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Show THE DEVELOPMENT OF AN UL TRA-LOW-EMISSION GAS-FIRED CYCLONIC COMBUSTOR Tian-yu Xiong Mark J. Khinkis Institute of Gas Technology 3424 S. State Street Chicago, IL 60616 William P. Coppin Maxon Corporation 201 E. 18th Street Muncie, IN 47302 ABSTRACT PAPER NO. 46 A gas-fired cyclonic combustor has been developed for relatively low-temperature direct-air heating applications that require ultra-low pollutant emissions. High-lean premixed combustion with a flame stabilizer is adopted to achieve ultra-low emissions and high turndown operation. On the basis of analytical studies and cold modeling, a 350-kW test combustor was designed and successfully tested. Experimental results obtained using natural gas and ambient air demonstrated that the test combustor can operate steadily at high excess air up to 80% to 1 00% over a large turndown range up to 40:1. At design operating conditions, NOx emissions as low as 0.6 vppm and CO and total hydrocarbon (THC) emissions below 3 vppm* were achieved. Over the full operating range, NOx emissions from 0.3 to 1.0 vppm and CO and THC emissions below 4 vppm were demonstrated. In all tests, concentrations of N02 were less than 40% of the total NOx emissions - lower than the level of N02 emissions from combustion processes required for good indoor air quality (0.5 vppm). This paper presents the concept of high-lean premixed Ultra-low-emission cyclonic combustion, design specifications for the combustion system, and the major experimental results, including flame stability, emissions, and turndown performance. INTRODUCTION Fuel-fired hot-air systems are widely used in a variety of industrial, commercial, and residential applications where relatively low-temperature hot air is needed for heating or drying. Basically, the two different approaches for heating air by a primary heat source provided from fuel combustion are 1) indirect and 2) direct. In indirect systems, the process air is not mixed with the products of combustion (POCs) but rather extracts the heat of combustion via a heat exchanger. In direct systems, the process air is mixed with POCs and then delivered to the heating or drying process. Therefore, almost 100% of the heat of fuel combustion is utilized for the process in direct-fired systems. In addition, direct-fired hot-air systems require the lowest capital and operating costs because expensive heat-exchange equipment is not required. However, the disadvantage of direct-fired systems is that POCs, which contain varying amounts of nitrogen oxides (NOJ, carbon monoxide (CO), unburned total hydrocarbons (THC), and possibly particulate matters (PM), can "vitiate" the environment (for example, indoor and * Unless otherwise specified, all pollutant emission data in this paper are corrected to 15% 02. 1 |