The plant has 2×400 MW Foster Wheeler boilers, each with 18 burners on three levels and 27 soot blowers.
The plant´s stated problem was excessive hard, glass like, deposits on the “V” bottom of the boilers.
These deposits could build up to 5-6 feet (1.5-1.8 Meters) and had to be loosened with explosives, which caused tube damage.
Shutdowns at the plant resulted in tube separation as the deposits cooled at different speeds. Once, the bottom of the boiler cracked open and the molten material fell out of the boiler on to a concrete pad.
The plant was burning 675,000 tons oil per year, (75.5 tons per hour).
The boiler cleaning downtime averaged 16 days per year, resulting in substantial production losses.
The plant was also using a magnesium hydroxide to coat the tubes to prevent corrosion. The ash loading was substantial and had to be removed and disposed of as a hazardous waste.
Heat value Btu/Lb: 18239 (MJ/kg 38.1)
Sulfur: 1.4 %
Nitrogen: 0.27 %
Water: 0.45 %
Ash: 0.07 %
Asphaltenes: 6.5 %
API Gravity: 9.9@ 60°
Vanadium: 110 ppm
Sodium: 50 ppm
Silicon: 61 ppm
Aluminum: 42 ppm
Bycosin proposed DP 94001 to reduce the maintenance downtime problem at this plant, based on the successes seen at other locations.
The organic magnesium based deposit inhibitor had proven to be superior to other treatments in reducing slag deposits and corrosion, without adding additional deposits to the tubes that reduce heat transfer.
Bycosin supplied an injection pump and storage tank and the plant staff added the product to the tank as necessary.
The primary effects of Bycosin DP 94001 are:
• fast reduction of slag deposits
• reduction of soot/stack solids
• the remaining deposits will be soft, porous and easy to remove
• cleaning downtime is often reduced by as much as 75%.
Bycosin DP 94001 is a slag inhibitor combined with a combustion catalyst that rapidly reduces existing slag deposits. It also reduces soot/stack solids and makes the remaining deposits soft, porous and easy to remove.
• The organic Mg penetrates easy into the deposits and slag, due to the smaller size of the organic Mg, and makes the deposits soft and friable.
• DP94001 rapidly cleans tubes and walls throughout the whole system from furnace to air pre heater by breaking the bond in the slag deposits.
• The product raises the melting point of the ash, reducing deposit formation and prevents corrosion at both high and low temperatures.
It’s important to keep the furnace surfaces clean in order to get maximum heat transfer (heat radiation).
In most cases, a surface with deposits will reduce heat transfer to the water in the tubes and increase the temperature of the flue gases out the stack. This can result in more deposits and high temperature corrosion in the back end of the boiler, in addition to expensive wasted energy.
The trial started in one of the 400 MW units and continued for a year.
The dosage of DP 94001 was initially set at 1:2000 (500 ppm) but later moved to 1:4000 (250 ppm) as the plant cleaned up and stayed clean.
Once Plant 1 saw the results, the magnesium hydroxide was stopped at plant 2 and the DP94001 was added.
The dosage was 1:2000 for 2 weeks and remarkable cleaning was seen.
Following an inspection of the boilers by company staff, comments such as “I have worked for this company for 20 years and never seen boiler tubes this clean, even after sandblasting” were heard.
After the trial was completed, the results where:
*V-bottom deposits were soft, porous and substantially reduced in volume.
• Cleaning of boiler was reduced from 2 times per year to 1 time every two years. A reduction of 75%.
• Before using Bycosin the plant was down 16 days per year.
• During the trial the downtime was reduced to 2 days per year.
• Production was increased by 250 000 MW, a substantial increase in earnings.
• Increased electricity production:1000.000 MWh
• Increased production income: $5,300,000 USD
• Cost of treated fuel: -$2,400,000 USD
• Decreased cleaning cost: $,240,000 USD
Total Increased Profitability: $3,140,000 USD