JPS5969697A - Dust removing device - Google Patents

Abstract

PURPOSE:To remove the adhered dust efficiently by a method wherein a vibrator is attached to a heat transfer tube to vibrate it without providing the tube with a strong impact force. CONSTITUTION:The temperature of fluid to be heated and heating fluid are detected always and the results of the detections are inputted into a control box 5, memorizing them and outputting command signals. A temperature difference between the fluid to be heated and the heating fluid, under a condition that the dust is not adhered to the surface of the heat transfer tube 1, is memorized previously into the control box 5, and when the value of the actually measured data of the temperature of the fluid to be heated with respect to the same of the heating fluid is lower than a specified value, the control box 5 decides that the dust is adhered to the tube and outputs an operating signal to the vibrators 4, 6 to effect the dust removing work. In this case, if displacement sensors 11, 12 are attached to vibration transmitting rods to measure the displacement and the number of vibration and the feedback of the results of them are fed into the control box, the control of the dust removing work may be more facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for removing dust attached to heat exchanger tubes and the like.

In various heat exchange devices including waste heat boilers, dust consisting of unburned components contained in the heating fluid adheres to the surfaces of heat transfer tubes that perform heat recovery, reducing the heat transfer coefficient.

Therefore, it is necessary to periodically remove the attached dust. One method for removing this dust is to use a hammering device. This method has traditionally been completed manually.
9X This is a mechanical system that applies a striking force to the heat transfer tubes and thereby removes the adhering dust, but it has the following problems. Specifically, (1) Since the hammering device applies a striking force to a specific part of the heat exchanger tube, the heat exchanger tube may be distorted or cracked around the striking part, which may shorten the life of the heat exchanger tube. It has decreased significantly.

(2) There is a high possibility that a very loud sound will be generated when the ball is hit, causing noise pollution.

(3) There is a limit to the impact force that can be applied to the heat exchanger tube in terms of the lifespan of the heat exchanger tube and noise, and this also places a limit on the removal of attached dust.

(4) Hammering is essentially an impulse response, and each time a striking force is applied, the vibration is attenuated, and it is impossible to accumulate it in the form of full amplitude resonance, etc., so dust is removed. The efficiency of the energy used is low.

There are the above-mentioned problems with dust removal using a hammering device, and there is a need for a dust removal device that is less polluting, more economical, and more efficient in removing dust.

An object of the present invention is to provide a dust removal device that is low in pollution, economical, and has a high dust removal rate.

In short, the present invention is an apparatus that attaches an excitation device, which is a vibrator, to a heat exchanger tube, vibrates the heat exchanger tube without applying strong impact force to the heat exchanger tube, and efficiently removes attached dust.

Examples of the present invention will be described below.

In FIG. 1, numeral 1 is a heat exchanger tube, and 2 is a lower header attached to this heat exchanger tube 1. In FIG. A vibration device 4 is attached to the lower header via a vibration transmission rod 3. As this vibration device 4, a vibrator using a rhenoid is effective.

FIG. 2 schematically shows the deflection state of the heat exchanger tube 1 at each vibration frequency, and FIG. 3 is a diagram showing the relationship between the output vibration frequency of the vibration device and the displacement of the heat exchanger tube. In both figures, (a) shows -order vibration, (b) shows second-order vibration, (C) shows third-order vibration, and (d) shows fourth-order vibration. FIG. 5 shows the state of dust adhering to the heat exchanger tube 1, and the dust consists of Dl adhering to the upstream side of the exhaust gas G, which is the heating fluid, and Dl adhering to the downstream side. Here, in the case of secondary vibration (b), looking at the displacement of the heat exchanger tube l, these dust adhering surfaces repeatedly expand and contract as shown in FIG. (In the figure, A indicates elongation and B indicates contraction.) Specifically, the dust adhering surface is subjected to elongation and contraction once each in one vibration period. As a result, cracks occur in the dust particles DI and D2, and the attached dust particles are peeled off and removed.

The inventors tested the effectiveness of dust removal using various vibration modes and confirmed that the following method was effective. FIG. 4 shows this vibration mode. That is, secondary vibration (b)
, third-order vibration (C), fourth-order vibration (d), and third-order vibration (
C) and secondary vibration (b) are applied in sequence for about 10 seconds each,
Furthermore, it was confirmed that extremely good dust removal efficiency could be obtained by repeating this process (5) several times. It was confirmed that the dust removal rate was further improved by applying higher-order vibration to generate surface waves on the surface of the heat exchanger tube, but this placed a large load on the vibration device itself, making it difficult for the vibration device to operate. This is not practical as it reduces the lifespan.

Next, when the vibration device 4 is attached to the heat exchanger tube, the unique vibration frequency of the heat exchanger tube is actually measured when the assembly of the heat exchanger tube is completed, and is inputted to the control device 5'. Based on this measured value, when removing dust, the vibration device is sequentially controlled in a pattern as shown in FIG. 4, for example.

FIG. 7 shows another embodiment. In this embodiment, another vibrating device 6 is attached so that the vibrating direction is perpendicular to the vibrating direction of the vibrating device 4. Reference numeral 7 denotes a vibration transmission rod disposed between the vibration excitation device 6 and the lower header 2. In addition,
Although not shown in the drawings, in addition to or in place of this vibration device 6, another (6) vibration device may be attached at a position facing the vibration device 4.

Next, numeral 8 is a humidity detector that detects the humidity of a heated fluid such as water discharged from a heat transfer tube, and numeral 10 is a temperature sensor that detects the temperature of a heated fluid such as combustion exhaust gas. , the temperature of the fluid to be heated, and the temperature of the heated fluid are constantly detected, and the detection results are input into the control box 5 which stores them and issues command signals. The control box 5 stores in advance the temperature difference between the heated fluid and the heated fluid when no dust is attached to the surface of the heat transfer tube, and the temperature of the heated fluid relative to the heated fluid is determined to a specified value based on the measured data. If it is lower than that, it is assumed that dust has adhered, and the control box 5 issues an activation signal to each of the vibration devices 4 and 6 to perform dust removal work. In this case, control becomes easier if displacement sensors 11 and 12 are attached to each vibration transmission rod, the displacement and vibration frequency are measured, and the results are fed back to the control box.

Regarding the activation timing of the vibration device, instead of or in addition to the humidity of the fluid to be heated and the heating fluid,
It is effective to perform the following control. That is, focusing on the fact that the pressure loss of the heating fluid increases when dust adheres to the heat exchanger tube, the flow velocity of the heating fluid upstream and downstream of the heat exchanger tube is detected, and the difference between these flow velocities is determined to be a value greater than a predetermined value. Activate the vibration device when

By carrying out this invention, a large impact force is not applied to a specific portion of the heat exchanger tube, so the life of the heat exchanger tube can be extended, and moreover, no large noise is generated.

Further, even if the frequency is increased, the life of the heat exchanger tube will not be significantly reduced, so the dust removal effect can be enhanced by using a relatively high frequency.

Furthermore, the vibrations applied to the heat exchanger tube are continuous, and the damping of the vibrations is less than that of a hammering device that applies vibrations as impulses, and dust can be removed efficiently with less energy.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a heat exchanger tube showing a first embodiment of the present invention, Fig. 2 is a conceptual diagram schematically showing the deflection state of the heat exchanger tube, and Fig. 3 shows the relationship between vibration frequency and displacement. Figure 4 is a diagram showing an example of control of the vibration device, Figure 5 is a cross-sectional view of a heat exchanger tube with dust attached, Figure 6 is a diagram showing the expansion and contraction state of the dust attached part, and Figure 7 is a diagram showing an example of control of the vibration device. The figure is a control system diagram of an excitation device showing another embodiment. 1... Heat transfer tube 2... Lower header 3.7... Vibration transmission rod 4.6... Vibration device 5... Control Box 8.10...Temperature detector 11, 12...Displacement sensor D,, 11...Dust agent Patent attorney Okada Gobe (9) Time No. Figure 5

Claims (1)

[Claims] 1. At least one vibrating device is provided that is connected directly to the heat exchanger tube or indirectly through an intervening member such as a vibration transmission rod, and this vibrating device is used to generate vibrations at an arbitrary frequency. A dust removal device characterized by removing attached dust by vibrating a heat transfer tube for an arbitrary period of time. 2. Dust removal according to claim 1, characterized in that a control box is connected to the vibrating device to store and issue a command signal, and the vibrating device is operated by the command signal from the control box. Device. 3. The device according to claim 1 or 2, characterized in that a plurality of the vibration devices are installed, and each vibration device is installed so that the vibration directions of the vibration devices are substantially perpendicular to each other. Dust removal equipment. (1) 4. Claim 1, characterized in that a displacement measuring sensor is attached to the vibration device or the intervening member, and the vibration device is controlled using the measured value of this sensor as a correction value.
The dust removal device according to any one of Items 1 to 3. 5. Claim 1, characterized in that the activation timing of the vibration device is determined based on the temperature difference between the heating fluid and the heated fluid and/or the difference in flow velocity of the heating fluid on the upstream side and the downstream side of the heat transfer tube. 4. The dust removal device according to any one of items 4 to 4.