JP2010216721A - Steel ball recovery device and steel ball recovery method for shot cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel ball recovery device and a steel ball recovery method for a shot cleaning device preventing temperature rising of steel balls due to contact of the steel balls with high temperature dust for a long time. <P>SOLUTION: In a steel ball separating device of the shot cleaning device, the steel balls are spread on a heat transfer tube and the dust adhered to the boiler heat transfer tube is removed, the dust is recovered along with the spread steel balls, and the steel balls and the dust are cooled and separated. A separating device of a trommel structure is connected to a boiler lower part via a supply chute 3, and a powdery dust chute 2a recovering powdery dust 15 and a steel ball recovery chute 2b recovering the steel balls 14 are disposed in a lower part of the separating device. <P>COPYRIGHT: (C)2010,JPO&INPIT

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 the case of this soot blow method, 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 can be obtained, but the injection force decreases sharply 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 even if cooling air is blown, the steel balls cannot be uniformly cooled. 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 removes dust adhering to a boiler heat transfer tube by spraying steel balls on a heat transfer tube, and also collects dust together with the scattered steel balls to cool and separate the steel ball and dust. In the separation device, a separator having a trommel structure is connected to the inside of the boiler through a supply chute at a lower portion of the boiler in a state of continuous communication, and a powder dust chute for collecting dust and a steel ball for collecting the steel ball at the lower portion of the separation device. A ball collecting chute is provided.

  In this way, the dust and the steel balls that have fallen to the lower part of the boiler are sent to the separation device of the trommel structure via the chute 3, and are separated into the dust and the steel balls by the separation device. Is short, so there is no temperature rise in the steel ball.

  In the present invention, a steel ball recovery tank is connected to the steel ball recovery chute, and a cooling device for cooling the steel balls is disposed in the steel ball recovery tank. However, the steel ball recovery tank has air permeability and can be sufficiently cooled with cooling air.

  Further, in the present invention, the sieve of the steel ball separation device has a fine size for collecting powder dust on the supply chute side (upstream side) and a coarse size for collecting the steel balls on the downstream side, and lump dust larger than the size of the steel ball. Can be recovered from the upstream end of the separator. Boiler dust is a powdery dust, but in rare cases, it may contain and discharge lumped dust or refractory pieces installed on the boiler wall. It becomes an obstacle of the steel ball transfer system including the cutting device. For this reason, in order to isolate | separate the lump | aggregate more than a steel ball size, it was set as the trommelen structure with a 2nd stage mesh. In this structure, the supply chute side of the cylindrical sieve is a fine sieve where only dust dust smaller in size than the steel balls is discharged under the sieve, and the downstream side is coarse enough to discharge the steel balls under the sieve. The steel balls are discharged using a sieve. Here, a steel ball and a steel ball-sized lump are discharged, but since this lump is the same size as the steel ball, it does not hinder the steel ball cutting device or the conveyance system.

  In addition, as a method of using this device, a steel ball is sprayed on the heat transfer tube to remove the dust adhering to the boiler heat transfer tube, and the dust is collected together with the sprayed steel ball to cool and separate the steel ball and dust. In the method of separating steel balls of a cleaning device, a separator having a trommel structure is connected to the lower part of the boiler in a state of continuous communication with the inside of the boiler via a supply chute, and dust and steel balls are separately collected by the separating device. It is what.

  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 is separated from the tank for collecting 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 dust discharge device. 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.

  FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention. As shown in FIG. 1, the dust and steel balls collected by the boiler lower chute 5 are fed into the trommel sieve 1 by the supply chute 3 via the shut-off valve 4 that is always open. The trommel sieve 1 is housed in the casing 2 and is blocked from the outside air. Further, the trommel sieve 1 supports the cylindrical sieve at two locations by the trommel sieve support column 17 by the rotating shaft 7. 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 shaft penetrating portion. The rotating shaft 7 and the cylindrical screen may have a slight inclination on the discharge side or a spiral guide vane on the inner surface in order to have a function of feeding dust and steel balls.

  Trommel sieve 1 has two meshes and the feed enters fine sieve 1a. In general, a steel ball of 6.3 mm is used as a steel ball for shots, and when a steel ball of the same size is used, a fine mesh of about 5 mm is suitable. With this sieve, dust of 5 mm or less is classified under the sieve. Dust and steel balls of 5 mm or more move to the sieve 1b provided with the next coarse texture. When the steel ball is 6.3 mm, the mesh at this portion is provided with a mesh of about 10 mm, and the steel ball and lump dust of 10 mm or less fall under the sieve. In rare cases, a lump of a size larger than the size of the steel ball may flow in, which may impede the biting of the steel ball cutting device and the transfer of the steel ball. It is discharged from the sieve end.

  The powdery dust 15 that has passed through the fine sieve 1a is collected in a powdery dust chute 2a provided immediately below, and is discharged out of the system from a rotary valve 12 having a sealing function. The steel balls 14 are collected in the steel ball tank 8 through a coarse steel ball chute 2b. The steel ball heated in the process of passing through the boiler is cooled by the air blown by the cooling air pipe 9 installed in the steel ball tank 8. The blown air cools the steel balls 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 rotary valve 12 having a seal mechanism is provided at the discharge portion of the powdery dust 15. A lump chute 2c is provided at the discharge portion of the lump dust 16, and a double seal damper 13 is used to provide a sealing mechanism at the outlet of this lump chute. 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 14 is constantly discharged to the boiler via the trommel sieve 1, the casing 2 is always filled with air and there is no concern about corrosion due to the inflow of gas in the boiler. Absent. Moreover, when checking the inside of the trommel sieve 1 during boiler operation, the inside of the trommel sieve can be opened and checked by closing the shutoff valve 4.

DESCRIPTION OF SYMBOLS 1 Trommel sieve 1a Fine sieve 1b Coarse sieve 2 Casing 2a Powdery dust chute 2b Steel ball chute 2c Lump chute 3 Supply chute 4 Shut-off valve 5 Boiler lower chute 6 Trommel rotary drive part 7 Trommel rotary drive shaft 8 Steel ball tank 9 Cooling air Blow pipe 10 Steel ball cutting feeder 11 Injector 12 Rotary valve 13 Double seal valve 14 Steel ball 15 Powdery dust 16 Lump dust 17 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 Conservator 25 Dust discharge device 26 Soot blower

Claims (4)

In the steel ball separation device of the shot cleaning device that disperses the steel balls on the heat transfer tubes to remove the dust adhering to the boiler heat transfer tubes, collects the dust with the dispersed steel balls, and cools and separates the steel balls and dust,
A separator having a trommel structure is connected to the inside of the boiler through a supply chute at the bottom of the boiler in a state of continuous communication with a powder dust chute for collecting dust and a steel ball collecting chute for collecting the steel ball at the bottom of the separator. A steel ball separation device for a shot cleaning device, characterized in that it is disposed. 2. The steel ball of the shot cleaning device according to claim 1, wherein a steel ball recovery tank is connected to the steel ball recovery chute, and a cooling device for cooling the steel ball is disposed in the steel ball recovery tank. Separation device. The sieve of the steel ball separator is a finer for collecting powdery dust on the supply chute side (upstream side), and a coarser part for collecting the steel ball on the downstream side and lump-shaped dust having a size equal to or larger than the steel ball is the separator. The steel ball separation device for a shot cleaning device according to claim 1, wherein the steel ball is collected from a downstream end of the shot cleaning device. In the steel ball separation method of the shot cleaning device, in which the steel balls are sprayed on the heat transfer tubes to remove the dust adhering to the boiler heat transfer tubes, the dust is collected together with the scattered steel balls, and the steel balls and dust are cooled and separated.
A steel ball separation of a shot cleaning device, wherein a separator having a trommel structure is connected to the inside of the boiler through a supply chute in a continuously communicating state with a lower part of the boiler, and dust and steel balls are separately collected by the separation device. Method.

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