惰性粒子喷动床中反应干燥集成化制备超细碳酸钙

在一内径为42mm的惰性粒子喷动床中, 以CO2气体和Ca(OH)2悬浮液制备超细碳酸钙粒子为研究对象,实验考察了进气中CO2气体浓度、Ca(OH)2悬浮液浓度、反应温度,静床高等操作条件对产物制备的影响。结果表明,利用惰性粒子喷动床反应与干燥集成化的特点,获得了平均粒度为80 nm、含水量低于0.15%的方解石型超细碳酸钙粒子,开发了一步法制备超细碳酸钙的新工艺。     

喷动床研究与进展

叙述了近年来出现的几种改型喷动床，包括多喷头喷动床、喷动流化床、带导向管的喷动床、性粒子旋转射流式喷动床、射流喷动床的研究与进展。它们在传统柱锥形喷动床的基础上，通过增加喷口、导向管、流化气、惰性粒子或增加喷动气速等方法，来克服原有喷动床应用的局限性，拓展其应用领域。     

加压喷动床中细颗粒喷动特性

在内径分别为 186mm和 80mm的加压喷动床中 ,以空气为喷动介质 ,在 10 1～ 70 0kPa的压力范围内考察了几种不同粒度的细颗粒在加压下的喷动特性 .研究结果表明在不同的Re_t 内压力对最小喷动速度的影响不同 .实验还发现 ,随着压力的升高 ,喷动区直径增大 ,稳定操作区域增大 ,加压可明显改善喷动床的操作稳定性     

大尺寸喷动床最低喷动速度的估算

最低喷动速度是喷动床设计的重要参数之一。过去人们习惯采用Mathur-Gisher公式来计算,但由于该公式是建立在小直径床层(D_c=0.076～0.3m)实验的基础上的,故在大直径床层上应用时,产生明显的偏差。本文通过实际数据分析,提出了大直径喷动床层最低喷动速度计算的经验公式。     

新颖环形喷动床颗粒喷动特性实验研究

一种新颖的环形喷动床由内外两个不同内径、同心的垂立圆筒组成,在环形空间底部设置多个喷口,在喷口两侧布置倾斜的导流板.研究颗粒在这种喷动床内的流动特性,探讨喷口结构、颗粒种类以及床内载料量对环形喷动床颗粒喷动特性的影响.实验结果表明:颗粒在环形喷动床内分为三个明显不同的区域,即颗粒填充移动区、密相喷动流化区以及稀相夹带区.当颗粒出现分区喷动后,随床内载料量的增多,填充移动区的高度维持不变,始终等于导流板的高度,而密相喷动区的高度不断增加.风量和颗粒种类对床层最大喷动量、密相喷动高度以及床层压力分布规律有着十分重要的影响.采用不同的喷口结构时,在相同的载料量下,直向喷口的密相喷动区高度更大,而且床内各测点的平均压力大于采用斜向喷口时的相应测点压力.     

双喷嘴矩形喷动床中最小喷动速度的实验研究

在双喷嘴矩形喷动床内,以空气为喷动气体,研究了最小喷动速度的变化规律和影响因素。实验表明,双喷嘴矩形喷动床的最小喷动速度与颗粒粒径、床层高度及操作温度有关。并在综合考虑床层高度以及气体和固体颗粒的物性的基础上,得出了双喷嘴矩形喷动床最小喷动时雷诺数的经验关联式。     

喷动床发展与现状

介绍了流化床的一个分支——喷动床的发展与现状。首先简述了喷动床的发展史，然后着重讲解了有关喷动床的几个基本概念，并对喷动床的流动特性及其与传统流化床的异同点作了描述。给出了一些喷动床的床型变化及应用实例，并提供了一份有关喷动床研究的较完整的文献清单     

双喷嘴矩形喷动床压降的实验研究

在双喷嘴矩形喷动床内,以空气为喷动气体,研究了最大喷动压降与操作压降的变化规律和影响因素。实验表明：双喷嘴矩形喷动床的最大喷动压降和操作压降与颗粒粒径、床层高度及表观气速有关,而操作压降还与床体结构有关。在综合考虑各影响因素的基础上,得出了双喷嘴矩形喷动床最大喷动压降的经验关联式。     

喷动床干燥工艺综述

喷动床干燥是对传统流化床干燥的革新和改造 ,它不仅能顺利地干燥谷物等颗粒粗大的物料 ,而且适用于热敏性物料的干燥 ,同时还可以进行多项化工单元操作。与国外发展成熟的喷动床技术相比 ,国内这方面的进展则显得较为缓慢。因此 ,本文从喷动床的起步、特点、结构、流化形式及喷动机制等方面入手 ,对其进行了较为系统的介绍 ,并给出了部分参数的计算公式及热质传递方程。     

超细粉在导向管喷动床中的流化行为

以料径5μm的CaCO3超细粉为物料，对其在半圆形导向管喷动床中的流化行为进行研究，考察床层压降特性及喷嘴直径、导喷距及导向管直径对起始流化行为的影响。     

Spouted Beds of Inert Particles for Drying Suspension

A brief review of Brazilian research on drying process in spouted beds shows its relevance and evolution trends. Needs for applying this technique to dry pasty materials are discussed, focusing on a new model approach in order to overcome operational problems with particle agglomeration and with thermal efficiency. Based on this approach, two cases, drying of black liquor in a conical spouted bed of inert polypropylene particles under intermittent operation and drying of egg emulsion in a conical spouted bed of inert glass beads under continuous operation, are presented and analyzed.     

Spouted Beds of Inert Particles for Drying Suspension

ABSTRACT

A brief review of Brazilian research on drying process in spouted beds shows its relevance and evolution trends. Needs for applying this technique to dry pasty materials are discussed, focusing on a new model approach in order to overcome operational problems with particle agglomeration and with thermal efficiency. Based on this approach, two cases, drying of black liquor in a conical spouted bed of inert polypropylene particles under intermittent operation and drying of egg emulsion in a conical spouted bed of inert glass beads under continuous operation, are presented and analyzed.     

Drying of Suspensions in the Draft Tube Spouted Bed

A draft tube spouted bed dryer with inert particles was used for drying suspensions. The effects of the operating conditions on dryer throughput and product quality were investigated. Experiments were performed in a cylindrical column 215 mm in diameter with a draft tube 70 mm in diameter and 900 mm in length. The bed was made of polyethylene particles, 3.3 mm in diameter with a density of 921 kg/m³. The fungicide Zineb, calcium carbonate, calcium stearate and pure water were used as feeding materials. A drying model using the continuity and momentum equations for turbulent accelerating two‐phase flows and conventional rate equations is proposed and discussed. The work is relevant for estimating dryer performance.     

带浸没加热管的惰性粒子振动流化床干燥强度研究

采用带浸没加热管的惰性粒子振动流化床对（石灰）膏状物料干燥进行了实验研究。利用正交实验，考察了加料速率、振动条件、进气温度、进气速度、加热管功率等参数对干燥强度的影响，得出了计算干燥器干燥强度的关联式。结果表明，由于浸没加热管热量的引入，能显著增加干燥器的干燥能力，实验条件下干燥器干燥强度超过250kg·（m^3·h）^-1，干品湿含量可降至1．5％以下，质量能达到要求，相关数据可为膏状物料干燥器的设计和开发提供借鉴。     

利用连续式膜气液接触器制备纳米CaCO3:粒子形貌和膜污染（英文）

Nanosized calcium carbonate particles were prepared with a continuous gas-liquid membrane contactor. The effects of Ca(OH)2 concentration, CO2 pressure and liquid flow velocity on the particles morphology, pressure drop and membrane fouling were studied. With rising Ca(OH)2 concentrations, the average size of the particles increased. The effects of Ca(OH)2 concentration and CO2 pressure on particles were not apparent under the experimental conditions. When the Ca(OH)2 concentration and liquid flow velocity were high, or the CO2 pressure was low, the fouling on the membrane external surface at the contactor entrance was serious due to liquid leakage, whereas the fouling was slight at exit. The fouling on the membrane inner-surface at entrance was apparent due to adsorption of raw materials. The membrane can be recovered by washing with dilute hydrochloric acid and reused for at least 6 times without performance deterioration.     

超微粒子的特性、制备和应用

对超微粒子的特性、制备和应用作了简明的介绍。特别对超微粒子制备工艺的选择作了比较细致的阐述。     

不同形态纳米碳酸钙制备及应用的研究进展

本文介绍了晶形控制技术,从不同形貌角度分别对球形、针状、链锁状、立方形、片状以及无定形纳米碳酸钙的制备与应用进行了阐述与分析,并对其广阔的发展前景作了展望.