Coal gasification process optimization for maximum calorific value and minimum CO2 emission using Taguchi method and utility concept

Two experimental simulations of underground coal gasification (UCG) processes, using large bulk samples of lignites, were conducted in a surface laboratory setup. Two different lignite samples were used for the oxygen-blown experiments, i.e., “Velenje” meta-lignite (Slovenia) and “Oltenia” ortho-lignite (Romania). The average moisture content of the samples was 31.6wt.% and 45.6wt.% for the Velenje and Oltenia samples, respectively. The main aim of the study was to assess the suitability of the tested lignites for the underground coal gasification process. The gas composition and its production rates, as well as the temperatures in the artificial seams, were continuously monitored during the experiments. The average calorific value of gas produced during the Velenje lignite experiment (6.4 MJ/Nm3) was much higher compared to the result obtained for the experiment with Oltenia lignite (4.8 MJ/Nm3). The Velenje lignite test was also characterized by significantly higher energy efficiency, i.e., 44.6%, compared to the gasification of Oltenia lignite (33.4%). The gasification experiments carried out showed that the physicochemical properties of the lignite used considerably affect the in situ gasification process. Research also indicates that UCG can be considered as a viable option for the extraction of lignite deposits; however, lignites with a lower moisture content and higher energy density are preferred, due to their much higher process efficiency.

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Experimental Study of Reverse Underground Coal Gasification

Energies ◽

10.3390/en11112949 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2949 ◽

Cited By ~ 1

Author(s):

Hongtao Liu ◽

Feng Chen ◽

Yuanyuan Wang ◽

Gang Liu ◽

Hong Yao ◽

...

Keyword(s):

Growth Rate ◽

Flame Front ◽

Oxygen Concentration ◽

Coal Gasification ◽

Calorific Value ◽

Injection Rate ◽

Underground Coal Gasification ◽

Gasification Process ◽

Combustible Gases ◽

Different Characteristics

Underground coal gasification (UCG) produces less pollution and is safer than traditional coal mining. In order to investigate the effects of different gasifying agents or comprehensive analyses of the characteristics of the gas components in the three zones for the reverse underground coal gasification process, a model test was carried out. The results showed that the oxygen concentration of a gasifying agent is recommended to be higher than 21%, which will lead to more combustible gases and a higher calorific value of gas. Higher flow rates and oxygen content generally afforded more desirable gas compositions and calorific values, with the latter as high as 1430.19 kcal/Nm3. For the enriched oxygen gasifying agent in the reverse gasification process, the flow increase from 10 to 20 Nm3/h affords a rapid increase in the growth rate of the flame front, from 1.80 to 4.88 m/day, which is much faster than that for the air gasifying agent. Increasing the gas injection rate and oxygen concentration will increase the growth rate of the flame front. This affects the distribution of the three zones and further leads to different characteristics of the gas components.

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Pemanfaatan gasifikasi batubara untuk unit pengeringan teh

Jurnal Teknik Kimia Indonesia ◽

10.5614/jtki.2006.5.2.6 ◽

2018 ◽

Vol 5 (2) ◽

pp. 443

Author(s):

Ari Susandy Sanjaya ◽

S Suhartono ◽

Herri Susanto

Keyword(s):

Coal Gasification ◽

Fixed Bed ◽

Calorific Value ◽

Diesel Oil ◽

Fuel Oil ◽

Dual Fuel ◽

Processing Unit ◽

Producer Gas ◽

Downdraft Gasifier ◽

Gasification Process

Coal gasification utilization for tea drying unit. Anticipating the rise of fuel oil, the management of a tea plantation and drying plant has considered to substitute its oil consumption with producer gas (gaseous fuel obtained from gasification process). A tea drying unit normally consumes 70 L/h of industrial diesel oil and is operated 10 hours per day. The gasification unit consisted of a down draft fixed bed gasifier (designed capacity of about 100 kg/h), gas cooling and cleaning systems. The gas producer was delivered to the tea processing unit and burned to heat the drying oil: Low calorific value coal (4500 kcal/kg) and wood waste (4000 kcal/kg) have been used as fuel. The gasification unit could be operated as long as 8 hours without refueled since the coal hopper on the toppart of gasifier has a capacity of 1000 kg. Sometimes, the gasification process must be stopped before coal completely consumed due to ash melting inside the gasifier. Combustion of producer gas produced a pale-blue flame, probably due to a lower calorific value of the producer gas or too much excess air. Temperature of heating-air heated by combustion of this producer gas was only up to 96 oC. To achieve the target temperature of 102 oC, a small oil burner must he operated at a rate ofabout 15 L/h. Thus the oil replacement was about 78%.Keywords: Fuel oil, Producer gas, Downdraft gasifier, Dual fuel, Calorific value, Burner. AbstrakKenaikan harga bahan bakar minyak untuk industri pada awal 2006 telah mendorong berbagai pemikiran dan upaya pemanfaatan bahan bakar alternatif. Sebuah unit gasifikasi telah dipasang di pabrik teh sebagai penyedia bahan bakar alternatif. Unit gasifikasi tersebut terdiri dari gasifier, pendingin, pembersih gas, dan blower. Unit gasifikasi ini ditargetkan untuk dapat menggantikan konsumsi minyak bakar 70 L/jam. Gasifier dirancang untuk kapasitas 120 kg/jam batubara, dan memiliki spesifikasi sebagai berikut: downdraft gasifier; diameter tenggorokan 40 cm, diameter zona reduksi 80 cm. Bunker di bagian atas gasifier memiliki kapasitas sekitar 1000 kg batubara agar gasifier dapat dioperasikan selama 8 jam tanpa pengisian-ulang. Bahan baku gasifikasi yang telah diuji-coba adalah batuhara kalori rendah (4500 kcal/kg) dan limbah kayu (4000 kcal/kg). Gas produser (hasil gasifikasi) dibakar pada burner untuk memanaskan udara pengering teh sampai temperatur target 102 oC. Pembakaran gas produser ternyata menghasilkan api biru pucat yang mungkin disebabkan oleh rendahnya kalor bakar gas dan tingginya udara-lebih. Temperatur udara pengering hasil pemanasan dengan api gas produser hanya mencapai 96 oC. Dan untuk mencapai temperatur udara pengering 102 oC, burner gas prod user harus dibantu dengan burner minyak 15 L/jam. Jadi operasi dual fued ini dapat memberi penghematan minyak bakar 78%.Kata kunci: Minyak bakar, Gas produser, Downdraft gasifier, Dual fuel, Kalor bakar, Burner.

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Quality assessment of gas produced from different types of biomass pellets in gasification process

Energy Exploration & Exploitation ◽

10.1177/0144598719875272 ◽

2019 ◽

Vol 38 (2) ◽

pp. 406-416 ◽

Cited By ~ 2

Author(s):

Marcel Mikeska ◽

Jan Najser ◽

Václav Peer ◽

Jaroslav Frantík ◽

Jan Kielar

Keyword(s):

Gas Turbines ◽

Combustion Engine ◽

Calorific Value ◽

Internal Combustion ◽

Combustion Gas ◽

Gas Cleaning ◽

Gasification Process ◽

Different Types ◽

Before And After ◽

Cleaning Technology

Gas from the gasification of pellets made from renewable sources of energy or from lower-quality fuels often contains a number of pollutants. This may cause technical difficulties during the gas use in internal combustion gas engines used for energy and heat cogeneration. Therefore, an adequate system of gas cleaning must be selected. In line with such requirements, this paper focuses on the characterization and comparison of gases produced from different types of biomass during gasification. The biomass tested was wood, straw, and hay pellets. The paper gives a detailed description and evaluation of the measurements from a fix-bed gasifier for the properties of the produced gases, raw fuels, tar composition, and its particle content before and after the cleaning process. The results of elemental composition, net calorific value, moisture, and ash content show that the cleaned gases are suitable for internal combustion engine-based cogeneration systems, but unsuitable for gas turbines, where a different cleaning technology would be needed.

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Conventional and Alternative Sources of Thermal Energy in the Production of Cement—An Impact on CO2 Emission

Energies ◽

10.3390/en14061539 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1539

Author(s):

Karolina Wojtacha-Rychter ◽

Piotr Kucharski ◽

Adam Smolinski

Keyword(s):

Co2 Emissions ◽

Co2 Emission ◽

Alternative Fuels ◽

Carbon Dioxide Emission ◽

Calorific Value ◽

Production Costs ◽

Partial Substitution ◽

Research Activities ◽

Starting Point ◽

Clinker Production

The article evaluates the reduction of carbon dioxide emission due to the partial substitution of coal with alternative fuels in clinker manufacture. For this purpose, the calculations were performed for seventy waste-derived samples of alternative fuels with variable calorific value and variable share in the fuel mixture. Based on annual clinker production data of the Polish Cement Association and the laboratory analysis of fuels, it was estimated that the direct net CO2 emissions from fossil fuel combustion alone were 543 Mg of CO2 per hour. By contrast with the full substitution of coal with alternative fuels (including 30% of biomass), the emission ranged from 302 up to 438 Mg of CO2 per hour, depending on fuel properties. A reduction of 70% in the share of fossil fuels resulted in about a 23% decrease in net emissions. It was proved that the increased use of alternative fuels as an additive to the fuel mix is also of economic importance. It was determined that thanks to the combustion of 70% of alternative fuels of calorific value from 15 to 26 MJ/kg, the hourly financial profit gain due to avoided CO2 emission and saved 136 megatons of coal totaled an average of 9718 euros. The results confirmed that the co-incineration of waste in cement kilns can be an effective, long-term way to mitigate carbon emissions and to lower clinker production costs. This paper may constitute a starting point for future research activities and specific case studies in terms of reducing CO2 emissions.

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Changes in properties of tar obtained during underground coal gasification process

International Journal of Coal Science & Technology ◽

10.1007/s40789-021-00440-6 ◽

2021 ◽

Author(s):

Marian Wiatowski ◽

Roksana Muzyka ◽

Krzysztof Kapusta ◽

Maciej Chrubasik

Keyword(s):

Coal Gasification ◽

Coal Tar ◽

Liquid Product ◽

Coke Oven ◽

Underground Coal Gasification ◽

Gasification Process ◽

Dominant Component ◽

Process Gas ◽

High Volatility ◽

Product Separator

AbstractIn this study, the composition of tars collected during a six-day underground coal gasification (UCG) test at the experimental mine ‘Barbara’ in Poland in 2013 was examined. During the test, tar samples were taken every day from the liquid product separator and analysed by the methods used for testing properties of typical coke oven (coal) tar. The obtained results were compared with each other and with the data for coal tar. As gasification progressed, a decreasing trend in the water content and an increasing trend in the ash content were observed. The tars tested were characterized by large changes in the residue after coking and content of parts insoluble in toluene and by smaller fluctuations in the content of parts insoluble in quinoline. All tested samples were characterized by very high distillation losses, while for samples starting from the third day of gasification, a clear decrease in losses was visible. A chromatographic analysis showed that there were no major differences in composition between the tested tars and that none of the tar had a dominant component such as naphthalene in coal tar. The content of polycyclic aromatic hydrocarbons (PAHs) in UCG tars is several times lower than that in coal tar. No light monoaromatic hydrocarbons (benzene, toluene, ethylbenzene and xylenes—BTEX) were found in the analysed tars, which results from the fact that these compounds, due to their high volatility, did not separate from the process gas in the liquid product separator.

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