instrumentation design for an ammonia plant: cad model capture

INSTRUMENTATION DESIGN FOR AN AMMONIA PLANT:CAD MODEL CAPTURE

Ana Carolina Olivera1, Gustavo E. Vazquez1, Nélida B. Brignole1,2

1 Laboratorio de Investigación y Desarrollo en Computación Científica (LIDeCC)Departamento de Ciencias e Ingeniería de la Computación

Universidad Nacional del SurAv. Alem 1253 – 8000 - Bahía Blanca

Argentina

2 Planta Piloto de Ingeniería Química (PLAPIQUI)Universidad Nacional del Sur - CONICET

Complejo CRIBABB – Camino La Carrindanga km. 7 – CC 717 - Bahía BlancaArgentina

INSTRUMENTATION DESIGN FOR AN AMMONIA PLANT:CAD MODEL CAPTURE

Introduction Instrumentation

Design Automatization

Decision Support System (DSS)

Software Reengineering Concept Stages

Requirement Analysis Model Capture Re-design of the DSS Conclusions

IntroductionInstrument Design

V-1

E-1

P-1

E-2

P-2

E-3

P-3

P-4

P-6P-20

I-2

I-3?

?

?

Instrumentation Design

Model Variables

UnmeasuredVariables

Measured Variables

ObservableVariables

UnobservableVariables

RedundantVariables

Non-RedundantVariables

Observability Redundancy

Decision Support System (DSS)

User Inferface

Process Engineer

Generatation Module(GM)

Generation Equation

Observability Classification

Report

Observability Module (OM)

DesiredClassification

Redundancy Analysis

Module (RM)

Redundancy Classification

Report

DesiredClassification

Final Classification

YES

NODecision Support

Tools

Decision Support Tools

NO

YES

Ponzoni I. & others et. al., 2004

Vazquez G. E & others et. al., 2001

Ferraro S. J. & others, 2002

Software Reengineering

Forward engineering is the traditional process of moving from high-level abstractions and logical, implementation-independent designs to the physical implementation of the system.

Reverse engineering is the process of analyzing a subject system to: Identify the system’s components and their

interrelationships and create representations of the system in another form

or at a higher level of abstraction

Software Reengineering

Software Reengineering is the examination and alteration of a subject system to reconstitute it in a new form and the subsequent implementation of the new form.

Forward engineering Reverse engineering

Software Reengineering

Software Reengineering - Stages

Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

Requirement Analysis

During its application for the analysis of industrial plants, the tool (GM) suffered several anarchical changes that mainly had to do with the addition of new items of equipment and measurements.

Those changes had been made without following a specific method and also without documenting the modifications.

The problem was partly caused by the programming language whose features made the maintenance difficult.

The upkeeping was unrelated to faults, but had mainly to do with the addition of new unforeseen functionalities.

Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

Requirement Analysis

The existing software was integrated to the tools for observability analysis, redundancy identification and the other modules that constituted the DSS.

Since these modules were all developed in an independent way, the interfaces did not offer the users distinctive advantages when a complex design has to be carried out.

Requirement Analysis

Their integration demanded global restructuring.

Requirement Analysis

Another important aspect is friendliness, which can be achieved by a graphical interface with facilities to visualize the flowsheet that is being created. This facility should be available at any point during the definition allowing the addition or remotion of an instrument wherever needed.

Model Capture

Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

Model Capture

the original design and architecture of the software was recuperated to create a representation with a higher level of abstraction.

Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

Model Capture

In this stage both the study of the existing documentation and the interviews with the developer of the original software are mandatory.

Firstly, all the code was scanned to find weaknesses in the implementation and in the programming language.

At this point an intensive analysis on the data structures, functionalities and software architecture is carried out to achieve the DSS original design.

The earliest implementation considered the plant topology, but it was not directly shown to the user.

Achieving the visibility of the input data was an essential goal of this reengineering.

Model Capture Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

Re-design

The re-design may be carried out after having settled the requirements of the DSS and captured the original design.

Bearing in mind the advantages of the object-oriented paradigm and making use of the Unified Modelling Language (UML) (Fowler et al., 1998), this activity was successfully performance.

Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

Re-design

-Shape

PlantEquipment

+addProcessUnit()+deleteProcessUnit()+savePlant()

-name : String = ""-processUnits

ChemicalPlant

1

*

-listOfStream

Equipment-input : Equipment-output : Equipment

StreamComponent

-Phase

MaterialStream EnergyStream

Atributes

Operations

Class Name

Association

Generalization

Generalization

1

*

Instruments

* 1

Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

Re-design

-numberOfStreamHeatExchanger : Integer

HeatExchangers VesselsPumps

Vessel reactionVessel

...Column

-listOfStream

Equipment

...

Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

Re-design

Draw Plant1

1

«uses»

PlantInstrumentation

*

1

Plant Designer Process Engineering

Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

Re-design The topology of a chemical plant must be

straightforwardly available to the engineer. Its representation is natural because it may be captured

as a directed graph. Topologically speaking, a chemical plant may be represented by a graph, its nodes being the items of equipment and its edges being the process streams.

As to the modules for observability and redundancy, they have been developed and tested carefully. Therefore, they should remain untouched. The only modification was to establish an interface and hide their implementation totally.

Source Text +Documentation

List of Requirements

Requirement AnalysisBase

Architecture

Model Capture

List of Problem

Problem Detection

Remove Problem

Problem Analysis

New Base Architecture

Change Propagation

Re-organization

Legacy

ModGen vs. DSS Prototype

ModGen DSS Prototype

DSS Prototype – NH3 Plant

DSS Prototype

DSS Prototype

Conclusions

In this work we only discussed the first two stages in the re-engineering procedure.

In this paper reverse engineering has been addressed since we have explained how to deal with complex software resulting from a chaotic generation by the constant incorporation of new tools.

It was discussed how to re-adapt it by means of the software reengineering approach, so that it fulfils a standard programming and becomes transparent and reusable.