Challenge
- Reduce electrical energy costs of coolant water flow control using speed management for motors that control pumps. The procedure was done using manual valves.
Solutions
Results
- A reduction in energy consumption of 500 kW, equivalent to 50%, maintaining the same coolant water flows for the process.
Founded in 1920, Enaex, a Chilean company, produces and distributes ammonium nitrate and a full range of explosives and blasting materials serving the mining, utilities and seismic surveying sectors.
In recent years Enaex (part of the Sigdo Koppers groups since 1993) has experienced growth both locally and internationally, increasing the presence of its products in more than 40 countries.
Its Prillex América production plant implemented a series of PowerFlex® 7000 medium voltage AC drives to gain major energy savings for its coolant water flow control.
The collaboration between Enaex and Rockwell Automation allowed the plant to continue operating fully during project implementation without affecting the production process in any way.
Starting in 2010, when its fourth plant, known as PANNA 4, came on line, Enaex S.A. reached an annual production capacity of 850,000 tons of ammonium nitrate (technical grade), making it the largest production center in the world, with enough output to supply a large part of consumption in Latin America an other countries globally.
This complex, located in the city of Mejillones (Region II of Chile), is near the largest mining center in South America and close to the Port of Mejillones. Specifically, the Prillex América plant is situated seven kilometers from Compañía Portuaria Mejillones S.A., known as Puerto Angamos, which handles the export of ammonium nitrate to more than 40 countries on five continents.
Enaex as a corporation decided to establish a strategic growth plan. Energy efficiency is one of the primary pillars of this strategy. As a result, the company identified an opportunity to save energy in its coolant water flow control by managing the speed of motors that control the pumps in the plant.
“Energy costs are an important aspect of the cost of each ton produced, so the impact of any energy savings on our production process is always welcome," explains Alberto Yagnam Zalaquett, Engineering Superintendent, Enaex.
To obtain these energy savings, the company installed three Allen-Bradley PowerFlex 7000 medium voltage frequency drives supplied by Rockwell Automation. These systems have 4.16 kV and 1000 hp each.
“We have been Rockwell Automation customers since 1998. All the medium voltage frequency drives we have in the plant are from Allen-Bradley. We have had good results with this equipment over the years. For that reason and for reasons of standardization, we finally decided to go forward with the project with Rockwell Automation,” says Yagnam.
Optimum Results
Implementation of the project was completed in October of 2012, taking advantage of the servicing of Unit 3 (PANNA 3), which was taken out of service for a month. To house the equipment, the company built an electrical room, which cost very little since the size and the Direct-to-Drive technology of the frequency drives drastically reduced the dimensions of the room.
“In addition, the equipment frame supplied to us at that time for the same power was also smaller in size," states Yagnam.
Prior to implementing the system, the Prillex América plant was unable to control pump motor speed for the coolant water flow control of Unit 3. This procedure was carried out using manual valves, which meant that they operated continuously at nominal speed. This, in turn, meant that the motors were, in practice, consuming nominal power.
“The power consumed by the coolant system, prior to the modification, was 1 MW, that is, we had two 746 hp motors each connected directly to the line. Afterwards, with the installation of the frequency drives, we were able to reduce consumption by 500 kW while maintaining the same coolant water flows for the process," explains Yagnam.
According to Yagnam, the economic indicators of the project made this highly attractive.
“We invested US$1,207,000 and obtained a net present value of US$2,472,000, an IRR of 59% and a payback of 1.7 years. In fact, once in operation, the measured energy savings surpassed the initial project numbers," he explains.
According to Yagnam, the greatest challenge for the project team was initially to gather everything necessary to execute during the servicing of the unit and, secondly, to complete construction within the month that the service shutdown lasted.
“Personally, this is an important achievement since not a single ton of product was lost due to the implementation of the project. That is to say, the impact of project implementation on production was zero," he states.
Rockwell Automation Support
The engineering superintendent at Enaex explains that the company relied constantly on the technical support provided by Rockwell Automation.
“For example, our standard is to support all control circuits for our frequency drives using UPSs. We were faced with the issue that the equipment came from the factory with the control system powered directly from the line, but after various proposals and conversations with the experts at Rockwell Automation, we were able to find a control system backup solution without losing the guarantee on our equipment,” Yagnam said.
Yagnam states that Rockwell Automation is consistently committed to supporting existing installed equipment and contributing to solutions for new issues that arise over time. “As for response times, we have already experienced them and I can say that they are within the appropriate range," he said.
Yagnam qualifies Rockwell Automation's work as total management with consistent support and service before, during and after the project. “We are planning to work with them on a smaller scale project, which is also related to the installation of low voltage frequency drives for energy savings in airflow control. We hope to have it successfully completed by the end of the year," he said.
