Quenching system suitable for high-temperature flue gas treatment of organic chlorides combustion

Abstract

The application discloses a quenching system suitable for treating high-temperature flue gas of organic chlorides incineration, which comprises a quenching device and an absorption tower; the quenching device comprises a quenching device jacket serving as a cooling medium channel arranged on an outer wall and a cooling graphite ring arranged on a top; the cooling graphite ring comprises a graphite ring jacket serving as a cooling medium channel, an overflow ring gap is formed on an upper portion of an inner wall of the graphite ring jacket, and cooling medium overflowing from the overflow ring gap can flow down along an inner wall of the quenching device; the quenching device jacket and the graphite ring jacket are communicated through a communication pipeline. The application has the following advantages: 1) the high-temperature flue gas can be rapidly cooled to 120 DEG C or below, the safe and stable operation of the absorption tower is guaranteed, and the generation of dioxin is avoided; 2) the cooling medium is uniformly distributed in the jacket, and the heating of each point in the inner cylinder of the quenching device is uniform; and 3) the high-temperature flue gas can be prevented from washing and corroding the interior.

Description

Technical Field

[0001] This invention relates to the field of chlor-alkali chemical production technology, and in particular to vinyl chloride synthesis and trichloroethylene production systems. Background Technology

[0002] In the chlor-alkali chemical industry, the high-boiling-point column bottom of the vinyl chloride distillation unit in polyvinyl chloride (PVC) production plants produces high-boiling-point residues, mainly dichloroethane. In trichloroethylene (TC) production plants, the distillation unit produces low-boiling-point and high-boiling-point waste liquids, primarily tetrachloroethane and pentachloroethane. Various organochlorine treatment technologies exist, such as stripping, adsorption, biodegradation, and photocatalytic oxidation, but all have limitations. Furthermore, organochlorine compounds are highly complex, making thorough treatment difficult with conventional methods. Incineration technology, however, can completely decompose and transform hazardous waste, ensuring that the exhaust gas meets emission standards. Incineration technology reduces the harm of hazardous waste to humans and the environment, and is a necessary guarantee for the sustainable development of chlor-alkali enterprises.

[0003] The exhaust gas from organochlorides is collected and sent to an incinerator for combustion, using natural gas or hydrogen as fuel and supplemented with air. The incinerator operates at a temperature controlled between 1000 and 1150°C, reaching the complete oxidation temperature of organochlorides, fully converting them into CO2, HCl, and H2O. The high-temperature flue gas is rapidly cooled through a quench unit. After cooling, the flue gas absorbs hydrogen chloride byproducts, producing hydrochloric acid, through water absorption. The remaining gases (such as nitrogen, carbon dioxide, and trace amounts of hydrogen chloride) are washed in an alkaline scrubbing tower to achieve compliant emissions.

[0004] Although high-temperature incineration can completely remove organochlorides, it easily produces highly toxic dioxins during the process. Since dioxins decompose readily at high temperatures, controlling the incineration temperature above 1000℃ and limiting the flue gas residence time in the incinerator to more than 2 seconds can effectively prevent dioxin formation. However, dioxins can regenerate in environments of 300-500℃ after decomposition, leading to incomplete decomposition. Therefore, to avoid dioxin formation in incineration flue gas, in addition to controlling the incineration temperature and flue gas residence time, designing an efficient flue gas quenching system is essential. Summary of the Invention

[0005] To rapidly cool the high-temperature flue gas from the combustion furnace to below 120°C, thereby ensuring the safe and stable operation of the hydrogen chloride absorption tower and its absorption effect, while also preventing the generation of dioxins, this invention provides a quenching system suitable for treating high-temperature flue gas from organochlorine incineration.

[0006] The technical solution adopted in this invention is: a quenching system suitable for treating high-temperature flue gas from organochlorine incineration, comprising a quencher and an absorption tower; the quencher includes a quencher jacket serving as a cooling medium channel on its outer wall and a cooling graphite ring on its top; the cooling graphite ring includes a graphite ring jacket serving as a cooling medium channel, and an overflow annular gap is provided on the upper part of the inner wall of the graphite ring jacket, allowing the cooling medium overflowing from the overflow annular gap to flow down along the inner wall of the quencher; the quencher jacket and the graphite ring jacket are connected by a connecting pipe; the top and bottom of the quencher are respectively provided with a high-temperature flue gas inlet and a cooled flue gas outlet; the cooled flue gas outlet is connected to the absorption tower.

[0007] As a further improvement of the present invention, the quench cooler is provided with a spray system for cooling high-temperature flue gas.

[0008] More preferably, the spraying system includes at least three layers of spray pipes arranged vertically, and the spray pipes are provided with spray holes.

[0009] Preferably, the liquid phase outlet at the bottom of the absorption tower is connected to the spray system and the quencher jacket via a cooling water pipe; a cooler is installed on the cooling water pipe.

[0010] More preferably, it also includes an industrial water supply line for replenishing water to the spray system and the quencher jacket.

[0011] More preferably, it also includes an elevated tank for replenishing water to the jacket of the quencher, and the industrial water supply pipeline is capable of supplying water to the elevated tank.

[0012] More preferably, the spray system includes a spray water flow meter for monitoring the spray water flow rate, and an industrial water supply pipeline spray water programmable valve interlocked with the spray water flow meter.

[0013] More preferably, it also includes a cooling water flow meter for monitoring the cooling water flow rate in the quencher jacket, and a cooling water control valve for the industrial water supply pipeline and a cooling water control valve for the high-level tank water supply pipeline that are interlocked with the cooling water flow meter.

[0014] More preferably, the flue gas outlet pipe of the quench cooler is equipped with a quench cooler outlet thermometer for monitoring the flue gas temperature, and the quench cooler outlet thermometer is interlocked with the upstream incinerator shutdown system.

[0015] The beneficial effects of this invention are: 1) The quenching system of this invention, suitable for treating high-temperature flue gas from organochlorine incineration, can rapidly cool the high-temperature flue gas from the combustion furnace to below 120°C, ensuring the safe and stable operation of the hydrogen chloride absorption tower and its absorption effect, while avoiding the generation of dioxins. 2) Connecting the quencher jacket and the graphite ring jacket through a connecting pipe ensures that the cooling medium is evenly distributed inside the jacket, guaranteeing uniform heating at all points inside the quencher cylinder. 3) By opening an overflow annular gap in the upper part of the inner wall of the graphite ring jacket, the cooling medium overflowing from the overflow annular gap can flow down along the inner wall of the quencher. This achieves the goal of controlling the pressure of the cooling medium entering the quencher jacket, ensuring that the cooling medium in the jacket flows evenly from the overflow annular gap along the inner wall of the quencher, forming a liquid film on the inner wall to prevent the high-temperature flue gas from eroding and corroding the interior. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the quenching system structure suitable for treating high-temperature flue gas from organochlorine incineration according to the present invention.

[0017] Figure 2 This is a schematic diagram of the spray system nozzle arrangement structure in a specific implementation.

[0018] Figure 3 This is an enlarged view of part a.

[0019] The diagram is labeled as follows: 1-Flow meter, 2, 12, 36-Pressure gauge, 3-Industrial water supply pipeline spray water control valve, 4, 7, 9, 11, 13, 35-Regulating valve, 5, 8, 10, 14-Flow meter, 6-Spray water flow meter, 15-Cooling water flow meter, 16-Industrial water supply pipeline cooling water control valve, 17-High-level tank water supply pipeline cooling water control valve, 18-High-level tank, 19-Ball valve, 20-Level gauge, 21-Cooling graphite ring, 22-Overflow annular gap, 23-Graphite ring jacket, 24-Connecting pipe, 25, 26, 27-Spray nozzle, 28-Quick cooler, 29-Quick cooler jacket, 30-Thermometer, 31-Quick cooler outlet thermometer, 32-Absorption tower, 33-Circulating pump, 34-Cooler. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] like Figure 1 , Figure 2 , Figure 3As shown, the quenching system of the present invention, suitable for treating high-temperature flue gas from organochlorine incineration, includes a quencher 28 and an absorption tower 32. The quencher 28 includes a quencher jacket 29 disposed on the outer wall as a cooling medium channel and a cooling graphite ring 21 disposed on the top. The cooling graphite ring 21 includes a graphite ring jacket 23 as a cooling medium channel. An overflow annular gap 22 is opened on the upper part of the inner wall of the graphite ring jacket 23, and the cooling medium overflowing from the overflow annular gap 22 can flow down along the inner wall of the quencher 28. The quencher jacket 29 and the graphite ring jacket 23 are connected by two U-shaped connecting pipes 24. The top and bottom of the quencher 28 are respectively provided with a high-temperature flue gas inlet and a cooled flue gas outlet. The cooled flue gas outlet is connected to the absorption tower 32. The quencher 28 is equipped with a spray system for high-temperature flue gas spray cooling, as shown in the attached figure. Figure 2 As shown, the spray system is located inside the quench cooler 28, with three layers of spray pipes arranged from top to bottom, forming a 60-degree angle when projected onto the horizontal plane. Each layer of spray pipes has spray holes facing downwards, and each layer is equipped with a flow meter and a regulating valve. The first layer of spray pipes is also connected to an industrial water supply pipeline. The liquid phase outlet at the bottom of the absorption tower 32 is connected to the spray system and the quench cooler jacket 29 via a cooling water pipeline; a cooler 34 is installed on the cooling water pipeline. An industrial water supply pipeline for supplying water to the spray system and the quench cooler jacket 29 is also included. The main industrial water pipeline is equipped with a flow meter and a remote pressure gauge to monitor the industrial water supply and measure the usage. An elevated tank 18 for supplying water to the quench cooler jacket 29 is also included, and the industrial water supply pipeline can supply water to the elevated tank 18. The spray system includes a spray water flow meter 6 for monitoring the spray water flow rate, and an industrial water supply pipeline spray water control valve 3 interlocked with the spray water flow meter 6. It also includes a cooling water flow meter 15 for monitoring the cooling water flow rate in the quench cooler jacket 29, and an industrial water supply pipeline cooling water control valve 16 and a high-level tank water supply pipeline cooling water control valve 17 interlocked with the cooling water flow meter 15. A quench cooler outlet thermometer 31 for monitoring the flue gas temperature is installed on the flue gas outlet pipe of the quench cooler 28, and the quench cooler outlet thermometer 31 is interlocked with the upstream incinerator shutdown system.

[0022] During operation, water is first added to the absorption tower 32 to ensure that there is a certain liquid level in the bottom of the absorption tower. The circulating pump 33 is started to transport the medium. The medium is cooled to below 50°C by the cooler 34 (using circulating water cooling). Part of it is circulated back to the absorption tower 32, and part of it is adjusted by the regulating valve 35 to keep the pressure of the pressure gauge 36 not lower than 350 kPa before being transported to the quench system. The purpose of keeping the pressure not lower than 350 kPa is to ensure that the spray distribution of the nozzle is uniform.

[0023] The cooling medium from the absorption tower 32 is divided into four parts, which are respectively fed into the three-layer nozzle and the quencher jacket 29. One part of this medium is regulated by the regulating valve 4 to ensure that the flow rate of the flow meter 5 is not less than 6 m³ / s. 3 / h, then enters the nozzle 25 and is sprayed through the small holes on the nozzle; a portion is adjusted by the regulating valve 7 to ensure that the flow rate of the flow meter 8 is not less than 6m³ / h. 3 / h, then enters the nozzle 26 and is sprayed through the small holes on the nozzle; a portion is adjusted by the regulating valve 9 to ensure that the flow rate of the flow meter 10 is not less than 6m³ / h. 3 / h, then enters the nozzle 27 and is sprayed through the small holes on the nozzle; part of it is adjusted by the regulating valve 11 to control the pressure of the pressure gauge 12 on the pipeline at 120kPa, and then adjusted by the regulating valve 13 to control the flow rate of the flow meter 14 at 4m 3 / h, the medium, after being regulated by the dual regulating valves, enters the jacket 29 of the quench cooler, and then enters the graphite ring jacket 23 from the top of the quench cooler jacket 29 through the U-shaped connecting pipe 24. It overflows from the top overflow annular gap 22 of the graphite ring jacket 23 and flows down along the inner wall of the quench cooler 28 cylinder, forming a liquid diaphragm on the inner wall to prevent the flue gas from scouring the inner wall of the quench cooler 28.

[0024] The actual flow rate of the high-temperature flue gas from the incinerator is 29115 m³ / h. 3 The flue gas, at a temperature of 1100℃, is mainly composed of HCl (22.5%), CO2 (6.6%), N2 (53.3%), O2 (5%), and H2O (12.6%). The high-temperature flue gas enters the quench cooler 28 and comes into contact with the cooling medium sprayed from nozzles 25, 26, and 27, rapidly cooling to 97℃. The cooled flue gas then goes to the absorption tower 32 for washing to produce hydrochloric acid. The hydrochloric acid at the bottom of the tower is cooled by the cooler 34; part of it continues to circulate as a cooling medium back to the quench system, part returns to the absorption tower 32 as an absorption medium, and part is discharged as a byproduct hydrochloric acid.

[0025] To ensure the safety of the quench cooler, this system is designed with four interlocks. The low-low value of the interlock for the spray water flow meter 6 is set to 6m. 3 / h, the interlock low-low value setting of cooling water flow meter 15 is 3m 3 / h, the interlock high value of the quench cooler outlet thermometer 31 is 120℃. When the displayed value of the spray water flow meter 6 is lower than 6m 3 When the temperature reaches / h, the first-level spray pipe interlock of the quench cooler 28 is immediately triggered, and the industrial water supply pipeline spray water control valve 3 opens to replenish water to the first-level spray pipe pipeline to prevent the outlet temperature of the quench cooler 28 from exceeding the limit. When the displayed value of the cooling water flow meter 15 is lower than 3m³ / h... 3When the flow rate reaches / h, the quench cooler jacket water supply interlock is immediately triggered, and the industrial water supply pipeline cooling water control valve 16 opens to replenish water to the quench cooler jacket pipeline, preventing stress damage to the quench cooler caused by water shortage and overheating. If the displayed value of the cooling water flow meter 15 is lower than the interlock value and the industrial water supply pipeline cooling water control valve 16 is opened, but the displayed value of the cooling water flow meter 15 is still lower than 3m³ / h... 3 At this time, the high-level tank water replenishment interlock is triggered, and the cooling water control valve 17 of the high-level tank water supply pipeline is opened to replenish water to the jacket pipeline. When the temperature of the quench cooler outlet thermometer 31 is higher than 120℃, the upstream incinerator interlock is triggered, the incinerator stops feeding and gas, and the source of high-temperature flue gas is cut off to prevent high-temperature flue gas from damaging the downstream absorption tower.

[0026] Under normal circumstances, the liquid level in the high-level tank 18 needs to be maintained above 95%. When the liquid level is below 95%, water is added to it through the ball valve 19. The main function of maintaining a high liquid level in the high-level tank is to trigger the high-level tank interlock to open the cooling water control valve 17 of the high-level tank water supply pipeline to replenish water to the jacket 29 of the quencher in the event that the absorption tower circulating pump 33 stops abnormally and there is no cooling medium delivered to the quencher, thus preventing damage to the quencher due to insufficient liquid in the jacket.

Claims

1. A quenching system suitable for treating high-temperature flue gas from organochlorine incineration, characterized in that: The system includes a quench cooler (28) and an absorption tower (32); the quench cooler (28) includes a quench cooler jacket (29) disposed on the outer wall as a cooling medium channel and a cooling graphite ring (21) disposed on the top; the cooling graphite ring (21) includes a graphite ring jacket (23) as a cooling medium channel, and an overflow annular gap (22) is provided on the upper part of the inner wall of the graphite ring jacket (23), and the cooling medium overflowing from the overflow annular gap (22) can flow along the quench cooler (28). The gas flows down the inner wall; the quencher jacket (29) and the graphite ring jacket (23) are connected by a connecting pipe (24); the top and bottom of the quencher (28) are respectively provided with a high-temperature flue gas inlet and a cooled flue gas outlet; the cooled flue gas outlet is connected to the absorption tower (32); wherein, the quencher (28) is provided with a spray system for high-temperature flue gas spray cooling; the spray system includes at least 3 layers of spray pipes arranged vertically, and the spray pipes are provided with spray holes.

2. The quenching system suitable for treating high-temperature flue gas from organochlorine incineration according to claim 1, characterized in that: The liquid phase outlet at the bottom of the absorption tower (32) is connected to the spray system and the quencher jacket (29) via a cooling water pipe; a cooler (34) is installed on the cooling water pipe.

3. The quenching system suitable for treating high-temperature flue gas from organochlorine incineration according to claim 2, characterized in that: It also includes an industrial water supply line for replenishing water to the spray system and the quencher jacket (29).

4. The quenching system suitable for treating high-temperature flue gas from organochlorine incineration according to claim 3, characterized in that: It also includes an elevated tank (18) for replenishing water to the quencher jacket (29), and the industrial water supply line is capable of supplying water to the elevated tank (18).

5. The quenching system suitable for treating high-temperature flue gas from organochlorine incineration according to claim 4, characterized in that: The spray system includes a spray water flow meter (6) for monitoring the spray water flow rate, and an industrial water supply pipeline spray water programmable valve (3) interlocked with the spray water flow meter (6).

6. The quenching system suitable for treating high-temperature flue gas from organochlorine incineration according to claim 4, characterized in that: It also includes a cooling water flow meter (15) for monitoring the cooling water flow in the quencher jacket (29), and an industrial water supply pipeline cooling water control valve (16) and a high-level tank water supply pipeline cooling water control valve (17) interlocked with the cooling water flow meter (15).

7. The quenching system suitable for treating high-temperature flue gas from organochlorine incineration according to claim 4, characterized in that: The flue gas outlet pipe of the quench cooler (28) is equipped with a quench cooler outlet thermometer (31) for monitoring the flue gas temperature. The quench cooler outlet thermometer (31) is interlocked with the upstream incinerator shutdown system.

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