Development of prevention technique for the silica scale deposition interfering with utility systems of geothermal energy

硅垢沉积干扰地热能利用系统防治技术开发

• 批准号: 14550735
• 负责人: MORI Hidetoshi
• 金额: $ 1.79万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550735/
• 关键词: Geothermal Fluid; Geothermal Energy; Scaling; Fouling; Ultrasonic Irradiation; Scale Prevention; Silica Scale; Fouling Factor; シリカ

For the development of utilization systems of geothermal energy, it is important and emergency issue to establish the prevention techniques of scaling or fouling on heat transfer surfaces. In this research project we presented the fundamental data on scale formation mechanism which has been analyzed by a chemical engineering approach, leading to the proposal of prevention techniques, seed addition method and ultrasonic irradiation method.For the effective application of the seed addition method, scale formation mechanism has been discussed in detail. Adsorption rate was observed from the measurements of mono-and poly-silica concentrations by changing the pH value, temperature, and initial silica concentration. The results reasonably indicate that the activation energy for polymerization process is 5-8 kcal/mol, which is affected by the existing metal ions. These data are available for the design of seed addition technique.An ultrasonic irradiation technique has also been proposed for t … More he prevention of scale deposition on heat transfer surfaces. In experiments copper pipes were immersed in calcium sulfate aqueous solutions, and hot water was, flowed inside the pipes. Measurements of the mass of scale deposited on the pipe surface demonstrated significant deposition rate without ultrasonic irradiation. Under ultrasonic irradiation, on the other hand, no scale was observed. In the case of intermittent irradiation technique, it was found that the irradiation during the scale nucleation period is more effective for the prevention of scale deposition. The details of the results obtained will be published in the Kagaku Kogaku Ronbunshu (vol.30,2004).In relation to the utilization of geothermal energy, wicks which will be widely used for the transport of geothermal fluids and/or energy, were characterized experimentally. Measurements of capillary suction potential of mesh-type wicks have developed a capillary model, which reasonably makes it possible to predict unsaturated hydraulic conductivity by considering the dependency of tortuosity on saturation level, as well as to deduce a dimensionless capillary suction potential. The capillary model has also been provided to predict saturation profiles observed in a wick through which liquid flows at constant infiltration rate and draining to a liquid table.The friction factor determined from the observed capillary potential has been related to Reynolds number Re by a simple relation, which experimentally proved independent of the mesh woven-types and mesh layers consisting of a wick. The estimated product of friction factor and Reynolds number demonstrates its availability to predict,the saturated hydraulic conductivity of mesh-type wicks. The results was published in the Journal of Chemical Engineering of Japan (vol.36,2003). Less

对于地热能利用系统的发展，建立传热面结垢或污垢的预防技术是一个重要而紧迫的问题。在本研究项目中，我们提供了通过化学工程方法分析的结垢机理的基础数据，从而提出了预防技术、种子添加法和超声波照射法。为了有效应用种子添加法，详细讨论了结垢机理。通过改变pH值、温度和初始二氧化硅浓度，通过测量单二氧化硅和聚二氧化硅浓度来观察吸附率。结果合理地表明，聚合过程的活化能为5-8 kcal/mol，该活化能受存在的金属离子的影响。这些数据可用于种子添加技术的设计。还提出了超声波辐照技术来防止传热表面上的水垢沉积。在实验中，将铜管浸入硫酸钙水溶液中，让热水在管内流动。对管道表面沉积的水垢质量的测量表明，无需超声波照射即可实现显着的沉积率。另一方面，在超声波照射下，没有观察到水垢。在间歇照射技术的情况下，发现在氧化皮成核期间进行照射对于防止氧化皮沉积更有效。所获得的详细结果将发表在Kagaku Kogaku Ronbunshu(vol.30,2004)中。 在地热能的利用方面，对将广泛用于地热流体和/或能量的输送的吸芯进行了实验表征。网状吸芯毛细管吸入势的测量建立了毛细管模型，该模型可以合理地通过考虑曲折度对饱和水平的依赖性来预测不饱和导水率，并推导无因次毛细管吸入势。还提供了毛细管模型来预测在吸液芯中观察到的饱和度分布，液体以恒定的渗透速率流经吸液芯并排至液体台。根据观察到的毛细管电势确定的摩擦系数通过简单的关系与雷诺数 Re 相关，实验证明该关系与吸液芯组成的网状编织类型和网状层无关。摩擦因数和雷诺数的估计乘积证明了它可以预测网状吸芯的饱和导水率。其结果发表在日本化学工程学报(2003年第36卷)上。较少的

项目成果

Yasuda, K.: "Prevention of Scale Deposition on Heat Transfer Surfaces by Ultrasonic Irradiation"Kagaku Kogaku Ronbunshu. (in press). (2004)

Yasuda, K.：“通过超声波照射防止传热表面上的水垢沉积”Kagaku Kogaku Ronbunshu。

Hidetoshi Mori: "Dependency of Tortuosity on Saturated and Unsaturated Flow within Mesh-Type Wicks"Journal of Chemical Engineering of Japan. Vol.36, No.12. 1449-1457 (2003)

Hidetoshi Mori：“网状吸芯内的曲折度对饱和和不饱和流动的依赖性”日本化学工程杂志。

Mori, H.: "Dependency of Tortuosity on Saturated and Unsaturated Flow within Mesh-Type Wicks"Journal of Chemical Engineering of Japan. Vol.36 No.12. 1449-1457 (2003)

Mori, H.：“网状吸芯内的曲折度对饱和和不饱和流动的依赖性”日本化学工程杂志。

安田 啓司: "超音波照射による伝熱面へのスケール析出防止"化学工学論文集. Vol.30(印刷中). (2004)

Keiji Yasuda：“通过超声波照射防止传热表面结垢”《化学工程杂志》第 30 卷（出版中）。

Hidetoshi Mori: "Dependency of Tortuosity on Saturated and Unsaturated Flow within Mesh-Type Wicks"Journal of Chemical Engineering of Japan. Vol.36,No.12. 1449-1457 (2003)

Hidetoshi Mori：“网状吸芯内的曲折度对饱和和不饱和流动的依赖性”日本化学工程杂志。