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Method for simultaneous purification of elementary substance mercury and nitric oxides in coal-fired flue gas

A technology for nitrogen oxides and coal-fired flue gas, applied in chemical instruments and methods, separation methods, air quality improvement, etc., can solve the problem of difficulty in finding catalysts that can be used stably for a long time, catalyst poisoning, increasing the complexity of flue gas purification systems Investment cost and other issues, to achieve the effect of good reliability, low one-time investment and simple process flow

Inactive Publication Date: 2006-11-22
SHANGHAI JIAO TONG UNIV +1
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  • Summary
  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

For this reason, some people try to use catalytic oxidation method to oxidize Hg in flue gas 0 However, due to the poisonous effect of sulfur dioxide in the flue gas on the catalyst, it is still difficult to find a catalyst that can be used stably for a long time
In addition, this method adds an additional catalytic conversion unit, which increases the complexity and investment cost of the flue gas purification system

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Preparation of simulated boiler flue gas: Use a quartz tube with a diameter of 20mm and a length of 500mm as the reactor, with a 200mm water jacket cooling device downstream, and use a tubular heating furnace for heating. Use simulated flue gas prepared on site ([NO]=350ppm, [Hg 0 ] = 50μg / m 3 , [SO2]=1000ppm, all the other are air), the air flow of 800ml / min passes through the reactor continuously, and by the total mercury, Hg in the reactor outlet gas 0 , NOx concentration to determine the effect.

[0024] Ammonium chloride solution was prepared with deionized water, and the concentration of ammonium chloride in the solution was 1%. A metering pump is used to spray the mist of the mixed solution into the simulated gas from the inlet of the reaction tube, so that the stoichiometric ratio between the ammonium chloride added to the simulated flue gas and the NO in the flue gas is 0.7:1. When the temperature of the reaction tube is 1000°C and the reaction is stable, th...

Embodiment 2

[0027] Simulated flue gas conditions are the same as in Example 1.

[0028] The chemical additive adopts monochloramine, the main reducing agent adopts urea, utilizes tap water or deionized water to prepare the mixed solution containing 0.2% and 1% of monochloramine solution and urea respectively, make the chemical reaction of urea and monochloramine in the solution The metering ratio is 5.5:1. A metering pump is used to continuously spray mist droplets of monochloramine solution into the simulated flue gas from the inlet of the reaction tube, so that the stoichiometric ratio of monochloramine added to the simulated flue gas to NO in the flue gas is 0.5:1. When the temperature of the reaction tube is 1000°C and the reaction is stable, the oxidation rate of elemental mercury reaches 94%, and the reduction rate of nitrogen oxides is about 45%.

[0029] Then use simulated desulfurization lye (2% sodium carbonate solution) to absorb the above-mentioned gas (in a 500mL gas absorpt...

Embodiment 3

[0031] Simulated flue gas conditions are the same as in Example 1.

[0032] The chemical additive is monochloromethane, the main reducing agent is methane, and the mixed gas of methane and monochloromethane is prepared, the volume concentration is 1% and 0.2% respectively (the rest is air), and the ratio of the main reducing agent to the chemical additive is 5 : 1. The above-mentioned mixed gas is continuously sprayed into the simulated flue gas from the inlet of the reaction tube by a fan, so that the stoichiometric ratio of the total amount of methane and methyl chloride added to the simulated flue gas to the NO in the flue gas is 2:1. When the temperature of the reaction tube is 1000°C and the reaction is stable, it is measured that the oxidation rate of elemental mercury reaches 94%, and the reduction rate of nitrogen oxides is about 37%.

[0033] Then use simulated desulfurization lye (2% sodium carbonate solution) to absorb the above-mentioned gas (in a 500mL gas absorpti...

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Abstract

The invention relates to a method for cleaning mercury and nitrogen oxide in fire coal smoke gas, employing specific chemical matter as additive to be added into high-heat smoke gas in furnace, said chemical matter selectively reducing nitrogen oxide and oxiding mercury into bivalent mercury. Said chemical matter comprises compound containing ammonium and halogen atom absorption, and lower carbon number hydrocarbons containing halogen atom and it's derivant; it can be used separately or together with urea, ammonia gas and natural gas. The matter is degraded under high temperature, and then they can oxide mercury and selectively reduce nitrogen oxide into innocuous nitrogen; smoke gas is treated in desulfurization unit to absorb bivalent mercury and sulfur dioxide. The invention controls nitrogen oxide, mercury and sulfur dioxide in smoke gas without increasing main device and using no catalyst.

Description

technical field [0001] The invention relates to a simultaneous purification method of elemental mercury and nitrogen oxides in coal-fired flue gas. By adding chemical substances to high-temperature flue gas, nitrogen oxides are selectively reduced to nitrogen, and elemental mercury in the flue gas is converted It is divalent mercury that can be simultaneously absorbed by the wet desulfurization device, so as to realize the comprehensive treatment of coal-burning pollutants. Background technique [0002] Mercury has serious physiological toxicity. In its "Global Mercury Status Assessment" report published in February 2003, the United Nations Environment Program warned against the global mercury pollution problem. Since coal contains a certain amount of mercury, the use (mainly combustion) of a large amount of coal is one of the main causes of mercury pollution. For this reason, many countries have begun to pay attention to the control of mercury pollution in the coal combust...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D53/60B01D53/64B01D53/78
CPCY02A50/20
Inventor 晏乃强吴忠标贾金平徐新华汪大翚
Owner SHANGHAI JIAO TONG UNIV
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