St. Johns River Power Park

The St. Johns River Power Park (SJRPP) is a large coal-fired electric generating plant featuring two turbine/generators that can each supply 632,000 KW to the transmission grid. The facility is jointly owned by JEA – 80% share, and Florida Power and Light – 20% portion. An additional long term Purchase Power Agreement between the two utilities allows each to share the power output and operating expenses equally as a 50/50 split.

The plant is located on a 1,600 acre site in the northeast section of Jacksonville, Florida. Coal to fuel the plant is supplied primarily from overseas utilizing a ship unloading facility owned and operated by the plant. When operating at maximum capacity the plant consumes approximately 4.5 million tons of coal per year.

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When the plant was constructed in the early 1980’s it represented the largest construction project in Jacksonville’s history. More than 2,200 construction workers were employed during the peak period of 1986. Construction spanned 6 years and the final project cost was $1.45 billion. Unit 1 began commercial production on March 27, 1987. Unit 2 was completed a year later and began its operation on May 27, 1988.

SJRPP represented a departure from normal business practices for both JEA and FPL. At the time the SJRPP project was conceived, both owners depended primarily on fuel oil for their generation requirements. When, in the 1980’s, petroleum prices sky-rocketed those utilities that depended on fuel oil for their generating plants had to increase rates dramatically to pay for their ever-increasing fuel bills. Public dissatisfaction with this trend was substantial. Bold measures were needed to salvage a deteriorating economy.

Coal was the chosen solution. It was, by comparison to fuel oil, an inexpensive alternative. It had a stable price history, was plentiful in the United States and, with the addition of a port facility, was available from abroad. Although the capital investment was substantial the owners decided to move forward with the coal-fired plant.

The decision proved to be a good one. Year after year SJRPP has been a provider of large quantities of affordable and reliable electricity. For many years during this period SJRPP was recognized as the most fully utilized fossil-fired power plant in North America. Having coal-fired generation in their portfolios allowed the Owners to keep electricity rates low and helped promote economic growth and prosperity throughout the region. In keeping with this track record, SJRPP was honored with Power Magazine’s coveted Marmaduke Award for operational excellence in 1997.

Not only has SJRPP been an economic success, it has also been a leader in environmental responsibility. When the plant was built in the 1980’s it came equipped with the then state of the art environmental controls. These controls included low NOx burners to limit the emission of nitric oxides, electrostatic precipitators to remove particulate matter and wet limestone flue gas de-sulfurization (FGD) units to remove sulfur dioxide (SO2) from the flue gas. In addition, a wastewater treatment plant large enough to service a community of 25,000 residents treats all the industrial wastewater from various processes throughout the plant.

Since original construction, environmental regulations have tightened and SJRPP has made the necessary improvements to stay current with the new limits, including two generations of upgrades for the burners as well as various modifications to the FGDs and precipitators. In 2004 a di-basic acid (DBA) injection system was added to further enhance the SO2 removal capability of the FGD systems. In 2009 selective catalytic reactors (SCRs) were placed in service to further reduce NOx emissions. The SCRs were a substantial addition to the plant. The project spanned a four year time period and cost $283 million.

The other area of environmental concern with coal-fired plants is the disposal of solid wastes. Coal contains a certain amount of non-combustible minerals. This is the ash that remains after the coal is burned. It is collected in hoppers beneath the furnaces and precipitators and transported pneumatically to storage silos. SJRPP has partnered with a company, Separations Technologies to process and market this material. The ash is used as aggregate and a pozzuolanic supplement for the production of concrete. This re-cycling effort greatly reduces the amount of ash which is deposited in an on-site protected landfill.

In addition to ash, SJRPP also produces synthetic gypsum as a solid by-product of the FGD process. This material is sold to a local manufacturer, US Gypsum, for the production of wallboard. In a typical year, 200,000 tons of this material is produced.

Points of Interest throughout St. Johns River Power Park

  • Ocean-going vessels can unload coal at the St. Johns River Coal Terminal (SCRCT) located on Blount Island in the St. Johns River. The 30 acre facility includes a dock supporting a 1,500 tons/hr. clamshell-type ship unloader. Each scoop of the bucket removes 23 tons of coal from the ship. The coal is transported to the plant over 3.2 miles of conveyor belts.
  • Up to 800,000 tons of coal can be stored in the SJRPP coal yard. This represents a 65 day supply when both units are operating at maximum capacity. The entire yard is lined with high density polyethylene and all rainwater runoff is treated at the wastewater treatment facility.
  • The plant employs a rotary car dumper to unload coal arriving in railcars. Special railcars with swivel couplings allow the car to be rotated 120 degrees to empty the car into below ground hoppers quickly. A 100 railcar train containing 10,000 tons of coal can be unloaded in approximately four hours.
  • While being transported to the boilers on conveyor belts, the coal passes through a set of coal crushers which reduce the size of the coal to ¼” diameter chunks. The coal is then fed through pulverizers which further reduce the coal to the consistency of talcum powder. The coal is blown into the furnaces with hot air passing through the pulverizers. It ignites at the burners. The flames look like fire created with fuel oil or natural gas.
  • The boilers use this heat to generate steam at a pressure of 2,400 psi and a temperature of 1000 deg. F. The furnace areas of the boilers are 62 ft. wide by 68 ft. deep by 200 ft. high. These open areas are surrounded by vertical tubes which circulate demineralized water and generate the steam. The boilers are hung from massive beams at the top of the boiler structure and expand downward as the boilers heats up. The bottoms of the boilers expand 14 in. downward when at rated temperature. At full capacity each boiler produces 4,900,000 pounds per hour of steam.
  • Each of the plant’s two turbines is supplied with steam from their own single boilers. The steam passes through 20 stages of turbine blades which convert the thermodynamic energy of the steam into mechanical energy. The turbines rotate at 3,600 revolutions per minute. The four sections of the turbine and the attached generator are 152 ft. in total length. At full load each turbine produces nearly one million horsepower.
  • The generators are attached in-line with the turbines and convert the turbine’s mechanical energy into electrical energy. Each generator weighs 390 tons. They are cooled with hydrogen gas for the rotating portions and demineralized water for the stationary stator portions. They each produce 660 megawatts of electricity at 24,000 volts.
  • To minimize electrical losses the current leaving the generators is stepped up in voltage from 24,000 volts to 220,000 volts in the main step-up transformers. At this point a small portion of the power is siphoned off to power the plant equipment. The remaining 632 megawatts from each generator is sent to the switchyard where it enters the grid over five different transmission lines.
  • The steam leaving the last stage of the turbines is turned back into water in the plant’s two condensers. These are large steel boxes filled with small tubes. Cold water is passed through the tubes and the steam on the shell side of the tubes condenses. This rapid change from steam to water creates a near perfect vacuum. Exhausting into a vacuum greatly increases the efficiency of the turbines. The condensed water is recycled back to the boilers to begin the whole process over again.
  • The water cooling the tubes in the condensers comes from the two cooling towers. Perhaps the most prominent feature of the plant when viewed from afar, each tower is 460 ft. high. They are hyperbolic in shape and, at the base, are 370 ft. in diameter. Each tower cools 250,000 gallons per minute of water 20 deg. F. by the process of evaporative cooling.
  • The other, even taller structure on the plant site is the stack. The stack actually contains two individual brick chimneys. The structure is 640 ft. tall and is 78 ft. in diameter at the base. It is supported by a 10 ft. thick concrete foundation. Each chimney is built from 650,000 acid-resistant bricks. A small cage-like elevator is used to access the various platform levels. Platforms extend from the sides of the stack about two-thirds of the way up. These are used when manual stack testing is conducted. The probes used to traverse the diameter of the chimneys are too long to fit within the concrete shell without these extra surfaces. The chimneys are also fitted with continuous emission monitors (CEMs) which constantly measure the levels of SO2, NOx, CO2, CO and the opacity of the flue gas to assure that regulatory limits are being achieved.

SJRPP strives to be a good neighbor in the community, which is why it’s named a “power park” as opposed to simply a “power plant.” SJRPP has invested heavily in state-of-the-art environmental controls to meet or surpass all regulatory requirements. From an esthetics viewpoint, the grounds of the plant have been landscaped and maintained to achieve a park-like environment for the enjoyment of our employees and visitors.

The plant also owns and maintains the E. Dale Joyner Nature Preserve on Pelotes Island. This pristine wilderness area is located adjacent to the plant and proves that a natural habitat can co-exist and even thrive next to a modern industrial facility. Although the Preserve is no longer open to the public, for many years it offered an educational and enjoyable outing for many school children.