Experimental data of the aqueous NH3 and CO2 absorption at temperatures from 15 °C to 35 °C, NH3 concentrations from 5% to 15% and CO2 loadings from 0.2 to 0.6 measured with the Wetted Wall Column

The absorption between aqueous NH3 and CO2 is studied using the Wetted Wall Column in order to show the effect of the solvent condition on the rate of reaction. A total of 27 different cases are investigated in the region defined by temperatures from 15 °C to 35 °C, NH3 concentrations from 5% to 15% and CO2 loadings from 0.2 to 0.6. The paper reports the data measured during the experiments, the experimental apparatus description and the experimental procedure. The data here presented are both the raw data measured with their uncertainty and the final value of the overall mass transfer coefficient. The overall mass transfer coefficient is the result of the raw data treatment explained in the research paper related to this data. The data here reported are analyzed in the paper by Lillia et al. (2018) [1].


a b s t r a c t
The absorption between aqueous NH 3 and CO 2 is studied using the Wetted Wall Column in order to show the effect of the solvent condition on the rate of reaction. A total of 27 different cases are investigated in the region defined by temperatures from 15°C to 35°C, NH 3 concentrations from 5% to 15% and CO 2 loadings from 0.2 to 0.6. The paper reports the data measured during the experiments, the experimental apparatus description and the experimental procedure. The data here presented are both the raw data measured with their uncertainty and the final value of the overall mass transfer coefficient. The overall mass transfer coefficient is the result of the raw data treatment explained in the research paper related to this data. The data here reported are analyzed in the paper by Lillia et al. (2018) [1].
& The data are acquired by the Wetted Wall Column apparatus. The partial pressure of the CO 2 inside the reactor is measured considering the total pressure in the reactor with a pressure transducer (Rosmount 2088) and the CO 2 concentration with the CO 2 probe (VAISALA GMT 220). The CO 2 flow absorbed by the solvent in the reactor is measured considering the difference of the CO 2 concentration with the CO 2 probe (VAISALA GMT 220) before and after the reactor and the gas mole flow blown to the reactor.

Data format
Raw measurements with uncertainties and their analysis (the overall mass transfer coefficient).

Experimental factors
The solvent is prepared gravimetrically in terms of ammonia composition and CO 2 loading (defined as the rapport of CO 2 and NH 3 in the solvent).

Experimental features
A gas mixture of N 2 and CO 2 with a known composition flows in the Wetted Wall Column in contact with solvent with a known composition. The partial pressure of the CO 2 inside the reaction chamber and the CO 2 flux absorbed by the solvent are measured during the experiment for different compositions of gas and solvent. The result is the overall mass transfer coefficient which describes the dependence of the rate of absorption and the partial pressure of the CO 2 . Data source location

Value of the data
Enhance the number of analyzed cases for the CO 2 capture with ammonia solvents Raw data with their uncertainties provide information about the accuracy of the measures and the procedure used.
Raw data are treated to compute the overall mass transfer coefficient under the hypothesis explained by Lillia et al. [1]. Other researcher can model the phenomenon under other hypothesis and treat the raw data with different procedures and compare the K ov results found.
K ov value can be compared with other data in literature and new data measured in future works with the same method.

Data
The data provided by the paper are the Wetted Wall Column measurements for every case analyzed with the absolute uncertainty. The aim of the measurements is the calculation of the CO 2 flux absorbed by the solvent and the partial pressure of the CO 2 inside the Wetted Wall Column reactor. The data presented are the raw data measured by the Wetted Wall Column apparatus and their analysis following the procedure explained in the relative research article by [1]. The raw data treatment returns the overall mass transfer coefficient K ov [mol/(m 2 s Pa)] that correlates the difference of CO 2 partial pressure in the reaction chamber and the CO 2 flux absorbed by the solvent as defined in Eq. (1) where φ CO 2 [mol/(s m 2 )] is the total CO 2 molar flux absorbed, P gas CO 2 [Pa] is the partial pressure of carbon dioxide in the bulk gas and P liq CO 2 [Pa] the partial pressure of carbon dioxide in the bulk liquid. This constant identifies both the effect of the rate of reaction and the mass transfer of the CO 2 and it is usually reported in this kind of experimental work. Hence, also the value of the K ov is reported with its uncertainty.   Table 1 presents the instrument list. The Wetted Wall Column allows for counter-current contact between the liquid solvent and a defined gas mixture. CO 2 and N 2 are supplied by gas bottles with a molar purity of 99.995% and 99.996% respectively. The streams from the bottles are controlled by two Bronkhorst mass flow controllers which determine the composition of the inlet mixture in the chamber. The gas mixture passes through a pre-saturator at ambient temperature and a saturator immersed in a thermostatic bath at the temperature of the experiment. After the saturators, the gas mixture is saturated with water at the same temperature of the thermostatic bath. Between the reaction chamber and the CO 2 concentration probe (VAISALA CARBOCAP GMT 221) is positioned a condenser. The saturators and the condenser are necessary in order to have a known amount of water in the gas and consequently determine accurately the amount of CO 2 in the gas flow. Before the reaction chamber, in the gas line, there is a bypass valve. The valve allows to measure the carbon dioxide concentration before and after the absorption reactions switching the flow straight to the CO 2 probe or to the reaction chamber.

Wetted Wall Column (WWC) experimental apparatus
The thermostatic bath controls the temperature of the reaction chamber and the temperature of the inlet solvent in the reaction chamber. The solvent, prepared with a known NH 3 concentration and CO 2 loading is charged in a liquid reservoir of 0.7 dm 3 . A micro pump pushes the liquid with a controlled mass flow into the thermostatic bath and then into the reaction chamber. The reaction chamber consists of a glass tube in which a stainless steel tube is located (dimensions are reported in Fig. 1). The liquid, pushed inside the stainless steel tube, falls down in a thin film around the stainless steel tube. In this way the contact area between the liquid and the gas phase is well defined.
Based on the known contact area between the gas and the liquid, and the amount of CO 2 absorbed in the chamber, it is possible to determine the dependence between the CO 2 surface flux absorbed by the liquid and the CO 2 partial pressure in the gas mixture at a fixed temperature. A clear scheme of the plant layout is available in the Fig. 1 in the second paragraph of the article which describes the experimental data analysis [1].

Solvent preparation procedure
The solvent is identified by two numbers: (i) the ammonia concentration, defined as the initial weight of ammonia on the weight of water (wt. NH 3 /wt. H 2 O) and (ii) the CO 2 loading defined as the ratio between the CO 2 and the ammonia in the solution. The chemicals used to prepare the solutions are: deionized water, ammonia solution 28 wt% and ammonium bicarbonate NH 4 HCO 3 . The solvent is prepared gravimetrically with a balance with an accuracy of 0.01 g and a full scale of 1000 g. The ammonia concentration and the CO 2 loading is calculated considering the apparent concentration of H 2 O, NH 3 and CO 2 . Deionized water is considered pure H 2 O, ammonia solution is 28 wt% NH 3 and 72 wt% H 2 O, and one molecule of NH 4 HCO 3 is one molecule NH 3 plus one molecule H 2 O plus one molecule CO 2 .

Experimental procedure
The experimental procedure for measuring the overall mass transfer coefficient is described by the following points: