The cost of replacing or repairing a valve is small compared to the cost of
lost heat-rate efficiency in power plants caused by leaking valves. Minor
leaks will grow to major leakage, causing frequent equipment repair or
replacement and costly unscheduled plant shutdowns. Valves can have
severe leakage that is not visible to the eye as internal valve leakage can
go undetected for long periods of time.
Superior cycle Isolation testing services provide the decision-making tools necessary to avoid unnecessary repairs and prioritize the higher value items. ValvTechnologies’ ValvPerformance Testing™ program provides innovative solutions for efficiently maintaining valve populations and solving valve leakage problems.
Overall Reductions in Operations and Maintenance Spend
Energy losses attributable to poor steam/water cycle isolation valves in power generation applications can add up to three or more percent in total unit heat rate (efficiency) losses. ValvTechnologies’ Ultrasonic Emission Testing program enables an inexpensive, rapid recovery of lost generation with minimal effort and without interruptions to plant operation.
The underlying theory is simple: a leaking isolation valve is releasing energy and the ultrasonic emissions or noise levels coming from that valve can proxy the rate of energy release (i.e. the flow rate). ValvTechnologies takes that premise to the next level and beyond. Using knowledge-based software, ValvTechnologies is able to correlate the noise or ultrasonic emissions from a subject valve to a vast database of valves with known, laboratory-verified leakage rates.
By interpolating among multiple variables including acoustics, valve size, type and class, fluid and the upstream and downstream pressure and temperature conditions, the software returns a mass flow rate of leakage. This is based on the premise that an identical valve, leaking under identical conditions will produce identical acoustic signatures in a laboratory, as it does in a power plant.
Get your Noise Signature™, just as everyone has a unique written signature, so every leaking valve has a unique Noise Signature™ no two are the same, especially since there are so many different valve shapes and sizes. The acoustic emissions measured with our ultrasonic equipment are specific to each individual valve, just as your signature is unique to you. The acoustic readings, taken together, are the specific Noise Signature™ for that individual valve.
Accurate, Quantitative Results
After determining the rate of leakage, ValvTechnologies then calculates the corresponding energy losses and the overall effect of those losses on plant operating economics for each individual valve.
Referring to the table below, the process has been third-party verified for accuracy. On populations of valves, the process has demonstrated to be within 4% of the laboratory-verified leakage rate and within 10% over two standard deviations.
ValvTechnologies reports efficiency losses based on fuel consumption and fuel costs. This is qualified as the minimum expected benefit. In the vast majority of cases, more heat or energy cannot be added to the power cycle to account for valve leakage related losses; consequently valve leakage will also have an effect on plant generating output (MWHRs). The total extent or impact of a leaking valve depends on the location of the valve in the cycle and the thermal or equipment capacity constraints of the individual unit.
The solution has been tested accurate and ValvTechnologies clients have seen the results in the control room. A minimal investment in effective steam cycle isolation can yield dramatic improvements in plant operating profit.
The value of cycle isolation testing is not limited to the recovery of energy.
Additional benefits include:
- Reductions in cycle make-up requirements
- Protection of other plant equipment from unnecessary heat loads or water induction problems
- Verification of warranties and guarantees of valves in place
- Confirmation that plant equipment can be isolated for repairs
- The general transparency necessary to make more informed decisions
Improvements in plant efficiencies correspond to a reduction in environmental toxins and pollutants. Every pound of coal saved with an assumed Carbon content of 75% by weight results in 2.75 pounds less CO2 emitted to the atmosphere.
ValvTechnologies has a wide experience in zero leakage, severe service isolation valve solutions for the fossil power, nuclear generation, oil & gas, heavy oil, refining, petrochemical, mining and minerals, pulp and paper sectors.
Do you have any questions regarding Valve Leakage Problems or Maintenance?