Rectifying the Inherent Compressor Control Issues Using Dynamic Simulation

Autor: Haitham Al-Kalbani, Vijayakrishna Nalagatla
Rok vydání: 2017
Předmět:
Zdroj: Day 3 Wed, November 15, 2017.
DOI: 10.2118/188789-ms
Popis: A dynamic study was performed to evaluate the proposed compressor control scheme (migrating from the existing standalone compressor vendor control scheme) for the existing propane compressor system. Dynamic study was required as the system included complex compressor controls. It was intended that the inherent control design issues could be identified with the dynamic simulations before implementing the complex control designs in highly critical compressor. The main objectives of the dynamic simulation were to: Confirm the control scheme and it's transient responsesConfirm the anti-surge / capacity control system designConfirm the control and trip set points The study included building a dynamic model (using Unisim dynamics) of the relevant process equipment in the propane compressor loop, and subjecting it to transient conditions to evaluate the control scheme. The main conclusions / recommendations of the study were: The proposed control scheme was able to maintain a constant desired suction pressure while keeping all other controllers in the compressor loop stable and ensured that the compressor operate with a safe margin from surge during normal operating conditions.During the turndown, frequent oscillations were observed due to the antisurge parameter oscillations. This was mainly due to the opening of the quench valve and atomization valve by the temperature controller during hot recycle and subsequent closing of atomization valve. This could have led to the damage of the compressor in the longterm. To avoid, it was recommended to change the control logic such that the atomization valve to close only (once opened) when operating point reaches to right side of the surge control line with sufficient margin. Based on the above recommendations, the proposed logic was implemented in the plant successfully. Turndown operation is stable and no oscillations are observed. Hence it is recommended to carry out dynamic simulations to verify such complex and critical compressor control schemes to prevent any control issues and long term integrity issues with compressors.
Databáze: OpenAIRE