Experimental Investigation on Co-Combustion Characteristics of Bituminous Coal and Semi-coke Blends in a 660 MW Utility Boiler
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With the rapid development of the low-rank coal chemistry industry, the production of semi-coke has ever been increasing.However, the semi-coke is difficult to burnout and the NOx generation during semi-coke combustion is high.Therefore, the co-combustion of semi-coke and bituminous coal in utility boiler is considered as a promising approach to realize the efficient utilization of the semi-coke.Here, the cocombustion features of bituminous coal and semi-coke blends were investigated in a 660 MW utility boiler.The results show that the NOx generation decreases firstly and then increases with the rises of the load and the fraction of semi-coke.The effects of load and blending ratio of semi-coke are both obvious on burnout behavior than those on NOx generation.With the rise of oxygen concentration, the NOx generation rises and the unburned carbon in fly ash decreases.The Na-bearing mineral are better-preserved with the higher oxygen concentration.The experimental results may provide guidance for the realization of the utilization of the semicoke in the utility boiler.Keywords:
Bituminous coal
The CFB boilers located in Longyan and Jinjiang in the province of Fujian, was originally designed to burn anthracite. Recently, a research was carried out to study the adaptability of coal type by burning Shenhua bituminous coal in this unit. It showed that the temperature of bed and exhaust gas would not change signally after the change of coal type. Both of the coals share similar ash characteristics. But the use of Shenhua bituminous coal can reduce the carbon content in the fly ash and the auxiliary power rate, thus improving the economic operation of boiler. As for the pollutant, Shenhua bituminous coal brought less dust emission and more NO x . On the whole, change of the coal type is beneficial to the economic operation of the plant. The study can provide valuable references for similar type units on how to expand coal sourcing channels and reduce plant cost.
Anthracite
Bituminous coal
Adaptability
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The co-zcarbonization tests on between coal and coal asphalt,as well as tests on coking with additon of coal asphalt into the 20 kg coke oven have been conducted. Results indicate that the coal asphalt has certain effects upon modification of the coal used in WISCO and adding of this material is a help to the improvement of coke strength.
Bituminous coal
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Combining with lignite features this article analyzes the influence of bituminous coal boiler mix burning with lignite coal to boiler proper and auxiliary equipments,and concludes technical points of bituminous cal boiler mix burning with lignite coal.
Bituminous coal
Hard coal
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This paper presents the influence of fuel quality as related to converting a typical 400 MW oil fired boiler to fire coal. A table shows the coal analyses selected for this evaluation. These analyses, one of an eastern bituminous coal and the other of a western sub-bituminous col, exemplify the broad range of coal qualities which are encountered in coal conversion analyses and to which specific boiler design parameters are addressed. An evaluation for coal fired unit derating is followed by consideration for auxiliary equipment required for coal firing.
Bituminous coal
Clean coal technology
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Taking a bituminous coal fired 350 MW unit boiler as the object,experiment of co-combustion with different proportions of lignite premixed on coal convey belt was conducted.The safety,economy and environmental protection characteristic of the pulverizing and combustion system under different blending proportion of lignite conditions were investigated.The results showed that,after co-firing with the Zha coal,drying capacity that the pulverizing system needed increased dramatically,and the blending proportion of Zha coal should not be larger than 50% for each boiler.With an increase in the Zha coal proportion,the reheat steam temperature rose obviously,the exhaust temperature and ash combustible content increased,and the boiler efficiency dropped.When the proportion of Zha coal reached 3/8,the NOx emission dropped by about 24.7%.When co-firing the Zha coal with Dayou coal,proportion of less than 3/8 will not aggravate the slagging occurred in burner area and high temperature convective heating surface area.
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Fluidized bed combustion
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The activation of power plant boiler for the w-shaped flame boiler, the original design for anthracite, mixed burning bituminous coal. Since mixed burning bituminous coal, repeatedly coke extinguishing, causing unplanned shutdown. This paper using the inhibition of coking chamber of a stove or furnace and coking prevention measures in advance to the greatest extent, prevent break coke furnace. And through continuous experiment bituminous coal blending ratio, the boiler burner band renovation, eventually reduce coking chamber of a stove or furnace coke and breaks down, can effectively improve the power plant safe operation and economic benefits.
Anthracite
Stove
Bituminous coal
Delayed coker
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This paper discusses the effect of co-firing on system's operation and emission by experimental analysis.The results show that comparing with coal,biomass(rice husk) has lower combustion temperature and faster firing rate,when co-firing with bituminous coal,the combustion temperature decreases and the firing rate boosts up,which result in a better characteristic of burnout,increase of the value in use of biomass and reduction of emissions comparing with coal combustion.
Bituminous coal
Cofiring
Husk
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This paper presents a thermogravimetric analysis and combustion test for different coals used in a coal-fired power plant in Malaysia. The main objective is to investigate the suitability of adopting a newly-introduced sub-bituminuous coal in an existing boiler furnace commonly firing standard design coals. In order to ensure that the new coal will not give an adverse effect to the boiler, detail analytical and thermal performance of the new coal is investigated, together with design and other limiting coals. The combustion test was performed in a scaled down, 150kW, single swirl burner combustion test facility available in TNB Research Sdn. Bhd. In the study, combustion gas temperature at different sectors downstream of burner region is measured to determine the peak temperature for all tested coals. Based on the investigation, it was noted that coal with the highest fixed carbon content gives the highest temperature measure at all sectors. Similarly, coal with the lowest fixed carbon gives the lowest temperature. The temperature profile for the newly tested coal was found to be comparable to the design and limiting value coals. Even though it was observed that the temperature given by the new coal is the highest slightly downstream of the burner, the temperature was observed to be decreases as combustion gas flow downstream of the combustor rig. Based on the observation it can be said that the new coal is suitable to be used by the existing boiler furnace.
Bituminous coal
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In continuation of our previous study on production of high-strength metallurgical coke from torrefied softwood (cedar), we studied coke production from a mixture of torrefied cedar (TC) and noncaking coal by pulverization to sizes <100 μm, mixing, binderless hot briquetting, and carbonization. These sequential processes produced coke with a tensile strength of 5–17 MPa, which was equivalent to or greater than that of conventional coke (5–6 MPa), from TC-coal mixtures over the entire ranges of TC mass fraction in briquette of 0–100%, torrefaction temperature of 250–300 °C, and choice of coal (sub-bituminous or medium-volatile bituminous coal). The mixing of TC and coal hindered densification of coke due to hindrance of shrinkage of more-shrinkable TC-derived particles during the carbonization under many of the conditions. Nevertheless, positive synergy occurred in the coke strength at TC mass fractions of over 50%, where coal-derived particles were dispersed in the matrix of TC-derived particles, bonded to them during the carbonization, and behaved as a reinforcement of the matrix. The bonding between TC-derived and coal-derived primary particles was revealed by scanning electron microscopy. Copulverization of mixed TC and coal to sizes <40 μm before the briquetting gave cokes having strengths as high as 23–28 MPa. The fine pulverization increased the frequencies of mutual bonding of TC-derived particles and coal-derived particles and bonding between TC-derived and coal-derived particles per coke volume. The strength of coke from the TC-coal mixture generally followed volume-based additivity of strengths of cokes from TC and coal. This was realized by mixing primary particles of TC and coal within ≈10 μm scale or even smaller.
Bituminous coal
Briquette
Anthracite
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