Planta Cementera, Otavalo
Review
UNACEM Ecuador (before “Lafarge Cementos”), is a company dedicated to manufacture cement. Their industrial plant is located in Otavalo, Imbaura province, Ecuador. The plant provide two clinker kilns for their productive process. The line No. 1 has a pre-heater tower of four stages with a gases flow stream from the kiln; This process work with liquid residual combustible oil, pet coke and biomass. The Line 2 has a tower pre-heater of five stages, besides of pre-heater and tertiary air works with liquid residual combustible, solids (pet coke) and biomass.
In 2015, the Company received the Environment license of co-process waste dangerous products for cement kilns (Governmental agreement 048. Official register N° 439 of 3td of May 2011, from environment minister of Ecuador), turn into the first industrial plant of the country that could do this treatment controlled For that,, UNACEM Ecuador supervised their emission gases continuously, mainly the concentrations of CO, SO2, NOx, VOC oxygen reference at 7%.
Design
For this CEMS in UNACEM Ecuador, was installed a complete system with field instrumentation. Through an analytics enclosure, which has gas analyzers units correspond to variables required, the control system doing the correction on line.
The stack emission gases of the line 2, was selected a ring´s measurement where were installed the following instruments: a extractive sample heated probe BÜHLER, with a dust filter of 2 micros heated to 180°C to reduce condensates , an absolute pressure transmitter SIEMENS, SITRANS DSIII model; a RTD with a temperature transmitter in head.
The sample gas is transported approx., 30 meters length through a heated hose to the analytic enclosure. The analytic enclosure provided of 19 inches rack, double door with safety glass door each, auto-supportable and laterals removable.
In this enclosures was installed a ULTRAMAT 23 (U23) to measure CO, SO2 and O2; a HCT gas analyzer FIDAMAT 6; and NOx gas analyzer with chemioluminicence technology, it was required with Ecuatorian norms.
The sample conditioning systems (SCS) is composed of a dust filter 2 micras PTFE made, with moisture detector. In addition, a simple gas compressor cooler, with two gas stream, 320 kJ/h capacity, two peristaltic pumps to remove the condensation and drain it to a condensate tank of 6.5 lt capacity, with a high level switch installed; a sample gas pump diaphragm type with a needle valve to regulated the gas flow rate. Finally, a rotameter installed downstream to the inlet port of the U23 with a parallel connection with the outlet port.
Secondly, the analog outputs of U23 of the gas concentration conditioned through a PLC SIEMENS S7-1200, at 7% O2 and communicated (PROFIBUS DP) to a DCS SIEMENS, PCS7 based, called CEMAT.
The control system is also in charge of validating the starting conditions of the gas outlet; for example, check the temperature of the probe and heated hose is maintained at 180 ° C, the cooler temperature reaches 5 ° C, there is no humidity in the sample line and the high level sensor with condensate tank not be activated. Those validations connected in series to enable the operation of the suction pump sample gas.
The display of process variables showed on a touch screen display, SIEMENS, KTP-700 model, second generation of 64K color. It allows you to see the starting up sequence changing the color of each instrument according to their status. In addition, let see trends in real-time gas concentrations of both raw variables as the corrected, logging alarms gas concentration levels as the levels allowed by the Ecuadorian Standard. Finally show an explanatory menu helps each deployment, with the ability to view excerpts from text documents such as standards and technical articles on the continuous measurement of gases.
Advantages.
The proposed design was very versatile and flexible in the assembly system in Colombia, reducing transportation costs and implementation. Likewise, the control equipment used in Siemens SIMATIC (S7-1200 PLC) line and its monitoring screen “touch screen” KTP-700, become strong, the control system and improve undoubtedly the presentation of the process variables discrete and analog system signals.
Additionally, the control system has wide potential offered by communications integration with existing systems, or by RS-485 networks via PROFIBUS-DP, Ethernet or PROFINET networks.
Conclusions
The solution offered, integrates the best SIEMENS product solutions in different segments, under the concept of TIA (“totally integrated automation”). The pressure transmitter SITRANS DSIII, gas analyzers ULTRAMAT 23 and FIDAMAT 6, the S7-1200 control system, KTP 700 display 7 “high resolution color and all its accessories electrical connection of the SIRIUS family, allow a solution CEMS integral and open as it is robust and differentiating CGA’s market.