Coke Calcining Waste Heat Boiler

Hamon Deltak is an engineering firm that designs and manufactures waste heat recovery solutions for power generation and process applications. HDI has a global reputation for supplying quality equipment for the most demanding applications and operating conditions.

The project

A Coke Calcining Waste Heat Boiler designed and fabricated by Deltak in 1981 for a west coast refinery. A different boiler OEM was selected to debottleneck plant capacities in 1988. In 2012, Deltak was asked to come in to retrofit and upgrade the convection section and the radiant section of the boiler.

THE CHALLENGES

The convective boiler section had poor finning and eroding refractory, along with acid dew point corrosion concerns on the casing. In the radiant section of the boiler, there were coke fines built up in areas that were inaccessible, and there was tube erosion, and sagging on some of the horizontal tubes.

THE SOLUTIONS

For the Convection Section, HDI worked closely with the end user to design a warm casing to reduce acid dew point corrosion, utilizing an improved refractory design to help reduce erosion. HDI maintained the overall module size with no more than a 5% weight increase, and because of the tight tolerances, HDI engineers analyzed every component, including individual fin designs, row by row, to save weight.

For the Radiant Section, HDI provided an “In-Kind” replacement with the same dimensions, same basic construction, same basic weight, and same thermal performance, with the following changes being made:

  • To address the acid dew point problem, warm casing was designed and supplied rather than a cold casing design. 
  • HDI altered the bend detail of screen boiler tubes to not only create a maintenance and inspection lane into the furnace, but also to reduce the erosion rate while preserving thermal performance, and meet shipping and installation size limitations and restrictions.
  • Overlaid tubes with Inconel and added tube shields to reduce erosion.
  • Added eight nozzles through the casing and inner membrane, for instruments and urea injection, which included flexible penetration seals. The nozzles pass through the outer warm casing and inner tube membrane, which have different thermal growths.
  • Added a membrane on the Radiant Section floor tubes as a coke fine blocker and additional support to prevent stress and sagging of the tubes.
  • Added a scallop bar between floor tubes and wall tubes to prevent coke fines from building up.
  • Redesigned the original refractory floor with ceramic fiber insulation to reduce weight.
  • Revised the membrane corner detail to a diagonal, one piece membrane from the original two piece membrane.
  • To help with maintenance and cleaning, HDI added additional removable casing doors.

HDI also supplied a replacement the Outlet Duct Expansion Joint.

Aside from periodical tube shield replacements, the boiler has been running with no major issues since the Hamon Deltak, Inc. retrofit.