Teknologi emisi rendah: aplikasi aliran berpusar

Buku ini secara amnya menerangkan mengenai penggunaan teknologi pusaran udara untuk mengurangkan pembentukan emisi dari proses pembakaran seperti oksida nitrogen (NOx), karbon monoksida (CO) dan hidrokarbon tak terbakar (HC). Perbincangan dalam buku ini memfokuskan kemampuan pemusar udara aliran jejarian dengan pemboleh ubah kekuatan pusaran yang berupaya menambahbaik percampuran bahan api cecair dan udara serta mengawal pembentukan bahan cemar ketika dioperasikan pada tekanan ambien. Buku ini dipersembahkan dalam cara yang dirasakan dapat membantu pembaca untuk memahami masalah yang ditimbulkan dan bagaimana penggunaan teknologi pusaran dapat menyelesaikan masalah tersebut. Perlaksanaan penyelesaian yang dibincangkan merupakan gabungan daripada permodelan berkomputer serta ujikaji yang telah dijalankan di makmal. Permodelan berkomputer melibatkan analisis isoterma dan permodelan tindak balas (pembakaran) sementara keputusan ujikaji memberi lebih tumpuan kepada analisis emisi pembakaran. Walaupun tidak dinafikan terdapat pelbagai lagi kaedah yang dapat mengurangkan emisi, penulis merasakan teknologi pusaran yang dibentangkan dalam buku ini merupakan antara kaedah yang paling cekap dan mudah untuk dipraktikan dalam menghasilkan sebuah pembakar yang lebih mesra alam sekitar

Keberkesanan pembakaran udara berperingkat dalam mengurangkan emisi dari pembakar berbahanapi gas

Combustion process from a gas burner tends to emit emissions containing several different pollutants such as NOx, CO, CO2 etc. These emissions must be reduced as they are harmful towards living things. Due to this, a study on the burner performance is very essential to ensure that the burner is able to operate efficiently and producing low emissions level. An experiment has been performed by regulating the airflow rates at 7, 8, 9, 10 and 12 g/s. This experiment also involved injecting secondary air to study the emission reduction. Results obtained showed that the optimum burner operation is at equivalence ratio of 0.86 and at 17.69 kW

Prediction of the flow inside a micro gas turbine combustor

The main purpose of this study is to predict the flow dynamics inside a micro gas turbine combustor model. The flow field inside the combustor is controlled by the liner shape and size, wall side holes shape, size and arrangement (primary, secondary and dilution holes), and primary air swirler configuration. Air swirler adds sufficient swirling to the inlet flow to generate central recirculation region (CRZ) which is necessary for flame stability and fuel air mixing enhancement. Therefore designing an appropriate air swirler is a challenge to produce stable, efficient and low emission combustion with low pressure losses. Four axial flat vane swirlers with 20 °, 30 °, 45 ° and 60 ° vane angle corresponding to swirl number of 0.27, 0.42, 0.74, and 1.285 respectively were used in this analysis to show vane angle effect on the internal flow field. The flow behavior was investigated numerically using CFD solver FLUENT 6.2. This study has provided physical insight into the flow pattern inside the combustion chamber. Results show that the swirling action is augmented with the increase in the vane angle, which leads to increase in the turbulence strength, recirculation zone size, and amount of recirculated mass. However, all these happen at the expense of the increase in pressure losses. In case of 20 ° swirler (swirl number < 0.4), the produced swirling flow is not enough to generate CRZ

Pengaruh nombor pusar ke atas pengurangan emisi NOx dari pembakar berbahan api cecair menggunakan pemusar udara aliran paksi

Pemusar udara, selain menstabilkan nyalaan adalah satu bentuk kawalan pasif bagi mengurangkan emisi gas pembakaran. Bahan cemar yang keluar bersama gas ekzos terdiri daripada gas oksida nitrogen (NOx). Gas ini amat merbahaya dan membawa kepada pencemaran udara sekeliling. Penggunaan udara pusar didapati dapat mengurangkan emisi NOx ini. Kekuatan pusaran diukur melalui nilai nombor pusar yang dapat dikira semasa merekabentuk pemusar udara. Kadar emisi ini bergantung kepada sudut pesongan bilah pemusar tersebut. Di dalam kajian ini, pemusar aliran paksi yang mempunyai sudut pesongan 40°, 50°, 60° dan 70° digunakan bagi membuktikan keberkesanan penggunaan pemusar udara aliran paksi ke atas pembakar dan pengaruh nombor pusar dalam mengurangkan emisi dari pembakar. Daripada ujikaji yang dijalankan dapat dilihat semakin tinggi nombor pusar, emisi NO semakin berkurangan. Emisi NOx menurun sebanyak 36% apabila menggunakan pemusar aliran paksi bersudut 70° dibandingkan dengan pemusar aliran paksi bersudut 40°

The comparison of various gas turbine inlet aircooling methods for various ambient condition trough energy and exergy analysis

The strong influence of climate conditions on gas turbine behavior is well known. During the summer season the output of gas turbines falls to a value that is less than the rated output under high temperature conditions. Cooling the turbine inlet air can increase output power considerably, because cooled air is dense, giving the turbine a higher mass flow rate and resulting in increased turbine output and efficiency. This study is to use the energy and exergy analysis method to evaluate the air cooling method used for enhancing the gas turbine power plant. In addition, the effect of inlet air cooling method on the output power, exergy efficiency and exergy destruction have been analyzed. Also at the end of the paper the comparison of two mentioned methods has been investigated

The Application of Water Cooling on Reducing NOx from a Gas Burner System

A gas burner system applying water cooling has been investigated using a 140mm inside diameter combustor of 294-mm length. The combustor was placed vertically upwards. All tests were conducted using natural gas only. A fixed straight blade radial swirler with 76-mm outlet diameter was placed at the inlet plane of the combustor. An orifice plate of 59 mm was inserted at the exit plane of the swirler to enhance turbulence and help in mixing of the fuel and air. Fuel was injected at the back plate of the swirler using central fuel injector with eight fuel holes pointed radially outward. Tests were conducted at 5mmH 20 pressure loss. A reduction of about 21.53% on NOx emissions was achieved at equivalence ratio of near stoichiometric (0.88) and a reduction of 35.7% was achieved at equivalence ratio of 0.42. Other emissions such as carbon monoxide were well under 100 ppm except below the equivalence ratio of 0.5 due to cooling effect. Unburned hydrocarbon emissions were well below 10 ppm except below the equivalence ratio of 0.5

Performance evaluation of palm oil-based biodiesel combustion in an oil burner

This paper presents an experimental investigation of the combustion characteristics of palm methyl ester (PME), also known as palm oil-based biodiesel, in an oil burner system. The performance of conventional diesel fuel (CDF) and various percentages of diesel blended with palm oil-based biodiesel is also studied to evaluate their performance. The performance of the various fuels is evaluated based on the temperature profile of the combustor's wall and emissions, such as nitrogen oxides (NOx) and carbon monoxide (CO). The combustion experiments were conducted using three different oil burner nozzles (1.25, 1.50 and 1.75 USgal/h) under lean (equivalence ratio (φ) = 0.8), stoichiometric (φ = 1) and rich fuel (φ = 1.2) ratio conditions. The results show that the rate of emission formation decreases as the volume percent of palm biodiesel in a blend increases. PME combustion tests present a lower temperature inside the chamber compared to CDF combustion. High rates of NOx formation occur under lean mixture conditions with the presence of high nitrogen and sufficient temperature, whereas high CO occurs for rich mixtures with low oxygen presence

Combustor aerodynamic using radial swirler

A study has been conducted to investigate the flow pattern in a gas turbine combustion chamber by simulation and experimental approaches. Flow pattern inside a combustor is important to self sustain the flame, increase mixing of air and fuel, and increase combustion intensity. Aerodynamically curved vanes allow the incoming axial flow to turn gradually. This inhibits flow separation on the suction side of the vane. Thus, more complete turning and higher swirl and radial-velocity components can be generated at the swirler exit with the added advantage of lower pressure loss. The swirl number varied from 0.49, 1.29 and 2.29 for flat vanes and only 1.57 for curved vane. The highest swirl number of 2.29 for flat vane and 1.57 for curve vane are capable of creating a clear reversal mass flow rate zone and higher swirl strength reduces the corner recirculation zone size and hence reduces the negative impact on the combustion process and the homogeneity of the wall temperature as well. Further investigation can be done for higher swirl number for both types of swirler

Development of low liquid fuel Burnera

Recently, most of the gas turbine combustion research and development involves in lowering the emissions emitted from the combustor. Emission causes adverse affect to the world and mankind especially. Main concern of the present work is to reduce the NOx emission since the CO emission could be reduced through homogeneous mixing of fuel and air. Homogeneous mixing of fuel and air is also needed in order to reduce NOx emission. A liquid fuel burner system with radial air swirler vane angle of 30o, 40o, 50o and 60o has been investigated using 163mm inside diameter combustor. Orifice plates with three different sizes of 20mm, 25mm and 30mm were inserted at the back plate of swirler outlet. All tests were conducted using diesel as fuel. Fuel was injected at two different positions, i.e. at upstream and downstream of the swirler outlet using central fuel injector with single fuel nozzle pointing axially outwards. Experiment has been carried out to compare the three emissions NOx, CO and SO2. NOx reduction of about 53 percent was achieved for orifice plate of 20mm with downstream injection compared to orifice plate of 20mm with upstream injection. CO2 and SO2 was reduced about 26 percent and 56 percent respectively for the same configuration. This comparison was taken using swirler vane angle of 60o. The overall study shows that larger swirler vane angle produces lower emission results compared to the smaller ones. Smaller orifice plates produce better emission reduction. Meanwhile, downstream injection position significantly decreases the emission levels compared to upstream injection position. Combination of smallest orifice plate and largest swirler vane angle with downstream injection produce widest and shortest flame length

H2-rich syngas strategy to reduce NOx and CO emissions and improve stability limits under premixed swirl combustion mode

The combustion performance of H2-rich model syngas was investigated by using a premixed swirl flame combustor. Syngas consisting mainly of H2 and CO was blended with components such as CH4 and CO2 in a mixing chamber prior to combustion at atmospheric condition. The global flame appearance and emissions performance were examined for high (H2/CO = 3) and moderate (H2/CO = 1.2) H2-rich syngases. Results showed that higher H2 fractions in the syngases produce lower NOx emissions per kWh basis across all equivalence ratios tested. CO emissions are equivalence ratio dependent and are less affected by the H2 fraction in the syngas. Increasing CO2 diluent ratios result in the decrease of NOx, particularly for moderate H2-rich syngases. In contrast, syngas without CO shows an increase of NOx with increasing CO2 for fuel-lean mixtures. Addition of CO2 increases the lean blowout limit of all syngases. Higher fraction of H2 produces lower lean blowout limits due to the characteristics of high diffusivity of hydrogen molecules and high flame speed that assist in the stabilisation of the flame under flame-lean conditions. The range of blowout limits for moderate and high H2-rich and pure hydrogen syngases under diluent ratios up to 25% were within the range of ϕ = 0.12–0.15