OCR Text |
Show form a soot cloud. the emittance of soot clouds of this concentration have been shown to be about 0.6 by Sigel and Howell [4]. It is shown that soot or solid particles dominate the emittance of a gas cloud and can form a surface which is more capable of radiating than the gaseous components (H20 and C02)' The highly luminous flame is expected to radiate heat more efficiently and thus operating at lower peak temperatures. crI - TEST PROGRAM A. Summary of past years test and conclusions: By "CRACKER", we mean a combustion chamber designed to partially burn or crack methane gas under fuel rich conditions, which promotes soot formation with other products of combustion. The "cracker" method of gas firing takes about 25% of the furnace natural gas consumption through a separate cracker to produce soot particles. This is then re-blended with the balance of 75% of gas producing a mixture temperature of about 550°F "soot rich" gas for the burners . The "cracker" process is a separate "add-on" system that would also utilize a "bypass" design to facilitate installation. EQUIPMENT DESCRIPTION The first series of cracker tests were conducted using a test unit as shown in Figure 2 and Table-I. The heat was supplied by an oxygen/natural gas burner which fired axially into the combustion/reaction chamber. The cracking natural gas was added tangentially into the combustion chamber. The interior temperatures were monitored by thermocouples, one in the combustion chamber, two in the residence/reaction zone, one in the natural gas m~x~ng chamber, and one in the discharge port. The outer shell surface temperatures were measured by thermocouples located in positions similar to those of the inner locations. A water cooled gas sample probe was located in the natural gas fuel mixing chamber. In this part of the test we did not add the remaining (75%) natural gas to the mixing port. Soot concentrations were measured from a sample port in the discharge. During heat-up, combustion products were monitored by a Tbermox analyzer (Model CMFA-P), which continuously measured 02 and total combustibles. The Thermox was also used to adjust the oxy/ fuel burner stoichiometry before the cracking gas was introduced . All the test gas analysis were made using an Orsat. Concentrations of C02, 02 , CO, CH4, H2, N2 (by difference) was determined by the Orsat. Soot (carbon) concentration were made using an Anderson particulate measuring probe and filter media. -3- |