Ross Products Division, Abbott Laboratories - Executive Summary
EXECUTIVE SUMMARY |
Abbott Laboratories, Ross Products Division located in Altavista, Virginia has an accidental release prevention program that combines the newest equipment technologies with operational procedures, training, and management practices. All applicable procedures of the U. S. Environmental Protection Agency (EPA ) Prevention Program are adhered to. The in-plant emergency response procedures have been developed at this facility consistent with the emergency response services available in the community. Implementation and maintenance of the the sytems and programs discussed in this report have the full support of Abbott management.
The Altavista facility has a single, closed-looped ammonia system. This system is used to cool water to 33 to 40 degrees F. The frigid water is circulated throughtout the plant to cool various processes and storage tanks used in the manufacture of nutritional products. At no time does the ammonia come in contact with the water. All of t
he ammonia handling equipment is located in the site's Powerhouse.
The system is comprised of three ammonia compressors, three chill plates (heat exchangers), two condensers, one high pressure receiver, two ice banks, control systems, relief valves, safety equipment (such as ammonia monitors) and associated piping. The small compressor is 255 tons of cooling and the two larger are 1000 tons each. Operation of the system is monitored and controlled 24 hrs per day, 365 days per year from the Powerhouse Control Room.
Liquid ammonia goes from the high pressure receiver through the chill plates and ice bank coils while water is circulated over the outside of the chill plates and coils. The liquid ammonia absorbs energy from the water and is turned into low pressure gas. The water temperature is reduced from the loss of energy. This water is circulated throughtout the plant for cooling. Chill plates and compressors can be added or subtracted depending on the cooling load. The low pr
essure gas is then returned to the intercooler and then to the ammonia compressors that turn the ammonia vapor back into a high pressure gas. The high pressure gas then goes to the condensors that use fans and water circulating over the ammonia carrying pipes to remove the heat from the ammonia and return it to a liquid. The liquid then drains by gravity back to the high pressure receiver.
All ammonia equipment with the exception of the condesors is located in the Ammonia Equipment Rooms. This area is equipped with exhaust fans that are regularly tested. Testing is initiated by our Preventive Maintenance (PM) System to assure that the fans continue to work properly. Each ammonia room has an ammonia detector which is connected to the monitoring/alarm system. The lower detector is set at 35 ppm and the high alarm is set at 500 ppm. If a level of 35 ppm of ammonia is detected, an alarm sounds in the Powerhouse Control Room. If a level of 500 ppm is detected, an alarm sounds in
the Powerhouse Control Room and exhaust fans will switch to high speed.
Each piece of ammonia equipment is on the Preventive Maintenance Program. PMs are generated automatically at the designed frequency from a computer database. Contractors check pieces of ammonia equipment such as piping, exchangers, etc. for corrosion every five years. Safety relief valves allow the system to relieve over-pressurization in a controlled manner, avoiding a dangerous buildup of pressure. All safety relief valves are piped above the roof. All ammonia system safety relief valves are replaced every five years.
Ammonia system valves are numbered to correspond to site process and instrumentation drawings (P & IDs) for the ammonia system. Difficult to reach valves have been equipped with chain operation for ease of operation and faster response in the event of an ammonia emergency.
The worst-case release scenario at the Altavista site involves the failure and release of the entire ammonia system (
30,000 lbs). The offsite consequence analysis was performed using conditions pre-defined by the EPA, namely release of the entire amount in 10 minutes. Possible causes of the worst-case release or the probability are not considered. EPA-mandated conditions for atmospheric temperature, humidity and surface roughness have been modified as follows:
EPA Value Modeled Value
Atmospheric Temperature 77 deg F 96.89 deg F
Humidity 50 % 67.21 %
Surface Roughness 0.1 0.4
Only the population in an elliptical plume extending downwind of the release point is potentially affected.
The alternate release scenario that was modeled
involves the failure of an evaporative condensor causing the relief valve on the #3 compressor to open. Condensor loss could be due to failure of the cooling fans in the tower. To minimize the chance of such an incident, status of the condensor fans can be monitored from the computer control screen. The alternate release assumes a loss of 1200 pounds of ammonia during a 34 seconds interval. The SLAB model was used for the Alternate Release Scenario since the Degadis model would not indicate an "off site" consequence. Wind speed was increased on the alternate release to 2.29 m/s.
The site's general accidental release prevention program is based on the following key elements:
1. High level of training of the operators.
2. Preventive maintenance program.
3. Use of state-of-the-art- process and safety equipment.
4. Use of accurately developed operating procedures, written with the participation of the operators.
5. Performance o
f hazard reviews of equipment and procedures.
6. On-going auditing and inspection program.
Chemical-specific prevention steps include: availability of self-contained breathing apparatus (SCBA), to be worn by the operators or Emergency Response (ER) members if ever needed; awareness of the hazards and toxic properties of ammonia; limited or controlled access to the ammonia rooms; the presence of ammonia detectors; and a fully implemented Process Safety Management Program.
There have been no accidental releases at this facility in the past five years.
This facility has a trained emergency reponse (ER) Team that has been trained specifically in aiding the Powerhouse employees should there be an emergency or release. This facility participates with the Campbell County Department of Public Safety (LEPC). Emergency response procedures and operations are reviewed or checked annually.
There have been no system changes to the operation since implementation of the PSM Program an
d the Management of Change Procedures; however, as recently as the March, 1999's Process Hazards Analysis (PHA), there were changes proposed to improve safety for the facility. These recommendations are now being evaluated.