Colorado Springs Utilities’ Martin Drake power plant faces a number of unique challenges. Situated in downtown Colorado Springs, at the foot of the scenic Pike’s Peak region, the coal-fired plant must meet tight environmental requirements while satisfying growing power demands across the Front Range. As a relatively old facility, Martin Drake also must strive to maintain efficient, cost-effective operations to remain competitive against newer units.
Previously a seven-unit facility, Martin Drake now houses three coal-fired boilers: Unit 5, 46 MW net, online in 1962; Unit 6, 77 MW net, online in 1968; and Unit 7, 131 MW net, online in 1974. Recent performance results are impressive. The equivalent forced outage rate for first quarter 2005 was 0.7 percent; equivalent availability was 98.3 percent; peak equivalent availability was 97.9 percent; and nonfuel O&M production costs were $7.01/MWh.
Coal to the plant comes from the Foidel Creek seam in northern Colorado and from the Powder River Basin in Wyoming. Martin Drake uses a computerized PLC-based blending system to control blend quality in 10 percent increments. “We normally lock into a certain coal blend for each unit,” said Bob Head, Operations Superintendent at Martin Drake. “Typically, we only change the blend if the fuel quality changes.” The plant relies on ultimate analysis results from the mine and on monthly proximate analyses performed in-house to make adjustments and to identify elemental changes (such as a spike in calcium content) that could present operational problems. Recently, Unit 5 was operating on a 40/60 split between PRB and Foidel Creek; Unit 7 was operating on a 25 PRB/75 Foidel Creek split; and Unit 6 was operating on 100 percent Foidel Creek to achieve maximum unit output at 83 MW (gross).
Colorado Springs Utilities operates three coal-fired boilers at its Martin Drake facility in downtown Colorado Springs.
Due to its proximity to Pike’s Peak and the broader Colorado Springs area, particulate control is particularly important at Martin Drake. Originally equipped with electrostatic precipitators, the plant retrofitted baghouses in 1997, 1978, and 1993 (Unit 5, 6 and 7, respectively) to enable the plant to meet its state-imposed opacity limit of 20 percent. For fly ash handling, Martin Drake originally used a settling basin with polymer injection, which proved to be labor intensive for both operations and maintenance. “When we went to a baghouse on Unit 7, we went to a dry fly ash system,” said Head. “The dry system uses vacuum blowers with a separator collector-type system to control dust. Each unit has its own separator collector, but we set it up so they can share unit responsibility for maintenance or long-term outages. Another very positive aspect of the dry fly ash is the opportunity to sell this ash to local concrete companies, which we do. Also, an additional benefit is the water savings.”
To optimize value from unit outages, Martin Drake has adopted a sectionalized outage approach, wherein the plant only focuses on those components in need of performance improvement. “Previously, in an annual eight-week outage, we would look at every section of the turbine, HP, IP, LP,” said Head. “This past Fall, we only inspected and did blade work on the Unit 6 LP section; we did not look at the HP section. One of the main benefits of this approach is that outages are much shorter, which reduces the amount of purchased power needed to replace the lost generation, and of course, it gets our unit back in service faster.” Springs Utilities relies on heat rate changes as well as prior operating and maintenance reports to identify which turbine sections will require outage work. Recent inspection results have identified a likely alignment problem in the Unit 5 turbine/generator rotor, which will be addressed in a Fall 2005 outage.
Although Springs Utilities outsources its main turbine rotor work to third parties, it can perform some significant maintenance in-house. When the original Units 1-4 were dismantled in 1997, Springs Utilities converted the area into a state-of-the-art maintenance shop. “We do our own milling, machining, modifying of parts, and we have our own R-stamp for certified welds,” said Head. “For the LP rotor work in the Fall of 2004, we did all of the case welding, for example.”
Working with utility consulting company Reliability Management Group, Martin Drake recently implemented a three-week planning and scheduling process for needed maintenance activities or operational improvements. The operations crew performs a backlog review over the weekend, and turns in work orders they feel are pertinent to effective plant operation. On Monday morning, the Operations Superintendent and the Maintenance Superintendent review the list and decide what will go into the three-week schedule based on the prioritization description. Load limiting or safety-related work orders have top priority, followed by heat rate and other items directly impacting unit performance (such as sootblowers and cooling tower fans).
In June 2004, crews installed 10,000 condenser tubes to change the plant’s cooling system from potable to non-potable water. The conversion saves an average of 30 million gallons of drinking water each year, a key component of Springs Utilities’ water conservation efforts. The project involved running a new supply line to the plant, building a new storage tank, and installing new lines to each cooling tower. The condenser tubes in Units 6 and 7 were changed from 304 stainless steel to 316 stainless steel because 304 stainless steel tubing can’t handle the chlorine levels expected in the non-potable water. To optimize operation of its cooling water system, Martin Drake is also installing Nalco’s 3D Trasar system, which will control the plant’s chlorine bleach system, tower blowdown valves, polymer injection, corrosion inhibitor injection, and conductivity.
Martin Drake pays close attention to maintaining and reducing overall plant heat rate. The plant relies heavily on General Physics’ EtaPRO real-time heat rate monitor to track performance. “These numbers are always right in front of the operator, reinforcing the importance of heat rate,” said Head. “Also, because the EtaPRO system feeds directly into our PI historian, I can track each crew’s performance.” Head also compares the EtaPRO values stored in the PI historian with the figures calculated by the plant engineers, and they’ve always been within a few hundred Btu/kWh, increasing his confidence in the EtaPRO results.
When Martin Drake installed low-NOx burners several years ago to cut its NOx emissions, it realized the burners would reduce boiler efficiency by about one percent. To recover this loss and ensure optimum NOx control, Springs Utilities installed NeuCo’s CombustionOpt neural network software. “Many companies install neural networks only for their NOx reduction capabilities, but the heat rate reduction capabilities are just as important,” said Head. By controlling variables such as mill temperatures, fan settings, and mill groups as a whole, significant heat rate reductions are possible. Taken together, the EtaPRO and CombustionOpt products have reduced heat rate at Martin Drake by 150 Btu/kWh.
Plant control functions for Martin Drake"s three units have all been combined into a single control room.
A reorganization of Springs Utilities’ operations division in 2005 led to streamlining Drake operations from 49 operators to 32. “We were staffed to run several of our remote, peaking plants out of Martin Drake,” said Head. “We had also become too dependent on the bigger crews, and this was creating a negative and less productive culture.” To drive down costs and stay competitive, Martin Drake went from nine operations staff per crew to six per crew, and the remote plants were staffed separately. “The response has been positive since the right-sizing, and I am seeing more ownership by the operators,” said Head.
Springs Utilities incorporates a “pay for performance” element in its compensation program. This is not an incentive program, stressed Head, but a part of the employees’ pay program. From 1 to 12 percent of an employee’s salary is at-risk based on achieving certain hard and soft targets. Hard targets include items like equivalent forced outage rate, equivalent availability, heat rate and $/MWh. Soft targets include items such as communication skills and diversity training; Head selects several each year to be part of the pay for performance plan.
In 2003, Martin Drake combined control rooms across its three units to streamline and centralize plant operation. The original control rooms were quite unique. The number 1 control room controlled the Unit 5 boiler, turbine, generator and many 34 kV breakers and transformers. The number 2 control room controlled the Unit 6 and 7 boilers, turbines, and generators. Operators were trained on both systems and rotated between the control rooms on a 35-day schedule. For the new combined control room, Springs Utilities employees handled all planning, installation and implementation, resulting in a cost savings of about $4.5 million. “The operators were very involved and the final product was exactly what we wanted without having to negotiate every change with a contractor,” said Head. “We have a strong ownership culture here and our personnel love projects.”
As recent proof of this ownership culture, Martin Drake recently achieved a notable milestone. On July 19, Unit 7 passed the 200-day mark without an outage, an impressive feat for a 30-year old coal unit. p