Con Edison’s East River Repowering Project in Manhattan, a truncated ‘combined cycle’ facility to maintain what the utility calls reliable and reasonably priced steam supply and electricity for Con Edison customers in New York City, went into operation several years ago as part of a major improvement project at the East River energy complex.

It employs two GE combustion turbines connected to two HRSGs and a steam ring header. This unique configuration provides steam at 3.2 million lb/h for dispatch into Manhattan, where it is used as a key source for the district heating system. Control for a number of critical processes in the 360 MW plant was managed by Emerson’s Ovation platform.

Con Edison’s large investment in this plant made safe and timely commissioning and start up crucial. Because the East River facility is located in Manhattan, Con Edison also had to adhere to strict environmental constraints, such as noise levels during construction, as well as emissions levels during plant commissioning, startup and operation.

Optimising start up

In order to help ensure optimal operation of the plant, Con Edison looked for a way to efficiently train their operators using equipment and plant models duplicating the repowered plant prior to actual commissioning and startup. Con Edison also wanted a tool to help them verify and validate new control logic prior to its installation into the plant’s Ovation control system.

The company has been a customer of Emerson’s for two decades, and decided that the best approach was to work with them to try and provide the right solution. Emerson’s ‘Scenario’ simulation product was selected to monitor and control the unique processes associated with the new technology employed at the East River site. In practice, this meant Con Edison engineers and operators teaming up with Emerson to configure a high-fidelity Scenario solution.

Simulation training

Emerson is finding that in the current ROI driven business climate power producers are beginning to appreciate more the value of a flexible simulation tool and are keen to take advantage of what it offers for engineering analyses, validation of new control logic and enhanced operator performance, all of which contribute to increased plant reliability and safety. The Scenario product has developed into a flexible tool utilising tie-back logic, algorithmic models and comprehensive first-principle models, to provide a range of training and engineering simulation solutions that can be tailored to individual facilities.

ERRP’s simulation consists of actual plant control software and duplicate workstations that mimic the East River control room. Scenario was used extensively to train operators, formerly familiar with traditional boiler/steam turbine plant configurations, on the operation of the new truncated combined cycle plant, a configuration in which turbine exhaust is used to generate high grade process steam rather than power a steam turbine. Through using the simulation technology, operators also became well versed in using the microprocessor-based system, which, unlike the previously installed hard-wired controls, enables operators to more quickly recognise and react to abnormal plant process situations. Scenario simulation was also used to develop optimum operator methodology that is documented in the plant’s operating procedures.

During the simulation design phase and prior to plant startup, East River’s operators and engineers used the simulator to evaluate both steady state and transient conditions based on plant design criteria. Results from these evaluations provided Con Edison engineers with a better understanding of process dynamics and enhanced troubleshooting tactics, leading to the development of accurate control strategies under normal and abnormal operating conditions.

Con Edison also used Scenario to test the interfaces with third-party equipment connected to the Ovation control system, such as the GE Mark V turbine control system and PLC networks for the burner management, gas compressor and water treatment systems. Pre-testing of the data links helped to further reduce the plant’s commissioning time.

‘Use of Scenario helped to ensure that Con Edison’s investment in ERRP’s new plant technology would be optimised by well-trained operators and accurate controls’ said Hsiu-Chen Wang, the Con Edison senior engineer for the project. ‘One major benefit was safe and efficient plant startup that reduced the plant’s commissioning time from four months to one month.’

Optimising other processes

After a successful plant startup, Scenario simulation is now used to optimise East River’s processes for improved efficiency and reliability. Further plant tuning, as well as the addition of any new equipment, can be tested and confirmed using the simulation technology before integration into the live system. Con Edison is also considering using Scenario as a means to realise additional revenue through its Learning Centre outsource training for new cogeneration facilities throughout the New York metropolitan area.