Secondary combustion treatment system for coke oven tail gas

Abstract

The utility model relates to a secondary combustion treatment system for coke oven tail gas, which aims to solve the technical problem that the environment is polluted by the discharged coke oven tail gas, and adopts the technical scheme that the secondary combustion treatment system comprises a combustor and an induced draft fan, and the induced draft fan is connected with a coal gas inlet pipe and the combustor; the device further comprises a gas mixing chamber, a secondary combustion gas return pipeline, an air inlet pipe, a continuous emission monitoring system (CEMS) and a control system, the gas mixing chamber is connected with the combustor and the exhaust pipeline, the secondary combustion gas return pipeline is connected with the gas mixing chamber, the other end of the secondary combustion gas return pipeline is connected with the induced draft fan, the air inlet pipe is connected with the induced draft fan, a first butterfly valve is arranged on the exhaust pipeline, and a second butterfly valve is arranged on the control system. A sampling probe and a pressure sensor are arranged on the exhaust pipeline, a second butterfly valve is arranged on the secondary combustion air return pipeline, and a third butterfly valve is arranged on the air inlet pipe; and the continuous discharge monitoring system is electrically connected with the sampling probe. Tail gas returns to the combustor for secondary combustion, and is discharged after reaching the emission standard, so that the pollution to the atmospheric environment is reduced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to coke oven tail gas treatment equipment technical field, concretely relates to a coke oven gas combustion tail gas desulfurization device. BACKGROUND

[0002] Coke oven gas enters the boiler and produces tail gas after combustion by the burner, and the tail gas is discharged through the chimney, if the tail gas is not fully combusted in the burner, the tail gas still contains a large amount of SO2, NO x , CO and other substances, which will cause serious pollution to the atmospheric environment if directly discharged into the air, therefore, the coke oven tail gas must be treated, especially desulfurized and denitrified, before being discharged into the air. SUMMARY

[0003] The utility model discloses a kind of secondary combustion treatment systems of coke oven tail gas to solve the above problems.

[0004] To solve the technical problem, the utility model adopts the technical scheme that:

[0005] A kind of secondary combustion treatment system of coke oven tail gas, including burner and induced draft fan, the air inlet of induced draft fan is connected with gas inlet pipe, and the air outlet of induced draft fan is connected with the air inlet of burner;

[0006] It further includes gas mixing chamber, secondary combustion back gas pipeline, air inlet pipe, continuous emission monitoring system (CEMS) and control system, the air outlet of gas mixing chamber is connected with the air inlet of burner respectively, one end of secondary combustion back gas pipeline is connected with gas mixing chamber, the other end is connected with the air inlet of induced draft fan, the air inlet of induced draft fan is connected with air inlet pipe, first butterfly valve is equipped on the exhaust pipe of the air outlet of gas mixing chamber, sampling probe is equipped on the exhaust pipe of the air outlet of gas mixing chamber, pressure sensor is equipped on the exhaust pipe of first butterfly valve, second butterfly valve and gas flow sensor are equipped in secondary combustion back gas pipeline, third butterfly valve is equipped on air inlet pipe;

[0007] Continuous emission monitoring system is electrically connected with sampling probe, and control system is electrically connected with continuous emission monitoring system, first butterfly valve, pressure sensor, second butterfly valve, third butterfly valve and gas flow sensor respectively.

[0008] Further, heat exchanger is equipped between the air outlet of burner and the air inlet of gas mixing chamber, the heat exchanger is of shell-and-tube structure, and the shell side is communicated with the air outlet of burner, and the tube side is connected with cooling water circulation system

[0009] Further, redundancy sensor is equipped in the exhaust pipe close to first butterfly valve, and the redundancy sensor is of the same type as sampling probe.

[0010] Compared with the prior art, the utility model has the advantages of

[0011] 1、 the utility model discloses a secondary combustion back gas pipeline is set up, is used in combination with first butterfly valve and second butterfly valve, make the exhaust gas that does not reach the emission standard reenters the combustor and carries out secondary combustion, discharges after reaching the emission standard, reduces the pollution to the atmospheric environment;

[0012] 2、 the utility model discloses setting up heat exchanger before gas mixing chamber, makes exhaust gas reach normal temperature state when detecting, avoids damaging detection component part;

[0013] 3、 the utility model discloses being equipped with pressure sensor in the exhaust pipe of first butterfly valve, effectively prevents gas accumulation and breaks the pipe, avoids the occurrence of safety accident;

[0014] 4、 the utility model discloses being equipped with redundancy sensor in the exhaust pipe, verifies the detection result of sampling probe, to guarantee the reliability and safety of equipment in the operation process. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the structural schematic diagram of the utility model;

[0016] In the drawing: 1, coal gas inlet pipe;2, combustor;3, induced draft fan;4, gas mixing chamber;5, exhaust pipe;6, first butterfly valve;7, pressure sensor;8, sampling probe;9, secondary combustion back gas pipeline;10, redundancy sensor;11, second butterfly valve;12, air inlet pipe;13, third butterfly valve;14, heat exchanger;15, gas flow sensor. DETAILED DESCRIPTION

[0017] The utility model is further explained in connection with the drawings below.

[0018] As Figure 1 Shown, a coke oven exhaust gas's secondary combustion treatment system, including combustor 2 and induced draft fan 3, the air inlet of induced draft fan 3 is connected coal gas inlet pipe 1, and the air outlet of induced draft fan 3 is connected with the air inlet of combustor 2;

[0019] The gas mixing chamber 4 is connected with the air outlet of the burner 2 and the exhaust pipe 5, and a heat exchanger 14 is arranged between the burner 2 and the gas mixing chamber 4, wherein the heat exchanger 14 is of a shell-and-tube structure, the shell is communicated with the air outlet of the burner 2, and the tube is connected with a cooling water circulating system, so that the high-temperature gas is reduced to below 80 DEG C; one end of the secondary combustion back gas pipe 9 is connected with the gas mixing chamber 4, and the other end is connected with the air inlet of the induced draft fan 3; the air inlet pipe 12 is connected with the air inlet of the induced draft fan 3; the first butterfly valve 6 is arranged on the exhaust pipe 5, the redundant sensor 10 is arranged in the exhaust pipe 5 close to the first butterfly valve 6, the redundant sensor 10 is of the same type as the sampling probe 8, the sampling probe 8 is arranged on the exhaust pipe 5 at the air outlet of the gas mixing chamber 4, the pressure sensor 7 is arranged on the exhaust pipe 5 at the first butterfly valve 6, the second butterfly valve 11 and the gas flow sensor 15 are arranged on the secondary combustion back gas pipe 9, the third butterfly valve 13 is arranged on the air inlet pipe 12, the control system adopts a fuzzy PID algorithm, the opening degrees of the second butterfly valve 11 and the third butterfly valve 13 are dynamically adjusted according to the real-time flow data of the gas flow sensor 15 and the pollutant concentration feedback of the CEMS, and the back gas ratio is ensured to be less than or equal to 25%.

[0020] The continuous emission monitoring system is electrically connected with the sampling probe 8, and the control system is electrically connected with the continuous emission monitoring system, the first butterfly valve 6, the pressure sensor 7, the second butterfly valve 11, the third butterfly valve 13 and the gas flow sensor 15 respectively.

[0021] The fuzzy PID algorithm takes the pollutant concentration deviation (the difference between the CEMS detection value and the preset threshold value) and the deviation change rate as input variables, takes the opening adjustment amount of the second butterfly valve 11 and the third butterfly valve 13 as output variables, and dynamically optimizes the PID parameters through a fuzzy rule base.

[0022] Under the conditions that the calorific value of the coke oven gas is 18 MJ / m³ and the combustion temperature is greater than or equal to 1000 DEG C, when the back gas ratio is controlled to be 20%, the NO x The emission concentration is reduced from 800 ppm to 50 ppm, and the combustion efficiency is improved by 22%; when the tail gas is cooled to 50 DEG C, the service life of the sampling probe 8 is prolonged to 12 months.

[0023] When the system is put into use, the gas component threshold value in the emission standard is input into the control system, a preset pressure value is input into the pressure sensor 7, and a preset back gas flow value is input into the gas flow sensor 15.

[0024] When in use, coke oven gas is absorbed into the burner 2 from the gas inlet pipe 1 through the induced draft fan 3, and combustion is carried out in the burner 2. The tail gas after combustion is cooled by the tube-shell heat exchanger 14, and then enters the gas mixing chamber 4 after being reduced to below 80℃. The gas is discharged from the exhaust pipe 5, and the sampling probe 8 at the outlet detects the SO2, NO x , CO and other components in the tail gas, and the detected data are transmitted to the continuous emission monitoring system, and then to the control system for comparison and analysis with the preset values.

[0025] If the concentration of pollutants exceeds the preset threshold, the control system controls the first butterfly valve 6 to reduce the opening degree, and the second butterfly valve 11 to increase the opening degree. The gas in the gas mixing chamber 4 is absorbed from the induced draft fan 3 and returned to the burner 2 along the secondary combustion return gas pipe 9 for secondary combustion. The gas flow sensor 15 monitors the return gas flow value in the secondary combustion return gas pipe 9 in real time, and the control system dynamically adjusts the opening degree of the second butterfly valve 11 according to the concentration of pollutants in the return gas (from the CEMS), limiting the proportion of return gas flow in the burner 2 to ≤25%. If the proportion of non-compliant return gas flow introduced into the secondary combustion return gas pipe 9 is too high, it will dilute the concentration of fresh coke oven gas in the gas inlet pipe, resulting in a decrease in the fuel heat value in the burner 2 and an insufficient combustion temperature, making it difficult to fully decompose the pollutants. When the sampling probe 8 detects that the pollutant components in the exhaust gas exceed the standard, the control system preferentially increases the opening degree of the third butterfly valve 13 (supplementing air) rather than simply increasing the return gas flow, to avoid diluting the fuel concentration.

[0026] The tail gas produced after combustion is cooled again and enters the gas mixing chamber 4 to mix with the tail gas produced last time. The pollutant components in the tail gas after secondary combustion are eliminated, and the tail gas in the gas mixing chamber 4 is diluted. At this time, the sampling probe 8 detects the gas components in the exhaust pipe 5 again.

[0027] When the sampling probe 8 detects that the gas components in the exhaust pipe 5 meet the emission standard, the control system controls the first butterfly valve 6 to be fully open and the second butterfly valve 11 to be closed, and the tail gas is directly discharged.

[0028] When the second butterfly valve 11 is closed or has a small opening degree, the opening degree of the third butterfly valve 13 is controlled by the control system to be synchronously fully open or increased, to prevent the secondary combustion return gas pipe 9 from being absorbed by the induced draft fan 3 and damaged due to the closure of the second butterfly valve 11.

[0029] When the opening degree of the first butterfly valve 6 is small, the pressure sensor 7 monitors the gas pressure in real time. When the pressure sensor 7 detects that the pressure value exceeds the preset value, the first butterfly valve 6 is quickly opened until it is fully open, to prevent the exhaust pipe 5 from being damaged due to excessive gas pressure.

[0030] The high-temperature exhaust gas after combustion is cooled by the heat exchanger 14, ensuring that the detection element works within a safe temperature range, and avoiding damage to subsequent butterfly valves, pressure sensors, sampling probes and other components in a high-temperature environment, thereby prolonging the service life.

[0031] When the exhaust gas passes through the redundant sensor 10, the redundant sensor 10 collects the pollutant components in the exhaust gas again, analyzes the components, and verifies the results detected by the sampling probe 8, so as to ensure the reliability and safety of the equipment during operation.

Claims

1. A coke oven tail gas secondary combustion treatment system, comprising a burner (2) and an induced draft fan (3), the air inlet of the induced draft fan (3) being connected to a gas inlet pipe (1), and the air outlet of the induced draft fan (3) being connected to the air inlet of the burner (2); further comprising a gas mixing chamber (4), a secondary combustion return gas pipeline (9), an air inlet pipe (12), a continuous emission monitoring system and a control system, the gas mixing chamber (4) being connected to the air outlet of the burner (2) and an exhaust pipeline (5), one end of the secondary combustion return gas pipeline (9) being connected to the gas mixing chamber (4), and the other end being connected to the air inlet of the induced draft fan (3), the air inlet of the induced draft fan (3) being connected to the air inlet pipe (12), the exhaust pipeline (5) being provided with a first butterfly valve (6), the exhaust pipeline (5) at the air outlet of the gas mixing chamber (4) being provided with a sampling probe (8), the exhaust pipeline (5) at the first butterfly valve (6) being provided with a pressure sensor (7), the secondary combustion return gas pipeline (9) being provided with a second butterfly valve (11) and a gas flow sensor (15), and the air inlet pipe (12) being provided with a third butterfly valve (13); the continuous emission monitoring system being electrically connected to the sampling probe (8), and the control system being electrically connected to the continuous emission monitoring system, the first butterfly valve (6), the pressure sensor (7), the second butterfly valve (11), the third butterfly valve (13) and the gas flow sensor (15). characterized in that A heat exchanger (14) is arranged between the air outlet of the burner (2) and the air inlet of the gas mixing chamber (4), the heat exchanger (14) being of a shell-and-tube structure, the shell being connected to the air outlet of the burner (2), and the tubes being connected to a cooling water circulation system. A redundant sensor (10) is arranged in the exhaust pipeline (5) near the first butterfly valve (6), the redundant sensor (10) being of the same type as the sampling probe (8).

2. A system for the secondary combustion treatment of coke oven tail gas according to claim 1, characterized in that, ​ 3. A system for the secondary combustion treatment of coke oven tail gas according to claim 1, characterized in that, ​

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