What is bog gas?

This natural evaporation, known as boil-off is unavoidable and has to be removed from the tanks in order to maintain the cargo tank pressure. …

What is bog in oil and gas?

Heat slowly affects the tanks, which can cause the LNG inside to evaporate and produces a substance known as boil-off gas (BOG). Natural gas remains liquefied by staying at a consistent pressure, but when boil-off occurs and it returns to gas, the larger volume of gas will increase the tank pressure.

What is required to enable bog?

The BOG, at about -143°C and atmospheric pressure, is taken from the cargo tanks and passed through a compressor, where its pressure is raised to 4.5 bar and temperature to -60°C. This is then passed through one side of a nitrogen heat exchanger where its temperature is reduced to -160°C at between 2 and 4 bar.

What is bog Reliquefaction?

The BOG reliquefaction process is based on reversed nitrogen Brayton cycle refrigeration technology. This means that the process is a closed nitrogen cycle for extracting heat from the boil-off gas. Typically, the reliquefaction system is used to control the cargo tank pressure by liquefying boil-off gas.

What is boiled of gas?

The Boil Off Gas (BOG) is the continuously evaporated or boiled LNG vapor that causes the pressure inside the tank to rise due to heat entering the cryogenic tank during storage and transportation, which changes the quality of LNG over time.

How is bog rate calculated?

An approximate BOG generation value can be calculated by dividing the total heat input by the latent heat of the refrigerated product at fluid temperature.

Does LPG boil off?

Liquefied petroleum gas (LPG) is stored and transported in tanks as a cryogenic liquid, at a temperature below its boiling point near atmospheric pressure. Due to heat entering the cryogenic tank during storage and transportation, a portion of the LPG continuously evaporates, creating a gas called boiloff gas (BOG).

How boil off gas can be consumed in engine room?

Boil-off gas (BOG) combustion system – BOG combustion systems are used only onboard LNG carriers. Excess BOG is sent to the engine room via gas heaters by low capacity compressor and is burned by the main boilers as fuel.

What is boil off rate?

marine. The amount of liquid that is evaporating from a cargo due to heat leakage and expressed in % of total liquid volume per unit time.

What is boil off gas compressor?

Boil off gas enters into the suction line of the compressor, is compressed and sent either to a condenser for re-liquefaction, fed into a gas turbine as fuel in a power generation plant, or is directed into a pipeline for city gas usage. …

Does LPG gas evaporate?

As its boiling point is below room temperature and heat, LPG will evaporate quickly at normal temperatures and pressures and is usually supplied in pressurized steel vessels. LPG is heavier than air, unlike natural gas, and thus will flow along floors and tend to settle in low spots, such as basements.

At what temperature does LPG become a gas?

What’s the boiling temperature (point) of LPG? Water boils at 100°C or 212°F, becoming a gas (steam). In contrast, LPG (propane) boils at -42°C or –44°F, becoming gas vapor.

When to use forcing Bog or boil off gas?

ii)Forcing boil-off gas (Forcing BOG) Burning: If the fuel consumption of the main generators cannot be met by the gas supplied by natural boil-off from the tanks, additional gas can be obtained by utilizing the forcing vaporizer.

How is excess bog sent to the engine room?

Excess BOG is sent to the engine room via gas heaters by low capacity compressor and is burned by the main boilers as fuel. The main boilers are capable of operating under different fuel combustion modes such as exclusively BOG mode, combined BOG and fuel oil mode, and exclusively fuel oil mode.

What does boil off mean on a LNG tanker?

Boil-off gas (BOG) LNG tanker s are designed to carry natural gas in liquid form at a temperature of – 163°C, close to the vaporization temperature. Despite tank insulation designed to limit the admission of external heat, even a small amount of it will cause slight evaporation of the cargo. This natural evaporation, known as boil-off is

How does the LNG carrier recover boil off gas?

Boil-off gas (BOG) recovery system, also BOG reliquefaction plant– An onboard reliquefaction system that recovers boil-off gas in LNG carriers and returns it to the cargo tanks.