The cross-flow high-efficiency low-nitrogen coal powder burner for cement rotary kilns developed by Yangzhou Yinyan Machinery Co., Ltd. has been granted a national utility model patent. This patent not only effectively addresses the issues of low coal powder combustion concentration, excessive primary air usage, and poor energy-saving effects in existing rotary kiln burners, but also effectively resolves the prominent problem of high nitrogen oxide emissions from current burners.

During the interview, the reporter learned that the burners currently used in cement rotary kilns generally adopt a discrete layout of Laval supersonic nozzle design, which has strong secondary air capability. However, the Laval nozzle has a fixed outlet area, and the axial air flow intensity can only be adjusted through the upstream butterfly valve. If the outlet area needs to be adjusted to accommodate fuel fluctuations, the kiln must be stopped to replace the nozzle, resulting in poor adaptability. In addition, the Laval nozzle reduces the contact time between coal powder and secondary air through the internal arrangement of coal-air, which does not significantly lower NOx emissions and has no practical application value.

To address the above issues, Yangzhou Yinyan Company has innovated the burner design concept by increasing the coal powder delivery concentration and reducing the primary air usage to minimize the amount of cold air entering the kiln. Without adding other equipment, it utilizes the combustion characteristics of coal powder to increase the coal powder delivery concentration, changing the jet conditions of the combustion air after the coal powder is ejected, creating an oxygen-deficient area in the initial stage of combustion to improve the retention time and temperature level of the fuel in the fuel-rich area, increasing the retention time of carbon particles in the fuel-rich area, and reducing the tendency for nitrogen oxides to form in carbon particles, thereby maximizing energy consumption reduction and significantly decreasing NOx generation.

Based on the above design concept, Yangzhou Yinyan Company has successfully solved a series of technical challenges, such as low-temperature calcination processes and technologies, industrial design of high-efficiency low-nitrogen burners, and intelligent sensor control technology for burners, successfully developing a multi-channel coal powder burner using cross-flow technology. Its core technologies include the use of cross-flow technology, low-resistance high-pressure nozzles, low-pressure honeycomb rotary cutting nozzles, adjustable swirlers, and flexible adjustable low-resistance high-efficiency nozzles. After testing by relevant cement enterprises, when the coal powder concentration is ≥5kgca, the ignition mode of coal powder combustion shifts from multiphase ignition filtering to homogeneous ignition, featuring enhanced stable combustion characteristics, reduced ignition temperature, and increased flame propagation speed; the swirling air and low-pressure rotary cutting nozzle form a cross-flow area that not only supplies sufficient oxygen to aid combustion but also creates a recirculation zone for the flame core, conducive to forming a stable flame, thereby suppressing NOx generation and significantly reducing NOx emissions, resulting in nitrogen oxide emissions from the kiln system being <0.04%—0.06%.

Recently, the Jiangsu Provincial Economic and Information Commission formulated and announced the "Implementation Plan for Clean Production Transformation in Key Industrial Sectors of Jiangsu Province," which requires the promotion and application of "Nitrogen Oxide Emission Reduction Combination Technology for Cement Kilns" in the cement industry, including Yangzhou Yinyan Company's "Energy-saving Multi-channel Low-nitrogen Burner Technology" and "Selective Non-catalytic Reduction (SNCR) De-NOx Technology."