Hazardous Gas Monitoring System

Abstract

To provide a hazardous gas monitoring system (34).SOLUTION: The hazardous gas monitoring system (34) includes a panel (66) including multiple sensing lines (64). Each sensing line (64) is configured to receive and monitor an air sample. Each sensing line (64) includes a water separator (92) to remove condensed moisture, a coalescing filter (94) disposed downstream of the water separator (92), and a flow and gas monitoring system (96) disposed downstream of the coalescing filter (94). The hazardous gas monitoring system (34) may be used to monitor the presence of hazardous gases within an enclosure (14), such as an enclosure (14) for a turbomachine (68).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates generally to turbomachinery. More particularly, the present disclosure relates to a system for hazardous gas monitoring within an enclosure of a turbomachine. [Background technology]

[0002] Gas turbines and / or generators (e.g., hydrogen-cooled generators) are used to generate electrical power for a variety of applications. To protect the turbines and / or generators from the surrounding environment, or vice versa, the turbines and / or generators may be housed or enclosed in an enclosure with appropriate inlets, exhaust outlets, ventilation mechanisms, and the like. For example, the gas turbines and / or generators may be housed in an enclosure, which can facilitate noise reduction during turbine operation and can suppress environmental hazards, such as the leakage of flammable gases (e.g., fuel gas or hydrogen) into the surrounding environment. A monitoring system may be fluidly coupled to the enclosure to sample the air within the enclosure to detect the presence of harmful gases. Unfortunately, under certain conditions, these monitoring systems can trip the power generating unit (e.g., due to moisture or ice in the sensing lines), causing unnecessary and costly shutdowns. This issue may lead some operators to disable the monitoring system and stop monitoring the enclosure for harmful gases. Summary of the Invention

[0003] Certain embodiments commensurate in scope with the initially claimed subject matter are summarized below. These embodiments are not intended to limit the scope of the claimed embodiments; rather, these embodiments are merely intended to provide a brief summary of possible forms of the present subject matter. Indeed, the embodiments claimed herein may include a variety of forms that may be similar to or different from the embodiments set forth below.

[0004] In a first embodiment, a hazardous gas monitoring system is provided. The hazardous gas monitoring system includes a panel including a plurality of sensing lines. Each sensing line is configured to receive and monitor an air sample. Each sensing line includes a water separator for removing condensed moisture, a drip filter disposed downstream of the water separator, and a flow and gas monitoring system disposed downstream of the drip filter.

[0005] In a second embodiment, a hazardous gas monitoring system is provided. The hazardous gas monitoring system includes a panel including a plurality of sensing lines. Each sensing line is configured to receive and monitor an air sample from an enclosure housing a turbomachine. Each sensing line includes a water separator to remove condensed water, and each of the plurality of sensing lines vents a respective air sample to the atmosphere.

[0006] In a third embodiment, a hazardous gas monitoring system is provided. The hazardous gas monitoring system includes a panel including a first sensing line and a second sensing line. The first and second sensing lines are each configured to receive and monitor an air sample from an enclosure housing a turbomachine. The first and second sensing lines each include a water separator for removing condensed moisture. The water separators of the first and second sensing lines are coupled to a common drain line, and each orifice is disposed between the respective water separator and the common drain line.

[0007] These and other features, aspects, and advantages of the presently disclosed technology will be better understood from the following detailed description when taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts throughout the drawings. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a partial schematic diagram of a turbine system having a gas turbine within a gas turbine enclosure that utilizes a hazardous gas monitoring system for monitoring gas leaks, according to one embodiment. [Figure 2]1 is a schematic diagram of a turbine system utilizing a hazardous gas monitoring system to monitor for gas leaks, according to one embodiment of the present disclosure. [Figure 3] FIG. 1 is a schematic diagram of one embodiment of a hazardous gas monitoring system coupled to multiple enclosures. [Figure 4] 1 is a schematic diagram of one embodiment of a panel (e.g., a hazardous gas detection panel) of a hazardous gas monitoring system. [Figure 5] 1 is a schematic diagram of one embodiment of a sensing line with heat tracing that can be used in embodiments of the present hazardous gas monitoring system. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes one or more specific embodiments of the presently disclosed embodiments. While an effort to provide a concise description of these embodiments may not describe all features of an actual implementation, it is understood that in the development of an actual implementation, such as an engineering or design project, many implementation-specific decisions must be made to achieve the developer's particular objectives, including, for example, meeting system-related and business-related constraints, and that these constraints may vary from implementation to implementation. Moreover, it is understood that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill in the art having the benefit of this disclosure.

[0010] When introducing elements of various embodiments of the presently disclosed embodiments, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0011] As described below, hazardous gas monitoring systems are intended to monitor the presence of hazardous gases (e.g., combustible gases, such as fuel gas (e.g., natural gas) in a gas turbine enclosure or hydrogen in a generator enclosure) within equipment areas (e.g., enclosures) associated with turbomachinery (e.g., gas turbines, generators, etc.). In particular, the hazardous gas monitoring system includes a panel that prevents freezing and moisture buildup. The panel includes multiple sensing lines or conduits that provide air samples from sensing points (where sample probes are located) within one or more enclosures. Each sensing line includes a flow monitor configured to proactively monitor and determine if the sample flow has decreased to an unacceptable level.

[0012] Each sensing line also includes a water separator to remove condensed moisture from the sensing line to reduce the possibility of freezing. To prevent remaining condensed moisture from freezing in the sensing lines, the panels may be placed in a cabinet equipped with a heater and thermostat. Additionally, portions of the sensing lines located outside the panels may have heat tracing thereon to prevent freezing of water in the sensing lines. Preventing moisture buildup or freezing in the monitoring system may increase the reliability of the monitoring system while avoiding costly and unnecessary shutdowns or trips of the power generation system.

[0013] In certain embodiments, at least one sensing line may be inactive (e.g., for sensor replacement or maintenance) while another sensing line remains active to allow the turbomachine to continue operating. Additionally, in some embodiments, the sensing lines may vent the air sample after monitoring to the atmosphere (instead of returning it to the enclosure via an exhaust line) to avoid backpressure that may affect the monitoring system.

[0014] FIG. 1 is a partial schematic diagram of an embodiment of a turbine system 10 enclosed or housed by a turbine enclosure 14 (e.g., a gas turbine enclosure). The turbine system 10 may be a stationary or mobile gas turbine power generation unit. For example, the turbine system 10 may be a stationary unit located at a power generation plant, such as an integrated gasification combined cycle (IGCC) power plant. For example, the turbine system 10 may be a mobile unit transported by a trailer. The turbine system 10 includes a gas turbine or gas turbine engine 12, an enclosure 14 (e.g., a gas turbine enclosure) that houses the gas turbine 12, and a load 16 (e.g., an electrical generator, power generation equipment) driven by the gas turbine 12. The turbine system 10 also includes a combustion air intake system 18 and a ventilation air intake system 20 upstream of the gas turbine 12. The gas turbine enclosure 14 may define a first intake port 22 (e.g., a first air intake port or a turbine air inlet), a second intake port 24 (e.g., a second air intake port or an enclosure ventilation inlet), an air outlet port 26, and an exhaust outlet port 27.

[0015] The first intake port 22 is coupled to a combustion air intake system 18 upstream of the gas turbine 12. The combustion air intake system 18 may include one or more filters for filtering the air supplied to the gas turbine 12. The first intake port 22 channels air into the gas turbine 12. For example, the first intake port 22 may channel air into a compressor of the gas turbine 12. For example, the gas turbine 12 may compress the air from the first intake port 22, mix the air with fuel, and combust the air-fuel mixture to drive one or more turbines.

[0016] The second intake port 24 is coupled to the ventilation air intake system 20. The ventilation air intake system 20 may include one or more filters for filtering air supplied to the enclosure 14 of the gas turbine 12. The ventilation air intake system 20 may supply air into the enclosure 14 via one or more fans 30. The second intake port 24 directs air into the enclosure 14 surrounding the gas turbine 12 to ventilate the enclosure.

[0017] The exhaust outlet port 27 is coupled to a combustion exhaust stack or combustion exhaust duct 28 for ventilating exhaust gases from the gas turbine 12. The air outlet port 26 is coupled to a duct 29 for discharging ventilation air. The gas turbine 12 includes a shaft 32 that extends through the enclosure 14 and couples to the load 16. As described in more detail below, a hazardous gas monitoring system 34 may be utilized to monitor the presence of hazardous gases (e.g., flammable gases) within the enclosure 14. The hazardous gas monitoring system 34 is a suction system that samples air from the enclosure 14, monitors gas concentrations, and determines appropriate safety measures if a hazardous gas is present. As described in more detail below, the hazardous gas monitoring system 34 is configured to prevent moisture buildup or freezing within the monitoring system 34.

[0018] 2 is a schematic diagram of an embodiment of a turbine system 10 utilizing the present hazardous gas monitoring system 34 to monitor for gas leaks. The turbine system (e.g., a gas turbine system, a dual-fuel turbine system) 10 may use liquid or gaseous fuels, such as natural gas and / or hydrogen-rich syngas, to power the turbine system 10. As shown, in each combustor 58 of a plurality of combustors 58, a fuel nozzle 50 (e.g., a multi-tube fuel nozzle) takes a fuel supply 52 from a liquid fuel system 54 or a gaseous fuel system 56 and mixes the fuel with an oxidant (e.g., air, oxygen, oxygen-enriched air, oxygen-reduced air, or any combination thereof), which may be supplied by a compressor 62. In the following description, the oxidant is referred to as air, although any suitable oxidant may be used in the disclosed embodiments.

[0019] Once the fuel and air are mixed, the fuel nozzles 50 distribute the fuel-air mixture in a ratio suitable for optimal combustion, emissions, fuel consumption, and power output. The turbine system 10 may include one or more fuel nozzles 50 located within each of a plurality of combustors 58. The fuel-air mixture is combusted in a chamber within each of the plurality of combustors 58, thereby producing hot, pressurized exhaust gases.

[0020] The multiple combustors 58 direct the exhaust gases through the turbine section (or “expansion turbine”) 40 of the gas turbine 12 toward an exhaust outlet 60 (e.g., to the outlet port 27). As the exhaust gases pass through the turbine section 40, they impart force on turbine blades, causing a drive shaft 32 to rotate along the axis of the turbine system 10. As shown, the shaft 32 may be connected to various components of the gas turbine system 10, including a compressor 62. The compressor 62 also includes blades coupled to the shaft 32. As the shaft 32 rotates, the blades within the compressor 62 also rotate, thereby compressing air from the first (air) inlet port 22 through the compressor 62 and directing it to the fuel nozzles 50 and / or the multiple combustors 58. The fuel nozzles 50 may contain a fuel plenum or may be connected to an end cover with a fuel plenum, which may improve fuel distribution within the nozzles 50 before the fuel-air mixture is discharged to the combustors 58.

[0021] The shaft 32 may also be connected to a load 16, which may be, for example, a vehicular or stationary load such as a generator set at a power plant or a propeller on an aircraft. The load 16 may include any suitable device that may be powered by the rotational output of the turbine system 10.

[0022] As described in more detail below, a hazardous gas monitoring system 34 may be utilized to sample the air within the enclosure 14 to detect, monitor, and evaluate the presence and amount of hazardous gases that may be present in the event of a fuel leak. While the hazardous gas monitoring system 34 has been discussed with respect to the gas turbine system 10, the monitoring system 34 may be utilized with other turbomachinery, such as hydrogen-cooled generators. Additionally, the hazardous gas monitoring system 34 may be utilized to monitor any other type of equipment area or enclosure where it is desirable to monitor for the presence of hazardous gases.

[0023] FIG. 3 is a schematic diagram of the present hazardous gas monitoring system 34 (e.g., a suction-driven system) coupled to multiple enclosures 14. The hazardous gas monitoring system 34 includes multiple sensing lines 64 coupled to the enclosures 14. The number of enclosures 14 coupled to the hazardous gas monitoring system 34 (particularly, the panels 66 of the system 34) may vary (e.g., one, two, three, four, or more). Each enclosure 14 includes a turbomachine 68 (e.g., a gas turbine 12, a generator, or other turbomachine). The turbomachinery 68 may form part of a power plant 69. One or more sensing lines 64 may be coupled to each enclosure 14. As shown, at least two sensing lines 64 are coupled to each enclosure 14. Each sensing line 64 extends within the respective enclosure 14 to a sensing point 70 where an air sample is drawn into the sensing line 64. In certain embodiments, the panels 66 may be disposed within a cabinet 80. Cabinet 80 may include a heater 82 for maintaining sensing line 64 coupled to panel 66 above freezing (0 degrees Celsius) to prevent moisture in sensing line 64 from freezing. Cabinet 80 may also include a thermostat 84 for providing an indication of the temperature within cabinet 80.

[0024] The hazardous gas monitoring system 34 includes a controller 72 communicatively coupled to a flow and gas monitoring system 96 ( FIG. 4 ) for each sensing line 64. In certain embodiments, the controller 72 is communicatively coupled (e.g., transfers data, receives and provides instructions) with various components and systems of a service platform 74 (e.g., a cloud computing service, a distributed control system) and / or the turbomachine 68 via a wired or wireless network or communication system. In some embodiments, the controller 72 may be part of the service platform 74. The controller 72 includes a processor 76 and a memory 78 (e.g., a non-transitory computer-readable medium / memory circuit) communicatively coupled to the processor 76, for storing one or more instruction sets (e.g., processor-executable instructions) implemented to perform operations related to the hazardous gas monitoring system 34 and / or the turbomachine 68.

[0025] For example, the operations may involve monitoring the sample flow within each detection line 64, adjusting the temperature within the cabinet 80 via the heater 82, adjusting the temperature of heat tracing of the portion of the detection line 64 outside the panel 66 (discussed further herein), monitoring the presence of a hazardous gas within the air sample, and / or providing action (e.g., safety action, such as shutting down an individual turbomachine 68 or providing a perceptible warning to a user) in response to detecting an actionable concentration or volume of a hazardous gas.

[0026] More specifically, memory 78 may include volatile memory, such as random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM), an optical drive, a hard disk drive, or a solid-state drive. Additionally, processor 76 may include one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), one or more general-purpose processors, or any combination thereof. Furthermore, the term "processor" is not limited to only integrated circuits referred to in the art as processors, but rather refers broadly to computers, processors, microcontrollers, microcomputers, programmable logic controllers, application-specific integrated circuits, and other programmable circuits.

[0027] For example, memory 78 may store various limits or ranges for parameters of the sample stream in sensing line 64 (e.g., flow rate, flow velocity, volumetric flow rate, etc.), temperatures on the sensing lines within cabinet 80 or outside the cabinet, and / or hazardous gas concentrations (and associated upper and lower explosive limits). For example, memory 78 may store information entered by an operator or user (e.g., via controller 72 and / or service platform 74). Information may be collected via flow and gas monitoring system 96 ( FIG. 4 ) for each sensing line 64, thermostat 84, or other equipment (e.g., a temperature sensor providing the ambient temperature of monitoring system 34).

[0028] FIG. 4 is a schematic diagram of one embodiment of a panel 66 (e.g., a hazardous gas monitoring panel) of a hazardous gas monitoring system 34. The panel 66 includes a panel wall 86. The panel wall 86 includes a plurality of sensing lines 64. As shown, the panel wall 86 includes two sensing lines 64 (e.g., sensing lines 88, 90). As noted above, the number of sensing lines 64 associated with the panel 66 may vary (e.g., one, two, three, four, or more). As shown, the sensing lines 88, 90 are associated with sensing points 1 and 2 from which respective air samples are drawn. Sensing points 1 and 2 may be located in the same enclosure (e.g., one housing turbomachinery) or in different enclosures. In certain embodiments, each enclosure may include two or more sensing points (and associated sensing lines 64) coupled to the panel 66.

[0029] Each sensing line 64 includes a water separator 92, a droplet filter or coalescer 94, and a flow and gas monitoring system 96 located downstream of the coalescer 94. The water separator 92 removes condensed water from the sensing line 64. The coalescer 94 further separates the water from the sensing line 64. The flow and gas monitoring system 96 includes a flow indicator 98, a flow monitor 100, and one or more gas sensors 102. The flow and gas monitoring system 96 may be communicatively coupled to a controller (e.g., controller 72 of FIG. 3). The flow indicator 98 (e.g., a ball-type sight flow indicator) provides a visual indication of the sample flow in the sensing line 64. The flow monitor 100 includes one or more sensors (e.g., a flow meter, an ultrasonic flow meter, etc.) and circuitry (e.g., processing and memory circuitry) for detecting a parameter (e.g., flow rate, volumetric flow rate, etc.) of the sample flow in the respective sensing line and determining whether the parameter is at an undesirable level (e.g., out of range, below a specified limit). One or more gas sensors 102 are utilized to detect the presence of harmful gases in the sample stream. The one or more gas sensors 102 may include a microstructured gas sensor, a flow infrared point sensor, an infrared camera, and / or an ultrasonic sensor. The one or more gas sensors 102 may be capable of detecting one or more specific gases (e.g., natural gas, hydrogen, etc.). As shown in FIG. 4, the flow monitor 100 is positioned downstream of the flow indicator 98, and the one or more gas sensors 102 are positioned downstream of both the flow indicator 98 and the flow monitor 100. In certain embodiments, the flow indicator 98, the flow monitor 100, and the one or more gas sensors 102 may be positioned in a different order.

[0030] As shown in FIG. 4 , at the coalescer 94, each sensing line 64 is split into a flow and gas monitoring line 104 and a drain line 106. The air sample to be monitored flows through the flow and gas monitoring system 96 along the flow and gas monitoring line 104, and any moisture separated from the air sample flows along the drain line 106. An orifice 108 (e.g., a flow-restricting orifice) is positioned along the flow and gas monitoring line 104 downstream from the flow and gas monitoring system 96. An orifice 110 (e.g., a flow-restricting orifice) is also positioned along the drain line 106. The orifices 108, 110 are sized to provide an optimal division and / or pressure drop between the various lines. The flow and gas monitoring line 104 and the drain line 106 rejoin downstream of the orifices 108, 110. Downstream of the junction of the respective flow and gas monitoring lines 104 and drain line 106 of the sensing lines 88, 90, the sensing lines 88, 90 join to eject the air sample into the atmosphere through an ejector 118.

[0031] The separated moisture from the water separators 92 for each of the sensing lines 88, 90 flows to a common drain line 112. Orifices 114, 116 (e.g., flow-restricting orifices) are positioned between each of the water separators 92 and the common drain line 112. The orifices 114, 116 are sized to provide optimal division and / or pressure drop between the various lines. The common drain line 112 ejects moisture from the air sample through separate ejectors 120.

[0032] To facilitate the ejection (e.g., by suction) of the sample from the ejectors 118, 120 to the atmosphere, instrument air is supplied to each of the ejectors 118, 120 from an instrument air supply 122 via an air line 124. Venting the air sample to the atmosphere (instead of returning it to the enclosure via an exhaust line) prevents back pressure from building up and disrupting flow within the system.

[0033] In certain embodiments, to allow the turbomachine (e.g., gas turbine or generator) to continue operating, at least one sensing line 64 (e.g., sensing line 88) may be inactive while another sensing line 64 (e.g., sensing line 90) remains active, thereby allowing replacement or maintenance of the sensor in sensing line 88 while the other sensing line 90 continues to monitor for the presence of harmful gases within the enclosure.

[0034] 5 is a schematic diagram of one embodiment of a sensing line 64 having heat traces 126. The heat traces 126 are disposed on a conduit wall 128 of the sensing line 64. The heat traces 126 can maintain or increase the temperature of the conduit wall 128 to maintain the temperature of the sensing line 64 above freezing (0 degrees Celsius) and prevent moisture from freezing within the sensing line 64. In certain embodiments, each heat trace 126 can take the form of an electric heating element in physical contact along the length of the conduit wall 128. In certain embodiments, the heat traces 126 can be controlled by a controller (e.g., controller 72 of FIG. 3 ).

[0035] Technical effects of the disclosed embodiments include providing a hazardous gas monitoring system including a panel coupled to a plurality of sensing lines, the plurality of sensing lines being coupled to one or more enclosures (e.g., enclosures housing turbomachinery). The panel includes features for avoiding moisture buildup and freezing within the sensing lines. Preventing moisture buildup or freezing within the monitoring system can increase the reliability of the monitoring system while avoiding costly and unnecessary shutdowns or trips of the power generation system.

[0036] This specification uses examples to describe the present embodiments, including the best mode. The examples also enable any person skilled in the art to practice the embodiments disclosed herein, including making and using any device or system, and performing any incorporated methods. The patentable scope of the embodiments disclosed herein is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ in material way from the literal language of the claims. [Explanation of symbols]

[0037] 1 detection point 2 Detection points 10 Gas Turbine System 12 Gas turbines, gas turbine engines 14 Gas Turbine Enclosure 16 Load 18 Combustion air intake system 20 Ventilation air intake system 22 Intake port 24 intake port 26 Air Outlet Port 27 Exhaust outlet port 28 Combustion exhaust stack or combustion exhaust duct 29 Duct 30 fans 32 Drive shaft 34 Harmful Gas Monitoring System 40 Turbine section 50 fuel nozzle 52 Fuel supply 54 Liquid Fuel System 56 Gaseous Fuel System 58 Combustor 60 exhaust outlet 62 Compressor 64 detection lines 66 Panels 68 Turbomachinery 69 Power Plant 70 detection points 72 Controller 74 Service Platform 76 processors 78 memory 80 Cabinet 82 Heater 84 Thermostat 86 Panel Wall 88 Detection Line 90 detection line 92 Water separator 94 Drip filter or coalescer 96 Flow and Gas Monitoring Systems 98 Flow Indicator 100 Flow Monitors 102 Gas Sensor 104 Flow and Gas Monitoring Lines 106 Drainage Line 108 Orifice 110 Orifice 112 Drainage line 114 Orifice 116 Orifice 118 Ejector 120 Ejector 122 Instrument air supply source 124 Air Line 126 Heat Tracing 128 Conduit wall

Claims

1. A panel (66) comprising a panel wall and a plurality of detection lines (64) disposed on and extending along the panel wall, each detection line (64) configured to receive and monitor an air sample, and each detection line (64) of the plurality of detection lines (64) a water separator (92) for removing condensed water from the air sample; a drip filter (94) disposed downstream of the water separator (92); a flow and gas monitoring system (96) located downstream of said droplet filter (94); a panel (66) Equipped with The water separator (92), the droplet filter (94), and the flow and gas monitoring system (96) are disposed in the panel wall, and the flow and gas monitoring system (96) includes a flow indicator configured to provide a visual indication of the sample flow of the air sample flowing through each detection line (64), and a gas sensor configured to detect the presence of a harmful gas in the sample flow.

2. The hazardous gas monitoring system (34) of claim 1, wherein each sensing line (64) of the plurality of sensing lines (64) is divided into a flow and gas monitoring line (104) and a drain line (106).

3. The hazardous gas monitoring system (34) of claim 2, wherein the division between the flow and gas monitoring line (104) and the drain line (106) occurs at the droplet filter (94).

4. 3. The hazardous gas monitoring system (34) of claim 2, wherein in each detection line (64) of the plurality of detection lines (64), a first flow restriction orifice (108) is positioned along the flow and gas monitoring line (104) downstream of the flow indicator and the gas sensor of the flow and gas monitoring system (96) to restrict sample flow, and a second flow restriction orifice (110) is positioned along the drain line (106) to restrict drain flow.

5. The hazardous gas monitoring system (34) of claim 1, wherein the water separator (92) of each of at least two of the plurality of sensing lines (64) is coupled to a common drain line (112).

6. 6. The harmful gas monitoring system (34) of claim 5, wherein for the at least two detection lines (64) of the plurality of detection lines (64), a respective flow restriction orifice (114, 116) is disposed between the respective water separator (92) and the common drain line (112).

7. The hazardous gas monitoring system (34) of claim 5, wherein the common drain line (112) is coupled to a first ejector (120) for discharging a drain stream to atmosphere.

8. 8. The hazardous gas monitoring system (34) of claim 7, wherein the at least two sensing lines (64) of the plurality of sensing lines (64) are coupled to a second ejector (118) for ejecting a sample stream to the atmosphere.

9. 9. The hazardous gas monitoring system (34) of claim 8, wherein an instrument air supply (122) is fluidly coupled to both the first and second ejectors (118, 120) to facilitate evacuation.

10. 2. The harmful gas monitoring system (34) of claim 1, configured to utilize a first detection line (64) of the plurality of detection lines (64) while a second detection line (64) of the plurality of detection lines (64) is stopped or disconnected.

11. A harmful gas monitoring system (34) as described in claim 5, wherein the collection filters (94) of each of at least two detection lines (64) of the plurality of detection lines (64) are connected to a drain line (106) different from the common drain line (112).

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