At some plants these activities are carried out by one or more personnel whose primary responsibility is the maintenance of these statistics. (This is not to say that all departments are not involved in the collection of data, only that all data is eventually supplied to one organization.) At other plants, these responsibilities are spread out over various persons (and sometimes various departments), and the collection and maintenance of this data is only part of their responsibilities. Either method can be successful. However, when data collection/maintenance is a secondary function, frequently, it is not given the attention that it requires. When this happens, critical information can be lost, or worse it may be corrupted. This can lead to wrong conclusions and actions.
Another advantage of having an individual or small organization responsible for all data is that relationships between bits of information can be seen and used to validate data. For example, if one organization keeps up with the availability statistics, and another organization keeps up with equipment tag out records, then the first organization might not know about all the equipment worked on during an outage or derating.
7.2.2Technician
A job category that is often missing from Indian utilities is that of a "technician." This classification covers skilled labor that pentbrms many of the heat rate improvement related activities, such as:
Setting up test instruments, and collecting data.
Condenser air inleakage leak detection.
Coal and ash sampling.
Coal analysis (proximate, ultimate, ash fusion, grindability, fineness, etc.).
Cycle isolation surveys.
Infrared scans (boiler casing, etc.).
Vibration data collection.
Oil sampling and analysis.
Most of the Indian plants that were visited in this project have some laboratory personnel performing some of these functions, but frequently some of these tasks are performed by unskilled labor under the direction of an engineer or manager. There are problems usiig unskilled labor, even under the direction of experienced engineers:
Many tasks, such as pulverizer testing, require close coordination between personnel, and precise movements of equipment in order to get accurate results. Obtaining repeatable results from this type of work requires a highly skilled crew, who are familiar with the plant equipment, familiar with the test equipment, and can work together as a cohesive team.
There are safety concerns, as persons who are not familiar with the equipment are likely to get hurt.
A better solution, that would result in quicker tests and more accurate results, would be to set up a group of personnel, and train them to perform these tasks.
7.2.3 Engineer
At some plants, one or more engineers is designated as the "Heat Rate" or "Performance" engineer. At other plants, all engineers are theoretically responsible for heat rate activities in their areas of responsibility. Either of these approaches can work. Some of the heat rate related hnctions of the plant engineers include:
Reviewing the unit performance each day, including the control charts/trend charts of the "primary process indicators" (see Section 2), and where deviations are noted, assisting with determining the root cause and best course of action to restore optimum performance.
Reviewing the heat rate losses, comparing current operation to both "target values" (for how well is the current operation) and also to "expected values"(1ooking for opportunities for long term improvements)
Test Program. Usually the engineers are responsible for the plant's test program including developing detailed test procedures, determining test schedules (when various performance tests such as condenser performance or pulverizer fineness should be done), ensuring that the tests are carried out properly, reviewing results, and recommending corrective actions as necessary.
Heat Rate Action Plan (HRAP). Engineers usually are responsible for much of the HRAP (See Section 5). They recommend activities to be placed in the "Heat Rate Improvement Plan", monitor progress of approved activities, review results to see if the desired results are obtained (and if not, why not).
7.2.4Maintenance Responsibilities
There are several activities that must be carried out by the maintenance department. This includes both routine activities, that are done on a schedule, and activities that are performed on an asneeded basis. The level of staffing in the maintenance department should be sufficient to perform these activities.
Some of the routine activities that are required, but often get dropped due to time/manpower constraintsinclude :
7.2.4.1 Calibration of Coal Weighing Equipment
The equipment used to measure the quantity of he1 burned must be regularly maintained. This could be batch coal scales, volumetric feeders, gravimetric feeders, or belt scales. All of these devices require periodic maintenance and adjustments to keep the indicated weights accurate.
7.2.4.2 Instrument Calibration
A frequent cause of heat rate losses is inaccurate instrumentation. Full loop calibrations should be performed on a fiequent basis for critical measurements, such as throttle temperature and boiler outlet 02.
7.2.4.3 Pulverizer Maintenance
Another common area where heat rate losses occur is in the fuel supply system. Too often, personnel take the attitude that if the pulverizer is running and grinding coal, all is well. However, if the skirt has holes, the grinding pressure is not correct, fuel line orifices are worn, etc., there will be efficiency losses. A detailed preventative maintenance program that includes performance issues should be in place at every plant.
7.2.4.3 Condenser Maintenance
One piece of equipment that is often overlooked is the steam condenser. Because of this, it frequently is the source of the highest heat rate deviations. Most condensers should be cleaned several times during the year, not just once a year during outages. With the proper equipment, (which is relatively inexpensive), condenser tube cleanliness can be maintained at a high level, improving not only heat rate, but also generation.
7.3Corporate Departments
There are several heat rate related activities that are typically handled, at least partly, by the corporate staff.
7.3.1 Corporate Heat Rate Group
In most corporate offices, there is a staff whose primary function is overall administration of all heat rate improvement activities. This includes both assisting the plants' staff with their efficiency improvement activities, and monitoring the performance of all units in the system while looking for potential improvements.
One function of this group is to set minimum standards (each plant may expand these minimum requirements as they see fit) for various activities, such as procedures for collection, filtering, reduction, storage and retrieval of data. For example, they would set a corporate standard for the minimum ash sampling frequency, or develop a list of the minimum points that should be control charted or trend charted (see Section 2). This group would also set the minimum information that should be included in each unit's Heat Rate Action Plan, and minimum tracking requirements.
A second typical responsibility of this staff is assisting the plants' staff with developing and maintaining the expected level curves, heat rate correction curves, s o h a r e , etc., necessary for
calculating heat rate deviations (see Section 3). From the utility perspective, it is important that all units be held to similar "expected" levels and that heat rate deviations be calculated in a uniform manner. If this is done, then comparisons between dissimilar units can be made, and resources (manpower and money) can be applied where the most benefits will result. Another result of having all units' heat rate deviations calculated in a similar manner, is that not only can individual units' losses be "rolled-up" to plant values, but they can also be rolled-up to system values. These system roll-ups are a responsibility of the corporate staff. Then questions such as "Which unit in the system has the most potential for improving the system heat rate (and reducing the system cost) from a high pressure turbine overhaul?" or "How much money can the system save if the system's heat rate deviation due to high condenser pressure is reduced by half?" Unless every unit in the utility is using "expected levels" developed the same way, these types of comparisons are not possible, or will not be correct.
Another responsibility that is usually assigned to the corporate staff is to maintain thermodynamic models of each cycle in the utility (turbine and in some cases boiler). This is not to say that the plant staff cannot build or use these models, only that the corporate staff usually has one or two "experts" in this field who assist the plant's personnel. Due to the complexity of these models, unless a person works with them frequently, it is difficult to stay proficient, and most individual plants do not need to work with the models often enough to maintain a high level of skill.
A very important fbnction is to assist the plants' stafTwith analyzing the trend/control charts and heat rate deviations. When problems arise, both groups work together to determine the root cause of the problem, and to determine the best solution. Once a course of action is identified, that activity is added to the Heat Rate Action Plan" (see Section 5), along with the schedule for implementation and other related information.
Another fbnction is to help disseminate information between the plants in the utility. If one plant has a problem, the corporate staff should be aware if similar problems have occurred at other plants, and what actions were taken there. Also, if one plant tries something new (equipment, operating procedure, maintenance procedure, etc.) the corporate staff should make the other plants aware of the results where they could be applicable. One way they sometimes do this is to organize short workshops/conferences where the personnel involved in heat rate improvement from each plant can meet and exchange ideas.
7.3.2 Corporate Test Group
Section 4 discusses the details of various types of performance tests that can be used not only to determine equipment condition, but also to help diagnose the cause of deterioration. Some utilities do all their performance testing with a corporate test staff. Other utilities perform all performance testing with the plant staff. Many utilities have both, a corporate test staff for large and contract tests, and each plant having some personnel and equipment for running smaller performance tests.
There are three reasons for having some testing capability at each plant. First, having a group of people at each plant that are trained in performance testing enables the plant to be able to run most types of tests at any time. Second, it allows the test schedule to quickly change as unit conditions change. (For example, if the corporate test crew is at a unit to run a turbine test, but the control valves cannot be fblly opened for several days, they cannot move to another type of test as easily, if at all, as the plant crew.) Third, if all necessary testing were performed by the corporate crew, the cost (travel time, meals, lodging, etc.) becomes excessive. However, there are also drawbacks to splitting the responsibility for testing. First, it can be difficult to maintain a qualified test crew at each plant. At any plant, certain tests may not be run very often. Also, the plant personnel running performance tests may have other duties as well, therefore, these people may not be as experienced as a full time corporate test crew would be. This can lead to poor quality tests. The second drawback is that some equipment, which can be expensive to purchase and maintain, must be obtained for each plant, and since many tests are not run frequently, the equipment is under utilized. Each utility weighs these factors and decides how to best obtain the necessary test results.
Major tests, such as fbll turbine cycle heat rate or boiler optimization tests, where a large number of instruments are required, are almost always carried out by the corporate test crew. As a minimum, a turbine cycle heat rate test should be done before (approximately one year) and immediately afler outages where the turbines are inspected. By testing one year before the outage, the results of the test can be used to determine the work scope. Boiler optimization tests are usually carried out any time there is a major change to the boiler cycle. Typical activities that would trigger these tests include changes to the boiler heat transfer area, significant fbel changes, etc.
The corporate group also has the capability of running smaller tests, such as enthalpy drop turbine efficiency, clean and dirty air tests, fan tests, etc. Even at utilities where each plant has a test group, the corporate group is sometimes called in to assist with special tests, train plant personnel, confirm results, or to catch-up if the plant group gets behind.
Another function of the corporate test group is to stay aware of new developments in test equipment and procedures, not only for themselves, but also to pass on this information to the plants' staE
This group would include both engineers and test technicians. Some test groups also include instrument technicians to assist in maintaining/calibrating test equipment and installation work. All personnel should have completed the qualification cards for the equipment they use and for the types of tests they run. (see Appendix G)
A side benefit of a corporate test group is that they are frequently used as a training unit for new engineers. There are several reasons for temporarily assigning new engineers to this group:
It provides training in several systems (boiler, turbine, condensate, feedwater, etc.)
It provides training not only on the mechanical side of the systems, but also on the controls and instrumentation and power measurements.
It provides training at several plants, where the new engineer can be exposed to various designs, control systems, operating practices, etc., and meet personnel at several plants for hture contacts.
The new engineers are made aware of the importance of thermal efficiency.
7.3.3 Corporate Laboratory
Most utilities have a large amount of test equipment, coal analysis equipment, etc. Most plants have personnel who can maintain and calibrate most equipment, but usually some equipment requires special attention, such as high accuracy test equipment. Also, it is not economically feasible to purchase some infrequently used, special purpose equipment for each plant. Some utilities contract these special laboratory services. Other utilities have an internal laboratory. Advantages of an in-house laboratory include better quality control and reduced turnaround time. These advantages must be weighed against the initial cost of obtaining the equipment and skilled personnel. This laboratory may perform one or more of the following hnctions:
Check of new equipment to ensure that it meets specifications(such as test equipment) Calibration and I or repair of measuring and test equipment
*Pressure, temperature, flow, mass and electrical
*Chemical meters (pH, Conductivity, etc.)
Oil Analysis
*Fuel oils
*Insulating oils
*Lubricating oils Coal 1ash analysis
*Proximate
*Ultimate
*Ash chemistry
*Ash fbsion Metallurgical
*Failure analysis
*Metallography
*Mechanical tests
*Chemical tests
7.3.4Corporate Controls Tuning Group
Another specialized skill is the ability to "tune" modern control systems. With advanced digital control systems, the control of a single parameter (such as steam temperature) may be a hnction of more than twenty inputs. Tuning these highly complex and intertwined control loops so that the unit operates smoothly and efficiently at all loads and during load changes requires a great amount of knowledge and skill (usually learned through trial and error over several years of on-
the-job-training). Because this fbnction is not required frequently at an individual plant, it is usually assigned to a small corporate group, who specialize in this area, or it is contracted out.
7.4Training
Training is a never ending activity. This is especially true of technical fields where new equipment, techniques and programs are continually being developed. Because of this, and the fact that power plants are such complex systems, no one is ever hlly trained and there is always more to learn in any field. The training that a person needs depends on the work that he is expected to perform. There is some overlap, in that many training programs apply to several different job categories. For example, since heat rate is everyone's responsibility, all plant personnel should have some basic training on heat rate. Other training is specific to particular jobs. For example, the skills and need in-depth knowledge to properly tune a distributed control system is required by only a few personnel, and only the test crew needs to be hlly trained in the proper use of a high velocity thermocouple (HVT) probe. (It is probably advantageous that many persons have some cursory knowledge of these activities, but everyone cannot be hlly trained to perform all fbnctions.)
There are several sources for training. There are vendors available to teach all the courses discussed here. However, in order to keep the cost to a minimum, frequently these courses are taught by the utility's own personnel. One advantage of this is that the course can be made specific to the equipment and procedures at each plant. Another advantage is that this allows more flexibility in the scheduling. A potential drawback is frequently the persons who are most knowledgeable in an area, are not trained to be teachers. However, usually with some training and practice, a utility's expert can be utilized to effectively pass on their expertise. A third method of instruction that is gaining in popularity is computer based training (CBT). In this method, lessons are available on a computer. Frequently, the lesson includes tests and feedback of results, and even remedial lessons are available. An advantage of this is that the student can take these courses when he has available time. A drawback is that "live" instructors and classes usually generate more interest and exchange of ideas than CBT.
The following sections (7.4.1 - 7.4.6) describe some of the heat rate related training typically provided to power plant personnel.
7.4.1 Plant Systems Overview
Frequently, as part of all new employee's orientation, there is a short training course on each of the systems in a power plant (i.e., feedwater, coal handling, power transmission, etc.). Included in this course are:
Basics of fluid flow, thermodynamics, heat transfer, AC power
Turbines, pumps, fans, valves,
Condenserslcirculating water system
Condensate system
Feedwater system
Water chemistry and treatment
Steam generation
Instrumentation& control systems
Electrical power generation
Electrical power distribution
This type of course is taught different ways. At some plants, this course is taught all at once over a week or more, at other plants, it may be taught one hour a day for several months. Some utilities have much of this material available on computer based training (CBT) where employees can take lessons as their schedule allows.
7.4.2 Basic Thermal Performance
Individuals whose job fbnctions can directly affect the efficiency of the unit are frequently given additional training on heat rate fundamentals, with emphasis on how heat rate is measured, and how it is affected (positively and negatively). This course usually places more emphasis on practical aspects of heat rate improvement with lots of examples of how operators, maintenance personnel, equipment modifications, changes to control loops, etc., can affect the efficiency of the unit, with a minimal amount of basic mathematics and theory. This course is strongly recommended, not only for engineers, but also for operations personnel and maintenance supervisors. Included in this course are:
What is heat rate, and how is it measured.
How are losses measured, and an explanation of expected levels and target levels. "Rules of thumb" - costs of typical heat rate losses
Turbine cycle
*Turbine performance
*Condenser performance
*Feedwater heater performance
*Cycle isolation and auxiliary steam usage Boilercycle
*Pulverizers
*Air heaters and air preheaters
*Factors affecting combustion and heat transfer
Turbine & boiler Interactions
*FWH out of service affecting steam flow through reheater
*Final FW temperature affect on firing
*Steam extraction for air preheating coils
*Attemperation
Auxiliary Power Usage
7.4.3 Advanced Thermal Performance
A third course on advanced thermal performance is recommended for personnel who are deeply involved in heat rate improvement, but after they have had some experience in this field. This course is similar to the basic course, but more in depth. It includes:
*Emphasis and examples on how to work through logic or structure trees to determine the root cause of performance deterioration
*Boiler optimizationtesting
*Details of how heat balances are generated (manually and computer programs).
*Details on other calculations (how heat rate correction factors are developed, how boiler losses are calculated, pump affinity laws, etc.)
*Examples of interaction of various effects (i.e., how damage in the turbine can affect final feedwater temperature), etc.
7.4.4Turbine & Boiler Modeling
A course that is very valuable is on thermodynamic modeling. One of the most usefbl tools available to help performance engineers is computer software for modeling the turbine and or boiler cycle of a power plant. This allows the engineer to quickly analyze test data, generate heat rate correction factors, and evaluate proposed equipment or controls modifications, and other "what if" analysis. These courses are usually taught by representatives from the software vendor, although there are third party vendors.
7.4.5 Equipment 1Systems
A usefbl source of continuing education is advanced courses and workshops on various equipment and systems. Courses on turbines, pumps, valves, condensers, feedwater heaters, pulverizers, air heaters, boiler optimization, etc., are available from several sources. Some manufactures offer courses on their equipment, which go into detail on operation and maintenance practices. Universities, retired utility and OEM personnel, engineering societies such as ASME, and other third parties, also offer valuable courses. These courses are very useful for helping engineers gain a better, more in-depth knowledge of specific areas. They also help keep personnel aware of new equipment and techniques.
7.4.6 Testing
For those persons involved in performance testing, specialized training is required covering several areas including:
The use of equipment (such as pitot tubes, coal sampling equipment, helium leak detection, etc.)
How to set-up both the equipment and the unit for each type of test.
Calculation procedures (which may be manual or computer based)
How to interpret the results, and recommend corrective actions.
This training can include both class room and field work. In addition, the use of "Qualification Cards" ensures that the personnel handling equipment and running tests are trained. Appendix G lists some of the qualification cards and includes an example of an "Equipment" card and a "Test" card. Equipment cards are specific to a piece of equipment, and frequently are specific to a particular manufacturer and, in some cases, even a particular model. (Because the procedure for. handling different models can vary, a qualification card is needed for each model.)
Before a person is "signed-off' on an "Equipment" card, he must demonstrate his ability to properly use the equipment (including any routine calibration and maintenance that it requires), and must have demonstrated his knowledge of the safety and technical aspects of the equipment (under what conditions the equipment can be used, potential problems, limitations, etc.).
Before a person is "signed-off7on a "Test" card, he must demonstrate his ability to lead a crew in running that test. This includes properly setting-up all necessary equipment, setting the unit conditions, collecting the data, calculating the results, analyzing the results, and recommending corrective action.