Cameras in for the kiln

Saudi Cement is employing thermal imaging equipment at its plant in Hofuf, Saudi Arabia. The equipment is monitoring two 10,000 tonnes/day kilns equipped with six-stage preheaters via three Thermoteknix installations.

The supplier’s ThermaScope HTV cameras provide live images of the burner pipe as well as of the first- and second-stage coolers at the plant. The cement company chose the HTV model as it offered direct output to a CCTV display, giving operators and control engineers a clear image of the process.

Abnormal conditions such as over- or under- temperature, poor temperature distribution or irregular flame shape is instantly shown. These can be alarmed and interpreted by the operator or process engineer with analysis tools and temperature displays.

Live video images of the process are displayed on PC monitors in the control room, with every pixel in the field of view measured for exact temperature evaluation.

The temperature at specific points or within areas of interest are measured and can be continuously displayed and recorded. Alarm points for areas of interest are defined, while analogue control outputs can be programmed for interfacing with process control algorithms.

The camera interface and control box houses the signal processing electronics and retract control logic for the FPA sensor. The video image from the FPA sensor is optimised at a ThermaScope control box. The system employs electronic image enhancement algorithms to provide an optimal video image at the control room monitor.

Temperature sensor data is also processed in the control box and sent to the control room processor for display, alarming and control circuit output.

Additionally, the control box monitors camera housing temperature sensors and flow rates within the ThermaScope air and cooling water support utilities. When any support system problems are sensed, the control logic initiates camera retraction to protect the sensor and housing.

The two kilns at the Saudi Cement plant presented challenges when it came to installing the units. Each kiln features tertiary air ducts on either side, the supports for which interfered with the line of sight to the kiln and obstructed the view of areas where problems are likely to occur.
Two Thermoteknix Centurion stereo systems were mounted on 30m-high towers to eliminate all blind spots on both kilns, resulting in a control room display with clear, single-brick resolution and all girth gear visible.

Interface to the Centurion unit is provided by a 19-inch, rack-mounted, ruggedised PC interface unit, which supports up to two scanners, eight pyrometer inputs, eight tyre/kiln slip inputs and 12 relay outputs.

Mono/stereo and fill-in pyrometer configurations enable it to operate on covered kilns or where pillars or obstacles obstruct the line of sight between scanner and kiln.

Two or more TK50 scanners can be connected to the WinCem software for elimination of shadows and obstructions.
Alternatively, if only a few objects obscure the line of sight between scanner and kiln, fixed point pyrometers can be placed between the object and the kiln, with the signal fed directly into WinCem. This provides automatic integration into the Centurion scanned data for an unobscured view of the kiln.

At the Hofuf Saudi Cement Plant, WinCem alarms have been set to activate blowers to move in and cool essential areas of the kilns.

Avoid costly and unexpected downtime

Effective predictive or condition-based maintenance work today involves getting real-time data to the user in order to give more visibility. This is possible through an MES (Manufacturing Execution System), which interfaces with existing SCADA, HMIs, other process control and automation systems (such as variable speed drives) as well as business systems.

According to Jez Palmer of Schneider Electric, the level of information provided by an MES can begin with standards reports. These, he said, can cover many areas, including alarm states and statistics, run hours, tag calculations and values for aspects, including kWh and processes marked as shift parameters.
In addition, users can access alarm management reports focusing on correlation, frequency, major events and longest standing, which will help identify common problem areas that may require more regular maintenance, or highlight areas that could potentially fail. This ensures preventative maintenance work can be carried out before the problem results in costly and unexpected downtime.

“Taking the information a step further, businesses can look at the state of a plant or specific process and analyse its behaviour,” said Palmer. “Production-specific modules can provide real-time data on yield, energy consumption per output unit, output per shift, as well as actual versus targets on materials, energy, waste, emissions and product output.”

Access to this level of detail can offer economic benefits in a number of ways. Information on aspects of the plant, such as identifying ’lost production’ shows the potential of a machine to deliver more output. Also, quickly identifying causes that can be detrimental to production, such as operator issues and machine or material issues, or raising production consistency and reducing waste, are all factors that can have an impact on the company’s predictive maintenance schedule.

As well as real-time information, historical data can be used in predictive maintenance. It can assist in planning a maintenance programme, as the records can be used to predict when issues will happen in the future, based on trends and patterns. This, said Palmer, can help with budgeting, again controlling costs as the amount of unplanned, ad hoc work should be reduced.