To choose a demulsifier for refinery desalting, I recommend matching the chemical to the crude oil emulsion, desalting equipment, operating conditions, and treated-water requirements. The most reliable selection method is not to choose a product from a general catalogue alone, but to compare candidate demulsifiers through controlled laboratory bottle tests and, when possible, a monitored plant trial. I evaluate water separation speed, interface quality, residual water, salt removal, chemical dosage, and downstream effects before making a recommendation.
A demulsifier that performs well on one crude blend may not deliver the same result on another. Crude oil composition, asphaltenes, solids, naphthenic acids, brine salinity, temperature, mixing intensity, and residence time can all influence performance. As a chemical reagents supplier, Ling Rain helps buyers define a practical screening process instead of relying only on product names or a single performance indicator.
Refinery desalting is designed to remove entrained water, dissolved salts, and associated inorganic contaminants from crude oil before downstream processing. The demulsifier supports this operation by weakening the interfacial film that keeps water dispersed in oil, allowing water droplets to coalesce and separate more effectively. However, the demulsifier is only one part of the system; temperature, wash-water quality, mixing, electric field strength, and settling conditions also affect the result.
Before selecting a product, I first define the actual operating problem. A refinery may be experiencing slow water separation, high salt in desalted crude, excessive rag-layer formation, unstable desalter interface, high chemical consumption, or oil carryover in the wastewater. Each problem can require a different balance of demulsification speed, interface control, and oil-water selectivity.
I begin by collecting representative information about the crude feed and the emulsion. Useful data includes API gravity, viscosity at operating temperature, water cut, salt content, solids content, crude blend ratio, and the presence of heavy or acidic components. If the refinery processes multiple crude sources, I recommend testing the normal blend as well as the most difficult expected blend.
The emulsion history is equally important. I ask whether the problem appears after crude blending, after heating, following tank transfer, or during changes in desalter throughput. A stable emulsion formed by high shear may require a different product response from a naturally occurring water-in-oil emulsion. Without this background, a laboratory result can be difficult to interpret correctly.
The candidate demulsifier should be screened under conditions that reasonably represent the desalter. Important variables include crude temperature, wash-water dosage, mixing energy, residence time, electric field conditions, and injection location. As a controlled starting point, many technical teams use bottle-test temperatures within approximately 40–80 °C, but the correct test temperature should reflect the actual process rather than a universal rule.
I also record the available separation time. If the equipment provides only a short residence period, fast water release and a clean interface may be more important than performance observed after several hours. If the desalter has longer settling conditions, the evaluation can include both early separation and final water clarity.
I do not recommend screening only one demulsifier at one dosage. A practical program normally compares several product types or formulations at multiple dosage levels, because performance can change significantly with concentration. Candidates may be based on different combinations of resin, polymer, polyol, or other surface-active components, depending on the supplier’s formulation strategy and the crude application.
For an initial laboratory screen, a buyer may compare low, medium, and high treatment levels around the supplier’s recommended range. The exact dosage must be determined by testing, and it should be expressed in an operationally useful unit such as milligrams per kilogram of crude. A product that works at a lower dosage is not automatically the best choice if it produces a poor interface or increases oil loss to wastewater.
A bottle test should use a representative crude and consistent mixing, heating, dosing, and observation procedures. I recommend recording the time to first water release, separated-water volume, interface appearance, residual water in the oil phase, and the amount of rag layer. A practical observation schedule can include readings at 5, 15, 30, and 60 minutes, followed by a longer observation period when the plant residence time requires it.
The test should also examine the water phase, not only the crude phase. Cloudy water, excessive oil droplets, or a persistent emulsion may indicate poor selectivity or excessive treatment. A 24-hour observation can be useful for confirming whether a separation that appears acceptable initially remains stable, although the result should not replace an operating-condition trial.
Fast separation is valuable when desalter capacity is limited, but speed alone does not define a successful demulsifier. I look for a distinct interface, limited rag-layer growth, and water that separates without excessive oil carryover. A product that releases water rapidly but creates a thick, unstable interface may cause operating difficulties later.
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The chemical should be evaluated against the refinery’s salt and residual-water targets. Demulsifiers do not remove dissolved salts directly; they help separate the brine that carries those salts out of the crude. For this reason, poor desalting may result from insufficient wash-water contact, poor mixing, inadequate settling, or electrical problems rather than from demulsifier chemistry alone.
I therefore compare candidate products using the complete desalting result, including crude salt, residual water, and water quality. If a product improves visible separation but does not improve salt removal, the refinery should investigate the wider process before increasing dosage.
A demulsifier must be considered in relation to downstream units and wastewater treatment. Excessive chemical addition may influence furnace fouling, corrosion control, downstream catalyst sensitivity, or effluent treatment requirements, depending on the formulation and process conditions. These effects cannot be assumed from a laboratory bottle test, so I advise reviewing the product’s technical information and conducting appropriate compatibility checks.
Purchase price is only one part of the chemical cost. I compare treatment cost per tonne of crude, required dosage, injection reliability, water handling impact, and the potential cost of unstable operation. A product with a lower price per kilogram may have a higher total cost if it requires substantially more dosage or creates additional wastewater problems.
Crude blends change, and emulsion behavior can change with them. Applying one fixed dosage without monitoring can lead to under-treatment during difficult feeds or unnecessary chemical consumption during easier operation. I recommend defining a normal operating range and a controlled adjustment method based on crude properties and desalter performance.
One test may identify promising candidates, but it cannot represent every seasonal feed, blend, or process disturbance. I prefer repeated tests using fresh representative samples and, where practical, a short plant trial. The trial should define success criteria in advance, such as improved salt removal, stable interface, acceptable water quality, and no adverse downstream observation.
I suggest scoring each candidate against technical, commercial, and service criteria. The technical section can include separation time, interface quality, residual water, salt performance, water-phase clarity, and dosage response. The commercial section can include price per kilogram, estimated treatment cost, packaging, minimum order quantity, shelf-life information, and lead time.
| Evaluation Area | Questions to Ask | Evidence to Request |
|---|---|---|
| Technical performance | Does the product separate water and control the interface? | Test method, dosage range, and representative test observations |
| Process compatibility | Is it suitable for the crude blend and desalting conditions? | Technical data sheet and application guidance |
| Supply reliability | Can the supplier support repeat orders and changing demand? | Packaging options, production schedule, and shipment planning |
| Technical service | Will the supplier help interpret test results? | Sampling support, test recommendations, and troubleshooting process |
I also recommend confirming sample quantity and logistics before starting the evaluation. For a laboratory screen, a buyer may request 500 mL or 1 L samples of each candidate, depending on the number of tests and the laboratory procedure. These quantities are planning examples rather than universal requirements, so the supplier and laboratory should agree on the sample amount in advance.
At Ling Rain, I approach refinery desalting requirements as an application-matching project rather than a simple product transaction. We can review crude characteristics, operating temperature, emulsion symptoms, dosage expectations, and available test information before suggesting a suitable demulsifier direction. Where specific performance data is not available, I use conservative language and recommend controlled testing instead of making an absolute claim.
Our support can include product information, sample coordination, dosage discussion, packaging planning, and communication about repeat supply requirements. Buyers should provide as much process information as possible, including the crude type, desalter configuration, current chemical, observed failure mode, and target operating conditions. Better input generally supports a more relevant screening recommendation.
The best demulsifier for refinery desalting is the one that delivers acceptable separation, salt removal, interface stability, and downstream compatibility under the refinery’s actual conditions. I recommend beginning with crude and process characterization, screening multiple candidates at controlled dosages, and confirming the preferred option through a monitored plant trial. Do not select solely on product price, a generic description, or one bottle-test observation.
As the next step, prepare a short technical brief containing your crude properties, operating temperature, water and salt results, current demulsifier dosage, separation problem, and expected purchase volume. Share that information with Ling Rain so we can help define an appropriate sample and evaluation plan. A disciplined selection process can reduce trial-and-error purchasing and provide a clearer basis for long-term demulsifier supply.
Contact us to discuss your requirements of Demulsifier For Refinery Desalting. Our experienced sales team can help you identify the options that best suit your needs.