Coal Gasification is a Big Business with Lots of Challenges

This was the conclusion reached in the Hot Topic Hour yesterday. GE has 150 gasifier systems in operation with many more under planning and construction. South Korea, India, Mongolia, and the Ukraine are all realizing that coal can be the lowest cost source for gas, chemicals, and fuels.  China is the leading purchaser. Here is the McIlvaine forecast for gas in China in billions of m³ per year.

The first column is the aggregate forecasts of the industry as of last year. The second column represents the McIlvaine forecast based on the assumption that China executes its proposed plan in entirety. If China does gear up to provide 200 billion m³/yr of gas from coal, it will change the world’s energy picture in a major way.

Coal gasification is the largest present use of ceramic and metal high temperature filter elements.

Stack Gas Volume flowing through High Temperature Filter Elements

Coal Gasification Overview by Bob McIlvaine - Hot Topic Hour February 12, 2015

McIlvaine believes that coal-fired power plants should take advantage of all technology to improve plant efficiency as well as to cost-effectively meet the environmental requirements.

Revision Date:  2/13/2015

Tags:  221112 - Fossil Fuel 化石燃料, 221112 - Fossil Fuel 化石燃料, McIlvaine, Filter Elements

Large pipeline and power plant gasifers are presently processing more than 7.5 million cfm of flue gas through high temperature filters (some goes through scrubbers). Industrial gasifiers add to this total. Other industrial applications such as refinery catalytic crackers, smelters, chemical plants, etc. are using candles. There many such applications but most are only small, e.g. 5,000 cfm.

Coal-fired power plants nearly all use low temperature filtration. Ninety percent process the gas at 350°F through electrostatic precipitators. The total is over 8 billion cfm. The new particulate regulations around the world are forcing these plants to gut the precipitators and replace them with media filters. There are many reasons why high temperature ceramic filters should be the replacement choice. An article on this appears later. If this were to occur the market for elements would be billions of dollars per year.

Mike Bockelie of Reaction Engineering discussed ways to solve the fouling of syngas coolers.  This study for DOE evaluated three options including:

• Soot blowers
• Coatings
• Sorbent injection

Sorbent injection was investigated to remove metal sulfides, vanadium and sodium Sorbents considered were

• Limestone - has high capture efficiency for sulfur
• Kaolinite - captures sodium and vanadium
• Focus è Aurora = “engineered” kaolinite

• commercially available
• demonstrated to have good performance at relevant conditions

Testing determined that the sorbents present a viable solution. The fouling was due to sub-micron particulate adhesion. The sorbents captured 90% of this particulate.

In the Q &A the question was posed as to whether the sorbent would also result in lower stack gas emissions. Mike said that this had not yet been investigated.

Another question was whether sorbent injection could be a way to eliminate the SO₂ scrubber.  Mike thought that the erosion in the cooler would be a problem.

Toward a Technology to Mitigate Syngas Cooler Plugging and Fouling by Mike Bockelie, Reaction Engineering International - Hot Topic Hour February 12, 2015

Mike discussed ways to solve the fouling of syngas coolers.

Revision Date:  2/13/2015

Tags:  221112 - Fossil Fuel 化石燃料, 221112 - Fossil Fuel 化石燃料, Reaction Engineering International, Filter Elements

Keith Moore of CastleLight provided details on the in-furnace gasification system.  Coal is first beneficiated. Limestone is mixed with it and then the mix is gasified.

NO_x and sulfur are reduced to low levels. There is a substantial efficiency increase. Keith observed that the existing electrostatic precipitator may have to be replaced with a baghouse to meet MACT, but no other major equipment would be required.

Keith believes that this is a cost-effective retrofit option for the older utility coal-fired power plants and for industrial boilers.  

Bob McIlvaine observed that many owners may be concerned that this approach is attractive only if it meets all the emission limits both present and future.  If additional SO₂, NO_x, or mercury removal is needed then the cost could be substantial. However, the new catalytic filter, DSI, high efficiency heat exchanger route could provide the flexibility to cost effectively provide greater emission reduction. Keith expressed interest in pursuing this and McIlvaine promised to send the schematic proposing a flexible program. 

Re-Engineering Coal-Fired Electric Generating Plants with Coal Gasification by Keith Moore, CastleLight Energy - Hot Topic Hour February 12, 2015

Keith provided details on the in-furnace gasification system. Coal is first beneficiated. Limestone is mixed with it and then the mix is gasified.

Revision Date:  2/13/2015

Tags:  221112 - Fossil Fuel 化石燃料, 221112 - Fossil Fuel 化石燃料, CastleLight Energy, Filter Elements

NEW APPROACHES TO POWER PLANT APC

The Catalytic Filter-DSI-HE Heat Exchanger-Mercury Module Option  

Clear Edge, Trimer, and Lhoist have considerable experience with a technology to take out all the pollutants in one chamber. Now Haldor Topsoe and FLS are teaming to offer catalytic filter elements with a big investment in new facilities and expanded staff.  McIlvaine believes that coal- fired power plants should take advantage of this technology to improve plant efficiency as well as to cost-effectively meet the environmental requirements. An entire new free website is being populated with the details.  http://www.mcilvainecompany.com/HotGasAnalysis/Subscriber/Default.htm

The concept involves removing the existing rotary heat exchanger and electrostatic precipitator and replacing it with the following train.

What are the advantages of this approach?

• Provide reductions of particulate, SO₂, NO_x, HCl, and mercury to meet MACT
• Small footprint
• Up to 3% increase in boiler efficiency due to

• Heat recovery from 850°F-150°F
• Eliminate the 10% leakage with rotary heat exchanger
• Low fan horsepower

• Flexibility
  • Add mercury module if needed
  • Can augment with SNCR at low capital cost if lower NO_x needed

• Low capital cost
  • For new system it is one device vs  baghouse, SCR and wet scrubber with up to $400/kW investment
  • For retrofit there are even bigger savings because of the small foot print

• No wastewater challenges
• No steam plume at the stack

There are hundreds of thousands of candles in operation. There are many thousands with the embedded catalyst.  The performance, maintenance requirements and life have been impressive on glass furnaces, biomass combustor, waste-to-energy plants, and mining operations. Component suppliers such as Pentair Goyen are designing pulse cleaning systems specifically for these elements. With the new manufacturing facilities in Houston Haldor Topsoe will add substantially to the supply capacity.

The conclusion by McIlvaine is that this technology is a very viable alternative. If a plant wants to sell flyash and gypsum then it will not be attractive. However, smaller plants will find this process very attractive.

Large plants would be well advised to consider the catalytic filter for dust and NO_x and a separate SO₂ removal unit. The Chinese plants, which already have wet FGD but need to upgrade particulate and NO_x controls, would be well suited to this approach. They could use condensing heat exchangers such as available from B&W.

HCl Scrubbing and Rare Earth recovery from Coal-fired Power Plants and Gasifiers

There are two proven technologies; but for the first time there is a proposition to marry the two and make coal much more attractive as a fuel source.

McIlvaine has long been advising power plants to consider making hydrochloric acid in a two scrubber system.  Bob McIlvaine was President of Environeering in 1970 when United Engineers bought HCl and SO₂ scrubbing systems from the company for Philadelphia Electric.  These systems operated for more than 25 years.

Relative to coal gasifers, the E gas system has a separate HCl scrubber. McIlvaine also suggests that the GE particulate scrubber could be run at low ph and produce hydrochloric acid. China is now mining flyash to recover large quantities of rare earth elements and metals. One of the leaching methods is with hydrochloric acid. Why buy hydrochloric acid when you can make it as part of the process?  The schematic below is a way to marry both processes.

Neumann has a contract from DOE to extract REEs and metals in conjunction with a scrubbing system which it is installing at Colorado Springs Public Utilities. The proposed approach differs by proposing that rather than buy acid, the power plant can make it.  The HCl content does not have to be high.  The first stage scrubber starts with water and then reaches equilibrium with 30 percent dirty acid. A portion is bled to maintain this percentage.

The advantages of using high chlorine coals would be that these coals are less expensive and the byproduct sales volume of acid will be higher.

The Chinese believe coal flyash is already a very attractive source for REEs.  This new approach would make it even more attractive.

Gasification Air Pollution Control Webinar - Hot Topic Hour February 12, 2015

Coal Gasification is a Big Business with Lots of Challenges.

Revision Date:  2/13/2015

Tags:  221112 - Fossil Fuel 化石燃料, 221112 - Fossil Fuel 化石燃料, Reaction Engineering International, McIlvaine, CastleLight Energy, Filter