Results are presented of the process of burning of sulfur-containing liquid fuels in a nonisothermal fluidized bed of a ShchKZ-1 industrial catalyst for the example of sulfurous and heavy high-sulfur oil. The optimal (“dropdown”) temperature profile in the bed was determined. This profile is characterized by a downstream decrease in temperature from 700 to 500°C. A mathematical simulation based on the description of experimental data on the variation of the sulfur concentration at the exit from the adsorbent (calcite) bed at its varied charge was used to calculate the specific capacity of the sorbent to be (14.2-15.9) x 103 g cm3. It was shown that the potential capacity of calcite in fluidized bed exceeds by an order magnitude that in a fixed bed.

Results of the studies of catalytic combustion of peat, anthracite, as well as the mixture at the peat to anthracite weight percent ratio 40/60 are discussed. The degree of the mixture burning-off was shown to increase when peat evolving large quantity of volatile substances is added to anthracite. The burn-up degrees of the solid fuel particles less than 1.25 mm in size were 98.2 % of peat, 50.9 % of anthracite, 74.2 % of the peat and anthracite mixture at 700–750 °C and 1 m height bed of the industrial aluminum-copper-chromium oxide catalyst IC-12-70. In combusting coarse particles (equivalent diameter 11.6–18.6 mm) of molded peat and anthracite mixture, the burn-up degree was 80.5 % at the top of the fluidized catalyst bed. The burn-up degree of the coarse particles fed to the bottom of the fluidized bed was estimated with allowance for the burn-up degree of fine particles moving through the bed. With the coarse molded particles of the peat and anthracite mixture fed to 1 m height catalyst bed, the burn-up degree was shown to reach no less than 95 %. When the catalyst used is 2 mm in size, the peat and anthracite particles comprised in the molded fuel must be no more than 1–1.5 mm in size in order to prevent from ash accumulation in the fluidized catalyst bed.

Oxidation of diesel fuel was studied using vibro-liquefied and fluidized beds of disperse bank sand in the presence of iron-containing microspheres isolated from flue ash of coal-fired boilers: ferrospheres and cenospheres activated with iron oxide. The obtained results are compared to the available data on oxidation of diesel fuel using microspheres of commercial catalysts for complete oxidation of organic compounds. Deeper oxidation of diesel fuel was observed at 500–600 °C in the presence of ferrospheres and cenospheres bearing iron oxide than in the vibro-liquefied bed of the inert material (bank sand). The most complete oxidation (84.3 %) was observed with ferrospheres at 700 °C. The ferrospheres were used for oxidation of diesel fuel in the fluidized bed of the inert material and they seemed less active under these conditions than the commercial catalysts based on СuСr2О4/Аl2О3and disperse Fe2O3. Nevertheless, the oxidation rate as high as 97.8 % can be achieved in the presence of ferrospheres by arranging jet fire above the bed. If so, the flame length decreases by half in comparison to the flame above the bed of the inert material. These observations, as well as a decrease in the proportion of CO and unburned carbon in combustion products indicate the catalytic activity of ferrospheres fed to the flame.

The work studied the catalytic combustion of heavy coal-tar products (HCTP) formed upon processing of Baltic shales to assess the efficiency of combustion in the presence of an Al-Cu-Cr oxide catalyst of complete oxidation of organic compounds with active component contents of 10 %, the optimum temperature modes of catalytic combustion were determined and an assessment of an opportunity for carrying out fuse combustion process in a boiling layer of a catalyst without using additional fuels was performed. It was demonstrated that the maximum degree of combustion of 97.7-97.8 % was reached at 700-750 degrees C. Herewith, the concentrations of harmful substances in exhaust gases were the following (ppm): CO 244-269; NOx 179-229; SO2 is absent. Based on the literature data on catalytic combustion of oil containing sulphur, it was demonstrated that the SO2 concentration at the outlet of the reactor could reach the value of 60 ppm during long-term operations of the setup for catalytic combustion of HCTP in autothermal mode considering the calcium oxide content in their mineral component. The carbon content in bottom ash amounted to 2.3-2.4 %. By the calcium oxide content, ash refers to basic fly ash and can be used as an additive to cement. Based on the results of catalytic combustion of HCTP in autothermal mode in a laboratory setup, emission of harmful substances in exhaust gases was determined using HCTP as fuels for a catalytic boiler-house with the air excess coefficient alpha = 1.2. Emissions of hazardous substances during combustion of HCTP do not exceed the value of maximum permissible emissions of each component right up to a background value of 0.9MPC.

The paper demonstrates an opportunity to determine the elemental composition of the combustible mass of plant biomass, peat, and fossil coal based on technical analysis findings followed by the assessment of the low heat value of solid fuel. This approach may be useful with the absence of elemental analysis findings and the lower heat of combustion of solid fuel. The content of carbon as the main element that forms the structure of solid fuel may be assessed via the yield of volatile matter, as demonstrated in the first case. Empirical dependencies of H-at/C-at and O-at/C-at ratios on carbon content in solid fuel, against which the low heat value of solid fuel with a sulphur content of no more than 2 % is calculated, are defined. Herewith, the deviation from the literature data did not exceed 10 %. The second option examines an opportunity to determine H-at/C-at and O-at/C-at at ratios via the yield of volatile matter. The low heat values of solid fuels with sulphur contents of no more than 2 % were calculated on the basis of the resulting empirical dependencies; herewith, the deviation from the known values does not exceed 6%.The use of the resulting empirical dependencies to define the low heat values of solid fuels with a sulphur content of 2.1-8.4 % in some cases, gives an increase in deviations from the literature data within 12-14 %.

Environmentally safe fuel combustion is an actual worldwide problem. The alternative technology of catalytic fuel combustion in fluidized bed of catalyst was developed in the Institute of Catalysis SB RAS. The technology allows one to conduct the process at 300-700 degrees C and significantly reduce outlet concentrations of toxic compounds. However, the use of sulfur oils as fuel demands solving a problem of the decreasing the outlet SO2 concentration because the oils contain small amount of ash to absorb SO2. The work is devoted to study features of sulfur light oil and high-sulfur heavy oil catalytic combustion in the fluidized bed of the Al-Cu-Cr-oxidic catalyst. It was shown that reduction of SO2 emission below the levels set by environmental regulations at conserving oxidation degree of oils within range of 99.5-99.8% may be reached by using a non-isothermal temperature profile in the reactor as well as a use of calcium carbonate or oxide at Ca/S > 2 to absorb sulfur oxides. The non-isothermal temperature profile in the reactor consisted of an oxidation zone with the temperature in the fluidized catalyst bed of 700 degrees C and a catalytic oxidation of SO2 to SO3 zone with equilibrium shift to reducing SO2 concentration because of the temperature change from 700 degrees C to 585 degrees C. The outlet NO concentration at the catalytic combustion of the oils also corresponded to the levels set by environmental regulations. (C) 2015 Elsevier B.V. All rights reserved.

Iron-containing catalysts for the deep oxidation were prepared by impregnation of a support (γ-Al2O3) with a solution of (NH4)3[Fe(C2O4)3] (sample FeOX FeOX/γ-Al2O3) or a solution of Fe(NO3)3 (sample FeNO FeOX/γ-Al2O3). The samples were studied by the BET method, XRD, XPS, and HREM. The catalyst activities were determined in the oxidation of CO: it was shown that the sample FeOX FeOX/γ-Al2O3is more active than the sample FeNO FeOX/γ-Al2O3. It is shown that the active component of the catalyst obtained with Fe(NO3)3 is α- Fe2O3, while the active component of the catalyst obtained with the solution of (NH4)3[Fe(C2O4)3] is a solid solution of Fe3+ in FeOX/γ-Al2O3. The sample FeOX FeOX/γ-Al2O3and industrial catalysts SHKZ-1 and IC-12-73 were tested in the combustion of brown Kansk-Achinsk coal in the fluidized bed. It is shown that the use of the sample FeOX FeOX/γ-Al2O3provides the high degree (95 %) of the lignite burning and reduces the CO emission as compared with the level obtained with an inert material.

The possibility of the environmentally friendly burning of sulfur crude oil in a fluidized catalyst bed is studied in order to use this method in an energy plant for local heat supply. Two types of oil are used in the experiments: sulfur and high-sulfur crude oil. The oils are combusted in a bed of aluminum–copper–chrome catalyst for the deep oxidation of organic compounds, and in a bed of inert material for comparison. The efficiency of sulfur crude oil combustion depends on the amount of toxic products in the combustion gas (CO, SO 2 and NO x ) and how complete the burning-out of organic components is. Calcite is used in a fluidized bed to remove SO 2 from flue gas. The burning of sulfur crude oil in a fluidized catalyst bed with calcite is shown to result in complete burning-out at relatively low temperatures (700°C) and excludes the presence of CO and SO 2 in the combustion gas. At the same time, the concentration of nitrogen oxides remains minimal and does not exceed environmental norms.

Calcite is used in the combustion of high-sulfur fuels to reduce emissions of SO2. However, at temperatures above 700 °С, calcite and resulting calcium sulfate begin to sinter, which negatively affects the binding of SO2and complicates the mathematical modeling of the process. Catalytic combustion reduces the maximal temperature of fuel combustion from 1200 °С to 700 °С, thereby reducing the sintering of materials and allowing the use of simpler model calculations. The aim of this work was to develop a simplified model of the observed kinetics of the process on the basis of experimental data obtained at 500–600 °С in a reactor with fixed-bed calcite. According to the model, the absorption of SO2 is the reaction of the second order (the first order with respect to the concentration of SO2 and the first order with respect to a number of free centers capable of binding SO2), and vacancy centers decreases linearly with an increase in the amount of absorbed SO2. Kinetic parameters of the model — the reaction rate constant and the ultimate capacity of calcite toward SO2 – were determined.

When burning high-sulfur fuels, calcite is added to a furnace to reduce SO2 emissions. Calcite and the resulting calcium sulfite start to cake above temperatures of 700°C, adversely affecting SO2 bonding and complicating the problem of mathematically simulating the process. The catalytic burning of fuel enables us to lower the maximum temperature of fuel combustion from 1200°C to 700°C. This reduces the caking of materials and allows the use of simple calculation models. The aim of this work is to create a simplified model of the kinetics of the observed process, based on experimental data obtained using a reactor with a fixed calcite bed at temperatures of 500–600°C. According to the model, SO2 absorption is a second-order reaction (first order with respect to SO2 and to free sites capable of SO2 bonding), and the fraction of free sites falls linearly as the quantity of absorbed SO2 grows. The kinetic parameters of the model are determined, i.e., the reaction rate constant and maximum calcite capacity with respect to SO2.

Calcite is used in the combustion of high-sulfur fuels to reduce emissions of SO2. However, at temperatures above 700 °С, calcite and resulting calcium sulfate begin to sinter, which negatively affects the binding of SO2and complicates the mathematical modeling of the process. Catalytic combustion reduces the maximal temperature of fuel combustion from 1200 °С to 700 °С, thereby reducing the sintering of materials and allowing the use of simpler model calculations. The aim of this work was to develop a simplified model of the observed kinetics of the process on the basis of experimental data obtained at 500–600 °С in a reactor with fixed-bed calcite. According to the model, the absorption of SO2 is the reaction of the second order (the first order with respect to the concentration of SO2 and the first order with respect to a number of free centers capable of binding SO2), and vacancy centers decreases linearly with an increase in the amount of absorbed SO2. Kinetic parameters of the model — the reaction rate constant and the ultimate capacity of calcite toward SO2 – were determined.

A catalytic method of combustion of a solid fuel in a fluidized bed is compared with a noncatalytic method. It is shown that the use of catalysts reduces the fuel consumption and sizes of heat generators approximately by an order of magnitude, while the specific load on the reactor volume increases by more than a factor of 20. Emission of toxic substances with fuel combustion products drastically decreases. Comparative stability of oxide non-platinum catalysts is estimated in the course of catalytic burning of the fuel with addition of an inert material. In burning fuels with a large content of sulphur, the maximum deactivation is found to occur within the first several tens of hours; this process is accompanied by sulphur accumulation in catalysts. Later on, the catalyst activity remains almost unchanged. It is found that a critical factor of catalyst stability is attrition resistance. The prospects of fuel burning in a layer of cermet honeycomb catalysts are demonstrated.

Catalysts based on transition metal oxides are the most promising for the efficient combustion of fuel in a fluidized bed. Afterburning coke is a limiting stage of fuel combustion, characterized by the release of carbon monoxide (CO) and its reacting with oxygen on the catalyst surface. Determination of the observed kinetic parameters of this process will further evaluate the efficiency of the catalyst, and optimize the performance of fluidized bed reactor. The study of the kinetics of CO oxidation on the industrial catalyst SCHKZ-1 (oxide aluminum-copper-chromium), currently used in the fluidized bed reactor when burning fuels. The studies carried out in conditions when the internal diffusion does not affect on the reaction rate. Kinetic parameters of the reaction were evaluated by a first order equation for CO and O2; the obtained values of activation energy and pre-exponential rate constants were respectively ko = 5,23·107 s–1, E = 32,8 kJ/mol. A comparison with published data showed their good correlation .

The process of methane combustion in a fluidized bed of spherical oxide catalyst containing mixed copper and magnesium chromite on toughened alumina (IK-12-73) depending on the temperature and the concentration of methane in the mixture with air was studied. It has been demonstrated that the conversion level of methane oxidation into CO2 in the case of the methane content equal to 2 % increases from 72 % at 500 degrees C to 99 % at 700 degrees N. Increasing the concentration of methane to 8 % does not causes reducing the conversion level of methane oxidation within the temperature range 600 -750 degrees C. It has been demonstrated that the concentration of nitrogen oxides in the course of methane combustion at the temperature values ranging within 500-750 degrees C does not exceed 3.5 ppm. The presence of H-2 and CO in the reaction mixture does not causes increasing the conversion level of methane oxidation when the volume ratio CH4/(CO + H-2) = 4 : 19.

The design and operation of catalytic solid fuel-flamed heat-generating units intended for local heating of industrial and municipal facilities are discussed. An advantage of these units is that their thermal power can be regulated between 0.5 and 10 Gcal/h and that they are capable of burning various types of solid fuels, including low-grade ones and waste, in an environmentally friendly way. Data characterizing the operation of an industrial-scale boiler plant with a thermal power of 3 Gcal/h are presented.

Features of the thermal decomposition (pyrolysis, steam reforming) of carbon-containing raw material in the vibro-liquefied bed of inert material and in the presence of the catalysts of deep oxidation were studied. It was shown that the presence of catalysts in wood pyrolysis ensures more complete transformation of condensable organic substances (resins) into light gaseous products (CO, H-2, CO2, CH4). For a model oxygen-containing organic substrate (glycerol), it was shown that the conversion of glycerol during its steam reforming in pseudo-liquefied bed of the catalysts of deep oxidation follows several routes including gasification with the formation of CO, H-2, CO2 and CH4, polycondensation of the products of glycerol dehydration with the formation of coke, steam gasification of coke. Similar processes are realized during the combustion of biomass at the stage of pyrolysis and gasification in the boiling bed. It was shown that efficient catalysts in the steam reforming of glycerol exhibit high activity in the process of oxidation of glycerol and biomass. Investigation of the process of catalytic combustion of aqueous solutions of glycerol showed that the degree of oxidation reaches 99.3-99.9 % with the use of the catalysts of deep oxidation. Oxidation process runs with the highest efficiency in the presence of PK-12-73 catalyst.

Pyrolysis of wood in vibro-fluidized beds of disperse packings of deep oxidation catalysts and inert materials is investigated. It is shown that the properties of the disperse packing material of vibro-fluidized beds do not have a significant effect on the rate and degree of conversion of wood to volatiles. The presence of catalysts in the vibro-fluidized bed leads to an increase in the amount of CO 2 , CO, H 2 , and CH 4 in the gas phase compared to the pyrolysis of wood in vibro-fluidized beds of inert materials. The greatest activity in the conversion of volatiles to CO 2 , CO, H 2 , CH 4 was found for the catalyst IK-12-73 (Mg 0.5 Cu 0.5 Cr 2 O 4 /Al 2 O 3 ). The accumulation of carbon in IK-12–73 catalyst has little effect on the conversion of volatile substances to gaseous products. The degree of burnout of wood particles under conditions of a vibro-fluidized bed of IK-12-73 catalyst is 99.7%, which is consistent with data on the catalytic combustion of wood in the fluidized bed.

A process was studied concerning the combustion of municipal wastewater sediments from sludge fields of the Gorvodocanal Co. (Novosibirsk), in the fluidized bed of a catalyst. It was found that at the process temperature of 700 degrees C, the burnout level of the sediment amounted up to 98 %. In this case, the content of toxic substances (Hg, HCl, SO3, P2O5, CO, NOx meets the sanitary standards. It was demonstrated that the combustion of sediments is possible after its preliminary drying up to obtaining the moisture level equal to 54 %. Key words: catalytic