Boiler Efficiency for Reduced Carbon Emission and Cost
by Marcelle P. Villegas - April 01, 2021
A case study at the GNPower coal power plant in Mariveles, Bataan (Photo credit: https://www.gnpower.com.ph/projects/)
GNPower Ltd. Co. (or “GNPower”) is a private limited partnership that was organised and established in 1997 by PMR Holding Corp. as its sole general partner and PMR Limited Co. as limited partner. The company aims to develop, operate and own power generation projects and associated facilities in the Philippines. Through the years, there were changes in the corporate structure and partnerships. By June 2014, the sole general partner of GNPower is GNPower Holdings GP Corporation which is owned by Power Partners, while Power Partners is the sole limited partner.
With regards to their coal energy project, it started way back in 2005. On that year, the partnership began the development of a coal-fired project. It was their first step in creating an “integrated, multi-fuel electricity generation and fuel handling energy complex”. 
Five years later, the GNPower began the construction of a 2x316MW (net) clean pulverized coal-fired power plant located in Mariveles, Bataan, Philippines (“Mariveles Project”). In this project, GNPower and Power Partners own a significant minority position through their ownership of GNPower Mariveles Coal Plant Ltd. Co. (GMCP). GMCP is the special purpose vehicle established to construct, own and operate the Mariveles Project. 
In 2013, the coal-fired facility was declared commercially available in the market. It is GNPower’s pioneer project and is the largest greenfield power project that was built in Luzon after the enactment of EPIRA in 2001.
GNPower Mariveles Coal Plant Ltd. Co. is now referred to as GNPower Mariveles Energy Center Ltd. Co.
Coal is considered a baseload energy resource in the Philippines as it is sufficiently cost-effective in providing a consistent supply of power. Currently, there are 28 coal-fired power plants operating throughout the Philippines.  One competitive and significant factor in the industry is the plant’s ability to supply adequate power while burning less coal in the process. In relation to this, a study was conducted by a group of experts to determine how cost-efficient is the operation in the Mariveles Coal Plant. What are the possible strategies they can or have implemented to assure boiler efficiency that utilizes less coal? What is the significance of this study with regards to protecting the environment through reduced carbon emission?
“A Study of the Changes in Efficiency of a Coal Fired Boiler Following the Conversion to a Dry Bottom Ash Handling System” is a study done by Artemio Boado (Plant Manager, Mariveles Power Plant), Zhao Peng (Engineering Manager, Qingdao Daneng), Steven Hou (General Manager, Int’l Business of Qingdao Daneng), Wang Yong (Chairman, Qingdao Daneng) and Edgardo B. Cruz (President, Philippine Coal Plant User Group).
The study aims to determine and analyse the boiler efficiency of Unit 2 of Phase 1 of GN Power Mariveles, according to measured data before and after the conversion of the bottom ash system from wet to dry which was implemented in March 2018. 
From their report, GN Power Mariveles Phase 1 consists of 2 x 340 MW T-fired sub critical coal fired boilers (Originally 2 x 316MW). The boilers were supplied by Harbin Boiler Company of China. This has a wet bottom handling system which consisted of a hopper under the boiler, sealing plate, submerged scraper conveyor, cooling water system, silo and discharger. The wet system was later converted to dry system by Qingdao Daneng Environmental Protection Equipment Incorporated Company (or Qingda) utilising their patented DUNOCON conveyor technology. “Both units were converted and commissioned in a standard scheduled 30-day boiler outage with Unit 2 converted in March 2018 and Unit 1 in February 2019. Since commissioning, both units dry bottom ash systems have operated well and without issue.” 
“When considering a pulverised coal fired boiler, the application of dry bottom ash handling technology is well proven and has several key advantages over those utilising water for the cooling and transportation of bottom ash. Along with the elimination of water handling and treatment, reduced power consumption, reduced maintenance etc, a significant amount of energy can be returned to the boiler from the reduction of energy losses at the boiler throat, waste heat from the bottom ash and the reduction of unburnt carbon in the bottom ash.” 
“However, in order to realise these potential benefits, the dry bottom ash system needs to be carefully designed and operated to ensure that the cooling air quantity and distribution through the conveyor and into the boiler are optimised.” 
Boiler efficiency testing standard
For this study, the efficiency of the boiler unit is determined basically by following the testing standard ASME PTC-4.1. (Further calculation methods not considered in ASME PTC-4.1 have been supplemented to compute for the credits specifically due to the adoption of dry bottom ash technology. )
There are two ways to compute for the boiler efficiency testing: (1) direct method (2) indirect method.
Direct method is obtained by the ratio of energy gain of working fluid (water or steam) compared to the energy input into the boiler. Here is the formula they used:
Comparative analysis of boiler efficiency
(1) Direct method
Based on Table 1 and Figure 2, that coal consumption has reduced by an average of 2.12% over a boiler load range of 320 MW to 340 MW since the retrofit conversion of Unit 2 to a Dry Bottom Ash System. Table 2 is the operating data from the owner with the boiler load between 339 and 340 MW which can be used to calculate the boiler efficiency using the ASME PTC4.1 direct method. 
(2) Indirect Method
For the Indirect Method, the study explored the various factors in measuring the efficiency of the boiler system. These factors include:
a) dry flue gas heat loss
Dry flue gas heat loss is the main reason of boiler heat loss. Using formula (2), various heat losses are discussed here:
Based on this data, there is no significant change in the flue gas temperature at the inlet of air preheater, and the oxygen content decreases. With the help of the advanced air control DUNOCON system, “the cooling air quantity is controlled quantitatively to the maximum extent”, thus no excess air enters the boiler through dry bottom ash handling system. The other dry system has multiple air doors, but DUNOCON has only one air door on the head of the conveyor which is interlocked with the ash temperature of conveyor outlet. As an effect, “the cooling air quantity has been limited to maximum extent under the premise of ensuring the ash cool down effect”.  The DUNOCON also has a special penetration heat transfer design that improves the cooling efficiency and reduces the need for cooling the air. In addition, this helps the unburned carbon at the bottom ash re-burn and recovers its heat.
In this part of the study, the boiler efficiency is increased by 0.382%.
Other factors under indirect method:
b) heat loss due to evaporation of water formed due to H2 in the coal,
c) heat loss due to H20 in the coal
d) heat loss due to H20 in the air
e) heat loss due to incomplete combustion of combustible gas
“The heat loss due to the incomplete combustion is principally concerned with the losses resulting from incomplete combustion of the gaseous products such as CO, H2 and various other hydrocarbons which can potentially be found in the flue gas of a boiler. Considering Mariveles Unit 2 is a large modern Utility Boiler, then we will assume that the losses through the incomplete combustion of gases is negligible for this study.” 
f) heat loss due to Boiler Surface Heat Loss, Radiant Heat Loss, and Convective Heat Loss
“This study assumes that the Boiler Surface Heat Loss and Convective Heat Loss will not be have been affected by the changes to the bottom ash system. However, due to the change from wet system to dry system, the radiant heat at the boiler throat is recovered back to the boiler by the cooling air.”
Based on their calculations, the boiler efficiency is increased by 0.11% because of the radiant heat recovered through the cooling air.
g) heat loss due to unburnt in fly ash
i) heat loss due to bottom ash in the wet system
All the bottom ash is cooled by the water. As a result, there is a loss of all the sensible heat associated with the bottom ash. In comparison, the dry system uses the cooling air to recover the bottom ash sensible heat and reintroduces it to the boiler. In addition, part of the unburned carbon in the ash can burned during the transportation process and the heat will be recovered by cooling air. Also those heat generated improves the boiler efficiency.
Regarding the carbon combustion quantity during the conveying period, the study reported the following test list:
Carbon content in wet ash 4.59%
Carbon content in dry ash 3.5%
This shows that about 1.09% of the carbon in the dry bottom ash reburns and releases heat. Those heat is also brought back to the boiler by the cooling air. The unique penetrating cooling action of the DUNOCON system increases the contact area between the bottom ash and the cooling air, and increases the combustion probability of carbon. Qt=174876 KJ/hr From the formula (16), the boiler efficiency increase R2=0.016%. 
To sum up, the efficiency of the boiler is increase by 0.51% after the retrofit in indirect method.
Cost and energy conservation
a) From the table 1, the average coal consumption before and after the retrofit of boiler is 208t/h and 204.45t/h under 330~340MW. Assuming that the annual operating time of 8000h, the annual coal saving is about 28,400t. 
b) Comparing this with the wet bottom ash handling system, the dry system has no circulating water system, thus the system is simpler and the operation is fully automatic. Additionally, the power consumption of dry system is lower than wet system.
c) After the retrofit, the daily maintenance work of dry system is almost zero. Compared with the wet system, it saves a lot of labor cost for the power plant.
d) Studies show that for every 1% increase in boiler efficiency, 2% of carbon dioxide emissions can be reduced , so the dry system also contributes to the reduction of emissions.
In conclusion, based on the study and analysis, the Unit 2 boiler efficiency of GN Power Mariveles Plant increased about 0.51% after retrofit to DUNOCON dry bottom ash handling system. The reduction of flue gas quantity is the main reason to improve the boiler efficiency. The advanced air control technology of the DUNOCON system is an important key point. “The recovery of radiant heat from the boiler throat and sensible heat from the bottom ash also improves the boiler efficiency. The improvement of boiler efficiency saves about 28,400 t of coal for the power plant every year. And compared with wet system, dry bottom ash handling system is more advanced, safe and stable, and saves a lot of operating costs for the power plant.”
Since the early 1990s, GNPower Ltd. Co. has been excelling in the power industry with their remarkable achievements in the completion of power projects. Their power plant projects had been providing electricity supply services to several Philippine-based customers. Other than developing coal-fired plant in Mariveles, (GNPower Mariveles Energy Center Ltd. Co.), they also have the GNPower Kauswagan Ltd. Co., and the upcoming GNPower Dinginin Ltd. Co. Of note, GNPower is the first Retail Electricity Supplier (RES) to be licensed by the Energy Regulatory Commission. They are also the first to have signed long-term power supply agreements with a group of Contestable Customers since 2006. GNPower also adheres to the mandate of the EPIRA Law of Department of Energy.
Mr Edgardo B. Cruz of Philippine Coal Plant Users Group and Mr Ariel Punzalan of PMR Group and GNPower Ltd. Co.
 Retrieved from the company website of GNPower Ltd. Co. - https://www.gnpower.com.ph/about-us-new/
 Chavez, Leilani (Nov. 5, 2020). Mongabay News. "Philippines declares no new coal plants — but lets approved projects through".
 Boado, Artemio, Cruz, Edgardo B., et. al. “A Study of the Changes in Efficiency of a Coal Fired Boiler Following the Conversion to a Dry Bottom Ash Handling System”.
Philippine Resources - September 24, 2021
DOTr, Pasay City sign deal for monorail, flyover extension
Residents and those working in Pasay City will soon enjoy easier public transportation after the Department of Transportation (DOTr) and the city government signed a deal for the construction of a monorail and extension of the Epifanio Delos Santos Avenue (Edsa)-Tramo flyover. In a live broadcast on Facebook on Wednesday, DOTr Secretary Arthur Tugade and Pasay City Mayor Emi Calixto-Rubiano signed the memorandum of agreement (MOA) for the proposed Integrated Pasay Monorail and Edsa-Tramo flyover extension project. Tugade said the project will be interoperable with the Light Rail Transit Line 1 (LRT-1), Metro Rail Transit Line 3 (MRT-3), the Edsa Busway, and the Edsa Greenways. “[Ito ay] makapagbibigay ng mas mabilis at episyenteng biyahe sa mga pasahero. Magiging mas madali na rin ang access patungong central business district (CBD) ng Pasay (This will provide fast and efficient travel to passengers. Access to Pasay CBD will also be easier),” Tugade said. Aside from its benefits to commuters, he said the project will also create jobs. “Ang paulit-ulit kong sinasabi na karugtong ng mga proyekto para sa kaunlaran ay trabaho para sa Pilipino (What I have always been saying is that development projects go hand-in-hand with jobs for Filipinos),” Tugade said. He said the project is a partnership between the DOTr, Pasay City government, and SM Prime Holdings. “Makakaasa 'ho kayong magpapatuloy ang DOTr sa pagsusulong ng mga proyekto para sa ikauunlad ng pampublikong transportasyon sa bansa (You can be rest assured that the DOTr will continue to promote projects for the development of public transportation in the country),” Tugade said. The MOA signing was witnessed by Pasay City Vice Mayor Noel del Rosario, DOTr Undersecretary for Finance Giovanni Lopez, Undersecretary for Legal Affairs Reinier Paul Yebra, Undersecretary for Railways Timothy John Batan, SM Prime Holdings President Jeffrey Lim, and other representatives from the Pasay City government and the private sector. On Sept. 7, the Pasay City government and the SM Prime Holdings made a joint presentation on the project to the DOTr. By Raymond Carl Dela Cruz Article courtesy of the Philippine News Agency
Philippine Resources - September 24, 2021
DOTr eyes GenSan airport as alternate int'l gateway
Photo credit: Department of Transportation The Department of Transportation (DOTr) is pushing for the inclusion of the newly rehabilitated and expanded airport here as among the alternate gateways for returning Overseas Filipino Workers (OFWs) and international travelers. DOTr Secretary Arthur Tugade proposed the move on Thursday as he personally led the formal unveiling and inauguration of the city airport’s new passenger terminal building and other completed facilities. He said the city’s international standard airport can accommodate airline passengers coming in from as far as the Middle East. Tugade said it can be realized once the proposed increase in the daily cap for returning OFWs, currently at 2,000 for the Ninoy Aquino International Airport (NAIA), is approved. Once the cap is expanded, he said NAIA might “choke” with the influx of airline passengers from various countries. “If we will increase the cap, we need to expand our gateways and not limit them to Clark, Cebu, and NAIA. We can include GenSan among the gateways for travelers from Doha who are going to Manila,” he said in a press conference. He said they will propose such strategy with the airlines serving the international routes, including the Philippine Airlines, and seek the approval of the city government. The other possible alternate gateways could be the Laoag International Airport in Ilocos Norte and the Bohol-Panglao International Airport, Tugade said. The rehabilitated and expanded General Santos Airport passenger terminal building, which was completed early this month, is part of the PHP959-million upgrade implemented by the national government. The other completed components are the procurement and installation of navigational aids and the construction of the new Civil Aviation Authority of the Philippines (CAAP) administration building at the airport. Under the project, Tugade said the passenger terminal area has tripled in size from 4,000 to 12,000 square meters. “This will allow the airport to accommodate more passengers and provide them comfortable and convenient travel,” he said in his speech. A DOTr report said the larger passenger terminal building can now accommodate around 2 million passengers annually, a significant jump from the previous 800,000 per year. Tugade said the improvement at the city airport will continue next year with the upgrading of its air control tower, which he considered as “too low.” He said they will build a “higher and modernized” tower in 2022 to make it “more world-class” and can easily adjust to the needs of the airport. The official said the upgrading of the airport, which started in 2018, is among the agency and the national government’s top priorities in Mindanao. He said the initiative is part of the government’s efforts to bring more progress and economic opportunities in Mindanao, which “suffered from long years of neglect in terms of development.” Tugade said they endeavored to implement these projects despite the challenges posed by the continuing coronavirus disease 2019 (Covid-19) pandemic to pursue their goal of giving a “comfortable and convenient life” to Filipinos. “After the pandemic, we want all these developments in place and ready to benefit the people,” he said. In a video message, President Rodrigo Duterte commended the DOTr, the local government, and concerned stakeholders for completing the projects at the city airport amid the Covid-19 pandemic. He said the city has “gone a long way” in terms of the development of its air connectivity and airport facilities. “The rehabilitation and expansion of the airport passenger terminal building, among others, will truly boost General Santos City’s role as an agro-industrial and eco-tourism hub,” the President said. City Mayor Ronnel Rivera lauded the national government for helping the city realize its dream of having an international-standard airport. Aside from the expanded passenger terminal building, the airport is now capable of accommodating bigger aircraft like Boeing 737 and 747, as well as Airbus A330, A340, and A350. “(What) we are seeing now is a result of multisectoral commitment and dedication in various stages of the airport development, which includes coordination of several initiatives, preparation of the airport master plan, operations, and marketing,” he said. The mayor said the local government will continue to engage with prospective investors and airlines for the opening of more flights to and from the airport and the development of adjacent areas. He cited the proposed establishment of an aerotropolis or growth area centered on the city airport and its surrounding areas. “We are opening a wide array of opportunities, not only on the improvement of our infrastructure facilities but also in terms of investments that will generate more economic opportunities for the city and the entire region (Soccsksargen),” he said. Aside from the inauguration of the airport projects, Tugade also led the unveiling of completed initiatives at the Makar port here. The DOTr said it includes the construction of the Port Operations Building and other vital facilities, which includes a parking area, covered court, port manager’s quarter or Day Care Center, and drainage system. “The improved port of Makar will now offer safer, comfortable, and a more convenient port experience to passengers, while ensuring a faster turnaround for vessels, cargo trucks, and other ancillary service providers,” it said. Article courtesy of the Philippine News Agency
Philippine Resources - September 22, 2021
Cebu-Cordova Link Expressway 83% Complete
Photo credit: Cebu-Cordova Link Expressway As of August 31, 2021, the construction progress of the Cebu-Cordova Link Expressway (CCLEX) project was at 83.84 percent. The P30-billion toll bridge, which will be substantially completed by the end of 2021, will use a full electronic toll system when it opens to motorists in the first quarter of 2022 to enable faster traffic flow and seamless travel. The project recently marked a milestone with the completion of the installation of all 56 stay cables that hold the main bridge deck. On September 11, the Cebu Cordova Link Expressway Corporation (CCLEC), through its contractor, installed the last and longest stay cable, which is 219 meters long. The gap on the main bridge, on the other hand, is now down to only two meters before span closure and preparations are underway for the lowering of the form travelers. These form travelers, which weigh 500 tons in each tower, were used to construct the main bridge’s pier table and deck. Also, all 434 NU (Nebraska University) girders for the entire project have already been installed. With this, the mobile launching gantry used to install the girders have been demobilized. At the Cebu South Coastal Road (CSCR) on ramp and off ramp sections of CCLEX, construction of its substructures is complete. Ongoing works are now on the installation of precast planks and the concreting of deck slab. Also finished is the 200-meter pedestrian footbridge beside the CSCR with all six prefabricated steel walkways already installed. The footbridge will start near the U-turn slot of the South Road Properties’ welcome tower and will connect to the on-ramp sidewalk of CCLEX. At the Cebu viaduct, the construction of deck slab is ongoing. The Cordova viaduct, on the other hand, is now structurally complete with its substructure already done. Installation of handrails are underway. At the causeway, embankment works continue to progress with the placing of 20 vent pipes, which equalize the flow of seawater along the Cordova Channel, is finished. Also structurally complete are the four low-level bridges along the causeway, which will provide fishermen continued access to their fishing grounds. Aside from these, works are ongoing for the toll plaza and the CCLEX Operations and Maintenance Center. CCLEX, highlighted by its iconic crosses on top of the twin pylons of the cable-stayed main bridge over the Mactan Channel, is Metro Pacific Tollways Corporation’s (MPTC) first toll road project outside Luzon. CCLEX, which will be the third link to Mactan Island from Cordova Municipality to mainland Cebu through Cebu City’s South Road Properties, has a design speed of 80 kilometers per hour (kph) and a navigational clearance or height of 51 meters to allow large vessels to pass underneath the bridge. Not only is CCLEX seen to reduce traffic and make traveling more convenient but also spur trade activities and open greater economic opportunities for Cebu and the rest of the Visayas region. CCLEX is a project of Cebu Cordova Link Expressway Corporation (CCLEC), in partnership with the local government units of Cebu City and Municipality of Cordova. CCLEC is a wholly owned subsidiary of MPTC, the toll road arm of Metro Pacific Investments Corporation (MPIC), a publicly listed infrastructure holding company and a member of the MVP Group of Companies. MPTC is the largest toll road concessionaire and operator in the Philippines, which expansion goals include establishing toll operations in the Visayas, other parts of the Philippines, and in neighboring countries notably Vietnam, and Indonesia. Article courtesy of Cebu-Cordova Link Expressway