Life cycle assessment of straw fast pyrolysis based on energy integration

doi:10.11949/0438-1157.20210081

Abstract

Abstract:

The fluidized fast pyrolysis technology of biomass has the advantages of simple equipment structure and high yield of liquid phase products. However, a large amount of circulating fluidizing gas needs to be heated to the reaction temperature during the reaction process, so there is a problem of high energy consumption. And, the straw recycling in China is facing the problems of widely distributed, centralized processing and transportation with high cost. Based on the pilot test with a 1000 t/a processing capacity, the research optimized the design of fluidized fast pyrolysis, constructed a straw fluidized fast pyrolysis system. Through heat exchange, multi-stage separation and condensation, the heat recovery of the system is accounting for 66.02% of the total heat, in which the system realized heat self-sufficiency. Through life cycle assessment, the analysis shows that the greenhouse gas emission of the whole system is -428.42 kg CO₂ eq, which greatly reduces the impact on the environment compared with straw open burning.

Key words: straw, fluidization, fast pyrolysis, life cycle assessment

摘要：

生物质的流态化快速热解技术具有设备结构简单、液相产物得率高等优点，但反应过程中大量的循环流化气体需要加热至反应温度，因而存在能耗高的问题。针对我国农村秸秆分布广和集中处理运输消耗大等特点，在已有1000 t/a处理规模的中试基础上，提出了具有能量回收效率高、秸秆处理集约化的流态化快速热解系统。系统通过高温气相换热、冷凝与提馏相结合等方法，回收了占总需求66.02%的热量，得到含水率小于3%的热解原油及富水木醋液产品，并通过烟气燃烧供热实现了系统热量自给。通过生命周期评价表明，整个系统的温室气体排放为-428.42 kg CO₂ eq，与秸秆直接焚烧相比大幅度降低了对环境的影响。

关键词: 秸秆, 流态化, 快速热解, 生命周期评价

CLC Number:

TQ 062

ZHANG Xi,ZHANG Lilong,LI Rui,WU Yulong. Life cycle assessment of straw fast pyrolysis based on energy integration[J]. CIESC Journal, 2021, 72(5): 2792-2800.

张溪,张立龙,李瑞,吴玉龙. 基于能量集成的秸秆生物质快速热解生命周期评价[J]. 化工学报, 2021, 72(5): 2792-2800.

Figures/Tables 9

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阶段	输入		输出
阶段	资源	数量	产品	数量
秸秆生产采收	N肥	2.60 kg	秸秆（含水率70%）	2216.67 kg
	P₂O₅	1.09 kg
	K₂O	3.06 kg
	农药	0.18 kg
	灌溉水	108.55 m³
	电力	48.85 kWh
	柴油	2.64 kg
秸秆运输	货车	9.5 t·km	秸秆（含水率30%）	950.00 kg
秸秆破碎干燥	秸秆	950.00 kg	秸秆（含水率5%）	700.00 kg
秸秆破碎干燥	滚筒电机	4.5 kWh	秸秆（含水率5%）	700.00 kg
流态化热解	秸秆（含水率5%）	700.00 kg	生物炭	126.00 kg
	空气	500.00 kg	高温气相^①	1958.00 kg
	循环流化气	1540.00 kg	CO₂^②	234.03 kg
	空气风机	7.24 kWh	H₂O^③	38.54 kg
	流化气风机	27.45 kWh	N₂^④	383.43 kg
冷凝分离	高温气相^①	1958.00 kg	生物原油	133.00 kg
	脱水塔循环泵	2.20 kWh	木醋液	285.00 kg
	循环水	0.54 m³
	醋液塔循环泵	3.00 kWh
	水泵	3.70 kWh

阶段	输入		输出
阶段	资源	数量	产品	数量
秸秆生产采收	N肥	2.60 kg	秸秆（含水率70%）	2216.67 kg
	P₂O₅	1.09 kg
	K₂O	3.06 kg
	农药	0.18 kg
	灌溉水	108.55 m³
	电力	48.85 kWh
	柴油	2.64 kg
秸秆运输	货车	9.5 t·km	秸秆（含水率30%）	950.00 kg
秸秆破碎干燥	秸秆	950.00 kg	秸秆（含水率5%）	700.00 kg
秸秆破碎干燥	滚筒电机	4.5 kWh	秸秆（含水率5%）	700.00 kg
流态化热解	秸秆（含水率5%）	700.00 kg	生物炭	126.00 kg
	空气	500.00 kg	高温气相^①	1958.00 kg
	循环流化气	1540.00 kg	CO₂^②	234.03 kg
	空气风机	7.24 kWh	H₂O^③	38.54 kg
	流化气风机	27.45 kWh	N₂^④	383.43 kg
冷凝分离	高温气相^①	1958.00 kg	生物原油	133.00 kg
	脱水塔循环泵	2.20 kWh	木醋液	285.00 kg
	循环水	0.54 m³
	醋液塔循环泵	3.00 kWh
	水泵	3.70 kWh

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