(459c) Development Of Tuwax As A Cape-Open Compliant Process Modelling Environment

The primary objective of this project, founded by TOTAL, is to modify TUWAX source code to comply with the CAPE-OPEN (CO) standards and so to enable TUWAX as a standalone application capable to run with any commercial thermodynamic software using 1.1 CAPE-OPEN Thermodynamic & Physical Properties interfaces.

1) Presentation of TUWAX

? TUWAX is a program for predicting paraffin deposition in single and two-phase flow environments. It is developed at Tulsa University Paraffin Deposition Project (TUPDP) and is regularly updated. Indeed knowledge gained from experimental modeling studies is utilized to permanently enhance the computer program written in FORTRAN 77.

? The wax deposition computer simulator consists of four main elements:

- The hydrodynamic module is used to calculate pressure gradient and to identify the flow pattern existing in a section of a pipeline.

- Depending on the flow pattern predicted previously, the heat transfer module predicts the bulk and wall temperature along the pipe segment.

- The thermodynamic module, developed by Multiphase Solution Inc. (MSI), predicts the wax concentration and properties of existing phases at specific temperatures and pressures.

- The wax deposition module predicts the wax deposition rates from the prevailing flow and temperature conditions.

? The minimum input data are:

- Pipe configuration (Diameter, Length, Pipe Conductivity, Surrounding Temperature, etc.)

- Operating conditions (Inlet Temperature and Pressure, Flow rate)

- Fluid properties (currently obtained from MSI-TUWAX)

? Relationship between TUWAX and MSI's thermodynamic package:

MSI generates some look-up tables of thermodynamic properties that are required for the Wax deposition calculation. The user must input the fluid composition, the pressure range and number of intervals; the temperature range and the number of intervals; and the model to use. Then, TUWAX is able to read and interpolate these tables by using appropriated routines.

2) Development of TUWAX standalone application

? The objective is to plug any commercially available CAPE OPEN Compliant Thermodynamic Software into TUWAX.

? To reach this objective, we used a library (COThermoWrapper1.1.dll) developed by PROSIM SA.This library allows an easy access to CAPE-OPEN Thermo Property Packages 1.1 from an application written in FORTRAN. This application can be a standalone program or a CAPE-OPEN Unit Operation. The library acts as a wrapper around the TUWAX code adding support of CO interfaces.

? The wrapping approach preserved the main three modules of the code (Hydrodynamic, Heat Transfer, and Wax Deposition). We only modified the routines in charge of reading and interpolating the look-up tables, which represents 15 % of the code. Thus, it will be easy to update the other three modules described previously if needed.

3) Interoperability with TUWAX using Infochem's MultiFlash thermodynamic services

? Some tests using an Infochem's Multiflash Property Package have already been conducted on an industrial case provided by TOTAL and allowed us to verify the compatibility between TUWAX and a CO compliant Thermodynamic Software through 1.1 Thermo Interface.

? Simulations with MultiFlash are intended to ensure a better fluid description because we can keep track of the change in composition in time and space. The water phase will also be better described and that may give us an opportunity to enhance the TUWAX model.