Refining Oil
As with many commodity chemical processes, petroleum refineries have increased in scale considerably since the first ones were built in the early 20th century. Economies of scale have played a large part in defining the current make-up of petroleum refineries.
Due in part to the expansion of distribution facilities, environmental regulations, and the removal of price controls in 1981, many of the very small scale (less than 10,000 barrels per day (BPD)) refineries have shutdown since 1980.
While considerable range still exists in world petroleum refineries, many very small scale refineries are filling either a geographic or specialty product niche.
With every refinery having a different process flow and complexity level based on the crude types fed and the product slate chosen, it is difficult to make general cost model for all refineries. Then NoDoC simulates the cost estimation based on the technologies and effective variables.
Large refineries will tend to have a greater level of complexity to optimize process economics by upgrading low quality crudes into valuable clean fuels. Smaller refineries cannot afford this level of complexity, focusing on a very limited input and output slate.
In order to provide NoDoC cost models on a more equal footing, petroleum refineries have been broken down by process unit type. Each of these process units are complicated processes by themselves, with many having been scaled considerably. Process size ranges are provided for each unit type. Please note that the capacities are for individual units at the plant and not the total amount of capacity available at the site. For example, although ExxonMobil’s Baytown refinery has 557,000 BPD of atmospheric distillation capacity, this is performed over a number of individual units.
NoDoC simulates the cost of refineries by simulating the cost of following units:
Vacuum Crude Distillation
The first step of any petroleum refinery is to feed crude oil into a distillation column to obtain the rough product cuts that will be further refined and blended downstream. Most initial distillation is done at atmospheric conditions. When feeding a heavy crude slate, bottoms from atmospheric distillation units are sometimes sent to a vacuum crude tower for further component separation.
Alkylation
This process consists of the reaction of isobutane with a mixed light olefinic (usually C3 and C4) stream to produce a high octane gasoline blending component. The resulting product is usually blended to make premium, 90 to 93 octane, gasoline. This reaction occurs at cold temperatures and low pressures, using stirred sulfuric acid as a reaction catalyst.
Aromatics
In general, aromatics units tend to be pair with more complex refineries that have both reforming capacity and a strong market for aromatics products (benzene, toluene, and xylenes). Large refineries that are paired with olefins plants also usually possess some sort of aromatics processing capacity. Raw feed from refinery reformers or heavy sections of olefins plants are sent to aromatics processing units for extraction. This is usually a physical conversion, which consists of solvents, zeolite adsorption, and distillation.
Fluidized Catalytic Cracking
A standard process in many refineries is the upgrading of gas oil to gasoline. FCC units have been present in US refineries for over 50 years, and are considered a very mature technology. In this process, a fluidized catalyst reacts with an inlet gas oil stream at high pressure to produce a predominantly unsaturated product stream suitable for gasoline blending. The catalyst is separated from exit gases in a cyclone, regenerated in a separate reactor, and then reintroduced into the process reactor.
Hydrocracking
In this process, gas oil or distillate is converted to lighter, higher octane blending components in the presence of hydrogen. Unlike an FCC unit, the process occurs over a fixed bed at high pressure. Because of the presence of hydrogen in the reactor, the product produced is saturated, with different blending properties than FCC product.
Naphtha Reforming
Many straight-run pipestill naphthas or condensates from natural gas liquid processing have low octane values due to the presence of paraffinic hydrocarbons. In order to increase the octane value and make the naphtha streams more suitable for blending, reformers are used. Reforming reactions usually occur at high temperatures over fixed-bed platinum catalysts. The product reformate is a branched, unsaturated hydrocarbon stream. Hydrogen is also produced in this reaction.
Desulfurization
Unless the crude slate is very sweet, most refinery gasoline and on-road distillate products require desulfurization to meet product specifications. This is a mature technology, using hydrogen and a fixed-bed catalyst to remove sulfur from the product stream.
Claus sulfur recovery
The Claus process is the principal process used for large scale (above ~25 TPD) sulfur recovery. The size of Claus plant used depends on the required degree of sulfur recovery, often dictated by air pollution regulations.
Due in part to the expansion of distribution facilities, environmental regulations, and the removal of price controls in 1981, many of the very small scale (less than 10,000 barrels per day (BPD)) refineries have shutdown since 1980.
While considerable range still exists in world petroleum refineries, many very small scale refineries are filling either a geographic or specialty product niche.
With every refinery having a different process flow and complexity level based on the crude types fed and the product slate chosen, it is difficult to make general cost model for all refineries. Then NoDoC simulates the cost estimation based on the technologies and effective variables.
Large refineries will tend to have a greater level of complexity to optimize process economics by upgrading low quality crudes into valuable clean fuels. Smaller refineries cannot afford this level of complexity, focusing on a very limited input and output slate.
In order to provide NoDoC cost models on a more equal footing, petroleum refineries have been broken down by process unit type. Each of these process units are complicated processes by themselves, with many having been scaled considerably. Process size ranges are provided for each unit type. Please note that the capacities are for individual units at the plant and not the total amount of capacity available at the site. For example, although ExxonMobil’s Baytown refinery has 557,000 BPD of atmospheric distillation capacity, this is performed over a number of individual units.
NoDoC simulates the cost of refineries by simulating the cost of following units:
Vacuum Crude Distillation
The first step of any petroleum refinery is to feed crude oil into a distillation column to obtain the rough product cuts that will be further refined and blended downstream. Most initial distillation is done at atmospheric conditions. When feeding a heavy crude slate, bottoms from atmospheric distillation units are sometimes sent to a vacuum crude tower for further component separation.
Alkylation
This process consists of the reaction of isobutane with a mixed light olefinic (usually C3 and C4) stream to produce a high octane gasoline blending component. The resulting product is usually blended to make premium, 90 to 93 octane, gasoline. This reaction occurs at cold temperatures and low pressures, using stirred sulfuric acid as a reaction catalyst.
Aromatics
In general, aromatics units tend to be pair with more complex refineries that have both reforming capacity and a strong market for aromatics products (benzene, toluene, and xylenes). Large refineries that are paired with olefins plants also usually possess some sort of aromatics processing capacity. Raw feed from refinery reformers or heavy sections of olefins plants are sent to aromatics processing units for extraction. This is usually a physical conversion, which consists of solvents, zeolite adsorption, and distillation.
Fluidized Catalytic Cracking
A standard process in many refineries is the upgrading of gas oil to gasoline. FCC units have been present in US refineries for over 50 years, and are considered a very mature technology. In this process, a fluidized catalyst reacts with an inlet gas oil stream at high pressure to produce a predominantly unsaturated product stream suitable for gasoline blending. The catalyst is separated from exit gases in a cyclone, regenerated in a separate reactor, and then reintroduced into the process reactor.
Hydrocracking
In this process, gas oil or distillate is converted to lighter, higher octane blending components in the presence of hydrogen. Unlike an FCC unit, the process occurs over a fixed bed at high pressure. Because of the presence of hydrogen in the reactor, the product produced is saturated, with different blending properties than FCC product.
Naphtha Reforming
Many straight-run pipestill naphthas or condensates from natural gas liquid processing have low octane values due to the presence of paraffinic hydrocarbons. In order to increase the octane value and make the naphtha streams more suitable for blending, reformers are used. Reforming reactions usually occur at high temperatures over fixed-bed platinum catalysts. The product reformate is a branched, unsaturated hydrocarbon stream. Hydrogen is also produced in this reaction.
Desulfurization
Unless the crude slate is very sweet, most refinery gasoline and on-road distillate products require desulfurization to meet product specifications. This is a mature technology, using hydrogen and a fixed-bed catalyst to remove sulfur from the product stream.
Claus sulfur recovery
The Claus process is the principal process used for large scale (above ~25 TPD) sulfur recovery. The size of Claus plant used depends on the required degree of sulfur recovery, often dictated by air pollution regulations.
