RU2749063C1 - Installation for catalytic combustion of fuel in form of sewage sludge from municipal treatment plants and method for its combustion - Google Patents

Abstract

FIELD: waste disposal.

SUBSTANCE: invention relates to devices and methods for the disposal of wet sludge from municipal treatment plants. The invention relates to an installation for the catalytic combustion of fuel in the form of sewage sludge. The installation includes a catalytic reactor, in which a nozzle for supplying the catalyst is located in the upper part of the case, and under the cover with the flue gas outlet pipe, there is a bump stop made in the form of a hollow truncated cone, fixed to the reactor case down with a base with a smaller diameter, in which a pyramidal tetrahedral tip is fixed with a top down with a diagonal of the base greater than the diameter of the smaller base of the truncated cone of the bump stop, thus, that gaps are formed between the plane of the tip base and the plane of the smaller base of the truncated cone of the bump stop. In the lower part of the case of the catalytic reactor, in the oxidation zone, there are two diametrically opposite pipes for supplying sewage sludge, in each of which a water supply pipe is welded. Between the catalyst removal pipe and the zone of discharge of unburned sludge components with a discharge screw, there is an air distribution device, which consists of two external distribution collectors located in the same plane and parallel to each other at diametrically opposite walls of the reactor case, with three circular pipes extending from each collector through the knees with perforation holes in the lower part of the wall, each of which is welded into the reactor case and the free welded end of each of them is inserted into a cup welded externally into the reactor case from the opposite side from the knee. All the perforated pipes are located parallel in the same plane and installed with gaps between them. The perforated part of the pipe is located inside the reactor case. The total area of the perforation holes in the pipes is 2.5 % of the cross-sectional area of the lower part of the reactor case. The installation includes a blower and a heat generator connected in series to the catalytic reactor by means of an air supply line, and a recuperator, an economizer, a bag filter, a wet vortex scrubber, a high-pressure fan and a chimney connected in series to the catalytic reactor by means of a gas discharge line. It also includes a solid fuel supply system - a flow hopper with a screw dispenser and a hopper for unloading non-combustible components of sewage sludge. The invention also concerns a method for combusting fuel in the form of sewage sludge.

EFFECT: technical result is uniform boiling of the layer, ensuring the removal of large inclusions from the boiling layer zone with further removal from the reactor without stopping it; reducing the removal of material and catalyst, their sticking to the bump stop when working without changing the pressure drop on the bump stop device, the effect of a highly active deep oxidation catalyst on the degree of sludge burnout, effective vapor deposition and neutralization of acid gases.

4 cl, 5 dwg, 1 tbl, 7 ex

Description

The invention relates to devices and methods for burning wet sludge of wastewater from municipal wastewater treatment plants containing organic substances.

Known installation with an inert fluidized bed for the disposal of carbon-containing waste in urban wastewater treatment plants (patent RU No. 2351847), which contains a boiler plant, a fluidized bed furnace and a gas engine power plant with an exhaust gas pipeline. A high-pressure blower fan with a mixing chamber of fresh air and hot flue gases, to which the exhaust gas pipeline of the gas engine power plant is connected, a box-type air heater, through which, by means of the said fan, the hot gas-air mixture enters the fluidized bed furnace for combustion over a hot inert fluidized bed of wet carbon-containing sewage sludge waters, a settling chamber located above the combustion chamber of a fluidized bed with a cross-section exceeding the cross-section of said furnace, and side pockets for receiving ash and slag waste from the settling chamber with auger unloaders. When wet sewage sludge falls on the hot surface of the fluidized bed, the water instantly evaporates, and the solid particles burn out intensively. The resulting ash and slag waste settles in the discharge side pockets due to the section of the settling chamber increased in comparison with the fluidized bed chamber and is removed from the furnace using screw unloaders. The smallest unburned fuel particles and unburned combustible gases are burned in the afterburner.

The disadvantage of this invention is combustion in a layer of inert material. Implementation of the process in this mode leads to the formation of a huge amount of toxic substances in the exhaust gases, which, as a consequence, leads to the need to create complex and expensive purification systems. In addition, the use of an inert material determines the implementation of the process in the region of high temperatures (at least 800-1000 ° C), which leads to a large material consumption of structures, as well as increased requirements for the materials themselves.

A known method of processing wastewater sludge containing organic substances (patent RU No. 2568978), in which the dewatered sludge is dried to a moisture content of 1-2% in the upper part of the additional reactor in contact with a fluidized bed of a mixture of dispersed catalyst particles and inert material at a temperature of 100-200 ° C. After separation from the vapor-gas mixture, about 60% of the sediment with a moisture content of 1-2% is treated at a temperature of 700-750 ° C in the lower part of the reactor in a fluidized bed of a mixture of dispersed particles of catalyst and inert material, organized sequentially by a stationary nozzle and a grid with cell parameters providing a gradient temperatures between the continuous fluidized bed above the grate and under the grate 500-550 ° C. Heat treatment of the rest of the precipitate is carried out in the main reactor at a temperature of 500-750 ° C in a fluidized bed of a mixture of dispersed catalyst particles and an inert material organized by a fixed packing.

The disadvantage of this invention is the presence of an additional stage of preliminary drying, which leads to a complication of the technological chain, significantly higher energy consumption and complexity of control of each stage of the process. In addition, river sand is used as an inert layer material in the considered methods. River sand and catalyst particles are not a completely homogeneous mixture, and also have different strength characteristics, which leads to the possibility of the appearance of inhomogeneities in the distribution of the catalyst over the bed, as well as to a higher attrition rate.

The closest technical solution is the installation described in the article "Experience of operation of hot water boilers with catalytic combustion of liquid and solid fuel in a fluidized bed.", Authors: A.D.Simonov, N.А. Yazykov, A.S. Aflyatunov, I.A. Fedorov, V.A. Yakovlev, V.N. Parmon; journal "Alternative Energy and Ecology". 2014. No. 19 (159). S.70-85. The installation includes three reactor blocks, a solid fuel supply system with a screw feeder, a liquid fuel supply device, a liquid fuel ignition system, a rotary piston compressor for air supply to liquefy the catalyst bed and fuel oxidation, an economizer, a system for cleaning flue gases from dust (cyclone and bag filter). Flue gases after cyclones and filters are discharged into a common chimney. From cyclones and filters, the captured ash enters the pipe conveyor, through which it is fed to the storage hopper.

The disadvantages of this invention are the large dimensions of the heat generator and high power consumption; when burning fuels with a high total moisture content, due to an increase in the velocity of gases over the cross section of the apparatus with the formation of additional water vapor, the removal of catalyst particles increases, which leads to an increase in the catalyst consumption. In addition, there is no possibility of feeding water into the sediment. Since the sediment is an inhomogeneous mass, a situation may arise in which the moisture content of the sediment will be lower than the operating value (75%), which will lead to the heating of the layer. In the considered invention, the cooling of the layer is carried out by draining part of it from the reactor, which is suboptimal and costly. In addition, the considered installation does not have a vapor deposition unit (wet scrubber), which leads to an increased level of vapor emissions into the atmosphere.

The task of the claimed group of inventions is the development of a method and installation for the disposal of sludge wastewater, efficiently using heat when incinerating the sludge, ensuring the environmental safety of flue gases, allowing the process to be carried out in a continuous mode and allowing to reduce the consumption of the catalyst for complete oxidation.

The technical result of the claimed group of inventions is:

1. Uniform layer boiling;

2. Ensuring the withdrawal of large inclusions formed during the combustion of sludge wastewater from the fluidized bed zone with further removal from the reactor without shutting it down;

3. Reducing the carryover of material and catalyst, their adhesion to the baffle during operation without changing the pressure drop across the baffle device.

4. The use of a highly active catalyst for deep oxidation affects the degree of burnout of sludge sediments of municipal wastewater treatment plants during their incineration and the concentration of harmful substances in waste gases.

5. Effective vapor deposition and acid gas neutralization carried out in one device - a wet vortex scrubber.

The technical result is achieved by the design of the baffle and the air distribution device in the reactor and the inclusion of a wet vortex scrubber in the installation, as well as by the method of burning sludge in the presence of a catalyst for deep oxidation of CO and organic substances containing alumina as a carrier in an amount of not more than 50 wt% , and as an active component Fe ₂ O ₃ in an amount of 48-75 wt.%, as well as CuO and / or Mn ₂ O ₃ and / or Co ₂ O ₃ and / or Cr ₂ O ₃ in an amount of 2-10 wt. %.

The baffle is located in the upper part of the reactor vessel under the cover with the flue gas outlet pipe. The baffle is made in the form of a hollow truncated cone, while the truncated cone is fixed to the reactor vessel downward by a base with a smaller diameter, in which a pyramidal four-sided tip is fixed with its apex downward with a base diagonal greater than the diameter of the smaller base of the truncated cone of the baffle, so that between the base plane gaps are formed by the plane of the smaller base of the truncated cone of the bumper. The base of the baffle cone with a larger diameter is 40% larger than the diameter of the flue gas outlet. The design of the baffle inside the reactor reduces the carryover of material and catalyst and their adhesion to the baffle.

An air distribution device is located in the lower part of the reactor vessel between the catalyst removal branch pipe and the area for unburnt sludge components with a screw unloader. The air distribution device consists of two external distribution headers located in the same plane and parallel to each other at diametrically opposite walls of the casing, with three round tubes with perforation holes in the lower part of the wall extending from each header through the bends, each of which is welded into the reactor vessel and the free welded end of each of them is inserted into a glass welded from the outside into the reactor vessel from the side opposite from the knee. All perforated pipes are located parallel in the same plane and there are gaps between them for the passage of ash. The perforated part of the tubes is located inside the reactor vessel, and the total area of the perforations in the tubes is 2.5% of the cross-sectional area of the lower part of the reactor vessel. The design of the air distribution device ensures uniform boiling in the separation zone and the oxidation zone of the reactor, minimizes the adhesion of ash to the air distributor, through the gaps between the air distributor pipes large particles of unburned sludge components and the catalyst enter the discharge zone at the base of the reactor vessel, where the discharge screw is located for unloading large non-combustible components of sewage sludge (WWS) with further removal from the reactor without stopping it.

The scrubber located after the bag filter significantly condenses (precipitates) water from the steam-gas mixture and neutralizes acid gases by alkaline treatment. The scrubber solves the problem of cooling down to an acceptable temperature and removing excess water vapor from flue gases after combustion of carbon-containing fuel or organic compounds before their release into the atmosphere. The main acidic oxide in the composition of the exhaust gases after the reactor is sulfur dioxide SO ₂ . This oxide is formed from the sulfur contained in the cake - sludge of waste water, during oxidation with oxygen in a fluidized bed of catalyst. To neutralize the equilibrium forms of sulfurous acid formed in the solution, an alkaline agent (NaOH or Na ₂ CO ₃ ) is added to the scrubber water.

Utilization (combustion) is carried out in the presence of a catalyst for deep oxidation of CO and organic substances containing alumina as a carrier in an amount of not more than 50 wt%, and as an active component Fe ₂ O ₃ in an amount of 48-75 wt%, as well as CuO and / or Mn ₂ O ₃ and / or Co ₂ O ₃ and / or Cr ₂ O ₃ in an amount of 2-10 wt.%; heat treatment is carried out by continuously feeding the sludge into a reactor heated to a temperature of 750 ° C, which is simultaneously supplied with air necessary to maintain the regime of fluidization and oxidation of the organic part of the sludge and additional oxidation of CO formed during combustion. At the same time, the excess air ratio is close to stoichiometric (1 <α ≤ 1.2).

As a measure of the catalytic activity of catalysts in the process of burning sludge from municipal wastewater treatment plants, the degree of sludge burnout in the process of incineration, which is 98.1 - 99.3%, was chosen.

The essence of the invention is illustrated by figures 1, 2, 3, 4, 5.

FIG. 1. Scheme of the installation of thermocatalytic oxidation of sewage sludge.

FIG. 2. Schematic representation of a catalytic reactor.

FIG. 3. Picture of the air distribution device of the reactor

FIG. 4. Image of the bump stop (longitudinal section)

FIG. 5. Image of the bumper (cross-section)

The installation for catalytic combustion of sewage sludge (Fig. 1) includes a blower 34 and a heat generator 33 connected in series with a catalytic reactor 25, and a recuperator 26, an economizer 27, a bag filter 28, a wet vortex scrubber 29, a gas outlet line, high-pressure fan (smoke exhauster) 30 and chimney 31, and also includes a solid fuel supply system (supply hopper with auger dispenser) 35, a hopper for unloading incombustible components of sewage sludge 32.

The catalytic reactor (Fig. 2) is a vertical body 1, while the diameter of the reactor in the lower part is equal to 1.70 m, in the middle part - 2.18 m, in the upper part - 2.80 m., The height of the internal cavity of the reactor is -4, 0 m.

In the upper part of the reactor vessel 1 there is a catalyst supply pipe 2 and a baffle 10 under the cover 8 with a flue gas outlet pipe 9, made in the form of a hollow truncated cone. In the middle part inside the reactor vessel 1 there is an organizing nozzle 7 to reduce the heterogeneity of the fluidized bed, i. E. destruction of large gas bubbles in the reactor. In the lower part of the casing there are two sludge sludge inlet pipes 4, and two coal auger feed pipes 3 and a catalyst removal pipe 6. The sludge cake (cake) is fed into the reactor through two diametrically opposite pipes 4, while they are equipped with water metering pipes 5, which makes it possible to effectively control overheating in the reactor, which can occur due to the inhomogeneity of the sediment composition. Between the catalyst removal branch pipe 6 and the discharge zone 24 of incombustible sludge components with a branch pipe for the unloading auger 18, the outlet from which is provided with a gate valve 19, there is an air distribution device 12. The air distribution device 12 includes (Fig. 3) two distribution manifolds 13, elbows 14 and pipes 15 with perforations 16 in the lower walls of the pipes, the open ends of the pipes are inserted into the nozzles 17.

The baffle shown in Figs. 4 and 5 includes a truncated cone-shaped body 10 and a pyramidal tetrahedral tip 11.

FIG. 2 marked: the boundary of the separation zone 21 of the catalytic reactor, the zone of oxidation, coal injection, input of sludge 22, the air distribution zone 23 and the zone of unloading non-combustible components of the sludge 24.

The installation works as follows. In an empty reactor 25 (Fig. 1), 2.5 m ^{3 of} catalyst is poured through the pipe 2 (Fig. 2). They include a high-pressure fan 30, a blower 34., turn on the circulation of water in the economizer 27, turn on the heat generator TG 33 (Fig. 1). The flue gases that are formed in the TG heat generator during the flare combustion of diesel fuel are mixed with air and at a temperature of about 700 ° C, which is set by regulating the air flow from the blower, and fed through the air distributor 12 (Fig. 2, 3) into the reactor ... The uniformity of air distribution in the zone 23 and in the oxidation zone 22 of the reactor (Fig. 2) is ensured by the flow of air through two collectors 13 and holes 16 in the lower part of the wall of the air distribution pipes 15 (Fig. 3). In this case, the air flow changes from a horizontal direction to a vertical one and its uniform distribution over the oxidation zone 22 of the reactor. To ensure uniform fluidization of the catalyst bed and to prevent catalyst particles from entering the gas supply pipeline, the area of the holes in the perforated pipes is 2.5%, which corresponds to the rate of gas outflow from the holes at the level of 24 m / s. The proposed gas distribution design provides a more uniform fluidization of the bed. The perforation of the lower parts of the pipe walls ensures that the air diffuser is not clogged. To ensure free thermal expansion of the perforated pipes 15, their free ends with a gap are inserted into the nozzles 17, the nozzles are welded from the outside into the reactor vessel 1, their outer location allows maximum use of the lower section of the reactor.

The heated flue gases are passed through the catalyst bed. After heating the catalyst layer to a temperature of 350-400 ° C, the required additional amount of air is added to it (up to 8500 nm ³ / h with a pressure of up to 40 KPa). In this case, the catalyst bed is brought into a fluidized state, and at the same time, from the bunkers 35 (Fig. 1), at a small flow rate, crushed coal is fed into the reactor 25 with screw feeders through the nozzles 3, controlling the temperature rise in the bed to 600-700 ℃. When fixing a steady rise in temperature by increasing the consumption of coal, the temperature in the layer is brought to 750 ° C: the catalyst is gradually added to the reactor, through the pipe 2, to the total volume of the catalyst in 9m ³ , at the same time, the coal supply is gradually increased and the hot air is turned off while maintaining temperature 750 ° C. Additional uniformity of the air flow inside the reactor is provided by the organizing nozzle 7 (Fig. 2), it serves to reduce the heterogeneity of the fluidized bed, i.e. destruction of large gas bubbles in the reactor. Then the heat generator 33 is turned off. After the catalyst has been heated up, sewage sludge (WWS) with a moisture content of 73-75% is fed into the reactor through two diametrically opposite pipes (4), the inlet of which is located in the lower part of the reactor in the oxidation zone, coal input, sludge input 22 . (Fig. 2). Sludge sludge supply pipes 4 in the reactor are equipped with water metering pipes 5, which makes it possible to effectively control overheating in the reactor, which can occur due to the inhomogeneity of the sludge composition. Gradually increase the consumption of WWS and control the temperature in the oxidation zone, coal input, sludge input. As the temperature rises, the consumption of crushed coal is reduced. Upon reaching the nominal WWS flow rate (wet sediment 6 t / h), the temperature in the oxidation zone, coal input, sludge input 22 is maintained at 750 ° C. With the complete cessation of the supply of additional fuel and a further increase in the bed temperature above the required (750 ° C) for heat treatment of the sludge, water is supplied to the sludge supply pipe 4 through the pipe 5.

After turning off the heat generator 33, air is supplied through the recuperator 26 through the annular space. Air heating occurs due to the extraction of heat from the exhaust flue gases of the reactor 25.

When the temperature drops below the nominal 750 ° C, which is associated with an increase in the WWS humidity of more than 75%, the crushed coal supply system 35 is switched on at the minimum productivity of the screw feeders, the temperature in the layer is brought to the nominal 750 ° C by increasing the productivity of the screw feeders and thereby the consumption of crushed coal ...

When the temperature in the layer rises above 750 ° C, i.e. with a decrease in the WWS humidity below 73-75%, the volume of air passing through the recuperator 26 decreases, while the volume of air going directly from the blower 34 to the reactor 25 increases while maintaining the total air flow rate equal to 8273-8300 m ³ / h. In this case, the air temperature decreases and thereby the temperature in the reactor layer 25 decreases. In the limit, all air passes bypassing the recuperator 26. With a subsequent decrease in the WWS humidity and a further increase in the temperature in the layer, the water supply is switched on through the pipes 5 starting from the minimum flow rate to the maximum. When the maximum flow rate of water is reached and the tendency for an increase in temperature in the bed is maintained, the flow rate of the WWS fed to the reactor decreases.

With a decrease in the height of the catalyst bed due to abrasion of the catalyst, the catalyst is added to the operating level without stopping the reactor.

Through the gaps between the pipes 15 of the air distributor 12, large non-combustible components of sewage sludge enter the unloading zone 24 (Fig. 2) at the base of the reactor vessel 1, where the unloading auger 18 is located for unloading the incombustible components of sewage sludge. Periodically carry out the unloading of large incombustible inclusions of sludge of sewage by a screw 18, through the unloading zone of incombustible inclusions 24 (Fig. 2) located at the base of the reactor. Unloading takes place without stopping the reactor.

To reduce the phenomenon of catalyst carryover from the reactor together with the flue gases formed as a result of WWS combustion, a baffle 10 is installed in the separation zone 21 (Figs. 4, 5). Flue gases with catalyst particles formed as a result of sludge combustion in the separation zone 21 collide with a baffle 10 in the form of a truncated cone with a pyramidal four-sided tip 11. Baffle 10 is fixed on the reactor vessel 1 under the flue gas outlet pipe 9 downward with a base with a smaller diameter, in which a pyramidal four-sided tip 11 is fixed with its top downward with a larger diagonal of the base than the diameter of the smaller base of the truncated cone of the bumper. The design of the baffle ensures a uniform distribution of the flow over the cross section of the reactor and the absence of aerodynamic hindrances. Solid catalyst particles and ash particles are beaten off and returned to the separation zone 21 - the boiling layer, where they burn out, or through the gaps of the perforated pipes 15 of the air diffuser 12 fall into the discharge zone of non-combustible components 24. Small particles of catalyst or ash that have fallen into the cavity of the baffle cone are poured through the gaps, formed by the plane of the base of the tip and the plane of the smaller base of the truncated cone of the bumper. The rest of the dust and gas flow through the flue gas outlet pipe 9 located in the cover 8 leaves the reactor and is directed to the subsequent stages of the process chain.

750 °С от реактора 25 поступают в рекуператор 26, где охлаждаются до температуры 660 °С. Воздух, проходящий через рекуператор 26 нагревается до расчетной температуры 239 °С. Дымовые газы из рекуператора 26 поступают в трубное пространство экономайзера 27, где охлаждаются водой, циркулирующей по межтрубному пространству до температуры 185-200°С, затем поступают на очистку в рукавный фильтр 28. В рукавном фильтре 28 дымовые газы очищаются от механической взвеси. Очищенные дымовые газы поступают в скруббер 29 (Фиг.1), в котором происходит "осаждение" пара, содержащегося в дымовых газах, в количестве 3,5 т/ч, а также улавливание кислотных оксидов за счет связывания с щелочным агентом, дополнительно подающимся в воду скруббера 29. Парогазовая смесь в составе: дымовые газы не менее 11600 кг/ч, зола 0,9 кг/ч и водяной пар не менее 4500 кг/ч с температурой 185-200 °С, а так же вода на орошение в количестве не менее 240 м3/ч с температурой 25-30 °С подаются в скруббер в горизонтальном направлении. Такие условия обеспечивают охлаждение парогазовой смеси до температуры 60-70 °С, при этом из охлажденной парогазовой смеси конденсируется не менее 3500 кг/ч водяного пара, а температура воды, вытекающей из скруббера, на 10-20 °С выше температуры воды, подаваемой на орошение. Flue gases with temperature

750 ° C from the reactor 25 enter the recuperator 26, where it is cooled to a temperature of 660 ° C. The air passing through the recuperator 26 is heated to a design temperature of 239 ° C. The flue gases from the recuperator 26 enter the tube space of the economizer 27, where they are cooled with water circulating through the annular space to a temperature of 185-200 ° C, then they enter the bag filter 28 for cleaning. In the bag filter 28, the flue gases are cleaned of mechanical suspension. The cleaned flue gases enter the scrubber 29 (Fig. 1), in which the vapor contained in the flue gases is "precipitated" in an amount of 3.5 t / h, as well as the capture of acid oxides by binding with an alkaline agent, which is additionally fed to scrubber water 29. Steam-gas mixture consisting of: flue gases at least 11,600 kg / h, ash 0.9 kg / h and water vapor at least 4500 kg / h with a temperature of 185-200 ° C, as well as water for irrigation in an amount not less than 240 m3 / h with a temperature of 25-30 ° С are fed into the scrubber in the horizontal direction. Such conditions ensure the cooling of the vapor-gas mixture to a temperature of 60-70 ° C, while at least 3500 kg / h of water vapor condenses from the cooled vapor-gas mixture, and the temperature of the water flowing out of the scrubber is 10-20 ° C higher than the temperature of the water supplied to irrigation.

In this case, the water supplied to the scrubber is continuously dosed with an alkaline agent (NaOH or Na2CO3), which ensures effective dissolution and binding of acid oxides (mainly SO2) that are part of the flue gases. Based on the data of chemical analysis, the sulfur content in the combustible mass of the sediment is up to 0.8 wt. %. The sludge consumption in the process of thermocatalytic oxidation, calculated on the basis of the combustible mass, is 1050 kg / h, which in terms of SO2 is 16.8 kg / h. The ash formed during the incineration of the sludge captures at least 90% of the dioxide (with the formation of salts) or at least 15.12 kg / h. Thus, the scrubber receives no more than 1.68 kg / h of SO2. Based on the assumption that all dissolved sulfur dioxide is converted into equilibrium forms of sulfurous acid, it can be calculated that in this case, the concentration of [H +] will be about 1.08 * 10-4 mol / l. Therefore, the pH of such a solution will have a value of about 4.0.

To neutralize such a solution, sodium alkali (NaOH) can be used, in an amount corresponding to a concentration of 1 * 10-4 mol / l or 24 mol / h. Therefore, about 960 g / h NaOH must be added to the scrubber water. When used to neutralize sodium bicarbonate (Na2CO3), the introduction of 0.5 * 10-4 mol / l or 12 mol / h of salt will be required. This corresponds to a consumption of 1.272 kg / h.

From the scrubber 29, flue gases with a steam content of 1 t / h are fed through the gas ducts through the high-pressure fan 30 into the chimney 31.

The activity of the catalyst used in the CO oxidation reaction is determined on a Chemosorb device by the pulse method at the temperature of 50% CO conversion.

Example 1

Aluminum hydroxide of the pseudoboehmite type is stirred in distilled water with the addition of concentrated nitric acid. The acid modulus (molar ratio of acid to aluminum oxide) is 0.01. The suspension is stirred for 1 hour. The suspension was added to the pulverized powder of the active ingredient (nanocomposite obtained by calcination of salts of nitrates, with a surface area of at least 10 m ² / g, obtained by the method described in (Fedorov AV, Tsapina AM, Bulavchenko OA, Saraev AA, Odegova GV, Ermakov DY , Zubavichus YV, Yakovlev VA, Kaichev VV, Structure and Chemistry of Cu – Fe – Al Nanocomposite Catalysts for CO Oxidation, Catalysis Letters. 2018.- V.148., N12. - P.3715-3722. DOI: 10.1007 / s10562 -018-2539-5) to obtain a plasticized mass. The water content in the plasticized mass is 80 wt.%. Drop molded into a 20 wt.% Ammonia solution through a layer of hydrocarbon liquid. The granules are air-dried for 24 hours at 110 ° C. for 2 hours and calcined at 700 ° C. for 1 hour The resulting catalyst contains 3.0 wt% CuO, 50.0 wt% Fe ₂ O ₃ and 47.0% Al ₂ O ₃ .

The 50% CO conversion temperature is 215 ° C. The degree of sludge burnout is 98.1%.

Example 2.

Similar to example 1. The resulting catalyst contains 75.0 wt. % Fe ₂ O ₃ and 25.0% Al ₂ O ₃ .

The 50% CO conversion temperature is 225 ° C. Sludge burnup rate 97.5%

Example 3.

Similar to example 1. The resulting catalyst contains 5.0 wt. % Mn ₂ O ₃ , 60.0 wt. % Fe ₂ O ₃ and 35.0% Al ₂ O ₃ .

The 50% CO conversion temperature is 230 ° C. Sludge burnup 98.5%

Example 4

Similar to example 1. The resulting catalyst contains 4.5 wt. % Cr ₂ O ₃ , 60.0 wt. % Fe ₂ O ₃ and 35.5% Al ₂ O ₃ .

The 50% CO conversion temperature is 230 ° C. Sludge burnup 98.0%

Example 5. Similar to example 1.

The resulting catalyst contains 4.0 wt. % Co ₂ O ₃ , 61.0 wt. % Fe ₂ O ₃ and 35.0% Al ₂ O ₃ .

The 50% CO conversion temperature is 200 ° C. Sludge burnup 98.9%

Example 6. Similar to example 1.

The resulting catalyst contains 4.0 wt. % Co ₂ O ₃ , 6.0 wt. % CuO, 55.0 wt. % Fe ₂ O ₃ and 35.0% Al ₂ O ₃ .

The 50% CO conversion temperature is 180 ° C. Sludge burnup 99.6%

Example 7. Similar to example 1.

The resulting catalyst contains 7.0 wt. % Mn ₂ O ₃ , 3.0 wt. % CuO, 52.0 wt. % Fe ₂ O ₃ and 38.0% Al ₂ O ₃ .

The 50% CO conversion temperature is 185 ° C. Sludge burnup 99.3%

Comparative characteristics of deep oxidation catalysts are shown in the Table.

Table

Comparative characteristics of deep oxidation catalysts

Temperature to reach 50% CO conversion, ° C Sediment burnout,% Example 1 215 98.1 Example 2 225 97.5 Example 3 230 98.5 Example 4 230 98.0 Example 5 200 98.9 Example 6 180 99.6 Example 7 185 99.3

Claims (4)

1. Installation for catalytic combustion of fuel in the form of sewage sludge, including a catalytic reactor, in which a branch pipe for the catalyst supply is located in the upper part of the housing, and a baffle made in the form of a hollow truncated cone is located under the cover with a flue gas outlet pipe, while fixed on the reactor vessel downward with a base with a smaller diameter, in which a pyramidal four-sided tip is fixed with its apex downward with a base diagonal larger than the diameter of the smaller base of the truncated cone of the baffle, in such a way that gaps are formed between the plane of the base of the tip and the plane of the smaller base of the truncated cone of the baffle; in the lower part of the casing of the catalytic reactor, in the oxidation zone, there are two diametrically opposite pipes for supplying sewage sludge, into each of which a water supply pipe is welded, between the catalyst removal pipe and the area for unburnting unburnt sludge components with a pipe for unloading auger there is an air distribution a device that consists of two external distribution manifolds located in the same plane and parallel to each other at diametrically opposite walls of the reactor vessel, with three round pipes with perforations in the lower part of the wall extending from each manifold through the bends, each of which is welded into the reactor vessel and the free welded end of each of them are inserted into a glass welded from the outside into the reactor vessel from the side opposite to the knee, while all perforated pipes are located parallel in one plane and installed with gaps between them, and the perforations this part of the tube is located inside the reactor vessel, while the total area of perforations in the tubes is 2.5% of the cross-sectional area of the lower part of the reactor vessel; connected in series with the catalytic reactor by an air supply line - an air blower and a heat generator, and a gas outlet line - a recuperator, an economizer, a bag filter, a wet vortex scrubber, a high-pressure fan and a chimney, and also includes a solid fuel supply system - a supply hopper with a screw feeder, a hopper unloading of non-combustible components of sewage sludge. 2. Installation according to claim 1, characterized in that in the catalytic reactor, the base of the baffle with a larger diameter is 40% larger than the diameter of the flue gas outlet pipe. 3. Installation according to claim 1, characterized in that in the lower part of the casing, the catalytic reactor contains two nozzles for screw coal supply. 4. The method of combustion of fuel in the form of sludge of sewage, which is carried out in the installation described in claim 1, while heat treatment is carried out in a fluidized bed in the presence of a catalyst for deep oxidation of CO and organic substances containing as a carrier alumina in an amount of not more than 50 wt.%, And as an active component Fe ₂ O ₃ in an amount of 48-75 wt.%, As well as CuO, and / or Mn ₂ O ₃ , and / or Co ₂ O ₃ , and / or Cr ₂ O ₃ in the amount of 2-10 wt.%; heat treatment is carried out by continuous supply of sewage sludge to a catalytic reactor heated to a temperature of 750 ° C, which is simultaneously supplied with air necessary to maintain the fluidization mode of the catalyst bed and oxidation of the organic part of the sludge and additional oxidation of CO formed during combustion; flue gases go from the catalytic reactor to the recuperator, then to the economizer tube space, where they are cooled with water, then go to the bag filter for cleaning, then the cleaned flue gases enter the wet vortex scrubber, in which water vapor formed during catalytic combustion is simultaneously condensed sewage sludge, and neutralization of acid gases contained in flue gases.

Images