Application of corrosion-resistant high-precision filter material in waste incineration flue gas purification

Bag type of dust collector is an important dust removal device for waste incineration systems. Among them, the filter material for bag type dust collector is used as the core filtering material, and it has been paid more and more attention by people.

During the treatment of waste incineration dust, due to the high temperature of the flue gas, large fluctuations, strong corrosiveness, large moisture content, fine dust particles, and high viscosity, ordinary filter materials are difficult to adapt to the harsh working conditions mentioned above. In the past, the failure of PPS or P84 filter materials in the waste incineration industry brought risks and losses to customers.

Therefore, the selection of suitable filter materials and high-quality qualified products is the top priority of waste incineration plants.

Characteristics of refuse incineration conditions

1. The temperature of the flue gas entering the dust collector after deacidification is generally 160-200 ℃, and it can reach about 260 ℃ in an instant.

2. The flue gas contains acid gas such as sulfide, nitrogen oxide, hydrogen fluoride and hydrogen chloride, which is easy to form acid corrosion on the dust collector and filter material.

3. The moisture content in soot can reach 20-30% or even 60%.

4. After deacidification, the dust itself has a strong hygroscopicity. When the temperature fluctuates, the high moisture content is easy to form dew condensation conditions, causing the dust board paste bag trapped in the filter bag to become blocked, and even the filter bag is damaged.

5. The average particle diameter of the waste incineration dust is 20 ～ 30μm. Those less than 30μm can occupy 50 ～ 60%. The true density is 2.2 ～ 2.3g / cm³ and the bulk density is only 0.3 ～ 0.5 g / cm³.

Selection basis

1) Dust collector data

① Filtering wind speed

② Intake method

③ Air distribution

④ Ash cleaning parameters and methods

⑤ Center distance of flower plate

⑥ Warehouse and poppet valve

⑦ Ash conveying system

⑧ Current running resistance (Pa)

⑨ Shutdown frequency (times/year)

2) Flue gas analysis

① Operating temperature

② Smoke composition

③ Dust characteristics

3) On-site usage

① Use of the original filter bag

② Use of supporting framework

③ Problems in operation and maintenance

Features

In view of the special working conditions of the waste incineration industry, our company uses 100% PTFE needle felt and e-PTFE film. Among them, our company uses imported or domestic first-class PTFE fiber manufacturers to produce needle felt.

PTFE fiber

Polytetrafluoroethylene is a neutral polymer compound with a unique molecular structure, that is, a completely symmetrical structure. It can be used continuously for a long time under the high temperature of 240 ℃, the instant temperature can reach 260 ℃; strong chemical stability, corrosion resistance; good self-lubricity, extremely low friction coefficient, easy to clean.

e-PTFE film treatment

Our e-PTFE membrane filter is a PTFE filter with microporous polytetrafluoroethylene film on the surface of the PTFE filter.

The key of the coated filter is polytetrafluoroethylene film, which is made by a special biaxial stretching process. It is a non-sticky, smooth and microporous three-dimensional film. The number of micropores can reach 1 × 109 / cm³. , Can be laminated on the surface of traditional needle felt and woven filter material.

Has the following characteristics:

1. Excellent filtration efficiency (above 99.99%);

2. Excellent dust cake peeling performance;

3. The smooth surface greatly reduces the phenomenon of bagging;

4. Stable running resistance and low energy consumption;

5. Capable of capturing ultra-fine dust with a particle size of less than 1 um;

6. Opening rate: 85 ～ 93%;

7. Uniform pore size distribution, controlled in the range of 0.05 ~ 3 um

8. Temperature applicable range: -180 ～ 260 ℃

9. Excellent chemical resistance (except for molten alkali metal, elemental fluorine gas has slight corrosion)

Advantages of 100% PTFE filter + ePTFE membrane product

1. High-temperature resistance (200-280 ℃)

2. Corrosion resistance, no hydrolysis, the strength of the filter material structure will not change or decay in the working conditions

3. Easy cleaning

4. Better film fastness and longer service life

5. Stable running resistance

6. Higher filtering accuracy

7. Better cost performance

8. Can meet environmental protection requirements below 5-10mg / m³

Applications

One:

An industrial hazardous waste disposal plant, 2 grate incinerators. Dry deacidification and bag dust removal.

100% PTFE filter material + ePTFE coated cloth bag has been used for more than 2 years, running resistance is about 1000-1200pa, and the dust emission concentration at the outlet of the bag filter is less than 8mg / m³.

The use of dust removal is as follows:

Continuous working temperature (℃): 160-180

Instant temperature (° C): 230

Ash Conveying System: Mechanical

Into the wind: side into the wind

Number of clean air chambers: 6

Filter bag material: 100% PTFE filter material + ePTFE membrane

Gram Weight (g / ㎡): 800

Baghead type: Snap band

Filter bag specifications (mm): Φ130 * 6000

Filter bag use time: February 2018

Required life: 2 years

Two:

1 × 700t / d waste incinerator, equipped with a bag filter. The specific flue gas purification process is low-nitrogen combustion + SNCR + semi-dry deacidification + activated carbon adsorption + bag filter.

100% PTFE filter material + ePTFE membrane bag has been running on this dust collector for more than 2 years. The operation is good, the dust is stable below 10mg / m³, and the running resistance is about 1200-1500pa.

Dust collector usage:

Continuous working temperature (℃): 160

SO2 (mg / m³): 30-50

NOX (mg / m³): 150-200

O2 (mg / m³): 6-8

H2O (%): 20

HF (mg / m³): 2-4

Filter bag material: 100% PTFE filter material + ePTFE membrane

Gram Weight (g / ㎡): 800

Baghead type: Snap band

Filter bag specification (mm): diameter 160 * 6000

Supporting skeleton specifications: diameter 155 * 5980

Number of warehouses: 8

Cleaning method: offline

Into the wind: down into the wind

Life: more than 2 years