ESC is continuously focused on the safety of our employees and customers. Learn more about our COVID-19 response plan and find answers on frequently asked questions.        Learn More
Industry:  Petrochem Products
Project Type:  StackVision Full DAS Implementation plus OPC UA
Scope:  1 Natural Gas Boiler
Driver:  Expansion project includes 450 MMBTUH boiler
Regulation(s):  40CFR60 (NSPS) Appendices A, B, F, and Subpart Db plus ODEQ permit
Parameter(s):  NOx, O2, CO, VOC, SO2, PM
Location:  Oklahoma
Year:  2018

Project Description

The driver for this installation was an expansion project to build a large capacity urea plant and make improvements to the existing urea and ammonia plants. Construction of a new 450 MMBTUH boiler to support the expansion was part of the project. The facility was also getting modern smart analyzers and there was a need for PI data to go into the DAS as well. The facility falls under Oklahoma Department of Environmental Quality (ODEQ) regulation. The boiler falls under NSPS Subpart Db, but the state permit is overall more restrictive than Db. There were specific requirements from the state for both the CEMS and data management.

Problems or Requirements

DAS must communicate with “Smart” Analyzers
An important requirement of the project was that the new DAS be able to communicate with the new smart analyzers being installed as part of the project.
Wanted DAS to write to and read from PI servers
The original request had specific language that at first posed a problem. For the sake of security, our PI communications keep the plant systems in control and so they are not set up to “write to” or push data into plant systems. Fortunately, the actual need was simply for two-way communications between the PI servers and the DAS.
Previous DAS had difficulty with Subpart Db
Initially, their plan was to have the vendor add the new boiler to the former DAS, but they ran into difficulties with implementation as requested. That DAS was older, and the requirements were not “plain” Db.
ODEQ permit more stringent than Subpart Db
Among other differences there are some 3-hour and 30-day average limits required which are not a standard part of Subpart Db. Also, as a part of ODEQ’s major source standard conditions, all fuel-burning equipment is required to minimize emissions of VOCs (Volatile Organic Compounds). So, VOC monitoring needed to be tracked and reported also.

Solutions and Outcomes

Modbus to DCS device communication
The 8864 Data Controllers allow for complex Modbus communications. In this case a mix of devices in the DCS talk with the 8864 over Modbus. Modbus provides rich digital communication for most smart devices.
Requirement for two-way communication with PI servers met with OPC UA
PI to DAS communications go by the OPC UA server installed with StackVision. It can act as slave to historians or other OPC servers. Our Data Mapper Utility makes it simple to concentrate data from multiple OPC DA/UA servers and disparate systems, devices, and machines.
StackVision handles Db
StackVision has no problem with the QA, monitoring, recordkeeping and reporting requirements of NSPS Subpart Db, even with added ODEQ requirements and the use of some options in the appendices.
No CEMS for Boiler MACT
The facility uses Pipeline-quality Natural Gas (PNG) for feedstock, so they split the stream and use PNG as fuel for the boilers, also. The clean gas fuel source combined with the frequency of use, newness, and large size of this boiler means they are required to do an annual tune-up to comply with Boiler MACT, but no monitoring.

Questions about the ESC DAS?

We'd love to answer your questions.

Contact Us

New to Data Acquisition Systems?

Check out our helpful animation that teaches the basics of

What is a DAS?