RU2801574C1 - Solid composite fuel - Google Patents

Abstract

FIELD: solid energy fuels.

SUBSTANCE: solid composite fuel is proposed, composed of petroleum coke as the main energy component and an initiating additive, where the initiating additive is represented by a carbon residue from the pyrolysis of used tires in the following ratio, wt.%: petroleum coke 50-90, carbon residue 10-50.

EFFECT: intensification of the process of ignition and subsequent combustion of petroleum coke by increasing the reactivity, which is expressed in a decrease in the ignition delay and a decrease in the temperature of the onset of intense oxidation.

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Description

The invention relates to solid energy fuels, namely to solid composite fuel, which can be used for combustion at thermal power plants and boiler plants.

An invention is known (patent RU No. 2490316 C1, IPC C10L 5/00, C10B 55/00, C10B 57/00, C21B 5/02, publ. 20.08.2013), describing a fuel composite consisting of finely ground petroleum coke and a desulfurizer ( calcium oxide/hydroxide) used as a fuel for blast-furnace smelting. The ratio of carbon-containing ground material and desulfurizer is 90-99 wt.% and 1-10 wt.%, respectively. This invention allows to expand the raw material base of energy fuels used for blast-furnace smelting. Due to the presence of a desulfurizer in the mixture, the emission of sulfur-containing compounds is reduced.

The disadvantage of this invention is the increased slag formation due to the mineral additive. In addition, due to the initially low reactivity, this composition is not completely gasified in the hearth zone.

An invention is also known (patent RU No. 2186093, IPC C10L 5/00, publ. 27.07.2002), describing a solid composite fuel consisting of coal (82-95 wt.%) and oil shale (5-18 wt.%) . This composite fuel is applicable for combustion in thermal power plants and boiler plants. Due to the use of a low-grade energy fuel additive, it is possible to reduce fuel costs while maintaining an acceptable level of calorific value and basic technical indicators of the fuel.

The disadvantage of this invention is the use of high-sulfur and high-ash components, which in turn imposes restrictions on the acceptability of this fuel composite for thermal power equipment.

Also known is the invention (WO 2012/054001, IPC C10L 5/44, C10L 5/14, C10L 5/48, publ. 04/26/2012), describing a solid composite fuel consisting of materials of plant origin and plastic waste. As plant components are offered: paper waste, wood, sawdust, straw, grain husks, plant stems, peat. Can be used as individual components presented, and their combinations in the amount of 60-97 wt.%. High pressure polyethylene, low pressure polyethylene and polypropylene in the amount of 3-40 wt.% can be used as a binder and the second component of the fuel composite.

The disadvantage of this invention is the heterogeneity of the components, which does not allow to provide the values of the calorific value in a narrow range, the use of relatively wet raw materials (biomass), which requires the complication of the preparation scheme of the fuel composite in the form of dryers. Also, in the case of the implementation of the presented technology, it is difficult to expand the range of components used from among the plastics common in municipal solid waste.

A fuel composite is also known (Buravchuk N. I. Fuel composites from fine-grained carbon-containing technogenic raw materials // Innovation and expertise: scientific works. - 2017. - No. 2. - P. 191-203), consisting of anthracite fines, coal sludge, biomass and binder of organic origin. The mass ratio of biomass, anthracite sludge and coal sludge is 1:1:3, respectively. This fuel composition, formed into briquettes or granules, can be sold without additional drying and using cold pressing. The use of this composition allows the use of carbonaceous waste and, through the use of biomass, to increase the allowable humidity for the formation of fuel pellets that meet strength standards.

The disadvantage of the proposed fuel composite is its complex composition and related recommendations for choosing the optimal particle size distribution for each component, which provide the strength of the fuel pellets.

An invention is also known (patent RU No. 2477745, IPC C10L 5/00, C10L 5/14, C06D 5/06, publ. 03/20/2013), describing a fuel composite containing screenings of active charcoal and ballistic powder, which are crushed to a fraction size 0.5-1.0 mm. Polyacrylamide is used as a binding component for the formation of a fuel briquette. Presented composite fuel contains: 75-86 wt.% screenings active charcoal, 10-20 wt.% ballistic gunpowder, 4-5 wt.% polyacrylamide. This invention improves the combustion characteristics of the composite compared to the combustion of charcoal. In addition, this invention solves the problems of improving the environmental acceptability of fuel and saving solid fossil resources.

The disadvantage of this invention is the fire and explosion hazard during production, transportation and storage, due to the low ignition temperature of ballistic powder.

The closest to the proposed invention is a solid composite fuel (patent RU No. 2128806, IPC F23C 1/06, publ. 04/10/1999), including the main energy component - petroleum coke and initiating additive - lean coal in the following proportions of components, wt.%: 10-15 petroleum coke; 85-90 - lean coal.

The disadvantage of the known solution is the need to provide sufficiently fine grinding to form a mixture with lean coal. It also has the disadvantage that the solution is only suitable for use in circulating fluidized bed boilers.

The technical objective of the present invention is the intensification of the combustion process of traditional fossil fuels (petroleum coke) with an energetically valuable solid-phase pyrolysis product of used tires (carbon residue).

The technical result of the proposed solid composite fuel is to intensify the process of ignition and subsequent combustion of petroleum coke by increasing the reactivity, which is expressed in a decrease in the ignition delay (from 5% to 46%) and a decrease in the temperature of the onset of intense oxidation (from 3 to 25%).

The technical problem is solved by solid composite fuel, which includes petroleum coke as the main energy component and an initiating additive.

What is new is that the carbon residue of waste tire pyrolysis is used as an initiating additive in the following ratio of components, wt.%:

Petroleum coke 50–90 carbon residue 10–50

Petroleum coke, used as the basis for composite fuel, is a by-product of the processing of high-boiling oil fractions. This raw material has found wide application in the manufacture of electrodes, corrosion-resistant equipment, and solid fuels. Petroleum coke is characterized by low content of volatile compounds and moisture, high ash content, low reactivity and high values of calorific value and carbon content.

The carbon residue is a dispersed powder obtained by pyrolysis of used tires. It has technical parameters close to petroleum coke, and is distinguished by a slightly higher content of volatile compounds.

The use of the carbon residue from the pyrolysis of used tires in the amount of 10–50 wt.% in the composition with petroleum coke makes it possible to increase the reactivity of such a mixture relative to homogeneous petroleum coke by 5–46%. This result is explained by the fact that the ignition temperature of the carbon residue of the pyrolysis of used tires is lower than that of petroleum coke, thereby heating and further thermal degradation of petroleum coke particles occurs more intensively.

An example of the practical implementation of the invention.

The original sample of petroleum coke and the carbon residue of the pyrolysis of waste tires were crushed using a ball mill.

Subsequently, the fuel components were sifted through a system of sieves for fractionating particles with a size of less than 80 μm and formed into composites with the following ratio of components, wt. %: 50 - 90 petroleum coke (main energy component); 10 - 50 carbon residue of waste tire pyrolysis (initiating component) by mixing them to a homogeneous mixture to evenly distribute the carbon residue in the petroleum coke.

A complete technical analysis of the original fuel components and their composites has been performed. The heat of combustion, ash content, humidity and yield of volatile compounds were determined in accordance with the methods of GOST 147-2013, GOST 22692-77, GOST R 52911-2020, GOST 22898-78. The elemental composition (CHNS) was determined using a Euro EA 3000 analyzer (EuroVector, Italy). Technical characteristics of solid fuel compositions and their elemental composition are given in table 1.

Table 1. Technical characteristics of fuel components and their elemental composition.

Fuel composite, wt.% Humidity,
Wa ^_ Ash content,
A ^d Volatile release,
V ^daf heat of combustion,
Q , MJ/kg Elemental composition WITH H N S O mass. % mass. % Petroleum coke NK 0.29 9.96 1.98 28.60 84.32 0.19 0.31 0.61 4.32 90 NK / 10 UO 0.31 10.50 2.52 28.46 83.59 0.25 0.30 0.84 4.22 75 NK / 25 UO 0.33 11.29 3.33 28.25 82.50 0.34 0.29 1.18 4.08 50 NK / 50 UO 0.38 12.63 4.68 27.90 80.68 0.49 0.28 1.75 3.84 Carbon Residue 0.46 15.29 7.38 27.20 77.04 0.78 0.24 2.90 3.36

The determination of the change in the reactivity of the solid composite fuel was carried out using a laboratory bench for the combustion of solid fuels. The main elements of the stand are: temperature-controlled muffle furnace "Sputnik" with a digital temperature controller (measurement error ± 1 °C); high-speed camera Photron FastCam MINI UX 100 (Photron, Japan) with image format – 1024×1024 pixels, frame rate – up to 10 ⁵ per second; a platform of a coordinate mechanism designed to introduce fuel pellets into the furnace with a displacement error in space of less than 1 mm and a PID - temperature controller OVEN TPM10 complete with a thermocouple, designed to control the temperature of the still air medium inside the combustion chamber.

For the study, a fuel sample in the form of a cone with a mass of ~1.0 ± 0.05 g was placed on the holder of the coordinate mechanism. Further, the coordinate mechanism was set in motion with the help of a signal supplied from a PC via a communication channel. The sample was introduced into a preheated temperature-controlled furnace at a temperature of 1000°C. Simultaneously with the movement of the coordinate mechanism into the combustion chamber, video recording was carried out until the moment of ignition and the combustion process of the fuel sample. The reactivity of the studied samples was carried out by comparing the ignition delay time. The ignition delay time was considered to be the time from the moment the fuel sample entered the focus of the chamber until the appearance of a glow on the surface of the sample, which corresponded to the onset of the thermal decomposition process. The temperature in the combustion chamber was controlled using a platinum-rhodium thermocouple and recorded through a PID temperature controller. Flue gases were removed to the environment using forced ventilation.

The results of the experiment indicate that the solid composite fuel is characterized by a decrease in the ignition delay time (from 5% to 46%) relative to petroleum coke.

The results of determining the ignition delay time of the experiment are presented in Table 2.

Table 2 - Ignition Delay Time

fuel composite,
wt. % Ignition delay time, s Petroleum coke NK 1.93 90 NK / 10 UO 1.83 75 NK / 25 UO 1.76 50 NK / 50 UO 1.04 Carbon Residue 0.39

Thermal analysis was also performed to characterize the oxidation process of the solid composite fuel. Oxidation was performed using an STA 449 C Jupiter thermal analyzer (Netzsch, Germany). All experiments were carried out in an air flow with a flow rate of 100 ml/min, at a heating rate of 10°C/min in a corundum crucible with a perforated lid in the temperature range of 25–1000°C, the weight of the fuel sample was 10 mg.

Based on the results of thermal analysis, the temperatures of the beginning and end of the intense oxidation process T _i and T _f , respectively, were determined graphically. The maximum rate of weight loss w _max and the corresponding temperature T _max .

The results of the experiment indicate that the solid composite fuel used is characterized by a decrease in the initial temperature of intense oxidation T _i (from 3 to 25%) and a shift in the oxidation process to lower temperatures.

The results of thermal analysis are presented in table 3.

Table 3 - Characteristics of the oxidation process

fuel composite,
wt. % T _i , °С T _f , °С W _max , wt%/min _Tmax , °C Petroleum coke 634 863 4.41 767 90 NK / 10 UO 611 843 4.04 745 75 NK / 25 UO 576 824 3.50 740 50 NK / 50 UO 521 692 4.74 570 carbon residue 508 623 7.25 580

Thus, the proposed solid composite fuel, made on the basis of explosion-proof components, makes it possible to increase the reactivity of such a mixture relative to homogeneous petroleum coke by 5-46% and reduce the temperature of the onset of intense oxidation (from 3 to 25%).

Claims (2)

Solid composite fuel, which includes petroleum coke as the main energy component and an initiating additive, characterized in that it contains a carbon residue from the pyrolysis of used tires as an initiating additive in the following ratio, wt.%: Petroleum coke 50-90 carbon residue 10-50