Q&A

(2010) Question 60: Please discuss advanced methods you use to monitor corrosion in operating units. Are any of these used in conjunction with the DCS for continuous on-line monitoring?

Marathon utilizes three methods of corrosion monitoring in the crude/vacuum units: multipoint resistance measurement (iicorr, FSM, GEBetz RCM) systems for naphthenic acid corrosion, ER probes, and corrosion coupons. While the use of coupons may not be considered an ‘advanced method’ for monitoring corrosion, we do continue to utilize them in our refining system.

(2010) Question 64: Please discuss the latest tray and packing technologies for improved fractionation efficiency in existing crude and vacuum units. In particular, what is the effectiveness in terms of fouling/plugging and resulting run length?

Well designed and installed fractionator tray, packing and liquid/vapor distributor equipment are one important tool in ensuring the crude/vacuum unit is able to reach its targeted runlength. A good understanding of operating parameters along with measures and systems to ensure that operation stays within those parameters are the other tools necessary to meet that targeted runlength.

(2010) Question 65: What methods do you use for heat recovery from furnace flue gas equipment at ~260°C (500°F)?

Air preheat systems are used for recovery of heat from flue gas down to app. 300 deg F. The 300 deg F temperature is set based on limiting dewpoint corrosion on cold metal surfaces. This temperature will vary depending on the materials employed, the sulfur content of the treated fuel gas, and cold ambient temperature.

(2010) Question 68: Do you see any benefit in continuing to steam strip crude tower distillate cuts since these side streams require further processing in down stream hydrotreaters?

We have observed definite benefits to steam stripping the distillate cuts and have been working to determine whether the benefit is worth the cost. The main purpose for distillate side strippers is to control product flash with a secondary purpose of lifting lighter material and affecting the product cuts.

(2008) Question 1: What are your experiences taking reactor effluent samples? What safety issues do you consider when taking samples? What do you consider to be best practices?

Question 1: What are your experiences taking reactor effluent samples? What safety issues do you consider when taking samples? What do you consider to be best practices? Edwin Yuh (UOP) UOP has traditionally included sampling capability in our licensed units when there are multiple reactor systems. For example, a sample point is typically installed at the pretreat reactor outlet before the cracking reactor in hydrocracking units to measure nitrogen slip. Many UOP licensees collect reactor effluent samples routinely. Quite a few recently licensed units are designed as integrated hydroprocessing units processing different feeds with different catalyst systems.

(2008) Question 2: Do you re-evaluate your unit operating procedures at regular intervals? How often? What principles/standards are these procedures reviewed against?

Question 2: Do you re-evaluate your unit operating procedures at regular intervals? How often? What principles/standards are these procedures reviewed against? David Rapavi (HOVENSA) HOVENSA reviews and re-issues unit operating procedures in accordance with OSHA Standard 1910.119 paragraph (f)(3), which states “Operating procedures shall be reviewed as often as necessary to assure that they reflect current operating practice, including changes that result from changes in process chemicals, technology and equipment, and changes to facilities.

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