cement
Just like in power production, energy efficiency plays an important role in a good functioning cement plant and process control is indispensable for producing a high quality product. Therefore it is necessary to continuously monitor the processes with analysis systems, also in order to comply with the relevant emission limit values.
Kelma has a product range, covering gas detection, gas analysis systems capable of measuring in very dusty atmospheres and at high temperatures or in a stack up to non-contact temperature measurements for a precise temperature control.
Many cement plants use pulverised coal as a fuel. This coal is often pulverised on-site in a coal mill and stored in coal bunkers. The coals mills are inertisised with nitrogen in order to prevent an explosion. This means that for a safe operation of the mill, it is required to monitor the O2 concentrations at all times during operation of the mill. Furthermore the pulverised coal can start to smoulder. This will cause a dramatic rising in CO-levels, with the eminent risk of an explosion as a consequence and at the same time this smouldering fire can get out of control in no time. For that reason a continuous monitoring of CO is required.
The raw material enters the kiln via pre-heater and pre-calciner. In the kiln, the sintering process takes place at temperatures up to 1.400 °C. The final product, clinker is leaving the kiln at the opposite end for further processing. Producing high quality clinker requires accurate control of energy input: Insufficient heat will leave unconverted lime while excess heat increases fuel consumption and could damage the kiln. Energy input and optimal combustion conditions can be derived from gas analysis data taken from the process gas at the kiln inlet. The concentrations of CO, NO and O2 and in some cases CO2 and SO2 need to be monitored continuously inside the kiln close to the raw material inlet. These measurements have to take place under extremely harsh conditions (high temperatures, high dust load, high concentrations of corrosive gases,...). Sick has developed a unique measuring system dedicated for this application. Furthermore we can add an optical pyrometer for continuously monitoring the temperature in the kiln.
In addition to the rotary kiln, modern cement plants are equipped with a multistage cyclone pre-heater and a pre-calciner. The pre-heater is using the excess heat from the kiln and the pre-calciner. Pre‑heating and pre‑calcining of the raw material shorten the sintering process in the kiln, the overall fuel consumption is reduced. Here too CO, NO, O2 and SO2 should be monitored.
Before emitting the gas from a stack some scrubbing and cleaning is required. Dust will be removed with a filter system appropriate for the application. To make sure a brake-through is detected at an early stage and no emission limit is surpassed, there are some cost effective solutions in our product range. When an electrostatic precipitator is used, in general the dust particles are humidified to increase conductivity. The sprayer intensity is controlled by continuously monitoring the gas volume flow with our FLOWSIC100. In this ESP there is also a risk of fire/explosion, therefore a fast CO measurement at the filter inlet is required. In case of CO peaks, the filter can be shut down in time and be prevented from serious damages.
Finally, depending on the kind of fuel used and local environmental regulations, a number of pollutants are to be monitored continuously in the flue gas at the stack along with dust (particulate matter, PM), gas flow, and the reference values H2O, temperature and O2. The monitored data is transferred to a specific data acquisition system for further processing and reporting to the authorities. In case of co‑incineration of alternative fuels, additional components such as HCl, HF, Hg and TOC may be required to be monitored as well. Monitoring equipment used for CEM applications must be approved by the government (for example Waste Incineration Directive 2000/76/EC) fulfilling the quality standard EN 14181. Here too we can supply you with a solution for all of these parameters.