Process Simulation and Optimization of Fluid Catalytic Cracking Unit’s Rich Gas Compression System and Absorption Stabilization System

In a fuel-based refinery, rich gas in the fluid catalytic cracking (FCC) unit is further processed to separate dry gas and refinery products (i.e., stabilized gasoline and liquified petroleum gas). The process is utility-intensive and costly and includes a two-stage compressor, pumps, an absorber, a stripper, a stabilizer, and a re-absorber. The optimization was conducted with respect to the compressor outlet pressure from the gas compression system (GCS) and the flow rate of absorbent and supplementary absorbent from the Absorption-stabilization System (ASS) using the process simulation software Aspen Plus. Compared to the base case of a 725 kt/a rich gas FCC unit, a refinery can save 2.42% of utility costs under optimal operation. Through optimized operation, medium-pressure steam consumption has been reduced by 2.4% compared to the base case, resulting in a significant improvement in total operational cost. The optimization strategy can provide insightful guidance for the practical operation of GCS and ASS.</p

Improving refinery productivity through better utilization of crude oil blending using linear programming.

Refinery Linear Programming (LP) Models and other mathematical techniques for optimization have evolved over many years to create solutions for complex crude oil blending problems. The objective of this case study was to develop a mathematical single period programming model to simulate blending problems to ensure the greatest possible revenue is generated. The yield of products at a refinery, given stringent environmental regulations on product qualities, the reducing availability of quality light, sweet, feedstock make refinery optimization a significant exercise to perform in order to stay in business. In this work a representation of a case study refinery model was presented, in which the overall gross profit margin, density, and sulphur content of the products were calculated, and evaluated to ensure they fall within the market specification and demand. The model is also able to predict operating variables like the cut-point temperatures in the Crude Distillation Unit which will result in the best outcome for the given scenario. The model formulation is illustrated, scenario based evaluations performed, and results discussed

Graphical Revamping Of A Crude Distillation Unit Under Two Variable Operational Scenarios - Naphtha Stabilizer And Reformer Operated

Energy costs represent significant parts of the total operating costs of crude refining industries. Energy integration is a typical solution to reduce heating and cooling utilities in crude refining plants through maximizing the target temperature of crude oil streams before entering the furnace. Over the past few decades, a significant progress has been made in energy integration methods including Pinch technology and mathematical programming approaches. Example of these is a graphical technique which plots Thot versus Tcold for energy analysis and revamping studies. The current research employs the Thot - Tcold diagrams in an algorithm to retrofit an existing crude atmospheric distillation unit (CDU) located in north of Egypt (Suez region). This real CDU unit is operated under two different operational modes: (i) without naphtha stabilizer; the process reformer is in operation to reform all naphtha streams without stabilization, and (ii) with naphtha stabilizer; LPG is separated from naphtha stream. The performance of the current HEN is analyzed using the graphical axes of Thot - Tcold diagrams. The graphical method is used to identify exchangers across the Pinch and recognize the potential modifications to improve the energy performance and reduce fuel consumption. Implementing the graphical identified modifications on the existing plant resulted in: (1) stabilizer scenario; energy savings are achieved by 21.1% with additional capital investment of 0.81 MM$and annual energy savings of 0.82 M$, (2) reformer scenario; the energy savings are 0.42 MM$with capital investment of 0.33 M$

Utility-Process Interface Optimization

A step-by-step procedure was obtained in optimizing the utility and process by working inwards of onion model diagram. The process plantused in the case study is the palm oil refinery, whilethe utility is the steamgeneration withturbo generator. Utility system was the first part that beingoptimized since the source of energy is coming from this system. From the optimization of utility, the marginal steam pricing plot was constructed to visualize the scope of saving as a result of steam saving at the process site. The energy saving of the process was obtained by working outthe difference of the existing to the minimum heating requirement. The amount of steam saving then used to determine the scope of saving by referring to the marginal steam pricing plot which is at $32,326.44/year. A retrofitting of the heat exchanger network was made and the estimated capital cost of installing new heat exchanger, covering the needed area was about$123,266.24. The payback period for investing the new heat exchanger with the scope saving obtained is about 4 years

Lineaarinen monitavoiteoptimointimalli kilpailevien jalostamoiden vertailuun

For benchmarking, a petroleum refining company is interested in how different market scenarios affect their competitors. This thesis is a feasibility study for the use of a multi-objective linear programming (MOLP) model for analyzing the impact of market prices on competing petroleum refineries. Linear programming (LP) models are widely used for optimizing petroleum refinery operation. The existing LP models can be utilized in the design of a MOLP model which makes it a particuarly desired model type. MOLP is a method for solving linear problems where multiple conflicting objective functions are optimized simultaneously. In this case, the different objective functions depict the profits of competing companies. Since there are several decision makers, this problem is different from those that have been extensively studied in open literature. In this thesis, a MOLP model labeled the Refinery Ranking Model (RRM) is designed. The user sets the market parameters for the RRM which then determines the optimal purchases and sales for each refining company. The results indicate that MOLP can be used to analyze the market dynamics of competing refining companies. The RRM could be expanded to include dozens of refineries and still describe their detailed behavior well and with a very reasonable solution time.Öljynjalostajille, kuten muillekin yrityksille, on hyödyllistä verrata omaa toimintaansa kilpailijoihinsa. Tämä diplomityö on soveltuvuustutkimus, joka selvittää lineaarisen monitavoiteoptimoinnin (MOLP) soveltuvuutta mallintamaan markkinatilanteiden vaikutuksia kilpaileviin öljynjalostamoihin. Lineaarista ohjelmointia käytetään laajalti öljynjalostamoiden toiminnan optimointiin. Koska öljynjalostajilla on osaamista tällaisista malleista, MOLP-mallin rakentaminen on verrattain helppoa. MOLP on menetelmä, jolla ratkaistaan lineaarisia ongelmia, joissa yritetään minimoida tai maksimoida useita keskenään ristiriitaisia tavoiteyhtälöitä. Tämän työn tapauksessa nämä tavoiteyhtälöt ovat kilpailevien öljynjalostajien tulokset. Koska kukin jalostaja pyrkii optimoimaan omaa tulostaan muista välittämättä, on ongelmassa useita päätöksentekijöitä. Tämä erottaa kyseisen tapauksen aiemmin julkisessa kirjallisuudessa käsitellyistä MOLP-malleista. Tässä työssä luodaan kilpailevien jalostamoiden toimintaa ja tuottavuutta kuvaava MOLP-malli. Käyttäjä voi syöttää malliin markkinahintoja ja muita parametreja. Työn tulokset osoittavat, että MOLP-mallia voidaan käyttää tällaiseen analyysiin. Mallia voitaisiin myös laajentaa kattamaan kymmeniä jalostamoita ilman, että tarkkuus tai ratkaisuaika kärsisivät suuresti