Q&A

(2012) Question 70: What are your experiences with processing oil sludge in the delayed coker?

One of our delayed cokers does process crude rag layer draw, wastewater sludge, and oily water. I think they primarily process the crude rag layer, however. What we do here is introduce the sludge after we have steamed the coke bed and established the quench water flow. We then temporarily remove the quench water to allow the sludge injection, and then we maintain a minimum temperature – I think it is around 600°F – to ensure that no oil accumulates in the cutting water.

(2012) Question 71: Is there any test method for performance evaluation of silicon-based antifoam agent used in coker?

Don mentioned the ASTM test procedure. It may also be beneficial to conduct elemental silicon loading. Silicone is a known molecule: dimethylpolysiloxane. The amount of elemental silicon introduced into the drum over a period of time can be tracked and compared with silicon in the distillate. Generally, the biggest step change to silicon loading is improving the chemical feed system.

(2012) Question 72: What are Best Practices for steam rates in cokers, heater velocity steam, valve purge steam, and drum steam out? Do newer, double-fired heater designs use less steam?

Sim Romero with KBC, who is sitting in the audience, will be conducting Coking 101 and will cover these topics. Since I am repeating Sim’s responses, I will summarize the answers.

(2012) Question 73: What is your experience with coke bed instability?

We have seen coke beds collapse during the beginning stages of the quench water addition. We have had operational problems because we were not able to get the quench water into the coke bed. We even tried alternating back and forth between the stripping steam and the quench water, but we were not able to penetrate the coke bed with the quench water.

(2012) Question 74: We have experienced leak issues around gaskets in cyclical and hot temperature services. What solutions have you developed to eliminate these issues?

At one of our two cokers, we use ring joint flanges from the coker heater outlet to the coke drum inlet and have had no leak issues. At the other coker, we have a short section of piping at the coke drum feed inlet that had raised face (RF) with spiral wound gasket drum (SPWD) that would occasionally leak.

(2012) Question 75: Please describe your best turnaround practice for cleaning and inspecting heat exchanger bundles versus replacement.

KBC is a nonoperating company, so we do not operate any equipment or conduct turnarounds. However, we do know that the bundle must be cleaned for inspection. We are accustomed to seeing hydrolancing or chemical cleaning for less severe services.

(2012) Question 16: What is the commercial experience on the use of H2 membranes in hydrotreaters or hydrocrackers for H2 recovery? What is a reasonable membrane life given the sensitivity to fouling and temperature changes?

At the Denver Refinery, we have a few hydrogen separation membranes. We call them our hydrogen purification unit. Our #3 HDS, which is currently our ULSD unit, was previously a gas oil hydrotreater until we revamped it in 2006. So, the HPUs (hydrogen purification units) were in consistent service from 1990 to 2006.

(2012) Question 17: Now that natural gas prices are low in North America, what options are available to increase refinery volume gain and product quality by exploiting low-cost hydrogen? Is the low hydrogen production cost impacting the economics between the selection of coking or hydrocracking?

There were a number of questions this year that requested information about how to effectively utilize low-cost hydrogen to increase refinery volume yields.

(2012) Question 18: What are the economic incentives to justify upgrading reactor internals? What techniques have been utilized to assess the performance of existing reactor internals?

The primary incentive is catalyst life and the ability to meet turnaround intervals. Gas and liquid distribution improvement results in increased catalyst performance and potentially longer catalyst life. Reactor internal upgrades may consist of quench decks, mixing chambers, and improved liquid distributor trays.

(2012) Question 19: Since API-932 (Waterwash Best Practices) was published, what has been the impact on reactor effluent air cooler washwater system design and reliability? Are there any active or ongoing studies to improve waterwash systems, in addition to API-932?

The question of issues associated with waterwash has been discussed since the API-932 was issued. This first slide gives a little chronology of some of the documents.

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