Efficient cracking reaction system for tetrafluoroethylene production

Abstract

The utility model relates to the field of chemical equipment, and provides an efficient cracking reaction system for tetrafluoroethylene production, which comprises a pi-type reactor, an R22 gas inlet pipe, a steam inlet pipe and a heating furnace for heating the gas inlet pipe, and the proportional control module is used for controlling the air inlet flow of the R22 air inlet pipe and the steam inlet pipe. The Pi-type reactor disclosed by the utility model has the beneficial effects that the mixer is arranged between the steam inlet pipe and the Pi-type reactor body and can be used for fully and uniformly mixing R22 and steam, so that the cracking efficiency is improved, the conversion rate and the selectivity can reach the level of the existing device, and the effect of improving the yield is achieved; the raw materials are fully mixed in the nozzle pipe and finally enter the pi-type reactor body through the conical expansion pipe to react, so that the two materials are more fully mixed, uniform distribution of cracking heat is ensured, and a relatively proper conversion rate and relatively high selectivity of R22 are powerfully ensured.

Description

Technical Field

[0001] The utility model relates to the field of chemical industry, in particular to a high-efficiency cracking reaction system for producing tetrafluoroethylene. Background Art

[0002] Tetrafluoroethylene is an important fluorine-containing monomer, which is widely used in the production of high-performance polymers. A key step in its production process is cracking preparation, that is, converting compounds containing tetrafluoroethylene into tetrafluoroethylene through cracking reaction. The technology of preparing tetrafluoroethylene by dichlorodifluoromethane (CHClF2, commonly known as Freon 22) and water vapor dilution cracking is an effective industrial method, that is, dichlorodifluoromethane reacts with water vapor under the action of high temperature and catalyst to produce tetrafluoroethylene and by-products.

[0003] Patent CN101973843A discloses a technology for preparing tetrafluoroethylene by diluting and cracking dichloromethane and water vapor. Tetrafluoroethylene is produced by diluting and cracking R22 water vapor. In the process of producing tetrafluoroethylene by diluting and cracking R22 water vapor, the cracking reactor used is a "π" type reactor. At present, the maximum capacity of a single set of equipment in the same industry is 12,000 tons / year. The diameter of the "π" type reactor is generally DN125 or DN150, and the single tube capacity is about 2500t / a. If a single set of production capacity is 40,000 tons / year, or the single tube capacity is calculated according to two heating furnaces, it is 5000t / a. Each heating furnace needs to carry 4 "π" type reactors, and the reactor diameter needs to be increased to DN200. The two materials will be mixed according to the original structure, and uneven mixing and uneven heating will occur, which will cause low cracking conversion rate and selectivity, and the production capacity cannot meet the design requirements, resulting in increased energy consumption. In this cracking reaction process, the control of the proportion of raw material R22 and water vapor added is only a simple single-loop control, and the cracking temperature control is also only a simple single-loop control. In this way, the inconsistent pace of each control cannot form a system, and it is difficult to achieve the best conversion rate and selectivity. In this way, material consumption and energy consumption cannot reach the ideal state. Utility Model Content

[0004] Aiming at the shortcomings of the prior art, the invention solves the problem of uneven mixing and heating when two materials are mixed according to the original structure in the preparation of tetrafluoroethylene.

[0005] The utility model provides a high-efficiency cracking reaction system for tetrafluoroethylene production, comprising a π-type reactor, an R22 air inlet pipe, a steam air inlet pipe and a heating furnace for heating the air inlet pipe, wherein the R22 air inlet pipe and the steam air inlet pipe are connected to the π-type reactor, and a proportional control module is further included to control the air inlet flow rates of the R22 air inlet pipe and the steam air inlet pipe.

[0006] Furthermore, the π-type reactor includes an inlet pipe, a mixer, a mixer outlet nozzle, a reaction section and an outlet pipe which are connected in sequence, the inlet pipe is connected to a steam inlet pipe, the mixer is provided with an R22 inlet pipe connected to the R22 inlet pipe, and the front end of the reaction section is provided with a trumpet shape connected to the mixer outlet nozzle.

[0007] Furthermore, the heating furnace is provided with a semi-water gas inlet pipe for providing fuel, and a bottom blower for providing hot air, and the air outlet duct of the bottom blower is heated in the heating furnace and intersects with the semi-water gas inlet pipe.

[0008] Furthermore, the steam inlet pipe is provided with a steam meter for detecting steam flow and a steam regulating valve for controlling the steam flow, a steam temperature sensor is provided at one end of the steam inlet pipe close to the π-type reactor, and the reaction system is provided with a steam PIDA control module for cascade controlling the steam flow, which is electrically connected to the steam meter, the steam regulating valve and the steam temperature sensor.

[0009] Furthermore, the R22 air inlet pipe is provided with an R22 meter for detecting the R22 flow rate and an R22 regulating valve for controlling the R22 flow rate, the reaction section is provided with a cracking reaction temperature sensor, and the proportional control module is provided with an R22PIDA control module for cascade controlling the R22 flow rate, which is electrically connected to the R22 meter, the R22 regulating valve and the cracking reaction temperature sensor.

[0010] Furthermore, the semi-water gas inlet pipe is provided with a semi-water gas meter for detecting the flow rate of the semi-water gas and a semi-water gas regulating valve for controlling the flow rate of the semi-water gas, the heating furnace is provided with a heating furnace temperature sensor, and the proportional control module is provided with a semi-water gas PIDA control module for cascade controlling the flow rate of the semi-water gas, which is electrically connected to the semi-water gas meter, the semi-water gas regulating valve and the heating furnace temperature sensor.

[0011] As a preferred solution, the semi-water gas inlet pipe is provided with a cut-off valve, and the proportional control module is provided with an emergency cut-off module heating furnace temperature sensor, a steam meter, an R22 meter and a cut-off valve.

[0012] As a preferred solution, the proportion control module for controlling the raw material proportion is electrically connected to the steam meter and the R22 meter.

[0013] The beneficial effects of the utility model are:

[0014] 1. The utility model is provided with a mixer between the steam inlet pipe and the π-type reactor body, which can fully and evenly mix R22 and water vapor, improve the cracking efficiency, make the conversion rate and selectivity reach the level of the existing device, and achieve the effect of increasing production;

[0015] 2. The water vapor passes through the outer cylinder of the mixer and the mixer reduction pipe section in sequence from the steam inlet pipe. As the inner diameter of the mixer reduction pipe section gradually decreases, the water vapor flow rate increases, thereby forming a negative pressure, sucking in the R22 entering from the R22 inlet pipe, fully mixing in the nozzle pipe, and finally entering the π-type reactor body through the tapered expansion pipe for reaction, so that the two materials are more fully mixed, ensuring the uniform distribution of cracking heat, and effectively guaranteeing a more suitable conversion rate and higher selectivity of R22.

[0016] 3. Inserted thermometers are installed at the tail end of the π-type reactor body and on the side wall of the steam inlet pipe, which improves the accuracy of the traditional wall-mounted temperature measuring points, is conducive to the control of the cracking temperature and can effectively control the conversion rate and selectivity.

[0017] 4. The tetrafluoroethylene cracking automation control system has a small improvement over the existing R22 cracking process control system, is low-cost, safe and stable, and is easy to implement in enterprise production.

[0018] 5. An automatic control system is formed through only five control measures, namely: cascade control of semi-water gas entering the heating furnace, cascade control of steam feeding, cascade control of raw material R22 feeding, proportional control of steam and R22 entering the heating furnace, and interlocking control of heating furnace overtemperature and material cutoff (steam, R22). Under the condition that the original process remains unchanged, only software system control measures are taken to replace manual control operations to ensure safe and stable operation, which has important economic significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the content of the utility model easier to understand, the utility model is further described in detail according to specific embodiments and in conjunction with the accompanying drawings.

[0020] Figure 1 It is a structural schematic diagram of the utility model.

[0021] Figure 2 It is a structural schematic diagram of the π-type reactor of the utility model.

[0022] The reference numerals in the accompanying drawings are:

[0023] 1. π-type reactor; 11. inlet pipe; 12. mixer; 13. mixer outlet nozzle; 14. reaction section; 15. outlet pipe; 2. steam inlet pipe; 21. R22 inlet pipe; 3. R22 inlet pipe; 4. heating furnace; 5. semi-water gas inlet pipe; 6. bottom fan; XV1. semi-water gas cut-off valve; F1. semi-water gas flowmeter; FV1. semi-water gas regulating valve; T1. heating furnace temperature sensor; FIC401 semi-water gas cascade regulator; F2. steam flowmeter; FV2. steam regulating valve; T2. steam temperature sensor; FIC402. steam PIDA control module; F3. R22 meter; FV2. R22 regulating valve; T3. cracking reaction temperature sensor; FIC403. R22PIDA control module; FIC404. proportional control module; XV1. cut-off valve. DETAILED DESCRIPTION

[0024] To illustrate the features of the present invention, the present invention is further described below with reference to the accompanying drawings and embodiments.

[0025] Example:

[0026] See also Figure 1 and Figure 2 The present embodiment provides a high-efficiency cracking reaction system for tetrafluoroethylene production, comprising a π-type reactor 1, an R22 air inlet pipe 3, a steam air inlet pipe 2 and a heating furnace 4 for heating the air inlet pipe, wherein the R22 air inlet pipe 3 and the steam air inlet pipe 2 are connected to the π-type reactor 1, and further comprising a proportional control module to control the air inlet flow rates of the R22 air inlet pipe 3 and the steam air inlet pipe 2.

[0027] The π-type reactor 1 includes an inlet pipe 11, a mixer 12, a mixer outlet nozzle 13, a reaction section 14 and an outlet pipe 15 which are connected in sequence. The inlet pipe 11 is connected to the steam inlet pipe 2. The mixer 12 is provided with an R22 inlet pipe 21 connected to the R22 inlet pipe 3. The front end of the reaction section 14 is provided with a trumpet-shaped connection to the mixer outlet nozzle 13. The mixer can fully mix R22 and water vapor, improve the cracking efficiency, and make the conversion rate and selectivity reach the level of existing devices, so as to achieve the effect of increased production. In this embodiment, the bending radius of the inlet pipe 11 is 500 mm, and the bending radius of the outlet pipe is 600 mm. The problem of uneven cracking temperature caused by uneven mixing due to the increase in pipe diameter is solved by setting the mixer outlet nozzle 13.

[0028] The heating furnace 4 is provided with a semi-water gas inlet pipe 5 for providing fuel. In order to improve the heating efficiency of the heating furnace 4, this embodiment is also provided with a bottom blower 6 for providing hot air. The air outlet duct of the bottom blower 6 is heated in the heating furnace 4 and intersects with the semi-water gas inlet pipe 5, thereby improving the reaction efficiency of the semi-water gas.

[0029] The steam inlet pipe 2 is provided with a steam meter F2 for detecting the steam flow rate and a steam regulating valve FV2 for controlling the steam flow rate. The steam inlet pipe 2 is provided with a steam temperature sensor T2 at one end close to the π-type reactor 1. The reaction system is provided with a steam PIDA control module FIC402 for cascade control of the steam flow rate, which is electrically connected to the steam meter F2, the steam regulating valve FV2 and the steam temperature sensor T2. In this embodiment, the temperature after steam heating is set to 800°C. If the actual temperature rises, it means that the steam flow rate is large. The cascade controller FIC402 in the DCS will issue an instruction to reduce the steam flow rate setting value, and then control the steam regulating valve FV2 to close, thereby realizing the automatic adjustment of the cascade control steam regulating valve FV2.

[0030] The R22 inlet pipe 3 is provided with an R22 meter F3 for detecting the R22 flow rate and an R22 regulating valve FV3 for controlling the R22 flow rate, the reaction section 14 is provided with a cracking reaction temperature sensor T3, and the reaction system is provided with an R22PIDA control module FIC403 for cascade control of the R22 flow rate, which is electrically connected to the R22 meter F3, the R22 regulating valve FV3 and the cracking reaction temperature sensor T3. In this embodiment, the temperature of the cracking reactor R401 is set to a certain value such as 690°C. If the actual temperature rises, it means that the R22 flow rate is large, and the R22PIDA control module FIC403 will issue an instruction to reduce the R22 flow setting value, and then control the R22 regulating valve FV3 to move down, thereby realizing automatic adjustment of the semi-water gas regulating valve FV3.

[0031] The semi-water gas inlet pipe 5 is provided with a semi-water gas meter F1 for detecting the semi-water gas flow and a semi-water gas regulating valve FV1 for controlling the semi-water gas flow, the heating furnace 4 is provided with a heating furnace temperature sensor T1, and the reaction system is provided with a semi-water gas PIDA control module FIC401 for cascade controlling the semi-water gas flow, which is electrically connected to the semi-water gas meter F1, the semi-water gas regulating valve FV1 and the heating furnace temperature sensor T1. In this embodiment, the heating furnace temperature is set to 900°C. If the actual temperature rises, it means that the semi-water gas flow is large, and the cascade controller FIC401 in the DCS will issue an instruction to reduce the semi-water gas flow setting value, thereby controlling the semi-water gas regulating valve FV1 to move down, thereby realizing the automatic adjustment of the semi-water gas regulating valve FV1.

[0032] The reaction system is provided with a ratio control module FIC404 for controlling the ratio of raw materials, which is electrically connected to the steam meter F2 and the R22 meter F3. In this embodiment, the ratio of steam to R22 is set to 1.3, and the flow rate of R22 is taken as the base number. When the flow rate of R22 increases, the ratio regulator FIC404 calculates F3 multiplied by 1.3 and then issues a command to adjust the set value of the steam flow rate, thereby controlling the steam regulating valve FV2 to automatically adjust the action.

[0033] As a preferred solution, the semi-water gas inlet pipe 5 is provided with a cut-off valve XV1, and the reaction system is provided with an emergency cut-off module I401, a heating furnace temperature sensor T1, a steam meter F2, an R22 meter F3 and a cut-off valve XV1. The interlocking control of over-temperature and material cut-off of the heating furnace is realized. When any monitoring point of the steam flow, R22 flow, and heating furnace temperature exceeds the set value, such as the heating furnace temperature exceeds the set temperature of 980°C, the cut-off valve XV1 is interlocked and closed to stop the gas, so as to avoid over-temperature damage to the heating furnace and play a protective role.

[0034] The above embodiments and drawings are only used to illustrate the technical solution of the utility model, and are not intended to limit the utility model. The utility model is described in detail with reference to the preferred embodiments. It should be understood by ordinary technicians in this field that the changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the utility model do not deviate from the purpose of the utility model and should also fall within the scope of protection of the claims of the utility model. Other related technical structures not fully disclosed in the utility model are prior art in the field.

Claims

1. An efficient cracking reaction system for tetrafluoroethylene production, characterized in that: The invention comprises a π-type reactor (1), an R22 air intake pipe (3), a steam air intake pipe (2), and a heating furnace (4) for heating the air intake pipe, wherein the R22 air intake pipe (3) and the steam air intake pipe (2) are connected to the π-type reactor (1), and further comprises a proportional control module for controlling the air intake flow rates of the R22 air intake pipe (3) and the steam air intake pipe (2).

2. The high-efficiency cracking reaction system for tetrafluoroethylene production according to claim 1, characterized in that: The π-type reactor (1) comprises an inlet pipe (11), a mixer (12), a mixer outlet nozzle (13), a reaction section (14) and an outlet pipe (15) which are connected in sequence, wherein the inlet pipe (11) is connected to a steam inlet pipe (2), the mixer (12) is provided with an R22 inlet pipe (21) connected to an R22 inlet pipe (3), and the front end of the reaction section (14) is provided in a trumpet shape and connected to the mixer outlet nozzle (13).

3. The efficient cracking reaction system for tetrafluoroethylene production according to claim 1, characterized in that: The heating furnace (4) is provided with a semi-water gas inlet pipe (5) for supplying fuel, and is also provided with a bottom fan (6) for supplying hot air; the air outlet duct of the bottom fan (6) is heated in the heating furnace (4) and intersects with the semi-water gas inlet pipe (5).

4. The high-efficiency cracking reaction system for tetrafluoroethylene production according to claim 1, characterized in that: The steam inlet pipe (2) is provided with a steam meter (F2) for detecting the steam flow rate and a steam regulating valve (FV2) for controlling the steam flow rate; a steam temperature sensor (T2) is provided at one end of the steam inlet pipe (2) close to the π-type reactor (1); and a steam PIDA control module (FIC402) for cascade controlling the steam flow rate is provided in the proportional control module and is electrically connected to the steam meter (F2), the steam regulating valve (FV2) and the steam temperature sensor (T2).

5. The high-efficiency cracking reaction system for tetrafluoroethylene production according to claim 2, characterized in that: The R22 air inlet pipe (3) is provided with an R22 meter (F3) for detecting the R22 flow rate and an R22 regulating valve (FV3) for controlling the R22 flow rate, the reaction section (14) is provided with a cracking reaction temperature sensor (T3), and the proportional control module is provided with an R22 PIDA control module (FIC403) for cascade controlling the R22 flow rate, which is electrically connected to the R22 meter (F3), the R22 regulating valve (FV3) and the cracking reaction temperature sensor (T3).

6. The high-efficiency cracking reaction system for tetrafluoroethylene production according to claim 3, characterized in that: The semi-water gas inlet pipe (5) is provided with a semi-water gas meter (F1) for detecting the flow rate of the semi-water gas and a semi-water gas regulating valve (FV1) for controlling the flow rate of the semi-water gas. The heating furnace (4) is provided with a heating furnace temperature sensor (T1). The proportional control module is provided with a semi-water gas PIDA control module (FIC401) for cascade controlling the flow rate of the semi-water gas, which is electrically connected to the semi-water gas meter (F1), the semi-water gas regulating valve (FV1) and the heating furnace temperature sensor (T1).

7. The high-efficiency cracking reaction system for tetrafluoroethylene production according to claim 6, characterized in that: The semi-water gas inlet pipe (5) is provided with a shut-off valve (XV1), and the proportional control module is provided with an emergency shut-off module (I401), a heating furnace temperature sensor (T1), a steam meter (F2), an R22 meter (F3) and a shut-off valve (XV1).

8. The high-efficiency cracking reaction system for tetrafluoroethylene production according to claim 5, characterized in that: The proportional control module (FIC404) configured to control the raw material ratio is electrically connected to the steam meter (F2) and the R22 meter (F3).

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