Energy Analysis Monitoring Systems - Foiling Excessive Energy Consumption  
Introduction

Unless you have been in a cave over the last few months, energy consumption and costs have taken over the nation's conscience. Our shrinking industrial base must be wise consumers of our resources such as gas and electricity to remain competitive. Within the metals industries, in particular Aluminum manufacturing, large amounts of gas and electricity are required to generate end product. To generate 1lb of aluminum from alumina, requires about 6.2 kWH (kilowatt hours) of electricity. Once the raw material has been created, aluminum is casted into furnaces or smelters, requiring about 1100 BTU's per lb to liquefy.To examine further, 1 SCF (Standard Cubic Foot) of natural gas can generate a range of 800 – 1100 BTU's. It takes roughly 2100 Btu/lb to melt aluminum to allow for casting. Given a large ingot of 30,000 lbs, the number of BTU's needed will equate to very large natural gas bills.

In order to ensure Natural Gas usage remains constant in relation to the manufactured lbs, Deadline Solutions, Inc. has come up with a solution to provide reporting and trending of natural gas usage within the Aluminum industry. In order to accomplish these goals, two key variables need to be harvested, gas usage in SCF and lbs produced over time. The consumption and processing of these variables would become the Energy Analysis + Monitoring System (EAMS).

Who is using the gas?

Within most aluminum facilities, there are a number of existing natural gas meters in place to help trend the gas usage. One of the first obstacles to overcome is the wide disparity of control systems within the factory floor that contains the flow data in units of SCFH. Some aluminum manufacturing facilities will have a casting group, cold rolling and hot rolling facilities which may contain different manufacturers of control systems from GE to Siemens. To solve this problem, Deadline Solutions selected Kepware Technologies to provide a landing zone of all natural gas readings into one process. Kepware manufactures OPC (OPen Connectivity) software that can speak the various PLC (Programmable Logic Controllers) found within the site. Deadline Solutions was required to solve this problem by connecting to Allen-Bradley, various Modbus devices, Yokogawa and GE 9070 PLC's. Right out of the box Kepware has a solution for each of these devices providing a single source concentrator of OPC data. With all of our OPC data contained in one location, trending and management of these variant natural gas flow meters becomes routine.

In order to obtain a higher degree of accuracy, secondary natural gas flow meters where installed to fill the gaps of existing meters. Use of wireless technologies was employed to save on material and labor costs. The secondary network consisted of wireless RF modems providing coverage over the entire site. Essentially the wireless flow meter configuration could be placed anywhere required with the facility with no concern of location of dependant resources such as wired LAN connectivity. Base stations where designed at key locations that would accept the wireless data and ground it to the automation LAN. Once the data was available on the LAN, the Kepware Modbus driver was used to collect and store the flow data to EAMS.

Having flow data is trended over time; the consumption of gas is computed to the hour or day as the base unit. Gaps in data would cause under-reporting of gas consumption with EAMS. The reliability and stability Kepware OPC Servers to collect the flow data is fundamental for the EAMS system to be successful.

What did we do?

As with our flow meters, production data presents a similar challenge with different MES/Level 3 systems used within the facility. The production data was harmonized into a common format so it could be understood by computation logic within each plant area. Putting software engineering best practices to use, Deadline Solutions built a web services layer in front of each of the manufacturing units. Web services provided endpoints which could transgress routed and firewalled environments. Each area contained a web server that published there lbs data. Using web services (WS-*) provide the contractual data format and security standard to harmonize the information into a central store. Much like our natural gas usage, the production data is now stored in a consistent uniform manor across disparate systems.

Did we conserve our resources?

By marrying two technologies, Web Services and Kepware OPC data, the EAMS system now has the data inputs required. Reporting and reviewing of natural gas consumption over production is a much easier task. Answers to questions such as how much gas was used? How many BTU's per lb where used? Is the furnace or process more efficient this week from last week? Being able to answering these questions provides feedback to maintenance and process folks to tune their devices and processes. Being able to tune your world enables manufacturers to be conservationists of energy rather than simply users.