(78f) Ethylene Furnace Pre-Commissioning and Commissioning - New Furnace or after Major Revamp

ETHYLENE FURNACE PRE-COMMISSIONING AND COMMISSIONING – NEW FURNCACE OR AFTER MAJOR FURNACE REVAMP

Kari Enqvist
CEO, Chief Consultant
ENQ-Consulting Oy

Abstract:

This paper will give the overview of decisions and considerations for the furnace project schedule planning, design phase, inspections during equipment manufacturing, construction and hydrotesting to guarantee good pre-commissioning and commissioning, focus being in the pre-commissioning and commissioning itself, to finally achieve successful start-up and feed-in. All these activities have also significant importance for attaining long, trouble free operating life for critical furnace components. The learnings and experience, summarized in this paper, are collected from working in a numerous grass root and revamp projects in different operating companies and with different EPC contractors.

When starting the project to build grass root ethylene unit, new furnace in the existing plant or just doing a major revamp and technology upgrade to old furnace in older ethylene unit, to get smooth first start-up and feed-in as well as to achieve the design performance, if not with the first run but maybe the second run, the planning for the pre-commissioning and commissioning must to be kept in mind throughout all the phases of the project.

In early planning and design, the first considerations are where to locate the tie-ins, when to install those, how to isolate the construction site from the rest of the plant or how to minimize the disturbance to the rest of the plant ongoing construction, how to allow for safe and complete line cleaning, steam blowing, chemical cleaning etc. and to do all that while in the middle of the operating plant or in the middle of the project site where the construction work is still going on?

In project scheduling, the priorities for sequence of construction has to be set to allow for early start of pre-commissioning, but same time to allow for remaining construction to continue.

During the design, serious consideration has to be given about the prerequisites for hydro testing, chemical cleaning and piping blowing/flushing methods in order to minimize e.g. the eventual need for golden welds or to minimize the waiting time for already cleaned systems before the commissioning and burner ignition is possible.

Inspections in vendor shops are important e.g. for before fabrication checking critical piping/tubing process side condition for scale and coating. To speed up pre-commissioning, the mechanical cleaning might be needed before pipe bending and spools production. All large bore process gas piping is better to check carefully before spools production and to do the mechanical rust and scale removal, before lifting pipe sections on pipe racks and structures.

Automation loop checking, functional checking etc. before burner ignition testing is time consuming, which is often underestimated. BMS and controls test activities might cause limitations also for finalization of other still bending construction work.

Furnace start-up to Hot Steam Standby soonest possible after Calcium Silica refractory installation and chemical cleaning completion is mandatory to prevent any Alkaline Hydrolysis damage in the refractory and to get the initial Magnetite layer to protect the freshly chemically cleaned, very reactive BFW and Steam systems metal surfaces.

If all well planned and diligently done, operator is expected so see smooth start-up and feed-in with less or not at all furnace cold shut downs for venture, FG & Pilot gas filter and nozzle plugging, less coking due to corrosion products coming with HC Feed or Process Steam etc.