North power generation hiflo camclose camgt 4v300

The North Bangkok Power Plant is exposed to a large concentration of industrial dust in combination with high humidity

EGAT is the largest energy producer in Thailand and has recently invested in North Bangkok Power Plant (NBPP).

NBPP has a combined-cycle power plant with a contracted power generation capacity of 670 MW. The plant employs combined-cycle production technology, utilizing both natural gas and steam as the fuel for power production.

In 2014, EGAT began searching for alternative solutions to the existing filtration system after incurring high costs due to engine degradation. As a result of the surrounding environmental conditions, their existing system required an engine shutdown at least 3 times per year for water washing, and the combustion air filters had to be replaced once every few months.

The Site

NBPP is located alongside Chao Phraya River in Thailand near the six lane Rama 7 Bridge, passing through the heart of Bangkok. Since the location is susceptible to a high concentration of dust, high humidity and frequent strong winds, the plant‘s two 227.4 MW gas turbines are exposed to an average dust concentration of 96 µg/m³ PM-10 (24 hr average), with an average relative humidity of 73% and temperature of 33°C.

The Bidding Process

In need of better performing filters, in 2014, EGAT opened a bid requesting an upgrade to a 3-stage EPA class static filtration system without a filter housing retrofit. At the time, EGAT was using the following 3-stage system:

• 1^st stage: G3 coalescer filters (replaced every 1-2 months)
• 2^nd stage: G4 pre-filters (replaced 3 times per year)
• 3^rd stage: F9 final filters (replaced once per year)

The criteria of no retrofitting of the main structure was a major challenge for the bidders, therefore, only Camfil and two other major filter suppliers joined the bidding process.

Camfil's Life Cycle Cost Analysis

Camfil used its Life Cycle Cost (LCC) analysis software to determine the best solution for NBPP. In the evaluation, the software considered variables such as the surrounding environment along with the pollutants in the air, the turbine model, the cost of fuel, the average value of each MW produced, the lost production due to downtime, the filter disposal cost, as well as how fouling and pressure drop affected power output.

LCC Test Results & Product Benefits

The following 3-stage system was recommended as the optimal solution based on the LCC; the turbine would be protected against coarse dust and humidity without any modifications of the hardware:

1^st stage - Hi-Flo F7¹: With a guaranteed stable efficiency according to EN779:2012, the Hi-Flo filters effectively clean the air of larger particles and contaminants such as pollen, paper dust and other atmospheric impurities. The filter material is specifically produced with the goal of minimizing system energy costs. This means that the initial pressure drop is low and has a flat trajectory of development over the operating period. Additionally, the filter’s particle separation efficiency remains high and meets  promised performance standards.

2^nd stage - CamClose M6¹: This stage adds additional protection from water droplets and semi-liquid particles. The easy snap-on mounting system of the CamClose panel filter requires neither retrofitting of the filter housing nor additional assembly parts to fit on a compact filter cassette. This makes it possible to add an extra filter stage to the filter system without the need of an extra filter bank.

3^rd stage - CamGT 4V-300 E10² met the EPA class requirements. The CamGT 4V-300 is a high-performing filter that eliminates bypass air, provides higher power output, extends turbine life, and reduces maintenance and life cycle costs. Furthermore, each filter grade is individually optimized in order to provide the lowest possible pressure drop.

Savings

Camfil was awarded the project, providing the optimal balance of minimal pressure drop and high filter efficiency of 93%^3, with the lowest total cost. Before EGAT upgraded to EPA class filters, the annual combined degradation of heat rate and power output was 6.38%. Consequently, the engines required offline washing 3 times a year with costs of  $1.56M USD/engine. After they switched to an EPA class, the degradation lowered to 2% and offline washing was required only once per year, together costing only $0.94M USD/engine. EGAT estimated that their total savings amounted to $1.24M USD per year from the upgrade.

¹ EN779:2012 standard

² EN1822:2009 standard

³ MPPS, most penetrating particle size.