SITRANS CV производства Siemens

• Analysis of natural gas in power plants:
  • For quality control
  • For turbine optimization
  • Pipeline monitoring
• Analysis of natural gas when opening up sea beds (off-shore plants).
• Analysis of bio-natural gas in preprocessing plants
• Analysis of natural gas in liquefaction and regasification plants (LNG Regasification and Storage)
• Determination of calorific value in natural gas for power plants, in gas transfer stations, or during turbine optimization
• Analysis of calorific value in natural gas preparation plants

Flexible installation: The rugged and compact design enables installation in even extreme areas of application, such as offshore exploration, or directly at the pipeline. The SITRANS CV has the certification required (such as explosion protection or splashwater protection) to meet the requirements of these applications.

Like the MicroSAM, the SITRANS CV consists of a basic unit and an analysis module, which, if necessary, can be replaced in as short a time as possible. Combined with low power and gas consumption, this keeps operating costs down.

Notable features of the CV Control software, which has been specially developed for calibration-related applications, includes its ease of operation and transparency.

The automatic method optimization integrated in the software increases the repeatability of the calorific value measurement and reduces the cost of ownership.

The serial RS 485/RS 232 and Ethernet interfaces enable communication with both the control system and a flow computer.

Like the MicroSAM, the unit’s high analytical capability can be attributed to narrow-bore capillary columns, live injection, live switching and in-line detection.

Enclosure

• EEx-d version standard (acc. to ATEX II 2G)
• Heating adjustable from 60 to 165 °C (isothermal)
• Decentralized installation close to sampling point

Analytical modules

The compact analytical modules contain all the functional components of a chromatograph. The SITRANS CV operates with:

• Live injection
• Valveless live switching on microchip basis
• Standardized analytical modules
• Multidetection through use of up to 8 micro thermal conductivity detectors in smallest possible areas (e.g. on all column/purging outputs and injection)

Live injection

The SITRANS CV has a two-stage injection system. Using a micro injection valve, a defined quantity of sample is first brought up to the carrier gas pressure. This eliminates the pressure-dependent error in the dosing quantity present with conventional systems. In the second stage, the sample is transferred to the column by a valveless micro injection system (live dosing). The result is an "active" injection.

The injection volume can be varied time-controlled, and exactly matched to the column requirements.

Valveless live column switching

Because of the high dead volume of conventional valves, only the valveless version can be considered for a miniaturized system. In this case, the generation of differences in flow using several electronic pressure regulators at appropriate positions of the column setup causes a change in the flow directions. (The system operates according to the Wheatstone principle, but pneumatically.) The functions "Cut" and "Backflushing" can then be implemented free of dead volume.

The column system

The column system consists of three capillary columns connected in sequence. Micro TCDs or micro live circuits are installed in sequence ("inline") upstream and downstream of the individual columns. Three electronic pressure regulators supply the columns with carrier gas and carry out the switching functions (injection, backflushing and cut).

By using narrow-bore capillary columns, the separation at high resolution is carried out within a much shorter time, approx. factor 2 to 3 compared to standard capillary columns.

Electronic pressure regulators

A high pressure stability together with rapid changing rates in the hPa range are required for precise and fast switching. This is achieved in the electronic pressure regulators by means of a piezo actuator.

Detector

The micro TCDs (silicon wafer technology) work on the principle of continuous measurement of the different thermal conductivities of the carrier gas and the components to be measured.

The measurement can be carried out without falsification by avoiding catalytic effects on the heating wires and maintaining a constant flow velocity. This permits consistent in-line detection, i.e. without qualitative or quantitative losses of substances.

Modules

The standardized application modules generally feature live injection and live switching functions, detectors and three separating columns.

Application

The SITRANS CV is a storage product. Precalibration is carried out at the factory, using helium and argon (as the carrier gas) and a calibration gas. The measured components and switching functions (live injection, backflushing, cut) are saved in the GC. The calibration process itself should be performed during commissioning on-site.

Measurements can be made within the following working ranges:

Measured components and performance parameters for Pos. 8_0 (master setup, standard calorific value analysis in accordance with ISO 6976-1995)

¹⁾ Any oxygen or carbon monoxide present in the sample will be detected along with the nitrogen and, therefore, taken into account when the nitrogen concentration is determined.

²⁾ Hexane+ = group_{(iso/n-hexane to iso/n-nonane)}

³⁾ Heptane+ = group_{(iso/n-hexane)} and group_{(iso/n-heptane to iso/n-nonane)}

⁴⁾ Nonane+ = group_{(iso/n-hexane)}, group_{(iso/n-heptane)}, group_{(iso/n-octane)}, group_{(iso/n-nonane)}

Measuring range of the additional measured component oxygen of the extended calorific value analysis (see Order No. 7KQ3105-1)

The remark in footnote 1 about the detection of oxygen and nitrogen is not valid in the case of an extended calorific value analysis. In this case, all components from the Table "Measured components and performance parameters for Pos. 8_0 (master setup, standard calorific value analysis in accordance with ISO 6976-1995)" plus oxygen are detected and quantified.

Analyses within the checked working range as well as the quality parameters resulting from these (upper and lower calorific values, density, relative density and Wobbe index) correspond to the requirements listed below.

Measurements within the scope of the possible working ranges (Table "Measured components and performance parameters for Pos. 8_0 (Master setup, standard analysis of calorific value in accordance with ISO 6976-1995)", right column, and Table "Measuring range of the additional measured component oxygen of the extended analysis of calorific value (see Order No. 7KQ3105-1)") are possible. However, checking of the repeatability and correctness has not been carried out by the official German body "Physikalisch technischer Bundesanstalt (PTB)".

The repeatability of the measured components complies with ISO 6974-5 (2001) – Annex B

The repeatability of the calorific value and standard density achieve a relative standard deviation of < 0.015%.

The calibration gas is an extremely important factor for consideration in terms of the MPE (maximum permissible error), and has a significant effect on the accuracy of the overall measuring system. For this reason, SITRANS CV - based on a comparative measuring procedure - can never be more accurate than the calibration gas used. Other parameters besides the accuracy data on the calibration gas certificate are important for the accuracy of a system. Examples of these include the optimum gas composition, the ambient temperatures of the calibration gas cylinders during transportation and operation, potential condensation of, for instance, higher hydrocarbons in a calibration gas cylinder, and the functionality of the sample preparation system.

Under optimum conditions, the SITRANS CV achieves an MPE of < 0,1 % for the calorific value and standard density.

SITRANS CV is designed for measuring different types of natural gas. The table below lists the typical specifications of natural gases (measured and residual components):

Composition of Dutch, Russian and Algerian natural gas, as well as LNG

SITRANS CV with SIMATIC Extension Unit

SITRANS CV, dimensions in mm

Notes on 7KQ3105-..

Support bracket

For easy mounting, incl. support for 8 gas connections consisting of:

• Mounting part: Dimensions 380 x 110 mm (W x H)
• Bracket for gas connection: Dimensions 146 x 110 mm (D x H), bracket on right side, mounted at right angle

Sample flow switchover

The chromatograph enables automatic selection and switchover of 3 sample flows and 1 calibration flow. The DO signal from the gas chromatograph requires an external relay for the solenoid valve. The sample preparation system can be ordered separately.

Ambient temperatures

Particularly in warmer zones, weather protection is necessary to protect the SITRANS CV against direct solar radiation. The chromatograph is designed as standard for temperatures from -20 to +55 °C. A version in a thermostatically-controlled casing is also available as an option for temperatures outside these limits.

Communication

SITRANS CV has two serial interfaces. One RS 485 / RS 232 connection for Modbus communication (RTU / ASCII). Modbus mapping can be flexibly used (see manual for more information). SITRANS CV is operated via the second interface Ethernet (TCP/IP).

Other serial and analog (4 to 20 mA) interfaces are available as an option; these can be ordered as a supplementary solution package.

Documentation

The documentation includes a SITRANS CV Manual and CVControl Operating Manual in English and German. The documents can be found on the enclosed CD.

CVControl operating software

The operating software (language: English or Russian) is included in the scope of supply. Windows XP or Windows 7 must be installed on the computer in order to install this software.

Application

A general system check is made of the basic unit and the integrated application module. The module and basic unit are described in the manual. In addition to the original master setup as the standard method, other country or user-specific method setups are available. The performance record ex works contains the analysis check, including a repeatability record (4h test).

The standard method (original master setup) is installed in the chromatograph, and four CD-ROMs are supplied with the following:

• 2 CDs SITRANS CV Software (including manuals and CVControl Operating Manual)
• 1 CD Country-specific partial setups
• 1 CD Parameter backup for SITRANS CV (including documentation for the individual module with TCD bridge voltages and EPC pressures, as well as module-specific hardware setups)

Order No. Pos. 8_0: Applications – Standard calorific value analysis - Certified in conjunction with GWK-CHRPA-CV-CER-1

This application comprises the standard calorific value analysis. The chromatograph's measurement method is set at the factory, using a synthetic natural gas mixture. The performance parameters specified in Table 3 and the criteria explained in the subsequent text apply to the individual components in Table 1 and their physical variables.

Calculation of the calorimetric variables is based on GOST, AGA 8 and ISO 6976-95 with the last-named as the default. The reference states for the combustion and for the gas volume that must be specified for calculation purposes are preset to the default state (T_b= 25 °C, T_n = 0 °C) and can be easily changed to other reference states during commissioning using the operating software (T_b = operating temperature, T_n = standard temperature).

The CVControl software provides the energy units BTU/ft³, KWh/m³ and MJ/m³.

Order No. Pos. 8_1: Applications – extended calorific value analysis with oxygen

This position includes the extended calorific value analysis of the components and possible working ranges from Table 1. Oxygen is measured in addition to the listed components (see Table 2).

A carrier gas dry filter (Order No. filter set A5E00400116) on the mounting bracket of the SITRANS CV or enclosed separately is used as standard for this measurement.

The remarks concerning oxygen and CO in footnote 1 of Table 1 are no longer applicable to this position. The information concerning calculation and performance parameters are identical to Pos. 8_0.

Important:

For correct operation of SITRANS CV in accordance with Pos. 8_0 and 8_1, all measured components must be present in the calibration gas. The calibration gases listed in Table "Recommended calibration gases for Pos. 8_0 and 8_1" are recommended:

Recommended calibration gases for Pos. 8_0 and 8_1

A summary of the various country-specific setups, i.e. standard settings including measured components and calibration gases, can be found on the parameter backup CD in the "Readme.pdf" document.

A01 – SITRANS CV for calorific value analysis Pos. 8_0 and Pos. 8_1 - Russian configuration

This position includes the possibility for ordering SITRANS CV with a Russian Ex certificate.

IMPORTANT: This Russian version results in a change in the nomenclature from SITRANS CV to MicroSAM.

B02- SITRANS CV with extended measuring range in combination with Pos. 8_0

This position permits separate measurement of the group isomers of the higher hydrocarbons C6 to C7(+) and C6 to C9 (+). In accordance with the designation C7(+) and C9 (+), a detailed measurement is carried out up to and including n-C9.

Important:

Testing and certification of the SITRANS CV is carried out using the standard calorific value analysis in accordance with Pos. 8_0. If Pos. D02 or D03 has been selected, this does not include repetition of the proof of repeatability (4 h test) of the unit during the factory acceptance.

The following calibration gases are essential for operation of the SITRANS CV including these extended measuring ranges:

Components and concentrations of the calibration gases for the extended measuring ranges

Further information regarding startup of SITRANS CV including C7(+) and C9(+) measurement can be found in the manual and on the enclosed document CD (country-specific setup "Readme.pdf" file)

D01 - Acceptance and customer information - Factory acceptance, visual check, 1 day

The scope of supply is checked and the documentation and operation of the unit explained as part of the factory acceptance process. The factory acceptance does not include repetition of the proof of repeatability (4 h test) of the unit.

D02 - Acceptance and customer information - Factory acceptance with performance record, 1 day

The scope of the tests to be carried out is described in the Table "Scope of tests during factory acceptance". When ordering D02, please supplement the desired option from E0x.

Scope of test during factory acceptance

SITRANS CV is a standard product. Only in this manner is it possible to guarantee short delivery times and attractive prices. All performance records required retrospectively require higher overhead. However, will will be happy to come to an agreement regarding implementation.

D03 - Acceptance and customer information - Factory acceptance, each additional day

Only in conjunction with D01 or D02

E0x - Repeatability test

Proof of repeatability over a period of 4 h is included as standard. Longer repeatability records for the unit can be ordered by means of the supplementary item E0x.

E01 to E03 - Repeatability test, 8 h – 24 h – 48 h

Only in conjunction with D02

Linearity tests can be carried out in the factory on request. The standard calibration gases required for this (Table "Recommended calibration gases for linearity test during acceptance") are provided free of charge. If the customer specifies other calibration gases with different compositions or higher uncertainty requirements, they must provide these gases for acceptance purposes. As an option, Siemens can procure these special calibration gases (subject to a charge).

On request, proof of the complete functionality of the SITRANS CV is possible within the certified temperature and ambient conditions.

Recommended calibration gases for linearity test during acceptance

The calibration gases have the following uncertainties:

Notes on 7KQ2160-..

Analog and serial data transmission

SITRANS CV does not provide internal analog outputs. These properties can be provided by the SIMATIC Extension Unit. This uses the Modbus output of the chromatograph in order to generate up to 8 active analog outputs (standard, more analog outputs on request).

Modbus multiplexers are available in addition, and allow up to 2 Modbus masters to be connected to the SITRANS CV. The distance from the SITRANS CV should not be more than 1 200 m. In the case of an installation without enclosure (without explosion protection), we deliver the components for generation of analog outputs mounted on a rail, otherwise in the Ex d enclosure.

Pos. 08_ 0 - 5 – Analog values via external unit

This position includes:

• Mounting rail
• Power supply
• SIMATIC S 7-300 and SIMATIC S7, Micro Memory Card 3.3 V NFLASH, 64 KB
• Analog output module with terminating connector
• Protocol converter

Pos. 09_ A – C: Modbus multiplexer

(only applicable together with 0-4)

The Modbus signal can be routed using the Modbus multiplexer and connected to two Modbus masters. B specifies supply of the components without CE certificate.

Pos. 10_ A - B: Enclosure

This position includes the option for installation of the SIMATIC extension unit in the hazardous area (Zone 1 and Zone 2). A protective casing Ex d with standard cable glands including the modules required for the analog outputs and the Modbus multiplexer (if applicable) are provided for this purpose.