Dust Removal Efficiency and Operation Characteristics of Metal Filters for Coal Gasification Fines and Standard Dust Sample

금속필터를 사용한 석탄가스화 분진 및 표준 분진의 집진 효율과 운전특성

Abstract

Demand for improving dust removal efficiency in coal power plants and the dust removal requirement to the level of capturing fine particulate matter and ultrafine particles have been increasing. While bag filter and electrostatic precipitator (ESP) are typically used for dust removal in the processes operating at atmospheric pressure, metal filters or ceramic filters are employed for dust which is produced at high temperature/pressure system as in coal gasification. For dust removal at the high temperature/pressure conditions, two metal filters of five compressed/sintered layers were manufactured and applied to analyze the dust removal characteristics. Manufactured metal filters exhibited more than 99% dust removal efficiency on coal gasification fine particulates in mass basis. To evaluate the fine particulate removal efficiency of less than $2.5{\mu}m$, JIS standard fine sample was used and confirmed the removal efficiencies of 97% and 70~82% on the fine particulates of $1{\sim}2.5{\mu}m$ size range. For the size range of less than $1{\mu}m$, dust removal efficiency of manufactured metal filters significantly degraded with smaller particle size. Improving methods are proposed to overcome the limitations in applying to fine dust of less than $1{\mu}m$.

석탄화력발전소에서 발생하는 분진 효율을 높이고 미세먼지와 극미세먼지까지 집진할 필요성이 높아지고 있다. 상압 영역에서 운전되는 플랜트 발생 분진 제거를 위해서는 백필터나 전기집진기를 사용하나, 고온고압에서 운전되는 석탄가스화와 같은 경우는 금속필터나 세라믹필터가 사용된다. 고온고압에서 분진 집진을 위해 2종의 5겹 압착/소결한 금속필터를 제작하였고 이를 사용했을 때 분진 포집효율과 $10{\mu}m$ 이하 입자에 대한 포집 성능을 파악하였다. 석탄가스화 분진에 대한 금속필터의 집진효율은 무게기준으로 99%대에 달하였다. 제작한 금속필터 2종의 미세먼지 입자 이하(< $2.5{\mu}m$) 크기까지 집진성능을 파악하고자 JIS 분진 표준시료를 대상으로 실험을 수행하였고, $1{\sim}2.5{\mu}m$ 입자크기 범위에 대해 97%와 70~82%의 집진 성능을 확인하였다. $1{\mu}m$ 이하 입자크기 영역에서는 입자크기가 작아짐에 따라 제작한 금속필터의 집진효율이 급격히 낮아짐을 볼 수 있었다. 이러한 $1{\mu}m$ 이하 입자들에 대한 집진 제한점을 극복하고자 금속필터 성능의 개선 방안을 제시하였다.

Fig. 1. Dust removal test facility using fine particulate matter obtained from coal gasifier.

Fig. 2. Dust removal test facility using JIS standard fine particulate matter.

Fig. 3. Dust concentration measuring equipment.

Fig. 4. Particle diameter distribution diagram of fly-ash fines obtained from coal gasifier.

Fig. 5. Particle diameter distribution of JIS standard fine particulate matter sample.

Fig. 6. Cross-sectional diagram of metal filter manufactured through compression/sintering with 5 layers of stainless steel sheets.

Fig. 7. Installation of metal filters to the dust removal test facility.

Fig. 9. Operational characteristics of differential pressure by filter-cleaning methods (metal filter No. 1).

Fig. 10. Operational characteristics of differential pressure by filter-cleaning methods (metal filter No. 2).

Fig. 11. Removal efficiency of fine particulate matter using metal filter No. 1 for JIS standard fines.

Fig. 12. Removal efficiency of fine particulate matter using metal filter No. 2 for JIS standard fines.

Fig. 8. Particle size distribution of coal feed and captured fines in 3 ton/day coal gasification test using metal filter No. 1.

Table 1. Bulk density of fly-ash fines obtained from coal gasifier

Table 2. Specification of metal filter

Table 3. Dust concentration results using metal filter No. 1 for coal gasification flyash fines

Table 4. Dust concentration results using metal filter No. 2 for coal gasification flyash fines

Table 5. Environmental emission regulations of dust in Korea