New Vølund furnace camera provides a better view of flame front
The newly developed furnace camera can be placed in the rear ceiling where it provides a much better view of the dynamic of the flame front. The camera is air cooled, remains clean, and is easy to install and maintain.
Tests involving a modified location of the furnace camera led to the development of the all new, air-cooled cylinder camera. The purpose of the camera and the new location is to improve the regulation of waste combustion through a better overview of the dynamic of the flame front.
Modified location enables improved regulation
”We have developed a programme which can both calculate the position of the flame front, and then communicate the position to the control system. In reality, however, it has been difficult to use the programme for feeding regulation as most furnace cameras are located at the rear of the furnace. From this position, it is difficult to see more than the burn-out. For this reason, we wanted to experiment with another camera location in order to follow the flame front,” says Søren Nymann Thomsen, R&D engineer at Babcock & Wilcox Vølund, concerning the basis of the project, in which the camera was tested out in the rear ceiling of the furnace.
”We obtain completely different information by setting the camera at another angle. It shows much more of the dynamic in the flame front, which allows for better regulation,” he explains.
New angle on flame front.
To the left the flame front is captured with a traditionally placed burn-out camera; to the right the flame front is captured with the camera in the new location on the rear ceiling.
New camera developed for project
As a starting point, Babcock & Wilcox Vølund was not supposed to develop a camera on its own, but the need arose during a development project.
”The test camera we bought for the project became slagged within one day. So we had to decide whether to buy a new camera or to develop a camera made for the job. We opted for the latter,” recounts Søren Nymann Thomsen, who developed the air-cooled cylinder camera with a tiny peephole.
The camera is located in an air-cooled pipe. The tip of the camera is made of a ceramic material that can withstand temperatures of up to 1,300 degrees. The camera house is made of heat-resistant plastic that can withstand temperatures of up to 300 degrees. The plastic insulates the camera so effectively from the heat that air cooling is enough to protect the unit. Air cooling is advantageous because it is simple and inexpensive compared to water cooling, and it also serves to keep the camera free of slag. Air cooling also reduces the risk of acid condensation from the flue gas, which is a common problem with water cooling.
Seven-month test: Only dust to brush away
The camera was tested on AffaldPlus' furnace line 4 in Næstved, Denmark, over a period of seven months. ”It was installed in January 2011, and when I inspected it in July, all I had to do was brush off a bit of dust,” explains Søren Nymann Thomsen.
The camera can be installed without much complication in new plants, where it is integrated in the rear ceiling from the beginning. It is also easy to install in existing plants. Finally, an aluminium coupling makes it easy to set the camera in at the right distance.
”When the camera needs to be inspected or replaced, the process is similar to that of changing a battery. The entire cylinder is removed, and then it's a simple matter of screwing out the camera house. The camera is held in place in the camera house by an O-ring with an aluminium fastener. This means that the camera needs only to be pushed in place, and then it will be properly centred thanks to the O-ring,” Søren Nymann Thomsen explains.
Furnace camera from Babcock & Wilcox Vølund:
- Air-cooled cylinder camera for both rear wall and rear ceiling
- Provides a better view due to its wider burn angle (100 degrees)
- Stays cleaner than water-cooled cameras
- Easy to install (due to features like: thumb screws, aluminium coupling for indicating distance in furnace wall, O-ring suspension, and a camera house that can easily be screwed on and off)
Søren Nymann Thomsen, R&D Engineer with Babcock & Wilcox Vølund, is the man behind the new air-cooled Vølund furnace camera.
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