Scrubber capital cost

The electrostatic effect can be incorporated into wet scrubbing by charging the particulates and/or the scrubbing-liquor droplets. Electrostatic scrubbers may be capable of achieving the same efficiency for fine-particulate removal as is achieved by high-energy scrubbers, but at substantially lower power input. The major drawbacks are increased maintenance of electrical equipment and higher capital cost. 

Since power is a substantial component of the fixed operating cost of a unit, the operating cost would run approximately seven times more on a scrubber installation. The installation costs of a hot-rolled steel precipitator to handle 100,000 cfm would be between 3.50 and 4.50/cfm as opposed to 1.40 to 1.80/cfm for a venturi scrubbing system. Although the initial capital expenditure is high for the precipitator, if the total operating and capital costs are amortized over an acceptable period of time, 8 to 10 years, the precipitator will prove to be the. lore economically feasible choice because of its low operating and maintenance costs. 

As noted above, batch and semi-batch-based operations result in periodic high loads and subsequent over-design and increased capital cost. By destroying the hypochlorite in situ, within the scrubber recycle loop, the end of cycle concentration can be reduced and the load on the end-of-pipe hypochlorite destruction system lowered allowing an overall cost reduction. The reduced free chlorine concentration also leads to improved process safety, although increased heat removal is required. 

There are two basic evaporator designs that are typically used atmospheric and vacuum evaporation (Metals Handbook 1987). Atmospheric evaporation principles are similar to those of a heated open tank, with the exception that the heated liquid is sprayed over plastic packing in order to increase its surface area and accelerate evaporation. Atmospheric evaporators on chrome plating lines have sometimes been used simultaneously as evaporators and as plating bath fume scrubbers. Atmospheric evaporators are considerably less expensive than vacuum evaporators. Typical atmospheric evaporator capital costs range from 2500 to 4000, while vacuum evaporator costs can be an order of magnitude or more higher. In atmospheric evaporator systems, however, vaporized water is not recovered, as it can be in vacuum systems. 

Spray-dryers are simpler and more compact than conventional wet scrubbers and have a lower capital and operating cost. Also, they do not produce large quantities of wastewater, and the spent absorbent is dry, thereby eliminating the need for thickening and filtration of the sludge. However, if the same dust precipitator is used for both the fly-ash and fhe spray-dryer product, the mixture of fly-ash and spent absorbent that they produce is unmarketable, and must be disposed of. Also, they require more expensive absorbents than conventional wet scrubbers. They are most suitable for retrofitting small plants that burn medium-sulfur coals, where capital costs and space restrictions are more of a consideration. ... 

Venturi scrubbers have lower capital cost than other types of scrubber because they are mechanically simple but they have a high energy consumption because of the need for pressurizing the gas to force it through the venturi. They also double as a fly-ash collection device, and so there is no need for separate scrubbers and fly-ash collectors when these units are used. " Because venturi scrubbers are cocurrent devices, with both the flue gas and absorbent traveling in the same direction, they cannot remove sulfur dioxide as completely as countercurrent devices, such as wet-scrubber towers, They also produce a wet mixture of... 

Presuming that the information quoted by the vendors is accurate, then scrubber system A is effectively consuming over 30 times the "power" that system B consumes to do the same job The results, presented in Table II, show clearly that the 55.1 kPa (8 psi) pressure drop reduces all other consumptions of available energy to insignificance. If additional compressor capacity must be purchased to cover this power drain, the added capital cost would be roughly... 

Under such circumstances, the scrubber/cyclone of vendor B is clearly the better choice. Since no additional compressor capacity would be required, the actual capital costs associated with vendor B are nearly 50% lower than for vendor A. Furthermore, vendor B s operating costs due to power consumption are almost negligible compared with vendor A s—lower by a factor of 45, when a typical compressor efficiency ( jj) is taken into account. 

For the venturi scrubber/cyclone comparison, evaluation of available energy consumptions revealed that the 55.1 kPa (8 psi) pressure drop of system A implied additional operating and capital costs which by far exceed its apparent cost savings over system B. This dramatic revelation proceeded from only a very few straightforward calculations. 

A thorough analysis of the capital and operating economics was made for the system described above. The basis for this estimate is shown in Table III, and relatively conservative assumptions have been made for the cost of the various utilities, maintenance, operating supplies, overhead, and capital charge rate. The analysis was based on designing the plant for the equivalent of 7000 hr/yr of full load operation. The capital costs, broken down into the gas interface loop and the regeneration system, are shown in Table IV. The cost for the scrubber loop and its asso-... 

Hydrogen peroxide technology has a high initial capital cost because of the need to have two scrubber vessels. The operating costs, initially high because of the cost of the reagent, may drop in the future as a result of either of the following events ... 

Alkaline absorption involves treating the tail gas with sodium hydroxide in a scrubber. After washing, concentrations of NOx as low as 200 ppmv in tail gas can be achieved. The byproduct of the washing process is a low concentration solution of sodium nitrite/nitrate that requires safe disposal or further use. The capital cost of the absorption process is 4.3% of the total investment cost of a dual-pressure nitric acid plant. 

Since most other processes for the utilization of tail gas have a scrubber system as an emergency backup, a bleach plant can sometimes be installed for little incremental capital. Costs then are associated more with storage and shipping systems than with the reaction process. 

Scrubber Water droplets injected into fine gas particles adhere to droplets which are then separated from the gas (typically by cyclones) Can achieve capture efficiencies of >99% [262] Low capital cost Can capture much smaller particles (sub-micrometre) than cyclone alone Useful for removal of hygroscopic or sticky particles and gas streams with high moisture contents Pumping cost can be significant, particularly for large flows Requires subsequent separation of particles from water... 

As methanol emissions continue to be monitored more closely, there are some methods of reducing the methanol in the deaerator vent. The vent stream could be condensed and sent to the reformer or the steam system. Catalytic combustion could be used to reduce the methanol. A scrubber system could be added to remove the methanol. In some instances a condensate stripper is added instead of the deaerator to remove the ammonia, methanol, and other contaminants from the condensate. This system recycles the vent stream to the reformer as process steam and the bottoms are mixed with the incoming boiler feedwater makeup. However, this system adds considerable capital cost to a project. 

Although the use of a plasma torch increases the global electticity cost, it reduces the electrical power required by the off-gas treatment system (exhaust fans, scrubbers, particulate filters) because the off-gas flow rate is much lower than with a burner. Indeed, there is about an 80% off-gas flow rate reduction when using a plasma torch instead of a burner. Not only does this reduce operating costs of the off-gas treatment system in existing plants, it also reduces the capital cost for future plants because a smaller and less complex off-gas treatment system can be purchased. 

The typical capital cost for a peat bed system in the UK is given as 550 per square meter of cross-section area, including associated fans, scrubber, and local ducting. At a flow rate of 125 m /hr m, this is about 4.50 per m /hr ( 7.65 per scfm) of capacity (Valentin, 1990). 

The immediate impact of the 1970 Act was to enforce FGD in a very short time scale (Kyte, 1989). Costs for the utilities have risen accordingly. The overall cost of all air pollution control in the UShas been estimated to exceed 35 billion each year (Edison Electric Institute, 1989), and air pollution costs can account for more than one-third of a new coal-fired power plant s cost. A single FGD system or scrubber may cost 100 million or more, and capital costs for adding scrubbers on older plants can equal or exceed the original plant investment. All this investment has obviously had an impact upon emissions. The ERA calculate that from the peak year of 1973, total SO2 emissions were down nearly 21 per cent by 1987, while... 

Some disadvantages of the fluidized beds are the complexity in operability, difficult separation of the fine catalyst particles from the exhaust gas (imposing significant capital costs for cyclones and oil scrubbers) and erosion problem due to the high linear velocities (Dry, 1996). Moreover, H2S contamination of the synthesis gas feed means complete deactivation. 

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