RU2265644C2 - Method and a device for treatment of a fuel - Google Patents

Abstract

FIELD: Methods and devices for treatment of fuels.

SUBSTANCE: the invention is pertaining to a method and a device for treatment of a fuel with a catalyst solution. The method of treatment of a fuel with a catalyst, in particular, the treatment of a pulverized coal, which is burnt at a pig iron production in blast furnaces in tuyeres, provides, that the catalyst reducing the temperature of inflammation or at a constant temperature - accelerating the speed of the fuel burning up is fed during crushing of the unsorted coal into a coal breakage or a coal powder to coal particles, in particular, apply on the coal particles. In the capacity of the catalyst use the solution, containing cerium and iron salts of organic and-or mineral acids on the basis of the water solution. The device differs that it is equipped with abrading attritor for mincing of a non-sorted coal or coke into the micronized coal or a coal dust, in particular, an air-swept mill having the mincing rollers rotating on a bowl, a separator, a body, a camera for mincing-sorting and an inlet for the unsorted coal feeding, and also an outlet for micronized coal or a coal dust withdrawal. In the mincing-sorting chamber there is at least one device, which has been made with a capability to feed the catalyst to the coal particles, in particular, to deposit the catalyst on them in the process of mincing and sorting for reduction of the inflammation temperature or for rising the speed of burning-out at a constant temperature. The invention promotes cost reduction at a pig iron production and also ensures a possibility to use the less expensive coal or petroleum coke.

EFFECT: the invention promotes a cost reduction at a pig iron production and ensures a possibility to use the less expensive coal or petroleum coke.

20 cl, 5 dwg

Description

The invention relates to a method for processing fuel, in particular pulverized coal fuel for the production of pig iron, according to the restrictive part of claim 1 of the formula, and also to a device for implementing the method according to the restrictive part of claim 11 of the formula.

From WO 99/64636 a method for producing cast iron in a blast furnace is known, when using the method of injection of crushed coal, coal dust as additional fuel is supplied together with hot air and / or oxygen through tuyeres to a blast furnace in order to reduce coke consumption and thereby reduce costs to receive every ton of cast iron. To achieve a further reduction in coke consumption, pulverized coal treated with the added catalyst is used. As a catalyst additive, aqueous solutions of compounds of subgroup elements such as zirconium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc or aluminum, tin or lead, in particular a solution of copper sulfate, are proposed. The advantages of using pulverized coal fuel with the addition of a catalyst, along with a reduction in coke consumption, should be the replacement of more expensive coal, lower slag yield and lower emissions of harmful particles, as well as improved quality of cast iron.

In the article "Blast furnace efficienci enhancer for pulverized coal injection" in the journal Steel Technology, February 2000, p. 61 ff, this method is described in detail. Pulp-coal fuel, which is fed through tuyeres to partially replace coke, has a particle size of 75 μm and a moisture content of <1%, and 350 to 600 ml of catalyst solution is supplied for each ton of coal. The feed is made using a special device, which is located behind the storage for unsorted coal and in front of the MPS mill (figure 2), and unsorted coal is treated by spraying it with a catalyst solution. In addition, it is described that, due to the corrosive properties of the catalyst solution, the sprayer must meet special requirements, and in addition, a system for regular cleaning of the nozzle is required.

The basis of the invention is the creation of a method and device for processing fuel, in particular pulverized coal fuel for the production of pig iron, which would allow the most simple and effective way to save coke and increase the proportion of blown coal, as well as use less expensive coal or petroleum coke.

According to the invention, this problem is solved in part of the method due to the use of a catalyst that lowers the ignition temperature of the fuel or at a constant temperature increases the rate of burnout, and due to the fact that the catalyst, in particular the catalyst solution, is applied to the coal particles during grinding of coal into coal dust. Coal particles or coal dust treated in this way can be fed directly into the tuyeres of the blast furnace together with hot air, which is brought to a temperature of about 1250 ° C in the blast air heater, and / or brought together with oxygen to the tuyeres of the blast furnace, or served in a temporary storage facility .

It turned out that the treatment with the catalyst, which is offered by the company Emissions-Reducings-Concept GmbH (ERC) under the trademark "Carbamine 5010" and which is described in DE 19800873 C2, helps to reduce the ignition temperature of the fuel and accelerate combustion. A lower flash point and faster combustion inside the tuyeres mean faster ignition and faster burn-out of residual coke, i.e. almost complete combustion of coal inside the tuyeres. These factors, along with the partial pressure of oxygen, the tuyere temperature (radiation fraction) and the fineness of coal grinding, as well as its inlet temperature and humidity, largely determine the efficiency of pulverized coal injection and its effect on coke consumption and the quality and quantity of pig iron produced.

The ignition temperature and the burnup characteristic are determined by the origin of the coal used. At the same time, the so-called carburization or maceral composition plays a significant role in tuyeres. The volatile particles of coal ignite the residual coke as soon as it reaches the ignition temperature. However, an inherent increase in the coke temperature occurs inside the tuyeres not due to the combustion of volatile components, but, first of all, due to the heat of radiation of the tuyere walls. The burning out of the remaining coke is restrained kinetically, and, in particular, the inert part of the coal slows down the burning.

Additives acting as catalysts, i.e. catalysts that reduce the ignition temperature of residual coke contribute to better burnout. The burn-up time of coal is reduced and therefore the amount of blown coal may increase, or low-volatility coal or petroleum coke can be used.

An ERK additive acting as a catalyst (hereinafter referred to as an ERK additive) is described in DE 19800873 C2. It is used in the form of an aqueous solution that contains cerium and iron salts of organic and / or inorganic acids and has a hydrogen ion concentration of pH below 7, and may also contain a wetting agent and / or a neutralizing substance. There is an indication of the compositions and concentrations of the catalyst solution given in this patent and the field of application.

Accordingly, a known catalyst solution is provided for reducing the emission of harmful substances during combustion and / or drying, and / or processes for heating fuel containing carbon, and can be added to solid fuels such as coal, wood, biomass, waste, and also heavy oil , and other liquid fuel and / or supplied air before burning. An action that reduces the emission of harmful substances is also mentioned in connection with tuyeres in domain processes. It is not described how the fuel is processed.

A particular advantage of the claimed method is the possibility of burning the treated pulverized coal composition in tuyeres with a slight excess of air, so that the formation of nitric oxide is suppressed.

A particularly advantageous treatment of pulverized coal fuel with a catalyst solution, in particular an ERC additive, can be performed in an abrasive mill in which unsorted coal or petroleum coke is milled and dried, ground into coal dust and fed to a separator using a fluid, for example hot gas, located above the grinding chamber.

It is advisable to add a catalytic additive in the form of an aqueous solution having a temperature of from 5 to 35 ° C, or inject it into the grinding-sorting chamber, where the temperature is lower than the boiling or decomposition temperature.

With regard to the device, it has been found that the injection of an ERC additive into a mill, in particular into an abrasive mill, such as an air-jet abrasive mill, contributes to a particularly efficient treatment of ground fuel particles. It is assumed that the corresponding location of the at least one sprayer and the direction of the jets accelerate the wetting of the flowing stream of the milled material inside the air-jet abrasive mill and / or the penetration into coal particles or coke particles. Thanks to the grinding process, a characteristic increase in the surface of the coal occurs, so that there is a clear increase in the distribution density on the reaction surface, and the pores can also be better moistened or saturated.

A particular benefit is that known devices for injecting water into an attrition mill can be used for the ERC additive. The devices can be arranged in this case, respectively, above the grinding rollers, and either between two adjacent grinding rollers against each other, or at an angle of about 120 °. The spray angle α can be from 10 to 70 °, preferably about 60-70 °, and extend approximately vertically or in the direction of the grinding rolls or separator. It is advantageous to place two devices in the mill body, and the spraying direction and spraying angle can be the same or different.

In principle, the devices can be placed in a mill with any spray angle throughout the chamber for grinding and sorting. At least one device or nozzle must be positioned so that even on the base, which is located on the bowl, the dosage of the catalyst liquid and the treatment of the crushed coal or coke with the composition can be carried out. When placing the sprinklers at the cone level for coal fines, it is preferable to choose the tangent direction of blowing relative to the cone for coal fines, so as to spray clouds of flowing solid particles moving in the form of a spiral in the direction of the separator. In this way, it is possible to prevent the catalyst from wetting the walls of the cone for coal fines and baking to the walls of the cone, in particular at the corresponding high injection pressure.

It is advisable to regulate the flow of ERC additives depending on the crushed coal, its amount and flow rate. An ERK additive, which, for example, is stored in a container, is fed through a supply pipe, and before feeding, adding water, a solution of the appropriate concentration is prepared. Injection can be carried out together with compressed air, and the pressure is expediently from about 2 to 10 bar.

Along with the benefits of a lower coke consumption by replacing more expensive coke or more expensive coal with cheaper coal or petroleum coke, and thus reducing the cost of cast iron production, less dust emissions and better quality cast iron are achieved. It is possible to reduce the amount of combustion air or oxygen, which reduces the formation of nitrogen oxides. Cheaper and more expensive coal differ from each other, in particular, the content of volatile substances and ash. Cheaper coal has a more limited volatile content, typically less than 25-30%, and a higher ash content, usually more than 7-8%. More limited dust emission i.e. reducing the emission of unburned soot leads to a reduction in energy losses and lower costs in the process of flushing a blast furnace with gas, since the removal of soot requires increased energy and technical costs. The reduction in soot emissions is an indicator of the burnup quality of the received amount of coal and thereby the efficiency of the catalyst used.

The invention is explained below in more detail using the drawings, in which schematic images are given.

Figure 1 is a partial longitudinal section of an air-jet abrasive mill with a spray;

Figure 2 is a schematic illustration of an air-jet abrasive mill with two sprinklers;

Figure 3-5 - an air-jet abrasive mill with four, three and two grinding rollers and, respectively, two sprinklers (cross section).

Figure 1 shows a sectional view of an air-jet abrasive mill 2. On the bowl 3, grinding rolls 4 rotate, of which only one grinding roll is represented. A blade rim 5 is arranged around the circumference of the bowl 3, through which heated gas 13 flows in a swirling stream specified by the slope of the blades into the grinding and sorting zone 12, and from the grinding rollers 4, the crushed material is fed to the separator 7 in the stream 6. Still insufficiently crushed material falls back through the cone for coal fines to the bowl 3 and is subjected to further grinding. Fine material 9 is discharged through an outlet (not shown here) from the separator 7 and fed to the tuyeres (not shown here) of a shaft furnace (not shown here) or in a temporary storage facility (not shown).

The processing of coal particles of a moving fluid stream of crushed material occurs using devices 10, which are designed to inject or inject a solution of catalyst, in particular ERC additives, into the grinding-sorting chamber 12 to improve combustion. These devices 10 can be positioned above the grinding rollers 4 and / or at the level of the grinding rollers 4, in particular slightly above the bowl 3 or the edges of the bowl, in particular to be mounted on the mill body 11. At least one of the sprayers 10 should be directed to the bowl 3 and facilitate the treatment of the base of the bowl 3. The catalyst solution can be supplied through a common supply pipe 18. The devices 10 correspond essentially to water sprinklers that are designed to lower the temperature of the ground material or according to Security Jicin, usually in an air abrasive mills. These known water sprinklers are advantageously used for injecting an ERC additive.

The temperature of the ERC additive injected through the device 10 is less than 95 ° C. Injection occurs together with compressed air 14, which is supplied to the device 10, and the pressure is from 2 to 10 bar. The spray angle α of the substantially horizontal upper spray gun 10 is advantageously 60-70 °, while the spray angle of the lower spray gun 10 depends on the angle of the jet.

Particularly advantageous is the arrangement of the sprinklers 10 at the level of the lower cone region for coal fines 8, since an effective treatment of the particles of the crushed material in the rising stream 6 is achieved. In FIG. in particular, for processing the ground material located on the bowl 3, and particles of the ground material located above the edge of the bowl 3. In addition, the heated gas 13 receives an injected catalyst solution, so that the particles the crushed material may be wetted or soaked in its upstream fluid stream 6.

Figure 2 shows a schematic illustration of an air-jet mill 2, which is located above the grinding rollers 4, of which only one grinding roller 4 is represented, with two sprinklers 10. The sprinklers 10 are mounted on the mill body 11 and are connected by supply piping 15 to the pump unit (not here submitted).

The ERK additive is stored in a tank (not shown here) and diluted with water in a predetermined ratio in front of the pump unit. The locking elements 16 and the electromagnetic control valves 17 allow dosing depending on a given amount of coal and the speed of the heated gas.

In addition, the sprinkler 10 is located slightly above the bowl (not shown), and the nozzles are mounted so that the base is wetted by the catalyst liquid.

In Fig. 3, the abrasive mill 2 is presented in cross section and has four grinding rollers 4 and two sprinklers 10. The sprinklers 10 are located opposite each other almost in the middle between the respective two grinding rollers 4, so that the bisector of the spray angle α (see Fig. 1 and 2) forms a secant, and, thus, coal particles in the stream of crushed material are processed in the spaces between two grinding rollers 4 and in the center of the mill.

The sprinklers 10 can also be positioned appropriately so that the spray angle is tangentially directed. Thus, neither the area of the grinding rolls nor the cone body for coal fines (not shown here) will be wetted, or very little wetting will occur, so that there will be no baking. The tangential sprinklers 10 are indicated by a dashed line. These sprinklers mounted tangentially can be installed in addition to the sprinklers 10 located almost radially, or instead of them at a different level.

Figure 4 shows an air-jet abrasive mill 2 with three grinding rollers 4 and two sprinklers 10. The sprinklers 10 are located eccentrically in two gaps of three between the grinding rollers 4 and sprinkle the ERC additive in the gaps and almost parallel to the inner end surface of one of two adjacent grinding rolls 4 in the direction of the center of the mill.

The abrasive mill 2 according to FIG. 5 has two grinding rollers 4 and two sprinklers 10. They are mounted against each other, however eccentrically between the two grinding rollers 4. In addition to the sprinklers 10 of FIGS. 4 and 5, sprinklers 10 installed along tangent and indicated in FIG. 3 by a dashed line.

Through the sprinklers 10, it is possible to supply an ERC additive in a ratio of 0.2-1 l per 1 ton of coal, moreover, it is diluted in a ratio of 1:10. Injection occurs at a pressure of about 2 to 10 bar. The spray angle α can be from 10 to 70 °, preferably 60-70 °.

The feed of the treated pulverized coal fuel through the tuyeres of the blast furnace takes place at a speed of about 200 m / s. It was found that the residual burning time after injection of coal is 4-5 microseconds, and the concentration of the ERK additive is approximately 30-50 ppm.

Claims (20)

1. A method of treating fuel with a catalyst, in particular pulverized coal, which is burned in the production of pig iron in blast furnaces in tuyeres, characterized in that the catalyst lowers the ignition temperature or at a constant temperature increases the rate of burning of the fuel during grinding of unsorted coal into fines or coal dust is fed to the coal particles, in particular applied to the coal particles, and a solution containing organic and / or inorganic cerium and iron salts is used as a catalyst acids based on an aqueous solution .. 2. The method according to claim 1, characterized in that the catalyst is used to reduce the emission of harmful substances during combustion and / or drying, and / or in the process of heating a material containing carbon. 3. The method according to claim 2, characterized in that the catalyst is injected into the grinding-sorting chamber in the form of a solution containing cerium and iron as salts of inorganic and / or organic acids in an aqueous solution with a hydrogen ion concentration index of less than 7. 4. The method according to claim 2 or 3, characterized in that the unsorted coal is ground in an abrasive mill using grinding rolls rotating on the bowl, and the catalyst is fed into the area above the bowl and / or grinding rolls. 5. The method according to one of claims 2 to 4, characterized in that the unsorted coal in an air-jet abrasive mill having a separator and a grinding-sorting chamber is subjected to grinding and drying and the catalyst is fed into the grinding-sorting chamber at a temperature below 100 ° FROM. 6. The method according to claim 5, characterized in that the spray angle α when feeding the catalyst into the chamber for grinding-sorting is approximately 10-70 °. 7. The method according to claim 5 or 6, characterized in that the catalyst is injected into the chamber for grinding-sorting horizontally and tangentially to the bottom of the cone for coal fines. 8. The method according to one of claims 2 to 7, characterized in that the feed of the catalyst is controlled depending on the supplied unsorted coal and the flow rate. 9. The method according to one of claims 2 to 8, characterized in that the catalyst is injected into the grinding-sorting chamber together with compressed air and the pressure is from 2 to 10 bar. 10. The method according to one of claims 2 to 9, characterized in that the catalyst is supplied in a ratio of 0.2-1 l per 1 ton of coal and diluted 1:10. 11. A device for treating fuel with a catalyst, in particular pulverized coal for the production of pig iron, and for implementing the method according to one of claims 1 to 10, characterized in that there is an abrasive mill for grinding unsorted coal or coke into finely divided coal or coal dust, in particular, an air-jet mill having grinding rolls rotating on a bowl, a separator, a housing, a grinding-sorting chamber and an inlet for unsorted coal, as well as a terminal for finely ground coal or coal dust and, and in the chamber for grinding and sorting, at least one device is arranged for feeding the catalyst to the coal particles, in particular for applying the catalyst to them, during grinding and sorting to reduce the ignition temperature or to increase the burn-up rate at a constant temperature. 12. The device according to claim 11, characterized in that the devices are made in the form of sprinklers and are located above the bowl and / or grinding rolls. 13. The device according to claim 11 or 12, characterized in that as sprinklers use devices provided for the injection of water into the chamber for grinding-sorting. 14. The device according to one of paragraphs.11-13, characterized in that the spray angle α of the sprayers is from about 10 to 70 °. 15. The device according to one of paragraphs.11-14, characterized in that there are two sprinklers located, when viewed from above, between two respective grinding rolls. 16. The device according to clause 15, wherein the sprinklers are located in the center or eccentrically between two adjacent grinding rollers. 17. The device according to one of paragraphs.11-16, characterized in that the catalyst is made with the possibility of its filing in the form of a solution in the sprayers using a pump unit, injection under pressure from 7 to 10 bar and spraying. 18. The device according to one of paragraphs.11-17, characterized in that the sprinklers are horizontally arranged in the direction of the gaps between the grinding rolls and the center of the mill, which, when viewed in the cross section of the abrasive mill, the bisector of the spray angle α forms a secant. 19. The device according to one of paragraphs.11-18, characterized in that at least one sprinkler is installed in the direction of the bowl and is directed to the base. 20. The device according to one of paragraphs.11-18, characterized in that the sprinklers are directed tangentially to the cone for coal fines.

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