BACKGROUND OF THE INVENTION 1. Field of the Invention.

[02] This invention relates to facilities for the refinement of crude oil.

2. Description of Related Art [03] Crude oil refinement processes are well known and described in the prior art.

Large-scale oil refinement is accomplished by combining one or more processes to manufacture products meeting specific specifications. All processes involved in the refinement of crude oil involve heating of crude oil and/or its hydrocarbon component (s) to various temperatures to achieve separation of fractions, cracking of long hydrocarbon chains, or modification of molecules. Many specific processes are proprietary, either covered by patents or hidden as trade secrets, but are typically licensed to design firms for use in crude oil refining and can be utilized in the inventive system disclosed herein.

[04] Large-scale oil refinement is typically accomplished using equipment designed to process large volumes of fluids. Refineries may produce a wide and varied range of products that is determined by the basic design of the facility. However, all large-scale refinement produces products to exacting specifications. To achieve this level of quality, tight restrictions must be placed on the crude oil feedstock used in the facility.

[05] Large-capacity crude oil refinement facilities are often designed and constructed with large equipment to capitalize on the economic advantages resulting from high-volume processing and economies of scale. The high-volume flow rates of the crude and/or product streams require large bore piping in the refineries. This type of refinery design has traditionally been constructed in place.

[06] Production capability of all equipment regardless of size is limited by both maximum throughput and minimum throughput. The range of maximum to minimum rate, commonly referred to as turndown capability, is often a controlling design factor of a facility.

[07] It has been considered uneconomical to construct high-volume oil refinement facilities from multiple smaller production units. However, prior analysis has been based on a construct-in-place method economic model. Further, consideration was not given to the economic benefits of mass production and construction processes obtained when fabricating multiple identical skids and equipment.

[08] A small capacity skid-mounted mobile refinery is described by Hogan in U. S. Patent Nos. 3,953, 298 and 4,039, 130. The Hogan refinery is designed to be transported over a highway and has a throughput capacity of 750-1,500 barrels per day (bpd). Similarly, a small-capacity, truck-mounted diesel fuel cracking unit for use in refining waste petroleum products at a reservoir or storage tank site is disclosed by LeBlanc et al. in U. S. Patent No.

5,316, 743.

SUMMARY OF THE INVENTION [09] The present invention provides an alternative method for the design and construction of a large-capacity crude oil refinery using a combination of multiple small-and/or medium-sized refining units. Each small refining unit is constructed by connecting several equipment modules or skids capable of being transported from a factory to a project site by truck, sea transport containers, or railway containers. Each equipment module or skid houses a component system that may be placed on a concrete foundation and interconnected in the field with other skid mounted components to create a small, self-contained refining unit. The refining units may operate independently or likewise be interconnected in combination as determined by the processing needs.

[10] The small, individual equipment modules are supported via standard structural shapes connected in such a manner as to provide support for individual equipment, piping, and electrical wiring for power and control as may be placed on skids. The structural shapes also provide a framework that provides the ability for the entire contents of the modules to be lifted for placement onto a truck, into shipping containers, and onto support foundations. The equipment modules are designed to allow simple, quick connections between multiple modules in the field using standard piping and electrical components to provide a complete refining unit.

[11] In one embodiment, the invention provides for the installation of multiple refining units to form a large-capacity, crude oil process refinery. The possible refining processes for which a modular refinery may be used include, but are not limited to, the following: atmospheric distillation, vacuum distillation, hydrotreating, catalytic reforming, isomerization, hydrocracking, catalytic cracking, delayed coking, residue reduction, asphalt, gasoline blending, sulfur recovery, ethylene processing, hydrogen production, and liquid petroleum gas (LPG) production.

[12] In another embodiment, the invention may be configured to stack the skids in a refining unit on top of each other, rather than adjacent to other modules on the ground, to create a vertical crude/vacuum refinery unit. A vertical refining unit may provide a complete crude distillation process system combined with a complete vacuum process system for distillation, separation, stripping, and/or removal of petroleum fractions such as liquid petroleum gas (LPG), gasoline, naphtha, kerosene, gas-oils and residue, and particulate from crude oil.

[13] Other features, utilities, and advantages of various embodiments of the invention will be apparent from the following more particular description of embodiments of the invention as illustrated in the accompanying drawings and defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS [14] Figure 1 is a plan view of a large-capacity modular refinery comprised of multiple medium capacity modular processing units.

[15] Figure 2 is a magnified plan view of Figure 1 focusing on the central grouping of five identical medium capacity modular processing units.

[16] Figure 3 is a plan view of an individual medium sized modular processing unit as shown in Figures 1 and 2 composed of smaller specific processing components.

[17] Figure 4 is a magnified plan view of Figure 1 focusing on the single delayed coker unit.

[18] Figure 5 is a schematic diagram of a large, prior art oil refinery facility.

[19] Figure 6 is a schematic diagram of a modular oil refinery facility according to a first embodiment of the present invention.

[20] Figure 7 is a schematic diagram of the processing flow of a modular oil refinery according to a second embodiment of the present invention.

[21] Figure 8 is a schematic diagram of the processing flow of a modular oil refinery according to a third embodiment the present invention.

[22] Figure 9 is a schematic diagram of the processing flow of a modular oil refinery according to a fourth embodiment of the present invention.

[23] Figure 10 is a schematic design of the processing flow of a modular oil refinery according to a fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION [24] Figures 1 and 2 depict an exemplary embodiment of a large-capacity modular refinery 100 comprised of five modular refining units 300a-e configured in parallel. Greater or fewer refining units 300 (see Figure 3 for detail of an individual unit) may be combined depending upon the particular processing needs. A coker unit 400 with modular, skid-mounted equipment systems may additionally be connected to the modular refining units 300a-e.

Construction of a large-scale refinery using multiple small-or medium-sized, refining units 300a-e with skid-mounted process components allows the start-up and production of crude oil <BR> <BR> immediately upon installation of a single refining unit, e. g. , 300a, while installation of<BR> additional refining units, e. g. , 300b-e, continues. Further, the capacity of a modular refinery 100 may be increased or decreased over time depending on growth or demand by simply adding or removing a refining unit 300.

[25] As shown in Figure 1, an exemplary embodiment of the large-capacity modular refinery 100 may have other components in addition to the modular refining units 300a-e. A thermocracking unit 102 may be provided to interface with the modular refining units 300a-e.

Thermocracking is the process of modifying long hydrocarbon chains into smaller, more-valuable hydrocarbons. There are many types of thermocracking processes available, many of which are proprietary, and as with all processes each can be customized to produce the product slate desired from the feedstock provided. However, the purpose of any thermocracking process is the same: to take low-quality, low-value product and create high-quality, high-purity hydrocarbon streams with little or no residue that are of high value.

One such thermocracking process, hydrocracking, uses a feedstock such as vacuum gas oils (VGO). The feedstock is heated, introduced into a reactor vessel, and mixed with a hydrogen stream in the presence of a catalyst. The reaction vessel operates at extremely high temperatures and pressures. The combination of temperature, pressure, and the presence of free hydrogen molecules trigger simple chemical reactions. Cracking occurs by breaking longer hydrocarbon chains into smaller hydrocarbon chains that are more desirable. The exemplary modular refining units 300 of the present invention are shown incorporating individual hydrocracking sections, which are described in greater detail below.

[26] The large-capacity modular refinery 100 may also have a sulfur recovery unit 104. A sulfur recovery unit may provide several processes for removing sulfur from refined streams, gas, and water, for example, sour water stripping where ammonia and entrained hydrogen sulfide are removed. Flare stacks 106 may also be provided for burning off excess or unwanted byproducts of the refining process. The flare stacks 106 may further be used in upset conditions, for example, to remove hazardous materials when performing a refinery shutdown. Liquid gas pressure tanks 108 may be provided for the storage of LPG's resulting from the refining process. Further, a pump house 110 and water tank 112 may be provided for use in extinguishing a fire in case of an emergency.

[27] Construction time of the large-capacity modular refinery 100 is reduced through the interconnection of the modular refining units 300a-e as shown in increased detail in Figure 2, as small shippable equipment modules or skids may be fabricated in a factory and simply placed on foundations and connected together in the field. Relocation of all or part of the modular refinery 100 may be rapidly accomplished by disconnecting the equipment modules of each of the refining units 300 in the field, placing the individual equipment modules on trucks, transporting the equipment modules to the new location, and reconnecting the equipment modules. The number of modular refining units 300 used depends on the capacity and client product requirements.

[28] Figure 3 shows an arrangement of an exemplary embodiment of an individual, modular crude oil refining unit 300. A typical modular refinery unit 300 may be designed to process, for example, 5,000, 10,000, 15,000, or 20,000 bpd of crude oil. A modular refining unit 300 may be composed of three primary operational sections: a crude oil atmospheric distillation section, a vacuum distillation section, and a hydrogen treatment section.

Separating hydrocarbon fractions from crude oil is typically accomplished through a simple atmospheric distillation process. Two factors, crude oil composition and the desired final product (s), determine the final distillation process requirements, including operating parameters, flow rates, temperatures, and pressures, as well as equipment requirements.

[29] In the atmospheric distillation section of the modular refining unit 300, crude oil from a well head, storage tank, or other supply source is heated to a temperature that allows vaporization of the desired fractions. Heating does not exceed 900°F to prevent cracking of the individual hydrocarbon chains. The crude is heated by passing the crude through a series of heat exchanger modules 302 that use products from the distillation process itself to recapture the stored heat in the stream, by directly heating the crude oil in a dedicated heat source, crude heater module 304, or a combination of both. The recapturing of heat from the products through heat exchanger modules 302 is a common step to reduce energy costs of the system although not necessary for the process. For crude oils having a high-entrained salt content, the crude is heated to an elevated temperature, mixed with water, and processed by a desalinization module 306, which separates the water from the oil. The water is used to wash the salts from the crude leaving the crude relatively clean of salt. The clean crude then continues the process of heating.

[30] After the crude oil attains the temperature required for the process, the oil is passed through a flash drum module 308 where the certain fractions of the oil having boiling temperatures lower than the boiling temperature of the crude oil are released from the crude.

The remaining liquid crude oil enters the lower portion of the atmospheric distillation column 310 while the vapors from the flash drum module 308 enter the mid to upper section of the atmospheric distillation column 310. The atmospheric distillation column 310 is where the actual separation of the hydrocarbon fractions occurs. The atmospheric distillation column 310 may be a separate skid-mounted module. The column temperature varies from a high temperature at the bottom to lower temperature at the top.

[31] The atmospheric distillation column 310 is designed with internal configurations that force a mixing of vapor streams that move up the column with condensing liquids that move down the column. Through this process, the various fractions are separated with fairly high purity. The various fractions are removed from the atmospheric distillation column 310 at various elevations that are determined by column temperatures. Liquid fractions are typically sent to small stripper columns on stripper module 312 where the fractions are distilled once more to remove additional lighter fractions, which are reintroduced into the atmospheric distillation column 310. Other miscellaneous equipment, for example, pumps 314 on stripper module 312 and compressor module 316, are used to move liquids or vapors, while the heat exchanger modules 302 are used to exchange heat from the hot fraction streams to the cold crude oil stream.

[32] The main hydrocarbon fractions of interest in refining that are obtained from crude distillation crude oil are LPGs (methane, ethane, propane, and butane), straight run gasoline, naphtha, kerosene, and light and heavy gas oils. The remaining liquid is a heavy liquid commonly referred to as residue, atmospheric gas oil (AGO), or atmospheric bottoms. This residue liquid contains mainly hydrocarbon molecules that are heavy and have very high boiling temperatures, for example, asphalts. However, there are still additional desirable fractions such as gas oils entrained within the residue.

[33] To remove the desired entrained fractions remaining in the atmospheric column residue, the residue is subjected to additional distillation processing in the vacuum distillation section. A vacuum heater module 338 heats the residue from the atmospheric distillation column and passes the heated residue to a vacuum column module 318 where the pressure is reduced to significantly reduce boiling temperatures. A vacuum pump module 340 creates a vacuum in the vacuum column module 318 to reduce the pressure. A flash distillation process occurs in the vacuum column module 318 in which the boiling of the liquid residue and subsequent release of vapor cools the liquid residue. Steam generated by the power plant boiler module 320 is introduced into the vacuum column module 318 to maintain heat and provide a means of control for the vacuum system. Gas oils resulting from the flash distillation process are pulled off the vacuum column module 318 in to the vacuum separator module 342 and residue, typically termed vacuum bottoms, remains for use other processes if desired.

[34] A hydrotreating section may further be provided in the modular refining unit.

Hydrotreating is a process wherein certain hydrocarbon fractions undergo chemical reactions to remove or modify certain undesirable sulfur molecules that are part of the hydrocarbon chain. The actual process is dependant on the fluid stream composition, quantity of sulfur, and the desired effects.

[35] In a typical hydrotreating process, a hydrocarbon stream, for example, from the atmospheric distillation section or the vacuum distillation section, is mixed with hydrogen generated by a hydrogen plant module 348. This mixed stream is heated to 500-800°F in a hydrotreating heater module 336 and passed through a hydrotreating column module 322 that operates as a reactor vessel filled with a catalyst that precipitates the occurrence of several reactions. The hydrogen (H2) combines with the sulfur atoms to form hydrogen sulfide (H2S4), a gas free from the hydrogen molecule. Some of the nitrogen compounds are converted to ammonia (NH4). Some of the metals entrained in the mixed stream are deposited on the catalyst. Finally, if present, any olefins, aromatics, or naphthenes become hydrogen saturated and some cracking occurs, resulting in the creation of some LPG products.

[36] The treated stream from the hydrotreating column module 322 is sent to a hydrogen separator module 324 where the excess hydrogen is removed, sent to a hydrogen recycle compressor module 328, and returned to the unheated feed stream. The product stream exits the separator module 324 and enters a flash vessel 326, which in this embodiment is part of the separator module 324, where light gases, such as LPG, hydrogen sulfide, and some ammonia are vented to an overhead system for treatment in downstream processes. When the process requires light gases to be completely removed, a small fractionator column module 330, commonly called a stabilizer, is added downstream of the flash vessel 326 where a small distillation process occurs. Products are removed and sent to downstream processing units or storage. The column bottom residue may be sent to a secondary heater, heated, and returned to the hydrogen separator for additional distillation or in some designs the heated column bottom residue is sent to a second stage reactor where it is mixed with hydrogen and allowed to further react and break the remaining long hydrocarbon chains. The primary purposes of hydrotreating is to remove certain sulfur compounds and metals that poison catalysts used in downstream processes and to remove sulfur compounds that, when burned, produce obnoxious fumes and are contributors to air pollution. Other proprietary processes are used to remove the sulfur compounds or to modify them to less offensive compounds.

[37] Each modular refining unit may also include a cooling tower 346 to provide water for the heat exchangers 302 for both the atmospheric distillation section and the vacuum distillation section. Pipe racks 354 run throughout each modular refining unit 300 to provide for fluid flow within the modular refining unit 300 and fluid interconnection between the modular refining units 300 and other component systems of the large-capacity, modular refinery. A motor control center module 350 houses the electrical generation motors and their controls for supplying power to the modular refining unit. A control room module 352 may be provided to house computer systems and other system control equipment for operating the modular refining unit 300. The control systems in the control room module 352 may be designed whereby a single control room module 352 may control all of the modular refining units 300, as well as any other units that make up the large-capacity, modular refinery 100. The control systems may also be connected to a remote location, for example, via a satellite link, to allow monitoring of the facility by an offsite team of engineers. These engineers can provide notice to control operators of potential equipment failures, review for identification of operational errors, and provide a direct resource for troubleshooting problems.

[38] A modular refining unit may further include an isomerization unit 332. Isomerization is the process of modifying the hydrocarbon molecule arrangement. Two types of isomerization are used within a refinery. Butane isomerization is usually found in facilities that have alkylation process, as isobutene is consumed in the process. Paraffin isomerization is utilized in refineries that have a primary product output of high-octane gasoline. The isomerization process converts normal pentanes and hexanes into isopentanes and isohexanes.

[39] For example, presuming the isomerization unit 332 performs a paraffin isomerization process, feedstock from the hydrotreater, crude distillation column, thermocracker, or other source of naphtha may be used. The feedstock stream or streams are sent to a feed fractionator column that concentrates the normal pentanes and hexanes by separating the isomers of these chains. With the isomers removed; the normal paraffins are mixed with hydrogen and organic chlorides and fed into a reactor vessel. The reactor catalyst causes approximately half the feed stream to be converted to isomers (isomerate). The resulting stream is discharged to a simple flash tank where excess hydrogen is removed and recompressed in a hydrogen recycle compressor for remixing into the incoming feedstock.

The product stream empties from the flash tank into a stabilizer column where the LPGs are removed. The remaining isomerate stream is remixed with the isomer stream from the feed fractionator column. In some processes an additional column called a splitter is located downstream of the stabilizer column to separate the normal hexanes for recycling and conversion into isohexanes.

[40] A modular refining unit may additionally include a reformer unit 344. Reforming is similar to isomerization in that the process reforms the feed stream hydrocarbon molecules into isomers of the molecules. However, the additional reactions occur in the process, some of which are beneficial and some of which are not. Naphtha is typically the feedstock for reforming. The reactions occur in a series of three or more reactors depending on the process design. Each reactor performs a different process function. Each reactor operates between 200 and 500 psi and between 900-975°F. The feed stream is mixed with a hydrogen stream, heated, and introduced into the first reactor where it passes through a platinum catalyst. The stream passes from the first reactor to the second and then to the third. The stream passes through a platinum catalyst in each reactor. Output from the third reactor, the stream, which is a vapor at this temperature, is cooled and passed to a hydrogen separator where the excess hydrogen is removed. The process is a generator of hydrogen, but additional hydrogen is supplied to ensure an adequate hydrogen volume for the reaction, thus preventing carbon molecules from depositing on the platinum catalyst. The stream is discharged from the hydrogen separator to the stabilizer column where the lighter formed fractions are removed.

The remaining stream or reformate is then discharged to downstream processes or operations.

[41] A gasoline blending unit (not shown) may further be incorporated into the modular refining unit 300. Gasoline blending is the blending of straight run gasoline, if available, with isomerate, reformate, and naphtha along with certain other additives to produce a fuel for internal combustion engines. The necessary equipment modules may consist of pumps, a method for injection of measured quantities, and storage facilities.

[42] In addition to the modular refining units 300, the large-capacity, modular refinery 100 may further include a delayed coker unit 400 as detailed in Figure 4. The delayed coker unit 400 converts vacuum tower residue or other heavy hydrocarbon fractions from the modular refining units 300 into coke, a solid, coal-like substance, used for fuel or as material for industrial processes, for example, the production of high-quality steel. A pipe rack 436 provides fluid interconnection between the delayed coker unit 400 and the modular refining units 300.

[43] Feedstock for the delayed coker unit 400 is preheated by exchanging heat with coker oil products in heat exchangers 404 on a fractionator and stripper module 402. Additional heat exchangers 438 may be utilized by the processes of the delayed coker unit 400. The preheated feedstock then enters the bottom of a coker fractionator column module 406 where it mixes with recycled product that is condensed in the bottom of the coker fractionator column 406. The mixture is then heated further by pumping the mixture through the coker heater module 408 where the mixture reaches approximately 1000°F. At this temperature, severe thermocracking of the hydrocarbon chains occur. The feedstock is then fed from the coker heater module to the a coke drum module 410 at high velocities to prevent coking (i. e., coke build-up) within the coker heater tubes and blockage of the system. To maintain the velocities required to prevent formation of coke within the coker heater tubes, steam from a steam drum module 412 is injected into the tubes to raise the stream velocity. Steam is extensively used in the process and can be generated using waste heat of the process. Steam is generated and stored on the steam drum module 412.

[44] The stream enters the bottom of the coke drum module 410. In the coke drum 410, vapors rise and are sent to a fractionator column 414 on the fractionator and stripper module 402 where small amounts of refinery products are removed. In the fractionator column 412, overhead oil vapors are captured at the top and sent to a fractionator overhead drum 416, also on the fractionator and stripper module 402. Product streams from the fractionator column 412 are pumped to upstream processes by product pumps 418 on a condensate skid 420.

Sour water is stripped from the stream by the stripper portion of the fractioner and stripper module 402 and sent to the sulfur recovery unit 104. The remaining oily products are cooled by exchanging heat with incoming cold feed. The remaining liquid in the coke drum module 410 continues to crack existing chains until a solid coke is formed.

[45] The solid coke is removed from the coke drum 410 by the use of a high-pressure water jet, for example, operating at 2000 psi, supplied by the decoking water tank module 422. The jet is used to cut the coke from the drum and the coke is collected within a catch or settling basin or settling maze module 434, and the water is recycled and returned to the water tank module 422. The coke drum 410 is cooled during a cool down cycle. During this cool down, steam and wax tailings flow to a blowdown drum module 424 where they are condensed by heat exchange with a cooled circulating oil stream. The diluted wax tailings are withdrawn from the bottom of the blowdown drum 424 and pumped to an oil cooler 426 on a blowdown module 428. Excess oil is removed and sent to the fractionator column 412.

Light hydrocarbon gases and steam from the top of the blowdown drum module 424 are collected and sent to a blowdown condenser 430, also on the blowdown module 428. After condensing, the mixture is separated and water is sent to the decoking water tank module 422. Light hydrocarbon vapors from the settling maze 434 are cooled and compressed by a compressor 432 and separated from condensed liquids in a knock-out drum 440 on the condensate module 420. The liquids are pumped to a slop oil tank storage (not shown) and the vapors are recycled through the coker fractionator column 406.

[46] The limitations of a prior art large-capacity refinery are depicted schematically in Figure 5. Typically a prior art large refinery will have a single feedstock input and a single output with little scalability in throughput. As depicted schematically in Figures 6-10, the modular refinery 100 of the present invention is completely scalable and can operate with as many or as few modular refining units as desired or required to fit the needs of a particular situation. Crude input to the modular refinery may be from a single stock stream as shown in Figure 6 or from individual stock streams as shown in Figure 7. Likewise, output from the modular refinery may be divided into singular outputs from each of the refining units as shown in Figure 6 or the output from each of the refining units may be combined into a single flow as shown in Figure 7.

[47] Greater control of the refining process may be achieved by using extensive process controls and computer-controlled optimization software that may run on a stand-alone processor as part of a distributed control system for the entire modular refinery system or on individual refining unit control systems. Electrical connection and control of and between the modular units is denoted in Figures 6-10 by the dashed connection lines. The control facilities may be connected to a remote location via satellite link to allow monitoring of the facility by an offsite team of engineers. These engineers can provide notice to control operators of potential equipment failures, review for identification of operational errors, as well as provide a direct resource for troubleshooting problems.

[48] One of the benefits of constructing a large-scale, modular refinery 100 from multiple small-and medium-sized refining units 300 is the resulting greater overall turndown capability. Volume demands of downstream processes vary according to refinery sales. The large-capacity modular refinery design provides greater control of volume of crude processed by allowing one or more of the distillations and vacuum systems to be shut down while allowing the remaining operating distillation and vacuum systems to be operated at various capacities between 50% and 100% of capacity, to provide the exact production volumes required as demand fluctuates. For example, by connecting five 20,000 bpd refining units 300 to form a 100,000 bpd capacity modular refinery 100, greater operational flexibility is obtained. One such example of flexibility is the shutdown of one or more of the 20,000 bpd refining units as depicted in Figure 8, as well as individual turndown capability within each refining unit.

[49] In a typical prior art refinery with a turndown capability of 50% of the maximum capacity, there is an inflexible limitation on the ability of the refinery to process a particular quantity of feedstock. If a prior art refinery has a 100,000 bpd capacity with a turndown capacity of 50%, it has a minimum throughput requirement of 50,000 bpd. However, with the modular refinery design of the present invention, assuming each 20,000 bpd refining unit has a similar 50% turndown capability, the minimum requirement for this 100,000 bpd facility is only a 10,000 bpd throughput. Thus, more flexible turndown capability can be achieved than the usual, inflexible fifty-percent typical of standard design and construction.

[50] Crude oil is available on the commercial market from a wide variety of supply sources. Each source produces crude having unique characteristics such as API gravity, sulfur content, entrained hydrocarbons fractions, and salts and minerals. In conventionally designed refineries, the processing of crude oil from two or more sources is accomplished by blending the crude upstream of the crude distillation unit and processing the blend. Blend processing has met with mixed success at best in the past.

[51] By using multiple combined systems of modular refining units, the need for upstream blending is eliminated because each crude feedstock can be processed in a separate refining unit by a process designed to account for the unique characteristics of the feedstock, and the products can be blended downstream. Processing with multiple combined refining units provides the flexibility to process various grades of crude oil simultaneously in separate crude and vacuum process systems at optimum process temperatures and pressures for the individual crude being processed. Mixing fraction streams from multiple crude streams of varying qualities downstream of the distillations processes affords maximum fraction separation while minimizing common problems that occur when multiple crude streams of varying qualities are mixed upstream of the distillation process system. The processes made possible by the present invention thereby substantially reduce common problems inherent in upstream blending. This concept is depicted in Figure 9 wherein two refining units process a first stock stream while a third refining unit separately processes a second stock stream. In this example, the outputs are kept separate. This allows a single refinery to process a wide spectrum of crude feeds having varying characteristics and meet product specifications.

[52] Additional flexibility can be obtained through the combination of multiple small-or medium-sized refining units with larger refining units. Low-volume product streams from each small-or medium-volume unit can be combined and further treated in single, larger units, as shown in Figure 10, to allow maximum flexibility while minimizing operational costs. Additionally, several of the refining units may initially perform one processing step after which the output is transferred to one or more additional refining units in the modular refining facility for additional processing steps to produce a finished product. The modular refining units may be combined in various manners and numbers to support multiple refining processes, for example, atmospheric distillation, vacuum distillation, hydrotreating, isomerzation, and catalytic reformation.

[53] In another embodiment of the invention, the various skids or modules in each refining unit 300 may be stacked on top of each other to provide a large-capacity, modular refinery in a vertical orientation. The vertical refining unit provides a complete crude distillation process system combined with a complete vacuum process system for distillation, separation, stripping and/or removal of petroleum fractions such as liquid petroleum gas (LPG), gasoline, naphtha, kerosene, gas-oils and residue, and particulate from crude oil. As with the ground-based refining units previously described, the vertical mounting of modules in a refining unit may provide single output capacities, for example, from 5,000 bpd to 200,000 bpd or multiple outputs wherein each refining unit may be capable of, for example, 5,000 to 20,000 or more bpd arranged to provide processing volumes required.

[54] A vertical refining unit may consist of a crude column, a vacuum column, a crude oil heater, a vacuum column feed heater, and a structure having multiple levels or stories for support and access to pumps, heat exchangers, strippers, separators, flash drums, piping, valves, and other miscellaneous vessels and equipment required for the process of crude oil distillation. Each level may be individually factory constructed complete with equipment and vessels mounted, interconnecting piping, valves, instruments, other miscellaneous equipment, electrical and instrumentation wiring, grating or other platform material, handrail, structural cross bracing, and stairways. The individual levels may be field assembled by placing the initial level atop a foundation and securing it place with structural bolts. Additional levels may be added by bolting an upper level onto a lower level, completing the mating pipe connections, and finishing the electrical and instrumentation wire connections at the junction boxes.

[55] With conventional refinery design and construction, pumps, heat exchangers, and vessels are placed at grade and process fluid piping is run from nozzles located at various positions on the columns to the equipment at grade and/or back up to various locations on the columns. Each grade level equipment module and vessel must be placed on its own individual foundation. Conventional design also requires a significant plot area to physically place the numerous amounts of equipment and vessels while providing suitable maintenance access. Further, conventional design connects these individual equipment and vessels by utilizing significant pipe runs, which result in significant pressure losses and significant pump head (s). To overcome these pressure losses and high pump heads, pump sizes are increased.

Increased pump size requires larger electrical drivers and pipe diameters, which in turn result in higher initial capital costs. The longer pipe runs increase the need for pipe supports and associated infrastructure.

[56] In contrast, the multiple-level, vertical refining unit places equipment close to the vertical location of each nozzle. This approach improves the fluid flow design of the system and minimizes pipe run lengths, which result is lower pressure losses. The resulting reduction in pressure loss significantly reduces or eliminates the need for larger pumps and allows for minimum pipe diameters. This results in a reduction in initial capital costs for piping and pumps as well as significant reductions in operating costs over conventional refineries during the life of the modular refining system. The vertical skid design reduces the facility foot plan, provides for minimum pipe lengths, greatly reduces pipe supports, and eliminates additional support infrastructures such as pipe support foundations. The multiple-level, vertical skid design may use a single foundation system, thus reducing site foundation layout, excavation, forming, and concrete finishing, all reducing the capital costs of the project. The compact design allows new construction to minimize property requirements and allows existing facilities to add a multiple-level, crude/vacuum refining unit in an area normally required for a conventional single component.

[57] The multiple-level, vertical skid design also reduces field construction time and costs because of the extensive utilization of shop fabrication and fit-up. In addition, the design minimizes existing facility down time during construction. Unlike conventionally constructed crude and vacuum refineries that are constructed in the field for permanent operation at a single site, the combination crude/vacuum vertical refining unit provides a fully bolted construction that allows complete tear down and reassembly at a different site with minimal site specific engineering and construction.

[58] Although various embodiments of this invention have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular embodiments and not limiting. Changes in detail or structure may be made without departing from the basic elements of the invention as defined in the following claims.