Black powder in gas pipelines


METHODS TO HELP REMOVE BLACK POWDER FORM GAS PIPELINES

Black Powder is a contaminant found in natural gas transmission and distribution systems all over the world. Chemical or microbial reactions with steel found in natural gas pipelines, gas wells, and associated facilities can create powder.
Related image
Figure 1: Black powder in gas pipeline
Steps involved:
1.      Laboratory analysis
Analyze samples of powder for their chemical composition and particle size distribution, taking samples from debris of pigging operations or from filters’ deposits.

2.      Physical removal of powder
Cleaning pigging provide immediate means to eliminate the Powder from flowing or building up inside the pipeline.
a.       Cleaning pigging
To remove powder deposits, solids or accumulated debris in the pipeline. A standard of four cleaning runs will be adequate.
b.      Intelligent pigging
After the pipeline section is declared cleaned, then inspect first by a profile pigging and then an intelligent pigging (magnetic flux leakage).
  
3.      Separation technology
a.       Filter – separators
If a filter-separator is already installed, the filters should be cleaned three times a week. Operators have to change filter separator elements. Use very fine sub-micron filters.
b.      Filters
We can also install cyclo-filters or cartridge filters at the inlet of the metering stations. The filters should be cleaned at least three times a week.

4.      Moisture control 
Removal of water condensation in the pipeline is the most critical step in preventing black powder formation in a gas grid. Install a glycol dehydration units, refrigeration and knockout drum units; and ensure the sales gas entering the pipelines does not contain water levels in excess of the maximum allowable level of 7 lb/mmscf.

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