Cooperation Separation And Conversion Of Dust And Sulfurous Phosphorus Impurities From Yellow Phosphorus Gas By Corona Discharge

Yellow phosphorus is a kind of important chemical products. The capacity and production of yellow phosphorus of our country occupy first in the world, and the electric furnace is main manufacturing process. The main components of the yellow phosphorus furnace gas are phosphorus steam, CO, dust and some impurities. Dust and impurities must be removed for yellow phosphorus production and resource utilization of tail gas. Wet cleaning is the main method to remove the dust from the furnace gas, which resulting mass of phosphorus sludge. It is costly and should consume a lot of energy and water for recycling phosphorus from phosphorus sludge. Not only that, wastewater containing phosphorus is produced in the treatment of phosphorus sludge. After dedusting, yellow phosphorus tail gas contains 85%-95% CO, which can be used as a heat source or a carbon chemical raw material gas. However the dust and sulfurous phosphorus impurities, such as COS, PH₃, H₂S, will corrode equipment and affect the quality of the raw material gas. So purification of the yellow phosphorus gas is very important for clean production, environmental protection and resource utilization. A series of technologies were combined to separation and conversion of dust and sulfurous phosphorus from yellow phosphorus gas, including wet cleaning, alkali washing, adsorbing and catalyzing. However, there are some disadvantages for combined technologies step by step:the technological complexity, the long craft route and problems resulted from coexistent matters. It is significant to develop a synthetical and simple technology for purification of the yellow phosphorus gas to promote clean production of phosphorus gas and resource utilization of tail gas.Corona discharge is one of gas discharge technologies, which can generate a large of high-energy electrons. Dust particles charged can be collected in the electric field and COS, PH₃, H₂S can be conversed by electron collision based on the characteristic of corona discharge. Besides, interaction may occur between dust and gas impurities with corona discharge to make the conversion easier and reduce the by-productions. In this way, the goals of cooperation separation and conversion of dust and sulfurous phosphorus from yellow phosphorus gas will be achieved, which will simplify process.The pipe style corona discharge reactor, gas system and dust simulator were employed to study the effect of cooperation separation and conversion. The focus of the thesis were mainly on the conversion, pathway and mechanism of COS, PH₃ and H₂S by corona discharge, the effect of cooperation separation and conversion of dust and sulfurous phosphorus by corona discharge, and the influences of corona discharge conductions on separation and conversion.Results and conclusions are as follows:?1? COS, PH₃ and H₂S can be converted by corona discharge effectively. The efficiency of COS, PH₃ and H₂S were 80%,100% and 100% with inlet concentration of 1120 ppm,1080 ppm and 1140 ppm, O₂ content of 0.1% and SIE of 806 J/L at room temperature and relative humidity of 23%. The conversion easiness of COS, PH₃ and H₂S by corona discharge were:PH₃> H₂S> COS.?2? The products of COS, PH₃ and H₂S mixture treated by corona discharge were H₂, CO, CO₂, elemental sulfur, SO₂, P₄S₁₀, H₃PO₄ when oxygen concentration was 0.1%. The products were CO, CO₂, elemental sulfur, SO₂ and H₃PO₄ without H₂ and P₄S₁₀ when oxygen concentration was over 0.7%. Based on the characteristic of products, it can be infer that COS, PH₃ and H₂S were converted resulting from the broking of bond by high-energy electrons collision. And the products of the corona discharge were mainly decided by the coexistence of ion type.?3? Dust can be charged, moved directionally and then be collected by corona discharge in the electric field. The dedusting efficiencies were over 99% in the experiment. Dust had positive effect on conversion of COS and H₂S and negative effect on PH₃ when it existed with COS, PH₃ and H₂S. Yield of CO₂ increased and yield of CO and SO₂ decreased because of the addition of dust. Sulfur of phosphorus of COS, PH₃ and H₂S were fixed and collected by the reactor due to these gases or their intermediates reacted with CaF2?Al3+ of the dust by corona discharge. Thus, dust and sulfurous phosphorus were separated and converted simultaneously.?4? Taking the efficiency of cooperation separation and conversion and energy yield into considered, the electrode of round bar perform best among different electrodes. The smaller of anode-cathode distance, the higher efficiency of cooperation separation and conversion of dust and COS, PH₃, H₂S would be achieved, as well as the energy yield. With the increased staying time, the efficiency of cooperation separation and conversion increased, but energy yield came down. The efficiency of cooperation separation and conversion at the two statuses were the same under the same SIE when simulate gas was with 86% CO. The increasing of temperature would influence the efficiency for influencing the discharging characteristics.Over all, the corona discharge technology can remove the dust, COS, PH₃ and H₂S simultaneously from the yellow phosphorus furnace gas, and idea results could be achieved through designing and adjusting the discharge and relative conditions.