REFINERY CHEMICAL CLEANING: CRITERIA FOR DETERGENT SELECTION

Chris Spurrell Chevron Products Company

324 W. El Segundo Blvd. El Segundo, CA 90245

Mialeeka Bibbs Chevron Products Company

324 W. El Segundo Blvd. El Segundo, CA 90245

Abstract

Mechanical equipment in the oil processing industry can operate for years between shutdowns. During this time there is often a tendency for scale, debris and sludges to form within this equipment. During the shutdowns these fouling materials have to be removed before mechanical work or even entry can be allowed. Detergents have been developed to speed the cleaning and decontamination of equipment. These detergents alone or in combination with other chemicals such as oxidizing agents have reduced the need for caustic and acid washing of refinery equipment. Detergents, however, can interfere with the subsequent reprocessing of the oil removed. And they may have adverse effects on the refinery's water effluent system. Several criteria for detergent selection and field test methods are presented.

Introduction

Oil processing equipment has long been known to accumulate fouling materials while in operation. These can range from polymeric sludges, sometimes called coke, to various corrosion derived materials, such as iron sulfide, and scale forming mineral deposits formed from calcium, magnesium, barium, and silica among others. There are also components of the crude such as benzene which can permeate the equipment and must be removed to meet OSHA requirements. And, of course, flammability must be reduced.

For many years the techniques of caustic washing and acid washing have addressed many of these concerns. However, the generation of hazardous wastes from high or low pH washes has prompted the development of detergent cleaners which can remove or mitigate many of the expected foulants without generating hazardous or "listed" wastes. Further, a careful selection of detergent qualities can provide the

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best cleaning during turnarounds while minimizing troublesome reprocessing of the recovered oil and water solutions.

Many detergent formulations have been offered to the petroleum processing industry as "environmentally friendly heavy duty degreasers." While noble in word and goal, these terms are hardly quantifiable. Fairly objective measurements like the Hydrophilic / Lipophilic Balance fail to answer the necessary questions of cleaning ability and subsequent processing impacts.

In order to arrive at a detergent selection criteria the Chevron E1 Segundo refinery embarked on a series of tests, mostly field expedients, in order to provide a rational basis for selecting a cleaner to use during shutdowns.

The main concerns of widespread use of detergent / surfactant materials around the refinery were:

1) How well does it clean?

2) How much emulsion will it form in the effluent system?

3) In contact with other hydrocarbon streams, how much oil and grease will the detergent put into the effluent water?

4) How toxic is the detergent to the microbes in the effluent system's activated sludge plant?

5) How much foam will be generated in the drains and effluent system, especially in the Induced Air Flotation (IAF) systems?

SOAPS TESTED

JAYNE PRODUCT: JPX, Energy Plus Red, Energy

W. R. GRAINGER: Ball-o-Solv, Knockdown, Red Eye, Jump Start, Gobble

CHEMCO: Citrifresh, Synthene, APC

DIANA INDUSTRIES: HS-1000, EP680AC, Citrus EP680AC

WEST PENETONE: Citrikleen HD-CH

UNITED LABORATORIES: Zyme flow

RAMCO: Pac Attack

PROCTOR & GAMBLE: Joy

DOW: Fantastik

CHEMISOLVE: US 1600

CA RECYCLING CENTER: D - 99

HARVEY UNIVERSAL INC.: Harvey's Power Grease & Tar Cutter

We chose these detergents to represent a broad spectrum. While we never investigated the active materials in these cleaners, their advertising and characteristics indicated that we had examples of citrus or terpene based cleaners, enzyme-based cleaners as well as commercially available household cleaning formulations.

CLEANING ABILITY TEST

In order to rank the various soaps cleaning ability we coated thin carbon steel strips (corrosion coupons) with residuum (from SJV crude) and then exposed the treated strips to a 160 Deg. F stirred water solution which contained 10% of the various soaps. The residuum percent removal (by weight) was then recorded. Only the terpene based cleaners were effective under these conditions (See Figure 1). These cleaners were then tested at 5% and 1%. Only Q and C retained their effectiveness at 5% (See Figure 2). None of the cleaners in this test were effective at 1%.

EFFLUENT IMPACT TESTS

In order to evaluate the impact on Refinery effluent systems and potential environmental impact we measured the soaps foaming tendency, emulsion forming tendency, Oil and Grease contribution in the presence of hydrocarbon, and toxicity towards Refinery activated sludge bio organisms.

FOAM TEST For a foam test a 100 mLs graduated cylinder was filled with 90 mLs of tap water, 2 mLs of diesel fuel, and 0.9 mL of soap. The cylinder with the solution was stoppered and shaken vigorously ten times. The solution was allowed to settle for 10 minutes before measurements were taken. Foam ranged from 0 to 35 mL (See Figure 3).

EMULSION TEST For an emulsion test the emulsion thickness was measured after the above-mentioned test. The chemical cleaners exhibited emulsion ranges from 2 to 3 mL (See Figure 4). The majority of cleaners had an emulsion band of 2 mL, which was equal to the blank, and the initial amount of diesel used.

OIL & GREASE TEST After the above visual measurements were taken we transferred the test solutions to a 4 oz sample bottle which was left undisturbed for one hour. A one mL sample was taken from the middle of the bottle and tested for Oil and Grease content. The test used consisted of a Freon extraction followed by an infrared absorbance using the Foxboro Oil and Grease analyzer. The test displayed Oil and Grease values ranging from 1000 to 6000 PPM (See Figure 5).

TOXICITY TEST The toxicity test used was developed at the E1 Segundo Refinery to test the toxicity of Refinery chemicals towards their activated sludge. This test is not believed, or intended, to correlate with traditional effluent toxicity tests which are performed on higher organisms (e.g.. Daphnia, Rainbow Trout, etc.) Rather, this test is designed to use Refinery acclimated bio organisms in order to evaluate a given chemical's potential to cause an Effluent Treatment Plant upset.

The toxicity test is based on respirometry wherein a bioculture is sealed in a flask along with nutrients, test chemical, and an oxidation / reduction potential indicator. The Redox indicator changes color (blue to pink to clear) with the microorganisms' consumption of the oxygen. The test flask oxygen uptake is

then compared to that of a blank. Toxicity or inhibition is measured by the additional time taken by the organisms to consume oxygen compared to the blank.

We used two different concentrations 1,000 PPM and 10,000 PPM for the chemical dosage.

The toxicity test was based on a scale of 0 to 6 with zero being best (See Figure 6).

pH The pH of 1.0-% soap solutions is shown in Figure 7.

EVALUATION SCOPE LIMITATIONS In this study, while we performed tests on a variety of cleaners, we focused only on those cleaners, which can truly function as "heavy duty degreasers." As a result there is environmental impact information but no cleaning performance information on products, which may be effective as general purpose cleaning agents. Another aspect, which was not addressed, was the ability of the cleaners to reduce LEL and benzene. We have field experience here going back several years that the terpene based cleaners are effective at removing benzene when added during a steam out or water wash. Likewise other cleaners have been shown to remove benzene even though their effectiveness on heavy oils is poor by comparison.

C O N C L U S I O N We were able to find quantifiable differences in the cleaners tested. These differences, which relate to both the cleaning effectiveness and environmental impact, can be used to select the best detergent for and oil processing facility's needs. Because of the differences in foulants, effluent treatment facilities, disposal and reprocessing options, these tests are best viewed as a point of reference from which an intelligent detergent selection can be made.

eL E ANING AB IL IT Y

C i i m

3.5

3

2.5

2

1.5

1

0.5

0

Raling 3- Abo,,e 95% at 5 2 - 60-95% effective ~ 5% 1 - 20% or less effedrNeat 5% 0 - Little effed ci 10%

Q C J K O R A P H D E F M B G L N I U V S T

DE T E R GE NT

F I G U R E 1 - C l e a n i n g Abi l i ty

T op 5 Chemi cal el eaner s

m

O

120%

100%

80%

60%

40%

20%

0% m O K J Q C

DE T E R GE NT

F I G U R E 2 - Top Cleaners

AVE R AGE FOAM

35

30 A

,,,,,4 25

E v 20

E 15

0 1o I . I .

0 ~- ~ Z CL ~ ~ ~ 0 --

DE T E R GE NT

F I G U R E 3 - Average F o a m

AVE R AGE E MU L S ION

3.5<

3

2,5

v 2

1,5

21 0.5

0

Z

Z

DET E RGE NT

F I G U R E 4 - Average Emuls ion

AVE RAGE OIL AND GR E AS E

7ooo T 6OOO

ASO00 1~ 4000

v 3000

m

2OOO

1000

Z

DE T E R GE NT

F I G U R E 5 - A v e r a g e Oil and G r e a s e

6.00

5.00

I1• 4,00

, . ~ 3.00 | m

O 2.00 i n iB

X 0

I ~ 1,00

0.00 R E B I A F

T oxi ci ty T es t 0 = Best 6 = Worst

P D N L G C O H Q M J K

DE T E R GE NT

F I G U R E 6 - T o x i c i t y T e s t

pH 11.5

11

10.5

10

~j : 9.5

Q.., 9

8.5

8

7.5

7

S M H V J Q T D C B O I N L A P R K F G E

DE T E R GE NT

F I G U R E 7 - p H