Hindustan Petroleum Corporation Limited (HPCL) – Visakh Refinery (East Coast –Andhra Pradesh, India) has 4 Nos. Gas Turbine Generators (GTGs) i.e., GTG – 3, 4, 5 & 6, each rated for 20 MW, which use Diesel as start-up fuel and Naphtha as fuel for power generation. Under Visakh Refinery Modernization Project (VRMP), the receipt, distribution, firing of Natural Gas (NG) is considered in the new GTGs.
For the existing GTGs, Natural gas will be made available at the battery limit of existing Captive Power Plant (CPP). It is proposed to have Natural Gas (NG) firing provision / Fuel Conversion system to enable NG usage as fuel in the existing GTGs. The Gas Conditioning System is designed for providing fuel gas in clean, dry conditions as acceptable to the Gas Turbine’s fuel gas quality requirements and at a pressure range as required by Gas Turbines.
This Study carries out HAZOP for Natural gas firing provision for Gas turbine generators (GTG’s) of HPCL Vizag refinery.
In this fuel conversion package, the fuel gas (Natural gas) made available at the battery limit is routed through Gas Conditioning system. The common system for two GTs consists of Scrubber skid (1X100%), Filter separator skid (2X100%), Electric Heater (1x 100%) & Steam Heater (1x100%). The individual streams to each GT consist of Fine Filter skid along with and Pressure Control Valves which regulates the pressure to the Inlet of GT’s.
Above configuration is replicated for other two GTs.
Clean gas outlet of this gas conditioning systems is routed to Gas Turbines.
Activities involved in HAZOP Study:
- Reviewing of PFD, P&ID, Plant Layout, Cause & Effect Diagram, Process Description, Equipment’s Data Sheet etc.…
- Node Separations in P&IDs of the process based on process streams, phase change and equipment’s.
- Describing the design intents of each nodes separated and seeking the approval of the facilitator prior to the workshop.
- Preparation of worksheet with various guide words, parameters, causes, consequences , safeguards and recommendations.
- Participation in the brainstorming Hazop workshop as a Scribe which consist of a (Facilitator/Chairman), Technical crew, Contractor and Client.
- Providing and implementing recommendations based on risk rankings and uninterrupted operation of GTGs.