預內核計算是:
- [Bot Qual.CV.Remove]=And([Bot Temp.POV.Disconnect] ; [Bot Qual.POV.Disconnect])
如果底部溫度POV和底部質量POV都處于未連接狀態(未連接標簽設置為true),計算通過將“Remove”標簽設定為true來刪除底部質量CV。 - [Top Qual.CV.Remove]=And([Top Temp.POV.Disconnect]; [Top Qual.POV.Disconnect])
如果頂部溫度POV和頂部質量POV都處于未連接狀態(未連接標簽設置為true),計算通過將“Remove”標簽設定為true來刪除頂部質量CV。
3. [Top Qual.CV.Priority]=Iif([Bot Qual.CV.SetrangeHighLim]-[Bot Qual.POV.Measurement]; 1;10)
如果底部質量CV超出了底部質量高限(Bot Qual POV測量值),計算將把頂部質量CV優先級減少到10。否則計算分配給頂部質量CV的CV優先級是1。 - [Sub_Debutanizer.SUB.RequestedStatus]=Not(And([Bot Qual.CV.Remove];[TOP QUAL.CV.Remove]))
如果頂部和底部質量CVs都被移走(它們的Remove標簽被設定為true),計算將把Sub_Debuta子控制器的請求狀態設定為0(OFF)。否則指定的子控制器請求狀態為1(ON)。 - [Reflux.MV.MaxMove]=Iif([BOT QUAL.CV.SetrangeHighLim]-[BOT QUAL.POV.Measurement];100;150)
這項計算修改了Reflux的Maximum Rate of Change(最大變化率)的值。如果底部質量CV超出其上限(bottom qual POV SRHi),將回流的最大動作增加至150。否則最大動作為100。 - [Reboiler.MV.MaxMove]=Iif([BOT QUAL.CV.SetrangeHighLim]-[BOT QUAL.POV.Measurement];1;1.5)
這項計算修改了Reboil的Maximum Rate of Change(最大變化率)的值。如果底部質量CV超出其上限(bottom qual POV SRHI),將再沸的最大動作增加到1.5。否則為1。 - [DEBUTANIZER.CON.EFTrackingFilterTimeConst]=Min(Max([DEBUTANIZER.CON.EFTrackingFilterTimeConst]; 560);1060)
這項計算用來將Economic Function Tracking Filter(經濟函數跟蹤濾波)限制在5~60mins。
兩個內核后計算是: - [ExternalOutput1.EXTOUT.Value]=[Bot Qual.CV.Reachable_ConstraintActivity]
這項計算將底部質量CV在穩態時的約束行為記錄在外部位號ExternalOutput1。 - [ExternalOutput2.EXTOUT.Value]=[Top Qual.CV.Reachable_ConstraintActivity]
這項計算將頂部質量CV在穩態時的約束行為記錄在外部位號ExternalOutput2。
以上所述的計算所需的兩個外部位號是:
預內核計算由下式給出:
最后,內核后計算是:
下圖部分顯示了相應的計算報告。若要使用此功能,請在頁面頂部選擇“Report”選項卡。
如下所述,我們通過兩個場景來探討計算引擎的性能。
仿真1
首先讓我們來考慮被稱為Debutanizer Max Moves.(脫丁烷塔最大步幅)的仿真場景。General場景界面和Sub_Debutanizer界面的相關信息如下圖所示。
原文:
The pre-kernel calculations are:
- [Bot Qual.CV.Remove]=And([Bot Temp.POV.Disconnect] ; [Bot Qual.POV.Disconnect])
This calculation removes the bottom quality CV by setting the “Remove” flag to true if both the bottom temperature POV and the bottom quality POV are disconnected (their disconnect flags are set to true). - [Top Qual.CV.Remove]=And([Top Temp.POV.Disconnect]; [Top Qual.POV.Disconnect])
This calculation removes the top quality CV by setting the “Remove” flag to true if both the top temperature POV and the top quality POV are disconnected (their disconnect flags are set to true). - [Top Qual.CV.Priority]=Iif([Bot Qual.CV.SetrangeHighLim]-[Bot Qual.POV.Measurement]; 1;10)
This calculation decreases the top quality CV Priority to 10 if the bottom quality CV exceeds the bottom quality high limit (Bot Qual POV measurement). Otherwise, the calculation assigns a CV Priority of 1 to the top quality CV. - [Sub_Debutanizer.SUB.RequestedStatus]=Not(And([Bot Qual.CV.Remove];[TOP QUAL.CV.Remove]))
This calculation sets the Sub_Debuta subcontroller requested status to 0 (OFF) if both the top and bottom quality CVs are removed (their Remove flags are set to true). Otherwise specify the subcontroller requested status as 1 (ON). - [Reflux.MV.MaxMove]=Iif([BOT QUAL.CV.SetrangeHighLim]-[BOT QUAL.POV.Measurement];100;150)
This calculation modifies the Maximum Rate of Change value for the Reflux. If the bottom quality CV exceeds its upper limit (bottom qual POV SRHi), increase the max move for the reflux to 150. Else use 100 for the max move. - [Reboiler.MV.MaxMove]=Iif([BOT QUAL.CV.SetrangeHighLim]-[BOT QUAL.POV.Measurement];1;1.5)
This calculation modifies the Maximum Rate of Change value for the Reboil. If the bottom quality CV exceeds its upper limit (bottom qual POV SRHI), increase the max move for the reboiler to 1.5. Else use 1. - [DEBUTANIZER.CON.EFTrackingFilterTimeConst]=Min(Max([DEBUTANIZER.CON.EFTrackingFilterTimeConst]; 560);1060)
This calculation restricts the Economic Function Tracking Filter to lie between 5 and 60 minutes.
The two post-kernel calculations are: - [ExternalOutput1.EXTOUT.Value]=[Bot Qual.CV.Reachable_ConstraintActivity]
This calculation records the constraint activity at steady state for the bottom quality CV to the external tag ExternalOutput1. - [ExternalOutput2.EXTOUT.Value]=[Top Qual.CV.Reachable_ConstraintActivity]
This calculation records the constraint activity at steady state for the top quality CV to the external tag ExternalOutput2.
The two external tags required for the calculations outlined above are:
The pre-kernel calculations are given by:
Lastly the post-kernel calculations are:
The figure below partially shows the corresponding calculations report. To access this feature select the “Report” tab at the top of the page.
We investigate the performance of the calculation engine through a couple of scenarios as described below.
Simulation 1
First consider the simulation scenario called: Debutanizer Max Moves. The General scenario page as well as the Sub_Debutanizer page with the relevant information are shown below.
2016.6.15