A preheating system and device for preparing acetylene from natural gas and application thereof

Abstract

The present application relates to the technical field of natural gas acetylene, disclose a kind of natural gas acetylene preheating system, including oxygen preheating furnace, natural gas preheating furnace, the exhaust pipe of the oxygen preheating furnace is connected with the exhaust pipe of the natural gas preheating furnace, characterized by, the exhaust port of the exhaust pipe of the natural gas preheating furnace is additionally provided with semi-closed component.Acetylene furnace runs stably, thereby avoid the problem that acetylene furnace often appears unplanned shutdown, applicable to different environments, reduce operation, maintenance and repair cost.

Description

Technical Field

[0001] This invention relates to the field of natural gas to acetylene technology, and more specifically to a preheating system for natural gas to acetylene production. Background Technology

[0002] Acetylene is an organic compound with the chemical formula C2H2, commonly known as coal gas or carbide gas. It is the smallest member of the alkyne compounds, a colorless gas at room temperature and pressure, slightly soluble in water, soluble in ethanol, acetone, chloroform, and benzene, and miscible in diethyl ether. It is one of the important raw materials for organic synthesis, and is also a monomer for synthetic rubber, synthetic fibers, and plastics. It can also be used in oxyacetylene welding and cutting.

[0003] There are three industrial methods for producing acetylene from natural gas: partial oxidation, electric arc, and plasma. The partial oxidation method involves pipelines carrying natural gas and oxygen into a controlled environment. After filtration to remove solid impurities such as rust, the two gases are heated separately in a natural gas preheater and an oxygen preheater. The natural gas and oxygen exiting the preheaters then enter a gas mixing section from a cracking reactor. Once uniformly mixed, they flow downwards into the combustion chamber, where partial oxidation of natural gas and methane cracking occur, producing acetylene and other reaction products.

[0004] Chinese patent document CN215102929U discloses a high-efficiency, energy-saving, and environmentally friendly system for the partial oxidation of natural gas to acetylene. This system includes an air preheating system, a natural gas preheating furnace, an oxygen preheating furnace, an acetylene cracking furnace, a scrubbing tower, a carbon black separation system, and a heat exchange system. The air preheating system is connected to both the oxygen and natural gas preheating furnaces and preheats the air entering each furnace. The oxygen and natural gas preheating furnaces are connected to the inlets of the acetylene cracking furnace, and the outlet of the furnace is connected to the scrubbing tower. The carbon black water discharge outlet of the furnace and the scrubbing material discharge outlet of the scrubbing tower are connected to the carbon black separation system, which is also connected to the heat exchange system.

[0005] Chinese patent document CN113444553B discloses an apparatus and method for removing volatile organic compounds from a natural gas-to-acetylene system, such as... Figure 1As shown, the device for removing volatile organic compounds from the natural gas-to-acetylene system includes an oxygen preheater 101, a natural gas preheater 102, and a cooling tower 104, all connected to an acetylene furnace 103. The cooling tower 104 is connected to a dust collector 106. The acetylene furnace 103, cooling tower 104, and dust collector 106 are all connected to a closed-loop separation tank 107. The closed-loop separation tank 107 includes a top-sealed tank body 30, with support legs 9 at the bottom. The side wall of the tank body 30 has a liquid outlet N1 and a liquid outlet pipe 11. The bottom sidewall of the tank 30 is provided with liquid discharge ports N4 and N5, sediment outlet N2 and liquid inlet N3; a baffle is axially arranged inside the tank 30 to divide the inner cavity of the tank 30 into a liquid inlet zone 29 and a carbon black collection zone 28; a flexible scraper 15 is provided at the top of the tank 30 to be in pressure contact with the top of the baffle. The flexible scraper 15 moves in the opposite direction to the flow of carbon black water. The floating carbon black is scraped into the carbon black collection zone 28 by the rotation of the flexible scraper 15. After the carbon black in the carbon black water is separated, the clean water is discharged from the liquid outlet N1.

[0006] Chinese patent document CN114832765A discloses a system and method for producing acetylene and syngas from natural gas. The system includes an acetylene cracking reactor, which comprises a mixer, a reactor, and a furnace body arranged sequentially. A lifting mechanism is installed inside the furnace body, and a quenching ring and a cooling ring are connected to the lifting mechanism, located at the bottom of the reactor. A carbon black water pipeline is connected to the bottom of the furnace body, and the other end of the carbon black water pipeline is connected to a carbon black water clarification tank. A carbon black water circulation pump is connected to the bottom of the carbon black water clarification tank, and the outlet of the carbon black water circulation pump is connected to a cooling water pipeline and a quenching water pipeline. Several coolers are connected to the cooling water pipeline, which is connected to the cooling ring, and the quenching water pipeline is connected to the quenching ring.

[0007] The existing technology has the following shortcomings: the oxygen preheater and the natural gas preheater in the natural gas to acetylene process are connected to the acetylene furnace. The natural gas is cracked and converted into acetylene in the acetylene furnace. In actual use, the oxygen preheater and the natural gas preheater are unstable in operation, and pressure fluctuations will cause the acetylene furnace to frequently experience unplanned shutdowns. Summary of the Invention

[0008] To address the technical problem of unplanned shutdowns of acetylene furnaces, this invention provides a preheating system for acetylene production from natural gas, comprising an oxygen preheating furnace and a natural gas preheating furnace, wherein the exhaust pipe of the oxygen preheating furnace is connected to the exhaust pipe of the natural gas preheating furnace, characterized in that a semi-enclosed component is added to the exhaust port of the exhaust pipe of the natural gas preheating furnace.

[0009] Preferably, the semi-enclosed component includes an isolation cover and a support structure, wherein the support structure supports the isolation cover above the smoke exhaust port, and the space between the isolation cover and the smoke exhaust port is a smoke exhaust channel.

[0010] Preferably, the area of ​​the isolation cover is 10%-15% larger than the area of ​​the smoke exhaust port.

[0011] Preferably, the distance between the isolation cover and the smoke exhaust port is 100-300mm.

[0012] To facilitate smoke extraction, the isolation cover is tilted above the smoke extraction port.

[0013] Preferably, the isolation cover forms an angle of no more than 45° with the horizontal plane of the smoke exhaust port.

[0014] To facilitate flue gas exhaust and reduce pressure fluctuations in both the oxygen preheater and the natural gas preheater, the exhaust pipes of the oxygen preheater and the natural gas preheater are connected to an extended exhaust pipe. The top of the extended exhaust pipe is the exhaust port, and the oxygen preheater and the natural gas preheater share the same exhaust port.

[0015] To facilitate rain protection, the isolation cover adopts an arc-shaped structure, a square structure, or a cone-shaped structure with the opening facing downwards.

[0016] A natural gas partial oxidation device using the preheating system to produce acetylene.

[0017] The preheating system for acetylene production from natural gas is used in the partial oxidation process of natural gas to produce acetylene.

[0018] The present invention has the following beneficial effects: 1. In existing technologies, without the installation of semi-enclosed components, the pressure value in the middle section of the natural gas preheating furnace is around 0 Pa on rainy days. This invention treats the exhaust port of the combined exhaust pipe of the natural gas preheating furnace and the oxygen preheating furnace as semi-enclosed, so that the pressure value in the middle section of the natural gas preheating furnace is stabilized at a relatively high pressure of around 18 Pa on rainy days. It can also increase the pressure value of the upper and lower sections of the natural gas preheating furnace by 20-30 Pa, thereby providing a stable thrust for the combustion of natural gas in the acetylene furnace, ensuring sufficient combustion, stable operation of the acetylene furnace, and completely avoiding the problem of frequent unplanned shutdowns of the acetylene furnace.

[0019] 2. This invention is applicable to different environments, including rainy days, windy days, and foggy days. It can ensure the stable operation of the acetylene furnace. The exhaust port at the junction of the oxygen heater and the natural gas heater is directly connected to the atmosphere, and the exhaust port is protected to effectively prevent rainwater from entering.

[0020] 3. Reduce operating, maintenance and repair costs, avoid unplanned downtime, thereby reducing the number of maintenance and repairs, effectively reducing losses caused by downtime due to malfunctions, and thus significantly reducing long-term maintenance costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a device for removing volatile organic compounds from a natural gas-to-acetylene system, as described in Chinese patent document CN113444553B. Figure 2 This is a schematic diagram of Example 1 of the preheating system for natural gas to acetylene of the present invention; Figure 3 This is a schematic diagram of Example 2 of the preheating system for natural gas to acetylene of the present invention; Figure 4 This is a schematic diagram of Example 3 of the preheating system for natural gas to acetylene of the present invention; Figure 5 This is a schematic diagram of Example 4 of the preheating system for natural gas to acetylene of the present invention. Detailed Implementation

[0022] The following detailed description illustrates the specific implementation method: Semi-closed: This is a state between open and closed. It is characterized by not being completely closed or completely open. It is restricted or constrained in some aspects, but at the same time allows a certain degree of entry, exit, communication or change.

[0023] Those skilled in the art will understand that the process of producing acetylene from natural gas through partial oxidation mainly involves the oxidative cracking reaction of methane: Methane oxidation reaction (exothermic): CH4 + O2 → CO + H2O + H2 Methane thermal decomposition reaction (endothermic): 2CH4 → C2H2 + 3H2 Water-gas shift reaction: CO + H₂O → CO₂ + H₂ Those skilled in the art will understand that the process of producing acetylene from natural gas by partial oxidation mainly includes the following steps: Raw material preheating: Natural gas and oxygen are preheated to about 650°C to ensure that the reaction temperature can be reached quickly in the acetylene furnace; Mixing and reaction: Preheated natural gas and oxygen are rapidly mixed in a certain proportion in the mixing chamber, and then enter the reaction chamber through the burner for oxidation and cracking reaction; Rapid cooling and separation: The reacted gas is rapidly cooled to below 90°C to prevent further decomposition of acetylene. Carbon black is generated during the cooling process, requiring sedimentation, washing, and electrostatic precipitation to obtain dilute acetylene gas. Acetylene enrichment: Dilute acetylene gas contains a certain amount of carbon black and other impurities, requiring enrichment treatment. Commonly used enrichment solvents include N-methylpyrrolidone (NMP) and dimethylformamide (DMF). During the enrichment process, dilute acetylene is mixed with recovered gas and return gas, then compressed and fed into the pre-absorption tower and main absorption tower for absorption and enrichment, ultimately yielding concentrated acetylene gas.

[0024] Those skilled in the art will understand that an oxygen preheating furnace is constructed by sending oxygen at a pressure of 1.5 MPa to the oxygen preheating furnace after impurities have been removed by a filter. The oxygen preheating furnace is preheated to 650°C. A burner is installed at the bottom of the oxygen preheating furnace to burn natural gas to provide the heat required for preheating the oxygen. The temperature of the oxygen at the outlet of the oxygen preheating furnace is controlled by adjusting the flow rate of natural gas (supplying the burner) through an automatic remote control device.

[0025] Those skilled in the art will understand that in a natural gas preheating furnace: natural gas at a pressure of 0.35-0.50 MPa is filtered to remove impurities before entering the natural gas preheater and being preheated to 650°C. A burner is installed at the bottom of the natural gas preheating furnace to burn natural gas and provide the heat required for preheating the natural gas. The temperature of the natural gas at the outlet of the preheating furnace is controlled by adjusting the flow rate of natural gas (supplying to the burner) through an automatic remote control device. After preheating, natural gas and oxygen are sent to the acetylene furnace. The flow rate of natural gas is controlled by a flow controller, and the flow rate of oxygen is adjusted by a proportional regulator, thereby ensuring that the ratio of oxygen to natural gas sent to the acetylene furnace is the set flow ratio.

[0026] Those skilled in the art will understand that an acetylene furnace consists of a mixing chamber, a burner, a reaction chamber cooling device, and a shell. Preheated oxygen and natural gas are rapidly mixed in the mixing chamber and then enter the reaction chamber via the burner, where the mixture is burned at the burner outlet. Additionally, a portion of oxygen is supplied to the acetylene furnace burner (to stabilize the combustion of the natural gas-oxygen mixture). This oxygen is delivered into the reaction chamber through the burner nozzle, and a flow controller maintains a constant flow rate for combustion oxygen. Natural gas undergoes oxidation and thermal decomposition reactions at 1500°C in the reaction chamber, with the following reaction formula: 2CH4→C2H2+3H2 CH4 + 2O2 → CO2 + 2H2O CH4 + 0.5 O2 → CO + 2H2 CO + H₂O → CO₂ + H₂ C2H2→2C+H2 A preheating system for acetylene production from natural gas includes an oxygen preheating furnace and a natural gas preheating furnace. The exhaust pipe of the oxygen preheating furnace is connected to the exhaust pipe of the natural gas preheating furnace. The exhaust port of the exhaust pipe is a semi-enclosed component. The semi-enclosed component includes an isolation cover and a support structure. The support structure supports the isolation cover above the exhaust port. The space between the isolation cover and the exhaust port is an exhaust channel.

[0027] The area of ​​the isolation hood is 10%-15% larger than the area of ​​the smoke exhaust port, preferably 10%, 11%, 12%, 13%, 14% and 15%.

[0028] The distance between the isolation cover and the smoke exhaust port is 100-300mm, preferably 100mm, 200mm and 300mm.

[0029] The isolation cover is tilted and positioned above the smoke exhaust port.

[0030] The isolation cover forms an angle of no more than 45° with the horizontal plane of the smoke exhaust port, preferably 5°, 10°, 20°, 25°, 30°, 40° and 45°.

[0031] The exhaust pipe of the oxygen preheating furnace and the exhaust pipe of the natural gas preheating furnace are connected together by an extended exhaust pipe, the end of which is the exhaust port.

[0032] The isolation cover adopts an arc-shaped structure, a square structure, or a cone-shaped structure with the opening facing downwards.

[0033] The reference numerals in the accompanying drawings include: 1. Oxygen preheater; 2. Natural gas preheater; 3. Acetylene furnace; 4. Exhaust pipe one; 5. Exhaust pipe two; 6. Isolation hood; 7. Support frame; 8. Exhaust port; 9. Exhaust passage; 10. Extension exhaust pipe.

[0034] Example 1 like Figure 2 As shown, a preheating system for acetylene production from natural gas includes an oxygen preheating furnace 1 and a natural gas preheating furnace 2. The exhaust pipe 4 of the oxygen preheating furnace 1 and the exhaust pipe 5 of the natural gas preheating furnace 2 are connected to an extended exhaust pipe 10. The top of the extended exhaust pipe 10 is the exhaust port 8, and the exhaust port 8 is provided with a semi-enclosed component. The oxygen preheating furnace 1 and the natural gas preheating furnace 2 are respectively connected to an acetylene furnace 3.

[0035] The semi-enclosed component includes an isolation cover 6 and a support structure. The support structure consists of three support frames 7, which support the isolation cover 6 above the smoke exhaust port 8. A horizontal smoke exhaust channel 9 is located between the isolation cover 6 and the smoke exhaust port 8.

[0036] The area of ​​the isolation cover 6 is 10% larger than the area of ​​the smoke exhaust outlet 8.

[0037] The distance between the isolation cover 6 and the smoke exhaust port 8 is 100mm.

[0038] The isolation cover 6 is made of PVC material.

[0039] The isolation cover 6 adopts an arc-shaped structure.

[0040] Example 2 like Figure 3As shown, a preheating system for acetylene production from natural gas includes an oxygen preheating furnace 1 and a natural gas preheating furnace 2. The exhaust pipe 4 of the oxygen preheating furnace 1 and the exhaust pipe 5 of the natural gas preheating furnace 2 are connected to an extended exhaust pipe 10. The top of the extended exhaust pipe 10 is the exhaust port 8, which is provided with a semi-enclosed component. The oxygen preheating furnace 1 and the natural gas preheating furnace 2 are respectively connected to an acetylene furnace 3.

[0041] The semi-enclosed component includes an isolation cover 6 and a support structure. The support structure consists of three support frames 7, which support the isolation cover 6 above the smoke exhaust port 8. A horizontal smoke exhaust channel 9 is located between the isolation cover 6 and the smoke exhaust port 8.

[0042] The area of ​​the isolation cover 6 is 10% larger than the area of ​​the smoke exhaust outlet 8.

[0043] The isolation cover 6 is inclinedly disposed above the smoke exhaust port 8, and the isolation cover 6 forms a 30° angle with the horizontal plane of the smoke exhaust port 8.

[0044] The maximum distance between the isolation cover 6 and the smoke exhaust port 8 is 300mm.

[0045] The isolation cover 6 has an arc-shaped structure and is made of PVC material.

[0046] Example 3 like Figure 4 As shown, a preheating system for acetylene production from natural gas includes an oxygen preheating furnace 1 and a natural gas preheating furnace 2. The exhaust pipe 4 of the oxygen preheating furnace 1 and the exhaust pipe 5 of the natural gas preheating furnace 2 are connected to an extended exhaust pipe 10. The top of the extended exhaust pipe 10 is the exhaust port 8, which is provided with a semi-enclosed component. The oxygen preheating furnace 1 and the natural gas preheating furnace 2 are respectively connected to an acetylene furnace 3.

[0047] The semi-enclosed component includes an isolation cover 6 and a support structure. The support structure consists of three support frames 7, which support the isolation cover 6 above the smoke exhaust port 8. A horizontal smoke exhaust channel 9 is located between the isolation cover 6 and the smoke exhaust port 8.

[0048] The area of ​​the isolation cover 6 is 15% larger than the area of ​​the smoke exhaust outlet 8.

[0049] The distance between the isolation cover 6 and the smoke exhaust port 8 is 200mm.

[0050] The isolation cover 6 has a square structure and is made of PVC material.

[0051] Example 4 like Figure 5As shown, a preheating system for acetylene production from natural gas includes an oxygen preheating furnace 1 and a natural gas preheating furnace 2. The exhaust pipe 4 of the oxygen preheating furnace 1 and the exhaust pipe 5 of the natural gas preheating furnace 2 are connected to an extended exhaust pipe 10. The top of the extended exhaust pipe 10 is the exhaust port 8. The exhaust port 8 of the exhaust pipe 5 is provided with a semi-enclosed component.

[0052] The semi-enclosed component includes an isolation cover 6 and a support structure. The support structure consists of three support frames 7, which support the isolation cover 6 above the smoke exhaust port 8. A horizontal smoke exhaust channel 9 is located between the isolation cover 6 and the smoke exhaust port 8.

[0053] The area of ​​the isolation cover 6 is 20% larger than the area of ​​the smoke exhaust outlet 8.

[0054] The distance between the isolation cover 6 and the smoke exhaust port 8 is 150mm.

[0055] The isolation cover 6 adopts a cone-shaped structure with the opening facing downwards, and the isolation cover 6 is made of PVC material.

[0056] Example 5 The natural gas partial oxidation to acetylene apparatus using the preheating system described in Examples 1-4 above.

[0057] Comparative Example 1 A preheating system for acetylene production from natural gas includes an oxygen preheating furnace 1 and a natural gas preheating furnace 2. The exhaust pipe 4 of the oxygen preheating furnace 1 and the exhaust pipe 5 of the natural gas preheating furnace 2 are connected to an extended exhaust pipe 10. The top of the extended exhaust pipe 10 is the exhaust port 8. The oxygen preheating furnace 1 and the natural gas preheating furnace 2 are respectively connected to an acetylene furnace 3.

[0058] The preheating systems in Examples 1-4 and Comparative Example 1 were installed in the natural gas partial oxidation to acetylene unit, and the internal pressures of the oxygen preheater and the natural gas preheater were tested under different environments to obtain the parameters in Table 1.

[0059] Table 1 Examples 1-4 show the pressure values ​​of the upper, middle, and lower sections of a natural gas preheating furnace tested under cloudy or rainy conditions using preheating systems with different types of semi-enclosed components. Comparative Example 1 shows the pressure values ​​of the upper, middle, and lower sections of a natural gas preheating furnace tested under cloudy or rainy conditions using a preheating system without semi-enclosed components. The pressure values ​​of the upper, middle, and lower sections of the natural gas preheating furnace in Examples 1-4 are all higher than those in Comparative Example 1. Examples 1-4 completely avoid unplanned shutdowns of the acetylene furnace, reducing the number of shutdowns to 0. This demonstrates that the present invention can increase the pressure inside the natural gas heating furnace to ensure the supply thrust of natural gas, and significantly improves the number of shutdowns.

[0060] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A preheating system for acetylene production from natural gas, comprising an oxygen preheating furnace and a natural gas preheating furnace, wherein the exhaust pipe of the oxygen preheating furnace is connected to the exhaust pipe of the natural gas preheating furnace, characterized in that, The exhaust port of the exhaust pipe of the natural gas preheating furnace is equipped with a semi-enclosed component.

2. The preheating system for natural gas to acetylene according to claim 1, characterized in that: The semi-enclosed component includes an isolation cover and a support structure. The support structure supports the isolation cover above the smoke exhaust port, and the space between the isolation cover and the smoke exhaust port is a smoke exhaust channel.

3. The preheating system for natural gas to acetylene according to claim 2, characterized in that: The area of ​​the isolation hood is 10%-15% larger than the area of ​​the smoke exhaust outlet.

4. The preheating system for natural gas to acetylene according to any one of claims 2 and 3, characterized in that: The distance between the isolation cover and the smoke exhaust port is 100-300mm.

5. The preheating system for natural gas to acetylene according to claim 4, characterized in that: The isolation cover is tilted and positioned above the smoke exhaust port.

6. The preheating system for natural gas to acetylene according to claim 5, characterized in that: The isolation cover forms an angle of no more than 45° with the horizontal plane of the smoke exhaust outlet.

7. The preheating system for natural gas to acetylene according to claim 6, characterized in that: The exhaust pipe of the oxygen preheater and the exhaust pipe of the natural gas preheater are connected to an extended exhaust pipe, the top of which is the exhaust port.

8. The preheating system for natural gas to acetylene according to any one of claims 5-7, characterized in that: The isolation cover adopts an arc-shaped structure, a square structure, or a cone-shaped structure with the opening facing downwards.

9. A device for the partial oxidation of natural gas to acetylene, characterized in that, The preheating system described in any one of claims 1-8 is used.

10. The application of the preheating system for acetylene production from natural gas according to any one of claims 1-8 in the process of producing acetylene from natural gas by partial oxidation.

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