JP2010242653A - Multi-fuel combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably operate a multi-fuel combustion engine by maintaining a constant gas flow rate even if gas pressure of a gas supply source is reduced, and to prevent overshoot caused by increased engine speed when the load of a generator is shut down. <P>SOLUTION: A mixer 12 supplying fuel gas into an intake pipe 4 by a Venturi effect is disposed in the middle of the intake pipe 4 of the multi-fuel combustion engine injecting and supplying gas oil or the like into a combustion chamber, supplying the fuel gas to the intake pipe and burning it. A zero governor 8 is disposed between a fuel gas supply source and the mixer 12. After the fuel gas is set to have the same pressure as the atmosphere by the zero governor 8, the fuel gas is introduced into the intake pipe 4 by the Venturi effect of the mixer 12. Further, a solenoid valve 9 is disposed in a fuel gas supply passage and closed when the load current of the generator 2 is shut down, thereby cutting off fuel gas supply. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mixed combustion engine that is driven by supplying a fuel gas such as by-product hydrogen from an intake pipe of a diesel engine that uses light oil or the like as a main fuel and burning the main fuel and the fuel gas.

  In general, in order to increase the input by using a fuel gas such as by-product hydrogen as the fuel of the diesel engine and increase the input amount, a dedicated combustion engine using the fuel gas as the main fuel can be considered. It is difficult to apply to general-purpose diesel engines and existing engines because the engine compression ratio needs to be reduced to a level commensurate with the amount of heat of the fuel gas and a spark plug is added. Further, since the fuel gas is injected at a high pressure, when the pressure of the fuel gas supply source is low, equipment for increasing the pressure to a necessary pressure level is required.

  In addition, as a method of efficiently burning fuel gas with fewer changes in engine specifications, a mixed combustion engine that makes high-pressure injection into the intake side or cylinder using a diesel engine that uses liquid fuel such as light oil as the main fuel Can be considered. However, also in this case, when the pressure of the fuel gas supply source is low, equipment for increasing the pressure to the required pressure level is required. Further, since the fuel gas is supplied at a high pressure, there are problems such as flashback and knocking. It is easy to happen and difficult to control.

  In such a problem, for example, in Patent Document 1, a biogas supply pipe is connected to an intake pipe of a diesel engine via a flow control valve, the opening of the flow control valve is made constant, It has been proposed to control the engine speed to be constant by adjusting the supply amount.

  Further, in Patent Document 2, a low calorie fuel introduction pipe is connected to a supply pipe of a diesel engine via a regulator and a flow rate control valve (A / F valve), and the supply amount of light oil is fixed. It has been proposed to control the amount of low calorie fuel supplied by a control valve so that the engine can be operated while preventing engine misfire and performance deterioration.

  The by-product hydrogen is a coke oven gas refined hydrogen of a steel mill, a salt electrolysis hydrogen of a caustic soda factory, hydrogen generated as a by-product in a refinery or the like.

JP 2002-309997 A JP 2004-278423 A

  In the mixed combustion engine as shown in Patent Document 1, a flow rate adjusting valve is provided between the biogas supply pipe and the intake pipe. In the mixed combustion engine as shown in Patent Document 2, the flow rate is adjusted. A regulator is provided in front of the valve so that the flow rate of the biogas is adjusted.

  However, the regulators and flow rate control valves used in Patent Documents 1 and 2 can maintain the gas pressure and the gas flow rate within a certain range even if there is a slight pressure fluctuation if there is a certain level of gas pressure. However, if the gas pressure of the gas supply source becomes too low, a constant gas pressure and gas flow rate cannot be maintained. Therefore, in the mixed combustion engine as shown in Patent Literatures 1 and 2, there is a problem that stable gas supply cannot be performed when the gas pressure of the gas supply source fluctuates and becomes a predetermined value or less.

  Further, when power is being supplied from a generator to a large load and the load is interrupted due to circumstances on the load side, the engine speed may increase rapidly and overshoot may occur. On the other hand, in a normal diesel engine that uses only light oil as a fuel, the governor can squeeze the light oil instantaneously to prevent the engine speed from overshooting greatly. However, in the mixed combustion engine as shown in Patent Documents 1 and 2, even when a large load is cut off, even if the supply of light oil is restricted by the action of the governor, such measures are not taken on the gas fuel side. As a result, control is not in time, the engine speed greatly overshoots, falls into an overfrequency and overvoltage, and there is a risk of damage to the load equipment in the case of independent operation that does not link with commercial power. There was also.

   In view of such problems, the present invention is unlikely to cause flashback or knocking, and can maintain a constant gas flow rate and stably operate a mixed combustion engine even when the gas pressure of the gas supply source is low. In addition, premixing (a method in which fuel gas is premixed in the intake air and then supplied to the combustion chamber) can be prevented without remodeling the engine and overshooting the engine speed due to load interruption. The purpose is to provide an engine.

  In order to solve the above-mentioned problems, the invention according to claim 1 of the present application is a mixed combustion engine that supplies fuel gas to an intake pipe of a diesel engine and burns it, and is provided in the middle of the intake pipe and is fueled by a venturi effect. A mixer that supplies gas into the intake pipe, a zero governor provided between the fuel gas supply source and the mixer, and a fuel gas supply amount that is provided between the mixer and the zero governor. And a fuel valve for performing the operation.

   The invention according to claim 2 of the present application is the mixed combustion engine according to claim 1, wherein the generator is driven, and a gas supply amount is set in accordance with a load amount of the generator and a type of the fuel gas. The fuel gas supply amount is controlled by adjusting the opening of the fuel valve based on the set load amount of the generator and the set gas supply amount.

   The invention according to claim 3 of the present application is the mixed combustion engine according to claim 1 or 2 that drives a generator, wherein an electromagnetic valve is provided in the fuel gas supply path, and a load amount of the generator is reduced. The fuel gas supply is cut off by closing the solenoid valve when the number of the fuel gas is suddenly decreased.

   The invention according to claim 4 of the present application is the invention according to claim 3, wherein the time measurement is started when the load amount of the generator decreases to the first set value, and then within a predetermined time, The fuel gas supply is cut off when the fuel gas is lowered to a second set value lower than the first set value.

The present invention has the following effects.
That is, in the invention according to claim 1, a mixer for supplying fuel gas into the intake pipe by the venturi effect is provided in the middle of the intake pipe, and a zero governor is provided between the fuel gas supply source and the mixer. As a result, even if the gas pressure of the gas supply source is lowered, the gas pressure to be supplied is kept constant at the same pressure as the atmospheric pressure by the zero governor. By sucking into the intake pipe due to the effect, the fuel gas can be stably supplied.

  In the invention according to claim 2, in the mixed combustion engine according to claim 1, which drives the generator, the gas supply amount is set in accordance with the load amount of the generator and the type of the fuel gas, and the generator The fuel gas supply amount is controlled based on the load amount and the set gas supply amount. As a result, the supply amount of fuel gas can be controlled to the optimum amount according to the type and load amount of fuel gas such as LPG, CNG, biogas, and byproduct hydrogen, and the ratio of fuel gas supply amount can be greatly increased. Can be increased.

  In the invention according to claim 3, in the mixed combustion engine according to claim 1 or 2 for driving the generator, an electromagnetic valve is provided in the fuel gas supply path, and when the load on the generator is suddenly reduced, the electromagnetic The supply of fuel gas was cut off by closing the valve. As a result, it is possible to prevent the engine speed from greatly overshooting when the load is cut off.

  In the invention according to claim 4, in the mixed combustion engine according to claim 3, the time measurement is started when the load amount of the generator is reduced to the first set value, and then within the predetermined time, The fuel gas supply is cut off when the pressure drops to a second set value lower than the set value. As a result, depending on whether or not the speed at which the load current decreases is greater than or equal to a predetermined value, it is determined whether the load is cut off or the load is reduced within a range where the engine speed does not greatly overshoot. You can

It is a system schematic block diagram of the mixed combustion engine which concerns on one Example of this invention. It is a structural diagram of a fuel valve and a mixer. It is a figure which shows the relationship between a load electric current and a fuel valve opening degree. It is a figure for demonstrating control when the load amount of a generator falls rapidly. It is a flowchart which shows the gas supply control in the mixed combustion engine of this invention.

   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, description will be made assuming that by-product hydrogen is used as the fuel gas.

  FIG. 1 is a schematic system configuration diagram of a mixed combustion engine according to an embodiment of the present invention. In FIG. 1, 1 is a diesel engine, 2 is a generator driven by the diesel engine 1, 3 is an air cleaner, 4 is an intake pipe, 5 is an exhaust pipe, 6 is a light oil injection nozzle, 7 is a regulator, 8 is a zero governor, 9 Is a solenoid valve, 10 is a flame extinguishing filter, 11 is a fuel valve, 12 is a mixer, 13 is a pressure sensor, and 14 is a controller for controlling the solenoid valve 9 and the fuel valve 11.

  The diesel engine 1 is operated using light oil injected into the combustion chamber by the light oil injection nozzle 6 and by-product hydrogen mixed into the intake air by the mixer 12, and drives the generator 2. The generator 2 is driven by the diesel engine 1 to output a three-phase alternating current, and supplies power to various loads via the circuit breaker CB.

  By-product hydrogen is introduced into the intake pipe 4 from a gas supply source (not shown) through the regulator 7, zero governor 8, electromagnetic valve 9, flame extinguishing filter 10, fuel valve 11, and mixer 12. The regulator 7 reduces the pressure of by-product hydrogen received from the gas supply source to, for example, about 1 MPa so as to be within a predetermined range, and supplies the pressure to the zero governor 8. The zero governor 8 has a function of maintaining the gas pressure on the secondary side in the vicinity of the atmospheric pressure regardless of the pressure change and flow rate change on the primary side, and absorbs the pressure fluctuation of the gas supply source. It is provided to drop it. As the zero governor 8, a known one manufactured and sold as a general-purpose product can be used.

  The solenoid valve 9 is used to shut off by-product hydrogen under the control of the controller 14 in order to prevent excessive overshoot of the diesel engine 1 when the load of the generator 2 is cut off. The flame extinguishing filter 10 is formed by winding a corrugated metal ribbon in a spiral shape to prevent the propagation of flame by a flame extinguishing element formed so that the cross section becomes a honeycomb shape. It is provided in the hydrogen supply path so that the raw gas is transmitted from the combustion chamber of the diesel engine 1 to prevent the fire from being transferred to the gas supply source. As this flame-extinguishing filter 10, the well-known thing manufactured and sold as a general purpose product can be used.

  As shown in FIG. 2, the fuel valve 11 moves a valve body 15 having a conical tip at a tip by a stepping motor 16 to control the amount of by-product hydrogen introduced. The stepping motor 16 is controlled by the controller 14 and can be driven in multiple steps (for example, 140 steps) step by step from fully closed to fully opened of the valve body 15. In addition, the flow rate of each valve can be adjusted by changing the angle of the tip of the valve body 15. If the angle is made obtuse, the flow rate change for each step becomes small, and if the angle is made acute, the flow rate change for each step. Becomes larger.

  The operating speed of the valve body 15 is, for example, 0.01 sec / step. The slower the speed, the greater the stability of the control, but the slower the response, so this level of operating speed is selected. In addition, as the capacity of the engine output increases, the amount of gas input increases. However, if one fuel valve 11 is insufficient for the required gas input amount, four or other than that as shown in FIG. It is possible to increase in parallel with 2, 3, 5,.

  The mixer 12 supplies by-product hydrogen into the intake pipe 4 by the venturi effect. As shown in FIG. 2, the mixer 12 is connected in the middle of the intake pipe 4 connecting the air cleaner 3 and the diesel engine 1. By-product hydrogen to be sent is introduced into the intake pipe 4. As described above, the present invention employs a method of introducing the fuel gas into the intake pipe 4 using the intake negative pressure, and therefore the present invention can be applied regardless of whether the diesel engine 1 is a non-turbo engine or a turbo engine.

  The venturi unit built in the mixer 12 selects the optimum diameter φ according to the engine output, the type of fuel gas, and the like. At that time, as the diameter φ is reduced, it becomes easier to suck by-product hydrogen. However, if the diameter φ is excessively reduced, the intake negative pressure of the diesel engine 1 increases and the oxygen concentration sent to the combustion chamber decreases. It is limited to a safe range where abnormal vibration does not occur.

  Such a mixer 12 is provided in the middle of the intake pipe 4, and a zero governor 8 is provided between the by-product hydrogen supply source and the mixer 12. Even if the gas pressure of the gas supply source becomes low, the zero governor 8 Since the pressure is kept constant at the same pressure as the atmospheric pressure and the intake pipe 4 is sucked by the venturi effect of the mixer 12, the gas flow rate of by-product hydrogen can be controlled to be constant, and the supply rate of by-product hydrogen is greatly increased. Even if it is increased (for example, about 70%), the engine can be stably operated without causing backfire or knocking.

  The pressure sensor 13 is provided on the downstream side of the air cleaner 3, detects the pressure in the intake pipe 4, and outputs it to the controller 14. When the air cleaner 3 is clogged and its downstream side is lowered to a predetermined value (for example, 6.22 kPa) or less, the controller 14 closes the electromagnetic valve 9 to shut off the byproduct hydrogen, and the byproduct hydrogen is taken in. Avoid excessive introduction into the pipe 4.

  The controller 14 detects the load current with the current transformer CT, and when the load is cut off during operation of the diesel engine 1, the solenoid valve 9 is closed to prevent excessive overshoot of the diesel engine 1 and the by-product is generated. Shut off hydrogen. Further, the fuel valve 11 is controlled by calculating an optimum step according to the load amount of the generator 2. The load amount of the generator 2 should originally be determined by the power output from the generator 2, but in this embodiment, for simplicity, the load amount is detected by detecting the load current. I decided to judge.

  A plurality of data indicating the relationship between the load current and the fuel valve opening as shown in FIG. 3 for each type of fuel gas is registered in the controller 14. In FIG. 3, A, B, C, and D indicate registration data for each type of fuel gas, and such data is registered in association with the capacity of the generator 2. The relationship between the load current and the fuel valve opening is not always linear. Then, the fuel valve opening degree may be finely registered in correspondence with the load current for each interval of the minimum unit, or only the data of the refraction point may be registered, and the intermediate portion thereof may be obtained by calculation. .

  The controller 14 detects the load current by the current transformer CT, obtains the fuel valve opening corresponding to the detected load current based on the registered data, and determines the stepping motor 16 corresponding to the fuel valve opening. The fuel valve 11 is controlled by calculating the step.

  Further, as described above, the controller 14 determines that the generator has become unloaded when the load is cut off during the operation of the diesel engine 1 and the load current rapidly decreases, and the electromagnetic valve 9 To shut off by-product hydrogen. At that time, when the load current of the generator is reduced to the first set value, the clocking is started, and then the generator is set to the second set value lower than the first set value within a predetermined time. Is no load.

FIG. 4 is a diagram for explaining the control when the load amount of the generator is suddenly reduced. When the generator 2 is operating at a load current I _L, when the load current becomes I ₁ is a first set value decreases, it starts clocking. And when it becomes below the I2 which is _2nd setting value within predetermined time (for example, 0.3 second), it determines with the generator having become no load. For example, the _first set value I ₁ may be set to 75% of the rated current, and the second set value I ₂ may be set to 25% of the rated current.

  By doing so, when the load current is reduced at a speed at which excessive overshoot of the diesel engine 1 does not occur, the supply of fuel gas is not cut off, and the diesel engine 1 may overshoot excessively. Only when the load current decreasing speed is equal to or higher than a predetermined value, it can be determined that the load is cut off and the supply of the fuel gas can be cut off.

  Next, the gas supply amount control operation of the controller 14 will be described with reference to the flowchart shown in FIG. First, based on the magnitude of the load current detected by the current transformer CT, it is determined whether or not the generator 2 is in a load operation (step S1). For example, if the load current is 5% or more of the rated current, it is determined that the load is being operated.

  If the load operation is being performed in step S1, it is determined whether or not T seconds (for example, 3 seconds) have elapsed (step S2), and when T seconds have elapsed, the solenoid valve 9 is opened and byproduct hydrogen is removed. Supply (step S3).

  And it is discriminate | determined whether the generator 2 is continuing load operation (step S4), and if load operation is not continued, it will be discriminate | determined whether T second has passed for confirmation (step S5). When T seconds have elapsed, the solenoid valve 9 is closed to stop the supply of by-product hydrogen (step S6).

  On the other hand, if the load operation is continued in step S4, based on the output of the pressure sensor 13, it is determined whether or not the negative pressure in the intake pipe 4 has dropped to a predetermined value (for example, 6.22 kPa) ( In step S7), if the air cleaner 3 is reduced to a predetermined value, the air cleaner 3 may be clogged. Therefore, an inspection of the air cleaner 3 is instructed (step S8), the process proceeds to step S6, the solenoid valve 9 is closed, and byproduct hydrogen is generated. Stop supplying.

If the negative pressure has not decreased to a predetermined value in step S7, it is determined whether the load current has become I ₁ or less based on the output of the current transformer CT (step S9), and has become I ₁ or less. If not, the opening of the fuel valve 11 corresponding to the detected load current is calculated based on the registration data as shown in FIG. 3 (step S10). Then, the calculated opening and the current opening are compared to determine whether or not the calculated value is larger than the current value (step S11). If the calculated value is larger than the current value, the stepping motor 16 is controlled. Thus, the opening degree of the fuel valve 11 is increased to a value corresponding to the calculated value (step S12). If the calculated value is smaller than the current value, the stepping motor 16 is controlled to reduce the opening of the fuel valve 11 to a value corresponding to the calculated value (step S13).

On the other hand, in step S9, When the load current becomes I ₁ below, and the timer is started, t seconds (e.g., 0.3 seconds), it is determined whether or not elapsed (step S14), and after the lapse of t seconds , the load current is determined whether it is I ₂ or less is I ₁ smaller value (step S15), and if not become I ₂ below, the process returns to step S1, when I becomes I ₂ below, Since the load is cut off, the process proceeds to step S6, the solenoid valve 9 is closed, and the supply of byproduct hydrogen is stopped.

  In the mixed combustion engine of the present invention, the supply of fuel gas is controlled in this way.

DESCRIPTION OF SYMBOLS 1 ... Diesel engine 2 ... Generator 3 ... Air cleaner 4 ... Intake pipe 5 ... Exhaust pipe 6 ... Light oil injection nozzle 7 ... Regulator 8 ... Zero governor 9 ... Solenoid valve 10 ... Flame filter 11 ... Fuel valve 12 ... Mixer 13 ... Pressure sensor 14 ... Controller 15 ... Valve body 16 ... Stepping motor

Claims (4)

A mixed combustion engine that supplies fuel gas to the intake pipe of a diesel engine and burns it,
A mixer that is provided in the middle of the intake pipe and supplies fuel gas into the intake pipe by a venturi effect; a zero governor provided between the fuel gas supply source and the mixer; the mixer and the zero governor; And a fuel valve that adjusts the supply amount of fuel gas. The mixed combustion engine according to claim 1, which drives a generator.
The gas supply amount is set according to the load amount of the generator and the type of the fuel gas, and the opening degree of the fuel valve is adjusted based on the load amount of the generator and the set gas supply amount. And controlling the amount of fuel gas supplied. The mixed combustion engine according to claim 1 or 2, which drives a generator,
A mixed combustion engine, wherein an electromagnetic valve is provided in the fuel gas supply path, and the supply of the fuel gas is shut off by closing the electromagnetic valve when the load of the generator is suddenly reduced.   When the load amount of the generator decreases to the first set value, the timing starts, and then when the fuel gas decreases to a second set value lower than the first set value within a predetermined time, the fuel gas The mixed combustion engine according to claim 3, wherein the supply of the engine is cut off.

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