In thermal power plants, the steam surface condenser is the heart of the operation — and a key element to the plant’s water-steam cycle. A condenser is critical in that its efficiency directly affects the plant’s power-generating capacity, which in turn influences operating costs and the bottom line. For these reasons, plants have good cause to consider technology that facilitates optimal condenser operation.
In power plants, condensers act as a heat-rejection engine when condensing steam into water. The volume collapse of that conversion (on the order of 1,700 times) causes a significant pressure change, creating a vacuum that pulls steam through the turbine. Because the heat transfer of the condenser drives the back end of the water-steam cycle, the efficiency of that heat exchange is crucial to optimizing the extraction of energy from the steam.
Inefficiencies — caused by a host of issues — can creep into the condenser and lead to:
- Power production losses.
- Higher production costs resulting from higher fuel usage and costs.
- Lower environmental performance from CO₂ emissions.
- Reduced profit margins.
As digital technologies and controls reshape manufacturing and industry, plants of all types are turning to monitoring tools that use data and analytics to solve problems, reduce risks and operate more productively. In line with this trend are technologies that combine in analytics with real-time sensor data from plant assets to help operators identify condenser performance issues such as fouling. By harnessing the power of data related to temperature, pressure, water chemistry and flow velocity, among others, power plants can gain insights into the condition and performance of their condensers. This knowledge can be valuable for making critical operating decisions that impact power output and profitability.
Maximizing Heat Transfer Efficiency
The operation of the condenser sets the stage for the performance of the plant, where relatively small improvements in condenser efficiency can yield significant financial benefits. In some cases, achieving as little as a 2 percent increase in the efficiency of the steam-turbine system can translate to hundreds of thousands of dollars in savings per year (as measured in terms of megawatt output or reduced fuel cost).
With heat transfer being the key process factor, the cleanliness of the condenser plays a major role. Essentially, the cleaner the condenser, the better the cooling, the greater the vacuum and the more efficient the plant.
Fouling of the heat transfer tubes is one of the main culprits that can significantly impede heat transfer in the condenser. Fouling can take on different forms and can be caused by a range of sources. For instance, power plants that use surface water or treated wastewater in their circulating water system may experience biofilm growth if they lack sufficient biological control. If seawater is used, biological macrofouling may result in lost efficiency.
Inorganic scaling also can occur from an incorrect water-chemical balance, leading to deposits such as calcium carbonate or calcium phosphate. If the power plant is near a coal yard or positioned near road traffic, silt or suspended solids could enter through the cooling tower and be deposited in the condenser tubes. Likewise, varying types of debris that get into the cooling tower could become lodged in the condenser tubes.
Similarly, performance issues can contribute to reduced heat transfer. For instance, cracks in the welds of the condenser can cause air ingress and greater backpressure on the turbine. This would result in reduced heat transfer and lower thermal efficiency.
Ultimately, issues related to fouling force power plants to burn more fuel to generate the same amount of energy, pushing their fuel costs higher.
Plants have good cause to invest in technologies that facilitate optimal condenser operation. Source:KrerkkiatStocker / iStock / Getty Images Plus
Data Analytics Tools Can Improve Heat Transfer
With one analytics option to optimize condenser performance, collected data is sent to an analytics engine, where it is filtered to remove noisy data and normalized to negate the impact of process variations such as changes in cooling water flow, inlet temperature or plant load. Subsequently, the data is analyzed using proprietary software models to produce meaningful outputs.
By comparing a plant’s ideal condenser performance against its actual performance, power generation losses can be detected quickly. In such a case, the more data that is fed into an analytics engine, the deeper the insights can be. In addition to several basic process and design inputs, plants can deploy sensors to capture real-time data inputs related to cooling water flow, fuel type, condensate conductivity, air removal rate, condensate dissolved oxygen, inlet/outlet pressures and temperatures. This gives the analytical tool more data to analyze and interpret.
Plant personnel can use the software to drill down to underlying trends and diagnose issues such as the root cause for a performance loss in greater detail. When monitoring thermodynamic performance, for example, detecting a backpressure increase could indicate fouling or air ingress. Spikes in O₂ in the condensate could suggest possible ingress at unit restart points. A decrease in both the ideal and actual cleanliness factor might imply a mechanical failure in performance. The analytics give plant operators the ability to track condenser performance over time based on key indicators and proactively identify opportunities for intervention and optimization.
As power generation moves toward gas and generating energy from waste, where efficiency becomes increasingly important, condenser analytics enable solution providers to become a surrogate member of a power plant’s maintenance team. They can provide technical confidence and insights that can help to continuously optimize the power generation process.
Condenser analytics also can provide plants with insights into the condition of their equipment, providing support teams with action items they can take to protect assets. Prepared with an awareness of emerging issues, plant personnel can be proactive and forward thinking, addressing specific risks before they become expensive problems.
For instance, real-time analytics technology can trigger alarms when certain conditions — a condenser tube leak, for example — that pose the threat of a potential failure are detected, alerting personnel to take corrective measures immediately. Plants also can use sensor data to optimize their operational programs and develop predictive maintenance approaches. These measures can decrease downtime and impact productivity positively.
Digital security must be addressed: Digital condenser analytics raise concerns to the security aspects of accessing a power plant’s confidential data. For obvious reasons, power operations are not open to the idea of allowing outside access to their control systems and data networks. Plants that would like to benefit from condenser analytics software can alleviate these concerns by going with a provider that offers one-way communications from the customer to the solution provider. PC
Condenser Analytics in Action
At InterGen’s Rocksavage power plant, in Cheshire, United Kingdom, digital condenser analytics software is being implemented to help improve performance of the facility’s steam condenser.
The analytics software pulls live data from the plant’s distributed control system (DCS) system as well as online analyzers to monitor and evaluate the conditions of the condenser based on design criteria, fuel type and cost. It then assesses the condenser’s thermodynamic performance as well as the economic and environmental penalties and losses of inefficient operation.
The outputs are visualized in an interactive dashboard that contains design information and a daily-average condenser health report. The thermodynamics dashboard allows users to view multiple performance parameters while the economics dashboard allows users to visualize the financial and environmental impact of operating with varying cleanliness factors (CF).
Utilizing the analytics tool at the Rocksavage site allows the operators to evaluate the performance of the steam surface condenser, validate the effectiveness of chemical treatments vs. actual performance, and make critical decisions concerning the profitability of the power station.
The economics dashboard allows users to visualize the financial and environmental impact of operating with varying cleanliness factors.
The thermodynamics dashboard allows users to view multiple performance parameters.