Furnaces fulfil many critical roles in various industrial processes. These vessels frequently have to continuously operate under extreme conditions that are characterised by elevated levels of heat, chemical attack, abrasion and mechanical stress amongst many others.
As a result of this and a number thermodynamic considerations, furnaces have to be designed for sustainable functionality over anything else. Therefore a number of desirable qualities like the ability to comprehensively inspect the vessels as they operate are generally not always achievable.
Whilst numerous indicators are used to assess the performance of operating furnaces and assist in detecting some defects, oftentimes stoppages and prolonged cooling times are necessary to perform complete visual inspections and further diagnosis.
However, with increasing consciousness on the need to ensure the sustainability of production operations, increasing production costs and pressures many manufacturers experience from fluctuating commodity prices. More proactive methods of inspecting furnaces give as much detail as possible while minimising any associated downtime are preferable.
DGC offers a comprehensive range of such Furnace Inspection Services which have been widely adopted in various industrial sectors like metals smelting, mineral processing, and thermal energy.
In this article we will briefly describe Furnace Endoscopy, one of DGC’s Furnace Inspection techniques, as well as outline a few typical findings from inspection campaigns.
WHAT IS IT
Furnace endoscopy allows for real time visualisation of the interior of a furnace while it is in operation. Enabling operators to fully assess the internal state of various parts of the unit. Furnace Endoscopy is normally targeted at identifying anomalies in terms of refractory lining wear, material flow issues, excess material build-ups or the physical state of internal equipment.
During inspection a highly robust, purpose designed water / air cooled camera is inserted through existing inspection openings on strategically selected parts of the furnace system. The camera is then manually manipulated to view angles of up to 360 degrees within the unit. Images are captured and labelled according to the opening location and visualisation angle.
After inspection images are then taken for further processing, analysis and interpretation in their industrial context. Analysis is always done in conjunction with furnace drawings and process data.
Theoretically the highly robust furnace endoscopy devices can be used to inspect units at any temperature. Units that operate at higher temperatures tend to provide clearer images as the internal high temperature glows provide improved lighting. Additional lighting may be required when inspecting units that operate at lower temperatures.
TYPICAL FINDINGS
Various extents of refractory lining wear. Depending on the extent of wear, recommendations for repairs may be accurately made.
Open joints in brickwork, could let heat through to inner refractory linings which are often less tolerant to furnace working temperatures. Caulking of the open joints or brick replacements may be proposed to remedy these.
Burner flame issues, if the flame within the furnace is not in the desired, typical shape, this could be an indication of issues with the air inlets, burner or fuel systems.
Wear on burner block
Mechanical damage on burners
System blockages from material build-ups
Assurance of the integrity of non-damaged areas
MAJOR ATTRIBUTES OF FURNACE ENDOSCOPY INSPECTIONS
The technique allows furnace operators to timeously identify a number of issues that are linked to the state of the furnace. Typically before the onset of the orthodox, speculative and lagging performance indicators.
Since furnace endoscopy inspections are conducted at working temperatures, there is no need to stop production operations and incur prolonged cooling times that conventional methods of inspection would otherwise require.
Finally, given the amount of quality information that may be interpreted from furnace endoscopy images, maintenance planners are able to timeously plan and schedule any necessary repair work with a great degree of confidence.
