JPH0316615B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention prevents dust from adhering to the inside of the sampling tube in a device having a sampling tube with its tip facing into a duct for performing various measurements on dust in exhaust gas. It is about the method.

As shown in FIG. 4, the measurement of the dust is usually carried out by inserting one end into a duct 1' and bending the tip along the duct at a substantially right angle to the other end of the sampling tube 2'. In addition, there is a detection part or a dust collection part A′ using filter paper, and an SO ₂ absorption bottle.
B', mist remover C', suction pump D', gas flow meter E', gas meter F', etc. are connected in sequence and the exhaust gas sample is sucked in. In this case, the sampling tube 2' is simply a thin tube. Since the tube has a fixed diameter, dust adheres and accumulates inside the tube, making it difficult to accurately measure the properties of dust.

Now, considering the adhesion state of the dust mentioned above,
This dust adhesion occurs at the bent portion of the sampling tube that is bent at a nearly right angle along the duct.
Moreover, the degree of curvature is remarkable on the inner wall on the side where the degree of curvature is large. In other words, this part has the highest resistance, and dust tends to accumulate due to centrifugal force.
Once retained, adhesion is promoted. Therefore, by interposing a gas film other than the exhaust gas sample along the inner wall of this bent part, adhesion can be prevented, and furthermore, this gas film is moved by the exhaust gas sample and prevents dust from accumulating throughout the sampling tube. This makes it possible to prevent

Focusing on the above points, the present invention covers the bent portion of the sampling tube with an outer tube, separately supplies clean gas into the outer tube, and also provides several perforations in the inner wall of the sampling tube. Alternatively, the perforations or perforations are arranged in tandem so that the water is constantly ejected into the sampling tube from these perforations or perforations, and an example of an apparatus implementing the method of the present invention will be described with reference to the drawings. Duct 2 is a sampling tube, which, like the conventional device shown in FIG. 4, includes a detection section or a dust collection section A using filter paper, a gas cleaning bottle B, a mist removal bottle C, A suction pump D, an instantaneous flow meter E, a gas meter F, etc. are connected in sequence, but this sampling tube 2 is separately covered with an outer tube 3, and this outer tube 3 is separately covered with a filter paper or a filter tie. The filtered clean air is sent through a pipe 4 through a flow meter C by a blower (B) equipped with a regulating valve and a bypass. As is clear from FIG. 2, the bent portion of the sampling tube 2 bent at an almost right angle
Perforations or perforations 5 consisting of a plurality of circular holes are opened in a line in the inner wall on the side with the maximum degree of curvature, and clean air is blown into the sampling tube 2 from these perforations or perforations 5. It is becoming more and more common.

FIG. 3 shows a modification of FIG. 2, in which the perforations or gaps 5 are formed as slits instead of round holes, and are formed so as to be ejected in the flow direction of the exhaust gas sample.

With the above configuration, the present invention interposes a clean gas film along the inner wall of the bent portion of the sampling tube having the maximum degree of curvature as described above, thereby preventing dust from coming into contact with the inner wall, and preventing dust from coming into contact with the inner wall. The sampling tube is designed to be wrapped around and moved backwards, and the inside of the sampling tube can be kept clean at all times without applying external force to the sampling tube. In addition to the air shown in FIG. 1, this clean gas may also be supplied from a cylinder or the like using nitrogen gas, carbon dioxide gas, etc., instead of using a blower.

[Brief explanation of drawings]

FIG. 1 is an explanatory side view showing an example of an apparatus for carrying out the method of the present invention, FIG. 2 is a side view of the main part of FIG. 1, and FIG. 3 is a side view showing a modification of FIG. 4
The figure is an explanatory side view of a conventional device. 1 is the duct, 2 is the sampling tube, 3 is the outer tube,
5 indicates a perforation or a gap, A indicates a filter, and B indicates a blower.

Claims (1)

[Claims] 1. In a device having a sampling tube whose tip is bent approximately at right angles, a plurality of perforations or perforations arranged vertically along the bending direction of the sampling tube are formed in advance on the inner wall of the bent portion of the sampling tube.
At the same time, an appropriate compressed gas kept clean is constantly ejected into the sampling tube from these perforations or through holes through an outer tube provided to enclose the sampling tube to separate it from the exhaust gas sample. A method for preventing dust adhesion inside a sampling tube, characterized by forming a gas film along the inner wall of a bent portion of the sampling tube.