EGR rate dynamic optimization control system in dual-fuel mode

Abstract

The invention discloses an EGR (Exhaust Gas Recirculation) rate dynamic optimization control system in a dual-fuel mode, which belongs to the technical field of marine engines, and comprises a mixing box, an EGR rate dynamic optimization control system and an EGR rate dynamic optimization control system, the air inlet end of the main waste gas box is communicated with an exhaust pipe of the dual-fuel engine through a pipeline, and the exhaust end is communicated with the mixing box through a pipeline; an exhaust manifold communicating with the exhaust pipe; the air inlet ends of the auxiliary waste gas boxes are communicated with the exhaust manifold through pipelines, and the exhaust ends of the auxiliary waste gas boxes are communicated with the mixing box through pipelines; eGR valves are arranged at the gas inlet and outlet ends of the main waste gas box and the auxiliary waste gas box, and conveying equipment is further arranged at the gas inlet and outlet end of the auxiliary waste gas box; the main waste gas box and the auxiliary waste gas box are internally provided with sensor assemblies used for measuring parameters of waste gas in the main waste gas box and the auxiliary waste gas box. According to the device, a cooperative mechanism of recirculation exhaust gas component optimization and EGR rate dynamic correction is adopted, when the DRF of the dual-fuel engine changes drastically or the working condition changes suddenly, the situation that the EGR rate change amplitude is too large is avoided, and the combustion stability is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of marine engines, in particular to an EGR rate dynamic optimization control system in a dual-fuel mode. BACKGROUND

[0002] Dual-fuel engines (such as diesel and natural gas) can reduce fuel consumption by 10%-15% and reduce soot emissions by 30%-40% through the mixed combustion of two fuels, but also face technical challenges such as complex exhaust composition and large working condition fluctuations. Under different fuel replacement rates (DRF), the exhaust gas emitted by the engine has significant differences in parameters such as NOx concentration, HC species, and temperature, which puts higher requirements on the adaptability and control accuracy of the exhaust gas recirculation (EGR) system.

[0003] When a dual-fuel engine switches between diesel mode and natural gas mode (i.e., the fuel replacement rate DRF changes dramatically) or is in a sudden acceleration, cold start, or other working condition mutation scenarios, due to the significant differences in combustion characteristics of different fuels (such as slow natural gas combustion speed, high unburned HC, and dilution sensitivity), the traditional EGR control strategy must significantly adjust the EGR rate (for example, from 25% in diesel mode to below 20% in natural gas mode) to meet the emission requirements in different modes.

[0004] However, the dramatic fluctuations in EGR rate can cause sudden changes in intake dilution, sudden drops in combustion temperature, or lean mixtures, which can easily cause combustion instability, misfire, power lag, and even knocking, severely restricting the smoothness of dual-fuel engine operation and emission consistency.

[0005] In addition, traditional EGR relies only on real-time exhaust gas, whose composition fluctuates dramatically with working conditions, resulting in large differences in actual emission effects under the same EGR rate, making it difficult to achieve precise control.

[0006] Therefore, an EGR rate dynamic optimization control system in a dual-fuel mode is provided to solve the above problems. SUMMARY

[0007] The purpose of the present application is to provide an EGR rate dynamic optimization control system in a dual-fuel mode, which solves the problem of combustion instability caused by passive and significant adjustment of the EGR rate when the fuel replacement rate of the existing dual-fuel engine changes dramatically or the working condition mutates.

[0008] The present application achieves the above-mentioned purpose through the following technical solutions: An EGR rate dynamic optimization control system in a dual-fuel mode, comprising: a mixing tank in communication with an intake pipe of a dual-fuel engine; a main exhaust tank having an intake end in communication with an exhaust pipe of the dual-fuel engine through a pipeline and an exhaust end in communication with the mixing tank through a pipeline; an exhaust manifold, which is communicated with the exhaust pipe; at least two auxiliary exhaust boxes, the intake end of the auxiliary exhaust box is communicated with the exhaust manifold through a pipeline, and the exhaust end is communicated with the mixing box through a pipeline; wherein, the intake and exhaust ends of the main exhaust box and the auxiliary exhaust box are provided with EGR valves, and the intake and exhaust ends of the auxiliary exhaust box are further provided with conveying equipment; the main exhaust box and the auxiliary exhaust box are both provided with a sensor assembly for measuring the exhaust gas parameters in the box, and the auxiliary exhaust box is further provided with a catalytic adsorption module for purifying exhaust gas; the auxiliary exhaust box stores standard exhaust gas, and the main exhaust box and the auxiliary exhaust box independently or cooperatively input the recirculated exhaust gas into the mixing box based on the operating conditions of the dual-fuel engine.

[0009] As a further optimization scheme of the application, the standard exhaust gas is the exhaust gas discharged under the operating state of the dual-fuel engine with load ≥ 50% of rated load, speed fluctuation rate ≤ ± 2%, combustion cycle variation rate COVimep ≤ 5% and coolant temperature ≥ 80℃.

[0010] As a further optimization scheme of the application, the mixing box is provided with a fuel gas input pipe and an air input pipe; and the exhaust pipe is provided with control valves at the intake pipeline connection point of the main exhaust box and downstream of the exhaust manifold connection point.

[0011] As a further optimization scheme of the application, one end of the auxiliary exhaust box is rotatably provided with an exhaust gas input pipe, a driving assembly for driving the rotation of the exhaust gas input pipe is arranged on the side of the exhaust gas input pipe, and a rotary joint is arranged at the end of the exhaust gas input pipe; the other end of the auxiliary exhaust box is fixedly provided with an exhaust gas output pipe; a dynamic catalytic assembly is arranged in the auxiliary exhaust box, which comprises a rotating cylinder fixedly connected coaxially with the exhaust gas input pipe, a catalytic module sleeved on the outer periphery of the rotating cylinder, a retaining frame fixedly arranged on the inner wall of the auxiliary exhaust box and used for positioning the catalytic module, and a fixed cylinder fixedly arranged on the end face of the auxiliary exhaust box and gap-fitted with the other end of the rotating cylinder.

[0012] As a further optimization scheme of the application, a partition is fixedly arranged in the rotating cylinder to separate the rotating cylinder into two independent airflow cavities, a first through hole is uniformly arranged on the circumferential side wall of one of the airflow cavities, and a second through hole is uniformly arranged on the circumferential side wall of the other airflow cavity; the retaining frame comprises a ring body and a plurality of fan-shaped blocks fixedly arranged on the outer periphery of the ring body, the auxiliary exhaust box, the rotating cylinder and the fan-shaped blocks form a plurality of catalytic cavities, and the catalytic modules are embedded one by one in the catalytic cavities; an exhaust gas passage is arranged on the fan-shaped block corresponding to the position of the first through hole, and the first through hole is periodically aligned with the catalytic cavities to directly impact the catalytic modules, or aligned with the exhaust gas passage to laterally impact the catalytic modules.

[0013] As a further optimization scheme of the application, the waste gas passage comprises a main passage extending radially along the sector block, and at least two branch passages symmetrically arranged on both sides of the main passage and having outlet ends respectively communicating with two adjacent catalytic cavities.

[0014] As a further optimization scheme of the application, a plurality of third through holes are formed in the circumferential side wall of the fixed cylinder at positions corresponding to the second through holes; the second through holes are periodically aligned with or misaligned with the third through holes to pulse the newly-inlet waste gas into the inner cavity of the fixed cylinder.

[0015] As a further optimization scheme of the application, a stirring assembly is arranged in the inner cavity of the fixed cylinder, and the stirring assembly comprises a stirring rod fixedly arranged on the partition plate and a plurality of stirring blades arranged on the stirring rod.

[0016] As a further optimization scheme of the application, the sensor assembly is arranged in the inner cavity of the fixed cylinder.

[0017] As a further optimization scheme of the application, the control method of the system comprises the following steps: S1, when the dual-fuel engine operates in a steady state condition, the main waste gas tank operates alone to input the real-time waste gas of the dual-fuel engine into the mixing tank; S2, when the dual-fuel engine operates in a non-steady state condition, the main waste gas tank and at least one auxiliary waste gas tank operate cooperatively or the auxiliary waste gas tank operates alone to input the real-time waste gas of the dual-fuel engine and the stored standard waste gas into the mixing tank, or to input the stored standard waste gas alone into the mixing tank; wherein the steady state condition is that the dual-fuel engine is in an operating state of load ≥ 50% rated load, speed fluctuation rate ≤ ± 2%, combustion cycle variation rate COVimep ≤ 5% and coolant temperature ≥ 80℃, and the non-steady state condition is all conditions except the steady state condition; wherein when the remaining amount of the standard waste gas in any one of the auxiliary waste gas tanks decreases to a set threshold, the EGR valve downstream of the auxiliary waste gas tank is closed, and another auxiliary waste gas tank is enabled to ensure continuous supply of the standard waste gas to the mixing tank.

[0018] The application has the following advantages: 1. The application adopts a cooperative mechanism of recirculated waste gas composition optimization and EGR rate dynamic correction, and when the DRF of the dual-fuel engine changes sharply or the working condition changes suddenly, the EGR rate adjustment range can be controlled within ± 3%, which greatly improves the combustion stability, and through composition adjustment, the actual emission effect is ensured to meet the standard, the standard waste gas with high CO2 and low O2 is introduced in the low-efficiency working condition, which significantly improves the dilution efficiency and heat buffering capacity of EGR, and is suitable for emission and stability optimization of the dual-fuel engine in complex working conditions such as fuel switching and cold start.

[0019] 2、The application adopts at least two auxiliary exhaust gas tanks to ensure that the mixing tank is always supplied with sufficient standard exhaust gas, avoiding the problem of EGR interruption when the single auxiliary exhaust gas tank is replenished.

[0020] 3、The application realizes the uniform distribution of the new exhaust gas among the multiple catalytic cavities through the continuous rotation of the rotating cylinder, which makes the new exhaust gas pass through the alternating mode of forward impact and lateral impact, fully contacts with the catalytic module, realizes high-efficiency purification, and makes the new exhaust gas enter the inner cavity of the fixed cylinder in the form of pulse through the second through hole, which promotes the mixing of the new exhaust gas and the remaining previous standard exhaust gas in the inner cavity, and the synchronous operation of the stirring assembly further promotes the mixing of the new exhaust gas and the previous standard exhaust gas, ensuring the uniformity of the exhaust gas composition. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a flow principle schematic diagram of the application; Figure 2 It is a structure schematic diagram of the auxiliary exhaust gas tank of the application Figure 1 ; Figure 3 It is a structure schematic diagram of the auxiliary exhaust gas tank of the application Figure 2 ; Figure 4 It is a structure schematic diagram of the rotating cylinder of the auxiliary exhaust gas tank of the application; Figure 5 It is a partial structure sectional view of the auxiliary exhaust gas tank of the application; Figure 6 It is a structure schematic diagram of the catalytic module and the holder of the auxiliary exhaust gas tank of the application; Figure 7 It is a structure schematic diagram of the fixed cylinder of the auxiliary exhaust gas tank of the application.

[0022] In the figure: 1, dual-fuel engine; 101, air inlet pipe; 102, exhaust pipe; 103, control valve; 2, main exhaust gas tank; 3, auxiliary exhaust gas tank; 301, exhaust gas input pipe; 302, exhaust gas output pipe; 303, driving assembly; 304, rotating cylinder; 304a, partition; 304b, first through hole; 304c, second through hole; 305, catalytic module; 306, fixed cylinder; 306a, third through hole; 307, stirring assembly; 307a, stirring rod; 307b, stirring blade; 308, holder; 308a, ring body; 308b, sector block; 308c, catalytic cavity; 308d, exhaust gas passage; 308e, main passage; 308f, branch passage; 4, mixing tank; 401, fuel gas input pipe; 402, air input pipe; 5, exhaust manifold; 6, EGR valve; 7, conveying equipment. DETAILED DESCRIPTION

[0023] The application will be further described in detail below with reference to the accompanying drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the application and cannot be understood as limiting the scope of protection of the application. Those skilled in the art can make some non-essential improvements and adjustments to the application according to the above application content.

[0024] Embodiment one In order to solve the problem of combustion instability caused by passive large adjustment of EGR rate when the existing dual-fuel engine has a large change in fuel replacement rate (DRF) or a sudden change in working condition, please refer to Figure 1 The application provides a dual-fuel mode EGR rate dynamic optimization control system, which comprises: A mixing box 4 which is in communication with an air inlet pipe 101 of a dual-fuel engine 1; A main exhaust box 2, the air inlet end of which is in communication with an exhaust pipe 102 of the dual-fuel engine 1 through a pipeline, and the air outlet end of which is in communication with the mixing box 4 through a pipeline; An exhaust manifold 5 which is in communication with the exhaust pipe 102; At least two auxiliary exhaust boxes 3, the air inlet end of each auxiliary exhaust box 3 being in communication with the exhaust manifold 5 through a pipeline, and the air outlet end of each auxiliary exhaust box 3 being in communication with the mixing box 4 through a pipeline; The air inlet and outlet ends of the main exhaust box 2 and the auxiliary exhaust boxes 3 are each provided with an EGR valve 6, and the air inlet and outlet ends of the auxiliary exhaust boxes 3 are each further provided with a conveying device 7; Each of the main exhaust box 2 and the auxiliary exhaust boxes 3 is provided with a sensor assembly for measuring the exhaust gas parameters in the box, the exhaust gas parameters including but not limited to CO2 concentration, O2 concentration, HC content, temperature and pressure, and the auxiliary exhaust boxes 3 are each further provided with a catalytic adsorption module for purifying exhaust gas, the pollutants including but not limited to NOx and HC; The auxiliary exhaust boxes 3 store standard exhaust gas, the standard exhaust gas being exhaust gas discharged under the operating conditions of the dual-fuel engine 1 that the load is greater than or equal to 50% of the rated load, the speed fluctuation rate is less than or equal to ±2%, the combustion cycle variation rate COVimep is less than or equal to 5%, and the coolant temperature is greater than or equal to 80℃, and the main exhaust box 2 and the auxiliary exhaust boxes 3 independently or cooperatively input the recirculated exhaust gas into the mixing box 4 based on the operating conditions of the dual-fuel engine 1.

[0025] The mixing box 4 is provided with a fuel gas input pipe 401 and an air input pipe 402, and the mixing box 4 is provided with a corresponding turbulence structure to ensure that the real-time exhaust gas, the standard exhaust gas, the air and the fuel gas are uniformly mixed, and local concentration is avoided to be too high to cause unstable combustion; and the exhaust pipe 102 is provided with a control valve 103 downstream of the air inlet pipeline connection point of the main exhaust box 2 and the connection point of the exhaust manifold 5.

[0026] The control method of the system comprises the following steps: S1, when the dual-fuel engine 1 is running in a steady state condition, the composition of the exhaust gas is monitored in real time by the sensor assembly in the main exhaust gas tank 2, including: CO2 concentration, O2 concentration, HC (hydrocarbon) content, temperature and pressure, when the exhaust gas meets the preset standard exhaust gas standard (such as CO2≥10%, O2≤5%, HC≤200ppm), at this time only rely on a single main exhaust gas tank 2 to supply the mixed tank 4 with recirculated exhaust gas, the intake end and the exhaust end EGR valve 6 of each auxiliary exhaust gas tank 3 are in the closed state and do not participate in exhaust gas recirculation, wherein the steady state condition is that the dual-fuel engine 1 is in a running state with load≥50% rated load, speed fluctuation rate≤±2%, combustion cycle variation rate COVimep≤5% and coolant temperature≥80℃; S2, when the dual-fuel engine 1 is running in a non-steady state condition (such as idle, cold start, low load, fuel switching, sudden acceleration, etc.), the main exhaust gas tank 2 continues to input real-time exhaust gas to the mixed tank 4, at the same time, the exhaust end EGR valve 6 and the conveying device 7 of at least one auxiliary exhaust gas tank 3 that has stored standard exhaust gas are opened, and the standard exhaust gas is conveyed to the mixed tank 4 as needed, mixed with the real-time exhaust gas, diluting the oxygen concentration in the intake air, forming recirculated exhaust gas with controllable composition and stable thermodynamic performance, reducing the combustion temperature to inhibit the generation of NOx, or the standard exhaust gas is conveyed to the mixed tank 4 alone, wherein the non-steady state condition is all conditions other than the steady state condition; Further, the ratio of real-time exhaust gas to standard exhaust gas is dynamically adjusted based on the real-time condition (speed, load, air-fuel ratio, fuel type) of the engine 1 and the target effective EGR rate, by adjusting the proportion of standard exhaust gas, the dilution capacity and heat capacity of the mixed exhaust gas are optimized, NOx generation is inhibited and combustion stability is maintained; S3, the mixed tank 4 receives real-time exhaust gas from the main exhaust gas tank 2 and standard exhaust gas from the auxiliary exhaust gas tank 3, and introduces fuel gas through the fuel gas input pipe 401 and combustion air through the air input pipe 402, after the various gases are fully mixed in the mixed tank 4, they finally re-enter the combustion chamber of the dual-fuel engine 1 through the intake pipe 101, completing the cycle.

[0027] When the remaining amount of standard exhaust gas in any one auxiliary exhaust gas tank 3 falls below a set threshold (such as 15%), the control system will automatically perform the following operations: Close the downstream EGR valve 6 of the auxiliary exhaust gas tank 3, stop supplying gas to the mixing tank 4, enable another auxiliary exhaust gas tank 3, and continue to provide standard exhaust gas to the mixing tank 4 to ensure that the mixing tank 4 is always supplied with sufficient standard exhaust gas; for the auxiliary exhaust gas tank 3 that has been closed, the composition of the exhaust gas is monitored in real time by the sensor assembly in the main exhaust gas tank 2, and when it is detected that the exhaust gas meets the preset standard exhaust gas standard, the control system opens the upstream EGR valve 6 of the closed auxiliary exhaust gas tank 3 and inputs real-time standard exhaust gas into it through the exhaust manifold 5 for replenishment. The new exhaust gas is mixed with the remaining previous standard exhaust gas to form new standard exhaust gas, ready for the next use.

[0028] Traditional EGR control often needs to make a large adjustment to the EGR rate (such as from 25% to 20% or lower) when switching between dual-fuel modes (such as diesel mode and natural gas mode) to cope with the difference in NOx and unburned HC emission characteristics. Large fluctuations in EGR rate can easily cause sudden changes in intake dilution, leading to combustion phase shift, misfire or power response lag. The present scheme introduces high-inert standard exhaust gas as a regulating medium, and only needs to make a small adjustment to the EGR rate (such as from 25% to 23%) between diesel mode (DRF=0%) and natural gas mode (DRF=100%), avoiding combustion instability caused by dramatic changes in flow. By optimizing the composition to adapt to different DRF requirements, in diesel mode, the high CO2 characteristics (12%-15%) of real-time exhaust gas itself can be used to achieve efficient NOx suppression with a small amount of standard exhaust gas. In natural gas mode, although the EGR rate only decreases slightly, by significantly increasing the proportion of standard exhaust gas (which has been treated by catalytic adsorption, HC<150ppm), the active carbon and hydrogen content in the recirculated exhaust gas is significantly reduced, unburned HC generation is inhibited, and the specific heat of the mixture is increased to prevent the combustion temperature from being too high.

[0029] Example Two On the basis of Example One, in order to solve the problem of unstable exhaust gas quality and insufficient exhaust gas composition uniformity of the standard exhaust gas in the EGR system, as shown in Figure 2-Figure 6 One end of the auxiliary exhaust gas tank 3 is rotatably provided with an exhaust gas input pipe 301, a driving assembly 303 for driving the rotation of the exhaust gas input pipe 301 is arranged on the side of the exhaust gas input pipe 301, and a rotary joint is arranged at the end of the exhaust gas input pipe 301. The other end of the auxiliary exhaust gas tank 3 is fixedly provided with an exhaust gas output pipe 302. A dynamic catalytic assembly is arranged in the auxiliary exhaust gas tank 3, which includes a rotating cylinder 304 fixedly connected with the exhaust gas input pipe 301, a catalytic module 305 sleeved on the outer periphery of the rotating cylinder 304, a retaining frame 308 fixedly arranged on the inner wall of the auxiliary exhaust gas tank 3 and used for positioning the catalytic module 305, and a fixed cylinder 306 fixedly arranged on the end face of the auxiliary exhaust gas tank 3 and in gap cooperation with the other end of the rotating cylinder 304.

[0030] A partition 304a is fixedly arranged in the rotating cylinder 304 to divide the rotating cylinder 304 into two independent air flow cavities, the circumferential side wall of one of the air flow cavities is uniformly provided with first through holes 304b, and the circumferential side wall of the other air flow cavity is uniformly provided with second through holes 304c; the retainer 308 comprises a ring body 308a and a plurality of fan-shaped blocks 308b fixedly arranged on the outer periphery of the ring body 308a, the vice exhaust gas tank 3, the rotating cylinder 304 and the fan-shaped blocks 308b enclose a plurality of catalytic cavities 308c, and the catalytic modules 305 are correspondingly embedded in the catalytic cavities 308c; the fan-shaped blocks 308b are provided with exhaust gas passages 308d at positions corresponding to the first through holes 304b, the first through holes 304b are periodically aligned with the catalytic cavities 308c to directly impact the catalytic modules 305, or are aligned with the exhaust gas passages 308d to laterally impact the catalytic modules 305, and the catalytic modules 305 are porous medium catalytic modules, which are selected based on specific dual-fuel types.

[0031] The exhaust gas passages 308d comprise a main passage 308e extending radially along the fan-shaped blocks 308b and at least two branch passages 308f, the branch passages 308f are symmetrically arranged on both sides of the main passage 308e and the outlet ends thereof are respectively communicated with two adjacent catalytic cavities 308c, so that the lateral impact air flow can simultaneously act on two adjacent catalytic modules 305.

[0032] As shown in Figure 7 , a plurality of third through holes 306a are provided on the circumferential side wall of the fixed cylinder 306 at positions corresponding to the second through holes 304c; the second through holes 304c are periodically aligned with or misaligned with the third through holes 306a to pulse the newly-incoming exhaust gas into the inner cavity of the fixed cylinder 306 and mix with the remaining previous standard exhaust gas in the inner cavity to obtain new standard exhaust gas. When the second through holes 304c are aligned with the third through holes 306a, the newly-incoming exhaust gas enters the inner cavity of the fixed cylinder 306 in the form of pulses, and when the two are misaligned, the exhaust gas flow is blocked. This periodic alignment and misalignment mechanism enables the newly-incoming exhaust gas to enter the fixed cylinder 306 in the form of pulses and mix with the remaining previous standard exhaust gas in the inner cavity, thereby promoting the uniformization of the exhaust gas.

[0033] As shown in Figure 4 , the inner cavity of the fixed cylinder 306 is provided with a stirring assembly 307, and the stirring assembly 307 comprises a stirring rod 307a fixedly arranged on the partition 304a and a plurality of stirring blades 307b arranged on the stirring rod 307a. The stirring blades 307b rotate under the driving of the stirring rod 307a, further promoting the mixing of the newly-incoming exhaust gas and the previous standard exhaust gas, and ensuring the uniformity of the composition of the exhaust gas.

[0034] A sensor assembly is arranged in the inner cavity of the fixed cylinder 306, and the sensor assembly further comprises a sensor for measuring the remaining amount of standard exhaust gas.

[0035] The specific working process of the auxiliary exhaust gas tank 3 supplementing the new incoming exhaust gas is as follows: the driving assembly 303 drives the exhaust gas input pipe 301 to rotate at a low speed, and the rotating cylinder 304 fixed coaxially with the exhaust gas input pipe 301 rotates synchronously; the upstream EGR valve 6 of the auxiliary exhaust gas tank 3 is opened, and the downstream EGR valve 6 is closed, preparing to receive the new incoming exhaust gas; after the new incoming exhaust gas is divided by the exhaust manifold 5, it enters the inside of the rotating cylinder 304 through the rotating joint at the end of the exhaust gas input pipe 301; the continuous rotation of the rotating cylinder 304 makes the new incoming exhaust gas fully contact with the catalytic module 305 in the alternating mode of forward impact and lateral impact, realizing high-efficiency purification of pollutants such as NOx and HC, so as to ensure that the recirculated exhaust gas entering the combustion chamber has the excellent characteristics of low pollutant content and high inert components, which not only effectively inhibits the re-generation of NOx in the combustion process, but also reduces the emission of unburned hydrocarbons, and the new incoming exhaust gas treated by catalysis moves axially along the auxiliary exhaust gas tank 3 to the second through hole 304c, is injected into the inner cavity of the fixed cylinder 306, and is uniformly mixed with the previous standard exhaust gas, obtaining new standard exhaust gas. x The specific working process of the auxiliary exhaust gas tank 3 supplementing the new incoming exhaust gas is as follows: the driving assembly 303 drives the exhaust gas input pipe 301 to rotate at a low speed, and the rotating cylinder 304 fixed coaxially with the exhaust gas input pipe 301 rotates synchronously; the upstream EGR valve 6 of the auxiliary exhaust gas tank 3 is opened, and the downstream EGR valve 6 is closed, preparing to receive the new incoming exhaust gas; after the new incoming exhaust gas is divided by the exhaust manifold 5, it enters the inside of the rotating cylinder 304 through the rotating joint at the end of the exhaust gas input pipe 301; the continuous rotation of the rotating cylinder 304 makes the new incoming exhaust gas fully contact with the catalytic module 305 in the alternating mode of forward impact and lateral impact, realizing high-efficiency purification of pollutants such as NOx and HC, so as to ensure that the recirculated exhaust gas entering the combustion chamber has the excellent characteristics of low pollutant content and high inert components, which not only effectively inhibits the re-generation of NOx in the combustion process, but also reduces the emission of unburned hydrocarbons, and the new incoming exhaust gas treated by catalysis moves axially along the auxiliary exhaust gas tank 3 to the second through hole 304c, is injected into the inner cavity of the fixed cylinder 306, and is uniformly mixed with the previous standard exhaust gas, obtaining new standard exhaust gas.

[0036] The above-described embodiments only express several embodiments of the present application, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application. It should be noted that, for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the protection scope of the present application.

Claims

1. A dynamic optimization control system for EGR rate in dual fuel mode, characterized in that: include: a mixing box (4) communicating with an intake pipe (101) of the dual-fuel engine (1); A main exhaust gas box (2), the air inlet end of which is connected to the exhaust pipe (102) of the dual-fuel engine (1) through a pipeline, and the exhaust end of which is connected to the mixing box (4) through a pipeline; an exhaust manifold (5) communicating with the exhaust pipe (102); At least two auxiliary exhaust gas boxes (3), wherein the air inlet end of the auxiliary exhaust gas box (3) is connected to the exhaust manifold (5) through a pipe, and the exhaust end of the auxiliary exhaust gas box (3) is connected to the mixing box (4) through a pipe; The main exhaust gas box (2) and the auxiliary exhaust gas box (3) are both provided with EGR valves (6) at their inlet and outlet ends, and the auxiliary exhaust gas box (3) is also provided with a conveying device (7). The main exhaust gas box (2) and the auxiliary exhaust gas box (3) are both provided with sensor components for measuring exhaust gas parameters therein, and the auxiliary exhaust gas box (3) is also provided with a catalytic adsorption module for purifying exhaust gas; The auxiliary exhaust gas box (3) stores exhaust gas that meets the standards, and the main exhaust gas box (2) and the auxiliary exhaust gas box (3) input recirculated exhaust gas into the mixing box (4) independently or in coordination based on the operating conditions of the dual-fuel engine (1).

2. The EGR rate dynamic optimization control system in dual fuel mode according to claim 1, characterized in that: The exhaust gas meeting the standards is the exhaust gas discharged from the dual-fuel engine (1) when the engine is in an operating state with a load of ≥50% of the rated load, a speed fluctuation rate of ≤±2%, a combustion cycle variation rate COVimep ≤5% and a coolant temperature of ≥80°C.

3. The EGR rate dynamic optimization control system in dual fuel mode according to claim 1, characterized in that: The mixing box (4) is provided with a fuel gas input pipe (401) and an air input pipe (402); The exhaust pipe (102) is provided with a control valve (103) at both the air intake pipe access point of the main exhaust box (2) and the exhaust manifold (5) access point downstream.

4. The EGR rate dynamic optimization control system in dual fuel mode according to claim 2, characterized in that: One end of the auxiliary exhaust gas box (3) is rotatably provided with an exhaust gas inlet pipe (301), a driving assembly (303) provided on the side of the exhaust gas inlet pipe (301) for driving the exhaust gas inlet pipe (301) to rotate, and a rotary joint provided at the end of the exhaust gas inlet pipe (301), and the other end of the auxiliary exhaust gas box (3) is fixedly provided with an exhaust gas outlet pipe (302); A dynamic catalytic assembly is provided in the auxiliary exhaust gas box (3), and the dynamic catalytic assembly comprises a rotating cylinder (304) fixedly connected to the exhaust gas inlet pipe (301) coaxially, a catalytic module (305) sleeved on the outer periphery of the rotating cylinder (304), a retaining frame (308) fixedly provided on the inner wall of the auxiliary exhaust gas box (3) and used to position the catalytic module (305), and a fixed cylinder (306) fixedly provided on the end surface of the auxiliary exhaust gas box (3) and having a clearance fit with the other end of the rotating cylinder (304).

5. The EGR rate dynamic optimization control system in dual fuel mode according to claim 4, characterized in that: A partition (304a) is fixedly provided inside the rotating cylinder (304) to separate the rotating cylinder (304) into two independent airflow chambers, wherein a first through hole (304b) is evenly provided on the circumferential side wall of one of the airflow chambers, and a second through hole (304c) is evenly provided on the circumferential side wall of the other airflow chamber. The retaining frame (308) includes a ring body (308a) and a plurality of sector blocks (308b) fixedly arranged on the outer periphery of the ring body (308a); the auxiliary exhaust box (3), the rotating cylinder (304) and the sector blocks (308b) enclose a plurality of catalytic chambers (308c); and the catalytic modules (305) are embedded in each catalytic chamber (308c) in a one-to-one correspondence; An exhaust gas channel (308d) is provided on the sector block (308b) at a position corresponding to the first through hole (304b), and the first through hole (304b) is periodically aligned with the catalytic cavity (308c) to directly impact the catalytic module (305), or aligned with the exhaust gas channel (308d) to laterally impact the catalytic module (305).

6. The EGR rate dynamic optimization control system in dual fuel mode according to claim 5, characterized in that: The exhaust gas channel (308d) comprises a main channel (308e) extending radially along the sector block (308b), and at least two branch channels (308f). The branch channels (308f) are symmetrically arranged on both sides of the main channel (308e), and their outlet ends are respectively connected to two adjacent catalytic chambers (308c).

7. The EGR rate dynamic optimization control system in dual fuel mode according to claim 5, characterized in that: A plurality of third through holes (306a) are provided on the circumferential side wall of the fixed cylinder (306) at positions corresponding to the second through holes (304c); The second through hole (304c) is periodically aligned or misaligned with the third through hole (306a), and pulse-transmits new exhaust gas into the inner cavity of the fixed cylinder (306).

8. The EGR rate dynamic optimization control system in dual fuel mode according to claim 5, characterized in that: A stirring assembly (307) is provided in the inner cavity of the fixed cylinder (306), and the stirring assembly (307) comprises a stirring rod (307a) fixed on the partition (304a), and a plurality of stirring blades (307b) provided on the stirring rod (307a).

9. The EGR rate dynamic optimization control system in dual fuel mode according to claim 8, characterized in that: The sensor assembly is arranged in the inner cavity of the fixed cylinder (306).

10. The EGR rate dynamic optimization control system in dual fuel mode according to claim 2, characterized in that: The control method of the system comprises the following steps: S1. When the dual-fuel engine (1) operates in a steady-state condition, the main exhaust gas box (2) operates alone to input the real-time exhaust gas of the dual-fuel engine (1) into the mixing box (4); S2. When the dual-fuel engine (1) operates in a non-steady-state operating condition, the main exhaust gas box (2) and at least one auxiliary exhaust gas box (3) operate in coordination or the auxiliary exhaust gas box (3) operates alone to input the real-time exhaust gas of the dual-fuel engine (1) and the stored exhaust gas that meets the standards into the mixing box (4), or input the stored exhaust gas that meets the standards into the mixing box (4) alone; The steady-state operating condition is an operating condition in which the dual-fuel engine (1) is in a load ≥50% of the rated load, a speed fluctuation rate ≤±2%, a combustion cycle variation rate COVimep ≤5% and a coolant temperature ≥80°C, and the unsteady-state operating condition is all operating conditions except the steady-state operating condition; When the remaining amount of the qualified exhaust gas in any one of the auxiliary exhaust gas boxes (3) drops to a set threshold, the EGR valve (6) downstream of the auxiliary exhaust gas box (3) is closed, and the other auxiliary exhaust gas box (3) is activated at the same time to ensure that the qualified exhaust gas is continuously supplied to the mixing box (4).

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