Study of the Layered Structure of Deposit in a Biomass-Fired Boiler (Case Study)

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• 作者：Haiyu Liu ; Houzhang Tan ; Yang Liu ; Zhengning Liu ; Lin Ma ; Mohamed Pourkashanian ; Tongmo Xu
• 刊名：Energy & Fuels
• 出版年：2011
• 出版时间：June 16, 2011
• 年：2011
• 卷：25
• 期：6
• 页码：2593-2600
• 全文大小：998K
• 年卷期：v.25,no.6(June 16, 2011)
• ISSN：1520-5029

文摘

Biomass-fired boilers generally experience severe deposit problems, in particular on the intermediate temperature superheaters (SH2). In order to investigate the formation mechanisms of the deposit, mature deposits collected from the superheaters of a 30 MW biomass-fired power plant were analyzed using SEM-EDX, XRD, and XRF techniques. The results show that the deposits formed on the SH2 have an obvious layered structure, and temperature-dependent layers exist close to the tube wall, where the crystallization process is mainly affected by the steam temperature. Referenced to the three phase equilibrium diagram data in the silicate cement field, the eutectic salt KCl鈥揔₂SO₄鈥揘a₂SO₄ may be formed in a secondary step after KCl and K₂SO₄ condense on the tube surface. The chemical subsequence processes are also capable of analyzing the deposits鈥?formation process and their composition along the thickness of the deposits of any of the three superheaters in this case. As the surface temperature of the deposits increases along the thickness of the deposits, NaCl and Na₂S₂O₃ can be deposited together with the components KCl, K₂SO₄, K₂Ca(SO4)₂路H₂O, K₃Na (SO4)₂, CaSO₄, and SiO₂. K₂Ca(SO₄)₂路H₂O and K₃Na(SO₄)₂ are produced through the secondary reaction in all layers after they have deposited. In addition, monocrystal KCl (melting point 770 掳C) was found in the top layer of the deposits. The cone shape of the layered structure of the deposits also indicates that the formation of the deposits may also be affected by the pattern of the gas flow.