Proceedings
of the Tomsk Polytechnic Institute
of the Order of the October Revolution and the Order of the Red Banner of Labor
named after S. M. Kirov

Vol. 198　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　1974

EFFECT OF PRESSURE AND HOLDING UNDER PRESSURE ON THE STRENGTH OF THERMOBRIQUETTES

S. I. SMOLYANINOV, S. G. MASLOV, Yu. P. BELOUSOV

(Presented by the Scientific-Methodological Seminar of the Faculty of Chemical Technology)

It was established by us earlier [1, 2] that the optimum holding time under pressure in the thermobriquetting of peat is 120 seconds. The briquetting presses currently in use operate with a much shorter holding time. In addition, a longer holding time

Fig. 1. Dependence of the crushing resistance of thermobriquettes on holding under pressure.

Briquetting pressure: 1—100 kg/cm²; 2—200 kg/cm²; 3—300 kg/cm²; 4—400 kg/cm²; 5—700 kg/cm²

entails an increase in the fleet of pressing equipment and, consequently, an increase in capital costs and operating expenses.

In the present work, in order to reduce the holding time, an attempt was made to increase the briquetting pressure, proceeding from the known proposition that polymerization and condensation reactions are accelerated as pressure increases. These reactions underlie the hardening of liquid products released when peat is heated to the thermobriquetting temperature. The latter is one of the reasons for holding under pressure during thermobriquetting of peat [1].

Fig. 2. Dependence of the abrasion of thermobriquettes on holding under pressure.
Briquetting pressure: 1—100 kg/cm²; 2—200 kg/cm²; 3—300 kg/cm²; 4—400 kg/cm²; 5—500 kg/cm²; 6—700 kg/cm².

The experimental part of the work was carried out with air-dry peat from the Tagan bog in Tomsk Oblast. The method for obtaining and testing thermobriquettes was described earlier [3]. The holding time was varied from 0 to 120 seconds, and the briquetting pressure from 100 to 700 kg/cm². The data obtained are shown graphically in Figs. 1 and 2.

It is apparent from the graphs that, with increasing pressure, at any holding time, the strength of the thermobriquettes increases. At first it increases sharply: the curves rise steeply upward (Fig. 1) or fall steeply downward (Fig. 2); then there is a transition, and subsequently the curves run almost parallel to the “holding time” axis. It may be noted that the greater the briquetting pressure, the more rapidly the curve passes through the region of abrupt changes, that is, the strength of the briquettes reaches its optimum value. For example, thermobriquettes with a crushing strength of 310 kg/cm² can be obtained with the following combinations of briquetting pressure and holding under pressure: 1) 300 kg/cm² and 30 sec; 2) 200 kg/cm² and 120 sec; 3) 400 kg/cm² and 5 sec; 4) 500 kg/cm² and 0 sec.

From the above it follows that, in thermobriquetting, the holding under pressure can be substantially reduced by replacing its effect with a higher briquetting pressure.

LITERATURE

1. S. I. Smolyaninov, V. E. Voronin. Obtaining peat thermobriquettes under high-speed heating conditions. Peat Industry, 4, 26, 1962.

2. S. I. Smolyaninov, S. G. Maslov. Obtaining fuel-smelting materials from milled peat by the thermobriquetting method. Proceedings of the Siberian Branch of the Academy of Sciences of the USSR, Series of Technical Sciences, No. 6, issue 2, 112–116, 1964.

3. S. I. Smolyaninov, A. M. Denisov. Effect of briquetting pressure and temperature on the mechanical properties of peat thermobriquettes. Proceedings of TPI, vol. 112, 82–87, 1963.