A lost foam casting waste gas oxidation combustion treatment purifier

Abstract

The invention discloses a waste gas oxidation combustion treatment purifier for lost foam casting, which belongs to the field of lost foam casting. An air intake chamber, a mixing chamber, a combustion chamber, a burner and a discharge port are arranged in a shell; the air intake chamber, the mixing chamber, the combustion chamber and the discharge port are connected in sequence, the mixing chamber is a volute spiral air intake channel, a circular metal mesh is arranged in the combustion chamber, and a conical flame reflection device is arranged in the center of the metal mesh. The purifier has a simple structure, low investment, high purification rate, and the waste gas purification efficiency reaches more than 99%, and the emission reaches the standard. The odor emitted by the water ring vacuum pump in the lost foam casting workshop is eliminated, and the tail gas emission problem in the lost foam casting process is solved.

Description

Technical Field

[0001] The invention relates to the field of lost foam casting, and in particular to a lost foam casting waste gas treatment purifier. Background Art

[0002] Lost foam casting is a method of using foam plastic (EPS, STMMA or EPMMA) polymer material to make a solid mold with the same structure and size as the part to be cast. After being dipped in refractory coating (for strengthening, smoothing and breathability) and dried, it is buried in dry quartz sand and subjected to three-dimensional vibration molding. The molten metal is poured into the casting sand box under negative pressure, so that the polymer material model is heated, vaporized and extracted, and then replaced by liquid metal and cooled and solidified to form a one-time molding new casting process for producing castings.

[0003] Since the lost foam casting process was applied to industrial production, the impact of toxic and harmful waste gases produced by thermal decomposition of foam materials on the environment has always attracted the attention of people and environmental protection departments. In lost foam casting, harmful gases are generated due to the vaporization of EPS or STMMA when casting and pouring metal liquid. These polymer raw materials are materials made of copolymers of styrene and methyl methacrylate. The waste gas generated by lost foam casting is mainly discharged at the vacuum pump outlet, and the harmful gases generated in other processes are relatively small. The main harmful gases in the vacuum pump exhaust pipe are benzene series. There are currently four ways to treat these waste gases emitted by lost foam casting: (1) Absorption treatment. When the absorbent is used to a certain extent, it needs to be treated and regenerated before use. Therefore, the absorption method requires a relatively complex process and may cause secondary pollution if not handled properly. Commonly used absorption equipment includes packed towers, turbulent ball towers, plate towers, spray towers, Venturi absorbers, etc. When the absorbent is used to a certain extent, it needs to be treated before use, which increases the cost of use. (2) Adsorption treatment: the adsorbent also needs to be regenerated before use. The regeneration process will cause secondary pollution to the environment. In addition, the equipment cost is high and the frequency of use is low, resulting in a waste of resources. (3) Gas thermal combustion purification: due to the large variations in the waste gas flow and the concentration of combustible gases generated during the pouring process of lost foam casting, it is easy to cause detonation, explosion and incomplete combustion purification, causing danger and secondary emission pollution. (4) Catalytic combustion treatment: the concentration of waste gas is unstable and fluctuates greatly. At the same time, it is impossible to ensure a constant temperature in the catalytic combustion chamber, resulting in incomplete waste gas treatment. The sudden increase in the concentration of combustible gas during pouring will cause detonation, which can easily cause equipment damage and high equipment investment costs.

[0004] In waste gas treatment, due to the particularity of lost foam casting, the existing treatment and purification methods are not suitable for use in the field of lost foam casting. The main manifestation is that the basic interval of lost foam casting is about 1 hour, the pouring time is generally 2-6 minutes, and the longest will not exceed 10 minutes. The waste gas treatment device adopts absorption and adsorption methods. Although it is suitable for intermittent work, the cost of use is high and it is not suitable for the low value-added casting industry; the catalytic combustion treatment device has a large investment and requires preheating, which is not suitable for intermittent short-term work. Gas thermal combustion net treatment, due to the unstable amount and concentration of waste gas generated during the pouring of lost foam casting, general combustion is prone to cause accidents such as detonation and explosion, and the unstable gas volume causes incomplete combustion of waste gas, which affects the failure of environmental protection detection. Therefore, a special equipment for the treatment of waste gas generated in the field of lost foam casting is needed. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a purifier for oxidative combustion treatment of combustible lost foam casting waste gas which has a simple structure, low price and good purification effect.

[0006] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0007] A lost foam casting waste gas oxidation combustion treatment purifier, comprising a shell, wherein an air inlet chamber, a mixing chamber, a combustion chamber, a burner and an exhaust port are arranged in the shell; the mixing chamber is arranged on the outside of the shell, the mixing chamber comprises an air inlet end and an air outlet end, the air inlet end is connected to the air inlet chamber; the air outlet end is connected to the combustion chamber, and the burner is connected to the combustion chamber; the end of the combustion chamber is connected to the air outlet; the exhaust port is arranged on the top of the shell;

[0008] The mixing chamber is a volute spiral air inlet passage, and a blade group is provided on the air inlet passage; the center of the mixing chamber is connected to the combustion chamber;

[0009] The air inlet chamber includes an air inlet pipe and a fan, the air inlet pipe is connected to the inlet of the air inlet channel; a pressure sensor is provided at the air inlet pipe; the flow area of ​​the air inlet pipe is smaller than the flow area of ​​the air inlet channel; the fan is arranged at the inlet of the air inlet channel and delivers air into the air inlet channel;

[0010] A circular metal mesh is provided in the combustion chamber, and a conical flame reflection device is provided at the center of the metal mesh; the diameter of the metal mesh is the same as the inner diameter of the combustion chamber;

[0011] The side of the shell is provided with a ventilating opening;

[0012] A water storage layer is arranged on the inner wall of the shell, and a water inlet and a water outlet are arranged on the water storage layer.

[0013] Furthermore, the burner is fixed to the air inlet end of the mixing chamber and passes through the mixing chamber to be in contact with the combustion chamber.

[0014] Furthermore, there are multiple blade groups and they are evenly distributed on the air inlet channel along the air inlet direction; each blade group is provided with 3-5 evenly distributed blades, and the angle between the blades and the wind direction is 4.5°.

[0015] Preferably, the blade groups are preferably 4 groups, and the blades are nickel-chromium alloy blades, with an angle of 4.5 degrees, and the interval between two adjacent blades is 15 mm and evenly distributed on the central axis of the mixer.

[0016] Furthermore, two ends of the blade are fixed on both sides of the air inlet channel, and the blade can rotate freely under the action of wind force.

[0017] Furthermore, the burner is connected to the center of the mixing chamber and delivers flame into the combustion chamber.

[0018] Furthermore, the metal mesh has at least two layers, and the metal mesh is a tungsten alloy mesh.

[0019] Furthermore, the mesh diameter of the metal mesh is 2 mm, and the thickness of the metal mesh is 3 mm.

[0020] Furthermore, the vent is a positive pressure vent and is arranged above the combustion chamber.

[0021] Furthermore, an exhaust fan is provided in the shell, and the exhaust fan is arranged above the combustion chamber and connected to the exhaust port.

[0022] Furthermore, it also includes a PLC control system, the pressure sensor is connected to the PLC control system signal; the burner, fan, and exhaust fan are respectively connected to the PLC control system for driving control.

[0023] The lost foam casting waste gas oxidation combustion treatment purifier of the present invention has the following beneficial effects:

[0024] (1) The volute spiral mixer can fully mix the exhaust gas and air (oxygen) before the combustion chamber, and the mixer is equipped with blades to further fully mix the incoming exhaust gas and air (oxygen) to ensure sufficient subsequent combustion. At the same time, the fan uses a pressure sensor to send a signal to the PLC control system, which automatically adjusts the fan's air supply according to the amount of incoming exhaust gas.

[0025] (2) There are two layers of tungsten alloy mesh in the combustion chamber, and a flame reflection device 403 is installed in the center of the tungsten alloy mesh. After the flame of the burning petroleum gas or natural gas in the burner is sprayed onto the flame reflection device 403, the flame reflection device 403 expands to cover the entire mesh surface in all directions to prevent the exhaust gas that is not completely burned from overflowing. The burner burns the first layer of tungsten alloy mesh to a red temperature of 800-900℃ within 30 seconds. After the exhaust gas is fully burned, it is discharged from the combustion chamber through the mesh holes of the tungsten alloy mesh. The combustion is fast, full and thorough, saving energy consumption and purifying the environment.

[0026] (3) The air intake volume and the combustion volume of the burner are controlled by the PLC control system to achieve precise control, avoid energy waste, and be environmentally friendly. A water tank is installed outside the combustion chamber to make full use of waste heat and make rational use of resources.

[0027] (4) The purifier has a simple structure, low investment, high purification rate, and exhaust gas purification efficiency of more than 99%, and has achieved standard emission. It eliminates the odor emitted by the water ring vacuum pump in the lost foam casting workshop and solves the problem of tail gas emission in the lost foam casting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 It is a schematic diagram of the structure of the present invention;

[0030] Figure 2 It is a schematic diagram of the structure inside the housing of the present invention;

[0031] Figure 3 It is a side schematic diagram of the present invention;

[0032] 1 shell, 2 mixing chamber, 3 combustion chamber, 4 burner, 5 discharge port, 6 fan, 7 air inlet pipe, 8 positive pressure vent, 9 water storage layer, 10 water inlet, 11 water outlet;

[0033] 201 air inlet end, 202 air outlet end, 203 volute spiral air inlet channel, 204 blade group, 205 blade

[0034] 301 air outlet;

[0035] 401 a first layer of tungsten alloy mesh, 402 a second layer of tungsten alloy mesh, 403 a flame reflection device 403 . DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0037] A lost foam casting waste gas oxidation combustion treatment purifier, such as Figure 1-3 As shown, it includes a shell 1, and an air inlet chamber, a mixing chamber 2, a combustion chamber 3, a burner 4 and an exhaust port 5 are arranged in the shell 1; the mixing chamber 2 is arranged on the outside of the shell 1, and the mixing chamber 2 includes an air inlet end 201 and an air outlet end 202, the air inlet end 201 is connected to the air inlet chamber; the air outlet end 202 is connected to the combustion chamber 3, and the burner 4 is connected to the combustion chamber 3; the end of the combustion chamber 3 is connected to the air outlet 301; the exhaust port 5 is arranged on the top of the shell 1;

[0038] The mixing chamber 2 is a volute spiral air inlet channel 203, and a blade group 204 is provided on the air inlet channel 203; the center of the mixing chamber 2 is connected to the combustion chamber 3;

[0039] The air inlet chamber includes an air inlet pipe 7 and a fan 6, the air inlet pipe 7 is connected to the inlet of the air inlet channel 203; a pressure sensor is provided at the air inlet pipe 7; the flow area of ​​the air inlet pipe 7 is smaller than the flow area of ​​the air inlet channel 203; the fan 6 is arranged at the inlet of the air inlet channel 203 and delivers air into the air inlet channel 203;

[0040] A circular metal mesh is provided in the combustion chamber 3, and a conical flame reflection device 403 is provided at the center of the metal mesh; the diameter of the metal mesh is the same as the inner diameter of the combustion chamber 3;

[0041] The housing 1 is provided with a vent on its side;

[0042] A water storage layer 9 is disposed on the inner wall of the shell 1 , and a water inlet 10 and a water outlet 11 are disposed on the water storage layer 9 .

[0043] In this embodiment, the mixing chamber 2 is a volute spiral air inlet channel 203, and a blade group 204 is provided on the air inlet channel 203. The fan 6 provided at the air inlet end 201 of the mixer adopts a medium-pressure fan of a servo motor, and the air is supplied into the volute spiral air inlet channel 203. The air volume is sent to the PLC control system by the pressure sensor signal at the air inlet pipe 7 of the air inlet chamber, and the air volume of the fan 6 is automatically adjusted according to the amount of exhaust gas entering. Four groups of blade groups 204 are provided in the mixing chamber 2. Each blade group 204 is provided with 3-5 evenly distributed cast circular nickel-chromium alloy blades 205, the blades 205 are 4.5 degrees, and the interval between two adjacent blades 205 is 15mm, and they are evenly distributed on the air inlet channel 203. The two ends of the blades 205 can be rotatably fixed on both sides of the air inlet channel 203; due to the inclination, the nickel-chromium alloy blades 205 of the first and second groups can rotate freely under the action of wind force on the central axis, stirring the combustible exhaust gas and the oxygen in the air to fully mix again, and the mixed gas enters the combustion chamber 3 from the spiral outlet end 202 (annular flat mouth). The burner 4 is connected to the center of the mixing chamber 2 and sends the flame into the combustion chamber 3.

[0044] In this embodiment, the combustion chamber 3 wall is cast with nickel-chromium alloy, and two layers of 3mm thick circular tungsten alloy mesh are arranged inside, the mesh diameter is 2mm, and the thickness of the tungsten alloy mesh is 3mm. A conical flame reflection device 403 is designed in the middle part of the tungsten alloy mesh, and the top of the cone is protruding toward the burner 4. After the flame of 300,000 kcal of petroleum gas or natural gas burning in the burner 4 is sprayed into the combustion chamber 3, the flame is sprayed onto the flame reflection device 403, and then the flame reflection device 403 expands to cover the entire mesh surface of the tungsten alloy mesh in all directions to prevent the exhaust gas that is not completely burned from overflowing. The burner 4 burns the first layer of tungsten alloy mesh 401 to a red temperature of 800-900℃ within 30 seconds, and then burns the second layer of tungsten alloy mesh 402 red by transmission. After the first layer of tungsten alloy mesh 401 of the exhaust gas is burned, it enters the second layer of tungsten alloy mesh 402 and burns again, making the combustion more complete and thorough. The combusted gas is discharged from the combustion chamber 3 through the mesh holes in the tungsten alloy mesh, comes out from the gas outlet 301 and is distributed in the shell 1, and then is discharged through the exhaust port on the top of the shell 1.

[0045] In this embodiment, the burner 4 is fixed at the air inlet end 201 of the mixing chamber 2 and passes through the mixing chamber 2 to contact and connect with the combustion chamber 3. The burner 4 is 300,000-600,000 kcal, and the gas is liquefied petroleum gas or natural gas. The electronic control system uses Siemens program control, electronic proportional adjustment, and the air volume and gas volume use servo motor control to accurately match the air-fuel ratio. The flame monitoring uses an ion probe, which has power failure, low gas pressure, low air pressure, gas leakage monitoring, and flameout secondary ignition functions. It is equipped with a special UV ultraviolet electronic eye detection module to fully monitor the overall operating status, and has the characteristics of safety and efficiency.

[0046] In this embodiment, the vent is a positive pressure vent 8, and is arranged above the combustion chamber 3. An exhaust fan is arranged in the housing 1, and the exhaust fan is arranged above the combustion chamber 3 and connected to the exhaust port 5. In order to ensure that the combustion chamber 3 can fully burn, the temperature change must be controlled at 800-900°C, so a slightly negative pressure design is adopted, and a positive pressure vent 8 is opened on the housing 1. The exhaust fan is designed according to the maximum exhaust volume during lost foam casting. During lost foam casting, the exhaust gas exhaust volume generated by the different volumes and masses of EPS foam can be freely adjusted.

[0047] In this embodiment, a PLC control system is also included, and the pressure sensor is connected to the PLC control system signal; the burner 4, the fan 6, and the exhaust fan are respectively connected to the PLC control system for driving control. The air intake of the fan 6, the pressure of the burner 4, the oil supply, and the exhaust volume of the exhaust fan are regulated in real time by the air intake of the exhaust gas, so that the whole equipment is balanced.

[0048] In this embodiment, a water storage layer 9 is also provided on the inner wall of the shell 1, and a water inlet 10 and a water outlet 11 are provided on the water storage layer 9. The waste heat generated by the combustion of the exhaust gas is used to heat the water in the water storage layer 9, and the hot water can be used for domestic water or part of industrial water, saving energy consumption.

[0049] Purification effect after oxidation combustion using the purifier 7 of the present invention: During the oxidation combustion process, the inlet end 201 and the exhaust port 5 are sampled with a syringe, and then gas chromatography analysis is performed. The concentration detection results before and after the exhaust gas purification treatment are statistically shown in Table 1.

[0050] Table 1: Results of exhaust gas concentration test after combustion and purification treatment

[0051]

[0052] After multiple tests, the exhaust gas concentration after purification reached the following indicators: benzene <10mg / m 3 , toluene <1mg / m 3 , styrene <3mg / m 3 The environmental standard (T J36-79) stipulates that the emission standard of waste gas is: benzene <40mg / m 3 , toluene <100mg / m3, styrene <40mg / m3.

[0053] The test results show that the exhaust gas purification efficiency has reached more than 99%, and the emission has reached the standard. The odor emitted by the water ring vacuum pump in the lost foam casting workshop has been eliminated, and the exhaust gas emission problem in the lost foam casting process has been solved.

[0054] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A lost foam casting waste gas oxidation combustion treatment purifier, characterized in that: The invention comprises a shell, wherein an air inlet chamber, a mixing chamber, a combustion chamber, a burner and an exhaust port are arranged in the shell; the mixing chamber is arranged outside the shell, the mixing chamber comprises an air inlet end and an air outlet end, the air inlet end is connected to the air inlet chamber; the air outlet end is connected to the combustion chamber, and the burner is connected to the combustion chamber; the end of the combustion chamber is connected to the air outlet; the exhaust port is arranged at the top of the shell; The mixing chamber is a volute spiral air inlet passage, and a blade group is provided on the air inlet passage; the center of the mixing chamber is connected to the combustion chamber; The air inlet chamber includes an air inlet pipe and a fan, the air inlet pipe is connected to the inlet of the air inlet channel; a pressure sensor is provided at the air inlet pipe; the flow area of ​​the air inlet pipe is smaller than the flow area of ​​the air inlet channel; the fan is arranged at the inlet of the air inlet channel and delivers air into the air inlet channel; A circular metal mesh is provided in the combustion chamber, and a conical flame reflection device is provided at the center of the metal mesh; the diameter of the metal mesh is the same as the inner diameter of the combustion chamber; The side of the shell is provided with a ventilating opening; A water storage layer is arranged on the inner wall of the shell, and a water inlet and a water outlet are arranged on the water storage layer.

2. According to claim 1, the lost foam casting waste gas oxidation combustion treatment purifier is characterized in that: The burner is fixed at the air inlet end of the mixing chamber and passes through the mixing chamber to be in contact with the combustion chamber.

3. According to claim 1, the lost foam casting waste gas oxidation combustion treatment purifier is characterized in that: There are multiple blade groups and they are evenly distributed on the air inlet channel along the air inlet direction; each blade group is provided with 3-5 evenly distributed blades, and the angle between the blades and the wind direction is 4.5°.

4. According to claim 3, the lost foam casting waste gas oxidation combustion treatment purifier is characterized in that: The two ends of the blade are fixed on the two sides of the air inlet channel, and the blade can rotate freely under the action of wind force.

5. The lost foam casting waste gas oxidation combustion treatment purifier according to claim 1, characterized in that: The burner is connected to the center of the mixing chamber and delivers flame into the combustion chamber.

6. The lost foam casting waste gas oxidation combustion treatment purifier according to claim 1, characterized in that: The metal mesh has at least two layers, and the metal mesh is a tungsten alloy mesh.

7. The lost foam casting waste gas oxidation combustion treatment purifier according to claim 1, characterized in that: The mesh diameter of the metal mesh is 2 mm, and the thickness of the metal mesh is 3 mm.

8. The lost foam casting waste gas oxidation combustion treatment purifier according to claim 1, characterized in that: The vent is a positive pressure vent and is arranged above the combustion chamber.

9. The lost foam casting waste gas oxidation combustion treatment purifier according to claim 1, characterized in that: An exhaust fan is arranged in the shell, and the exhaust fan is arranged above the combustion chamber and connected to the exhaust port.

10. The lost foam casting waste gas oxidation combustion treatment purifier according to claim 1, characterized in that: It also includes a PLC control system, and the pressure sensor is connected to the PLC control system signal; the burner, fan, and exhaust fan are respectively connected to the PLC control system for driving control.

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