How can the conversion rate of conversion units be maximized?

First and foremost, it is essential to ensure the activity of the catalyst being used; if the catalyst has high activity. Increase the temperature of the temperature adjustment shift; however, the temperature of the low-temperature shift should not be raised too much, as it would affect the equilibrium shift rate. By appropriately increasing the water-to-carbon ratio, the possibility of raising pressure is generally not very high, as pressure is influenced by the load; once the load is set, the pressure remains more or less constant

Main factors affecting the carbon monoxide conversion reaction 1. The effect of temperature on the carbon monoxide conversion reaction. The carbon monoxide conversion reaction is a reversible exothermic reaction; therefore, an increase in temperature is unfavorable for the reaction equilibrium. In other words, the equilibrium conversion rate of carbon monoxide decreases as temperature rises. However, within the active range of the catalyst, increasing the temperature can accelerate the reaction rate. Under the same gas composition and gas-to-solid ratio conditions, selecting an appropriate temperature that facilitates both an increase in the equilibrium conversion rate of CO and an acceleration of the reaction rate enables optimal reaction results and the most efficient use of catalyst. The lower the active temperature of the catalyst, the higher the equilibrium conversion rate of CO under the same conditions, meaning the lower the CO content in the converted gas. In other words, when the same CO conversion rate is achieved, a catalyst with lower activity can maintain a lower steam-to-gas ratio, thereby saving steam usage. 2. Effect of steam-to-gas ratio on the CO shift reaction. The steam-to-gas ratio refers to the volume ratio of water vapor to CO in the coal gas entering the shift reactor. (It can also be expressed as the volume ratio of water vapor to dry semi-water gas.) The gas ratio has a significant impact on the CO conversion rate. The equilibrium CO conversion rate increases as the steam-to-gas ratio rises; however, this increase occurs at a faster rate initially and then slows down. That is, when the steam-to-gas ratio is low, the slope of the CO conversion rate curve is quite steep. As the steam-to-gas ratio continues to rise, the slope of the curve gradually decreases. Eventually, when the steam-to-gas ratio reaches a certain value, the equilibrium CO conversion rate curve becomes increasingly flat. The effect of gas-to-vapor ratio on reaction rate. Generally, when the vapor-to-gas ratio is low, the reaction rate increases rapidly as this ratio rises; thereafter, it gradually decreases as the ratio continues to increase, a pattern similar to that of the effect of the vapor-to-gas ratio on the equilibrium conversion rate of CO. Therefore, at lower steam-to-gas ratios, appropriately increasing the steam-to-gas ratio is beneficial for improving both the CO conversion rate and the reaction rate; however, an excessively high steam-to-gas ratio is not economically viable. 3. Effect of pressure on the CO conversion reaction The CO conversion reaction is an equimolar reaction, and the total volume of the gases remains unchanged before and after the reaction; therefore, pressure has no effect on the reaction equilibrium. Pressurization is applied during the transformation process, with the aim of ； It increases the reaction rate of CO, improves the thermal efficiency of the system and reduces power consumption; meanwhile, the higher pressure results in a smaller footprint for the equipment and a more compact design. Studies show that stress significantly increases the activity of catalysts, accelerating the reaction rate. In other words, since the reaction rate increases under pressure, less catalyst is required compared to normal-pressure shift at the same scale. 4. Effect of space velocity on the CO conversion reaction. Space velocity is abbreviated as “SV”. It refers to the standard volume of gas passing through a unit volume of catalyst per unit time, with the unit being m3(std)/ or abbreviated as h-1. The magnitude of the space velocity determines both the production capacity of the catalyst and the conversion rate. If the space velocity is too low, there is little reaction heat generated; consequently, the temperature of the catalyst bed drops and the conversion rate decreases. If the space velocity is too high, the gas has little time to come into contact with the catalyst; it leaves the catalyst bed before a reaction can occur, resulting in a decrease in the conversion rate. The space velocity is related to the type of catalyst; different types of catalysts determine different space velocities. The B116 catalyst used in our company’s medium-pressure reactors can operate at a space velocity of 250–1000 h-1, while the B303Q catalyst used in low-pressure reactors can operate at a space velocity of 1500–300 h-1. The magnitude of the catalyst space velocity is also related to the activity of the catalyst. The catalyst has good activity and fast reaction speed, allowing for a higher space velocity to be used. The catalyst has poor activity and the reaction rate is slow, so the space velocity must be reduced.

1. The conversion reaction of carbon monoxide is an exothermic reaction, and its chemical equation is: CO + H2O == CO2 + H2 + Q. The conversion of carbon monoxide is an exothermic, isovolumetric reversible reaction. From the perspective of chemical equilibrium, lowering the reaction temperature, increasing the amount of steam, and removing carbon dioxide can shift the chemical equilibrium to the right, thereby improving the carbon monoxide conversion rate ； In terms of reaction rate, increasing the reaction temperature facilitates an increase in the speed of chemical reactions. Under certain conditions, CO can undergo the following side reactions: CO + H2 → C + H2O; CO + 3H2 → CH4 + H2O; CO2 + 4H2 → CH4 + 2H2O. All of these side reactions are exothermic, and their occurrence is detrimental to the proper progress of the conversion process. Since these side reactions are all exothermic and involve volume reduction, low temperature and high pressure facilitate their occurrence. During normal operation of the shift reaction, increasing the reaction temperature or using a catalyst with good selectivity for the shift reaction can prevent or reduce the occurrence of side reactions. The following further explains the effects of temperature, pressure, vapor-to-gas ratio, etc., on the conversion reaction. 2. Temperature: Temperature has a significant effect on the chemical reaction rate of transformation reactions; moreover, its effect on the forward and reverse reaction rates is different. As the temperature rises, the rate of the exothermic reaction, i.e., the shift reaction, increases slowly, while the rate of the reverse reaction (endothermic reaction) increases rapidly. At the same time, the conversion rate of carbon monoxide decreases as the temperature rises. Therefore, when the shift reaction begins, the concentration of reactants is high; raising the temperature can accelerate the reaction rate. At the end stage of the reaction, the reaction temperature must be lowered to slow down the rate of the reverse reaction; this allows for a higher conversion rate to be achieved. At the same time, the determination of the reaction temperature is also related to factors such as the gas-to-vapor ratio, gas composition, catalyst activity, and temperature range. 3. Pressure: The volume of the gas remains unchanged before and after the transformation reaction; therefore, increasing the pressure does not alter the equilibrium state of the reaction. However, an increase in pressure raises the concentration of the reactants, facilitating molecular interactions. It also increases the utilization rate of the catalyst’s internal surface as well as the contact time between the gas and the catalyst. As a result, the space velocity increases with rising pressure, thereby enhancing the production efficiency of the catalyst. Under pressure, CO can undergo some side reactions; meanwhile, due to limitations related to the material of the equipment and the strength of the catalyst, the pressure should not be increased too much. 4. Steam-to-gas ratio: In production, the volume ratio of water vapor to dry water gas is commonly used as the steam-to-gas ratio. The gas-to-solid ratio has a significant impact on the conversion rate of carbon monoxide; the equilibrium conversion rate increases as the gas-to-solid ratio rises, but this increase is initially rapid before slowing down. When the gas-to-solid ratio reaches a certain value, the equilibrium conversion rate curve gradually levels off. The effect of the gas-to-vapor ratio on reaction rate is such that, at relatively low gas-to-vapor ratios, the reaction rate increases rapidly as this ratio rises; thereafter, it gradually slows down as the ratio continues to increase. An appropriate increase in the gas-to-vapor ratio is beneficial for improving both the conversion rate of carbon monoxide and the reaction rate. However, an excessively high gas-to-vapor ratio is not economical and can lead to desulfidation reactions of the catalyst. Furthermore, the transformation reaction is closely related to the activity of the catalyst.

In typical reactions, the reaction conversion rate is increased by increasing the amount of reactants, raising the inlet temperature, and increasing the inlet pressure. It’s just that when considering the balance of effects, an appropriate temperature and pressure need to be selected.