JPH0448938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for improving the combustibility of diesel engine fuel, and more specifically, by dissolving oxygen in advance under pressure in a liquid fuel for a diesel engine and then bringing it into contact with an oxidation catalyst, By partially oxidizing the fuel oil to generate peroxide in the fuel, and burning this in a diesel engine,
The present invention relates to a method for improving combustibility that can reduce the amount of black smoke generated in exhaust gas by improving the ignitability of fuel oil and increasing dissolved oxygen in the fuel oil.

Conventional technology Diesel engines are widely used in trucks, buses, industrial machinery, power generation equipment, ships, etc., and recently their use in passenger cars has also increased, and the demand for light oil or heavy oil fuel used in diesel engines has also increased. are doing. For this reason, in the petroleum refining industry, in order to increase the production of these liquid fuels from limited crude oil, methods of increasing the end point temperature of distillation and increasing the yield, production using heavy oil catalytic cracking equipment, thermal cracking equipment, etc. Studies are underway on the use of cracked oil. For large ships, the use of bunker heavy oil with an increased mixing ratio of heavy oil such as asphalt or residual oil from cracking equipment, or coal tar oil, which is a by-product during coke production, is also being considered. These liquid fuels have a higher carbon/hydrogen (C/H) ratio than straight-run light oil or heavy oil, which increases black smoke in the exhaust gas, and also have a low cetane number, making stable ignition difficult.

In order to improve the ignitability, that is, the cetane number, of diesel engine fuel, nitro compound-based cetane number improvers such as amyl nitrate have been reported, but they require addition in large amounts and are not economical. It is also known that peroxide has the effect of improving the cetane number, but peroxide
It has poor stability and has a strong oxidizing effect, so if it is added to fuel at a refinery and shipped, the peroxide will oxidize and deteriorate the fuel oil during transportation and storage, resulting in sludge. It is difficult to put it into practical use because it causes generation.

As for a system for reforming and supplying fuel during engine operation, Japanese Patent Application Laid-open No. 144816/1984 describes a system that reformes diesel oil under high temperature conditions of 400 to 800°C to produce hydrogen, carbon monoxide, methane, etc. A heat engine has been proposed that uses light oil containing methanol etc. and peroxide and supplies these to the intake air system of the engine. However, this system is not practical because the production of methanol actually reduces the cetane number.

However, the inventors of the present application have developed a method for first burning low-quality fuel with good ignitability, by catalytically partially oxidizing an auxiliary fuel mainly composed of saturated hydrocarbons at a low temperature of about 90 to 220 degrees Celsius to produce peroxide-containing fuel. Japanese Patent Application No. 58-153147 (Japanese Unexamined Patent Publication No. 153147/1983) describes a method of improving the combustibility of the main fuel by converting it into a fuel that has been used in combination with the main fuel and supplying it to a diesel engine.
-45765). However, this method
Two types of fuel are required, and air is introduced into the oxidation catalytic reaction device, and the gas (air) and liquid (auxiliary fuel) must be brought into contact with the solid catalyst to perform an efficient partial oxidation reaction. In addition, there were practical problems because air and auxiliary fuel had to be introduced into the reactor by controlling their respective flow rates while maintaining a certain flow rate ratio, making the equipment and control complex. .

Purpose of the Invention The present invention utilizes the property of peroxide to improve the cetane number, does not cause the problem of oxidative deterioration even during fuel storage, has good ignitability even with low-quality fuel oil, and controls the generation of black smoke. The object of the present invention is to provide a method for improving combustibility, which allows combustion to be carried out in a controlled manner.

Structure of the Invention In other words, the first aspect of the present invention is that when supplying liquid fuel to a diesel engine, an oxygen-containing gas is first dissolved in the liquid fuel under pressure, and then the oxygen-containing gas is brought into contact with an oxidation catalyst to form particulate matter in the fuel. This is a method for improving the combustibility of diesel engine fuel, which comprises generating oxide and then injecting it into an engine combustion chamber and combusting it. The second aspect of the present invention is
A portion of the fuel in which the oxygen-containing gas is dissolved under pressure is made into a liquid fuel containing peroxide by contacting with an oxidation catalyst, and this is mixed with a fuel in which the remaining oxygen-containing gas is dissolved under pressure, This is a method for improving the combustibility of diesel engine fuel, which involves injecting this fuel into an engine combustion chamber and combusting it.

Effects In the first invention of the present application, an oxygen-containing gas is dissolved in liquid fuel in advance and brought into contact with an oxidation catalyst, so that the dissolved oxygen and fuel come into contact with the catalyst in the liquid phase, and the partial oxidation reaction is carried out efficiently. Due to the action of the peroxide produced as a result of this progress, even fuel with a low cetane number can be combusted with good ignitability. Furthermore, during fuel injection, the fuel droplets are re-atomized by the action of the residual dissolved oxygen-containing gas that has not been consumed by partial oxidation, thereby suppressing the generation of black smoke in the exhaust gas. In addition, the second invention improves the ignitability of the fuel and suppresses the generation of black smoke in exhaust gas, as in the first invention, and also makes it possible to combust the fuel containing peroxide and the remaining oxygen-containing gas. When mixing with dissolved fuel, the mixing ratio can be adjusted to freely adjust the amount of peroxide produced and the amount of dissolved oxygen in the fuel supplied to the engine, making it easier to respond to fluctuations in operating conditions and reducing the amount of black in exhaust gas. Smoke generation can be further controlled. Moreover, in these inventions, peroxide is generated during engine operation and is immediately subjected to combustion, so it has no effect on fuel deterioration.

Embodiments The present invention is applied to the process of supplying liquid fuel in the fuel tank of a diesel engine to the combustion chamber of the engine, and the fuel necessary for the engine to operate is processed by the following means. While
It is supplied to the engine and combusted.

The present invention will be explained in more detail below based on FIG. In FIG. 1, liquid fuel 2 stored in a fuel tank 1 is sent to a pressurized container 5 by a pump 3, while air (oxygen-containing gas) 6 pressurized by a compressor 4 is fed into the pressurized container 5. to form a phase of pressurized air. Air is dissolved in the liquid fuel 2 under pressure in the container. Oxygen pressurized dissolved fuel 7 in which air is pressurized and dissolved
is divided into two parts by a three-way valve 16 at a branch part of the pipe 8, and a part thereof is a reactor 13 filled with an oxidation catalyst 14.
is guided through piping 8 to make sufficient contact with the catalyst. Here, partial oxidation is performed using dissolved oxygen as an oxidizing agent to the extent that peroxide is produced. The partially oxidized fuel is then dissolved in the remaining oxygen pressurized dissolved fuel 1
5, is pressurized by a fuel pump 9, and is injected into a combustion chamber 11 from a fuel injection nozzle 10. The dissolved gas in the fuel droplets generated by injection rapidly expands outside the droplets within the combustion chamber 11, and the droplets are re-atomized by this force, improving the efficiency of contact with the engine intake air. In addition, the oxygen released from the droplets is also used as combustion oxygen, which, together with the action of peroxide in the fuel, improves ignitability and suppresses the generation of black smoke. These comprehensive effects enable efficient combustion.

The liquid fuel used in the present invention is light oil or heavy oil, and is used in high-speed diesel engines for vehicles, etc.
It is widely used in medium- to low-speed diesel engines for small to large ships, land-based power generation, etc. In other words, light oil is distillate oil, which has most of its fraction in the boiling point range of 250 to 380°C, which is obtained by straight-run distillation of crude oil at atmospheric pressure, as well as aromatic or unsaturated carbonized oil produced by catalytic cracking or thermal cracking of heavy oil, etc. This includes cracked oil containing multiple hydrogen components, light oil fractions produced as by-products during naphtha cracking, and hydrogenated products of these.

In the present invention, first, an amount of liquid fuel necessary for engine operation is continuously taken out from a fuel tank, and this is brought into contact with pressurized oxygen-containing gas to dissolve oxygen into the fuel under pressure. The oxygen-containing gas includes
Air is preferably used in practice because it may contain components such as nitrogen. In order to dissolve the oxygen-containing gas into the liquid fuel under pressure, known means can be applied, such as introducing the liquid fuel into a pressure-resistant container and bringing the oxygen-containing gas into contact with the container.

The amount of oxygen dissolved in the liquid fuel is partially oxidized as described below to a peroxide value of approximately 300~
The amount of oxygen may be set to the amount necessary to obtain a fuel having 5000 ppm or further to promote re-atomization of droplets during fuel injection.
It should be set to about 300 to 5000c.c. (converted to standard conditions). Therefore, the pressure of the oxygen-containing gas during pressurized dissolution is 3 to 20 Kgf/cm ² (oxygen partial pressure).
(gauge), or when using air, the total pressure should be approximately 15~
Just set it to 80Kgf/cm ² (gauge). By the way
“Petrolenm Refinery” by W.L.Nelson
According to Section 204, Table 5-7 of ``Engineering'' 4th edition (published by McGraw-Hill), at 25℃, the oxygen partial pressure in 1 part of diesel oil is 760, 1560, 3800 mmHg.
Dissolve at 154, 380, and 770 c.c. (standard condition), respectively. These weigh approximately 270, 650, and 1330 respectively
Equivalent to ppm. When air is used as the oxygen-containing gas, the entrained nitrogen is also dissolved, which effectively works to atomize the droplets in the present invention.

Next, all or a portion of the liquid fuel in which oxygen is dissolved under pressure (hereinafter referred to as oxygen pressurized dissolved fuel) is brought into contact with an oxidation catalyst to partially oxidize the fuel using the dissolved oxygen in the fuel as an oxidizing agent. , producing peroxide in the fuel. Here, the total amount of oxygen-pressurized dissolved fuel refers to the amount of fuel required for engine operation, while a portion of the fuel refers to a portion of the total amount, and is practically selected from the range of 10 to 90 wt%. be done.

Partial oxidation in the present invention means oxidation to the extent that peroxide is produced, and is not oxidation accompanied by modification to form carbon monoxide, hydrogen, or methanol. In the present invention, the hydrocarbon RH (R means any of an alkyl group, an aromatic hydrocarbon group, or a naphthenic hydrocarbon group, and H means hydrogen) of the fuel is expressed as ROOH by partial oxidation. It is converted to peroxide and becomes a liquid fuel containing it. The amount of peroxide produced by partial oxidation of liquid fuel is expressed as the weight of oxygen contained in the peroxide in ppm (hereinafter simply expressed as ppm) relative to the weight of the fuel, and this is called the peroxide value. . This value is determined by the ASTM D3703 "Standard Test", which involves adding potassium iodide and titrating the liberated iodine with sodium thiosulfate.
Method for Peroxide Number of Aviation
It can be determined using "Tnrbine Fnels" (standard test method for peroxide number of aviation turbine fuel).
In the present invention, the peroxide value in the fuel is approximately 300~
It is preferable to partially oxidize to 5000 ppm, preferably 500 to 5000 ppm, in order to improve ignitability.

Now, in order to perform a partial oxidation reaction, Ni, Cu, Pt,
A reactor is filled with one or more known oxidation catalysts such as metals such as Pd and Ag or their oxides, and the oxygen-pressurized dissolved fuel is continuously passed through the reactor and brought into contact with the catalyst. . As a result, partial oxidation progresses due to dissolved oxygen in the fuel, and peroxide is formed. The reaction temperature during partial oxidation is approximately
A temperature of about 60 to 150°C is sufficient, and contact can be carried out in a liquid phase. Note that the peroxide value is determined not only by the temperature but also by the amount of dissolved oxygen, the contact time with the catalyst,
It can be adjusted by appropriately selecting the type of catalyst, etc.

The oxygen pressurized dissolved fuel that is brought into contact with the oxidation catalyst includes:
Since the oxygen necessary for peroxide formation is uniformly dissolved, the partial oxidation reaction proceeds efficiently and peroxide is produced in the liquid fuel. Further, in the present invention, since the amount of oxygen supplied can be controlled by the pressure of the oxygen-containing gas, that is, by the amount of oxygen dissolved, the peroxide production reaction can be easily controlled and the oxidation reaction can be prevented from proceeding excessively. To give a concrete example,
Nickel oxide catalyst (average particle size 3 mm) is made by dissolving air in commercially available light oil at a pressure of 15 Kgf/cm ² (gauge) and supporting this fuel on alumina while maintaining the pressurized state.
When oil is passed through a reactor filled with 500 g at a rate of 30 ml per minute and brought into contact at a temperature of 100°C, a partially oxidized fuel with a peroxide value of 700 ppm is obtained. The peroxide value can be easily changed depending on the type of catalyst, contact time, contact temperature, and amount of dissolved oxygen. In general, when peroxide is present in fuel, it causes sludge formation, but in the present invention, it is not added to the fuel in the fuel tank, and the fuel after the partial oxidation reaction is continuously This problem does not occur because the fuel is taken out of the reactor and immediately combusted in the engine combustion chamber.

The peroxide-containing liquid fuel obtained as described above is injected into the combustion chamber of a diesel engine from an injection nozzle of the engine, either as it is or mixed with the remaining oxygen pressurized dissolved fuel that has not been subjected to partial oxidation. be done. Unreacted oxygen or other gases such as nitrogen that do not participate in the oxidation reaction are dissolved in the injected peroxide-containing liquid fuel. As mentioned above, all or part of the oxygen-pressurized dissolved fuel is subjected to partial oxidation, and the partially oxidized peroxide-containing liquid fuel has a significantly improved cetane number, so it has good ignitability. It is. As mentioned above, when a part of the oxygen-pressurized dissolved fuel is partially oxidized,
a partially oxidized fuel containing peroxide;
The remaining oxygen pressurized dissolved fuel is mixed at a ratio of approximately 10:90 to 90:10 (wt%) while maintaining the pressurized state.
This is supplied to the combustion chamber. When selecting this mixing ratio, it is preferable to set conditions such that the peroxide number in the fuel after mixing is 300 ppm or more, preferably 500 to 5000 ppm, in order to improve the cetane number. When the remaining oxygen-dissolved fuel is mixed with the peroxide-containing fuel, the amount of dissolved oxygen in the mixed fuel increases, resulting in the effect of preventing black smoke from occurring in the exhaust gas. That is, this mixed oil is injected into the combustion chamber of a diesel engine as usual and used as fuel, but the fuel in the form of droplets injected into the engine combustion chamber is dissolved in the combustion chamber by dissolved oxygen or accompanying nitrogen, etc. The rapid expansion force of other dissolved gases causes further atomization, the release of dissolved oxygen to the outside of the droplets increases oxygen enrichment, and the presence of peroxide promotes ignition of the diesel fuel and regenerates the droplets. Atomization shortens the fuel time of droplets, thereby suppressing the generation of black smoke.

On the other hand, when partially oxidized fuel is directly used for combustion, all or part of the remaining dissolved oxygen is consumed in peroxide formation.
Although the amount is generally low, when air is dissolved under pressure, it still contains a significant amount of nitrogen, so the fuel droplets injected into the combustion chamber of the engine are free from residual dissolved oxygen or nitrogen. The rapid expansion force of the dissolved nitrogen in the combustion chamber further atomizes the droplets, which, in combination with the peroxide in the fuel, promotes ignition and rapid combustion. When partially oxidized fuel is used as it is or as a mixture, if the peroxide number in the fuel is 500 ppm, the cetane number will improve by about 5. Furthermore, the combustion time t required for a droplet to burn out is proportional to the square of the particle size r of the fuel droplet (t
∝r ² ), re-atomization of fuel droplets with dissolved oxygen or other dissolved gases can significantly shorten the burning-out time t of fuel droplets, thereby greatly reducing the generation of unburned soot (black smoke). decrease to

Effects of the Invention The method of the present invention allows even diesel engine fuel with a low cetane number to be ignited with good ignitability and to be combusted with a reduced amount of black smoke generation, so it is particularly preferably applied to diesel engines that use fuel with a low cetane number. can.

[Brief explanation of the drawing]

FIG. 1 is an example of an embodiment of the present invention, and shows a system in which partially oxidized fuel is mixed with residual oxygen-pressurized dissolved fuel and supplied to an engine for combustion. In the figure, 2 is a liquid fuel, 6 is a pressurized oxygen-containing gas (pressurized air), 7 is an oxygen pressurized dissolved fuel, 13 is a reactor filled with an oxidation catalyst 14, and 15 is the remaining oxygen pressurized gas. 10 is a fuel injection nozzle, 11 is a diesel engine combustion chamber,
12 is a piston of a diesel engine.

Claims (1)

[Claims] 1. When supplying liquid fuel from the fuel tank of a diesel engine to the engine, (a) an oxygen-containing gas is dissolved under pressure in the fuel taken out from the fuel tank, and (b) the oxygen (c) contacting the pressurized dissolved fuel with an oxidation catalyst to partially oxidize the fuel with dissolved oxygen to produce peroxide in the fuel; and (c) injecting the peroxide-containing fuel into the engine combustion chamber. A method for improving the fuel properties of diesel engine fuel, which comprises burning the diesel engine fuel. 2. When supplying liquid fuel from the fuel tank of a diesel engine to the engine, (a) an oxygen-containing gas is dissolved under pressure in the fuel taken out from the fuel tank, and (b) a portion of the oxygen-containing gas is then dissolved under pressure. (c) contacting an oxidation catalyst to partially oxidize the fuel with dissolved oxygen to produce peroxide in the fuel; (c) then a fuel containing peroxide;
A method for improving the combustibility of a diesel engine fuel, which comprises mixing the remaining oxygen pressurized dissolved fuel as described above, and (d) then injecting the mixed fuel into an engine combustion chamber and combusting it.