Pleased to meet you hope you guess my name
But what's puzzling you is the nature of my game.

("Sympathy for the Devil," by Mick Jagger, 1968).

 

SYN GAS PRODUCTION AND WHBs

The next two PTOA segments will be dedicated to reviewing steam reforming processes and the Waste Heat Boilers (WHBs) that will be standard equipment in a steam reforming processes.

"Steam Reforming" logically infers using steam to change the structure...and thereby "reform"...feedstocks into desired products.

PTOA Readers and Students are already very familiar with the Steam Methane Reforming and Water Gas Shift Reactions shown above because these reactions were featured in PTOA Segments #23 and #27 which respectively focussed on using steam to make Hydrogen (H2)and how to interpret a chemical reaction.

The combined products from the first two reactions...Carbon Monoxide (CO), Hydrogen (H2), and Carbon Dioxide (CO2) are collectively called "Syngas."

"Syngas" is short for "Synthesized Gas." "Synthesized" means "manufactured" or "produced by man-made technologies."

By tweaking temperatures and pressures, the components of Syngas can be favored to make more CO or CO2 instead of  Hydrogen.

The steps that follow the production of Syngas determine which of a variety of Syngas-derived products will be made. Besides Hydrogen, the short-list of Syngas derived products includes:

Ammonia which is used as a fertilizer.

Methanol which is used to make fuel gas additives and also is used to make acetic acid..the main  ingredient in plastic bottles.

Formaldehyde which is used to make home building products.

Ethylene which is a building block to make many petrochemicals and plastics. Ethylene is the most synthesized organic chemical. Ethylene is made by steam reforming hydrocarbons that are a little larger than methane.

Even "clean" diesel and gasoline can be made from steam reforming natural gas. The expensive yet do-able processing to make motor fuels from natural gas was used in Hitler's Germany and South Africa during the years that South Africa was boycotted.

Whichever product is favored for production, the Reaction Furnaces required to produce Syngas require a lot of thermal energy made by combustion.

Ergo, these industrial processes will include Waste Heat Boilers that make high pressure steam as a by-product and simultaneously recover heat that would be wasted and needlessly injected into the atmosphere.

PTOA Readers and Students may work in a natural gas conversion process plant someday.

Fuel refineries,petrochemical complexes, and natural gas conversion process industries will have Syngas generators.

Plant Employers will respect process plant workers that understand the economic considerations related to upgrading feedstock into desired products.

 

NATURAL GAS = METHANE=CH4

Natural gas is the same city gas that fuels the burners of a home gas range.

Natural gas=Methane gas! They are one and the same.

The chemical structure of Natural Gas/Methane Gas is CH4...one Carbon molecule holding hands with four Hydrogen molecules.

Natural Gas ... Methane ... CH4 ... is left over organic material from dinosaur days which can be directly recovered from natural gas fields and also comes out of the ground with crude oil.

At the time this PTOA segment was written, natural gas production by hydraulic fracturing was a highly controversial yet effective energy substitute that had decreased the USA's dependence upon foreign oil imports.

Indications are that the production and conversion processing of natural gas will be prevalent for decades to come.

 

THE STEAM METHANE REFORMING (SMR) PROCESS

The chemical reaction taking place in the Reaction Furnace of a Steam Reformer is the top reaction shown in the box to the above right...the one that is labelled "Methane reforming rxn."

"Rxn" is an abbreviation for "reaction."

The reforming of Methane with steam (the SMR Reaction) is very endothermic.

PTOA Readers and Students already know that "endothermic" means that the reaction requires heat to continue.

Would you believe the SMR reaction is so endothermic that temperatures ranging from 1800-2200 °F must be supplied for the reaction to continue? That is 980-1204°C! Hot on any temperature scale!

This "need for heat" translates into a whopping fuel gas and/or natural gas fuel bill because a large quantity of either or both of them is combusted in the Reaction Furnace 24/7!

A schematic of the Reaction Furnace of a Steam Methane Reformer is below. PTOA Readers and Students should trace out the lines and verify the following statements:

• Natural Gas (aka Methane) and Steam (H2O) are blue lines that flow into the top of three reaction tubes. The reaction tubes are stuffed with catalyst that convert the Methane into Hydrogen and Carbon Monoxide (Syngas).
• Syngas product (peach colored line) flows out of the bottom of the Reaction Furnace of the Steam Methane Reformer.

• Downward-firing burners generate sufficient heat to keep the endothermic reaction going.The hot temperatures in the Reaction Furnace are generated by fuel gas and air combusted in the burners which are at the top of the Reaction Furnace (maroon colored lines).
• The flue gases (aka combustion products) flow out of the bottom of the Reaction Furnace as light blue lines.

A case study of generating Syngas to make ammonia is featured in the next PTOA Segment. PTOA Readers and Students will learn the next processing steps for the Syngas and hot flue gases that exit the Reaction Furnace.

 

TAKE HOME MESSAGES: Natural Gas and Methane Gas are one and the same.

Methane production is increasing in the USA and more than likely methane processing will increase as well.

Methane can be reformed into a variety of products, all of which must first go through the step of making Syn Gas.

Syn Gas is composed of Hydrogen (H2), Carbon Monoxide (CO), and Carbon Dioxide (CO2).

The Syn Gas generator in a steam reforming plant is called a Reaction Furnace. 

The Steam-Methane Reaction (SMR) is very endothermic; high temperatures are required to keep the reaction going.

Waste Heat Boilers and heat recovery systems will be features of any industrial complex that includes a steam reforming process.

 

©2015 PTOA Segment 00044
Process Industry Stationary Equipment: Steam Methane Reaction Furnace

 

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