A safe treatment system and method for ferrous sulfide

Abstract

The present invention belongs to the field of chemical industry, and in particular, relates to a ferrous sulfide safety treatment system and treatment method. The ferrous sulfide safety treatment system provided by the present invention comprises: a nitrogen air intake pipeline, a compressed air air intake pipeline, a purge gas heater, a purge gas intake pipeline, and a purge gas discharge pipeline. The present invention configures a ferrous sulfide safety treatment system for the ferrous sulfide filter to be repaired, and can perform safe oxidation pretreatment on the ferrous sulfide inside the filter before the equipment is opened for repair, so that it is converted into iron oxide with more stable chemical properties, fundamentally solving the safety risks to people and chemical facilities caused by the spontaneous combustion of ferrous sulfide in contact with air.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry, and in particular relates to a ferrous sulfide safety treatment system and a treatment method. Background Art

[0002] In chemical plants, especially oil refining plants that use crude oil as the main processing raw material, due to the presence of active sulfur in the working medium, which mainly includes elemental active sulfur (S), hydrogen sulfide (H 2 S), due to its active chemical properties, it can directly react with metal pipes and containers to form metal sulfides. The reaction formula is as follows:

[0003] Fe+H 2 S (wet) → FeS + H 2 ↑.

[0004] The corrosion product of ferrous sulfide is dark brown or black solid and is insoluble in water. As the material flows during the operation of the device, it is continuously transferred from the upstream to the downstream of the device, and continuously accumulates and settles in a relatively low speed area, such as the filter and cecum section on the on-site process pipeline. When ferrous sulfide is heated or exposed to light in the air, it will spontaneously combust and the following reactions will occur:

[0005] FeS+3 / 2O 2 =FeO+SO 2 +49kJ;

[0006] 2FeO+1 / 2O 2 =Fe 2 O 3 +271kJ.

[0007] During the spontaneous combustion of ferrous sulfide, if there is no combustible material to support it, white SO will be produced. 2 Gas, often mistaken for water vapor, has a pungent odor and can cause health hazards if inhaled in excess. In this process, a large amount of heat is released. When there are other combustibles (such as oil) around, thick smoke will be emitted, causing fires and explosions. Therefore, in chemical plants, when inspecting and repairing equipment rich in ferrous sulfide, especially when cleaning filters, measures should be taken to prevent ferrous sulfide from spontaneous combustion.

[0008] like Figure 1The figure shows a ferrous sulfide filtration system commonly used in chemical plants. The filtration system has two sets of filters, one open and one standby during normal operation, that is, the air inlet and air outlet valves of one set of filters are fully open, and the air inlet and air outlet valves of the other set of filters are fully closed. When the filter resistance appears during operation and the device system needs to be cut out for maintenance and cleaning, first open the air inlet and air outlet valves of the standby set of filters, and then close the air inlet and air outlet valves of the filter to be repaired after the newly cut-in filter is put into use normally. The filter cut out of the system is depressurized and replaced before being delivered for maintenance.

[0009] At present, when cleaning filters rich in ferrous sulfide in chemical plants, steam or inert gas is mainly used to replace the combustible gas in the filter. After the filter temperature cooler temperature drops to room temperature (when replaced with steam purge), the equipment inspection port is opened to reduce the risk of spontaneous combustion of ferrous sulfide powder in contact with air after the filter inspection port is opened, causing the combustible gas to catch fire or even explode. This method can only reduce the risk of maintenance work to a certain extent, and cannot completely avoid the spontaneous combustion of ferrous sulfide. Especially in chemical plants, most of the surrounding process materials are flammable and explosive. Once the maintenance personnel open the filter that needs to be repaired, the spontaneous combustion of ferrous sulfide is uncontrollable, and a large amount of toxic gas SO is generated. 2 And high-temperature heat release phenomenon will cause great harm to surrounding workers and equipment facilities. Summary of the invention

[0010] In view of this, the purpose of the present invention is to provide a safe treatment system and method for ferrous sulfide. The treatment system provided by the present invention can perform safe oxidation pretreatment on the ferrous sulfide inside the ferrous sulfide filter before it is opened for maintenance, so as to convert it into iron oxide with more stable chemical properties, thereby fundamentally solving the safety risks to people and chemical facilities caused by spontaneous combustion of ferrous sulfide when it comes into contact with air.

[0011] The present invention provides a ferrous sulfide safety treatment system, comprising:

[0012] A nitrogen inlet pipeline, on which a nitrogen purge valve and a nitrogen flow meter are sequentially arranged along the airflow direction;

[0013] A compressed air intake pipeline, on which a compressed air purge valve and an air flow meter are arranged along the air flow direction;

[0014] A purge gas heater, wherein the air inlet of the purge gas heater is respectively connected to the air outlet end of the nitrogen air inlet pipeline and the air outlet end of the compressed air air inlet pipeline;

[0015] A purge gas inlet pipeline, on which a purge gas inlet thermometer and a purge gas inlet sampling point are arranged along the air flow direction, the inlet end of the purge gas inlet pipeline is connected to the outlet of the purge gas heater, the outlet end of the purge gas inlet pipeline is respectively connected to the inlet of each ferrous sulfide filter, and a purge gas inlet valve corresponding to the ferrous sulfide filter is arranged on the connecting pipeline;

[0016] A purge gas discharge pipeline is provided with a purge gas outlet thermometer and a purge gas outlet sampling point along the air flow direction. The air inlet end of the purge gas discharge pipeline is respectively connected to the air outlet of each ferrous sulfide filter, and a purge gas outlet valve corresponding to the ferrous sulfide filter is provided on the connecting pipeline.

[0017] The present invention provides a method for safely treating ferrous sulfide, and uses the ferrous sulfide safety treatment system described in the above technical solution to treat the ferrous sulfide filter to be repaired. The specific treatment process includes:

[0018] a) Cut out the ferrous sulfide filter to be repaired from the filtration system, open the corresponding purge gas outlet valve, and discharge the residual gas in the ferrous sulfide filter to the discharge point through the purge gas discharge pipeline;

[0019] b) Open the purge gas inlet valve corresponding to the ferrous sulfide filter to be repaired, open the nitrogen purge valve, and start nitrogen purging the filter to be repaired;

[0020] c) When the combustible gas content of the purge gas at the outlet of the ferrous sulfide filter to be repaired is lower than the set value, the purge gas heater is turned on to start heating the filter to be repaired; when the purge gas temperature at the inlet and outlet of the ferrous sulfide filter to be repaired reaches the set value, the compressed air purge valve is turned on to start adding air to the purge gas inlet, and with the addition of air, the ferrous sulfide in the ferrous sulfide filter to be repaired undergoes oxidation reaction and releases heat;

[0021] d) By adjusting the air intake ratio of the nitrogen air intake pipeline and the compressed air air intake pipeline, the oxygen content in the purge air intake is gradually increased; in this process, by adjusting the growth rate of the oxygen content in the purge air intake, the temperature rise rate of the purge air outlet at the outlet of the ferrous sulfide filter to be repaired is controlled to be lower than the set value;

[0022] e) When the oxygen content in the purge gas inlet increases to the set value, and the oxygen content at the outlet and inlet of the ferrous sulfide filter to be repaired is equal, and the sulfur dioxide content at the outlet of the ferrous sulfide filter to be repaired no longer increases, close the compressed air purge valve and stop the purge gas heater, and adjust the nitrogen purge valve to cool and purge the filter with nitrogen; when the purge gas outlet temperature of the ferrous sulfide filter to be repaired drops to the set value, and the SO 2After the content drops to the set value, close the nitrogen purge valve, and close the purge gas inlet valve and purge gas outlet valve corresponding to the ferrous sulfide filter to be repaired, and deliver the ferrous sulfide filter to be repaired for maintenance.

[0023] Preferably, in step c), the set value of the combustible gas content is ≤0.5 vol%.

[0024] Preferably, in step c), the set value of the purge gas temperature is 180-220°C.

[0025] Preferably, in step d), the set value of the temperature rise rate is ≤50°C / h.

[0026] Preferably, in step d), the specific process of gradually increasing the oxygen content in the purge gas inlet comprises:

[0027] d1) First, the oxygen content in the purge gas inlet will be gradually increased to 1~3vol%. With the increase of the oxygen content in the purge gas inlet, the ferrous sulfide in the ferrous sulfide filter to be repaired will undergo oxidation reaction and release heat, resulting in an increase in the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired;

[0028] d2) When the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired no longer rises and shows a downward trend, the oxygen content in the inlet of the purge gas will be gradually increased to 5~8vol%; along with the increase of the inlet oxygen content of the purge gas, the ferrous sulfide in the ferrous sulfide filter to be repaired continues to undergo oxidation reaction and release heat, resulting in an increase in the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired;

[0029] d3) When the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired no longer rises and shows a downward trend, the oxygen content in the purge gas inlet will be gradually increased to 12~15vol%; along with the increase in the oxygen content of the purge gas inlet, the ferrous sulfide in the ferrous sulfide filter to be repaired continues to undergo oxidation reaction and release heat, resulting in an increase in the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired;

[0030] d4) When the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired no longer rises and shows a downward trend, the oxygen content in the inlet purge gas will be gradually increased to 20~25vol%; along with the increase in the inlet oxygen content of the purge gas, the ferrous sulfide in the ferrous sulfide filter to be repaired continues to undergo oxidation reaction and release heat, resulting in an increase in the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired.

[0031] Preferably, in step e), the set value of the oxygen content is 20-25 vol%.

[0032] Preferably, in step e), the set value of the outlet temperature of the purge gas is ≤40°C.

[0033] Preferably, in step e), the SO 2 The set value of content is ≤15mg / m³.

[0034] Compared with the prior art, the present invention provides a ferrous sulfide safety treatment system and treatment method. The ferrous sulfide safety treatment system provided by the present invention comprises: a nitrogen inlet pipeline, on which a nitrogen purge valve and a nitrogen flow meter are sequentially arranged along the air flow direction; a compressed air inlet pipeline, on which a compressed air purge valve and an air flow meter are arranged along the air flow direction; a purge gas heater, the air inlet of the purge gas heater is respectively connected to the air outlet end of the nitrogen inlet pipeline and the air outlet end of the compressed air inlet pipeline; a purge gas inlet pipeline, on which a purge gas inlet thermometer and a purge gas inlet sampling point are arranged along the air flow direction, and the purge gas inlet The air inlet end of the air pipeline is connected to the air outlet of the purge gas heater, and the air outlet end of the purge gas inlet pipeline is respectively connected to the air inlet of each ferrous sulfide filter, and a purge gas inlet valve corresponding to the ferrous sulfide filter is arranged on the connecting pipeline; a purge gas discharge pipeline is provided with a purge gas outlet thermometer and a purge gas outlet sampling point along the air flow direction, and the air inlet end of the purge gas discharge pipeline is respectively connected to the air outlet of each ferrous sulfide filter, and a purge gas outlet valve corresponding to the ferrous sulfide filter is arranged on the connecting pipeline. The safe treatment method of ferrous sulfide provided by the present invention comprises the following processes: a) cutting the ferrous sulfide filter to be repaired out of the filtering system, opening the corresponding purge gas outlet valve, and discharging the residual gas of the ferrous sulfide filter to a discharge point through a purge gas discharge pipeline; b) opening the purge gas inlet valve corresponding to the ferrous sulfide filter to be repaired, opening the nitrogen purge valve, and starting to purge the filter to be repaired with nitrogen; c) when the combustible gas content of the purge gas outlet of the ferrous sulfide filter to be repaired is lower than a set value, opening the purge gas heater, and starting to heat up the filter to be repaired; when the purge gas temperature of the air inlet and the air outlet of the ferrous sulfide filter to be repaired reaches a set value, opening the compressed air purge valve, and starting to add air into the purge gas inlet, and along with the addition of air, the ferrous sulfide filter to be repaired is heated. The ferrous sulfide in the filter undergoes oxidation reaction and releases heat; d) By adjusting the air intake ratio of the nitrogen inlet pipeline and the compressed air inlet pipeline, the oxygen content in the purge air intake is gradually increased; in this process, by adjusting the growth rate of the oxygen content in the purge air intake, the temperature rise rate of the purge air outlet at the outlet of the ferrous sulfide filter to be repaired is controlled to be lower than the set value; e) When the oxygen content in the purge air intake is increased to the set value, and the oxygen content at the outlet and inlet of the ferrous sulfide filter to be repaired is equal, and the sulfur dioxide content at the outlet of the ferrous sulfide filter to be repaired no longer increases, the compressed air purge valve is closed and the purge air heater is stopped, and the nitrogen purge valve is adjusted to cool the filter with nitrogen; when the purge air outlet temperature of the ferrous sulfide filter to be repaired drops to the set value, and SO 2After the content is reduced to the set value, the nitrogen purge valve is closed, and the purge gas inlet valve and the purge gas outlet valve corresponding to the ferrous sulfide filter to be repaired are closed, and the ferrous sulfide filter to be repaired is delivered for repair. The present invention configures a set of ferrous sulfide safety treatment system for the ferrous sulfide filter to be repaired, and can perform safe oxidation pretreatment on the ferrous sulfide inside the filter before the equipment is opened for repair, so as to convert it into iron oxide with more stable chemical properties, fundamentally solving the safety risks to people and chemical facilities caused by the spontaneous combustion of ferrous sulfide in contact with air. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0036] Figure 1 It is a schematic diagram of a conventional ferrous sulfide filtration system provided by the present invention;

[0037] Figure 2 It is a schematic diagram of a ferrous sulfide filtering system connected to a ferrous sulfide safety treatment system provided by the present invention.

[0038] Explanation of the accompanying drawings: 1 is the first filter inlet valve, 2 is the first filter, 3 is the first filter outlet valve, 4 is the second filter inlet valve, 5 is the second filter, 6 is the second filter outlet valve, 7 is the nitrogen purge valve, 8 is the nitrogen flow meter, 9 is the compressed air purge valve, 10 is the air flow meter, 11 is the purge gas heater, 12 is the purge gas inlet thermometer, 13 is the purge gas inlet sampling point, 14 is the first filter purge gas inlet valve, 15 is the second filter purge gas inlet valve, 16 is the first filter purge gas outlet valve, 17 is the second filter purge gas outlet valve, 18 is the purge gas outlet thermometer, and 19 is the purge gas outlet sampling point. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] A ferrous sulfide safety treatment system matched with a ferrous sulfide filtration system, such as Figure 2 As shown:

[0042] (1) Ferrous sulfide filtration system includes:

[0043] The first filter 2 and the second filter 5 are arranged in parallel; the air inlet of the first filter 2 is connected to the first filter air inlet valve 1, and the air outlet is connected to the first filter air outlet valve 3; the air inlet of the second filter 5 is connected to the second filter air inlet valve 4, and the air outlet is connected to the second filter air outlet valve 6.

[0044] (2) The corresponding ferrous sulfide safety treatment system includes:

[0045] A nitrogen inlet pipeline, on which a nitrogen purge valve 7 and a nitrogen flow meter 8 are sequentially arranged along the airflow direction;

[0046] A compressed air intake pipeline, on which a compressed air purge valve 9 and an air flow meter 10 are arranged along the air flow direction;

[0047] A purge gas heater 11, wherein the air inlet of the purge gas heater 11 is respectively connected to the air outlet end of the nitrogen air inlet pipeline and the air outlet end of the compressed air air inlet pipeline;

[0048] A purge gas inlet pipeline is provided with a purge gas inlet thermometer 12 and a purge gas inlet sampling point 13 along the air flow direction, the inlet end of the purge gas inlet pipeline is connected to the outlet of the purge gas heater 11, and the outlet end of the purge gas inlet pipeline is connected to the inlets of the first filter 2 and the second filter 5, respectively, and the corresponding first filter purge gas inlet valve 14 and second filter purge gas inlet valve 15 are provided on the connecting pipeline;

[0049] A purge gas discharge pipeline is provided with a purge gas outlet thermometer 18 and a purge gas outlet sampling point 19 along the air flow direction. The air inlet end of the purge gas discharge pipeline is respectively connected to the air outlets of the first filter 2 and the second filter 5, and the corresponding first filter purge gas outlet valve 16 and second filter purge gas outlet valve 17 are provided on the connecting pipeline.

[0050] Example 2

[0051] A method for safely treating ferrous sulfide is provided, wherein the ferrous sulfide safe treatment system of Example 1 is used to treat the ferrous sulfide filter to be repaired; taking the ferrous sulfide filter to be repaired as the first filter 2 as an example, the specific process includes:

[0052] (1) When the first filter 2 in operation needs to be cut out of the ferrous sulfide filtration system for inspection and cleaning, firstly, the first filter 2 is cut out of the ferrous sulfide filtration system according to the normal process (open the second filter air inlet valve 4 and the second filter air outlet valve 6, close the first filter air inlet valve and the first filter air outlet valve 3), open the first filter purge gas outlet valve 16, and discharge the residual gas in the first filter 2 to the discharge point through the purge gas discharge pipeline;

[0053] (2) Open the first filter purge gas inlet valve 14, open the nitrogen purge valve 7 (nitrogen content ≥ 98 vol%), and start nitrogen purging the first filter 2;

[0054] (3) When the combustible gas content of the purge gas at the outlet of the first filter 2 is less than 0.5 vol%, the purge gas heater 11 is turned on to start heating the first filter 2; when the purge gas temperature at the inlet and outlet of the first filter 2 reaches 200°C, the compressed air purge valve 9 is slightly opened to start adding air (the oxygen content in the compressed air is about 22 vol%) to the purge gas inlet. As the air is added, the ferrous sulfide in the first filter 2 undergoes an oxidation reaction and releases heat;

[0055] (4) The oxygen content in the purge gas intake is gradually increased to 2 vol% by the nitrogen flow meter 8 and the air flow meter 10. As the oxygen content in the purge gas intake increases, the ferrous sulfide in the first filter 2 undergoes an oxidation reaction and releases heat, causing the purge gas outlet temperature at the first filter 2 outlet to increase. During this process, pay close attention to the temperature rise of the purge gas outlet at the first filter 2 outlet. The temperature rise rate should be controlled below 30°C / h and should not exceed 50°C / h. If the temperature rises too quickly, cut off the air to cool it down.

[0056] (5) When the outlet temperature of the purge gas at the outlet of the first filter 2 stops rising and shows a downward trend, the oxygen content in the inlet of the purge gas will be gradually increased to 5-8 vol%. During this process, pay close attention to the temperature rise of the outlet of the purge gas at the outlet of the first filter 2, and the temperature rise rate should be controlled below 30°C / h.

[0057] (6) When the outlet temperature of the purge gas at the outlet of the first filter 2 no longer rises and shows a downward trend, the oxygen content in the inlet of the purge gas will be gradually increased to 12~15vol% (the amount of nitrogen can be appropriately reduced); during this process, pay close attention to the temperature rise of the outlet of the purge gas at the outlet of the first filter 2, and the temperature rise rate should be controlled below 30℃ / h;

[0058] (7) When the outlet temperature of the purge gas at the outlet of the first filter 2 no longer rises and shows a downward trend, the oxygen content in the inlet of the purge gas will be gradually increased to 20~25vol% (the amount of nitrogen can be appropriately reduced); during this process, pay close attention to the temperature rise of the outlet of the purge gas at the outlet of the first filter 2, and the temperature rise rate should be controlled below 30℃ / h;

[0059] (8) When the oxygen content at the outlet and inlet of the first filter 2 is equal, and the sulfur dioxide content at the outlet of the first filter 2 no longer increases, close the compressed air purge valve 9 and stop the purge gas heater 11, and appropriately open the nitrogen purge valve 7 to purge the first filter 2 with nitrogen to cool it down; when the outlet temperature of the purge gas at the outlet of the first filter 2 drops to 40°C and the SO2 content in the purge gas is 2 After the content is reduced to the safety limit accepted by the human body (15 mg / m³), close the nitrogen purge valve 7, and close the first filter purge gas inlet valve 14 and the first filter purge gas outlet valve 16, and deliver the first filter 2 for maintenance.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for safely handling ferrous sulfide, characterized in that: The ferrous sulfide safety treatment system is used to treat the ferrous sulfide filter to be repaired, and the ferrous sulfide safety treatment system includes: A nitrogen inlet pipeline, on which a nitrogen purge valve and a nitrogen flow meter are sequentially arranged along the airflow direction; A compressed air intake pipeline, on which a compressed air purge valve and an air flow meter are arranged along the air flow direction; A purge gas heater, wherein the air inlet of the purge gas heater is respectively connected to the air outlet end of the nitrogen air inlet pipeline and the air outlet end of the compressed air air inlet pipeline; A purge gas inlet pipeline, on which a purge gas inlet thermometer and a purge gas inlet sampling point are arranged along the air flow direction, the inlet end of the purge gas inlet pipeline is connected to the outlet of the purge gas heater, the outlet end of the purge gas inlet pipeline is respectively connected to the inlet of each ferrous sulfide filter, and a purge gas inlet valve corresponding to the ferrous sulfide filter is arranged on the connecting pipeline; A purge gas discharge pipeline is provided with a purge gas outlet thermometer and a purge gas outlet sampling point along the air flow direction, the air inlet end of the purge gas discharge pipeline is respectively connected to the air outlet of each ferrous sulfide filter, and a purge gas outlet valve corresponding to the ferrous sulfide filter is provided on the connecting pipeline; The specific processing process includes: a) Cut out the ferrous sulfide filter to be repaired from the filtration system, open the corresponding purge gas outlet valve, and discharge the residual gas in the ferrous sulfide filter to the discharge point through the purge gas discharge pipeline; b) Open the purge gas inlet valve corresponding to the ferrous sulfide filter to be repaired, open the nitrogen purge valve, and start nitrogen purging the filter to be repaired; c) When the combustible gas content of the purge gas at the outlet of the ferrous sulfide filter to be repaired is lower than the set value, the purge gas heater is turned on to start heating the filter to be repaired; when the purge gas temperature at the inlet and outlet of the ferrous sulfide filter to be repaired reaches the set value, the compressed air purge valve is turned on to start adding air to the purge gas inlet, and with the addition of air, the ferrous sulfide in the ferrous sulfide filter to be repaired undergoes oxidation reaction and releases heat; d) By adjusting the air intake ratio of the nitrogen air intake pipeline and the compressed air air intake pipeline, the oxygen content in the purge air intake is gradually increased; in this process, by adjusting the growth rate of the oxygen content in the purge air intake, the temperature rise rate of the purge air outlet at the outlet of the ferrous sulfide filter to be repaired is controlled to be lower than the set value; e) When the oxygen content in the purge gas inlet increases to the set value, and the oxygen content at the outlet and inlet of the ferrous sulfide filter to be repaired is equal, and the sulfur dioxide content at the outlet of the ferrous sulfide filter to be repaired no longer increases, close the compressed air purge valve and stop the purge gas heater, and adjust the nitrogen purge valve to purge the filter with nitrogen to cool it down; when the purge gas outlet temperature at the outlet of the ferrous sulfide filter to be repaired drops to the set value, and the SO2 content in the purge gas outlet drops to the set value, close the nitrogen purge valve, and close the purge gas inlet valve and purge gas outlet valve corresponding to the ferrous sulfide filter to be repaired, and deliver the ferrous sulfide filter to be repaired for repair.

2. The method for safe treatment of ferrous sulfide according to claim 1, characterized in that: In step c), the set value of the combustible gas content is ≤0.5 vol%.

3. The method for safe treatment of ferrous sulfide according to claim 1, characterized in that: In step c), the set value of the purge gas temperature is 180-220°C.

4. The method for safe treatment of ferrous sulfide according to claim 1, characterized in that: In step d), the set value of the temperature rise rate is ≤50°C / h.

5. The method for safe treatment of ferrous sulfide according to claim 1, characterized in that: In step d), the specific process of gradually increasing the oxygen content in the purge gas inlet includes: d1) First, the oxygen content in the purge gas inlet will be gradually increased to 1~3vol%. With the increase of the oxygen content in the purge gas inlet, the ferrous sulfide in the ferrous sulfide filter to be repaired will undergo oxidation reaction and release heat, resulting in an increase in the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired; d2) When the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired no longer rises and shows a downward trend, the oxygen content in the inlet of the purge gas will be gradually increased to 5~8vol%; along with the increase of the inlet oxygen content of the purge gas, the ferrous sulfide in the ferrous sulfide filter to be repaired continues to undergo oxidation reaction and release heat, resulting in an increase in the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired; d3) When the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired no longer rises and shows a downward trend, the oxygen content in the purge gas inlet will be gradually increased to 12~15vol%; along with the increase in the oxygen content of the purge gas inlet, the ferrous sulfide in the ferrous sulfide filter to be repaired continues to undergo oxidation reaction and release heat, resulting in an increase in the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired; d4) When the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired no longer rises and shows a downward trend, the oxygen content in the purge gas inlet will be gradually increased to 20~25vol%; along with the increase in the oxygen content of the purge gas inlet, the ferrous sulfide in the ferrous sulfide filter to be repaired continues to undergo oxidation reaction and release heat, resulting in an increase in the outlet temperature of the purge gas at the outlet of the ferrous sulfide filter to be repaired.

6. The method for safe treatment of ferrous sulfide according to claim 1, characterized in that: In step e), the oxygen content is set to a value of 20-25 vol%.

7. The method for safe treatment of ferrous sulfide according to claim 1, characterized in that: In step e), the set value of the outlet temperature of the purge gas is ≤40°C.

8. The method for safe treatment of ferrous sulfide according to claim 1, characterized in that: In step e), the set value of the SO2 content in the outlet gas of the purge gas is ≤15 mg / m³.

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