精馏塔的控制方法浅析

介绍了精馏塔的一般调节方法,分别阐述了精馏塔塔压的控制方法、塔釜温度的控制方法、塔顶温度的控制方法、塔釜液面的控制方法。阐述了加压塔和常压塔塔压的调节方法;介绍了通过控制塔釜蒸汽进气量控制塔釜温度;阐明了控制回流量和回流温度控制塔顶温度的方法;介绍了塔釜液面稳定的重要性以及如何控制塔釜液面稳定的方法。最后阐明了塔的能够维持正常操作的其它的约束条件。     

脱乙烷塔系统存在的问题及优化

针对独山子2号乙烯装置脱乙烷塔出现的塔顶物流丙烯含量高,塔釜液在线分析乙烷超标,对脱乙烷塔进料、塔釜出料,前向预切割系统的设计数据和运行数据进行分析,得出2号预切割塔进料温度高是造成脱乙烷塔塔顶温度高、丙烯损失量大的原因。通过技改增加旁路调节,降低了脱乙烷塔进料量和进料温度,提高了脱乙烷塔精馏效果,降低了脱乙烷塔顶碳三损失和釜液中碳二损失。     

酯化反应“快循环”产生的原因及对策

聚酯装置生产负荷超过100%后,酯化釜经常出现"快循环"。经过分析,PTA平均粒径的变小是引起酯化"快循环"的直接原因。通过对酯化釜浆料进料和反应温度的及时调整,合理利用2种调节手段,才能确保生产平稳,产品品质优等。     

反应精馏—萃取联合过程合成乙酸乙酯的研究

将固体酸作为主催化剂与不锈钢填料以一定的规律置于反应精馏塔中，以一路易斯酸作为辅助催化剂置于塔釜中，采用反应精馏的形式连续合成乙酸乙酯。塔顶全部酯相经萃取脱去水后再引出部分回流到反应精馏塔塔顶，构成了反应精馏－萃取联合过程。该过程酯化转化率高，酯相带水能力强，减少了回流比，降低了能耗，提高了设各的生产能力。     

乙烯利酯化搅拌反应器的改进与模拟优化

利用计算流体力学（CFD）技术对乙烯利酯化搅拌釜内流场进行了模拟研究,对比了工业酯化釜和新酯化釜的气体分散效果等反应器性能。结果表明,工业酯化釜因桨叶形式不当、桨间距过小等原因,气体分散效果很差;新改进的酯化釜依照工艺要求,调整了桨叶结构,增加了挡板,使气体分散效果得到明显改善,反应器液层空间得到有效利用。模拟研究结果可为工业酯化釜装置的技术改进提供一定的指导。     

间歇精馏分离杂醇溶液的实验研究

通过间歇精馏分离杂醇溶液,得到浓度≥99%的异丁醇和正丁醇产品,并对分离过程中塔顶浓度随时间的变化趋势,塔顶、塔釜温度随时间的变化趋势进行了实验研究及数据分析。结果表明:随着精馏过程的进行,塔顶产品浓度、塔顶温度、塔釜温度呈现逐渐上升的趋势,但在合格产品采出阶段,塔顶产品浓度、塔釜温度、塔顶温度比较稳定,为工业生产回收异丁醇和正丁醇提供了有效的操作依据。     

反应精馏——萃取联合过程合成乙酸乙酯的研究

将固体酸作为主催化剂与不锈钢填料以一定的规律置于反应精馏塔中，以一路易斯酸作为辅助催化剂置于塔釜中，采用反应精馏的形式连续合成乙酸乙酯。塔顶全部酯相经萃取脱去水后再引起部分回流到反应精馏塔塔顶，构成了反应精馏－萃取联合过程。该过程酯化转化率主，酯相带水能力强，减少了回流比，降低了能耗，提高了设备的生产能力。     

最新专利

PBT装置酯化釜的清洗方法（公开号CN102211102A公开日2011．10．12申请人中国石油化工集团公司） 该发明涉及PBT装置酯化釜的清洗方法,属于化工生产技术领域。以三甘醇为清洗剂,按以下步骤实施：将酯化釜、工艺塔、清液贮槽、污液贮槽及相应管道内的物料全部排尽。酯化釜处于降温充氮状态,釜温低于150℃,将三甘醇由清液贮槽经工艺塔卸入酯化釜,其液位漫过釜内加热列管的高度,然后对酯化釜进行缓慢升温至255℃,维持在该温度下蒸煮浸泡10—15h。清洗物从酯化釜出口排向污液贮槽,在污液贮槽内部冷却至80℃之后,用泵排出装桶,最后用生产水对装置进行全面清洗。该方法可以有效清洗PBT装置酯化釜,釜内壁及列管外壁上的大多数结焦碳化物松动并被清除,产品色值、酯化釜供热效率、过滤器使用周期等情况明显好转。     

第一酯化釜压力控制阀失灵下的生产控制

介绍第一酯化釜压力调节阀突发故障,无法控制酯化压力,所采取的紧急措施。在尾气排放管线上加装一调节阀,调节不凝性尾气的排放量来控制酯化系统的压力,开车得以继续进行。整个酯化系统都在正压下运行,工艺参数作相应调整,酯化率和切片质量未受影响。     

横河DCS在PET酯化釜上的应用

从系统硬件、系统软件、系统网络3个方面介绍了横河公司的CENTUM—CS3000控制系统的组成。以酯化釜回流EG的流量控制、酯化釜液位控制系统和酯化釜搅拌电机联锁为例,论述了该控制系统在生产中的应用。     

酯化分馏控制的影响因素及改进措施

通过实例介绍酯化反应产生的水、游离EG的气速和回流液流量对分馏的影响及几种干扰分馏控制的因素。改变操作方法,用控制分馏柱中温、检测,保证柱顶温代替原控制柱顶温,用计量泵更换调节阀来控制回流量,建立适用于本装置的酯化内、外温及进料速度和酯化分馏标准曲线,对出现故障的分馏柱及时整改,定期校验测量仪表等可以提高产品质量,保证生产连续稳定。     

REDUCING STATIC DEVIATIONS OF PRODUCT QUALITIES IN THE TEMPERATURE CONTROL OF AN IDEAL HEAT-INTEGRATED DISTILLATION COLUMN

Two strategies are proposed in this work for the reduction of static deviations of product qualities in the dual-point temperature control of a simulated ideal heat-integrated distillation column. The key to achieve this purpose is to sense the changes in operating conditions and make appropriate adjustments simultaneously to the set-points of the top and bottom control loops. The first method is based on the inferential signals extracted from the composition of products and the second one from the temperatures of the top and bottom stages. Both strategies are intensively studied through the operation of the simulated ideal heat-integrated distillation column separating a binary equimolar mixture of benzene and toluene, and it is found that they could work effectively to decrease the static deviations in product qualities. The strategies are characterized by great simplicity in principle and a relatively small effort in process modeling, thereby allowing wide applications in the operation of various distillation columns with a dual-point temperature control scheme.     

Distillation Tower with Distributed Control Strategy: Feed Temperature Loads

Distillation towers require control systems adjusted to rapidly reject loads. Temperature control of these units is normally carried out at the bottom and top of the column, increasing the tower response time. In this paper, a change in this temperature control configuration is proposed through the introduction of heating points distributed among the trays throughout the column. The proposed strategy was tested in an experimental unit with an ethanol‐water mixture applying a conventional approach (control at bottom and top only) and the proposed distributed configuration (bottom, top and tower trays) with feed temperature disturbance. The results showed a significant reduction in the time required for the column to stabilize after the load introduction, compared with the conventional approach, making faster dynamics possible.     

Design and control of acetic acid dehydration system via heterogeneous azeotropic distillation

Acetic acid dehydration is an important operation in the production of aromatic acid, such as terephthalic acid or in the manufacture of cellulose acetate. Although acetic acid and water does not form azeotrope, but using simple distillation to separate these two components is not practical. The reason is because the system has tangent pinch on the pure water end, thus it is more customary in industry to use an entrainer via a heterogeneous azeotropic distillation column system for the separation. In this study, a suitable entrainer is selected from three candidate acetates through rigorous steady-state simulation of this system. Optimum process design and operating condition are determined to keep high-purity bottom acetic acid composition and also keep a small acetic acid loss through top aqueous draw. Furthermore, the overall control strategy of this column system is proposed to hold both bottom and top product specifications in spite of feed rate and feed composition load disturbances. The proposed overall control strategy is very simple requiring only one tray temperature control loop inside the heterogeneous azeotropic column.     

Offset‐Free Inferential Feedback Control of Distillation Compositions Based on PCR and PLS Models

An offset‐free inferential feedback control strategy for distillation composition control using principal component regression (PCR) and partial least squares (PLS) models is presented in this paper. PCR and PLS model based software sensors are developed from process operational data so that the top and bottom product compositions can be estimated from multiple tray temperature measurements. The PCR and PLS software sensors are then used in the feedback control of the top and bottom product compositions. With this strategy the problem of substantial time delay in composition analyzer based control and of substantial bias in single tray temperature control can be overcome. A practically very important issue in software sensor based feedback control is that static control offsets often exist due to a static estimation bias, especially when the process operating condition changes. A technique for eliminating the static estimation bias and the resulting static control offsets through mean updating of process measurements is proposed in this paper. Applications to a simulated methanol‐water separation column demonstrate the effectiveness of this control strategy.     

尿素醇解法合成碳酸二甲酯催化精馏工艺模拟

在AspenPlus平台上对尿素醇解法合成碳酸二甲酯反应精馏工艺进行模拟,针对反应精馏塔塔顶冷凝器结晶堵塞问题,优化了采出方式,提高了塔顶温度,以防止结晶。     

精馏塔持续放空原因剖析

以脱水塔为例,用沸点组成图研究了精馏塔塔顶混合气相冷凝过程中,塔顶压力与冷凝液泡点的关系,从而根据冷凝液实际温度判别放空原因。从脱水塔塔顶冷凝液过冷现象认为压力升高与冷凝能力无关,指出不凝气积聚是导致精馏塔持续放空的主要原因。     

MTBE-C_4-甲醇的蒸馏-渗透汽化集成分离过程设计

<正>国内现有甲基叔丁基醚（MTBE）生产装置20余套,年生产能力约50万t,分化工及炼油型2种工艺路线。1994年以前建成的大多采用筒式反应器技术,1994年以后则以齐鲁石化公司研究院开发的预反应加催化蒸馏技术为多。无论是化工型还是炼油型工艺路线,无论是采用筒式反应器还是催化蒸馏技术,最后均需用水洗工艺将C_4中的甲醇脱除,此工艺设备投资大、操作繁、耗能高。渗透汽化（PVAP）膜分离是近十几年来颇受注目的一项新型膜分离技术,具有一次性分离度高、设备简单、无污染、低能耗等优点,对某些用常规分     

Distillation column control: The use of feed temperature to respond to modest variations in feed composition

Most distillation columns operate with feed temperature controlled to some fixed value at or close to the boiling point of the feed, variations in this temperature being seen as unwanted disturbances to the column. Conventional control schemes can meet top and bottom composition specifications within the scope of the column but at the price of long response times due to the considerable inventory of a column in relation to its throughput. This paper shows that by admitting the feed temperature as a control variable and using feedforward control, much faster responses can be achieved.     

A model-based control system for a distillation column

A control concept which includes an adaptive multivariable control algorithm and an observer model has been put into practice in the operation of a distillation column which separates water from a solvent. The model yields predictions of solvent concentration in the waste water which forms the top product. Early detection of disturbances permits an adjustment of the process in time. This has resulted in an exceptionally smooth operation of the column, with a drastic reduction in solvent concentration fluctuations, observed with conventional control technology. Since the only measurements required are pressure, temperature and the rate of flow, this control system is largely free from disturbances. In addition to considerably reducing the burden on operating personnel, use of this control system has lowered the costs of waste water treatment, solvent losses, analysis expenditure and energy consumption.