JP5390225B2 - Steel ball collecting device and steel ball collecting method of shot cleaning device - Google Patents

Description

  The present invention relates to a steel ball recovery of a shot cleaning device, in which dust adhered to the heat transfer tube surface of a heat exchanger disposed in an exhaust gas passage of a boiler is removed by colliding the steel ball by falling and colliding with the steel ball. The present invention relates to an apparatus and a steel ball collection method.

  If dust adheres to the surface of the heat exchanger tube of the heat exchanger disposed in the exhaust gas flow path of the boiler, the heat recovery rate of the heat exchanger decreases, and thus the adhering dust needs to be removed periodically.

  Conventionally, a soot blow system in which steam generated from a boiler is sprayed onto a heat transfer tube to remove dust from the heat transfer tube formed of a horizontal tube group is generally used. In this system, the strength of the wiping off is generated depending on the distance of the heat transfer tube from the soot blow and the position in the heat transfer tube group. That is, the dust attached to the heat transfer tube group is removed by the strong injection force on the surface of the heat transfer tube group on the side close to the soot blow injection nozzle, but the injection force is weakened on the inner side of the heat transfer tube group and the dust removal performance is deteriorated. There was a problem. For this reason, it is necessary to install a large number of soot blowers in the height direction, and the cost for installation has been great. Furthermore, the surface heat transfer tube group on the side close to the injection nozzle has a problem that the heat transfer tube group is worn because the injection force is strong. Further, since steam is used as the jet fluid, the steam recovery amount is reduced at the time of soot blow, and the power generation is reduced particularly when power is generated by the steam turbine.

  FIG. 3 shows an example in which a soot blow type dust removing device is installed in the waste heat boiler 20. In FIG. 3, the hot exhaust gas is cooled in the radiation cooling chamber 21, enters the adjacent chamber from the lower part of the boiler, exchanges heat through the superheater 22, the evaporator 23, and the economizer 24, and is discharged from the upper part of the boiler. Each of these heat exchangers is composed of a horizontal heat transfer tube group. A number of soot blowers 26 are provided to remove dust adhering to and accumulated on these heat transfer tube groups, and a steam ejection hole is provided at the tip of the probe in a direction perpendicular to the axis of the probe. It sprays to the whole heat exchanger tube by the operation to do. The dust deposited on the heat transfer tube group is removed by intermittent soot blow operation. The dust that has been wiped down settles down and is discharged from the dust discharge device 25 to the outside of the boiler.

  In this soot blow system, the heat transfer tube near the nozzle side, especially the heat transfer tube on the surface side, receives a strong injection force, and the dust removal effect is obtained, but the injection force is sharply reduced in the back heat transfer tube , Dust wiping ability is reduced. For this reason, the pressure of the injection force is increased to ensure a sufficient dust wiping force for the heat transfer tube on the back side, but this results in the wear of the heat transfer tube on the surface side. Further, in the soot blow system, it is common to use boiler steam as the jet fluid, but since steam of 1 to 2 ton / hour is used as the amount of steam, the amount of heat recovered from the boiler is reduced. .

  In contrast to this soot blow system, a system in which steel balls are dispersed from the upper part of the heat exchanger as disclosed in Patent Document 1 has been conventionally employed. This is shown in FIG. In FIG. 4, the steel ball 28 collides with the heat transfer tube group in the process of falling through the heat transfer tube 27, falls down while dust is removed, and the steel ball 28 dropped together with the dust is sent to the dust separator 29 by the cutting gate, And steel balls are separated and recovered. The collected steel balls are sent to the steel ball distributor 32 via the chute tube by the vertical conveying device 30 and again sprayed from the upper part of the heat transfer tube group.

  In the conventional shot cleaning system, the temperature of the steel balls dispersed from the upper part of the boiler is raised by a high-temperature gas flow in the process of passing through the heat transfer tube group, but the time for passing through the heat transfer tube group is as short as about 10 seconds. Therefore, the temperature of the steel ball that rises due to contact with the high-temperature gas is about 200 ° C., and is not a temperature that causes a problem in heat resistance. However, the temperature of the dust descending with the steel ball is about 700 to 900 ° C., and in the structure where the dust is stored in the lower part of the hopper and discharged together with the dust from the cutting gate to the dust separator, it receives heat from the dust and becomes high temperature. . Furthermore, since dust and steel balls are mixed and stored in the dust separator, ventilation in the dust separator is not stable, and the steel balls cannot be cooled uniformly even when cooling air is blown. In addition, since the temperature of the steel balls is increased, there is a problem that the wear of the steel balls is quick and the replenishment amount of the steel balls is increased. For this reason, the shot cleaning method is limited to the economizer portion where the gas temperature and the dust temperature are low.

JP-A-10-223396

  The problem to be solved by the present invention is to provide a steel ball recovery device and a steel ball recovery method of a shot cleaning device that prevent a steel ball from being heated to high temperature due to contact with high temperature dust for a long time.

The present invention relates to a shot cleaning device in which steel balls are dispersed on a heat transfer tube to remove dust adhering to the boiler heat transfer tube, and the dispersed steel balls and dust are taken out from the lower part of the boiler to separate and cool the steel balls from the dust. In the steel ball separating device, a separator having a trommel structure is connected to a boiler lower part through a supply chute in a constantly communicating state with the inside of the boiler, and the trommel structure has a concentric cylindrical double structure and the same rotating shaft. a structure that rotates integrally together, inside the sieve with a coarse sieve shake off the steel ball and powdery dust on the outside of the sieve, the outer sieve with sieve particulars shake off powder dust by the trommel structure A separation device of the above is surrounded by a casing, and a steel ball chute for collecting a steel ball and a dust collecting chute for collecting powdery dust and massive dust are provided at a lower portion of the casing, A steel ball tank is connected to the ball chute, and a cooling air pipe for cooling the steel ball is arranged in the steel ball tank, and the air blown into the steel ball tank passes through the sieve and passes the supply chute. It is characterized by being discharged into the boiler via .

  In this way, since the supply chute is connected to the inner screen of the double structure trommel separator from the lower part of the boiler, the steel ball and the dust are supplied to the inner screen. The inner screen sifts out steel balls and powdered dust. Since the size of steel balls generally used is about 6.3 mm, the size of the inner mesh is about 10 mm. By adopting a sieve mesh of about 10 mm, the steel ball 6.3 mm used is wiped off to the outer sieve, and at the same time, lump and powder dust of 10 mm or less are also wiped off. By adopting an outer sieve mesh of about 5 mm, only powdered dust of 5 mm or less is sieved off. Moreover, the steel ball and the lump of 5 mm to 10 mm are collected in the steel ball tank.

  In the present invention, a spiral feed blade is provided on the inner surface of the inner sieve and the inner surface of the outer sieve. In this way, the steel balls and dust supplied by installing the feed blades can be made more compact than those in which the steel balls and dust are moved and sieved only by the rotation of the sieve device.

  Further, the feed blade of the present invention is configured such that the steel ball and the dust supplied to the inside are inside by setting the direction of the feed blade installed on the inside and the direction of the feed blade installed on the outside in the forward and reverse directions by the rotation operation of the rotating shaft. The movement direction in the sieving device is opposite to that in the sieving device, and dust and lump can be collected in a lump with the same collective chute and can be separated from the steel ball. It becomes compact.

  According to the present invention, the steel ball and dust that have descended in the boiler can be separated from the dust and the steel ball by the trommel separator, and the temperature of the steel ball can be prevented from rising. In addition, since the dust collecting is less in the tank that collects the steel balls, the tank has improved air permeability, and the cooling effect can be enhanced by the cooling air.

It is a longitudinal cross-sectional view which shows the Example of this invention. It is an AA arrow line view of FIG. It is the schematic of the conventional steel ball separation apparatus. It is the schematic of the conventional steel ball separation apparatus.

Embodiments of the present invention will be described below based on examples shown in the drawings.

  As shown in FIG. 1, the dust and steel balls collected by the boiler lower chute 5 are fed into the trommel structure separation device 1 by the supply chute 3 via the shut-off valve 4 which is always open. The trommel sieve 1 is housed in the casing 2 and is blocked from the outside air. The trommel sieve 1 has a double-cylindrical structure, with a coarse sieve 1b on the inner sieve and a fine sieve 1a on the outer sieve. These sieves are connected by a rotary shaft 7 by an inner sieve support column 17b and an outer sieve support column 17a. It is supported. Both ends of the rotary shaft 7 pass through the casing 2, one end is connected to the rotary drive device 6, and the other end is pivotally supported by a rotary shaft support bearing 18. A rotary shaft sealing device 19 is provided in the penetrating portion of the rotary shaft 7.

  With the trommel sieve 1, the feed enters the inner coarse sieve 1b. In general, a steel ball of 6.3 mm is used as a steel ball for shot, and when a steel ball of the same size is used, the coarse sieve 1b is preferably about 10 mm. Due to this coarseness, steel balls of 10 mm or less and powdered dust are sieved to the outer fine sieve 1a. On the other hand, the outer fine screen 1a has a screen size of about 5 mm. Therefore, the steel balls 14 sieved on the fine sieve 1a are collected in the steel ball tank 8 through the steel ball chute 2b by the rotation of the fine sieve 1a. The powdery dust 15 of 5 mm or less is directly recovered from the mesh of the fine sieve 1a to the collective dust chute 2a. In addition, a lump of the size of the steel ball or larger may flow in rarely, and this may impede the biting of the steel ball cutting device or the transfer of the steel ball, so the lump is collected from the coarse sieve 1b. It is collected directly on the chute 2a. Further, since the downstream sieve end of the fine sieve 1a is connected to the collective dust chute 2a, the massive dust 16 is also collected together with the massive matter.

  The powdery dust 15 that has passed through the fine sieve 1a is collected in an aggregate dust chute 2a provided immediately below, and is discharged out of the system through a double seal valve 13 having a sealing function. The steel balls 14 remaining on the outer fine screen 1a are collected in the steel ball tank 8 through the steel ball chute 2b. The steel ball 14 heated in the process of passing through the boiler is cooled by the air blown by the cooling air piping 9 installed in the steel ball tank 8. The blown air cools the steel balls 14 in the process of passing through the gaps between the steel balls, passes through the trommel sieve 1, and is discharged into the boiler via the supply chute 3. At this time, it is necessary to set the cross-sectional area so that the wind speed at the outlet of the boiler lower chute 5 does not hinder the downward discharge of dust, and a speed of 3 to 5 m / s is preferable. In addition, an injector 11 is provided at the outlet of the steel ball tank 8 via a steel ball cutting feeder 10.

  Since the inside of the casing 2 of the trommel sieve 1 is operated in communication with the boiler, a double seal damper 13 is used to provide a sealing mechanism for the discharge port of the powdery dust 15 and the massive dust 16. The steel ball cutting feeder 10 has a sealing function to prevent leakage of high-pressure carrier air. As described above, since the air blown into the steel ball tank 8 is always discharged to the boiler via the trommel sieve 1, the trommel sieve 1 casing 2 is always filled with air and corroded by the inflow of gas in the boiler. There is no worry.

  In the double-structure sieve, feed blades 1c and 1d for moving steel balls and dust are disposed on the inner surface of the outer fine sieve 1a and the inner surface of the inner coarse sieve 1b. The feed blades 1c and 1d are attached so that the feed blade 1c installed on the outer fine screen 1a and the feed blade 1d installed on the inner surface of the inner coarse screen 1b are reversely fed to each other. ing. For example, when the steel ball and dust are installed to move toward the supply chute 3 by the feed blade 1c of the outer fine screen 1a, the feed blade 1d of the inner coarse screen 1b is installed to move in the opposite direction. Although lump dust of 10 mm or more remains on the inner coarse sieve 1b, the dust is moved to the opposite side of the supply chute 3 by the feed blade 1d and discharged from the end of the inner coarse sieve 1b.

DESCRIPTION OF SYMBOLS 1 Trommel sieve 1a Fine sieve 1b Coarse sieve 1c Fine sieve feed blade 1d Coarse sieve feed blade 2 Casing 2a Aggregate dust chute 2b Steel ball chute 3 Supply chute 4 Shut-off valve 5 Boiler lower chute 6 Trommel rotation drive 7 Trommel rotation drive Axis 8 Steel ball tank 9 Cooling air blowing pipe 10 Steel ball cutting feeder 11 Injector 12 Missing number 13 Double seal valve 14 Steel ball 15 Powdery dust 16 Bulk dust 17a Outer trommel sieve support column 17b Inner trommel sieve support column 18 Rotating shaft Support bearing 19 Rotating shaft sealing device 20 Boiler 21 Radiation cooling chamber 22 Superheater 23 Evaporator 24 Carbon saver 25 Dust discharge device 26 Soot blow

Claims (4)

A steel ball separator for a shot cleaning device that disperses steel balls on the heat transfer tubes to remove the dust adhering to the boiler heat transfer tubes, takes out the scattered steel balls and dust from the bottom of the boiler, and separates and cools the steel balls from the dust. In
A trommel structure separation device is connected to the inside of the boiler through a supply chute at the bottom of the boiler in a continuous communication state. The trommel structure has a concentric cylindrical double structure and rotates integrally with the same rotating shaft. structure and both the inner sieve and a coarse sieve shake off the steel ball and powdery dust on the outside of the sieve, the outer sieve and sieve particulars shake off powder dust separation device of the trommel structure casing A steel ball chute for collecting the steel ball and a dust collecting chute for collecting the powdery dust and the lump dust are provided at a lower part of the casing, and a steel ball tank is connected to the steel ball chute, and the steel ball tank is connected to the steel ball chute. disposed cooling air pipe for cooling the steel balls, the air blown into the steel ball tank passes through said sieve, to characterized in that it is discharged via the feed chute into the boiler Steel ball separator of shot cleaning devices. The steel ball separating device for a shot cleaning device according to claim 1, wherein spiral feed blades are disposed on the inner surface of the inner screen and the inner surface of the outer screen.   3. The shot cleaning device according to claim 1 or 2, wherein the feed blades are installed so that the directions of the feed blades installed on the inside and the feed blades installed on the outside in the forward and reverse directions by the rotation operation of the rotation shaft. Steel ball separator. A steel ball separation method for a shot cleaning device in which steel balls are dispersed on a heat transfer tube to remove dust adhering to the boiler heat transfer tube, and the dispersed steel balls and dust are taken out from the lower part of the boiler to separate and cool the steel balls from the dust. In
A trommel structure separation device is connected to the inside of the boiler through a supply chute at the bottom of the boiler in a continuous communication state. The trommel structure has a concentric cylindrical double structure and rotates integrally with the same rotating shaft. structure and both to overlooked pay the steel balls and powder dust outside the sieve from the inside of the coarse sieve, to overlooked paying powdery dust from the outside of the fine sieve, the separation device of the trommel structure surrounded by a casing A steel ball chute for collecting the steel ball and a dust collecting chute for collecting powdery dust and lump dust are provided at the lower part of the casing, and a steel ball tank is connected to the steel ball chute, and the steel ball is connected to the steel ball tank. disposed cooling air pipe for cooling the air blown into the steel ball tank passes through the sieve, through the feed chute, characterized in that it is discharged into the boiler shop Steel ball separation method of the cleaning device.

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