WO2019077845A1

WO2019077845A1 - Gas sampling probe and flue exhaust gas analysis device provided with same

Info

Publication number: WO2019077845A1
Application number: PCT/JP2018/029002
Authority: WO
Inventors: 亮田辺
Original assignee: 株式会社島津製作所
Priority date: 2017-10-16
Filing date: 2018-08-02
Publication date: 2019-04-25
Also published as: JPWO2019077845A1; JP6973497B2; CN111226104B; CN111226104A

Abstract

This probe (10) comprises a case (21) provided with an opening part (24A) for introducing sampling gas, a filter (30) that is accommodated in the case (21) and removes dust included in the sampling gas introduced into the case (21), and a heater unit (40) for heating the filter (30). The heater unit (40) comprises a first heater (41) that is intended to be constantly energized, a second heater (42) that is a heater for heating capacity adjustment, and a thermostat (50) for switching the second heater (42) on and off according to the temperature of the filter (30). Through the switching on and off of the second heater (42) by the thermostat (50), the heater unit (40) is capable of keeping the temperature of the sampling gas that passes through the filter (30) at a temperature at which the condensation of the sampling gas is suppressed.

Description

Gas sampling probe and flue gas analyzer equipped with the same

The present invention relates to a gas sampling probe used when sampling and analyzing flue gas discharged from a thermal power plant, an incinerator, a boiler or the like, and a flue gas analyzer provided with the same.

In the conventional gas sampling probe, a cylindrical case which is easy to attach to a chimney or the like is usually used as a main body, and a cylindrical filter is provided coaxially in the case. In addition, a hole for sampling gas introduction is provided on the chimney side of the case, a sealing member is attached to the opening on the other end side of the case, and dust is removed from the outlet hole provided on this sealing member Piping for leading out the sampling gas is connected. And it is comprised so that the sampling gas derived | led-out via this piping may be supplied to a gas analyzer etc. Patent Document 1 discloses an example of a conventional gas sampling probe.

By the way, in the case of this type of gas sampling probe, the temperature of the sampling gas passing through the filter is maintained above the acid dew point (about 150 ° C.) of the flue gas in order to suppress the clogging of the filter by the drain. Further, for this purpose, a heater is provided which heats the filter from the outer surface of the case through the sampling gas inside. In addition, when the sampling gas is heated more than necessary by the heater, the case where it exceeds the use limit temperature (specifically, 180 ° C.) of the member constituting the gas sampling probe, for example, the sealing member is considered. Therefore, the heater is on / off controlled to keep the sampling gas in the range of 150 ° C. to 180 ° C.

The conventional gas sampling probe controls the heater on / off by a thermostat that detects the temperature of the outer surface of the case. The thermostat is configured to cut off the heater circuit directly, so that the gas sampling probe alone can turn the heater on and off without providing a control box.

Japanese Patent Application Laid-Open No. 10-48107

By the way, in the conventional gas sampling probe, since the entire heater is on / off controlled by the thermostat, the life of the thermostat is short, and there is a problem that it is troublesome to replace the thermostat. In addition, when replacement of the thermostat is delayed, drain may adhere to the filter, which may cause clogging. For this reason, it has been desired to extend the life of the thermostat.

An object of the present invention is to provide a gas sampling probe with an extended life of a thermostat and a flue gas analyzer provided with the same.

(1) One mode of the gas sampling probe according to the present invention is a case provided with an opening for introducing a sampling gas, a filter which is contained in the case and removes dust contained in the sampling gas introduced into the case A gas sampling probe having a heater unit for heating the filter, wherein the heater unit is a first heater that is a heater for constant current application, a second heater that is a heater for adjusting the heating capacity, and the filter A thermostat for performing on / off control of the second heater according to the temperature of the second heater, the heater unit controls the temperature of the sampling gas passing through the filter by the on / off control of the second heater by the thermostat; Configured to maintain the temperature at which It has been.

According to such a configuration, the current flowing only to the second heater of the first heater and the second heater flows to the thermostat. For this reason, compared with the case where the total value of the current which flows into each of the 1st heater and the 2nd heater flows into a thermostat, the current value which flows into a thermostat can be decreased. Further, since the first heater is constantly energized and only the second heater is on / off controlled, the heater capacity to be on / off controlled can be reduced as compared with the conventional case. For this reason, the temperature decrease rate of the filter when the second heater is off becomes low, and the on / off cycle of the thermostat becomes long. This extends the life of the thermostat and reduces the hassle of replacing the thermostat. In addition, even when the thermostat does not operate properly, the filter is heated by the first heater, so clogging of the filter is unlikely to occur.

(2) According to an example of the gas sampling probe, the combined heating capacity of the first heater and the second heater is the sampling of the temperature of the sampling gas passing through the filter at the lower limit of use of the ambient temperature. The heating ability of the first heater at the time of non-energization of the second heater is set to the ability to be held above the acid dew point of the gas, the member constituting the gas sampling probe at the upper limit of use of the ambient temperature. It is set to the ability to hold below the use limit temperature of the member.

According to such a configuration, the capacity of the first heater and the capacity of the second heater can be set appropriately, and the shortage of the heating capacity of the heater unit at the lower limit of use of the ambient temperature is suppressed. In addition, excessive heating capacity of the heater unit at the upper limit of use of the ambient temperature is also suppressed.

(3) According to an example of the gas sampling probe, each of the first heater and the second heater is a heater that covers a part of the outer surface of the case, and the first heater is a lower portion of the case. The second heater is attached so as to cover, and the second heater is attached in combination so as to cover the upper part of the case.

According to such a configuration, the convection of the sampling gas is more likely to occur inside the case when the second heater is not energized, as compared to the case where the first heater is attached to the upper portion of the case. The filter can be heated uniformly.

(4) According to an example of the gas sampling probe, the thermostat is attached to the side of the second heater in the upper part of the case.
According to such a configuration, the thermostat can appropriately control on / off of the second heater according to the temperature change of the filter, as compared with the case where the thermostat is mounted at another place.

(5) One mode of the flue gas analyzer according to the present invention comprises the gas sampling probe according to any one of the above (1) to (4).
According to such a configuration, the life of the thermostat used for the gas sampling probe is extended, and the trouble of replacing the thermostat is reduced.

The gas sampling probe according to the present invention and the flue gas analyzer including the same increase the life of the thermostat and prevent the clogging of the filter.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram which shows the state which attached the flue exhaust gas analyzer of embodiment to the flue. FIG. 2 is a cross-sectional view of the gas sampling probe of FIG. The circuit diagram of the electric circuit of the gas sampling probe of FIG. The time chart which shows an example of operation | movement of the gas sampling probe of FIG.

Embodiment
The configuration of the flue gas analyzer 1 will be described with reference to FIG.
The flue gas analyzer 1 is connected to the flue F connecting the boiler B and the chimney C in, for example, a power plant etc., and is a specific component contained in the flue gas discharged from the boiler B via the flue F It is an apparatus which measures the density | concentration of a measurement object component which is.

The flue gas analysis apparatus 1 includes a gas sampling probe (hereinafter, “probe 10”), a pump (not shown), a gas analyzer 70, a plurality of pipes P, and a power supply 60 (see FIG. 3). The power source 60 is an AC power source or a DC power source, and is electrically connected to each device so as to supply power to the probe 10, the pump, the gas analyzer 70, and the like. The probe 10 is installed in the flue F so that the flue gas flowing in the flue F can be sampled as a sampling gas. In one example, the probe 10 is installed on the side or upper part of the outer surface of the flue F. The pump is provided downstream of the probe 10. The downstream side is the downstream side in the direction in which the sampling gas flows. The pump and the probe 10 are connected by a pipe P. A gas analyzer 70 is provided downstream of the pump. The pump and the gas analyzer 70 are connected by a pipe P. In one example, the gas analyzer 70 is installed near the flue F on an installation surface (not shown) such as the ground.

The gas analyzer 70 is an analyzer using a method such as an infrared absorption method or a chemiluminescence method. In one example, the gas analyzer 70 is a double luminous flux analyzer using an infrared absorption method. When the pump is driven, sampling gas is sampled through the probe 10, and the sampled sampling gas flows into the gas analyzer 70. The gas analyzer 70 measures the concentration of the measurement target component contained in the sampling gas. An example of the component to be measured is sulfur dioxide.

The configuration of the probe 10 will be described with reference to FIG.
The probe 10 has a body 20 and a filter 30. The main body 20 includes a case 21, a flange 23, an inlet-side connection portion 24, and a outlet-side connection portion 25. The case 21 forms a passage 21A through which the sampling gas collected from the flue F flows. The shape of the case 21 is cylindrical. The case 21 is provided with an opening 24A for introducing a sampling gas. The flange 23 is fixed to the upstream end of the case 21. In one example, the case 21 is connected to the flue F by fixing the flange 23 to the flue F by a connecting member (not shown) such as a bolt. The probe 10 is connected to the flue F such that the central axis of the case 21 extends in the horizontal direction.

The introduction side connection portion 24 is a member provided on the upstream side portion in the case 21 in order to fix the connection pipe PF connected to the flue F. The end of the connection pipe PF is inserted into the opening 24A formed in the introduction side connection 24. The passage in the flue F and the passage 21A in the case 21 communicate with each other by the connection pipe PF connected to the introduction side connection portion 24. The outlet side connection portion 25 is a member provided on the downstream side in the case 21 in order to fix the pipe P connecting the probe 10 and the pump. The end of the pipe P is inserted into an outlet hole 25A formed in the outlet connection 25. The passage 21A in the case 21 and the pump communicate with each other by the pipe P connected to the lead-out side connection portion 25.

The filter 30 is coaxially mounted in the case 21 so that, for example, the sampling gas introduced into the case 21 is introduced from the outer peripheral side to the inner peripheral side. In one example, the filter 30 is accommodated between the lead-in connection part 24 and the lead-out connection part 25 in the case 21. The shape of the filter 30 is cylindrical. The filter 30 is, for example, a metal mesh filter. An example of the material which comprises the filter 30 is stainless steel. The filter 30 removes dust contained in the sampling gas introduced into the case 21. Since the sampling gas from which dust has been removed by the filter 30 flows into the gas analyzer 70, the concentration of the component to be measured is accurately measured.

The probe 10 further includes a heater unit 40. The heater unit 40 is provided to heat the filter 30. In one example, the heater unit 40 is provided on the outer surface 22 of the case 21. The heater unit 40 generates heat by the current supplied from the power supply 60. The heat generated from the heater unit 40 is transferred to the filter 30 via the case 21 and the sampling gas flowing through the passage 21A. Therefore, the filter 30 is indirectly heated by the heat of the heater unit 40.

The heater unit 40 includes a first heater 41, a second heater 42, and a thermostat 50. The first heater 41 is a heater for constant current conduction. The second heater 42 is a heater for adjusting the heating capacity. The thermostat 50 performs on / off control of the second heater 42 according to the temperature of the filter 30 (hereinafter, “filter temperature”). The first heater 41, the second heater 42, and the thermostat 50 are electrically connected to the power supply 60 (see FIG. 3). In one example, the entire probe 10 is covered with a case (not shown) or the like so that the

heaters

41 and 42 and the thermostat 50 are not exposed to the outside. An example of the material which comprises a case is stainless steel.

The first heater 41 and the second heater 42 are heaters that respectively cover a part of the outer surface 22 of the case 21. In one example, each

heater

41, 42 is a partial cylindrical band heater. The first heater 41 is attached to cover the lower part 22B of the outer surface 22 of the case 21, and the second heater 42 is attached in combination to cover the upper part 22A of the outer surface 22 of the case 21. There is. In one example, the

heaters

41 and 42 are fixed to the case 21 by connecting the

heaters

41 and 42 with a connecting member (not shown) such as a bolt. The

heaters

41 and 42 fixed to the case 21 constitute a cylinder covering the outer surface 22 of the case 21.

The thermostat 50 is configured to be able to switch the electrical connection between the second heater 42 and the power supply 60 in accordance with the temperature of the outer surface 22 of the case 21. The temperature of the outer surface 22 of the case 21 correlates with the filter temperature. An example of the thermostat 50 is a bimetal thermostat. The thermostat 50 is provided, for example, on the outer surface 22 of the case 21 so as to be adjacent to the second heater 42. In one example, the thermostat 50 is attached to the side of the second heater 42 in the upper portion 22A of the case 21. According to such a configuration, the thermostat 50 can appropriately control the on / off of the second heater 42 according to the temperature change of the filter 30 as compared with the case where the thermostat 50 is attached at another place.

The electrical circuit of the probe 10 will be described with reference to FIG.
The heater unit 40 is, for example, a parallel circuit in which a second heater 42 and a thermostat 50 are connected in series, and the series circuit and the first heater 41 are connected in parallel. The heater unit 40 is configured to be able to maintain the temperature of sampling gas passing through the filter 30 (hereinafter referred to as “passing gas temperature”) at a temperature at which condensation of the sampling gas is suppressed by on / off control of the second heater 42 by the thermostat 50. ing. Specifically, the heater unit 40 is configured to be able to maintain the passing gas temperature above the acid dew point (about 150 ° C.) of the sampling gas by the on / off control of the second heater 42 by the thermostat 50. In one example, the heater unit 40 regulates the filter temperature such that the passing gas temperature is maintained above the acid dew point. Further, the heater unit 40 is configured to be capable of holding the members constituting the probe 10 at a temperature equal to or lower than the use limit temperature (about 180 ° C.) of the members. When the temperature of the member constituting the probe 10 is maintained at or below the use limit temperature, the deterioration by the heat of the member constituting the probe 10 is hardly promoted. The member which comprises the probe 10 contains the sealing member etc. which are accommodated in case 21. As shown in FIG.

The combined heating capacity of the first heater 41 and the second heater 42 is set to the ability to hold the passing gas temperature above the acid dew point at the lower limit of use of the ambient temperature around the probe 10 (hereinafter referred to as "ambient temperature"). It is done. The total heating capacity is a heating capacity obtained by combining the heating capacity of the first heater 41 and the heating capacity of the second heater 42. The use lower limit value of the ambient temperature is the lower limit temperature at which the probe 10 can operate normally. An example of the lower limit of use is -10 ° C. The heating ability of the first heater 41 when the second heater 42 is not energized is set to the ability to keep the member constituting the probe 10 at or below the use limit temperature of the member at the upper limit of use of the ambient temperature. . The use upper limit value of the ambient temperature is the upper limit temperature at which the probe 10 can operate normally. An example of the upper limit of use is 50.degree. According to such a configuration, the capacity of the first heater 41 and the capacity of the second heater 42 can be appropriately set, and the heating capacity of the heater unit 40 may be insufficient at the lower limit of use of the ambient temperature. It is suppressed and it is also suppressed that the heating capability of the heater unit 40 becomes excessive in the use upper limit value of ambient environment temperature.

The thermostat 50 is configured such that the contact 51 is connected and disconnected in accordance with the temperature of the outer surface 22 of the case 21. When the contact 51 of the thermostat 50 is connected, the first heater 41 and the second heater 42 are electrically connected to the power supply 60. When the filter temperature rises to the first temperature TA in the state where the contact 51 is connected, the contact 51 is disconnected. An example of the first temperature TA is 180 ° C. When the contact 51 of the thermostat 50 is disconnected, the electrical connection between the second heater 42 and the power supply 60 is disconnected. The first heater 41 is electrically connected to the power supply 60 both when the contact 51 is connected and when the contact 51 is disconnected. If the filter temperature drops to a second temperature TB lower than the first temperature TA while the contact 51 is disconnected, the contact 51 is connected again. An example of the second temperature TB is 150.degree. FIG. 3 shows a state in which the contact 51 of the thermostat 50 is disconnected.

The operation of the probe 10 will be described with reference to FIG.
Before time t11, the probe 10 is not used. At this time, the filter temperature is lower than the first temperature TA and the second temperature TB, and the contact 51 of the thermostat 50 is connected. At time t11, for example, the switch of the power supply 60 is switched from off to on, whereby energization of the

heaters

41 and 42 and the gas analyzer 70 is started. The heat generated from the

heaters

41 and 42 is transferred to the filter 30 via the case 21 and the sampling gas flowing through the passage 21A. Therefore, the filter temperature rises. When the filter temperature rises to a predetermined temperature, energization of the pump of the flue gas analyzer 1 is started. One example of the predetermined temperature is the second temperature TB. By driving the pump, the gas flowing through the flue F is introduced into the case 21 through the opening 24A.

At time t12, as the filter temperature rises, the filter temperature reaches the first temperature TA, and the contact 51 of the thermostat 50 is disconnected. Therefore, the heat generation of the second heater 42 is stopped, and the amount of heat supplied from the heater unit 40 to the case 21 is reduced. On the other hand, since the current flows to the first heater 41 in the same manner as before the filter temperature reaches the first temperature TA, the first heater 41 continuously heats the filter 30. For this reason, the filter temperature gently decreases after the contact point 51 is disconnected.

At time t13, the filter temperature reaches the second temperature TB as the filter temperature decreases, and the contact 51 of the thermostat 50 is connected again. Therefore, the second heater 42 generates heat again, and the amount of heat supplied from the heater unit 40 to the case 21 increases. After time t13, the filter 30 is heated by the

heaters

41 and 42 in the same manner as in the period from time t11 to t12, and the filter temperature rises. Thereafter, the same condition as that in the period from time t12 to t13 is repeated.

According to the probe 10, as described above, since the first heater 41 generates heat even when the second heater 42 does not generate heat, the rate of decrease of the filter temperature, which decreases with the stop of the heat generation of the second heater 42, decreases. For this reason, the on-off cycle of the thermostat 50 becomes long, and the life of the thermostat 50 becomes long. Further, since the current flowing only to the second heater 42 of the first heater 41 and the second heater 42 flows to the thermostat 50, the total value of the currents flowing to the first heater 41 and the second heater 42 is the thermostat The current value flowing to the thermostat 50 can be reduced as compared to the case where the current flows to 50. Therefore, the life of the thermostat 50 is extended. Thus, since the life of the thermostat 50 is extended, the trouble of replacement of the thermostat 50 is reduced.

Further, even when the thermostat 50 does not operate normally, the filter 30 is heated by the first heater 41, so clogging of the filter 30 hardly occurs. In addition, since the first heater 41 for constant current conduction is provided at the lower portion 22B of the case 21, the inside of the case 21 is disconnected even when the contact 51 of the thermostat 50 is disconnected or the thermostat 50 does not operate normally. The sampling gas flowing on the side of the lower portion 22B is always heated by the first heater 41. As compared with the case where the first heater 41 is attached to the upper portion 22A of the case 21, convection of the sampling gas is more likely to occur in the case 21, so that the sampling gas and the filter 30 can be uniformly heated. For this reason, the possibility that the temperature of sampling gas and filter 30 will fall locally is reduced, and clogging of filter 30 hardly occurs.

(Modification)
The above embodiment is an example of the gas sampling probe and the flue gas analyzer including the same according to the present invention, and is not intended to limit the configuration. The present invention can take the form which the modification of an embodiment shown below, for example besides the embodiment, and the at least two modifications which do not contradict each other were combined.

The mounting positions of the first heater 41 and the second heater 42 can be arbitrarily changed. In the first example, the first heater 41 is attached so as to cover the upper portion 22A of the outer surface 22 of the case 21 and the second heater 42 covers the lower portion 22B of the outer surface 22 of the case 21. It is attached in combination. In the second example, the first heater 41 is attached so as to cover one side of the outer surface 22 of the case 21, and the second heater 42 is the other side of the outer surface 22 of the case 21. In combination to cover the In the third example, at least one of the first heater 41 and the second heater 42 is attached to the inner circumferential surface of the case 21. According to this example, the filters 30 are heated by the driving of the

heaters

41 and 42 through the sampling gas flowing through the passage 21A of the case 21. In the fourth example, at least one of the first heater 41 and the second heater 42 is attached to the filter 30 or a member in the vicinity thereof. According to this example, the filter 30 is directly heated by the drive of the

heaters

41 and 42. The

heaters

41 and 42 in the third and fourth examples may constitute heaters other than the band heater.

The heater unit 40 further includes one or more other heaters in addition to the first heater 41 and the second heater 42. In this example, the heater unit 40 is preferably configured such that another heater and the thermostat 50 are connected in parallel.

The electric circuit relating to the heater unit 40 can be arbitrarily changed. In the first example, the first heater 41 is electrically connected to the power supply 60, and the second heater 42 and the thermostat 50 are electrically connected to a power supply different from the power supply 60. In the second example, the first heater 41 is electrically connected to a power supply different from the power supply 60, and the second heater 42 and the thermostat 50 are electrically connected to the power supply 60.

The mounting position of the thermostat 50 can be arbitrarily changed. In the first example, the thermostat 50 is attached to the outer surface 22 of the case 21 upstream of the second heater 42. In the second example, the thermostat 50 is provided adjacent to the first heater 41 on the outer surface 22 of the case 21.

DESCRIPTION OF SYMBOLS 1: 1 flue gas exhaust gas analyzer 10: Gas sampling probe 21: Case 22: Outer surface 22A: Upper part 22B: Lower part 24A: Opening part 30: Filter 40: Heater unit 41: 1st heater 42: 2nd heater 50: thermostat

Claims

A case with an opening for introducing sampling gas,
A filter which is contained in the case and removes dust contained in the sampling gas introduced into the case;
A gas sampling probe having a heater unit for heating the filter;
The heater unit includes a first heater which is a heater for constant current conduction, a second heater which is a heater for adjusting a heating capacity, and a thermostat which controls the second heater according to the temperature of the filter.
The heater unit is configured to be able to maintain the temperature of the sampling gas passing through the filter at a temperature at which condensation of the sampling gas is suppressed by on / off control of the second heater by the thermostat. .
The combined heating capacity of the first heater and the second heater is set to an ability to maintain the temperature of the sampling gas passing through the filter at or above the acid dew point of the sampling gas at the lower limit of use of the ambient temperature. ,
The heating ability of the first heater when the second heater is not energized is set to the ability to keep the member constituting the gas sampling probe at or below the use limit temperature of the member at the upper limit of use of the ambient temperature. The gas sampling probe according to claim 1.
Each of the first heater and the second heater is a heater which covers a part of the outer surface of the case,
The gas sampling probe according to claim 1, wherein the first heater is attached so as to cover the lower part of the case, and the second heater is attached in combination so as to cover the upper part of the case.
The gas sampling probe according to claim 3, wherein the thermostat is attached to a side of the second heater at an upper portion of the case.
A flue gas analyzer comprising the gas sampling probe according to any one of claims 1 to 4.