PTQ Q2 2023 Issue

maximum by preventing any new foulant from forming. Conversion of the crude increased by 2-3 wt%, improving the overall performance of the operation. Subsequent tests determined that the minimum amount of nano-additive required to maintain the new maximum temperature and improved performance was 100 ppm. For commercial-scale operations, this can likely be in the range of 75-125 ppm to gain the same benefits. Heavy oil piping With the success of the nano-additive on the immersion heater with Athabasca bitumen, atmospheric tower bot- toms from Athabasca bitumen was circulated to mimic long-term fouling accumulation on transfer piping to downstream conversion units. The hypothesised fouling mechanism in this type of piping is a combination of heavier hydrocarbon thermal, hydrocarbon physical (asphaltene precipitation), and inorganic physical. Temperatures were increased above what is normally expected in the pipes to initiate and propagate at least one of the fouling mechanisms. Once the appropriate conditions were set, fouling was witnessed during a planned stop- page to visually inspect the fouling and from an increased pressure drop. Figure 3 shows the temperatures and pressure drops along with the impact of additive addition part-way through a test run on the operating conditions. As with the immersion heater testing, no new fouling was created. Any previously generated foulant was moved back into the

770

765

No additive

New Max T with additive

760

755

Max T with no additive

Add 300 ppm additive after 60 hours and reactor recovered and increased performance

750

745

740

100

120

Hours of operation (hrs)

Figure 2 Plot of liquid pool temperature over time with additive addition

solution and did not adhere to the piping or accumulate in the strainers. Delayed coker fractionator – fractionation zone testing Distillate and coker gasoils contain a high content of dienes or conjugated olefins that can polymerise to generate coke when the operating temperature is in the range of 450- 615°F (232-324ºC). 1 Hydrocarbons with a diene value of four or greater (>4) usually generate or form polymeric coke when the operating temperature is 500-580°F (260- 304ºC). 2 Thus, the fractionation sections of delayed cok- ing fractionators are vulnerable to polymeric coke fouling.

550 570 590 610 650 670 690 710 730 630 750

1.5

CS inlet temp

CS outlet temp

20 min∆P avg. (psi)

Additive

Velocity – 6 ft/s

0.5

-0.5

-1

-1.5

Figure 3 Operating conditions during a pipe fouling test

Additives investigated for polymeric coke formation

Base chemistry

Magnesium sulphonate with

Magnesium carbonate (2)

Calcium sulphonate (3)

MGO nanoparticles (1)

Concentration of base chemistry

30-35%

10-30%

Specific gravity

1.42

1.0288 @ 16°C

0.9066-0.9366 @ 20°C 0.905-0.935 g/cm3 @ 20°C 2.75-6.75 cP (mPa.s) @ 20°C

Density Viscosity

1.40 g/cm 3 @ 20ºC 0.25 cP @ 15°C

1.011 g/cm3

0.028 cP @ 38°C

Flash point

65.6°C

61.6°C

26°C

Table 2

PTQ Q2 2023