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DC Rectification

The production of chlorine, chlorate, aluminum, and magnesium all depend exclusively on the reliable conversion of high voltage AC electrical energy into DC. These devices, known as rectifiers, take one of several forms: mercury arc devices, diodes, thyristors, and choppers. Andritz Automation is widely renowned for the application of these types of devices to industrial applications.

Rectifiers and transformers are among the most reliable (and often ignored) pieces of equipment in an industrial plant. It is not uncommon to find units that have been in service for up to 50 years. It is this inherent reliability that presents challenges. All equipment design is a result of economic compromises. Units designed in the era when electric power was cheap frequently experience losses that are considered excessive in today's economic climate. Control systems that were the cutting edge of technology in 1960 may not be repairable since the parts may not be available. And perhaps the most serious challenge is finding anyone who knows "what is inside the box" when there is trouble since the original designer probably retired 20 years ago and the rectifier supplier has gone out of business.

The Solution

Servicing the needs of plants that use DC rectification was one of the founding businesses of Andritz Automation in the mid-1960's. Today, DC rectification remains a core business for our company. We have developed innovative solutions to problems in harmonic filtration, step-less output amperage control, DC bus design, and rectifier control systems. There are a number of papers that have been written on these subjects.

• Harmonics and Power Factor Correction
  • Even Harmonic Resonance (PDF)
• Reliability and Control Enhancements for Old Rectifiers
  • New Life for Old Power Rectifiers (PDF)
  • New Life for Old Thyristor Power Rectifiers using Contemporary Digital Control (PDF)
  • Re-Using and Re-Rating Older Rectifiers with New DC/DC Choppers (PDF)
• High Amperage Switches
• Retrofitting Used Equipment for Re-use
• New Rectifier installation
• DC bus design and optimization
• DC system metering
• Automated Demand Control System

Plant Management and Operation

While good engineering and solid technology is essential for the adequate design of a chemical process, it is up to the Plant Operations personnel to use these tools to accomplish the project's overall goals. These goals go beyond merely making the production quota and staying within the budget to include the human aspects of plant safety, incident investigation and prevention, environmental compliance, and more recently, protection from terrorism. Coming from an extensive background in plant management and operations, Andritz Automation's personnel not only understand, but have for many years fulfilled these responsibilities on a 12 hour 7 day a week basis.

We offer the following systems and services to assist the plant management meet the expectations of the facility owners, the employees, and the community in which the plant operates.

Specialized Operational Systems and Tools

• Integrated Contingency Plans: In today's complex operational environment there are multiple requirements for contingency plans including: OSHA's Right to Know, EPA's RCRA, USCG's OPA 90 rules, as well as the more well known OSHA Process Safety Management, and EPA's Risk Management Plan. All these rules and regulations have divergent goals and requirements. Developing a single response plan for the facility that meets all the requirements will simplify and clarify the response during an incident. Andritz Automation has developed such an approach.
• Automated Safety Recommendation Tracking Systems: The multiple sets of regulations that govern the operation of today's plants also result in a host of recommendations coming from audits, investigations, management of change issues, and process hazard analyses. Managing the competition for scare resources to address these recommendations is a daunting task. Andritz Automation has developed a database program that simplifies the management process and provides a convenient format for the required documentation.

Safety and Responsible Care

• OSHA Process Safety Management and EPA Risk Management Plan: Andritz Automation offers customers complete PSM services ranging from a single Process Hazard Analysis (PHA) to full scale program audits and consultations. If programs are be found deficient, Andritz Automation has provided cost effective solutions for small and large facilities. One specialized tool is our innovative Process Hazard Analysis Revalidation technique. OSHA requires that each PHA be revalidated each five years. We have developed a technique that is more cost effective than the usual approach of interrupting the schedule of 5-10 plant personnel for several days to accomplish the task.
• Security and Vulnerability: While the protection of the plant physical assets is fairly straight forward, protection of the process control system is not. The issue of Cyber Security is a natural outgrowth of our Process Control expertise. We have the ability to detect as well as correct any defects found that could allow malicious attack on the plant control system. The Chlorine Institute has recently warned that this is a serious risk that should not be ignored.

Operational Efficiency

In-depth knowledge of the Chlor-Alkali business allows us to act as consultants to take advantage of business opportunities or process improvements that may not have been fully implemented at an individual plant site. We have been given a grant by the Atlantic Canada Opportunities Agency to assist firms in their district evaluate opportunities for process improvement. In addition, we have conducted benchmarking studies for customers in Latin America and in Eastern Europe.