JP2002254042A - Dust removal method for evacuation device, its device and operation method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the decarbonization time by conducting dust deposit removal without fail for a evacuation device for vacuum degasification processing of molten steel. SOLUTION: In this dust removal method of an evacuation device system which consists of a booster, and ejector, and an condenser, the dust is deposited in the system during vacuum degasification process. After finishing vacuum degasification process, the pressure in the system is adjusted to the atmospheric pressure condition, and high-pressure wash water is injected from the upstream side of each apparatus against the gas flowing direction toward the dust exhaust direction. The dust is washed away from the upstream apparatus to the downstream apparatus in the system by switching the high-pressure washing sequentially. Also, for this removal device, high-pressure washing pipeworks are located from a high-pressure washing pump to boosters (1a, 1b and 1c), a condenser (3a), ejectors (2a and 2b) and also to a moving valve, an inhalation tube bending part, and a high-pressure washing cutoff valve is located at each pipework.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing dust deposited in a depressurizing booster and an ejector or a condenser for condensing driving steam used for, for example, vacuum degassing of molten metal, and an apparatus therefor. The present invention relates to the use of an evacuation device equipped with the device.

[0002]

2. Description of the Related Art In a metal manufacturing process, it is well known that a vacuum process is performed in various processes. In particular, in the steelmaking process, the load of vacuum degassing of molten steel is constantly increasing in response to stricter steel material quality requirements in recent years.
The amount of dust generated during vacuum degassing is also increasing due to the increase in load steel types, and the amount of dust deposited on the vacuum exhaust system is also increasing. The amount of dust accumulated on the tray inside the condenser, which condenses water, is increasing, and the occurrence of clogging in the vacuum pumping system causes an obstacle such as a reduction in vacuum pumping capacity.

[0003] The fact is that the operation of the apparatus is periodically stopped without removing means for removing the accumulated dust in the evacuation system, and the cleaning operation is performed manually. For example, in the case of a condenser with the largest amount of accumulated dust, in the conventional operation, the manholes at the top and bottom of the condenser are opened, and an operator enters the condenser through the manhole to remove dust accumulated on the condenser tray. This work is a dangerous work with a poor working environment such as a high temperature inside the device, dust, a narrow work place, and a high working place, and heavy heavy work.
Also, in order to reduce the accumulated dust as much as possible, even during low-vacuum processing, water was not necessarily required to flow through the condenser, which necessitated wasteful consumption of utilities.

[0004]

Under the condition where the number of steel grades designated for vacuum degassing is increasing, it is desirable to eliminate as much as possible the periodic suspension of vacuum degassing equipment for dust removal. Has been implemented in various ways, but maintenance-free has not yet been realized as a measure against dust in the evacuation apparatus. 2. Description of the Related Art Conventionally, the work of removing accumulated dust in a vacuum exhaust system has been performed manually, and an urgent solution has been desired because of the poor working environment. Also, if reliable measures to remove and accumulate dust can be taken, it is possible to drastically change the use of the components of the vacuum evacuation device, and it is expected that wasteful utility consumption will be prevented, and that its refining performance (decarburization performance) will be improved. . The present invention provides a method and an apparatus for removing dust in an evacuation system, which solve the conventional problems described above, enable automatic removal of accumulated dust in the evacuation system, and can increase the operation rate of the apparatus. Along with
It is an object of the present invention to provide a vacuum degassing operation method characterized by including the apparatus.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies and found that boosters,
In a dust removal method for a vacuum exhaust system composed of an ejector and a condenser, dust deposited in the system during the vacuum degassing process, after the vacuum degassing process is completed, the pressure in the system is set to an atmospheric pressure, and then the gas is removed. High-pressure cleaning water is injected from the upstream side of each device in the flow direction toward the dust discharge direction, and high-pressure cleaning is sequentially switched from the upstream device to the downstream device in the system to blow away dust, and high-pressure cleaning water is sprayed. A high-pressure washing pump is arranged, and high-pressure washing pipes are individually arranged from the high-pressure washing pump to the booster (1a, 1b, 1c), the condenser (3a), and the ejector (2a, 2b). Was placed. The condenser (3a) and the ejector (2
a, 2b) A high-pressure washing pipe is arranged at the movable valve and the bent part of the suction pipe between the movable valve and the suction pipe to enable high-pressure washing. In addition, the tray and / or the ejector inner surface of the condenser with a large amount of dust accumulation are coated with a dust-impossible material or a dust-impossible material is used. It was found that stainless steel was used. The decarburization time of the vacuum degassing process is reduced by stopping the cooling water of the condenser (3a) in the low-medium vacuum region when the booster is not operating in the dust removing device equipped with these. The present inventors have devised an operation method for vacuum degassing, and have completed the present invention.

[0006]

FIG. 1 shows an example of a vacuum exhaust system and a high-pressure cleaning system used in a molten steel vacuum degassing apparatus (molten metal vacuum processing equipment) utilizing a vacuum pump. The exhaust gas at the time of vacuum processing is supplied to the depressurizing boosters 1a, 1b, 1c and / or the ejector 2
The driving steam used by the boosters and the ejectors is sucked by the a, 2b, 2c and 2d, and the used steam is sequentially condensed by the condensers 3a, 3b and 3c which are the steam condensing devices. At the time of exhaust gas suction and condensation of the used steam, dust in the generated gas also adheres and accumulates on each device at the same time. In particular, remarkable adherence accumulates on the condenser tray plate 4, and in the conventional method, the cooling water in the condenser 3a is used. Is difficult to operate, and for this reason,
The equipment capacity was based on the ability to suck entrained steam at the condenser cooling water temperature.

[0007] This adhered and deposited dust is reliably removed,
In addition, in order to maximize the ejector capacity in the low and medium vacuum range (use of the amount of entrained steam by stopping the condenser water in the low and medium vacuum range), the area where dust adhesion is particularly noticeable The condenser tray plate 4 is coated with a material that does not easily adhere to dust, such as Teflon, or stainless steel, which is a material that does not easily adhere to dust, is applied.
In some cases, it is desirable to apply the same as the above for the inner surface of the ejector. And the high pressure washing pump 5
A high-pressure cleaning pipe circuit 6 is provided, and high-pressure water for dust removal is supplied from each high-pressure cleaning pipe 6 to each device. The high-pressure cleaning water is supplied from the upstream side sequentially through the high-pressure cleaning shut-off valve 7 after the atmospheric pressure after the treatment is completed. By using this method, it is possible to stop the water in the condenser 3a in the low / medium vacuum region, the amount of entrained steam from the condenser cooling water is eliminated, and the exhaust gas can be sucked up to the maximum ejector capacity max, improving the refining efficiency. Was planned.

FIG. 2 is a flow chart showing the operation procedure of the procedure for spraying high-pressure cleaning water in a vacuum exhaust system. After the pressure in the system is brought to the atmospheric pressure after the vacuum degassing process is completed, high-pressure cleaning is sequentially performed from 1a to 1b and 1c. , 2a, and 2b in the dust discharge direction, and finally, the inside of the condenser 3a is washed with high pressure and the process is completed. In the embodiment, the cleaning time is set to about 10 sec. However, it is necessary to change the cleaning time depending on the properties of the attached dust. In addition, it is desirable to perform this cleaning every time the processing is completed.

[0009]

EXAMPLE Table 1 shows an example of a vacuum exhaust processing operation pattern (equipment operation pattern) in which the present invention is applied and the condenser is stopped in a low / medium vacuum region.

[0010]

[Table 1]

FIG. 3 shows a conventional operation pattern (in the case where no condenser water is stopped in a low / medium vacuum region), and FIG. 4 shows a vacuum evacuation in which a condenser is stopped in a low / medium vacuum region utilizing the present invention. The decarburization behavior when using the processing operation pattern is shown.

Conventionally, dust generated during vacuum processing adheres to and accumulates on each device of the vacuum evacuation system, leading to a reduction in the vacuum evacuation ability. Dust deposited on the equipment was removed. When removing, the work is extremely mentally distressing for the worker because the work is performed in an unsafe environment in which the working load is high and the CO gas may be generated in a poor working environment. Had to be abolished.

According to the present invention, the work for removing the adhered and deposited dust in the vacuum exhaust system is abolished, and a maintenance-free facility is realized. Further, by applying the present invention, as shown in Table 1, water can be shut off in the condenser 3a in the middle and low vacuum regions, so that the utility can be saved and the refining efficiency is greatly improved. 3 and 4
As is clear from the comparison, it is clear that the present invention significantly reduces the time to reach the high vacuum region and significantly improves the decarburization efficiency in the medium vacuum region. This effect
It not only improves production efficiency, such as by reducing processing time, but also greatly reduces running costs.

[0014]

As described above, the present invention is constituted by the above-described apparatus, and can realize a maintenance-free operation and high operating efficiency. In addition, by applying the present invention, the present invention can be applied to a medium / low vacuum region. It is possible to improve the equipment with excellent practicality, durability and economic efficiency with simple equipment, and the industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a vacuum evacuation system to which the present invention is applied.

FIG. 2 is a flowchart showing an operation procedure for ejecting high-pressure cleaning water in an evacuation system.

FIG. 3 is a view showing decarburization behavior in operation when a conventional method is applied.

FIG. 4 is a view showing a decarburization behavior in an operation when the present invention is applied.

[Explanation of symbols]

 1a, 1b, 1c: Booster 2a, 2b, 2c, 2d: Ejector 3a, 3b, 3c: Condenser 4: Condenser tray 5: High-pressure washing pump 6: High-pressure washing piping circuit 7: High-pressure washing shut-off valve 8: Movable valve 9 ： Bend of suction pipe

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Tanaka 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (72) Inventor Ryuji Fujita 46-59 Ohara Nakahara, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture F-term (reference) within Nippon Steel Plant Design Co., Ltd.

Claims (6)

[Claims] 1. A method of removing dust in a vacuum exhaust system comprising a booster, an ejector, and a condenser, wherein dust deposited in the system during vacuum degassing is increased in pressure after the vacuum degassing is completed. After pressure is applied, high-pressure cleaning water is injected from the upstream side of each device in the gas flow direction toward the dust discharge direction, and high-pressure cleaning is sequentially switched from the upstream device to the downstream device in the system to blow off dust. A method for removing dust in a vacuum exhaust system. 2. A high-pressure cleaning pump for blowing high-pressure cleaning water in a vacuum exhaust system dust removing device comprising a booster, an ejector, and a condenser.
The booster (1a, 1b, 1)
c), condenser (3a), ejector (2a, 2)
b) A high-pressure cleaning pipe is individually arranged, and a high-pressure cleaning shut-off valve is arranged for each pipe. 3. The vacuum evacuation according to claim 2, wherein a high-pressure cleaning pipe is disposed at a movable valve and a suction pipe bent portion between the condenser (3a) and the ejector (2a, 2b) to perform high-pressure cleaning. Equipment dust removal equipment. 4. The dust removing device according to claim 2, wherein the tray portion and / or the inner surface of the ejector of the condenser having a large amount of dust accumulated thereon are coated with a material which does not easily adhere to dust or a material which does not easily adhere to dust. 5. The dust removing apparatus according to claim 4, wherein the material which is hardly adhered to dust is Teflon (registered trademark), a coating with alma, and the material which is hardly adhered to dust is stainless steel. 6. The vacuum degassing process by stopping the cooling water of the condenser (3a) in the low-medium vacuum region when the booster is not operating in the dust removal device according to any one of claims 2 to 5. A method for operating vacuum degassing, characterized in that the decarburization time is reduced.