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Low-temperature SCR denitration treatment method and device

A treatment method, low-temperature denitrification technology, applied in separation methods, chemical instruments and methods, and dispersed particle separation, etc., can solve problems such as easy poisoning and deactivation of low-temperature SCR catalysts, affecting denitrification efficiency and service life, and difficulties in the application of SCR technology. Achieve the effect of reducing denitrification cost, reducing replacement frequency, and good low-temperature activity

Active Publication Date: 2018-12-07
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, most of the existing boilers do not reserve a denitrification space at this position, which brings great difficulties to the application of the SCR process
In addition, the flue gas in this process section contains a high concentration of dust, and the dust contains alkali metals, arsenic, mercury and other substances that can poison the catalyst, affecting its denitrification efficiency and service life
The flue gas denitrification processes disclosed in Chinese patents CN103768903A, CN103768932A, and CN103768934A require a flue gas temperature of 300-400°C, all of which are medium-temperature denitrification, and require large-scale transformation of the boiler, and the investment cost is relatively high
However, the above catalysts containing SO 2 In the case of water and water, the denitrification activity is not high, and the low temperature range where the denitrification rate is greater than 90% is narrow, which limits its application to a certain extent.
[0005] The currently developed low-temperature denitrification catalyst does not contain SO 2 and H 2 The flue gas of O often has good denitrification activity, but in actual situations, the flue gas still contains H 2 O and SO 2 , the low-temperature SCR catalyst is still vulnerable to poisoning and deactivation under this condition

Method used

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  • Low-temperature SCR denitration treatment method and device

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0030] (1)Al 2 o 3 Preparation of sol: Add pseudo-boehmite to deionized water, add concentrated nitric acid dropwise while stirring, heat to 50-90°C, add nitric acid dropwise until completely peptized, control the pH value of the solution to 2-5, and age After 12-48 hours, a transparent aluminum sol was obtained. The mass ratio of pseudo-boehmite to deionized water is 1:2-1:10, and the mass ratio of concentrated nitric acid to pseudo-boehmite is 1:5-3:5.

[0031] (2)Al 2 o 3 Preparation of the coating: the honeycomb ceramic substrate is immersed in Al 2 o 3 Immerse in the sol for 3-10 minutes, after taking it out, blow off the residual liquid in the channel with compressed air, dry and roast to obtain Al-coated 2 o 3 Coated carrier. The honeycomb ceramic matrix is ​​a cordierite honeycomb ceramic matrix.

[0032] (3) TiO 2 - Preparation of molecular sieve composite slurry: TiO with anatase structure 2 Mix the powder with molecular sieve and urea, add Al 2 o 3 Sol,...

Embodiment 1

[0038] After the flue gas of a coal-fired boiler is pretreated by dust removal and heated to 150 °C, the relevant parameters of the flue gas are shown in Table 1.

[0039] Table 1 Flue gas composition of a coal-fired boiler

[0040]

[0041] The low-temperature denitration catalyst prepared by CN201510801022.2 Example 1-4 is marked as A-D catalyst, loaded in the SCR denitration reactor, and the operating space velocity is 4800h -1 . With hot air as the dilution gas, the volume concentration of ammonia in the diluted ammonia gas is 3.5v%. The ammonia injection grid adopts the ammonia injection grid commonly used in this field. The final catalyst composition (based on the mass of the honeycomb ceramic substrate) and the treatment effect are shown in Table 2.

[0042] Table 2 Composition and treatment effect of low-temperature denitrification catalyst

[0043]

Embodiment 2

[0045] After the regenerated flue gas of a catalytic cracking unit is pretreated by dedusting and heated to 180 °C, the relevant parameters of the flue gas are shown in Table 3.

[0046] Table 3 Flue gas composition of a coal-fired boiler

[0047]

[0048] Using the same catalysts A-D as in Example 1, packed in the SCR denitrification reactor, the denitrification reactor operates at a space velocity of 5400h -1 . With hot air as the dilution gas, the volume concentration of ammonia in the diluted ammonia gas is 3.0v%. The ammonia injection grid adopts the ammonia injection grid commonly used in this field. The treatment effect is shown in Table 4.

[0049] Table 4 Treatment Effects of Different Catalysts

[0050]

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Abstract

The invention relates to a low-temperature selective catalytic reduction (SCR) denitration treatment method. The method comprises the following steps: controlling the temperature of NOx-containing flue gas to be 120-300 DEG C through a heat exchange unit, then uniformly mixing the NOx-containing flue gas with ammonia gas sprayed out by an ammonia spraying grid, sending the mixed gas into an SCR denitration reactor, converting the NOx into N2 and H2O under the action of a low-temperature denitration catalyst, and discharging the purified gas after heat is recycled. The low-temperature SCR denitration treatment device provided by the invention is realized by adopting the method. The device provided by the invention has the advantages of good low-temperature activity, high sulfur resistance,good water stability, high anti-poisoning capacity, low treatment cost and the like.

Description

technical field [0001] The invention belongs to the technical field of environmental protection waste gas treatment, and in particular relates to a low-temperature SCR denitrification treatment method and device. Background technique [0002] Nitrogen oxides (NOx) have N 2 O, NO, NO 2 , N 2 o 3 , N 2 o 4 and N 2 o 5 and other forms, and can cause a variety of hazards, such as photochemical smog can be produced with volatile organic compounds (VOC) in the atmosphere, which can cause strong irritation to the eyes and throat, and cause headaches and respiratory diseases. cause death. my country's NOx emissions have exceeded 20 million tons for many years in a row, 21.94 million tons in 2010, 24.043 million tons in 2011, 23.378 million tons in 2012, 22.273 million tons in 2013, and 20.78 million tons in 2014. In recent years, it has shown a continuous downward trend, but its pollution situation is still serious. On September 12, 2014, three ministries and commissions in...

Claims

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Application Information

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IPC IPC(8): B01D53/90B01D53/86B01D53/56
CPCB01D53/8631B01D53/90B01D2255/2065B01D2255/20707B01D2255/2073B01D2255/20761B01D2255/2094B01D2255/50
Inventor 王明星王宽岭李欣姜阳
Owner CHINA PETROLEUM & CHEM CORP
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