The LH Storage

The LH2 storage mainly consists of a horizontal cylindrical cryogenic tank with a capacity of 270,000 litres (17,000 kg of LH2) at temperature of -253°C and pressure of 0.13 MPa, pressure building circuits, and piping system. Fig. 3.8 shows a simplified P&I diagram of the system developed in the study based on [216], study visit to a similar plant, and discussions with some experts. The LH2 tank is filled directly from a liquefaction plant. It is equipped with the level indicator LI, level switch (LSHL), and a trip switch (LSH) at successively higher levels. It has two independent shutoff valves V-1 and V-3, both of which are operator actuated. The LI is simply an indicator which has also transmitted to control room. The LSHL is connected to an audible/light alarm, and LSH to an automatic trip system and close main valve of the plant (PCV-40). The LH2 is withdrawn to an LH2 tanker truck through remotely controlled valve V-5.

The tank pressure is maintained by a pressure building circuit which mainly consists of a coil (ambient evaporator, D) and its pressure regulator (PCV-1). The circuit vaporizes liquid hydrogen from the bottom of the tank and sends hydrogen in the gas phase to the tank (top). Operation of the circuit is controlled by the PCV-1 triggered by PIC-1 based on the tank pressure (low) obtained and transmitted by pressure transmitter (PT). When the pressure in the tank is lower than the set point of the PCV-1, then the circuit is working.

In order to protect the tank against overpressure two pressure safety valves (SV-1, SV-2) are installed. One of the two safety valves is operated exchangeable at relative pressure of 0.143 MPa. Additionally, the PCV-2 is used as the secondary pressure relief devices. The operation of the PCV-2 is similar to the PCV-1, but it opens if the tank pressure is high.

Additionally, the tank is equipped with pressure switches (PIS and PSHL) used to protect the tank against excessive lower pressure. The PSHL activates the PCV-3 to close in case of the tank pressure is very low.

Diagram Genset

Figure 3.8 Simplified P&I diagram of the LH2 tank at depot [216, 223]

V 3-10 - Hand operated valves

RV/O - Outer relief valve

SV 1-6 - Pressure safety valves

PIC - Pressure Indicator controller

PT - Pressure transmitter

LSH - Level switch high P & I DIAGRAM

LSHL - Level switch high low

1-)- - Vacuum valves LH2 Tank at a Liquefaction Plant

Figure 3.8 Simplified P&I diagram of the LH2 tank at depot [216, 223]

Table 3-2 The most important capacity and dimension of the LH2 storage at depot


1. LH2 tank Horizontal cryogenic tank V=270,000 liter (17,000 kg).

2. Liquid lines Diameter of 101.6 mm (4 in)* 180 kg/h

3. Vapor lines_Diameter of 101.6 mm (4 in)* 180 kg/h_

Source. Linde AG; (*) estimated value

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