Safety functions for explosive zones

Halvorsen Mobile Steam Unit Zone 2 is designed for customers who require steam for shorter or longer periods of time.

The system is flexible and can meet a full range of customer requirements, for both industrial land-based projects and offshore installations.

The safety functions are fully integrated so that the unit can be placed in areas where there is a risk of explosive gases (Z-015). The entire unit is assembled in a container approved for offshore transportation (DnV 2.7.1).

Regulations

The boiler is designed in accordance with the following specifications and regulations:

• Norwegian Standard Z-015N Temporary Equipment
• DnV 2.7.1 Certification Notes Offshore Containers
• NS-EN 12953-1 Shell boilers

The Halvorsen Mobile Steam Unit Zone 2 is based on a system whereby a traditional fuel gas boiler together with extra equipment is fitted in a 20-foot container offshore.

In order to meet the requirement for utilisation in areas exposed to gas, the container is equipped with relief ventilation where air is provided from a safe area. The necessary gas and overpressure detectors which automatically shut down the unit are also installed, along with manual and automatic fire extinguishing equipment.

Boiler

The boiler installed in the container is a traditional gas fuel boiler with a large water volume and flash gas surface. This provides good steam quality and stable steam pressure, even with heavy loads. Due to the large volumes of water, a high volume of energy is stored in the boiler, which can provide continuous capacity for short periods of time without any significant loss in pressure.

Another advantage provided by this design is that when the boiler is operating as standby, it provides an immediate supply of steam at specific pressure and temperature:

Technical figures:

• Boiler efficiency (continuous operation) 1,710 kW
• Steam production 2,500 kg/hr
• Steam pressure 10 barg
• Diesel consumption 162 kg/hr
• Voltage and frequency 3 x 230 V – 3 x 400 V, 50-60 Hz
• Electric consumption 6 kW

Burning and combustion system

• Type of burner: 3-mouth combustion air burner, with diesel pump, suction from day tank.
• Diesel consumption: 162 l / kg
• Voltage: 3 x 230V - 3 x 400V 50-60Hz
• Electric consumption 3 kW

A drip drawer has been installed under the burner to catch any oil spills.

Diesel day tank

Volume: 800 litres

Feed water system

The steam unit is supplied with a complete feed water system comprising:

• Atmospheric feed water tank
• Volume: 760 litres
• The tank level is regulated by a controlled water level
• 2 x Feed water pumps, type Grundfoss CR3-25
• Capacity 3m3 / hr with 12 bar
• Voltage 3 x 230V - 3 x 400V, 50-60Hz
• Electric consumption 2.2 kW
• Chemical dosage unit
• Softens the filter

Control panel for the steam unit

A control panel is fitted to the wall of the steam unit.

Panel functions:

• Regulation of water level in the boiler by starting/stopping the feed pump
• By increasing the temperature in the shell boiler, the volume will be reduced

- Alarm functions:
- High water level, boiler
- Low water level, boiler
- High pressure, boiler
- High temperature, exhaust
- Low water level, feed tank
- Low oil level, feed tank
- After shut-down functions:
- Lowest water level, boiler
- Highest pressure, boiler
- Highest temperature, exhaust
- Discharger for:
- Feed pumps
- Burner
- Ventilation fan