Ventilation systems used in oil and gas applications operate in some of the most challenging and corrosive environments on earth. Great demands are placed on their design and build quality because they are expected to perform with exceptionally high reliability, to protect against the inherent hazards found in these environments.
Safety critical ventilation systems provide dilution, dispersion and removal of potentially hazardous concentrations of flammable gas gaseous mixtures from hazardous areas. The HVAC plant provides pressure differential between hazardous and non-hazardous areas. In addition they provide comfortable environments for living conditions.
Tyco is able to design, specify and supply a range of ventilation products through our long established relationships with all the major offshore HVAC equipment manufacturers and specialist companies.
Tyco can advise on the most appropriate equipment to use and identify where different equipment or revised systems could improve or correct shortcomings in existing plant design.
Air Handling Units
Air handling units are an effective way of packaging all the separate HVAC components used to condition supply airflow and to control exhaust airflow. Typically a Supply Air Handler will include some or all of: intake water separation and particulate filtration, one or more Fire Dampers, a cooling coil and a heating matrix, humidifier elements, a volume control damper, a pressurisation fan (normally centrifugal type), and a shut-off damper.
Exhaust Air Handlers typically contain only dampers and a fan, as there is no need to condition waste air being exhausted to atmosphere.
Tyco uses a diverse range of manufacturers to provide new build air handlers to client rspecific requirements, we also have access to a wide range of spare parts for any air handler to keep existing units in service at low cost.
The air quality in most environments that the oil and gas industry operates in is often contaminated by various particulate matter and can be corrosive in its untreated state.
In offshore environments a weatherproof intake and moisture elimination stages are normally fitted to separate out moisture from rain or salt spray from the incoming airflow. One or more stages of filtration media are also used; usually a coarse filter for gross fouling and a fine filter to remove smaller particulate including soot.
Onshore locations may experience different contamination such as sandstorms or insects, and this can often be successfully removed by using specialist filtration media.
Certain areas also have extract filtration fitted, to the reduce build-up of contamination within duct work reducing system efficiency and creating a fire hazard. Examples of these are grease separation filters fitted to galley extract hoods, and lint filters fitted to laundry clothes dryers.
Tyco has experience across a wide range of operating environments and can advise on various ways to improve supply and extract air quality.
Ventilation fans create airflow, and are available in several different types to suit different applications. Centrifugal fans can create a high discharge pressure and are typically used as pressurisation fans in safe area ventilation systems. They are also less affected by the build-up of contaminants and are useful in dirty, laundry or galley extracts.
Axial fans are used for airflow but are less effective against a high discharge pressure. Numerous further specialist types are available, and all types can be built with a variety of materials to resist static electricity discharge, corrosion, contaminant build-up and other factors.
Tyco works with a number of ventilation fan manufacturers to ensure the correct product is available to the client.
We have access to both OEM and high-quality third party refurbishment facilities to return failed fans to service quickly where offshore repair can’t be achieved.
Dampers in their most simple form are a valve in a ventilation system, they open or close to control airflow in normal circumstances and some types are specially designed to prevent the spread of smoke, gas and fire in an emergency.
The operation of both fire and gas dampers are safety-critical and they undergo regular maintenance to ensure that in an emergency they will operate as expected. They do have a limited lifespan and some manufacturers recommend replacement at distant intervals to limit the effects of obsolescence and fatigue of non-replaceable components.
Tyco works with every major supplier of offshore HVAC dampers to ensure clients are always able to procure the correct model for their asset. All safety critical dampers are supplied with the complete range of certificates for their type, and are usually available with manufacturer’s warranties.
Cooling the supply airflow is necessary for two reasons in oil and gas environments: it reduces salt-laden moisture in the airflow to reduce corrosion to equipment within the ventilated area, and it cools the supply airflow in warm environments. This is achieved using one or more cooling coils in the airflow, with a cooling medium being passed back and forth along tubes across the airflow. Fins across the airflow increase the effective surface area for cooling. The cooling medium absorbs heat from the airflow, and removes it as waste heat. Cooling is achieved by simple seawater coils acting directly on the airflow or by using refrigerant as a cooling medium, either directly or by cooling a ‘chilled water’ circuit which then passes through the cooling coils.
Seawater coils are simplest but are also prone to corrosion, water erosion and blockage by contaminants in the seawater. Refrigerant directly cooling airflow is very effective in some applications, but also risks emitting the refrigerant into the airflow in the event of a cooling coil failure. Chilled water circuits enable a smaller refrigerant charge to be used and are also safer in the event of a coil failure.
Tyco can offer refurbishment of failed cooling coils or replacement with a like-for-like item. A number of materials and coatings are available to extend the life of the coil providing a lower through life cost, including our fit-and-forget titanium coils which will typically last beyond the lifespan of the platform, even on seawater cooling applications.
Supply airflow is heated to raise the temperature of incoming airflow to a pre-heat level, to establish a minimum comfort temperature throughout all areas served by the ventilation. Re-heaters serving individual areas can then be individually set depending on use of the room and needs of the occupant. Pre-heating reduces the load on these smaller re-heaters, and provides some warmth in case of failure of the local re-heater. Pre-heaters can be electric elements, steam or hot water coils, and in some cases waste heating medium from other equipment such as power generation is used to improve efficiency.
Tyco is able to refurbish or replace heating coils and reheater units so that clients can maintain a comfortable environment in conditioned areas, with low through-life cost.
Humidifiers and Dehumidifiers
One negative effect of conditioning supply air is that by condensing moisture out of the airflow and then warming that airflow, the relative humidity of the airflow is significantly reduced to uncomfortable levels.
Artificial humidification can be used to raise the relative humidity of supply airflow up to comfortable levels at around 50%RH, at which most of the ill-effects described above are remedied. This can take the form of steam sprays, purified cold water sprays, or trickle-evaporative humidification.
Tyco has undertaken numerous projects to repair or replace humidifiers, greatly improving the environmental condition within the served areas and improving the general wellbeing of occupants. We can supply Dehumidifiers and Dehumidification Systems, starting with air volumes 50m³/h up and going beyond 57,000 m³/h.
Ventilation ducts are used to distribute supply and extract flows to the individual areas to be served so that the airflow is spread evenly throughout various areas. This allows the air change rates and supply or extract airflows to be finely balanced to suit the requirements of each particular room, in line with industry standards. Ducting must be correctly specified and insulated to limit spread of fire, and sized to achieve roughly the correct airflow so that duct sizes are minimised where practical, without being undersized for the required airflow. Equipment such as volume control and fire dampers, ventilation outlet / intake terminals and duct re-heaters are often fitted to ducting. Access hatches should also be fitted for maintenance, inspection and cleaning.
Tyco is well experienced in duct work design, fabrication, modification and installation, and has carried out this work in numerous new build or retrofit scenarios.
Local Exhaust Ventilation
Some contaminants generated in oil and gas environments are so hazardous to human health that special systems are installed to prevent the exposure of the substance to personnel. On almost every oil and gas installation these will include laboratory fume cupboards and fabrication shop welding fume extracts as a minimum. On drilling assets there will also be numerous systems to control the release of vapours from drilling mud in shale shakers and mud pits, and of harmful dusts from mud or cement mixing hoppers.
These systems must be designed by competent persons to ensure the system completely captures the contaminant and transports it to exhaust in a safe location. The system should be designed to allow access for cleaning out any build-up of contaminant, since this will reduce the system efficiency. Tyco has a design team with the right qualifications and extensive experience to deliver LEV systems for a wide range of applications.
HVAC System Automation and Interfacing
As platforms are brought up to date or new equipment is added, greater emphasis is being placed on automation and interfacing with a central control system, principally to improve reaction times to system failures and reduce the workload on operations personnel. This can include retrofitting equipment with CBM sensors, to upgrading control panels to provide additional surveillance or even full automation.
Tyco has completed several significant projects to upgrade HVAC control and monitoring to interact with the clients central control systems.