JPS6221979B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a combustion method and apparatus for combusting hydrocarbon fuel and utilizing its energy, such as an internal combustion engine or a boiler, in which a part of the exhaust gas discharged from the combustor is subjected to a reforming reaction and reused as fuel. The present invention relates to a method and an apparatus for obtaining the heat necessary for the reforming reaction from exhaust gas through the wall of a reforming reactor. The present invention reuses the exhaust gas discharged from a combustor such as an internal combustion engine as part of the fuel, and uses the heat in the exhaust gas to perform a reforming reaction, resulting in low fuel consumption and thermal energy. The purpose of the present invention is to provide a combustion method and apparatus that can make effective use of fuel. That is, the present invention provides a combustion method in which hydrocarbon fuel is combusted and its energy is utilized, in which a reactor filled with a reforming catalyst is disposed in the exhaust gas passage of the combustor, and the exhaust gas discharged from the combustor is Alcohol-based fuel is added to and mixed with a portion of the exhaust gas, and the mixture is fed into the reactor to undergo a reforming reaction to produce a reformed gas containing hydrogen and carbon monoxide. The reforming reaction is carried out by feeding the raw gas together with a hydrocarbon fuel and an oxygen-containing gas into a combustor, burning them, and transmitting the heat in the exhaust gas into the reactor through the reactor wall. A combustion method (first invention) characterized in that: According to the present invention, the water contained in the exhaust gas is reacted with the alcohol-based fuel added and mixed therein to produce a reformed gas containing hydrogen and carbon monoxide. The water becomes hydrogen and carbon monoxide again and is reused as fuel. Therefore, compared to the conventional method in which the entire amount of exhaust gas is released to the outside, the present invention can reduce the amount of hydrocarbon fuel sent to the combustor, resulting in a combustion method with low fuel consumption. can be provided. Furthermore, in the present invention, the heat required for the reforming reaction (endothermic reaction) can be obtained from the exhaust gas through the reactor wall, so the thermal energy in the exhaust gas can be effectively utilized. Further, there is no need to separately provide a heat source for reaction, and the apparatus is simple. Further, according to the present invention, the fuel sent to the combustor is a hydrocarbon fuel and a reformed gas, and since the reformed gas contains hydrogen and carbon monoxide, the fuel concentration in the combustor is It can be easily combusted even if it is dilute. Therefore, the present invention exhibits particularly excellent effects on combustion in internal combustion engines. That is, when the present invention is applied to combustion in an internal combustion engine, in addition to the above-mentioned effects, the fuel fed to the internal combustion engine (corresponding to the combustor described above) contains gases such as hydrogen, carbon monoxide, and methane. Because of its presence, the octane number of the fuel increases, and even if the fuel concentration is low, explosive combustion can easily occur. In addition, since a portion of the exhaust gas is recirculated to the internal combustion engine, the combustion temperature of the internal combustion engine can be lowered, thus reducing the amount of nitrogen oxides produced during combustion, and purifying the exhaust gas. can be done. In the first invention, it is preferable to use alcohol containing methanol as a main component as the alcohol fuel. That is, not only methanol but also methanol containing a small amount of ethyl alcohol, propyl alcohol, etc., such as industrial methanol, is used. A combustor is a device for burning a given fuel, such as a boiler that uses combustion heat itself as energy, or an internal combustion engine that uses the explosive force during combustion as energy. Reformed gas catalysts are used to react water in exhaust gas with alcohol-based fuel to reform it into hydrogen and carbon monoxide. Palladium, rhodium, ruthenium, etc.) are used. In the reactor, hydrogen and carbon monoxide are produced by the above reaction. Therefore, in the reformed gas leaving the reactor, in addition to the above-mentioned hydrogen and carbon monoxide, nitrogen present in the exhaust gas, unreacted water,
Contains carbon dioxide. Further, unburned carbon monoxide and hydrocarbons contained in small amounts in the exhaust gas pass through the reactor as they are. The gas reformed into hydrogen and carbon monoxide is mixed with hydrocarbon fuel, which is sent to the combustor as the original fuel, and sent to the combustor together with oxygen-containing gas, which is the oxidizing agent, for combustion. . Here, the oxygen-containing gas refers to a gas containing oxygen for burning the hydrocarbon fuel such as air, oxygen, or fuel such as hydrogen. It is preferable that a portion of the exhaust gas, that is, the amount of exhaust gas fed into the reactor, be 50% or less of the total amount of exhaust gas discharged from the combustor. This is because if it exceeds 50%, the amount of reformed gas sent to the combustor is too large, making it impossible to operate the combustor smoothly. The ratio of alcohol fuel added to the exhaust gas fed into the reactor is preferably 0.05 to 0.7 times by weight. If the amount is less than 0.05 times by weight, the reaction between the water in the exhaust gas and the alcohol fuel will not be sufficient, and the water in the exhaust gas will not be sufficiently reformed into hydrogen and carbon monoxide. Furthermore, if the weight is 0.7 times the weight or more, even if the alcohol fuel is increased further, the effect of producing reformed gas will be small, and the catalyst temperature in the reactor will vary depending on the type of catalyst, but it will be around 200℃ or more. It is 800℃. Furthermore, when carrying out the method of the present invention, it is necessary to maintain the temperature of the catalyst layer at the high temperature described above.
Since the reformed gas production reaction is an endothermic reaction, some kind of heating means is required to maintain the catalyst layer at such a temperature. In the present invention, the reactor is placed in the exhaust gas passage of the combustor. The apparatus for carrying out the method of the present invention includes:
A combustor such as an internal combustion engine or a boiler, and a mixer connected to the exhaust passage of the combustor, which introduces a part of the exhaust gas discharged from the combustor and mixes alcohol-based fuel therein; a reactor connected to the reactor for converting the mixture produced in the mixer into a reformed gas containing hydrogen and carbon monoxide; The reactor comprises a means for introducing reformed gas together with a hydrocarbon fuel and an oxygen-containing gas into the combustor, and the reactor is configured to contain nickel, cobalt, copper, iron, chromium or platinum for conversion into the reformed gas. The reactor is filled with a reforming catalyst such as a group metal, and is configured such that the mixture passes through the layer of the reforming catalyst and is converted into reformed gas, and the reactor is configured to absorb the exhaust gas of the combustor. A combustion device is conceivable, which is disposed in the passage and allows the heat in the exhaust gas to be transferred into the reactor through the reactor wall to carry out the reforming reaction. According to this device, since the reactor is placed in the exhaust gas passage, heat transfer from the high-temperature exhaust gas to the catalyst layer in the reactor occurs, raising the catalyst layer to the temperature required for the reaction. can be held. A mixer for mixing exhaust gas and alcohol fuel mixes both in one container, as shown in FIG. 2 of the embodiment. In addition to using a single mixer as described above, this mixer can also be used instead by directly mixing the two in a pipe leading to the reactor. In either case, since the exhaust gas is in a high temperature state, when the two are brought into contact, the alcohol-based fuel is vaporized and sent in gaseous form to the reactor. The reactor converts the mixture of exhaust gas and alcohol fuel produced in the mixer into reformed gas containing hydrogen and carbon monoxide, as detailed in FIG. 3 of the embodiments described above and later. It is a device for Note that this reactor is preferably provided near the exhaust gas outlet of the combustor in order to effectively receive heat from the exhaust gas. If the combustor is an internal combustion engine, it is installed in the exhaust manifold or in the exhaust pipe close to it. Examples and examples related to the present invention are shown below. Example Using a copper-iron catalyst as a reforming catalyst, methanol as an alcoholic fuel is added and mixed to a part of the exhaust gas of an automobile internal combustion engine, and this is subjected to a reforming reaction with the above catalyst. The components in the reformed gas were measured. The above-mentioned copper-iron catalyst is made by impregnating and supporting 2% by weight of copper and iron (an atomic ratio of 1:1) on spherical γ-alumina particles for a catalyst carrier having a diameter of about 3 mm. When carrying out the reforming reaction, the above catalyst should be
A 20 mm quartz tube was filled, and a mixed gas of the exhaust gas and methanol vapor was continuously fed into the catalyst layer. Methanol was previously gasified at about 150°C and mixed with exhaust gas. The experiment was carried out by feeding each of the exhaust gases listed in Table 1 for a feed rate of 0.70 mol/hour of methanol (CH ₃ OH). The amount of methanol fed into the catalyst layer was 6 based on LHSV. Also,
Table 1 shows the amount of mixed gas of methanol and exhaust gas fed to the catalyst layer, the ratio of methanol to the exhaust gas, and the center temperature of the catalyst layer. Note that the above "LHSV" refers to the liquid equivalent amount cc of methanol that passes through a catalyst layer of unit volume cc per hour. The results of the experiment are shown in Table 1.

[Table] In Table 1, H ₂ represents hydrogen, CO represents carbon monoxide, CH ₄ represents methane, CO ₂ represents carbon dioxide, H ₂ O represents water, and N ₂ represents nitrogen (the same applies hereinafter). As is known from the results in Table 1, by reacting exhaust gas and methanol, hydrogen and
It can be seen that a reformed gas containing carbon monoxide is obtained. It is also known that the amount of water in the reformed gas is less than the amount of water fed into the reactor. As is clear from the above facts, water in the exhaust gas can be reformed into hydrogen and carbon monoxide by reacting the exhaust gas with methanol. An example in which the present invention is applied to the operation of an internal combustion engine of an automobile will be shown below. As shown in Figures 1 to 3, the device used in this example consists of a gasoline tank 1 containing gasoline as a hydrocarbon fuel, a methanol tank 10 containing methanol, a vaporizer 2, and a combustor. It consists of an internal combustion engine 3, a mixer 4 for mixing exhaust gasoline, and a reforming reactor 5. The methanol tank 10 has pipes 12 and 14.
and is connected to the mixer 4 via the methanol feed pump 13. The carburetor 2 is a well-known carburetor, and is connected to the gasoline tank 1 and an air introduction pipe 22, and the discharge port of the carburetor 2 is connected to the intake manifold 31 of the internal combustion engine 3 via a fuel pipe 23. . As shown in FIG. 2, the mixer 4 is a cylindrical vessel, and has a methanol nozzle 41 and an exhaust gas nozzle 42 on its upper part, and a mixed gas nozzle 44 on its side wall. and 44 are connected to the methanol introduction pipe 14, the exhaust gas pipe 43, and the mixed gas introduction pipe 45, respectively. Note that 46 is a lid. As shown in FIG. 3, the reactor 5 is a cylindrical vessel in which a reforming catalyst 51 is filled. The reforming catalyst 51 is connected to wire meshes 54 and 5 provided in the reactor 5.
Hold between 3 and 3. The reactor 5 has its upper end connected to the mixed gas feed pipe 45 and its lower end connected to the reformed gas feed pipe 52. The other end of the reformed gas feed pipe 52 is connected to the fuel pipe 23.
Connect to. Further, the reactor 5 is sandwiched between the split tubes 33 that can be divided into two in the axial direction in a direction perpendicular to the axial direction of the split tubes 33 (vertical direction in the figure). Further, an exhaust gas sampling pipe 47 is similarly sandwiched and disposed in the split pipe 33, and the pipe 47 is connected to the front exhaust gas pipe 43. The split pipe 33 connects one end to the exhaust manifold 32 of the internal combustion engine 3 and the other end to the exhaust pipe 34 . In FIG. 1, 48 is a check valve, 49 is a valve, and 21 is an air filter. When operating the internal combustion engine 3 using the above device, the mixed gas valve 49 is closed, and as is well known, the internal combustion engine 3 is first started by the starter motor, and gasoline and air are sucked into the carburetor 2. The internal combustion engine 3 is operated by explosive combustion. Exhaust gas from the internal combustion engine 3 is discharged through an exhaust manifold 32, a front split pipe 33, and an exhaust pipe 34. This exhaust gas heats the catalyst 51 in the reactor 5. Next, in order to carry out the combustion method according to the present invention, when the catalyst 51 is heated to the reforming reaction temperature, the mixed gas valve 49 is opened, and a predetermined amount of methanol is pumped in by the methanol feed pump 13. The mixture is continuously fed into the mixer 4 little by little. At the same time, exhaust gas is introduced into the mixer 4 from the exhaust gas pipe 43. In the mixer 4, the methanol that is continuously dropped little by little as described above is vaporized by the exhaust gas at a high temperature of 500 to 800°C, and the two are mixed. This mixed gas is delivered to the reactor 5 through a mixed gas feed pipe 45.
The gas is then reformed under a catalyst and converted into reformed gas containing hydrogen and carbon monoxide. This reformed gas is charged into the fuel pipe 23 through the reformed gas feed pipe 52, and is fed to the internal combustion engine as fuel together with the air and gasoline. The exhaust gas pipe 43, the mixer 4, the mixed gas feed pipe 45, the split pipe 33, the exhaust manifold 32, and the reformed gas feed pipe 52 are covered with a heat insulating material to keep them warm. The operating conditions and results of the above device were as follows. (a) Internal combustion engine used and its driving conditions Piston type, capacity 1588 c.c., rotation speed 1800 rpm,
Intake pressure 800mmHg, excess air ratio 1.0, ignition timing 24
゜BTDC, torque 6.0Kg-m. (b) Reactor conditions The catalyst was the same copper-iron catalyst as shown in the experimental example, the amount of catalyst was 100 ml, and the size of the catalyst layer was 40 mm in diameter.
mm, length 8 cm, catalyst layer center temperature 300 to 400°C, and space velocity of the mixed gas 100,000/hour. (c) Gas composition Table 2 shows the composition of gases in each part of the device, such as exhaust gas and reformed gas. In the same table, "applicable parts" refer to the parts A to G shown in FIG. Note that the value of part C shown in FIG. 1 is the sum of the values of parts A and B, so it is omitted from the table. Air was used as the oxygen-containing gas fed into the vaporizer 2, and is shown as oxygen O ₂ and nitrogen N ₂ in the same table. The exhaust gas and reformed gas contain trace amounts of ethylene, propylene, or nitrogen oxides, but these are not shown in the table because they have little effect on the above reactions and combustion.
The exhaust gas sampled at section A was 20% of the total amount of exhaust gas from the internal combustion engine.

[Table] As can be seen from the above table, smooth combustion and driving can be achieved even under the above conditions. (d) Harmful gas When operated under the above conditions, the harmful components in the exhaust gas were as shown in Table 3. For comparison, in addition to the conventional method, in which the amount of methanol to be sent to the reactor is directly sent to the internal combustion engine without collecting exhaust gas or reforming it into gas, the other methods are the same as above. Almost the same operation was carried out to detect the above-mentioned harmful components. The results are also listed in Table 3.

[Table] In the table, _NO
indicates carbon monoxide. Also, [g/
ps/hr] is internal combustion engine 1 horsepower ps, 1 hour hr
Indicates the weight (g) discharged per unit.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, Fig. 1 is an explanatory diagram of a device for operating an internal combustion engine according to the present invention, Fig. 2 is a partially cutaway front view of a mixer, and Fig. 3 is an arrangement of a reactor. It is a partially cutaway front view showing the state. DESCRIPTION OF SYMBOLS 1... Gasoline tank, 2... Carburizer, 3... Internal combustion engine, 4... Mixer, 5... Reactor, 10... Methanol tank, 43... Exhaust gas pipe, 51... Reforming catalyst, 53, 54... Wire mesh.

Claims (1)

[Claims] 1. A combustion method in which hydrocarbon fuel is combusted and its energy is utilized, in which a reactor filled with a reforming catalyst is disposed in the exhaust gas passage of a combustor,
A reformed gas containing hydrogen and carbon monoxide is produced by adding and mixing alcohol-based fuel to a portion of the exhaust gas discharged from the combustor, and feeding the mixture into the reactor to undergo a reforming reaction. and then feeding the reformed gas together with a hydrocarbon fuel and an oxygen-containing gas into a combustor to burn them and transfer the heat in the exhaust gas into the reactor through the reactor wall. A combustion method characterized by carrying out the above-mentioned reforming reaction. 2 The amount of exhaust gas added to alcohol-based fuel is 50% of the total amount of exhaust gas emitted from the combustor.
Claim 1 characterized in that:
Combustion method described in section. 3 Reforming catalysts include nickel, cobalt, copper, iron,
3. The combustion method according to claim 1 or 2, wherein chromium or a platinum group metal is used. 4 a combustor, connected to the exhaust passage of the combustor,
A mixer that introduces a portion of the exhaust gas discharged from the combustor and mixes alcohol fuel therein; and a mixer that is connected to the mixer and mixes the mixture made by the mixer with hydrogen and carbon monoxide. a reactor for converting the reformed gas into a reformed gas containing a hydrocarbon fuel and an oxygen-containing gas; The reactor is filled with a reforming catalyst such as nickel, cobalt, copper, iron, chromium, or platinum group metal for conversion into the reformed gas, and the layer of this reforming catalyst is and the reactor is arranged in the exhaust gas passage of the combustor to transfer the heat in the exhaust gas into the reactor for the reaction. A combustion device characterized in that the above-mentioned reforming reaction is carried out by transferring heat through the vessel wall. 5. The combustion device according to claim 4, wherein the combustor is an internal combustion engine.