Tag Archives: diesel fuel

Commercial Grade Diesel Fuel Production

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The units in GlobeCore’s USB line provide for production of high-quality commercial grade diesel fuel from cheap or inexpensive components.  The high-quality commercial grade diesel fuels such as Euro-2,3,4, and 5 can be made from inexpensive components due to the hydrodynamic cavitation technology found in GlobeCore’s advanced equipment.

The following components may be used to produce summer diesel fuel:

  • light stove fuel;
  • old, segregated and contaminated diesel fuel
  • dark stove fuel;
  • used oil; and
  • biodiesel fuel.

Additionally, different additives that increase the cetane number of the final product may also be used when producing diesel fuel with GlobeCore USB units.

The following is the technological process of commercial-grade diesel fuel production. First, original components are purified and then, together with metered additives, are supplied to the hydrodynamic blender to be processed.  As a result, there is commercial-grade diesel fuel that meets customer’s needs.

Diesel fuel, obtainted by using GlobeCore USB equipment, is homogeneous and does not separate if it is stored even for a long periods of time. Cavitation technologies allow for water to be included into the fuel production process.

Diesel fuel, that contains approximately15% of water by volume, is able to eliminate hazardous waste emissions and is very important and useful when working in poorly ventilated production facilities.

How to Increase the Cetane Number of Diesel Fuel?

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Such additives as nitro compounds or synthins are added to diesel fuel to increase its cetane number.  In practical terms, the special equipment in the USB line is used to inject additives and obtain homogenized fuels.  They are considered to be an integral part of the production process when increasing the cetane number by a described method.

The combustion of diesel fuels is affected by the design of the equipment and its operational principles.  The combustion chamber should be designed in such a way that it will benefit the vortex formation (when the air is compressed) that allows for the reduction of fuel heating.   It is desirable to use cast iron pistons, as they have a lower thermal conductivity that reduces the combustion distance (the air and fuel are heated actively).

The fractional composition of fuel is needed while assessing the quality of diesel. This composition may be defined by the flash temperature or in the same way as fuel composition.

Diesel fuel purification: the price of centrifuge

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During centrifuge separation of diesel fuel, a solid particle or a water droplet experiences the centrifugal force directed away from the center of rotation. At the same time, the particles may also experience the buoyancy force in the opposite direction (to the center of rotation). The difference of centrifugal separation from gravity separation is that the acceleration does not originate from gravity forces, but from centrifugal acceleration. In this case, the gravity force is much weaker than centrifugal and can be neglected. Particle movement is also slowed by drag, caused by the liquid medium.

There are two types of systems used for centrifugal force for purification of diesel fuel: stationary and rotary. In the former system, the flow of fuel rotates in a stationary apparatus. In the latter, the fuel rotates together with the rotor of the machine. In scientific literature the former are also named hydrocyclones, and the latter are referred to as centrifuges (centrifuge separators).

The centrifugal force in hydrocyclones is generated by the rotation of the flow of diesel fuel in stationary tank. The latter may have various shapes: conical, cylindrical or cone-cylindrical.

The most common hydrocyclone system is when flow swirling is caused by tangential entry into the system. Such units are used in the United States for polishing of light oil products and liquefied gases in main oil lines. Hydrocyclones ensure removal of particles as small as 20 micron.

Hydrocyclones have no rotating parts, therefore such systems are reliable and do not require regular maintenance. The main drawback is the reduction of efficiency if the diameter of the tank is increased. This dictates the solution of combining several hydrocyclones of small diameter into a single system, which, together with collectors, is a complex structure.

Another drawback of hydrocyclones is a significant hydraulic resistance, caused by a sharp 180o change of flow direction. To reduce this effect, flow straighteners are used to arrange the outflow form the cyclone. However, the use of straighteners complicates the cyclone’s design and can reduce purification efficiency due to the change of hydrodynamics in the flow.

To further reduce the losses, direct flow cyclones may be used. These feature swirl devices. It should be noted that such cyclones are less efficient than the previously mentioned counter-current cyclones. This is due to the fact that fuel flow carries some foreign particles away.

There have been attempts to apply cyclones to remove free water from diesel fuel. Such attempts were not very successful, since the velocity of water droplets is significantly lower than in centrifuge separators, limiting dehydration efficiency.

Complete separation of water from diesel fuel is impossible, but its efficiency can be increased in double stage cyclones.

As was mentioned before, centrifuges are systems in which centrifugal forces are generated by the rotation of the moving part, the rotor. It can be driven mechanically, electrically, hydraulically or pneumatically, or even by the flow of diesel fuel.

There are many centrifuge models today, which can differ significantly, both in terms of design and assembly.

There are thick and thin layer centrifuges. They can also differ in terms of diesel fuel movement, which can be parallel to the rotor generating line, in the cross-section plane, at an angle to the axis, in a helical line, etc.

Thick layer centrifuges are rather simple. The rotor is a hollow cylinder. Diesel fuel may move either along the axis of the cylinder or perpendicularly to it. Such unit are mostly used for coarse purification of diesel fuel from larger particles. Smaller particles may be easily carrier away by the flow, not being able to reach the wall due to large distances between the particles and the rotor.

Thin layer centrifuges offer better purification of diesel fuel from solid particles. Their rotors are divided into separate chambers with radial size much smaller than in thick layer centrifuges. This shortens the trajectory of the particles. Efficiency of purification in such devices is also higher due to less pronounced slip of diesel fuel against the wall of the rotor.

Thin layer centrifuges may be cylindrical, conical, helical and multifillar helical.

Centrifuges with spiral and conical insets separate contamination consecutively in all chambers through which the fuel passes. Flow rate is significant, which means that some particles may be carried away by the flow.

Centrifuges with helical inset take diesel fuel into all chambers simultaneously. Then the fuel moves axially, similar to a centrifuge with cylindrical insets. The advantage of these devices is a simpler rotor manufacture technology and almost no slipping of the liquid.

Diesel fuel is supplied along the whole rotor length in multifillar helical centrifuges. The flow velocity in this case does not exceed limits, therefore there is no slipping of liquid relative to the rotor, while contamination removal is simplified. The drawback is a more complex rotor design compared to the other centrifuge types.

Centrifuges with conical rotor insets are also widely used. The movement of liquid occurs along the generating line of the body. A model with a full conical rotor does not efficiently utilize all of its volume, so conical plate centrifuges have been designed. Unfortunately, contamination may also be carried by diesel fuel.

Centrifuges with conical plates are also referred to as purifiers. They are used for dehydration of diesel fuel. Separation of water from diesel fuel in this case is quite efficient, and separate phases are removed from the rotor separately, This is due to a gravity disk in the rotor. It fixes the position of phase separation boundary and creates a hydraulic lock in its upper part.

Speaking of diesel fuel, which has higher density, removal of water is problematic. The main difficulty is that the shift of phase boundary in the direction of rotor axis. In general, removing water from high density fuel by regular methods is difficult, if at all possible.

Removal of contamination from diesel fuel with centrifuges is realistic with low hydraulic resistance and constant throughput. This is why in general centrifuges are widely accepted in purification and dehydration of diesel fuel.

General advantages of centrifuges in comparison to other diesel fuel purification methods are as follows:

  • constant throughput and hydrodynamic resistance;
  • ability to operate with significant pressure drop;
  • low sensitivity to diesel fuel flow fluctuations;
  • self-cleaning capability.

The drawbacks are as follows:

  • complex design;
  • generally complicated purification process;
  • the need for qualified servicing;
  • the need of external power source;
  • low throughput.

This last disadvantage is probably the most significant, as it makes this type of equipment impractical for processing of large volumes of fuel.

Cheap purification of diesel fuel

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Speaking of diesel fuel, a good place to begin is probably the fact that it is one of the most widespread motor fuels for various vehicles, both land-based (automobiles, tractors, locomotives, tugs) and maritime. Diesel fuel production takes up to 30% of total crude oil produced in the world.

Diesel fuel powers internal combustion engines, sensitive to various contaminants, just as any fuel system. Therefore diesel fuels must comply with certain regulations.

The higher the quality of the fuel, the better the engine operates. Engine’s efficiency is reached due to the anticorrosion properties of diesel fuels. Since these fuels are well purified from contamination which could cause metal corrosion, such contaminants are not a factor. Corrosive activity of fuels is more due to the presence of alkali and mineral acids, water, organic acids and sulfur compounds.

The worldwide environmental deterioration forces many countries to tighten environmental requirements to fuels. Due to the need for reliable and efficient operation of modern vehicles, there are strict requirements to the composition and properties of diesel fuel. Most importantly, these regulations concern the harmful emissions into the environment.

Such emissions include sulfur and ash, as well as polycyclic hydrocarbons. Sulfur was mentioned first for a reason. Sulfur and its compounds are one of the most environmentally hazardous components of diesel fuel.

Publications concerning fuel often use the word sulfur meaning its various compounds: disulfides, sulfides, mercaptan sulfur, thiophane and thiophene.

The hazard of sulfur to internal combustion engines is not only in corrosion, but also the formation of engine sludge. It forms due to combustion of sulfur compounds and can cover the engine with solid and dense film. This is obviously harmful to fuel system. If the need to clean the engine is neglected, the engine fails. Sludge may also contaminate oil. Due to the direct contact with engine parts, the parts wear down, piston rings being the most vulnerable.

In such conditions, the manufacturer of diesel fuel must solve the traditional problem of most industries and productions: how to supply fuel of high quality, compliant with all environmental regulations with minimum costs.

One can find many publications on the web dealing with “cheap diesel polishing”, but not many comprehensively describe methods of quality improvement and polishing of diesel fuel, touching instead on more specific issues. Let us take a broader view of the problem.

Special additives are used for improvement of fuel quality. They are used if the content of sulfur in the fuel is too low. We have spoken of the harmful effects of sulfur, however, if the amount of this substance is insufficient, the fuel’s lubrication properties suffer. This is when additives come into play.

Since the amount of diesel fuel consumed grows annually, the assortment of additives also increases.

The most popular today are the anti-gel, cetane-improving, anti-wear and PPD additives.

Anti-gel additives improve quality of diesel fuel. These additives eliminate crystallization of paraffin in lower temperatures. Without this additives, fuel may become cloudy. This additives serves two purposes: removes water and improves solidification point of fuel. Fuel must be heated before adding anti-gel additives.

The purpose of anti-wear additives is self-explanatory. They are required to improve the fuel’s lubricating properties. They form a protective film on contact with a metal surface.

Cetane number is an indication of the fuel’s combustion ability. Certain additives improve that characteristic. High cetane number improves the fuel’s startability, which is important during cold start of the engine. This type of additives also helps to reduce the amount of harmful emissions in the exhaust.

PPD additives allow summer fuel to be used in winter. The use of PPD also improves the fuel’s lubrication properties, which in many respects influences the lifetime of the fuel system and its components.

There are several chemical and physical methods of sulfur removal.

Sulfuric acid processing involves mixing the fuel with a small amount of 90-93% sulfuric acid. The process runs at normal temperature.

The process results in two substances: purified product and acidic sludge, containing the undesired waste. In general sulfuric acid treatment requires a lot of reagents and is quite cumbersome. Acidic sludge can then be used for production of sulfuric acid.

The drawbacks of the sulfuric acid treatment cause transition to better methods: extraction and hydrotreatment. In future, the acidic treatment may be used for production of white oil, since the large consumption of reagents is not profitable for companies.

Adsorption processing involves bringing the oil product in contact with adsorbents, e.g. silica gels or bleaching clays. They absorb resins and nitric compounds which should be removed from petrochemical products.

Bleaching clay is a natural material with highly pronounced absorption ability. They can decolorize various substances. Until recently, the drawback of this method was incomplete adsorbent regeneration.

Selective polishing methods involve various solvents (nitrobenzene, liquid sulfur dioxide, furfurol, dichorene ethyl ester), which selectively dissolve the harmful substances in an oil product. The main drawback of this method is its inability to restore solvent and its loss. Selective polishing is not widely used for diesel fuel, this method being reserved mostly for oil purification.

Hydrotreatment is used for production of low-sulfur diesel from high-sulfur oil. In the process of hydrotreatment, organic sulfur, oxygen and nitrogen compounds are destroyed. The drawbacks of this method are the high temperature (around 380-420ºC) and pressure (up to 4 MPa), and equipment complexity.

Membrane purification allow to remove sulfides, thiophene, disulfines, mercaptans etc from diesel fuel.

The above are the primary methods of diesel fuel polishing. The selection of a method depends on initial fuel contamination and the required degree of purification, as well as financial considerations. One of the solusions is high quality equipment, proven in the oil product purification market. One such product is GlobeCore’s UVR-450/16. This system can be successfully used for purification of diesel fuel, as well as gas condensate, gasoline, kerosene etc. The UVR-450/16 can also purity industrial, turbine and other types of oil. By purchasing such equipment you become an owner of a highly productive mini-plant, aimed at a wide spectrum of processes in oil product polishing and regeneration.

Fuel purification

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There are quite a few methods of removal of water and solid particles from diesel and motor fuels. The most wide spread methods are settling, centrifuge separation and filtration. Without a doubt, all the methods have both advantages and drawbacks, therefore the research into new methods of fuel purification, chemical and physical, is ongoing. These methods can be divided into one-time and continuous.

The methods of the first group use preliminary treatment of fuel. In the general case, the process is performed by hot water wash or steam purge. The need to use water is dictated by its properties as a surfactant, which can remove most contaminants from the phase boundary between fuel and water. In turn, to completely remove water after the wash, de-emulsifiers are needed. This method does not allow to completely remove contaminants from the processed liquid. Particles smaller than 3 micron mostly remain in the fuel.

This is not the only method. Hydrodynamic method involves passing fuel at 21 – 35 MPa pressure through a special conical valve with reduction of pressure to atmospheric. With the rapid change of velocity and pressure, asphalt and tar are destroyed. The drawback of this method is that nonorganic solids are not destroyed, and the total amount of contaminants in the fuel does not change. However, the size of contaminant particles becomes smaller, which allows to eliminate the risk of rapid clogging of filters, pipelines and nozzles.

Fuel can also be purified by sound waves. In this case, the particles become larger instead of smaller due to acoustic coagulation and can then be filtered out.

Electric separators can remove water from petrochemical fuels. Electric field cases water droplets in the fuel to coagulate, and these droplets can then be separated by gravity or centrifuge.

Physical and chemical methods of one-time water removal from fuel are complicated and cumbersome, even through they are quite efficient. They rely on filtration through adsorbents (charcoal, zeolite, silica gel and alumina gel).

Long-term physical and chemical methods are relatives simpler. They maintain fuel purity for storage and transportation, as well as operation. The method involves injection of small amounts of special additives. Their influence remains constant from the moment of injection to the moment of combustion in the cylinder. Known additive spectrum is quite wide. They limit or prevent corrosion of engine parts, prevent formation of tar, coagulate solid particles etc.

Method selection depends on the specific requirements to fuel.

Inexpensive purification of diesel fuel

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Purification of diesel fuel is a rather important issue today, since poor quality diesel fuel may cause the whole fuel system to fail. Obviously, the desired effect should be produced with the minimum of financial resources. The following is a review of inexpensive diesel fuel purification methods.

Quality of diesel fuel should be observed regularly, and the fuel should be purified in time by removing small solid particles. This allows to prevent potential problems for the fuel system.

In general case, diesel fuel can be purified by physical methods and a combination of physical and chemical processes.

A mesh filter is a partial solution. It can capture particles larger than 80 micron. If the particles are smaller, they can pass through the filter unobstructed, and will still cause contamination of the fuel.

Filtration is an important physical method, because it allows to remove dust, which can enter the fuel tank at the filling station. Presence of dust in the fuel causes insufficient supply to the combustion chamber and reduces engine power. Simple filters are made in the form of a case containing a filtering element. More complex filters can capture water, which allows to improve diesel fuel performance.

However, such filters require increased attention, since they cannot let fuel through when they are saturated with water. Unpurified fuel passes around the barrier, which may cause failure of the fuel system and the engine.

Separation is different from filtration in terms of increased reliability. If the fuel is heavily contaminated, regular filters cannot entirely purify it. In this case separators are used. These systems can remove contaminants from the fuel, and the quality of purification does not depend on the amount of the undesired substances. Much like filters, separators can remove both solid particles and water from the fuel, but the design of such systems is much more complex.

The principle of operation divides separators into chemical and physical systems. They separate water and contaminants and remove them to the bottom of a purifier. To maintain operability of the separators, the bottom must be cleaned of the sediment from time to time.

While choosing the purification method, it should be noted that the purity of the processed diesel fuel may not always comply with the sensitivity of the fuel system.

In this case, proven and efficient equipment is in order. One such plant is GlobeCore’s UVR-450/6. This system removes hydrogen sulfide and unsaturated hydrocarbons, reduces the content of paraffin and sulfur. During processing, the fuel is lightened and stays light. The UVR-450/6 plant is reliable and simple to operate. Beside diesel fuel, it can process heavy fuel oil, gas condensate, and regenerate transformer, turbine and industrial oil.

Diesel fuel purification

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If a vehicle owner notices problems in the fuel system, the source of the problems needs to be found. Often such problems are caused by contaminated diesel fuel. One solution is to study special literature or search the Internet to find quick ways of diesel fuel purification.

Let us generally consider ways to purify fuels, as well as oils. The methods are different, one such difference being the required time. However, the availability of choice is a step forward all in itself!

To purify fuel and oil from hydrocarbons, tar and nitrogen compounds, 96% sulfuric acid solution is used. It is added in the amount of 0.5 – 1% of the product. After that the liquid separates: the top layer of purified product with some residual acid and the bottom layer: a thick black substance (acid sludge). Acid can be neutralized by alkali (mostly by sodium hydroxide).

Besides, alkali can remove acids, hydrogen sulfide, phenols and mercaptan. The substances resulting from treatment with sodium hydroxide, are usually water soluble and can be removed from the fuel with the water solution of alkali.

Adsorbents (bleaching clay or silica gel) are used to remove sulfur compounds, tar and organic acids.

Selective purification is an interesting looking method. This process is based on the ability of some materials to solve contaminants. Some of the solvents are mononitrobenzene, phenol, liquid propane, furfuraldehyde etc. These act differently: some solve the contaminant and are removed, while others solve hydrocarbons and cause precipitation of contaminants. The advantage of the mthod is that after treatment the solvent may be distilled and reused.

To remove high pour point hydrocarbons from oil products (paraffin removal), the product is cooled and then solid crystals of paraffin and ceresine are removed.

Every diesel fuel and oil can be treated with hydrogen at elevated temperature and pressure in the presence of a catalyst. This is called hydrotreatment. It allows thorough removal of sulfur compounds from oil or fuel, due to the fact that hydrogen binds sulfur to form hydrogen sulfide. Specific conditions of the process are such: the product and hydrogen is heated to 400 ºС and enter a special reactor with the pressure of 50 kg per cm2.

Still, probably the simplest method of fuel purification is the centrifuge. It helps to remove water, tar and solids from the fuel.

In practice, it is best to trust proven equipment, tested and tried in the field of oil and diesel fuel purification. Something like the UVR systems, which can lighten diesel fuel and HFO, gas condensate and gasoline. The main advantage of the UVR is its versatility: beside the above mentioned products, these systems handle regeneration of various oils, such as turbine, industrial, transformer etc, equally well.

By purchasing a UVR unit made by GlobeCore, you can process various products with the output in full compliance with the existing norms and regulations.

Diesel fuel: removal of paraffin by electric fields

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Partial removal of paraffin from diesel fuel by direct current fields is quite efficient. First, it allows to improve the low temperature performance of fuel. Second, diesel fuel retains some of the n-paraffin hydrocarbons, which define the cetane number. Third, removal of paraffin increases diesel fuel yield from crude oil in comparison to traditional purification methods. Fourth, the electric purification process is significantly simpler than such methods as hydrodewaxing. The drawback is the requirement of low temperature for the process, which, incidentally, also makes it suitable for cold areas.

Removal of paraffin requires special electric dewaxer machines. Each cycle of operation consists of several operations.

First, diesel fuel premixed with an additive enters the interelectrode space through lower side inlets of the system. The fuel can travel from one interelectrode space to another through gaps. Positively charged electrodes are meshes and do not impede movement of the liquid.

To eliminate overflow when fuel level is exceeded, the fuel is drained through the top connector to a special vessel. The interelectrode space is pre-calculated and must consider the thickness of sediment forming on the electrodes. In practice, the sediment rarely exceeds 10-15 millimeters.
When the electrodes are energized, paraffin sediment forms on both sides of the electrodes. Diesel fuel is then removed from the chamber, maintaining power on the electrodes.

The equipment is built with an incline to outlets to accelerate output of the processed fuel.
After fuel is removed, power is disengaged, then paraffin is removed from the electrodes. The latter operation is carried out by warm liquid. The molten paraffin drains to the bottom of the tank and is removed through lower outlets.

After this, the machine and the bottom of the unit should be cooled down to process temperature. To do so, cold liquid is circulated through the tank.

Kerosene, thickened with silicagel or calcium chloride, serves as both cooling and heating agent. Its dielectric properties are also a factor.

Hydrotreatment of diesel fuel

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Today, the desired properties of diesel fuel is mostly dictated by environmental considerations. The European community pays a lot of attention to environmental issues, making its requirements to chemical composition of diesel fuel ever stricter.

Thus, beginning with January 2005, the Euro-4 regulations, limiting sulfur content in diesel fuel to 50 ppm, came into force. Four years later, Euro-5 regulations were introduced, with 10 ppm max sulfur content in diesel fuel. Polycyclic aromatic hydrocarbon content requirement was reduced to 2%. With time, the regulations will be increased to 95% distillation point of 340-350ºС and the cetane number to 54-58. Fuels compliant with this standard, are made in Sweden, the UK, Finland and Germany.

Sulfur compounds are more difficult to remove from diesel fuel than from benzene, since the former are less reactive. Their rate of decay is significantly lower in transformation from triophen to trimethyldibenzothiophene.

Hydrodewaxing is applied for production of diesel fuel with the required operational parameters. The feedstock for this process is straight-run diesel fractions, which boil out of low sulfur, high sulfur and sulfur crude oil at 180-330ºС, 240-360 ºС and 180-360ºС accordingly.

To ensure low sulfur content in fuel (15 ppm or so), a deep hard hydropurification is required, at 9-10 MPa and 315-400ºС. Hydrogen consumption is high, and volume velocity of petrochemicals along cobalt-molybdenum or aluminum-nickel-molybdenum catalysts is low.

The following are the output parameters of the process:

  • weight yield – up to 97%;
  • hydrocarbon gas – до 0,7%;
  • benzene – до 1,5%;
  • hydrogen sulfide – до 2,5%.

The drawback of the hydrotreatment is its low versatility. GlobeCore manufactures and supplied versatile UVR-450/6 systems, which can lighten not only diesel fuel, but also HFO, benzene, kerosene and gas condensate, regenerate transformer, turbine and industrial oil. The unit does not require constant operator attention, operating in either manual or automatic mode. Human interference is only needed for start, stop and sorbent replacement.

The UVR-450/6 is very energy efficient. When switching from one processed product to another, it is only required to drain the remaining product from the system, replace sorbent and filters. There are no additional complicated operations involved.

A diesel fuel producing fungus found…

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There is nothing surprising about this find, since microscopic organisms, which synthesize certain hydrocarbons, had been found before. The special thing about this fungus is that it makes 55 types of hydrocarbons. It was located inside wood fibers of Eucryphia cordifolia (a tree from northern Patagonia) and was named Gliocladium roseum. According to Dr. Gary Strobel (one of the authors of the research), no one has seen anything like that before. The research was reported by Montana State University.

Biodiesel, diesel, diesel fuel, biofuel producing fungus

The results of the research were published in the Microbiology magazine. Mass-spectrography indicated that the fungus excretions contain octane, 1-octen, heptane and hexadecane, which are all components of diesel fuel. Of course, the amounts are far less than what is required for industrial production. It has been suggested that the fungus uses these substances for “clearing” the adjacent surfaces from competing neighbors. However, the find will not be in vain. Scientists hope to research the genome of the fungus and extract the genes used for hydrocarbon synthesis to create industrially feasible species.