Coking Acidic Wastewater: Inside the SINOKLE KHC Coalescing Route That Needs No Chemicals

Among the streams that come out of a coking plant, acidic wastewater has a reputation for being stubborn. Its composition is messy - high concentrations of coke powder, emulsified oil and assorted harmful chemicals - and the consequences reach beyond the treatment unit itself. Production stability suffers, environmental compliance becomes a running risk, and the people working around the plant are exposed to odours and hazards. As discharge rules tighten, the old approach of dilution and settling no longer holds, so the industry is looking for processes that are both more effective and more dependable.

What Makes This Water Difficult

Four characteristics explain most of the trouble.

• Fine coke powder. Particle size clusters between 5-20 um, and the 10-15 um fraction alone accounts for as much as 56.44%. Particles that small settle readily inside equipment and pipework, and blockages follow.
• Emulsified oil with tiny droplets. Emulsified oil makes up more than 60% of the total oil load, with droplet size concentrated at 10-25 um. The emulsion is stable, so oil-water separation is slow and the stripper's efficiency drops.
• Wide swings in composition. Oil content can reach 500-3000 mg/L, sulfide 10,000-20,000 mg/L, and ammonia nitrogen 10,000-20,000 mg/L. Concentrations jump around, pungent odours appear, and both the neighbourhood and the operators pay for it.
• Clogging equipment. Over long runs coke powder and emulsified oil build deposits inside the stripper. In bad cases the unit shuts down unplanned, and the loss is substantial.

Taken together these factors inflate operating cost and expose the plant to penalty risk, which is why a route that removes pollutants stably and efficiently has become the precondition for green upgrading.

The SINOKLE Process Layout

The route SINOKLE put together centres on CDFU cyclonic dissolved air flotation, a fine filter, and the KHC high-efficiency coalescing oil remover. It leans on purely physical demulsification and separation. No chemicals are dosed, so the risk of secondary pollution is cut at the source rather than managed afterwards.

Stage one: CDFU cyclonic dissolved air flotation

As the front-end pretreatment unit, CDFU deploys micro-nano bubbles with a diameter of 5-30 um to break the emulsion. The bubbles make full contact with the emulsified oil, rupture the oil-water interfacial film, and let oil droplets coalesce quickly and float for removal. In single-stage duty the unit reaches an oil removal efficiency above 90% and a suspended-solids removal rate beyond 80%. When influent flow or quality shifts, the treatment performance stays stable - an important point, because this feed rarely behaves.

Stage two: fine filter

Effluent from CDFU passes into a fine filter that lifts out remaining tiny suspended solids and residual coke powder. The purpose is not to polish for its own sake: a cleaner stream protects the coalescing cartridges downstream and keeps the whole train running steadily over the long term.

Stage three: KHC high-efficiency coalescing oil remover

KHC relies on patented coalescing packing and high-precision coalescing cartridges, achieving oil-water separation through purely physical coalescence. It can take out emulsified oil droplets above 0.1 um, and the demulsification performance is stable and repeatable. The separated waste oil carries low moisture and good quality, which means it can go straight back to refining. That single detail does a lot of work - waste discharge falls, resources are recovered, and production cost comes down.

Advantages That Show Up on Site

• Fully automatic, enclosed and pressurized. The risk of leakage and odour spread drops sharply, which helps both plant safety and neighbourhood relations.
• Mostly static equipment. Few moving parts means low maintenance demand, a long service interval and solid operational reliability.
• No chemical dosing. Without coagulants there is no scum and no sludge to speak of, so solid-waste disposal pressure falls.
• Small footprint, strong shock resistance. A good match for coking plants where space is tight and feed quality swings widely.
• Dual economic and environmental gain. Waste oil is recovered and reused, energy and consumables are saved, and compliance risk comes down.

Reading the Four Characteristics Together

It helps to see why these four points interact rather than sit side by side. Fine coke powder gives the emulsified oil something to cling to, which stabilises the emulsion and makes gravity separation even slower. The wide swings in concentration then punish any process that assumes a steady feed, and the deposits that form inside the stripper are the physical consequence of that same combination. A treatment route that works here has to tolerate the swings, break the emulsion without adding reagents, and keep solids moving rather than settling where they should not.

Where This Is Heading

The process has already been applied at a number of refining and petrochemical enterprises, where it has run stably and delivered clear economic benefit. As the technology matures and spreads, more coking plants are expected to adopt it, and the industry moves a step closer to a low-carbon, green and sustainable footing. For operators weighing it up, the appeal is straightforward: a physical route that keeps the oil in a form worth recovering, and keeps the water inside its permit.