Safety interlocking system of monochlorodifluoromethane water dilution cracking reaction system

Abstract

The utility model discloses a safety interlocking system of a monochlorodifluoromethane water dilution cracking reaction system, and relates to the technical field of tetrafluoroethylene production. According to the utility model, through the dispersed instrument control system, when the pressure of the fuel gas feeding pipeline of the steam superheater is too low or the two cracking reactors are overheated, the feeding is stopped and the introduction of the fuel gas is stopped by controlling the closing of the monochlorodifluoromethane feeding valve A1, the monochlorodifluoromethane feeding valve B1 and the fuel gas feeding valve A; therefore, production is ensured to be in a safe state. When the disperse instrument control system does not act, the monochlorodifluoromethane feeding valve A2, the monochlorodifluoromethane feeding valve B2 and the fuel gas feeding valve B can be controlled to be closed through the safety instrument system, feeding is stopped, fuel gas introduction is stopped, meanwhile, the fire extinguishing steam feeding valve is opened, fire extinguishing steam is introduced into the steam superheating furnace, and the fire extinguishing effect is achieved. Therefore, production is ensured to be in a safe state.

Description

Technical Field

[0001] The utility model relates to the technical field of tetrafluoroethylene production, in particular to a safety interlocking system of a difluorochloromethane water dilution cracking reaction system. Background Art

[0002] At present, there are two main processes for producing tetrafluoroethylene using difluorochloromethane as raw material: empty tube thermal cracking and steam dilution cracking. Among them, the steam dilution cracking method has high conversion rate, few by-products, high yield and low production cost, and is one of the important methods for industrial production of tetrafluoroethylene.

[0003] The steam dilution cracking production process uses difluorochloromethane and superheated steam to preheat in a steam superheater, and then mix them in an adiabatic tubular reactor for cracking reaction. The reaction equation is: 2CHClF2→CF2=CF2+2HCl. Then, the finished tetrafluoroethylene is obtained through water washing, alkali washing, calcium chloride dehydration, compression, sulfuric acid drying, compression, distillation and other processes.

[0004] The cracking reaction is particularly critical in the tetrafluoroethylene production process. The cracking process is carried out at high temperature. The material temperature in the reaction system generally exceeds its autoignition point. If overheating occurs in the reaction system, the fuel system fluctuates greatly, and the fuel gas pressure is too low, it may cause the steam superheater burner to flash back, causing the burner to burn out, etc., resulting in material leakage and even fire and explosion accidents, causing serious personal injury, property loss and environmental pollution. Therefore, in view of this problem, it is necessary to provide a safety interlock system for the dichloromethane water dilution cracking reaction system to ensure the safe production. Utility Model Content

[0005] The technical problem to be solved by the utility model is: to overcome the deficiencies of the prior art and provide a safety interlock system for a difluorochloromethane water dilution cracking reaction system. Through a distributed instrument control system, when the fuel gas feed line pressure of a steam superheater is too low or two cracking reactors are overheated, the difluorochloromethane feed valve A1, the difluorochloromethane feed valve B1 and the fuel gas feed valve A are controlled to be closed, the feed is stopped and the introduction of fuel gas is stopped, thereby ensuring that production is in a safe state.

[0006] The technical solution of the utility model is:

[0007] A safety interlock system for a difluorochloromethane water-dilution cracking reaction system, the cracking reaction system comprising a steam superheater, a cracking reactor A and a cracking reactor B, wherein a difluorochloromethane heating pipeline A, a difluorochloromethane heating pipeline B, a superheated steam heating pipeline A and a superheated steam heating pipeline B are arranged in the steam superheater, the feed port of the difluorochloromethane heating pipeline A is connected to the difluorochloromethane feed pipeline A, and the discharge port is connected to the difluorochloromethane discharge pipeline A, the feed port of the difluorochloromethane heating pipeline B is connected to the difluorochloromethane feed pipeline B, and the discharge port is connected to the difluorochloromethane discharge pipeline B; the feed port of the superheated steam heating pipeline A is connected to the superheated steam feed pipeline A, and the discharge port is connected to the superheated steam discharge pipeline A, the feed port of the superheated steam heating pipeline B is connected to the superheated steam feed pipeline B, and the discharge port is connected to the superheated steam A water vapor discharge pipeline B; a difluorochloromethane discharge pipeline A and a superheated steam discharge pipeline A are connected to a cracking reactor A, and a difluorochloromethane discharge pipeline B and a superheated steam discharge pipeline B are connected to a cracking reactor B; a fuel gas feed pipeline is connected to the steam superheater; a difluorochloromethane feed valve A1 is provided on the difluorochloromethane feed pipeline A, a difluorochloromethane feed valve B1 is provided on the difluorochloromethane feed pipeline B, and a fuel gas feed valve A is provided on the fuel gas feed pipeline; a pressure sensor A is provided on the fuel gas feed pipeline, a temperature sensor A1 is provided on the cracking reactor A, and a temperature sensor B1 is provided on the cracking reactor B; the difluorochloromethane feed valve A1, the difluorochloromethane feed valve B1, the fuel gas feed valve A, the pressure sensor A, the temperature sensor A1 and the temperature sensor B1 are electrically connected to the distributed instrument control system respectively.

[0008] Preferably, the steam superheater is connected to a fire extinguishing steam feed pipeline, a fire extinguishing steam feed valve is arranged on the fire extinguishing steam feed pipeline, a difluorochloromethane feed valve A2 is arranged on the difluorochloromethane feed pipeline A, a difluorochloromethane feed valve B2 is arranged on the difluorochloromethane feed pipeline B, and a fuel gas feed valve B is arranged on the fuel gas feed pipeline; a pressure sensor B is arranged on the fuel gas feed pipeline, a temperature sensor A2 is arranged on the cracking reactor A, and a temperature sensor B2 is arranged on the cracking reactor B; the fire extinguishing steam feed valve, the difluorochloromethane feed valve A2, the difluorochloromethane feed valve B2, the fuel gas feed valve B, the pressure sensor B, the temperature sensor A2 and the temperature sensor B2 are respectively electrically connected to the safety instrument system.

[0009] Preferably, the fuel gas feed pipeline and the fire extinguishing steam feed pipeline are connected to the bottom of the steam superheater furnace.

[0010] Preferably, an air heating pipeline is provided in the steam superheating furnace, the feed port of the air heating pipeline is connected to an air inlet pipeline, the discharge port is connected to an air outlet pipeline, and the air outlet pipeline is connected to the steam superheating furnace.

[0011] Preferably, the air outlet pipeline is connected to the bottom of the steam superheater.

[0012] Preferably, the air heating pipeline is arranged on the top of the steam superheater.

[0013] Preferably, the chlorodifluoromethane heating pipeline A and the chlorodifluoromethane heating pipeline B are arranged at the upper part of the steam superheater, and the superheated steam heating pipeline A and the superheated steam heating pipeline B are arranged at the lower part of the steam superheater.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] The utility model uses a distributed instrument control system to control the chlorodifluoromethane feed valve A1, the chlorodifluoromethane feed valve B1 and the fuel gas feed valve A to close, stop feeding and stop introducing fuel gas, so as to ensure that production is in a safe state. In addition, when the distributed instrument control system does not work, the chlorodifluoromethane feed valve A2, the chlorodifluoromethane feed valve B2 and the fuel gas feed valve B can be controlled by the safety instrument system to close, stop feeding and stop introducing fuel gas, and at the same time open the fire extinguishing steam feed valve to introduce fire extinguishing steam into the steam superheating furnace, so as to ensure that production is in a safe state. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The utility model is a schematic diagram of the structure of the safety interlock system of the difluorochloromethane water dilution cracking reaction system.

[0017] In the figure, 1, steam superheater; 2, cracking reactor A; 201, temperature sensor A1; 202, temperature sensor A2; 3, cracking reactor B; 301, temperature sensor B1; 302, temperature sensor B2; 4, difluorochloromethane heating pipeline A; 5, difluorochloromethane heating pipeline B; 6, superheated steam heating pipeline A; 7, superheated steam heating pipeline B; 8, difluorochloromethane feed pipeline A; 801, difluorochloromethane feed valve A1; 802, difluorochloromethane feed valve A2; 9, difluorochloromethane discharge pipeline A; 10, difluorochloromethane feed pipeline B; 1001, difluorochloromethane Feed valve B1; 1002, difluorochloromethane feed valve B2; 11, difluorochloromethane discharge pipeline B; 12, superheated steam feed pipeline A; 13, superheated steam discharge pipeline A; 14, superheated steam feed pipeline B; 15, superheated steam discharge pipeline B; 16, fuel gas feed pipeline; 1601, fuel gas feed valve A; 1602, fuel gas feed valve B; 1603, pressure sensor A; 1604, pressure sensor B; 17, fire extinguishing steam feed pipeline; 1701, fire extinguishing steam feed valve; 18, air heating pipeline; 19, air intake pipeline; 20, air outlet pipeline; 21, blower. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0019] Example 1

[0020] like Figure 1As shown, this embodiment provides a safety interlock system for a difluorochloromethane water dilution cracking reaction system, wherein the cracking reaction system comprises a steam superheater 1, a cracking reactor A2 and a cracking reactor B3, wherein a difluorochloromethane heating pipeline A4, a difluorochloromethane heating pipeline B5, a superheated water vapor heating pipeline A6 and a superheated water vapor heating pipeline B7 are arranged in the steam superheater 1, wherein the difluorochloromethane heating pipeline A4 and the difluorochloromethane heating pipeline B5 are arranged at the upper part of the steam superheater 1, and the superheated water vapor heating pipeline A6 and the superheated water vapor heating pipeline B7 are arranged at the lower part of the steam superheater 1. The feed port of the difluorochloromethane heating pipeline A4 is connected to the difluorochloromethane feed pipeline A8, and the discharge port is connected to the difluorochloromethane discharge pipeline A9; the feed port of the difluorochloromethane heating pipeline B5 is connected to the difluorochloromethane feed pipeline B10, and the discharge port is connected to the difluorochloromethane discharge pipeline B11; the feed port of the superheated steam heating pipeline A6 is connected to the superheated steam feed pipeline A12, and the discharge port is connected to the superheated steam discharge pipeline A13; the feed port of the superheated steam heating pipeline B7 is connected to the superheated steam feed pipeline B14, and the discharge port is connected to the superheated steam discharge pipeline B15; the difluorochloromethane discharge pipeline A9 and the superheated steam discharge pipeline A13 are connected to the cracking reactor A2, and the difluorochloromethane discharge pipeline B11 and the superheated steam discharge pipeline B15 are connected to the cracking reactor B3.

[0021] like Figure 1 As shown, the bottom of the steam superheater 1 is connected to a fuel gas feed pipeline 16, the top of the steam superheater 1 is provided with an air heating pipeline 18, the feed port of the air heating pipeline 18 is connected to an air intake pipeline 19, a blower 21 is provided on the air intake pipeline 19, the discharge port is connected to an air outlet pipeline 20, and the air outlet pipeline 20 is connected to the bottom of the steam superheater 1. The steam superheater 1 preheats the raw material monochlorodifluoromethane and superheated water vapor for tetrafluoroethylene production by the heat generated by the combustion of the fuel gas, and after preheating, cracking reactions are carried out in the cracking reactor A2 and the cracking reactor B3.

[0022] like Figure 1As shown, a difluorochloromethane feed valve A1 801 is provided on the difluorochloromethane feed line A8, a difluorochloromethane feed valve B1 1001 is provided on the difluorochloromethane feed line B10, and a fuel gas feed valve A 1601 is provided on the fuel gas feed line 16; a pressure sensor A 1603 is provided on the fuel gas feed line 16, a temperature sensor A1 201 is provided on the cracking reactor A2, and a temperature sensor B1 301 is provided on the cracking reactor B3; the difluorochloromethane feed valve A1 801, the difluorochloromethane feed valve B1 1001, the fuel gas feed valve A1601, the pressure sensor A 1603, the temperature sensor A1 201 and the temperature sensor B1 301 are electrically connected to a distributed instrument control (DCS) system, respectively.

[0023] Working principle:

[0024] The DCS system presets the low limit and low-low limit of the pressure of the fuel gas feed line 16, and the high limit and high-high limit of the temperature of the cracking reactor A2 and the cracking reactor B3. During the reaction, the pressure sensor A1603, the temperature sensor A1201 and the temperature sensor B1301 feed back the pressure of the fuel gas feed line 16, the temperature information of the cracking reactor A2 and the cracking reactor B3 to the DCS system in real time. When the pressure sensor A1603 detects that the pressure of the fuel gas feed line 16 reaches the low limit, or when the temperature sensor A1201 or the temperature sensor B1301 detects that the temperature of the cracking reactor A2 or the cracking reactor B3 reaches the high limit, the DCS system issues a high limit alarm to remind the staff. When the pressure sensor A 1603 detects that the pressure of the fuel gas feed line 16 reaches the lower limit, or when the temperature sensor A1 201 or the temperature sensor B1301 detects that the temperature of the cracking reactor A 2 or the cracking reactor B 3 reaches the upper limit, the DCS system controls the closing of the difluorochloromethane feed valve A1 801, the difluorochloromethane feed valve B1 1001 and the fuel gas feed valve A 1601, stops the continuous introduction of fuel gas into the steam superheater 1, and stops supplying to the cracking reactor A 2 and the cracking reactor B 3, so that the pressure of the fuel gas feed line 16 rises above the lower limit and the temperature of the cracking reactor A 2 and the cracking reactor B 3 drops below the upper limit, ensuring that the production is in a safe state.

[0025] Example 2

[0026] On the basis of Example 1, Figure 1As shown, the bottom of the steam superheater 1 is connected to a fire extinguishing steam feed pipeline 17, on which a fire extinguishing steam feed valve 1701 is provided, a difluorochloromethane feed valve A2 802 is provided on a difluorochloromethane feed pipeline A8, a difluorochloromethane feed valve B2 1002 is provided on a difluorochloromethane feed pipeline B10, a fuel gas feed valve B 1602 is provided on a fuel gas feed pipeline 16; a pressure sensor B 1604 is provided on the fuel gas feed pipeline 16, a temperature sensor A2 202 is provided on a cracking reactor A2, and a temperature sensor B2 302 is provided on a cracking reactor B3; the fire extinguishing steam feed valve 1701, the difluorochloromethane feed valve A2 802, the difluorochloromethane feed valve B2 1002, the fuel gas feed valve B 1602, the pressure sensor B 1604, the cracking reactor A2 is provided with a temperature sensor A2 202, and the cracking reactor B3 is provided with a temperature sensor B2 302. 1604. Temperature sensor A2 202 and temperature sensor B2 302 are electrically connected to a safety instrument system (SIS), respectively.

[0027] Working principle:

[0028] The lower limit and low-low limit of the pressure of the fuel gas feed pipeline 16, as well as the upper limit and high-high limit of the temperature of the cracking reactor A2 and the cracking reactor B3 are preset in the SIS system, the lower limit of the pressure is lower than the low-low limit of the pressure preset in the DCS system, and the high limit of the temperature preset in the SIS system is greater than the high-high limit of the temperature preset in the DCS system; during the reaction process, the pressure sensor B 1604, the temperature sensor A2 202 and the temperature sensor B2 302 feed back the pressure information of the fuel gas feed pipeline 16 and the temperature information of the cracking reactor A2 and the cracking reactor B3 to the DCS system in real time.

[0029] When the pressure of the fuel gas feed pipeline 16 is too low or the temperature of the cracking reactor A2 or the cracking reactor B3 is too high, if the DCS system does not take action, causing the pressure of the fuel gas feed pipeline 16 to continue to decrease or the temperature of the cracking reactor A2 or the cracking reactor B3 to continue to increase, then when the pressure sensor B 1604 detects that the pressure of the fuel gas feed pipeline 16 has reached a lower limit, or when the temperature sensor A2 202 or the temperature sensor B2 302 detects that the temperature of the cracking reactor A2 or the cracking reactor B3 has reached a higher limit, the SIS system issues a high limit alarm to alert the staff. When the pressure sensor B 1604 detects that the pressure of the fuel gas feed pipeline 16 has reached the lower limit, or when the temperature sensor A2 202 or the temperature sensor B2302 detects that the temperature of the cracking reactor A 2 or the cracking reactor B 3 has reached the upper limit, the SIS system controls the closing of the difluorochloromethane feed valve A2 802, the difluorochloromethane feed valve B2 1002 and the fuel gas feed valve B 1602, stops continuing to pass the fuel gas into the steam superheater 1, and stops feeding the cracking reactor A 2 and the cracking reactor B 3; and opens the fire extinguishing steam feed valve 1701 to pass fire extinguishing steam into the steam superheater 1 to prevent the burner of the steam superheater 1 from flashing back due to the low fuel gas pressure, which may cause the burner to burn out, etc., thereby ensuring that the production is in a safe state.

Claims

1. The safety interlock system of the difluorochloromethane water dilution cracking reaction system is characterized by: The cracking reaction system comprises a steam superheating furnace (1), a cracking reactor A (2) and a cracking reactor B (3). The steam superheating furnace (1) is provided with a difluoromonochloromethane heating pipeline A (4), a difluoromonochloromethane heating pipeline B (5), a superheated steam heating pipeline A (6) and a superheated steam heating pipeline B (7). The feed inlet of the difluoromonochloromethane heating pipeline A (4) is connected to a difluoromonochloromethane feed pipeline A (8), the discharge outlet is connected to a difluoromonochloromethane discharge pipeline A (9), the feed inlet of the difluoromonochloromethane heating pipeline B (5) is connected to a difluoromonochloromethane discharge pipeline A (9), and the feed inlet of the difluoromonochloromethane heating pipeline B (5) is connected to a difluoromonochloromethane discharge pipeline A (10). The feed port is connected to a chlorodifluoromethane feed pipeline B (10), and the discharge port is connected to a chlorodifluoromethane discharge pipeline B (11); the feed port of the superheated steam heating pipeline A (6) is connected to a superheated steam feed pipeline A (12), and the discharge port is connected to a superheated steam discharge pipeline A (13); the feed port of the superheated steam heating pipeline B (7) is connected to a superheated steam feed pipeline B (14), and the discharge port is connected to a superheated steam discharge pipeline B (15); the chlorodifluoromethane discharge pipeline A (9), the superheated steam discharge pipeline A (1 3) is connected to the cracking reactor A (2), the difluorochloromethane discharge pipeline B (11) and the superheated steam discharge pipeline B (15) are connected to the cracking reactor B (3); the steam superheater (1) is connected to the fuel gas feed pipeline (16); the difluorochloromethane feed pipeline A (8) is provided with a difluorochloromethane feed valve A1 (801), the difluorochloromethane feed pipeline B (10) is provided with a difluorochloromethane feed valve B1 (1001), and the fuel gas feed pipeline (16) is provided with a fuel gas feed valve A (1601); A pressure sensor A (1603) is provided on the fuel gas feed pipeline (16), a temperature sensor A1 (201) is provided on the cracking reactor A (2), and a temperature sensor B1 (301) is provided on the cracking reactor B (3); the difluorochloromethane feed valve A1 (801), the difluorochloromethane feed valve B1 (1001), the fuel gas feed valve A (1601), the pressure sensor A (1603), the temperature sensor A1 (201) and the temperature sensor B1 (301) are respectively electrically connected to the distributed instrument control system.

2. The safety interlock system of the difluorochloromethane water dilution cracking reaction system according to claim 1, characterized in that: The steam superheater (1) is connected to a fire extinguishing steam feed pipeline (17), on which a fire extinguishing steam feed valve (1701) is provided, a difluorochloromethane feed pipeline A (8) is provided with a difluorochloromethane feed valve A2 (802), a difluorochloromethane feed pipeline B (10) is provided with a difluorochloromethane feed valve B2 (1002), a fuel gas feed pipeline (16) is provided with a fuel gas feed valve B (1602); a pressure sensor is provided on the fuel gas feed pipeline (16). The cracking reactor A (2) is provided with a temperature sensor A2 (202), and the cracking reactor B (3) is provided with a temperature sensor B2 (302); the fire extinguishing steam feed valve (1701), the difluorochloromethane feed valve A2 (802), the difluorochloromethane feed valve B2 (1002), the fuel gas feed valve B (1602), the pressure sensor B (1604), the temperature sensor A2 (202) and the temperature sensor B2 (302) are respectively electrically connected to the safety instrument system.

3. The safety interlock system of the difluorochloromethane water dilution cracking reaction system according to claim 2, characterized in that: The fuel gas feed pipeline (16) and the fire extinguishing steam feed pipeline (17) are connected to the bottom of the steam superheater (1).

4. The safety interlock system of the difluorochloromethane water dilution cracking reaction system according to claim 1, characterized in that: An air heating pipeline (18) is arranged in the steam superheating furnace (1); the feed port of the air heating pipeline (18) is connected to an air inlet pipeline (19); the discharge port is connected to an air outlet pipeline (20); and the air outlet pipeline (20) is connected to the steam superheating furnace (1).

5. The safety interlock system of the difluorochloromethane water dilution cracking reaction system according to claim 4, characterized in that: The air outlet pipeline (20) is connected to the bottom of the steam superheater (1).

6. The safety interlock system of the difluorochloromethane water dilution cracking reaction system according to claim 4, characterized in that: The air heating pipeline (18) is arranged on the top of the steam superheating furnace (1).

7. The safety interlock system of the difluorochloromethane water dilution cracking reaction system according to claim 1, characterized in that: The chlorodifluoromethane heating pipeline A (4) and the chlorodifluoromethane heating pipeline B (5) are arranged at the upper part of the steam superheating furnace (1), and the superheated steam heating pipeline A (6) and the superheated steam heating pipeline B (7) are arranged at the lower part of the steam superheating furnace (1).

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