Micro Refineries

Introductory Information

OGDC  specializes in Project managing the EPIC of skid mounted modular crude oil refineries that process from 300 to 12,000 barrels per day (15,000 to 600,000 metric tons per year) of crude oil.

The design comes in standard sizes of 300 bpd (15,000 metric tons per year), 600 bpd (30,000 metric tons per year), 1,000 bpd (50,000 metric tons per year), 3,000 bpd (150,000 metric tons per year) 6,000 bpd (300,000 metric tons per year) and 12,000 bpd (600,000 metric tons per year).

The basic crude oil atmospheric distillation unit (ADU) produces naphtha, kerosene, diesel and #6 fuel oil.  Additional processing units can be supplied  that are capable of producing specification high-octane motor fuel, commercial jet fuel, low sulfur diesel, fuel oil and asphalt.  Two or more plants can be installed on a single site allowing the simultaneous processing of more than one type of crude oil and one plant can still be in operation in the event that one plant is down.  The plant sizes can be increased in stages.

Larger ADU plants (3,000 to 12,000 bpd):·

•  Can be set up and be in operation within several weeks after arrival at a fully-prepared and completed site.
• Allow a single operator to restart the plant from a cold start in less than four hours and have the plant in full operation.
• Are completely automated and once an operator sets all the controlling points, all product temperatures and flows are controlled automatically. 
• If a product specification drifts off, or if a potentially hazardous condition develops, the plant automatically turns itself off to a safe condition without the help of an operator.
• Require only a flat support area or concrete slab.
• Require no water or instrument air.

OGDC can supply the following additional equipment for its distillation units:

• Special alloy construction for processing high sulfur crudes.
• Desalter packages for removing salt from the crude for corrosion prevention.
• Naphtha, jet fuel and diesel hydrotreaters for sulfur removal from the products.
• Catalytic reformers for producing high octane gasoline motor fuels.
• Gasoline stabilizers for reducing the Reid vapor pressure of gasoline.
• Vacuum distillation units for producing paving grade asphalt (bitumen).
• Sulfur plants for sulfur conversion and air emissions reduction that include an amine plant.
• A sulfur plant and a tail gas plant.
• Winterized skids for operation in artic weather.
• Portable laboratory and control buildings with supplies.

Summary

The following data is specifically for the advanced unit which is a 6,000 bpd (300,000 metric tons per year) plant. This model has a turndown capability of 3 to 1, the 100-300 implies that this plant can operate at a rate of 100,000 to 300,000 metric tons per year (2,000 to 6,000 bpd).

The 100-300 topping plant is a modularized, highly portable topping plant capable of processing 6,000 barrels per day of a wide range of crude oil and produces light naphtha, heavy naphtha, kerosene, diesel, gas oil and fuel oil.  The plant can be set up within several weeks after arrival at a completed plant site and can be operational within a month of arrival.

The plant is automatic, can be started up in one hour, hased an automatic system to shut the plant down in the event that a hazardous situation occurs and a “First Out” annunciator to let the operator know the reason for the shutdown.  Automatic controls control the temperature of the heater outlet, tower top vapor temperature, diesel/kerosene/heavy naphtha side draw temperatures, diesel/kerosene/heavy naphtha reboiler temperatures, the level of the tower bottoms, diesel/kerosene/heavy naphtha stripper levels and the naphtha and water levels in the naphtha accumulator.

The standard plant construction material is carbon steel.  Special alloys are specified when warranted for corrosion prevention.

Plant Feed and Products

Flexibility is incorporated in the design of this plant to process a variety of crude oils.  The actual capacity of the plant will depend on the percentages of the fractions of the specific crude processed.  Specifically, the plant is designed to process 6,000 barrels per day of 35° to 41° API crude and the products from the plant are light naphtha, heavy naphtha, kerosene, diesel, gas oil and reduced crude (fuel oil).  The plant can be operated at 33% of its rated capacity.

The ending True Boiling Point (TBP) cut point of the different products can be adjusted  somewhat to maximize one cut over another.  As an example, the heavy naphtha end point can be adjusted to 400 °F (205 °C) to maximize naphtha production while minimizing kerosene production.  Conversely, the heavy naphtha end point can be reduced to 325 °F (163 °C) to minimize naphtha production and maximize kerosene production.

The starting TBP cut point of the diesel depends on the ending TBP cut point of the kerosene and the diesel product specifications.  With the design basis crude, a starting TBP cut point of 300 °F (149 °C) to 400 °F (205 °C) and an ending TBP cut point of 600 °F (315 °C) to 680 °F (360 °C) is used with a minimum flash point of 125 °F (52 °C).

Reduced crude is the bottom of the barrel with a minimum flash point of 150 °F (66 °C) and is normally used as a #6 fuel oil.

The products will be furnished at the edge of the skid at the following pressures and temperatures:

• Naphtha Product: A minimum of 50 feet (15 meters) of head and a maximum temperature of 20 °F (6.7 °C) above ambient temperature, or 100 °F (38 °C), whichever is higher.
  
• Kerosene:  A minimum of 50 feet (15 meters) of head and a maximum temperature of 100 °F (38 °C).
  
• Diesel:  A minimum of 50 feet (15 meters) of head and a maximum temperature of 125 °F (52 °C).
  
• Reduced Crude (#6 Fuel Oil): A minimum of 50 feet (15 meters) of head and a maximum temperature of 250 °F (121 °C).

Codes and Standards

The following prevailing standards of United States engineering design and codes are adhered to in the processing, layout and selection of the various component parts used in the fabrication and assembly of this plant:

• ASME Code Section VIII, Division 1, Pressure Vessels and Heat Exchangers
• ANSI B31.3 Petroleum Refinery Piping
• FM Requirements for Burner Control
• API-RP520, Parts I and II, Design and Installation of Pressure Relieving Systems in Refineries
• API-500 A Classification of Areas for Electrical Equipment in Petroleum Refineries (Class 1, Group D, Division 2) on the process end of the skid.  A firewall separates the process area from the MCC/control room.  A seal is placed in all conduits that pass through the firewall.  The heater is located at least 50 feet from the other process equipment and control room.

All process vessels are designed and fabricated in accordance with the ASME Code, Section VIII, Division 1.  The tower and strippers, with associated trays, are 316 stainless steel.  Fabrication shops for the vessels are tested and certified by ASME, insurance companies and other regulatory agencies to perform fabrication in accordance with the ASME Code, Section VIII, Division 1.  These shops are provided with a certificate having a certificate number and they are audited and re-certified every three years.  Copies of the shop’s certificate are available after a purchase order has been issued for the coded vessels.

The fabrication shops must use certified welders who are tested and certified in accordance with the ASME Code, Section IX.

Pressure gauges are calibrated annually in accordance with a dead weight tester.

Certified mill test reports on materials used on ASME Code vessels are provided and shipped with each vessel for the buyer’s and customs use.

Sufficient surge capacity is provided in all vessels to assure stable control and allow corrective action to be taken in the event of a process upset or equipment failure.  Sufficient elevation is provided for all vessels to assure adequate suction head at low liquid level for pumps.

The heater is a horizontal cabin-type with a convection section.  Certified mill test reports on materials used to build the heater are provided and shipped with the heater for the buyer’s and customs use.  The heater is built in accordance with the following codes:

• Coil:  ASME Section I
• Tubes:  ASTM A-106 Grade B
• Fittings:  ANSI B16.9
• Flanges:  ANSI B16.5
• Burner:  FM Requirements All piping and valves required within the process battery limits are provided, fabricated and installed to the maximum practical extent. 

Piping design is according to ANSI B31.3.  All process piping (2” and smaller) is 316 stainless steel tubing using tube bends, Swagelok fittings and a minimum of welds.  Piping larger than 2” is A-106, Grade B seamless.

Special Services

The plant includes furnishing the following:

• Three (3) sets of job books containing vendor drawings, data, spare parts lists and equipment operating manuals.
  
  
• Three (3) sets of drawings including process flow diagram (PFD), piping and instrumentation diagrams (P&IDs), equipment layout drawings, piping plans, electrical schematics, equipment specifications and data sheets.
  
  
• Three (3) sets of plant operating manuals consisting of the recommended start-up, operating and shutdown procedures.
  
  
• One (1) year supply of manufacturer’s recommended spare parts.
  
  
• Four (4) weeks of a start-up engineer’s time to assist in plant erection and training of buyer’s operators (travel and per diem expenses extra).

Equipment and Services Excluded

The following equipment and services are excluded from a standard plant and will be furnished only on an optional adder basis. 

These extras include:

• All permits and permitting costs i.e. building, environmental, operating, etc.
• Sales tax, use tax, duties, customs fees, or other taxes, if applicable.
• Freight beyond the Port of Houston, Texas (quoted price is FAS Port of Houston).
• Land acquisition.
• Site grading, tank berms and landscaping.
• Facility roads and paving.
• Main office or other buildings.
• Required utilities (such as potable water, fire protection, natural gas, electrical power, telephone, sewer, etc.).
• Concrete foundations for the equipment.
• Unloading and erection of the plant at the site.
• Crude feed and product storage tanks.
• Truck or rail load/unload racks.
• Interconnecting piping (and associated pipe supports) between the plant and the storage tanks.
• Field (off-skid) electrical and controls wiring, etc.
• Travel and living expenses for the start-up engineer.

Tseofirming Technology

Zeoforming is a catalytic-refining process for low-octane gasoline cuts of various origins into unleaded, antiknock gasoline using zeolite-containing catalysts.

Zeoforming is an efficient method of unleaded gasoline production from gas condensate gasoline cut, oil, natural gasoline, oil refinery gases, and broad fraction of light hydrocarbons.This process was developed by scientists at the Technological Design Institute of catalytic and adsorptive processes on zeolites, "Zeosit" of the Siberian Branch of the Academy of Science and the Institute of Catalysis named after Academic G.K. Boreskov. The technology has been tested at different stages during 1990-1997: from pilot to industrial testing.

The traditional method of antiknock gasoline production uses a platinum catalyst in low-capacity installations (mini-plants) within oil and gas condensate refineries. Depending on the mode of operation, a single Zeoforming installation can produce gasoline ranging from brand А-76 to АИ-93. Gasoline output depends on the composition of the feedstock. Operating in the А-76(А-80) mode, gasoline makes up 80-95% of the output, while in mode АИ-93, the gasoline output is 60-85% The quantity of hydrocarbon gas (mainly propane-butane cut) varies within the range of 19-40% depending on the composition of the feedstock and the commercial gasoline brand. As much as 70% of the hydrocarbon gas could be transformed into liquid gas.

Comparison of parameters of reforming and zeoforming processes

 Consumption rate per 1 ton of feed stock

Brief description of the process for producing gasoline from synthetic gas

Intake
Synthetic gas is supplied to the compressor suction from the natural gas conversion block where it mixes with circulation gas. The mixed gas is further squeezed up to an operating pressure point, and then divided into two streams. The major stream is heated in the heat exchanger-recuperator due to the reactor-heated gas, and is supplied to the reactor inlet. The minor stream -- cold bypass -- goes to the reactor's inter-shelf space for thermal regulation in the reactor.

After passing the reactor, the reaction products are consecutively supplied to the heat exchanger-recuperator and the cooler-condenser, to be cooled by the jacket water.

Separation
Separation of gas from the liquid products of the reaction takes place in the high pressure separator. To prevent accumulation of inert-gases (nitrogen, methane and etc.) in the circulation gas, part of it is removed as relief gas. Relief gas is supplied to the combustion network for production of thermal and electric power. After passing through a high pressure separator, the major portion of gas is supplied to the compressor suction.

After leaving the high pressure separator, liquid products are throttled and separated from the dissolved gas in the low pressure separator, and then are divided into water and unstable gasoline cut in the sludge tank. Water from the sludge tank is supplied to the natural gas conversion block, while unstable gasoline is supplied to the stripping tower where light hydrocarbons are separated from the gasoline cut. Commercial gasoline coming from the bottom of the tower is collected in the tank and is supplied to the storage.

Product composition
The gasoline output makes up 65-70% of the mass of supplied natural gas; about 5% of the natural gas hydrocarbon is transformed into light hydrocarbons (С3-С5) that is used for combustion purposes; less than 5% (hydrocarbon) is removed in the form of СО2 and the rest 20-25% of the mass of hydrocarbon are bled-off in the form of untransformed СО, СО2 and uncondensed С1 - С4 hydrocarbons. Relief gases are utilized in the gas turbine power plant (ГТУ) for generation of thermal and electric power.

Olefin content in the gasoline is less than 3%. Benzene content does not exceed 0.6% of the mass.