秸秆压块燃料炉设计与试验

农村地区采用秸秆压块燃料供暖可有效降低温室气体和大气污染物的排放。针对秸秆压块燃料炉存在自动化程度低、低效、高排放等问题，该研究基于秸秆压块燃料燃烧特性，设计了一台具有自动供料装置的秸秆压块燃料炉，采用分区燃烧、鼓风与引风耦合配风等方式，提高燃烧性能。对秸秆压块燃料炉进行性能测试，试验结果表明：通过自动供料机可以实现连续10 h小流量输送燃料，燃料输送量为2.57～4.12 kg/h；其额定热功率8 kW，热效率71.20%，耗电量3.83 (kW·h)/d；最佳燃烧工况下，粉尘、CO、NOx排放量分别为35.78 mg/m3、0.104 %、191.1 mg/m3，符合国家标准的排放限值。对燃料炉的测试与评价验证了锅炉结构合理，可为后续高自动化秸秆压块燃料炉的研发提供参考依据。

Design and experiment of a heating boiler using straw briquette as fuel

Biomass resources are rich in most rural areas in China, particularly with about 400 million tons of standard coal biomass feedstock available for energy utilization each year. However, a large amount of agricultural waste, such as straw biomass, has not been fully utilized in recent years. The straw can be densified into the briquette for space heating, in order to reduce the emission of greenhouse gases and air pollutants, according to local conditions. However, there are many challenges in the briquetting fuel boiler for the combustion of straw briquettes, including low automation, low efficiency, and high air pollutant emissions. In this study, a straw briquetting boiler was designed with an automatic feeding device using the combustion characteristics of straw briquettes suitable for rural household heating. A double-chain plate transmission mechanism was adopted in the automatic feeder, further to realize the continuous, stable, and small-flow delivery of fuel, according to the size of the briquette. The straw briquette was mainly burned in the gas phase. A dual combustion chamber structure was designed for the zonal combustion of volatile matter and fixed carbon. The combined air supply with air induction was adopted to improve the combustion performance for the full combustion of fuel. The flue gas circulation devices were also added to reduce NOX emissions. A special igniter was adopted to significantly shorten the ignition time for the biomass. The automatic rocking grate system was adopted for the removal of intermittent ash, and the fuel layer was loosened at a fixed time to increase the contact area between fuel and air. A performance test was conducted in the straw briquette fuel boiler. The experimental results show that the automatic feeder continuously delivered the fuel at a stable, small-flow rate for 10 h with a fuel delivery volume of 2.57-4.12 kg/h, fully meeting the heating demands of different users. The rated thermal power of the fuel boiler was 8 kW. The positive balance efficiency and reverse balance efficiency of the fuel boiler were 71.20% and 71.51%, respectively, of which the heat loss was 4.11%, suitable for indoor heating. The power consumption was 3.83 (kW·h)/d. The emission concentrations of dust, CO, and NOx were 35.78 mg/m3, 0.104 %, and 191.1 mg/m3, respectively, under the optimal combustion conditions, which fully met the emission limits of national standards. The test and evaluation of the fuel boiler can be used to verify the boiler structure. The finding can provide a strong reference for the subsequent design in the high-automatic straw briquetting fuel boiler.