Plant-level Dynamic Optimization of Cryogenic Carbon Capture with Conventional and Renewable Power Sources

Increasing competitiveness of renewable power sources due to tightening restrictions on CO2 emission from fossil fuel combustion is expected to cause a shift in power generation systems of the future. This investigation considers the impact of the Cryogenic Carbon Capture™ (CCC) process on transitional power generation. The CCC process consumes less energy than chemical and physical absorption processes and has an energy storage capability that shifts the parasitic loss of the CCC process away from peak hours. The CCC process responds rapidly to the variation of electricity demand and has a time constant that is consistent with the intermittent supply from renewable power sources. The hybrid system of conventional and renewable power generation units and the CCC process are optimized in this investigation. The system under consideration consists of load-following coal and gas-fired power units, a CCC process, and wind generation. The objective is to meet the residential and CCC plant electricity demands while maximizing the operating profit. The results demonstrate that an average profit of $35 k/hr is obtained from this hybrid system over the selected days. The total electricity demand is best met using a combination of coal, gas, and wind power with grid-scale energy storage

Investigating the Impact of Cryogenic Carbon Capture on Power Plant Performance

Cryogenic Carbon Capture (CCC) is a CO2 mitigation process that can be integrated into existing baseline and load following fossil-fueled power plants. This process consumes less energy than conventional chemical absorption and includes energy storage capability. The CCC process has a fast response time to load changes to allow higher utilization of intermittent renewable power sources to be used at a grid-scale level in the power sector. The impact of the CCC process on the performance and operating profit of a single fossil-fueled power generation unit is studied in this paper. The proposed system (power production from wind, coal, and natural gas) meets the total electricity demand with 100% utilization of the available wind energy. The operational strategy for the hybrid energy-carbon capture system and the change in the performance of the hybrid system due to the seasonal changes are also examined in this paper. A sensitivity analysis is implemented to investigate the change in operating strategy of the hybrid system based on the relative fraction of wind energy adoption. The optimal wind energy adoption factor in the proposed system is obtained

Nonlinear Modeling, Estimation and Predictive Control in APMonitor

This paper describes nonlinear methods in model building, dynamic data reconciliation, and dynamic optimization that are inspired by researchers and motivated by industrial applications. A new formulation of the ℓ1-norm objective with a dead-band for estimation and control is presented. The dead-band in the objective is desirable for noise rejection, minimizing unnecessary parameter adjustments and movement of manipulated variables. As a motivating example, a small and well-known nonlinear multivariable level control problem is detailed that has a number of common characteristics to larger controllers seen in practice. The methods are also demonstrated on larger problems to reveal algorithmic scaling with sparse methods. The implementation details reveal capabilities of employing nonlinear methods in dynamic applications with example code in both Matlab and Python programming languages

Post-Installed Fiber Optic Pressure Sensors on Subsea Production Risers for Severe Slugging Control

Fiber optic sensors have gained increasing use in monitoring offshore structures. The sensors have successfully monitored flowlines, umbilicals, wells, Tension Leg Platform (TLP) tendons, production and drilling risers, and mooring lines. Fiber optic sensors are capable of monitoring strain, temperature, pressure, and vibration. While the success of fiber optic monitoring has been clearly demonstrated, the sensors are now under consideration for automation applications. This paper details the plausibility of using pressure measurements from post-installed fiber Bragg grating (FBG) sensors with Model Predictive Control (MPC) to suppress severe slugging in subsea risers. Prior control schemes demonstrate that slugging is mitigated using a topside choke valve. The most effective methods use a pressure measurement immediately upstream of the touchdown zone of the riser; however, the majority of production risers do not have pressure sensing at that location. With advances in subsea clamp design and bonding it is now possible to install a non-penetrating FBG sensor to monitor pressure near the touchdown zone without shutting down production. Stabilizing the two phase flow both reduces vibration-induced fatigue and has the potential to allow increased throughput with relaxed topside processing constraints. MPC predicts and adjusts for disturbances to avoid pressure and flow instability. The performance of the controller is influenced by sensor location, choke valve response time, and riser geometry. This study demonstrates that severe riser slugging is effectively controlled with MPC and a post-installed, non-penetrating FBG sensor

The Application and Accuracy of Structure from Motion Computer Vision Models with Full-Scale Geotechnical Field Tests

Structure from motion (SfM) computer vision is a relatively new technology that allows engineers to reconstruct a three-dimensional (3D) model of a given scene using twodimensional digital photographs captured from a single, moving camera. SfM computer vision provides an economic and user-friendly alternative to other 3D scene-capture and modeling tools such as light distance and ranging (LiDAR). Although the resolution and accuracy of laser-based modeling methods are generally superior to vision-based modeling methods, the economic advantages associated with the latter may make it a useful and practical alternative for many geotechnical engineering applications. Although other engineering disciplines have investigated the potential usefulness of SfM computer vision for years, its application to geotechnical engineering generally remains unexplored. Researchers are currently investigating the application of this technology to select full-scale geotechnical field experiments and assessing its potential usefulness as a high-resolution instrumentation/monitoring tool. This paper presents preliminary computer vision results and findings from these studies. The field experiments, as well as the hardware and software details used to develop 3D SfM computer models of the experiments are summarized. The developed 3D models are presented, and displacements measured in the models are compared against ground truth to evaluate accuracy. Observed advantages and limitations of SfM computer vision are discussed, and several potentially useful applications of the technology in geotechnical engineering are listed

The Imd Pathway Is Involved in Antiviral Immune Responses in Drosophila

Cricket Paralysis virus (CrPV) is a member of the Dicistroviridae family of RNA viruses, which infect a broad range of insect hosts, including the fruit fly Drosophila melanogaster. Drosophila has emerged as an effective system for studying innate immunity because of its powerful genetic techniques and the high degree of gene and pathway conservation. Intra-abdominal injection of CrPV into adult flies causes a lethal infection that provides a robust assay for the identification of mutants with altered sensitivity to viral infection. To gain insight into the interactions between viruses and the innate immune system, we injected wild type flies with CrPV and observed that antimicrobial peptides (AMPs) were not induced and hemocytes were depleted in the course of infection. To investigate the contribution of conserved immune signaling pathways to antiviral innate immune responses, CrPV was injected into isogenic mutants of the Immune Deficiency (Imd) pathway, which resembles the mammalian Tumor Necrosis Factor Receptor (TNFR) pathway. Loss-of-function mutations in several Imd pathway genes displayed increased sensitivity to CrPV infection and higher CrPV loads. Our data show that antiviral innate immune responses in flies infected with CrPV depend upon hemocytes and signaling through the Imd pathway

Identification and Functional Analysis of Antifungal Immune Response Genes in Drosophila

Essential aspects of the innate immune response to microbial infection appear to be conserved between insects and mammals. Although signaling pathways that activate NF-κB during innate immune responses to various microorganisms have been studied in detail, regulatory mechanisms that control other immune responses to fungal infection require further investigation. To identify new Drosophila genes involved in antifungal immune responses, we selected genes known to be differentially regulated in SL2 cells by microbial cell wall components and tested their roles in antifungal defense using mutant flies. From 130 mutant lines, sixteen mutants exhibited increased sensitivity to fungal infection. Examination of their effects on defense against various types of bacteria and fungi revealed nine genes that are involved specifically in defense against fungal infection. All of these mutants displayed defects in phagocytosis or activation of antimicrobial peptide genes following infection. In some mutants, these immune deficiencies were attributed to defects in hemocyte development and differentiation, while other mutants showed specific defects in immune signaling required for humoral or cellular immune responses. Our results identify a new class of genes involved in antifungal immune responses in Drosophila

Long-Range Activation of Systemic Immunity through Peptidoglycan Diffusion in Drosophila

The systemic immune response of Drosophila is known to be induced both by septic injury and by oral infection with certain bacteria, and is characterized by the secretion of antimicrobial peptides (AMPs) into the haemolymph. To investigate other possible routes of bacterial infection, we deposited Erwinia carotovora (Ecc15) on various sites of the cuticle and monitored the immune response via expression of the AMP gene Diptericin. A strong response was observed to deposition on the genital plate of males (up to 20% of a septic injury response), but not females. We show that the principal response to genital infection is systemic, but that some AMPs, particularly Defensin, are induced locally in the genital tract. At late time points we detected bacteria in the haemolymph of immune deficient RelishE20 flies, indicating that the genital plate can be a route of entry for pathogens, and that the immune response protects flies against the progression of genital infection. The protective role of the immune response is further illustrated by our observation that RelishE20 flies exhibit significant lethality in response to genital Ecc15 infections. We next show that a systemic immune response can be induced by deposition of the bacterial elicitor peptidoglycan (PGN), or its terminal monomer tracheal cytotoxin (TCT), on the genital plate. This immune response is downregulated by PGRP-LB and Pirk, known regulators of the Imd pathway, and can be suppressed by the overexpression of PGRP-LB in the haemolymph compartment. Finally, we provide strong evidence that TCT can activate a systemic response by crossing epithelia, by showing that radiolabelled TCT deposited on the genital plate can subsequently be detected in the haemolymph. Genital infection is thus an intriguing new model for studying the systemic immune response to local epithelial infections and a potential route of entry for naturally occurring pathogens of Drosophila