Anhydrous Ammonia Pipeline/Terminals Computer Process Modeling and Simulation, and Process Improvements Engineering and Design

Project Synopsis

Engineering support for various operations associated with anhydrous ammonia (NH₃NH3) pipeline systems which include transport lines, booster stations, hot and cold (cryogenic) storage facilities and terminal flare systems.

Project Summary

NH₃ TERMINALS/PIPELINE PROCESS ENGINEERING SUPPORT

The client owns and operates an anhydrous ammonia (NH₃) pipeline system that includes the transport lines, booster stations, and hot and cold (cryogenic) storage facilities.  Process Engineering Associates, LLC (PROCESS) was contracted by the client to provide engineering support for various operations associated with these facilities as well as with the flare systems at the terminals.  Specific project tasks included the following:

• Development of a comprehensive heat transfer model designed to predict product vaporization rates from cryogenic storage tanks during refrigeration system shutdown periods given site-specific tank and system data and local ambient condition ranges.  PROCESS also developed site-specific operations manuals such that client engineering and operations personnel can use the program.

• Execution of flare system evaluations for all hot and cold storage terminals to determine if the flare systems meet operating regulations and guidelines and for making design and/or control system change recommendations to improve the flare systems operation as necessary.

• Development of a product pipeline hydraulic model designed to calculate emissions rates through various configurations and sizes of holes in the product pipeline. PROCESS also developed an operations manual explaining the use of the program for different pipeline breach scenarios such that client engineering and operations personnel can use the program.

• Development of computer process simulations using licensed commercial process simulation software and preparation of mass and energy balances and process flow diagrams (PFDs) for the refrigeration cycles at all cold storage terminals.

• Evaluation of compressor building ventilation systems at all cold storage terminals to determine that adequate ventilation was present to prevent lower explosive limit (LEL) excursions.   Recommendations for ventilation systems were made as necessary.

• Perform an investigation for the purpose of determining NH₃ flare NOx emissions values for flaring.

• Evaluation of the effect of bypassing the cold storage tank back pressure control valves on flare emissions.  The evaluation included development of a hydraulic model to calculate product velocity at the flare tips.

• Estimation of flare system fuel gas usage at a cold storage terminal in support of the client’s environmental permitting efforts.

• Evaluation of the flare systems of two cold storage terminals that can potentially blow down static inventories of product to the flare during maintenance operations.  This task included development of a hydraulic model to analyze fluid flow in the flare systems piping and knockout drums to help ensure that flare velocities met regulatory requirements.

As part of this project, the PROCESS project manager visited each hot and cold storage facility as well as many of the booster stations for the purpose of collecting the information required for evaluation of the vent/flare systems and for development of the emissions calculation programs.  PROCESS also designed control systems for all vent/flare systems to help ensure that the systems will comply with regulatory requirements, to provide a more automated method of controlling vapor product flow rates to the flares, and to facilitate better combustion conditions.

Industry Type

• Gas Pipeline

Utilized Skills

• Hydraulic modeling
• Computer simulations
• Flare system design