JP2613836B2 - Exhaust gas denitration method and apparatus for diesel engine generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating exhaust gas from a diesel generator in the presence of a catalyst to remove nitrogen oxides contained therein.

[0002]

2. Description of the Related Art In recent years, with respect to air pollution, due to the growing public opinion, legal regulations have been becoming stricter. In particular, there is a problem with nitrogen oxides in exhaust gas in working machines such as a generator driven by a diesel engine. I'm getting serious.
As a method of treating such exhaust gas to remove nitrogen oxides, a denitration method using a catalytic reaction method using a reducing agent is currently considered to be the most advantageous. Hydrogen fuel is used.

[0003]

However, in the method using ammonia as a reducing agent, ammonia is a dangerous substance. Particularly, in a relatively small-sized portable diesel engine generator, an increase in the amount of added ammonia is dangerous. The situation is large and the application is practically difficult. Further, in the method using a hydrocarbon as a reducing agent, the catalytic reaction is suitably performed within a relatively high temperature range, but the temperature range is narrow, and is particularly used for outdoor work. For portable diesel engine generators, lighting equipment,
Various loads such as welding machines and vibratory hammers are connected.They are rarely operated continuously at the rated load, and are operated under sudden load fluctuations. In addition, it is difficult to stably maintain the temperature in the catalyst reaction layer within an appropriate temperature range, and there has been a problem that the denitration efficiency is very poor.

[0004] In view of the above problems, the present invention provides a low-risk, generally easily available, relatively easy to store and handle diesel fuel, kerosene, propane gas and the like as a reducing agent for a catalytic reaction. Using hydrocarbons, easily follow the load fluctuation of the diesel engine generator, properly maintain the temperature of the exhaust gas introduced into the catalytic reactor, high denitration efficiency, effective use of energy, It is an object of the present invention to provide a catalytic reaction type denitration method and a denitration device which are compact and economical as equipment and can be suitably used in a portable diesel engine generator used as an outdoor power source.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a method for producing exhaust gas from a diesel engine using an electric heater utilizing the output of a generator by the diesel engine and clean exhaust gas from a catalytic reactor. Is heated by a heat exchanger using as a heating medium, a hydrocarbon is mixed with the exhaust gas as a reducing agent, and the mixture is supplied to the catalytic reactor to reduce nitrogen oxides contained by an oxidation / reduction reaction. The amount of power supplied to the electric heater and the amount of power supplied to the heat exchanger are determined by the detected load change amount of the generator by the load detection unit and the detected temperature change amount of the exhaust gas supplied to the catalytic reactor by the temperature detection unit. Exhaust gas denitration method for a diesel engine generator, wherein a supply amount of the clean exhaust gas is controlled and a temperature of the exhaust gas supplied to the catalytic reactor is controlled. A device for reducing nitrogen oxides contained in exhaust gas of a diesel engine by an oxidation / reduction reaction using a hydrocarbon as a reducing agent in the presence of a catalyst, wherein the exhaust gas between the diesel engine and a catalyst reactor is provided. In the gas system, an electric heater using the output of the generator by the diesel engine and a heat exchanger using the clean exhaust gas from the catalytic reactor as a heating medium are arranged,
A hydrocarbon supply device is provided, and a high-temperature side clean exhaust gas pipe is provided which branches from an exhaust pipe on the exhaust side of the catalytic reactor and supplies a clean exhaust gas as a heating medium to the heat exchanger. A flow control valve is provided on each of the pipe and the low-temperature side clean exhaust gas pipe connected to the heat exchanger, and the generator is provided with a load detector for detecting a load of the generator, and a supply of the catalyst reactor is provided. On the air side, a temperature detector for detecting the temperature of the exhaust gas is provided, and a load change amount detected by the load detector and a temperature change amount detected by the temperature detector are input, and a power supply amount to the electric heater is input. And an exhaust gas denitration device for a diesel engine generator provided with a control mechanism for controlling the opening and closing of each of the flow control valves, and an exhaust gas denitration device provided with the electric heater in an exhaust gas conduit of the exhaust gas passage And Further, there is provided an exhaust gas denitration apparatus in which the electric heater is provided in the heat exchanger, and an exhaust gas denitration apparatus in which the electric heater is provided near an intake portion of the diesel engine instead of the exhaust gas passage. It is a suggestion.

[0006]

The exhaust gas generated by the operation of the diesel engine generator is provided with a hydrocarbon as a reducing agent in an exhaust gas passage, and is heated or not heated by an electric heater and supplied to a heat exchanger. It is heated by a heating medium and supplied to the catalytic reactor at a temperature suitable for a catalytic reaction, that is, an oxidation / reduction reaction in the presence of a catalyst. The position of the electric heater in the exhaust gas passage is arbitrary, and its operation does not change depending on the position. Further, the electric heater can be arranged not only in the exhaust gas passage but also in the vicinity of the intake section such as the air cleaner of the engine section. In this case, the combustion condition of the engine changes,
The heated exhaust gas is generated. Exhaust gas supplied to the catalytic reactor is purified by reducing nitrogen oxides contained therein by catalytic reaction with hydrocarbons. The clean exhaust gas is exhausted directly to the atmosphere by an exhaust pipe as it is, or a part or most of the clean exhaust gas is supplied as a heating medium to a heat exchanger via a clean exhaust gas pipe, and the unpurified exhaust gas is discharged. After heating, it is released to the atmosphere.

The temperature detecting means detects the amount of change in the temperature of the exhaust gas on the supply side of the catalytic reactor and notifies the control mechanism. The load detecting means detects the change in the load of the generator and notifies the control mechanism. The mechanism adjusts the power supply to the electric heater in response to these detections, and operates the flow control valve of the exhaust pipe and the flow control valve of the clean exhaust gas pipe on the heat exchanger exhaust side to operate the heat exchanger. The temperature of the exhaust gas supplied to the catalytic reactor is appropriately maintained by controlling the supply amount of the heating medium to the reactor.

When a hydrocarbon is used as the reducing agent, FIG.
As shown in the above, the temperature of the exhaust gas passing through the catalyst layer needs to be at least 300 to 600 ° C., and to obtain a denitration rate of 70% or more, about 400 to 550 ° C., and to obtain a denitration rate of 80% or more. It needs to be about 400-500 ° C. When the exhaust gas temperature is low, such as when the generator is not loaded or lightly loaded, or in an operating environment where the outside air temperature is low, power is supplied to the electric heater immediately by the automatic operation of the control mechanism. Since high-temperature exhaust gas is generated from the engine due to an increase in the load of the generator due to power supply, the temperature of the exhaust gas increases efficiently due to a synergistic effect with the temperature increase due to the direct heating of the electric heater. On the other hand, the automatic operation of the control mechanism immediately closes the flow control valve of the exhaust pipe, opens the flow control valve of the clean exhaust gas pipe, and heats the heat exchanger with the clean exhaust gas from the catalytic reactor. The temperature of the exhaust gas can be rapidly increased by increasing the flow rate of the medium. At the time of the rated load of the generator such that the temperature of the exhaust gas from the engine becomes relatively high, the heating by the electric heater is stopped by the automatic operation of the control mechanism, and only the adjustment of the amount of the heating medium to the heat exchanger is performed. The exhaust gas can be set to an appropriate denitration reaction temperature.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The exhaust gas denitration method and apparatus of the present invention will be described below with reference to the drawings showing embodiments. FIG. 1 is a schematic configuration diagram of an exhaust gas denitration device of the present invention attached to a diesel engine generator, FIG. 2 is a table showing a relationship between a reaction temperature and a denitration rate in the exhaust gas denitration device, and FIG. 4 is a table showing the relationship between the temperature of the exhaust gas and the temperature of the exhaust gas.

In FIG. 1, a diesel engine generator 1 has an engine horsepower of 78 PS and a generator capacity of 60 PS.
The KVA includes a generator unit 2 and an engine unit 3, and exhausts 200 Nm ³ of exhaust gas from the engine unit 3.
An exhaust manifold 4 for extracting exhaust gas from the engine unit 3 has an electric heater 6 formed at an end of an exhaust gas conduit 5.
The exhaust gas conduit 5 is further extended and connected to the heat exchanger 8. A nozzle 9 for injecting diesel fuel as a reducing agent is attached to the exhaust gas conduit 5, and the fuel tank 1 is connected via a hose 10.
Connected to 1. The heat exchanger 8 is adapted to be able to supply the exhaust gas to a catalytic reactor 12 which is directly connected thereto. The catalytic reactor 12 is formed in a cylindrical shape and is filled with a zeolite-based oxidation / reduction catalyst. It is introduced from the inlet 12a to the center, passes through the catalyst layer in the radial direction, and reaches the outlet 12b. The outlet portion 12b is connected to an exhaust tail pipe 15 via an exhaust pipe 13 and a flow control valve 14, and is connected to a heating section of the heat exchanger 8 via a high-temperature side clean exhaust gas pipe 16 branched from the exhaust pipe 13. , The hot clean exhaust gas from the catalytic reactor 12 is discharged from the exhaust pipe 13 to the atmosphere via the flow control valve 14 and the exhaust tail pipe 15, and the hot clean exhaust gas pipe 16 is The heat is returned to the heat exchanger 8 via the heat exchanger 8 to be used as a heating medium. Further, a low-temperature side clean exhaust gas pipe 17 is connected to a clean exhaust gas outlet of the heat exchanger 8, and the low-temperature side clean exhaust gas pipe 17 is connected to the exhaust tail pipe 15 via a flow control valve 18. The low-temperature clean exhaust gas after heat exchange can be discharged to the atmosphere.

In the exhaust gas denitration apparatus of the present invention, the electric heater 6 from the generator section 2 is used in accordance with the load state of the generator section 2 and the temperature state of the exhaust gas supplied to the catalytic reactor 12.
A controller 19 that performs a power supply operation to the heat exchanger and an opening / closing control operation of the flow control valves 14 and 18 that regulate the amount of the heating-side gas to the heat exchanger 8.
Is provided. That is, the generator section 2 is provided with a load detector 20 for detecting a load change amount of the diesel engine generator 1, and a temperature for detecting a temperature change amount of exhaust gas passing through the inlet 12 a of the catalytic reactor 12. Detector 21 is provided,
Controller 19 receives the signal W and T of the load variation and temperature variation, to perform the capacity control of the electric heater 6 via the heater controller 22 on the basis thereof, also the output signal V _a and V By issuing _b , the return amount of the high-temperature clean exhaust gas to the heat exchanger 8 by opening and closing the flow control valves 14 and 18 is controlled. 23 is
It is a monitoring nitrogen oxide and oxygen measuring device that measures the nitrogen oxide concentration and oxygen concentration of the exhaust manifold 4 and the exhaust tail pipe 15 of the engine unit 3 and measures the denitration rate.

In the exhaust gas denitration apparatus described above, the exhaust gas from the engine unit 3 is introduced from the exhaust manifold 4 into the electric heater chamber 7. The exhaust gas temperature of the diesel engine generator 1 at no load or light load is 20
0-250 ° C., and at this temperature, the catalyst reactor 1
Even if introduced into 2, the catalyst is hardly catalyzed. At the time of such no load or light load, the heater control device 22 is controlled by an automatic control signal based on a signal W from the load detector 20 by an arithmetic routine of the controller 19.
Is operated, power is supplied from the generator unit 2, and heating by the electric heater 6 is performed.

The load of the generator unit 2 is the sum of the external actual load using the output of the generator unit 2 and the load of the electric heater 6.
And the exhaust gas temperature rises accordingly. For example, in the diesel engine generator 1, when a vibratory hammer and a lighting device are used as loads, the load factor and the exhaust gas temperature by the temperature detector 21 fluctuate as shown in Table 1 according to the use condition. That is, the exhaust gas temperature fluctuates in accordance with the change in the load factor. For example, the exhaust gas temperature is about 200 to 300 ° C. in the case of a load only of the lighting device, Is increased by about 20%, so that the exhaust gas temperature becomes about 20%.
The temperature rises by 0 ° C to 400 to 500 ° C.

[0014]

[Table 1]

FIG. 3 will be described. A solid line a is an exhaust gas temperature curve when the electric heater 6 is used, and a broken line b is an exhaust gas temperature curve when the electric heater 6 is not used. When the electric heater 6 is not used, the temperature of the exhaust gas from the engine unit 3 is about 250 ° C. at the operating point A, but at the operating point B where the engine output is increased by P = 10%, the exhaust gas temperature is t ₁ = 70 ° C. increase. When the electric heater 6 is used, the engine output is increased by P = 10%, and when this output is supplied to the electric heater 6, the temperature of the exhaust gas from the engine unit 3 is increased by t ₁ = 70 ° C. and the electric power is increased. The exhaust gas temperature rise due to the direct heating of the heater 6 is t ₂ = 110 ° C., which is a total rise of 180 ° C. At the time of rated operation of the engine unit 3, that is, at the time of full load, the exhaust gas temperature near the exhaust manifold is about 500 ° C., so that there is no particular need for heating and power supply operation to the electric heater 6 is not performed. It has become.

Diesel fuel is injected and added as a reducing agent from a fuel tank 11 through a nozzle 9 in the middle of the exhaust gas conduit 5. The exhaust gas containing the diesel fuel is supplied to the catalytic reactor 12 via the heat exchanger 8, and the exhaust gas that has passed through the exhaust gas conduit 5 usually has a temperature depending on the piping and installation environment of the path. Is lowered, and the temperature at the inlet of the heat exchanger 8 becomes about 200 to 300 ° C., so that the heat in the heat exchanger 8 is further heated by the high-temperature clean exhaust gas used as a heating medium, and Will be supplied.

In the catalytic reactor 12, an oxidation / reduction reaction between the nitrogen oxides in the exhaust gas and the diesel fuel is performed in the presence of the catalyst, and the nitrogen oxides are reduced to produce nitrogen, which is harmless. Become This reaction is an exothermic reaction, and the temperature of the clean exhaust gas that has passed through the catalyst layer rises. As shown in FIG. 2, the present inventors have found that the decomposition rate of nitrogen oxides by the catalytic reaction in the catalytic reactor 12 is about 400 to 5
It has been found that the temperature is 50% or more and 70% or more and about 80% or more in a relatively narrow temperature range of about 400 to 500 ° C. At this time, the temperature of the purified exhaust gas that is purified and discharged from the catalytic reactor 12 is The high temperature clean exhaust gas is used as a heating medium while controlling its flow rate according to the temperature of the exhaust gas supplied to the heat exchanger 8 as a fluid to be heated. The degree of heating is controlled so that the exhaust gas supplied to the catalytic reactor 12 is stabilized at the appropriate temperature as described above.

[0018] That is, the temperature variation of the temperature detector 21 detects low, the controller 19 outputs signal V _a in response to the input signals T, the V _b, the flow control valve on the low temperature side clean exhaust gas pipe 17 By increasing the opening of 18 and decreasing the opening of the flow control valve 14 of the exhaust pipe 13, the amount of the heating medium by the high-temperature clean exhaust gas from the heat exchanger 8 is increased, and the temperature of the exhaust gas is raised. I do. Then, the case where the detected temperature variation is high, the controller 19, the output signal V _a and V _b,
The opening degree of the flow control valve 18 is made small, and the opening degree of the flow control valve 14 is made large, so that the amount of the heating medium by the high-temperature clean exhaust gas is reduced and the amount of the high-temperature clean exhaust gas directly discharged to the atmosphere via the exhaust pipe 13 is increased. Then, an operation is performed so as to reduce the temperature rise of the exhaust gas introduced into the catalytic reactor 12.

In the apparatus of the first embodiment described above, the electric heater 6 is disposed substantially in the exhaust gas conduit 5, and the exhaust gas from the engine unit 3 is supplied while the exhaust gas conduit 5 is directly heated. Although it has the advantage of easy mounting and dismounting and easy maintenance and management due to the mode of heating, the catalytic reactor 1
The installation mode of the electric heater as the exhaust gas heating means for supplying the exhaust gas to the fuel cell 2 is not limited to this.

FIG. 4 is a configuration diagram showing an installation state of an electric heater for heating exhaust gas in the apparatus according to the second embodiment of the present invention. Configurations other than those directly related to the electric heater are the same as those in the first embodiment, and are not shown. In the second embodiment, the electric heater 25
Is disposed in the exhaust gas passage of the heat exchange section 26a of the heat exchanger 26, and the electric heater 25 is heated by the operation of the heater control device 27 according to the output signal of the controller (not shown), and the heating by the heat exchange with the heating medium is performed. In addition, the exhaust gas from the exhaust gas conduit 5 is rapidly heated, so that the heat loss is small and the apparatus can be made compact.

FIG. 5 is a diagram showing the installation of electric heaters in the apparatus according to the third embodiment of the present invention. Configurations other than those directly related to the electric heater are the same as those in the first embodiment, and are not shown. Book 3
In the embodiment, an electric heater 30 is disposed at an inlet portion 29a of an air cleaner 29 constituting an intake portion of the engine portion 3 so that the air supplied to the engine portion 3 can be heated by the operation of the heater control device 31. Yes, this gives
The high-temperature exhaust gas can be discharged by changing the combustion conditions of the engine unit 3, and has the advantages of easy attachment and detachment and easy maintenance.

[0022]

As is apparent from the above description, according to the present invention, an electric heater and a heat exchanger are used as a means for heating exhaust gas from a diesel engine generator, and a generator load and a catalyst reactor are supplied. The amount of power supply to the electric heater and the amount of heating medium to the heat exchanger are responsively controlled based on the amount of change in the temperature of the supply exhaust gas, and the electric heater uses the output of the generator to allow the engine to operate using the electric heater. Clean exhaust gas from a catalytic reactor heated efficiently by the heat of catalytic reaction as a heating medium for a heat exchanger by increasing the temperature of the exhaust gas efficiently by the synergistic effect of the increase in the load of the section and the direct heating of the electric heater The following effects suitable for a diesel engine generator for outdoor work can be obtained.

(1) The temperature of the exhaust gas used for the catalytic reaction can be maintained in an appropriate temperature range by easily following the temperature fluctuation of the exhaust gas from the engine due to the load fluctuation of the generator, and the denitration is stably performed. Efficiency can be maintained. (2) As a reducing agent, hydrocarbons that are less dangerous, are easily available, such as engine fuel, and are easy to handle can be used. (3) Electric energy and heat energy can be used efficiently. (4) There are few restrictions on the installation of the electric heater, and it is installed as a relatively compact facility, which is economical.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an exhaust gas denitration apparatus according to a first embodiment of the present invention attached to a diesel engine generator.

FIG. 2 is a table showing a relationship between a reaction temperature and a denitration rate in the exhaust gas denitration apparatus of FIG.

FIG. 3 is a table showing a relationship between an engine output and an exhaust gas temperature in the exhaust gas denitration apparatus of FIG. 1;

FIG. 4 is a partial configuration diagram showing an arrangement state of an electric heater in an exhaust gas denitration apparatus according to a second embodiment of the present invention.

FIG. 5 is a partial configuration diagram showing an arrangement state of an electric heater in an exhaust gas denitration apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diesel engine generator 2 Generator part 3 Engine part 4 Exhaust manifold 5 Exhaust gas conduit 6 Electric heater 7 Electric heater room 8 Heat exchanger 9 Nozzle 10 Hose 11 Fuel tank 12 Catalytic reactor 12a Inlet 12b Exit 13 Exhaust pipe 14 Flow control valve 15 Exhaust tail pipe 16 High temperature clean exhaust gas pipe 17 Low temperature clean exhaust gas pipe 18 Flow control valve 19 Controller 20 Load detector 21 Temperature detector 22 Heater control unit 23 Nitrogen oxide / oxygen meter 25 Electric heater 26 Heat exchanger 26a Heat exchange unit 27 Heater controller 29 Air cleaner 29a Inlet 30 Electric heater 31 Heater controller

Continuation of the front page (72) Inventor Eimamasa Oide 2-8-65 Yoshinodai, Kawagoe-shi, Saitama Pref. Inside the Saitama Factory of Denyo Corporation (56) References JP-A-5-296028 (JP, A) JP-A Sho 61-197740 (JP, A)

Claims (5)

(57) [Claims] An exhaust gas of a diesel engine is heated by an electric heater using an output of a generator of the diesel engine and a heat exchanger using a clean exhaust gas from a catalytic reactor as a heating medium, and the exhaust gas is heated. A method in which a hydrocarbon is mixed with a gas as a reducing agent and supplied to the catalytic reactor to reduce nitrogen oxides contained by an oxidation / reduction reaction. Controlling a power supply amount to the electric heater and a supply amount of the clean exhaust gas to the heat exchanger by a detected temperature change amount of the exhaust gas supplied to the catalyst reactor by the detection unit; Exhaust gas denitration method for a diesel engine generator, wherein a temperature of the exhaust gas supplied to the exhaust gas is controlled. 2. A device for reducing nitrogen oxides contained in exhaust gas of a diesel engine by an oxidation / reduction reaction using a hydrocarbon as a reducing agent in the presence of a catalyst, wherein the device comprises a catalyst and a catalyst reactor. In the exhaust gas passage, an electric heater utilizing the output of the generator by the diesel engine and a heat exchanger using the clean exhaust gas from the catalytic reactor as a heating medium are provided, and a hydrocarbon supply device is provided. A high-temperature side clean exhaust gas pipe that branches from the exhaust pipe on the exhaust side of the catalytic reactor and supplies a clean exhaust gas as a heating medium to the heat exchanger, and the branched exhaust pipe and the heat exchanger A flow control valve is provided for each of the low-temperature side clean exhaust gas pipes to be connected, and a load detector for detecting a load of the generator is provided for the generator, and the exhaust gas is provided for a supply side of the catalytic reactor. A temperature detector for detecting the temperature of the gas is provided; and a load change amount detected by the load detector and a temperature change amount detected by the temperature detector are input, and a power supply amount to the electric heater and the respective flow rate control are provided. An exhaust gas denitration device for a diesel engine generator, comprising a control mechanism for controlling opening and closing of a valve. 3. An exhaust gas denitration apparatus for a diesel engine generator according to claim 2, wherein said electric heater is provided in an exhaust gas conduit of said exhaust gas passage. 4. The exhaust gas denitration system for a diesel engine generator according to claim 2, wherein said electric heater is provided in said heat exchanger. 5. The exhaust gas denitration apparatus for a diesel engine generator according to claim 2, wherein the electric heater is provided near the intake section of the diesel engine instead of the exhaust gas system path.