Gasification – Application Overview

Gasification – Application Overview

Gasification is a thermal/chemical process that converts any carbon-containing material into a synthesis gas composed primarily of carbon monoxide and hydrogen. During this process, a lower-value carbonaceous/hydrocarbon feedstock (coal, petroleum coke, biomass, etc.) is subjected to high temperatures, moderate pressures and reducing conditions, for conversion to a higher value synthesis gas (syngas) by means of partial oxidation with air, oxygen, and/or steam.

The hydrogen-to-carbon ratio of coal is lower than that of liquid or gaseous fuels. Therefore conversion of coal into an alternative fuel must involve either an addition of hydrogen or a rejection of carbon.

Gasification converts low value residuals into higher value synthetic products. Petroleum feed is mixed at high temperatures (above 350°C/662°F) with oxygen and steam in a gasifier vessel. A hydrogen and carbon monoxide gas mixture called synthesis gas (syngas) fuel is produced and drawn from the gasifier.

The syngas is further scrubbed and cleaned. An inter ash/slag by-product is also produced at the bottom of the gasifier.

PROCESS BENEFITS: 

Fuel flexible

• Coal, pet coke, refinery wastes, biomass, sewage sludge and MSW
• High sulfur feeds accepted

Environmentally superior

• Low CO, SOx and NOx emissions
• Zero particulate emissions
• No solid wastes
• Sulfur recovered as by-product

PROCESS: 

• A hydrocarbon feedstock is fed into a high-pressure, high-temperature chemical reactor (gasifier) containing steam and a limited amount of oxygen.
• Under these ‘reducing’ conditions, the chemical bonds in the feedstock are severed by the extreme heat and pressure and a syngas is formed and drawn from the gasifier.
• The moisture in the feedstock is evaporated and exits the gasifier in the vapor phase as a component of the gas stream, acting as a diluent, thereby reducing the energy content of the gas.
• Under the reducing conditions in the gasifier, most of the fuel’s sulfur converts to hydrogen sulfide (H2S).
• The syngas is further scrubbed/cleaned.
• An inert ash/slag by-product is also produced at the bottom of the gasifier.

MARKET APPLICATIONS: 

• Refinery based co-production (power, steam, hydrogen) from coke, resid.
• Baseload power
• Coal repowering
• Combined cycle refueling
• Feed to chemicals – NH3/urea
• Feed to methanol
• Feed to ultra-clean fuel (diesel)

DRIVERS: 

• Electric power deregulation
• Increased energy demand
• Clean energy solutions – greenhouse gas reductions
• Strain on natural gas – driving prices up – supply uncertainty
• Continued reliance on coal in U.S.
• Significant reserves – clean coal emphasis
• Significant world scale coking capacity additions – more pet coke on the market
• Refineries processing heavier crudes – results in lower value pet coke
• Increased demand for hydrogen in refineries
• Ultra clean transportation fuel
• Direct reduced iron production
• Chemicals – ammonia / fertilizers

ENVIRONMENTAL BENEFITS:

• Gasification processes “bad actors” in coal/coke prior to end use
• Allows power generation of low value fuels (feeds) with near natural gas performance and emissions
• Lower all around emissions versus conventional solid fuel technologies

SUMMARY: 

• Gasification is the cleanest, most efficient commercial means to generate power from solid fuels
• Continuing trend of oil, gas and electric power markets improves IGCC prospects
• Growth rate of gasification is accelerating – additional opportunities in chemicals (from coal and petcoke)
• Environmental pressures (including Hg, CO2) favor gasification
• Technical advancements aid gasification
• Challenge – providing the market a mature technology
• This industry represents a ripe market for specialty valve OEMs due to combination of technology, plant size and market growth

FLOW DIAGRAM
Item	Applications	Temp range (°F)	Pressure (psi)	Size (in)
1	Slurry tank emergency block valve	250 – 500	100 – 200	6 – 10
2	Feed slurry pump isolation	38 – 100	100 – 200	6 – 10
3	Gasifier isolation	38 – 150	900 – 1200	6 – 10
4	Oxygen feed isolation	38 – 100	900 – 1200	4 – 8
5	Coarse slag lock hopper isolation	50 – 350	900 – 1200	6 – 12
6	Lock hopper drum inlet	200 – 320	900 – 1200	12 – 24
7	Lock hopper drum outlet	200 – 320	900 – 1200	12 – 24
8	Level control let down isolation	38 – 150	100 – 200	4 – 10
9	Backwater flash drum isolation	50 – 350	900 – 1200	4 – 10
10	Oxygen depressurizing valve	38 – 100	900 – 1200	4 – 8
11	Oxygen depressurizing isolation	38 – 100	900 – 1200– 2600	4 – 8