ANALYSIS OF BURNING TIME AND STRENGTH OF CHARCOAL BRIQUETTES BASED ON TREE LEAF RESIN

ABSTRACT

This article presents the results of research focused on the briquetting of coal powder, specifically examining its burning time and durability. Tree leaf resin was selected as the binding agent, and a piston press device was recommended for compressing the coal powder along the horizontal axis. Experimental studies were conducted to produce briquette products and substantiate their parameters within the recommended briquetting design. During the experiments, various parameters were varied, including the concentration of the fermented resin solution (10%, 15%, and 20%), the amount of water added (10%, 15%, and 20%), the number of revolutions of the curved mechanism (20, 25, and 30 rpm), and the diameter of the working chamber (15, 20, and 25 mm). The results indicated that at the lower load limit, the burning time of the briquette increased from 86 to 110 seconds, while at the upper load limit, it rose from 95 to 124 seconds. Additionally, the strength of the briquette was found to increase from 0.11 to 0.53 H/cm². The experimental data were mathematically analyzed, and an empirical equation for determining the strength of the briquettes was proposed.

АННОТАЦИЯ

В данной статье представлены результаты исследований, посвящённых брикетированию угольного порошка с целью определения времени его горения и долговечности. В качестве связующего материала была выбрана смола, полученная из листьев деревьев, и рекомендовано использование поршневого прессового устройства для прессования угольного порошка вдоль горизонтальной оси. Проведены экспериментальные испытания, направленные на получение брикетов и обоснование их параметров в рекомендованной конструкции брикетирования. В ходе исследований варьировались параметры: концентрация ферментированной смолы в растворе (10%, 15% и 20%), количество добавляемой воды (10%, 15% и 20%), число оборотов кривого механизма устройства (20, 25 и 30 об/мин) и диаметр рабочей камеры (15, 20 и 25 мм). Результаты показали, что при нижнем пределе нагрузок время горения брикета увеличивалось с 86 до 110 секунд, а при верхнем пределе – с 95 до 124 секунд. Также установлено, что прочность брикета возросла с 0,11 до 0,53 Н/см². Данные экспериментов были подвергнуты математической обработке, и предложено эмпирическое уравнение для определения прочности брикетов.

Keywords: Briquetting, coal powder, burning time, durability, binder, leaf resin, piston pressing device, briquette strength, empirical equation.

Ключевые слова: Брикетирование, угольный порошок, время горения, долговечность, связующее средство, смола листьев, поршневое прессовое устройство, прочность брикетов, эмпирическое уравнение.

Introduction

The global advancement of high-quality coal briquette fuel technology and briquetting devices is of paramount importance in the context of sustainable energy production. This development involves the optimization of various technical parameters to enhance product durability, increase burning efficiency, and maximize heat output while minimizing ash generation and energy consumption during combustion [1]. The effective briquetting of coal powder necessitates the modernization of traditional technologies, consideration of the infrastructural characteristics of production facilities, and the selection of cost-effective binding additives [2].

Recent research has underscored the significance of employing innovative briquetting methods that focus on rationalizing the production process. This includes the evaluation of binders that facilitate mechanical activation, structural modification, and the enhancement of surface energy in briquettes, which are critical for improving the fuel's strength and structural properties [3]. Such advancements not only contribute to the overall efficiency of the briquetting process but also align with global sustainability goals by producing cleaner-burning fuels.

Significant scientific and research efforts have been undertaken in countries such as Canada, the United States, Russia, China, Ukraine, and Belarus, among others, to enhance fuel briquette production technologies [4]. However, challenges remain, particularly in the development and implementation of low-cost binders and energy-efficient construction designs that are conducive to the briquetting of coal dust. Addressing these issues is essential for improving the economic viability of briquette production and for promoting the widespread adoption of briquette fuels as an alternative energy source [5].

Methods

It is known that the development of a new method of production of coal briquettes with the help of a binder requires the selection of types of binder products that ideally satisfy all the requirements at the same time. In this case, the low cost of the required binder, the ability to increase the combustion heat of the obtained agglomerated fuel, and the ability to give high mechanical strength to the briquette are of great importance.

Today, coal mining, their transportation and supply of high-quality fuels for consumers, as well as industries dealing with coal fuels, are one of the main sectors. The coal industry includes the processes of coal mining (in some cases enrichment, briquetting) and delivery to consumers. The most preferred and effective method of coal mining is open pit mining. If the coal deposits are located in a pit, it is mined in a closed (mine) method. Open methods are mainly used in the coal industry of Uzbekistan. This method also has its drawbacks. For example, due to being in open basins, the moisture content of the coal is high, and it decomposes under the influence of atmospheric heat. This results in the formation of fine coal dust in coal mines. This indicator is around 60%.

The rational use of these generated coal powders by consumers presents several challenges. For example, during loading, transportation and consumer use, a large part of the product remains as waste. Various pressing methods are used in our republic to eliminate emerging problems. These include screw, roller and manual pressing devices. Coal pulverization is achieved by placing it in a certain container, giving it high pressure and adding binders to its composition [6,7].

Research object

In response to the identified requirements, we conducted a comprehensive scientific investigation to address these challenges. Initially, we examined binders that have shown promise in recent years, evaluating their physicochemical properties. Following this, we performed a systematic four-step analysis of briquetting devices using the MatLab program. The findings from this analysis indicated that coconut waste, paraffin, by-products from oil production, bark from thorny plants, and multi-component resins derived from tree leaves are the most effective binders for coal powder briquetting under the conditions present in Uzbekistan.

Our evaluation of briquetting devices revealed that utilizing an advanced return force during the briquetting process enhances the strength of the compressed product by 1.23 times when compared to methods relying on centrifugal and impact forces [8]. Consequently, based on these analytical results, tree leaf resin was chosen as the binding agent. We also designed a piston press specifically for compressing coal powder along a horizontal axis and developed its construction. Figure 1 illustrates the schematic representation of the pressing device, while Figure 2 provides an overview of the laboratory equipment developed for this purpose.

Figure 1. Scheme of the pressing device

Figure 2. Overview of the laboratory device

This device distinguishes itself from other presses by its ability to incorporate only small amounts of additional binders during the coal powder pressing process. It operates at high pressure, features a straightforward construction, and delivers high efficiency. Coal powder is sourced from storage facilities and sorted to include only particles smaller than 5 mm. Edible fractions are separated from the remaining material, which is then crushed. The sorted coal powder is subsequently dried at temperatures ranging from 80 to 100 ℃ before being conveyed to the pressing station.

The device operates as follows: Initially, the electric motor (1) transmits rotational motion through the clutch (2) to the reducer (3). The reducer then transfers this motion to the drive disk (6) at a 10:1 ratio. The driving disk conveys the movement to the shaft (8) via the crank mechanism (7). As a result, rod (8) moves the piston (10) in a forward and backward motion. The product is fed into the press hopper (13), where, in the piston’s first position, coal powder is loaded into the cylinder (11). Once the piston (10) shifts to its second position, it closes off the hopper (13), initiating the pressing operation.

During this operation, the briquetting process occurs within the forming section, the third component of the device. Here, the coal powder is compacted under high pressure within the conical stirrer located inside the cylinder (12). The resulting briquette, which emerges from the forming section, is of a specific length and is subsequently cut to the desired dimensions using specialized automatic cutters [9,10].

Results

Experimental investigations were carried out to produce briquette products and validate their parameters within the proposed briquetting design. During these studies, several variable parameters were examined, including solutions of fermented leaf waste resin in water at concentrations of 10%, 15%, and 20%. The amounts of water used were also varied at 10%, 15%, and 20%. Additionally, the rotational speeds of the device's curved mechanism were set at 20, 25, and 30 revolutions per minute (rpm), with working chamber diameters of 15, 20, and 25 mm being tested. It was also essential to consider the humidity of the external environment during the research.

The coal powder selected for this study was sourced from the Angren mines. For the experiments, the aforementioned variable parameters included the 10%, 15%, and 20% solutions of fermented leaf waste resin in water, as well as the specified percentages of water and resin mixed for each kilogram of coal powder. The total mass of the binder and powder was established at 10 kg. Following the experiments, the briquette products were air-dried for a period of 48 hours, after which the burning time for each briquette was recorded. The findings from the experiments are summarized in Table 1.

Table 1.

Burning time of briquette product for different values of variable parameters

The data illustrated in Table 1 indicate that an increase in the quantity of fermented leaf resin and binder within the coal powder-water mixture leads to higher moisture levels in the final product. This increase in moisture content subsequently prolongs the burning duration of the briquettes. Moreover, both the rotational speed of the crank mechanism and the diameter of the working chamber have a significant impact on combustion time. For instance, at the lower load limits, the burning duration of the briquettes extended from 86 seconds to 110 seconds as the product's moisture content shifted from 6.29% to 6.65%. Similarly, at the upper load limits, the burning time rose from 95 seconds to 124 seconds with an increase in moisture from 7.78% to 8.23%. This variation is attributed to changes in the diameter of the working chamber.

Additionally, alterations in the parameters of the working chamber and the bending mechanism also influence the product's durability. Consequently, the study examined how these variable parameters affect the strength of the briquettes. The briquette products produced under various device settings and binder types were evaluated using the laboratory model of the SIB-145 durability testing machine. Each experiment was conducted five times, and the arithmetic mean values were calculated and compared with the theoretical predictions. The multifactorial nature of the experiments was considered, and supporting graphs were created based on the data collected at both the lower and upper limits. The results of Experiment 3 are illustrated in Figures 4 and 5.

1-When the number of rotations of the crank mechanism is 20 rpm/min; 2- When the number of rotations of the crank mechanism is 30 rpm/min;

Figure 3. Dependence of the amount of binder liquid on the strength of the briquette. When the amount of fermented leaf extract in water is 10%.

1-When the number of rotations of the crank mechanism is 20 rpm/min; 2- When the number of rotations of the crank mechanism is 30 rpm/min;

Figure 4. Dependence of the amount of binder liquid on the strength of the briquette. When the amount of fermented leaf extract in water is 15%.

1-When the number of rotations of the crank mechanism is 20 rpm/min; 2- When the number of rotations of the crank mechanism is 30 rpm/min;

Figure 5. Dependence of the amount of binder liquid on the strength of the briquette. When the amount of fermented leaf extract in water is 20%.

It can be seen from the graphical relationships presented in Figures 3, 4 and 5 that the amount of fermented leaf resin and binder in water, the amount of coal powder, and the number of twisting mechanisms increase the strength of the product. In addition, the diameter of the working chamber has a significant effect on the durability of the product. For example, when the diameter of the working chamber changes from 15 to 25 mm at the lower limit of the loads, the strength of the briquette drops by 0.46 to 0.1 H/cm². At the upper limit of the loads, when the diameter of the working chamber changes from 15 to 25 mm, the strength of the briquette drops from 0.53 to 0. A decrease of 15 H/cm² was observed.

The graphical relationships presented in Figures 3, 4 and 5 can be expressed by the following regression equations determined by the method of least squares [11,12].

The slope of the material discharge part of the nozzle is R=15°

When the amount of fermented leaf resin in water is 10%;

In the download below:

At high load:

When the amount of fermented leaf resin in water is 15%;

In the download below:

At high load:

When the amount of fermented leaf resin in water is 20%;

In the download below:

At high load:

As a result of processing the empirical formulas obtained as a result of the research, the equation for theoretical determination of briquette strength was recommended, H/cm²;

The results of the study differ from the theoretical calculation results by 3.75% and do not exceed. The quantities in equation (7) are 10, 15 and 20% solution of leaf waste tar in water, water content is 10, 15 and 20%, the number of revolutions of the device crank mechanism is 20, 25 and 30 rpm/min and the diameter of the working chamber is 15, 20 and 25 mm. is meaningful when it is between

Within the specified limits, the difference of the research results according to equation 7 does not exceed 4% on average compared to the calculated results, which means that the obtained experimental results are correct. Equation (7) can also be used in engineering calculations and in the selection of rational operating modes and parameters of the apparatus.

Conclusions

In summary, the developed device offers a viable solution to the challenges of supplying consumers with solid fuels that possess high durability, combustibility, and specific porosity. In our country, numerous tree branches are burned without being utilized, while the stems of annual plants are either left in the fields or similarly incinerated. Even when these materials are employed as fuel, they yield less heat due to their dispersed and low-density state.

The production of fuel briquettes not only enhances the efficient utilization of organic materials' thermal energy but also mitigates the release of various toxic gases that typically result from their improper combustion. When fuel briquettes are burned, no toxic gases are emitted.

These points underscore the importance of effectively utilizing various types of wood and annual plant stems in the Republic of Uzbekistan. As we look to the future, it is crucial to recognize that natural fuel reserves, such as oil, gas, coal, and fuel oil, are finite. Thus, addressing this issue is essential not only for our republic but also for the entire planet.

References:

1. Guo Z. et al. Parameter optimization of waste coal briquetting and particulate matter emissions test during combustion: A case study //Environmental Pollution. – 2022. – Т. 294. – С. 118621.
2. Khakimov A., Vokhidova N. Analysis of industrial waste with binding properties //Academia Science Repository. – 2023. – Т. 4. – №. 03. – С. 113-120.
3. Khakimov A., Vokhidova N. Characteristic of binders in briquetting brown coal (lignite) //International Journal of Advance Scientific Research. – 2023. – Т. 3. – №. 04. – С. 50-59.
4. Khakimov А. А., Salikhanova D. S., Vokhidova N. K. Calculation and design of a screv press for a fuel briquette //Scientific-technical journal. – 2020. – Т. 24. – №. 3. – С. 65-68.
5. Lesego M., Yurievna N. A. Role of state in improving energy security in developing countries: analysis of world experience //Государственное и муниципальное управление. Ученые записки. – 2018. – С. 118.
6. Nasiba V. High-pressure coal dust pressing machine //Universum: технические науки. – 2022. – №. 7-4 (100). – С. 17-19.
7. Olugbade T. O., Ojo O. T. Binderless briquetting technology for lignite briquettes: A review //Energy, Ecology and Environment. – 2021. – Т. 6. – С. 69-79.
8. Raj R., Tirkey J. V. Techno-economic assessment of sugarcane bagasse pith-based briquette production and performance analysis of briquette feed gasifier-engine system //Journal of Environmental Management. – 2023. – Т. 345. – С. 118828.
9. Saidakbarovna S. D., Akhmedovich K. A., Abdusattor o‘g‘li D. A. The current state of technologies for the production and activated clay adsorbents //International Journal of Advance Scientific Research. – 2022. – Т. 2. – №. 04. – С. 25-28.
10. Samomssa I. et al. Optimization of fuel briquette production from cassava peels, plantain peels and corn cobs //Journal of Material Cycles and Waste Management. – 2021. – Т. 23. – №. 5. – С. 1905-1917.
11. Хакимов А. А. Совершенствование технологии получения угольных брикетов с использованием местных промышленных отходов: Дисс.… PhD. – 2020.
12. Хакимов А. А. Технология Получения Качественных Брикетов С Использованием Горючих Вяжущих Компонентов //Central Asian Journal of Theoretical and Applied Science. – 2022. – Т. 3. – №. 6. – С. 459-463.