Grain facility automation can provide many possibilities. This article will suggest ways to make a smooth and profitable transition to elevator automation.
After considering how much money is at stake, this topic quickly becomes quite important. A rail loadout operation can weigh U.S.$150,000 worth of grain per hour, so time and accuracy counts. The ability to retrieve information about the operation is key to improving it.
Elevator automation could mean a drastic increase in efficiency. For companies that have platform scales, automation would allow the operator to immediately print out a complete ticket with all the necessary customer and order information on it instead of recording the weight and having a clerk type out the ticket and re-enter the weights — where errors typically occur.
First, there are a few terms one should know to fully understand automation.
MMI or HMI, man-machine interface — more recently known as human-machine interface — describes a graphical package that allows an operator to see an entire or partial facility overview at a glance. With a well-designed HMI, the operator is able to start and stop equipment, monitor alarms, run maintenance reports, see trends and link to process and customer data all from one computer.
NTEP is an often-used abbreviation for National Type Evaluation Program. NTEP is a program of cooperation between the U.S. National Conference of Weights and Measures (NCWM), the National Institute for Standards and Technology (NIST), U.S. state weights and measures officials and the private sector for determining conformance of weighing with the provisions of the NIST Handbook 44. Currently, more than 30 states require NTEP approval for scale equipment to be used in "legal for trade" applications.
PLC, programmable logic controller, is a device that performs input/output and control logic functions and can communicate with other devices in industrial automation applications.
RFID, radio frequency identification, is a device that automatically identifies a truck or rail car by passing a tag by a scanner. The tag and scanner communicate with each other at a radio frequency somewhere between 10 megahertz and 5 gigahertz; the scanner then works with a computer to process the information. RFID for truck and rail car transactions is commonly done using passive tags that operate without an onboard battery, enabling them to last indefinitely.
STEPS TO INTEGRATION. Automation is not generally done in one leap, but rather in a series of small steps due to costs and training. The first step in progressing from a manual system to a fully automated one is to obtain accurate weighing systems.
Legal-for-trade bulk weighing scales and truck/rail scales are NTEP-approved 0.1% accurate. As long as the scales are maintained and tested regularly they will continue weighing at this accuracy. The better the measurement going into the process, the better the end result.
Second, get the facility data (or paperwork flow) under control. The automation journey starts with understanding and managing the reams of data flowing around the facility. Good control over the scale and customer data is critical.
A good data handling system should be modular, so options like automatic grading, blending, inventory, reporting, automatic RF tag system and automation can be added at any time. If automation is added, the data handling system must be able to pass information transparently to the automation system, with little or no operator re-training required. Be sure the data handling system includes:
Solid computer hardware. Use industrial-grade computer hardware with an air-filtration system to keep out dust and a vibration-dampening hard drive mounting to ensure equipment reliability.
Reporting capability. It is important to be able to run reports without relying on another department.
Ease of use. For operator and supervisor sanity, "simple to use" is a basic requirement. Everything the operator needs should be obvious and accessible from one main screen, if possible.
An interface for current or future transferring of scale data to the grain accounting package to reduce data entry and errors.
Seamless interface to a facility's data handling software is critical. Re-entering of data can lead to costly mistakes. On average, a skilled data-entry operator makes one mistake per 300 keystrokes. Imagine the potential for error from a cold, tired operator hurrying to finish a unit train.
Ideally, customer, commodity, bin and other transaction data is entered only once — at the beginning of the transaction — and is passed along to the automation system, then to the grain accounting package without further data entry. A good data handling and reporting system can save hours of handwriting or spreadsheet work at the end of the day, week or month. Also, instant access to the data can improve an operation in "real time." For example, grade factors can be monitored during loadout to ensure that the target grade is met.
Once the data management is under control, it's time to move into the third step: facility automation. By incorporating equipment control, alarms, trending and other features, automation streamlines the flow of data and makes an operation more efficient, allowing personnel to focus on more important tasks. Automation constantly monitors a facility's operations, improving safety and possibly lowering workman's compensation rates.
TIPS AND TRAPS. When planning for scale automation, make sure the automated system is an improvement over the manual system and avoid buying more capability than you need. Unless a payback is obvious, it probably isn't necessary.
To help keep costs down, hire an experienced vendor. Many companies supply elevator automation, including consultants, scale vendors, millwrights, contractors, electricians, engineering companies and even some scale dealers. Remember, all automation is not created equal. Grain has its own set of rules and requirements — both user and government defined — so make sure the automation vendor has the specific experience needed for the job.
Ask the vendor if a new or redesigned automation system will:
• Allow supervisors and operators to show real-time (dollar) savings at the end of every day, week and month?
• Reduce labor costs?
• Reduce unload times and improve loadout speed?
• Reduce mixing grains?
• Keep operator training times to a minimum?
• Allow for optimizing upgrades?
The system should allow a facility to expand or add capability easily — a "pay as you grow" philosophy. Over time, a facility should be able to add work stations and plant equipment without making existing equipment obsolete.
Key to the system's success is the design, for it is only useful if real operators can use it. The system must be intuitive, not requiring any specialized knowledge on the part of the operator.
Alarm functions should include a clear indication of the problem device and allow the operator to easily evaluate the situation and diagnose the problem. Because the control system constantly monitors the status of all I/O points, a component that moves into an alarm condition should be immediately clear to the operator.
For example, the automation system should display an alarm on the screen —sound a horn or flash strobe lights —to alert the operator to prevent facility damage. Because equipment is interlocked, several devices may shut down or change state. An alarm log should record the alarm and the operator's reactions.
For analog-type sensors, several thresholds can be set up. The operator will be warned once a component's value starts to move outside its normal operating limits. If a potentially hazardous condition occurs, the automation system can immediately shut down the suspect component.
Because of remote diagnostic and support tools available, it is not necessary to have someone on site to maintain the PLC and HMI programming. Local support should be available if industry standard, open-type, non-proprietary equipment and software is used.
Finally, be prepared to answer certain questions from the vendors. Vendors need to know about current control systems, the amount and types of PLCs at the facility, which manual operations to automate and how many I/O points to tie-in.
They will want to know the amount and types of scales at the facility, where the most costly operations errors have occured in the past and whether the system should be designed to control multiple scales or the entire facility from one work station. Provide a sketch showing overall facility layout, including vessels, control rooms, scales and material flow.
Provide information about the facility's accounting package as well as any other companies involved in the automation process, including the engineering or design firm; the electrical contractor and scale dealer/service.
In the end, the vendor should know your operation as well as you do.
Jim Gavrish, senior project engineer for CompuWeigh Corp., Cheshire, Connecticut, U.S., presented this article at the Grain Elevator and Processing Society's 1999 annual conference.