Portable Pipelines for First Responders. Chris Christopoulos, Jr.

Transcription

1 Portable Pipelines for First Responders

2 Introduction Recently the Northeastern United States has begun to see an increase in the demands and use of Natural Gas in lieu of other fossil fuels, e.g. propane and fuel oil. The conversion to natural gas by some industry estimates can save high volume users upwards of percent in their fuel costs and reduce Carbon Dioxide emissions 1. So how is this happening in areas without access to Natural Gas via pipeline? The answer is Virtual Pipelines or Portable Pipelines. 2 Portable Pipelines are designed to provide natural gas to areas not served by a traditional pipeline. They are comprised of a modular system with four primary components: compressed or liquefied natural gas supply, transportation, storage, and decompression or re-gasification. As the use of natural gas becomes more common in areas not serviced by a traditional pipeline, first responders need to be aware of the safety features, installation, and testing requirements of the fixed site systems and equally important, be able to identify the different types of transport vehicles being used to transport, store, and offload Compressed Natural Gas (CNG) and Liquefied Natural Gas (LNG). Purpose The purpose of this white paper is to educate first responders and highlight the components of a portable pipeline: supply, transport, storage and end use, and to identify the different types and safety features of containers being used to transport CNG and LNG. Furthermore, the paper will indentify some of the potential problems first responders may face when responding to on site and transportation emergencies. Lastly, this paper will list several important considerations for response to transportation incidents. Fixed site facilities will differ Virtual Pipeline is trademarked by Xpress Natural Gas, Boston, MA, 2 P a g e C h r i s C h r i s t o p o u l o s, J r.

3 in their scope and configuration. Therefore, first responders should become familiar fixed site facilities in their community. Components of a Portable Pipeline Supply Liquefied Natural Gas (LNG) Liquefied Natural Gas is natural gas that has been cooled to temperatures at -260 F until it becomes a liquid. This process reduces its volume by approximately 600 times and allows for the transport of larger quantities in a smaller container. 3 The primary sources for LNG in New England are import facilities located in Cape Ann and Everett Massachusetts (Figure 1). Figure 1 - LNG Terminal, Everett, MA 4 Compressed Natural Gas (CNG) The supply component receives natural gas from an existing pipeline which is loaded to specialized trailers after being compressed via a compressor station. The natural gas is compressed to a higher pressure, upwards of 3600 psi, which in turn allows for a greater storage density (Figure 2). Figure 2 - XNG Compressor Station - Baileyville, Maine 3 Center for Liquefied Natural Gas, P a g e C h r i s C h r i s t o p o u l o s, J r.

4 Currently there are four operational compressor stations and two under construction serving New England. NG Advantage of Vermont operates one in Milton, VT and is currently building another in Pembroke, NH (expected opening April/May 2014). Xpress Natural Gas of Maine operates a station in Baileyville, ME and is building one in Eliot, ME (expected opening May/June 2014). Irving Oil supplies CNG to Eastern Maine from its compressor station in Lincoln, New Brunswick, and Global Partners operates a facility in Bangor, ME (Figure 3). Transportation and Storage Figure 3 New England Compressor Stations Liquefied Natural Gas LNG is transported in Cryogenic Cargo Tank Trucks (MC-338) from the supply point to end use. In a portable pipeline LNG is off-loaded from one tanker to another which is permanently 4 P a g e C h r i s C h r i s t o p o u l o s, J r.

5 stored onsite (Figure 4). For detailed information on Cryogenic Cargo Tank Trucks visit Figure 4 - Cryogenic Cargo Tank used as fixed site storage Compressed Natural Gas (CNG) CNG in the northeast is transported in the following types of high pressure tube trailers: Type I Cylinder Trailer Type III Cylinder Trailer Type IV Cylinder Trailer/Module Type I Cylinder Trailer These are the standard bulk high pressure highway container with a normal operating pressure between 2000 and 5000 psi and have a gas capacity between 100,000 and 144,000 standard cubic feet. When used for CNG, the normal operating pressure is 3600 psi at 59 F (Figure 5). 5 P a g e Figure 5 Type I Cylinder Trailer 4 C h r i s C h r i s t o p o u l o s, J r.

6 The trailer configurations can contain up to 36 high pressure steel cylinders which are interconnected by a rear manifold (Figure 6). Figure 6 Rear Manifold Each cylinder has both a front and rear pressure relief device (PRD). PRD s will activate by either heat, pressure or both (Figure 7). When activated, the PRD will release the entire contents of the affected cylinder(s). Figure 7 Front and Rear PRD s 6 P a g e C h r i s C h r i s t o p o u l o s, J r.

7 Type III Cylinder Trailer OSCOMP, one of the companies serving end users in New England operates a custom Type III Cylinder trailer. Type III cylinders are constructed of an aluminum liner and completely wound with carbon fiber. The trailers contain pods of cylinders, each containing thirty (30) cylinders and trailers are configured to hold 5 pods or 150 cylinders (Figures 8 and 9). Figure 8 OSCOMP Type III Trailer Figure 9 rear view with open doors The cylinders are fourteen inches in diameter and nine feet long and are interconnected to a manifold. Cylinders have a normal operating pressure of 3600 psi at 59 F and are equipped with a PRD on each end which will activate at 212 F. When activated, the PRD s vent the product of the affected cylinder into the frame of the pod and out through the top of the container (Figure 10). Figure 10 PRD 7 P a g e C h r i s C h r i s t o p o u l o s, J r.

8 Type IV Cylinder Trailer/Module The Type IV cylinders are constructed of a high-density polyethylene wrapped in filament wound epoxy-carbon fiber outer shell. In the Northeastern United States, both Xpress Natural Gas of Maine and NG Advantage of Vermont utilize a specially designed TITAN Type IV pressure vessel manufactured by Hexagon Lincoln in Lincoln, Nebraska. The cylinders in the TITAN module are forty-two and one half inches in diameter by thirty-eight and one half feet long with an operating pressure of 59 F and a liquid capacity of 2,219 gallons and a CNG capacity of 88,860 standard cubic feet (SCF) per cylinder (Figure 11). Figure 11 TITAN Cylinder The TITAN modules are comprised of four (4) composite tanks and a total capacity of 355, 440 standard cubic feet per module, which are mounted into a steel frame and then mounted on a flat bed. The top and all sides are enclosed to keep the module free of dirt, snow, etc. and resemble a standard box trailer 5 (Figure 12). Figure 12 TITAN with Box Truck Sides P a g e C h r i s C h r i s t o p o u l o s, J r.

9 According to Lincoln representatives, there are currently fifty-four (55) of these units in operation in the Northeastern United States (Massachusetts, Vermont, Maine and New Hampshire), South Carolina, and 262 world-wide as of December The TITAN units are manufactured and used in the United States under a Department of Transportation Special Permit. Figure 13 shows the TITAN without the outer sides of the box truck. Figure 13 Hexagon Lincoln TITAN The TITAN modules are equipment with a fire protection system which activates when a wire activates by expanding at 226 F. The system then vents all cylinders simultaneously via ¾ high pressure tubing to vents at the top of the box truck (Figure 14). The system can also be manually activated via a push button inside the doors on the rear of the box truck. The system will vent the contents of the tanks within 45 minutes. The tanks will degrade under fire conditions and if the fire protection system fails to vent the product, the tank can potentially suffer a catastrophic failure. Figure 14 TITAN Valve and Safety System Controls 9 P a g e C h r i s C h r i s t o p o u l o s, J r.

10 Each cylinder is equipped with a burst disk which is designed to fail at 4750 psi (Figure 15) and the system has a pressure relief valve (Figure 16) which will activate at 4500 psi. Burst disks were primarily designed to work on steel tanks to relief pressure that might build up during fire impingement on a cylinder. According to the manufacturer, in a fire scenario, the fire protection system would activate and vent all cylinders prior to pressures reaching 4750 psi or the composite cylinder would likely degrade and fail prior to a burst disk activating. The pressure relief valve is only functional when the entire module piping system is under pressure during loading and offloading operations. Figure 15 TITAN Burst Disk Figure 16 TITAN Relief Valve 10 P a g e C h r i s C h r i s t o p o u l o s, J r.

11 Portable Pipelines utilize a just in time management system to manage onsite demands. Trailers remain onsite and are rotated out when the pressure drops to a predetermined pressure. Trailer rotations depend on the end user demands, but can be as often and six to eight trailers per day during peak times (Figure 17). Figure 17 - CNG Onsite Storage Decompression or Re-Gasification With LNG, the system requires the use of vaporizers to convert the liquefied product to a gas. There are two basic types of vaporizers: Heated and Ambient Temperature. The system located in Lebanon, NH and pictured below utilizes an ambient temperature vaporizer (Figure 18). The LNG leaves the cargo tank at approximately 50 psi and is ultimately dropped to approximately 15 psi on the distribution side of the system. Figure 18 Ambient Air Vaporizers 11 P a g e C h r i s C h r i s t o p o u l o s, J r.

12 With the CNG Portable Pipeline, as the material is off-loaded from the pressure vessels, temperatures drop and the product must be heated prior to end use. As the compressed natural gas is offloaded it is sent to a heating unit to which heats the gas. Figure 19 shows a natural gas fired heater. Other companies use a high temperature glycol system to re-heat the CNG (Figure 20). The gas then moves through one or more stepdown pressure regulators to drop the pressure in most applications to 50 psi before entering the facility for the end user. Figure 19 Natural Gas Fired Heaters Figure 20 High Temperature Glycol Heather 12 P a g e C h r i s C h r i s t o p o u l o s, J r.

13 Why do Virtual Pipeline present a challenge for First Responders? LNG has a liquid to gas ratio of approximately 600:1, thus a release of an onsite storage cargo tank can create a large vapor cloud. The following illustrates the affected area with a release during the summertime (Figure 21). LNG, due to the cryogenic temperature cannot be odorized while in transit. Methyl mercaptan is injected after the LNG is vaporized during on site usage (Figure 22). During the initial installation of this system in Lebanon, a small quantity of methyl mercaptan was released during the filling process of the reservoir tank. This created over thirty 911 calls reporting an odor of propane in the entire downtown area. Figure 21 - Release Impact Area - summer 13 P a g e C h r i s C h r i s t o p o u l o s, J r.

14 Figure 22 - Methyl Mercaptan Storage Tank CNG facilities utilize compressed natural gas at high pressures (upwards of 3,600psi) from the onsite storage through several step-down pressure reducing devices to an end use pressure of approximately 50psi. Onsite storage component is made possible by utilizing specially designed high pressure tube trailers, upwards of 3-5 trailers per site depending on demands. Trailers are rotated in and out of the end use system based on the demands of the customer. In the Lebanon, NH installations the supplier estimates upwards of 5-8 deliveries per day during peak usage months. Local fire departments should become familiar with the onsite facilities during construction and develop pre-incident response plans accordingly. While many First Responders might not have a facility within their community utilizing CNG, as more and more facilities are brought online, there is a likelihood of having these high pressure tube trailers traveling through their community. Unlike LNG facility installations which can be referenced to National Fire Protection Association 59A, Standard for the Production, Storage, and Handling of Liquefied Natural Gas, the technology for CNG is so new that there are no specific guidelines for system installation or 14 P a g e C h r i s C h r i s t o p o u l o s, J r.

15 use. Based on the State of New Hampshire Fire Code, the State Fire Marshal has issued a ruling requiring a Performance Based Design for system installations 6 (See appendix A). The Type III trailers are designed so that only the affected individual cylinders will vent should a Pressure Relief Device (PRD) activate. It is important for responders to be familiar with the location of the PRD s and that the vent piping is tied directly into the Pod frame and will ultimately vent out the top of the Pod (Figure 23). Figure 23 Type III Trailer Frame Vents The TITAN modules are transported in an enclosed box trailer and placarded as a compressed flammable gas (UN 1971). Each module contains four (4) 38.5 feet long by 42.6 inch in diameter composite cylinders. The cylinders are constructed of a filament wound epoxycarbon fiber outer shell and a high density polyethylene liner. First responders unfamiliar with this configuration could be led to believe this is a normal box truck. Using key words, such as the company name as stenciled on the box can be used as a clue for identification (Figures 25 & 26). However, it is important to note that some of the modules currently in use have no identifying company information (Figure 27). 6 State of New Hampshire, Fire Marshal s Office Informational Bulletin: Virtual Pipeline Compressed Natural Gas Facilities, 2013, 15 P a g e C h r i s C h r i s t o p o u l o s, J r.

16 Figure 25 XNG TITAN Trailer Figure 26 NG Advantage TITAN Trailer Valve Figure 27 TITAN Trailer 16 P a g e C h r i s C h r i s t o p o u l o s, J r.

17 First responders need to know how the system operates and that even if the tank is venting it could be supplying fuel to the fire. Extinguishing a fire under these circumstances would not be the best option as the flow of material cannot be stopped if the trailer is venting (Figure 28). A full trailer will vent for minutes. First responders should also be aware that venting gas decompresses rapidly and can reach extremely cold temperatures at the vent opening and at the point of release is at a very high concentration of methane and difficult to ignite due to the air / fuel ratio. Also, high pressure releases can cause a static electricity build-up which could be a potential ignition source. Vent Lines Figure 28 TITAN Emergency Vents 17 P a g e C h r i s C h r i s t o p o u l o s, J r.

18 Rollover Protection the TITAN Modules are mounted inside of a steel intermodal container. The intermodal frames are subjected to a vertical load test from a crane. The only documented rollover of a TITAN Module occurred in Colombia, South America. The trailer rolled while going around a corner. Bolts holding several tank broke and one tank rotated 90, but the tanks stayed within the frame and no gas was released (Figure 29). Figure 29 TITAN Rollover Columbia, South America Currently the TITAN modules are not equipped with a remote shutoff or thermal automatic shutoff valve to stop the flow from the trailer should a high pressure offloading hose fail. The only way to stop the flow of gas from the trailer in this scenario would be to approach the trailer and manually activate the main line valve (Figure 30). As of this writing the manufacturer is working to engineer a solution that would (1) allow for manual activation but not at the rear of the trailer and (2) provide an automatic thermal shut off valve that will activate in the case of fire. Figure 30 TITAN Rear View 18 P a g e C h r i s C h r i s t o p o u l o s, J r.

19 First Responders need to be aware of this newer technology, especially as the demands for CNG increase in areas not serviced by traditional pipelines. The Type III trailer pods will vent only affected cylinders and through the frame rail of the pod; whereas, the TITAN cylinder trailers appear as a standard bob trailer with a methane placard and will vent via vent ports at the top rear of the trailer. Not understanding how these vessels vent or the fire protection features can lead to a catastrophic failure and injure, or worse kill first responders. Response Considerations 1. Identification - First Responders must be able to recognize that the TITAN box trucks have some features that can help to identify the contents. All vehicles are required to be placarded as compressed natural gas (UN 1971). Additional features include vent louvers located at the sides of the trailer at the top of the box, visible cylinders, or the name of the company which can be used as a visual clue to help distinguish trailers. Lastly, in the event of a roll over, first responders can view the emergency vent exhaust ports at the top of both the Type III and Type IV TITAN module. 2. Gas Release with Fire the TITAN composite tank will normally degrade in a fire condition. However, in the event of fire under the module and non-activation of the fire protection system to vent the gas, there is a chance of catastrophic failure of the cylinder. With both the Type III and TITAN module small fires can be extinguished if the flow of gas can be controlled by using dry chemical or carbon dioxide fire extinguishers. Fire department personnel should consider the use of a thermal imaging camera before approaching containers. 3. Gas Release No Fire responders should be aware of the potential impact area by the release of gas at high pressure. Methane is lighter than air. Venting containers are easily recognized by high pitched venting noises. Rapid decompression of CNG can create extremely cold temperatures. First responders should use caution when utilizing fog streams to control gas as this may increase the rate of release due to the warmer water temperature vs. the cooler gas or potentially freeze safety venting systems. This cooling will also produce a visible vapor cloud. Responders may smell the odor of mercaptan at 19 P a g e C h r i s C h r i s t o p o u l o s, J r.

20 or near the ground and this added odorant begins to separate from the lighter than air natural gas. 4. Isolation and Evacuation - First responders should be aware of potential evacuation areas in the event of venting. Initial isolation and evacuation distances should be determine by using ERG Guide 115. According to Guide 115, the initial isolation area should be at least 330 feet in all directions; evacuation for a leak without fire should be at least ½ miles downwind; and for a leak with fire at least 1 mile in all directions. The author would like to thank the following companies for providing information, pictures, and technical support for the development of this document. 1. Callan and Company, Middlefield, CT, 2. OSCOMP Systems, Houston, Texas, 3. Global Partners, Waltham, Massachusetts, 4. Hexagon-Lincoln, Inc., Lincoln, Nebraska, 5. Xpress Natural Gas, Boston, Massachusetts, 6. NG Advantage, Milton, Vermont, 20 P a g e C h r i s C h r i s t o p o u l o s, J r.