Tests of burners for rotary furnaces

Abstract

In organizing a system for firing of rotary furnaces, experience in operating with bu~e~ equipment developed in the refractory and cement industries is used. Existing publications [!, 2] are devoted primarily to the operation of furnaces and do not provide information on the results of tests of burners and the characteristics of flames.The authors of this article have obtained the technical characteristics of burners developed in the Eastern Refractory Institute (range of control, chemical undercombustion of the fuel, character of temperature distribution) and also experimental data on the rules of burnout of fuel under conditions close to the conditions of development of the flame in a rotary furnace with supersonic flow of the jet and various designs of burners.The tests were made on an experimental unit which was a geometrically similar model of the unloading portion of a 3.6-m rotary furnace. The stand was made in the form of a horizontally placed cylindrical lined combustion chamber 1 with a 1.36-m diameter and a 6.0-m length, enclosed in a water-cooled shell (Fig. i). On one side of the chamber at a distance of 0.4 m there is an end sheet with a center hole for the burner 2. The gap between the chamber and the end sheet is closed and imitates the unloading slot of the furnace, in the lower portion of which is located the damper 3 for regulating the entry of air into the furnace. Along the length of the combustion chamber there are 14 holes for inserting measuring probes 4 into the flame.Models of three types of burners were investigated.The burners had the same housing, which was a tube with a 35-mm inside diameter and a l-mm length ending in an interchangeable orifice (Fig. 2).The burner with orifice A had a conical throttle narrowing the flow of gas in its path and forming with the cylindrical orifice a controllable cross section Laval ring orifice. The burner with orifice B differed from the burner with orifice A in the presence of two Laval ring orifices, one of which, the inner, was controllable.In the burner with orifice C the conical throttle was broadened in the path of movement of the gas and the ring outlet cross section was greater than the inlet cross section of the orifice, which provided an ultrasonic gas flow rate. Inside the burner there was a rod with a thread for fastening the throttle and the drive for longitudinal movement of the rod with the throttle.A characteristic feature of fuel combustion in a rotary furnace is the fact that the gas burns in a diffusion flame in the operating space of the furnace. The intensity of combustion depends upon the rate of mixing of gas with air entering the operating space from the cooler, both as a result of vacuum created by the exhaust fan and injection created by the high-speed gas jet. The rate of mixing of gas with air increases intensely with the creation of a highly turbulent gas jet with supersonic gas flow. In this work the rate of flow of natural gas from the burner was varied from 432 to 582 m/set.Calculations of the burners were made using ...