Clean start-up method for bottom blowing oxidation furnace

Abstract

The invention belongs to the non-ferrous metal smelting industry, and discloses a clean starting method for a bottom blowing oxidation furnace. The method comprises the following main steps: preparation work before start-up of the bottom blowing oxidation furnace: the first start-up stage is the initial stage of molten pool making, and a lead grid is put into use to form a molten pool; the sulfur content and the feeding amount of the smelting raw materials are continuously increased according to the heating temperature of the five-section catalyst in the sulfuric acid converter; and in the later period of molten pool making at the third start-up stage, when the temperature of the five-stage catalyst in the sulfuric acid converter rises to the normal production temperature, a normal production formula is executed, and the bottom blowing oxidation furnace is started cleanly to complete production. Under the condition that equipment investment is not increased, the amount of sulfur dioxide flue gas generated in the start-up stage of the bottom-blowing oxidation furnace is matched with the temperature conversion capacity of the five-section catalyst of the sulfuric acid converter of the sulfuric acid conversion system, and the production problem that the index of sulfuric acid tail gas is abnormal in the start-up process of the bottom-blowing oxidation furnace is successfully solved; and the whole process of lead smelting clean start-up is realized.

Description

Technical Field

[0001] The present invention belongs to the non-ferrous metal smelting industry; specifically, it relates to a method for clean start-up of a bottom-blown oxidation furnace. Background Art

[0002] In the non-ferrous metal lead smelting industry, a large amount of SO2 flue gas is generated during lead smelting. Converting it into sulfuric acid through an acid-making device is one of the important links in non-ferrous metal lead smelting. Most acid-making devices adopt the "3+2" five-stage catalyst double conversion process of a sulfuric acid converter and the "III.I - V.IV.II" heat exchange process. The traditional start-up of a bottom-blown oxidation furnace mainly aims to meet the normal production of the oxidation furnace. When starting the furnace, a large amount of smelting raw materials are directly put in, resulting in a high concentration of sulfur dioxide flue gas during start-up. Since the temperature of the sulfuric acid converter has not fully risen in the initial stage of start-up, the sulfur dioxide conversion rate is low, and a large amount of sulfur dioxide is not converted and absorbed and enters the tail gas treatment system. Due to the limited ability of the tail gas treatment system to treat sulfur dioxide, the sulfur dioxide flue gas is directly discharged into the air, resulting in abnormal sulfuric acid tail gas emissions, that is, the amount of sulfur dioxide flue gas generated during the start-up stage of the bottom-blown oxidation furnace does not match the temperature conversion ability of the five-stage catalyst of the sulfuric acid converter in the sulfuric acid preparation system, leading to abnormal sulfuric acid tail gas emissions, which not only causes serious environmental pollution but also brings huge environmental protection pressure and economic losses to the enterprise. Summary of the Invention

[0003] In order to solve the problem of abnormal sulfur dioxide emissions in the tail gas of the sulfuric acid system during the start-up of the bottom-blown oxidation furnace, the present invention provides a method for clean start-up of the bottom-blown oxidation furnace. Without increasing equipment investment, by changing the process batching and start-up mode, the clean start-up of the bottom-blown oxidation furnace is successfully and stably realized, and the sulfur dioxide in the tail gas of the sulfuric acid system is stably discharged up to standard throughout the start-up process, providing a reference idea for lead smelting in the bottom-blown oxidation furnace in the industry and other related industries.

[0004] In order to solve the above problems, the technical solution of the present invention is as follows:

[0005] A method for clean start-up of a bottom-blown oxidation furnace, the method comprising the following steps:

[0006] S1: Start baking the bottom-blown oxidation furnace until the baking temperature reaches above 1200°C; the sulfuric acid preparation system heats the five-stage catalyst in the sulfuric acid converter to a preset temperature and keeps it warm to meet the start-up conditions of the bottom-blown oxidation furnace;

[0007] S2: The first stage of forming a molten pool: Put lead grids into the bottom-blown oxidation furnace, and the lead grids melt to form a molten pool; during this stage, the flue gas enters the first tail gas treatment system through a high-temperature fan, and the acid-making valve of the sulfuric acid preparation system is closed;

[0008] S3: Middle stage of the second-phase molten pool formation: Open the acid-making valve in the sulfuric acid system to allow flue gas to enter the sulfuric acid converter. When the pressure at the outlet of the electrostatic precipitator of the bottom-blowing oxidation furnace is between -200 Pa and -250 Pa, turn off the high-temperature fan; start feeding the smelting raw materials, and continuously increase the sulfur content and feeding amount of the smelting raw materials according to the temperature rise of the five-stage catalyst in the sulfuric acid converter. The sulfur content and feeding amount of the smelting raw materials are less than those in normal production.

[0009] S4: The third stage is the late stage of molten pool formation. When the temperature of the five-stage catalyst in the sulfuric acid converter rises to the normal production temperature, execute the normal production formula, and the clean start-up of the bottom-blowing oxidation furnace is completed.

[0010] Further, in step S1, the preset temperature of the five-stage catalyst is that the temperature of the first-stage catalyst rises to 410 - 420 °C, the temperature of the second-stage catalyst rises to 320 - 330 °C, and the temperature of the fourth-stage catalyst rises above 380 °C.

[0011] Further, in step S2, an oxygen lance is used in the bottom-blowing oxidation furnace. The oxygen lance includes a first oxygen lance and a second oxygen lance. The first oxygen lance feeds natural gas and oxygen. The natural gas and oxygen in the central pipe enter the bottom-blowing oxidation furnace through the annular pipe. The pressure of the natural gas is 0.3 - 0.5 MPa, and the pressure of the oxygen is 0.2 - 0.4 Mpa; the second oxygen lance feeds nitrogen and oxygen. The nitrogen and oxygen in the central pipe enter the bottom-blowing oxidation furnace through the annular pipe. The pressure of the nitrogen is 0.3 - 0.5 MPa, and the pressure of the oxygen is 0.2 - 0.4 Mpa;

[0012] In step S3, the first oxygen lance feeds natural gas and oxygen. The pressure of the natural gas is 0.5 - 0.9 Mpa, and the pressure of the oxygen is 0.5 - 0.9 Mpa; the second oxygen lance feeds nitrogen and oxygen. The pressure of the nitrogen is 0.5 - 0.9 Mpa, and the pressure of the oxygen is 0.5 - 0.9 Mpa;

[0013] In step S4, the first oxygen lance is removed from the bottom-blowing oxidation furnace; the second oxygen lance feeds nitrogen and oxygen. The pressure of the nitrogen is 0.9 - 1.0 Mpa, and the pressure of the oxygen is 0.9 - 1.0 Mpa.

[0014] Further, in step S2, before feeding the lead grid into the bottom-blowing oxidation furnace, the bottom of the bottom-blowing oxidation furnace is paved with charcoal or coke particles to prevent the lead grid from damaging the refractory.

[0015] Further, the lead content in the lead grid described in step S2 is above 90%, the feeding speed is 40 - 60 t / h, and the lead grid feeding amount is 40 - 80 t. A lead molten pool is formed in the bottom-blown oxidation furnace. The formation of the lead molten pool enables the bottom-blown oxidation furnace to form a stable temperature field. When the lead-containing smelting raw materials are fed in the middle stage of the second-stage molten pool formation, the bottom-blown oxidation furnace can quickly meet the temperature requirements for normal production, improving the reaction rate of the lead materials during the start-up of the cold-state oxidation furnace. Moreover, the molten pool of the present invention can also enable the sulfur-containing lead raw materials to be smelted to fully react, avoiding the situation that the lead materials sinter into lumps after baking and are not conducive to the reaction. At the same time, the formation of the molten pool not only ensures the temperature of the oxidation furnace but also enables the bottom-blown oxidation furnace to start up with a small amount of raw materials for smelting, ensuring that the sulfur dioxide content in the flue gas is effectively controlled and avoiding the large amount of raw materials fed directly after baking, which may lead to uncontrollable sulfur dioxide flue gas and abnormal sulfuric acid tail gas indicators during the start-up process.

[0016] Further, during the middle stage of the second-stage molten pool formation, the lead grade of the smelting raw materials is 38% - 43%, the sulfur content is 8% - 15%, the feeding amount is 30 - 75 t / h, and the oxygen-to-material ratio is 60 - 100 Nm 3 / t.

[0017] Further, according to the temperature rise of the five-stage catalyst in the sulfuric acid converter, the sulfur content and feeding amount of the smelting raw materials are continuously increased to make the sulfur dioxide flue gas volume generated during the start-up stage of the bottom-blown oxidation furnace match the temperature conversion capacity of the five-stage catalyst in the sulfuric acid converter of the sulfuric acid conversion system. The specific operation steps are as follows:

[0018] When the temperature of the first-stage catalyst in the sulfuric acid converter is 410 - 420 °C and the temperature of the fourth-stage catalyst is above 380 °C, Formula One is executed; the feeding amount of Formula One is set at 30 - 40 t / h, where the lead content is 38 - 40%, and the sulfur content is 8 - 9.5%; the oxygen-to-material ratio is 60 - 80 Nm 3 / t, and the sulfur dioxide content in the flue gas at the outlet of the oxidation furnace boiler is 1 - 2.8%;

[0019] When the temperature of the second-stage catalyst in the sulfuric acid converter is 410 - 420 °C and the temperature of the fifth-stage catalyst is 390 - 400 °C, Formula Two is executed; the feeding amount of Formula Two is set at 40 - 50 t / h; where the lead content is 41 - 43%, and the sulfur content is 9.5 - 10.5%; the oxygen-to-material ratio is 60 - 80 Nm 3 / t, and the sulfur dioxide content in the flue gas at the outlet of the oxidation furnace boiler is 3 - 4%;

[0020] When the temperature of the third stage in the sulfuric acid converter is above 380 °C, and at this time, all the five-stage catalyst layers in the sulfuric acid converter are basically heated up to above 380 °C, Formula Three is executed; the feeding amount of Formula Three is set at 50 - 65 t / h, where the lead content is 38 - 43%, and the sulfur content is 9.5 - 11%; the oxygen-to-material ratio is 80 - 100 Nm 3 / t, the flue gas at the outlet of the oxidation furnace boiler contains 8-12% sulfur dioxide;

[0021] The bottom-blown oxidation furnace can start up with a small amount of raw materials for smelting. When the activity of the five-stage catalyst in the sulfuric acid converter is not high, the sulfur dioxide concentration in the early stage is reduced. As the converter heats up, the ability of the five-stage catalyst in the sulfuric acid converter to convert sulfur dioxide in the flue gas into sulfur trioxide is improved. By controlling the bottom-blown oxidation furnace to increase the feeding amount of smelting raw materials and the sulfur content in the formula, the amount of sulfur dioxide flue gas generated during the start-up stage of the bottom-blown oxidation furnace is always matched with the amount of sulfur dioxide converted by the five-stage catalyst in the sulfuric acid converter of the sulfuric acid conversion system (temperature affects the conversion ability of the catalyst), achieving the effect of stable compliance discharge of sulfur dioxide in the sulfuric acid tail gas.

[0022] Further, the normal production temperatures of the five-stage catalyst in the sulfuric acid converter in step S4 are 408±2°C for the first-stage catalyst, 450±5°C for the second-stage catalyst, 420±5°C for the third-stage catalyst, 415±10°C for the fourth-stage catalyst, and 405±5°C for the fifth-stage catalyst.

[0023] Further, the set amount of the normal production formula feed is 65-75 t / h, where the lead content is 43-45%, the sulfur content is 10-15%; the oxygen-to-material ratio is 80-100 Nm 3 / t, and the flue gas at the outlet of the oxidation furnace boiler contains 12-14% sulfur dioxide.

[0024] Through the above technical solutions, the beneficial effects of this application are:

[0025] 1. Without increasing equipment investment, by controlling the feeding amount of the bottom-blown oxidation furnace and the sulfur content of the lead to be smelted according to the temperature of the five-stage catalyst in the sulfuric acid converter, the amount of sulfur dioxide flue gas generated during the start-up stage of the bottom-blown oxidation furnace is matched with the conversion ability of the five-stage catalyst temperature in the sulfuric acid converter of the sulfuric acid conversion system, successfully solving the production problem of abnormal sulfuric acid tail gas indicators during the start-up process of the bottom-blown oxidation furnace, realizing the whole process of clean start-up of lead smelting, having good reference significance for the treatment of sulfur dioxide in the sulfuric acid tail gas of other subsequent built bottom-blown oxidation furnace lead smelting and other non-ferrous metals, and having great popularization value for the clean production treatment of smelting enterprises of the same scale in the current industry.

[0026] 2. In the first stage of melting bath formation of the present invention, after the baking temperature of the bottom-blown oxidation furnace reaches above 1200 °C, no raw materials to be smelted are added in this stage. Instead, lead grids (lead content greater than 90%) are put into the bottom-blown oxidation furnace to form a lead melting bath. The formation of the lead melting bath enables the bottom-blown oxidation furnace to form a stable temperature field. When adding lead-containing smelting raw materials in the middle stage of the second stage of melting bath formation, the bottom-blown oxidation furnace can quickly meet the temperature requirements for normal production, improving the reaction rate of lead materials during the start-up of the cold oxidation furnace. Moreover, the melting bath of the present invention can also enable the sulfur-containing lead raw materials to be smelted to fully react, avoiding the situation that after baking, directly feeding the materials will cause the lead materials to sinter into lumps and be unfavorable for the reaction. At the same time, the formation of the melting bath not only ensures the temperature of the oxidation furnace but also enables the bottom-blown oxidation furnace to start smelting raw materials with a small amount of materials, ensuring that the sulfur dioxide content in the flue gas is effectively controlled and avoiding the large amount of materials fed directly after baking, which may lead to uncontrollable sulfur dioxide flue gas and abnormal sulfuric acid tail gas indicators during the start-up process.

[0027] 3. In the middle stage of the second stage of melting bath formation, the bottom-blown oxidation furnace can start smelting raw materials with a small amount of materials. When the activity of the five-stage catalyst in the sulfuric acid converter is not high, the sulfur dioxide concentration in the early stage is reduced. As the converter heats up, the ability of the five-stage catalyst in the sulfuric acid converter to convert sulfur dioxide in the flue gas into sulfur trioxide is improved. By controlling the bottom-blown oxidation furnace to increase the feeding amount of smelting raw materials and the sulfur content in the formula, the amount of sulfur dioxide flue gas generated during the start-up stage of the bottom-blown oxidation furnace is always matched with the amount of sulfur dioxide converted by the five-stage catalyst in the sulfuric acid converter of the sulfuric acid conversion system (temperature affects the conversion ability of the catalyst), achieving the effect of stable discharge of sulfur dioxide in the sulfuric acid tail gas up to the standard. Combining with the fact that in the first stage of melting bath formation, it not only ensures the normal temperature of the oxidation furnace but also ensures the stable discharge of sulfur dioxide in the sulfuric acid tail gas up to the standard, achieving the coordinated control of the bottom-blown oxidation furnace and the linkage operation of the sulfuric acid preparation system, realizing the process line of stable discharge of sulfur dioxide in the tail gas during the cold start-up of lead smelting, and having good environmental and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a process flow chart for treating lead smelting flue gas; DETAILED DESCRIPTION OF THE INVENTION

[0029] In the present invention, the flue gas generated by the oxidation furnace is divided into two types, one is sulfur-free flue gas and the other is sulfur-containing flue gas. Figure 1 It is a process flow chart for treating lead smelting flue gas; as Figure 1As shown in the figure, the process of sulfur-free flue gas is that the high-temperature flue gas generated by the oxidation furnace passes through the waste heat boiler for heat exchange and the electrostatic precipitator for dust collection, and then enters the tail gas absorption system I for treatment and is discharged outside. At this time, the sulfuric acid production valve is closed; for sulfur-containing flue gas, the sulfuric acid production valve is opened, the high-temperature fan is closed, and after the smelting raw materials are put in, the sulfur-containing flue gas generated by the oxidation furnace passes through the waste heat boiler for heat exchange and the electrostatic precipitator for dust collection, and then enters the sulfuric acid preparation system. In the sulfuric acid preparation system, the flue gas flows through the high-efficiency washing tower - packed tower - purification electrostatic precipitator - drying tower - converter - absorption tower. The converter undergoes a primary conversion, and the absorption tower undergoes a primary absorption. Then the flue gas enters the converter - absorption tower again for the secondary conversion of the converter and the secondary absorption of the absorption tower. The remaining flue gas passes through the tail gas absorption system II and is discharged outside after being treated by the electric demister.

[0030] The sulfuric acid production device for lead smelting flue gas includes a flue gas drying and purification system, a sulfuric acid conversion system (the conversion of sulfur dioxide to sulfur trioxide, the "3 + 2" five-stage catalyst double conversion process for the five-stage catalyst of the sulfuric acid converter and the heat exchange process of "III.I - V.IV.II"), and an absorption system (sulfur trioxide is absorbed by sulfuric acid and finally becomes 98% sulfuric acid). It is a relatively mature technology, and the waste heat boiler and electrostatic precipitator connected to the bottom-blown oxidation furnace are also relatively mature technologies. The present invention mainly changes the process batching and starting mode, so the equipment of the lead smelting system is not described in detail.

[0031] Example 1

[0032] A method for clean startup of a bottom-blown oxidation furnace includes the following steps:

[0033] S1: Before starting up the bottom-blown oxidation furnace, the feeding belt of the auxiliary equipment, the boiler, the electrostatic precipitator, the scraper, and the feeding system are operating normally; the bottom-blown oxidation furnace is strictly baked according to the refractory baking curve standard, and the baking temperature reaches above 1200 °C, meeting the feeding conditions;

[0034] The tail gas treatment system is operating normally; the tail gas treatment system I treats the sulfur dioxide-free flue gas, and the tail gas treatment system II treats the remaining flue gas after sulfur dioxide passes through the sulfuric acid converter and sulfuric acid absorption; at this stage, the sulfuric acid converter heats the air through an electric furnace, and the sulfuric acid blower circulates the hot air in the sulfuric acid converter to raise the temperature of each section of the catalyst in the converter to the corresponding temperature and keep it warm.

[0035] The temperature increase of the catalyst in the sulfuric acid converter: the temperature of the first-stage catalyst rises to 410 °C, the temperature of the second-stage catalyst rises to 365 °C, and the temperature of the fourth-stage catalyst rises to about 385 °C; when the temperature of the catalyst in the converter rises to the normal temperature, or when the temperature cannot continue to rise after adjustment, maintain the temperature of each section and notify the furnace to meet the startup conditions; at this time, the temperature of the third-stage catalyst rises to 200 °C, and the temperature of the fifth-stage catalyst rises to 340 - 350 °C.

[0036] S2 First stage of melting pool formation: Before the bottom-blown oxidation furnace is transferred in, 1t of charcoal or coke pellets is fed through the feeding port to cover the bottom to prevent the lead grid from damaging the refractory; after the charcoal or coke pellets are used up, the bottom-blown oxidation furnace is transferred to the correct position according to the converter procedure. The oxygen lance of the bottom-blown oxidation furnace is put into use. The oxygen lance includes a first oxygen lance and a second oxygen lance. The first oxygen lance introduces natural gas and oxygen. The natural gas and oxygen in the central pipeline enter the bottom-blown oxidation furnace through the annular pipeline. The pressure of the natural gas is 0.3 - 0.5MPa, and the pressure of the oxygen is 0.2 - 0.4Mpa; the second oxygen lance introduces nitrogen and oxygen. The nitrogen and oxygen in the central pipeline enter the bottom-blown oxidation furnace through the annular pipeline. The pressure of the nitrogen is 0.3 - 0.5MPa, and the pressure of the oxygen is 0.2 - 0.4Mpa; 6 oxygen lances are put into use in the bottom-blown oxidation furnace at this stage, including 3 first oxygen lances and 3 second oxygen lances; the lead grid enters the furnace through the belt via the feeding port. Pay attention to observing the melting speed of the lead grid in the furnace. The lead content in the lead grid is above 90%. Control the feeding speed of the lead grid at 40t / h, and the feeding amount of the lead grid is 53.2t. The flue gas enters the first tail gas treatment system through the high-temperature fan.

[0037] S3 Middle stage of the second stage of melting pool formation: After the feeding of the lead grid is completed and the lead grid is completely melted through the observation port to form a melting pool; open the acid-making valve of the sulfuric acid preparation system to allow the flue gas to enter the sulfuric acid conversion system. The sulfuric acid fan increases the air volume and reduces the air volume of the high-temperature fan. When the pressure at the outlet of the electrostatic precipitator of the bottom-blown oxidation furnace is between -200Pa and -250Pa, the high-temperature fan of the bottom-blown oxidation furnace is stopped using, and the smelting raw materials are started to be fed; continuously increase the sulfur content and feeding amount of the smelting raw materials according to the temperature rise of the five-stage catalyst in the sulfuric acid converter. The sulfur content and feeding amount of the smelting raw materials are less than those of the smelting raw materials during normal production; the specific operation steps are as follows:

[0038] When the temperature of the catalyst in the first stage of the converter is 410 - 420°C and the temperature of the catalyst in the fourth stage is above 380°C, the feed rate is set at 40t / h, and Formula 1 is executed; the feed rate of Formula 1 is set at 30 - 40t / h, where the lead content is 38 - 40%, and the sulfur content is 8 - 9.5%; the oxygen-to-feed ratio is 60 - 80Nm 3 / t, and the flue gas at the outlet of the boiler of the oxidation furnace contains 1 - 2.8% sulfur dioxide;

[0039] When the temperature of the catalyst in the second stage is 410 - 420°C and the temperature of the catalyst in the fifth stage is 390 - 400°C, the feed rate is set at 45t / h, and Formula 2 is executed; the feed rate of Formula 2 is set at 40 - 50t / h; where the lead content is 41 - 43%, and the sulfur content is 9.5 - 10.5%; the oxygen-to-feed ratio is 60 - 80Nm 3 / t, and the flue gas at the outlet of the boiler of the oxidation furnace contains 3 - 4% sulfur dioxide;

[0040] After 20 minutes, the feed rate is set at 50t / h, and Formulation Sheet 2 is executed;

[0041] The temperature of three sections is above 380°C. At this time, the five-section catalyst layer has basically been heated to above 380°C. The feed rate is set at 50 t / h, and Formula 3 is executed; for Formula 3, the feed rate is set at 50 - 65 t / h, with a lead content of 38 - 43% and a sulfur content of 9.5 - 11%; the oxygen-feed ratio is 80 - 100 Nm 3 / t, and the flue gas at the outlet of the oxidation furnace boiler contains 8 - 12% sulfur dioxide;

[0042] After 20 minutes, the feed rate is set at 55 t / h, and Batching Sheet 3 is executed;

[0043] After 20 minutes, the feed rate is set at 60 t / h, and Batching Sheet 3 is executed;

[0044] After 20 minutes, the feed rate is set at 65 t / h, and Batching Sheet 3 is executed;

[0045] In this stage, natural gas and oxygen are introduced into the first oxygen lance. The pressure of natural gas is 0.52 Mpa, and the pressure of oxygen is 0.6 Mpa; nitrogen and oxygen are introduced into the second oxygen lance. The pressure of nitrogen is 0.64 Mpa, and the pressure of oxygen is 0.6 Mpa; the temperature rise of the five-section catalyst in the sulfuric acid converter in this stage is based on the chemical reaction process of converting SO2 into SO3, and the heat released in this process heats the catalyst.

[0046] S4 Third stage, late stage of melting pool formation: Execute Formula 3. When the temperatures of the five-section catalyst in the sulfuric acid converter are 408 ± 2°C for the first-section catalyst, 450 ± 5°C for the second-section catalyst, 420 ± 5°C for the third-section catalyst, 415 ± 10°C for the fourth-section catalyst, and 405 ± 5°C for the fifth section, the feed rate is set at 65 t / h, and the normal production formula is executed. For the normal production formula, the feed rate is set at 65 - 75 t / h, with a lead content of 43 - 45% and a sulfur content of 10 - 15%; the oxygen-feed ratio is 80 - 100 Nm 3 / t, the flue gas at the outlet of the oxidation furnace boiler contains 12 - 14% sulfur dioxide, the conversion rate of sulfur dioxide flue gas is normal, and the sulfur dioxide in the sulfuric acid tail gas is stably discharged up to the standard; in the first oxygen lance of the bottom-blown oxidation furnace, natural gas is switched to nitrogen, and the pressure of nitrogen in the oxygen lance is 0.9 - 1.0 Mpa, and the pressure of oxygen is 0.9 - 1.0 Mpa; for the second oxygen lance, the pressure of nitrogen in the oxygen lance is 0.9 - 1.0 Mpa, and the pressure of oxygen is 0.9 - 1.0 Mpa. The clean start-up of the bottom-blown oxidation furnace is completed.

[0047] Example 2

[0048] A method for the clean start-up of a bottom-blown oxidation furnace, comprising the following steps:

[0049] S1: Before the bottom-blown oxidation furnace starts up, the feeding belt, boiler, electrostatic precipitator, scraper, and feeding system of the auxiliary equipment are operating normally; the bottom-blown oxidation furnace is strictly baked according to the refractory baking curve standard, and the baking temperature reaches above 1200°C, meeting the feeding conditions;

[0050] The tail gas treatment system is operating normally; the first tail gas treatment system processes flue gas without sulfur dioxide, and the second tail gas treatment system processes the remaining flue gas after sulfur dioxide is absorbed by the sulfuric acid converter and sulfuric acid absorption; in this stage, the sulfuric acid conversion system heats air through an electric furnace, and the sulfuric acid blower circulates hot air in the sulfuric acid converter to raise the temperature of the catalysts in each section of the converter to the corresponding temperature and keep it warm.

[0051] The temperature increase of the catalysts in the sulfuric acid converter: the temperature of the first-stage catalyst rises to 410 °C, the temperature of the second-stage catalyst rises to 365 °C, and the temperature of the fourth-stage catalyst rises to about 385 °C; when the temperature of the catalysts in the converter rises to the normal temperature, or when the temperature cannot continue to rise after adjustment, maintain the temperature of each section and notify the furnace to meet the starting conditions;; at this time, the temperature of the third-stage catalyst rises to 200 °C, and the temperature of the fifth-stage catalyst rises to 340-350 °C.

[0052] S2 First stage to build a molten pool: Before the bottom-blown oxidation furnace is transferred, 1t of charcoal or coke particles is put into the bottom through the feeding port to prevent the lead grid from damaging the refractory; after the charcoal or coke particles are used up, the bottom-blown oxidation furnace is transferred to the correct position according to the converter program, and the oxygen lance of the bottom-blown oxidation furnace is put into use. The oxygen lance includes a first oxygen lance and a second oxygen lance. The first oxygen lance introduces natural gas and oxygen. The natural gas and oxygen in the central pipeline enter the bottom-blown oxidation furnace together through the annular pipeline. The pressure of the natural gas is 0.4-0.44 MPa, and the pressure of the oxygen is 0.21-0.27 Mpa; the second oxygen lance introduces nitrogen and oxygen. The nitrogen and oxygen in the central pipeline enter the bottom-blown oxidation furnace together through the annular pipeline. The pressure of the nitrogen is 0.21 MPa, and the pressure of the oxygen is 0.21-0.27 Mpa; the lead grid enters the furnace through the belt and the feeding port. Pay attention to observing the melting speed of the lead grid in the furnace. The lead content in the lead grid is more than 90%, the feeding speed of the lead grid is 50t / h, and the feeding amount of the lead grid is 80t. The flue gas enters the first tail gas treatment system through the high-temperature blower.

[0053] S3 Second stage, middle stage of building a molten pool: After the lead grid is put into use and completely melted through the observation port to form a molten pool; open the sulfuric acid production valve of the sulfuric acid conversion system to allow the flue gas to enter the sulfuric acid conversion system and then enter the second tail gas treatment system. The sulfuric acid blower increases the air volume and reduces the amount of the high-temperature blower. When the pressure at the electric dust collector outlet of the bottom-blown oxidation furnace is between -200 Pa and -250 Pa, the high-temperature blower of the bottom-blown oxidation furnace is stopped, and the smelting raw materials are started to be fed; according to the temperature increase of the fifth-stage catalyst in the sulfuric acid converter, continuously increase the sulfur content and feeding amount of the smelting raw materials. The sulfur content and feeding amount of the smelting raw materials are less than those of the smelting raw materials during normal production; the specific operation steps are as follows: when the temperature of the first-stage catalyst in the converter is 410-420 °C and the temperature of the fourth-stage catalyst is above 380 °C, the feeding amount is set at 40t / h, and formula one is executed; the feeding amount of formula one is set at 30-40t / h, where the lead content is 38-40%, and the sulfur content is 8-9.5%; the oxygen-to-material ratio is 60-80 Nm 3 / t, the flue gas at the outlet of the oxidation furnace boiler contains 1 - 2.8% sulfur dioxide;

[0054] The temperature of the second-stage catalyst is 410 - 420 °C, the temperature of the fifth-stage catalyst is 390 - 400 °C, the feed rate is set at 48 t / h, and Formula Two is executed; the feed rate setting of Formula Two is 40 - 50 t / h; among which the lead content is 41 - 43%, and the sulfur content is 9.5 - 10.5%; the oxygen-feed ratio is 60 - 80 Nm 3 / t, the flue gas at the outlet of the oxidation furnace boiler contains 3 - 4% sulfur dioxide;

[0055] After 20 minutes, the feed rate is set at 50 t / h, and Batch Sheet Two is executed;

[0056] The temperature of the third stage is above 380 °C. At this time, the catalyst layers of all five stages have basically been heated up to above 380 °C. The feed rate is set at 56 t / h, and Formula Three is executed; the feed rate setting of Formula Three is 50 - 65 t / h, among which the lead content is 38 - 43%, and the sulfur content is 9.5 - 11%; the oxygen-feed ratio is 80 - 100 Nm 3 / t, the flue gas at the outlet of the oxidation furnace boiler contains 8 - 12% sulfur dioxide;

[0057] After 20 minutes, the feed rate is set at 65 t / h, and Batch Sheet Three is executed;

[0058] In the above stage, natural gas and oxygen are introduced into the first oxygen lance. The pressure of natural gas is 0.5 - 0.9 Mpa, and the pressure of oxygen is 0.5 - 0.9 Mpa; nitrogen and oxygen are introduced into the second oxygen lance. The pressure of nitrogen is 0.5 - 0.9 Mpa, and the pressure of oxygen is 0.5 - 0.9 Mpa; the temperature rise of the five-stage catalyst in the sulfuric acid converter in this stage is based on the chemical reaction process of converting SO2 into SO3. This process releases heat to raise the temperature of the catalyst. After the sulfur dioxide flue gas is converted and absorbed to produce sulfuric acid, the remaining flue gas enters the tail gas treatment system two.

[0059] S4 Third stage, late stage of melting pool formation: Execute Formula Three. When the temperatures of the five-stage catalysts in the sulfuric acid converter are 408 ± 2 °C for the first-stage catalyst, 450 ± 5 °C for the second-stage catalyst, 420 ± 5 °C for the third-stage catalyst, 415 ± 10 °C for the fourth-stage catalyst, and 405 ± 5 °C for the fifth stage, the feed rate is set at 70 t / h, and the normal production formula is executed. The feed rate setting of the normal production formula is 65 - 75 t / h, among which the lead content is 43 - 45%, and the sulfur content is 10 - 15%; the oxygen-feed ratio is 80 - 100 Nm 3 / t, the flue gas at the outlet of the oxidation furnace boiler contains 12 - 14% sulfur dioxide. The conversion rate of sulfur dioxide flue gas is normal, and the sulfur dioxide in the sulfuric acid tail gas is stably up to the standard for emission; in the first oxygen lance of the bottom-blown oxidation furnace, natural gas is switched to nitrogen, and the nitrogen pressure in the oxygen lance is 0.9 - 1.0 Mpa, and the oxygen pressure is 0.9 - 1.0 Mpa; for the second oxygen lance, the nitrogen pressure in the oxygen lance is 0.9 - 1.0 Mpa, and the oxygen pressure is 0.9 - 1.0 Mpa. The clean start-up of the bottom-blown oxidation furnace is completed.

[0060] The above-described embodiments are only preferred embodiments of the present invention, which are merely used to explain the present invention and do not limit the scope of implementation of the present invention. For those skilled in the art of this technology, of course, other implementation manners can be easily made by means of replacement or change according to the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. A method for cleaning and starting up a bottom-blown oxidation furnace, characterized in that, The method includes the following steps: S1: The bottom-blown oxidation furnace starts baking until the baking temperature reaches above 1200 °C; the sulfuric acid preparation system heats the five-stage catalyst in the sulfuric acid converter to a preset temperature and keeps it warm to meet the starting conditions of the bottom-blown oxidation furnace. S2: The first stage is the molten pool formation stage: Lead grids are put into the bottom-blown oxidation furnace, and the lead grids melt to form a molten pool; during this stage, the flue gas enters the first tail gas treatment system through a high-temperature fan, and the acid-making valve of the sulfuric acid preparation system is closed. S3: The middle stage of the second stage of molten pool formation: The acid-making valve of the sulfuric acid preparation system is opened to allow the flue gas to enter the sulfuric acid converter. When the pressure at the outlet of the electrostatic precipitator of the bottom-blown oxidation furnace is between -200 Pa and -250 Pa, the high-temperature fan is closed; starting to input smelting raw materials, the sulfur content and feeding amount of the smelting raw materials are continuously increased according to the rising temperature of the five-stage catalyst in the sulfuric acid converter, and the sulfur content and feeding amount of the smelting raw materials are less than those in normal production. S4: The third stage is the late stage of molten pool formation: When the temperature of the five-stage catalyst in the sulfuric acid converter rises to the normal production temperature, the normal production formula is executed, and the clean start-up of the bottom-blown oxidation furnace is completed.

2. The method for cleaning and starting up a bottom-blown oxidation furnace according to claim 1, characterized in that, In step S1, the preset temperature of the five-stage catalyst is that the temperature of the first-stage catalyst rises to 410 - 420 °C, the temperature of the second-stage catalyst rises to 320 - 330 °C, and the temperature of the fourth-stage catalyst rises to above 380 °C.

3. A method for clean start-up of a bottom-blown oxidation furnace according to claim 1, wherein in step S2, an oxygen lance is used in the bottom-blown oxidation furnace, and the oxygen lance includes a first oxygen lance and a second oxygen lance. The first oxygen lance introduces natural gas and oxygen, the pressure of natural gas is 0.3 - 0.5 MPa, and the pressure of oxygen is 0.2 - 0.4 Mpa; the second oxygen lance introduces nitrogen and oxygen, the pressure of nitrogen is 0.3 - 0.5 MPa, and the pressure of oxygen is 0.2 - 0.4 Mpa. In step S3, the first oxygen lance introduces natural gas and oxygen, the pressure of natural gas is 0.5 - 0.9 Mpa, and the pressure of oxygen is 0.5 - 0.9 Mpa; the second oxygen lance introduces nitrogen and oxygen, the pressure of nitrogen is 0.5 - 0.9 Mpa, and the pressure of oxygen is 0.5 - 0.9 Mpa. In step S4, the first oxygen lance of the bottom-blown oxidation furnace introduces nitrogen and oxygen, the pressure of nitrogen in the oxygen lance is 0.9 - 1.0 Mpa, and the pressure of oxygen is 0.9 - 1.0 Mpa; the second oxygen lance introduces nitrogen and oxygen, the pressure of nitrogen in the oxygen lance is 0.9 - 1.0 Mpa, and the pressure of oxygen is 0.9 - 1.0 Mpa.

4. A method for cleaning and starting up a bottom-blown oxidation furnace according to claim 1, characterized in that, In step S2, before putting lead grids into the bottom-blown oxidation furnace, charcoal or coke particles are used to line the bottom of the bottom-blown oxidation furnace.

5. A method for cleaning and starting up a bottom-blown oxidation furnace according to claim 1, characterized in that, In step S2, the lead content in the lead grids is above 90%, the feeding speed is 40 - 60 t / h, and the feeding amount of lead grids is 40 - 80 t.

6. A method for cleaning and starting up a bottom-blowing oxidation furnace according to claim 1, characterized in that, During the middle stage of the second stage of molten pool formation, the lead grade of the smelting raw materials is 38% - 43%, the sulfur content is 8% - 15%, the feeding amount is 30 - 75 t / h, and the oxygen-to-material ratio is 60 - 100 Nm³ / t.

7. A method for cleaning and starting up a bottom-blown oxidation furnace according to claim 1, characterized in that, According to the temperature rise of the five-stage catalyst in the sulfuric acid converter, continuously increase the sulfur content and feeding amount of the smelting raw materials. The specific operation steps are as follows: When the temperature of the first-stage catalyst in the sulfuric acid converter is 410 - 420 °C and the temperature of the fourth-stage catalyst is above 380 °C, implement Formula 1; the feed rate of Formula 1 is set at 30 - 40 t / h, where the lead content is 38 - 40%, the sulfur content is 8 - 9.5%; the oxygen-to-feed ratio is 60 - 80 Nm³ / t, and the sulfur dioxide content in the flue gas at the outlet of the oxidation furnace boiler is 1 - 2.8%; When the temperature of the second-stage catalyst in the sulfuric acid converter is 410 - 420 °C and the temperature of the fifth-stage catalyst is 390 - 400 °C, implement Formula 2; the feed rate of Formula 2 is set at 40 - 50 t / h; where the lead content is 41 - 43%, the sulfur content is 9.5 - 10.5%; the oxygen-to-feed ratio is 60 - 80 Nm³ / t, and the sulfur dioxide content in the flue gas at the outlet of the oxidation furnace boiler is 3 - 4%; When the temperature of the third stage in the sulfuric acid converter is above 380 °C, and at this time, the five-stage catalyst layers in the sulfuric acid converter are basically heated to above 380 °C, implement Formula 3; the feed rate of Formula 3 is set at 50 - 65 t / h, where the lead content is 38 - 43%, the sulfur content is 9.5 - 11%; the oxygen-to-feed ratio is 80 - 100 Nm³ / t, and the sulfur dioxide content in the flue gas at the outlet of the oxidation furnace boiler is 8 - 12%.

8. A method for cleaning and starting up a bottom-blown oxidation furnace according to claim 1, characterized in that, In step S4, the normal production temperatures of the five-stage catalysts in the sulfuric acid converter are 408 ± 2 °C for the first-stage catalyst, 450 ± 5 °C for the second-stage catalyst, 420 ± 5 °C for the third-stage catalyst, 415 ± 10 °C for the fourth-stage catalyst, and 405 ± 5 °C for the fifth-stage catalyst respectively.

9. A method for clean start-up of a bottom-blown oxidation furnace according to claim 1, characterized in that, The feed rate of the normal production formula is set at 65 - 75 t / h, where the lead content is 43 - 45%%, the sulfur content is 10 - 15%; the oxygen-to-feed ratio is 80 - 100 Nm³ / t, and the sulfur dioxide content in the flue gas at the outlet of the oxidation furnace boiler is 12 - 14%.

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