Designing a water gas shift reactor

In this report, design the water gas reactor to find the optimal dimensions, height, and diameter, catalyst amount, and heat exchange strategy of a reactor. The reactors are also known as the (WGSR) “water gas shift reactor” is converted a carbon monoxide to present the syngas in the form of the carbon dioxide along with more hydrogen is generated. In the hydrogen generation process, the WGSR is the intermediate step, which is dependable for about 95% hydrogen generated. (Barbosa Lima & et.al, 2012)

Figure 1: Process Block Diagram Generation of Hydrogen Unit

By the use of guard bed, prevent the catalyst poisoning as well as deactivation when sulfur is removed from hydrocarbon. (SRR)  is stand for Steam Reform Reactor is the multi-tubular catalyst packed the furnace reactor. A reaction of the WGR is; 

It provides the techniques of the extracting energy from a toxic CO through convert it into the usable   plus with the. This reaction is depend on the activity of the catalyst for the various metals which is based on the catalyst involving the  The mathematical model for the WGSR is most beneficial in the study of the concentration profile plus the Temperature profile. The WGSR is the heterogeneous reaction (solid/gas), in this reaction two options are used, HTS “High Temperature Shift” this reactor catalyst is based with series of HTS by the LTS “Low Temperature Shift” in inter-cooling stage. 

Figure 2: Reactor Set-Up Block diagram

The design equation of the reactor is all fixed in the Bed catalytic to assumed as behave like ideal for the plug floe reactor, design and sizing the reactor below equation is used,

A WGR produces a reaction that is both lethal and non-poisonous for the general public consumption. The reaction is ideal for the creation of hydrogen gas and carbon dioxide while separating other aspects such as carbon dioxide from the hydrogen. Scientifically speaking, water gas shift reaction is limited equilibrium reaction usually conducted at high temperatures and kinetically below 250⁰C.

The design specification for the reactors set up is shown as below, first of all, presents the Feed compositions; (Water Gas Shift Reactor, 2018)

The design specification for the catalyst prosperities is explained as below table;

The equation below shows the reaction of carbon monoxide with water vapor to form hydrogen gas as well as carbon dioxide.

The whole idea of a WGSR is to provide ideal conditions for the reaction of carbon (II) oxide and water vapor to create carbon (IV) oxide and hydrogen gas. The mixture of the hydrogen and the carbon (II) oxide is referred to as water gas. The water-gas shift reactor was first invented by Felice Montana, an Italian physicist when it came a time that the world was in dire need of a less expensive and more effective way of producing hydrogen gas. The gas was used in the industrial development of ammonia gas and fertilizer through the Haber-Bosch process.

The expression of the empirical rate is explained a WGSR in the ferrochrome catalyst in a power law;

Whereas;

R is reaction rate; Ea is the activation energy;  is the pre exponential factor;   is the reaction equilibrium constant, the estimated parameters are I, m, q, n and the  partial pressure or component, R is the universal gases constant as well as T is absolute temperature.

The condition and the catalyst which are used in the WGSR are also explained;

A catalyst is anything that speeds up a reaction without changing the outcome or the products.This section will highlight the necessary catalysts used for water gas shift reaction and their respective condition for optimum performance.

Copper oxide – This catalyst works best in low-temperature conversions. This includes temperatures of between 200-250^oC. If the catalyst exceeds the upper-temperature limit, it will be susceptible to thermal sintering. (R.Burch, 2006) Also, they operate at a general pressure of 10-30 atm.

Iron oxide – iron oxide operates at a temperature range of between 310 – 450^oC. The exothermic nature of the reaction is the cause of the long temperature stretch. The inlet temperature is 350^oC to prevent the temperature from going above 550^oC. Iron oxide operates at an atmospheric pressure of 82.7 atm.

Chromium oxide – Chromium acts as a preventive measure that stabilizes iron oxide and inhibits sintering. Chromium also operates at the temperature and pressure as Iron oxide.

Zinc oxide- Zinc Oxide is used in low-temperature conditions to offer structural support and also prevent sulfur from poisoning the copper. It operates under the optimal conditions of temperature and pressure as copper oxide above.

Alumina – Aluminum (III) Oxide prevents dispersion and pellet shrinkage. It also operates the low temperatures of between 200-250^oC and at a pressure of 10-30 atm.

WGSR is the significant fuel processing reaction on behalf of to obtain the hydrogen in the reformed mixture of gases.The space velocity, temperature, concentration profile, by the reactor of WGS reactions. To produce the hydrogen form the synthesis of gas, that comprises the CO as well as  . WGSR helps in a manufacturing of hydrogen and it doesn’t involve even small traces of oxygen because it can make reaction fail. Explosion can take place if oxygen combines with reaction, along with this oxygen is very corrosive.

To make sure that oxygen doesn’t combine with the products and tries to be a part of the reaction, one should be very careful while this reaction takes place. The adiabatic process is one that does not involve heat transfer between the system and the surrounding. Hence, the work done will drive change in state properties such as pressure, temperature, volume, and internal energy. All these aspects will vary in an adiabatic process

Adiabatic water shift reactors are used since the work done by the system is zero. The net internal energy of the system is zero since there is no external pressure that the gases can expand against. This results in less energy being used to run the reactors as no work is needed. The adiabatic water shift reactor is one that does not allow heat to enter or leave its system. This results in the system gaining or losing heat after a certain period since no heat is lost to nor gained from the surrounding. (Varigonda, 2004)

Both high temperature as well as low temperature is used as catalysts in a water gas shift reaction. In fact, the temperature has been known to work as a better catalyst compared to chemicals such as nickel since temperature does not react further at any condition, with the reactants.

The low the temperature, the slow the reaction, the more hydrogen is produced. Also, with high temperature, the reaction rate may increase, but the conversion of the reactants will not be effective to obtain maximum output. Another reason is that low temperature favors exothermic reversible reaction, which favors the conversion of carbon monoxide at low temperatures.

References

Barbosa Lima, F. D., & et al. (2012). Modeling and Simulation of WaterGas Shift Reactor: An Industrial Case. INTECH, 52-74.

Morabiya, P. Y., & et al. (2012). Modeling & Simulation of Water Gas Shift Reaction. International Journal of Scientific Engineering and Technology, 1 (3), 106-110.

R.Burch. (2006). Gold catalysts for pure hydrogen production in the water–gas shift reaction: activity, structure and reaction mechanism. Physical Chemistry Chemical Physics, 8 (47).

Varigonda, S. (2004, July 30). Multivariable Control Design for the Water Gas Shift Reactor in a Fuel Processor. Proceeding of the 2004 American Control Conference.

Water Gas Shift Reactor. (2018, September 28). Water Gas Shift Reactor Design. Retrieved from https://www.slideshare.net/l16cn/water-gas-shift-reactor-design