Kiln inlet gas analyses done for the control of an efficient combustion and the quality of a clinker produced are constantly done in environments where temperatures vary between 1100-1300°C; dust concentration is about 2000g/m³; and gas flow is turbulent. Such measurement causes constant problems in the cement sector. The Turkish cement sector mostly uses petroleum coke, lignite, and certain waste as fuel. The combustion of these fuels results in high amounts of corrosive gas. Works done so far aimed at cooling standard measurement probes off by using substances such as water and oil and taking samples based on a cleaning with purge air.
However, measurement probes in furnace transition gas
analyses face problems such as
• High temperature (1100-1300°C),
• Very high amount of dust (2000g/m3 ),
• Corrosive environment (SO2 and other corrosive gases in high concentration),
• CaCO3 accumulation in catheters due to the process water used for cooling,
• Falling probe water pressure,
• Acid-metal corrosion due to excessive probe cooling,
• Fall of coagulated materials onto probes from preheaters and cyclones,
• Probe burning as a result of higher catheter temperatures due to material accumulation on probes,
• Occurrence of clogging due to dust accumulation in the probe,
• Clogging due to clumping of material in front of the probe based on waste incineration.
Such problems cause blockages, as well as breaks, cracks, and bends in probes if no measure is taken. Failure to take sufficient measures in transition implementations in our country caused measurement continuity to fall to a level of about 40 percent. The companies have installed
standard back blowing or 2 stages back blowing (separate compressed air application to the filter and the sonde) to prevent plugging of the probes against these problems. However, due to the incineration of waste, the substances may get sticky over time which cannot be cleaned with compressed air, and as a result this can cause plugging of the probe. In addition, samples cannot be taken during back blowing and continuous measuring is not achieved due to this situation.
The ENOTEC-CEMTEC probe that our company SETTEKNİK sells and offers after-sales services for is a water-cooled kiln inlet gas sampling probe, which can design the catheter length up to 4.5 meters; carry out dust filtration inside the catheter; and provide a minimum of 95 percent of measurement continuity thanks to its four different self-cleaning features
The CEMTEC probe avoids material accumulation thanks to its rotation of ±45 degrees. This eliminates problems such as bends and twists arising due to material accumulation. Plus, the 10cm-back-and-forth movement of the catheter prevents materials from accumulating on top.
The probe constantly opens the probe front thanks to its inner filter piston and prevents materials from accumulating in that part and, this avoids blockages in the probe. Moreover, the fact that this piston is smaller than the probe hole diameter allows the sampling process to continue during the piston movement.
Another feature provided allows for the cleaning of inner surfaces and filter pores of the probe through an instant high-pressure air in the form of a pulse instead of a long blow-back airin standard sampling probes. This pressure air is towards outside from the inside of the filter instead of being from the filter surface. This kind of an air flow avoids dust residues in pores and, thus, extends the life of a filter. The situation where the pressure air is from the filter surface can result in filter blockages and cause the life of the filter to shorten due to substances accumulating and heating up in that part.
All of these cleaning features of the probe can be checked using the PLC provided within the system. The PLC also makes it possible to follow the entire system work.
The probe is equipped with an externally protective flange pipe in order to avoid damage that may arise due to falling materials. This flange is produced using a special kind of highly heat-resistant steel in a manner to protect the probe from sharp falls.
In addition to back purge air tank, there is also another air tank right next to the probe which has 1000 liters capacity. This tank slowly takes the probe out using
high power in case of problems such as high cooling water temperatures and power failures that may occur in the system. Taking the probe out in a fast manner poses a risk of work accidents. The fact that the movement is pneumatic allows for the probe to take itself out even if there is a power failure.
The priority in the kiln inlet gas analysis is to take samples accurately. If sample is taken successfully, it can be sampled as a cold or hot extractive. In the past some problems occurred due to companies installed cold extractive system in the kiln inlet area with wrong cabinet design and standard equipment. If the system is designed with appropriate cooler and filters, these systems can operate at the optimum level. Equipment such as cooler and humidity filter is not used in hot extractive systems. The gas is sampled by entering the analyzer directly. However, the initial investment of such systems are higher than the cold extractive systems. Also, these systems’ maintenance and interventions in case of malfunction can only be done by authorized service. This situation will also add maintenance and technical service costs for a system which already has a high initial investment cost. The cold extractive systems are more compact and problems can be detected by the end user.
There are also some misleading and incorrect information on the loss of SO2 value in the cold extractive systems are being speculated. Cold extractive systems have been in use and accepted globally for emission control of SO2 source fuel derivatives which are coal, petroleum coke, fuel-oil and so on. Loss of SO2 due to condensation in the sample gas should always be low at the ignorable level in the sample gas containing high concentrations of SO2 . By doing benefit-cost analysis of the systems, our company which can make installation in both systems; have tested
that cold extractive SIEMENS systems (if properly designed) work efficiently.
In our first project that we realized the selling and commissioning processes in Turkey, our customer was complaining that their old probes were constantly becoming blocked, cracked, and broken and that they were significantly wasting the time of their maintenance team. Our customer purchased the ENOTEC CEMTEC probe and Siemens gas analysis system after we provided them with the necessary technical details. The probe and the gas analysis system reached a working efficiency of over 99 percent within 6 months following their installation, and so
far no technical intervention was required.