CN-121977219-A - Device and method for dephosphorizing flue gas of yellow phosphorus tail gas boiler

CN121977219ACN 121977219 ACN121977219 ACN 121977219ACN-121977219-A

Abstract

The invention relates to the technical field of phosphorus chemical industry and environmental protection, in particular to a device and a method for dephosphorizing flue gas of a yellow phosphorus tail gas boiler. The device adopts the gas boiler, the specific dephosphorization component, the waste heat boiler and the dust remover which are sequentially connected, so that the phosphoric acid content in high-temperature flue gas is effectively removed, the corrosion of phosphoric acid to equipment in the yellow phosphorus tail gas combustion process is avoided, the operation period of the gas boiler equipment is prolonged, the utilization rate of yellow phosphorus tail gas reaction heat is improved, superheated steam and low-pressure steam are byproducts, and meanwhile, dephosphorization ash residues are enriched, and the low-cost purification of yellow phosphorus tail gas phosphorus pollutants and boiler corrosion prevention are further realized.

Inventors

NIE YUNXIANG
MEI YI
Ma Peigen
DU QIANG
LI FUJIN
XIE DELONG

Assignees

昆明理工大学

Dates

Publication Date: 20260505
Application Date: 20260128

Claims (10)

1. The device for dephosphorizing the flue gas of the yellow phosphorus tail gas boiler is characterized by comprising a gas boiler (I), a dephosphorization component, a waste heat boiler (III) and a dust remover (IV) which are connected in sequence, wherein the dephosphorization component comprises a dephosphorization device (II) connected with the gas boiler (I), a feeder (V) and an ash collector (VI); The dephosphorization device (II) is used for enabling the high-temperature flue gas (03) to be in contact with a dephosphorization agent (05) and dephosphorizing to obtain dephosphorization flue gas (07), and obtaining tail gas (09) with P 2 O 5 content less than or equal to 5 mg/m 3 through a dust remover (IV) after the low-pressure steam (08) is generated by a byproduct of the waste heat boiler (III); Wherein, dephosphorization ware (II) is shell and tube heat exchanger, and built-in baffle (4) divide into dephosphorization portion and separation portion, and connect feeder (V) and ash collector (VI) respectively.
2. The apparatus according to claim 1, wherein the baffle (4) connects the top and the side walls of the dephosphorization (II) and does not connect the bottom of the dephosphorization (II); And/or the height ratio of the baffle (4) to the dephosphorizer (II) is 0.3-0.4:1; And/or the length ratio of the dephosphorization part to the dephosphorization device (II) is 0.6-0.8:1.
3. The apparatus according to claim 1 or 2, wherein the ratio of length, width and height of the dephosphorization device (II) is 2-3:0.7-0.9:1; and/or the length of the dephosphorization device (II) is more than or equal to 3m, preferably 3-4m; And/or the side wall of the dephosphorization device (II) is provided with a flue gas inlet (2) and a flue gas outlet.
4. A device according to any one of claims 1-3, wherein at least one parallel connected tubulation is arranged in the dephosphorization device (II), and each tubulation is connected to the top and bottom of the dephosphorization device (II), respectively; and/or the inner diameter of the tube array is 6-8cm; And/or the top of the dephosphorization device (II) is provided with a steam drum (3); and/or at least one lower header (1) is arranged at the bottom of the dephosphorization device (II); And/or, according to the material flowing direction, each tube array is respectively connected with a steam drum (3) and a lower header (1), the steam drum (3) is connected with a gas boiler (I) for carrying out heat recovery on process water filled in the tube array and the high-temperature flue gas (03), and the obtained steam is sent to the steam drum (3) to be converted into superheated steam (04) and is sent to the gas boiler (I), so that the temperature of the superheated steam (04) is 400-500 ℃ and the pressure is 2-3MPa.
5. The apparatus according to any of claims 1-4, wherein the vertical distance of the feeder (V) to the flue gas inlet of the dephosphorizer (II) is 0.2-0.4m, according to the material flow direction; and/or the bottom of the dephosphorization device (II) is provided with an ash collecting groove (5), and a screw (6) is preferably arranged in the ash collecting groove (5); And/or according to the material flow direction, the ash collector (VI) is connected with a feeder (V) and is used for returning dephosphorization ash as a circulating dephosphorization agent (010) and recycling the dephosphorization ash.
6. A method for dephosphorizing yellow phosphorus tail gas boiler flue gas, which is characterized by comprising the following steps: S1, burning yellow phosphorus tail gas (01) containing yellow phosphorus and phosphine with oxygen-containing gas (02) to obtain high-temperature flue gas (03) with the temperature of more than or equal to 400 ℃ and a heat byproduct superheated steam (04) released by burning; s2, contacting the high-temperature flue gas (03) with a dephosphorizing agent (05) and dephosphorizing to obtain dephosphorized flue gas (07) and dephosphorized ash; s3, heat recovery is carried out on the dephosphorization flue gas (07), low-pressure steam (08) as a byproduct is obtained, and tail gas (09) with the P 2 O 5 content less than or equal to 5 mg/m 3 is obtained through dust removal.
7. The method according to claim 6, wherein, in step S1, In the yellow phosphorus tail gas (01), the content of CO is 85-90vol.%, the content of P 4 is 100-800 mg/Nm 3 ,PH 3 and the content of P is 500-9000 mg/Nm 3 ; and/or, in the oxygen-containing gas (02), the O 2 content is not less than 20vol.%, preferably 20-100vol.%; And/or the temperature of the combustion is 750-1050 ℃, preferably 800-900 ℃; and/or the temperature of the high-temperature flue gas (03) is 400-500 ℃; And/or the temperature of the superheated steam (04) is 400-500 ℃ and the pressure is 2-3MPa.
8. The method according to claim 6 or 7, wherein, in step S2, The dephosphorizing agent (05) is selected from alkaline absorbent, preferably at least one selected from ground phosphate rock, coal ash, coal gangue and limestone; And/or the average particle diameter of the dephosphorizing agent (05) is less than or equal to 1mm, preferably 0.4-0.6mm.
9. The method according to any one of claims 6-8, wherein, in step S2, The ratio of the P content in kg/h of the dephosphorizing agent (05) to the P content in m 3 /h of the yellow phosphorus tail gas (01) is 1-15:1, preferably 3-9:1; And/or the mass flow rate of the dephosphorizing agent (05) is more than or equal to 25kg/h, preferably 40-100kg/h; And/or the volume flow of the yellow phosphorus tail gas (01) is more than or equal to 3000m 3 /h, preferably 4500-10000m 3 /h; And/or the temperature of the dephosphorization flue gas (07) is less than or equal to 350 ℃, preferably 180-300 ℃.
10. The method according to any one of claims 6-9, wherein, in step S3, The temperature of the low-pressure steam (08) is 120-150 ℃ and the pressure is 0.3-1MPa; And/or the temperature of the tail gas (09) is less than or equal to 100 ℃, preferably 80-90 ℃; And/or when the content of the dephosphorizing agent in the dephosphorizing ash is more than or equal to 30wt%, the dephosphorizing agent is recycled as a circulating dephosphorizing agent (010), otherwise, the dephosphorizing agent is directly discharged as waste residue (06).

Description

Device and method for dephosphorizing flue gas of yellow phosphorus tail gas boiler Technical Field The invention relates to the technical field of phosphorus chemical industry and environmental protection, in particular to a device for dephosphorizing the flue gas of a yellow phosphorus tail gas boiler and a method for dephosphorizing the flue gas of the yellow phosphorus tail gas boiler. Background The yellow phosphorus production capacity of China is about 150 ten thousand tons/year, and accounts for more than 80% of the world, the tail gas 2800-3200m 3 of yellow phosphorus byproduct per 1 ton is produced, the CO content is about 90%, the total amount of the end of the year gas is about 5.5X10 9m3, and the equivalent heat value is about 600 ten thousand tons of standard coal. However, the elemental phosphorus (also called yellow phosphorus, P 4) and phosphine (PH 3) in the yellow phosphorus tail gas are combusted and hydrated to generate phosphoric acid, and the phosphoric acid is converted into a liquid state after being contacted with the surface of a heat exchanger at a temperature lower than about 400 ℃, so that the phosphoric acid has strong corrosiveness (namely dew point corrosion) on metal materials, and becomes a key problem for utilizing the yellow phosphorus tail gas. At present, the yellow phosphorus tail gas boiler used in industry is mainly made of a low-temperature Duan Tu corrosion-resistant material so as to isolate the corrosion of phosphoric acid. For example, CN203203011U discloses a boiler for burning corrosion-resistant yellow phosphorus tail gas, and a nickel-chromium-molybdenum alloy coating is coated on the heated surface of the boiler to prevent the pipeline system of the boiler from being corroded. CN203203010U discloses a boiler for burning yellow phosphorus tail gas, the water-cooled wall surface of the water-cooled system of the hearth is a coating of anti-corrosion material. However, due to high temperature conditions and gas flushing, the effect of the anti-corrosion material is poor, so that pitting corrosion occurs on equipment, frequent shutdown and maintenance are required, and the operation and maintenance costs are high. Disclosure of Invention The invention aims to solve the problems that equipment is damaged, frequent shutdown and maintenance are needed, the maintenance cost is high, the utilization rate is low and the like caused by the corrosion of phosphoric acid generated by combustion of yellow phosphorus and phosphine contained in yellow phosphorus tail gas, and provides a device and a method for dephosphorizing flue gas of a yellow phosphorus tail gas boiler, which not only effectively avoid the corrosion of phosphoric acid in the combustion process of the yellow phosphorus tail gas, but also realize the reaction heat recovery, the phosphorus pollutant removal and the flue gas whitening of the yellow phosphorus tail gas. In order to achieve the aim, the first aspect of the invention provides a flue gas dephosphorization device of a yellow phosphorus tail gas boiler, which comprises a gas boiler, a dephosphorization part, a waste heat boiler and a dust remover which are sequentially connected, wherein the dephosphorization part comprises a dephosphorization device connected with the gas boiler, a feeder and an ash collector; the dephosphorization device is used for contacting the high-temperature flue gas with a dephosphorization agent and dephosphorizing to obtain dephosphorization flue gas, and obtaining tail gas with P 2O5 content less than or equal to 5 mg/m 3 through the dust remover after the dephosphorization flue gas is subjected to low-pressure steam by the waste heat boiler; Wherein, the dephosphorization device is a tube type heat exchanger, the built-in baffle plate is divided into a dephosphorization part and a separation part, and the dephosphorization part and the separation part are respectively connected with the feeder and the ash collector. The second aspect of the invention provides a method for dephosphorizing yellow phosphorus tail gas boiler flue gas, which comprises the following steps: S1, burning yellow phosphorus tail gas containing yellow phosphorus and phosphine with oxygen-containing gas to obtain high-temperature flue gas with the temperature of more than or equal to 400 ℃ and a heat byproduct superheated steam released by burning; s2, contacting the high-temperature flue gas with a dephosphorizing agent and dephosphorizing to obtain dephosphorized flue gas and dephosphorized ash; s3, carrying out heat recovery on the dephosphorized flue gas, and removing dust from the dephosphorized flue gas to obtain byproduct low-pressure steam, thereby obtaining tail gas with the P 2O5 content of less than or equal to 5 mg/m 3. Compared with the prior art, the invention has the following advantages: (1) The device provided by the invention adopts the gas boiler, the specific dephosphorization component, the waste heat boiler and the dust rem