Dynamic Pipeline Simulation

Summary

Fluid flow transients in a pipe system may cause operational instabilities leading to shut-down of the system, or may cause mechanical damages due to excessive vibration or overpressure. Dynamic pipeline simulation therefore plays an important role for design and operation of pipe networks. TOYO has been applying dynamic pipeline simulation technologies in design, commissioning and trouble shooting for pipe networks conveying liquid, gas or both.

Application Example of Water Hammer Analysis for Liquid Piping Network

Liquid flow transients in piping network may cause steep pressure upset so-called “water hammer” or “pressure surge”. Typical water hammer sources are pump trip followed by check valve closure and quick operation of control valves. Steep pressure increase and decrease are often generated by such events and the pressure upset quickly propagates over the system. Excessive pressure increase may cause overpressure in the system, while excessive pressure decrease may cause vacuum in the system followed by secondary pressure upset due to vapor cavity formation (liquid vaporization) and collapse (vapor condensation). Such steep pressure upset also induces impulsive fluid dynamic loads which may result in serious vibrations and/or damages in the piping system.

In this example, water hammer analysis for cooling water (CW) network in a chemical plant was carried out to determine the type of CW pump discharge check valve. The CW system is as shown in Fig.1. Pressure transient at Check Valve B outlet due to Pump B trip is computed as shown in Fig.2. With a dual plate type check valve, the maximum surge pressure exceeded the design pressure, while it was well within the design pressure with a nozzle type check valve. Based on this analysis, nozzle type check valve was confirmed adequate.

TOYO utilizes water hammer analysis to ensure flawless engineering executions and swift field trouble shootings.

Fig.1 Schematic of CW system

Fig.1 Schematic of CW system

Fig.2 Pressure transients at Check Valve B outlet

Fig.2 Pressure transients at Check Valve B outlet

Application Example of Dynamic Analysis for Gas Piping Network

Gas dynamic analysis is utilized for studying such system transients as compressor start-up / shut-down and flaring in order to ensure design adequacy and system operability, or for investigating countermeasures against problems caused by severe gas flow transients.

One of typical concerns in gas compression system is compressor surge, which can cause severe vibration and damage in the machine and the associated piping system. In this example, compressor behavior in a reactor loop shown in Fig.3 was studied in order to confirm adequacy of the selected anti-surge valve size. Figure 4 shows trajectory of the compressor operating point after its shut-down. As shown in Fig.4, the trajectory stayed out of the surge region, and the anti-surge valve size was therefore confirmed adequate.

TOYO utilizes gas dynamic analysis to ensure flawless engineering executions and swift field trouble shootings.

Fig.3 Schematic of reactor loop

Fig.3 Schematic of reactor loop

Fig.4 Trajectory of compressor operating point after compressor shut-down

Fig.4 Trajectory of compressor operating point after compressor shut-down

Application Example of Dynamics Analysis for Multiphase Pipeline

In long-distance pipelines conveying mixture of oil, gas, and water, prediction of multiphase flow transients is of great importance for design, operation, and maintenance of the pipelines.

In this example, a subsea pipeline over 100 km transferring natural gas and condensate from offshore platform to onshore facility as illustrated in Fig.5 was considered. Multiphase flow transients in this pipeline for seven days were simulated.
The pipeline inlet pressure at offshore platform and fluid temperature arriving at onshore facility were simulated as shown in Fig.6. These simulation results showed good agreement with actual measurement data, hence operation and production plan was investigated based on multiphase pipeline simulation.

TOYO utilizes such multiphase flow dynamic analysis technologies to ensure flawless engineering executions and swift field trouble shootings.

Fig.5 Schematic of Subsea Pipeline

Fig.5 Schematic of Subsea Pipeline

Fig.6 Transients of Pipeline Inlet Pressure and Outlet Temperature

Fig.6 Transients of Pipeline Inlet Pressure and Outlet Temperature