JP2004226153A - Diagnosing method for evacuation installation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diagnosing method for an evacuation installation, dispensing with placement of any new device in particular, and detecting not only the position of a leak but also its scale. <P>SOLUTION: According to this diagnosing method for an evacuation installation, the position of a leak and the scale of the leak are specified in an evacuation installation in which a plurality of ejectors are series-connected. This method is characterized in that the plurality of ejectors are sequentially operated from the downstream side (where the vacuum tank side is assumed to be upstream), that the amount of leak in an evacuation system is found for each operation step, and that a difference between the amount of leak in a relevant step and the amount of leak in a step prior to the relevant step is assumed to be the amount of leak in an ejector newly operated in the relevant step, with respect to the respective operation steps. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

＜計算方法＞
▲１▼．各排気ステップ毎に、リーク孔径を計算。
▲２▼．リーク孔径を比較し、リーク箇所を特定する。
【００１３】
また、この診断結果は、処理毎に変化する可能性があるため、その傾向を監視し、１回の診断で判断するよりも複数の診断で判断したほうがより確実な判断ができる。
また、リーク量に関しては、低真空度（常圧に近い側）では、もともと排気装置系内に入っているガス量の評価が定量的に難しいため、ある一定の真空度以上の高真空度側で診断したほうが良い。目安は、２００Ｔｏｒｒ前後である。
【００１４】
【実施例】
図１の真空排気設備実機を使用して実処理中に本発明を適用した結果が、図５である。図５より、２Ｂ部にリークが発生していると判断できる。
【００１５】
【発明の効果】
本発明により、特に新たな装置の設置を必要とせず、また、リークの箇所ばかりでなく、その規模をも検知し得る真空排気設備の診断方法を提供することを可能とした。
【図面の簡単な説明】
【図１】脱ガス設備全体概念図。
【図２】真空排気パターンの一例。
【図３】真空排気速度の一例を示す図。
【図４】エジェクター作動時のリーク量の一例を示す図。
【図５】本発明による真空排気系の診断結果を示す図。
【符号の説明】
１Ｂ、２Ｂ、３Ｂ スチームエジェクター
１Ｃ 第１コンデンサー ４Ｅ エジェクター
２Ｃ 第２コンデンサー ５ＥＡ、５ＥＢ エジェクター
３Ｃ 第３コンデンサー ６ＥＡ、６ＥＢ エジェクター
ＡＣ アフターコンデンサー[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of diagnosing vacuum exhaust equipment provided for vacuum processing, such as RH degassing equipment or DH degassing equipment.
[0002]
[Prior art]
For example, as a vacuum exhaust equipment used for an RH degassing equipment or the like, a general equipment in which a plurality of exhaust steam ejectors are connected in series is generally used. By operating the ejector, the inside of the vacuum chamber on the most upstream side is evacuated, whereby the molten steel in the ladle is sucked into the vacuum chamber and exposed to vacuum to perform degassing such as dehydrogenation and decarburization.
[0003]
However, a leak occurs in the exhaust system due to distortion of the flange portion due to deterioration over time due to deterioration of the exhaust system or a hole due to corrosion. If a leak occurs in the evacuation system, gas is introduced into the system and the evacuation speed drops, the inside of the vacuum chamber does not reach the predetermined degree of vacuum, the degassing efficiency is reduced, or insufficient stirring is caused. May cause trouble. Therefore, it is important to quickly detect and deal with the leak in the exhaust system.
Conventionally, as a method of detecting the occurrence of a leak, as disclosed in Patent Document 1, there has been a method of providing a vibration sensor for detecting a vibration of an exhaust system and detecting a leak portion based on a change in the vibration.
[0004]
[Patent Document 1]
JP-A-63-98537
[Problems to be solved by the invention]
However, in the above-mentioned conventional method, it is necessary to newly install a device for detecting vibration, and it is not possible to detect the magnitude of the leak only by vibration.
An object of the present invention is to provide a method of diagnosing vacuum exhaust equipment that does not require installation of a new device and that can detect not only the location of a leak but also its scale.
[0006]
[Means for solving the problem]
The present invention seeks to advantageously solve the above problems, the gist of which is as described in the claims,
(1) A method for diagnosing a vacuum exhaust system that specifies a leak location and a leak scale in a vacuum exhaust system in which a plurality of ejectors are connected in series, wherein the plurality of ejectors are located on the downstream side (however, the vacuum tank side is defined as the upstream side) ), The leak amount in the vacuum evacuation system is obtained for each of the operation steps sequentially operated, and the difference between the leak amount in the operation step and the leak amount in the operation step before the step is newly operated in the step. A method for diagnosing vacuum exhaust equipment, wherein the amount of leak in an ejector is used.
(2) The diagnosis of the vacuum evacuation equipment according to the above (1), wherein the leak amount in each of the operation steps is obtained from an integral value of a deviation between a theoretical evacuation speed and an actual evacuation speed of the step. Method.
(3) The method for diagnosing vacuum exhaust equipment according to the above (1) or (2), wherein a leak hole diameter when the leak hole is assumed to be a perfect circle is obtained from the obtained leak amount.
(4) The method according to any one of (1) to (3), wherein diagnostic data for a plurality of times is accumulated for a leak amount or a leak hole diameter in each step, and a tendency of a leak location or a leak scale is managed. The method for diagnosing the vacuum exhaust equipment described in the above.
It is.
The feature is that using only the existing vacuum pumping equipment, multiple ejectors are sequentially operated from the downstream side, and the location of the leak and the size of the leak amount are estimated based on the state of the vacuum pumping speed at each time Is what you do.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
FIG. 1 is a diagram illustrating an example of the entire vacuum exhaust system. A vacuum tank for processing molten steel in a ladle is located at the most upstream side, and downstream thereof, 1B, 2B, and 3B steam ejectors are connected in series to cool the discharged steam and discharge it to the outside of the system. There is a first condenser (1C), then a relatively small ejector 4E is connected, a second condenser (2C) is arranged, downstream of which an ejector 5EA, 5EB is connected in parallel and a third condenser (3C). ), Ejectors 6EA and 6EB are further arranged, and an after condenser (AC) is connected to the stripping tower.
[0008]
Usually, when starting vacuum evacuation, the lower opening of the vacuum chamber is immersed in molten steel, and then operated from the steam ejector on the downstream side (the vacuum chamber side is the upstream side, and the stripping tower side is the downstream side), It works sequentially to the ejector on the upstream side. That is, the air existing in the system is discharged from the side near the stripping tower, and finally the air in the vacuum tank is exhausted, the inside of the vacuum tank is evacuated, the molten steel is sucked into the tank, and exposed under vacuum to remove Perform gas treatment. FIG. 2 shows a specific operation sequence of the ejector. First, 6EA and 6EB on the most downstream side are operated, and when a predetermined degree of vacuum (here, 180 Torr) is reached by a vacuum gauge measured in the vacuum tank or 1B before, the next upstream ejector is operated. Some vacuum level detectors usually include a space between 1B and the vacuum chamber, or a vacuum chamber, or both. Any of them can be applied to the present invention.
[0009]
5E and 6E connect two ejectors in parallel. These are operated by two ejectors when the displacement at start-up is large and the load is large. When the degree of vacuum is high to some extent (absolute vacuum side) and the amount of bleeding is reduced, one ejector operates. The aim is to reduce steam.
[0010]
FIG. 3 is a diagram showing a conceptual diagram of an evacuation curve when the ejectors are sequentially operated. “Reference” indicates a theoretical vacuum pumping speed. This is because, in addition to the exhaust characteristics of the vacuum exhaust equipment at the time of new installation, the amount of generated gas such as CO from molten steel due to degassing during actual operation, and the system required for processing gas for reflux, gas for purge, etc. The vacuum pumping speed was determined in consideration of the amount of gas input to the vacuum pump.
[0011]
On the other hand, the description of “actual” indicates that when a leak occurs due to aging or the like, other gases are introduced into the system, so that the apparent evacuation speed becomes slow. The leak amount can be determined from the difference between the “reference” and the “actual” pumping speeds. In addition, if the amount of leak is obtained for each step of operating each ejector, the effect of the leak at that location becomes smaller only when the ejector is actually operated at the location where the leak actually occurs. The leak location can be identified by observing the transition of the ejector and the leak amount.
For example, when 2B is operated as shown in FIG. 4, the leak amount becomes small. Thus, it can be estimated that a leak has occurred in 2B.
Further, the size of the hole can be estimated from the leak amount. Although the leak amount itself may be used, it is effective to express the damage amount by expressing it by the hole diameter, since the magnitude of the damage can be sensed intuitively.
[0012]
A specific example of how to determine the leak amount and the leak hole diameter is shown below. However, the present invention is not particularly limited to the following formula.
By comparing the change in the degree of vacuum during evacuation with the theoretically calculated value, the amount of leak in each part of the vacuum tank to 3B is estimated.

<Calculation method>
▲ 1 ▼. Calculate leak hole diameter for each exhaust step.
▲ 2 ▼. Compare leak hole diameters and identify leak locations.
[0013]
In addition, since this diagnosis result may change for each process, it is possible to make a more reliable judgment by monitoring the tendency and making a judgment by a plurality of diagnoses rather than by one diagnosis.
Regarding the amount of leak, it is difficult to quantitatively evaluate the amount of gas originally contained in the exhaust system at a low vacuum (near normal pressure). It is better to make a diagnosis. The standard is around 200 Torr.
[0014]
【Example】
FIG. 5 shows the result of applying the present invention during actual processing using the actual vacuum pumping equipment of FIG. From FIG. 5, it can be determined that a leak has occurred in the portion 2B.
[0015]
【The invention's effect】
According to the present invention, it has become possible to provide a method of diagnosing vacuum exhaust equipment that does not require installation of a new device and that can detect not only the location of a leak but also its scale.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of the entire degassing facility.
FIG. 2 shows an example of an evacuation pattern.
FIG. 3 is a diagram showing an example of a vacuum pumping speed.
FIG. 4 is a diagram illustrating an example of a leak amount when an ejector is operated.
FIG. 5 is a diagram showing a diagnosis result of the evacuation system according to the present invention.
[Explanation of symbols]
1B, 2B, 3B Steam ejector 1C First condenser 4E Ejector 2C Second condenser 5EA, 5EB Ejector 3C Third condenser 6EA, 6EB Ejector AC After condenser

Claims (4)

A method for diagnosing a vacuum exhaust system for identifying a leak location and a leak scale in a vacuum exhaust system in which a plurality of ejectors are connected in series, wherein the plurality of ejectors are sequentially arranged from a downstream side (however, a vacuum tank side is defined as an upstream side). The leak amount in the vacuum evacuation system is calculated for each operation step that has been operated sequentially, and the difference between the leak amount in the operation step and the leak amount in the operation step before the step is determined by the leak amount in the ejector newly operated in the step. A method for diagnosing vacuum exhaust equipment, characterized in that the amount is an amount. The method according to claim 1, wherein the amount of leak in each of the operation steps is obtained from an integral value of a deviation between a theoretical evacuation speed and an actual evacuation speed in the step. 3. The method for diagnosing vacuum exhaust equipment according to claim 1, wherein a leak hole diameter when the leak hole is assumed to be a perfect circle is obtained from the obtained leak amount. 4. The vacuum exhaust equipment according to claim 1, wherein diagnostic data for a plurality of times is accumulated for a leak amount or a leak hole diameter in each step, and a tendency of a leak location or a leak scale is managed. Diagnostic method.

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