Brazilian unbiased energy generator Epasa confronted important environmental and operational challenges with heavy gas oil sludge. By means of progressive engineering and problem-solving, the corporate developed a state-of-the-art two-stage de-watering and de-oiling course of that transforms sludge into reusable assets.
For practically a decade after Centrais Elétricas de Paraíba—or Epasa—started industrial operation of its Termonordeste and Termoparaíba vegetation in 2010, the Brazilian unbiased energy producer grappled with the twin tasks of offering thermal energy for reliability whereas addressing its shareholders’ environmental issues. The 2 energy vegetation close to João Pessoa, a dynamic coastal metropolis on Brazil’s japanese tip, contribute a mixed capability of 342 MW, making them collectively the second-largest gas oil thermoelectric complicated in Brazil and among the many high 5 largest on the planet. As Epasa Plant Supervisor Marcelo Agra Junior defined to POWER, the services are outfitted with 40 engines from MAN Vitality Options, together with 38 MAN/STX 18V32/40 motors with a producing capability of 8.76 MW every and 02 MAN/STX 9L32/40 motor able to 4.38 MW. EPASA makes use of OCB1, a low-sulfur content material heavy gas oil, to gas its operations.
Whereas Brazil now depends on renewables—primarily hydropower—for 80% of its technology capability, the vegetation play a pivotal position as a standby useful resource when reservoir ranges at Brazil’s hydropower services are low, Agra stated. Nevertheless, the thermoelectric’s environmental posture has come underneath sharp reduction lately, owing partly to a societal embrace of decarbonization and a sustainability push by Epasa’s two shareholders—CPFL Energia, Brazil’s second-largest transmission and distribution firm, and EBRAZIL, a thermoelectric energy large in Brazil. “So, we focus quite a bit on mitigating our environmental affect as a lot as doable, [mainly] by mitigating our productive course of and our impacts on the area people,” he stated.
For years, Epasa’s most vital environmental impacts got here from guaranteeing its HFO was adequately purified, a step important to guard and prolong the lifetime of its engines. Impurities in HFO can result in important put on and tear, operational inefficiencies, and even failures. To purify its uncooked HFO, Epasa had used centrifugal separators manufactured by German agency GEA and Swedish firm Alfa Laval. Centrifugal separators purify HFO by quickly rotating the oil to generate centrifugal pressure, separating the denser impurities and water from the oil, effectively clarifying the oil to be used in engines and mills.
Centrifugal separators, nevertheless, produce sludge, a concentrated mass that’s usually composed of separated impurities and water, which will get entrapped with the strong particles through the separation course of. At Epasa, which makes use of 1,600 tonnes of HFO each day when it’s producing at whole capability, sludge beneficiation had shortly grown into an crucial.
“Usually, our sludge composition is 80% of water and 20% of oil,” Agra defined. Earlier than, Epasa would truck out the sludge to a 3rd celebration for therapy, with the recovered oil going to business, he stated.
“So, think about the amount of vans that we would have liked to ship this sludge—which is principally water—to a 3rd celebration to deal with.” Agra famous that the observe was each costly and environmentally averse.
Treating Sludge In-Home
In 2019, Epasa’s inside engineering departments proposed an bold answer to deal with the sludge in-house. “The pillars that we envisioned have been to make use of the sludge as a lot as doable in our course of, to deal with the water in compliance with the Brazilian environmental laws, after which to make sure, by way of 24/7 supervision, to deal with the water, abiding by legislative limits in order that we may return it to rivers.”
Nevertheless, after researching options by visiting sludge therapy services globally, Epasa realized the answer didn’t exist as a industrial providing. The corporate then moved to contract a Brazilian engineering firm to assist it design a devoted system that will cater to the facility plant’s particular calls for. “The whole system would have required integrating applied sciences from two distributors,” Agra famous.
 |
|
1. Epasa’s system featured a GEA OSE 80 for sludge beneficiation and the WSE 20 bilge separator for purifying oily water earlier than disposal. Courtesy: Epasa |
Following engineering discussions, which lasted greater than a yr, Epasa convened an in-house group of consultants and collaborated with GEA, which “opened a window to vary particular elements of their commonplace tools” and adapt the mission to Epasa’s wants. Beneath the working answer, Epasa bought a GEA OSE 80 centrifugal separator to beneficiate the sludge produced by the usual GEA and Alfa centrifugal separators through the purification of uncooked HFO. As well as, Epasa built-in a GEA WSE 20 bilge separator to purify the oily water earlier than disposal (Determine 1).
Basically, as Agra defined, the system operates in two key phases. Within the first stage, the GEA OSE 80 centrifugal separator, with an efficient capability of as much as 2,300 liters per hour and working at a separating temperature of 95C, beneficiates the sludge. This de-watering course of effectively separates the sludge into three distinct outputs: water, which nonetheless incorporates oil starting from 5% to 30% by quantity; handled oil that Epasa may reuse as gas; and sludge residue, appropriate for direct supply to industrial customers akin to cement and ceramic industries. The preliminary combination getting into the OSE 80 sometimes contains 70% to 95% water and about 3% strong content material, highlighting its capability to deal with excessive moisture content material successfully.
The second stage entails the GEA WSE 20 centrifugal separator, designed to course of as much as 1,200 liters per hour at a barely decrease temperature of 90C, which focuses on de-oiling. This stage is essential for treating the oil-laden water produced within the first stage by way of a mixture of filtration, coalescence, and separation strategies. At this stage, the combination predominantly consists of water (99.8% by quantity) with a minimal oil content material of 0.1%. This ensures that the ultimate discharged water meets environmental requirements for disposal or potential reuse in different processes.
 |
|
2. Epasa’s sludge beneficiation system is the primary worldwide to implement a whole GEA Group system in a thermoelectric energy plant, using centrifugal separators for sludge beneficiation and water purification. Courtesy: Epasa |
The mission, carried out in 2021 (Determine 2), instantly confirmed promising outcomes, however after an intensive interval of monitoring and working the therapy system, Epasa’s workforce recognized a possibility to make enhancements. “Initially, the mission aimed to acquire beneficiated sludge with low moisture content material to be commercialized with added worth,” the corporate famous. “Nevertheless, the product obtained from treating the HFO sludge by the GEA OSE 80 separator had a water content material effectively under 1%, and laboratory checks confirmed that the product met HFO specs. Thus, each time the product was appropriate with the gas saved within the storage tank, we directed the beneficiated sludge for burning in our engines, thereby decreasing HFO consumption.”
A Significant Mission with Extra Potential
In line with Agra, the mission has up to now helped Epasa scale back its HFO losses from 2% to 0.2%. That alone has proven some financial positive aspects. “The payback of the mission might be lower than three years, although that will require full technology for 3 years, which isn’t our actuality,” he stated. As well as, the system is enticing, provided that set up of the system was comparatively simple, he famous.
A brief-lived problem he highlighted was that the system’s integration into the plant required a brief halt to operations. After that, implementing the answer effectively requires time to adequately practice plant personnel and make sure that they’ll combine the brand new course of into current operations, he stated.
For Agra, a extra important lesson rests within the expertise it gained in pulling collectively numerous consultants to resolve a longstanding downside. He recommended that the answer now stands as a profitable enterprise alternative for Epasa.
—Sonal Patel is a POWER senior editor (@sonalcpatel, @POWERmagazine).
