Optimizing Coking Units in Refineries

What is Coking?

Coking is a unit operation found in more complex refineries to convert tarry residual or ‘resid’ streams from vacuum and atmospheric distillation into value-added products and intermediates such as LPG, naphtha, diesel, light and heavy gas oils. Coking is often accomplished via a delayed coking unit that includes a furnace, two coking drums— one online and one in regeneration, and a fractionating column.

Coking Process via Delayed Coking

In the coking process in refinery, the flow is heated to coking temperature in the furnace, then fed to the online coking drum. Large volumes of steam are injected after the furnace to delay the coking reaction until the flow enters the coking drum, where the heavy oil is cracked to lighter hydrocarbons, and into coke that mostly deposits in the drum for removal during the regeneration cycle. The cracked hydrocarbons then head to the fractionator column for separation of the different streams, with the bottoms recycled back to the inlet for another pass through the coker.

Fractionator In The Coking Process

In the fractionator, the remaining coke fines and initially injected steam exit the process in the fractionated products as particulate and water contamination. Depending on the product, removal of excess particulate and water is required to achieve final product quality, or to meet feedstock requirements for other unit operations, for example on kerosene or diesel streams feeding hydrotreaters.

Refinery Needs from Coking

Meet coker unit refinery production quotas
Ensure final product water and particulate standards are met on naphtha, diesel streams
Protect downstream units from production or reliability issues due to high solids or water levels in the coker fractionates

Optimizing Your Refinery's Coker Unit: Overcoming Production Challenges with Pall Solutions

Challenge	Solution
Effective Particulate Removal : Achieve daily coker unit production targets.	Meet coker production targets, product quality specifications and downstream unit protection by effective removal of particulate and free water contaminants that are driving fractionates out of specification.
Particulate Control: Consistently meet particulate and water specification on naphtha and diesel streams headed for final product blending.	For particulate control: Solid particle contaminants in the delayed coker operations coker are mostly coke fines, some very fine that may not be adequately removed by nominal filters, or filter media without fixed pore sizes that may exhibit unloading, media migration, channeling or poor sealing. A range of absolute and nominal rated filter elements is available to reliably reduce suspended solids to final product or intermediate solids specifications
Controlling Liquid: Ensure downstream reactor bed protection from delta P build or deactivation due to solids fouling or water contamination.	For liquids control: Conventional glass fiber coalescers will disarm due to the high volume of surfactants in the fractionates—naturally occurring sulfur compounds, or additives such as corrosion inhibitors or well treating chemicals. Disarmed coalescers will let large volumes of free water downstream until the elements are changed out, producing high water content fractionate. Other separators such as mesh packs, chevrons, cyclones, sand beds or electrostatic precipitators will not provide effective removal of the fine droplet emulsion created by the surfactants, so that high levels of free water will be seen downstream. High efficiency AquaSep® EL coalescers operate without disarming and provide effective removal of the fine emulsions to as low as 15 ppmv free water, protecting final product quality and downstream processes such as hydrotreater beds.

Challenge

Solution

Effective Particulate Removal :

Achieve daily coker unit production targets.

Meet coker production targets, product quality specifications and downstream unit protection by effective removal of particulate and free water contaminants that are driving fractionates out of specification.

Particulate Control:

Consistently meet particulate and water specification on naphtha and diesel streams headed for final product blending.

For particulate control:

Solid particle contaminants in the delayed coker operations coker are mostly coke fines, some very fine that may not be adequately removed by nominal filters, or filter media without fixed pore sizes that may exhibit unloading, media migration, channeling or poor sealing.

A range of absolute and nominal rated filter elements is available to reliably reduce suspended solids to final product or intermediate solids specifications

Controlling Liquid:

Ensure downstream reactor bed protection from delta P build or deactivation due to solids fouling or water contamination.

For liquids control:

Conventional glass fiber coalescers will disarm due to the high volume of surfactants in the fractionates—naturally occurring sulfur compounds, or additives such as corrosion inhibitors or well treating chemicals. Disarmed coalescers will let large volumes of free water downstream until the elements are changed out, producing high water content fractionate.

Other separators such as mesh packs, chevrons, cyclones, sand beds or electrostatic precipitators will not provide effective removal of the fine droplet emulsion created by the surfactants, so that high levels of free water will be seen downstream.

High efficiency AquaSep® EL coalescers operate without disarming and provide effective removal of the fine emulsions to as low as 15 ppmv free water, protecting final product quality and downstream processes such as hydrotreater beds.

Coking in Refineries Process Flow Diagram

Key Application/Filter Recommendations For Coking In Refineries(other applications not shown)

Application	Pall Product	Customer Benefits
Prefiltration prior to liquid/liquid coalescer	Ultipleat® High Flow filters, or Coreless filters.	Improves the efficiency and life of the liquid/liquid coalescer Ensures product quality and downstream unit reliability needs are met through effective removal of problematic solids
Water Removal	AquaSep EL liquid/liquid coalescer	Ensures product quality and downstream unit reliability needs are met through effective removal of problematic free water

Application

Pall Product

Customer Benefits