Road Tanker Truck

It seems likely that liquid hydrogen will be delivered to filling stations by LH2 tanker trucks because LH2 does not have to be transported under pressure. The volume of fuel that can be transported is much larger than what is possible with the compressed gas. Nevertheless, the density of liquid hydrogen is lower than that of other fuels (e.g. gasoline), and the tanker has to be well insulated. Therefore, only around 2,000 to 4,000 kg can be delivered by a single tanker, enough to fill 400 to 800 vehicles, or a two to four day supply for a filling station, yet only a 5 to 10 hour supply for a station on a busy motorway. The study considers hydrogen transportation by means of a LH2 tanker truck to transport hydrogen from a depot to a filling station.

3.7.1.1 System Description

The study focuses on a hydrogen delivery by means of a LH2 tanker truck from a hydrogen plant (depot) to hydrogen filling stations situated in a city. The truck delivery characteristics, such as numbers of filling stations, roundtrip distances, and number of deliveries per year were modelled using the spreadsheet model developed by [143] based on hydrogen demand for the city. Coverage of the hydrogen station was compared with the idealized numbers of gasoline stations. According to [143] numbers of the hydrogen stations are at least 10% (for a small market penetration) of the total gasoline stations

_Table 3-6 Hydrogen truck delivery model for the study_

Hydrogen Delivery Model Values Remarks

Population, N:

100,000

Number of population

Average pop. Density, D (1/km2):

1,000

Ranges: 700-1202

Average number of per person, LDVP:

0,8

Ranges: 0,5-1,2

H2 filling station capacity, S (kg/day):

100

Selection: 100, 1500

H2 consumption, Q (kg/veh.day):

0.68

Based on H2LDV 20,000km/yr (Table 2-8)

Fraction of H2 LDVs, H2LDV:

0.01

Selections: 0.01; 0.1; 0.3; 0.7

Distance H2 plant to the city gate, X:

100

in km

Ideal numbers of gasoline station:

40

N*LDVP/2000; 2000 LDVs/station

Hydrogen demand of the city, C:

544

N*LDVP*Q*H2LDV; in kg/day

Number of hydrogen filling station, n:

8

C/(0.7*S); 0.7= 70% of output capacity

City area, A (km2):

100

N/D

Hydrogen station area (km2):

12.9

A/n

Average distance between stations (km):

3.6

SQRT(A)

Round trip distance per delivery (km):

215

2*X + 1.5*SQRT(A)

LH2 truck capacity (kg):

4000

Existing tank truck capacity

Truck delivery per station, T (days):

40

T/S, One truck every 40 days

Truck delivery for the city (days):

5

One truck every 5,1 days

Numbers of deliveries per year:

71

70,9 trips per year

Coverage of the H2 stations:

19.4%

H2 station/Gasoline station, min. 10%

The city was modelled as an ideal area assumed to be "circular" city, with a population density which is higher in the central core and lower in the outer regions. A city of 100,000 people is assumed to have an average population density of 1000 people/km2 or an area of 100 km2 (radius of 10 km). An average number of light duty vehicle (LDV) per person is assumed to be 0.8, so that the ideal number of gasoline stations for the city is 40. The hydrogen demand of the city for the 1% early fleet market penetration (assuming that the hydrogen consumption per vehicle is about 0.68 kg/day) (see Table 2-8) is 544 kg/day. Assuming that the capacity of a hydrogen station is 100 kg/day with the output capacity of 70%, the number of a hydrogen filling station is calculated to be about 8 units. The table also shows that the total roundtrip distance is 215 km with total deliveries of 71 trips per year. The detailed calculation is shown in Table 3-6.

In the QRA study it is also assumed that the city has a uniformly distributed group of equally sized hydrogen stations (Fig. 3.17). The LH2 tank truck is supposed to transport LH2 from a production plant (in city "A") to the filling stations (in city "B"). It makes about 71 deliveries per year along a round trip distance of 215 km. The route is broken into two segments of uniform population density. The first segment is the round trip distance of 200 km (i.e.2x100 km) with the population density of 500 people/km2. The second segment is around the city B of about 15 km with population density of 1000 people/km2.

A = H2 Filling Station

Diagram Filling Station Tank Detail
Figure 3.17 Hydrogen truck delivery for the city B 3.7.1.2 The LH2 Tanker Truck

The LH2 tank truck has a capacity of 53m3 or about 4000 kg of LH2 (-253°C, 0.13 MPa). The tank has dimensions of 2.5m of diameter and 8.5m of length. The tank is typically a doublewalled cylindrical tank consisting of an inner pressure vessel, enclosed in an outer casing or jacket. The inner pressure vessel is designed, manufactured and tested to meet the requirements of "Technische Regeln für Dampfkessel" (TRD), "Bundesimmissionsschutzgesetz" (BImSchG), as well as Sec. VIII of the ASME Boiler and Pressure Vessel Code.

Fig. 3.19 shows a typical internal piping arrangement of a cryogenic tank truck. It has two liquid phase lines. The first liquid line is used to fill the truck at the production plant through connector C/1 and V-8, and to unload it using the off-loading pump through C/2 and V-14. The second liquid line is a pressure-building circuit (PBC) used to increase the inner tank pressure by vaporizing a small amount of liquid. The coil (D) with a large heat transfer area can readily vaporize liquid and return the warmed gas to the ullage (top) space of the tank. This pressure build-up is performed prior to and during the offloading process in order to maintain adequate suction pressure for the centrifugal transfer pump.

The gas-phase lines include a pressure-relief device, which directly communicates with the vapor or gas space near the midpoint of the top centerline. A spring loaded pressure relief valve (V-19) and a rupture disk device (RD) are normally provided on the tank truck. These relief devices are designed to maintain pressure at a safe level under emergency conditions, including exposure of the vessel to a fire. Pressure-relief devices are designed to the requirements of Section VIII of the ASME Boiler & Pressure Code as well as CGA pamphlet S1.2, "Pressure Relief Device Standards—Cargo and Portable Tanks for Compressed Gases."

Another gas-phase circuit has multiple uses as a gas-phase outlet, pressure building coil return, and a transfer pump re-circulation line.

Tank Truck Pressure Relief
Figure 3.18 Schema of an LH2 tank truck [Linde AG]
Tank Truck Pneumatic Valves Scheme
Figure 3.19 Simplified P&I diagram of an LH2 tank truck [131].
Table 3-7 The most important capacities and dimensions of the LH2 truck

Components

Dimension

Capacity

1. LH2 tank

Length 13.6 m, diameter 2.5 m

53,000 l (4000 kg)

2. Liquid line

Diameter of 76.2 mm (3 in)

3. Vapour line

Diameter of 50.8 mm (2 in)

The inner vessel pressure, transfer pump discharge pressure, and liquid contents are monitored with trailer-mounted gauges. A differential pressure indicator is the most common device used for contents measurement. Sampling of product in the inner pressure vessel is necessary in order to determine the level of product purity. A liquid tap typically teed externally to a liquid line can be used for sampling. The vacuum level can be monitored using the trailer-equipped thermocouple gauge tube.

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  • Semere
    How much to fill liquid hydrogen truck tanker?
    7 years ago

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