A deep processing tail gas treatment and purification agent, device and method for coal tar

Abstract

The present invention discloses a purification agent, device and method for treating and purifying the tail gas from deep processing of coal tar, relating to the technical field of flue gas treatment. Using the vacuum tail gas from deep processing of coal tar as fuel gas, the fixed-bed dry desulfurization, denitrification and dust removal system includes a desulfurization and denitrification module. The desulfurization and denitrification module is connected to each boiler through a flue gas passage, and a high-efficiency composite desulfurization and denitrification purification agent is used in the desulfurization and denitrification module, with good flue gas desulfurization and denitrification effects.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal tar processing, and specifically discloses a tail gas treatment and purification agent, device and method for deep processing of coal tar. Background Art

[0002] High-temperature coal tar is one of the by-products in the crude gas generated by the pyrolysis of coal in the coking industry. Its composition is very complex, containing tens of thousands of compounds, mainly composed of aromatic hydrocarbons (especially polycyclic aromatic hydrocarbons), and also containing a small amount of phenols, heteroatom compounds (nitrogen, sulfur, oxygen), and high-molecular cyclic hydrocarbons, etc. The related products of coal tar deep processing are important raw materials for the production of plastics, synthetic fibers, dyes, rubber, pharmaceuticals, high-temperature resistant materials, electrodes, etc., and can be used to synthesize various industrial products such as insecticides, saccharin, dyes, drugs, and explosives. At present, the annual output of high-temperature coal tar in China is about 17 million tons. Most of the high-temperature coal tar is deeply processed and rectified to separate fractions such as phenol oil, naphthalene oil, wash oil, anthracene oil, and pitch, and then each fraction is separated and refined to produce chemical raw materials such as anthracene, naphthalene, phenol, and pitch. The vacuum distillation process is accompanied by a large amount of vacuum tail gas, including the vacuum tail gas of the tar distillation unit, the vacuum tail gas of the industrial naphthalene unit, the vacuum tail gas of the modified pitch unit, the vacuum tail gas of the refined phenol unit, the vacuum tail gas of the needle coke unit, etc. These vacuum tail gases have the characteristics of small gas volume, complex components, large fluctuations, high calorific value, obvious peculiar smell, and containing sulfur and nitrogen.

[0003] For the tail gas treatment technology in coal tar deep processing, the currently widely used method is to wash and cool through a venturi tube, a packed tower, etc. and then send it to an incinerator for incineration. This method can capture the oil and gas components in the tail gas to the greatest extent, but it can hardly remove organic sulfur substances such as COS and methanethiol in the tail gas; due to the small gas volume, high concentration, and low pressure of such tail gases, it is difficult to implement traditional methods such as COS hydrolysis, organic sulfur hydrogenation, adsorption, or alkali elution to remove hydrogen sulfide, and a large amount of solid waste such as hydrolysis agents and adsorbents or alkali residues will be generated, causing secondary pollution. Therefore, most coal tar processing enterprises mix this tail gas with other waste gases and then send it to the incinerator for incineration. The vacuum tail gas is treated as waste gas, and the calorific value is not fully utilized. Sulfur-containing substances such as H2S, COS, and methanethiol will become SO2, and the purpose of meeting the emission standards of incineration tail gas is achieved through dilution, causing serious pollution to the environment and bringing great environmental protection pressure to coal tar processing enterprises. Patent 202311059085.6 only conducts desulfurization treatment through pretreatment, with relatively high investment, complex process, large floor area, and high operation difficulty. A large amount of wastewater is generated during the process, and the absorption efficiency of the complex iron solution for COS and methanethiol is limited. The calorific value of the tail gas cannot be fully utilized, and the final nitrogen oxides may also be relatively high.

[0004] The magnesium oxide desulfurization process was developed in the 1880s and was first successfully applied in Japan. It has now become one of the main flue gas desulfurization processes in Japan. The representative process in the magnesium oxide wet desulfurization process is the magnesium oxide slurry washing - regeneration method. The main reactions of this process are as follows:

[0005] However, currently, the literature records that MgO cannot be used alone for desulfurization.

[0006] Yin Andong et al. recorded in "Characteristics of NO Removal by Pyrolytic Carbon from Sludge" that Fe2O3 without supported activated carbon cannot remove NO. Summary of the Invention

[0007] In view of the current situation and deficiencies in the treatment of vacuum tail gas from coal tar deep processing, the present invention proposes an energy-saving, resource comprehensive utilization, and environmentally friendly purification machine, method, and device for recycling tar deep processing vacuum tail gas as fuel gas, and at the same time, purification treatment is carried out to meet the requirements of ultra-low emissions of sulfides and nitrogen oxides. The present invention relates to a method and device for recycling and purifying vacuum tail gas from coal tar deep processing.

[0008] To achieve the above object, the present invention uses a high-efficiency composite desulfurization and denitrification purification agent. The purification agent includes the content of each component in weight percentage: 40% - 60% calcium hydroxide, 15% - 30% silicon dioxide, 10% - 20% aluminum oxide, 1% - 10% iron(III) oxide, and 1% - 5% magnesium oxide.

[0009] It includes a vacuum pump, a scrubbing tower, a safety water seal tank, an induced draft fan, a tubular heating furnace, and a tail purification device connected in sequence; the vacuum pump is connected to the coal tar processing device and separates the tail gas. The outlet of the vacuum pump is connected in series with the flue gas inlet of the scrubbing tower through a pipeline. The tail gas outlet of the scrubbing tower is connected to the tail gas of the safety water seal tank through a pipeline. The tail gas outlet of the safety water seal tank is connected to the inlet of the tubular furnace through a flame arrester. The outlet of the tubular furnace is connected to the inlet of the tail purification device. The tail gas after being treated by the tail purification device is discharged through a chimney connected to the tail gas outlet;

[0010] The tail purification device includes three fixed fluidized beds connected in series in sequence. Among them, the inlet of the first fixed fluidized bed is connected to the exhaust pipe of the tubular heating furnace. The outlet of the first fixed fluidized bed is connected to the inlet of the second fixed fluidized bed. The outlet of the second fixed fluidized bed is connected to the inlet of the third fixed fluidized bed. The outlet of the third fixed fluidized bed is connected to the chimney through a suction fan;

[0011] The three fixed fluidized beds are filled with the composite desulfurization and denitrification purification agent.

[0012] The tubular heating furnace includes a bottom burner and an exhaust pipe at the top. The bottom burner is connected to a flame arrester, and the exhaust pipe is connected to the outlet of the tail purification device. The upper ends of the fixed fluidized beds are all connected to a purifier loader, and a discharging device is arranged below the lower ends of the fixed fluidized beds. The discharging device includes a purification discharger arranged below the outlet end of the fixed fluidized bed, a discharging elevator connected to the end of the purification discharger, and a discharging collector connected to the upper end of the discharging elevator.

[0013] A method for treating tail gas in deep processing of coal tar specifically includes the following steps:

[0014] Step 1: Load a high-efficiency composite desulfurization and denitrification purifying agent into the solidified fluidized bed through a purifier loader. A vacuum pump separates the tail gas from the coal tar processing device, and the tail gas is washed in a scrubbing tower to absorb the macromolecules and liquid components in the tail gas.

[0015] Step 2: The tail gas washed in the scrubbing tower enters a safety water seal tank for gas-liquid separation, and at the same time serves as a safety water seal, that is, it reduces gas-liquid entrainment and also prevents backfire.

[0016] Step 3: The tail gas separated by the safety water seal tank passes through a draft fan and a flame arrester and is sent to the burner of the tubular heating furnace as fuel gas. It burns in the tubular heating furnace, and the burned tail gas is collected and discharged to the tail purification device.

[0017] Step 4: The tail gas discharged from the tubular heating furnace through the exhaust pipe after combustion treatment enters the solidified fluidized bed and reacts with the purifying agent. The purifying agent reacts with the combustion tail gas, and the reacted tail gas meets the emission requirements and is sent to the chimney for emission through a suction fan.

[0018] The purifying agent in Step 4 can react with nitrogen oxides and sulfur dioxide in the tail gas to complete desulfurization and denitrification.

[0019] After the reaction in the solidified fluidized bed in Step 4, the purifying agent is discharged through a purification discharging device, and then new purifying agent is loaded through a purifier loader.

[0020] Different from the prior art, the advantages of the present invention are as follows:

[0021] 1. The method of the present invention is a process of washing oil, incineration and tail gas purification treatment. First, incineration is carried out and then the incinerated tail gas is purified. It can fully recycle the calorific value of the tail gas. At the same time, the treatment of sulfides and nitrogen oxides at the end is more thorough, the emission concentration is lower, the sulfur dioxide in the flue gas does not exceed 10 mg / Nm 3 , the nitrogen oxides do not exceed 20 mg / Nm 3 , and the total non-methane hydrocarbons do not exceed 30 mg / Nm 3 , which is more conducive to reducing environmental pollution.

[0022] 2. The method of the present invention has simple process, convenient operation, stable operation and low investment. It makes full use of the process heating furnace in production without adding a new heating furnace. At the same time, the vacuum tail gas enters the burner through a single pipeline, which can avoid mixing with other tail gases to form explosive gases, and the operation is safe and reliable.

[0023] 3. The method of the present invention first uses wash oil for cleaning. The wash oil can be recycled in the coal tar processing system. At the same time, using the principle of similar solubility, it absorbs the macromolecular substances in the flue gas, solves the problem of incomplete combustion of macromolecular gases, then undergoes gas-liquid separation through a safety seal to avoid backfire, further passes through a flame arrester to prevent backfire when the gas volume is small, and passes through an induced draft fan to avoid problems of small gas volume and large pressure fluctuations, ensuring the stability of the tail gas reuse combustion.

[0024] 4. The method of the present invention adopts flue gas purification treatment after incineration. The flue gas purification treatment uses 3 series-connected fixed fluidized bed reactors, with two in use and one in reserve. The fixed fluidized bed uses granular high-efficiency dry purification agents to simultaneously remove sulfur dioxide and nitrogen oxides in the tail gas, realizing ultra-low emission of the tail gas. At the same time, the main component of the waste purification agent is calcium sulfate, which can be recycled as an effective resource without environmental pollution. Description of the Drawings

[0025] Figure 1 It is the process flow chart of the deep processing device for coal tar. Detailed Embodiments

[0026] The following further describes the present invention in conjunction with the detailed embodiments, and the protection scope of the present invention is not limited by the following embodiments.

[0027] Embodiment 1

[0028] As Figure 1 shown, a deep processing tail gas treatment device for coal tar includes a vacuum pump 1, a washing tower 2, a safety water seal tank 3, an induced draft fan 4, a tubular heating furnace 6, and a tail purification device connected in series in sequence; the vacuum pump 1 is connected to the coal tar processing device to separate the tail gas from the coal tar processing device. The outlet of the vacuum pump 1 is connected in series with the flue gas inlet of the washing tower 2 through a pipeline. The tail gas outlet of the washing tower 2 is connected to the tail gas of the safety water seal tank 3 through a pipeline. The tail gas outlet of the safety water seal tank 3 is connected to the inlet of the tubular heating furnace 6 through a flame arrester 5. The outlet of the tubular heating furnace 6 is connected to the inlet of the tail purification device. The tail gas after being treated by the tail purification device is discharged through a chimney 15 connected to the tail gas outlet;

[0029] The tubular heating furnace 5 includes a bottom burner 6-1 and an exhaust pipe 7 at the top. The bottom burner 6-1 is connected to the flame arrester 5, and the exhaust pipe 7 is connected to the outlet of the tail purification device;

[0030] The tail purification device includes three fixed fluidized beds 9 connected in series in sequence. Among them, the inlet of the first fixed fluidized bed is connected to the exhaust pipe 7 of the tubular heating furnace 6 of the tail purification device. The outlet of the first fixed fluidized bed is connected to the inlet of the second fixed fluidized bed, the outlet of the second fixed fluidized bed is connected to the inlet of the third fixed fluidized bed, and the outlet of the third fixed fluidized bed is connected to the chimney 15 through a suction fan 14.

[0031] The inlet ends of the fixed fluidized beds 9 of the tail purification device are all connected to the outlet of the purifier loader 10, and a discharging device is arranged below the outlet end of the fixed fluidized bed 9 of the tail purification device. The discharging device includes: a purification discharger 11 arranged below the outlet end of the fixed fluidized bed, a discharging elevator 12 connected to the end of the purification discharger 11, and a discharging collector 13 connected to the upper end of the discharging elevator 12.

[0032] An efficient composite desulfurization and denitrification purifying agent is arranged in the fixed fluidized bed 9. The efficient composite desulfurization and denitrification purifying agent includes the content of each component by weight percentage: 40%-60% of calcium hydroxide, 15%-30% of silicon dioxide, 10%-20% of aluminum oxide, 1%-10% of iron sesquioxide, and 1%-5% of magnesium oxide.

[0033] A method for treating the tail gas of deep processing of coal tar specifically includes the following steps:

[0034] Step 1: Load an efficient composite desulfurization and denitrification purifying agent into the fixed fluidized bed 9 through the purifier loader 10. The vacuum pump separates the tail gas of the coal tar processing device, and the tail gas is washed by the washing tower 2 to absorb the macromolecules and liquid components in the tail gas.

[0035] Step 2: The tail gas washed by the washing tower 2 enters the safety water seal tank 3 for gas-liquid separation, and at the same time plays a role of safety water seal, that is, reducing gas-liquid entrainment and preventing backfire.

[0036] Step 3: The tail gas separated by the safety water seal tank 3 passes through the induced draft fan 4 and the flame arrester 5 and is sent to the burner 6-1 of the tubular heating furnace 6 as fuel gas, burns in the tubular heating furnace 6, and the tail gas after combustion is collected and discharged to the tail purification device.

[0037] Step 4: The tail gas discharged from the exhaust pipe after the combustion treatment of the tubular heating furnace 6 enters the tail purification device to react with the purifying agent. The purifying agent reacts with the combustion tail gas, and the tail gas after the reaction meets the emission requirements and is sent to the chimney 15 for emission through the suction fan.

[0038] Preferably, the purifying agent in Step 4 can react with nitrogen oxides and sulfur dioxide in the tail gas to complete desulfurization and denitrification.

[0039] Preferably, after the reaction in the curing fluidized bed 9 in step 4, the purifying agent is discharged through the purifying unloading device 11 and then new purifying agent is loaded through the purifier loader 10.

[0040] Furthermore, the tail gas after combustion in the tubular heating furnace 6 contains sulfur dioxide (SO2), nitrogen oxides and CO polluting gases.

[0041] The sulfur dioxide (SO2) and nitrogen oxide contents in the waste gas are monitored at the exhaust outlet and inlet of the tail gas purification device. As shown in Table 1, the average removal rate of sulfur dioxide (SO2) is 99.8%, and the average removal rate of nitrogen oxides is 95%.

[0042] Table 1

[0043] Specifically, the principle of the fixed bed dry desulfurization and denitrification process:

[0044] SO2 in the tail gas after combustion reacts with active components such as calcium hydroxide and magnesium oxide in the purifying agent to form corresponding solid salts, thus achieving the purpose of desulfurization:

[0045] Ca(OH)2 + SO2 + 1 / 2O2 → CaSO4 + H2O

[0046] The present invention adopts a fixed fluidized bed. After the flue gas flows through, the sulfur dioxide therein is oxidized into sulfur trioxide and is reacted and solidified into calcium sulfate (gypsum) solid; water is not used throughout the process, nor is wastewater generated. The operation control process is only a simple step; the desulfurization effect can be adjusted according to the required contact time or the replacement frequency of the purifying agent, and 100% removal can be achieved. It is not sensitive to some short-term fluctuations in the flue gas composition and is also not sensitive to the flue gas temperature. It is suitable for almost all flue gas conditions, and the purifying agent has strong adaptability to the flue gas humidity;

[0047] Preferably, ammonia is not used in the denitrification of the fixed fluidized bed. Instead, the purifying agent is used for denitrification rather than an oxidant for direct chemical reaction denitrification; first, oxygen and nitric oxide in the flue gas catalytically react on the purifying agent to generate nitrogen dioxide, and the nitrogen dioxide will undergo a disproportionation reaction as follows in the presence of alkali and water: 3NO2 + H2O → 2HNO3 + NO;

[0048] 2NO + O2 → 2NO2;

[0049] 2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O

[0050] After calcium hydroxide, silicon dioxide, aluminum oxide, iron(III) oxide and magnesium oxide are fully mixed, a series of complex chemical reactions can occur under the action of water and alkali to generate a variety of hydrates with porous structures. Through drying and activation, it has a large specific surface area and certain alkalinity, thus having a good adsorption effect on nitrogen oxides.

[0051] The dry purification agent uses the above-mentioned high-efficiency composite desulfurization and denitrification purification agent, which is non-toxic and has no secondary pollution. It is a purification agent developed and produced for the catalytic oxidation method. It can oxidize NO to NO2 in a relatively wide and low temperature range (from room temperature to below 300 °C). The removal effect of NOx can be easily adjusted, and its removal rate can reach 95% or higher; the process is simple and easy to operate, and the investment and operation costs are relatively low. Since ammonia is not used, there is no safety hazard; dry catalytic denitrification is not sensitive to short-term fluctuations in flue gas composition and is also not sensitive to flue gas temperature, and is almost suitable for all flue gas conditions.

[0052] Example 2 Detection of the desulfurization and denitrification ability of the high-efficiency composite desulfurization and denitrification purification agent

[0053] The preparation of the high-efficiency composite desulfurization and denitrification purification agent with Al2O3 and SiO2 as carriers of the present invention includes the following steps:

[0054] (1) Preparation of the carrier: Mix the Al2O3 and SiO2 powders in a ratio of 1:1.5, grind and mix them evenly, then add them to a 1 - 1.5 mol / L dilute nitric acid solution, heat and stir in a water bath at 50 - 60 °C overnight to form an Al2O3 - SiO2 composite precipitate. After the precipitate is filtered by suction, add deionized water to wash it until the nitric acid is completely washed away; then dry it.

[0055] (2) Carrier pretreatment: Add the composite precipitate obtained in step (1) to a 1 - 1.5 mol / L NaOH or KOH solution for erosion. The solid - liquid ratio of the composite precipitate to the NaOH or KOH solution is 1:3. Then add deionized water to wash it, and then dry it in an oven. The structure of the treated composite precipitate is loose.

[0056] (3) Calcination: Heat the composite precipitate obtained in step (2) from room temperature to 250 - 260 °C at a rate of 2 - 5 °C / min; heat from 250 - 260 °C to 600 - 620 °C at a rate of 5 - 10 °C / min; heat from 600 - 620 °C to 1000 - 1050 °C at a rate of 10 - 12 °C / min; heat from 1000 - 1050 °C to 1500 - 1600 °C at a rate of 12 - 17 °C / min, and keep it at a constant temperature for 4 - 6 hours, then cool it naturally to room temperature to finally obtain the carrier.

[0057] (4) Preparation of the catalyst: Calcium hydroxide, iron(III) oxide, and magnesium oxide are added to a nitric acid solution to obtain an active ingredient solution. The support obtained in step (3) is immersed in the active ingredient solution, then washed with deionized water, and the impregnated support obtained is dried. Then, it is calcined at 500 - 600 °C and cooled to obtain a composite desulfurization and denitrification purifying agent. The mass ratios of calcium hydroxide, iron(III) oxide, and magnesium oxide to the mass of Al2O3 in the support are 3 - 4:1, 0.5 - 1:1, and 0.1 - 0.5:1, respectively.

[0058] Using the composite desulfurization and denitrification purifying agent as the experimental object, in the temperature range of 200 - 400 °C, with a space velocity of 15000 h -1 , the simulated flue gas composition is: 300 mg / m 3 NO, 4000 mg / m 3 SO2, 2000 mg / m 3 CO, 4000 mg / m 3 CO2, 2% O2, and the balance gas is N2. Under these conditions, the removal rate of SO2 reaches 99.8%, the removal rate of NO reaches 95.2%, and the removal rate of CO reaches 0%.

[0059] Detection of the desulfurization and denitrification ability of the composite desulfurization and denitrification purifying agent in Comparative Example 1

[0060] The preparation of the high-efficiency composite desulfurization and denitrification purifying agent with Al2O3 and SiO2 as the support according to the present invention includes the following steps:

[0061] (1) Preparation of the support: The Al2O3 and SiO2 powders are mixed in a ratio of 1:1.5, ground and mixed evenly, and then added to a 1 - 1.5 mol / L dilute nitric acid solution. The mixture is heated and stirred overnight in a water bath at 50 - 60 °C to form an Al2O3 - SiO2 composite precipitate. After filtration, the precipitate is washed with deionized water until the nitric acid is completely washed away; then it is dried.

[0062] (2) Support pretreatment: The composite precipitate obtained in step (1) is added to a 1 - 1.5 mol / L NaOH or KOH solution for etching. The solid - liquid ratio of the composite precipitate to the NaOH or KOH solution is 1:3. Subsequently, it is washed with deionized water and then dried. The structure of the treated composite precipitate is loose.

[0063] (3) Calcination: The composite precipitate obtained in step (2) is heated from room temperature to 250 - 260 °C at a rate of 2 - 5 °C / min; then heated from 250 - 260 °C to 600 - 620 °C at a rate of 5 - 10 °C / min; then heated from 600 - 620 °C to 1000 - 1050 °C at a rate of 10 - 12 °C / min, and then heated from 1000 - 1050 °C to 1500 - 1600 °C at a rate of 12 - 17 °C / min, and calcined at a constant temperature for 4 - 6 hours, and then naturally cooled to room temperature to finally obtain the carrier.

[0064] (4) Preparation of catalyst: Calcium hydroxide and magnesium oxide are added to the nitric acid solution to obtain an active ingredient solution. The carrier obtained in step (3) is immersed in the active ingredient solution, then washed with deionized water, and the impregnated carrier obtained is dried, and then calcined at 500 - 600 °C, and after cooling, a composite desulfurization and denitrification purifying agent is obtained. The mass ratios of calcium hydroxide and magnesium oxide to the mass of Al2O3 in the carrier are 3 - 4:1 and 0.1 - 0.5:1 respectively.

[0065] Taking the composite desulfurization and denitrification purifying agent as the experimental object, in the temperature range of 200 - 400 °C, the space velocity is 15000 h -1 , and the simulated flue gas composition is: 300 mg / m 3 NO, 4000 mg / m 3 SO2, 2000 mg / m 3 CO, 4000 mg / m 3 CO2, 2% O2, and the balance gas is N2. Under this condition, the removal rate of SO2 reaches 99.8%, the removal rate of NO reaches 0%, and the removal rate of CO reaches 0%.

[0066] Detection of desulfurization and denitrification ability of the composite desulfurization and denitrification purifying agent in Comparative Example 2

[0067] The preparation of the high-efficiency composite desulfurization and denitrification purifying agent using Al2O3 and SiO2 as the carrier according to the present invention includes the following steps:

[0068] (1) Preparation of carrier: The Al2O3 and SiO2 powders are prepared in a ratio of 1:1.5, then ground and mixed evenly, and then added to a 1 - 1.5 mol / L dilute nitric acid solution, and heated and stirred in a water bath at 50 - 60 °C overnight to form an Al2O3 - SiO2 composite precipitate. The precipitate is filtered by suction and then washed with deionized water until the nitric acid is completely washed away; then dried.

[0069] (2) Carrier pretreatment: Add the composite precipitate obtained in step (1) to a 1 - 1.5 mol / L NaOH or KOH solution for erosion. The solid - liquid ratio of the composite precipitate to the NaOH or KOH solution is 1:3. Subsequently, add deionized water for washing, and then dry. The structure of the treated composite precipitate is loose.

[0070] (3) Calcination: Heat the composite precipitate obtained in step (2) from room temperature to 250 - 260 °C at a rate of 2 - 5 °C / min; heat from 250 - 260 °C to 600 - 620 °C at a rate of 5 - 10 °C / min; heat from 600 - 620 °C to 1000 - 1050 °C at a rate of 10 - 12 °C / min; heat from 1000 - 1050 °C to 1500 - 1600 °C at a rate of 12 - 17 °C / min, and perform isothermal calcination for 4 - 6 hours, then naturally cool to room temperature to finally obtain the carrier.

[0071] (4) Preparation of catalyst: Add magnesium oxide to a nitric acid solution to obtain an active ingredient solution. Immerse the carrier obtained in step (3) into the active ingredient solution, then wash with deionized water, dry the impregnated carrier obtained, and then calcine at 500 - 600 °C. After cooling, a composite desulfurization and denitrification purifying agent is obtained. The mass ratio of magnesium oxide to Al2O3 in the carrier is 0.1 - 0.5:1.

[0072] Using the composite desulfurization and denitrification purifying agent as the experimental object, in the temperature range of 200 - 400 °C, with an airspeed of 15000 h -1 ,the simulated flue gas composition is: 300 mg / m 3 NO, 4000 mg / m 3 SO2, 2000 mg / m 3 CO, 4000 mg / m 3 CO2, 2% O2, with the balance gas being N2. Under this condition, the removal rate of SO2 reaches 95%, the removal rate of NO reaches 0%, and the removal rate of CO reaches 0%.

[0073] Detection of the desulfurization and denitrification ability of the composite desulfurization and denitrification purifying agent in Comparative Example 3

[0074] The preparation of the high - efficiency composite desulfurization and denitrification purifying agent using Al2O3 and SiO2 as carriers according to the present invention includes the following steps:

[0075] (1) Preparation of carrier: Mix Al2O3 and SiO2 powders in a ratio of 1:1.5, then grind and mix them evenly. Then add them to a 1 - 1.5 mol / L dilute nitric acid solution, and heat and stir in a water bath at 50 - 60 °C overnight to form an Al2O3 - SiO2 composite precipitate. After the precipitate is filtered by suction, add deionized water for washing until the nitric acid is completely washed away; then dry.

[0076] (2) Carrier pretreatment: Add the composite precipitate obtained in step (1) to a NaOH or KOH solution with a concentration of 1 - 1.5 mol / L for erosion. The solid-liquid ratio of the composite precipitate to the NaOH or KOH solution is 1:3. Subsequently, add deionized water for washing, and then dry. The structure of the treated composite precipitate is loose.

[0077] (3) Calcination: Heat the composite precipitate obtained in step (2) from room temperature to 250 - 260 °C at a rate of 2 - 5 °C / min; heat from 250 - 260 °C to 600 - 620 °C at a rate of 5 - 10 °C / min; heat from 600 - 620 °C to 1000 - 1050 °C at a rate of 10 - 12 °C / min; heat from 1000 - 1050 °C to 1500 - 1600 °C at a rate of 12 - 17 °C / min, and perform isothermal calcination for 4 - 6 hours, then naturally cool to room temperature to finally obtain the carrier.

[0078] (4) Preparation of catalyst: Add calcium hydroxide to a nitric acid solution to obtain an active ingredient solution. Immerse the carrier obtained in step (3) in the active ingredient solution, then wash with deionized water, dry the impregnated carrier obtained, and then calcine at 500 - 600 °C. After cooling, a composite desulfurization and denitrification purifying agent is obtained. The mass ratio of calcium hydroxide to Al2O3 in the carrier is 3 - 4:1.

[0079] Using the composite desulfurization and denitrification purifying agent as the experimental object, in the temperature range of 200 - 400 °C, with an airspeed of 15000 h -1 , the simulated flue gas composition is: 300 mg / m 3 NO, 4000 mg / m 3 SO2, 2000 mg / m 3 CO, 4000 mg / m 3 CO2, 2% O2, and the balance gas is N2. Under this condition, the removal rate of SO2 reaches 85%, the removal rate of NO reaches 0%, and the removal rate of CO reaches 0%.

[0080] Detection of desulfurization and denitrification ability of the composite desulfurization and denitrification purifying agent in Comparative Example 4

[0081] The preparation of the high-efficiency composite desulfurization and denitrification purifying agent using Al2O3 and SiO2 as carriers according to the present invention includes the following steps:

[0082] (1) Preparation of the support: Mix Al2O3 and SiO2 powders in a ratio of 1:1.5, grind and mix them evenly, then add them to a 1 - 1.5 mol / L dilute nitric acid solution, heat and stir in a water bath at 50 - 60 °C overnight to form an Al2O3 - SiO2 composite precipitate. After suction filtration, add deionized water to wash the precipitate until all the nitric acid is completely washed away; then dry it.

[0083] (2) Pretreatment of the support: Add the composite precipitate obtained in step (1) to a 1 - 1.5 mol / L NaOH or KOH solution for erosion. The solid - liquid ratio of the composite precipitate to the NaOH or KOH solution is 1:3. Subsequently, add deionized water to wash, and then dry. The structure of the treated composite precipitate is loose.

[0084] (3) Calcination: Heat the composite precipitate obtained in step (2) from room temperature to 250 - 260 °C at a rate of 2 - 5 °C / min; heat from 250 - 260 °C to 600 - 620 °C at a rate of 5 - 10 °C / min; heat from 600 - 620 °C to 1000 - 1050 °C at a rate of 10 - 12 °C / min; heat from 1000 - 1050 °C to 1500 - 1600 °C at a rate of 12 - 17 °C / min, and keep it at a constant temperature for calcination for 4 - 6 hours, then cool it naturally to room temperature to finally obtain the support.

[0085] (4) Preparation of the catalyst: Add calcium hydroxide and iron(III) oxide to a nitric acid solution to obtain an active ingredient solution. Immerse the support obtained in step (3) in the active ingredient solution, then wash it with deionized water, dry the impregnated support, and then calcine it at 500 - 600 °C. After cooling, a composite desulfurization and denitrification purifying agent is obtained. The mass ratio of calcium hydroxide to Al2O3 in the support is 3 - 4:1. The mass ratio of iron(III) oxide to Al2O3 in the support is 0.5 - 1:1.

[0086] Taking the composite desulfurization and denitrification purifying agent as the experimental object, in the temperature range of 200 - 400 °C, with a space velocity of 15000 h -1 , the simulated flue gas composition is: 300 mg / m 3 NO, 4000 mg / m 3 SO2, 2000 mg / m 3 CO, 4000 mg / m 3 CO2, 2% O2, and the balance gas is N2. Under this condition, the removal rate of SO2 reaches 85%, the removal rate of NO reaches 0%, and the removal rate of CO reaches 0%.

[0087] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating tail gas from coal tar deep processing, characterized in that: The specific steps include: Step 1: Load a high-efficiency composite desulfurization and denitrification purifier into the solidified fluidized bed through the purifier loader, separate the tail gas from the coal tar processing unit with a vacuum pump, and wash the tail gas through a washing tower to absorb the macromolecules and liquid components in the tail gas; Step 2: The tail gas after being cleaned by the cleaning tower enters the safety water seal tank for gas-liquid separation, which also acts as a safety water seal, reducing gas-liquid entrainment and preventing flashback; Step 3: The tail gas separated by the safety water seal tank is sent to the burner of the tubular heating furnace through the induced draft fan and the flame arrester, and is burned in the tubular heating furnace as fuel gas. After the tail gas is burned, it is collected and discharged to the tail purification device; Step 4: the tail gas discharged from the exhaust pipe after the combustion treatment in the tubular heating furnace enters the solidified fluidized bed to react with the purifier, and the purifier reacts with the combustion tail gas. The tail gas after the reaction meets the emission requirements and is sent to the chimney through the exhaust fan for emission; The step 4 is reacted in the temperature range of 200-400°C. The preparation of the composite desulfurization and denitrification purifier comprises the following steps: (1) preparing a carrier: Al2O3 and SiO2 powders are prepared in a ratio of 1:1.5, and then ground and mixed evenly, and then added to a 1-1.5 mol / L dilute nitric acid solution, and heated and stirred in a water bath at 50-60°C to react overnight to form an Al2O3-SiO2 composite precipitate, and the precipitate is filtered and washed with deionized water until the nitric acid is completely washed away; and then dried; (2) Carrier pretreatment: the composite precipitate obtained in step (1) is etched by adding 1-1.5 mol / L NaOH or KOH solution, wherein the solid-liquid ratio of the composite precipitate to the NaOH or KOH solution is 1:3, followed by washing with deionized water, and then drying, wherein the structure of the composite precipitate after treatment is loose; (3) Calcination: the composite precipitate obtained in step (2) is heated from room temperature to 250-260°C at a rate of 2-5°C / min; from 250-260°C to 600-620°C at a rate of 5-10°C / min; from 600-620°C to 1000-1050°C at a rate of 10-12°C / min, and from 1000-1050°C to 1500-1600°C at a rate of 12-17°C / min, and calcined at a constant temperature for 4-6 hours, and then naturally cooled to room temperature to finally obtain a carrier; (4) preparing a catalyst: adding calcium hydroxide, ferric oxide and magnesium oxide to a nitric acid solution to obtain an active ingredient solution, immersing the carrier obtained in step (3) in the active ingredient solution, then washing with deionized water, drying the impregnated carrier, and then calcining at 500-600° C., and cooling to obtain a composite desulfurization and denitrification purifier; The exhaust gas discharged through the exhaust pipe contains: 300 mg / m 3 NO, 4000mg / m 3 SO2, 2000 mg / m 3 CO, 4000 mg / m 3 CO2, 2%O2, N2.

2. The method for treating tail gas from coal tar deep processing according to claim 1, characterized in that: The purifier in step 4 reacts with nitrogen oxides and sulfur dioxide in the tail gas to complete desulfurization and denitrification.

3. The method for treating tail gas from coal tar deep processing according to claim 1, characterized in that: The purifier after the reaction in the solidified fluidized bed in step 4 is discharged through the purifier discharge device, and then new purifier is loaded through the purifier loader.

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