The names of the facilities and participants in the cases are missing and the facts have changed, but the lessons remain intact. Some case studies are composed of several projects or events that have taken place over several years.
Steam Turbine Types
- Steam Turbine Components
- Startup and Operation
- Performance Monitoring and Analysis
- Analyzing Performance Data – Corrected Pressures
- Analyzing Performance Data – Flow Function
Shut-off valves are located in the hot reheat line immediately upstream of the IP turbine section. Inspection of the machine indicated that particle erosion had removed significant material from the blades on the HP and IP turbines.
Refresher
Steam Turbine Efficiency
The flow function at the HP turbine inlet (at the throttle valves) changes in this example in the same proportion as the throttle flow (−17.2%). A calculation of Φ at the first stage outlet shows that there is a progression of deposit build-up through the steam path.
Example
For this example, the ratio of the test to design flow function to the stage following the leading stage is 0.694, indicating a reduced flow capability of the second or subsequent stages of the HP turbine. In other words, the deposits should be expected to become larger and larger as the steam passes through the HP turbine.
Case Study Details
Performance Trend
Calculate the corrected first-stage and hot-reheat pressures and determine a likely scenario for the lost output. Use the design and measured conditions to calculate the items below for design and test conditions:.
IP Turbine Enthalpy Drop
Assume that the efficiency of the HP turbine section from first stage to discharge decreases in proportion to the degradation of the overall efficiency of the HP turbine. The IP turbine expansion line is usually drawn as a straight line on the Mollier diagram from the point downstream of the cut-off valves to the junction.
Case Study Findings
As identified earlier, the turbine inlet flow function changed proportionally with the change in throttle flow. As the steam in the HP turbine was slightly overheated for the washes, the first stage did not get the full benefit of the wet steam wash.
Decision Making and Actions .1 Value
Decision Making and Actions – Alternatives
Knowing the cost of leaking seals could help hire an outside expert during turbine reassembly to avoid installation problems and future performance losses. Again, knowing the value of the losses would help determine whether advanced technology pieces would have value and improve the company's returns to shareholders.
Decision Making and Actions – Making a Plan
The field service engineer should record the "as found" and "as left" gasket clearances, which would indicate the quality of the work performed and the condition of the unit after the last overhaul. A fourth option would be for the owner to consider advanced designs to improve the long.
Closure
When presenting information to management, be clear about the objectives and use the time you have wisely. If the meeting is for information only, you may expect new assignments on items you did not expect.
Symbols and Abbreviations
Standard organizations regularly update industry codes; but that is not always the case with practices or guidelines developed within a company. When making a request for help solving a problem or for resources, be specific about the request and show that you have a plan to get things done.
Answer Key
This is not always the case, but future developments may provide additional tools for engineers and manufacturers of pumps, compressors, fans and turbines that can improve their energy efficiency. Engineers should be alert to cases in which observations do not necessarily agree with the practices in their company manuals.
Section 1.3.1, Assignment 1
Section 1.3.2, Assignment 2
Section 1.5.1, Assignment 3
Section 1.5.3, Assignment 4
Improved monitoring of the turbine service provider during maintenance outages would also be a reasonable recommendation. Proposed reviews of actual installations of the newly designed components, which require resources, will be useful support for a management decision.
Case Study
In addition, the maintenance inspection workforce has been assembled and is in the process of conducting site access safety training, which will be completed by the end of the day. In addition, a delay in taking advantage of the high electricity prices in the short term would place the outage during a period of peak prices in the summer, making the decision more difficult.
Background
- Types of Gas Turbine Generating Plants
The output of the steam turbine in these cycles is nominally one third of the output of the gas turbine generator. This configuration improves the economy of scale by reducing the steam cycle cost compared to the gas turbine/HRSG combination.
Gas Turbine Operating Risks
- Gas Turbine Major Maintenance
- Equivalent Fired Hours
- Failure Costs
- Reading Assignment
A Hot Gas Path Inspection (HGPI) includes both the combustion section and the turbine section of the gas turbine. The inspection includes a CI and HGPI, as well as an inspection of the compressor section.
Case Study Evaluations .1 Review
- Presenting Results
- Judgment Calls
- Exercise
- Sensitivities
- Exercise – Sensitivities
- Presentation of Results
Assume there are two methods of arriving at the maintenance interval (MI): a) For the base case, assume the manufacturer has subtracted a small margin (δ) from the actual mean time to failure minus twice the standard deviation (σ). Find the probability of failure at the end of the proposed 3 week run time extension.
Case Study Results
Closure
Answer Key
Section 2.4.5
The downside risks from technical and commercial assumptions can easily overwhelm the projected base gain of just $2.5 million. Taking into account the other downside risks associated with the workforce, there are several factors that could lead to a decision to take the HGPI outage as planned.
Background
- Gas Turbine Types
- Gas Compressor Fouling and Cleaning
- Exercise 1
- Inlet Filtration
- Gas Turbine Performance Measurement
Since the power of the gas turbine is proportional to the amount of air, even small amounts of deposits on the compressor blades will have a noticeable effect on the power of the machine. The output of a gas turbine is approximately proportional to the mass flow rate through the machine.
Case Study Details
- Derivative of the Cost Function
- Exercise 2
- Linear Programming
- New Methods – New Thinking
- Exercise 3: Gas Turbine Inlet Filtration Upgrade
- Presenting Results
From either method, it is clear that the frequency of water flushing is only a function of the rate of change in output due to compressor fouling. A presentation of the results of this case-study analysis can be condensed into a few important points.
Case Study Results / Closure
Once the topics are clearly presented, your company will have the opportunity to propose working with the client to complete one or both of the alternatives. In the first year of operation with upgraded filters, we stopped online and offline washing of compressors.
Symbols and Abbreviations
Answer Key
A sample of the spreadsheet calculation used to calculate the net present value of the filter installation and savings is shown in Figure 3.11. One method of determining the power level of the reactor core is the continuous measurement of the thermal input to the steam power cycle – steam calorimetry.
Background
- Nuclear Steam Power Cycles
- Core Power-Level Measurement
- Differential Pressure Flow Measurement Devices
- Two-Phase Piping Pressure Drop
- Uncertainty
Reheat improves cycle efficiency and reduces moisture in the final stages of the LP turbine. Another feature of the primary reactor cooling loop in the PWR is the charging system – not shown in Figure 4.2.
Case Study Details
After factory approval of the reactor cooling system components, the uncertainty of the input to the steam calorimetry calculation is assumed to be ±5%. The data are summarized below for the three elements labeled 1, 2, and 3 for one of the two reactors at the site.
Exercises
- Uncertainty
- Conclusions
This can be an exhausting exercise, especially in the case of measuring steam flow. Another option is to perform a Monte Carlo simulation using a random number generator to determine the range of uncertainty.
Closure
Symbols and Abbreviations
Answer Key
Section 4.3
Consecutive states or events BD: SGU blowdown. i: sequence as in first, second and third SGU FW: feed water in SGU. There are three possible uncertainties that contribute to the SGU outlet pressure measurement, including: pressure measurement behind the flow nozzle, pressure loss in the flow nozzle, and pressure losses in the pipeline between the SGU outlet and the flow nozzle.
Section 4.3.1, Monte Carlo simulation
Further Reading
Background
- Reading Assignment
- Müller-Steinhagen and Heck
- Void Fraction
- Pumping Net Positive Suction Head Required
- Projects
The study and determination of the two-phase flow regime is as varied as that of frictional pressure loss. Coefficients of resistance for valves and fittings are available from a number of resources on the Internet - The Engineering Toolbox (http://www.engineeringtoolbox.com/) and pump companies, for example. 2005) is also an excellent resource for elbows, tees, extensions, and reducers.
Case Study Details
In this study, you received the process design from the PFD along with the flow properties as calculated by the process design engineer. In collaboration with the piping designer, you developed an isometric sketch of the reboiler inlet and outlet piping, presented in Figure 5.5.
Exercises
- Liquid Flow to Reboiler
- Two-Phase Flow from Reboiler
- Pump Suction
- Discuss
Two-phase friction pressure gradient MSH (5.1) and total pressure loss due to friction in the two-phase return lines to the tower with a 20% margin. The height of the center line of the reboiler so that the pressure leaving the two-phase line is equal to the pressure entering the liquid line from the tower.
Closure
The engineer must develop the calculation and two-phase pressure loss correlations based on a document provided by the customer.
Symbols and Abbreviations
Answer Key
Stakeholders in the project include the national government, the local porter, local communities, shipping companies, LNG suppliers and natural gas customers. From reservoir pressure, natural gas must be compressed to approximately 6.9 MPa to meet pipeline requirements.
Background
- Models
- Availability: Planned and Unplanned Outages – Parallel Systems
- Series and Parallel Processes
- Stochastic Models
- Reading
- Applicability
For example, when calculating the probability of a forced failure of the parallel components of Process 2 in Figure 6.4 using equation (6.7), the planned and unplanned failure rates of Processes 1 and 3 must also be subtracted. Suppose the planned failure rate of the components in Figure 6-5 is 6% and the forced failure rate is 3%.
Case Study Details
- Initial Block Flow Diagram
- Business Structure
- Modified Block Flow Diagram
- Other Considerations
- Exercises
To perform a steam turbine maintenance outage, a complete shutdown of the CHP plant was required to isolate the steam turbine from the condenser. Neglecting the sixth year of operation, which includes a steam turbine failure, calculate the following for the gas turbine / HRSG block:. a) The effective forced outage rate for one gas turbine / HRSG train.
Closure
Determine the percentage of power output and heat input for the scenarios described in points 1b. Write a Visual Basic program for a Monte Carlo analysis of the expected power and heat availability from the CHP plant for years 1 through 5.
Symbols and Abbreviations
Comment on the need to consider simultaneous forced outages and forced outages during the gas turbine's major maintenance periods.
Answer Key
D 3. True
Section 6.2.5 (a) 3.97%
- Background
- Cogeneration or CHP
- Environmental Considerations
- Efficiency
- Case Study Details .1 General
- Proposed CHP Plant
- Steam Boilers
- Fuel
- Gas Turbine
- Refresher
- Gas Mixture Molecular Weight
- Gas Mixture Heating Value
- Species Weight Fraction
- Ultimate Analysis
- Objective
- Exercises
- Outside Reading
- Boiler Operation
- Cogeneration Plant
- Conclusion
- Closure
- Symbols and Abbreviations
- Answer Key
- Background
- Dispatch and Renewable Power Resources
- Capacity Factor and Availability Factor
- Fuel Costs (FC in Equation (8.1))
- Capital Cost Recovery (CR in Equation (8.1))
- Nonfuel Operations and Maintenance (M in Equation (8.1))
- Regulation and Government Support
- Refresher
- Short-Run Marginal Cost
- CO 2 Emissions
- Long-Run Marginal Cost
- Case Study Details
- Reading Assignment
- Transmission Costs
- Economic Models
- Carbon Emissions
- Understanding the Findings
- Explaining the Results
- Closure
- Answer Key
Determine the energy value of the HP and MP steam delivered to the refinery using the mean ambient temperature for the reference condition. Different power generation technologies are often compared using the levelized cost of electricity (LCOE), or levelized cost of energy – the ratio of the lifetime cost of building and operating the facility to the lifetime energy production.
Section 8.3.1: Data Provided by EIA (Energy Information Administration, 2013: Table 1) is shown in Table 8.5
Estimates showed a 29% increase in the short-term marginal cost of natural gas-fired combined cycle generation as a result of a GHG emissions tax of $40/te. To achieve greater reductions in GHG emissions, the percentage of wind in the generation mix would need to be large enough to replace coal generation, which had a lower short-term marginal cost than natural gas.
Section 8.3.3: Economic Model Results with Stacked Bar Chart Shown in Figure 8.2 Wind
Section 8.3.4: Carbon Emissions 1
- Background
- Steam Surface Condensers
- Feedwater Heaters
- Overall Heat Transfer Coefficient
- Condensing Heat Transfer
- Forced Convection Inside Tubes
- Conduction Heat Transfer
- Off-Design Exchanger Performance
- Drain Line Sizing
- Reading
- Case Study Details
- Flow Diagram and Equipment
- Design Cases
- Exercises
Condensed steam and cascade drain exit the exchanger shell and are directed to the condenser at the steam turbine discharge. Lower-pressure shell-side water heaters are often located at the "neck" of the condenser—the transition zone between the steam turbine discharge and the condenser tube.
Application of Engineering Fundamentals
To ensure that a design is appropriate for all conditions, the owner (buyer) and engineer begin the design process by defining a set of design cases. For this case study, it is assumed that the design should be sufficient for 102% of the approved reactor power.
What happened to cause the winter time problems?”
The author suggests introducing the feedwater heater's drain enthalpy as a constant in equation (9.1) to keep the objective search function stable. Calculate the Froude number at the wintertime conditions using the pipe diameter chosen in 1.
Client Interface
- Closure
- Symbols and Abbreviations
- Answer Key
The client accepted the offer and developed a strong relationship with the engineer, and the firm made a profit on the equipment, materials and installation of the new design. In this study, the engineer suggested pumping the fifth extraction heater drain before the heater into the feedwater system.
Section 9.3.3 Part 1
- Background
- Maintenance Practices
- Economic Model for Maintenance
- Operating Costs other than Maintenance
- Refresher
- Cost to Generate Power
- Fixed and Variable Operations and Maintenance (O&M)
- Cost of Fuel
- Short‐Run Gross Margin
- Presentation Techniques .1 Waterfall Chart
- Line and Scatter Plots
- Reading
- Questions
- Case Study Details .1 Data
- Exercises
Condition-based maintenance (CBM) is a flexible maintenance regime based on measurements of the condition of a component, unit of equipment or system. The next row of the table has a value for the hidden series equal to the sum of columns B and C of the previous row (row 4).
Setup
Calculate the short-run marginal cost of producing power immediately after a major overhaul and the gross revenue from power sales at the annual average power price, ignoring fixed operating and maintenance costs in $/MWh. Neglecting inflation and the discount rate, we calculate short-run marginal costs using the results of 6.
Maintenance Optimization
Calculate the short-run marginal cost of electricity production immediately after the major overhaul and the gross earnings from the sale of electricity at the annual average price of electricity, ignoring fixed operating and maintenance costs in $/MWh. Short-run marginal cost includes only variable operating and maintenance costs.). Calculate the changes in heat rate and power output after 7.5 months due to changes in HP and LP turbine efficiency and input stream function.
Capital Improvements
- Closure
- Symbols and Abbreviations
- Answer Key
Create a "waterfall" map showing the impact on heat rate and output due to HP, and LP turbine efficiency, and the inlet flow function. The cost due to performance losses is significant compared to the cost of normal major maintenance, or equipment overhauls.
Section 10.4.1: Reading
Section 10.5.2: Exercises Part 1: setup
