Experimental Investigation on the Effects of the Geometry of the Pilot Burner on Main Flame

Various kinds of pilot burners were experimentally investigated to examine the effects of their geometry and their location relative to the main burner of a real size combustor. In addition, a wide range of fuel equivalence ratios were investigated to analyze the feasibility of the novel pilot burner for the conventional burner application. From the results, it is shown that the novel pilot burner with multi air holes had a thin, straight, long and stable pilot flame, while the conventional pilot burner had a thick, lifted, short and unstable flame. It is also shown that the novel pilot burner with an upper air flow hole had a straight pilot flame which led to less thermal damage to the burner combustor. This study suggests that not only pilot burner flame shape but also the vertical location of the pilot burner from the main burner combustor has a significant effect on combustor durability.

ANALISIS PERFORMANCE MESIN RESIDUAL OIL MAIN BURNER PADA UNIT PLTU 3/4 DENGAN METODE RELIABILITY AVAILABILITY MAINTAINABILITY (RAM) DI PT PEMBANGKIT JAWA BALI UNIT PEMBANGKIT GRESIK

ABSTRAK PT. Pembangkit Jawa Bali Unit Pembangkit Gresik merupakan anak perusahaan PLN BUMN produsen listrik yang salah satu penyuplai kebutuhan listrik di Jawa Timur. Salah satu unit pembangkit listrik Gresik yaitu PLTU unit 3 dan 4 yang mempunyai mesin kritis residual oil main burner pada sistem operasi listrik. Residual Oil Main Burner merupakan tempat pembakaran minyak yang dioperasikan ketika dibutuhkan dua pembakaran. Pada mesin residual oil main burner tidak terdapat penjadwalan pemeliharaan yang tepat. Maka dari itu perlunya kebijakan maintenance pada mesin residual oil main burner yang tepat. Metode yang digunakan Reliability Availability Maintainability (RAM) yang bertujuan untuk memprediksi kinerja keandalan, ketersediaan, kemampuan perawatan dari mesin sehingga memiliki performance mesin yang baik. Berdasarkan hasil perhitungan performance mesin dengan menggunakan metode Reliability Availability Maintainability (RAM), diperoleh nilai reliability sebesar 80,36% pada R(t) = 240 jam dan untuk mencapai nilai maintainability 81% dibutuhkan waktu perbaikan selama lima jam dengan inherent availability sebesar 99,31% dan operational availability sebesar 95,23%. Kata Kunci: availability, maintainability, PT. Pembangkit Jawa Bali Unit Pembangkit Gresik, reliability, residual oil main burner.

Modeling of the Coal Particle Behavior in an Ultra-Supercritical Boiler With Large Eddy Simulation

Large eddy simulation (LES) is becoming a promising tool for the design and retrofit of utility boilers. It explicitly calculates the large-scale eddies which play an important role in the particle behavior inside the boilers. An ultra-supercritical tangentially fired boiler was simulated under the boiler maximum continuous rate (BMCR) condition by LES. The particle phase was tracked by the simplified direct quadrature method of moments in the Eulerian framework. Five particle sizes were adopted to represent the wide particle size distribution. The predicted gas velocities were in good agreement with the thermal calculation. The LES results showed that the particles were more likely to be concentrated in the main burner zone while quickly dispersed in the over fire air (OFA) zone. A theoretical analysis found that the particle Stokes number based on the sub-grid scale was much smaller than one. The particles would behave as tracers for the eddies resolved by LES. However, some differences between the small and large particles were observed in the particle number density distributed along the vertical and horizontal directions. It meant that the inertial effects on the particle motion cannot be neglected.

Using Waste Heat to Dry RDF: a Technical and Environmental Assessment of the Low Temperature Belt Dryer Technology

In 2015, the Portuguese cement production company Cimpor modified the alternative fuel supply operation of refuse derived fuel (RDF) co-processing in the main burner of one of its cement kilns in Souselas. This modification resulted in the installation of an RDF drying unit with low temperature belt dryer (LTBD) technology that uses cascading energy available in Souselas cement plant. Implementation of the dryer project improves production and efficiency of the industrial process, while also resulting in environmental benefits as it decreases moisture and increases the lower calorific value of RDF, improving its quality. This paper intended to determine these environmental benefits and the added value that the project brings to the industry by presenting an energy balance and environmental assessment. This methodology allowed to compare the use of available heat as an energy source for the dryer instead of fossil fuels, such as natural gas or coal, which concluded that the waste heat available at the cement plant for the dryer would allow the saving of 75 to 84 kg of CO2-eq per tonne of wet RDF to be dried. Projects such as this one may greatly help address the main barriers of using RDF from municipal solid waste and other waste streams with high moisture content.

Comparing Jet-A and JP-10 Ignition Performance in a Swirl-Stabilized Combustor at High Mach Conditions

The capability of current turbomachinery-based engines limit the obtainable altitude and flight Mach number of modern aircraft. Maturing hypersonic technologies such as ram and scramjets allow greatly increased flight velocity but are not able to power themselves from the ground and, thus, rely on lift aircraft. Combined-cycle engines incorporate turbomachinery and ramjet technologies to allow both high and low flight Mach numbers. These high Mach capable systems are typically flown using specialty fuels such as JP-7 that are more applicable to hypersonic applications than conventional gas-turbine fuels such as JP-8/Jet A or JP-5. Potential issues exist, however, when operating a combined cycle that employs a legacy main combustor since these platforms were not designed for operation with these fuels. Of particular concern is the re-ignition performance of the turbomachinery core. The relight of the gas-turbine combustor occurs at high altitudes and relatively high vehicle speeds, yielding low pressure and temperature in the combustor as well as high combustor-dome velocities. All of these conditions are unfavorable for ignition. Additionally, heavy fuels require more energy for atomization and vaporization, which increases the probability that ignition will become a problem in a turbine-based combined-cycle (TBCC) system. Successful demonstration of legacy main-combustor technologies in hypersonic combined-cycle applications will eliminate the need for costly design of new main-burner technology. The literature does not provide information on the effects of running specialty fuels such as JP-7 and JP-10 in burners with conventional aerodynamic features. To fill that gap, a three-cup sector of a conventional fighter-class swirl-stabilized combustor configured to provide optical access through the sidewall was used in the study. Two test conditions representative of varying flight Mach number and altitude are evaluated. For each flight condition, the combustor pressure drop is varied to characterize ignition as a function of burner inlet velocity. Data are correlated by loading parameter and equivalence ratio at ignition, and at each test point the conditions are varied until ignition cannot be achieved.

Numerical Investigation of Fuel Distribution Effect on Flow and Temperature Field in a Heavy Duty Gas Turbine Combustor

Multiple-swirlers structure is commonly adopted for combustion design strategy in heavy duty gas turbine. The multiple-swirlers structure might shorten the flame brush length and reduce emissions. In engineering application, small amount of gas fuel is distributed for non-premixed combustion as a pilot flame while most fuel is supplied to main burner for premixed combustion. The effect of fuel distribution on the flow and temperature field related to the combustor performance is a significant issue. This paper investigates the fuel distribution effect on the combustor performance by adjusting the pilot/main burner fuel percentage. Five pilot fuel distribution schemes are considered including 3 %, 5 %, 7 %, 10 % and 13 %. Altogether five pilot fuel distribution schemes are computed and deliberately examined. The flow field and temperature field are compared, especially on the multiple-swirlers flow field. Computational results show that there is the optimum value for the base load of combustion condition. The pilot fuel percentage curve is calculated to optimize the combustion operation. Under the combustor structure and fuel distribution scheme, the combustion achieves high efficiency with acceptable OTDF and low NOXemission. Besides, the CO emission is also presented.

Investigations of the Stabilities of Piloted Flames Using Blast Furnace Gas

The effective utilization of low-grade energy sources generated from steel-making processes provides not only excellent opportunities for low cost power generation but also a significant means for the reduction of greenhouse gas emissions. In this paper, the work was carried out to study the static and dynamic combustion instabilities for gas turbine (GT) combustors burning low-calorific-value blast furnace gas (BFG). A burner was designed to stabilize the BFG flame with central pilot flames. A diagnostic system was set up to detect the characteristics of flame dynamics. In the experiments, the fuel ratio between the pilot and main burner, and the equivalence ratio of the main flame and the annular flow velocity were varied for the investigation of the combustion lean blowout (LBO) limits. The flame dynamics near LBO were investigated. The dynamic responses of the flame to flow perturbations were also measured. A network model was employed to study and validate the blowout mechanisms. The LBO limits were calculated and compared with experimental results for various equivalence ratios.

Development of the DLE Combustor for L30A Gas Turbine

This paper describes the development of the Dry Low Emission (DLE) combustor for L30A gas turbine. Kawasaki Heavy Industries, LTD (KHI) has been producing relatively small-size gas turbines (25kW to 30MW class). L30A gas turbine, which has a rated output of 30MW, achieved the thermal efficiency of more than 40%. Most continuous operation models use DLE combustion systems to reduce the harmful emissions and to meet the emission regulation or self-imposed restrictions. KHI’s DLE combustors consist of three burners, a diffusion pilot burner, a lean premix main burner, and supplemental burners. KHI’s proven DLE technologies are also adapted to the L30A combustor design. The development of L30 combustor is divided in four main steps. In the first step, Computational Fluid Dynamics (CFD) analyses were carried out to optimize the detail configuration of the combustor. In a second step, an experimental evaluation using single-can-combustor was conducted in-house intermediate-pressure test facility to evaluate the performances such as ignition, emissions, liner wall temperature, exhaust temperature distribution, and satisfactory results were obtained. In the third step, actual pressure and temperature rig tests were carried out at the Institute for Power Plant Technology, Steam and Gas Turbines (IKDG) of Aachen University, achieving NOx emission value of less than 15ppm (O2=15%). Finally, the L30A commercial validation engine was tested in an in-house test facility, NOx emission is achieved less than 15ppm (O2=15%) between 50% and 100% load operation point. L30A field validation engine have been operated from September 2012 at a chemical industries in Japan.

Investigations of the Stabilities of Piloted Flames Using Blast Furnace Gas

The effective utilization of low-grade energy sources generated from steel-making processes provides not only excellent opportunities for low cost power generation but also a significant means for the reduction of greenhouse gas emissions. In this paper, the work was carried out to study the static and dynamic combustion instabilities for gas turbine combustors burning low-calorific-value blast furnace gas (BFG). A burner was designed to stabilize the BFG flame with central pilot flames. A diagnostic system was set up to detect the characteristics of flame dynamics. In the experiments, the fuel ratio between the pilot and main burner and, the equivalence ratio of the main flame and the annular flow velocity were varied for the investigation of the combustion lean blowout (LBO) limits. The flame dynamics near LBO were investigated. The dynamic responses of the flame to flow perturbations were also measured. A network model was employed to study and validate the blowout mechanisms. The LBO limits were calculated and compared with experimental results for various equivalence ratios.

Kiln Process Impact of Alternative Solid Fuel Combustion in the Cement Kiln Main Burner – Mathematical Modelling and Full-Scale Experiment

Increased use of alternative fuels in cement kilns is a trend in the world. However, replacing fossil fuels like coal with different alternative fuels will give various impacts on the overall kiln process due to the fuel characteristics. Hence, it is important to know to what extent the fossil fuels can be replaced by different alternative fuels without severely changing process conditions, product quality or emissions. In the present study, a mass and energy balance for the combustion of different alternative fuels in a cement rotary kiln was developed. First, the impact of different fuel characteristics on kiln gas temperature, kiln gas flow rate and air requirement were observed by using coal (reference case), meat and bone meal (MBM), two different wood types, refuse derived fuel and a mixture of saw dust and solid hazardous waste as the primary fuel. It was found that the key process parameters depend largely on the chemical characteristics of the fuel. It appears that MBM shows quite different results from other alternative fuels investigated. Next, simulation of combustion of a mixture of coal and MBM in the main burner was carried out in three steps. The first step was combustion of replacing part of coal energy with MBM, and a reduction in kiln exhaust gas temperature compared to the coal reference case was found. In the second step, the fuel feed rate was increased in order to raise the kiln gas temperature to that of the reference case. In the third step, the fuel feed rate and the clinker production rate were changed in order to have not only the same kiln gas temperature but also to obtain the same volumetric flow rate of total exhaust gas from the precalciner as in the reference case. Around 7% of reduction in clinker production rate could be observed when replacing 48% of the coal energy input. Results from a full-scale test using the same mixture of coal and MBM verified the simulation results.