Set GGA Siemens
Область применения
This set is used in power generation applications.
Turbo generators in power plants are cooled with gas in order to increase their efficiency. In spite of the strict safety requirements hydrogen is used as a cooling gas. This offers huge advantages over air. These include considerably better cooling properties, lower friction loss on rotating parts, and a higher electrical breakdown strength. These features enable hydrogen to satisfy the requirements for the turbo generator to reach an optimum level of efficiency.
However, mixtures of hydrogen and air with a hydrogen content of anything from 4 to 77 % are explosive. For safety reasons, it is imperative that this is prevented during operation filling and emptying of the turbo generators. International standards (EN 60034-3 and IEC 842) state that redundant safety monitoring with two independent operating systems must be used for this.
In addition, contamination of the hydrogen cooling gas reduces the efficiency of the turbo generator, as it leads to considerably higher friction loss. For a 970 MW generator, a difference of 4% is equivalent to a 0.8 MW difference in power. There are also good reasons related to cost-effectiveness why the cooling gas should be continuously monitored for contamination.
The Set GGA is a complete solution for monitoring hydrogen-cooled turbo generators, with the dual benefit of being simple to handle and having low initial investment costs.
Обзор
The standardized Set GGA (Generator Gas Analyzer) has been specially designed for monitoring hydrogen-cooled turbo generators.
Дизайн
The Set GGA is available in the following versions:
- Generator Gas Analyzer (GGA)
- GGA with test gas skid
- GGA with test gas skid and installation frame
Analyzers
The GGA contains two CALOMAT 6E analyzers (19" rack unit versions). From the gas sampling system right through to the gas outlet, these are completely separate from one another, thereby ensuring full redundancy.
The CALOMAT 6E is a continuous gas analyzer for determining H2 and He in binary or quasi-binary gas mixtures.
To measure the hydrogen and inert gases continuously, the exact thermal conductivity of the sample gas mixture is measured and the concentration calculated from this. Only binary gas mixtures can be directly measured.
The CALOMAT 6E is used to measure 0 to 100 % CO2/Ar in air, 0 to 100 % H2 in CO2/Ar or 80 to 100 % H2 in air, in the context of monitoring hydrogen-cooled turbo generators, on account of its high measuring range dynamics.
The units are approved for use in ATEX Zone 2. Gas mixtures may also be fed in according to the definition of Zone 1. In terms of tightness and compressive strength, the measuring cell and entire physical structure of the gas path, from inlet to outlet, are certified up to 55 000 hPa . This is much higher than the pressure that arises when oxyhydrogen gas is ignited.
A flame arrestor at the sample gas inlet provides additional safety.
The integrated LCD display shows the measured values, status bar and measuring ranges simultaneously.
The T90 time is less than 5 s. This means that the delay between the measurement and displaying the result is very short.
Tests carried out under harsh field conditions have indicated that the 3-week drift of the measurement results is less than 0.1 %. Combined with a repeatability value of 0.1 %, this ensures that the measurement results gathered will be both accurate and precise.
Analyzer cabinet
Another feature of the GGA is a protective cabinet for the analyzers. This provides a compact location where the system can be easily installed, and offers protection against dust and water. The system is approved in accordance with IP54 degree of protection.
The cabinet measures 616 x 615 x 600 mm (H x D x W) and is made from painted sheet steel.
A key advantage of this type of construction is that it eliminates the need for a restricted breathing enclosure, allowing maintenance to be carried out without any difficulty. If a restricted breathing enclosure is required, it must be ensured that the system is operated in an airtight room. Restoring the restricted breathing enclosure once maintenance procedures have been performed is a costly and time-consuming process.
To keep operating and maintenance costs low, the GGA set supports natural cabinet ventilation and a filter element provides protection against particles of dirt. Purging with instrument air is not necessary.
Test gas skid
The analyzers and analyzer cabinet are supplied as part of the basic configuration of the set. As an option, however, it is also possible to obtain a suitable test gas skid on a mounting plate.
The test gas skid is responsible for preparing the extracted sample ready for analysis. This ensures that the sample, calibration and inert gases are fed into the analyzers at the right pressure and flow rate, and without having been mixed with other gases.
The skid is fully equipped with a flame arrestor, stopcock ball valve, stainless steel overflow regulator, single-stage pressure reducer, stainless steel 5-way transfer ball valve, all-metal flow meter for air, 1-channel isolating switch amplifier and installation material. The flowmeters are designed to transmit a limit monitoring signal. The connection is made on-site.
The test gas skid guarantees that all the requirements in terms of safety, quality and simplicity are satisfied when connecting sample, calibration and inert gases.
Installation frame
The installation frame is a supplementary feature of the set. It enables free-standing installation of the analyzer cabinet and test gas skid.
The installation frame is supplied in a fully assembled state (including feet). Its overall height is 2 000 mm.
Функции
There are three distinct processes in monitoring hydrogen-cooled turbo generators: normal operation, filling and emptying. The measuring task entails preventing a gas mixture of hydrogen and air outside the specified limits, or detecting the risk of this happening in good time, as well as monitoring the hydrogen purity.
During normal operation, the purity of the generator cooling gas is monitored. If the purity falls below a specific limit (e.g. < 95 % H2), a message is output. The monitored range is 80 to 100 % H2 in air.
Filling the generator is a two-stage procedure: first, the air in the generator is replaced by inert gas (argon or CO2), and then this is replaced by hydrogen. During this, the concentration trends of the gases are measured and the replacement processes monitored. To prevent explosive mixtures from being formed, it is necessary to monitor the measuring range of 0 to 100 % inert gas in air in the first step and 0 to 100 % H2 in inert gas in the second step.
The procedure is performed in reverse when emptying the generator: The hydrogen is first replaced with inert gas and the generator is then filled with air. The measuring tasks remain unchanged in this case. Here it is necessary to monitor the measuring ranges of 0 to 100 % H2 in inert gas first, and then 0 to 100 % inert gas in air.
Чертеж
Set GGA, dimensions in mm, figure corresponds to 7MB1950-0GA00-1EB0
Особенности
Standardized complete system
- Simple and fast to configure
- Field-proven, harmonized and reliable set
- Low purchase price and economic operation
- Suitable for optimizing the efficiency of H2-cooled turbo generators
Field-proven, reliable technologies
- High-precision and reliable purity monitoring of hydrogen
- Microchip-based thermal conductivity measurement
- Redundant measuring system
- SIL 1 certificate for the analysis hardware
Simple operation
- Intuitive menu prompting
- Configuration on large displays with plaintext
- Use of CO2 and AR as inert gas possible
Технические данные
Climatic conditions | |
Ambient temperature | 5 ... 50 °C |
Relative humidity | 70 %, non-condensing |
Corrosive atmosphere | No |
Gas inlet conditions | |
| |
| 800 ... 1 100 hPa (absolute) |
| 30 ... 90 l/h (0.5 … 1.5 l/min) |
| |
| 55 000 hPa (absolute) |
| 30 … 90 l/h (0.5 … 1.5 l/min) |
Power supply | |
| 200 ... 240 V AC, 47 ... 63 Hz |
| 100 ... 120 V AC, 47 ... 63 Hz |
| 24 V DC for switch amplifiers |
Type of connections | |
Pipe material | Stainless steel |
Connections/components |
|
Cabling | |
Electrical design | According to IEC |
Type of cables | Non-armored cables |
Cable ID | No single core labeling |
Installation | |
Site | Interior |
Ex-zone analyzer | ATEX II, 3G |
System design | |
Version | Cabinet |
Degree of protection | IP54 |
Automatic calibration | No |
Signal outputs | 4 ... 20 mA/isolated contact |
With sample gas return flow | On request |
Measuring response (relating to sample gas pressure 1 013 hPa absolute, 0.5 l/min sample gas flow and 25 °C ambient temperature) | |
Output signal fluctuation | < ± 0.75% of the smallest possible measuring range according to rating plate, with electronic damping constant of 1 s (σ = 0.25%) |
Zero point drift | < 1%/week of the smallest possible span according to rating plate |
Measured-value drift | < 0.5%/of the smallest possible span according to rating plate |
Repeatability | < 1% of the current measuring range |
Detection limit | 1 % of the current measuring range |
Linearity error | < ± 1 % of the current measuring range |
Influencing variable (relating to sample gas pressure 1 013 hPa absolute, 0.5 l/min sample gas flow and 25 °C ambient temperature) | |
Ambient temperature | < 1%/10 K referred to smallest possible span according to label |
Accompanying gases | Deviation from zero point |
Sample gas flow | < 0.1% of the smallest possible span according to rating plate with a change in flow of 0.1 l/h within the permissible flow range |
Sample gas pressure | < 1 % of the current measuring range with a pressure change of 100 hPa |
Auxiliary power | < 0.1 % of the current measuring range with rated voltage ± 10 % |
Generator gas analyzer
Analysis | Measuring point designation | Generator gas analyzer | |||||
|---|---|---|---|---|---|---|---|
Concentration | Unit | Measured component | Measuring range | ||||
Component | Min. | Typical | Max. | Small | Large | ||
Ar/CO2 in air | 0 | 100 | vol. % | Yes | 0 | 100 | |
H2 in Ar/CO2 | 0 | 100 | vol. % | Yes | 0 | 100 | |
H2 in air | 80 | 100 | vol. % | Yes | 80 | 100 | |
Sample temperature | 50 | °C | |||||
Dust content | 0 | mg/m3 | |||||
H2O dew point | -50 | °C | |||||
Aggregate state, sample1) | Gaseous | ||||||
1) Standard state at 20 °C, 101.3 kPa
Ответ от производителя может занять до 5 дней и более.
