JPH04148014A - Exhaust particulate removing device for diesel engine - Google Patents

Abstract

PURPOSE:To sufficiently burn vaporized fuel stably as well as to eliminate additional equipment with vaporized fuel self-supplied, by fractionating only constituents low in boiling point in fuel for a diesel engine so as to be supplied to an auxiliary fuel feed means, and thereby supplying vaporized fuel to a filter element carrying combustion catalyst. CONSTITUTION:When a diesel engine 1 is operated, exhaust gas 9 containing particulates flows into a filter element 6 through exhaust pipes 3a and 3b. and when the particulates are piled up in the filter element 6 so as to be increased in quantity, the particulates are then burnt with auxiliary fuel 43 injected into the upstream of the filter element 6 so as to be mixed. In this case, auxiliary fuel 43 is supplied from a fractinating unit 28. And liquid fuel 13c is supplied by a liquid fuel pump 29 from a fuel tank 11. Furthermore, carried gas 37 such as air, inert gas and the like is supplied to a header 40 from a carried gas pump 38, and it is shot up out of a nozzle 44 so as to be mixed with fractinated gas 42, so that it is thereby forwarded out of an auxiliary fuel outlet port 41 to an injection port 45 as auxiliary fuel 43.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a diesel engine exhaust gas purification device, and particularly to a particulate removal device suitable for removing particulates from exhaust gas.

[Conventional technology]

Cogeneration is a form of efficient generation and use of energy. Among them, systems that generate electricity with a diesel engine and recover the waste heat for use in air conditioners or heaters, or obtain steam or hot water, are excellent in terms of thermal efficiency and economic efficiency.

However, the exhaust gas of a diesel engine contains fine particles whose main component is carbon, which causes environmental pollution. These particles must be removed from the exhaust gas to prevent them from being released into the atmosphere.

Conventional devices for removing carbon particles include:
A filtration element is installed in the middle of the diesel engine exhaust pipe,
Filters that filter fine particles are known. In this type of device, the filtration element becomes clogged in a relatively short period of time.
As the exhaust pressure increases, it is necessary to appropriately remove the particulates collected on the filtration element.As a means of removing the particulates collected on the filtration element, that is, regenerating the filtration element, as shown in Figure 8, A particulate incineration mechanism consisting of an ignition mechanism or an exhaust gas heating mechanism is usually provided upstream. In the conventional diesel power generation and cogeneration system shown in FIG. This leads to a particulate remover comprising a particulate incineration mechanism 56 and the like.

The purified gas leaving the particulate remover is heat-recovered by an exhaust heat boiler 7 and is disposed of through a chimney 8. Light oil or heavy oil is normally used as fuel for a diesel engine, and is supplied to the diesel engine 1 from a fuel tank 11 by a fuel pump 12. Combustion air is supplied to the diesel engine 1 via the supercharger 4. A cooling system is essential for the diesel engine body, and a heat removal line consisting of a cooling tower 23, a pump 24, a heat exchanger 26, etc., and a hot water production line consisting of a water supply pump 16, a heat exchanger 18, and a hot water tank 22 are attached. be done. A portion of the hot water is supplied to the waste heat boiler 7 and is also used as steam 20. By the way, the incineration mechanism for fine particles collected by the filtration element 6 is shown in Figures 9 to 1.
The first to fifth methods shown in FIG. 3 are known. 9th
In the first example shown in the figure, in the vicinity of the filtration element 6,
Ignition equipment for electric heaters, etc.! ! The second example shown in FIG. 10 has an exhaust gas heater 58 such as an electric heater installed upstream of the particulate removal device. This increases the temperature of the exhaust gas.

This incinerates the fine particles that have accumulated on the filter element. If a combustion catalyst is supported on the filtration element, incineration at lower temperatures can be expected. In the third example shown in FIG. 11, a burner 60 for injecting and burning the same liquid fuel as that supplied to the diesel engine is provided upstream of the filtration element.

In the fourth example shown in FIG. 12, a combustion catalyst is supported on the filtration element 6, and gaseous fuel 63 supplied from a separate line is injected and mixed into the upstream part of the filtration element as auxiliary fuel. be. The gaseous fuel concentration at the time it reaches the filtration element is normal because it has been diluted to a concentration that does not allow combustion in the gas phase, and the entire filtration element can be heated almost uniformly by the catalytic combustion reaction. In the fifth example shown in FIG. 13, gaseous fuel is obtained by reforming and cracking light oil, which is the fuel for a diesel engine. That is, the catalyst layer 6 is placed in the exhaust gas passage 65 that bypasses the filtration element 6.
A modified decomposition bag with 7! 66, and heat the reforming cracker with exhaust gas. The fuel pump 68 pumps up the light oil 64a from the fuel tank 11 of the diesel engine, supplies it to the catalyst layer 67, and causes it to be reformed and decomposed. The generated hydrocarbon gas is supplied from the injection nozzle 62 to the exhaust pipe upstream of the filtration element.

[Problems to be Solved by the Invention] Among the above-mentioned conventional techniques, the direct ignition of accumulated particles by an electric heater or the like in the first example (Fig. 9) is effective when the amount of particles accumulated on the filter element is small. Even if it is ignited at the end, it will not be possible to continue combustion, and if the amount is too large or uneven, it will become locally high temperature.

This causes burnout or destruction of the filtration element, making it unsuitable for larger sizes. In the second example (Figure 10), it is possible to incinerate the particles regardless of the amount of particles, and if the exhaust gas temperature is increased and incineration is performed before a large amount of particles accumulate, it is possible to incinerate the particles as seen in the first example. Such shortcomings can be overcome. However, raising the temperature of the exhaust gas requires a large amount of energy, and especially when an electric heater or the like is used, the overall thermal efficiency decreases, and as with the first example, it is not suitable for increasing the size. The third example (Fig. 11) uses a burner that injects the same liquid fuel as that supplied to the diesel engine and burns it in the gas phase.The decrease in thermal efficiency is small, but the liquid fuel is heavy. Therefore, there are problems such as clogging of the burner nozzle, new generation of unburned particles, and control constraints due to the narrow range of stable combustion. In the fourth example (FIG. 12), it is necessary to provide gaseous fuel supply equipment, which is not required in normal diesel engines. In the fifth example (Figure 13), there is no problem in areas where gaseous fuel supply equipment such as city gas has been installed, but in areas where it is not, the cost of gas supply equipment increases. The process becomes complicated, and problems such as deterioration of the reforming cracking catalyst and coking due to carbon deposition may occur.

An object of the present invention is to provide a particulate removal device that can stably and efficiently incinerate particulates collected in a filtration element by self-supplying auxiliary fuel gas from the liquid fuel of a diesel engine used in the system. It is in.

[Means to solve the problem]

The above object includes a filtration element provided in a casing connected to an exhaust duct and supporting a combustion catalyst, and an auxiliary fuel supply means for supplying auxiliary fuel to incinerate particulates in exhaust gas collected by the filtration element. In the apparatus for removing particulates from diesel engine exhaust, the auxiliary fuel supply means includes a container holding diesel engine fuel oil, a heater provided in a liquid phase portion of the container, and a carrier gas provided in a gas phase portion of the container. Achieved by having a fractionator having an injector, a fuel oil supply means for supplying the diesel engine fuel oil to the fractionator, and a carrier gas supply means for supplying a carrier gas to the fractionator. be done.

The above object includes a filtration element provided in a casing connected to an exhaust duct and carrying a combustion catalyst, and a high-temperature gas supply means for supplying high-temperature gas to incinerate particulates in the exhaust gas collected by the filtration element. In the device for removing particulates from diesel engine exhaust, the high-temperature gas supply means includes a combustor equipped with a combustion catalyst, a container holding diesel engine fuel oil, a heater provided in a liquid phase portion of the container, and a heater provided in a liquid phase portion of the container. A fractionator having a carrier gas injector provided in a gas phase part, piping that communicates the gas phase part of the fractionator with the combustor, and a fuel oil supply means for supplying diesel engine fuel oil to the fractionator. and a carrier gas supply means for supplying carrier gas to the fractionator.

The above object is achieved by providing a pipe that communicates the fractionator with the tank storing the diesel engine fuel oil.

[Effect]

According to the above configuration, diesel engine fuel oil is supplied to the fractionator by the fuel oil supply means, and the fuel oil is heated according to the temperature level of the heat source by the heater provided in the liquid phase part of the fractionator. The low boiling point components inside evaporate and become vaporized fuel. The vaporized fuel is conveyed to the auxiliary fuel supply means by the carrier gas supplied from the carrier gas supply means, and becomes an auxiliary fuel for incinerating particulates in the exhaust gas collected by the filtration element.

Since the auxiliary fuel is a vaporized fuel, it burns stably and well and does not generate new soot and dust, and because it uses only low boiling point components in the fuel oil, it does not condense in the combustion catalyst or casing during startup or shutdown. There is no need for additional care, and there are no problems with burner blockage or conicing.

Since vaporized fuel can be self-sufficient, there is no need to install additional equipment for storing and supplying vaporized fuel.

Since the fuel oil is circulated between the fractionator and the diesel engine fuel oil tank, the low boiling point components in the fractionator will not decrease rapidly.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

In the first embodiment shown in FIG. 1, a diesel engine 1,
Generator 2, exhaust pipes 3a, 3b, supercharger 4°, particulate remover having a filtration element 6 carrying a combustion catalyst, exhaust heat boiler 7, fuel tank 11, fuel pump 12, heat exchanger 26, pump 24 A fractionator 28 is added to a conventional system consisting of a cooling system consisting of a cooling tower 23, etc., a hot water production line consisting of a pump 16° heat exchanger 18, a hot water tank 22, etc. The fractionator 28 is a container that can contain the liquid fuel 13c and the gas 42 fractionated from the liquid fuel.
．． A header 40 having a plurality of nozzles 44 and an overflow pipe 31 are arranged.

Further, an overflow pipe 31 of the fractionator 28 is provided with a liquid fuel supply line from the fuel tank 11 to the fractionator 28 via a liquid fuel pump 29 and a valve 30.
is piped to the fuel tank 11. The heater 34 includes
It branches off at the branch port 46 of the exhaust pipe 3b, passes through the damper 32 and the blower 33, reaches the heater 34, and then returns to the exhaust pipe 3b.
A branch line 35 returning to the branch gas return port 47 is connected. The header 40 includes a carrier gas pump 38 and a valve 3.
At least one auxiliary fuel outlet 41 is arranged in the zero fractionator 28 to which the fuel pump 9 is connected, and is connected to an inlet 45 arranged in the exhaust pipe 3b. The injection port 45 is
Downstream from branch 046.

It is located upstream of the filtration element 6.

This embodiment operates as follows. When the diesel engine 1 is operated, the exhaust gas 9 containing particulates is sent to the exhaust pipes 3a and 3b.
It flows into the filtration element 6 through. When the amount of particulates deposited on the filter element 6 increases, auxiliary fuel 43 is injected and mixed upstream of the filter element 6 and burned on the surface of the filter element by the action of a combustion catalyst, raising the temperature of the entire filter element. , incinerate particulates. Auxiliary fuel 43 is supplied from fractionator 28 . The liquid fuel 13c is supplied from the fuel tank 11 by a liquid fuel pump 29, and the liquid level in the zero fraction distiller 28 is adjusted by the opening degree of the valve 30 and the position of the overflow pipe 31. The heater 34 includes
Exhaust gas 9 is supplied via blower 33, and liquid fuel 13
Heat c.

Liquid fuels such as light oil and heavy oil used in diesel engines are composed of multiple components, and as is clear from the distillation curve example shown in Figure 2, they contain light components that evaporate at relatively low temperatures. ing. The exhaust gas temperature at the turbocharger 4 outlet is 1 Normally 2
50-400'C.

The amount of branched exhaust gas is adjusted by the damper 32, and the fractionator 28
Once the temperature inside the 0-minute distillate 928 is determined,
Evaporation components and evaporation amounts are determined depending on the fuel type. Also,
The evaporated components and the amount of evaporation must also satisfy the capacity of the combustion catalyst supported on the filtration element 6 and the amount of heat required to raise the exhaust gas 9 to a predetermined temperature. A carrier gas 37 such as an inert gas is supplied, ejected from a nozzle 44, mixed with the evaporated fractionated gas 42, and sent as auxiliary fuel 43 from an auxiliary fuel outlet 41 to an injection port 45.

Since the liquid fuel 13c is circulated between the fuel tank 11 and the liquid fuel 13c, the amount of light components does not suddenly decrease and become heavy.In addition, in this embodiment, the liquid fuel 13c is The liquid level is adjusted, which is simple and inexpensive. Since exhaust gas is used as the heat source for heating [I34], there is little decrease in the thermal efficiency of the entire system.

A second embodiment of the present invention is shown in FIG. 3, in which air 14b at the outlet of the supercharger is used as the carrier gas, and is supplied to the header 40 via a valve 39. Since the carrier gas pump can be omitted, the system is simple and inexpensive.

FIG. 4 shows a third embodiment of the invention. The exhaust gas that has passed through the heater 34 is supplied to the header 40 and used as the carrier gas. Since the carrier gas pump and the branch exhaust gas return line can be omitted, the system is not only simple and inexpensive, but also because the temperature of the exhaust gas used as the carrier gas is higher than that of the carrier gas used in the first and second examples. In addition, there is less loss in thermal efficiency.

In the fourth embodiment shown in FIG. 5, the branched exhaust gas 36 that has passed through the heater 34 is returned to the branched gas return port 47 provided downstream of the filtration element 6. In this example, the branched exhaust gas 36 can be supplied to the heater 34 by utilizing the pressure difference between the upstream and downstream sides of the filtration element 6, and the blower can be omitted.

Also, a sensor 49 that detects the state of the filtration element 6
If the evaporative components and amount of evaporation contained in the auxiliary fuel 43 are controlled by adjusting the opening degree of the control damper 48 via the controller 50 based on the signal, particulate incineration becomes more effective. It will be expensive.

The fifth embodiment shown in FIG. 6 is for controlling the liquid level of the liquid fuel 13c in the fractionator 28 with more precision, and a liquid fuel pump 29 and a control valve 54 are installed in the liquid fuel supply line. A level control pump 51 and a control valve 5 are installed in the return line.
A level detector $52 is installed to detect the liquid level. A signal from level detection $52 is sent via controller 53 to control valves 54,55 to control the level of liquid fuel 13c. In this example, since the liquid level is directly controlled, more reliable control can be achieved. Further, there is no restriction on the positional relationship with the fuel tank 11, which greatly increases the degree of freedom in equipment arrangement.

In the sixth embodiment shown in FIG. 7, a catalytic combustor 69 is disposed between the auxiliary fuel outlet 41 of the fractionator 28 and the inlet 45 provided in the exhaust pipe 3b.

The catalytic combustor 69 has a combustion catalyst layer 70 and an igniter 75. The auxiliary fuel 43 conveyed from the fractionator 28 is combusted in the catalytic combustor 69 and becomes high-temperature gas 73, which is then passed through the inlet 45. is injected upstream of the filtration element 6. Since relatively clean high-temperature exhaust gas obtained by pre-fueling auxiliary fuel in the catalytic combustor 69 can be supplied to the filter element, a highly reliable incineration operation can be performed. It is no longer necessary to carry a combustion catalyst in the filtration element 6, and the amount of combustion catalyst can be significantly reduced.6 In addition, in the embodiment, branched exhaust gas is used to heat the liquid fuel 13c. However, it is also possible to use electric heaters, steam, exhaust gas from other systems, etc.

The auxiliary fuel required by the present invention may be any fuel that can be catalytically combusted.The temperature of exhaust gas discharged from a diesel engine is approximately 200 to 600°C, although it varies depending on the size and load of the diesel engine. . If auxiliary fuel is used in all load ranges, a boiling point of 200°C or less is required, but it is difficult to obtain the required amount of 200°C or less distillate from among the fuels used as diesel engine fuels. Considering that auxiliary fuel is injected at about 50% load, a boiling point distillate of about 250 to 300°C is sufficient. In the present invention, the temperature inside the fractionator is controlled by a heater to obtain a distillate with a boiling point of 250 to 300°C from a given fuel oil. It is natural that the boiling point of the auxiliary fuel is set slightly higher than the temperature of the exhaust gas so that it does not condense after being mixed with the exhaust gas.

〔Effect of the invention〕

According to the present invention, by providing a fractionator that fractionates only low boiling point components in diesel engine fuel oil and supplies it to the auxiliary fuel supply means, vaporized fuel can be supplied to the filtration element supporting the combustion catalyst. So.

The vaporized fuel burns stably and well, preventing the generation of new soot and dust, condensation and adhesion to the combustion catalyst and casing during startup and shutdown, and blockage and coking of the burner.

Furthermore, since vaporized fuel can be self-sufficient, it is possible to avoid an increase in the cost of installing additional equipment for storing and supplying vaporized fuel.

Since the fuel oil is circulated between the fractionator and the diesel engine fuel oil tank, the low boiling point components in the fractionator do not decrease rapidly, making it possible to obtain vaporized fuel with stable physical properties. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the configuration of the first embodiment of the present invention, FIG. 2 is a fuel oil distillation curve diagram of the embodiment of the present invention, and FIG. 3 is a diagram showing the configuration of the second embodiment of the present invention. System diagram, FIG. 4 is a system diagram showing the configuration of the third embodiment of the present invention, FIG. 5 is a system diagram showing the configuration of the fourth embodiment of the present invention, and FIG. 6 is the system diagram showing the configuration of the fourth embodiment of the present invention. FIG. 7 is a system diagram showing the configuration of the sixth embodiment of the present invention, FIG. 8 is a system diagram of a conventional diesel power generation/heat cogeneration device, and FIG. 1st from the figure
FIG. 3 is a system diagram of a conventional particulate removal device. 1... Diesel engine, 2... Generator, 3... Exhaust pipe, 6... Filtration element. 7... Exhaust heat boiler, 9... Exhaust gas, 11... Fuel oil tank, 28... Fractionator, 29... Liquid fuel pump, 31... Overflow pipe, 34... Heating vessel,
43... Auxiliary fuel, 44... Nozzle.

Claims (1)

[Claims] 1. A filtration element that is provided in a casing connected to an exhaust duct and supports a combustion catalyst, and an auxiliary fuel supply that supplies auxiliary fuel to incinerate particulates in the exhaust gas collected by the filtration element. In the device for removing particulates in diesel engine exhaust, the auxiliary fuel supply means includes a container holding diesel engine fuel oil, a heater provided in the liquid phase portion of the container, and a gas phase portion of the container. a fractionator having a carrier gas injector provided therein; a fuel oil supply means for supplying the diesel engine fuel oil to the fractionator; and a carrier gas supply means for supplying carrier gas to the fractionator. A diesel engine exhaust particulate removal device comprising: 2. A diesel engine equipped with a filtration element that is installed in a casing connected to an exhaust duct and supports a combustion catalyst, and a high-temperature gas supply means that supplies high-temperature gas to incinerate particulates in the exhaust collected by the filtration element. In the apparatus for removing particulates in engine exhaust, the high-temperature gas supply means includes a combustor equipped with a combustion catalyst, a container holding diesel engine fuel oil, a heater provided in a liquid phase portion of the container, and a gas phase of the container. a fractionator having a carrier gas injector provided in the fractionator, a pipe communicating the gas phase part of the fractionator with the combustor, and a fuel oil supply means for supplying diesel engine fuel oil to the fractionator; A diesel engine exhaust particulate removal device comprising: a carrier gas supply means for supplying a carrier gas to a fractionator; and a fuel supply means having a carrier gas supply means for supplying a carrier gas to a fractionator. 3. Diesel engine exhaust particulates as set forth in claim 1 or 2, characterized in that a pipe is provided that communicates the fractionator with the tank for storing the diesel engine fuel oil. removal device.