Continuous chlorination pipeline reaction device and method for preparing ethyl 4-chloroacetoacetate

Abstract

The invention provides a continuous chlorination pipeline reaction device and a method for preparing ethyl 4-chloroacetoacetate. The device comprises a tank body, a liquid nitrogen system and a tubular reactor. The tank body is provided with a liquid nitrogen inlet pipe and a liquid nitrogen outlet pipe connected with the liquid nitrogen system, a reaction liquid inlet pipe connected with a reaction liquid feeding pipe, a first gas inlet pipe connected with a first feeding pipe, a second gas inlet pipe connected with a second feeding pipe, and a product outlet pipe. The tubular reactor is located in the tank body. The pipeline of the tubular reactor is in a curved shape, one end of which is connected with the reaction liquid inlet pipe and the first gas inlet pipe, and the other end is connected with the product outlet pipe. The reaction liquid inlet pipe is located downstream of the first gas inlet pipe. The tubular reactor is provided with a first mixer located at the inlet end of the tubular reactor and downstream of the reaction liquid inlet pipe. The second gas inlet pipe is connected with the first mixer. The invention has high reaction conversion rate, stable product quality, high output and energy saving.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and in particular relates to a continuous chlorination pipeline reaction device and a method for preparing ethyl 4-chloroacetoacetate. Background Art

[0002] The conventional refrigeration method is that the refrigeration unit pre-cools the refrigerant, and then sends the refrigerant to the reactor for heat exchange through a transfer pump. The specific heat capacity and viscosity of the refrigerant, the power consumption of the supporting power system, the cold loss of the refrigerant when it flows in the pipeline, the energy loss of the unit's cold energy during the exchange and transfer process, etc., all these reasons lead to a huge loss of cold energy in the unit, low cold energy utilization, and serious energy waste, which runs counter to the national goal of energy conservation and emission reduction.

[0003] Chlorination reactions are generally violent and release a lot of heat. Traditional kettle reactors have uneven heat exchange and are prone to side reactions due to inadequate temperature control, resulting in the production of polychlorinated products. Traditional batch production methods in kettle reactors are prone to the production of polychlorinated products due to uneven stirring and mixing, material mixing, and local excess of reactants. Poor chlorine control is prone to leakage accidents; the batch production method in kettles not only has a small output, but also has very unstable quality. These drawbacks lead to low efficiency of kettle reactors and frequent safety accidents. Summary of the invention

[0004] The present invention is made to solve the above problems, and aims to provide a continuous chlorination pipeline reaction device with high reaction conversion rate, stable product quality, high output and energy saving, and a method for preparing ethyl 4-chloroacetoacetate.

[0005] The present invention provides a continuous chlorination pipeline reaction device, which is characterized by comprising:

[0006] A tank body, wherein the tank body is provided with a liquid nitrogen inlet pipe, a liquid nitrogen outlet pipe, a reaction liquid inlet pipe connected to a reaction liquid feed pipe, a first gas inlet pipe connected to a first feed pipe, a second gas inlet pipe connected to a second feed pipe, and a product outlet pipe;

[0007] a liquid nitrogen system, which provides liquid nitrogen to the tank body to provide a low temperature environment inside the tank body, and the liquid nitrogen system is connected to the liquid nitrogen inlet pipe and the liquid nitrogen outlet pipe; and

[0008] A tubular reactor is located in the tank body, the pipeline of the tubular reactor is curved, one end of the tubular reactor is connected to the reaction liquid inlet pipe and the first gas inlet pipe, the reaction liquid inlet pipe is located downstream of the first gas inlet pipe, the other end of the tubular reactor is connected to the product outlet pipe, a first mixer is provided on the tubular reactor, the first mixer is located at the inlet end of the tubular reactor and downstream of the reaction liquid inlet pipe, and the second gas inlet pipe is connected to the first mixer.

[0009] Furthermore, in the continuous chlorination pipeline reaction device provided by the present invention, it can also have the following characteristics: wherein, the tubular reactor comprises a plurality of parallel pipelines, and the pipelines are connected end to end to form a connected pipeline.

[0010] Furthermore, the continuous chlorination pipeline reaction device provided by the present invention may also have the following feature: fins are provided on the outer side wall of the tubular reactor.

[0011] Furthermore, in the continuous chlorination pipeline reaction device provided by the present invention, it can also have the following characteristics: wherein, a first shut-off valve, a first flow regulating valve and a flow meter are arranged on the pipeline between the liquid nitrogen system and the liquid nitrogen inlet pipe, a second flow regulating valve is arranged on the reaction liquid feed pipeline, and a third flow regulating valve is arranged on the second gas feed pipeline.

[0012] The tank body is provided with a pressure sensor for measuring the pressure inside the tank body, and the tubular reactor is provided with a temperature sensor for measuring the temperature inside the tubular reactor.

[0013] The liquid nitrogen refrigeration continuous chlorination pipeline reaction device also includes a DCS system,

[0014] The first shut-off valve, the first flow regulating valve, the flow meter, the second flow regulating valve, the third flow regulating valve, the pressure sensor, and the temperature sensor are all connected to the DCS system; the pressure measured by the pressure sensor is interlocked with the first shut-off valve, the second flow regulating valve, and the third flow regulating valve; the temperature measured by the temperature sensor is interlocked with the first flow regulating valve, the second flow regulating valve, and the third flow regulating valve.

[0015] Furthermore, in the continuous chlorination pipeline reaction device provided by the present invention, it can also have the following characteristics: wherein, there are two liquid nitrogen inlet pipes, the two liquid nitrogen inlet pipes are respectively located on opposite sides of the tank body and located in the middle of the height of the tank body, and a liquid nitrogen nozzle is provided at one end of the liquid nitrogen inlet pipe in the tank body.

[0016] Furthermore, in the continuous chlorination pipeline reaction device provided by the present invention, it may also have the following feature: wherein, the tubular reactor is provided with at least one second mixer between the first mixer and the outlet end.

[0017] Furthermore, in the continuous chlorination pipeline reaction device provided by the present invention, it can also have the following characteristics: wherein, the number of the second mixer is one, and the second mixer is located in the middle position between the first mixer and the outlet end of the tubular reactor.

[0018] Furthermore, in the continuous chlorination pipeline reaction device provided by the present invention, it can also have the following characteristics: wherein the liquid nitrogen system comprises: a liquid nitrogen storage tank connected to the liquid nitrogen inlet pipe for storing liquid nitrogen and providing liquid nitrogen to the tank body, a nitrogen compressor connected to the liquid nitrogen outlet pipe for compressing the nitrogen coming out of the tank body, and a condenser for cooling the nitrogen compressed by the nitrogen compressor to prepare liquid nitrogen, the inlet of the condenser is connected to the outlet of the liquid nitrogen compressor, and the outlet of the condenser is connected to the inlet of the liquid nitrogen storage tank.

[0019] Furthermore, in the continuous chlorination pipeline reaction device provided by the present invention, it can also have the following characteristics: the continuous chlorination pipeline reaction device also includes a product storage tank connected to the product outlet pipe.

[0020] The present invention also provides a method for preparing ethyl 4-chloroacetoacetate, characterized in that the chlorination process adopts the following method:

[0021] Chloroacetoacetyl chloride is prepared by using the continuous chlorination pipeline reaction device described in any one of claims 1 to 9,

[0022] First, negative pressure is sucked into the tank body, and then the liquid nitrogen system reduces the temperature in the tubular reactor to 15°C±0.2°C, and then nitrogen is introduced into the tubular reactor through the first gas inlet pipe, and then a mixed solution of diketene and dichloromethane is introduced into the tubular reactor through the reaction liquid inlet pipe, and finally chlorine is introduced into the tubular reactor through the second gas inlet pipe. The liquid nitrogen system maintains the temperature in the tubular reactor at 15°C±1°C, and the materials react in the tubular reactor and flow out from the product outlet pipe to obtain chloroacetoacetyl chloride.

[0023] The present invention has the following advantages:

[0024] According to the continuous chlorination pipeline reaction device involved in the present invention, when preparing ethyl 4-chloroacetoacetate, the reaction conversion rate is high, the product quality is stable, the output is high, the energy is saved and the structure is simple.

[0025] The method for preparing ethyl 4-chloroacetoacetate involved in the present invention has high reaction conversion rate, stable product quality, high output and energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a continuous chlorination pipeline reaction device in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the following examples are combined with the accompanying drawings to specifically describe the continuous chlorination pipeline reaction device and the method for preparing ethyl 4-chloroacetoacetate of the present invention.

[0028] Embodiment 1

[0029] like Figure 1 As shown, the continuous chlorination pipeline reaction device 100 includes: a tank body 10, a liquid nitrogen system 20 and a tubular reactor 30.

[0030] The tank body 10 is provided with a liquid nitrogen inlet pipe 11, a liquid nitrogen outlet pipe 12, a reaction liquid inlet pipe 13, a first gas inlet pipe 14, a second gas inlet pipe 15, and a product outlet pipe 16. The reaction liquid inlet pipe 13 is connected to the reaction liquid feed pipe 61, the first gas inlet pipe 14 is connected to the first feed pipe 62, and the second gas inlet pipe 15 is connected to the second feed pipe 63. Specifically, the design pressure of the tank body 10 is 1.0 MPa. Specifically, in the chlorination process step of preparing ethyl 4-chloroacetoacetate, the first feed pipe 62 conveys nitrogen, and the second feed pipe 63 conveys chlorine.

[0031] The liquid nitrogen system 20 provides liquid nitrogen to the tank body 10 to provide a low temperature environment in the tank body 10 . The liquid nitrogen system 20 is connected to the liquid nitrogen inlet pipe 11 and the liquid nitrogen outlet pipe 12 .

[0032] In this embodiment, the liquid nitrogen system 20 includes: a liquid nitrogen storage tank 21, a nitrogen compressor 22 and a condenser 23. The liquid nitrogen storage tank 21 is used to store liquid nitrogen and provide liquid nitrogen to the tank body 10. The liquid nitrogen storage tank 21 is connected to the liquid nitrogen inlet pipe 11. The nitrogen compressor 22 is used to compress the nitrogen coming out of the tank body 10, and the nitrogen compressor 22 is connected to the liquid nitrogen outlet pipe 12. The condenser 23 is used to cool the nitrogen compressed by the nitrogen compressor 22. The inlet of the condenser 23 is connected to the outlet of the liquid nitrogen compressor 22, and the outlet of the condenser 23 is connected to the inlet of the liquid nitrogen storage tank 21. Nitrogen can be recycled, which is economical, convenient, safe and reliable.

[0033] In this embodiment, there are two liquid nitrogen inlet pipes 11, which are respectively located on opposite sides of the tank body 10 and at the middle of the height of the tank body 10. A liquid nitrogen nozzle is provided at one end of each liquid nitrogen inlet pipe 11 in the tank body 10.

[0034] The tubular reactor 30 is located in the tank body 10, and the pipeline of the tubular reactor 30 is curved. In the present embodiment, the tubular reactor 30 includes a plurality of parallel pipelines 33, and the two pipelines are connected end to end to form a connected pipeline. Specifically, the pipeline of the tubular reactor 30 is made of titanium, which can effectively prevent the corrosion of chlorine under low temperature conditions. One end of the tubular reactor 30 is connected to the reaction liquid inlet pipe 13 and the first gas inlet pipe 14, and the other end of the tubular reactor 30 is connected to the product outlet pipe 16. The reaction liquid inlet pipe 13 is located downstream of the first gas inlet pipe 14, and the gas entering the tubular reactor 30 from the first gas inlet pipe 14 is used to promote the reaction liquid entering the tubular reactor 30 from the reaction liquid inlet pipe 13 to flow to the outlet end of the tubular reactor 30, so as to avoid mixing of the reaction liquid. A first mixer 31 is provided on the tubular reactor 30, and the first mixer 31 is located at the inlet end of the tubular reactor 30 and downstream of the reaction liquid inlet pipe 13, and the second gas inlet pipe 15 is connected to the first mixer 31. The use of the tubular reactor 30 increases the reaction temperature from the original -25°C to -15°C, resulting in a faster reaction speed, a higher conversion rate, a greatly improved cold capacity utilization rate, and greatly improved product output, content and stability.

[0035] In this embodiment, fins are provided on the outer wall of the tubular reactor 30. The fins are made of stainless steel, which greatly increases the heat exchange area, thereby quickly conducting away the reaction heat and greatly improving the heat exchange effect.

[0036] In this embodiment, the tubular reactor 30 is provided with at least one second mixer 32 between the first mixer 31 and the outlet. Specifically, there is one second mixer 32, which is located in the middle of the first mixer 31 and the outlet of the tubular reactor 30.

[0037] In this embodiment, the pipeline between the liquid nitrogen system 20 and the liquid nitrogen inlet pipe 11 is provided with a first shut-off valve 51 for cutting off the liquid nitrogen, a first flow regulating valve 52 for adjusting the liquid nitrogen flow rate, and a flow meter 53 for measuring the nitrogen flow rate in the pipeline. Specifically, there are two first flow regulating valves 52, two flow meters 53, the first shut-off valve 51 is arranged on the main pipeline between the liquid nitrogen system 20 and the liquid nitrogen inlet pipe 11, and one first flow regulating valve 52 and a flow meter 53 are arranged on the two branches respectively. A second flow regulating valve 54 for cutting off the reaction liquid is arranged on the reaction liquid feed pipeline 61, a third flow regulating valve 55 for cutting off the gas on the pipeline is arranged on the second gas feed pipeline, a pressure sensor (not shown in the figure) for measuring the pressure in the tank body is arranged on the tank body 10, and a temperature sensor (not shown in the figure) for measuring the temperature in the tubular reactor is arranged on the tubular reactor 30. The continuous chlorination pipeline reaction device 100 also includes a DCS system, i.e., a distributed control system (not shown in the figure). The first shut-off valve 51, the first flow regulating valve 52, the flow meter 53, the second flow regulating valve 54, the third flow regulating valve 55, the pressure sensor, and the temperature sensor are all connected to the DCS system. The pressure measured by the pressure sensor is interlocked with the first shut-off valve 51, the second flow regulating valve 54, and the third flow regulating valve 55, and the temperature measured by the temperature sensor is interlocked with the first flow regulating valve 52, the second flow regulating valve 54, and the third flow regulating valve 55. Automatic operation is achieved by temperature-variable and pressure-variable interlocking automatic valves, and the vaporizer is strictly controlled not to be over-temperature or over-pressure, which not only ensures the vaporization effect, but also is safe and reliable.

[0038] Specifically, in the chlorination process step of preparing ethyl 4-chloroacetoacetate, when the pressure in the tank body 10 is greater than the preset pressure, the first shut-off valve 51 is automatically controlled to be closed, the introduction of liquid nitrogen is stopped, and the second flow regulating valve 54 and the third flow regulating valve 55 are automatically controlled to be closed, and the introduction of the reaction liquid and chlorine is stopped. When the temperature in the tubular reactor 30 is greater than the preset temperature upper limit, the first flow regulating valve 52 is automatically controlled to increase the opening, so that the liquid nitrogen entering the tank body 10 increases, and the second flow regulating valve 54 and the third flow regulating valve 55 are automatically controlled to reduce the opening, and the flow of the reaction liquid and chlorine is reduced. When the temperature in the tubular reactor 30 is lower than the lower temperature limit, the first flow regulating valve 52 is automatically controlled to reduce the opening, so that the liquid nitrogen entering the tank body 10 is reduced, and the second flow regulating valve 54 and the third flow regulating valve 55 are automatically controlled to increase the opening, and the flow of the reaction liquid and chlorine is increased.

[0039] In this embodiment, the continuous chlorination pipeline reaction device 100 further includes a product storage tank 40 , which is connected to the product outlet pipe 16 and is used to store the product coming out of the product outlet pipe 16 .

[0040] The continuous chlorination pipeline reaction device 100 of the present invention is not only applicable to the chlorination process for preparing ethyl 4-chloroacetoacetate, but also suitable for other chlorination reactions and reactions with large heat release.

[0041] Embodiment 2

[0042] The method for preparing ethyl 4-chloroacetoacetate comprises the following steps:

[0043] Step 1, chlorination process:

[0044] Chloroacetoacetyl chloride was prepared using the continuous chlorination pipeline reaction device 100 in Example 1.

[0045] First, negative pressure is sucked into the tank body 10. Specifically, the negative pressure of the tank body 10 is sucked to -0.099MPa, and the pressure maintenance is qualified. Specifically, before the negative pressure is sucked into the tank body 10, first check whether the water, electricity, compressed air, instrumentation, DCS system, and various operating equipment are in normal state, and check whether the second gas inlet pipe 15, the second feed pipe 63, and the tubular reactor 30 are leaking. After each device is normal and the leak test is qualified, the next step of operation is carried out.

[0046] Then, the liquid nitrogen system 20 is started, the first shut-off valve 51 is opened, the first flow regulating valve 52 is opened, and liquid nitrogen is introduced into the tank body 10. The liquid nitrogen system 20 reduces the temperature in the tubular reactor 30 to 15°C±0.2°C.

[0047] Then, nitrogen is introduced into the tubular reactor 30 through the first gas inlet pipe 14, specifically, nitrogen is introduced at a rate of 10 L / h. The first gas inlet pipe 14 selectively introduces nitrogen for two purposes: first, it promotes the liquid to flow toward the outlet in a single direction to prevent mixing; second, it acts as a selective agent for the reaction to avoid the chlorination reaction at the α position to produce ethyl 2-chloroacetoacetate.

[0048] Next, the mixture of diketene and dichloromethane is introduced into the tubular reactor 30 through the reaction liquid inlet pipe 13. Specifically, after nitrogen is introduced for 5 minutes, the mixture of diketene and dichloromethane is introduced at a rate of 100 kg / h. Specifically, the mass fraction of diketene in the mixture of diketene and dichloromethane is 50%.

[0049] Finally, chlorine is introduced into the tubular reactor 30 through the second gas inlet pipe 15. Specifically, chlorine is introduced at a rate of 42 Kg / h 1 minute after the mixed solution of diketene and dichloromethane is introduced. The liquid nitrogen system 20 maintains the temperature in the tubular reactor 30 at 15°C ± 1°C, and the material flows out from the product outlet pipe to the product storage tank 40 after the reaction in the tubular reactor 30. After 1 hour, samples are taken from the product storage tank 40 for analysis. The content of chloroacetoacetyl chloride is 98.5%. During the reaction process, automatic operation is achieved through temperature-change and pressure-change interlocking automatic valves to ensure that the temperature in the tubular reactor 30 is maintained at 15°C ± 1°C and the pressure in the tank body 10 does not exceed the standard.

[0050] Step 2, esterification reaction:

[0051] The product obtained in step 1 is subjected to an esterification reaction with ethanol to obtain ethyl 4-chloroacetoacetate. The specific preparation process can adopt the process of existing equipment, or can adopt the continuous chlorination pipeline reaction device 100 in Example 1 for preparation.

[0052] Embodiment 3

[0053] The method for preparing ethyl 4-chloroacetoacetate comprises the following steps:

[0054] Step 1, chlorination process:

[0055] Chloroacetoacetyl chloride was prepared using the continuous chlorination pipeline reaction device 100 in Example 1.

[0056] First, negative pressure is sucked into the tank body 10. Specifically, the negative pressure of the tank body 10 is sucked to -0.099MPa, and the pressure maintenance is qualified. Specifically, before the negative pressure is sucked into the tank body 10, first check whether the water, electricity, compressed air, instrumentation, DCS system, and various operating equipment are in normal state, and check whether the second gas inlet pipe 15, the second feed pipe 63, and the tubular reactor 30 are leaking. After each device is normal and the leak test is qualified, the next step of operation is carried out.

[0057] Then, the liquid nitrogen system 20 is started, the first shut-off valve 51 is opened, the first flow regulating valve 52 is opened, and liquid nitrogen is introduced into the tank body 10. The liquid nitrogen system 20 reduces the temperature in the tubular reactor 30 to 15°C±0.2°C.

[0058] Then, nitrogen gas is introduced into the tubular reactor 30 through the first gas inlet pipe 14 , specifically, nitrogen gas is introduced at a rate of 15 L / h.

[0059] Next, the mixture of diketene and dichloromethane is introduced into the tubular reactor 30 through the reaction liquid inlet pipe 13. Specifically, after nitrogen is introduced for 5 minutes, the mixture of diketene and dichloromethane is introduced at a rate of 200 kg / h. Specifically, the mass fraction of diketene in the mixture of diketene and dichloromethane is 50%.

[0060] Finally, chlorine is introduced into the tubular reactor 30 through the second gas inlet pipe 15. Specifically, chlorine is introduced at a rate of 84 Kg / h 1 minute after the mixed solution of diketene and dichloromethane is introduced. The liquid nitrogen system 20 maintains the temperature in the tubular reactor 30 at 15°C ± 1°C, and the material flows out from the product outlet pipe to the product storage tank 40 after the reaction in the tubular reactor 30. After 1 hour, samples are taken from the product storage tank 40 for analysis. The content of chloroacetoacetyl chloride is 98.5%. During the reaction process, automatic operation is achieved through temperature-change and pressure-change interlocking automatic valves to ensure that the temperature in the tubular reactor 30 is maintained between 15°C ± 1°C and the pressure in the tank body 10 does not exceed the standard.

[0061] Step 2, esterification reaction:

[0062] The product obtained in step 1 is subjected to an esterification reaction with ethanol to obtain ethyl 4-chloroacetoacetate. The specific preparation process can adopt the process of existing equipment, or can adopt the continuous chlorination pipeline reaction device 100 in Example 1 for preparation.

[0063] Table 1 is a comparison of the content, reaction temperature, and energy consumption of chloroacetoacetyl chloride prepared in the chlorination process for preparing ethyl 4-chloroacetoacetate using a kettle reactor and using the continuous chlorination pipeline reaction device 100 of the present invention.

[0064] Table 1

[0065]

[0066] It can be seen from the table that, in the chlorination process for preparing ethyl 4-chloroacetoacetate by using the continuous chlorination pipeline reaction device 100 of the present invention, the purity of the product chloroacetoacetyl chloride is improved, the reaction temperature is increased, the output is significantly increased, and the power consumption is significantly reduced.

[0067] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.

Claims

1. A method for preparing ethyl 4-chloroacetoacetate, characterized in that: Chloroacetoacetyl chloride is prepared by using a continuous chlorination pipeline reaction device, the continuous chlorination pipeline reaction device comprising: A tank body, wherein the tank body is provided with a liquid nitrogen inlet pipe, a liquid nitrogen outlet pipe, a reaction liquid inlet pipe connected to a reaction liquid feed pipe, a first gas inlet pipe connected to a first feed pipe, a second gas inlet pipe connected to a second feed pipe, and a product outlet pipe; a liquid nitrogen system, which provides liquid nitrogen to the tank body to provide a low temperature environment inside the tank body, and the liquid nitrogen system is connected to the liquid nitrogen inlet pipe and the liquid nitrogen outlet pipe; and a tubular reactor, located in the tank body, the pipeline of the tubular reactor is curved, one end of the tubular reactor is connected to the reaction liquid inlet pipe and the first gas inlet pipe, the reaction liquid inlet pipe is located downstream of the first gas inlet pipe, the other end of the tubular reactor is connected to the product outlet pipe, a first mixer is provided on the tubular reactor, the first mixer is located at the inlet end of the tubular reactor and downstream of the reaction liquid inlet pipe, and the second gas inlet pipe is connected to the first mixer; A first shut-off valve, a first flow regulating valve and a flow meter are arranged on the pipeline between the liquid nitrogen system and the liquid nitrogen inlet pipe, a second flow regulating valve is arranged on the reaction liquid feed pipeline, and a third flow regulating valve is arranged on the second feed pipeline. The tank body is provided with a pressure sensor for measuring the pressure inside the tank body, and the tubular reactor is provided with a temperature sensor for measuring the temperature inside the tubular reactor. The liquid nitrogen refrigeration continuous chlorination pipeline reaction device also includes a DCS system, The first shut-off valve, the first flow regulating valve, the flow meter, the second flow regulating valve, the third flow regulating valve, the pressure sensor, and the temperature sensor are all connected to the DCS system; the pressure measured by the pressure sensor is interlocked with the first shut-off valve, the second flow regulating valve, and the third flow regulating valve; the temperature measured by the temperature sensor is interlocked with the first flow regulating valve, the second flow regulating valve, and the third flow regulating valve; The chlorination process uses the following method to prepare chloroacetoacetyl chloride: First, negative pressure is sucked into the tank body, and then the liquid nitrogen system reduces the temperature in the tubular reactor to 15°C±0.2°C, and then nitrogen is introduced into the tubular reactor through the first gas inlet pipe, and then a mixed solution of diketene and dichloromethane is introduced into the tubular reactor through the reaction liquid inlet pipe, and finally chlorine is introduced into the tubular reactor through the second gas inlet pipe. The liquid nitrogen system maintains the temperature in the tubular reactor at 15°C±1°C, and the materials react in the tubular reactor and flow out from the product outlet pipe to obtain chloroacetoacetyl chloride.

2. The method for preparing ethyl 4-chloroacetoacetate according to claim 1, characterized in that: The tubular reactor comprises a plurality of parallel pipes, and the pipes are connected end to end to form a connected pipe.

3. The method for preparing ethyl 4-chloroacetoacetate according to claim 1, characterized in that: The outer side wall of the tubular reactor is provided with fins.

4. The method for preparing ethyl 4-chloroacetoacetate according to claim 1, characterized in that: There are two liquid nitrogen inlet pipes, which are respectively located on opposite sides of the tank body and in the middle of the height of the tank body. A liquid nitrogen nozzle is arranged at one end of the liquid nitrogen inlet pipe in the tank body.

5. The method for preparing ethyl 4-chloroacetoacetate according to claim 1, characterized in that: The tubular reactor is provided with at least one second mixer between the first mixer and the outlet end.

6. The method for preparing ethyl 4-chloroacetoacetate according to claim 5, characterized in that: There is one second mixer, and the second mixer is located in the middle between the first mixer and the outlet end of the tubular reactor.

7. The method for preparing ethyl 4-chloroacetoacetate according to claim 1, characterized in that: The liquid nitrogen system comprises: a liquid nitrogen storage tank connected to the liquid nitrogen inlet pipe for storing liquid nitrogen and providing liquid nitrogen to the tank body, a nitrogen compressor connected to the liquid nitrogen outlet pipe for compressing nitrogen coming out of the tank body, and a condenser for cooling the nitrogen compressed by the nitrogen compressor to prepare liquid nitrogen, wherein the inlet of the condenser is connected to the outlet of the nitrogen compressor, and the outlet of the condenser is connected to the inlet of the liquid nitrogen storage tank.

8. The method for preparing ethyl 4-chloroacetoacetate according to claim 1, characterized in that: Also includes: A product storage tank is connected to the product outlet pipe.

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