Combustion performance test of a new fuel DME to adapt to a gas turbine for power generation

Recently, DME (dimethyl ether, CH₃OCH₃) has attracted a great deal of attention as an alternative fuel owing to its easy transportation and cleanliness. This study was conducted to verify the combustion performance and to identify potential problems when DME is fueled to a gas turbine. Combustion tests were conducted by comparing DME with methane, which is a major component of natural gas, in terms of combustion instability, NO_x and CO emissions, and the outlet temperature of the combustion chamber. The results of the performance tests show that DME combustion is very clean but hard to control. The CO emission level of DME is lower than that of methane, while the NO_x emission level of DME is as low as that of methane. When firing DME, the pressure fluctuation in the combustion chamber caused by combustion instability is lower than that occasioned when firing methane. From the results of the outlet temperature of combustor we have ascertained that DME combustion is more likely to flash back than methane combustion and this property should be considered when operating a gas turbine and retrofitting a burner.     

Application of catalytic combustion to a 1.5 MW industrial gas turbine

A catalytic combustor is described for a 1.5 MW gas turbine engine. The catalyst temperature is limited and the high combustor outlet temperatures required by the turbine are generated downstream of the catalyst. The combustor design places a low NO_x preburner upstream of the catalyst and uses this preburner to achieve optimum catalyst operation by providing the desired catalyst inlet temperature. The combustor system employs the catalyst during engine acceleration and loading. The catalyst design has been tested on a sub-scale rig under full pressure and flow conditions simulating turbine operation over the entire operating range including acceleration and loading. The design should achieve emissions at full load operation of <3 ppm NO_x and <10 ppm CO and UHC. Low emissions operation is expected over the 75–100% load range. In addition, long-term sub-scale rig test results are reported at simulated full load operating conditions including cyclic operation and full load trips.     

Development of a catalytic combustor for a heavy-duty utility gas turbine

Catalytic combustion is an attractive technology for gas turbine applications where ultra-low emission levels are required. Recent tests of a catalytic reactor in a full scale combustor have demonstrated emissions of 3.3 ppm NO_x, 2.0 ppm CO, and 0.0 ppm UHC. The catalyst system is designed to only convert about half of the natural gas fuel within the catalyst itself, thus limiting the catalyst temperature to a level that is viable for long-term use. The remainder of the combustion occurs downstream from the catalyst to generate the required inlet temperature to the turbine.

Catalyst development is typically done using subscale prototypes in a reactor system designed to simulate the conditions of the full scale application. The validity of such an approach is best determined experimentally by comparing catalyst performance at the two size scales under equivalent reaction conditions. Such a comparison has recently been achieved for catalysts differing in volume by two orders of magnitude. The performance of the full scale catalyst was similar to that of the subscale unit in both emission levels and internal temperatures. This comparison lends credibility to the use of subscale reactors in developing catalytic combustors for gas turbines.     

Achieving ultra low emissions in a commercial 1.4 MW gas turbine utilizing catalytic combustion

The drive to achieve low emissions from gas turbines has been an ongoing challenge for over 30 years with the reduction of NO_x levels representing the most difficult issue. Catalytic combustion represents the technological approach that can achieve the lowest level of NO_x, in the range of 3 ppm and lower depending on the combustion system design. The program to develop a catalytic combustion technology that can achieve ultra low levels of NO_x, CO and unburned hydrocarbons (UHCs), applicable to a wide range of gas turbine systems and with long term durability is described. The technological approach is to combust only a portion of the fuel within the catalyst with the remaining fuel combusted downstream of the catalyst allowing the catalyst to operate at a low temperature and thus obtaining good long term catalyst durability. This catalytic combustion approach is then applied to a 1.4 MW gas turbine to demonstrate feasibility and to obtain real field experience and to identify issues and areas needing further work. The success of this demonstration lead to a commercial combustor design. This combustor and the final commercial package is described and the performance specifications discussed.     

Development of a catalytically assisted combustor for a gas turbine

A catalytically assisted low NO_x combustor has been developed which has the advantage of catalyst durability. This combustor is composed of a burner section and a premixed combustion section behind the burner section. The burner system consists of six catalytic combustor segments and six premixing nozzles, which are arranged alternately and in parallel. Fuel flow rate for the catalysts and the premixing nozzles are controlled independently. The catalytic combustion temperature is maintained under 1000°C, additional premixed gas is injected from the premixing nozzles into the catalytic combustion gas, and lean premixed combustion at 1300°C is carried out in the premixed combustion section. This system was designed to avoid catalytic deactivation at high temperature and thermal or mechanical shock fracture of the honeycomb monolith. In order to maintain the catalyst temperature under 1000°C, the combustion characteristics of catalysts at high pressure were investigated using a bench scale reactor and an improved catalyst was selected for the combustor test. A combustor for a 20 MW class multi-can type gas turbine was designed and tested under high pressure conditions using LNG fuel. Measurements of NO_x, CO and unburned hydrocarbon were made and other measurements were made to evaluate combustor performance under various combustion temperatures and pressures. As a result of the tests, it was proved that NO_x emission was lower than 10 ppm converted at 16% O₂, combustion efficiency was almost 100% at 1300°C of combustor outlet temperature and 13.5 ata of combustor inlet pressure.     

Studies on improving the performance of rubber seed oil fuel for diesel engine with DEE port injection

Use of vegetable oils in diesel engines leads to a marginally inferior performance and higher smoke emissions due to their high viscosity and carbon residue. The performance of vegetable oils can be improved by injecting a small quantity of diethyl ether (DEE) along with air. The main objective of this study is to improve the performance, emission and combustion characteristics of a direct injection diesel engine fuelled with rubber seed oil (RSO) through DEE injection at different flow rates of 100, 150 and 200 g/h. A single cylinder diesel engine with rated output of 4.4 kW at 1500 rpm was converted to operate in the DEE injection mode. DEE was injected into the intake port during suction stroke, while rubber seed oil was injected directly inside the cylinder at the end of compression stroke. The injection timing of DEE was optimized for this mode of operation. Results indicate that the brake thermal efficiency of the engine improves from 26.5% with neat RSO to a maximum of 28.5% with DEE injection rate of 200 g/h. Smoke reduces from 6.1 to 4 BSU with DEE injection at the maximum efficiency flow rate. Hydrocarbon and carbon monoxide emissions are also less with DEE injection. There is an increase in the NO_x emission from 6.9 g/kWh to 9.3 g/kWh at the optimum DEE flow rate. DEE injection with RSO shows higher peak pressure and rate of pressure rise compared to neat RSO. Heat release rate indicates an increase in the combustion rate due to the reduced ignition delay and combustion duration with DEE injection.     

Test results of a catalytically assisted combustor for a gas turbine

A catalytically assisted ceramic combustor for a gas turbine was designed and tested to achieve low NO_x emissions. This combustor is composed of a burner and a ceramic liner. The burner consists of an annular preburner, six catalytic combustor segments and six premixing nozzles, which are arranged in parallel and alternately. In this combustor system, catalytic combustion temperature is controlled under 1000 °C, premixed gas is injected from the premixing nozzles to the catalytic combustion gas and lean premixed combustion over 1300 °C is carried out in the ceramic liner. This system was designed to avoid catalyst deactivation at high temperature and thermal shock fracture of the ceramic honeycomb monolith of the catalyst. A 1 MW class combustor was tested using LNG fuel. Firstly, NO_x emissions from the preburner were investigated under various pressure conditions. Secondly, two sets of honeycomb cell density catalysts and one set of thermally pretreated catalysts ware applied to the combustor, and combustion tests were carried out under various pressure conditions. As a result, it was found that the main source of NO_x was the preburner, and total NO_x emissions from the combustor were approximately 4 ppm (at 16% O₂) at an adiabatic combustion temperature of 1350 °C and combustor inlet pressure of 1.33 MPa.     

Industrial gas turbine combustion performance test of DME to use as an alternative fuel for power generation

DME (dimethyl ether, CH₃OCH₃) is both a good alternative fuel for transportation and power generation and an LPG substitute owing to its cleanliness, multi-source productivity and the ease with which it is transported. This study was conducted to verify whether DME is a good fuel for gas turbines and to identify potential problems in fuelling a commercial gas turbine with DME. In this study, the GE7EA gas turbine of the Pyong-tak power plant in Korea was selected as the target of DME application. Combustion performance tests were conducted by comparing DME with methane, which is a major component of natural gas. Most results of the combustion performance tests show that DME is very clean and efficient fuel for gas turbines. However, other results have shown that it is necessary to retrofit a fuel nozzle to the combustor in consideration of the combustion properties of DME in order to enhance the availability and reliability of DME fired gas turbines.     

Combustion of low-calorific waste liquids in high temperature air

Waste liquids with low-calorific values are not easy to burn. In this experiment, a furnace with a pair of burners for high-cycled alternate firing was utilized to burn the low-calorific value liquids. In a 1383 K furnace, 1173 K preheated air was achieved via these burners equipped with regenerators. It was observed that the alternate firing with highly preheated air was an effective way to ignite and burn the low-calorific value liquids. The preheated air temperature was higher than the auto-ignition temperature of the flammable mixture of the waste liquids. The combustion gas temperature in the furnace was quite uniform via the high-cycled alternate firing, resulting in a longer residence time of combustion in the furnace as compared to the conventional incinerator. The convective heat transfer in this furnace was higher than that of the conventional incinerator, and more useful energy was extracted from the waste liquids for end users. For the waste liquids with lower heating values of 15.0 MJ/kg (19 wt.% water) and 10.4 MJ/kg (42 wt.% water), it was found that 49% and 10% of the heating values of the waste liquids, respectively, could be used for utility energy. Furthermore, the waste liquid with a lower heating value of 7.1 MJ/kg (45 wt.% water) could burn itself in this furnace without the need of co-firing of any auxiliary fuels. NO_x and CO emissions were lower than 60 ppmv (6% O₂) and 50 ppmv (6% O₂), respectively, for all tests.     

废塑料聚氯乙烯中氯含量的测定

针对废塑料聚已烯样品，以氧瓶燃烧分散试样，碱液吸收，佛尔哈德法滴定。详细考查了有关的样品分解、气体吸收、试液滴定条件。方法应用于多种废弃塑料中氯的测定，与同类方法相比简便、快速。对大量含氯5％－50％的塑料样品分析结果令人满意。     

Engineering prediction of soot concentration in the primary zone of the gas turbine combustor

The trends towards using heavier fuel oil in the gas turbine engine will increase the soot formation rate in the primary zone, which increases flame radiation and impairs flame tube durability. Therefore, devising a method to determine quantitiatively the soot concentration is of paramount importance, as it helps in combustor design and pollution control. The method proposed adopts the Schmidt technique for radiation measurements together with soot formation and oxidation models. The soot concentration predictions from this method have been compared with those calculated from measurements of radiation in the primary zone and exhaust smoke at the combustor exit. Favourable comparison was achieved, especially under full load conditions.     

Physical-chemical properties of waste cooking oil biodiesel and castor oil biodiesel blends

This work presents the physical-chemical properties of fuel blends of waste cooking oil biodiesel or castor oil biodiesel with diesel oil. The properties evaluated were fuel density, kinematic viscosity, cetane index, distillation temperatures, and sulfur content, measured according to standard test methods. The results were analyzed based on present specifications for biodiesel fuel in Brazil, Europe, and USA. Fuel density and viscosity were increased with increasing biodiesel concentration, while fuel sulfur content was reduced. Cetane index is decreased with high biodiesel content in diesel oil. The biodiesel blends distillation temperatures T₁₀ and T₅₀ are higher than those of diesel oil, while the distillation temperature T₉₀ is lower. A brief discussion on the possible effects of fuel property variation with biodiesel concentration on engine performance and exhaust emissions is presented. The maximum biodiesel concentration in diesel oil that meets the required characteristics for internal combustion engine application is evaluated, based on the results obtained.     

Pyrolysis kinetics of waste automobile lubricating oil

The kinetics of waste automobile lubricating oil have been studied experimentally and modeled mathematically. Experiments were carried out in the tubing bomb microreactor at a temperature of 420–440°C and reaction times of 5–50 min. Volatile pyrolysis products were identified and quantitatively determined by gas chromotography. A lump model of combined series and parallel reactions for oil formation is proposed. Conversion data fitted first order kinetics for C₅–C₁₁ and C₁₂–C₂₅. The kinetic parameters were determined by nonlinear least-squares regression of the experimental data. These calculated values of the product distribution were found to be in agreement with the experimental data.     

Microwave assisted in continuous biodiesel production from waste frying palm oil and its performance in a 100 kW diesel generator

A household microwave (800W) was modified as a biodiesel reactor for continuous transethylation of waste frying palm oil. The high free fatty acid oil was simultaneously neutralized and transesterified with sodium hydroxide. With the ethanol to oil molar ratio of 12:1, 3.0% NaOH (in ethanol) and 30s residence time, the continuous conversion of waste frying palm oil to ethyl ester was over 97%. The waste palm oil biodiesel was then tested in a 100 kW diesel generator as a neat fuel (B100) and 50% blend with diesel No. 2 fuel (B50). The engine performance and emission are recorded. At the engine loads varied from 0 kW to 75 kW (at 25 kW intervals) of the maximum electrical rating, the performance of the neat and B50 are slightly lower than diesel No. 2 fuel. Emissions of NO_x, CO and HC from B100 and B50 are lower than those of diesel No. 2 fuel, except that at the 75 kW engine load, where the B100 emits higher levels of NO_x than the diesel No. 2 fuel.     

Combustion characteristics of droplets composed of light cycle oil and diesel light oil in a hot-air chamber☆

Development of gas turbines fueled with light cycle oil (LCO) and oil mixture of LCO and diesel light oil (LO) requires an understanding of the droplet burning and vaporization characteristics of those oils. The present study is devoted to comparing the burning characteristics of isolated fuel droplets composed of an LCO and an LO. The tests were conducted in an atmospheric hot-air chamber preset at 1173 K, and the examined LCO had a lower cetane number but higher volatility and aromatics content compared to LO. It was demonstrated that the burning of the LCO droplet was sootier, while that of the LO droplet was more disruptive. At the tested temperature, coke formation was indistinct for both the oils, whereas slightly higher ignition delay time was shown for the LO droplet. The microexplosive burning more or less complicated the time-series droplet size d, an explicit burning rate constant, however, was still definable according to the d²-law to show the overall regression speed of the droplet surface area d² with burning time t. The rate constant exhibited little difference for smaller LCO and LO droplets but was greater for LO when the droplet was larger. The rate constant also gradually increased with increasing the initial droplet diameter d₀, which caused the relative size d/d₀ to be unified (normalized) into a single curve by a burning time t/d₀ⁿ (1.0<n<2.0). Analysis revealed that this unification resulted from the respective overlaps of the unsteady and quasi-steady burning phases for differently sized droplets. Further, it was clarified that the unification and analysis are generally valid to isolated liquid fuel droplet burning in hot ambiences.     

高压蒸汽透平的油路系统防火

分析了蒸汽透平油路系统着火的原因 ,列举了其存在的缺陷 ,提出了具体的防火技术措施     

湿热法在废油脂处理中的应用

研究湿热法在废油脂处理中的应用,考察了温度、压力、时间和水用量等处理因素对实验结果的影响,确定了最佳处理条件,即：废油脂30g、水12g于100℃密闭湿热处理45min,所得油脂的品质明显改善,酸值由2．26mgKOH／g降为2．06nagKOH／g,碘值由73．84g／100g降为70．80g／100g,皂化值由200．27nagKOH／g升至204．39nagKOH／g。上述结果表明,经湿热法处理后的油脂更适合于生物柴油的制备。     

Test results of a catalytic combustor for a gas turbine

A catalytically assisted low NO_x combustor has been developed which has the advantage of catalyst durability. Combustion characteristics of catalysts at high pressure were investigated using a bench scale reactor and an improved catalyst was selected. A combustor for multi-can type gas turbine of 10 MW class was designed and tested at high-pressure conditions using liquefied natural gas (LNG) fuel. This combustor is composed of a burner system and a premixed combustion zone in a ceramic type liner. The burner system consists of catalytic combustor segments and premixing nozzles. Catalyst bed temperature is controlled under 1000°C, premixed gas is injected from the premixing nozzles to catalytic combustion gas and lean premixed combustion is carried out in the premixed combustion zone. As a result of the combustion tests, NO_x emission was lower than 5 ppm converted at 16% O₂ at a combustor outlet temperature of 1350°C and a combustor inlet pressure of 1.33 MPa.     

煤气初冷器余热回收新技术

开发了初冷器余热回收利用新技术。通过热泵机组,夏季回收初冷器上段循环水余热制取低温水,冬季回收初冷器中段循环水余热加热采暖水,实现了初冷器余热的综合利用,降低了能耗,改善了环境。     

Evaporation of single droplets of ethanol-fuel oil mixtures

Measurements of droplet evaporation behaviour are reported for mixtures of pure and denatured ethanol with No. 2 fuel oil. A model for the evaporation of droplets of these mixtures is presented which uses continuous thermodynamics to describe the fuel oil fraction. Activity coefficients were used to describe non-ideal phase equilibrium behaviour. Distribution function parameters for the fuel oil were fitted from a continuous thermodynamics simulation of the ASTM distillation test; this simulation was also used to test the accuracy of the phase equilibrium model. The model is shown to give very good agreement with the measurements. Internal boiling of the liquid is seen to take place during evaporation of the alcohol, but is not sufficiently violent to eject mass from the droplet.