JP3687656B2 - Gas flow measuring device by differential pressure - Google Patents

Description

【００２６】
本実施例のツインヒートコンダクション管にて同様の試験を行った結果を図４に示す。
試験に用いたツインヒートコンダクション管の仕様は下記の通りである。
［１］配管サイズ ：２０Ａ
［２］配管材質 ：ＳＵＳ３０４ＴＰ−Ａ
［３］配管肉厚 ：２ｍｍ
［４］配管相互間 ：溶着接続 ＋ 熱伝導剤充填
［５］保温材 ：ポリエスチレン整形品
［６］保温厚さ ：３０ｍｍ
［７］保温空間処理 ：定ピッチグラスウール充填
［８］保温外面使用 ：ＳＵＳ板金仕上げ
［９］日射模擬 ：垂直投射
試験結果を表２に示す。
【００２７】
【表２】

【００２８】
すなわち、高圧側導圧配管１１と低圧側導圧配管１２の内部における気体温度はほとんど同一となって温度差による流れ相当分の差圧はほとんど計測されない。
【００２９】
【発明の効果】
以上のように、本発明によれば、高圧側導圧配管と低圧側導圧配管の内部における気体温度はほとんど同一となって温度差による流れ相当分の差圧はほとんど計測されず、二本の導圧配管を排気塔の外部に設けることのメリットを生かすことが可能になる。
【図面の簡単な説明】
【図１】本発明の実施例である二本の導圧配管を排気塔外に設置する例を示す概略図。
【図２】本発明の実施例の構成を示す断面図。
【図３】図２の断面側面図。
【図４】試験図を示す図。
【符号の説明】
１…排気塔、５…差圧検出器、６…差圧伝送器、１１…高圧側導圧配管、１２…低圧側導圧配管、１３…溶着金属部、１４…熱伝導材、１５…保温断熱部、２５…空白領域（空間部）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas flow rate device that measures the flow rate of a gas (mostly exhaust gas) that flows through the inside of a tall structure such as a chimney or an elevated exhaust tower, that is, a high-rise exhaust tower, by a differential pressure. .
[0002]
[Prior art]
In an exhaust tower for exhaust gas emission installed in a treatment facility for various types of waste including industrial waste, measurement and monitoring of the flow rate of exhaust gas passing through the exhaust tower may be required.
And an exhaust tower may be made into a very high structure from the environmental influence on the surrounding environment. In such cases, the uppermost height of the exhaust tower is almost 70 m or higher.
[0003]
Even in such a high exhaust tower, the flow velocity of the exhaust gas is very slow, and a venturi type or orifice type measurement method is employed for flow rate measurement. These measuring methods are well known as gas flow rate measuring means using differential pressure.
A differential pressure detector is disposed in the vicinity of the outlet end of the exhaust tower, which is a high-rise building, and the differential pressure from the flow rate detection end is taken out and measured.
[0004]
As a conventional detection method, 1) a configuration in which a differential pressure transmitter is installed in a high-rise section, 2) a configuration in which two differential pressure voltage pipes are provided inside the exhaust tower, and 3) two configurations on the outer wall of the exhaust tower The form which provides and measures differential pressure guide piping is adopted.
[0005]
[Problems to be solved by the invention]
The current problems with conventional detection methods and the problems that are expected to occur in the future are as follows.
The three methods mentioned above will be described separately.
1. Differential pressure transmitter installation method in high-rise part The installation position of the electronic measuring instrument is over 70m above the ground, and there is an annual inspection and other operational problems.
[0006]
2. The differential pressure detection conduit installation system inside the exhaust tower According to the system shown in the above 2, there is no influence of direct sunlight, and two differential pressure guiding pipes are provided at an accurate temperature depending on the fluid in the exhaust tower. Can measure. For this reason, the present method is most often adopted. However, corrosion may be promoted by the environment in the exhaust tower, and it will be necessary to re-execute even corrosion caused by aging, which is naturally difficult to re-execute because the construction is inside the exhaust tower. Impossible).
[0007]
3. Installation method of differential pressure detection pipe on the outer wall of the exhaust tower The installation location of the electronic measuring instrument can be on the ground, and the annual inspection and other problems can be solved, but the two differential pressure impulse lines are affected by sunlight. A temperature difference is generated, and the differential pressure cannot be measured accurately due to the rising airflow (rising flow) generated by the temperature difference. The measured differential pressure in the flow measurement of the exhaust tower is very small, such as several mm to several tens of mm, and the temperature difference between both pipes is required to be 1-2 ° C. It is difficult to keep within this temperature difference even if the temperature is kept. In addition, it may be possible to suppress the influence of direct sunlight by using vacuum insulation piping, but even if each differential pressure guiding tube is constructed with vacuum insulation piping, it is still affected by direct sunlight and the temperature difference between the two tubes is reduced. It cannot be completely suppressed. Even when both differential pressure guiding pipes are housed in one vacuum insulation pipe, it is difficult to make the temperature difference between the two pipes the same, and the pipes are very expensive. It cannot be adopted considering the aging of layers and re-evacuation.
As described above, there is a problem even if any method is adopted. However, since there are no other options at present, construction is carried out by either method.
[0008]
In order to solve the above-described problems, it is necessary to have a structure capable of constructing a conduit outside the chimney and not causing a temperature difference between the differential pressure guiding pipes.
All of the vacuum insulation pipes and heat insulation pipes are heat input suppression systems, but it is impossible to completely block the heat input, and naturally it is impossible to prevent the temperature of the pipe from rising due to heat input. For this reason, in addition to preventing heat input, the new apparatus is required to have a structure in which the pipes actively transmit heat to each other and do not cause a temperature difference. The problem is not to cause a temperature difference between the pipes, not to raise or lower the temperature. The present invention ensures that the temperature difference accompanying the temperature rise of the gas inside the two differential pressure guiding pipes is within an allowable value, so that the two differential pressure guiding pipes are placed outside the exhaust tower. An object of the present invention is to provide a pressure guiding piping structure that pays attention to satisfying the function of the installation.
[0009]
[Means for Solving the Problems]
The present invention is provided with a differential pressure detector for measuring the differential pressure of the exhausted gas in the vicinity of the outlet end of an exhaust tower such as a chimney or a high-rise structure, and two differentials from the differential pressure detector. In the gas flow measuring device in which the pressure guiding pipe is connected to the differential pressure transmitter and the gas flow rate based on the differential pressure is measured, each of the two differential pressure guiding pipes is piped outside the exhaust tower. The two differential pressure conduits and the heat conduction are integrated with each other, and are connected and integrated by a weld metal part, and a heat conductive material is disposed between the two differential pressure induction pipes. A gas flow rate measuring device using a differential pressure is provided as a structure in which a material is covered with a heat insulating heat insulating material.
[0010]
The heat insulating heat insulating material has a cylindrical shape, and a blank region may be formed in a part of the inside thereof. The blank area inside the cylindrical heat insulating heat insulating material can be configured to be closed at constant pitch intervals.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic overall configuration of an embodiment of the present invention. In the example of the figure, the exhaust tower 1 is an example having a height of 70 m from the ground. The exhaust gas 3 that gradually increases in flow velocity flows through the gas exhaust passage 2 in the exhaust tower 1 and is discharged as smoke 4 from the outlet. Is done.
A differential pressure detector 5 for measuring a differential pressure such as a venturi type or an orifice type is provided in the vicinity of the exhaust channel outlet end of the exhaust tower 1 as in the prior art.
[0012]
A differential pressure transmitter 6 is installed in the vicinity of the ground in the same manner as in the prior art, and the obtained signal is transmitted via an electric signal wiring 7 to a processing device using a flow rate processing device, for example, a computer (not shown) such as a personal computer. The exhaust gas flow rate is calculated and displayed on a computer screen or printed out by a printer.
[0013]
Two differential pressure guiding pipes 11 and 12 having the same diameter are connected to the outside of the exhaust tower 1 by connecting the high pressure part of the differential pressure detector 5 and the two parts of the differential pressure part and the differential pressure transmitter 6. It is provided along. One of the two differential pressure guiding pipes is a high pressure side pressure guiding pipe 11 and the other is a low pressure side pressure guiding pipe 12. In the high pressure side pressure guiding pipe 11 and the low pressure side pressure guiding pipe 12, pressure guiding paths 21 and 22 connected to the high pressure side portion and the low pressure side portion of the differential pressure detector 5 are formed, respectively.
[0014]
FIG. 2 and FIG. 3 show the arrangement of the high pressure side pressure guiding pipe 11 and the low pressure side pressure guiding pipe 12.
In these drawings, a high pressure side pressure guiding pipe 11 and a low pressure side pressure guiding pipe 12 are each made of a metal pipe, and are connected and integrally fixed by a weld metal portion 13. That is, the high pressure side pressure guiding pipe 11 and the low pressure side pressure guiding pipe 12 are integrated by metal welding. Between the two differential pressure guiding pipes 11 and 12, a heat conductive material 14 is disposed in contact with these and the weld metal portion 13. The heat conductive material 14 may be a known material.
[0015]
As shown in the figure, the heat conductive material 14 is provided between the two differential pressure guiding pipes 11 and 12 so as to fill the recessed portion and cover the weld metal portion 13. It may be provided so as to be a part of the dent or to rise from now on. The length of the heat conducting material 14 is the same as the length of the two differential pressure guiding pipes 11 and 12.
[0016]
In the case of the present embodiment, the two differential pressure guiding pipes 11, 12, the weld metal part 13, and the heat conductor 14 configured and integrated as described above are formed by a cylindrical heat insulating heat insulating material 15. Covered to form a twin heat conduction tube. The inside of the heat insulation heat insulating material 15 is a space portion 25, and the above-described configuration is integrally disposed in the space portion 25. Therefore, the heat conductive material 14 is disposed inside the space portion 25. In the drawing, a space region formed in the space portion 25 is partially formed.
[0017]
With such a configuration, heat conduction is performed between the two pressure guiding pipes 11 and 12, and the inside of the twin heat conduction pipe is used as a heat insulation effect part by a blank area. This blank area is formed by being closed at a constant pitch, and each area is a so-called still air space where the air stops.
[0018]
A part of the inner wall of the heat insulation heat insulating material 15 is in contact with a part of each of the pressure guiding pipes 11 and 12, that is, at two farthest portions.
The temperature equalizing member comprising the weld metal part 13, the heat conductor 14, and the heat insulation heat insulating material 15 provided in the twin heat conduction pipe is, for example, 70 m in all the lengths of the two pressure guiding pipes 11 and 12. It is provided over the length.
[0019]
As described above, according to this embodiment,
1) A differential pressure detector 5 comprising an orifice or a venturi pipe is installed at a differential pressure (flow rate) detection end in the vicinity of the upper opening of the exhaust tower.
2) The differential pressure is transmitted from the differential pressure detector 5 to the differential pressure transmitter 6 installed on the ground by the two differential pressure guiding pipes 11 and 12 laid on the outer surface of the exhaust tower 1.
3) The differential pressure transmitter 6 detects the differential pressure, converts it into an electrical signal, transmits the signal to an upper flowmeter (personal computer) via the electrical signal pipe 7, and measures the flow rate.
[0020]
In this case,
4) Two differential pressure guiding pipes, that is, the high pressure side piping 11 and the low pressure side pressure guiding pipe 12 are connected by a weld metal part 13.
5) In addition to metal connection, in order to increase the solid conduction area, a heat conducting material is further filled between the two pressure guiding pipes 11 and 12, so that solid heat conduction is positively performed.
6) Further, in order to suppress heat input from the outside, the outer surface portion was covered with a heat insulating heat insulating material 15.
7) Furthermore, a blank area (space part) was cut inside the heat insulating heat insulating material 15 to obtain a heat insulation effect part.
[0021]
Next, the tube temperature and the generated differential pressure are examined.
When both ends of the differential pressure guiding pipe are sealed, the pressure difference caused by the temperature difference between both pipe fluids can be obtained by the following equation.
[0022]
P1 / T1 = P2 / T2 from Pv = RT = constant
P2 = P1 / T2 / T1
Here, P: pressure T: temperature V: volume R: gas constant Therefore, the internal gas temperature T2 on the piping side that is more affected by direct sunlight T2 = 21 ° C = 294 ° K, the internal gas of the piping on the unaffected side If the temperature is T1 = 20 ° C. = 293 ° K and the pressure is atmospheric pressure P1 = 1.0332 kgf / cm 2 abs, then P 2 = 1.0368 kgf / cm 2 abs and the pressure difference ΔP = P 2 −P 1 = 0.0036 kgf / cm 2 = 36 mmH20 It is equivalent to pressure.
[0023]
When the both ends of the pipe are not closed, this differential pressure appears as a pseudo flow toward the pipe opening due to the differential pressure, and the differential pressure corresponding to the flow becomes a measurement error.
However, in the case of the present embodiment, the above-described configurations 4) to 6) or 4) to 7) hardly generate a differential pressure corresponding to the flow and eliminate the measurement error.
[0024]
The test data carried out in the situation of conventional piping and heat insulation construction are shown below.
The piping used for the test was carried out by standard piping construction shown below, which is usually adopted at power plants.
[1] Piping size: 20A
[2] Piping material: SUS304TP-A
[3] Pipe thickness: 2 mm
[4] Thermal insulation material: Polystyrene molded article [5] Thermal insulation thickness: 30 mm
[6] Thermal insulation outer surface use: SUS sheet metal finish [7] Solar radiation simulation: Table 1 shows the results of vertical and horizontal projection tests.
[0025]
[Table 1]

[0026]
FIG. 4 shows the result of a similar test performed on the twin heat conduction tube of this example.
The specifications of the twin heat conduction tube used for the test are as follows.
[1] Piping size: 20A
[2] Piping material: SUS304TP-A
[3] Pipe thickness: 2 mm
[4] Between pipes: welded connection + thermal conductive agent filling [5] Insulation material: Polystyrene foam [6] Insulation thickness: 30 mm
[7] Thermal insulation space treatment: Filled with constant pitch glass wool [8] Use of thermal insulation outer surface: SUS sheet metal finish [9] Solar radiation simulation: Table 2 shows the vertical projection test results.
[0027]
[Table 2]

[0028]
That is, the gas temperature inside the high pressure side pressure guiding pipe 11 and the low pressure side pressure guiding pipe 12 is almost the same, and the pressure difference corresponding to the flow due to the temperature difference is hardly measured.
[0029]
【The invention's effect】
As described above, according to the present invention, the gas temperatures inside the high-pressure side pressure guiding pipe and the low-pressure side pressure guiding pipe are almost the same, and the differential pressure corresponding to the flow due to the temperature difference is hardly measured. It is possible to take advantage of the provision of the pressure guiding pipe outside the exhaust tower.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example in which two pressure guiding pipes according to an embodiment of the present invention are installed outside an exhaust tower.
FIG. 2 is a cross-sectional view showing a configuration of an embodiment of the present invention.
3 is a cross-sectional side view of FIG. 2. FIG.
FIG. 4 is a diagram showing a test diagram.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Exhaust tower, 5 ... Differential pressure detector, 6 ... Differential pressure transmitter, 11 ... High pressure side pressure guiding pipe, 12 ... Low pressure side pressure guiding pipe, 13 ... Weld metal part, 14 ... Heat conduction material, 15 ... Thermal insulation Insulation part, 25 ... blank area (space part).

Claims (1)

A differential pressure detector for measuring the differential pressure of the exhausted gas is provided in the vicinity of the outlet end of the exhaust tower such as a chimney or a high-rise structure, and two differential pressure guiding pipes from the differential pressure detector Is connected to the differential pressure transmitter, and the gas flow rate measuring device for measuring the gas flow rate based on the differential pressure,
Each of the two differential pressure induction pipes is composed of a metal pipe piped outside the exhaust tower, and is connected and integrated by a weld metal part, and heat is generated between the two differential pressure induction pipes. Conductive material is disposed, and the two integrated differential pressure conduits and the heat conductive material are covered with a heat insulating heat insulating material, and the heat insulating heat insulating material has a cylindrical shape, and a part of the inside thereof is formed at a constant pitch interval. A gas flow rate measuring device using a differential pressure, wherein a closed blank region is formed.

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