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

Abstract

To suppress consumption of heating energy of a filter disposed within an air intake duct.SOLUTION: A freezing prevention control device includes: a freezing condition parameter detector capable of detecting a freezing condition parameter indicating whether or not a state where ice can adhere to a filter in an air intake duct occurs; a differential pressure gauge capable of detecting a differential pressure that is a difference between pressure upstream of the filter and pressure downstream of the filter in the air intake duct; and a control device body capable of indicating one state of a heating state for heating the filter and a non-heating state for preventing the heating of the filter relative to a filter heating device capable of heating the filter in accordance with the freezing condition parameter and the differential pressure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a technique for suppressing freezing of a filter disposed in an intake duct.

Background Art

[0002] As intake duct facilities for introducing outside air into a gas turbine or the like, for example, there is a facility disclosed in Patent Document 1 below. This facility includes an intake duct, a filter disposed in the intake duct, and a filter heating device for heating the filter. The temperature of the outside air flowing into the intake duct is detected by a thermometer. Also, the humidity of the outside air flowing into the intake duct is detected by a hygrometer. When the temperature of the outside air flowing into the intake duct becomes less than the dew point temperature and the humidity of this outside air becomes a predetermined humidity, the filter heating device guides hot air to the upstream side of the filter to heat the filter. Further, when the temperature of the outside air detected by this thermometer becomes equal to or higher than the dew point temperature, the filter heating device stops heating the filter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1 above, as described above, when the temperature of the outside air flowing into the intake duct becomes less than the dew point temperature and the humidity of this outside air becomes a predetermined humidity, the filter is heated by the filter heating device. However, even when the temperature of the outside air flowing into the intake duct becomes less than the dew point temperature and the humidity of this outside air becomes a predetermined humidity, there may be a case where almost no ice adheres to the actual filter. In this case, heating the filter by the filter heating device would consume heating energy wastefully.

[0005] Also, in the technology described in Patent Document 1 above, as described above, when the temperature of the outside air flowing into the intake duct becomes equal to or higher than the dew point temperature, the heating of the filter by the filter heating device is stopped. However, even when the temperature of the outside air flowing into the intake duct becomes equal to or higher than the dew point temperature, the ice adhering to the filter may not completely melt and may still remain. In this case, if the heating of the filter by the filter heating device is stopped, the heating energy consumed until immediately before the heating stop becomes wasted.

[0006] Therefore, an object of the present disclosure is to provide a technology capable of suppressing the consumption of heating energy for the filter.

Means for Solving the Problems

[0007] The anti-freezing control device as one aspect for achieving the above object is applied to the following intake duct facility. This intake duct facility includes an intake duct having an air intake port capable of sucking outside air and an air intake outlet through which the outside air sucked from the air intake port flows out, a filter disposed in the intake duct, and a filter heating device capable of heating the filter. The anti-freezing control device that controls the filter heating device includes a freezing condition parameter detector capable of detecting a freezing condition parameter indicating whether ice can adhere to the filter, a pressure difference meter capable of detecting a pressure difference that is the difference between the pressure on the upstream side, which is on the side of the air intake port rather than the filter, and the pressure on the downstream side, which is on the side of the air intake outlet rather than the filter, in the intake duct, and a control device main body capable of instructing, according to the freezing condition parameter and the pressure difference, one of a heating state of heating the filter and a non-heating state of not heating the filter to the filter heating device.

[0008] For example, consider the case where, depending only on the freezing condition parameters, one of the heating state and the non-heating state is indicated for the filter heating device. Even if the outside air flowing into the intake duct satisfies the freezing condition parameters, there may be little icing on the actual filter. In this case, if the filter is heated by the filter heating device, heating energy will be wasted. Also, even if the outside air flowing into the intake duct no longer satisfies the freezing condition parameters, there may be ice remaining on the filter without completely melting. In this case, if the heating of the filter by the filter heating device is stopped, the heating energy consumed until just before the heating stop will be wasted.

[0009] Next, consider the case where, depending only on the pressure difference between the upstream side and the downstream side of the filter, one of the heating state and the non-heating state is indicated. There may be a case where dust adheres to the filter and the pressure difference increases. In this case, if the filter is heated by the filter heating device, heating energy will be wasted. Also, as a result of heating the filter by the filter heating device, even if the ice adhering to the filter melts, there may still be cases where the freezing conditions are satisfied. In this case, ice starts to adhere to the filter again and the pressure difference increases. For this reason, the heating and non-heating of the filter by the filter heating device are repeated in a short time, and the consumption of heating energy increases.

[0010] On the other hand, in this aspect, depending on the freezing condition parameters and the pressure difference, one of the heating state and the non-heating state is indicated for the filter heating device. Therefore, in this aspect, when the freezing conditions are satisfied and the filter is clogged with ice and the pressure difference between the upstream side and the downstream side of the filter is large, the filter can be heated. Also, in this aspect, when the freezing conditions are not satisfied and the filter is hardly clogged with ice and the pressure difference between the upstream side and the downstream side of the filter is small, the heating of the filter can be stopped.

[0011] Therefore, in this aspect, the filter heating device can be heated during an appropriate time period and can be made non-heated during an appropriate time period, so that the consumption of heating energy of the filter can be suppressed.

[0012] An intake duct facility as one aspect for achieving the above object is equipped with the freeze prevention control device as the one aspect, the intake duct, the filter, and the filter heating device.

[0013] A gas turbine facility as one aspect for achieving the above object is equipped with the intake duct facility as the one aspect 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 drivable by the combustion gas. The filter heating device has a compressed air line capable of guiding a part 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. The control device main body uses an open instruction to the compressed air valve as an instruction for the heating state, and a close instruction to the compressed air valve as an instruction for the non-heating state.

[0014] A freeze prevention method as one aspect for achieving the above object is applied to the following intake duct facility. This gas turbine facility includes an intake duct having an air intake capable of sucking in outside air and an air intake outlet through which the outside air sucked in from the air intake flows out, a filter disposed in the intake duct, and a filter heating device capable of heating the filter. In the anti-freezing method for suppressing freezing of the filter, a freezing condition parameter detection step of detecting a freezing condition parameter indicating whether or not ice can adhere to the filter, a pressure difference detection step of detecting a pressure difference which is a difference between the pressure on the upstream side which is on the intake port side of the filter and the pressure on the downstream side which is on the intake outlet side of the filter in the intake duct, and a control step of instructing, according to the freezing condition parameter and the pressure difference, one of a heating state of heating the filter and a non-heating state of not heating the filter to the filter heating device are executed.

[0015] In this aspect, similar to the anti-freezing control device as the one aspect, consumption of heating energy of the filter can be suppressed.

Advantages of the Invention

[0016] In one aspect of the present disclosure, consumption of heating energy of a filter disposed in an intake duct can be suppressed.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0018] Hereinafter, various embodiments according to the present disclosure will be described with reference to the drawings.

[0019] "Embodiment of Gas Turbine Facility" Hereinafter, the gas turbine facility in the present embodiment will be described with reference to FIGS. 1 to 3.

[0020] As shown in FIG. 1, the gas turbine facility in the present 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 and high-pressure combustion gas G, and an intermediate casing 25.

[0022] The compressor 10 has a compressor rotor 11 rotatable about an axis Ar, a compressor casing 12 covering the compressor rotor 11, a plurality of compressor stator blade rows 13, an intake air amount adjuster 14, and an intake casing 15. The turbine 30 has a turbine rotor 31 rotatable about the axis Ar, a turbine casing 32 covering the turbine rotor 31, a plurality of turbine stator blade rows 33, and an exhaust casing 35. Hereinafter, the direction in which the axis Ar extends is defined as the axial direction Da, one side in the axial direction Da is defined as the upstream side Dau of the axis, and the other side in the axial direction Da is defined as the downstream side Dad of the axis. Also, the circumferential direction about the axis Ar is simply defined as the circumferential direction Dc. Further, the direction perpendicular to the axis Ar is defined as the radial direction Dr, the side approaching the axis Ar in the radial direction Dr is defined as the inner side Dri in the radial direction, and the opposite side is defined as the outer side Dro in the radial direction.

[0023] The compressor 10 is arranged on the upstream side Dau of the axis with respect to the turbine 30. The compressor rotor 11 has a compressor rotor shaft 11s extending in the axial direction Da around the axis Ar, and a plurality of compressor blade rows 11b attached to the compressor rotor shaft 11s. The plurality of compressor blade rows 11b are arranged in the axial direction Da. Each compressor blade row 11b is composed of a plurality of blades arranged in the circumferential direction Dc. On the downstream side Dad of the axis of each of the plurality of compressor blade rows 11b, one of the plurality of compressor stator blade rows 13 is arranged. Each compressor stator blade row 13 is attached inside the compressor casing 12. Each compressor stator blade row 13 is composed of a plurality of stator blades arranged in the circumferential direction Dc. The intake air amount adjusting mechanism 14 has a plurality of inlet guide vanes 14v and a driver 14d capable of changing the orientation of each inlet guide vane 14v. The plurality of inlet guide vanes 14v are arranged on the upstream side Dau of the axis with respect to the plurality of compressor 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 on the upstream side of the axis with respect to the plurality of inlet guide vanes 14v and is connected to the end of the upstream side Dau of the axis of the compressor casing 12. This intake casing 15 can efficiently guide the 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 around the axis Ar, and a plurality of turbine blade rows 31b attached to the turbine rotor shaft 31s. The plurality of turbine blade rows 31b are arranged in the axial direction Da. Each turbine blade row 31b is composed of a plurality of blades arranged in the circumferential direction Dc. On the upstream side Dau of the axis of each of the plurality of turbine blade rows 31b, one of the plurality of turbine stator blade rows 33 is arranged. 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 arranged in the circumferential direction Dc. The exhaust casing 35 is arranged on the downstream side Dad of the axis with respect to the plurality of turbine blade rows 31b and is connected to the end of the downstream side Dad of the axis of the turbine casing 32.

[0025] The intermediate casing 25 is arranged between the compressor casing 12 and the turbine casing 32 in the axial direction Da. The end of the upstream side Dau of the axis of the intermediate casing 25 is connected to the end of the downstream side Dad of the axis of the compressor casing 12. The end of the downstream side Dad of the axis of the intermediate casing 25 is connected to the end of the upstream side Dau of the axis of the turbine casing 32. The plurality of combustors 20 are attached to the intermediate casing 25 side by side in the circumferential direction Dc.

[0026] The exhaust casing 35 is connected to a chimney 39, for example, via an exhaust duct. Note that a waste heat recovery boiler for generating steam by using 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 located on the same axis Ar and are connected to each other to form a gas turbine rotor 1. For example, a rotor of a generator GEN is connected to this gas turbine rotor 1.

[0028] The intake duct facility 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 a freeze prevention control device 50 for controlling the filter heating device 45.

[0029] The intake duct 41 has an intake duct body 42 and a louver 43. The intake duct body 42 has an intake port 42i capable of sucking in outside air A and an intake outlet 42o through which the outside air A sucked in from the intake port 42i flows out. The intake outlet 42o of the intake duct body 42 is connected to the intake casing 15 of the compressor 10. Therefore, the outside air A flowing into the intake duct body 42 flows into the compressor casing 12 through the intake casing 15. A louver 43 is provided at a position along the intake port 42i inside the intake duct body 42. This louver 43 serves to suppress the inflow of large dust, snow, etc. in the outside air A into the intake duct body 42.

[0030] The filter 44 is disposed within the intake duct body 42 so as to block the flow path within the intake duct body 42. This filter 44 serves to catch foreign matter that has flowed into the intake duct body 42. Here, with reference to the filter 44, 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 capable of guiding a part of the high-temperature compressed air Acom generated by the compressor 10 to the upstream side Du of the filter 44 within the intake duct 41, and a compressed air valve 47 provided in the compressed air line 46. The compressed air line 46 is connected to the intermediate casing 25. Thus, this compressed air line 46 can guide a part of the compressed air Acom discharged from the compressor 10 and flowing into the intermediate casing 25 into the intake duct 41. In this filter heating device 45, when the compressed air valve 47 is open, the high-temperature compressed air Acom is guided to the upstream side Du of the filter 44, and the filter 44 is heated by this compressed air Acom. For this reason, this filter heating device 45 becomes the heating state (ON) when the compressed air valve 47 is open, and becomes the non-heating state (OFF) when the compressed air valve 47 is closed.

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

[0033] Hereinafter, various embodiments of the freeze prevention control device and the freeze prevention method will be described.

[0034] "First Embodiment of Freeze Prevention Control Device and Freeze Prevention Method" As shown in FIGS. 1 and 2, the freeze prevention control device 50 in this embodiment includes a freeze condition parameter detector 51, a differential pressure gauge 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 at a position upstream of the filter 44, i.e., at the position Du in the intake duct main body 42. Therefore, the thermometer 52 can detect the temperature of the outside air A at the position upstream of the filter 44, i.e., at the position Du. Also, the hygrometer 53 can detect the humidity of the outside air A at the position upstream of the filter 44, i.e., at the position Du.

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

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

[0039] As shown in FIG. 2, the control device main body 60 includes a differential pressure calculator 61, a flow rate calculator 62, a differential pressure judge 63, a freezing condition judge 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 on the upstream side Du of the filter 44 and the pressure on the downstream side Dd of the filter 44.

[0041] The flow rate calculator 62 calculates the flow rate of the outside air A flowing in 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 passage area of the intake duct main body 42 between the position where the second pressure gauge 57 is provided and the position where the third pressure gauge 58 is provided.

[0042] The pressure difference discriminator 63 determines a reference pressure difference ΔPb and determines whether the pressure difference obtained by the pressure difference calculator 61 is greater than the reference pressure difference ΔPb. As shown in FIG. 3, this pressure difference discriminator 63 holds a relationship Fx between the flow rate FL of the outside air A flowing in the intake duct main body 42 and the reference pressure difference ΔPb. The pressure difference discriminator 63 obtains a reference pressure difference ΔPb corresponding to the flow rate FL obtained by the flow rate calculator 62 using this relationship Fx. Note that this reference pressure difference ΔPb is a value 1.2 to 1.4 times the pressure difference when there is almost no dust, ice, etc. attached to the filter 44.

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

[0044] Here, the reference temperature Tb and the reference humidity Hb will be described. For ice to adhere to the filter 44, supercooled mist must exist in the outside air A. In other words, for the freezing condition to be satisfied, the outside air temperature must be below the dew point, that is, the outside air temperature must be less than 0°, and the humidity in the outside air A must be 100%. Therefore, in the present embodiment, as the freezing condition under which ice can adhere to the filter 44, the temperature detected by the thermometer 52 is less than 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 the humidity of 100%. In the present embodiment, the reference temperature Tb is slightly higher than 0°, for example, 2°. The temperature of the outside air A varies slightly depending on the temperature detection position. For this reason, in the present embodiment, the reference temperature Tb is set to 2°. Also, in the present embodiment, the reference humidity Hb is slightly lower than 100%, for example, 98%. The humidity in the outside air A varies slightly depending on the humidity detection position. Also, the hygrometer 53 generally has a large detection error. For this reason, in the present embodiment, the reference humidity Hb is set to 98%.

[0045] Note that the reference temperature Tb may be any temperature as long as it is 0° or more and 5° or less. Also, the reference humidity Hb may be any humidity as long as it is less than 100% and 95% or more.

[0046] In the present embodiment, as described above, it is not determined whether ice can adhere to the filter 44 only based on the temperature of the outside air A, but it is determined whether ice can adhere to the filter 44 based on the temperature of the outside air A and the humidity in the outside air A. Therefore, it is possible to recognize with a high probability that ice adheres 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 OFF instruction signal generator 71 outputs an OFF instruction signal indicating a non-heating state (OFF) to the compressed air valve 47 of the filter heating device 45, if the pressure difference is greater than the reference pressure difference ΔPb and the freezing condition is satisfied, the ON instruction signal generator 71 generates an ON instruction signal indicating a heating state (ON). Therefore, this ON instruction signal generator 71 has an AND circuit. When the OFF instruction signal generator 72 outputs an ON instruction signal to the compressed air valve 47 of the filter heating device 45, if the pressure difference is not greater than the reference pressure difference ΔPb and the freezing condition is not satisfied, the OFF instruction signal generator 72 generates an OFF instruction signal. Therefore, this ON instruction signal generator 71 has a NOR circuit. When the ON instruction signal generator 71 generates an ON instruction signal, the instruction signal output unit 73 continuously outputs the 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 continuously outputs the 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 unit has a flip-flop circuit that holds the signal.

[0048] Note that the control device main body 60 described above is a computer. Also, all of the functional elements of the control device main body 60 described above function when the freezing prevention control program stored in the external storage device of the computer is expanded into the main storage device of the computer and this freezing prevention control program is executed by the CPU (Central Processing Unit) of the computer.

[0049] Next, according to the flowchart shown in FIG. 4, the operation of the freezing prevention control device 50 in the present embodiment will be described.

[0050] The freezing condition parameter detector 51 detects a freezing condition parameter indicating whether ice can 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 upstream Du of the filter 44, and the second pressure gauge 57 detects the pressure of the outside air A at a position downstream Dd of the filter 44. The pressure difference calculator 61 obtains a pressure difference that is the 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 parameter detected by the freezing condition parameter detector 51 satisfies the freezing condition (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 less 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 condition is satisfied. Also, when the temperature determiner 65 determines that the temperature detected by the thermometer 52 is not less 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 condition is not satisfied.

[0053] After the pressure difference determiner 63 determines a reference pressure difference ΔPb corresponding to the flow rate of the outside air A obtained by the flow rate calculator 62, the pressure difference determiner 63 determines whether the pressure difference obtained 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 according to the judgment results of the freezing condition judgment device 64 and the pressure difference judgment device 63 (heating control step S5). Specifically, when the OFF instruction signal generator 71 of the heating controller 70 determines that the pressure difference is greater than the reference pressure difference ΔPb and the freezing condition is satisfied while the instruction signal output device 73 is outputting an OFF instruction signal, it generates an ON instruction signal indicating the heating state (ON). The OFF instruction signal generator 72 of the heating controller 70 generates an OFF instruction signal when the pressure difference is not greater than the reference pressure difference ΔPb and the freezing condition is not satisfied while the instruction signal output device 73 is outputting an ON instruction signal. When the ON instruction signal generator 71 of the heating controller 70 generates an ON instruction signal, the instruction signal output device 73 of the heating controller 70 continuously outputs 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 continuously outputs 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 the case where only the freezing condition parameter is used to instruct either the heating state or the non - heating state of the filter heating device 45. Even if the outside air A flowing into the intake duct 41 satisfies the freezing condition parameter, there may be little icing on the actual filter 44. In this case, if the filter 44 is heated by the filter heating device 45, heating energy will be wasted. Also, 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 that has not completely melted. In this case, if the heating of the filter 44 by the filter heating device 45 is stopped, the heating energy consumed until just before the heating stop will be wasted.

[0056] Next, consider the case where one of the heated state and the non-heated state is indicated according to only the pressure difference between the upstream side Du and the downstream side Dd of the filter 44. There may be a case where dust adheres to the filter 44 and the pressure difference increases. In this case, if the filter 44 is heated by the filter heating device 45, heating energy will be wasted. Also, as a result of heating the filter 44 by the filter heating device 45, even if the ice adhering to the filter 44 melts, there may still be a case where the freezing conditions are still satisfied. In this case, ice starts to adhere to the filter 44 again and the pressure difference increases. For this reason, the heating and non-heating of the filter 44 are repeatedly performed by the filter heating device 45 in a short period of time, and the consumption of heating energy increases.

[0057] On the other hand, in the present embodiment, one of the heated state and the non-heated state is indicated to the filter heating device 45 according to the freezing condition parameter and the pressure difference. Therefore, in the present embodiment, when the freezing conditions are satisfied and the filter 44 is clogged with ice and the pressure difference between the upstream side Du and the downstream side Dd of the filter 44 is large, the filter 44 can be heated. Also, in this aspect, when the freezing conditions are not satisfied and the filter 44 is hardly clogged with ice and the pressure difference between the upstream side Du and the downstream side Dd of the filter 44 is small, the heating of the filter 44 can be stopped.

[0058] Therefore, in the present embodiment, the filter heating device 45 can be put into the heated state in an appropriate time zone and into the non-heated state in an appropriate time zone, so that the consumption of heating energy of the filter 44 can be suppressed.

[0059] "Second Embodiment of Freezing Prevention Control Device and Freezing Prevention Method" As shown in FIG. 5, the freeze prevention control device 50a in the present embodiment also has a freeze condition parameter detector 51, a differential pressure gauge 55, and a control device main body 60a, similar to the freeze prevention control device 50 in the first embodiment. However, in the freeze prevention control device 50a in the present embodiment, only the configuration of the control device main body 60a is different from the configuration of the control device main body 60 of the freeze prevention control device 50 in the first embodiment. Therefore, hereinafter, the control device main body 60a of the freeze prevention control device 50a in the present embodiment will be mainly described.

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

[0061] The differential pressure judge 63a in the present embodiment has a first differential pressure judge 63aa and a second differential pressure judge 63ab. The first differential pressure judge 63aa determines a first reference differential pressure ΔPb1 and judges whether the differential pressure obtained by the differential pressure calculator 61 is greater than the first reference differential pressure ΔPb1. This first differential pressure judge 63aa holds the relationship Fx between the flow rate of the outside air A flowing in the intake duct main body 42 and the first reference differential pressure ΔPb1, similar to the differential pressure judge 63 in the first embodiment. The first differential pressure judge 63aa obtains the first reference differential pressure ΔPb1 corresponding to the flow rate obtained by the flow rate calculator 62 using this relationship Fx. The second differential pressure judge 63ab determines a second reference differential pressure ΔPb2 and judges whether the differential pressure obtained by the differential pressure calculator 61 is greater than the second reference differential pressure ΔPb2. In other words, the second differential pressure judge 63ab judges whether the differential pressure obtained by the differential pressure calculator 61 is less than or equal to the second reference differential pressure ΔPb2. This second differential pressure judge 63ab sets a differential pressure slightly smaller than the first reference differential pressure ΔPb1 at this time as the second reference differential pressure ΔPb2.

[0062] The freezing condition determiner 64a in this embodiment includes a temperature determiner 65a, a humidity determiner 66a, a first condition fulfillment determiner 68a, and a second condition fulfillment 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 greater than or equal to the second reference temperature Tb2. Both the first reference temperature Tb1 and the second reference temperature Tb2 are temperatures predetermined based on the dew point temperature. The first reference temperature Tb1 is, for example, 2°, which is slightly higher than 0°, the dew point temperature. Also, the second reference temperature Tb2 is, for example, 4°, which is 2° higher than the first reference temperature Tb1. Note that the first reference temperature Tb1 may be any temperature as long as it is, for example, 0° or higher and 4° or lower. Also, the second reference temperature Tb2 may be any temperature as long as it is a temperature 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 less than or equal to the second reference humidity Hb2. Both the first reference humidity Hb1 and the second reference humidity Hb2 are predetermined humidities based on 100% humidity. The first reference humidity Hb1 is, for example, 98%, which is slightly lower than 100% humidity. Also, the second reference humidity Hb2 is, for example, 2% lower than the first reference humidity Hb1, which is 96%. Note that the first reference humidity Hb1 may be any humidity as long as it is less than 100% and equal to or higher than 96%. Also, the second reference humidity Hb2 may be any humidity as long as it is slightly lower than the first reference humidity Hb1.

[0065] The first condition satisfaction determiner 68a determines 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 determiner 68a has an AND circuit. Also, the second condition satisfaction determiner 69a determines that the freezing condition is not satisfied when the temperature detected by the thermometer 52 is not less than the second reference temperature Tb2 (the temperature 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 (the humidity is less than or equal to the second reference humidity Hb2). Therefore, this second condition satisfaction determiner 69a has an OR circuit.

[0066] The heating controller 70a has an ON instruction signal generator 71, an OFF instruction signal generator 72a, and an instruction signal output unit 73, similar to the heating controller 70 in the first embodiment. However, the OFF instruction signal generator 72a of this heating control device generates an OFF instruction signal when the pressure difference is not higher than the second reference pressure difference ΔPb2 (less than or equal to the second reference pressure difference ΔPb2) and the freezing condition is not satisfied while the instruction signal output unit 73 outputs an ON instruction signal instructing the heating state (ON) to the compressed air valve 47 of the filter heating device 45. Therefore, this OFF instruction signal generator 72a has an AND circuit. Although the OFF instruction signal generator 72 in the first embodiment has a NOR circuit, the OFF instruction signal generator 72a in this embodiment has an AND circuit. This is because the pressure difference determination unit 63a in this embodiment outputs that the pressure difference is higher than the second reference pressure difference ΔPb2 (less than or equal to the second reference pressure difference ΔPb2), and the freezing condition determination unit 64a in this embodiment outputs 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 continuously outputs 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. Also, when the OFF instruction signal generator 72a generates an OFF instruction signal, the instruction signal output unit 73 continuously outputs 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 anti-freezing control device 50a in this embodiment will be described according to the flowchart shown in FIG. 4.

[0068] The freezing condition parameter detector 51 detects a freezing condition parameter indicating whether ice can adhere to the filter 44, similar to the first embodiment (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.

[0069] Also, the first pressure gauge 56 detects the pressure of the outside air A at the position Du upstream of the filter 44, and the second pressure gauge 57 detects the pressure of the outside air A at the position Dd downstream of the filter 44. The pressure difference calculator 61 obtains a pressure difference that is the 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 judgment unit 64a judges whether the freezing condition parameter detected by the freezing condition parameter detector 51 satisfies the freezing condition (freezing condition judgment step S3a). Specifically, when the first temperature judgment unit 65aa of the freezing condition judgment unit 64a judges that the temperature detected by the thermometer 52 is less than the first reference temperature Tb1, and the first humidity judgment unit 66aa of the freezing condition judgment unit 64a judges that the humidity detected by the hygrometer 53 is higher than the first reference humidity Hb1, the first condition establishment judgment unit 68a judges that the freezing condition is satisfied. Also, when the second temperature judgment unit 65ab judges that the temperature detected by the thermometer 52 is equal to or higher than the second reference temperature Tb2, and / or when the second humidity judgment unit 66ab judges that the humidity detected by the hygrometer 53 is equal to or lower than the second reference humidity Hb2, the second condition establishment judgment unit 69a judges that the freezing condition is not satisfied.

[0071] After the first pressure difference judgment unit 63aa determines a first reference pressure difference ΔPb1 corresponding to the flow rate of the outside air A obtained by the flow rate calculator 62, it judges whether the pressure difference obtained by the pressure difference calculator 61 is greater than the first reference pressure difference ΔPb1. Also, after the second pressure difference judgment unit 63ab determines a second reference pressure difference ΔPb2 corresponding to the flow rate of the outside air A obtained by the flow rate calculator 62, it judges whether the pressure difference obtained by the pressure difference calculator 61 is equal to or less than the second reference pressure difference ΔPb2. (Pressure difference judgment step S4a).

[0072] Similar to the first embodiment, the heating controller 70a outputs an ON instruction signal or an OFF instruction signal to the filter heating device 45 according to the determination results of the freezing condition determiner 64a and the pressure difference determiner 63a (heating control step S5).

[0073] As described above, also in this embodiment, similar to the first embodiment, according to the freezing condition parameter and the pressure difference, one of the heating state and the non-heating state is instructed for the filter heating device 45. Therefore, also in this embodiment, the consumption of the heating energy of the filter 44 can be suppressed.

[0074] Further, in this embodiment, on the condition that when the filter heating device 45 is in the heating state, the pressure difference determiner 63a determines that the pressure difference is equal to or less than a second reference pressure difference ΔPb2 which is not more severe than the first reference pressure difference ΔPb1, the filter heating device 45 is set to the non-heating state. Therefore, in this embodiment, even when there are some pressure difference fluctuations, it is possible to avoid the repetition of the heating state and the non-heating state in a short time.

[0075] Furthermore, in this embodiment, on the condition that when the filter heating device 45 is in the heating state, the freezing condition determiner 64a determines that the temperature is equal to or higher than a second reference temperature Tb2 which is not more severe than the first reference temperature Tb1, or the humidity is equal to or less than a second reference humidity Hb2 which is not more severe than the first reference humidity Hb1, the filter heating device 45 is set to the non-heating state. Therefore, in this embodiment, even when there are some temperature fluctuations and humidity fluctuations, it is possible to avoid the repetition of the heating state and the non-heating state in a short time.

[0076] "Third Embodiment of Freezing Prevention Control Device and Freezing Prevention Method" As shown in FIG. 6, the freezing prevention control device 50b in this embodiment also includes a freezing condition parameter detector 51b, a pressure difference meter 55, and a control device main body 60b, similar to the freezing prevention control devices 50 and 50a in the first and second embodiments.

[0077] Unlike the freezing condition parameter detector 51 in the above embodiments, the freezing condition parameter detector 51b in this embodiment has a mist amount meter 54 in addition to the thermometer 52 and the hygrometer 53. As shown in FIG. 1, the mist amount meter 54 is provided at a position Du upstream of the filter 44 in the intake duct main body 42 and can detect the amount of mist in the outside air A at a position Du upstream of the filter 44 in the intake duct main body 42. There are various types of mist amount meters for the mist amount meter 54, and any type of mist amount meter may be used. As a method for detecting the amount of mist, for example, a method of irradiating the outside air A with laser light and detecting the amount of mist based on the scattered light generated by the mist, or a method of arranging a baffle plate that blocks a part of the flow path through which the outside air A flows and detecting the amount of water dripping from the baffle plate, etc.

[0078] Similar to the control device main bodies 60 and 60a in the above embodiments, the control device main body 60b in this embodiment has a pressure difference calculator 61, a flow rate calculator 62, a pressure difference discriminator 63a, a freezing condition discriminator 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 discriminator 63a in this embodiment is the same as the pressure difference discriminator 63a in the second embodiment. Therefore, the pressure difference discriminator 63a in this embodiment has a first pressure difference discriminator 63aa and a second pressure difference discriminator 63ab. The heating controller 70a in this embodiment is the same as the heating controller 70a in the second embodiment. Therefore, similar to the heating controller 70a in the second embodiment, the heating controller 70a in this embodiment has an ON instruction signal generator 71, an OFF instruction signal generator 72a, and an instruction signal outputter 73. The freezing condition discriminator 64b in this embodiment is a discriminator obtained by adding a mist amount discriminator 67b to the freezing condition discriminator 64a in the second embodiment.

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

[0080] The first condition satisfaction determination device 68b in the present embodiment determines that the freezing condition is satisfied 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 mist amount detected by the mist amount meter 54 is greater than the first reference mist amount Mb1. Therefore, this first condition satisfaction determination device 68b has an AND circuit, similar to the first condition satisfaction determination device 68a in the second embodiment. Also, the second condition satisfaction determination device 69b determines that the freezing condition is not satisfied when the temperature detected by the thermometer 52 is not less than the second reference temperature Tb2 (the temperature is greater than or equal to the second reference temperature Tb2), and / or the humidity detected by the hygrometer 53 is not higher than the second reference humidity Hb2 (the humidity is less than or equal to the second reference humidity Hb2), and / or the mist amount detected by the mist amount meter 54 is not greater than the second reference mist amount Mb2 (the mist amount is less than or equal to the second reference mist amount Mb2). Therefore, this second condition satisfaction determination device 69b has an OR circuit, similar to the second condition satisfaction determination device 69a in the second embodiment.

[0081] Next, the operation of the freezing prevention control device 50b in the present embodiment will be described according to the flowchart shown in FIG. 4.

[0082] The freezing condition parameter detector 51b detects a freezing condition parameter indicating whether ice can adhere to the filter 44 (freezing condition parameter detection step S1b), similar to the above-described embodiment. However, here, 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] Also, the first pressure gauge 56 detects the pressure of the outside air A at the position Du upstream of the filter 44, and the second pressure gauge 57 detects the pressure of the outside air A at the position Dd downstream of the filter 44. The pressure difference calculator 61 obtains a pressure difference that is the 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 parameter detected by the freezing condition parameter detector 51b satisfies the freezing condition (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 less 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 amount of mist detected by the mist amount meter 54 is more than the first reference mist amount Mb1, the first condition establishment determiner 68b determines that the freezing condition is satisfied. Also, when the second temperature determiner 65ab of the freezing condition determiner 64b 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 of the freezing condition determiner 64b 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 of the freezing condition determiner 64b determines that 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 condition establishment determiner 69b determines that the freezing condition is not satisfied.

[0085] After determining the first reference pressure difference ΔPb1 according to the flow rate of the outside air A obtained by the flow rate calculator 62, the first pressure difference discriminator 63aa determines whether the pressure difference obtained by the pressure difference calculator 61 is greater than the first reference pressure difference ΔPb1. Further, after determining the second reference pressure difference ΔPb2 according to the flow rate of the outside air A obtained by the flow rate calculator 62, the second pressure difference discriminator 63ab determines whether the pressure difference obtained by the pressure difference calculator 61 is equal to or less than the second reference pressure difference ΔPb2 (pressure difference determination step S4a).

[0086] Similar to the above embodiments, the heating controller 70a outputs an ON instruction signal or an OFF instruction signal to the filter heating device 45 according to the determination results of the freezing condition discriminator 64b and the pressure difference discriminator 63a (heating control step S5).

[0087] As described above, also in this embodiment, similar to the first and second embodiments, according to the freezing condition parameters and the pressure difference, one of the heating state and the non-heating state is instructed for the filter heating device 45. Therefore, also in this embodiment, the consumption of the heating energy of the filter 44 can be suppressed.

[0088] Also, in this embodiment, similar to the second embodiment, it is possible to avoid the repetition of the heating state and the non-heating state in a short time even when there are some pressure difference fluctuations, temperature fluctuations, and humidity fluctuations.

[0089] Also, in this embodiment, when determining whether the freezing conditions are satisfied, in addition to the temperature and humidity, the amount of mist is also considered. Therefore, in this embodiment, it is possible to highly probabilistically recognize that a relatively large amount of ice adheres to the filter 44.

[0090] Furthermore, in the present embodiment, when the filter heating device 45 is in the heating state, the filter heating device 45 is set to the non-heating state on the condition that the mist amount determination unit 67b determines that the mist amount is equal to or less than a second reference mist amount Mb2, which is not as strict as the first reference mist amount Mb1. Therefore, in the present embodiment, even when there is a slight variation in the mist amount, it is possible to avoid repeatedly switching between the heating state and the non-heating state in 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 a mist amount meter 54. In this case, the freezing condition determination unit 64 of the control device main body 60 in the first embodiment will have a mist amount determination unit. This mist amount determination unit determines whether the mist amount 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 has a compressed air line 46 and a compressed air valve 47. However, the filter heating device may be any heating device as long as it can heat the filter 44. For example, it may be an electric heater arranged to surround the filter 44.

[0093] Also, the present disclosure is not limited to the embodiments described above. Various additions, changes, replacements, partial deletions, etc. are possible without departing from the conceptual ideas and spirit of the present invention derived from the content defined in the claims and their equivalents.

[0094] "Supplementary Note" The anti-freezing control devices 50, 50a, 50b in the above embodiments can be understood as follows, for example.

[0095] (1) The anti-freezing control devices 50, 50a, 50b in the first aspect are applied to the following intake duct facilities 40. This intake duct facility 40 includes an intake duct 41 having an intake port 42i capable of sucking outside air A and an intake outlet 42o through which the outside air A sucked from the intake port 42i flows out, a filter 44 disposed in the intake duct 41, and a filter heating device 45 capable of heating the filter 44. The freeze prevention control devices 50, 50a, 50b that control the filter heating device 45 include a freeze condition parameter detector 51, 51b capable of detecting a freeze condition parameter indicating whether ice can adhere to the filter 44, a differential pressure gauge 55 capable of detecting a pressure difference that is the difference between the pressure on the upstream side Du, which is on the side of the intake port 42i rather than the filter 44, and the pressure on the downstream side Dd, which is on the side of the intake outlet 42o rather than the filter 44, within the intake duct 41, and a control device main body 60, 60a, 60b capable of instructing either a heating state in which the filter 44 is heated or a non-heating state in which the filter 44 is not heated for the filter heating device 45 according to the freeze condition parameter and the pressure difference.

[0096] For example, consider the case of instructing either a heating state or a non-heating state for the filter heating device 45 according to only the freeze condition parameter. Even if the outside air A flowing into the intake duct 41 satisfies the freeze condition parameter, there may be little icing on the actual filter 44. In this case, if the filter 44 is heated by the filter heating device 45, heating energy will be wasted. Also, even if the outside air A flowing into the intake duct 41 no longer satisfies the freeze condition parameter, there may still be ice remaining on the filter 44 that has not completely melted. In this case, if the heating of the filter 44 by the filter heating device 45 is stopped, the heating energy consumed until immediately before the heating stop will be wasted.

[0097] Next, consider the case where one of the heated state and the non-heated state is indicated according to only the pressure difference between the upstream side Du and the downstream side Dd of the filter 44. There may be a case where dust adheres to the filter 44 and the pressure difference increases. In this case, if the filter 44 is heated by the filter heating device 45, heating energy will be wasted. Further, as a result of heating the filter 44 by the filter heating device 45, even if the ice adhering to the filter 44 melts, there may still be a case where the freezing conditions are satisfied. In this case, ice starts to adhere to the filter 44 again, and the pressure difference increases. For this reason, the heating and non-heating of the filter 44 are repeated by the filter heating device 45 in a short time, and the consumption of heating energy increases.

[0098] On the other hand, in this aspect, one of the heated state and the non-heated state is indicated to the filter heating device 45 according to the freezing condition parameter and the pressure difference. Therefore, in this aspect, when the freezing conditions are satisfied and the filter 44 is clogged with ice and the pressure difference between the upstream side Du and the downstream side Dd of the filter 44 is large, the filter 44 can be heated. Further, in this aspect, when the freezing conditions are not satisfied and the filter 44 is hardly clogged with ice and the pressure difference between the upstream side Du and the downstream side Dd of the filter 44 is small, the heating of the filter 44 can be stopped.

[0099] Therefore, in this aspect, the filter heating device 45 can be set to the heated state in an appropriate time zone and set to the non-heated state in an appropriate time zone, so that the consumption of heating energy of the filter 44 can be suppressed.

[0100] (2) The freeze prevention control devices 50, 50a, 50b in the second aspect are In the freeze prevention control devices 50, 50a, 50b in the first aspect, the freeze condition parameter detector 51, 51b includes a thermometer 52 capable of detecting the temperature of the outside air A at a position Du on the upstream side of the filter 44, and a hygrometer 53 capable of detecting the humidity of the outside air A at a position Du on the upstream side of the filter 44. The freeze condition parameters include the temperature of the outside air A and the humidity of the outside air A. The control device main bodies 60, 60a, 60b include a freeze condition judge 64, 64a, 64b for judging whether the freeze condition parameters satisfy the freeze condition under which ice can adhere to the filter 44, a pressure difference judge 63, 63a for judging whether the pressure difference is greater than the reference pressure difference ΔPb, and a heating controller 70, 70a for instructing the filter heating device 45 to be in the heating state or the non-heating state according to the judgment result of the freeze condition judge 64, 64a, 64b and the judgment result of the pressure difference judge 63, 63a. The freeze condition judge 64, 64a, 64b judges that the freeze condition is satisfied on the condition that the temperature detected by the thermometer 52 is lower than 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. When the filter heating device 45 is in the non-heating state, the heating controller 70, 70a instructs the filter heating device 45 to be in the heating state when the freeze condition judge 64, 64a, 64b judges that the freeze condition is satisfied and the pressure difference judge 63, 63a judges that the pressure difference is greater than the reference pressure difference ΔPb. When the filter heating device 45 is in the heating state, the heating controller 70, 70a instructs the filter heating device 45 to be in the non-heating state when the freeze condition judge 64, 64a, 64b judges that the freeze condition is not satisfied and the pressure difference judge 63, 63a judges that the pressure difference is less than or equal to the reference pressure difference ΔPb.

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

[0102] (3) The freezing prevention control devices 50a and 50b in the third aspect are In the freezing prevention control devices 50a and 50b in the second aspect, the reference temperature Tb has a first reference temperature Tb1 and a second reference temperature Tb2 higher than the first reference temperature Tb1. The reference humidity Hb has a first reference humidity Hb1 and a second reference humidity Hb2 lower than the first reference humidity Hb1. When the filter heating device 45 is in the non-heated state, the freezing condition determination units 64a and 64b determine 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. When the filter heating device 45 is in the heated state, the freezing condition determination units 64a and 64b determine that the freezing condition is not satisfied 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.

[0103] In this aspect, when the filter heating device 45 is in the heating state, the freezing condition determination units 64a and 64b determine whether the temperature is equal to or higher than a second reference temperature Tb2 that is not more stringent than the first reference temperature Tb1, or whether the humidity is equal to or lower than a second reference humidity Hb2 that is not more stringent than the first reference humidity Hb1. If either condition is met, the filter heating device 45 is set to the non-heating state. Therefore, in this aspect, even when there are some temperature fluctuations or humidity fluctuations, it is possible to avoid repeatedly switching between the heating state and the non-heating state in a short period of time.

[0104] (4) The freeze prevention control device 50b in the fourth aspect is In the freeze prevention control device 50b in the second aspect, the freezing condition parameter detector 51b includes 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 determination unit 64b determines that the freezing condition is satisfied when the temperature detected by the thermometer 52 is less 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 aspect, when determining whether the freezing condition is satisfied, in addition to the temperature and humidity, the amount of mist is also considered. Therefore, in this aspect, it is possible to highly probably recognize that a relatively large amount of ice adheres to the filter 44.

[0106] (5) The freeze prevention control device 50b in the fifth aspect is In the freeze prevention control device 50b according to the fourth aspect, the reference temperature Tb has a first reference temperature Tb1 and a second reference temperature Tb2 higher than the first reference temperature Tb1. The reference humidity Hb has a first reference humidity Hb1 and a second reference humidity Hb2 lower than the first reference humidity Hb1. The reference mist amount has a first reference mist amount Mb1 and a second reference mist amount Mb2 less than the first reference mist amount Mb1. When the filter heating device 45 is in the non-heated state, the freeze condition determination unit 64b determines that the freeze condition is satisfied 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 mist amount detected by the mist amount meter 54 is more than the first reference mist amount Mb1. When the filter heating device 45 is in the heated state, the freeze condition determination unit 64b determines that the freeze condition is not satisfied when 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 mist amount detected by the mist amount meter 54 is equal to or less than the second reference mist amount Mb2.

[0107] In this aspect, on the condition that when the filter heating device 45 is in the heated state, the mist amount determination unit 67b determines that the mist amount is equal to or less than the second reference mist amount Mb2, which is not as strict as the first reference mist amount Mb1, the filter heating device 45 is set to the non-heated state. Therefore, in this aspect, even when there is a slight variation in the mist amount, it is possible to avoid repeating the heated state and the non-heated state in a short period of time.

[0108] (6) The freeze prevention control devices 50, 50a, and 50b in the sixth aspect are In the freeze prevention control devices 50, 50a, and 50b according to any one of the second to fifth aspects, the pressure difference discriminators 63 and 63a hold a relationship Fx between the flow rate of the outside air A flowing in the intake duct 41 and the reference pressure difference ΔPb, and determine the reference pressure difference ΔPb corresponding to the flow rate of the outside air A flowing in the intake duct 41 using the relationship Fx.

[0109] (7) The freeze prevention control devices 50a and 50b in the seventh aspect are In the freeze prevention control devices 50a and 50b according to any one of the second to fifth aspects, 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 discriminator 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-heated state. The pressure difference discriminator 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 heated state. When the filter heating device 45 is in the non-heated state, the heating controller 70a instructs the filter heating device 45 to enter the heated state when it is determined by the freeze condition discriminators 64a and 64b that the freeze condition is satisfied and it is determined by the pressure difference discriminator 63a that the pressure difference is greater than the first reference pressure difference ΔPb1. When the filter heating device 45 is in the heated state, the heating controller 70a instructs the filter heating device 45 to enter the non-heated state when it is determined by the freeze condition discriminators 64a and 64b that the freeze condition is not satisfied and it is determined by the pressure difference discriminator 63a that the pressure difference is less than or equal to the second reference pressure difference ΔPb2.

[0110] In this aspect, when the filter heating device 45 is in the heating state, on the condition that the pressure difference determination unit 63a determines that the pressure difference is equal to or less than a second reference pressure difference ΔPb2 that is not stricter than the first reference pressure difference ΔPb1, the filter heating device 45 is set to the non-heating state. Therefore, in this aspect, even when there is a certain pressure difference fluctuation, it is possible to avoid repeating the heating state and the non-heating state in a short period of time.

[0111] The intake duct facility 40 in the above embodiment is understood as follows, for example. (8) The intake duct facility 40 in the eighth aspect includes the freeze prevention control devices 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 facility in the above embodiment is understood as follows, for example. (9) The gas turbine facility in the ninth aspect includes the intake duct facility 40 in the ninth aspect and the gas turbine GT. The gas turbine GT includes a compressor 10 capable of compressing the 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 drivable by the combustion gas. The filter heating device 45 has a compressed air line 46 capable of guiding a part of the compressed air Acom generated by the compressor 10 to the upstream side Du of 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 bodies 60, 60a, 60b use an open instruction to the compressed air valve 47 as an instruction for the heating state, and a close instruction to the compressed air valve 47 as an instruction for the non-heating state.

[0113] The freeze prevention method in the above embodiment is understood as follows, for example. (10) The freeze prevention method in the tenth aspect is applied to the following intake duct facility 40. This intake duct facility 40 includes an intake duct 41 having an air intake port 42i capable of sucking in outside air A and an air intake outlet 42o through which the outside air A sucked in from the air intake port 42i flows out, a filter 44 disposed in the intake duct 41, and a filter heating device 45 capable of heating the filter 44. In the freezing prevention method for suppressing the freezing of the filter 44, a freezing condition parameter detection step S1, S1b for detecting a freezing condition parameter indicating whether or not ice can adhere to the filter 44, a pressure difference detection step S2 for detecting a pressure difference, which is a difference between the pressure on the upstream side Du, which is on the side of the air intake port 42i rather than the filter 44, and the pressure on the downstream side Dd, which is on the side of the air intake outlet 42o rather than the filter 44, in the intake duct 41, and a control step for instructing the filter heating device 45 to be in one of a heating state for heating the filter 44 and a non-heating state for not heating the filter 44 according to the freezing condition parameter and the pressure difference are executed.

[0114] In this aspect, similar to the first aspect, the consumption of heating energy of the filter 44 can be suppressed.

[0115] (11) The freezing prevention method in the eleventh aspect is In the freezing prevention method according to the tenth aspect, in the freezing condition parameter detection steps S1 and S1b, as the freezing condition parameters, the temperature and humidity of the outside air A at the position Du on the upstream side of the filter 44 are detected. The control step includes a freezing condition determination step S3, S3a, S3b for determining whether the freezing condition parameters satisfy a freezing condition under which ice can adhere to the filter 44, a pressure difference determination step S4, 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 be in the heating state or the non-heating state according to the determination results in the freezing condition determination step S3, S3a, S3b and the pressure difference determination step S4, S4a. In the freezing condition determination steps S3, S3a, S3b, it is determined that the freezing condition is satisfied on the condition that the temperature detected in the freezing condition parameter detection steps S1, S1b is lower than a reference temperature Tb predetermined based on the dew point temperature, and the humidity detected in the freezing condition parameter detection steps S1, S1b is higher than a reference humidity Hb predetermined 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 in the freezing condition determination steps S3, S3a, S3b that the freezing condition is satisfied and it is determined in the pressure difference determination step S4, S4a that the pressure difference is greater than the reference pressure difference ΔPb, the filter heating device 45 is instructed to be in the heating 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 S3, S3a, S3b that the freezing condition is not satisfied and it is determined in the pressure difference determination step 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 be in the non-heating state.

[0116] In this aspect, similar to the second aspect, it is possible to highly probably recognize that ice adheres to the filter 44.

[0117] (12) The freezing prevention method according to the twelfth aspect is In the freezing prevention method according to the eleventh aspect, the reference temperature Tb has a first reference temperature Tb1 and a second reference temperature Tb2 higher than the first reference temperature Tb1. The reference humidity Hb has a first reference humidity Hb1 and a second reference humidity Hb2 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, 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, it is determined that the freezing conditions are satisfied. Also, in the freezing condition determination steps S3a and S3b, when the filter heating device 45 is in the heating state, 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, it is determined that the freezing conditions are not satisfied.

[0118] In this aspect, similar to the third aspect, it is possible to avoid the repeated alternation between the heating state and the non-heating state within a short period even when there are slight temperature fluctuations and humidity fluctuations.

[0119] (13) The freezing prevention method according to the thirteenth aspect is In the freezing prevention method according to the eleventh aspect, in the freezing condition parameter detection step S1b, the amount of mist in the outside air A is detected as the freezing condition parameter. In the freezing condition determination step S3b, if 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 amount of mist, it is determined that the freezing conditions are satisfied.

[0120] In this aspect, similar to the fourth aspect, it is possible to highly probably recognize that a relatively large amount of ice adheres to the filter 44.

[0121] (14) The anti-freezing method in the fourteenth aspect is In the anti-freezing method in the thirteenth aspect, the reference temperature Tb has a first reference temperature Tb1 and a second reference temperature Tb2 higher than the first reference temperature Tb1. The reference humidity Hb has a first reference humidity Hb1 and a second reference humidity Hb2 lower than the first reference humidity Hb1. The reference mist amount has a first reference mist amount Mb1 and a second reference mist amount Mb2 less than the first reference mist amount Mb1. In the freezing condition determination step S3b, when the filter heating device 45 is in the non-heated state, if the temperature detected in the freezing condition parameter detection step S1b is less 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 more than the first reference mist amount Mb1, it is determined that the freezing condition is satisfied. Also, in the freezing condition determination step S3b, when the filter heating device 45 is in the heated state, if the temperature detected in the freezing condition parameter detection step S1b is equal to or higher than the second reference temperature Tb2, the humidity detected in the freezing condition parameter detection step S1b is equal to or lower than the second reference humidity Hb2, or the mist amount detected in the freezing condition parameter detection step S1b is equal to or less than the second reference mist amount Mb2, it is determined that the freezing condition is not satisfied.

[0122] In this aspect, similar to the fifth aspect, even when there is some variation in the mist amount, it is possible to avoid the repeated switching between the heated state and the non-heated state within a short period of time.

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

[0124] (16) The anti-freezing method in the sixteenth aspect is In the anti-freezing method in the eleventh aspect to the fifteenth aspect, 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. In the pressure difference determination step S4a, when the filter heating device 45 is in the non-heated state, it is determined whether the temperature detected by the thermometer 52 is less than the first reference pressure difference ΔPb1. Also, in the pressure difference determination step S4a, when the filter heating device 45 is in the heated state, it is determined whether the temperature detected by the thermometer 52 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-heated state, and it is determined in the freezing condition determination steps S3a and S3b that the freezing conditions are 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 filter heating device 45 is instructed to enter the heated state. Also, in the heating control step S5, when the filter heating device 45 is in the heated state, and it is determined in the freezing condition determination steps S3a and S3b that the freezing conditions are not satisfied, and it is determined in the pressure difference determination step S4a that the pressure difference is less than or equal to the second reference pressure difference ΔPb2, the filter heating device 45 is instructed to enter the non-heated state.

[0125] In this aspect, similar to the seventh aspect, it is possible to avoid the heating state and the non-heating state being repeated within a short time even when there is some pressure difference fluctuation.

Explanation of Signs

[0126] GT: Gas turbine 1: Gas turbine rotor 10: Compressor 11: Compressor rotor 11s: Compressor rotor shaft 11b: Compressor blade row 12: Compressor casing 13: Compressor stator blade row 14: Intake air flow control device 14v: Inlet guide vane 14d: Driver 15: Intake casing 25: Intermediate casing 30: Turbine 31: Turbine rotor 31s: Turbine rotor shaft 31b: Turbine moving blade row 32: Turbine casing 33: Turbine stationary blade row 35: Exhaust casing 39: Chimney 40: Intake duct facility 41: Intake duct 42: Intake duct body 42i: Intake port 42o: Intake outlet 43: Louver 44: Filter 45: Filter heating device 46: Compressed air line 47: Compressed air valve 50, 50a, 50b: Anti-freezing control device 51, 51b: Anti-freezing condition parameter detector 52: Thermometer 53: Hygrometer 54: Mist meter 55: Differential pressure gauge 56: First pressure gauge 57: Second pressure gauge 58: Third pressure gauge 59: Downstream thermometer 60, 60a, 60b: Control device body 61: Differential pressure calculator 62: Flow rate calculator 63, 63a: Differential pressure judge 63aa: First differential pressure judge 63ab: Second differential pressure judge 64, 64a, 64b: Anti-freezing condition judge 65, 65a: Temperature judge 65aa: First temperature judge 65ab: Second temperature judge 66, 66a: Humidity judge 66aa: First humidity detector 66ab: Second humidity detector 67b: Mist amount detector 67ba: First mist amount detector 67bb: Second mist amount detector 68: Condition satisfaction detector 68a, 68b: First condition satisfaction detector 69a, 69b: Second condition satisfaction detector 70, 70a: Heating controller 71: ON instruction signal generator 72, 72a: OFF instruction signal generator 73: Instruction signal output unit 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: Upstream side of the axis Dad: Downstream side of the axis Dc: Circumferential direction Dr: Radial direction Dri: Inner side in the radial direction Dro: Outer side in the radial direction Du: Upstream side Dd: Downstream side

Claims

1. An intake duct having an intake port capable of sucking outside air and an intake outlet through which the outside air sucked from the intake port flows out, A filter disposed in the intake duct, A filter heating device capable of heating the filter, In an intake duct facility comprising In an anti-freezing control device for controlling the filter heating device, A freezing condition parameter detector capable of detecting a freezing condition parameter indicating whether ice can adhere to the filter, A differential pressure gauge capable of detecting a pressure difference that is the difference between the pressure on the upstream side, which is on the intake port side of the filter in the intake duct, and the pressure on the downstream side, which is on the intake outlet side of the filter, A control device main body capable of instructing one of a heating state in which the filter is heated and a non-heating state in which the filter is not heated for the filter heating device according to the freezing condition parameter and the pressure difference, Comprising An anti-freezing control device.

2. In the anti-freezing control device according to Claim 1, The freezing condition parameter detector has 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, The freezing condition parameter includes the temperature of the outside air and the humidity of the outside air, The control device main body A freezing condition judge for judging whether the freezing condition parameter satisfies the freezing condition under which ice can adhere to the filter, A differential pressure judge for judging whether the differential pressure is greater than a reference differential pressure, A heating controller for instructing the heating state or the non-heating state for the filter heating device according to the judgment result by the freezing condition judge and the judgment result by the differential pressure judge, Having The freezing condition judge judges that the freezing condition is satisfied on the condition that the temperature detected by the thermometer is lower than a predetermined reference temperature based on the dew point temperature and the humidity detected by the hygrometer is higher than a predetermined reference humidity based on 100% humidity, The heating controller When the filter heating device is in the non-heating state, if the freezing condition judge judges that the freezing condition is satisfied and the differential pressure judge judges that the differential pressure is greater than the reference differential pressure, the heating state is instructed to the filter heating device, When the filter heating device is in the heating state, if the freezing condition determination unit determines that the freezing condition is not satisfied and the pressure difference determination unit determines that the pressure difference is less than or equal to the reference pressure difference, an instruction to set the filter heating device to the non-heating state is issued. Freezing prevention control device.

3. In the freezing prevention control device according to claim 2, 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, the freezing condition determination unit when the filter heating device is in the non-heating state, determines that the freezing condition is satisfied if the temperature detected by the thermometer is less 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 heating state, determines that the freezing condition is not satisfied if the temperature detected by the thermometer is greater than or equal to the second reference temperature or the humidity detected by the hygrometer is less than or equal to the second reference humidity. Freezing prevention control device.

4. In the freezing prevention control device according to claim 2, 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, the freezing condition determination unit determines that the freezing condition is satisfied when the temperature detected by the thermometer is less 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. Freezing prevention control device.

5. In the freezing prevention control device according to claim 4, 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, the reference mist amount has a first reference mist amount and a second reference mist amount less than the first reference mist amount, the freezing condition determination unit when the filter heating device is in the non-heating state, determines that the freezing condition is satisfied if 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 heating state, it is determined that the freezing 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, or the mist amount detected by the mist amount meter is equal to or lower than the second reference mist amount. Freezing prevention control device.

6. In the freezing prevention control device according to claim 2, The pressure difference determination unit maintains the relationship between the flow rate of outside air flowing in the intake duct and the reference pressure difference, and determines the reference pressure difference corresponding to the flow rate of outside air flowing in the intake duct using the relationship. Freezing prevention control device.

7. In the freezing prevention control device according to claim 2, The reference pressure difference has a first reference pressure difference and a second reference pressure difference smaller than the first reference pressure difference. The pressure difference determination unit determines whether 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, determines whether the temperature detected by the thermometer is less than the second reference pressure difference when the filter heating device is in the heating state, The heating controller when the filter heating device is in the non-heating state, if the freezing condition determination unit determines that the freezing condition is satisfied and the pressure difference determination unit determines that the pressure difference is greater than the first reference pressure difference, instructs the filter heating device to enter the heating state, when the filter heating device is in the heating state, if the freezing condition determination unit determines that the freezing condition is not satisfied and the pressure difference determination unit determines that the pressure difference is equal to or less than the second reference pressure difference, instructs the filter heating device to enter the non-heating state. Freezing prevention control device.

8. A freezing prevention control device according to any one of claims 1 to 7, the intake duct, the filter, and the filter heating device. Intake duct facility.

9. The intake duct facility according to claim 8, a gas turbine, comprising 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 drivable by the combustion gas. The filter heating device has a compressed air line capable of guiding a part 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. The control device main body uses an open instruction to the compressed air valve as an instruction for the heating state, and a close instruction to the compressed air valve as an instruction for the non-heating state. Gas turbine facility.

10. An intake duct having an intake port capable of sucking outside air and an intake outlet through which the outside air sucked from the intake port flows out, A filter disposed in the intake duct, A filter heating device capable of heating the filter, In an intake duct facility comprising: In a freezing prevention method for suppressing freezing of the filter, A freezing condition parameter detection step of detecting a freezing condition parameter indicating whether or not the filter is in a state where ice can adhere thereto, A pressure difference detection step of detecting a pressure difference in the intake duct, which is the difference between the pressure on the upstream side, which is the side of the intake port with respect to the filter, and the pressure on the downstream side, which is the side of the intake outlet with respect to the filter, A control step of instructing, according to the freezing condition parameter and the pressure difference, one of a heating state in which the filter is heated and a non-heating state in which the filter is not heated for the filter heating device, A freezing prevention method for executing.

11. In the freezing prevention method according to claim 10, In the freezing condition parameter detection step, as the freezing condition parameter, the temperature and humidity of the outside air at a position upstream of the filter are detected, The control step includes: A freezing condition determination step of determining whether or not the freezing condition parameter satisfies a freezing condition in which ice can adhere to the filter, A pressure difference determination step of determining whether or not the pressure difference is greater than a reference pressure difference, A heating control step of instructing the filter heating device to be in the heating state or the non-heating state according to the determination result in the freezing condition determination step and the determination result in the pressure difference determination step, And includes: In the freezing condition determination step, it is determined that the freezing condition is satisfied on the condition that the temperature detected in the freezing condition parameter detection step is lower than a reference temperature predetermined based on the dew point temperature and the humidity detected in the freezing condition parameter detection step is higher than a reference humidity predetermined based on 100% humidity. In the heating control step, When the filter heating device is in the non-heating state, if it is determined in the freezing condition determination step that the freezing conditions are satisfied and it is determined in the pressure difference determination step that the pressure difference is greater than the reference pressure difference, the filter heating device is instructed to enter the heating state. When the filter heating device is in the heating state, if it is determined in the freezing condition determination step that the freezing conditions are not satisfied and it is determined in the pressure difference determination step that the pressure difference is less than or equal to the reference pressure difference, the filter heating device is instructed to enter the non-heating state. Freezing prevention method.

12. In the freezing prevention method according to claim 11, 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. In the freezing condition determination step, when the filter heating device is in the non-heating state, if the temperature detected in the freezing condition parameter detection step is lower than the first reference temperature and the humidity detected in the freezing condition parameter detection step is higher than the first reference humidity, it is determined that the freezing conditions are satisfied. when the filter heating device is in the heating state, if the temperature detected in the freezing condition parameter detection step is greater than or equal to the second reference temperature or the humidity detected in the freezing condition parameter detection step is less than or equal to the second reference humidity, it is determined that the freezing conditions are not satisfied. Freezing prevention method.

13. In the freezing prevention method according to claim 11, in the freezing condition parameter detection step, the amount of mist in the outside air is detected as the freezing condition parameter. In the freezing condition determination step, if the temperature detected in the freezing condition parameter detection step is lower than the reference temperature, the humidity detected in the freezing condition parameter detection step is higher than the reference humidity, and the amount of mist detected in the freezing condition parameter detection step is greater than a predetermined reference amount of mist, it is determined that the freezing conditions are satisfied. Freezing prevention method.

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

15. In the freezing prevention method according to claim 11, in the pressure difference determination step, using the relationship between the flow rate of outside air flowing in the intake duct and the reference pressure difference, the reference pressure difference corresponding to the flow rate of outside air flowing in the intake duct is determined. Freezing prevention method.

16. In the freezing prevention method according to any one of claims 11 to 15, the reference pressure difference has a first reference pressure difference and a second reference pressure difference that is smaller than the first reference pressure difference. In the pressure difference determination step, when the filter heating device is in the non-heated state, it is determined whether the temperature detected by the thermometer is less than the first reference pressure difference. when the filter heating device is in the heated state, it is determined whether the temperature detected by the thermometer is less than the second reference pressure difference. In the heating control step, when the filter heating device is in the non-heated state, if it is determined in the freezing condition determination step that the freezing conditions are satisfied and it is determined in the pressure difference determination step that the pressure difference is greater than the first reference pressure difference, the filter heating device is instructed to enter the heated state. when the filter heating device is in the heated state, if it is determined in the freezing condition determination step that the freezing conditions are not satisfied and it is determined in the pressure difference determination step that the pressure difference is equal to or less than the second reference pressure difference, the filter heating device is instructed to enter the non-heated state. Freezing prevention method.

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