Vetrocoke process

Catacarb process An extraction process used to remove carbon dioxide from process gases by scrubbing the hot gases with potassium carbonate solution containing additives which increase the hydration rate of the gas in the solution. The Vetrocoke process is similar. See Benfield process. 

Three commercial processes that use these various hot carbonate flow arrangements are the promoted Benfield process, the Catacarb process, and the Giammarco-Vetrocoke process (26—29). Each uses an additive described as a promoter, activator, or catalyst, which increases the rates of absorption and desorption, improves removal efficiency, and reduces the energy requirement. The processes also use corrosion inhibitors, which aHow use of carbon—steel equipment. The Benfield and Catacarb processes do not specify additives. Vetrocoke uses boric acid, glycine, or arsenic trioxide, which is the most effective. 

Various processes attempt to improve on the basic potassium carbonate process by using activators to increase the rate of CO2 absorption such as the Catacarb, Benfield, and Giammarco—Vetrocoke processes. 

Vetrocoke process aqueous potassium carbonate-arsenious oxide as Benfield, also As203 is poison—about 50% of activity is lost when As = 0.5%... 

RENEWABLE ENERGY RESOURCES] (Vol 21) Giammarco-Vetrocoke process... 

Giammarco-Vetrocoke Process Potassium Carbonate with Arsenite... 

Hot carbonates are well suited for the removal of C02 at moderate or high levels in the presence of little or no H2S. The process acquired its name from the use of elevated temperatures in both the absorber and the regenerator (110—115°C). Hot carbonates such as the Benfield and the Koppers Vacuum Carbonate utilize K2C03 to remove H2S, COS, and C02 from gas streams [35]. Their heat requirements and high solvent circulation make hot carbonates more expensive than other acid gas removal processes. Other hot carbonate processes, including the Catacarb and the Giammarco-Vetrocoke processes, use catalysts, corrosion inhibitors, and/or activators to enhance the removal of the acid gases. Hot carbonate-promoted systems are able to decrease the C02 level from 1% to 0.1%. Promoters include DEA, amine borates, and hindered amines [36]. 

Another chemical solvent process that was frequently used is the Giam-marco-Vetrocoke process in which a mixture of aqueous solutions of an alkali metal carbonate, an alkali metal arsenite, and an arsenate is used as the absorption medium. When correct proportions of arsenite to arsenate and pH... 

The Giammarco Vetrocoke Process uses arsenate as an additive to the potash solution. A modified version of this process has become state of the art as an oxidative purification unit for selective removal of H2S. 

Hot Potassium Carbonate (Benfleld) Process, 334 Catacarb Process, 363 Flexsorb HP Process, 369 Giammarco-Vetrocoke Process, 371... 

The general mechanisms for the absorption of CO2 and H2S in alkaline solutions and the effects of activators on CO2 absorption are discussed in an earlier section of this chapter oiti-tled Absorption Mechanisms. The followiiig discussions are specific to the Giammarco-Vetrocoke processes. 

The reaction rate for the overall reaction 5-19 is determined by the sum of the rates of 5-17 and 5-18, where 5-18 represents the rate-controlling step. The Giammarco-Vetrocoke process uses a glycine activator, which increases the rate of absorption by providing an alternative reaction path for COj, forming glycine carbamate as shown by reaction 5-20 ... 

Arsenite Solutions. Addition of essentially stoichiometric proportions of arsenic trioxide to aqueous sodiiun or potassium carbonate solutions results in a marked increase in the rate of absorption and desorption of carbon dioxide, as compared with conventional carbonate solutions. Figure 5-31 illustrates this phenomenon by comparing, qualitatively, the rate of absorption of carbon dioxide at 1 atm partial pressure and room temperature in 40% potassium carbonate and in a typical solution used in the Giarrunarco-Vetrocoke process (Riesen-feld and Mullowney, 1959). The effects of the more rapid absorption and desorption are appreciable savings in regeneration heat, reduction in equipment size, and production of treated gas of higher purity than is possible with ordinary hot carbonate solutions. 

Hgure S-32. Giammarco-Vetrocoke process flow scheme with split-stream absorption and two-pressure-level regeneration. Giammarco-Vetnxoke,... 

The Thylox process is no longer used commercially, while the arsenic-based version of the Giammarco-Vetrocoke process is still supported by the licensor in countries where the use of arsenical solutions is permitted. A non-arsenic, evolutionary modification of the G-V process is currently being offered for CO2 removal, and is claimed to be very competitive. This form of the process can not be classified as a liquid redox process, and is discussed in Chapter 5. 

After washing, the sulfur contains about 0.3% arsenic (as arsenite and ihioarsenate) on a dry basis (Anon., I960A). In general, since the Giammarco-Vetrocoke process is used in applications where the H2S content of the gas is relatively low, the amount of sulfur produced is small, and the end product is a low purity washed sulfiir paste which must be stored for disposal. However, in a few cases it is economical to further process the paste in an autoclave, and to produce liquid or solid sulfur of relatively high quality. 

The treating solutions used in the Giammarco-Vetrocoke process vary over a considerable range of concentrations. For the H2S removal process, Jenett (1962) reports sodium or potassium carbonate concentrations ranging from 0.5 to 15%, presumably with corresponding concentrations of arsenic compounds. Typical operating data for the Giammarco-Vetrocoke process reported by Jenett (1962) are shown in Table 9-6. 

The Takahax process was developed by Hasebe (1970) of the Tokyo Gas Company Ltd., to replace the Thylox and Giammarco-Vetrocoke processes (Swaim, 1972). The first commercial application of the Takahax process was to desulfurize coal gas in a revamped 1.4 MMscfd Thylox plant operated by Kamaishi Gas. About a hundred Takahax units were in operation at one time in Japan, primarily in gas works, steel plants, and chemical plants. The process is still extensively used in Japan for the desulfurization of coke oven gas. 

Jenett, E., 1964, An Assessment of the Giammarco-Vetrocoke Process in U.S. Gas Treating Operations—Theory and Practice, Proceedings of the Gas Conditioning Conference, University of Oklahoma, Norman, OK. 

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