Presentation on theme: "MUST HAVE SHOULD HAVE COULD HAVE Module # 150. Dealing with Process Upsets Objectives –Will be able to recognize an Upset –Will be able to analyze an."— Presentation transcript:
What is an Upset What do we mean by an upset? –Abnormal event that not is not likely to be repeated –An event which is caused by external action Operator leaning or stepping on scale Unbalanced mixer Sticky valve –An event that must not affect our working parameter Adjusting for an event will cause errors during the next feed –Permanent change in the process that must be fixed Ie partially blocked pipe –Long term will show a step change of: Ave Flow Rate Spill etc –Not always detected as could still be within limits! May require further investigation
Class Exercises A Place weight on scale at end of feed before DrainTime Expires Hint: weight could be a pen or eraser. –View results –Be sure to inspect the “Material Transfer Process” Screen –Make a note of: –Spill Status, are all three still green ? –Feed Status; what did it say ? –There should be some indication that this was an Upset. Did you see it? –Do a few more feeds: –Did the Qi adjust and remove the error –Hint: it may or may not depending whether you were outside the 100% limits or not
Class Exercises B Move scale enough to cause the “StableScale” light to go OFF while trying to start a feed –View results –Did it start ? (it should not have started) –Be sure to inspect the “Material Transfer Process” Screen –What error messages did you get ? Increase “Zero Flow Threshold” significantly –Did the feed start? –Why?
Class Exercises C Increase Spill and Flow Limits for a Material Path Introduce a large spill upset (Repeat Exercise A) –What happened –Did the feed complete OK –What happened to the K1 and K2 parameters? –Results: –As long as the upset value fell with the 50%range of the Limits the Qi will accept the result. Do a few more feeds without the Upset. –Was the next feed accurate ? –Why not?