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12.01.2011  | 

Keywords: [TOC monitoring] [boilers] [water contanimants] [analyzers] [catalysts] [sulfur recovery] [gas to chemicals] [components] [ceramic-matrix composites]

Optimize low TOC range monitoring

How can a monitoring system, with a very short response time and a reliable and fast validation/calibration method, enable reuse of pure and hot water by monitoring steam processes and boiler feed water for contaminations by organics, reduce operation cost and energy loss? ODS Sampling & Analytical Systems in the Netherlands is experienced in installing online total organic carbon (TOC) process-monitoring systems and advises operators how to optimize their processes to obtain fast and accurate TOC measurements. In low TOC ranges, measuring and validating/calibrating can be problematic. Today, boilers operate at very high pressure (100 bar–120 bar and higher). According to numerous guidelines, only water contamination at concentrations lower than 0.1 mg/l C to 0.2 mg/l C are allowed. Boilers operating at lower pressure (60 bar–80 bar) allow water contamination at a slightly higher level of about 0.5 mg/l C. The TOC analyzer must be capable of monitoring this potential low-level TOC contamination reliably.

To reduce operating costs and prevent any installation damages caused by too high TOC concentrations, the total monitoring TOC analyzer system’s response time should be as short as possible. There is a risk that contaminated return condensate is pumped back into the boiler drum before being detected. For monitoring possible TOC contaminations in steam processes and boiler feed-water applications, fast response times, as well as simple and fast validation of the results, are required. Thus, the total analyzing system—from the point of sample taking up to the analyzer—has to be optimized.

Reducing response time.

By optimizing the dimension, size and type of materials of all wetted parts, such effects mentioned above, can be minimized. Sufficient sample velocity in sample lines of at least 0.3 m/s, preferably 1 m/s, is important. Small sample-line diameters decrease the total wetted surface. In general, ODS recommends an OD of 6-mm or ¼-in. lines with an ID of about 4 mm. However, this small-diameter sample line can handle very high pressure without any risk. Seamless sample pipes in stainless-steel quality 316 should be used. Every meter of sample line is one meter too much.

TOC analyzers use the thermal oxidation method at 1,200°C combined with multiloop injection by LAR Process Analysers AG. These analyzers have low ranges with accurate and stable TOC or total carbon (TC) analyses. The lowest detectable limit is about 2 µg/l C.

No pump is used in the sample stream. Peristaltic pumps use flexible tubes that cause absorption effects.

TOC or TC?

A boiler needs pure water. This water is produced via the makeup-water installation. All impurities are removed as far as possible. Acid attacks the metal boiler wall, process pipes and heat exchangers, resulting in pit corrosion. A TOC analyzer analyzes only organic carbons. A TC analyzer responds to organic hydrocarbons, as well as inorganic carbon (carbonates).

Optimal sample conditioning.

Samples are extracted from a sample point in a big process pipe. A sample point at the lowest point, especially in horizontal pipes, will act as a buffer collecting fine particles like metal oxides, etc. Small particles need to be filtered out.

There are several methods to reduce the sample temperature. Although the analyzers can handle a temperature of about 90°C, it is safer to reduce the temperature to a lower value such as between 30°C and 40°C. ODS uses an air-cooled heat exchanger with a very-low internal volume. In fact, it transports the sample continuously, at a flow of about 1 liter/min., as close as possible to the analyzer.

Fast validation and calibration.

LAR has improved and simplified calibration and validation for TOC analyzers based on the high-temperature method at 1,200°C. With any other methods it is necessary to provide watery standards for calibration and validation—requiring high expenditure and long fall-out times. Its patented method uses a specified test gas. With the QuickTOCcondensate, the sample volume is defined by an injection loop and injected into the reactor via the carrier gas. The high temperature of 1,200°C enables use of a defined concentration of CO2 or methane. Such a certified validation gas is stable and usable for a long period of time. LAR’s QuickTOC analyzers are especially customized to meet pure-water application.


  Fig. 1. Sample conditioning panel. 

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Catalytic direct oxidation for sulfur recovery

GTC Technology has a worldwide technology licensing agreement with TDA Research for sulfur recovery from hydrogen sulfide (H2S) through catalytic direct oxidation. The agreement expands GTC’s platform of acid-gas removal technology, including GT-CO2, a process technology for CO2 removal; GT-SSR, a Claus process for sulfur recovery with over 60 licenses; and Crystasulf, a liquid-phase Claus process technology for sulfur recovery. GTC expects the catalytic direct oxygen technology to apply to a range of 0.2 tpd to 300 tpd.

“Direct oxidation catalyst technology provides a significant advance in sulfur recovery,” said Dr. Matt Thundyil, sulfur business leader for GTC Technology US, LLC. “We will be able to deliver greater value to our clients, and continue our exceptional track record in commercializing innovative technologies for the energy industry.”

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hte engaged in research for Total

The high-throughput experimentation (hte) company is collaborating with Total Gas and Power in a research project for optimizing a large-scale gas-to-chemical (GTC) process. The collaboration’s main goal was to compare the performance of newly developed catalyst formulations with a GTC catalyst already being used by Total on a large scale. The optimum process parameters for deployment on an industrial scale were successfully determined within the scope of the cooperation.

High throughput technologies and hte’s expertise, both in heterogeneous catalysis and process optimization, reportedly made a considerable contribution to securing the research project’s success. Based on a statistical Design of Experiments (DoE), hte performed numerous experimental investigations within a short period of time. The comprehensive and precise data provided from this was then used to create a macrokinetic reaction model for a GTC catalyst used by Total on an industrial scale.

With its development and optimization of GTC processes, Total is striving to establish natural gas, biomass and coal as economically viable alternatives to crude oil and thereby tap new petrochemical added value chains. Total and hte are building on their successful cooperation in a follow-up project.

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Material virtually eliminates sealless pump failure

CeraComp material, an innovative ceramic-matrix composite, reportedly delivers dramatic benefits over traditional silicon-carbide materials with superior fracture and wear resistance. It expands sealless pump reliability by virtually eliminating the risk of catastrophic failure. Green, Tweed’s CeraComp solutions are said to deliver exceptional toughness and fracture resistance for improved MTBF and reduced maintenance costs. The material is capable of withstanding temperatures over 1,100°F (600°C). This exceeds the upper limit of polymeric and elastomeric composites, and maintains outstanding chemical resistance. In addition, CeraComp’s excellent toughness enables better structural integrity and impact resistance, eliminating the risk of catastrophic failure.

The material’s design flexibility makes it suitable for a wide range of petrochemical and power applications. Green, Tweed’s Advanced Technology and Engineering teams have developed two solutions for canned-motor and magnetic-driven pumps. These bearings and bushings are suitable for both rotary and static usage.


  Fig. 2.  CeraComp components. 

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Precise and reliable oil-analysis method

A new method for elemental analysis of oil samples in the petrochemical industry uses the Thermo Scientific ARL PERFORM’X X-ray fluorescence (XRF) spectrometer to create a flexible and high-performance solution that is reportedly capable of reaching detection limits of below 0.5 ppm. Using wavelength dispersive XRF (WDXRF), the method is said to offer excellent repeatability and resolution, particularly for light elements such as sodium and calcium. In addition, it allows oils to be measured directly without dilution, reducing sample preparation time, and increasing speed and throughput of analyses.

The ARL PERFORM’X system provides dual sample loading and is able to process more than 60 samples per hour, offering rapid and precise analysis of up to 84 elements including sulfur, nickel, vanadium and lead. The instrument’s innovative sample-recognition capability ensures safe and straightforward loading of liquids. Featuring the latest version of the state-of-the-art Thermo Scientific OXSAS software, the instrument can operate with Microsoft Windows 7 to ensure simple and trouble-free analyses.



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Scanning unit offers inside view of components

The microscopy department at Freudenberg Forschungsdienste (Freudenberg Research Services) has started using a computed tomography (CT) scanning unit. Developed on the basis of X-ray technology, CT provides X-ray images from various angles, creating computer-assisted 3D images. These 3D images provide a perfect, faithful insight into the inside of the object being examined.

The specified object can be turned and rotated onscreen as required and viewed from all conceivable angles. With the help of CT images, Freudenberg checks whether material samples, prototypes and initial sample components meet stipulated specifications. These images can also be used to identify component damage and analyze its causes. Experts can examine the entire component as a transparent image or can make its plastic covering disappear at the click of a mouse, revealing the integral electric printed circuit board and contacts. Distances, angles, radii, surface areas, or the volume of even the tiniest trapping of air can be exactly calculated.

Freudenberg also uses CT scanning to check the even distribution of fibers in non-wovens and to find out whether air has been trapped in cast parts. With CT scanning, Freudenberg is making giant leaps forward in terms of the industrial development of elastomer components and fracture analysis.

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