Gasification Block – Gasification technology is used to convert solid fuels such as coal or petroleum coke to a gas that can be used to fuel gas turbines or converted into Synthetic Natural Gas (SNG) by adding a methanation block to the process. There are several technologies available which Hunton will explore, but the following description is based on the GE gasification technology.

The primary feed to the plant is petroleum coke. The solid fuel is mixed with water and ground into a slurry that can be pumped. The other feed to the unit is oxygen. A conventional air separation unit (ASU) is utilized. Using a cryogenic distillation process, air is separated into oxygen and nitrogen. The oxygen is compressed and routed to the gasification reactor.

The compressed oxygen and the pumped fuel slurry are injected into the reactor. The feed in converted into a high temperature, high pressure, medium BTU gas (about 270 BTU/standard cubic foot) call syngas, which then passes through an acid gas removal process where the CO2 is separated and captured. It then passes through a methanation block, where it is converted into a synthetic natural gas (SNG) of pipeline quality. Any inorganic materials, such as metals that naturally occur in the feed, are melted by the heat of the reactor.

The compressed oxygen and the pumped fuel slurry are injected into the reactor. The feed is converted into a high temperature, high pressure, medium BTU gas (about 270 BTU/standard cubic foot) called syngas. Any inorganic materials, such as metals that naturally occur in the feed, are melted by the heat of the reactor.

The hot gas and the molten minerals travel from the reactor into the radiant cooler. The radiant cooler uses the high temperature heat of the reactants to generate high pressure steam. The steam will be sold to Dow Chemical Company located next to the gasification facility. Dow will use this steam in their chemical processes instead of burning natural gas to generate the steam. Utilizing the process heat increases the efficiency of the gasification facility and reduces emissions from the Dow plant.

Vaporized water in the gas is condensed, and the molten minerals are solidified as the gas cools. The solids, called slag, are removed and sold as a byproduct of the process. Water recovered from the process is used to make the feed slurry. The water contains unconverted carbon from the process. Therefore, recycling the water is environmentally responsible and increases the efficiency of the facility.

Methanation Block – The syngas has about a one to relationship of hydrogen (H2) to carbon monoxide (CO). The syngas goes through a shift reactor where CO and steam (H2O) are converted into H2 and CO2 (carbon dioxide). When the ratio of H2 to CO becomes three to one, then the gas is converted into methane, CH4.

Sulfur Removal Block – One of the benefits of gasification technology is that the sulfur in the feed is also converted into a gas which can easily be removed prior to combustion. The sulfur in the feed is converted to hydrogen sulfide (H2S) and carbonyl sulfide (COS). During the shift process the COS is converted into H2S. The gas travels into the acid gas removal process. A solvent is used to absorb acid gases such as H2S and CO2. The H2S is converted to elemental sulfur and sold as a byproduct from the facility. The CO2 is compressed and fed into oil wells in the region for enhanced oil recovery (EOR).

Steam – The gasification and methanation processes generate significant heat which is captured by generating steam, which will be readily utilized by Dow Chemical in its production of various chemicals. This enables Dow Chemical to reduce its reliance on combustion turbines to produce steam, thereby, significantly decreasing their greenhouse gas emissions.