Advanced Specialty Gases - Executive Summary |
|
ABOUT ADVANCED SPECIALTY GASES, INC. ASG was established May 1991, marketing atmospheric rare gases (xenon, krypton, and neon). By establishing a joint venture production facility in Russia to process rare gases, ASG became a major supplier of these gases worldwide to the lighting aerospace industry. The company has since successfully expanded its product offering to include specialty fluorinated and high purity hydrocarbon gases and has added value by transfixing and mixing these gases. In that regard, the company has become one of the largest distributors of sulfur hexafluoride (SF6) in the Western United States. ASG continues to pursue its original objective of identifying and capitalizing upon industrial gas market inefficiencies. In pursuit of this objective, ASG began developing a manufacturing facility to produce Nitrogen Trifluoride (NF3) in Dayton, Nevada and recently entered into joint venture to produce SF6 in South Africa for worldwide distribution. A summary of ASG s operations is as follows: San Francisco, California (1991) - Current headquarters and marketing offices. Moscow, Russia (1992) - Joint venture: Akela. A joint venture with AGA-Sweden and three Russian steel mills to separate and purify rare gases (xenon, krypton, neon). Dayton, Nevada (1995) - Nitrogen Trifluoride (NF3 ) production; SF6 transfilling, rare gas transfilling and mixtures. Houston, Texas (1996) - Joint Venture: Specialty Chemical Products (SCP). Production of specialty hydrocarbon mixes for high purity and calibration applications. SCP will also repackage SF6 for distribution in the Southern United States. Pelindaba, South Africa (1996) - Joint venture with Atomic Energy Corporation (AEC). Production of fluorine and sulfur hexafluoride SF6 . NF3 Manufacturing Facility Site Information The facility is located on approximately 5 acres off of Highway 50 in the Dayton Industrial Park, 28 Enterprise Way, Mark Twain area, about 3.5 miles east of downtown Dayton. Th e built-on ground is about 2 acres out of which 1-1/2 acres are fenced in, leaving the rest as an employee parking lot. The fenced in area holds a 5,800 sqft production building with a 2,100 sqft awning as well as bulk chemical storage tanks for hydrogen fluoride, ammonia and nitrogen trifluoride. This area is served by three gates, two in the front leading to Enterprise Way, and one in the back. NF3 Manufacturing Process ASG employs a process which is known as in-situ electrolyte manufacturing process. The raw materials, hydrogen fluoride and ammonia, are introduced into the reactor (electrolytic cell) which is already filled with potassium bifluoride as the acting electrolyte. Electric power (DC) is fed to the reactor and nitrogen trifluoride is produced in the anodes chamber. The material is then purified and filled into bulk storage tubes. Hydrogen which is produced at the cathodes as a byproduct is also purified and then released to the atmosphere. Bulk Chemical Storage 1) Nitrogen Trifluoride Background Nitrogen Trifluoride (NF3) is nonflammable and is usually shipped as a compressed gas. It is inert and thermodynamically stable at ambient temperatures. At high temperatures, its reactivity will become similar to elemental fluorine. NF3 dissociates into NF2 and fluorine radicals. Hence, it is a strong oxidizer and ideal for certain cleaning applications. Upon inhalation of NF3 , physiological effects similar to those of carbon monoxide must be expected. NF3 has had many uses in the past, the most notable being as an oxidizer in rocket fuel. Though this use has been discontinued, other current applications include: 7 As a fluorine source for high-energy lasers, preferable to pure fluorine because of its comparative ease of handling at ambient temperatures. 7 As a chemical intermediate in the production of tetrafluorohydrazine and perfluoroammonium salts. 7 Cleaning in-situ CVD reactor tubes and fixtures used in semiconductor etching. Plas ma or in-situ cleaning with NF3 creates minimal waste and of that, little is toxic or hazardous. This application primary focus of ASGs NF3 marketing efforts. 7 As a dry etchant in the semiconductor industry, showing significantly higher etch rates and selectives when compared to carbon tetrafluoride (CF4) and mixtures of CF4 and oxygen. ASG utilizes three storage tubes with an average of 100 cuft internal volume. The maximum amount of nitrogen trifluoride per tube will not exceed 1,000 lbs of material. 2) Hydrogen Fluoride Background Hydrogen fluoride is a colorless fuming liquid or gas with a strong irritating odor. Hydrogen fluoride is a corrosive chemical and an inhalation hazard. Hydrogen fluoride is shipped under its own vapor pressure. Hydrogen fluoride is a strong acid and hence, it is used in many applications. The most common applications are: 7 As a raw material for CFC-alternatives. 7 For the pickling process in the metal industry. 7 As a glass etching agent . 7 For the alkylation process in refineries. ASG utilizes a 6,000 gallon storage tank and a 200 gallon intermediate storage tank. The maximum amount of hydrogen fluoride will not exceed 4,500 gallons. 3) Ammonia background Ammonia is a colorless, pungent gas, irritating to the mucous membranes and has a limited flammable range. Ammonia is shipped as a liquefied gas under its on vapor pressure. The principle uses of ammonia are in the fields of: 7 Agriculture (about 87%), especially to produce fertilizer. 7 Refrigeration 7 Metallurgical, such as nitriding, bright annealing, etc. 7 Technical, especially for the production of explosives. ASG utilizes a 3,000 gallon storage tank. The maximum amount of ammonia will not exceed 2,700 gallons. Building The 5,800 sqft building is divided into production/quality control, storage and office areas. The 2,100 sqft awning houses utilities pertinent to the process other than liquid nitrogen. Personnel The plant will be operating 24 hours a day, 7 days a week. It will be operated by a minimum production staff of two. Each shift will have an Operations Manager and a Chemical Technician on duty. In addition, during normal office hours, quality assurance, maintenance and office personnel will be on site. HIGHLIGHT OF SAFETY FEATURES & EQUIPMENT Plant Safety Systems 7 Totally independent, 5,000 gallon back-up supply and water pump (gas powered with battery powered starter). 7 All critical areas are fenced with three locked gates. 7 Three on-site water hydrants. 7 32,000 gallon passive containment area surrounding HF storage area. 7 2,000 gallons per minute water deluge system for the HF storage area. 7 Emergency hook-up for external water supply to water deluge system. 7 Five emergency shutdown switches throughout the facility. 7 Constant video surveillance over HF and ammonia storage areas. 7 On-site weather station. 7 100% X-ray of all critical piping systems. 7 Full ultrasonic testing of all storage vessels and critical piping. 7 Dedicated radio for communications to local fire department (CLCFD). 7 Safety showers and eyewash stations throughout the plant. 7 Gas sensors throughout the plant and redundant sensors around the HF storage area. 7 Plant is manned 24 hours per day while hazardous chemicals are on site. 7 Low pressures (#15 psig) maintained in all process piping systems. 7 Automatic initiation of plant shutdown at preset levels during operation. On-Site Emergency Response Team and Equipment 7 9 Hand-held fire extinguishers located throughout the plant. 7 2 Fire hoses (50 and 150). 7 4 Self-contained breathing units for emergency response teams. 7 8 Backup air bottles for breathing units. 7 4 Level A emergency response suits. 7 1 Oxygen respirator. 7 4 Portable gas sensors for all on-site gases. 7 1 Scorpion fire monitor. Emergency Equipment Supplied to CLCFD 7 Self-contained breathing units for emergency response teams. 7 Level A emergency response suits. 7 Level B emergenc y response suits. SAFETY SYSTEM DESCRIPTION HF Mitigation System The facility is prepared to deal with the unlikely event of an HF storage tank rupture. A concrete containment area holding approximately 32,000 gallons of liquid is surrounding both hydrogen fluoride bulk tanks. Also installed is a water deluge system covering the entire containment area. The system is designed to dump approximately 2,000 gpm of water onto the complete containment area, thus reducing the threat of HF vapors in the atmosphere. Twenty-five Bete nozzles, model number N7, are installed at a height of 20 feet above the containment area with additional nozzles covering the flange area on top of the storage tanks and the truck unloading area. The water flow is activated by the DCS when both sensors inside the containment area are in the alarm state (HF concentration >10 ppm). Activation of the system can be observed on the CC TV monitor inside the control room, where a green light at the DCS panel also indicates that the water is flowing. If the automatic activation of the system should fail and the situation calls for more flow, a manual override button at the DCS panel will also allow the activation of the deluge system. Once the deluge system is activated, a timer set for 13 minutes will ensure that the water flow stops, preventing the containment area from overflowing. The water flow can also be stopped by use of the manual override button. The system is fitted with a fire department connection (FDC) for outside emergency water supply. Secondary HF Mitigation System This system is a back-up for the primary mitigation system in case it cannot be activated for any reason whatsoever. The back-up water system is designed to be completely independent from any energy or water source. It consists of a 5,000 gallon water tank, a water pump and a fire water monitor aiming at the bulk storage tanks. The system is capable of dumping the water tanks content into the containment ar ea within 10 minutes. The gasoline powered engine of the pump will be activated with a button, located at the DCS panel. An indicator light right next to it will illuminate as soon as water flow occurs. Also placed at the panel is a voltage indicator for the engine battery which is connected to an automatic battery charger ensuring the readiness of the secondary HF mitigation system. Containment Systems The hydrogen fluoride and the ammonia bulk tanks are both placed with a secondary containment in the event of a major release. The HF containment area will hold up to 32,000 gallons of liquid. The NH3 containment area will hold up to 4,500 gallons of liquid. Alarm System The alarm system consists of 1 field horn located in control room. All alarms are listed and handled on the alarm screens enunciated by the field horn. The highest priority (7) has two cases; the first case is that any of the five ESD buttons will shut down the process and enunciate the control room horn. T he second case is that any of the gas detectors will turn on its local alarm and enunciate the control room horn. When the alarm is acknowledged, the control room horn will silence. The second highest priority (5) alarms indicate that a high high or low low process alarm has occurred, shutting down the process. The low priority (3) alarms indicate that a high or low alarm has sounded. This allows the Operations Manager to take quick action to eliminate problems and avert a shutdown. The lowest priority (1) alarms are just warnings to the Operations Manager for re-order points, maintenance and process status. Safety Showers There are 6 safety showers located throughout the facility. They all contain an eyewash station and are easily accessed. The safety showers are tested monthly for proper operation and the eyewash stations are covered with pop-off lids to keep them clean. The systems come with a 10 diameter deluge shower head and twin eyewash sprays. The body is manufactu red out of galvanized steel pipe, while the shower head and eyewash heads are manufactured out of plastic. Scrubbing and Ventilation System The Bact/Hellmich dry scrubber is a high efficiency scrubber, providing excellent mass transfer characteristics between gases and crushed limestone. The dry scrubber is of a single shell construction featuring distinct areas for the storage of limestone and its contact with gases. Gas enters the scrubber on one side and an internal baffle arrangement forces the gas to travel through the bed of cascading limestone. Spent limestone is discharged via an extraction screw in the bottom of the scrubbers hopper to a disposal system. The scrubber panel and the fan must be started manually. The conveyor screw will be activated by a timer for 6 seconds every two hours and its daily operation will be verified with the DCS by means of a totalizer. The scrubber fan, rated at 7,065 cfm, is designed for 6 air changes per hour and plant exhaust air is pul led out of three areas: 7 Cell room - 6,000 cfm 7 Purification room - 950 cfm 7 Cylinder fill room - 100 cfm Fire Sprinkler System A fire sprinkler system is installed and covers all areas of the building and it will active in the unlikely event of a fire. The sprinkler heads put out 2,250 gpm of water at 60 psi. Back-up Generator The facility contains a 25kW back-up generator that will activate in the event of a power outage. The following systems are connected to the generator. 7 Interior hi-bay lights 7 Exterior flood lights 7 Scrubber 7 DCS and UPS 7 3 electrical outlets in control room 7 Phone panel 7 CC TV camera for HF tank Fire Hoses The facility has three 100 foot long, 1-3/4 double jacketed, fire hoses to hook up to three fire hydrants located on the property, should the need arise. The facility also has one 50 foot long, 3 double jacketed, fire hose available. Fire Extinguishers Fire extinguishers are located throughout the facility for easy access in the unli kely event of a small fire. The fire extinguishers are rated for A, B and C fires. There are 11 total fire extinguishers located in the following areas. 7 1 - Shipping and receiving 7 1 - Front office 7 2 - Empty cylinder storage room 7 1 - Rectifier room 7 3 - Cell room 7 2 - Assembly dock 7 1 - Lab Weather Station The facility has a weather station designed to provide information on wind velocity and direction, in the event of a leak. |