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Munitions Processing Flowsheet for the Pueblo Chemical Agent

By Ann Thomas,2014-11-26 10:40
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Munitions Processing Flowsheet for the Pueblo Chemical Agent

    Munitions Processing Flowsheet for the Pueblo Chemical Agent

    Destruction Pilot Plant (PCAPP)

    Craig A. Myler, Chief Engineer, Process, Bechtel National, Inc.

    August Benz, Bechtel Fellow, Bechtel National, Inc.

    Scott Susman, Project Engineer, U.S. Department of Defense Assembled Chemical

    Weapons Alternatives (ACWA) Program

    Gary Anderson, U.S. Department of Defense ACWA Site Project Manager, PCAPP

    Abstract

The Pueblo Chemical Agent-Destruction Pilot Plant, or PCAPP, will be built to destroysafely

    and efficientlythe stockpile of chemical weapons stored at the U.S. Army Pueblo Chemical Depot since the 1950s. The PCAPP is designed to destroy more than 2,600 tons of mustard agent in over 780,000 munitions to eliminate the risk from continued storage.

The process involves five steps:

    1. Removal and treatment of the energetic items

    2. Removing the mustard agent

    3. Neutralizing the mustard agent

    4. Post treatment of neutralized mustard agent (hydrolysate)

    5. Treatment of the metal parts

    This paper will discuss the flowsheet and expectations for the above 5 steps. Full scale testing results will be presented for the Projectile Mortar Disassembly (PMD) machine, the Munitions Washout Station (MWS) and the Munitions Treatment Unit (MTU).

    recommend that the technology known as 1. Background.

    neutralization followed by biotreatment be

    used to destroy the chemical weapons. The U.S. Army Pueblo Chemical Depot,

     located near Pueblo, Colo., was originally

    Neutralization followed by biotreatment constructed as the Pueblo Ordnance Depot

    uses hot water to neutralize the chemical in 1942. Through many years and changing

    agent, effectively destroying the mustard missions, the depot is currently responsible

    agent molecules. The follow-on process, for safe and secure storage of 2600 tons of

    biotreatment, utilizes microbes to digest mustard agent in projectiles and mortars.

    and break down the neutralization byproduct, The weapons have been stored at the

    which is called hydrolysate. 23,000-acre depot since the 1950s. The

    In 2002, Bechtel was selected as the Department of Defense Assembled

    systems contractor to design, construct, Chemical Weapons Alternatives (ACWA)

    systemize, pilot test, operate and close the Program, the depot and the community

    Pueblo Chemical Agent-Destruction Pilot worked in partnership to

    Plant. The Bechtel Pueblo Team is made up treatment of the chemical agent, the PCAPP of Bechtel National, Inc., and its partners, process flowsheet was established. including Washington Demilitarization

    Company, Parsons, Battelle Memorial 2. Process Flowsheet.

    Institute, General Atomics and General 1Physics. The overall process flowsheet for the

    PCAPP is shown in Figure 2. The main

    process operations described in this paper

    are highlighted in Figure 3.

    2.1 Removing Energetics

    The munitions in the Pueblo Stockpile

    contain energetic materials including

    propellants and explosives. Only a portion

    of the 105 mm and all of the 4.2 inch

    mortars contain propelling energetics.

    These propellents will be safely removed

    manually, using procedures proven

    previously at other stockpile locations. The

    explosive components, which include fuses,

    boosters, and bursting charges will be removed using a robotic machine called the Linear Projectile Mortar Disassembly Figure 1: Chemical Weapons in machine (LPMD). Existing U.S. baseline Storage plants use a turntable-based PMD machine to move projectiles and mortars from station to station for reverse assembly and The Pueblo stockpile consists entirely of energetics removal. Using advanced robotic projectiles and mortars, all of which contain technology, the LPMD moves projectiles either distilled mustard (HD) or agent HT. and mortars between individual reverse The total number of munitions is over assembly stations in a linear array, allowing 780,000. for greater flexibility in both control and configuration. A significant improvement is It is apparent from the number of munitions the ability to easily replace individual to be destroyed at the PCAPP that the LPMD component assemblies, thereby processing flowsheet must consider plant reducing maintenance, changeover, and throughput as a critical design requirement. closure complexity. After removal, all As the agent make-up of the munition items uncontaminated propellants and explosives in the Pueblo Stockpile are all blister agent, are shipped off-site for commercial disposal. retooling of the plant for each munition type The LPMD is shown in Figure 4. (called change-over) requires only minor

    changes to the mechanical systems. With

    this in mind, and the overall requirement for

    neutralization followed by biological

     1 Taken from ACWA Program Fact Sheet on Chemical Weapons Destruction at U.S. Army Pueblo Chemical Depot, http://www.pmacwa.army.mil/co/ip/dl/acwa_pueblo_overview.pdf

    DUNNAGE/METAL OFF-SITE MUNITIONS MUNITIONS MUNITIONS PARTS SHIPMENT STORAGE SERVICE (G-BLOCK) MAGAZINE ENERGETICS STORAGE ENERGETICS/ SERVICE IGLOO HVAPROPELLANTS MAGAZINE (H-BLOCK) C VENBASELINE AND T OFF-SITE ENHANCED VENT TO SHIPMENT ENHANCED ATMOSPHERE EXPLOSIVE RECONFIGURATION CONTAMINATED RECONFIGURED DESTRUCTION ENERGETICS, CLEAN MUNITIONS TECHNOLOGY (EDT) LEAKERS, AND WASTE REJECTS DEMIN 25% NaOH WATER OFF-GAS VENT AGENT VENTREATMENT SYSTEM FILTER VENT T AREA VENT FROM (OTS) SDU/AUTOCLAVE MUNITIONS MUNITIONS BUFFER EMPTY CLEAN MUNITIONS TREATMENT WASHOUT SYSTEM OFF-SITE MUNITIONS STORAGE (MWS) SHIPMENT UNIT (MTU) VENT TO ATMOSPHERE VENT 25% NaOH WASHED BTA OTS 25% NaOH 5% NaOH STEAM AGENT VENT VENT TO ATMOS. SOLID SPENT BIO- AGENT COLLECTION WATER RECOVERY HYDROLYSATRESIDUE DECON DECON E TREATMENT & SYSTEM (WRS) 25% NaOH SYSTEM NEUTRALIZATION BRS OTS 93% HSO24 STEAM HOT PROCESS WATER VENT RECOVERED PROCESS BRINE REDUCTION CONDENSATOFF-SITE WATER TO WATER SYSTEM SYSTEM (BRS) E SOLID SHIPMENT USERS RESIDUE

    CLEAN DUNNAGE/ OFF-SITE SECONDARY WASTE SHIPMENT VENT TO OTS COOLING TOWER MAKEUP CONTAMINATED DUNNAGE/ SDU/AUTOCLAVE SECONDARY WASTE

    RAW TREATED SANITARY SANITARY SANITARY WASTE 25% NaOH 25% NaOH BULK CHEM WASTE WASTE TREATMENT TO USERS STORAGE

    Figure 2: PCAPP Process Flowsheet

    DUNNAGE/METAL OFF-SITE MUNITIONS MUNITIONS MUNITIONS PARTS SHIPMENT STORAGE SERVICE (G-BLOCK) MAGAZINE ENERGETICS STORAGE ENERGETICS/ SERVICE IGLOO HVAPROPELLANTS MAGAZINE (H-BLOCK) C VENBASELINE AND T OFF-SITE ENHANCED VENT TO SHIPMENT ENHANCED ATMOSPHERE EXPLOSIVE RECONFIGURATION CONTAMINATED RECONFIGURED DESTRUCTION ENERGETICS, CLEAN MUNITIONS TECHNOLOGY (EDT) LEAKERS, AND WASTE REJECTS DEMIN 25% NaOH WATER OFF-GAS VENT AGENT VENTREATMENT SYSTEM FILTER VENT T AREA VENT FROM (OTS) SDU/AUTOCLAVE MUNITIONS MUNITIONS BUFFER EMPTY CLEAN MUNITIONS TREATMENT WASHOUT SYSTEM OFF-SITE MUNITIONS STORAGE (MWS) SHIPMENT UNIT (MTU) VENT TO ATMOSPHERE VENT 25% NaOH WASHED BTA OTS 5% NaOH 25% NaOH STEAM AGENT VENT VENT TO ATMOS. SOLID SPENT BIO- AGENT COLLECTION WATER RECOVERY HYDROLYSATRESIDUE DECON DECON TREATMENT E & SYSTEM (WRS) 25% NaOH SYSTEM NEUTRALIZATION 93% HSOBRS OTS 24 STEAM HOT PROCESS WATER VENT RECOVERED PROCESS BRINE REDUCTION CONDENSATOFF-SITE WATER TO WATER SYSTEM SYSTEM (BRS) E SOLID SHIPMENT USERS RESIDUE

    CLEAN DUNNAGE/ OFF-SITE SECONDARY WASTE SHIPMENT VENT TO OTS COOLING TOWER MAKEUP CONTAMINATED DUNNAGE/ SDU/AUTOCLAVE SECONDARY WASTE

    RAW TREATED SANITARY SANITARY SANITARY WASTE 25% NaOH 25% NaOH BULK CHEM WASTE WASTE TREATMENT STORAGE TO USERS

    Figure 3: PCAPP Process Flowsheet Highlighting Main Process Operations

    agent to drain from the munition. This operation is conducted with the projectile oriented vertically, ojive down. Once the adapter is fractured and the burster well crushed, agent drains into a receiving cup. Once drained, the projectile is rinsed with high pressure water to remove residual agent material. A schematic of the MWS is shown in Figure 5. The agent and rinse water from the MWS is recovered in tanks for

    subsequent processing in the Agent

     Neutralization System (ANS). Figure 4: Linear Projectile Mortar 2.2.2 Munitions Washout System Disassembly Machine (MWS) for 4.2 inch Mortars As the 4.2 inch mortar has relatively thin 2.2 Removing the Mustard Agent walls and contains an internal baffle, hydraulic crushing of the burster well is not Once the energetic components have been conducted. Instead, the CAM for 4.2 inch removed, the projectile or mortar body mortars incorporates a cutting wheel to containing the mustard agent fill is remove the base of the mortar allowing transferred to a separate building for agent agent to drain. The cutting is done in an processing. The projectiles and mortars are enclosed space within the CAM to reduce at this point essentially heavy walled overall contamination. Following removal containers with a press fit burster well seal. of the mortar base, high pressure water is In U.S. baseline incineration plants, the again used to rinse residual agent material burster well is mechanically pulled out of from the mortar body and the removed the munition body and the chemical agent mortar base. The MWS for 4.2 inch mortar drawn out by vacuum. At the PCAPP, an processing is shown in Figure 6. As in the innovative approach will be used to remove projectile MWS, agent and rinse water from the chemical agent. The approach is the mortar processing is collected in tanks different for the projectiles and the mortars and then fed to the ANS. so they will be discussed separately. 2.3 Neutralizing the Mustard Agent 2.2.1 Munitions Washout System (MWS) for Projectiles. Hot water hydrolysis of distilled mustard was successfully proven out at the Aberdeen A unique system called a Munitions Chemical Agent Destruction Facility Washout System (MWS) will be used to (ABCDF) at an industrial scale. Using remove the agent from projectiles and rinse experience gained at the ABCDF, the residual agent material from the inside of the PCAPP ANS includes two turbine mixer munition body. The system consists of a equipped reactors with recirculation through robotic munitions handling system (using static mixers which are equivalent in the same robot model as used in the LPMD) throughput to the four reactors used at the and a number of Cavity Access Machines ABCDF. As HT has not previously been (CAM). For projectiles (105 and 155 mm), treated using this process, laboratory studies the CAM operates by hydraulically pushing were conducted to confirm the feasibility of the burster well into the munition, fracturing neutralization of HT. These studies the adapter, and creating an opening for the demonstrated that HT reacts very similarly

to HD, and analytical methods have been

    developed to confirm the destruction of HT.

    Projectile

    BursterWell

    Cup

     Hydraulic RamFigure 6: MWS for 4.2 in Mortar And Spray Processing

    2.4 Biotreatment of the Mustard Agent

    BursterwellHD mustard hydrolysates contain HydraulicallyProjectileCrushedPlaced inthiodiglycol (a similar diglycol is produced Cupfrom the T in HT), salt, NaOH and water.

    The organic diglycols can be effectively

    treated biologically. The biotreatment of

    mustard hydrolysate was demonstrated at

    the ABCDF using a large, off-site,

    commercial treatment facility. To treat Step 2Step 1hydrolysates on-site, the PCAPP design includes the use of twenty-four Immobilized

    Cell Bioreactors (ICB) segregated into six

    modules of four ICBs. Each ICB contains

    three treatment cells where air is passed Highthrough a proprietary packing material. PressureAgent WaterDrainBiological treatment occurs at the surface of Spray

    the packing and within the liquid in each

    ICB cell. Most of the treatment occurs in

    the first cell. Treatment in the second cell

    effectively completes the treatment with the

    third cell acting as a polishing treatment step.

    The effluent water from the ICBs is treated Step 4Step 3and returned to the process. Figure 7 shows the design of an ICB module.

    Figure 5: MWS Schematic for Projectile

    Processing

Another innovation at PCAPP is the

    elimination of the heating jacket for the

    reactors. The PCAPP reactors will use

    direct steam injection for heating. This will

    reduce the capital cost of equipment and

    provide for shorter heating times in what is

    the aqueous reactor system.

    is maintained above the capture velocity to assure that no chemical agent can be released from the clean end of the unit. Treated munitions exit the unit to bins outside of the processing facility. The steel from the projectile and mortar bodies will be reclaimed by smelting at an off-site facility. As the muffle contains both the metal parts and the ventilation air, there is never contact by chemical agent outside the muffle of the MTU. A cross-section of the MTU is shown in Figure 8.

    Figure 7: Immobilized Cell Bioreactor (ICB) InsulationMuffleModule

    2.5 Disposing of the Metal Parts

    Munition

    Another unique element of the PCAPP

    which supports the processing of large

    numbers of munitions is the method for

    treating the projectile and mortar bodies Heating ElementsBeltafter washout in the MWS. After washout, the projectile and mortar bodies (metal parts)

    Figure 8: Munitions Treatment Unit (MTU) may contain small yet measurable quantities

    Cross-Sectional Diagram of chemical agent. Batch thermal treatment

     processes require some form of staging area

    2.6 Secondary Waste Treatment before and after the process. Additionally,

     batch thermal processes produce a

    As chemical weapons are processed through maximum vapor emission load associated

    the PCAPP, contamination of miscellaneous with a batch of multiple metal parts

    other materials will occur which require thermally desorbing at roughly the same

    some form of treatment. These materials time. To avoid these two situations, the

    include gloves, protective suits and masks, PCAPP will utilize a continuous thermal

    containers, hoses, pallets, and other items processor to treat the metal parts from the

    which may come in contact with chemical MWS. The treatment unit operation is

    agent. This material is considered called a Muntions Treatment Unit (MTU).

    secondary waste. Two novel systems will The unit consists of an electrically heated,

    be used to treat secondary wastes at PCAPP. continuous belt muffle oven. Contaminated

    The Supplemental Decontamination Unit munitions from the MWS are placed on the

    (SDU) is a low temperature oven which chain belt and are conveyed through the

    treats waste in mesh trays in circulating hot oven. Six resistance heating zones provide

    air (typically 200-400ºF) in order to the positive control to heat the projectile and oovolatilize and/or decompose agent without mortar bodies to at least 1000 F (538 C)

    combusting the waste itself. The Autoclave for a minimum of 15 minutes thereby

    is the other waste treatment system at destroying any residual chemical agent.

    PCAPP, and is a standard commercial Clean air enters the unit at the discharge end

    vacuum cycle steam autoclave unit. A and passes through the muffle counter-

    version of SDU was successfully utilized at current to the metal parts. The volume of air

the ABCDF. Laboratory data collected on Table 2: Unit Operations of the PCAPP

    HD and HT show that with appropriate Process Flowsheet temperature and time, the range of potential

    secondary wastes expected at PCAPP can be Unit Operation Number of Parallel effectively treated for disposal in these units. Treatment Systems A list of the items tested is shown in Table 1. Linear Projectile 3

     Mortar Disassembly

     (LPMD)

    3. Conclusion Munitions Washout 2

     Stations (MWS)

    The process flowsheet for the Pueblo Agent Neutralization 1 (consisting of 2 Chemical Agent Destruction Pilot Plant has System (ANS) reactors) been developed to safely destroy over Immobilized Cell 24 ICBs in 6 780,000 chemical weapons stored at the Bioreactor (ICB) Modules of 4 Pueblo Chemical Depot. A number of novel Munitions Treatment 2 unit operations have been selected to remove Unit (MTU) energetics from the munitions, access the Supplemental 1 chemical agent contained in the munitions, Decontamination chemically neutralize both HD and HT, Unit (SDU) biologically treat the agent hydrolysate, Autoclave 1 thermally treat the drained and rinsed projectile and mortar bodies, and treat the contaminated secondary wastes from the process. The overall reliability and throughput of the PCAPP has been carefully evaluated in order to establish the number of parallel treatment systems required, as shown in Table 2.

    Table 1: Secondary Wastes Tested in SDU and Autoclave for HD and HT Treatment

    Material SDU Autoclave

    Steel Yes Yes

    Leather Yes Yes

    PTFE Yes Yes

    LDPE Yes Yes

    Butyl Rubber Yes Yes

    Wood (Oak) Yes Yes

    Wood (Pine) Yes Yes

    HEPA Filter Yes Yes

    Activated Charcoal Yes Yes

    Fiber Container Yes Yes

    PPE Material Yes Yes

Encapsulated HT Yes No

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