condition determiner 64, and a heating controller 70.

[0040] The pressure difference calculator 61 calculates the difference between the pressure detected by the first pressure gauge 56 and the pressure detected by the second pressure gauge 57. That is, the pressure difference calculator 61 calculates the pressure difference between the pressure Du upstream of the filter 44 and the pressure Dd downstream of the filter 44.

[0041] The flow rate calculator 62 calculates the flow rate of outside air A flowing through the intake duct main body 42 based on the pressure detected by the second pressure gauge 57, the pressure detected by the third pressure gauge 58, the temperature detected by the downstream thermometer 59, and the flow path area of ​​the intake duct main body 42 between the position where the second pressure gauge 57 is installed and the position where the third pressure gauge 58 is installed.

[0042] The pressure difference determiner 63 determines a reference pressure difference ΔPb and determines whether the pressure difference calculated by the pressure difference calculator 61 is greater than the reference pressure difference ΔPb. As shown in FIG. 3, the pressure difference determiner 63 holds a relationship Fx between the flow rate FL of outside air A flowing through the intake duct main body 42 and the reference pressure difference ΔPb. The pressure difference determiner 63 uses this relationship Fx to calculate the reference pressure difference ΔPb corresponding to the flow rate FL calculated by the flow rate calculator 62. The reference pressure difference ΔPb is 1.2 to 1.4 times the pressure difference when there is almost no dirt, ice, or the like attached to the filter 44.

[0043] The freezing condition determiner 64 includes a temperature determiner 65, a humidity determiner 66, and a condition satisfaction determiner 68. The temperature determiner 65 determines whether the temperature detected by the thermometer 52 is below a predetermined reference temperature Tb based on the dew point temperature. The humidity determiner 66 determines whether the humidity detected by the hygrometer 53 is higher than a predetermined reference humidity Hb based on 100% humidity. The condition satisfaction determiner 68 determines that the freezing condition is satisfied when the temperature detected by the thermometer 52 is below the reference temperature Tb and the humidity detected by the hygrometer 53 is higher than the reference humidity Hb. The condition satisfaction determiner 68 also determines that the freezing condition is not satisfied when the temperature detected by the thermometer 52 is not below the reference temperature Tb and / or the humidity detected by the hygrometer 53 is not higher than the reference humidity Hb. Therefore, the condition satisfaction determiner 68 includes an AND circuit.

[0044] Here, the reference temperature Tb and reference humidity Hb will be explained. For ice to adhere to the filter 44, supercooled mist must be present in the outdoor air A. In other words, for the freezing condition to be met, the outdoor air temperature must be below the dew point, i.e., below 0°C, and the humidity in the outdoor air A must be 100%. Therefore, in this embodiment, the freezing condition under which ice can adhere to the filter 44 is met when the temperature detected by the thermometer 52 is below a predetermined reference temperature Tb based on the dew point temperature, and the humidity detected by the hygrometer 53 is higher than a predetermined reference humidity Hb based on 100% humidity. In this embodiment, the reference temperature Tb is slightly higher than 0°C, for example, 2°C. The temperature of the outdoor air A varies slightly depending on the temperature detection position. For this reason, in this embodiment, the reference temperature Tb is set to 2°C. Furthermore, in this embodiment, the reference humidity Hb is slightly lower than 100%, for example, 98%. The humidity in the outdoor air A varies slightly depending on the humidity detection position. Furthermore, the hygrometer 53 generally has a large detection error, so in this embodiment, the reference humidity Hb is set to 98%.

[0045] The reference temperature Tb may be any temperature in the range of 0° C. to 5° C. The reference humidity Hb may be any humidity in the range of 95% or more and less than 100%.

[0046] In this embodiment, as described above, whether or not ice is likely to adhere to the filter 44 is not determined solely based on the temperature of the outside air A, but is determined based on the temperature of the outside air A and the humidity in the outside air A, so that it is possible to recognize with a high probability that ice will adhere to the filter 44.

[0047] The heating controller 70 includes an ON instruction signal generator 71, an OFF instruction signal generator 72, and an instruction signal output unit 73. When the instruction signal output unit 73 outputs an OFF instruction signal indicating a non-heating state (OFF) to the compressed air valve 47 of the filter heating device 45, the ON instruction signal generator 71 generates an ON instruction signal indicating a heating state (ON) if the pressure difference is greater than the reference pressure difference ΔPb and the freezing condition is satisfied. Therefore, the ON instruction signal generator 71 includes an AND circuit. When the instruction signal output unit 73 outputs an ON instruction signal to the compressed air valve 47 of the filter heating device 45, the OFF instruction signal generator 72 generates an OFF instruction signal if the pressure difference is not greater than the reference pressure difference ΔPb and the freezing condition is not satisfied. Therefore, the ON instruction signal generator 71 includes a NOR circuit. When the ON instruction signal generator 71 generates an ON instruction signal, the instruction signal output device 73 continues to output an ON instruction signal to the compressed air valve 47 of the filter heating device 45 until the OFF instruction signal generator 72 generates an OFF instruction signal. Also, when the OFF instruction signal generator 72 generates an OFF instruction signal, the instruction signal output device 73 continues to output an OFF instruction signal to the compressed air valve 47 of the filter heating device 45 until the ON instruction signal generator 71 generates an ON instruction signal. Therefore, this signal output device has a flip-flop circuit that holds the signal.

[0048] The control device main body 60 described above is a computer. All of the functional elements of the control device main body 60 described above function when an anti-freeze control program stored in an external storage device of the computer is loaded into the main storage device of the computer and executed by the CPU (Central Processing Unit) of the computer.

[0049] Next, the operation of the antifreeze control device 50 in this embodiment will be described with reference to the flowchart shown in FIG.

[0050] The freezing condition parameter detector 51 detects a freezing condition parameter that indicates whether or not ice may adhere to the filter 44 (freezing condition parameter detection step S1). That is, here, the thermometer 52 detects the temperature of the outside air A, and the hygrometer 53 detects the humidity in the outside air A.

[0051] The first pressure gauge 56 detects the pressure of the outside air A at a position Du upstream of the filter 44, and the second pressure gauge 57 detects the pressure of the outside air A at a position Dd downstream of the filter 44. The pressure difference calculator 61 calculates a pressure difference between the pressure detected by the first pressure gauge 56 and the pressure detected by the second pressure gauge 57 (pressure difference detection step S2).

[0052] The freezing condition determiner 64 determines whether the freezing condition parameters detected by the freezing condition parameter detector 51 satisfy the freezing conditions (freezing condition determination step S3). Specifically, when the temperature determiner 65 of the freezing condition determiner 64 determines that the temperature detected by the thermometer 52 is lower than the reference temperature Tb and the humidity determiner 66 of the freezing condition determiner 64 determines that the humidity detected by the hygrometer 53 is higher than the reference humidity Hb, the condition satisfaction determiner 68 determines that the freezing conditions are satisfied. When the temperature determiner 65 determines that the temperature detected by the thermometer 52 is not lower than the reference temperature Tb and / or the humidity determiner 66 determines that the humidity detected by the hygrometer 53 is not higher than the reference humidity Hb, the condition satisfaction determiner 68 determines that the freezing conditions are not satisfied.

[0053] The pressure difference determiner 63 determines a reference pressure difference ΔPb according to the flow rate of outside air A calculated by the flow rate calculator 62, and then determines whether the pressure difference calculated by the pressure difference calculator 61 is greater than the reference pressure difference ΔPb (pressure difference determination step S4).

[0054] The heating controller 70 outputs an ON instruction signal or an OFF instruction signal to the filter heating device 45 depending on the determination results of the freezing condition determiner 64 and the pressure difference determiner 63 (heating control step S5). Specifically, when the instruction signal output device 73 outputs an OFF instruction signal, the ON instruction signal generator 71 of the heating controller 70 generates an ON instruction signal instructing a heating state (ON) if the pressure difference is larger than the reference pressure difference ΔPb and the freezing condition is satisfied. When the instruction signal output device 73 outputs an ON instruction signal, the OFF instruction signal generator 72 of the heating controller 70 generates an OFF instruction signal if the pressure difference is not larger than the reference pressure difference ΔPb and the freezing condition is not satisfied. When the ON instruction signal generator 71 generates an ON instruction signal, the instruction signal output unit 73 of the heating controller 70 continues to output an ON instruction signal to the compressed air valve 47 of the filter heating device 45 until the OFF instruction signal generator 72 generates an OFF instruction signal. Also, when the OFF instruction signal generator 72 generates an OFF instruction signal, the instruction signal output unit 73 continues to output an OFF instruction signal to the compressed air valve 47 of the filter heating device 45 until the ON instruction signal generator 71 generates an ON instruction signal.

[0055] For example, consider a case where the filter heating device 45 is instructed to enter either a heated state or a non-heated state based solely on the freezing condition parameter. Even if the outside air A flowing into the intake duct 41 satisfies the freezing condition parameter, there may be little ice on the actual filter 44. In this case, heating the filter 44 with the filter heating device 45 results in unnecessary consumption of heating energy. Furthermore, even if the outside air A flowing into the intake duct 41 no longer satisfies the freezing condition parameter, there may still be ice remaining on the filter 44 without completely melting. In this case, stopping the heating of the filter 44 with the filter heating device 45 results in unnecessary consumption of heating energy that had been consumed up until the heating was stopped.

[0056] Next, consider a case where either the heated state or the unheated state is indicated based solely on the pressure difference between the upstream side Du and the downstream side Dd of the filter 44. Dust may adhere to the filter 44, increasing the pressure difference. In this case, heating the filter 44 with the filter heating device 45 results in unnecessary consumption of heating energy. Furthermore, even if ice adhering to the filter 44 melts as a result of heating the filter 44 with the filter heating device 45, the freezing condition may still be satisfied. In this case, ice may begin to adhere to the filter 44 again, increasing the pressure difference. Therefore, the filter heating device 45 repeatedly heats and unheats the filter 44 in a short period of time, resulting in increased consumption of heating energy.

[0057] On the other hand, in this embodiment, the filter heating device 45 is instructed to enter either a heated state or a non-heated state depending on the freezing condition parameters and the pressure difference. Therefore, in this embodiment, the filter 44 can be heated when the freezing condition is met and the filter 44 is clogged with ice, resulting in a large pressure difference between the upstream side Du and the downstream side Dd of the filter 44. Also, in this aspect, heating of the filter 44 can be stopped when the freezing condition is not met and the filter 44 is barely clogged with ice, resulting in a small pressure difference between the upstream side Du and the downstream side Dd of the filter 44.

[0058] Therefore, in this embodiment, the filter heating device 45 can be heated at appropriate times and can be put into a non-heated state at appropriate times, thereby reducing the consumption of heating energy for the filter 44.

[0059] Second Embodiment of Antifreeze Control Device and Antifreeze Method As shown in Figure 5, the antifreeze control device 50a in this embodiment also has a freezing condition parameter detector 51, a pressure differential meter 55, and a control device main body 60a, similar to the antifreeze control device 50 in the first embodiment. However, the antifreeze control device 50a in this embodiment differs from the control device main body 60 of the antifreeze control device 50 in the first embodiment only in the configuration of the control device main body 60a. Therefore, the following description will mainly focus on the control device main body 60a of the antifreeze control device 50a in this embodiment.

[0060] The control device main body 60a in this embodiment also has a pressure difference calculator 61, a flow rate calculator 62, a pressure difference determiner 63a, a freezing condition determiner 64a, and a heating controller 70a, similar to the control device main body 60 in the first embodiment. However, the pressure difference determiner 63a, the freezing condition determiner 64a, and the heating controller 70a of the control device main body 60a in this embodiment are different from the pressure difference determiner 63, the freezing condition determiner 64, and the heating controller 70 of the control device main body 60 in the first embodiment.

[0061] The pressure difference determiner 63a in this embodiment includes a first pressure difference determiner 63aa and a second pressure difference determiner 63ab. The first pressure difference determiner 63aa determines a first reference pressure difference ΔPb1 and determines whether the pressure difference calculated by the pressure difference calculator 61 is greater than the first reference pressure difference ΔPb1. Like the pressure difference determiner 63 in the first embodiment, the first pressure difference determiner 63aa maintains a relationship Fx between the flow rate of outside air A flowing through the intake duct main body 42 and the first reference pressure difference ΔPb1. The first pressure difference determiner 63aa uses this relationship Fx to calculate the first reference pressure difference ΔPb1 corresponding to the flow rate calculated by the flow rate calculator 62. The second pressure difference determiner 63ab determines a second reference pressure difference ΔPb2 and determines whether the pressure difference calculated by the pressure difference calculator 61 is greater than the second reference pressure difference ΔPb2. In other words, the second pressure difference determiner 63ab determines whether the pressure difference calculated by the pressure difference calculator 61 is equal to or smaller than the second reference pressure difference ΔPb2. The second pressure difference determiner 63ab determines the pressure difference slightly smaller than the first reference pressure difference ΔPb1 at this time as the second reference pressure difference ΔPb2.

[0062] The freezing condition determiner 64a in this embodiment includes a temperature determiner 65a, a humidity determiner 66a, a first condition satisfaction determiner 68a, and a second condition satisfaction determiner 69a.

[0063] The temperature determiner 65a includes a first temperature determiner 65aa and a second temperature determiner 65ab. The first temperature determiner 65aa determines whether the temperature detected by the thermometer 52 is less than a predetermined first reference temperature Tb1. The second temperature determiner 65ab determines whether the temperature detected by the thermometer 52 is less than a predetermined second reference temperature Tb2. In other words, the second temperature determiner 65ab determines whether the temperature detected by the thermometer 52 is equal to or greater than the second reference temperature Tb2. The first reference temperature Tb1 and the second reference temperature Tb2 are both predetermined temperatures based on the dew point temperature. The first reference temperature Tb1 is, for example, 2°C, slightly higher than the dew point temperature of 0°C. The second reference temperature Tb2 is, for example, 4°C, which is 2°C higher than the first reference temperature Tb1. The first reference temperature Tb1 may be any temperature between 0°C and 4°C. The second reference temperature Tb2 may be any temperature as long as it is slightly higher than the first reference temperature Tb1.

[0064] The humidity determiner 66a includes a first humidity determiner 66aa and a second humidity determiner 66ab. The first humidity determiner 66aa determines whether the humidity detected by the hygrometer 53 is higher than a predetermined first reference humidity Hb1. The second humidity determiner 66ab determines whether the humidity detected by the hygrometer 53 is higher than a predetermined second reference humidity Hb2. In other words, the second humidity determiner 66ab determines whether the humidity detected by the hygrometer 53 is equal to or lower than the second reference humidity Hb2. The first reference humidity Hb1 and the second reference humidity Hb2 are both predetermined humidity values ​​based on a humidity of 100%. The first reference humidity Hb1 is, for example, 98%, which is slightly lower than 100%. The second reference humidity Hb2 is, for example, 96%, which is 2% lower than the first reference humidity Hb1. The first reference humidity Hb1 may be any humidity value as long as it is lower than 100% and equal to or higher than 96%. The second reference humidity Hb2 may be any humidity value as long as it is slightly lower than the first reference humidity Hb1.

[0065] The first condition satisfaction judging device 68a judges that the freezing condition is satisfied when the temperature detected by the thermometer 52 is less than the first reference temperature Tb1 and the humidity detected by the hygrometer 53 is higher than the first reference humidity Hb1. Therefore, this first condition satisfaction judging device 68a has an AND circuit. Meanwhile, the second condition satisfaction judging device 69a judges that the freezing condition is not satisfied when the temperature detected by the thermometer 52 is not less than the second reference temperature Tb2 (is equal to or higher than the second reference temperature Tb2) and / or the humidity detected by the hygrometer 53 is not higher than the second reference humidity Hb2 (is equal to or lower than the second reference humidity Hb2). Therefore, this second condition satisfaction judging device 69a has an OR circuit.

[0066] Like the heating controller 70 in the first embodiment, the heating controller 70a includes an ON instruction signal generator 71, an OFF instruction signal generator 72a, and an instruction signal output unit 73. However, when the instruction signal output unit 73 outputs an ON instruction signal indicating the heating state (ON) to the compressed air valve 47 of the filter heating device 45, the OFF instruction signal generator 72a of this heating control device generates an OFF instruction signal if the pressure difference is not higher than the second reference pressure difference ΔPb2 (is equal to or less than the second reference pressure difference ΔPb2) and the freezing condition is not satisfied. Therefore, the OFF instruction signal generator 72a includes an AND circuit. Note that while the OFF instruction signal generator 72 in the first embodiment includes a NOR circuit, the OFF instruction signal generator 72a in this embodiment includes an AND circuit. This is because the pressure difference determiner 63a in this embodiment outputs a signal indicating that the pressure difference is higher than the second reference pressure difference ΔPb2 (i.e., equal to or lower than the second reference pressure difference ΔPb2), and the freezing condition determiner 64a in this embodiment outputs a signal indicating that the freezing condition is not satisfied. Therefore, although the configuration of the OFF instruction signal generator 72a in this embodiment is different from the configuration of the OFF instruction signal generator 72 in the first embodiment, the OFF instruction signal generator 72a in this embodiment also generates an OFF instruction signal when the pressure difference is not higher than the reference pressure difference and the freezing condition is not satisfied, similar to the OFF instruction signal generator 72 in the first embodiment. When the ON instruction signal generator 71 generates an ON instruction signal, the instruction signal output unit 73 continues to output an ON instruction signal to the compressed air valve 47 of the filter heating device 45 until the OFF instruction signal generator 72a generates an OFF instruction signal. Furthermore, when the OFF instruction signal generator 72a generates an OFF instruction signal, the instruction signal output device 73 continues to output an OFF instruction signal to the compressed air valve 47 of the filter heating device 45 until the ON instruction signal generator 71 generates an ON instruction signal.

[0067] Next, the operation of the antifreeze control device 50a in this embodiment will be described with reference to the flowchart shown in FIG.

[0068] As in the first embodiment, the freezing condition parameter detector 51 detects a freezing condition parameter indicating whether or not ice may adhere to the filter 44 (freezing condition parameter detection step S1). That is, in this embodiment, the thermometer 52 detects the temperature of the outside air A, and the hygrometer 53 detects the humidity of the outside air A.

[0069] The first pressure gauge 56 detects the pressure of the outside air A at a position Du upstream of the filter 44, and the second pressure gauge 57 detects the pressure of the outside air A at a position Dd downstream of the filter 44. The pressure difference calculator 61 calculates a pressure difference between the pressure detected by the first pressure gauge 56 and the pressure detected by the second pressure gauge 57 (pressure difference detection step S2).

[0070] The freezing condition determiner 64a determines whether the freezing condition parameters detected by the freezing condition parameter detector 51 satisfy the freezing condition (freezing condition determination step S3a). Specifically, when the first temperature determiner 65aa of the freezing condition determiner 64a determines that the temperature detected by the thermometer 52 is lower than the first reference temperature Tb1 and the first humidity determiner 66aa of the freezing condition determiner 64a determines that the humidity detected by the hygrometer 53 is higher than the first reference humidity Hb1, the first condition satisfaction determiner 68a determines that the freezing condition is satisfied. When the second temperature determiner 65ab determines that the temperature detected by the thermometer 52 is equal to or higher than the second reference temperature Tb2 and / or the second humidity determiner 66ab determines that the humidity detected by the hygrometer 53 is equal to or lower than the second reference humidity Hb2, the second condition satisfaction determiner 69a determines that the freezing condition is not satisfied.

[0071] The first pressure difference determiner 63aa determines a first reference pressure difference ΔPb1 according to the flow rate of outside air A calculated by the flow rate calculator 62, and then determines whether the pressure difference calculated by the pressure difference calculator 61 is greater than the first reference pressure difference ΔPb1. The second pressure difference determiner 63ab determines a second reference pressure difference ΔPb2 according to the flow rate of outside air A calculated by the flow rate calculator 62, and then determines whether the pressure difference calculated by the pressure difference calculator 61 is equal to or smaller than the second reference pressure difference ΔPb2 (pressure difference determination step S4a).

[0072] As in the first embodiment, the heating controller 70a outputs an ON instruction signal or an OFF instruction signal to the filter heating device 45 depending on the judgment results by the freezing condition judgement unit 64a and the judgment results by the pressure difference judgement unit 63a (heating control process S5).

[0073] As described above, in this embodiment, similar to the first embodiment, the filter heating device 45 is instructed to enter either a heated state or a non-heated state in accordance with the freezing condition parameters and the pressure difference. Therefore, in this embodiment as well, the consumption of heating energy for the filter 44 can be reduced.

[0074] Furthermore, in this embodiment, when the filter heating device 45 is in the heated state, the filter heating device 45 is put into the non-heated state on the condition that the pressure difference determiner 63a determines that the pressure difference is equal to or less than a second reference pressure difference ΔPb2, which is less strict than the first reference pressure difference ΔPb1. Therefore, in this embodiment, even if there is some fluctuation in the pressure difference, it is possible to avoid the heated state and the non-heated state being repeatedly switched within a short period of time.

[0075] Furthermore, in this embodiment, when the filter heating device 45 is in the heating state, the filter heating device 45 is switched to the non-heating state if the freezing condition determiner 64a determines that the temperature is equal to or higher than a second reference temperature Tb2, which is a condition that is less strict than the first reference temperature Tb1, or determines that the humidity is equal to or lower than a second reference humidity Hb2, which is a condition that is less strict than the first reference humidity Hb1. Therefore, in this embodiment, even if there are some temperature or humidity fluctuations, it is possible to avoid the filter heating device 45 from repeatedly switching between the heating state and the non-heating state within a short period of time.

[0076] "Third embodiment of anti-freeze control device and anti-freeze method" As shown in Figure 6, the anti-freeze control device 50b in this embodiment also has a freezing condition parameter detector 51b, a pressure differential meter 55, and a control device main body 60b, similar to the anti-freeze control devices 50 and 50a in the first and second embodiments.

[0077] The freezing condition parameter detector 51b of this embodiment differs from the freezing condition parameter detector 51 of the above-described embodiment in that it includes a mist amount meter 54 in addition to a thermometer 52 and a hygrometer 53. As shown in FIG. 1 , the mist amount meter 54 is provided in the intake duct main body 42 at a position Du upstream of the filter 44, and can detect the amount of mist in the outside air A at the position Du upstream of the filter 44 in the intake duct main body 42. There are various types of mist amount meters available for the mist amount meter 54, and any type of mist amount meter may be used. Examples of methods for detecting the amount of mist include a method in which a laser beam is irradiated onto the outside air A and the amount of mist is detected based on scattered light generated by the mist, and a method in which a baffle is disposed to block part of the flow path through which the outside air A flows and the amount of water dripping from the baffle is detected.

[0078] The control device main body 60b in this embodiment, like the control device main bodies 60 and 60a in the above embodiments, includes a pressure difference calculator 61, a flow rate calculator 62, a pressure difference determiner 63a, a freezing condition determiner 64b, and a heating controller 70a. The pressure difference calculator 61 and the flow rate calculator 62 in this embodiment are the same as the pressure difference calculator 61 and the flow rate calculator 62 in the above embodiments. The pressure difference determiner 63a in this embodiment is the same as the pressure difference determiner 63a in the second embodiment. Therefore, the pressure difference determiner 63a in this embodiment includes a first pressure difference determiner 63aa and a second pressure difference determiner 63ab. The heating controller 70a in this embodiment is the same as the heating controller 70a in the second embodiment. Therefore, the heating controller 70a in this embodiment includes an ON instruction signal generator 71, an OFF instruction signal generator 72a, and an instruction signal output unit 73, like the heating controller 70a in the second embodiment. The freezing condition determiner 64b in this embodiment is a determiner in which a mist amount determiner 67b is added to the freezing condition determiner 64a in the second embodiment.

[0079] The mist amount determiner 67b includes a first mist amount determiner 67ba and a second mist amount determiner 67bb. The first mist amount determiner 67ba determines whether the amount of mist detected by the mist amount meter 54 is greater than a predetermined first reference mist amount Mb1. The second mist amount determiner 67bb determines whether the amount of mist detected by the mist amount meter 54 is greater than a predetermined second reference mist amount Mb2. In other words, the second mist amount determiner 67bb determines whether the amount of mist detected by the mist amount meter 54 is equal to or less than the second reference mist amount Mb2. The second reference mist amount Mb2 is slightly less than the first reference mist amount Mb1.

[0080] In this embodiment, the first condition satisfaction determiner 68b determines that the freezing condition is met when the temperature detected by the thermometer 52 is less than the first reference temperature Tb1, the humidity detected by the hygrometer 53 is higher than the first reference humidity Hb1, and the amount of mist detected by the mist amount meter 54 is greater than the first reference mist amount Mb1. Therefore, like the first condition satisfaction determiner 68a in the second embodiment, the first condition satisfaction determiner 68b has an AND circuit. Furthermore, the second condition satisfaction determiner 69b determines that the freezing condition is not met when the temperature detected by the thermometer 52 is not less than the second reference temperature Tb2 (is equal to or greater than the second reference temperature Tb2), and / or the humidity detected by the hygrometer 53 is not higher than the second reference humidity Hb2 (is equal to or less than the second reference humidity Hb2), and / or the amount of mist detected by the mist amount meter 54 is not greater than the second reference mist amount Mb2 (is equal to or less than the second reference mist amount Mb2). Therefore, the second condition satisfaction judger 69b has an OR circuit, similar to the second condition satisfaction judger 69a in the second embodiment.

[0081] Next, the operation of the antifreeze control device 50b in this embodiment will be described with reference to the flowchart shown in FIG.

[0082] As in the above embodiment, the freezing condition parameter detector 51b detects a freezing condition parameter indicating whether or not ice may adhere to the filter 44 (freezing condition parameter detection step S1b). However, in this embodiment, the thermometer 52 detects the temperature of the outside air A, the hygrometer 53 detects the humidity in the outside air A, and the mist amount meter 54 detects the amount of mist in the outside air A.

[0083] The first pressure gauge 56 detects the pressure of the outside air A at a position Du upstream of the filter 44, and the second pressure gauge 57 detects the pressure of the outside air A at a position Dd downstream of the filter 44. The pressure difference calculator 61 calculates a pressure difference between the pressure detected by the first pressure gauge 56 and the pressure detected by the second pressure gauge 57 (pressure difference detection step S2).

[0084] The freezing condition determiner 64b determines whether the freezing condition parameters detected by the freezing condition parameter detector 51b satisfy the freezing conditions (freezing condition determination step S3b). Specifically, when the first temperature determiner 65aa of the freezing condition determiner 64b determines that the temperature detected by the thermometer 52 is lower than the first reference temperature Tb1, the first humidity determiner 66aa of the freezing condition determiner 64b determines that the humidity detected by the hygrometer 53 is higher than the first reference humidity Hb1, and the first mist amount determiner 67ba of the freezing condition determiner 64b determines that the mist amount detected by the mist amount meter 54 is greater than the first reference mist amount Mb1, the first condition satisfaction determiner 68b determines that the freezing conditions are satisfied. Furthermore, if the second temperature determiner 65ab determines that the temperature detected by the thermometer 52 is equal to or higher than the second reference temperature Tb2, and / or the second humidity determiner 66ab determines that the humidity detected by the hygrometer 53 is equal to or lower than the second reference humidity Hb2, and / or the second mist amount determiner 67bb determines that the amount of mist detected by the mist amount meter 54 is equal to or lower than the second reference mist amount Mb2, then the second condition satisfaction determiner 69b determines that the freezing condition is not satisfied.

[0085] The first pressure difference determiner 63aa determines a first reference pressure difference ΔPb1 according to the flow rate of outside air A calculated by the flow rate calculator 62, and then determines whether the pressure difference calculated by the pressure difference calculator 61 is greater than the first reference pressure difference ΔPb1. The second pressure difference determiner 63ab determines a second reference pressure difference ΔPb2 according to the flow rate of outside air A calculated by the flow rate calculator 62, and then determines whether the pressure difference calculated by the pressure difference calculator 61 is equal to or smaller than the second reference pressure difference ΔPb2 (pressure difference determination step S4a).

[0086] As in each of the above embodiments, the heating controller 70a outputs an ON instruction signal or an OFF instruction signal to the filter heating device 45 depending on the judgment results by the freezing condition judger 64b and the judgment results by the pressure difference judger 63a (heating control process S5).

[0087] As described above, in this embodiment, similarly to the first and second embodiments, the filter heating device 45 is instructed to enter either a heated state or a non-heated state in accordance with the freezing condition parameters and the pressure difference. Therefore, in this embodiment as well, the consumption of heating energy for the filter 44 can be reduced.

[0088] Furthermore, in this embodiment, as in the second embodiment, even if there are slight fluctuations in pressure difference, temperature, or humidity, it is possible to avoid the heating state and the non-heating state from being repeated within a short period of time.

[0089] In addition, in this embodiment, when determining whether the freezing conditions are met, the amount of mist is also taken into consideration in addition to the temperature and humidity, so that the present embodiment can recognize with a high probability that a relatively large amount of ice has adhered to the filter 44.

[0090] Furthermore, in this embodiment, when the filter heating device 45 is in the heated state, the filter heating device 45 is switched to the unheated state on the condition that the mist amount determiner 67b determines that the mist amount is equal to or less than a second reference mist amount Mb2, which is less strict than the first reference mist amount Mb1. Therefore, in this embodiment, even if there is some fluctuation in the mist amount, it is possible to avoid repeated switching between the heated state and the unheated state within a short period of time.

[0091] "Modification" The freezing condition parameter detector 51 in the first embodiment does not have the mist amount meter 54 of the freezing condition parameter detector 51b in the third embodiment. However, the freezing condition parameter detector 51 in the first embodiment may have the mist amount meter 54. In this case, the freezing condition determiner 64 of the control device main body 60 in the first embodiment has a mist amount determiner. This mist amount determiner determines whether the amount of mist detected by the mist amount meter 54 is greater than a predetermined reference mist amount.

[0092] The filter heating device 45 in the above embodiment includes a compressed air line 46 and a compressed air valve 47. However, the filter heating device may be any heating device that can heat the filter 44, and may be, for example, an electric heater that is arranged to surround the filter 44.

[0093] Furthermore, the present disclosure is not limited to the embodiments described above, and various additions, modifications, substitutions, partial deletions, etc. are possible within the scope of the conceptual idea and spirit of the present invention as derived from the content defined in the claims and their equivalents.

[0094] "Additional Notes" The antifreeze control devices 50, 50a, 50b in the above-described embodiments can be understood, for example, as follows.

[0095] (1) The anti-freeze control devices 50, 50a, 50b in the first aspect are applied to the following intake duct equipment 40. This intake duct equipment 40 includes an intake duct 41 having an intake port 42i capable of drawing in outside air A and an intake outlet 42o through which the outside air A drawn in from the intake port 42i flows out, a filter 44 arranged in the intake duct 41, and a filter heating device 45 capable of heating the filter 44. The anti-freeze control devices 50, 50a, 50b that control the filter heating device 45 include a freeze condition parameter detector 51, 51b that can detect a freeze condition parameter that indicates whether or not ice is likely to adhere to the filter 44, a pressure differential meter 55 that can detect the pressure difference within the intake duct 41 between the pressure on the upstream side Du, which is closer to the intake port 42i than the filter 44, and the pressure on the downstream side Dd, which is closer to the intake outlet 42o than the filter 44, and a control device main body 60, 60a, 60b that can instruct the filter heating device 45 to either a heating state in which the filter 44 is heated or a non-heating state in which the filter 44 is not heated, depending on the freeze condition parameter and the pressure difference.

[0096] For example, consider a case where the filter heating device 45 is instructed to enter either a heated state or a non-heated state based solely on the freezing condition parameter. Even if the outside air A flowing into the intake duct 41 satisfies the freezing condition parameter, there may be little ice on the actual filter 44. In this case, heating the filter 44 with the filter heating device 45 results in unnecessary consumption of heating energy. Furthermore, even if the outside air A flowing into the intake duct 41 no longer satisfies the freezing condition parameter, there may still be ice remaining on the filter 44 without completely melting. In this case, stopping the heating of the filter 44 with the filter heating device 45 results in unnecessary consumption of heating energy that had been consumed up until the heating was stopped.

[0097] Next, consider a case where either the heated state or the unheated state is indicated based solely on the pressure difference between the upstream side Du and the downstream side Dd of the filter 44. Dust may adhere to the filter 44, increasing the pressure difference. In this case, heating the filter 44 with the filter heating device 45 results in unnecessary consumption of heating energy. Furthermore, even if ice adhering to the filter 44 melts as a result of heating the filter 44 with the filter heating device 45, the freezing condition may still be satisfied. In this case, ice may begin to adhere to the filter 44 again, increasing the pressure difference. Therefore, the filter heating device 45 repeatedly heats and unheats the filter 44 in a short period of time, resulting in increased consumption of heating energy.

[0098] On the other hand, in this aspect, the filter heating device 45 is instructed to enter either a heated state or a non-heated state depending on the freezing condition parameters and the pressure difference. Therefore, in this aspect, the filter 44 can be heated when the freezing condition is met and the filter 44 is clogged with ice, resulting in a large pressure difference between the upstream side Du and the downstream side Dd of the filter 44. Also, in this aspect, heating of the filter 44 can be stopped when the freezing condition is not met and the filter 44 is barely clogged with ice, resulting in a small pressure difference between the upstream side Du and the downstream side Dd of the filter 44.

[0099] Therefore, in this embodiment, the filter heating device 45 can be put into a heated state at an appropriate time period and into a non-heated state at an appropriate time period, thereby reducing the consumption of heating energy for the filter 44.

[0100] (2) In the anti-freezing control device 50, 50a, 50b of the second aspect, in the anti-freezing control device 50, 50a, 50b of the first aspect, the freezing condition parameter detector 51, 51b has a thermometer 52 capable of detecting the temperature of the outside air A at a position Du upstream of the filter 44, and a hygrometer 53 capable of detecting the humidity of the outside air A at a position Du upstream of the filter 44. The freezing condition parameters include the temperature of the outside air A and the humidity of the outside air A. The control device main body 60, 60a, 60b includes a freezing condition determiner 64, 64a, 64b that determines whether the freezing condition parameters satisfy a freezing condition that may cause ice to adhere to the filter 44, a pressure difference determiner 63, 63a that determines whether the pressure difference is greater than a reference pressure difference ΔPb, and a heating controller 70, 70a that instructs the filter heating device 45 to enter the heated state or the non-heated state based on the determination results of the freezing condition determiner 64, 64a, 64b and the pressure difference determiner 63, 63a. The freezing condition determiner 64, 64a, 64b determines that the freezing condition is satisfied when the temperature detected by the thermometer 52 is less than a predetermined reference temperature Tb based on a dew point temperature and the humidity detected by the hygrometer 53 is higher than a predetermined reference humidity Hb based on 100% humidity. When the filter heating device 45 is in the non-heating state, if the freezing condition determiners 64, 64a, 64b determine that the freezing condition is satisfied and the pressure difference determiner 63, 63a determines that the pressure difference is greater than the reference pressure difference ΔPb, the heating controller 70, 70a instructs the filter heating device 45 to enter the heating state. When the filter heating device 45 is in the heating state, if the freezing condition determiners 64, 64a, 64b determine that the freezing condition is not satisfied and the pressure difference determiner 63, 63a determine that the pressure difference is equal to or less than the reference pressure difference ΔPb, the heating controller 70, 70a instructs the filter heating device 45 to enter the non-heating state.

[0101] For ice to adhere to the filter 44, supercooled mist must be present in the outside air A. In other words, for the freezing condition to be met, the outside air temperature must be below the dew point, i.e., below 0°C, and the humidity in the outside air A must be 100%. In this embodiment, the freezing condition under which ice can adhere to the filter 44 is met when the temperature detected by the thermometer 52 is below a predetermined reference temperature Tb based on the dew point temperature, and the humidity detected by the hygrometer 53 is higher than a predetermined reference humidity Hb based on 100% humidity. Therefore, in this embodiment, it is possible to recognize with a high probability that ice will adhere to the filter 44.

[0102] (3) In the anti-freeze control devices 50a, 50b of the third aspect, in the anti-freeze control devices 50a, 50b of the second aspect, the reference temperature Tb has a first reference temperature Tb1 and a second reference temperature Tb2 that is higher than the first reference temperature Tb1. The reference humidity Hb has a first reference humidity Hb1 and a second reference humidity Hb2 that is lower than the first reference humidity Hb1. The freezing condition determinators 64a, 64b determine that the freezing condition is satisfied when the temperature detected by the thermometer 52 is lower than the first reference temperature Tb1 and the humidity detected by the hygrometer 53 is higher than the first reference humidity Hb1 when the filter heating device 45 is in the non-heating state. The freezing condition determiners 64a, 64b determine that the freezing conditions are not met when the temperature detected by the thermometer 52 is equal to or higher than the second reference temperature Tb2 or when the humidity detected by the hygrometer 53 is equal to or lower than the second reference humidity Hb2 when the filter heating device 45 is in the heated state.

[0103] In this aspect, when the filter heating device 45 is in the heating state, the filter heating device 45 is switched to the non-heating state under the condition that the freezing condition determiners 64a, 64b determine that the temperature is equal to or higher than a second reference temperature Tb2, which is a condition less strict than the first reference temperature Tb1, or that the humidity is equal to or lower than a second reference humidity Hb2, which is a condition less strict than the first reference humidity Hb1. Therefore, in this aspect, even if there are some temperature or humidity fluctuations, it is possible to avoid the filter heating device 45 from repeatedly switching between the heating state and the non-heating state within a short period of time.

[0104] (4) In a fourth aspect of the anti-freezing control device 50b, in the anti-freezing control device 50b of the second aspect, the freezing condition parameter detector 51b has a mist amount meter 54 capable of detecting the amount of mist in the outside air A. The freezing condition parameter includes the amount of mist in the outside air A. The freezing condition determiner 64b determines that the freezing condition is met when the temperature detected by the thermometer 52 is lower than the reference temperature Tb, the humidity detected by the hygrometer 53 is higher than the reference humidity Hb, and the amount of mist detected by the mist amount meter 54 is greater than a predetermined reference mist amount.

[0105] In this embodiment, the amount of mist is also taken into consideration in addition to temperature and humidity when determining whether the freezing conditions are met, so that it is possible to recognize with a high probability that a relatively large amount of ice will adhere to the filter 44.

[0106] (5) In a fifth aspect of the anti-freeze control device 50b, in the anti-freeze control device 50b of the fourth aspect, the reference temperature Tb includes a first reference temperature Tb1 and a second reference temperature Tb2 that is higher than the first reference temperature Tb1. The reference humidity Hb includes a first reference humidity Hb1 and a second reference humidity Hb2 that is lower than the first reference humidity Hb1. The reference mist amount includes a first reference mist amount Mb1 and a second reference mist amount Mb2 that is lower than the first reference mist amount Mb1. The freezing condition determinator 64b determines that the freezing condition is met when, when the filter heating device 45 is in the non-heating state, the temperature detected by the thermometer 52 is lower than the first reference temperature Tb1, the humidity detected by the hygrometer 53 is higher than the first reference humidity Hb1, and the amount of mist detected by the mist amount meter 54 is greater than the first reference mist amount Mb1. The freezing condition determiner 64b determines that the freezing condition is not met when the filter heating device 45 is in the heated state and the temperature detected by the thermometer 52 is equal to or higher than the second reference temperature Tb2, the humidity detected by the hygrometer 53 is equal to or lower than the second reference humidity Hb2, or the amount of mist detected by the mist amount meter 54 is equal to or lower than the second reference mist amount Mb2.

[0107] In this embodiment, when the filter heating device 45 is in the heated state, the filter heating device 45 is switched to the non-heated state on the condition that the mist amount determiner 67b determines that the mist amount is equal to or less than a second reference mist amount Mb2, which is less strict than the first reference mist amount Mb1. Therefore, in this embodiment, even if there is some fluctuation in the mist amount, it is possible to avoid repeated switching between the heated state and the non-heated state within a short period of time.

[0108] (6) In the sixth aspect of the anti-freeze control device 50, 50a, 50b, in any one of the second to fifth aspects, the pressure difference determiner 63, 63a maintains a relationship Fx between the flow rate of outside air A flowing through the intake duct 41 and the reference pressure difference ΔPb, and uses the relationship Fx to determine the reference pressure difference ΔPb according to the flow rate of outside air A flowing through the intake duct 41.

[0109] (7) In a seventh aspect, the anti-freeze control device 50a, 50b is the anti-freeze control device 50a, 50b of any one of the second to fifth aspects, wherein the reference pressure difference ΔPb has a first reference pressure difference ΔPb1 and a second reference pressure difference ΔPb2 smaller than the first reference pressure difference ΔPb1. The pressure difference determiner 63a determines whether the temperature detected by the thermometer 52 is less than the first reference pressure difference ΔPb1 when the filter heating device 45 is in the non-heating state. The pressure difference determiner 63a determines whether the temperature detected by the thermometer 52 is less than the second reference pressure difference ΔPb2 when the filter heating device 45 is in the heating state. When the filter heating device 45 is in the non-heating state, if the freezing condition determiners 64a, 64b determine that the freezing condition is satisfied and the pressure difference determiner 63a determines that the pressure difference is greater than the first reference pressure difference ΔPb1, the heating controller 70a instructs the filter heating device 45 to enter the heating state. When the filter heating device 45 is in the heating state, if the freezing condition determiners 64a, 64b determine that the freezing condition is not satisfied and the pressure difference determiner 63a determines that the pressure difference is equal to or less than the second reference pressure difference ΔPb2, the heating controller 70a instructs the filter heating device 45 to enter the non-heating state.

[0110] In this aspect, when the filter heating device 45 is in the heated state, the filter heating device 45 is put into the non-heated state on the condition that the pressure difference determiner 63a determines that the pressure difference is equal to or less than a second reference pressure difference ΔPb2, which is less strict than the first reference pressure difference ΔPb1. Therefore, in this aspect, even if there is some fluctuation in the pressure difference, it is possible to avoid the heated state and the non-heated state being repeatedly switched within a short period of time.

[0111] The intake duct equipment 40 in the above embodiments can be understood, for example, as follows: (8) The intake duct equipment 40 in an eighth aspect includes the anti-freeze control device 50, 50a, 50b in any one of the second to fifth aspects, the intake duct 41, the filter 44, and the filter heating device 45.

[0112] The gas turbine equipment in the above embodiments can be understood as follows, for example. (9) A gas turbine equipment in a ninth aspect includes the intake duct equipment 40 of the ninth aspect and a gas turbine GT. The gas turbine GT includes a compressor 10 capable of compressing outside air A from the intake duct 41 to generate compressed air Acom, a combustor 20 capable of burning fuel F in the compressed air Acom to generate combustion gas, and a turbine 30 capable of being driven by the combustion gas. The filter heating device 45 includes a compressed air line 46 capable of guiding a portion of the compressed air Acom generated by the compressor 10 to the upstream side Du from the filter 44 in the intake duct 41, and a compressed air valve 47 provided in the compressed air line 46. The control device main body 60, 60a, 60b issues an open command to the compressed air valve 47 as an instruction for the heated state, and issues a close command to the compressed air valve 47 as an instruction for the non-heated state.

[0113] The anti-freezing methods in the above embodiments can be understood, for example, as follows: (10) A freezing prevention method in a tenth aspect is applied to the following air intake duct equipment 40. This air intake duct equipment 40 includes an air intake duct 41 having an air intake port 42i capable of drawing in outside air A and an air intake outlet 42o through which the outside air A drawn in from the air intake port 42i flows out, a filter 44 arranged in the air intake duct 41, and a filter heating device 45 capable of heating the filter 44. The anti-freezing method for suppressing freezing of the filter 44 includes the following steps: a freezing condition parameter detection step S1, S1b for detecting a freezing condition parameter indicating whether or not ice is likely to adhere to the filter 44; a pressure difference detection step S2 for detecting the pressure difference within the intake duct 41 between the pressure on the upstream side Du, which is closer to the intake port 42i than the filter 44, and the pressure on the downstream side Dd, which is closer to the intake outlet 42o than the filter 44; and a control step for instructing the filter heating device 45 to select one of a heating state in which the filter 44 is heated and a non-heating state in which the filter 44 is not heated, depending on the freezing condition parameter and the pressure difference.

[0114] In this embodiment, similarly to the first embodiment, the consumption of heating energy for the filter 44 can be reduced.

[0115] (11) In an eleventh aspect, in the antifreeze method of the tenth aspect, the freezing condition parameter detection steps S1 and S1b detect, as the freezing condition parameters, the temperature and humidity of the outside air A at a position Du upstream of the filter 44. The control step includes freezing condition determination steps S3, S3a, and S3b for determining whether the freezing condition parameters satisfy a freezing condition that may cause ice to adhere to the filter 44, a pressure difference determination step S4 and S4a for determining whether the pressure difference is greater than a reference pressure difference ΔPb, and a heating control step S5 for instructing the filter heating device 45 to enter the heated state or the non-heated state depending on the determination results in the freezing condition determination steps S3, S3a, and S3b and the pressure difference determination step S4 and S4a. In the freezing condition determination steps S3, S3a, and S3b, it is determined that the freezing condition is satisfied if the temperature detected in the freezing condition parameter detection steps S1 and S1b is lower than a predetermined reference temperature Tb based on a dew point temperature and the humidity detected in the freezing condition parameter detection steps S1 and S1b is higher than a predetermined reference humidity Hb based on 100% humidity. In the heating control step S5, when the filter heating device 45 is in the non-heating state, if it is determined that the freezing condition is satisfied in the freezing condition determination steps S3, S3a, and S3b and it is determined that the pressure difference is larger than a reference pressure difference ΔPb in the pressure difference determination steps S4 and S4a, the filter heating device 45 is instructed to switch to the heating state. In addition, in the heating control step S5, when the filter heating device 45 is in the heated state, if it is determined in the freezing condition determination steps S3, S3a, S3b that the freezing conditions are not met and it is determined in the pressure difference determination steps S4, S4a that the pressure difference is less than or equal to the reference pressure difference ΔPb, the filter heating device 45 is instructed to enter the non-heated state.

[0116] In this embodiment, as in the second embodiment, adhesion of ice to the filter 44 can be recognized with a high probability.

[0117] (12) In a twelfth aspect, in the anti-freezing method of the eleventh aspect, the reference temperature Tb has a first reference temperature Tb1 and a second reference temperature Tb2 that is higher than the first reference temperature Tb1. The reference humidity Hb has a first reference humidity Hb1 and a second reference humidity Hb2 that is lower than the first reference humidity Hb1. In the freezing condition determination steps S3a and S3b, when the filter heating device 45 is in the non-heating state, it is determined that the freezing condition is satisfied if the temperature detected in the freezing condition parameter detection steps S1 and S1b is lower than the first reference temperature Tb1 and the humidity detected in the freezing condition parameter detection steps S1 and S1b is higher than the first reference humidity Hb1. In addition, in the freezing condition judgment steps S3a and S3b, when the filter heating device 45 is in the heated state, it is judged that the freezing conditions are not met if the temperature detected in the freezing condition parameter detection steps S1 and S1b is equal to or higher than the second reference temperature Tb2, or if the humidity detected in the freezing condition parameter detection steps S1 and S1b is equal to or lower than the second reference humidity Hb2.

[0118] In this embodiment, as in the third embodiment, even if there are some temperature or humidity fluctuations, it is possible to prevent the heated state and the unheated state from being repeatedly changed within a short period of time.

[0119] (13) In a thirteenth aspect, in the antifreeze method of the eleventh aspect, the freezing condition parameter detection step S1b detects an amount of mist in the outside air A as the freezing condition parameter. In the freezing condition determination step S3b, it is determined that the freezing condition is satisfied when the temperature detected in the freezing condition parameter detection step S1b is lower than the reference temperature Tb, the humidity detected in the freezing condition parameter detection step S1b is higher than the reference humidity Hb, and the amount of mist detected in the freezing condition parameter detection step S1b is greater than a predetermined reference mist amount.

[0120] In this embodiment, similar to the fourth embodiment, it is possible to recognize with a high probability that a relatively large amount of ice has adhered to the filter 44.

[0121] (14) A fourteenth aspect of the anti-freezing method is the anti-freezing method of the thirteenth aspect, wherein the reference temperature Tb includes a first reference temperature Tb1 and a second reference temperature Tb2 that is higher than the first reference temperature Tb1. The reference humidity Hb includes a first reference humidity Hb1 and a second reference humidity Hb2 that is lower than the first reference humidity Hb1. The reference mist amount includes a first reference mist amount Mb1 and a second reference mist amount Mb2 that is lower than the first reference mist amount Mb1. In the freezing condition determination step S3b, when the filter heating device 45 is in the non-heating state, it is determined that the freezing condition is satisfied if the temperature detected in the freezing condition parameter detection step S1b is lower than the first reference temperature Tb1, the humidity detected in the freezing condition parameter detection step S1b is higher than the first reference humidity Hb1, and the mist amount detected in the freezing condition parameter detection step S1b is greater than the first reference mist amount Mb1. In addition, in the freezing condition judgment process S3b, when the filter heating device 45 is in the heated state, it is judged that the freezing conditions are not met if the temperature detected in the freezing condition parameter detection process S1b is higher than the second standard temperature Tb2, the humidity detected in the freezing condition parameter detection process S1b is lower than the second standard humidity Hb2, or the amount of mist detected in the freezing condition parameter detection process S1b is lower than the second standard mist amount Mb2.

[0122] In this aspect, as in the fifth aspect, even if there is some fluctuation in the amount of mist, it is possible to avoid the heating state and the non-heating state from being repeated in a short period of time.

[0123] (15) In the anti-freezing method of the fifteenth aspect, in the anti-freezing methods of the eleventh to fourteenth aspects, in the pressure difference determination steps S4 and S4a, the reference pressure difference ΔPb corresponding to the flow rate of the outside air A flowing through the intake duct 41 is determined using the relationship Fx between the flow rate of the outside air A flowing through the intake duct 41 and the reference pressure difference ΔPb.

[0124] (16) In a sixteenth aspect, in the antifreeze method according to any one of the eleventh to fifteenth aspects, the reference pressure difference ΔPb includes a first reference pressure difference ΔPb1 and a second reference pressure difference ΔPb2 that is smaller than the first reference pressure difference ΔPb1. In the pressure difference determination step S4a, when the filter heating device 45 is in the non-heating state, it is determined whether the temperature detected in the freezing condition parameter detection steps S1 and S1b is less than the first reference pressure difference ΔPb1. In addition, in the pressure difference determination step S4a, when the filter heating device 45 is in the heating state, it is determined whether the temperature detected in the freezing condition parameter detection steps S1 and S1b is less than the second reference pressure difference ΔPb2. In the heating control step S5, when the filter heating device 45 is in the non-heating state, if it is determined in the freezing condition determination steps S3a and S3b that the freezing condition is satisfied and it is determined in the pressure difference determination step S4a that the pressure difference is greater than the first reference pressure difference ΔPb1, the heating control step S5 instructs the filter heating device 45 to enter the heated state. Also, in the heating control step S5, when the filter heating device 45 is in the heating state, if it is determined in the freezing condition determination steps S3a and S3b that the freezing condition is not satisfied and it is determined in the pressure difference determination step S4a that the pressure difference is equal to or less than the second reference pressure difference ΔPb2, the non-heating state is instructed to the filter heating device 45.

[0125] In this aspect, similar to the seventh aspect, even if there is some fluctuation in the pressure difference, it is possible to prevent the heated state and the unheated state from being repeated in a short period of time.

[0126] According to one aspect of the present disclosure, it is possible to reduce the consumption of heating energy for a filter disposed in an intake duct.

[0127] GT: Gas turbine 1: Gas turbine rotor 10: Compressor 11: Compressor rotor 11s: Compressor rotor shaft 11b: Compressor rotor blade row 12: Compressor casing 13: Compressor stator blade row 14: Intake air amount regulator 14v: Inlet guide vane 14d: Driver 15: Intake casing 25: Intermediate casing 30: Turbine 31: Turbine rotor 31s: Turbine rotor shaft 31b: Turbine rotor blade row 32: Turbine casing 33: Turbine stator blade row 35: Exhaust casing 39: Chimney 40: Intake duct equipment 41: Intake duct 42: Intake duct body 42i: Intake port 42o: Intake outlet 43: Louver 44: Filter 45: Filter heater 46: Compressed air line 47: Compressed air valve 50, 50a, 50b: Anti-freeze control device 51, 51b: Freezing condition parameter detector 52: Thermometer 53: Hygrometer 54: Mist amount meter 55: Pressure difference meter 56: First pressure gauge 57: Second pressure gauge 58: Third pressure gauge 59: Downstream thermometer 60, 60a, 60b: Control device main body 61: Pressure difference calculator 62: Flow rate calculator 63, 63a: Pressure difference determiner 63aa: First pressure difference determiner 63ab: Second pressure difference determiner 64, 64a, 64b: Freezing condition determiner 65, 65a: Temperature determiner 65aa: First temperature determiner 65ab: Second temperature determiner 66, 66a: Humidity determiner 66aa: First humidity determiner 66ab: Second humidity determiner 67b: Mist amount determiner 67ba: First mist amount determiner 67bb: Second mist amount determiner 68: Condition satisfaction determiner 68a, 68b: First condition satisfaction determiner 69a, 69b: Second condition satisfaction determiner 70, 70a: Heating controller 71: ON instruction signal generator 72, 72a: OFF instruction signal generator 73: Instruction signal output device A: Outside air Acom: Compressed air F: Fuel Tb: Reference temperature Tb1: First reference temperature Tb2: Second reference temperature Hb: Reference humidity Hb1: First reference humidity Hb2: Second reference humidity Mb1: First reference mist amount Mb2: Second reference mist amount ΔPb: Reference pressure difference ΔPb1: First reference pressure difference ΔPb2: Second reference pressure difference Ar: Axis Da: Axial direction Dau: Axial upstream side Dad: Axial downstream side Dc: Circumferential direction Dr: Radial direction Dri: Radial inner side Dro: radially outer side Du: upstream side Dd: downstream side

Claims

1. An anti-freeze control device for an air intake duct facility comprising: an air intake duct having an air intake port capable of drawing in outside air and an air intake outlet through which the outside air drawn in from the air intake port flows out; a filter disposed in the air intake duct; and a filter heating device capable of heating the filter, the anti-freeze control device controlling the filter heating device comprising: a freeze condition parameter detector capable of detecting a freeze condition parameter indicating whether or not the filter is in a state in which ice may adhere to it; a pressure differential meter capable of detecting a pressure difference between the pressure on the upstream side of the filter, which is closer to the air intake port, within the air intake duct, and the pressure on the downstream side of the filter, which is closer to the air intake outlet; and a control device main body capable of instructing the filter heating device to select one of two states, a heating state in which the filter is heated, and a non-heating state in which the filter is not heated, depending on the freeze condition parameter and the pressure difference.

2. In the freeze prevention control device according to claim 1, the freeze condition parameter detector comprises a thermometer capable of detecting the temperature of the outside air at a position upstream of the filter, and a hygrometer capable of detecting the humidity of the outside air at a position upstream of the filter, and the freeze condition parameters include the temperature of the outside air and the humidity of the outside air, and the control device main body comprises: a freeze condition determiner that determines whether the freeze condition parameters satisfy a freeze condition under which ice may adhere to the filter, a pressure difference determiner that determines whether the pressure difference is greater than a reference pressure difference, and a heating controller that instructs the filter heating device to enter the heated state or the non-heated state depending on the determination results of the freeze condition determiner and the pressure difference determiner, and the freeze condition determiner determines that the freeze conditions are satisfied on the condition that the temperature detected by the thermometer is less than a predetermined reference temperature based on a dew point temperature and the humidity detected by the hygrometer is higher than a predetermined reference humidity based on a humidity of 100%, and the heating controller a freeze prevention control device which, when the filter heating device is in the non-heating state, instructs the filter heating device to the heated state if the freezing condition determiner determines that the freezing condition is satisfied and the pressure difference determiner determines that the pressure difference is greater than a reference pressure difference, and when the filter heating device is in the heated state, instructs the filter heating device to the non-heating state if the freezing condition determiner determines that the freezing condition is not satisfied and the pressure difference determiner determines that the pressure difference is equal to or less than a reference pressure difference.

3. A freeze prevention control device as described in claim 2, wherein the reference temperatures have a first reference temperature and a second reference temperature higher than the first reference temperature, and the reference humidity has a first reference humidity and a second reference humidity lower than the first reference humidity, and the freeze condition determiner determines that the freeze condition is satisfied when the temperature detected by the thermometer is lower than the first reference temperature and the humidity detected by the hygrometer is higher than the first reference humidity when the filter heating device is in the non-heating state, and determines that the freeze condition is not satisfied when the temperature detected by the thermometer is equal to or higher than the second reference temperature or the humidity detected by the hygrometer is equal to or lower than the second reference humidity when the filter heating device is in the heating state.

4. An anti-freeze control device as described in claim 2, wherein the freezing condition parameter detector has a mist amount meter capable of detecting the amount of mist in the outside air, the freezing condition parameter includes the amount of mist in the outside air, and the freezing condition determiner determines that the freezing conditions are met when the temperature detected by the thermometer is lower than the reference temperature, the humidity detected by the hygrometer is higher than the reference humidity, and the amount of mist detected by the mist amount meter is greater than a predetermined reference mist amount.

5. An anti-freeze control device as described in claim 4, wherein the reference temperatures have a first reference temperature and a second reference temperature higher than the first reference temperature, the reference humidity has a first reference humidity and a second reference humidity lower than the first reference humidity, and the reference mist amount has a first reference mist amount and a second reference mist amount less than the first reference mist amount, and the freeze condition determiner determines that the freeze condition is met when the temperature detected by the thermometer is less than the first reference temperature, the humidity detected by the hygrometer is higher than the first reference humidity, and the amount of mist detected by the mist amount meter is greater than the first reference mist amount, when the filter heating device is in the non-heating state, and determines that the freeze condition is not met when the temperature detected by the thermometer is equal to or higher than the second reference temperature, the humidity detected by the hygrometer is equal to or lower than the second reference humidity, or the amount of mist detected by the mist amount meter is equal to or lower than the second reference mist amount, when the filter heating device is in the heated state.

6. An anti-freeze control device as described in claim 2, wherein the pressure difference determiner maintains a relationship between the flow rate of outside air flowing through the intake duct and the reference pressure difference, and uses the relationship to determine the reference pressure difference according to the flow rate of outside air flowing through the intake duct.

7. A freeze prevention control device as described in claim 2, wherein the reference pressure difference has a first reference pressure difference and a second reference pressure difference smaller than the first reference pressure difference, and the pressure difference determiner determines whether or not the temperature detected by the thermometer is less than the first reference pressure difference when the filter heating device is in the non-heating state, and determines whether or not the temperature detected by the thermometer is less than the second reference pressure difference when the filter heating device is in the heated state, and the heating controller instructs the filter heating device to switch to the heated state when the freezing condition determiner determines that the freezing condition is satisfied and the pressure difference determiner determines that the pressure difference is greater than the first reference pressure difference when the filter heating device is in the non-heating state, and instructs the filter heating device to switch to the non-heating state when the freezing condition determiner determines that the freezing condition is not satisfied and the pressure difference determiner determines that the pressure difference is equal to or less than the second reference pressure difference when the filter heating device is in the heated state.

8. An air intake duct installation comprising: an anti-freeze control device according to any one of claims 1 to 7; the air intake duct; the filter; and the filter heating device.

9. Gas turbine equipment comprising: an intake duct facility as defined in claim 8; and a gas turbine, wherein the gas turbine comprises a compressor capable of compressing outside air from the intake duct to generate compressed air, a combustor capable of burning fuel in the compressed air to generate combustion gas, and a turbine capable of being driven by the combustion gas, wherein the filter heating device has a compressed air line capable of directing a portion of the compressed air generated by the compressor to the upstream side of the filter in the intake duct, and a compressed air valve provided in the compressed air line, and wherein the control device main body issues an open command to the compressed air valve as an instruction for the heated state, and issues a close command to the compressed air valve as an instruction for the non-heated state.

10. An anti-freezing method for suppressing freezing of an air intake duct facility comprising an air intake duct having an air intake port capable of drawing in outside air and an air intake outlet through which the outside air drawn in from the air intake port flows out, a filter arranged in the air intake duct, and a filter heating device capable of heating the filter, the anti-freezing method executing the following steps: a freezing condition parameter detection step of detecting a freezing condition parameter indicating whether or not the filter is in a state in which ice may adhere; a pressure difference detection step of detecting a pressure difference within the air intake duct between the pressure on the upstream side, which is closer to the air intake port than the filter, and the pressure on the downstream side, which is closer to the air intake outlet than the filter; and a control step of instructing the filter heating device to select one of a heating state in which the filter is heated and a non-heating state in which the filter is not heated, depending on the freezing condition parameter and the pressure difference.

11. A freeze prevention method according to claim 10, wherein the freezing condition parameter detection step detects the temperature and humidity of the outside air at a position upstream of the filter as the freezing condition parameters, and the control step includes a freezing condition judgment step of judging whether the freezing condition parameters satisfy the freezing conditions under which ice may adhere to the filter, a pressure difference judgment step of judging whether the pressure difference is greater than a reference pressure difference, and a heating control step of instructing the filter heating device to switch to the heated state or the non-heated state depending on the judgment results of the freezing condition judgment step and the judgment results of the pressure difference judgment step, wherein the freezing condition judgment step judges that the freezing conditions are satisfied under the condition that the temperature detected in the freezing condition parameter detection step is less than a predetermined reference temperature based on a dew point temperature and the humidity detected in the freezing condition parameter detection step is higher than a predetermined reference humidity based on a humidity of 100%, and wherein the heating control step a freeze prevention method comprising: when the filter heating device is in the non-heated state, if it is determined in the freezing condition determination step that the freezing condition is satisfied and the pressure difference is determined in the pressure difference determination step that the pressure difference is greater than a reference pressure difference, instructing the filter heating device to the heated state; and when the filter heating device is in the heated state, if it is determined in the freezing condition determination step that the freezing condition is not satisfied and the pressure difference is determined in the pressure difference determination step that the pressure difference is equal to or less than a reference pressure difference, instructing the filter heating device to the non-heated state.

12. A freeze prevention method as described in claim 11, wherein the reference temperatures have a first reference temperature and a second reference temperature higher than the first reference temperature, and the reference humidity has a first reference humidity and a second reference humidity lower than the first reference humidity, and the freeze condition determination step determines that the freeze condition is satisfied when the temperature detected in the freeze condition parameter detection step is lower than the first reference temperature and the humidity detected in the freeze condition parameter detection step is higher than the first reference humidity when the filter heating device is in the non-heating state, and determines that the freeze condition is not satisfied when the temperature detected in the freeze condition parameter detection step is equal to or higher than the second reference temperature or the humidity detected in the freeze condition parameter detection step is equal to or lower than the second reference humidity when the filter heating device is in the heated state.

13. An anti-freezing method as described in claim 11, wherein in the freezing condition parameter detection process, the amount of mist in the outside air is detected as the freezing condition parameter, and in the freezing condition judgment process, it is judged that the freezing condition is satisfied when the temperature detected in the freezing condition parameter detection process is lower than the reference temperature, the humidity detected in the freezing condition parameter detection process is higher than the reference humidity, and the amount of mist detected in the freezing condition parameter detection process is greater than a predetermined reference mist amount.

14. A freeze prevention method according to claim 13, wherein the reference temperature has a first reference temperature and a second reference temperature higher than the first reference temperature, the reference humidity has a first reference humidity and a second reference humidity lower than the first reference humidity, and the reference mist amount has a first reference mist amount and a second reference mist amount less than the first reference mist amount, and in the freeze condition determination step, when the filter heating device is in the non-heating state, the temperature detected in the freeze condition parameter detection step is lower than the first reference temperature, the humidity detected in the freeze condition parameter detection step is higher than the first reference humidity, and the mist amount detected in the freeze condition parameter detection step is greater than the first reference mist amount, the freeze condition is determined to be satisfied. a freezing prevention method, in which, when the filter heating device is in the heated state, it is determined that the freezing conditions are not satisfied if the temperature detected in the freezing condition parameter detection process is equal to or higher than the second reference temperature, the humidity detected in the freezing condition parameter detection process is equal to or lower than the second reference humidity, or the amount of mist detected in the freezing condition parameter detection process is equal to or lower than the second reference mist amount.

15. An anti-freezing method according to claim 11, wherein in the pressure difference determination step, the reference pressure difference corresponding to the flow rate of outside air flowing through the intake duct is determined using the relationship between the flow rate of outside air flowing through the intake duct and the reference pressure difference.

16. A freeze prevention method according to any one of claims 11 to 15, wherein the reference pressure difference has a first reference pressure difference and a second reference pressure difference smaller than the first reference pressure difference, and in the pressure difference determination step, when the filter heating device is in the non-heated state, it is determined whether or not the temperature detected in the freezing condition parameter detection step is less than the first reference pressure difference, and when the filter heating device is in the heated state, it is determined whether or not the temperature detected in the freezing condition parameter detection step is less than the second reference pressure difference, and in the heating control step, when the filter heating device is in the non-heated state, it is determined that the freezing condition is satisfied in the freezing condition determination step and the pressure difference is determined to be greater than the first reference pressure difference, the heating control step instructs the filter heating device to be in the heated state, and when the filter heating device is in the heated state, it is determined that the freezing condition is not satisfied in the freezing condition determination step and the pressure difference is determined to be equal to or less than the second reference pressure difference, the heating control step instructs the filter heating device to be in the non-heated state. How to prevent freezing.

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