ABB adds SIS to Natural gas dehydration facility
Located near a field of producing wells in western USA, the facility has safety critical points at each of several manifolds that share the total flow of raw gas being processed. One such manifold, as indicated Figure 1, has gas inputs coming through pipes from five wells in one area of the well field. Gas from the wells ranges in pressure up to 3,000 psi in insulated, underground pipe specified for these high pressures.
Removal of free and entrained water is done in two consecutive process steps. Both steps occur in pipe and vessels rated at 1,600 psi, which must be protected from possible pressure excursions at the manifolds. Once free and entrained water is removed from the natural gas, it flows via pipeline to another plant that separates it into such products as methane, carbon dioxide, hydrogen sulfide, nitrogen, and helium. Dehydration and separation of the raw gas are normally continuous processes occuring in sequence.
Originally, the dehydration facility operated with a basic Distributed Control System (DCS) to reduce gas pressures at the manifolds to 1,500 psi, as required to remove free water. The facility depended on pressure safety valves installed within the downstream process areas to shunt any overpressure gas to a flare stack.
Protecting lower pressure equipment
Growing demands for natural gas resulted in upstream supply pressures at the manifolds to near the maximum allowable. At this point engineers conducted a risk analysis study that indicated need for independent SIS protection at piping locations vulnerable to serious overpressures. The risk study also determined that a Safety Integrity Level (SIL) of 2 would be sufficient for all the components of an SIS -- sensor, logic solver, and final control element.
In this application, the SIS sensors are a pair of electronic DP transmitters from ABB to measure each critical pressure point -- set at 1,510 psi on a PLC SIL 2 logic solver. The final control elements are ball valves installed in each high-pressure supply pipe -- two valves in series to provide proper SIL for safety shut-off in case of overpressure.
The facility chose ABB 2600T series pressure transmitters having SIL-2 ratings certified by the German test agency TÜV. SIL-2 pressure transmitters work in pairs to monitor safety critical points. A pair of ABB SIL-2 rated pressure transmitters offers the same protection as three redundant conventional pressure transmitters.
Generally the installed and operating cost of specialized transmitters is far less than that of the required conventional transmitters to meet a specific SIL value. Set at 1510 psi the SIS catches an overpressure condition and shuts the ball valves in the high pressure piping within affected manifolds. This action takes place before any pressure safety valve vents, eliminating this possible source of undesirable emissions.
ABB is a leader in power and automation technologies that enable utility and industry customers to improve their performance while lowering environmental impact. The ABB Group of companies operates in around 100 countries and employs about 107,000 people.
MORE CASE STUDIES
Bedrock provides SCADA RTU platform for Clarksville Light and Water
The project is part of Clarksville, Arkansas' plan to save up to $2M over the next five years through improved control, monitoring, and security of...
Stahlin's enclosures provide protection for ECS compost temperature sensors
Engineered Composted Systems needed a strong corrosive resistant NEMA 4X enclosure that could survive this environment and protect their RF...
GE Digital software boosts connectivity in Brazilian steel plant
Gerdau has decided to rollout GE Digital’s Asset Performance Management (APM) solution to connect 600 assets in 11 plants across Brazil.
Inex dairy chooses Leroy-Somer motors to drive eneergy savings
A Belgium-based producer of dairy products, Inex is achieving minimum energy savings of at least 18% from its refrigeration process as a result of...
Supergasbras implements Implico's SAP SDM to automate logistics processes
Supergasbras needed a solution that offered comprehensive analysis tools, full process automation and the option of mobile use. The technology also...
Webinar: Increase Production and Optimize Manufacturing Processes Using Simulation
The webinar will show how engineers, production managers, and decision makers can rapidly assess the options for adapting an existing line to make...
Rockwell to showcase solutions for Water and Wastewater Facilities at WEFTEC 2016
Featuring its PlantPAx platform, Rockwell Automation will demonstrate process and automation solutions for efficient process control, monitoring...
Siluria names Erik Scher as Chief Operations Officer
As COO, Dr. Scher is responsible for the company's operating activities, including its OCM demonstration plant in Texas and multiple pilot plants...
ABB announces NKT Cables acquisition of ABB's cable system business
NKT Cables is acquiring ABB’s global high-voltage cable system business with a total value of 836 million euros (US$934 million). The business is...
IMTS concludes as third largest in their history
IMTS 2016, the 31st edition of the show, was the third largest in number of registrations (115,612) and in net square feet of exhibit space...