Introduction
O2 measurement in hydrocarbon vapor is used for safety monitoring in vacuum distillation columns in petroleum refining. With conventional paramagnetic oxygen analyzers, O2 concentrations are obtained through an extractive sampling system, which conditions the sample prior to being analyzed. Sample systems cause measurement response time delays, which are very critical in safety systems. Moreover there are many problems related to maintenance and operational costs of sample systems. The process gas to be measured contains high concentration of H2S that leads to quick corrosion of the sample system and analyzer. Another issue when using sampling systems is the sample is not representative of the process after the sample has been conditions and dew point of the sample has been modified, which affects the volume concentration of the sample.
The TDLS8000 Laser Analyzer is the solution to all these problems.
Expected Benefits
- High-speed response to meet all requirements of safety control
- Continuous monitoring of O2 concentration in-situ
- Eliminates the need for sampling and reduces the maintenance and running costs of the sampling system
Process Overview
The vacuum distillation column is used to distill the residual oil from the atmospheric distillation column. The distillation must be performed at absolute pressures as low as 2 to 15 kPa so as to limit the operating temperature to less than 370 to 380°C and to avoid hydrocarbons cracking processes. The presence of oxygen in the process can be caused by suction and can lead to explosion. Thereby there are rules to control the O2 level in vacuum columns. At level 2 to 5 % O2 the alarm and purging of vapor line by inert gas has to be switched on. That is why high-speed response and high reliability are required for O2 measurements.
Advantage
- vs Conventional Paramagnetic O2 Analyzer
Conventional Paramagnetic O2 analyzer cannot be used in-line measurement.
The TDLS8000 is capable of directly measuring the O2 concentrations in the vapor line, instead of conventional paramagnetic oxygen analyzers that perform measurements through a sampling system. When using traditional analyzer systems, since the application is for a process working under depression (vacuum), a pump is required. The deeper vacuum the more difficult it is to provide the proper pump. Sometimes it results in seal failure and air leakage and failure measurement results. - vs Other TDL Analyzers
The shape of O2 absorption spectrum become very sharp under this vacuum condition, which is difficult for other TDL analyzers to measure O2 concentration accurately.
But only TDLS8000 can measure O2 concentration accurately under such vacuum condition by True Peak integration (area) method. For the pressure variation test data, see next page.
Solution Details
Measurement System
- TDLS8000-☐☐-X1-☐☐-A1-☐-N/Z
/Z: Very low pressure
- IF8000-☐☐-☐☐-☐☐-12-N
Note: It is needed the suitable pressure class of the used flanges.
Measuring points of vacuum distillation column
Pressure Variation Test Data
This graph shows O2 measurement on 21%, 4%, 0.8% level under condition which gas pressure change from 1 BarA to 0.2 BarA by TDLS, and shows the measurement done stably and correctly without influence of pressure change.
O2 absorption spectra shape is big changed by pressure change, but the spectrum peak area change to pressure proportionally, so TDLS can compensate pressure influence correctly.
Measurement Value of O2 Concentration under Pressure Change 1 BarA to 0.2 BarA
行业
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化工
化工厂依靠连续和批量的生产过程，每个生产过程对控制系统都有不同的要求。连续的过程需要一个强大而稳定的控制系统，该系统不能因为自身失效而导致生产线关闭；批量过程的重点在于拥有一个可以灵活调整地公式和程序的控制系统。两种系统都需要在产品质量记录中进行管理，并且能够执行非常规操作。横河电机凭借广泛的产品组合、经验丰富的系统工程师、遍及全球的销售和服务网络，为每个工厂流程提供解决方案。
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油气下游
近年来，油气下游产业面临着越来越多的挑战。这些挑战包括待加工原料的特性变化、工艺设施及设备的老化、能源成本的上升、缺乏能够使炼油厂安全有效运行的熟练技术工人，以及市场和客户的需求不断变化。
多年来，横河与许多下游公司合作，致力于提供应对这些挑战和问题的工业解决方案。横河的VigilantPlant解决方案帮助工厂投资者尽可能实现最大的盈利能力和工厂内可持续的安全。
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石化
石化公司的需求极为多样繁杂。为了在当今竞争激烈的市场中脱颖而出，生产企业必须努力提高质量和生产力。横河电机在石化领域长期耕耘具有广泛的经验，我们可以为客户的需求提供量身定制的解决方案。
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精炼
在不断变化的市场中，炼油厂不仅是原油加工单位，而且是利润中心。同时，人们强烈意识到炼油厂设施安全性的重要。为了实现盈利、效率及环境保护的长期目标，需要包括计划、调度、管理和控制的总体生产解决方案。凭借在自动化领域多年积累的专业知识，横河可以为您提供经济实惠的完善的整体解决方案，改善操作并使世界更清洁。
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横河电机的新TDLS™8000功能强大，将诸多先进工业特性集成于一台耐用设备中。其平台设计适用于现场测量，无需进行样品抽取和样品处理。
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氧气浓度计
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