Internal combustion engine exhaust full residual heat recovery and nitrogen oxide control system and method

Abstract

The present application relates to the internal combustion engine technical field, especially provide a kind of internal combustion engine exhaust full waste heat recovery and nitrogen oxide control system and method, the control system includes internal combustion engine, coal powder boiler, coal powder burner, high temperature heat exchanger, low temperature heat exchanger, high pressure heater and low pressure heater;The output end of the internal combustion engine is sequentially connected with high temperature heat exchanger, low temperature heat exchanger and coal powder boiler;It further includes the boiler feed water input into the system, and boiler feed water is respectively input into high temperature heat exchanger, high pressure heater, low temperature heat exchanger, low pressure heater by pipeline.The purpose is to further recover the waste heat of internal combustion engine exhaust, improve internal combustion engine exhaust waste heat recovery efficiency, reduce high concentration NOx in internal combustion engine exhaust to improve internal combustion engine energy utilization efficiency, reduce pollutant emissions.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine technology, and more specifically, to a control system and method for the complete waste heat recovery and nitrogen oxide control of internal combustion engine exhaust. Background Technology

[0002] Large natural gas internal combustion generator sets have high power generation efficiency and rapid load change capability, and are often used as important peak-shaving and frequency regulation power sources for the power grid. However, the exhaust temperature of large internal combustion engines is as high as 300~500 ℃ during operation, and the exhaust contains a high concentration of nitrogen oxides (NOx), with a concentration of 500~800 mg / m3. Therefore, the treatment of exhaust gas from internal combustion engines is particularly important.

[0003] Currently, there are generally two ways to deal with the high-temperature exhaust gas of internal combustion engines. One common approach is to directly discharge the high-temperature flue gas into the atmosphere, which results in serious energy waste. The second approach is to add a waste heat boiler and a steam turbine power generation system at the tail of the internal combustion engine. However, due to the temperature of the exhaust gas from the internal combustion engine, the steam temperature generated by the waste heat boiler will be relatively low, resulting in low efficiency of the newly built waste heat power generation system. Moreover, the investment in the entire waste heat power generation system is high, and the economic benefits are very poor. On the other hand, the common method for treating NOx exhaust from internal combustion engines is selective catalytic reduction (SCR), which uses urea or ammonia as a reducing agent to reduce the NOx concentration in the exhaust to within the permissible emission standards. However, this method requires the addition of an expensive SCR denitrification catalyst system and consumes a large amount of urea or ammonia during operation. Therefore, it is particularly important to further recover waste heat from internal combustion engine exhaust, improve the efficiency of waste heat recovery, and reduce the high concentration of NOx in internal combustion engine exhaust to improve the energy utilization efficiency of internal combustion engines, reduce pollutant emissions, and lower operating costs. Summary of the Invention

[0004] The purpose of this invention is to provide a control system and method for the complete recovery of exhaust heat and nitrogen oxides from internal combustion engines, so as to further recover exhaust heat from internal combustion engines, improve the efficiency of exhaust heat recovery from internal combustion engines, reduce the high concentration of NOx in exhaust gas from internal combustion engines to improve the energy utilization efficiency of internal combustion engines, and reduce pollutant emissions.

[0005] The first aspect of the present invention provides a control system for the complete waste heat recovery and nitrogen oxides control of internal combustion engine exhaust, including an internal combustion engine, a pulverized coal boiler, a pulverized coal burner, a high-temperature heat exchanger, a low-temperature heat exchanger, a high-pressure heater, and a low-pressure heater; the output end of the internal combustion engine is sequentially connected to the high-temperature heat exchanger, the low-temperature heat exchanger, and the pulverized coal boiler; it also includes boiler feedwater input to the system, which is input to the high-temperature heat exchanger, the high-pressure heater, the low-temperature heat exchanger, and the low-pressure heater through pipelines.

[0006] Furthermore, the input end of the high-temperature heat exchanger is provided with a first valve, which is used to regulate the flow rate of the high-pressure boiler feedwater entering the high-temperature heat exchanger.

[0007] Furthermore, the input end of the low-temperature heat exchanger is provided with a second valve, which is used to regulate the flow rate of low-pressure boiler feedwater entering the low-temperature heat exchanger.

[0008] Furthermore, the boiler feedwater in the high-pressure heater is heated by high-pressure steam discharged from the turbine, and the boiler feedwater in the low-pressure heater is heated by low-pressure steam discharged from the turbine.

[0009] Furthermore, the pulverized coal burner includes a primary air duct, an exhaust pipe, and a central pipe; The exhaust pipe is provided with an air inlet and a first nozzle. The air inlet is used to input the exhaust gas from the internal combustion engine after waste heat recovery, and the first nozzle is used to inject the exhaust gas from the internal combustion engine into the furnace of the pulverized coal boiler. The primary air duct is fitted inside the exhaust pipe and is spaced apart from the exhaust pipe. The primary air duct is provided with an air inlet and a second nozzle. The air inlet is used to input primary air containing pulverized coal, and the second nozzle is used to inject the mixed primary air, pulverized coal, and internal combustion engine exhaust into the furnace of the pulverized coal boiler. The central pipe is located inside the primary air duct.

[0010] Furthermore, the central pipe is located at the center of the primary air duct, one end of the central pipe is closed, and the other end of the central pipe passes through the side wall of the primary air duct and is connected to the exhaust pipe.

[0011] Furthermore, a number of third nozzles are provided on the side of the central tube near the closed end of the central tube. The third nozzles are used to output a preset proportion of internal combustion engine exhaust into the primary air duct.

[0012] Furthermore, several of the third nozzles are evenly distributed on the sidewall of the central tube and arranged in layers.

[0013] Furthermore, the preset proportion of internal combustion engine exhaust is 10%-20% of the internal combustion engine exhaust in the exhaust pipe.

[0014] The second aspect of the present invention provides a method for recovering total waste heat and controlling nitrogen oxides from exhaust gas of an internal combustion engine. The control system for recovering total waste heat and controlling nitrogen oxides from exhaust gas of an internal combustion engine, as described in any one of the first aspects of the present invention, includes the following steps: The high-temperature exhaust gas generated by the internal combustion engine enters the high-temperature heat exchanger. At the same time, the boiler feedwater is fed into the high-temperature heat exchanger and the high-pressure heater through pipelines. The waste heat of the high-temperature exhaust gas from the internal combustion engine is absorbed by the boiler feedwater in the high-temperature heat exchanger. The boiler feedwater in the high-pressure heater is heated by the high-pressure steam discharged from the steam turbine. The high-temperature heat exchanger outputs the internal combustion engine exhaust after primary cooling to the low-temperature heat exchanger. At the same time, boiler feedwater is fed into the low-temperature heat exchanger and the low-pressure heater through pipelines. The residual heat of the internal combustion engine exhaust after primary cooling is absorbed by the boiler feedwater in the low-temperature heat exchanger. The boiler feedwater in the low-pressure heater is heated by the low-pressure steam discharged from the turbine. The exhaust gas from the internal combustion engine, after secondary cooling, is output from the low-temperature heat exchanger and ejected through at least one of the multi-layer burner nozzles of the pulverized coal burner. The working principle of the pulverized coal burner is as follows: After secondary cooling, the exhaust gas from the internal combustion engine is fed into the exhaust pipe through the air inlet of the pulverized coal burner. At the same time, primary air containing pulverized coal is fed into the primary air duct through the air inlet. An interlayer for forming gas flow is configured between the exhaust pipe and the primary air duct. The exhaust gas from the internal combustion engine flows in the interlayer as the peripheral air of the pulverized coal burner and is injected into the furnace of the pulverized coal boiler through the first nozzle. Meanwhile, a preset proportion of the internal combustion engine exhaust in the secondary cooling internal combustion engine exhaust is injected into the primary air duct through the third nozzle on the central pipe in the primary air duct and mixed with the primary air containing pulverized coal. The mixed internal combustion engine exhaust is then injected into the furnace of the pulverized coal boiler through the second nozzle.

[0015] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects: The present invention provides a control system and method for the complete recovery of waste heat and nitrogen oxides from internal combustion engine exhaust. This system combines an internal combustion engine with a pulverized coal boiler. The high-temperature exhaust from the internal combustion engine enters a high-temperature heat exchanger, while boiler feedwater is piped to both the high-temperature heat exchanger and a high-pressure heater. The waste heat from the high-temperature exhaust is absorbed by the boiler feedwater in the high-temperature heat exchanger, and the boiler feedwater in the high-pressure heater is heated by high-pressure steam discharged from the turbine. The high-temperature heat exchanger outputs the first-cooled exhaust from the internal combustion engine to a low-temperature heat exchanger, while boiler feedwater is piped to both the low-temperature heat exchanger and a low-pressure heater. The waste heat from the first-cooled exhaust is absorbed a second time by the boiler feedwater in the low-temperature heat exchanger, and the boiler feedwater in the low-pressure heater is heated by low-pressure steam discharged from the turbine. The low-temperature heat exchanger outputs the second-cooled exhaust from the internal combustion engine, which is then ejected through at least one of the multi-layer burner nozzles of the pulverized coal burner. The second-cooled exhaust is then input into the exhaust pipe through the air inlet of the pulverized coal burner, while primary air containing pulverized coal is introduced through the air inlet. The system inputs primary air into the exhaust pipe, and a jacket is configured between the exhaust pipe and the primary air duct to form a gas flow. The exhaust from the internal combustion engine flows within the jacket as the peripheral air of the pulverized coal burner and is injected into the furnace of the pulverized coal boiler through the first nozzle. Simultaneously, a preset proportion of the exhaust from the internal combustion engine, after secondary cooling, is injected into the primary air duct through a third nozzle located on the central pipe within the primary air duct to mix with the primary air containing pulverized coal. The mixed exhaust from the internal combustion engine is then injected into the furnace of the pulverized coal boiler through a second nozzle. The exhaust from the internal combustion engine, after two waste heat recovery processes, is directly input into the pulverized coal boiler to provide combustion assistance for the pulverized coal. Through the reduction effect within the furnace of the pulverized coal boiler, the concentration of NOx in the exhaust from the internal combustion engine is reduced, while the formation of NOx during the combustion of pulverized coal is suppressed. This eliminates the need for NOx purification SCR equipment for the exhaust from the internal combustion engine, reducing system costs. The pulverized coal boiler furnace recovers and utilizes the low-temperature waste heat from the exhaust from the internal combustion engine, further improving energy utilization efficiency and avoiding the waste of energy and environmental pollution caused by the direct emission of high-temperature exhaust. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the internal combustion engine exhaust waste heat recovery and nitrogen oxide control system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall structure of a pulverized coal burner provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the nozzle structure of a pulverized coal burner provided in an embodiment of the present invention; Figure 4 This is a schematic flowchart of the method for recovering total waste heat from internal combustion engine exhaust and controlling nitrogen oxides provided in an embodiment of the present invention.

[0017] Icons: 1-Internal combustion engine, 2-Pulverized coal boiler, 3-Pulverized coal burner, 31-Air inlet, 32-Air inlet, 33-Primary air duct, 34-Exhaust pipe, 35-Central pipe, 36-Third nozzle, 37-First nozzle, 38-Second nozzle, 4-High temperature heat exchanger, 5-Low temperature heat exchanger, 6-High pressure heater, 7-First valve, 8-Low pressure heater, 9-Second valve. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0020] As indicated in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0021] Flowcharts are used in this specification to illustrate the operations performed by the system according to embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0022] Please see Figures 1 to 3As shown, the first aspect of the present invention provides a control system for the complete waste heat recovery and nitrogen oxide control of internal combustion engine exhaust, including an internal combustion engine 1, a pulverized coal boiler 2, a pulverized coal burner 3, a high-temperature heat exchanger 4, a low-temperature heat exchanger 5, a high-pressure heater 6, and a low-pressure heater 8; the output end of the internal combustion engine 1 is sequentially connected to the high-temperature heat exchanger 4, the low-temperature heat exchanger 5, and the pulverized coal boiler 2; it also includes boiler feedwater input to the system, which is input to the high-temperature heat exchanger 4, the high-pressure heater 6, the low-temperature heat exchanger 5, and the low-pressure heater 8 through pipelines respectively; wherein, the boiler feedwater in the high-pressure heater 6 is heated by high-pressure steam discharged from the turbine, and the boiler feedwater in the low-pressure heater 8 is heated by low-pressure steam discharged from the turbine. The internal combustion engine exhaust waste heat recovery and nitrogen oxide control system and method provided in this embodiment combine an internal combustion engine 1 with a pulverized coal boiler 2. The high-temperature exhaust gas generated by the internal combustion engine 1 enters a high-temperature heat exchanger 4. Simultaneously, boiler feedwater is fed into the high-temperature heat exchanger 4 and a high-pressure heater 6 through pipelines. The waste heat of the high-temperature exhaust gas from the internal combustion engine 1 is absorbed by the boiler feedwater in the high-temperature heat exchanger 4. The boiler feedwater in the high-pressure heater 6 is heated by high-pressure steam discharged from the turbine. The high-temperature heat exchanger 4 outputs the internal combustion engine exhaust gas after primary cooling to a low-temperature heat exchanger 5. Simultaneously, boiler feedwater is fed into the low-temperature heat exchanger 5 and a low-pressure heater 8 through pipelines. The waste heat of the internal combustion engine exhaust gas after primary cooling is absorbed a second time by the boiler feedwater in the low-temperature heat exchanger 5. The waste heat in the low-pressure heater 8 is further heated by the boiler feedwater. The boiler feedwater is heated by low-pressure steam discharged from the turbine; the exhaust gas from the internal combustion engine, after secondary cooling, is output from the low-temperature heat exchanger 5 and ejected through at least one of the multi-layer burner nozzles of the pulverized coal burner 3, wherein the pulverized coal burner 3 preferably has 6 layers of nozzles, and in actual use, the internal combustion engine exhaust gas is preferably ejected from the second layer of nozzles from bottom to top; through the reduction effect in the furnace of the pulverized coal boiler 2, the concentration of NOx in the exhaust gas of the internal combustion engine is reduced, while the formation of NOx during the combustion of pulverized coal is suppressed, thereby eliminating the need for the NOx purification SCR equipment for the exhaust gas of the internal combustion engine and reducing system costs. The furnace of the pulverized coal boiler 2 recovers and utilizes the low-temperature waste heat of the exhaust gas of the internal combustion engine, further improving energy utilization efficiency and avoiding the waste of energy and environmental pollution caused by the direct emission of high-temperature exhaust gas.

[0023] Preferred, such as Figure 1 As shown, the input end of the high-temperature heat exchanger 4 is provided with a first valve 7, which is used to regulate the flow rate of the high-pressure boiler feedwater entering the high-temperature heat exchanger 4. The input end of the low-temperature heat exchanger 5 is provided with a second valve 9, which is used to regulate the flow rate of the low-pressure boiler feedwater entering the low-temperature heat exchanger 5. In this embodiment, the first valve 7 and the second valve 9 are existing feedwater regulating valves. By setting the first valve 7 and the second valve 9, the flow rate of the boiler feedwater entering the high-temperature heat exchanger 4 and the low-temperature heat exchanger 5 can be regulated according to actual needs, thereby regulating the heat recovery of the internal combustion exhaust gas by the high-temperature heat exchanger 4 and the low-temperature heat exchanger 5.

[0024] Preferred, such as Figure 2 and Figure 3 As shown, the pulverized coal burner 3 includes a primary air duct 33, an exhaust pipe 34, and a central pipe 35. The exhaust pipe 34 is provided with an air inlet 31 and a first nozzle 37. The air inlet 31 is used to input exhaust gas from the internal combustion engine after waste heat recovery, and the first nozzle 37 is used to inject the exhaust gas from the internal combustion engine into the furnace of the pulverized coal boiler 2. The primary air duct 33 is sleeved inside the exhaust pipe 34 and is spaced apart from the exhaust pipe 34. The primary air duct 33 is provided with an air inlet 32 ​​and a second nozzle 38. The air inlet 32 ​​is used to input primary air containing pulverized coal, and the second nozzle 38 is used to inject the mixed primary air into the furnace of the pulverized coal boiler 2. Primary air, pulverized coal, and exhaust gas from the internal combustion engine are injected into the furnace of the pulverized coal boiler 2. A central pipe 35 is located within the primary air duct 33, at its center. One end of the central pipe 35 is closed, and the other end penetrates the side wall of the primary air duct 33 and connects to the exhaust pipe 34. Several third nozzles 36 are located on the side of the central pipe 35 near its closed end. These third nozzles 36 output a preset proportion of exhaust gas from the internal combustion engine into the primary air duct 33. The several third nozzles 36 are evenly distributed on the side of the central pipe 35. The wall is layered, and the preset proportion of internal combustion engine exhaust is 10%-20% of the internal combustion engine exhaust in the exhaust pipe 34. The third nozzle 36 is preferably arranged in two layers, and each layer preferably has 6 third nozzles. The output ratio of internal combustion engine exhaust can be configured by limiting the area of ​​the above-mentioned pipe fittings. In this embodiment, the working principle of the pulverized coal burner 3 is as follows: the internal combustion engine exhaust after secondary cooling is input into the exhaust pipe 34 through the air inlet 31 of the pulverized coal burner 3, and at the same time, primary air containing pulverized coal is input into the primary air duct 33 through the air inlet 32. A wall is arranged between the exhaust pipe 34 and the primary air duct 33. The jacket is used to form the gas flow. The exhaust gas from the internal combustion engine flows in the jacket as the peripheral air of the pulverized coal burner 3 and is injected into the furnace of the pulverized coal boiler 2 through the first nozzle 37. At the same time, a preset proportion of the exhaust gas from the internal combustion engine after secondary cooling is also injected into the primary air duct 33 through the third nozzle 36 on the central pipe 35 located in the primary air duct 33 and mixed with the primary air containing pulverized coal. The mixed exhaust gas from the internal combustion engine is injected into the furnace of the pulverized coal boiler 2 through the second nozzle 38. The exhaust gas from the internal combustion engine after two waste heat recovery processes is directly input into the pulverized coal boiler 2 to provide combustion assistance for the pulverized coal. Specifically, after pulverized coal enters the boiler furnace, within the area of ​​the second nozzle 38 of the pulverized coal burner 3, under conditions of low excess air coefficient, the pulverized coal rapidly pyrolyzes into combustible volatile gases and coke. The combustible volatile gases mainly include hydrocarbons (CnHm), carbon monoxide (CO), and hydrogen (H2). At the high temperature in the furnace, the combustible volatile gases and coke have strong reducing properties. At this time, the exhaust gas from the internal combustion engine, simultaneously fed into the furnace, comes into full contact with these reducing substances, and the NOx in it is fully reduced, thus generating harmless N2. The main reaction equations are as follows: Coal → Coke (C) + Volatile gases (CnHm, CO, H2); NO + CnHm → CO2 + H2O + N2; NO + C → CO2 + N2; NO + CO → CO2 + N2; NO + H2 → H2O + N2; In summary, the invention avoids the energy waste and environmental pollution caused by the direct emission of high-temperature exhaust from internal combustion engines, significantly improving the energy utilization efficiency of the entire system. Furthermore, by using pulverized coal in the boiler furnace to reduce NOx in the internal combustion engine exhaust, the NOx purification SCR equipment for the internal combustion engine exhaust is eliminated. This results in a simple system structure, low equipment investment and maintenance, significantly reduced operating costs, and substantial economic benefits.

[0025] Please see Figure 4 As shown, the second aspect of the present invention provides a method for total waste heat recovery and nitrogen oxide control of internal combustion engine exhaust, which, according to any one of the technical solutions of the first aspect of the present invention, includes the following steps: Step S100: The internal combustion engine 1 generates high-temperature exhaust gas which enters the high-temperature heat exchanger 4. At the same time, the boiler feedwater is fed into the high-temperature heat exchanger 4 and the high-pressure heater 6 through pipelines. The waste heat of the high-temperature exhaust gas of the internal combustion engine 1 is absorbed by the boiler feedwater in the high-temperature heat exchanger 4. The boiler feedwater in the high-pressure heater 6 is heated by the high-pressure steam discharged from the steam turbine. Step S200: The high-temperature heat exchanger 4 outputs the internal combustion engine exhaust after the first cooling to the low-temperature heat exchanger 5. At the same time, the boiler feedwater is fed into the low-temperature heat exchanger 5 and the low-pressure heater 8 through the pipeline. The residual heat of the internal combustion engine exhaust after the first cooling is absorbed by the boiler feedwater in the low-temperature heat exchanger 5. The boiler feedwater in the low-pressure heater 8 is heated by the low-pressure steam discharged from the steam turbine. Step S300: The low-temperature heat exchanger 5 outputs the exhaust gas from the internal combustion engine after secondary cooling, and it is ejected through at least one of the multi-layer burner nozzles of the pulverized coal burner 3. The working principle of the pulverized coal burner 3 is as follows: After secondary cooling, the exhaust gas from the internal combustion engine is fed into the exhaust pipe 34 through the air inlet 31 of the pulverized coal burner 3. At the same time, the primary air containing pulverized coal is fed into the primary air duct 33 through the air inlet 32. An interlayer for forming gas flow is configured between the exhaust pipe 34 and the primary air duct 33. The exhaust gas from the internal combustion engine flows in the interlayer as the peripheral air of the pulverized coal burner 3 and is injected into the furnace of the pulverized coal boiler 2 through the first nozzle 37. Meanwhile, the internal combustion engine exhaust in the secondary cooling exhaust, in a preset proportion, is also injected into the primary air duct 33 through the third nozzle 36 on the central pipe 35 located in the primary air duct 33 and mixed with the primary air containing pulverized coal. The mixed internal combustion engine exhaust is then injected into the furnace of the pulverized coal boiler 2 through the second nozzle 38.

[0026] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

[0027] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0028] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although various examples have been discussed in the foregoing disclosure of some embodiments of the invention that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments described herein. For example, while the system components described above can be implemented using hardware devices, they can also be implemented solely using software solutions, such as installing the described system on existing servers or mobile devices.

[0029] Similarly, it should be noted that, in order to simplify the description disclosed herein and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments in this specification may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this method of disclosure does not imply that the subject matter of this specification requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0030] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A control system for total waste heat recovery and nitrogen oxide control of internal combustion engine exhaust, characterized in that, The system includes an internal combustion engine (1), a pulverized coal boiler (2), a pulverized coal burner (3), a high-temperature heat exchanger (4), a low-temperature heat exchanger (5), a high-pressure heater (6), and a low-pressure heater (8); the output end of the internal combustion engine (1) is sequentially connected to the high-temperature heat exchanger (4), the low-temperature heat exchanger (5), and the pulverized coal boiler (2); the system also includes boiler feedwater, which is fed into the high-temperature heat exchanger (4), the high-pressure heater (6), the low-temperature heat exchanger (5), and the low-pressure heater (8) through pipelines. The pulverized coal burner (3) includes a primary air duct (33), an exhaust pipe (34), and a central pipe (35); The exhaust pipe (34) is provided with an air inlet (31) and a first nozzle (37). The air inlet (31) is used to input the exhaust of the internal combustion engine (1) after waste heat recovery, and the first nozzle (37) is used to inject the exhaust of the internal combustion engine (1) into the furnace of the pulverized coal boiler (2). The primary air duct (33) is fitted inside the exhaust pipe (34) and there is a gap between them. The primary air duct (33) is provided with an air inlet (32) and a second nozzle (38). The air inlet (32) is used to input primary air containing pulverized coal, and the second nozzle (38) is used to inject the mixed primary air, pulverized coal, and exhaust gas from the internal combustion engine (1) into the furnace of the pulverized coal boiler (2). The central pipe (35) is located inside the primary air duct (33). The central pipe (35) is located at the center of the primary air duct (33). One end of the central pipe (35) is closed, and the other end of the central pipe (35) passes through the side wall of the primary air duct (33) and is connected to the exhaust pipe (34). The central tube (35) has several third nozzles (36) on one side near the closed end of the central tube (35). The third nozzles (36) are used to output a preset proportion of exhaust gas from the internal combustion engine (1) into the primary air duct (33). The several third nozzles (36) are evenly distributed on the side wall of the central tube (35) and arranged in layers.

2. The internal combustion engine exhaust waste heat recovery and nitrogen oxide control system according to claim 1, characterized in that, The high-temperature heat exchanger (4) is provided with a first valve (7) at its input end. The first valve (7) is used to regulate the flow rate of the high-pressure boiler feedwater entering the high-temperature heat exchanger (4).

3. The internal combustion engine exhaust waste heat recovery and nitrogen oxide control system according to claim 1, characterized in that, The input end of the low-temperature heat exchanger (5) is provided with a second valve (9), which is used to regulate the flow rate of low-pressure boiler feedwater entering the low-temperature heat exchanger (5).

4. The internal combustion engine exhaust waste heat recovery and nitrogen oxide control system according to claim 1, characterized in that, The boiler feedwater in the high-pressure heater (6) is heated by high-pressure steam discharged from the turbine, and the boiler feedwater in the low-pressure heater (8) is heated by low-pressure steam discharged from the turbine.

5. The internal combustion engine exhaust waste heat recovery and nitrogen oxide control system according to claim 1, characterized in that, The preset ratio of internal combustion engine (1) exhaust is 10%-20% of the internal combustion engine (1) exhaust in the exhaust pipe (34).

6. A method for recovering total waste heat from internal combustion engine exhaust and controlling nitrogen oxides, characterized in that, The internal combustion engine exhaust waste heat recovery and nitrogen oxide control system according to any one of claims 1 to 5 includes the following steps: The internal combustion engine (1) generates high-temperature exhaust gas which enters the high-temperature heat exchanger (4). At the same time, the boiler feedwater is fed into the high-temperature heat exchanger (4) and the high-pressure heater (6) through pipelines. The waste heat of the high-temperature exhaust gas of the internal combustion engine (1) is absorbed by the boiler feedwater in the high-temperature heat exchanger (4). The boiler feedwater in the high-pressure heater (6) is heated by the high-pressure steam discharged from the steam turbine. The high-temperature heat exchanger (4) outputs the exhaust gas of the internal combustion engine (1) after one cooling to the low-temperature heat exchanger (5). At the same time, the boiler feedwater is fed into the low-temperature heat exchanger (5) and the low-pressure heater (8) through the pipeline. The residual heat of the exhaust gas of the internal combustion engine after one cooling is absorbed by the boiler feedwater in the low-temperature heat exchanger (5) for the second time. The boiler feedwater in the low-pressure heater (8) is heated by the low-pressure steam discharged from the steam turbine. The low-temperature heat exchanger (5) outputs the exhaust gas from the internal combustion engine after secondary cooling and sprays it out through at least one of the multi-layer burner nozzles of the pulverized coal burner (3). The working principle of the pulverized coal burner (3) is as follows: After secondary cooling, the exhaust gas from the internal combustion engine is fed into the exhaust pipe (34) through the air inlet (31) of the pulverized coal burner (3). At the same time, the primary air containing pulverized coal is fed into the primary air duct (33) through the air inlet (32). An interlayer for forming gas flow is configured between the exhaust pipe (34) and the primary air duct (33). The exhaust gas from the internal combustion engine flows in the interlayer as the peripheral air of the pulverized coal burner (3) and is injected into the furnace of the pulverized coal boiler (2) through the first nozzle (37). Meanwhile, the internal combustion engine exhaust in the secondary cooling exhaust, in a preset proportion, is also injected into the primary air duct (33) through the third nozzle (36) on the central pipe (35) in the primary air duct (33) and mixed with the primary air containing pulverized coal. The mixed internal combustion engine exhaust is then injected into the furnace of the pulverized coal boiler (2) through the second nozzle (38).

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