Marine pure methanol engine fuel preheating system

Abstract

The utility model discloses a marine pure methanol engine fuel preheating system which comprises a conventional preheating circulation loop and a cold start preheating circulation loop, and the preheating circulation loop comprises a secondary heating unit, two electric control three-way valves, a first electric pump, a first filter and a pressure regulating valve. The cold start preheating circulation loop comprises a first-stage heating unit, a second filter, two electric control three-way valves, an electric control two-way valve and a second electric pump. According to the utility model, waste heat of circulating cooling water and exhaust gas of the marine pure methanol engine is fully utilized, and the problems of low combustion efficiency, severe emission and instability in a cold start stage are solved. And the energy consumption of methanol fuel atomization is reduced, so that the operation cost of the marine pure methanol engine is reduced.

Description

Technical Field

[0001] The utility model relates to a marine engine, in particular to a fuel preheating system of a marine clean energy engine, belonging to the technical field of new energy engines. Background Art

[0002] As a clean fuel, methanol produces significantly less harmful substances than petroleum combustion. Methanol has the advantages of being sulfide-free, reducing carbon smoke and nitrogen oxide emissions, having good anti-knock properties, and containing up to 50% oxygen. Among the many preferred alternative fuels for marine engines, methanol has important research value and development prospects, and has become the preferred alternative fuel for marine engines.

[0003] However, methanol has a high latent heat of vaporization. Whether it is direct injection or manifold injection, marine pure methanol engines face the problem of difficult cold start of the engine and incomplete combustion under other loads. During the cold start process of marine pure methanol engines, methanol fuel vaporizes poorly after injection in the intake duct, often enters the combustion chamber in liquid form to dilute the lubricating oil, and reduces the temperature in the cylinder at medium and low loads, causing the flame propagation front to quench on the combustion chamber wall. Therefore, how to improve the high latent heat of vaporization of methanol fuel in the engine and improve the combustion quality of methanol fuel under all engine operating conditions is a technical problem that needs to be solved urgently by those skilled in the art. Utility Model Content

[0004] The utility model aims to provide a pure methanol marine engine fuel preheating system, aiming to solve the problems of pure methanol fuel engine in the cold start stage and in the poor combustion stage due to poor methanol fuel atomization causing difficulty in starting, insufficient combustion causing reduced combustion efficiency, poor emissions and instability.

[0005] The utility model is realized through the following technical solutions:

[0006] A fuel preheating system for a pure methanol engine for a ship, wherein an intake manifold of a methanol rail of the pure methanol engine for a ship is provided with an intake manifold alcohol injector, a methanol rail voltage regulator is provided at one end of the methanol rail, an intake manifold is connected to one end of the intake manifold, and the other end of the intake manifold is communicated with an exhaust manifold; the system comprises a conventional preheating circulation loop and a cold start preheating circulation loop, wherein the conventional preheating circulation loop comprises a secondary heating unit, a first electrically controlled three-way valve, a second electrically controlled three-way valve, a first electric pump, a first filter and a pressure regulating valve, and the cold start preheating circulation loop comprises a primary heating unit, a second filter, a third electrically controlled three-way valve, a fourth electrically controlled three-way valve, an electrically controlled two-way valve and a second electric pump; in a conventional preheating circulation loop, a connecting pipe connected to the methanol fuel tank is connected to the fuel input port of the secondary heating unit in sequence through the first filter and the third electrically controlled three-way valve through-end, a methanol output port of the secondary heating unit is connected to the first electrically controlled three-way valve through-end, the first electric pump, the second filter, the pressure regulating valve and one end of the methanol rail in sequence through a connecting pipe, and one end of the exhaust manifold is connected to the exhaust gas input port of the secondary heating unit through the bypass end of the second electrically controlled three-way valve. The exhaust gas output port of the secondary heating unit leads to the exhaust port of the exhaust manifold; in the cold start preheating circulation loop, the connecting pipe connected to the methanol fuel tank is connected to the methanol input port of the primary heating unit through the second filter, the bypass end of the third electrically controlled three-way valve, and the second electric pump in sequence, the methanol output port of the primary heating unit is connected to the first electrically controlled three-way valve bypass port of the conventional preheating circulation loop through the connecting pipe, the connecting pipe of the methanol return oil port of the primary heating unit returns to the methanol fuel tank through the bypass end of the fourth electrically controlled three-way valve, and the connecting pipe connected to the methanol discharge port of the primary heating unit returns to the methanol fuel tank through the electrically controlled two-way valve; the cooling water pipe of the marine pure methanol engine is connected to the cooling water input port of the primary heating unit, and the cooling water output port of the primary heating unit returns to the marine pure methanol engine through the cooling water pipe; the signal lines of the central control unit are respectively connected to the first electric pump control end, the second electric pump control end, the first electrically controlled three-way valve control end, the second electrically controlled three-way valve control end, the third electrically controlled three-way valve control end, the fourth electrically controlled three-way valve control end, the electrically controlled two-way valve control end, the primary heating unit control end and the secondary heating unit control end.

[0007] The purpose of the utility model can be further achieved by the following technical measures.

[0008] Furthermore, the pressure sensor is connected to the connection between the pressure regulating valve and the methanol rail, the first temperature sensor is connected to the connecting pipe of the methanol output end of the secondary heating unit, and the second temperature sensor is connected to the connecting pipe between the methanol output port of the primary heating unit and the bypass end of the first electric-controlled three-way valve.

[0009] Furthermore, the primary heating unit is a box structure, including a box and several rectangular cooling water channels and multiple ceramic electric heating rods whose ends are respectively fixed on both sides of the box, and the multiple ceramic electric heating rods are located on the lower side of the several rectangular cooling water channels; the connection between the end panel and the box is sealed by a sealing ring, and the outside of the connection between the box and the several rectangular cooling water channels is also provided with a water collecting trough closed by a sealing plate, and the sealing plate fixed on the outside of the water collecting trough is provided with corresponding cooling water input port and cooling water output port, the methanol output port and the methanol return oil port are respectively arranged at the two ends of the box, and the methanol input port and the methanol discharge port arranged side by side are located on the same side of the box.

[0010] Furthermore, the secondary heating unit is a cylindrical structure, including a shell, a lower end cover, an upper inner oil accumulation end cover, a lower inner oil accumulation end cover, multiple methanol delivery pipes and 2 asbestos heat-resistant sealing rings, the two ends of the multiple vertically evenly arranged methanol delivery pipes are respectively fixedly welded to the upper inner oil accumulation end cover and the lower inner oil accumulation end cover, and the upper inner oil accumulation end cover is embedded in the inverted bottom end of the shell; the lower inner oil accumulation end cover is embedded in the lower end cover, and the lower inner oil accumulation end cover and the lower end cover located between the upper inner oil accumulation end cover and the bottom end of the shell are respectively sealed by asbestos heat-resistant sealing rings; the fuel output port of the secondary heating unit located in the center of the upper inner oil accumulation end cover extends upward from the top of the shell, and the methanol output port of the secondary heating unit located in the center of the lower inner oil accumulation end cover extends downward from the lower end cover; the exhaust gas input port of the secondary heating unit is vertically connected to the upper end of one side of the shell, and the exhaust gas output port of the secondary heating unit is vertically connected to the lower end of the other side of the shell.

[0011] Furthermore, the first temperature sensor and the second temperature sensor are both PT1000, and the temperature range is: -50℃~+200℃; the pressure range of the pressure sensor is: 0~1.6Mpa; the pressure range of the first electric pump and the second electric pump is: 0.2~1.0Mpa, and the flow rate is: 20m 3 / h; the filtration accuracy of the first filter is ≤10μm; the filtration accuracy of the second filter is ≤12μm.

[0012] The utility model uses the heat generated by the 55-70℃ high-temperature cooling water and the ceramic heating rod when it is powered on after circulating the marine pure methanol engine to preheat the primary heating unit used during cold start, and uses the 60-110℃ high-temperature exhaust gas discharged by the marine pure methanol engine to preheat the secondary heating unit during normal engine operation, making full use of the waste heat of the circulating cooling water and exhaust gas of the marine pure methanol engine, solving the problems of difficult atomization of methanol fuel in the cold start stage, reduced combustion efficiency, poor and unstable emissions caused by insufficient combustion, reducing the energy consumption of methanol fuel atomization, and thus reducing the operating cost of the marine pure methanol engine.

[0013] Advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments, which are given as examples only with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the principle diagram of the fuel preheating system for pure methanol marine engine of the utility model, which is in the cold start preheating stage at this time;

[0015] Figure 2 This is the principle diagram of the fuel preheating system for pure methanol marine engine of the utility model, which is in the stage of cold start preheating closed and conventional preheating cycle opened;

[0016] Figure 3 It is the front view of the primary heating unit;

[0017] Figure 4 yes Figure 3 AA cross-sectional view;

[0018] Figure 5 It is a three-dimensional diagram of the primary heating unit with the end panels at both ends of the box body and the upper and lower side panels removed;

[0019] Figure 6 is a cross-sectional view of the secondary heating unit. DETAILED DESCRIPTION

[0020] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0021] like Figure 1 to Figure 6 As shown, in the engine fuel preheating system of the utility model, an intake manifold alcohol injector 20 is respectively provided in the intake manifold 101 of the methanol rail 10 of the marine pure methanol engine 100, a methanol rail regulator 30 is provided at the right end of the methanol rail 10, an intake manifold 40 is respectively connected to one end of the intake manifold 101, and the other end of the intake manifold 101 is respectively communicated with the exhaust manifold 50. The utility model includes a conventional preheating circulation loop 1 and a cold start preheating circulation loop 2, the conventional preheating circulation loop 1 includes a secondary heating unit 11, a first electrically controlled three-way valve 111, a second electrically controlled three-way valve 112, a first electric pump 121, a first filter 131 and a pressure regulating valve 14, and the cold start preheating circulation loop 2 includes a primary heating unit 21, a second filter 132, a third electrically controlled three-way valve 113, a fourth electrically controlled three-way valve 114, an electrically controlled two-way valve 22 and a second electric pump 122.

[0022] In the conventional preheating circulation loop 1, the connecting pipe 301 connected to the methanol fuel tank 3 is connected to the secondary heating unit fuel input port 115 through the second filter 132 and the straight end of the third electric-controlled three-way valve 113 in sequence, and the secondary heating unit methanol output port 116 is connected to the first electric-controlled three-way valve 111 straight end, the first electric pump 121, the first filter 131, the pressure regulating valve 14 and the left end of the methanol rail 10 through the connecting pipe 301. The pressure regulating valve 14 is used to realize dynamic feedback regulation of the pressure signal fed back by the pressure sensor 5. The left end of the exhaust manifold 50 is connected to the exhaust gas input port 117 of the secondary heating unit through the second electric-controlled three-way valve side 112, and the exhaust gas output port 118 of the secondary heating unit leads to the exhaust port of the exhaust manifold 50.

[0023] In the cold start preheating circulation loop 2, the connecting pipe 301 connected to the methanol fuel tank 3 is connected to the primary heating unit methanol input port 211 through the second filter 132, the bypass end of the third electrically controlled three-way valve 113, and the second electric pump 122 in sequence, the primary heating unit methanol output port 212 is connected to the bypass port of the first electrically controlled three-way valve 111 of the conventional preheating circulation loop 2 through the connecting pipe 301, the connecting pipe 301 of the primary heating unit methanol return oil port 213 returns to the methanol fuel tank 3 through the bypass end of the fourth electrically controlled three-way valve 114, and the connecting pipe 301 connected to the primary heating unit methanol discharge port 214 returns to the methanol fuel tank 3 through the electrically controlled two-way valve 22. The cooling water pipe 102 of the marine pure methanol engine 100 is connected to the cooling water input port 103 of the primary heating unit, and the cooling water output port 104 of the primary heating unit returns to the marine pure methanol engine 100 through the cooling water pipe 102.

[0024] The signal line 41 of the central control unit 4 is respectively connected to the control end of the first electric pump 121, the control end of the second electric pump 122, the control end of the first electric-controlled three-way valve 111, the control end of the second electric-controlled three-way valve 112, the control end of the third electric-controlled three-way valve 113, the control end of the fourth electric-controlled three-way valve 114, the control end of the electric-controlled two-way valve 22, the control end of the first-level heating unit 2 and the control end of the second-level heating unit 2.

[0025] The pressure sensor 5 is connected to the connection between the pressure regulating valve 14 and the methanol rail 10, and is used to monitor the rail pressure of the methanol rail 14 in real time. The first temperature sensor 61 is connected to the connecting pipe 301 of the methanol output port 116 of the secondary heating unit, and the second temperature sensor 62 is connected to the connecting pipe 301 between the methanol output port 212 of the primary heating unit and the bypass end of the first electric control three-way valve 111, and both are used to monitor the supply temperature of the methanol fuel. When the marine pure methanol engine 100 is in a working condition of different loads, the central control unit 4 monitors the temperature of the methanol fuel in real time through the first temperature sensor 61, thereby adjusting the opening of the second electric control three-way valve 112 in real time, realizing the preheating effect of the secondary heating unit 1 on the methanol fuel under all working conditions, so as to realize the economical and reliable operation of the marine pure methanol engine 100.

[0026] like Figure 3 to Figure 5 As shown, the primary heating unit 2 is a box structure, including a box 21 and four rectangular cooling water channels 22 and a plurality of ceramic electric heating rods 23, each of which is fixed at both ends of the box 2. The plurality of ceramic electric heating rods 23 are located at the lower side of the four rectangular cooling water channels 22. A water collecting tank 222 closed by a sealing plate 221 is provided on the outer side of the connection between the box 21 and the four rectangular cooling water channels 22. The connection between the end panel 201 and the box 21 is sealed by a sealing ring 202. The sealing plate 221 fixed on the outer side of the water collecting tank 222 is provided with a corresponding cooling water input port 103 and cooling water output port 104. The methanol output port 212 and the methanol oil return port 213 are respectively arranged at the two ends of the box 21. The methanol input port 211 and the methanol discharge port 214 arranged side by side are located on the same side of the box 21 as the cooling water output port 104.

[0027] like Figure 6 As shown, the secondary heating unit 1 is a cylindrical structure, including a shell 11, a lower end cover 12, an upper inner oil accumulation end cover 13, a lower inner oil accumulation end cover 14, a plurality of methanol delivery pipes 15 and two asbestos heat-resistant sealing rings 16. The two ends of the plurality of vertically evenly arranged methanol delivery pipes 15 are respectively fixedly welded to the upper inner oil accumulation end cover 13 and the lower inner oil accumulation end cover 14, and the upper inner oil accumulation end cover 13 is embedded in the bottom end of the inverted shell 11. The lower inner oil accumulation end cover 14 is embedded in the lower end cover 12 and is located between the upper inner oil accumulation end cover 13 and the bottom end of the shell 11. The lower inner oil accumulation end cover 14 and the lower end cover 12 are sealed by the asbestos heat-resistant sealing ring 16 respectively. The secondary heating unit fuel output port 116 located in the center of the upper inner oil accumulation end cover 13 extends upward from the top of the shell 11, and the secondary heating unit methanol output port 115 located in the center of the lower inner oil accumulation end cover 14 extends downward from the lower end cover 12. The secondary heating unit exhaust gas input port 117 is vertically connected to the upper end of one side of the shell 11 , and the secondary heating unit exhaust gas output port 118 is vertically connected to the lower end of the other side of the shell 11 .

[0028] The first temperature sensor 61 and the second temperature sensor 62 are both PT1000, and the temperature range is -50°C to +200°C; the pressure range of the pressure sensor 5 is 0 to 1.6 MPa; the pressure range of the first electric pump 121 and the second electric pump 122 is 0.2 to 1.0 MPa, and the flow rate is 20 m 3 / h; the filtering accuracy of the first filter 131 is ≤10μm; the filtering accuracy of the second filter 132 is ≤12μm.

[0029] The process of preheating pure methanol fuel for marine engines using the utility model is as follows:

[0030] First, the central control unit determines the state of the marine pure methanol engine based on the cooling water temperature and the lubricating oil temperature;

[0031] like Figure 1 As shown, 1) when the ambient temperature is lower than 0°C, the cold start preheating circulation loop 2 is turned on to warm up the marine pure methanol engine. At this time, the conventional preheating circulation loop 1 is in a stopped working state, and the central control unit 4 sends a signal, and the bypass end of the third electric control three-way valve 113 and the through end of the fourth electric control three-way valve 114 are respectively electrically connected, and then the second electric pump 122 is electrically started, and at the same time, the central control unit 4 sends a signal to adjust the pressure of the pressure regulating valve 14 to reach 0.8Mpa. The methanol fuel in the methanol fuel tank 4 is replenished into the primary heating unit 2 through the second filter 132, the bypass end of the third electric control three-way valve 113 (direction indicated by the right-angle arrow) and the second electric pump 122 as shown by the arrow direction.

[0032] 2) When the primary heating unit 21 is full of methanol fuel, the central control unit 4 sends a signal, and the multiple ceramic heating rods 23 are powered on to preheat the methanol fuel in the primary heating unit 21. At the same time, the high-temperature cooling water of 55-70°C after circulation of the marine pure methanol engine passes through the primary heating unit 21 as shown by the arrow direction, and also preheats the methanol fuel in the primary heating unit 21. When the second temperature sensor 62 detects that the temperature of the methanol fuel output by the primary heating unit 21 is ≥50°C, the central control unit 4 sends a signal to shut down the second electric pump 122.

[0033] 3) The central control unit 4 sends a signal to start the intake manifold alcohol injectors 20 in the methanol rail 10 respectively, and the intake manifold alcohol injectors 20 respectively inject methanol fuel into the corresponding combustion chambers 103. At the same time, the central control unit 4 sends a signal to start the first electric pump 121, and the bypass end of the fourth electronically controlled three-way valve 114 is turned on. The methanol fuel circulates back to the primary heating unit 21 through the methanol rail 10 as indicated by the right-angle arrow at the bypass end of the fourth electronically controlled three-way valve 114. After multiple cycles, the cold start of the marine pure methanol engine is completed. The central control unit 4 sends a signal to close the first electric pump 121, the second electric pump 122, the first electric-controlled three-way valve 111, the third electric-controlled three-way valve 123 and the fourth electric-controlled three-way valve 124 respectively, and turns on the electric-controlled two-way valve 22. The methanol fuel in the primary heating unit 21 returns to the methanol fuel tank 3 through the methanol discharge port 214 and the electric-controlled two-way valve 22. After the methanol fuel in the primary heating unit 21 is emptied, the central control unit 4 sends a signal to close the electric-controlled two-way valve 22, and enters the next step to start the conventional preheating circulation loop 1.

[0034] 4) If Figure 2 As shown, the central control unit 4 sends a signal, and the first electric-controlled three-way valve 111 through-end, the third electric-controlled three-way valve 113 through-end and the fourth electric-controlled three-way valve 114 through-end of the cold-start preheating circulation loop 2 are electrically connected, and then the first electric pump 121 is electrically started, and the methanol fuel in the methanol fuel tank 3 enters the methanol rail 10 in the direction indicated by the straight arrow through the second filter 132, the third electric-controlled three-way valve 113 through-end, the secondary heating unit 1, the first electric-controlled three-way valve 111 through-end, the first electric pump 121, the first filter 131 and the pressure regulating valve 14, and the central control unit 4 sends a signal to start the intake manifold alcohol injector 20 in the methanol rail 4 respectively, and the intake manifold alcohol injector 20 injects methanol fuel to the corresponding combustion chamber 103 to complete injection combustion. The methanol fuel in the methanol rail 10 returns to the methanol fuel tank 3 through the fourth electric-controlled three-way valve 114 through-end.

[0035] 5) The first temperature sensor 61 feeds back the actual methanol fuel temperature flowing through the secondary heating unit 1 to the central control unit 4, and the central control unit 4 sends a signal to adjust the opening of the bypass end of the second electric-controlled three-way valve 112, thereby adjusting the flow of high-temperature exhaust gas at 60-110°C entering the secondary heating unit 11 through the exhaust manifold 50. The high-temperature exhaust gas enters the secondary heating unit 21 from the exhaust gas input port 11 of the secondary heating unit as indicated by the right-angle arrow in the second electric-controlled three-way valve 112, passes through the secondary heating unit 21 vertically, and then enters the exhaust manifold 50 from the exhaust gas output port 118 of the secondary heating unit to be discharged, and the methanol fuel in the secondary heating unit 11 is preheated by the high-temperature exhaust gas. During the operation of the marine pure methanol engine, the conventional preheating circulation loop 1 is always in working condition.

[0036] In addition to the above-mentioned embodiments, the present invention may also have other implementation modes. Any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A fuel preheating system for a pure methanol engine for a ship, wherein an intake manifold of a methanol rail of the pure methanol engine for a ship is provided with an intake manifold alcohol injector, a methanol rail voltage stabilizer is provided at one end of the methanol rail, an intake manifold is connected to one end of the intake manifold, and the other end of the intake manifold is communicated with an exhaust manifold; characterized in that: It includes a conventional preheating circulation loop and a cold start preheating circulation loop, wherein the conventional preheating circulation loop includes a secondary heating unit, a first electrically controlled three-way valve, a second electrically controlled three-way valve, a first electric pump, a first filter and a pressure regulating valve, and the cold start preheating circulation loop includes a primary heating unit, a second filter, a third electrically controlled three-way valve, a fourth electrically controlled three-way valve, an electrically controlled two-way valve and a second electric pump; in the conventional preheating circulation loop, a connecting pipe connected to a methanol fuel tank is connected to a fuel input port of the secondary heating unit through a second filter and a straight-through end of a third electrically controlled three-way valve in sequence, a methanol output port of the secondary heating unit is connected to a straight-through end of the first electrically controlled three-way valve, a first electric pump, a first filter, a pressure regulating valve and one end of a methanol rail through a connecting pipe, one end of an exhaust manifold is connected to an exhaust gas input port of the secondary heating unit through a bypass end of a second electrically controlled three-way valve, and an exhaust gas output port of the secondary heating unit leads to an exhaust port of the exhaust manifold; in the cold start preheating circulation loop, a connecting pipe connected to a methanol fuel tank is connected to a fuel input port of the secondary heating unit through a second filter and a straight-through end of a third electrically controlled three-way valve in sequence, a methanol output port of the secondary heating unit is connected to a straight-through end of a first electrically controlled three-way valve, a first electric pump, a first filter, a pressure regulating valve and one end of a methanol rail in sequence, one end of an exhaust manifold is connected to an exhaust gas input port of the secondary heating unit through a bypass end of a second electrically controlled three-way valve, and an exhaust gas output port of the secondary heating unit leads to an exhaust port of the exhaust manifold; The pipeline is connected to the methanol input port of the primary heating unit through the second filter, the bypass end of the third electrically controlled three-way valve, and the second electric pump in sequence; the methanol output port of the primary heating unit is connected to the first electrically controlled three-way valve bypass port of the conventional preheating circulation loop through a connecting pipeline; the connecting pipeline of the methanol return port of the primary heating unit returns to the methanol fuel tank through the bypass end of the fourth electrically controlled three-way valve, and the connecting pipeline connected to the methanol discharge port of the primary heating unit returns to the methanol fuel tank through the electrically controlled two-way valve; the cooling water pipeline of the marine pure methanol engine is connected to the cooling water input port of the primary heating unit, and the cooling water output port of the primary heating unit returns to the marine pure methanol engine through the cooling water pipeline; the signal lines of the central control unit are respectively connected to the first electric pump control end, the second electric pump control end, the first electrically controlled three-way valve control end, the second electrically controlled three-way valve control end, the third electrically controlled three-way valve control end, the fourth electrically controlled three-way valve control end, the electrically controlled two-way valve control end, the primary heating unit control end, and the secondary heating unit control end.

2. The marine pure methanol engine fuel preheating system according to claim 1, characterized in that: The pressure sensor is connected in parallel to the connection between the pressure regulating valve and the methanol rail, the first temperature sensor is connected in parallel to the connecting pipe of the methanol output end of the secondary heating unit, and the second temperature sensor is connected in parallel to the connecting pipe between the methanol output port of the primary heating unit and the bypass end of the first electrically controlled three-way valve.

3. The marine pure methanol engine fuel preheating system according to claim 1, characterized in that: The primary heating unit is a box structure, including a box and several rectangular cooling water channels and multiple ceramic electric heating rods fixed at both ends of the box, wherein the multiple ceramic electric heating rods are located at the lower side of the several rectangular cooling water channels; the connection between the end panel and the box is sealed by a sealing ring, and a water collecting trough closed by a sealing plate is provided on the outside of the connection between the box and the several rectangular cooling water channels, and corresponding cooling water input ports and cooling water output ports are provided on the sealing plates fixed on the outside of the water collecting trough, respectively, and the methanol output port and the methanol return oil port are respectively arranged at the two ends of the box, and the methanol input port and the methanol discharge port arranged side by side are located on the same side of the box as the cooling water output port.

4. The marine pure methanol engine fuel preheating system according to claim 1, characterized in that: The secondary heating unit is a cylindrical structure, including a shell, a lower end cover, an upper inner oil accumulation end cover, a lower inner oil accumulation end cover, multiple methanol delivery pipes and 2 asbestos heat-resistant sealing rings, the two ends of the multiple vertically evenly arranged methanol delivery pipes are respectively fixedly welded to the upper inner oil accumulation end cover and the lower inner oil accumulation end cover, the upper inner oil accumulation end cover is embedded in the bottom end of the inverted shell; the lower inner oil accumulation end cover is embedded in the lower end cover, located between the upper inner oil accumulation end cover and the bottom end of the shell, and the lower inner oil accumulation end cover and the lower end cover are respectively sealed by asbestos heat-resistant sealing rings; the fuel output port of the secondary heating unit located in the center of the upper inner oil accumulation end cover extends upward from the top of the shell, and the methanol output port of the secondary heating unit located in the center of the lower inner oil accumulation end cover extends downward from the lower end cover; the exhaust gas input port of the secondary heating unit is vertically connected to the upper end of one side of the shell, and the exhaust gas output port of the secondary heating unit is vertically connected to the lower end of the other side of the shell.

5. The marine pure methanol engine fuel preheating system according to claim 1, characterized in that: The first temperature sensor and the second temperature sensor are both PT1000, and the temperature range is: -50℃~+200℃; the pressure range of the pressure sensor is: 0~1.6Mpa; the pressure range of the first electric pump and the second electric pump is: 0.2~1.0Mpa, flow rate: 20m 3 / h; the filtration accuracy of the first filter is ≤10μm; the filtration accuracy of the second filter is ≤12μm.

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