Recycle gas, composition

The module OUTPUT generates a report (Tables XIV-XVII) summarizing input data, reactor operating conditions, product yields, properties of liquid products, recycle gas composition, and hydrogen production. Also, temperature and composition profiles are generated. 

A combination of coal beneficiation and relatively high-temperature roasting of the char is required for production of low-sulfur char from high-sulfur coal. When an equilibrium recycle gas composition (at about 70 psi H2) is used, char must be roasted at about 1400°F for periods of about 1 hr, as in the U.S. Steel Clean Coke process. Alternatively, the use of low-sulfur coal permits production of low-sulfur char under a wider range of hydrocarbonization conditions so that higher liquid yields, for example, may be obtained. 

Adjust the hydrogen makeup flow rate Fg. From eq. (25.3) of Table 25.2 we can see that Fa depends on yH2 (i.e., the value of the recycled gas composition in hydrogen), which must be maintained at 0.4 (see the assumptions resulting from process optimization in Table 25.1). Therefore, we can use a feedback controller which measures the hydrogen composition in the recycled gas and adjusts Fg in order to maintain yH2 = 0.4. 

Table Y.2 is the recycle matrix. (Feed + recycle) gas composition values are manually entered into cells AE3, AG3, AI3, AK3, and AL3. (Feed +recycle) gas quantities are...

Table Y.2 Matrix for determining intercept (i.e., exit gas) temperature when 20% of Fig. Y.l s exit gas is recycled to the Fig. Y.l feed gas stream, 660 K. The combined (feed + recycle) gas quantities are described in Section Y.2. The combined (feed+recycle) gas composition is described in Section Y.2.1. The intercept (exit gas) temperature is 890 K. This is not the steady-state 20% recycle exit gas temperature. The calculation now has to be repeated with recycle of 20% of the recycle matrix s output quantities substituted until two successive calculations give the same result. A Visual Basic program using... 

The feed to the arc consists of a mixture of fresh hydrocarbons and recycle gas. Table 6 indicates the composition of a typical feedstock as well as the composition of the gas leaving the arc furnace. 

The number of beds in series is an independent variable in the process design of such a system. It can be shown by analysis that the volume of recycle gas decreases almost in proportion to the increase in number of beds. Offsetting the reduction in recycle volume is the pressure drop across the system. Theoretical recycle power requirements then decrease somewhat as the number of beds increases. This is plotted in Figure 13 where it is assumed that (a) the make-up gas contains three moles H2 to one mole CO (b) the outlet gas composition corresponds to the equilibrium for Reactions 1, 2, and 3 (c) the recycle gas has the same composition as the outlet gas (d) inlet and outlet gas temperatures are 260°... 

Tn the synthesis of methane from carbon monoxide and hydrogen, it is desired to operate the reactor or reactors in such a way as to avoid carbon deposition on catalyst surfaces and to produce high quality product gas. Since gas compositions entering the reactor may vary considerably because of the use of diluents and recycle gas in a technical operation, it is desirable to estimate the effects of initial gas composition on the subsequent operation. Pressure and temperature are additional variables. 

The catalysts were reduced with 100% H2 at 371 °C and an inlet space velocity of 1000/hr. Because of the carbon-forming potential of a dry gas recycle composition and the cost of reheating the recycle if the water produced by the methanation reaction is removed, a wet gas recycle composition was used. The catalyst loading, gas composition, and test conditions for these tests are listed in Table II, and the effects of nickel content are compared in Table III. 

Effects of Cold Gas Recycle and Approach to Equilibrium. Product gases resulting from various CGR ratios were analyzed (Table XI). For the experiments tabulated, a decrease in the cold recycle ratio resulted consistently in increases in the product gas concentrations of water vapor, hydrogen, and carbon dioxide and a decrease in methane concentration. These trends may be noted in experiment HGR-12 as the CGR ratio decreased from 8.7 1 to 1.2 1, in experiment HGR-13 as it increased from 1.0 1 to 9.1 1, and in experiment HGR-14 as it decreased from 3.0 1 to 1.0 1. These trends indicate that the water-gas shift reaction (CO + H20 —> C02 + H2) was sustained to some degree. Except for the 462-hr period in experiment HGR-14, the apparent mass action constants for the water-gas shift reaction (based on the product gas compositions in Table XI) remained fairly constant at 0.57-1.6. These values are much lower than the value of 11.7 for equilibrium conversion at 400°C. In... 

The schematic diagram of the experimental setup is shown in Fig. 2 and the experimental conditions are shown in Table 2. Each gas was controlled its flow rate by a mass flow controller and supplied to the module at a pressure sli tly higher than the atmospheric pressure. Absorbent solution was suppUed to the module by a circulation pump. A small amount of absorbent solution, which did not permeate the membrane, overflowed and then it was introduced to the upper part of the permeate side. Permeation and returning liquid fell down to the reservoir and it was recycled to the feed side. The dry gas through condenser was discharged from the vacuum pump, and its flow rate was measured by a digital soap-film flow meter. The gas composition was determined by a gas chromatograph (Yanaco, GC-2800, column Porapak Q for CO2 and (N2+O2) analysis, and molecular sieve 5A for N2 and O2 analysis). The performance of the module was calculated by the same procedure reported in our previous paper [1]. 

It is well established that sulfur compounds even in low parts per million concentrations in fuel gas are detrimental to MCFCs. The principal sulfur compound that has an adverse effect on cell performance is H2S. A nickel anode at anodic potentials reacts with H2S to form nickel sulfide. Chemisorption on Ni surfaces occurs, which can block active electrochemical sites. The tolerance of MCFCs to sulfur compounds is strongly dependent on temperature, pressure, gas composition, cell components, and system operation (i.e., recycle, venting, and gas cleanup). Nickel anode at anodic potentials reacts with H2S to form nickel sulfide. Moreover, oxidation of H2S in a combustion reaction, when recycling system is used, causes subsequent reaction with carbonate ions in the electrolyte [1]. Some researchers have tried to overcome this problem with additional device such as sulfur removal reactor. If the anode itself has a high tolerance to sulfur, the additional device is not required, hence, cutting the capital cost for MCFC plant. To enhance the anode performance on sulfur tolerance, ceria coating on anode is proposed. The main reason is that ceria can react with H2S [2,3] to protect Ni anode. 

In 2004, a 50 kg coal per day continuous run facility was built to confirm reactor (fluidized bed) operating condition, feeding method, product gas composition, sorbent recycle, etc.18... 

Five product gas storage tanks having three functions are employed. The first tank entered is fortesting the product gas composition. Compounds indicative of the level of destruction are measured with a gas chromatograph hydrogen, methane, carbon dioxide, and carbon monoxide are also measured. If these tests are unsatisfactory, the gas is sent to a backup storage tank for recycle to the TRBPs or preheater. If the tests are... 

The module FLASH simulates the reformer flash separator by using a modified Chao-Seader method. The necessary constants for the Chao-Seader correlation have been developed for the lumped components. The output from this module determines the liquid yield and the composition of recycle gas. 

The composition of the synthesis gas, particularly the concentrations of hydrogen, carbon monoxide, and carbon dioxide, affects the atmosphere throughout the reactor directly, and also indirectly by its effect on the composition of the recycle gas. Synthesis gas, prepared by partial combustion of methane or some less hydrogen-rich carbonaceous material, lacks sufficient hydrogen for the conversion of all the carbon monoxide to hydrocarbons, and in this sense the synthesis gas is deficient in hydrogen. Stoichiometrically methane has sufficient hydrogen to convert all its carbon to olefins by the two-step process ... 

In the manufacture of methyl chloride a mixture of methane and chlorine is mixed with recycled gas and fed into a reactor. The CH4 Cl2 ratio is 4-5. The reactor temperature is maintained by regulating the gas feed rate. In methane chlorination plants, 95-96% chlorine yields and 90-92% methane yields are typical.176 All four chloromethanes are formed with a typical composition of 35 wt% methyl chloride, 45 wt% methylene dichloride, 20 wt% chloroform, and a small amount of carbon tetrachloride.178 The reaction, however, may be regulated so that either mono- or tetrachlorination predominates.177 179 180... 

There are two nested loops in the program (see Figure 5) o Composition of the recycle gas o Octane number of the C5+ reformate... 

In the inner loop, the composition of the hydrogen recycle gas is determined by successive substitution. If a target reformate octane is specified, an outer loop adjusts the inlet temperatures to all the reactors by equal increments until the target is reached. 

Step 7. Purge flow controls the composition in the recycle gas stream. The fresh feed F, controls the composition vA in the recycle gas stream. 

CH, 0 Purge stream 0 Composition control of recycle gas loop... 

---