CN105569883B

CN105569883B - Methanol cracking reactor utilizing engine waste heat

Info

Publication number: CN105569883B
Application number: CN201510967499.8A
Authority: CN
Inventors: 蒋炎坤; 张浩浩; 王容
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2015-12-18
Filing date: 2015-12-18
Publication date: 2021-12-17
Anticipated expiration: 2035-12-18
Also published as: CN105569883A

Abstract

The invention discloses a methanol cracking reactor utilizing engine waste heat. The device utilizes the waste heat of engine exhaust to heat methanol to crack it into a mixture of hydrogen and carbon monoxide. After cracking, the mixture is passed into the combustion chamber of the engine for combustion. The methanol cracker includes a shell, a methanol pipe, a heat exchange pipe, a cracked gas outlet, and the like. The outer shell of the reactor is wrapped with insulating ceramic wool, and the inner shell and the outer shell of the reactor are supported by steel pipes; methanol enters the cracking chamber through the methanol pipe, and the cracking chamber is filled with catalyst; Flow plate; exhaust gas enters the heat exchange tube from the front vent plate through the exhaust gas inlet to participate in heat exchange. The invention utilizes the waste heat of the exhaust gas discharged by the engine to carry out the methanol cracking hydrogen production reaction, reduces the pollutant discharge of the engine, enhances the utilization of the waste heat of the engine, and improves the energy efficiency of the engine. The device is economical, reliable, and has a long service life, and can be installed in automobiles, ships and other fields.

Description

Methanol cracking reactor utilizing engine waste heat

Technical Field

The invention relates to a methanol cracking reactor utilizing engine waste heat, and belongs to the field of engine waste heat utilization.

Background

The methanol is an oxygen-rich, environment-friendly and high-energy fuel, and the physical property of the methanol determines that the methanol exists in a liquid state at normal temperature and normal pressure. Compared with gasoline, methanol has high H/C and octane number, wide lean combustion range, high compression ratio and high efficiency. The methanol molecule contains 50% of oxygen, the combustion speed is high, the methanol molecule contains oxygen to support combustion, the combustion is sufficient, the heat efficiency can be improved, and the purification in the machine and the reduction of the emission of conventional gases such as CO, HC, NOx and the like can be realized. The production raw materials are wide and rich (such as inferior coal, coke oven gas, domestic production waste and the like), which is beneficial to the further popularization and application of the methanol fuel. China has a history of nearly forty years for research and test on methanol fuel to replace gasoline, and is applied in large scale in partial areas at present, so that economic benefits and social benefits are obtained. However, the current methanol used as a direct automobile alternative fuel can cause serious problems, such as low heat value, easy corrosion to engines, poor lubricity, and various toxic pollutants contained in exhaust gas, which prevent the further application of the methanol fuel. Due to the consideration of energy conservation and emission reduction, the defects of methanol as a direct alternative fuel are overcome by cracking the methanol into hydrogen and carbon monoxide and then burning the hydrogen and the carbon monoxide in an engine cylinder. The methanol cracking gas contains rich hydrogen, has the characteristic of hydrogen combustion, and can realize thin and quick combustion, thereby improving the thermal efficiency of the engine, greatly reducing harmful emissions and improving the dynamic property and the economical efficiency of the engine. Research shows that the fuel economy of the gasoline engine after hydrogen-doped combustion is improved by 30 percent, the combustion rate of the mixed gas can be improved by using gasoline/hydrogen mixed gas when the gasoline engine is partially loaded, and pure gasoline is used to ensure power output when the gasoline engine is loaded at high load; after the diesel engine is doped with hydrogen, the ignition and combustion-retarding period is shortened, the combustion can be completed near the top dead center, and the ignition and combustion-retarding period is not greatly influenced by the oxygen content in the mixed gas, so that conditions are created for reducing the emission of nitrogen oxides by adopting exhaust gas recirculation. The methanol cracking gas can provide hydrogen energy, namely the cleanest and environment-friendly fuel for automobiles. Meanwhile, in the aspect of hydrogen energy utilization, the problems of inconvenience in hydrogen storage, low safety coefficient and the like are solved by methanol cracking, and the application prospect is good. More preferably, the methanol low-temperature cracking catalyst has breakthrough development, and methanol can be completely cracked at a lower temperature by using a special catalyst, so that the technical route of cracking methanol to produce hydrogen by absorbing the waste heat of the tail gas of the automobile and using the methanol as the fuel of the internal combustion engine is technically supported.

The recovery and utilization of the waste heat of the engine are one of the development directions of the future automobile technology. In the existing engine waste heat recycling technology, in order to take the heat exchange effect and the shell strength of the reactor into consideration, a special material structure is adopted, so that the risk of air leakage at a welding seam is greatly increased; in some technical schemes, a heat exchange tube is filled with a catalyst, the catalyst loading capacity is small, and catalyst particles are easily washed away because methanol enters the tube and is in a liquid state; some technical schemes adopt an electric heating plug for auxiliary heating, so that the heat exchange of the reactor is enhanced, the reactor is easily heated unevenly, and the difficulty of controlling the reaction temperature is increased.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides the methanol cracking reactor which has compact structure, convenient disassembly, economy, reliability, high energy efficiency and low emission by utilizing the waste heat of the engine.

The invention provides a methanol cracking reactor utilizing waste heat of an engine, which comprises a shell, a methanol pipe, a heat exchange pipe and a cracked gas outlet, and is characterized in that:

the shell comprises an inner shell, an outer shell, a catalyst filling port, an exhaust gas inlet and an exhaust gas outlet, wherein the catalyst filling port, the exhaust gas inlet and the exhaust gas outlet penetrate through the outer shell and are communicated with the cavity of the inner shell; the catalyst filling port is used for filling the catalyst into the inner shell cavity; the waste gas inlet and the waste gas outlet are positioned at two ends of the shell and are used for inputting and discharging waste gas of the engine;

the methanol pipe extends from one end of the cavity of the inner shell, which is close to the waste gas inlet, to the other end, penetrates through the outer shell and is led out for inputting methanol steam, and one end of the methanol pipe, which is close to the waste gas inlet, is provided with a plurality of small holes for supplying the methanol steam to the inner cavity of the inner shell;

the heat exchange tube is axially arranged in the inner cavity of the inner shell, one end of the heat exchange tube is communicated with the waste gas inlet through a first vent hole plate, and the other end of the heat exchange tube is communicated with the waste gas outlet through a second vent hole plate;

the pyrolysis gas outlet is arranged at the other end opposite to the catalyst filling port and used for outputting pyrolysis gas to the outside.

Further, the inner cavity of the shell of the methanol cracking reactor is vertical to the direction of the heat exchange tube, and is provided with a plurality of baffle plates, and the baffle plates are provided with openings corresponding to the heat exchange tube; the baffle plate partially partitions the inner cavity and forms a bent S-shaped gas channel with the inner cavity, so that the catalyst and the methanol steam are mixed more uniformly.

Furthermore, a plurality of heat exchange tubes are arranged in the inner shell of the methanol cracking reactor, and all the heat exchange tubes are uniformly arranged in the radial cross section direction.

Furthermore, a heat exchange tube, an inner shell and a vent hole plate of the methanol cracking reactor are all made of copper materials.

Furthermore, a bypass pipe is arranged at a waste gas inlet of the methanol cracking reactor, and when the temperature of an inner shell of the cracking reactor is too high, a bypass valve is automatically opened, so that the waste gas input into an inner cavity of the shell is reduced.

Furthermore, a thermocouple temperature measuring port is formed in a shell of the methanol cracking reactor and used for inserting a thermocouple.

Further, an inner shell and an outer shell of the methanol cracking reactor are both cylindrical, the inner shell is vacuumized, and the outer shell is wrapped by heat-insulating ceramic wool.

Further, the support body between the inner shell and the outer shell of the methanol cracking reactor is a steel pipe.

Generally, compared with the prior art, the technical scheme of the invention has the following advantages:

1. the waste heat of the tail gas discharged by the engine is utilized to carry out the hydrogen production reaction by cracking the methanol, thereby reducing the energy waste of the waste heat of the engine and improving the energy utilization efficiency.

2. The temperature controller is adopted to measure the temperature of the methanol cracking reactor, and the fuel supply of the reactor is intelligently adjusted, so that the cracking hydrogen production reactor can work under the stable temperature condition.

3. The pyrolysis gas obtained by the reaction is mixed with gasoline for combustion, so that the combustion efficiency of the engine can be effectively improved, the pollutant emission of the engine is reduced, and the petroleum fossil fuel is saved.

4. The cracking cavity and the heat exchange cavity are effectively integrated, the structure is compact, the catalyst is conveniently filled, each part is conveniently disassembled, and the device is suitable for being installed on automobiles, ships and the like.

5. The liquid methanol enters the methanol pipe and carries out convection heat exchange with the waste gas, is vaporized into methanol steam, the storage amount of the catalyst in the cracking chamber is large, the middle part of the catalyst is separated by a baffle plate to form an S-shaped gas path, the contact mass transfer reaction area of the methanol steam and the catalyst is large, and the cracking rate is improved.

6. Because the heat exchange tube and the reactor inner shell are made of the same material, the damage to the welding seam caused by thermal stress is reduced; in addition, a layer of shell is added on the periphery of the reactor, and the middle of the shell is supported by a steel pipe, so that the strength of the reactor is greatly increased, and the heat preservation effect is also achieved. Therefore, the methanol cracking device is economical and reliable to use and has long service life.

7. The reactor is provided with a bypass pipe, a bypass valve is arranged in the reactor, and the adverse effect of overhigh temperature of a cracking chamber of the reactor on the cracking efficiency can be effectively reduced by controlling the opening and closing of the valve.

Drawings

FIG. 1 is a partial longitudinal structural sectional view of a methanol cracking reactor of the present invention;

FIG. 2 is a partial cross sectional view of a methanol cracking reactor according to the present invention;

FIG. 3 is a front view of a methanol pipe of the methanol cracking reactor of the present invention;

FIG. 4 is a perspective view of a methanol cracking reactor of the present invention;

the same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:

in the figure: 1-a waste gas inlet flange, 2-a reactor end socket, 3-a front guard ring, 4-a first vent hole plate, 5-a thermocouple temperature measuring port, 6-a heat exchange tube, 7-a catalyst filling port lower flange, 8-a catalyst filling port upper flange, 9-a catalyst filling port, 10-a baffle plate, 11-a pyrolysis gas outlet lower flange, 12-a pyrolysis gas outlet upper flange, 13-a pyrolysis gas outlet, 14-a second vent hole plate, 15-a rear guard ring, 16-a methanol tube, 17-a waste gas outlet, 18-a waste gas outlet flange, 19-a rear waste gas chamber, 20-a support steel tube arrangement space, 21-a reactor outer shell, 22-a pyrolysis chamber, 23-a reactor inner shell, 24-a waste gas inlet and 25-a bypass tube flange, 26-a bypass pipe, 27-a bypass valve, 28-a methanol pipe array small hole and 29-a support steel pipe.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Fig. 1, 2, 3 and 4 are a partial longitudinal structural sectional view, a transverse structural sectional view, a front view and a three-dimensional structural view of a methanol cracking reactor, respectively.

In the embodiment, the waste gas inlet 24 of the methanol cracking reactor is a three-way pipe, a bypass valve is arranged in the bypass pipe 26, when the cracking temperature is lower, the valve 27 is in a closed state, the waste gas of an engine directly enters the cracking chamber 22 through the reactor end socket 2, when the cracking temperature exceeds the optimal temperature, the electric control unit controls the electromagnetic pneumatic valve to open the valve, most of tail gas discharged by the engine is directly discharged through the bypass pipe, the cracking temperature is not increased any more, and meanwhile, the tail gas discharge backpressure is reduced;

in this embodiment, the waste gas inlet is welded to the reactor shell through the end enclosure; the waste gas outlet 17 is welded on the inner shell of the waste gas chamber of the reactor, and the other end of the waste gas chamber is welded on the inner shell 23 of the reactor; the reactor main body inner shell 23 is made of a copper material, the reactor main body outer shell 21 is made of a stainless steel material, and the reactor outer shell is wrapped by heat-insulating ceramic wool to reduce heat dissipation;

the methanol pipe 16 is fixed by welding, one end of the methanol pipe close to the first vent plate 4 is provided with an array small hole 28, the methanol feeding route adopts a mode opposite to the waste gas route, and the other end of the methanol pipe is connected with a methanol storage tank by a methanol delivery pipe through a methanol nozzle and a methanol pump; the heat exchange tube 6 passes through the baffle plate 10 and is welded on a vent hole plate, and the vent hole plate and the baffle plate are provided with a plurality of waste gas circulation holes; the pyrolysis gas outlet pipe is installed in a welding mode and is connected with the pyrolysis gas conveying pipe 13 through connecting

flanges

11 and 12; the thermocouple temperature measuring ports 5 are distributed at the waste gas inlet end, one end of the thermocouple is inserted into the cracking chamber through the temperature measuring ports, and the other end of the thermocouple is connected with the electric control unit through a temperature signal wire; each flange connection part is sealed under the pressure of a fastening bolt and a nut;

the electric control unit is connected with the methanol pump circuit. One end of the methanol pump is connected with the methanol storage tank, and the methanol storage tank are connected through a methanol delivery pipe. When methanol needs to be supplied to the reactor, the electric control unit controls a methanol pump through a circuit, the methanol pump is connected with a methanol nozzle, and the methanol is sprayed into a feeding pipe through the nozzle and then enters a cracking chamber;

the supporting steel pipe 29 is welded on the main body of the reactor inner shell, and the reactor outer shell is tightly wrapped on the outer side of the steel pipe to form a sleeve structure. The vent hole plates are respectively welded at two ends of the inner shell of the reactor main body. The inner shell and the outer shell of the reactor end socket are respectively welded on the inner shell and the outer shell of the reactor main body part, and the inner shell and the outer shell of the waste gas chamber are respectively welded on the inner shell and the outer shell of the reactor.

The catalyst is solid bead-shaped small particles, the whole cracking chamber is filled by the catalyst inlet and is separated from the reactor end enclosure and the waste gas chamber through a vent hole plate, the methanol pipe and the heat exchange pipe are inserted between the catalysts and horizontally arranged in the cracking chamber, and the cracking chamber is vertically separated by the baffle plate to form an S-shaped gas path.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. a methanol cracking reactor utilizing engine waste heat, comprising shell, methanol pipe (16), heat exchange pipe (6) and cracked gas outlet (13), characterized in that:

The casing comprises an inner casing (23), an outer casing (21), a catalyst filling port (9), an exhaust gas inlet (24) and an exhaust gas outlet (17) that pass through the outer casing and communicate with the cavity of the inner casing, the inner casing (23) A support body is arranged between ) and the outer shell (21); the catalyst filling port (9) is used to charge the catalyst into the inner shell cavity, and the exhaust gas inlet (24) and the exhaust gas outlet (17) are located on two sides of the shell. terminal for the input and discharge of engine exhaust gas;

The methanol pipe (16) extends from one end of the inner shell cavity close to the exhaust gas inlet (24) to the other end, and is led out through the outer shell (21). The liquid methanol in the methanol pipe and the exhaust gas undergo convective heat exchange and gasify into methanol vapor, and the methanol vapor enters the inner cavity of the inner shell through the small hole on the methanol pipe near the exhaust gas inlet;

The heat exchange tube is axially arranged in the inner cavity of the inner shell (23), one end of the heat exchange tube is communicated with the exhaust gas inlet (24) through the first ventilation orifice plate (4), and the other end is communicated with the exhaust gas inlet (24) through the second ventilation orifice plate (14). The exhaust gas outlet (17) communicates with each other; the inner cavity of the casing is perpendicular to the direction of the heat exchange tubes, and is provided with a plurality of baffles (10), and the baffles (10) are provided with openings corresponding to the heat exchange tubes. The baffle plate partially blocks the inner cavity of the shell, and cooperates with the inner cavity of the shell to form a curved S-shaped gas path to improve the methanol cracking rate;

The inner shell (23) and the outer shell (21) are both cylindrical, the inner shell (21) is evacuated, and the outer shell (21) is wrapped with heat-insulating ceramic wool; the support body between the inner shell (23) and the outer shell (21) is a support Steel pipe (29); the supporting steel pipe (29) is welded on the main body of the inner casing (23), and the outer casing (21) is tightly wrapped around the outer side of the supporting steel pipe (29) to form a sleeve structure; the first vent plate (4) ) and the second vent plate (14) are welded on both ends of the inner shell (23) respectively; the heat exchange tube (6) and the inner shell (23) are made of the same material to reduce the damage to the weld caused by thermal stress ;

The cracked gas outlet (13) is opened at the other end relative to the catalyst loading port (9) for outputting cracked gas to the outside, and the catalyst loading port (9) is provided at one end of the casing close to the exhaust gas inlet (24), The cracked gas outlet (13) is arranged at one end of the casing close to the exhaust gas outlet (17).

2 . The methanol cracking reactor according to claim 1 , wherein a plurality of heat exchange tubes are provided in the inner shell ( 23 ), and each heat exchange tube is about the center of the inner shell cavity in the radial cross-sectional direction. 3 . Centrally symmetrical arrangement.

3. The methanol cracking reactor according to claim 1 or 2, wherein the heat exchange tube, the inner shell and the vent plate are all made of copper.

4. methanol cracking reactor according to claim 1 and 2, is characterized in that, is provided with bypass pipe (26) at described waste gas inlet (24), when cracking reactor inner shell temperature is too high, bypass The through valve (27) is automatically opened to reduce the exhaust gas entering the inner cavity of the housing.

5. The methanol cracking reactor according to claim 1 or 2, wherein the shell is provided with a thermocouple temperature measurement port (5) for inserting a thermocouple.