The characterization and removal of foam promoting impurities from blended methyldiethanolamine - piperazine solution using membrane

The removal of acid gases from natural gas stream is an important process in many gas processing plants and for environmental protection. The most widely used acid gas removal technology nowadays is the absorption process using amine-based solvent. Foaming is the major cause that leads operational problems, resulting in excessive solvent losses, failure to meet treated gas specification and a reduction in gas treating capacity. Therefore, the main objectives of this research were to study the foam characteristics and the surface tension phenomenon of alkanolamines solution and to reduce their foaming promoters. The effect of natural gas impurities (foam promoters) in the blended methyldiethanolamine (MDEA)-piperazine solution such as hydrocarbon liquids, iron sulfide (dissolved solid), sodium chloride (salt), acetic acid (organic acid), methanol (hydrate inhibitor) and glycol (dehydrating agent) were investigated. The concentration of MDEA was found to significantly influence the foam activity in the solution. Iron sulfide, hydrocarbon and sodium chloride present in the solution had been identified as the impurities which apparently contributed to the high foaming tendency. At 5000 ppm concentration of impurities, the foam height achieved was 425 ml. Iron sulfide appeared to be the major foam promoter in the range of concentration solutions studied. Response surface methodology and central composite design had been applied to optimize the three factors that affected the foaming phenomenon. These factors were then correlated to the surface tension and foaming tendency. Asymmetric mixed matrix membrane (MMM) was applied to remove foam promoters in the amine solvent in order to reduce its foaming tendency. The MMM characteristics and performance were tested using scanning electron microscope, differential scanning calorimetry, Fourier transform infrared and membrane filtration tests. The contents of iron sulfide, hydrocarbon and sodium chloride as the main foam promoters had been successfully reduced as indicated by reduction of surface tension values by 12 %, 6.3% and 16 % respectively. These results indicated that membrane is a promising and viable technology to enhance the effectiveness of gas treatment system through the reduction of foam formatio

Carbon capture from natural gas combined cycle power plants: Solvent performance comparison at an industrial scale

Natural gas is an important source of energy. This article addresses the problem of integrating an existing natural gas combined cycle (NGCC) power plant with a carbon capture process using various solvents. The power plant and capture process have mutual interactions in terms of the flue gas flow rate and composition vs. the extracted steam required for solvent regeneration. Therefore, evaluating solvent performance at a single (nominal) operating point is not indicative and solvent performance should be considered subject to the overall process operability and over a wide range of operating conditions. In the present research, a novel optimization framework was developed in which design and operation of the capture process are optimized simultaneously and their interactions with the upstream power plant are fully captured. The developed framework was applied for solvent comparison which demonstrated that GCCmax, a newly developed solvent, features superior performances compared to the monoethanolamine baseline solvent

Optimization of High Content Sour Gas Treating Unit using Amine Solution

The removal of sour gas or acid gas such as hydrogen sulfide ,carbon dioxide and carbonyl sulfide from gas and liquid hydrocarbon streams always know as sweetening process is a vital process used for natural gas treatment. Although there is already an established treatment process widely used in industry since 1960’s to 70’s which is known as amine treatment this process is still becoming an issue for improvement. The purpose of this paper is to further research on the removal of high content sour gas by using the established amine treatment. With the used of HYSYS simulator this project will involve the development of the conventional amine treatment units, the evaluation on the efficiency of the treatment unit, and the analysis on the best parameter and specifications in both plant operation and amine solutions for maximum efficiency of CO2 removal. From the study, it is shown that the performance of acid gas removal can be increased and advantageous by increasing the amine concentration if and only if the concentration does not exceed the corrosion limits apart from increasing the contactor pressure. MEA shows the best performance in acid gas removal followed by DEA and MDEA solvent. In improving the single amine performance, mixtures of amines is identified to be one of the best alternatives in increasing CO2 absorption by using DEA/MDEA mixture

Process Optimization and Parameter Estimation in Pilot Plant Experiments via Bayesian Theorem for the CO2 Capture Process with a New Water Lean Amine Solvent

학위논문(박사)--서울대학교 대학원 :공과대학 화학생물공학부,2019. 8. 이윤우.The development of new amine solvents without the major drawbacks of conventional amines is crucial to industrial applications of CO2 capture. This paper presents a water-lean CO2 capture solvent having a low regeneration energy and low degradation. The water-lean solvent, K2Sol, is a sterically hindered diamine; because of the hindered amine site, K2Sol easily forms bicarbonate, resulting in a high absorption capacity. The minimum solvent regeneration energy is obtained using Gaussian process Bayesian optimization (GPBO) and bench-scale pilot plant experiments. GPBO finds the optimal solution using the input and output relationship of experiments; thus, expensive first-principle model construction can be avoided. According to the pilot plant experiment, the optimal regeneration energies of monoethanolamine (MEA) and K2Sol are 4.3 and 2.8 GJ/t CO2, respectively, indicating that K2Sol requires only 65% of the regeneration energy of MEA. Fewer than 30 experiments are required to find the optimal pilot plant operation for both the MEA and K2Sol experiments. The superior properties of K2Sol in terms of the CO2 loading, cyclic capacity, regeneration temperature, and degradation is also presented. Additionally, Bayesian parameter estimation is implemented for the absorber model with K2Sol, for the process design and the configuration optimization using a commercial process simulator. According to various assumptions, parameter candidates to be used in GSA is selected. The subset including 8 physiochemical parameters served as input variables of the surrogate model. Due to non-linearity of the full model, the surrogate model can not reflect the responses of the full model. The trade-off between the inaccuracy of the surrogate model and the high computation costs of the full model was solved by applying the hybrid model in the final sampling of MCMC. From the parameters posterior distribution, it is presented that a standard Gibbs free energy of HK2Sol+ is the most influenceable parameter at the full model and both forward reactions are near equally dominant. Most output responses of a full model with estimated parameters were also located in 95% confidence interval.습식 아민을 이용한 이산화탄소 포집 공정의 상용화를 위해서는 높은 재생 에너지를 비롯한 기존 아민 용매의 단점을 극복한 신 용매의 개발이 필수적이다. 본 연구에서는 이러한 단점을 극복한 신 저수계 아민 용매, K2Sol, 을 제안한다. K2Sol은 입체장애 구조를 가지는 디아민으로 구성되어 있으며, 아민 사이트의 장애구조로 인해 중탄산염을 쉽게 만들어 내며, 이로 부터 높은 흡수 용량을 가질 것으로 기대된다. 실험실 규모의 테스트를 통해 K2Sol의 이산화탄소 흡수능력, 열 용량, 열화내구성, 이산화탄소 흡수능에 따른 점도 등을 측정하였고, 이를 30wt% MEA의 성능과 비교하여 이산화탄소 포집 공정의 용매로서 우월한 성능을 가짐을 입증하였다. 이후 실험실 규모의 테스트 결과로부터, 이산화탄소 포집 공정에서 K2Sol의 성능을 검증하기 위해 최적 재생 에너지를 측정하기 위한 파일럿 스케일의 실험을 시행하였다. 파일럿 스케일의 실험의 비용과 시간 소모를 최소화하기 위해 해당 실험에 가우시안 프로세스 베이지안 최적화 기법 (GPBO) 을 적용하여 최저의 재생에너지를 찾는 최적 운전 조건을 찾았다. GPBO는 공정의 제일원리 모델 (First principle model) 없이 실험의 입력변수와 출력반응의 관계를 통해 근사 수학 모델을 만들어 최적해를 찾는다. 적은 횟수의 평가로 블랙박스 모델의 국부 최적값을 찾는데 용이하기 때문에, 파일럿 스케일 실험과 같은 높은 비용의 실험에 적절하다. 파일럿 플랜트 실험 결과 30wt% MEA의 최적 재생에너지가 4.3 GJ/t CO2, K2Sol의 최적 재생에너지가 2.8 GJ/t CO2로 MEA 대비 65% 수준의 낮은 재생에너지를 보였다. GPBO를 통해 최적 운전조건을 찾는데 각각 30회가 안되는 실험이 수행되었다. 또한 K2Sol을 이용한 이산화탄소 포집공정의 리보일러의 온도가 물의 끓는 점보다 낮은 것으로부터 낮은 수준의 열량으로 운전이 가능하므로 30wt% MEA 대비 경제적임을 입증했다. 마지막으로 파일럿 스케일 실험의 데이터만으로 상용 시뮬레이터를 이용한 공정 모델을 개발하기 위해 전역 민감도 분석과 베이지안 매개변수 추정법을 K2Sol을 이용한 흡수탑 모델에 적용하였다. 몇 가지의 가정을 통해, K2Sol의 순물질 매개변수를 group contribution method를 통해 추정하였고, K2Sol와 이산화탄소의 반응은 termolecular reaction mechanism으로 가정하였다. 이로부터 남은 16개의 파라메터를 이용하여 전역 민감도 분석을 시행하였고, 흡수탑 모델의 출력반응에 기여를 제일 많이 하는 8개의 파라메터를 선정하였다. 이 8개의 파라메터를 입력 변수로 하는 수학대리모델을 잔여학습기법을 기반으로 한 딥러닝 기법을 통해 개발하고, 개발된 수학대리모델과 기존 ASPEN Plus 모델을 기반으로 한 하이브리드 모델을 이용하여 베이지안 매개변수 추정법을 적용하였다. 그 결과, K2Sol 수용액의 양이온의 형성 깁스 에너지가 가장 큰 영향을 주는 파라메터이며, 각 정반응에서 K2Sol과 물이 동시에 지배적인 염기로 작용한다는 것을 보였다. 또 한 추정된 파라메터가 도입된 모델은 대부분의 실험의 출력을 95% 신뢰영역에서 만족함을 보였다.Chapter 1 Introduction 1 1.1 Research Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Research Objectives . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.3 Outline of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . 8 Chapter 2 Performance of A New Water Lean Amine Solvent Compared to MEA in Lab-Scale Experiments 9 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2 Experimental Section . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.3 Result and Discussion . . . . . . . . . . . . . . . . . . . . . . . . 14 2.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Chapter 3 Process Optimization of Pilot Scale Experiments for Post Combustion CO2 Capture Process with A New Water Lean Amine Solvent 29 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.2 Pilot-Scale Experimental Setup . . . . . . . . . . . . . . . . . . . 31 3.3 Optimization Methodology . . . . . . . . . . . . . . . . . . . . . 37 3.3.1 Gaussian process Bayesian optimization . . . . . . . . . . 38 3.3.2 Performance test of optimization method . . . . . . . . . 40 3.4 Result and Discussion . . . . . . . . . . . . . . . . . . . . . . . . 44 3.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Chapter 4 Bayesian Parameter Estimation for the CO2 Capture Process with A New Water Lean Amine Solvent 57 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 4.2 Model Description . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.3 Bayesian Inference using Surrogate Models and Hybrid Models . 70 4.3.1 Parameter subset selection using global sensitivity analysis 70 4.3.2 Posterior inference with surrogate models and hybrid models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 4.3.3 Deep neural network surrogate model methods . . . . . . 76 4.4 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . 79 4.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Chapter 5 Concluding Remarks 110 Appendix A Information of diamine 113 Appendix B Details of approximation spectral sampling 114 초록 127 감사의 글 129Docto

OPTIMIZATION OF A COMBINED APPROACH FOR THE TREATMENT OF DESALINATION REJECT BRINE AND CAPTURE OF CO₂

Carbon dioxide (CO₂) is the most widespread greenhouse gas that traps heat and raises the global temperature, contributing to climate change. Existing techniques to sequester carbon dioxide have numerous environmental concerns and usually require an extensive amount of energy. New technologies and methods, such as reactions with desalination reject brine according to the Solvay process, offer new hope for the reduction of carbon dioxide concentration in the atmosphere. Brine management is another environmental concern, as many desalination plants need to find suitable approaches for the treatment or disposal of the large amounts of concentrated brine, resulting from the desalination processes. Many conventional methods are used such as disposal through deep good injection, land disposal, and evaporation ponds. However, these methods still suffer from many drawbacks. An alternative approach is to further process the brine to extract all the salts through reactions with carbon dioxide. This has the advantages of being environmentally friendly and can produce valuable carbonate chemicals. The present work evaluates the Solvay process where carbon dioxide is passed into ammoniated brine and reacts with sodium chloride to form a precipitate of sodium bicarbonate and soluble ammonium chloride. The process has the dual benefit of decreasing sodium concentration in the reject brine and reducing carbon dioxide emissions to the atmosphere. Process parameters were studied in a semi-batch reactor to determine their effect on CO₂ capture efficiency and ions removal. These parameters included: ammonia to sodium chloride molar ratio, reaction time, temperature, gas flow rate, and pressure. Since ammonium bicarbonate is another important intermediate in the formation of sodium bicarbonate, its effect on ions removal was evaluated. The optimum conditions for maximum CO₂ capture efficiency and ions removal have been determined using response surface methodology (RSM). In addition, the continuous Solvay process has been studied at different liquid residence times. The optimum conditions for the continuous Solvay process have also been evaluated for long experimental runs. In the semi-batch mode, the highest sodium removal of 33.0 % and the best CO₂ capture of 86.2 % were obtained under specific conditions. The optimum CO₂ capture efficiency and ions removal was found to be at a temperature of 19.3oC, gas flow rate of 1.544 L/min, and 3.3NH3:1NaCl molar ratio. In the continuous Solvay process maximum ions removal were found at gas and liquid flow rates of 1.544 L/min and 12.5 ml/min, respectively, with a gas-to-liquid ratio of 123, and the reaction reached the steady-state after 240 min; the CO₂ capture efficiency in 480 min was equal to 97.9% and maximum sodium removal was 32.5%. These results indicated the technical feasibility of the Solvay approach for the capture of CO₂ and management of desalination reject brine

Process intensification for post combustion CO₂ capture with chemical absorption: a critical review

The concentration of CO₂ in the atmosphere is increasing rapidly. CO₂ emissions may have an impact on global climate change. Effective CO₂ emission abatement strategies such as carbon capture and storage (CCS) are required to combat this trend. Compared with pre-combustion carbon capture and oxy-fuel carbon capture approaches, post-combustion CO₂ capture (PCC) using solvent process is one of the most mature carbon capture technologies. There are two main barriers for the PCC process using solvent to be commercially deployed: (a) high capital cost; (b) high thermal efficiency penalty due to solvent regeneration. Applying process intensification (PI) technology into PCC with solvent process has the potential to significantly reduce capital costs compared with conventional technology using packed columns. This paper intends to evaluate different PI technologies for their suitability in PCC process. The study shows that rotating packed bed (RPB) absorber/stripper has attracted much interest due to its high mass transfer capability. Currently experimental studies on CO₂ capture using RPB are based on standalone absorber or stripper. Therefore a schematic process flow diagram of intensified PCC process is proposed so as to motivate other researches for possible optimal design, operation and control. To intensify heat transfer in reboiler, spinning disc technology is recommended. To replace cross heat exchanger in conventional PCC (with packed column) process, printed circuit heat exchanger will be preferred. Solvent selection for conventional PCC process has been studied extensively. However, it needs more studies for solvent selection in intensified PCC process. The authors also predicted research challenges in intensified PCC process and potential new breakthrough from different aspects

Dynamic Modelling, Simulation and Comparison of Large Scale Carbon Dioxide Capture in Coal Fired Power Plant using Various Amine Solvents

Chemical absorption in post combustion capture of carbon dioxide (CO2) is the most feasible and economical technology to capture CO2. In the present work, the efficacy of CO2 capturing were studied for three different amine solvents-monoethanolamine (MEA), a mixed solvent composed of methyldiethanolamine (MDEA) and piperazine (PZ), called activated MDEA (a-MDEA) and aqueous ammonia (NH3) solution. In the first part of this study, an Aspen Plus simulation model was developed and in the second part, the simulation model was used to carry out sensitivity analyses. The different key parameters for different solvents were also determined and analysed in the present study. For MEA, the key parameters were the effects of type of packing, solvent temperature and absorber height on the reboiler duty. Activated-MDEA has two key process parameters which are variation of PZ concentration in the mixed solvent and the solvent to feed ratio with the CO2 recovery and energy consumption in the reboiler of the stripper. Finally, a complete state-of-art study was done for aqueous NH3 solution on several key parameters like NH3 concentration, CO2 loading, absorber height, temperature of absorber and stripper, flow rate of lean and rich solvent, boilup ratio, condenser temperature, regeneration energy and the reboiler duty. In the final part of the study, an overall comparison is done between the three solvents by taking cost economics into consideration and thus recommending the best solvent for CO2 capturing in Post Combustion Capture using chemical absorption. Energy consumption is the major challenge for this process. Paralleling more columns or capturing a part of the overall flue gas can reduce the energy consumption

OPTIMIZATION OF PROCESS PARAMETERS FOR NATURAL GAS SWEETENING USING ASPEN HYSYS AND RESPONSE SURFACE METHODOLOGY

Amines process remains the most economic and efficient technology available today for the removal of acid gases. However, the costs associated with pumping higher flow rates and cost of increased energy needs for the regeneration of solution can undermine the economic feasibility of the project portfolio. The absorber pressure, the composition and temperature at which the sour gas is available dictates sour gas and amine flow rates needed to meet the sweet gas specifications. To improve absorber capacity for a given sweet gas specification, optimization are commonly carried out using spread sheet with an adjust function to manipulate sour gas flow rate for fixed amine flow rate. This study performed optimization using response surface methodology on a simulated and calibrated amine plant. The result shows that the optimum operating conditions for 96% CO2 removal were temperature of 30 oC, mass flow rate of 868.75 kg/hr and 20 numbers of plates. In conclusion, using experimental design and response surface methodology the parameter manipulation for attainment of optimal conditions is overcome

Physicochemical Properties and Solubility of Piperazine Activated Aqueous Solution of ß-Alanine As A Solvent for CO2 Capture

Carbon dioxide is one of the major greenhouse gas (GHG) contributors. It is an obligation for the industry to reduce the amount of carbon dioxide emission to the atmosphere. Tremendous research and studies are being done in order to develop the most plausible absorber for carbon dioxide removal. Amino acids are being looked into by the industry as a potential solvent for absorption of carbon dioxide to replace alkanolamines due to its ability to resist oxidative degradation, low volatility due to its ionic structure and higher surface tension. In addition, the introduction of promoter-like piperazine to amino acid helps to further enhance the solubility effect by acting as catalyst to speed up absorption process. In this work, the effect of piperazine activated aqueous solutions of B-alanine on physicochemical properties and solubility of CO2 is studied for various correlations. The properties are measured over a wide range of temperature from (30-60) 0C. The effect of activator piperazine on the CO2 loading performance of selected amino acid under high-pressure conditions (1bar to 10bar) at temperature range of (30-60) 0C was studied. From the observations, the density and surface tension of piperazine activated aqueous solutions of B-alanine decreases when the piperazine concentration increases. It was noticed that the density and surface tension decreases with increasing piperazine concentration in the blends. Density, viscosity and refractive index decrease with increasing temperature. Surface tension of piperazine activated aqueous solutions of B-alanine increases with increasing temperature. The value measured for physicochemical properties were correlated as a function of temperature using least-squares method and the correlation parameters are reported together with it respective standard deviation. Solubility of CO2 increases with decreasing temperature and increasing pressure. Quadratic representation of solubility using Response Surface Methodology (RSM) is generated and from the findings, the most important parameter to optimize solubility is system pressure. Addition of piperazine to amino acids solutions can increase the solubility effect of the solvent