Maintaining a Biogas Purification System 06-05-2013 SARBS 1
TIPS FOR MAINTENANCE SAVINGS 06-05-2013 SARBS 2
REVIEW OF BIOGAS TREATMENT PROCESSES 06-05-2013 SARBS 3
1. Inlet raw gas coalescer 2. H 2 S Removal Bioscrubber Iron Sponge SulfaTreat 06-05-2013 SARBS 4
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3. Particulate Filter 4. Blower(s) or Compressors 5. Moisture Removal System Compressor Recirculation Pump Condenser 06-05-2013 SARBS 8
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6. Water Droplet Coalescer 7. Siloxane Removal System 8. Final Particulate Filter 06-05-2013 SARBS 10
Where to look for ways to save on maintenance 06-05-2013 SARBS 11
Coalescers and Filters are only a small part of the O&M Budget, so not much can be gained by tweaking these. 06-05-2013 SARBS 12
Two potential areas of savings: 1) Replace non-cleanable filter elements with cleanable mesh pad type elements; 2) Possibly eliminate coalescers ahead of iron sponge vessels. 06-05-2013 SARBS 13
Implement a preventative maintenance program for blowers and moisture removal equipment. This is critical as the equipment ages. Budget key parts replacements. 06-05-2013 SARBS 14
As an alternative to in-house programs, consider purchasing a service maintenance agreement from a 3 rd party. These are inexpensive and will free up labor resources for more critical plant matters. 06-05-2013 SARBS 15
So far, we have discussed items that contribute to only 15% to 20% of the total maintenance budget. 06-05-2013 SARBS 16
The two biggest cost items are: 1) H 2 S removal media and 2) Siloxane removal media replacement. 06-05-2013 SARBS 17
H 2 S removal media replacement can be as much as 40% to 45% of the total maintenance cost on a digester gas purification system. 06-05-2013 SARBS 18
As a rule, it costs about $1.00 to $2.50 per pound of H2S removed from a digester gas stream (the higher number is for SulfaTreat ). This includes the new media, labor, disposal and transportation costs. 06-05-2013 SARBS 19
One pound of H 2 S is equivalent to 1 MMSCF of digester gas containing just 11.4 ppmv of H 2 S. 06-05-2013 SARBS 20
The costs add up fast. A digester gas stream with a high siloxanes level can cost $100 s each day for purification. 06-05-2013 SARBS 21
Ways to save on H 2 S removal: 1) Keep ph of iron sponge above 7.0. 2) Make sure there are 2 ppmv of oxygen for each ppmv of H 2 S in the biogas. 06-05-2013 SARBS 22
3) Try an air scour to restore the iron sponge effectiveness. Oxygen will enhance the H 2 S removal and extend the media life. 06-05-2013 SARBS 23
4) Review H 2 S Removal System design parameters to determine if the proper equipment is being used. Some rules of thumb: 06-05-2013 SARBS 24
Consider the use of a bioscrubber if H 2 S level is above 250 ppmv. Iron Sponge and SulfaTreat are best used if the H 2 S level is 100 to 400 ppmv. 06-05-2013 SARBS 25
If a bioscrubber can be installed, it can reduce H 2 S removal O&M costs by 75% or more. This offers an attractive payback on the capital investment. 06-05-2013 SARBS 26
Siloxane removal media replacement can be as much as 50% to 55% of the total maintenance cost on a digester gas purification system. 06-05-2013 SARBS 27
As a rule, it costs about $4.00 to $4.50 per pound of siloxanes removed from a digester gas stream. This includes the new carbon media, labor, disposal and transportation costs. 06-05-2013 SARBS 28
One pound of siloxanes is equivalent to 1 MMSCF of digester gas containing just 0.97 ppmv (970 ppbv) of total siloxanes. 06-05-2013 SARBS 29
The costs add up fast. A digester gas stream with a high siloxanes level can cost $100 s each day for purification. 06-05-2013 SARBS 30
Ways to save on siloxanes removal: 1) Consider a carbon exchange service (CXS) or a carbon recycle service (CRS). These can save as Much as 50% of the cost of new media and disposal of the spent media. 06-05-2013 SARBS 31
2) Consider replacing the nonregenerable siloxane removal system with a regenerable one, such as the CompHeet Process. This can save as much as 75%, and has a good payback. 06-05-2013 SARBS 32
Perform a review your Siloxane Removal System design parameters to determine if a regenerable system is a good fit. A rule of thumb: 06-05-2013 SARBS 33
Consider the use of a regenerable siloxane removal system if the total of the siloxanes and VOCs exceeds 25 ppmv. 06-05-2013 SARBS 34
Another area for potential savings is in analytical tests. Consider the use of a multifunction in-line analyzer and use a laboratory only for tests it cannot perform. 06-05-2013 SARBS 35
Wrap-up and Questions 06-05-2013 SARBS 36
You can reach me at: 425-497-8111 (Office) 425-614-9293 jeff@escpure.com 06-05-2013 SARBS 37