Method and Application of Enhancing Heavy Metal Capture in Desulfurization Tower Using Magnetic Media

Abstract

The invention belongs to the field of pollutant removal, and specifically discloses a method for using magnetic media to strengthen the collection of heavy metals in a desulfurization tower and an application thereof. Specifically, the method is to add a magnetic medium to the flue gas at the entrance of the desulfurization tower to promote the enrichment of heavy metals in the flue gas on the magnetic medium in the form of heterogeneous condensation or chemical adsorption; The spray layer and the magnetic adsorption layer are discharged from the outlet of the desulfurization tower, so as to intercept and capture the magnetic medium rich in heavy metals by using the dual functions of the spray droplets and the magnetic adsorption layer, so as to realize the removal of heavy metal pollutants in the flue gas. Enhanced capture. The invention can realize the enhanced capture of heavy metal pollutants in flue gas, avoid secondary pollution caused by powder escape, has high overall removal efficiency, strong safety and no environmental risk, and has the advantages of simple process flow and low operating cost. At the same time, it will not have a negative impact on the working status of the desulfurization system.

Description

technical field [0001] The invention belongs to the field of pollutant removal, and more specifically relates to a method for strengthening the collection of heavy metals in a desulfurization tower by using a magnetic medium and an application thereof. Background technique [0002] my country is the world's largest energy producer and consumer, and has formed an energy supply system with comprehensive development of coal, oil, natural gas, new energy, and renewable energy. Among them, coal-fired thermal power generation occupies an irreplaceable role in my country's energy system. leading position. However, coal-fired power generation will bring a lot of flue gas emissions, which contain some toxic pollutants such as NO x , SO 2 , particulate matter and heavy metals, causing serious damage to the ecological environment. With the development of science and technology, NO x , SO 2 , particulate matter and other related pollutant control equipment have been equipped in most...

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Problems solved by technology

[0004] Among the existing technologies for controlling the discharge of heavy metal pollutants in coal-burning flue gas, mainly include: (1) CN103952207A discloses an arsenic-fixing agent and its preparation method and a method for using the arsenic-fixing agent to fix arsenic. The arsenic-fixing agent is composed of CaCO 3 Composed of metal salts, the preparation method is to dry calcium carbonate, place it in a metal salt solution, heat it in a water bath at a temperature of 95±5°C for 2-2.5 hours, keep stirring, and filter it under the condition of 100-110°C Drying, grinding to 180-300 mesh, and then adding to the coal at a ratio of 0.5-5% of the coal mass, this method is based on the transformation law of arsenic in the high-temperature furnace and flue gas, and uses the arsenic-fixing agent with developed gaps to reduce The concentration of arsenic in high-temperature flue gas, but the arsenic-fixing agent of this method contains alkali metal salts such as sodium and potassium, and the alkali metal vapor released at high temperature will cause contamination of the boiler heat exchange tubes, seriously affecting the operation stability of the boiler, and the The preparation process of the arsenic-fixing agent is complicated, and it is not suitable for large-scale industrial production; (2) CN109045963A discloses a method for oxidation-absorption removal of gaseous selenium dioxide in coal-fired flue gas, and the prepared oxidant and absorbent are sprayed simultaneously It is sprayed into the upper part of the shower tower, and forms a convection flow with the coal-fired flue gas introduced from the lower part of the spray absorption tower, so that the gaseous selenium dioxide in the flue gas can fully react, and realize the transformation of selenium dioxide into selenate and be absorbed

The highest oxidation efficiency of this method can reach 99%, and the absorption efficiency can reach more than 98%, but this method needs to consume a large amount of chemical reagents, the cost is high, and it will change the composition of desulfurization slurry and affect the operation of desulfurization equipment; (3) Senior in the paper "Selenium Partitioning and Removal Across a Wet FGDScrubber at a Coal-Fired Power Plant" proposed a method to strengthen the removal of selenium pollutants in flue gas, by adding calcium hydroxide particles at the entrance of the desulfurization tower to adsorb selenium pollutants, Then it is removed inside the desulfurization tower, and the overall selenium removal rate is increased from 26-66% to 70-73%, but this method needs to add a large amount of calcium hydroxide particles (185-381 pounds / hour), the cost is high, and there may be The risk of selenium-enriched particles escaping from the desulfurization tower, causing secondary pollution

After research, it is found that the existing control technologies for the emission of heavy metal pollutants in coal-fired flue gas mainly have the following problems: (1) The process is complicated and not suitable for practical industrial applications; (2) A large amount of chemical reagents or raw materials are consumed, and the operation High cost, (3) has a negative effect on the working status of other equipment (such as boilers, desulfurization towers), affecting the normal production and operation process

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