The US Environmental Protection Agency (EPA) has issued a final greenhouse gas (GHG) Prevention of Significant Deterioration (PSD) construction permit to Natgasoline LLC to construct a new motor-grade gasoline production facility in Texas that uses natural gas as feedstock (gas-to-gasoline, or GtG).
Natgasoline is a new wholly owned greenfield methanol production complex being developed by OCI N.V. The proposed new GtG facility will comprise two main process operations: a methanol plant with a capacity of almost 1.75 million metric tons of methanol per year, and the methanol-to-gasoline plant (MTG), which will produce more than 8 million barrels of gasoline per year. The methanol plant will use natural gas delivered by pipeline as feedstock; the MTG plant will primarily use methanol from the methanol unit, but can also process methanol from other manufacturers.
The methanol feedstock for the MTG process will be fed through a series of MTG reactors, which convert the methanol first in a single reactor into dimethyl ether and then in five parallel reactors into a raw gasoline and liquefied petroleum gas (LPG) mixture.
There will be six gas-fired process heaters associated with the MTG unit: one with each MTG reactor to supply heat to the reaction, and the regeneration heater which will periodically combust coke that will build up on the reactor catalyst during operation.
After the MTG reaction, the combined raw gasoline and LPG mixture will be separated into three streams: a LPG stream, to be sent to LPG storage; a heavy gasoline stream to be routed to the heavy gasoline treatment (HGT) for further processing; and a light gasoline stream to be sent to gasoline blending with the product stream from HGT and storage.
The HGT unit converts undesired components by hydrogenation. The HGT reaction produces and LPG stream that is routed to LPG storage and a heavy gasoline stream to be blended with the light gasoline stream, and then routed to storage and loading.
|MTG process flow. Click to enlarge.|
In its application to the EPA, Natgasoline noted that while a Fischer-Tropsch process is an alternate design basis for converting syngas into liquid fuels, the process converts the synthesis gas into a wide variety of different products (e.g., mainly wax, and then oxygenates such as alcohols, aldehydes, carbonic-acids, and unsaturated hydrocarbons). The wax requires further treatment in order to produce gasoline and diesel. This process would generate significantly more GHG emissions to produce the commercial-grade fuels than the proposed natural gas to methanol to gasoline process it proposed, the company said.
The methanol plant is expected to start production in late 2016. It will be the largest methanol production in the US based on nameplate capacity.
OCI N.V. is a global producer of natural gas-based chemicals and an engineering and construction contractor based in the Netherlands.
In June 2010, EPA finalized national GHG regulations, which specify that beginning on 2 Jan 2011, projects that increase GHG emissions substantially will require an air permit. EPA has finalized 54 GHG permits in Texas, proposed an additional seven permits, and currently has 12 additional GHG permits in development in Texas.
EPA believes states are best equipped to run GHG air permitting programs. Texas is working to replace the federal implementation plan with its own State program, which will eliminate the need for businesses to seek air permits from EPA.