MODEL PREDICTIVE CONTROL FOR PRODUCTION OF ULTRA-LOW SULFUR DIESEL IN A HYDROTREATING PROCESS

ABSTRACT There is a continual desire around the world to reduce the sulphur content of diesel fuel to ultra-low levels (below 10 ppm) due to environmental concerns and the intention of improving air quality and lowering harmful exhaust emissions of diesel engines. In this work, a hydrodesulfurization unit fed with multiple diesel streams was addressed using a phenomenological mathematical model aiming to produce Ultra-Low Sulfur Diesel (ULSD). A three-phase model of a trickle-bed reactor was considered. A model-based predictive control strategy (MPC) was implemented with the objective of controlling the sulfur concentration at the exit of the reactor, manipulating the flow rates of the oils entering the system, the superficial velocity of the gas and the temperature of the load in the presence of disturbances in the concentration of organic sulfur compounds in the fed oils. It was observed that the control strategy reduced the contaminant content to the specification range of diesel S10.

摘要：鉴于全球对环境问题的关注，以及改善空气质量、降低柴油机有害排气排放的需求，世界各地始终致力于将柴油燃料的硫含量降至超低水平（低于10ppm）。本研究采用现象学数学模型，针对多股进料柴油流的加氢脱硫（hydrodesulfurization）装置开展研究，目标为生产超低硫柴油（Ultra-Low Sulfur Diesel, ULSD）。研究采用滴流床反应器（trickle-bed reactor）三相模型。本研究实施了基于模型的预测控制（model-based predictive control, MPC）策略，以控制反应器出口的硫浓度为目标，在进料油中有机硫化合物浓度存在扰动的情况下，通过调节进入系统的油液流量、气体表观流速以及进料温度实现控制。研究结果表明，该控制策略可将污染物含量降至柴油S10的规格范围内。