Low-grade Coal Research Articles

99/01432 Coal and biomass co-combustion on fluidized bed: comparison of circulating and bubbling fluidized bed technologies : Armestro, L. et al. Proc. Int. Conf. Fluid. Bed Combust., 1997, 14, (1), 301–311

The main objective of the proposed paper is to demonstrate the technical feasibility of fluidized bed as a clean technology for the combustion of low grade coal/biomass blends. The raw materials used as fuels in the tests are different blends of the following materials: refuse coal with a heating value of 3,658 kJ/kg (LHV, db) and 79.65% ash content; low grade coal--lignite with a heating value of 19952 kJ/kg (LHV, db), a sulfur content of 10.32% (db) and 23.70% ash content; and biomass--forestry wastes from wood cleaning whose heating value is 19555 kJ/kg (LHV, db). An absorbent, limestone, has been used for reducing sulfur emissions. Co-combustion tests, at the pilot plant level, have been carried out by using two fluidized bed technologies, circulating and bubbling. The object of this paper is to study, in an energy and emission point of view, the clean and efficient use of these resources. The paper collects, analyses and compares combustion test data.

99/00944 Development of modification process and slurrification technology for upgrading low grade coals : Usui, H. Kemikaru Enjiniyaringu, 1998, 43, (7), 498–503. (In Japanese)

99/00944 Development of modification process and slurrification technology for upgrading low grade coals : Usui, H. Kemikaru Enjiniyaringu, 1998, 43, (7), 498–503. (In Japanese)

Adsorption of Phenol from Aqueous Solutions by Oxidized and Solvent-Extracted Residual Coal

Studies on the adsorption of phenol from aqueous solution by using pretreated noncoking low-grade bituminous coal are reported. The coal showed better adsorption after oxidation for more than 6h. Extraction with quinoline and ethylenediamine also showed a remarkable increase in phenol adsorption. However, the coupling of oxidation and solvent extraction did not seem to help in improving the adsorption. The particle size of the coal showed no relation to the degree of oxidation, or to the period of adsorption. The solvent-extracted residual coal showed almost 43% adsorption of phenol, which was equivalent to that observed for activated carbon. Adsorption of phenol on low-grade coals or on residual coals obtained after solvent extraction (organosolvo-refining) may upgrade those fuels. Further studies may be required before using the phenol-adsorbed coal/solvent-extracted residual coal as a fuel.

A Novel Pulverized Coal Fired Burner

A novel pulverized coal fired burner, called “main burner with double primary air channels for pulverized coal”, is presented in this paper. Such a burner can burn various kinds of coals, including bituminous coal, low grade coal, lignite, semianthracite, anthracite, satisfying stability of combustion, controllability of the ignition location of pulverized coal, high efficiency, and low NO x , emission, thereby eliminating the unstable combustion caused by variation of coal quality and low load operation. It has not only solved the problem of low load operation and the combustion without oil assisting of Jiafu anthracite, which is the most difficult coal to burn in China, but also first successfully conducted the normal combustion in a tangentially pulverized anthracite fired furnace, as in a W-shaped flame furnace. According to the low load test on a tangentially pulverized coal fired furnace of 1025 t/h of anthracite combustion, its stability is superior to that of a W-shaped flame furnace with the same capacity, they will compete with each other in the future in China. This burner has been applied in the furnace of large scale, medium-and small-sized power stations in China, and even taken as finalized design for large tangentially low-volatile pulverized coal fired furnaces in Harbin Boiler Works, the biggest one in China. Also if used in W-shaped flame furnaces, it can further improve their combustion performance and reduce the steel consumption.

98/04029 Fluidized bed combustion of low grade coals and biomass

98/04029 Fluidized bed combustion of low grade coals and biomass

Organic solvent effects on waste plastics–lignite coliquefaction

The disposal of municipal solid waste (MSW) is currently one of the main environmental concerns especially in the industrialized regions. Converting the organic fraction of MSW into useful products, e.g. gas and liquid fuels, seems to be an option of a great interest both environmentally and economically. This paper examines the results of coliquefaction of low-grade coal, e.g. lignite, with post-consumer plastics. Special catalysts were prepared for this purpose and tested along with different types of organic solvents. The presence of these solvents during the coliquefaction process almost doubled total solids conversion into gas and liquid products. Decane and toluene were found to be the best organic solvents for coliquefaction of lignite with high density polyethylene (HDPE) and polystyrene, respectively. Total solids conversion reached almost 90% when a two-stage process was employed.

98/02690 Physical and chemical generalities and ecological aspects for oil agglomeration process of low-grade coals: Biletskyi, V. S. et al. DGMK Tagungsber., 1997, 9702, (Proceedings ICCS '97, Volume 1), 499–5502

98/02690 Physical and chemical generalities and ecological aspects for oil agglomeration process of low-grade coals: Biletskyi, V. S. et al. DGMK Tagungsber., 1997, 9702, (Proceedings ICCS '97, Volume 1), 499–5502

98/02014 Simultaneous processing of solid wastes and low-grade coals : Katagiri, K. Jpn. Kokai Tokkyo Koho JP 09,316,466 [97,316,466] (Cl. C10L1/32), 9 Dec 1997, Appl. 96/129,968, 24 May 1996, 6 pp. (In Japanese)

98/02014 Simultaneous processing of solid wastes and low-grade coals : Katagiri, K. Jpn. Kokai Tokkyo Koho JP 09,316,466 [97,316,466] (Cl. C10L1/32), 9 Dec 1997, Appl. 96/129,968, 24 May 1996, 6 pp. (In Japanese)

Low cost adsorbents for low temperature cleaning of flue gases

The adsorption capacity with regard to SO 2 of chars prepared from a low-grade coal has been evaluated at typical conditions of flue gas (presence of oxygen and water vapour and linear gas velocity of 0.12 m s −1) at an inlet concentration of 2 g SO 2 m −3. The flue gases have been simulated, varying the water vapour and oxygen contents as well as the adsorption temperature which was varied between 80°C and 150°C. The study has focused on the influence of several process variables as well as the intrinsic features of the chars, such as their porous texture, on the SO 2 adsorption capacity of the chars. Under the conditions studied, the positive effect of water vapour in the absence of oxygen has been observed. This effect can be explained by the intervention of oxygen functionalities in chars. Hero two effects overlap: the oxygen present in chars and their surface chemistry as well as the porous structure available. Temperature is also an important parameter in the SO 2 adsorption efficiency. A minimum surface area is required for the temperature effect to be observed; otherwise the catalytic oxidation of SO 2 to SO 3 and subsequent storage of H 2SO 4 takes place to a very small extent and the negative effect of temperature increase to 150°C is not appreciable.

Process Simulation of Desulfurization from Pyrite by Thiobacillus ferrooxidans in a Packed-Bed Medium-Recirculating Bioreactor under Different Recirculation Rates

Effect of medium-recirculation rate on desulfurization of pyrite by Thiobacillus ferrooxidans in a packed-bed bioreactor was examined for developing an efficient on-site desulfurization process of low grade coal. Linear relationship between elution rate of SO42- and oxygen supply rate indicated that desulfurization rate was limited by dissolved oxygen (DO) supply which was dependent on the recirculation rate. Based on these results, a mathematical model consisting of DO limitation and product inhibition was constructed and satisfactorily simulated the performance in the on-site type desulfurization process.

98/02188 Carbohydrate biofuels. II. The need and the potential for root-fuel in the Navajo nation

Over 80% of rural Navajos and about two-thirds of all Navajos use scarce woodfuel and low-grade coal for home heating half the year, with coal used mainly as a nighttime adjunct. Serious health problems arise because stoves are old and leak smoke and carbon monoxide. The impacts are gender-biased to women and small children. Respiratory disease is a major cause of Navajo mortality and unusually high admissions to Navajo Indian Health Service hospitals. A 1990 study at a Navajo hospital showed that Navajo children under two years of age from homes with woodstoves are nearly five times more likely to contract acute lower respiratory tract infections than children from homes with no stove. Correctives include improved stoves and fuels. Our previous studies on clean-burning starchy/cellulosic {open_quotes}rootfuels{close_quotes} in Latin America, Africa, and Asia are applicable. We discuss our preliminary work on the Navajo reservation, the current status of household stoves and stovefuels, the health impacts of woodsmoke and coalsmoke from old, faulty stoves, the conditions for growing rootfuel on the reservation, and policy and strategy for coping with the problem.

炭層の品位分布を考慮した長壁式採炭に対する数理計画モデル

The purpose of the present study was to develop a mathematical model for effective operation of a longwall working face in an underground coal mine. The model can evaluate the relationship between operating efficiency and working height of the face in a coal seam. The results show that, contrary to a common thought, the working height of the face must be 20-30 % lower than the thickness of the coal seam. As a consequence, low-grade coal near the bed and roof rock remains in the coal seam. The results of this model enable effective operation of the working face and maximum profit in a mine.

98/00606 Blowing gasification products of low-grade coal to decrease the coke consumption in iron smelting

98/00606 Blowing gasification products of low-grade coal to decrease the coke consumption in iron smelting

An analytical electron microscope study of airborne industrial particles in Sosnowiec, Poland

The types and the relative amounts of airborne particles in the city of Sosnowiec (Poland) during 21–22 June, 1994 were identified by analytical electron microscope analyses. They are mostly aspherical angular Al-bearing silica particles (0.1–5.15 μm) and clusters thereof. Carbonaceous particles form sheets of soluble volatile-rich materials (0.3–33.9 μm) and rare soot. Numerous nanometer-sized Al-bearing silica grains and salt minerals are associated with the larger particles. They resulted from inefficient combustion of low-grade coals by the local industries whereby the silica particles are coal impurities that survived combustion. The total particle emission was constant during a 24 h period but silica shards dominated the nighttime emission while carbonaceous particles abounded during the daytime. This study showed that tropospheric particles in regions dominated by inefficient coal combustion are fundamentally different from typical coal fly ash spheres.

97/02148 Fluidized bed combustion of solid organic wastes and low-grade coals: research and modeling

Experimental studies were carried out to investigate devolatilization and combustion of single spherical particles of wood, hydrolytic lignin from ethanol production, leather processing sewage sludge, and low-grade Belarusian brown coals in a fluidized bed of sand. A two-phase model of fluidized bed combustion of biowaste is proposed. The model takes into account combustion of both volatiles and char in the bed as well as in the freeboard. Experimentally obtained characteristics of devolatilization and char combustion are used as parameters of the model proposed.

97/00933 New development of F- synthesis: MFT industrial test status

This paper is concerned with the development of a novel process for the production of a gas rich in hydrogen and carbon monoxide by means of pressure gasification of pulverized brown coal. In the future, this process will be mainly utilized for the gasification of low grade coal, i.e. high-ash and salt-containing brown coal. The technology, including test plants already constructed, are described in this paper. The commissioning of a large-scale plant at VEB Gaskombinat Schwarze Pumpe was the first step towards the industrial use of this process, which can also be applied to pulverized hard coal and coke dust.

97/00927 Method for upgrading a hydrocarbon gas containing a hydrocarbon and sulfur species by cracking against the regenerated sorbent

This paper is concerned with the development of a novel process for the production of a gas rich in hydrogen and carbon monoxide by means of pressure gasification of pulverized brown coal. In the future, this process will be mainly utilized for the gasification of low grade coal, i.e. high-ash and salt-containing brown coal. The technology, including test plants already constructed, are described in this paper. The commissioning of a large-scale plant at VEB Gaskombinat Schwarze Pumpe was the first step towards the industrial use of this process, which can also be applied to pulverized hard coal and coke dust.

97/00929 Mixed fuel processing plant ‘Schwarze Pumpe’ in Germany for processing waste lignite products. A successful year of operation

This paper is concerned with the development of a novel process for the production of a gas rich in hydrogen and carbon monoxide by means of pressure gasification of pulverized brown coal. In the future, this process will be mainly utilized for the gasification of low grade coal, i.e. high-ash and salt-containing brown coal. The technology, including test plants already constructed, are described in this paper. The commissioning of a large-scale plant at VEB Gaskombinat Schwarze Pumpe was the first step towards the industrial use of this process, which can also be applied to pulverized hard coal and coke dust.

97/00402 Study on preparation of nitro-humic acid from low grade coal oxidized with nitric acid

97/00402 Study on preparation of nitro-humic acid from low grade coal oxidized with nitric acid

A method of determining thermal parameters of granular coal particles during devolatilization

Fluidized bed combustion offers great potential for the utilization of high-sulphur coal and low-grade coal in an environmentally acceptable manner. Utilization of fluidized bed technology, especially for the combustion of low quality lignites, enables pollutant emission control as well as efficient combustion. The most important stage during the combustion of coal particles is devolatilization, in which various factors such as heat transfer from the surroundings to the particle surface, heat conduction within the particle, the chemicals involved, the kinetics and the transport of volatile compounds within the particle play significant roles. The heat transfer coefficient, thermal diffusivity, thermal conductivity, heating coefficient and lag factor are the most significant thermal parameters in this process. In this study, a 1-D transient heat transfer analysis is carried out for a granular coal particle during devolatilization in a fluidized bed. The particle is idealized as a spherical solid body. Models are developed to determine the thermal parameters of such particles, and are verified using experimental centre temperatures of a 10mm granular coal particle subjected to devolatilization at a medium temperature of 960K. The data are taken from the literature. The results show that the thermal parameters determined here are in good agreement with experimental findings.