Engine multi-heat-source recovery system coupled with large and small turbochargers and working method

Abstract

According to the engine multi-heat-source recovery system coupled with the large turbocharger and the small turbocharger and the working method, through the arrangement of the large turbocharger system, the small turbocharger system, the EGR system and the steam Rankine cycle system, different branches can be switched according to different working modes of an electric generator, the waste heat utilization efficiency of the steam Rankine cycle system is improved, and the energy consumption is reduced. The system output power is improved, and the fuel economy of the internal combustion engine is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field related to multi-stage energy utilization, and in particular relates to an engine multi-heat source recovery system and a working method coupled with large and small turbochargers. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] During the actual operation of a diesel engine, about 50% of the total fuel energy is lost to the environment in the form of exhaust, scavenging air and cooling water. Recovering waste heat through steam Rankine cycle technology can effectively improve the thermal efficiency of the internal combustion engine and achieve the purpose of improving fuel economy. In the waste heat recovery system, the waste heat grade of the cylinder jacket water and the intake air is relatively low, and they are usually used as preheating sources to preheat the working fluid; under high load conditions, the waste heat grade of the intake air is relatively high, and an air cooler is used to preheat the working fluid, and the working fluid is usually heated above the evaporation temperature. In actual applications, traditional waste heat recovery systems cannot guarantee the operating stability of the system and cause energy losses.

[0004] The large and small turbocharger system is a technology proposed to solve the problem that a single turbocharger cannot meet the intake requirements of both low and high operating conditions of diesel engines as the operating range of diesel engines increases. The large and small turbocharger system arranges two or more turbochargers in parallel to reduce the equivalent flow area of ​​a single turbocharger, and adjusts the control valve of each turbocharger to cut in and out the turbocharger according to the operating conditions of the diesel engine, thereby meeting the turbocharging requirements of the diesel engine under different operating conditions and improving the transient response performance of the diesel engine.

[0005] Considering that the operating modes of large and small turbochargers during engine operation will significantly affect the type, quality and distribution of waste heat, it is difficult for traditional waste heat recovery bottoming cycle to achieve coupled recovery of multiple heat sources. Summary of the invention

[0006] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides an engine multi-heat source recovery system and a working method coupled with large and small turbochargers, so as to realize cascade utilization of energy and achieve the purpose of improving the fuel economy of the internal combustion engine.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides an engine multi-heat source recovery system coupled with large and small turbochargers, comprising:

[0009] A large and small turbocharger system, including a large compressor and a small compressor, and a large turbine and a small turbine respectively connected to the diesel engine;

[0010] A steam Rankine cycle system comprises a generator, a condenser, a cylinder jacket water heat exchanger, a large compressor air heat exchanger, a large turbine exhaust gas heat exchanger, an exhaust steam heat exchanger and a dual-purpose heat exchanger; the condenser, the cylinder jacket water heat exchanger, the large compressor air heat exchanger and the large turbine exhaust gas heat exchanger constitute a first low-temperature side branch; the condenser, the exhaust steam heat exchanger and the dual-purpose heat exchanger constitute a second low-temperature side branch; the condenser is connected to the cylinder jacket water heat exchanger and the exhaust steam heat exchanger through a first three-way valve; the medium output by the first low-temperature side branch and the second low-temperature side branch enters the expander of the generator, and the exhaust steam generated by the expander enters the high-temperature side inlet of the exhaust steam heat exchanger;

[0011] The EGR system includes an EGR switch valve connected to the intake pipe of the small turbine and the exhaust pipe of the small compressor through pipelines; the EGR high-temperature exhaust gas flow enters the high-temperature side inlet of the dual-purpose heat exchanger through the EGR switch valve.

[0012] In a second aspect, the present invention provides a working method of an engine multi-heat source recovery system coupling large and small turbochargers, which is applied to an engine multi-heat source recovery system coupling large and small turbochargers as described above, including: switching different branches to achieve efficient exhaust gas recovery according to different engine operating modes.

[0013] One or more of the above technical solutions have the following beneficial effects:

[0014] In the present invention, by setting up large and small turbocharger systems, EGR systems and steam Rankine cycle systems, different branches can be switched according to different working modes of the generator, thereby increasing the waste heat utilization efficiency of the steam Rankine cycle system, improving the system output power, and achieving the purpose of improving the fuel economy of the internal combustion engine.

[0015] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0017] Figure 1 This is a schematic structural diagram of an engine multi-heat source recovery system coupling large and small turbochargers in Embodiment 1 of the present invention;

[0018] In the figure, 1, large compressor; 2, large compressor switch valve; 3, large compressor air heat exchanger; 4, diesel engine; 5, large turbine switch valve; 6, large turbine; 7, cylinder bypass valve; 8, small compressor; 9, small compressor switch valve; 10, small compressor intake branch switch valve; 11, auxiliary fan bypass valve; 12, auxiliary fan switch valve; 13, auxiliary fan; 14, small turbine switch valve; 15, small turbine; 16, EGR switch valve; 17, expander; 18, generator; 19, condenser; 20, first three-way valve; 21, first working fluid pump; 22, cylinder jacket water heat exchanger; 23, large turbine exhaust gas heat exchanger; 24, second three-way valve; 25, second working fluid pump; 26, exhaust steam heat exchanger; 27, dual-purpose heat exchanger; 28, third three-way valve; 29, fourth three-way valve. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0020] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0021] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0022] Embodiment 1

[0023] This embodiment discloses an engine multi-heat source recovery system coupled with large and small turbochargers, comprising:

[0024] The large and small turbocharger system includes a large compressor 1 and a small compressor 8, and a large turbine 6 and a small turbine 15 respectively connected to the diesel engine;

[0025] A steam Rankine cycle system comprises a generator 18, a condenser 19, a jacket water heat exchanger 22, a large compressor air heat exchanger 3, a large turbine exhaust gas heat exchanger 23, an exhaust steam heat exchanger 26 and a dual-purpose heat exchanger 27; the condenser 19, the jacket water heat exchanger 22, the large compressor air heat exchanger 3 and the large turbine exhaust gas heat exchanger 23 constitute a first low-temperature side branch; the condenser 19, the exhaust steam heat exchanger 26 and the dual-purpose heat exchanger 27 constitute a second low-temperature side branch; the condenser 19 is connected to the jacket water heat exchanger 22 and the exhaust steam heat exchanger 26 through a first three-way valve 20; the medium output from the first low-temperature side branch and the second low-temperature side branch enters the expander 17 of the generator 18, and the exhaust steam generated by the expander 17 enters the high-temperature side inlet of the exhaust steam heat exchanger 26;

[0026] The EGR system includes an EGR switch valve 16 connected to the intake pipe of the small turbine 15 and the exhaust pipe of the small compressor 8 through pipelines; the EGR high-temperature exhaust gas flow enters the high-temperature side inlet of the dual-purpose heat exchanger 27 through the EGR switch valve 16.

[0027] In this embodiment, the large and small turbocharger system includes a large compressor 1, a large compressor switch valve 2, a large turbine switch valve 5, a large turbine 6, a small compressor 8, a small compressor switch valve 9, a small compressor intake branch switch valve 10, an auxiliary fan bypass valve 11, a small turbine switch valve 14 and a small turbine 15.

[0028] Specifically, the high-temperature exhaust gas of the diesel engine 4 is divided into two outputs: one path flows into the large turbine switch valve 5, the large turbine switch valve 5 is connected to the inlet of the large turbine 6, the outlet of the large turbine 6 is connected to the inlet of the high-temperature side of the large turbine exhaust gas heat exchanger 23, and is discharged into the atmosphere after releasing heat through the large turbine exhaust gas heat exchanger 23; the other path flows into the small turbine switch valve 14, the small turbine switch valve 14 is connected to the inlet of the small turbine 15, the outlet of the small turbine 15 is connected to the inlet B of the third three-way valve 28, the outlet C of the third three-way valve 28 is connected to the inlet of the high-temperature side of the dual-purpose heat exchanger 27, the high-temperature side outlet of the dual-purpose heat exchanger 27 is connected to the inlet A of the fourth three-way valve 29, and is discharged into the atmosphere through the outlet B of the fourth three-way valve 29.

[0029] The air intake is also divided into two inputs: one path flows into the inlet of the large compressor 1, the outlet of the large compressor 1 is connected to the large compressor switch valve 2, the large compressor switch valve 2 is connected to the high temperature side inlet of the large compressor air heat exchanger 3, and flows into the intake branch pipe of the diesel engine 4 through the high temperature side outlet of the large compressor air heat exchanger 3; the other path flows into the inlet of the small compressor 8, the outlet of the small compressor 8 is connected to one end of the small compressor switch valve 9, the other end of the small compressor switch valve 9 is connected to one end of the small compressor intake branch switch valve 10, the other end of the small compressor intake branch switch valve 10 is connected to one end of the auxiliary fan bypass valve 11, and flows into the intake branch pipe of the diesel engine 4 through the other end of the auxiliary fan bypass valve 11; the medium temperature cylinder jacket water in the diesel engine 4 is cooled by the cylinder jacket water heat exchanger 22 and then flows back to the diesel engine cylinder jacket.

[0030] The EGR system includes a cylinder bypass valve 7 , an auxiliary fan switch valve 12 , an auxiliary fan 13 and an EGR switch valve 16 .

[0031] Specifically, the EGR switch valve 16 connects the intake branch pipe in front of the small turbine switch valve 14 and the exhaust branch pipe after the small compressor switch valve 9, and the cylinder bypass valve 7 connects the exhaust branch pipe after the large compressor air heat exchanger 3 and the intake branch pipe in front of the large turbine switch valve 5; the EGR high-temperature exhaust gas flows into the EGR switch valve 16, the EGR switch valve 16 is connected to the inlet A of the third three-way valve 28, the outlet C of the third three-way valve 28 is connected to the high-temperature side inlet of the dual-purpose heat exchanger 27, the high-temperature side outlet of the dual-purpose heat exchanger 27 is connected to the inlet A of the fourth three-way valve 29, the outlet C of the fourth three-way valve 29 is connected to the auxiliary fan switch valve 12, the auxiliary fan switch valve 12 is connected to the inlet of the auxiliary fan 13, and flows into the intake branch pipe through the outlet of the auxiliary fan 13.

[0032] The steam Rankine cycle system includes an expander 17 equipped with a generator 18, a condenser 19, a first three-way valve 20, a first working fluid pump 21, a jacket water heat exchanger 22, a large compressor air heat exchanger 3, a large turbine exhaust gas heat exchanger 23, a second three-way valve 24, a second working fluid pump 25, an exhaust steam heat exchanger 26 and a dual-purpose heat exchanger 27.

[0033] Specifically, the working fluid cooled by the condenser 19 flows into the inlet A of the first three-way valve 20 and is divided into two parallel paths. One path is connected to the inlet of the first working fluid pump 21 through the outlet C of the first three-way valve 20. The outlet of the first working fluid pump 21 is connected to the low-temperature side inlet of the jacket water heat exchanger 22. The low-temperature side outlet of the jacket water heat exchanger 22 is connected to the low-temperature side inlet of the large compressor air heat exchanger 3. The low-temperature side outlet of the large compressor air heat exchanger 3 is connected to the low-temperature side inlet of the large turbine exhaust gas heat exchanger 23. The low-temperature side outlet of the large turbine exhaust gas heat exchanger 23 is connected to the inlet C of the second three-way valve 24. The other path is connected to the inlet C of the first three-way valve 20. The outlet B of the first three-way valve 20 is connected to the inlet of the second working fluid pump 25, the outlet of the second working fluid pump 25 is connected to the low-temperature side inlet of the exhaust steam heat exchanger 26, the low-temperature side outlet of the exhaust steam heat exchanger 26 is connected to the low-temperature side inlet of the dual-purpose heat exchanger 27, and the low-temperature side outlet of the dual-purpose heat exchanger 27 is connected to the inlet A of the second three-way valve 24; the outlet B of the second three-way valve 24 is connected to the inlet of the expander 17, the outlet of the expander 17 is connected to the high-temperature side inlet of the exhaust steam heat exchanger 26, the expander 17 is coaxially connected to the generator 18, and the high-temperature side outlet of the exhaust steam heat exchanger 26 is connected to the high-temperature side inlet of the condenser 19.

[0034] In this embodiment, the working fluid is water, and in some other embodiments, it may also be an organic working fluid or a non-azeotropic mixed working fluid or CO2.

[0035] Embodiment 2

[0036] This embodiment proposes a working method of the engine multi-heat source recovery system coupled with large and small turbochargers according to the first embodiment, including:

[0037] When the engine is in a low speed condition, the large turbine switch valve 5, the large compressor switch valve 2, the cylinder bypass valve 7, the auxiliary fan switch valve 12 and the EGR switch valve 16 are closed, and the small turbine switch valve 14, the small compressor switch valve 9, the small compressor intake branch switch valve 10 and the auxiliary fan bypass valve 11 are opened; in the steam Rankine cycle system, the first three-way valve 20 connects the inlet A to the outlet B, the second three-way valve 24 connects the inlet A to the outlet B, the third three-way valve 28 connects the inlet B to the outlet C, and the fourth three-way valve 29 connects the inlet A to the outlet C. Outlet B; the high-temperature exhaust gas after the small turbine 15 releases heat through the dual-purpose heat exchanger 27 and drives the steam Rankine cycle; the working fluid in the steam Rankine cycle loop that has been cooled by the condenser 19 flows into the second working fluid pump 25 through the first three-way valve 20, and the pressurized working fluid absorbs heat through the exhaust steam heat exchanger 26 and flows into the dual-purpose heat exchanger 27 to form superheated steam, and the superheated steam flows into the expander 17 through the second three-way valve 24 to perform work, and the exhaust steam at the outlet of the expander 17 releases heat through the exhaust steam heat exchanger 26 and flows into the condenser 19 for cooling, thereby realizing efficient recovery of exhaust energy under low-speed conditions.

[0038] When the engine is in a medium speed condition, the small turbine switch valve 14, the small compressor switch valve 9, the EGR switch valve 16, and the cylinder bypass valve 7 are closed, and the large turbine switch valve 5 and the large compressor switch valve 2 are opened; the first three-way valve 20 in the steam Rankine cycle system connects the inlet A to the outlet C, and the second three-way valve 24 connects the inlet C to the outlet B; the medium-temperature jacket water of the diesel engine 4, the medium-temperature air after the large compressor 1 and the high-temperature exhaust gas after the large turbine 6 drive the steam Rankine cycle; the working fluid cooled by the condenser 19 in the steam Rankine cycle passes through the first three-way valve 20, the first working fluid pump 21, the jacket water heat exchanger 22, the large compressor air heat exchanger 3 and the large turbine exhaust gas heat exchanger 23 to form superheated steam, and the superheated steam flows into the expander 17 through the second three-way valve 24 to perform work, and the exhaust steam at the outlet of the expander 17 flows into the condenser 19 through the exhaust steam heat exchanger 26 to release heat, thereby realizing efficient recovery of exhaust energy under medium speed conditions.

[0039] When the engine is at high speed, the EGR switch valve 16, the cylinder bypass valve 7 and the auxiliary fan switch valve 12 are closed, and the large turbine switch valve 5, the large compressor switch valve 2, the small turbine switch valve 14, the small compressor switch valve 9, the small compressor intake branch switch valve 10, and the auxiliary fan bypass valve 11 are opened; the first three-way valve 20 and the second three-way valve 24 in the steam Rankine cycle are fully opened, the third three-way valve 28 connects the inlet B to the outlet C, and the fourth three-way valve 29 connects the inlet A to the outlet B; the medium-temperature cylinder jacket water of the diesel engine 4, the medium-temperature air after the large compressor 1, and the high-temperature exhaust gas after the large turbine 6 and the small turbine 15 drive the steam Rankine cycle to achieve efficient recovery of diesel engine step waste heat under high speed conditions.

[0040] When part of the exhaust gas needs to be introduced to participate in the combustion process in the cylinder during the operation of the engine, the small turbine switch valve 14, the small compressor switch valve 9, the small compressor intake branch switch valve 10, the auxiliary fan bypass valve 11 are closed, the large turbine switch valve 5, the large compressor switch valve 2, the EGR switch valve 16, the auxiliary fan switch valve 12 and the cylinder bypass valve 7 are opened, and part of the air flowing through the large compressor air heat exchanger 3 flows into the exhaust branch through the cylinder bypass valve 7; the first three-way valve 20 and the second three-way valve 24 in the steam Rankine cycle are fully opened, the third three-way valve 28 connects the inlet A to the outlet C, and the fourth three-way valve 29 connects the inlet A to the outlet C; the medium-temperature cylinder jacket water of the diesel engine 4, the medium-temperature air after the large compressor 1, the high-temperature exhaust of the large turbine 6 and the high-temperature exhaust gas of the EGR drive the steam Rankine cycle, ensuring that the intake branch contains part of the burned exhaust gas while realizing efficient recovery of the exhaust and EGR exhaust gas energy.

[0041] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. An engine multi-heat source recovery system coupled with large and small turbochargers, characterized in that: include: A large and small turbocharger system, including a large compressor and a small compressor, and a large turbine and a small turbine respectively connected to the diesel engine; A steam Rankine cycle system comprises a generator, a condenser, a cylinder jacket water heat exchanger, a large compressor air heat exchanger, a large turbine exhaust gas heat exchanger, an exhaust steam heat exchanger and a dual-purpose heat exchanger; the condenser, the cylinder jacket water heat exchanger, the large compressor air heat exchanger and the large turbine exhaust gas heat exchanger constitute a first low-temperature side branch; the condenser, the exhaust steam heat exchanger and the dual-purpose heat exchanger constitute a second low-temperature side branch; the condenser is connected to the cylinder jacket water heat exchanger and the exhaust steam heat exchanger through a first three-way valve; the medium output by the first low-temperature side branch and the second low-temperature side branch enters the expander of the generator, and the exhaust steam generated by the expander enters the high-temperature side inlet of the exhaust steam heat exchanger; The EGR system includes an EGR switch valve connected to the intake pipe of the small turbine and the exhaust pipe of the small compressor through pipelines; the EGR high-temperature exhaust gas flow enters the high-temperature side inlet of the dual-purpose heat exchanger through the EGR switch valve.

2. The engine multi-heat source recovery system coupled with large and small turbochargers as claimed in claim 1, characterized in that: A large turbine switch valve is provided on the connecting branch between the diesel engine and the large turbine, and a small turbine switch valve is provided on the connecting branch between the diesel engine and the small turbine; the large compressor is connected to the high-temperature side inlet pipeline of the large compressor air heat exchanger through the large compressor switch valve, and the small compressor is connected to the intake branch pipeline of the diesel engine through the small compressor intake branch switch valve.

3. The engine multi-heat source recovery system coupled with large and small turbochargers as claimed in claim 2, characterized in that: The EGR system also includes a cylinder bypass valve, an auxiliary fan switch valve and an auxiliary fan, one end of the cylinder bypass valve is connected to the branch between the diesel engine and the large turbine switch valve through a pipeline, and the other end of the cylinder bypass valve is connected to the branch between the high-temperature side outlet of the large compressor air heat exchanger and the intake branch of the diesel engine through a pipeline; the auxiliary fan switch valve and the auxiliary fan are connected in series, and are connected in parallel with the auxiliary fan bypass valve, and the auxiliary fan bypass valve is arranged on the intake branch between the small compressor and the diesel engine.

4. The engine multi-heat source recovery system coupled with large and small turbochargers as claimed in claim 1, characterized in that: The outlet of the condenser is connected to the A port pipeline of the first three-way valve, and the B port of the first three-way valve is connected in sequence to the first working fluid pump, the low-temperature side of the cylinder jacket water heat exchanger, the low-temperature side of the large compressor air heat exchanger, the low-temperature side of the large turbine exhaust gas heat exchanger, and the C port pipeline of the second three-way valve.

5. An engine multi-heat source recovery system coupled with large and small turbochargers as claimed in claim 1 or 4, characterized in that: The outlet of the condenser is connected to the B-port pipeline of the first three-way valve, and the B-port of the first three-way valve is connected to the second working fluid pump, the low-temperature side of the exhaust steam heat exchanger, the low-temperature side of the dual-purpose heat exchanger, and the A-port pipeline of the second three-way valve in sequence; The port B of the second three-way valve is connected to the expander pipeline of the generator.

6. The engine multi-heat source recovery system coupled with large and small turbochargers as claimed in claim 2, characterized in that: The small compressor is connected to the small compressor switch valve and the A port pipeline of the third three-way valve in sequence, the C port of the third three-way valve is connected to the high-temperature side inlet pipeline of the dual-purpose heat exchanger, and the outlet of the small turbine is connected to the B pipeline of the third three-way valve; the high-temperature side outlet of the dual-purpose heat exchanger is connected to the exhaust branch of the small compressor intake branch switch valve through the fourth three-way valve.

7. A working method of an engine multi-heat source recovery system coupled with large and small turbochargers, applied to an engine multi-heat source recovery system coupled with large and small turbochargers as claimed in any one of claims 1 to 6, characterized in that: Including: according to different engine operating modes, switching different circulation pipelines to achieve efficient exhaust gas recovery.

8. A method for operating an engine multi-heat source recovery system coupling large and small turbochargers as claimed in claim 7, characterized in that: When the engine is in a low-speed working condition, the high-temperature exhaust gas of the small turbine releases heat through the dual-purpose heat exchanger and drives the steam Rankine cycle. In the steam Rankine cycle loop, the working fluid cooled by the condenser flows into the second working fluid pump through the first three-way valve. The pressurized working fluid absorbs heat through the exhaust steam heat exchanger and flows into the dual-purpose heat exchanger to form superheated steam. The superheated steam flows into the expander through the second three-way valve to perform work. The exhaust steam at the outlet of the expander releases heat through the exhaust steam heat exchanger and flows into the condenser for cooling, thereby realizing efficient recovery of exhaust energy under low-speed working conditions.

9. A method for operating an engine multi-heat source recovery system coupling large and small turbochargers as claimed in claim 7, characterized in that: When the engine is in medium speed condition, the medium temperature jacket water of the diesel engine, the medium temperature air after the large compressor and the high temperature exhaust gas after the large turbine drive the steam Rankine cycle. The working fluid cooled by the condenser in the steam Rankine cycle passes through the first three-way valve, the first working fluid pump, the jacket water heat exchanger, the large compressor air heat exchanger and the large turbine exhaust gas heat exchanger to form superheated steam. The superheated steam flows into the expander through the second three-way valve to perform work, and the exhaust steam at the outlet of the expander flows into the condenser through the exhaust steam heat exchanger to release heat, thereby realizing efficient recovery of exhaust energy under medium speed condition.

10. The method for operating an engine multi-heat source recovery system coupling large and small turbochargers as claimed in claim 7, characterized in that: When the engine is in high speed working condition, the medium temperature cylinder jacket water of the diesel engine, the medium temperature air after the large compressor, and the high temperature exhaust gas after the large turbine and the small turbine drive the steam Rankine cycle to achieve efficient recovery of diesel engine step waste heat under high speed working condition; Or, when exhaust gas needs to be introduced to participate in the combustion process in the cylinder during engine operation, the diesel engine's medium-temperature cylinder jacket water, medium-temperature air after the large compressor, large turbine high-temperature exhaust gas and EGR high-temperature exhaust gas drive the steam Rankine cycle.

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