Diseño de un sistema automático de dosificación de químicos para calderas de baja presión en la Empresa TERMOESMERALDAS

Abstract

Corrosion and scale accumulation are the main problems caused by the decrease in the chemical quality of the feedwater in the boilers of thermal power plants because they affect steam production and the plant's equipment, thus reducing its performance and efficiency and even putting them out of operation; therefore, the objective of this research was to design an automatic chemical dosing system for low-pressure boilers at the Esmeraldas II Thermal Power Plant. For the development of the system design, direct observation, interviews with the thermal power plant personnel and laboratory analysis were used to determine the dosage amount of the dissolved oxygen scavenger and the pH regulator to ensure that the pH and dissolved oxygen parameters of the feed water, boiler water and steam meet the quality criteria established by local and international standards (ASME, ABMA 402, etc.); and based on this, the dosage, sizing and distribution of equipment were determined. Based on the data obtained, it was determined that the system will consist of 2 morpholine tanks and 2 sodium sulfite tanks that will dose the chemicals to the feed tanks with flow rates of 53,8 l/h and 26,7 l/h for the amine; and 2,05 l/h and 1,7 l/h for the sodium sulfite together with the required instrumentation (level transmitters, dosing pumps, solenoid valves, online pH meter, etc.) controlled by a distributed control system (Ovation 3.7). It was concluded that the automation of the chemical dosing process allows greater performance of the plant and auxiliary equipment and it was recommended that CELEC-EP evaluate the implementation of the automation process to ensure greater efficiency and effectiveness in the chemical treatment of water.