Aspen Solids

Jump Start: Solids Process Modeling for Experienced Aspen Plus ® Users A Brief Tutorial (and supplement to training and online documentation) Jennifer Dyment, Product Marketing, Aspen Technology, Inc. Claus Reimers, Product Management, Aspen Technology, Inc. Ajay Lakshmanan, Product Management, Aspen Technology, Inc. Matthias Pogodda, Software Development, Aspen Technology, Inc. Wilfried Mofor, Product Management, Aspen Technology, Inc.

© 2014 Aspen Technology, Inc. AspenTech®, aspenONE®, the Aspen leaf logo, the aspenONE logo, and OPTIMIZE are trademarks of Aspen Technology, Inc. All rights reserved.11-5035-0414

Jump Start: Solids Process Modeling for Experienced Aspen Plus ® Users

Table of Contents Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 First Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Specifying Solid Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Specifying Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Specifying Stream Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Particle Size Distribution Meshes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Unit Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 The Model Palette . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Dryer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Spray Dryer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Crystallizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Granulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Crusher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Fluidized Bed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Conveying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Results Summaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Activated Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17



Introduction Solids process modeling with Aspen Plus provides an integrated solution for simulating processes containing solids. With the tools provided, it is easy to characterize and model these components and obtain reliable results based on the world’s most comprehensive property database and proven simulation technology. This functionality bridges the gap between process engineering and particle science by providing the tools to seamlessly integrate rigorous models for solid streams and unit operations with typical fluid process models. Now users can simulate processes that contain both fluids and solids in the same simulation environment, allowing accelerated production of consistent, conceptual designs. This document serves as a simple “getting started guide” for users who are experienced with Aspen Plus (but not necessarily solids process modeling). We will take you through the most common progression of how a process designer creates a simulation and implements solid components and unit operations. This is not meant to be used as a stand-alone reference document. We recommend that a range of other resources be called upon to give the new user a comprehensive view of how to use solids modeling in Aspen Plus. These may include: • AspenTech support website (support.aspentech.com) – contains a wide range of knowledge base items and provides answers to frequently asked questions • AspenTech self-guided examples are available on aspenONE® Exchange or can be accessed by going here: http://www.aspentech.com/October_2013_solids_modeling_demo_AT/

• AspenTech courseware available in on-line and in-person versions — provides formal training on process modeling • AspenTech business consultants This document covers solids modeling in Aspen Plus. This guide assumes that the user has Aspen Plus V8.4 or higher installed on their computer. Most features were introduced with V8.0, such as particle size distribution characterization and a majority of the unit operations. See Table 1 below for more information.

Version

Date of Release

Features

Aspen Plus V8.0

December 2012

• Integration of 25 SolidSim unit operations • PSD characterization • Solids-related results representation

Aspen Plus V8.2

May 2013

• Economics for solids processing (Activated Economics) • Total of 38 SolidSim unit operations integrated • Enhanced PSD definition and results representation

Aspen Plus V8.4

November 2013

• Conceptual models • Spray dryer unit model • Reactions in fluidized bed unit model

Table 1: Solids related features highlighted for the Aspen V8.0, V8.2, and V8.4 releases


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First Steps This section talks about the first steps you must take to include solid components in your model. It does not cover every step in creating a flow sheet.

Specifying Solid Components When you specify a component, its default type is Conventional. However, in order to model solid components you must change this to Solid (Figure 1).

Figure 1: Specify a stream as solid

Specifying Properties Since the properties for solids are different than the conventional properties for fluids, it might be necessary to manually manage those that apply to your process. In the Navigation Pane, select the “Methods” folder, then “Parameters.” Then click “New” and select the type of parameter that you want to specify in the pane that follows (Figure 2).

Figure 2: New property specification

Next, fill in the matrix of parameters and components as desired. Hover over any of the parameters in the dropdown list to see what the variables stand for (Figure 3).


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Figure 3: Specify properties for desired compounds

Tips and Tricks: You can always manually specify properties for components. This is especially helpful when working with compounds that are not well documented (such as different grades of coal).

Specifying Stream Class Once all of the property specifications are complete, you can move on to flow sheet specifications in the Simulation Environment. In the “Setup – Specifications” form you must select an appropriate stream class. To determine which is best, hover over the different choices on the dropdown menu to see suggestions (Figure 4). Typically, MIXCIPSD is a good choice when conventional solids are present with a particle size distribution.


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Figure 4: Specify stream class

Particle Size Distribution Meshes A common way of characterizing a solid stream is by particle size distribution (PSD), which describes the relative quantity of particles of varying sizes in a stream (generally a powder or granular material). A PSD can be expressed as either a list of values or a mathematical function. To define a PSD in Aspen Plus, you must first create a mesh (array of particle size classes), which characterizes a particular PSD. In the Navigation Pane, go to the “Setup” folder, then “Solids,” and select “PSD.” In order to define the PSD mesh, you either select a pre-defined mesh type (e.g. equidistant, geometric, or logarithmic) and enter the necessary parameters, or you define your mesh manually (e.g. selection user) as tabular data. For the later option, you can also copy and paste from the spreadsheet tools (e.g. MS Excel). Fill out the required inputs and select “Create PSD Mesh” (Figure 5). While the first mesh you define (named “PSD” by default) is used for the simulation, additional meshes can be created for streams that have different particle size distributions. To create additional meshes, go to “Solids” and select the PSD Mesh tab. Then choose “New…” (Figure 6). It is also possible to create new meshes on the stream data input (see ‘streams’). For more information, visit the self-guided example for setting up a particle size distribution in Aspen Plus available on aspenONE Exchange.

Figure 5: Create PSD mesh


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Figure 6: Generate additional PSD meshes

Unit Operations Table 2 shows a list of all of the solids unit operations available in Aspen Plus. This section only focuses on getting started with five of the most common blocks. To find more detail on any of these or to learn about the unit operations not discussed here, check out the Computer Based Training (CBT) Courses available on the AspenTech support website.

Unit Operation

Block Name

Tab

Classifier

Classifier

Solids

Crusher

Crusher

Solids

Crystallizer

Solids

Dryer

Solids

Granulator

Solids

CCD

Solids

Screen

Screen

Solids

Single Stage Solids Washer

Swash

Solids

Centrifuge

Cfuge

Solids Separators

Cyclone

Solids Separators

Electrostatic Precipitator

ESP

Solids Separators

Fabric Filter

FabFl

Solids Separators

Filter

Filter

Solids Separators

Hydrocyclone

HyCyc

Solids Separators

Venturi Scrubber

Vscrub

Solids Separators

FluidBed

Solids

Pipe & Pipeline

Pressure Changers

Crystallizer Convective Dryer and Spray Dryer Granulator/Agglomerator Multi-stage Solids Waster and Counter Current Decanter

Cyclone

Fluidized Bed Solids Conveying

Table 2: Solids unit operations in Aspen Plus


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The Model Palette To open the Model Palette, click the Model Palette button in the Show group on the View tab (Figure 7). There are two tabs on the palette that contain solid unit operations, the Solids tab and the Solids Separators tab (Figure 8).

Figure 7: The Model Palette button

Figure 8: The solids model palettes – Solids (top), Solids Separators (middle), and Pressure Changers (bottom)

Dryer There are two ways to model a dryer in Aspen Plus: shortcut dryer and convective dryer. There is also an option to model a Spray Dryer in Aspen Plus. Please see the section below. In order to switch types, use the dropdown menu on the Specifications tab for the dryer (Figure 9). The shortcut dryer allows you to model the unit operation with a minimum of information and can be used for any type of dryer. The convective model requires additional material streams for input and output of a drying gas (Figure 10) and requires more information. This is the more rigorous model.

Figure 9: Select dryer type © 2014 Aspen Technology, Inc. AspenTech®, aspenONE®, the Aspen leaf logo, the aspenONE logo, and OPTIMIZE are trademarks of Aspen Technology, Inc. All rights reserved.11-5035-0414

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Figure 10: Material streams for convective dryer model - red indicates a required stream, while blue indicates an optional stream

There are a number of self-guided examples pertaining to modeling dryers in Aspen Plus available on aspenONE Exchange. Examples include a belt dryer, fluidized bed dryer, mill dryer, flash dryer, and a batch dryer.

Spray Dryer The Spray Dryer model is found in the Dryer block and allows you to model a wide range of industrial spray dryers. The model is based on single droplet drying kinetics and does not consider the coalescence of droplets or the agglomeration of particles. The model considers multiple aspects of the spray dryer including atomization, droplet movement, drying, and particle formulation. Under the atomization tab (Figure 11), users have the ability to specify the type of model used for the droplet size distribution, including a built-in atomization model.

Figure 11: Atomization can be specified with the atomization tab of the Spray Dryer unit operation

The droplet movement is considered as downward fall and the equation of motion is derived from a force balance with ignores lift. The model considers the first (constant drying rate) and the second (falling drying rate) period. The second drying rate is described by use of a normalized drying curve. The normalized drying curve can be defined as tabular data or by use of a drying curve function. Particle formulation starts after the moisture content of the particle reaches the critical moisture content. Particle formulation can either be described with a solid particle model or with a porous particle model.


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Solid Particle Droplet

e kag

Wet Particle

rin

Sh eal

Id

Const Diameter Porous Particle

Ideal Shrinkage

Xcrit

1st Drying Stage

2nd Drying Stage

Figure 12: After critical moisture is met, the particle can either shrink in diameter to a solid particle or maintain a constant diameter and become a porous particle

There is self-guided example pertaining to modeling a spray dryer in Aspen Plus available on aspenONE Exchange.

Crystallizer The crystallization block allows you to model steady-state crystallization. To do so, you can choose between three different calculation methods: solubility, chemistry, and user subroutine (Figure 13).

Figure 13: The crystallizer form: input calculation method and operating mode

Each method requires a different set of input parameters, allowing you to choose how to calculate based on available property and operating information.


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Granulator The granulator block allows you to model the growth of particles by either granulation or agglomeration. In addition to this, the block has a shortcut model that allows you to define the outlet PSD (conceptual/short-cut model). Table 3 summarizes the minimum stream requirements for each of these options. If you include a gas stream, your model becomes a fluidized bed granulator and you cannot use either of the shortcut methods.

Table 3: Granulator methods and their associated stream requirements

If you select particle growth by granulation, there are two available calculation models: mixed and plug flow. In mixed, all parameters are independent of position, whereas in plug flow, size is dependent on position. Both models assume: • Steady state process • All particles are spherical • The suspension and particles are homogeneous • The solid concentration of the suspension is constant

In the case of a fluidized bed granulator, solids may be entrained by the fluidizing gas. To consider this, you must add a fluidization gas stream to the block and specify the cross-sectional area of the granulator and the ‘separation sharpness’ (Figure 14).

Figure 14: Specify elutriation parameters for a fluidized bed granulator


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There are self-guided examples for modeling granulation and agglomeration in Aspen Plus available on aspenONE Exchange.

Crusher You can model a variety of crushers and mills with the crusher block. Aspen Plus provides three methods to determine the outlet PSD: • Use an equipment model (e.g. hammer mill) • Determine outlet PSD from a power and distribution function • Define outlet PSD by use of a distribution function or tabular data If you want to use an equipment model, you must choose the equipment type and provide the necessary geometry and operating parameters (Figure 15).

Figure 15: Specify crusher type

For a first estimate, it might be sufficient to specify the outlet size distribution or determine it based on the comminution power. If you wish to use a comminution power, you must provide a Bond work index on the Grindability tab and specify if you wish to use Bond’s, Rittinger’s, or Kick’s law to calculate it (Figure 16). Table 4 summarizes the appropriate situations for each law.

Table 4: Determine the appropriate comminution law


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Figure 16: Specify comminution law and bond work index for a crusher

You can define the outlet PSD by using either distribution functions or by using tabular data.

Figure 17: Specify outlet PSD using tabular data for a crusher

There is a self-guided example for modeling crushing and screen potassium chloride in Aspen Plus available on aspenONE Exchange.


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Screen Aspen Plus allows you to model multi-deck screens. When creating a screen block, you must include outlet overflow (coarse material) and underflow (fine material) streams. You also have the option of adding up to nine midsize streams. Once you have added the appropriate number of material streams. You must fill out the stream specification matrix. Aspen Plus will automatically provide the appropriate number of screen decks to accommodate the desired number of outlet streams (Figure 18).

Figure 18: Screen specification matrix

The classification of the particles on each screen deck is described by a selection function (e.g. Plitt, Rogers, Molerus etc.). In addition, you can also specify outlet fines or calculate the fish-hook effect using the Whiten model, by filling out the appropriate parameters on the matrix.

Fluidized Bed The fluidized bed model in Aspen Plus allows you to model reactions, fluid mechanics, and the interaction of both—as well as the entrainment of particles. It also considers the geometry of the vessel, any additional gas supply, and the impact of heat exchangers on the bed temperature and fluid mechanics. With these features, you can determine the minimum fluidization velocity, the transport disengagement height, and the entrainment of solids from the bed. The fluidized bed model (Figure 19) considers two zones in the vessel, the bottom zone or dense bed and the freeboard, allowing you to determine the bubble related profiles in the bottom zone and the entrainment of solids in the freeboard.

Figure 19: To the left is a schematic of the two zones within the fluidized bed and to the right is the corresponding solids holdup as a function of reactor height


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Chemical reactions can be considered in the fluidized bed including changes in the PSD due to reactions. The reactions are defined in the reactions form for the simulation and can be further described with solids information by clicking the solids button (Figure 20).

Figure 20: For reactions involving solid phases, a solids form, accessed in the reactions tab, allows the user to specify which phases the reactants are in

There are self-guided examples for modeling fluidization including a fluidized bed reactor in Aspen Plus available on aspenONE Exchange.

Conveying Pneumatic conveying is used to transport powdered and granular solid material over short and long distances. This can be described by using the pipe or pipeline blocks that can be found on the Pressure Changers tab in the model palette of Aspen Plus. Both the pipe and the pipeline block allow you to model dilute and dense phase conveying of granular solids. In general, dilute phase has a lower solids loading and a lower pressure drop but the velocity at which the solids travel through the pipe needs to be relatively fast to avoid saltation or clogging. With dense phase conveying, solids are transported in dunes or slugs at low velocities and high pressure. Conveying lines can be operated in pressure or suction mode, depending on the positioning of the blower which is responsible for the pressure change (Figure 21). There are self-guided examples for modeling transportation of solids by pneumatic conveying in Aspen Plus available on aspenONE Exchange.

Figure 21: Users can see the pressure, elevation, and velocity as a function of the pipeline length © 2014 Aspen Technology, Inc. AspenTech®, aspenONE®, the Aspen leaf logo, the aspenONE logo, and OPTIMIZE are trademarks of Aspen Technology, Inc. All rights reserved.11-5035-0414

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Analysis Results Summaries Two quick ways to obtain information about your model are the model and stream summaries. The model summary, accessible from the Model Summary button in the Summary group on the Home tab, (Figure 22), provides information on the input parameters and operating conditions for every block in your process. It is organized by unit operation, therefore all of the blocks of a common type are summarized on the same tab (Figure 23).

Figure 22: The Model Summary button

Figure 23: The model summary form

Tips and Tricks: Blue parameters in the model summary are user inputs and can be changed directly in the form.

The stream summary displays all of the information available on each of the streams in the model. It is accessible from the Stream Summary button in the Summary group on the Home tab. When viewing the summary you have the option of viewing all streams, or restricting your view to selected streams. To choose, select the appropriate option from the “Display” dropdown in the upper left corner (Figure 24).


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Figure 24: The stream summary – Choose to see either all streams or selected streams

To find information on streams that contain solid materials, it is important to scroll down the summary matrix until you reach the item that says “*** ALL PHASES ***.” Complete data for streams containing solids will only be available below this row (Figure 25).

Figure 25: Scroll down to *** ALL PHASES *** to find data on streams containing solid materials

Additionally, you can filter what type of data is shown in the stream results by selecting a category from the “Format” dropdown menu (next to the “Display” dropdown). To view the particle size distribution of each stream in tabular form, select “SOLIDS.”


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Tips and Tricks: Data from the matrices provided by the model and stream summaries can easily be highlighted and then copied and pasted directly into Microsoft Excel.

Plots There are a variety of plots that you can create to visually analyze your data (PSD, Separation Efficiency, etc.). To generate a plot, open the form for a unit operation or material stream and select the appropriate button from the Plot group on the Home Tab. Note that you may have to scroll down to reach the desired button. You can also view all the available plot types by clicking the down arrow below the scroll bar (Figure 26). To determine what type of information is displayed on each plot, hover over the button.

Figure 26: Select the desired type of plot

Bear in mind, different types of unit operations and material streams are conducive to generating different kinds of plots. For example, you cannot generate PSD plots unless solids are present.

Note: You can only generate plots if you have run the simulation and obtained results.

Activated Economics While developing a design, you can utilize activated economics to explore different configurations and options to choose the most cost effective design. With activate analysis, you can explore priliminary cost analysis with the click of a button and explore the costs associated with each step by hovering over the unit after running activated economics (Figure 27).

Figure 27: Economic Analysis was done for the crushing section of this process to determine a first estimate of the cost of the project


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Additional Resources For further information on solids process modeling with Aspen Plus please consult:

Public Website: http://www.aspentech.com/

Support Website: The support website provides an extensive and growing knowledge base as well as Computer Based Training (CBT) Courses http://support.aspentech.com/webteamasp/My/FrameDef.asp?/webteamasp/My/product.asp?id1=4&id2=''&id3=all

Example Files: Click the Examples button on the Get Started tab when you open Aspen Plus to see some out of the box simulations. Using aspenONE Exchange or the support website, you can also access self-guided examples, which include both an example simulation and a step-by-step guide to work through the example. These self-guided examples can also be accessed here: http://www.aspentech.com/October_2013_solids_modeling_demo_AT/.


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About AspenTech AspenTech is a leading supplier of software that optimizes process manufacturing—for energy, chemicals, engineering and construction, and other industries that manufacture and produce products from a chemical process. With integrated aspenONE® solutions, process manufacturers can implement best practices for optimizing their engineering, manufacturing, and supply chain operations. As a result, AspenTech customers are better able to increase capacity, improve margins, reduce costs, and become more energy efficient. To see how the world’s leading process manufacturers rely on AspenTech to achieve their operational excellence goals, visit www.aspentech.com.

Worldwide Headquarters Aspen Technology, Inc. 20 Crosby Drive Bedford, MA 01730 United States phone: +1–781–221–6400 fax: +1–781–221–6410 [email protected]

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