NeSSI is an open, ad hoc initiative which is primarily concerned with the treatment and analysis of samples extracted from process equipment such as pipes and vessels (e.g. fractionation colum, heat exchanger) located in refineries or petrochemical plants. NeSSI provides specifications, guidelines and a forum for the on-going development of a Lego-style building block approach for analytical systems. This initiative is sponsored by the Center for Process Analytical Measurement (CPAC) situated at the University of Washington in Seattle, Washington, USA. The driving forces behind this initiative are to improve analytical system reliability through automation as well as to make analytical systems less expensive and simpler to build and maintain.
Background
editIn oil refineries and petrochemical manufacturing plants the discipline of process control is essential to make sure that equipment and processes operate in a safe and efficient manner. Process control requires data from many measuring instruments located throughout the plant, and uses control algorithms to manipulate pressures, temperatures and flows of the fluids in the plant to achieve desired operating objectives. One important class of measuring instrument is the process analyzer. A process analyzer is a device which can measure the chemical composition or the intrinsic physical properties of process fluids (vapors and liquids). Frequently this is achieved by extracting a sample of the process fluid, conditioning it in a sample system and then introducing it into the analyzer. The design features of analytical sample systems have changed little, from the early 1930's when the discipline of Process Analytics began in Germany, right through until the present day.
History
editThe rationale for NeSSI™ originated from focus group meetings held in 1999 at CPAC which called out for more reliable sampling and analysis for the manufacturing processes. Early work with NeSSI™ was started in July, 2000 by Peter van Vuuren (ExxonMobil Chemical) and Rob Dubois (Dow Chemical) with the (initial) aim of adopting new types of modular and miniature hardware which were being addressed in a standard being developed at that time by an ISA (Instrumentation, Systems and Automation) SP76 working group. (Reference 1) The term NeSSI™, along with the futuristic concepts of a NeSSI™-bus and smart sampling devices were first introduced outside of CPAC at a presentation given in January 2001 at the International Forum of Process Analytical Chemistry (IFPAC) at Amelia Island, Florida, USA. The Generation II conceptual and functional electrical specification was released by CPAC in 2003 and is an open publication on the CPAC/NeSSI website. (Reference 2)
Technical Objectives
edit- Facilitate the acceptance and implementation of modular, miniature & smart sample system technology based on the ANSI/ISA SP76 standard substrate.
- Provide a technology bridge to the process for sensor or lab-on-a-chip micro-analytical devices
- Promote the concept of field-mounted (By-Line) smart analytical systems.
- Lay the groundwork for Pipe to Pixel™ open connectivity architecture for intrinsically safe device (sensors and actuators) communication and industry standard communication protocols.
Comparison of Current vs. NeSSI™ Technology (Extractive Systems)
| CURRENT | NeSSI™ |
|---|---|
| Analyzer shelters | Analytical system close to the sampling point (By-Line) |
| Long, traced transfer lines | Short lines, fast response |
| Extensive design required | Minimal design, standard based design |
| Custom assembly | Modular Lego®-like assembly |
| Field repair | Modular replacement |
| Sample may not reach the analyzer | Sample flow is validated |
| Large amount of sample | Small amount of sample, less material to condition |
| Sample may condense | Temperature is controlled to prevent condensation |
| Conduits, seals, armored cable, purging | Simple plug-in connector, unarmored wiring using miniature, flexible cable |
| Large space required | Small, compact, low internal volume |
Applications
editNeSSI™ is used for process analytical measurements in the petrochemical, chemical and oil refining industries. These measurements may be for quality monitoring of raw material or final product, environmental compliance, safety, energy reduction or process control purposes. Vapor applications may include hydrocarbon feed stocks and intermediates (ethylene, ethane, propylene, etc.), natural gas streams, liquefied petroleum gas (LPG) streams, hydrogen and air gas streams. Liquid systems applicable to NeSSI™ are hydrocarbons such as diesel fuel as well as aqueous streams. Highly viscous fluids and solids are not suitable for use with NeSSI™. Very dirty, high particulate streams need to be filtered. Some liquid service applications may be limited by pressure drops associated with components hooked up in a serial configuration. NeSSI™ systems have found applications in areas other than the process analytical environments including micro reactor, mini plant and laboratory environments where small size, unskilled assembly and flexible configuration is important.
Technology Development Roadmap
editNeSSI™ technology development has been grouped into three technology generations which are backward compatible. The time spans project time to first commercialization. Gen I is commercialized and proven in numerous industrial and laboratory applications.
Technical Development Roadmap
Generation I – Fluid Components
editGeneration I covers mechanical systems associated with the fluid handling components. Generation I has adopted the ANSI/ISA SP76.00.2002 miniature, modular mechanical standard. SP 76 defines a dimensionally standard footprint which allows interchangeability of surface mount components between different manufacturers.
SP76.00.02-2002 Standard Footprint
Currently three manufacturers produce the substrates which provide the platform for the surface mount components. There are over 60 different types of surface mount components available from various suppliers who provide valves, filters and regulators as well as pressure and flow sensing devices. Commercial Systems (from left to right) Swagelok, CIRCORTech, Parker-Hannifin
Generation II – Connectivity using NeSSI™-bus and the SAM
edit- Adoption of a digital communication bus (NeSSI™-bus) that is specifically tailored for process analytics and intended to replace 4-20 mA systems.
- Classifying the interior of an enclosure handling hazardous fluids as Division 1/Zone 1 rather than Division 2.
- Adopting the use of a low energy, globally accepted Method of Electrical Protection called Intrinsic Safety for the NeSSI™-bus.
- Adopting the use of plug and play, self-identifying smart sensors, actuators and heaters.
- A move away from the use of local indicating devices such as gauges and rotameters in order to reduce labor intensive manual checking (rounds).
- Moving from a centralized control (automation) model to a local/field model which is represented by a small device called SAM (Sensor Actuator Manager).
- Adopting the concept of portable, 3rd party software “applets” for use with SAM.
- Sharing high level analyzer information and data over an Ethernet ANLAN layer to/from DCS (Distributed Control System) and O&M (Operation and Maintenance) users.
- Introduction of a Graphical User Interface (GUI) (WIKILINK) for better visualization of physically compact sampling systems.
Generation II Connectivity Model using NeSSI™-bus and SAM
Generation III - microAnalytical
editThe introduction of new microAnalytical devices to the process industries can be enabled by employing standard physical, electrical and software interfaces. Generation III will allow tighter integration of the sample conditioning and analytical measurement devices.
References
- “ANSI/ISA 76.00.02-2002 Modular Component Interfaces for Surface-Mount Fluid Distribution Components – Part1: Elastomeric Seals,” Instrumentation, Systems, and Automation Society (ISA), Compositional Analyzers Committee, (2002), www.isa.org
- Dubois, Robert N.; van Vuuren, Peter; Gunnell, Jeffrey J. “NeSSI™ (New Sampling/Sensor Initiative) Generation II Specification”, A Conceptual and Functional Specification Describing the Use of Miniature, Modular Electrical Components for Adaptation to the ANSI/ISA SP76 Substrate in Electrically Hazardous Areas. Center for Process Analytical Chemistry (CPAC), University of Washington, Seattle WA, (2003) www.cpac.washington.edu/NeSSI
External Links www.cpac.washington.edu/NeSSI