How to Understand Historian Basics

I spent some good time with Historians implementation using Aspen IP21....

Historians are time series databases which will store plant data from all units in a "centralized repository" ..from where users can visualize,Analyse various units/plants control system data in a structured way from their own desks... which ultimately useful for "Strategic Decision makings"...and also as a "real time monitoring system" which is also called "RTMS"...

Our Clients major focus was to reduce "Power Consumption" with out effecting Production and quality.

This software answers how to improve either Production/Quality/Save etc using your own data.. And at least it will take you to "2 Whys" based on the dashboards/Fault trees developed.

Once the system is enabled people will have an access to visualize historical data...from their own desks through either a web link which is called Aspen Process Explorer/a1PE..or through a a1PE desktop client itself...

" a1PE" itself have many statistical functions where analyst or process engineer can export the data in various forms for regression analysis or correlation analysis of dependent and independent variables..List below are some of the features of a1PE.

1. Statistics features like Regression, Mean,Median,Standard Deviation,Averages etc..
2. Exporting data inform of tables to excels.
3. Comments/Annotation can be set on trends. 
4. Alarms can be set with auto email feature is available in a1PE...
5. Adhoc Calculations can be done on the fly using tags.
6. Reports automation like daily reports  shift reports etc.. 

There are various advantages once this Historian is implemented...few are listed below ...
These reports automation will more successful if plant have a maximum online metering which will fetch data from transmitters/meters..

1. Automating Shift reports,Daily reports,Monthly reports,
2. Performance reports of an equipment,
3. Dashboards for real time monitoring for Production/Consumption/Stock/KPIs/Fault trees/Environmental etc..

Calculations can be build on the fly using "Aspen Calc" and store the information in a Tag..

Dashboards can be developed using "Aspen Graphic Studio Browser" where it has a various features like a dial gauges,input boxes,bars,graphs etc...

How Data flows:
DCS/PLC Control Systems To OPC To ASPEN IP21
"CIM-IO Interface" installation in OPC machines which acts as a TCP is an interface which sets communication between OPC and ASPEN IP21..

Some of the DCS Vendors like Honeywell,Emersion, FactoryTalk,Schneider etc...

"Aspen Administrator" Which we do maximum of the work like Repository Creation,Analog/Discrete/Text tags creation with all the properties like description,units,limits,OPC path mapping,

Major Components of Aspen IP21 which are listed below...

1. "CIM-IO Interface"
2. "CIM-IO Connection Manager"
3. "Aspen Administrator"
4. "Aspen Graphic Studio Browser" 
5. "Aspen Calc"
6. "a1PE or Aspen Process Explorer"

Definitely the process will be same in any historian...Some of them are
OSIsoft PI.
GE Historian
Factory Talk SE Historian

Sequence involved in Thermophysical properties(Fixed Properties and Temperature Dependent Properties) in Chemical Simulation Software

I have been reading some excellent literature where I tried to learn sequence of calculations involved in Thermophysical properties.

Let's start with assay processing where from TBP curve we will get Normal boiling point, composition and specific gravity as out put for each cut components.
Additional reading : Mid point average and LV% method, Watson K factor /Charecterization factor equation.  Where these methods used to convert curve to pseudo components as per cuts defined.All these methods uses boiling point and Gravity as main input.
Reference: Characterization of Petroleum fractions by Dr Qaiser Muslim Abid Ali Assady. And Characterization of Petroleum fraction Hassan S Nazi.

Now think like we have Normal Boiling Point and Gravity for each pseudo component.

Now we have to calculate Critical properties (Tc, Pc, Zc, Vc, Acentric factor)
All these fixed properties are derived from either RIAZI Dubert, Cavet 1962,Cavet 1980,TWU..  I calculated using RIAZI Dubert we got a good match however TWU is suggested because it will do some back calculations to check whether calculations are correct.

Now Temperature dependent properties at desired temperature.  Vapor Pressure (extention of Antoine equation), Acentric factor (depends on reduced  vapor pressure pitzer Correlation) .
 Density(from eos by eliminating V) Vapor pressure(extension of antoine - reidal) , Enthalpy (yan Alexander and Lee kessler,  William for solid H) .I got this understanding by reading one paper ( Thermophysical properties of UF6 which are required for stress testing when engraved in fire where literature data is not sufficient to calculate at higher Tr and Pr)

Note :
This is only for theoretical purpose only.  And there is no guarantee on using for research / any other purposes. 

What is Fouling and monitoring parameters involved and when to clean Heat Exchangers.

Fouling: The deposition of undesirable material on the surface of tubes/shells on an Exchanger.

From Historian data if you find cascade controller at Heat exchanger flow valve is fully open/Max Limit to maintain the outlet temperature then you should act.
Means temperature is maintaining and flow is increasing continously then we have to pay attention.
Even though if we don't have cascade arrangement there will be atleast flow controller so it is very obvious if temperature reduces we increase the hot fluid / steam flow.
Problem: Heat exchanger Fouling.
Monitoring data :Flow Control valve opening/flow and outlet temperature of exchanger.
In general a cascade range controller will be used for the exchanger to maintain outlet temperatures. Arrangement will be like this.

Why at this condition we have to send for maintainance...  read below.

I was reading an excellent blog...

https://eng-software.com/about-us/press/articles/managing-heat-exchanger-fouling-to-reduce-risky-conditions/
I have extracted some information from that article.
"

At a constant flow rate, as fouling occurs and the resistance to heat transfer increases, the heat exchanger’s heat transfer coefficient (U) decreases and will result in:

• a lower heat transfer rate
• a higher outlet temperature on the hot side (and lower dT hot)
• a lower outlet temperature on the cold side (and lower dT cold)

Since the outlet temperatures of the hot or cold side may be critical to the quality control parameters for the overall process, the flow rate must be increased to achieve the desired heat transfer rate and outlet temperature. A higher flow rate reduces theconvection heat transfer coefficient (hf) for the fluid and increases the overall heat transfer coefficient (U)to compensate for the effects of fouling. Very often in these applications, an automatic process control loop is used to measure and control the outlet temperature of one side of the heat exchanger by regulating the hot or cold side flow rate with a control valve (and occasionally a centrifugal pump operated by a variable speed drive).

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