Sludge Dispersant

NIPPON YUKA KOGYO >> Sludge Dispersant

Sludge Dispersant

Product name




Yunic 800VLS

Sludge inhibition and dispersion
for VLSFO (0.50% sulfur)
Standard dosing rate: 1/2000

Suppresses the formation of sludge caused by asphaltene and paraffin (wax) from VLSFO due to poor compatibility when mixing or bunkering VLSFO (0.50% sulfur).
Including poor compatibility when HSHFO (3.50% sulfur) and VLSFO are mixed.

200L D/M

Yunic 555D

Sludge inhibition and dispersion
for heavy fuel oil (3.50% sulfur)

Standard dosing rate: 1/8000

Suppress the occurrence of asphaltene sludge due to long-term storage, heating, and mixture of heavy fuel oil.

200L D/M

Yunic 650-II

Sludge dispersion and inhibition
Vanadium ash modification

Standard dosing rate: 1/5000

Suppress the occurrence of asphaltene sludge due to long-term storage, heating, and mixture of heavy fuel oil.
Raise the melting point of vanadium ash and change it to non-adhesion ash.

200L D/M


Benefits of "Yunic800VLS"

"Yunic 800VLS" is a fuel oil additive for marine fuel oil with a sulfur content of 0.50% or less that complies with the sulfur regulations effective from January 1, 2020 (hereinafter VLSFO) that suppresses the generation of sludge caused by asphaltene and paraffinic/wax content due to poor compatibility when switching and commingling of VLSFOs.
It effectively suppresses the sludge generated from VLSFOs and contributes to the prevention of sludge formation due to the poor compatibility (Sludge may be generated not only when commingling but also when used alone).
We developed "Yunic800 VLS" as a new product in May 2019, based on the know-how of the technology to suppress the sludge formation obtained from Yunic 555D.

VLSFO may generate sludge (caused by asphaltene and paraffin (wax)) if the compatibility is poor. As with high sulfur fuel oil, the generated sludge needs to be suppressed more strongly to prevent problems, such as sludge deposition in FO tank, FO strainer clogging and purifier malfunction etc. (Sludge may be generated not only when commingling but also when used alone)

Sludge formation in poor compatibility of VLSFOs
(Flocculated asphaltene and paraffin sludge is formed and deposited at the bottom)

Effect of "Yunic800VLS"

The following graph shows an example of the sludge formation suppression effect of Yunic 800VLS. This is a data comparing the suppression effect of sludge generated from commingling of VLSFOs with existing products Yunic 555D. The effect of stronger surpressing sludge caused by asphaltene and paraffin (wax) specific to VLSFOs shows a higher sludge formation suppressing performance than Yunic 555D, which is effective for dispersing asphaltene sludge.

Example of sludge formation suppression effect. (Commingling of VLSFOs)

The standard dosing rate for Yunic800VLS is 500 ppm (1/2000)

Please feel free to contact us if you are interested in Yunic800VLS.

Checking the compatibility (stability) of fuel oil by "Spot test"

It is possible to check the compatibility (stability) of a heavy fuel oil including VLSFO (Commingled VLSFOs, VLSFO alone, and compatibility against heating and long-term storage) by the "Fuel oil spot test (basic operation is based on ASTM D4740)" in our product "Oil tester YT series".
If the Spot test result "Evaluation 3~6", it is confirm that the compatibility (stability) is poor, we recommend to dose Yunic 800VLS as there will be a possibility of sludge formation.

We provide technical service advice for spot test judgment and analysis of various fuel oils including VLSFO. Please feel free to contact us for further information.


Obtained the product certification by NIPPON KAIJI KYOKAI (ClassNK) >> "Certification"

Precipitation of asphaltene sludge

C heavy oil contains a component called asphaltene. It is not soluble in paraffinic hydrocarbons (an oil that is made of hydrogen saturated bonding to carbon), which is the main component of C heavy oil. In heavy oil, asphaltene is dispersed because it is covered by substance with an intermediate property between asphaltene and paraffinic hydrocarbon. However, when heavy oil is heated or mixed with other type of oil, the covering substance will be removed and asphaltene will be precipitated from heavy oil and settle as sludge.

* Definition of asphaltene: Substance that is soluble in benzene but insoluble in n- heptanes.

* Porphyrin on the right of the above figure is the active central substance of hemoglobin in the blood of animals and chlorophyll in plants. One of the reasons that petroleum is said to be originated from plants and animals is that porphyrin is found in petroleum. M (metal) that is surrounded by 4 Ns (nitrogen) is iron in hemoglobin or magnesium in chlorophyll, and sometimes it is vanadium in heavy oil. Vanadium is a metal with a low melting point and is the reason of combustion failure caused by heavy oil.

Effect of Yunic 555D

Component of Yunic 555D can disperse asphaltene in paraffinic hydrocarbons as an "intermediate substance". Therefore, the addition of Yunic555D can compensate for the "intermediate substance" that is lost due to heating or mixing of other oil. The prevention of asphaltene precipitation and sludge can prevent supply cut of fuel due to strainer obstruction. It can also help to keep the tank clean and improve fuel economy by using up the asphaltene without losing it as sludge.

<Fuel tank that Yunic 555D is being used>

- Ship type

: Ocean-going container ship

- Fuel oil

: C heavy oil (mainly 380cSt)

- Tank capacity

: 900 m3

- Period of use

: 7 years and 8 months

- Tank cleaning

: Yet to be implemented

  • Reduce precipitates such as sludge by helping to disperse asphaltene (Effective use of the entire fuel oil)
  • Improve sprayability by miniaturizing fuel oil
  • Improve ignitability by improving sprayability and improve combustion by shortening of afterburning time

The average fuel efficiency improvement rate is about 3% by these synergistic effects. It has a high effect of improving fuel efficiency by burning the entire fuel efficiently.


Feel free to contact us if you are interested with Sludge Dispersant.