Refinery operating scenarios

On a qualitative basis, the estimates of recovered sulfur from refinery operations appear to be the most secure. Except for district IV, which depends heavily on the ultimate productivity of the Overthrust Belt, estimates of sulfur production from sour natural gas also seem reliable. The heavy crude oil sulfur output estimate is reasonably firm. Oil shale, tar sands, heavy oil and in situ coal combustion will produce little sulfur even under optimistic scenarios. The smelter acid projection is weak. Metal output may... 

In this section, we present two examples with different scenarios. The first example illustrates the performance of the model on a single site total refinery planning problem where we compare the results of the model to an industrial scale study from Favennec et al. (2001). This example serves to validate our model and to make any necessary adjustments. The second example extends the scale of the model application to cover three complex refineries in which we demonstrate the different aspects of the model. The refineries considered are of large industrial-scale refineries and actually mimic a general set-up of many areas around the world. The decisions in this example include the selection of crude blend combination, design of process integration network between the three refineries, and decisions on production units expansion options and operating levels. 

In this scenario, the three refineries are using a single feedstock type, Arabian Light, and operate centrally with no network integration alternatives. The major model constraints and results are shown in Tables 3.3 and 3.4, respectively. The three refineries collaborate to satisfy a given local market demand where the... 

In all previous scenarios, we did not change the market demand and, therefore, there was no expansion in the production unit capacities of the refineries. In this scenario, we will simulate a change in market demand and examine the modifications suggested by the model. Table 3.7 illustrates the new major operating constraints. 

Bitumen in tar sand deposits represents a potentially large supply of energy. However, many of these reserves are only available with some difficulty and optional refinery scenarios will be necessary for conversion of these materials to low-sulfur liquid products (Chapter 9) because of the substantial differences in character between conventional petroleum and tar sand bitumen (Table 1-6). Bitumen recovery requires the prior application of reservoir fracturing procedures before the introduction of thermal recovery methods. Currently, commercial operations in Canada use mining techniques for bitumen recovery. 

The acceptance of heavy oil and bitumen as refinery feedstocks has meant that the analytical techniques used for the lighter feedstocks have had to evolve to produce meaningful data that can be employed to assist in defining refinery scenarios for processing the feedstocks. In addition, selection of the most appropriate analytical procedures will aid in the predictability of feedstock behavior during refining. This same rationale can also be applied to feedstock behavior during recovery operations. Indeed,... 

Pure simulation approaches are proposed by Pitty et al. (2008) and Adhitya and Srini-vasan (2010). Pitty et al. (2008) propose a discrete-event simulation model for a refinery supply chain. Operational decisions such as unloading schedules and production planning are made based on simple priority rules. Various configurations of the modelled SC are studied and compared to reveal optimization potentials. This approach explicitly considers some details of ship and pipeline transports. Adhitya and Srinivasan (2010) describe a discrete-event simulation model for an SC producing and distributing lubricant additives. Here, batch production is modelled. Again, operational production decisions are made by priority rules and a scenario analysis is conducted to evaluate the effects of other priority... 

Oil and gas plants and gas industries use the same basic equipments (pumps, tanks, vessels columns etc.) because the basic physics and chemistry of hydrocarbon and gas processing is the same everywhere. Therefore the scenario types for various types of equipment might be categorized by risk analysis, accident history and operational experience. Accidents in oil and gas plants in one oil and gas operating company which includes six oil fields producing more than one million barrels of crude oil, 500 M ft gas, and 6500 barrels of liquified natural gas per day. Over a time period between 1985 to 2009 were assessed. This company has 7 operation units, 4 distillation plants, 10 gas compressor stations, 3 liquified gas plants, a gas refinery, and one water treatment plant. 

Sharing of past major incidents with other oil and gas industries provides useful input data for similar process industries in order to identify the most critical barriers and improve their safety processes. One poignant example highlights this matter. In 1998 there was an accident in the gas compression stage of a Middle East oil and gas plant which caused 7 dead as a result of fuel accumulation and vapor cloud explosion which was very similar to the Texas City Refinery disaster on March 23, 2005 in which a distillation tower was overfilled and an uncontrolled release of hydrocarbons led to a major explosion and fires. Fifteen people were killed and 180 were injured in the worst disaster in the United States in a decade. In both incidents, excess hydrocarbons were diverted into a pressure relief system that included a blowdown stack. In the Iranian case, it was equipped with a flare, but one which the operator didn t ignite in Texas City the blowdown stack was not equipped with a flare to burn off hydrocarbons as they were released. As a result, the flammable overflow from the tower entered the atmosphere. Ignition of the escaped hydrocarbons was enabled by startup of a nearby vehicle resulted in the explosion and subsequent fires (Hopkins, 2008). This example shows the repetitive patterns of accidents, and root causes of events all over the world in this sector. The lesson of this paper is that accidents in one country, where the scenarios are very similar, can and should serve as lessons to prevent the same scenario being actualized in other countries. 

In this section, more details about how the different components and modules within CAPE-SAFE will work within the integrated picture of PEEE. Case studies wiU be used from different plant types i.e. continuous and batch plants, as well as oil refinery process to show the mechanism of CAPE-SAFE following some scenarios. Other scenarios will be illustrated for the integration with some components within PEEE such as fault detection system, RCM-based CMMS, and operator interface system. 

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