Operations

NCPA's staff control operators (CO), in conjunction with Lake County Sanitation District (LACOSAN) staff, operate the pipeline and injection system from the steam field control center near NCPA's Power Plant Number 1 in the southeast Geysers.

After LACOSAN personnel have put the lake intake pumps into service and there is adequate fluid in the Southeast Regional Wastewater Treatment Plant (SERWTP) reservoir for start-up, the CO starts a predetermined number of pumps at the SERWTP pump station to fill the pipeline through the Harris Creek Reservoir (HCR) to a level-balance-point above Bear Canyon Pump Station (BCPS) Number 1. The CO then shuts down the SERWTP pumps leaving the pipeline full to that point. Next, the CO places start-up injection wells into service using geothermal condensate from their associated power plants. In order to fill the pipeline into the Geysers, the CO will put the Adjustable Frequency Drive (AFD) pumps in service to a predetermined speed. As the pressure builds at the suction to the BCPs, the CO will command the next AFD to the same speed as the pump below. When fluid starts being taken from the HCR, the CO then re-starts the SERWTP pumps.

The CO changes the Bear Canyon control mode to "operate," which allows for combined control of pump sets (constant speed and variable) in the Bear Canyon system. The goal at this point is to 1) match Bear Canyon flow with SERWTP flow, and 2) pressurize the Bear Canyon system to a pre-selected Pressure Set Point (PSP). Once the system is pressurized, the CO then changes the BCC mode to automatic pressure control and enters a PSP for the system to maintain at the pipeline terminus. At this point, all fluid is delivered to the start-up injection wells, and the HCR level is controlled by the CO.

To begin automatic operations, the CO puts the start-up injection wells into automatic and enters a Level Set Point for the HCR. When the wells are in start-up configuration they become part of the effluent distribution system (EDS). The HCR level is controlled by means of flow distribution through EDS controls.

The CO starts the SERWTP pumps to attain the desired flow rate for the pipeline. The HCR level then increases and the EDS increases flow demand for the start-up wells. Increased flow demand to the start-up wells lowers the Bear Canyon system pressure, and the Bear Canyon system increases AFD demand to increase flow through the system. The CO then starts the constant speed pump sets in the BCC as the AFD command reaches a predetermined maximum speed. When the desired pipeline flow rate has been set and all systems placed in automatic, the CO focuses attention on redistributing fluid to other distribution points. This redistribution is a matter of communication with Calpine operators and the opening of control valves.