Odorization of large quantities of natural gas at hubs in the distribution network

Network operators transport natural gas through gigantic gas transport networks to power plants, industrial operations and, using local networks, to private households throughout Germany. At distinct hubs, large quantities of gas arrive that are subsequently funneled into different sub-networks and various directions. A gas pressure controller and measuring system ensures compliance with mandatory safety regulations and processing without a hitch. It also regulates the inlet pressure to the required outlet pressure rating. At this stage, the gas is usually odorized—a measure intended to make the unintentional escape of gas recognizable early on for everybody. Thus, safety risks and accidents can be prevented, and gas leaks can be detected in a timely manner.

At this point, LEWA comes into play. For decades, LEWA has been building systems for gas odorization and has acquired unparalleled expertise regarding processes and applications.

In 2015, a major natural gas network operator enlisted this expertise. Using an odorizing system of the OD 4200 type specifically manufactured for this customer, it was possible to develop a solution that takes the on-site conditions into account and matches the customer's difficult process requirements optimally. Tetrahydrothiophene (THT), an organic sulfur compound with an intense odor, is used as the odorant. Using the OD 4200, THT odorizes quantities of up to one million standard cubic meters per hour.

Not only is the OD 4200 the largest odorizing system ever produced by LEWA, but it is also currently the largest of its kind in Germany.

The following properties make the OD 4200 an optimal solution for the application at the hub of the gas network:

• 3 pressure-shock resistant supply containers with a capacity of 4,200 l of odorant (3 x 1,400 l)
• Throughput of the required gas quantities using 4 LEWA ecoflow diaphragm metering pumps of the LDB type
• Throughput of up to 1,000,000 standard cubic meters per hour against a pressure of 70 bar
• High metering accuracy and automatic shutoff by pressure switch in case of fault
• Every 100 hours, pump 1 and pump 4 take turns as reserve pumps to prevent the valves from clogging, etc.
• Automatic report of faults to the main control unit on the customer's side
• Metering control using an electronic supervising system in the control cabinet
• 4 LEWA OCU odor control systems (controlled by PLC on the customer's part) including 4 SPU and SIOU network and power supply units and 4 EXU input cards
• Determination of the filling level using a capacitive probe
• Prevention of vessels from overflowing using a solenoid valve control card (automatic shutoff of the solenoid valve)
• Measurement of the odorant flow by 4 flow meters in the odorizing system or in the discharge line to the injection point
• Wetted parts made of 1.4404, 1.4571, 316SS steel, PTFE, perfluor elastomer or glass
• Cleaning the pump heads and the suction and pressure lines using 4 flushing systems
• In case of leakage, the escaping odorant is caught in a trough, which is tested in accordance with the steel trough directive
• Activated carbon filters for odor control in the ventilation lines of the vessels (including a three-way valve for the connection of a vapor return line)
• Flame protection filters as protection against explosions in the air venting line

OD 4200 installation dimensions