Hydrogen Units

The Desulfurization Drums are an important part of the hydrogen units. Methane is first fed through a Desulfurization Drum where sulfur impurities are removed before feeding the Reformer. There are two sulfur drums for each unit. Each is filled with activated charcoal. One drum is always in service. Each week the drums are swapped, and the active drum is taken out of service and regenerated by steaming it with 300# steam for B hours.

The Reformer is the primary equipment of a hydrogen (H2) unit. Hydrogen is manufactured by steam reforming of natural gas (methane of CH4). The gas is mixed with superheated steam in the Reformer manifold. This mixture flows through eight vertical tubes in the furnace. This is an endothermic reaction. These tubes contain nickel catalyst. The furnace is a single vortex burner, brick and insulated by blanket lined firebox. The tubes are heated in the furnace by burning natural gas. Gas temperature leaving the tubes is ~790-83O degrees Centigrade. At this point, H2 has been formed. However, the gas is a mixture of ~76% H2 and 13% CO, 10% C02, and 1 % CH4.

The rest of the equipment in the hydrogen unit is used to purify the H2 to 97%. The gas leaving the furnace is cooled by quenching with condensate. The gas leaving the furnace exit manifold enters the top of the quench drum and passes down through a 1-118 cubic feet bed of 1 inch stainless ring packing. Condensate is pumped from the condensate tank into the top of the quench drum through a spray nozzle. (Heliflow is used for start-up, and for emergency cooling). This cools the hot gas stream from 815 deg to 260 deg. centigrade. Exit the quench drum, the gas flows through the Shifter Converter.

The Shifter-Converter contains a bed of copper-zinc oxide catalyst. In the shifterconverter most of the CO reacts with water, and is converted to C02 to H2. The reaction in the shifter is exothermic. The shifter exit gas is about 300 deg. centigrade and contains ~79% H2, 19% C02, and 2% CO and CH4. (Condensate required for the shifter reaction comes from the condensate added to the quench drum). The exit gas then flows the tube side of the converter heat exchanger where it is cooled to about 165 deg centigrade. It then passes through the reboiler tube bundle to provide heat for MEA reactivation. Condensate from the condensate tank is used here to control the reboiler temperature.