Gas desulphurisation

The ratio of limestone to fuel required for effective desulphurisation depends upon both the mineral and sulphur content of the coal. It may be possible to burn low sulphur (<0.8%) western coal directly with 90% sulphur retention thus avoiding the necessity for flue gas desulphurisation and still meeting environmental SO2 emission regulations (18). Fluidyne (19) have indicated that a 3.65% Illinois coal with 0.3 lbs. of dolomite added per pound of coal in a fluidised bed combustor can reduce SO2 emission to less than 1.2 lbs. of SO2 per million BTU thermal output thus meeting U.S. EPA limits for large plants. 

The potential of ammonia-based flue gas desulphurisation waste solution as a nitrogen fertiliser has been assessed by Gissel-Neilson and Bertelsen (1989) by field trials using barley and rye grass. The solution had the same fertiliser value as calcium-ammonium-nitrate. The toxic effects of sulphite were reduced by avoiding direct contact of the solution with the plants. 

Side-entering wide blade impeller (HE3-S or Mark II) Oil storage. Paper pulp. Wastewater circulation. Flue gas desulphurisation... 

C Heat exchanger D Heat storage tank E Control E Auxiliaiy burner G DC/AC converter H Gas desulphurisation unit I Water treatment J Exhaust... 

AN OPTIMAL STRATEGY FOR RETROFIT FLUE GAS DESULPHURISATION IN THE UNITED KINGDOM... 

The aim of the optimisation is to determine the spatial pattern of retrofit flue gas desulphurisation FGD which, for a given total installed capacity of abatement, minimises the magnitude of the difference between the deposition loads and the critical loads for total sulphur deposition at the receptor sites. Such differences between deposition loads and ciritical loads are termed critical load exceedences. For a near continuous distribution of emission controls at about 50 power stations and 11 receptor sites, there are a large number of possible strategies to work through in an exhaustive analysis. The problem was solved using optimisation by simulated annealing [8-10], a specialised iterative improvement technique. 

Optimisation by simulated annealing and retrofit flue gas desulphurisation strategies. 

In November 2004, the government also proposed that some further cases could qualify as new entry. These included development of existing offshore platforms known as tie-backs , as well as changes to installations due to compliance with environmental regulations (such as the installation of flue-gas desulphurisation equipment) and increases in levels of good quality combined heat and power from eligible CHP stations would also be able to receive allowances from the new entrant reserve. 

The single furnace options incorporate flue gas desulphurisation (FGD) scrubbing whereas the two furnace options incorporate double contact sulphuric acid plants. 

C. Bautsch, H. Fahlenkamp Detailed simulation of wet flue-gas-desulphurisation scrubbers with CFD, Proceedings of the International Conference on Liquid Atomization Spray Systems (ICLASS 2006), Kyoto, Japan, paper ICLASS06-238. 

Figure 3.27 Flow schematic of flue gas desulphurisation by membrane gas absorption. Source [39],...

R. Klassen, A.E. Jansen, Achieving flue gas desulphurisation with membrane gas absorption, Fdt. Sep. (2003) 26-28, September. 

Kiel, J.H.A., Prins, W., and van Swaaij, W.P.M., Modelling of non-catalytic reactions in a gas-solid trickle fiow reactor dry, regenerative flue gas desulphurisation using a silica-supported copper oxide sorbent, Chem. Eng. Set, Al, 4271, 1992. 

J. Longhurst, The British flue gas desulphurisation programme. Acid magazine, 8, 22, 1989. 

Flue gas desulphurisation in large (>25 MW) coal/lignite boilers... 

On large coal fired boilers >25 MW, flue gas desulphurisation is necessary to control SO2 emissions. Removal efficiencies are in the 80-90% range FGD is now a fully commercialised technology with some 25,000 MW of capacity installed in Japan and the USA. 

Flue gas desulphurisation (FGD) processes. A near commercial process (ISPRA) [51] is based on reaction of sulphur dioxide with electrochemically generated bromine ... 

Other FGD processes. A variety of processes for flue gas desulphurisation [52] shown in Table 11.3, have been researched. The processes can be divided into two categories, direct and indirect electrochemical processes. 

In flue gas desulphurisation, direct electrochemical oxidation using electrocatalyst is sensitive to impurities in the gas stream. To overcome this potential problem several processes have been proposed using homo-... 

Figure 11.9 Block diagram of the ISPRA mark 13A process for flue gas desulphurisation.

ELECTROCHEMICAL ASPECTS Table 11.3 Flue gas desulphurisation (FGP) processes... 

A similar high temperature membrane separator has also been applied to flue gas desulphurisation. In this case the operating temperature is much lower than that for the treatment of hydrogen sulphide, i.e. 350°C. A different combination of molten salts of Li, Na and K sulphates are also used in this application (see Figure 11.11). 

Pollution control devices like electrostatic precipitator and flue gas desulphuriser are required if ash and sulphur content are more in the solid fuel (e.g. some varieties of coal, petroleum coke, etc.). These are costly. 

Galos, K. A., Smakowski, T. S. Sc Szlugaj, J. (2003). Flue gas desulphurisation products from Polish coal-fired power-plants. Applied Energ)f, 75(3-4) 257-265. 

Another part of the integration is that the biological waste water treatment plant treats all the waste waters from the site as well as the municipal waste water. The off-gas treatment for the production of viscose is combined with a sulphuric acid production unit. Gases containing sulphur can also be used as combustion air in various combustion plants with flue-gas desulphurisation. Additionally, the supply networks for steam and process water are highly sophisticated. 

Ferritic, austenitic, or ferritic-austenitic cast alloys are used in preference as materials for pumps in scrubber circuits of flue gas desulphurisation plants (FGD... 

Table 9 Essential parameters of scrubbing solutions in flue gas desulphurisation plants that operate with the calcium carbonate scrubbing process [29]...

---