Bed Pressure Research Articles

High dimensional Longitudinal Assessment of Ambient Home Environments and Their Association with Behaviors of People with Cognitive Decline

AbstractBackgroundTroubling behavioral symptoms such as mood changes or agitation are highly prevalent during the course of Alzheimer’s disease and related dementias (ADRD). Effective management is dependent upon understanding the causes and precipitants of behavioral symptoms. The objective of our studies is to evaluate the role of the physical ambient environment in instigating symptoms.MethodParticipants are from two studies: 1) MOnitoring DEmentia‐Related Agitation Using Technology Evaluation (MODERATE) which focuses on agitation in people with later‐stage dementia, and 2) Monitoring Apathy, Depression and Anxiety Using Technology Evaluation (ADA) which focuses on apathy, depression and anxiety in older adults with or without cognitive decline. A commercially available, multifunction environmental sensor, Awair Omni, was deployed in the room where the participant sleeps, measuring levels of temperature, humidity, carbon dioxide (CO2), total volatile organic compounds (VOC), particulate matter 2.5 (PM2.5), noise and light every 5 minutes. Additionally, a multi‐sensor array (bed pressure mats, motion sensors, and wearables) is deployed in homes to objectively measure participants’ behaviors. Caregivers in MODERATE report agitation level/event experienced by their partners while participants in ADA self‐report their level of symptoms via weekly online surveys.ResultTo date, 9 dyads (persons with cognitive decline and their caregivers) have enrolled in MODERATE and 9 participants are enrolled in ADA. 3135 days of data have been collected for MODERATE while 849 days of data have been collected for ADA. Mean participant characteristics: age = 75±8 years; 48% women; Blind MoCA = 13.2±7.96. For 4 weeks from 12/19/2022 to 1/15/2023, ambient environmental conditions identified (mean±SD): temperature = 21 ±2.0°C; humidity = 41±7.6%; VOC = 195±263 ppm; CO2 = 651±225 ppm; particulate matter 2.5 = 2.4±13 µg/m3; noise = 52±4.3 dBA; light = 9.5±40 Lux. The home environments are individually heterogeneous with high variability over time across multiple environmental conditions. Reports of behavioral symptoms show high week‐to‐week variability as well. Proposed methods of analyzing such data include generalized linear mixed model.ConclusionThis in situ environmental sensing approach provides more objective and timely data to enable identifying the relationship between physical environments and the behaviors of older adults at risk of or with ADRD. The knowledge generated will help prevent or mediate symptoms by prospectively modifying environmental conditions.

Modeling and simulation of dynamic characteristics of a green ammonia synthesis system

Green ammonia production system driven by renewable electricity will be under frequent dynamic operation due to the fluctuation of renewable energy. The nonlinear dynamic model of a green ammonia synthesis system is developed and the dynamic responses of PEM (proton exchange membrane) electrolysis subsystem, PSA (Pressure swing adsorption) subsystem and ammonia synthesis subsystem during the start-up process and under the fluctuation of renewable electrical current are analyzed. The start-up dynamic results show that the hydrogen production rate of PEM electrolysis system is positively correlated to the current. The nitrogen output of PSA system is affected by the adsorption time, adsorption pressure, bed length, and air velocity. A start-up period of 300 min from the warmed-up state to the design state can maintain the temperature rise rate of the ammonia synthesis reactor at approximately 40 K/h. The dynamic results under step fluctuations of electrical current show that the PEM electrolysis subsystem and the PSA subsystem response fast compared to the ammonia synthesis reactor and buffer tanks. Using large buffer tanks to smooth the fluctuation allows the system to slide with the variation of renewable current to some extent, resulting in a higher outlet ammonia fraction when the current increases. Different volume ratios of the hydrogen tank to the nitrogen tank volume can lead to different variations of the hydrogen/nitrogen ratio. PID controllers can effectively maintain the bed temperatures, hydrogen/nitrogen ratio, and pressure of the ammonia synthesis reactor at their set points despite fluctuations in renewable electrical current. Buffer tanks are necessary to compensate for the imbalance between the flow rate fluctuation caused by current change and the flow rate regulation caused by PID controllers.

Eulerian investigation of the mechanism of Ultra-low NOx emissions from CFB boilers with finer bed material

Industrial practice has confirmed that decreasing the bed material size substantially diminishes nitrogen oxide (NOx) emissions in coal-fired circulating fluidized bed (CFB) boilers. This reduction allows for compliance with the stringent ultra-low emissions standard (NOx < 50 mg/Nm3@6%O₂, dry) proposed by the Chinese government, all without the need for supplementary denitrification devices. Consequently, it becomes essential to delve into the mechanisms through which particle size, as a gas–solid flow characteristic, directly affects the chemical reaction dynamics within the coal combustion process. Due to the difficulty of field tests, this paper employs the Eulerian-Eulerian numerical method suitable for wide particle size distributions to investigate the impact of bed material particle size on gas–solid flow and NOx concentration. Furthermore, the generalized QC-EMMS drag model is utilized to predict the heterogeneous flow across varying particle size conditions. Industrial test data validated the simulation accuracy, with prediction errors of bed pressure drop, temperature, and NOx emission concentration ranging from 5 % to 8.1 %. The analysis revealed that the particle concentration distribution heterogeneity decreases as the particle size diminishes. The variation trends of NOx with particle size exhibit distinct differences between the lower dense phase region and the upper dilute phase region within the bed. For finer bed material particles, the high NOx concentration generated in the dense phase region experiences a more thorough reduction in the dilute phase region. Through the analysis of material concentration and reaction rate, it is believed that this phenomenon is related to the increased catalytic effect of fine ash particles in the dilute phase region, that is, the reduction in particle size leads to an increase in catalytic specific surface area, enhancing NOx reduction, thus achieving ultra-low emissions at the outlet. These research results provide theoretical support for further development of ultra-low emission coal-fired CFB boilers.

EGS P29 Evaluating Compliance and Identifying Barriers to Timely Cholecystectomy in Gallstone Pancreatitis: A Retrospective Study

Abstract Background Gallstone pancreatitis is a common cause of acute pancreatitis. Timely cholecystectomy within two weeks of admission is recommended by the UK Pancreatitis Guidelines and NCEPOD to prevent recurrent pancreatitis and associated complications. This study aimed to evaluate compliance with these guidelines at a District General Hospital. Methods A retrospective analysis was conducted on all patients (n=92) admitted with acute pancreatitis between July 1st 2022, and January 31st 2023. Patient demographics, diagnostic methods, time to surgery, and relevant laboratory values (median amylase, median CRP) were collected and analysed. Results 35% (n=32) of patients had gallstone pancreatitis. 26 were fit for cholecystectomy. 35% (n=9) were operated on within 2 weeks. Median time to surgery was 7 days and median CRP 133. There were no readmissions within 6 months. The delayed surgery cohort (n=17) had a median time to surgery of &amp;gt;60 days, median CRP 29 and a 59% (n=10) readmission rate . 1 patient had three readmissions. Reasons for delay were: 2 pancreatic necrosis, 1 pregnancy, 1 pneumonia, 1 delirium, 2 bed pressure, and 10 no clinical reason. 5 patients are still waiting for surgery at the time of analysis &amp;gt;6months. Conclusions Prior to the COVID-19 pandemic, compliance with UK pancreatitis and NCEPOD guideline was excellent (GIRFT) at our institution. Our findings are that most patients with gallstone pancreatitis are not being operated upon within two weeks. Delays result in hospital readmissions increasing resource use. Most delays were organisational rather than clinical. Patients who were ambulated for operative management within 2 weeks rarely were operated upon within this timeframe. Trust initiatives aimed at COVID-19 recovery prioritised early discharge and repurposed emergency ‘hot lists’ to reduce elective waiting lists. Interventions to increase emergency operating capacity are most likely to improve matters.

HPB P35 A snapshot analysis to identify ideal interval between liver imaging and resection

Abstract Background An increase in waiting times has been seen across all NHS service provisions in the last few years due to post-pandemic backlog, staffing issues, bed and theatre pressures. This has led to increasing intervals between cancer diagnosis and surgery, which may negatively impact patient outcomes. The ideal interval between final cross-sectional imaging and liver resection for hepatocellular carcinoma (HCC) and colorectal liver metastases (CRLM) is not well established.The aim of the study was to explore the most appropriate interval between scan and operation and its effect on outcomes; Tumour growth, resectability, R0 rates, disease free survival and overall survival. Methods A retrospective analysis of our prospective maintained liver resectional database was performed. Patients undergoing resection for HCC or CRLM between January 2020 and December 2021 were included. Patients were followed up until June 2023. Groups were split into a &amp;lt;6-week interval and ≥6-week interval group. Scans and radiology reports and post-op histology were reviewed to identify interval changes of individual tumours. We analysed outcomes of gross and percentage increase in tumour size, recurrence rates, median disease-free survival and overall survival. Patient demographics including age (≥18), gender, BMI, neoadjuvant chemotherapy, type of scan, initial size and number of lesions were analysed. Results 53 patients were included in the analysis (19 female). Disease free survival was 27.4 months in &amp;lt;6 week group vs. 24.9 months in ≥6 week group. Average tumour growth was 5.9mm higher (range 3.7-9.6mm) when interval time was &amp;gt;6 weeks. Tumour percentage growth was 11.5% in &amp;lt;6 week group vs 32% in ≥6 week group. Recurrence rate in &amp;lt;6 week group was 23.5% VS 30.5% in ≥6 week group. There was no difference in percentage overall survival, non-resectability rate or R1 rates. Conclusions In this snapshot study of liver resections over a two-year period we did find an expected bigger increase in tumour size in patients where the interval between last cross-sectional imaging and actual resection was longer. The ≥6week interval group seems to have more tumour recurrence but this did not impact overall survival. This pilot cohort was not powered to firmly establish guidance for maximum interval between last scan and surgery, but it prompts further investigation to get clarity to guide clinical practice. A larger cohort would ideally look at HCC and CRLM separately.

EGS P26 Facilitating the Emergency Surgical Ward Round: The Route to WardNav

Abstract Background The ward round is a corner stone of surgical practice, this is no different when dealing with the acute surgical take. Constant bed pressures result in frequently needing to visit multiple wards, requiring time and effort on staff to ensure patients are reviewed. With frequent rotation of junior doctors, often the responsibility of planning the ward round falls to the ward round leader, who is also making the clinical decisions. We hypothesise a ward round planning tool available to the surgical team would result in more efficient ward rounds, freeing the team to focus on clinical decisions. Methods A survey of junior doctors (foundation doctors and core trainees) was distributed assessing their level of engagement with ward round planning while on surgical rotations at Southmead Hospital, Bristol. An initial planning tool was created in Microsoft Excel utilising a node edge graph and an algorithm based on the Hamiltonian cycle. After further survey feedback, the tool was developed into a web-based app using a version of Djikstra’s algorithm. Results 25 junior doctors responded to the initial survey over two rotations. 100% had to go to multiple wards on a round, 64% actively think about the route required although only 28% would be confident in planning the route. 96% would find a planning tool helpful. Feedback on the Excel based tool from the first cohort revealed appetite for a mobile app-based version. The resultant application was created in R. The final version allows the user to start the round on any ward and creates the optimal route through the building, visually represented on a graph with accompanying text output. Conclusions Junior surgical doctors are not confident with planning ward rounds in a large teaching hospital. An app-based ward navigation tool has the potential to remove ward round planning from daily decision making and engage the junior surgical staff.

Patient and multidisciplinary health professional perceptions of an Australian geriatric evaluation and management and rehabilitation hospital in the home service.

Hospital in the Home models are rapidly expanding in response to increasing bed pressures. This study examined patient and multidisciplinary health professional perceptions of a new geriatric evaluation and management and rehabilitation hospital in the home service in Australia. The service was unique, as adults of all ages with a variety of rehabilitation or geriatric evaluation and management needs were within scope. A qualitative descriptive approach was used with a consumer co-researcher and a consumer advisor being integral to decision-making. Patient feedback was collected via a paper-based patient satisfaction survey between August 2020 and February 2022. Additionally, interviews with current and past staff were conducted from July to November 2021. Reflexive thematic analysis was conducted for qualitative data and descriptive statistics used for quantitative data. Patient surveys were analysed (n = 199, 42.2% response rate) with 60.8% of participants aged 75years or over and 26.6% speaking a language other than English. High satisfaction was expressed. Feelings of comfort, familiarity, convenience, and reassurance were voiced. A person-centred approach enhanced involvement in care. Challenges included carer burden and clear communication. Sixteen staff (33% response rate) were interviewed. In general, staff said the service was inclusive and responsive, and the home environment beneficial, particularly for patients from culturally diverse backgrounds. A strong hospital partnership and comprehensive multidisciplinary approach were vital. Challenges included fragmentation due to part-time roles and combining with a pre-existing acute hospital in the home service. This qualitative exploration of staff and patients' perceptions of a geriatrician-led, multidisciplinary geriatric evaluation and management and rehabilitation hospital in the home service demonstrated that it was person-centred and optimised patients' control and ownership of care. The inclusive service parameters ensured responsiveness to diverse needs whilst allowing earlier return home from hospital, both of which are vital for quality patient care.

Industrial-scaled Cu-Fe composite oxygen carrier for chemical looping combustion through extrusion-spheronization

It is crucial for the preparation of the high-performance and low-cost oxygen carrier (OC) in an industrial-scaled application to lay the foundation for the commercialization of chemical looping combustion (CLC) technology. In this work, a bimetallic OC (RCu-10 M) is prepared in an industrial-scaled extruder coupling with roller, composited by the red mud (aluminum industrial waste), copper ore and montmorillonite as raw materials. First, a thermogravimetric analyzer (TGA) is used to carry out 100 redox cycles using H2 as the reducing agent. RCu-10 M OC demonstrate remarkable redox stability and sintering-resistance across multiple cycles, and the oxygen donating capacity do not diminish as the number of cycles increases. The effects of temperatures and excess oxygen coefficients on the reactivities of RCu-10 M OC with Shenhua bituminous coal are then investigated by using a batch fluidized bed reactor. RCu-10 M OC maintains high combustion efficiency, exceeding 94.7 % at 950 °C, with an excess oxygen coefficient of 2.0. Finally, a lab-scaled interconnected fluidized bed reactor is applied to examine the realistic performance of RCu-10 M OC using CH4 fuel. The results demonstrate that the RCu-10 M OC successfully operates for ca. 100 min of continuous time, and there is no de-fluidization occurrence, and the bed pressure decrease is stable during operation, indicating that the RCu-10 M OC exhibits good fluidization properties and had the potential to be used in large-scale fluidized bed reactors. Further characterization data reveal that the chemical composition of RCu-10 M OC is stable throughout multiple cycles, as indicated by the almost uniform distribution of elements.

Are there wall effects on pressure drop through randomly packed beds of spherical catalyst particles?

AbstractFor packed beds of low tube‐to‐particle diameter ratio (), pressure drop has been found to increase at low Re &lt;100 and decrease at high Re &gt;1000, compared to that in unbounded beds. Particle‐resolved CFD (PRCFD) in the low Re viscous region shows that widely accepted corrections overestimate the wall effect, and an improved correction formula is given. In the inertial region at high Re it is important to use accurate and consistent values for void fraction, which strongly affects pressure drop. Literature data show reasonable agreement with a correlation developed for unbounded beds (Dixon AG., AIChE J. 2023;69(6):e18035), when the void fractions for the bounded beds are used. PRCFD simulations also confirm this agreement, and only a small further correction is suggested for the remaining wall effects on fixed bed pressure drop in the inertial range, since the correlation uses the correct limit for as Re increases.

Assessing the conveyance of fluidized natural gas hydrate in a horizontal tubing

This study evaluates the transportability of clayey-silt natural gas hydrate (NGH) solid particles during solid fluidization in horizontal tubing, a crucial step in recovering marine NGH. Non-uniform solid particle distribution in horizontal flows can cause unstable operations and financial losses. Thus, assessing transportability is necessary to avoid these issues and harness the potential of NGH as an alternative energy source. This study introduces a model based on each phase's two-layer approach and momentum balance equation, considers potential hydrates (re)formation, and overcomes previous models’ limitations. Moreover, it assumes that the critical settling velocity marks the moment when the lower bed of solid particles stagnates, thereby leading to the disappearance of frictional pressure in the lower bed. The proposed model is evaluated and compared with existing models using a laboratory dataset and the South China Sea offshore field dataset and found to provide the highest prediction accuracy and precision. Moreover, it reveals that the tubing diameter, solid particle diameter, and solid particle concentration are the major influential parameters affecting the solid particle conveyance. Consequently, the proposed model is suitable for evaluating the transportability of those solid particles in horizontal tubing, making it ideal for assessing their transportability in pipelines.

Influence of distributor plate design on mixing characteristics of rice husk biomass in a bubbling fluidized bed gasifier: An experimental and CFD study

This study investigates the mixing characteristics of rice husk biomass in a bubbling fluidized bed gasifier (BFBG) using different distributor plates: perforated, 45° slotted, and hybrid plates. The study explores the fluidization characteristics of a biomass/sand mixture using three distributor plates, observing the maximum difference in initial minimum fluidization velocity (Umf,i) and final minimum fluidization velocity (Umf,f) for perforated plate, indicating axial mixing and segregation, while the 45° slotted plate represents uniform bed expansion and fluidization, and the hybrid plate exhibits an intermediate behavior. Axial and lateral biomass distribution is also studied, and it is found that with the 45° slotted plate the highest axial distribution of rice husk is observed at the lower portion due to lateral and swirling flow whereas perforated plate causes the highest deviation at the lower portion but approaches ideal mixing at the mid and upper sections due to axial dominant flow. The hybrid plate exhibits a blend of axial and lateral flows, resulting in intermediate axial distribution at lower and upper section of gasifier. Radially, the perforated plate has the highest concentration of biomass at maximum height whereas the 45° slotted plate has concentration near the walls, and the hybrid plate has optimal mixing throughout. The hybrid plate also achieves the highest mixing index at all air velocities. Overall, the study provides insights into biomass mixing in BFBGs and highlights the superior performance of the hybrid distributor plate.The CFD study also carried out to complement the experimental results in terms of pressure drop and mixing behavior by employing different distributor plats. Multiphase two fluid model (TFM) with kinetic theory of granular flow has been employed for CFD simulations with the engagement of k-epsilon turbulence model. The simulation results are in good agreement with experimental results in terms of bed pressure drop quantitatively and mixing characteristics of rice husk biomass qualitatively.

COVID-19 Patients' Medication Management during Transition of Care from Hospital to Virtual Care: A Cross-Sectional Survey and Audit.

Virtual models of care were implemented to ease hospital bed pressure during COVID-19. We evaluated the medication management of COVID-19 patients transferred to virtual models of care. A retrospective audit of COVID-19 patients transferred from inpatient units to virtual care during January 2022 and surveys from patients transferred during December 2021-February 2022 was carried out. One hundred patients were randomly selected: mean age 59 years (SD: 19.8), mean number of medicines at admission 4.3 (SD: 4.03), mean length of virtual ward stay 4.4 days (SD: 2.1). Pharmacists reviewed 43% (43/100) of patients' medications during their hospital stay and provided 29% (29/100) with discharge medicine lists at transfer. Ninety-two (92%) patients were prescribed at least one new high-risk medicine whilst in hospital, but this was not a factor considered to receive a pharmacist medication review. Forty patients (40%) were discharged on newly commenced high-risk medicines, and this was also not a factor in receiving a pharmacist discharge medication list. In total, 25% of patient surveys (96/378) were returned: 70% (66/96) reported adequate medicine information at transfer and 55% (52/96) during the virtual model period. Patient survey data show overall positive experiences of medication management and support. Audit data highlight gaps in medication management during the transfer to a virtual model, highlighting the need for patient prioritisation.

Multi-objective optimization of breakthrough times for hydrogen purification through layered bed pressure swing adsorption based on genetic algorithm and artificial neural network model

Hydrogen purification from steam methane reforming (SMR) by pressure swing adsorption (PSA) technology is a common method to obtain high-purity hydrogen. The breakthrough time can well reflect the adsorption dynamics and help PSA cycle design. In order to avoid time-consuming and labor-intensive breakthrough curve experiments, it is very necessary to develop a fast and accurate surrogate model. In this study, a genetic algorithm (GA) and artificial neural network (ANN) are combined to predict and optimize breakthrough times of adsorbates in activated carbon/zeolite layered beds. Using the Latin hypercube sampling strategy, training data sets of GA-optimized ANN (GA-ANN) obtains from the physical model of adsorption, heat and mass transfer model. The genetic algorithm (GA) optimizes the weights and biases of ANN for better performance. The ANN topology has 4 input variables (superficial velocity, activated carbon height, adsorption pressure and feed temperature) and 3 output variables (breakthrough times of CH4, CO and CO2). The number of neurons in the hidden layer for the GA-ANN model was optimized as 7 to predict and optimize the maximum breakthrough time of SMR with a four-component (H2/CH4/CO/CO2) system. The sensitivity analysis displays that relative importance to the breakthrough time is in the order of superficial velocity (40.88%) > adsorption pressure (24.55%) > activated carbon height (21.04%) > feed temperature (13.53%). To obtain high-purity hydrogen, the GA-ANN model combined with multi-objective GA optimization is used to maximize the breakthrough times of CH4 and CO. The GA-ANN surrogate model proposed in this paper can not only accurately and quickly achieve the purpose of predicting the system breakthrough time with a high correlation coefficient (R = 0.9937) but also obtains the optimal operating conditions of PSA hydrogen purification.

Short (23-hour)-stay robotic-assisted radical prostatectomy in a state-funded national health service – Is it safe and feasible?

Objectives: The COVID-19 pandemic has led to a long waiting list for elective surgery and increasing bed pressures from acute admissions. This led to widespread cancellations on the day of surgery even for cancer procedures. To address this, all inpatient stay robotic-assisted radical prostatectomy (RARP) cases were managed via our day surgery unit as a 23-hour stay. We report the safety and feasibility of our initial implementation. Methods: A standard operating procedure for admission via the day surgery unit, including a modified enhanced recovery pathway, for patients undergoing RARP with or without pelvic lymph node dissection (PLND) was devised. All pre-operative variables were collected, and all perioperative outcomes analysed. Primary outcomes were number of on the day cancellations, discharge failure as 23-hour stay and 30-day readmissions. Results: Between November 2021 and June 2022, 135 patients underwent RARP with or without PLND via the day surgery unit. Mean patient age was 65 (46–76) years. Mean operative time and estimated blood loss were 153 (67–281) minutes and 197 (50–700) mL, respectively. Concomitant lymph node dissection was performed in 32.7% of cases. No patient required blood transfusion or conversion to open. We had 3 (2.2%) discharge failures, all of which were due to clinical reasons. Our 30-day hospital readmission rate was 3.7%, while another 5.2% attended emergency department and were discharged without admission. Conclusion: Short (23-hour)-stay RARP is safe and feasible and reduces pressure on inpatient beds but requires a multidisciplinary approach and engagement from all stakeholders. Level of evidence: 2

Hydrodynamics of a Multisized Particle Mixture in Shallow Fluidized Bed With Immersed Tubes

Abstract Inert solid particles have made the integration of more efficient power cycles with super high operating temperatures into the concentrated solar power (CSP) station feasible. Fluidized bed heat exchangers with feature of high heat transfer coefficient have great application potential in the particle-based CSP. However, the parasitic loads of the additional fluidizing gas loop and the finely sieved monosized particles may deteriorate the economic efficiency of the integrated system. In order to cope with this problem, a conceptual design of a shallow fluidized bed (SFB) heat exchanger is proposed for the new generation CSP technology. Fluidization characteristics of bauxite particles with a nonuniform particle size distribution in SFB with immersed tubes are investigated with a combination of experimental measurements and computational fluid dynamics simulations. Results show that the static bed height and opening area ratio of the distributor has insignificant influence on the range of semifluidized region and the minimum fluidization velocity Umf. The standard deviation of bed pressure drop σ in the grid region can be used as an alternative criterion for identifying the fluidization state. A range of superficial velocity that distinguishes two different solid circulation patterns exists, with its boundary values being four times and eight times the Umf, respectively. The immersed tubes can inhibit the asymmetric particle circulation patterns from developing in the SFB, but cause a substantial increase in the σ within the grid region.

Particle combination characteristics on PM2.5 granular bed filtration efficiency and pressure drop

Granular bed filters are widely utilized in hot gas dust removal due to their low cost, high temperature resistance, and simple structure compared with other dust removal methods. Conventional granular bed filtration is usually only applicable to the separation of particulate matters above PM10, and its PM2.5 efficiency separation needs to be improved. A new method for efficiently separating PM2.5 is developed in this study by combining different filter media. The effects of filter deck thickness, filter mediums diameter, and granular bed combination characteristics on PM2.5 separation efficiency and separation pressure drop are systematically studied. A group of single-deck filtration experiments show that the average separation efficiency for PM2.5 can reach 92.9% with an average separation pressure drop of 0.53 kPa. Double-deck granular bed filtration can also offer an average separation efficiency for PM2.5 91.2%, but the average separation pressure drop is significantly reduced to 0.4 kPa. The results prove that compared with a single granular bed; double granular beds demonstrate evident advantages in energy consumption ratio. This study provides references for studying PM2.5 in depth separation and granular bed filtration.

Numerical investigation on the influence of immersed tube bundles on biomass gasification in industrial-scale dual fluidized bed gasifier

Immersed tubes play a pivotal role in enhancing fluidization quality within fluidized beds by effectively disrupting bubbles. However, the effect of such internals within a large-scale gasification apparatus remains unclear. Consequently, this study focuses on numerically simulating biomass steam gasification within an industrial-scale dual fluidized bed gasifier that features immersed tube bundles using the multiphase particle-in-cell method. In this method, particles with identical properties are grouped, and the interparticle collisions are model via the solid stress to improve computational efficiency. The numerical model has been well verified with experiment in terms of bed pressure drop, solid recirculation and chemical reactions. Some main conclusions are shown as follows. Immersed tubes significantly alter the motion of gas and particles in the gasifier. The presence of immersed tubes can ameliorate solid entrainment and avoid excess particles escaping from the gasifier. The asymmetrical structure of the gasifier results in asymmetrical distribution of gas temperature and gas species. Increasing the number of immersed tubes slightly enhances particle temperature near the loop seal outlet. The radial biomass dispersion coefficient and axial sand dispersion coefficient decrease about 40.9 % and 28.9 % when increasing the immersed tube number from three to nine. The results provide enhanced understanding of the role of immersed tubes in altering gas-particle interactions and fluidization dynamics in industrial-scale fluidized bed gasifier.

Structural evolution of bed drainage channels under the shear effect of the whole process of tailings thickening

Cemented paste backfill (CPB) technology has the advantages of safety, environmental friendliness, economics, and efficiency. This method offers assurances for practical underground mining and tailings pond management. The bed drainage channel structure and coarse particles with diameters above 45 μm were reconstructed and quantitatively characterized in 3D by computed tomography (CT) for the whole tailings thickening process. The spherical pore diameter evolution trends, stick throat channel radius and throat channel length were analyzed with and without shear using the pore network model (PNM). The functional relationship between the average spherical pore diameter and bed pressure is given, and the boundary values between the bed’ primary and secondary drainage channels are clarified. The ratio of throat length to diameter (Tw) is proposed to measure the difficulty of throat channel structure on the water discharge in the bed. The effects of the volume and number of coarse particles with diameters above 45 μm on the bed porosity and pore connectivity were analyzed. The range of particle diameters that significantly affect the bed porosity and pore connectivity was clarified. The results show that the spherical pore diameter, throat channel radius, and throat channel length decrease with increasing bed pressure with and without shear. Moreover, the average spherical pore diameter in the bed has a power-law relationship with the bed pressure. The spherical pore diameter, throat channel radius, and throat channel length with shear were lower than without shear, and the slurry concentration was higher than without shear. The main drainage channels of the bed with and without shear consisted of large pore structures with diameters of not less than 433.3 μm and 329.8 μm, respectively. The throat channel structure parameter Tw increases with the increase of bed pressure. When Tw is higher than 8.7, the discharge of water in the bed is hindered, making it challenging to improve the slurry concentration. The porosity and pore connectivity of the bed decreases with increasing volume and number of coarse particles. Among them, coarse particles in the diameter 150–300 μm range significantly reduce the bed porosity and pore connectivity. This study guides the preparation of high-concentration paste filling slurry, which is helpful to improve the efficient mining capacity of mines and have fewer tailings ponds.

Full-Loop Study of a Pilot-Scale Dual Fluidized Bed Cold Flow System: Hydrodynamic Simulation

Computational particle fluid dynamics (CPFD) simulations of three-dimensional cold-flow gas-solid flow were performed for a pilot-scale dual-circulating fluidized bed (DCFB) using Barracuda Virtual Reactor® 17.4.0. This DCFB system is a fluidized bed gasifier used in a calcium-loop gasification process to produce a hydrogen-rich gas with CO2 capture. The effects of different bubble bed inlet airflow rates and different solid inventories on the full-loop pressure distribution and particle concentration distribution were compared. The increase in the bubble bed inlet airflow rate significantly increases the pressure in the bubble bed and lift pipe, and the increase in the solids inventory significantly increases the pressure where the solids are tightly packed. For long-term operation, the appropriate combination of parameters should be found to maintain a stable particle seal at the loopseals.

375 Introduction of a Physician Associate (PA) Led Surgical Ambulatory Emergency Clinic (SAEC) in the Highlands of Scotland

Abstract Aim The delivery of surgical care in the Highlands has changed. SAEC was developed to alleviate bed pressures, improve patient satisfaction, and avoid unnecessary workload. We aim to identify whether SAEC is alleviating pressures in the surgical inpatient department - is it used appropriately and cost effectively. Method Attendance was collected prospectively (1/9/22 to 31/10/22) using a dedicated data audit book and booking diary. Patient’s individual review outcomes were gathered. Results Of the 165 patients referred to SAEC, 90% were reviewed by the PA, 10% only by the consultant. On average, 3.7 patients were seen per day. The referral reasons were wide ranging: 64 referrals for abdominal pain in addition to abscesses, constipation, weight loss, vomiting, stoma reviews and more. The age of patients ranged from 20-91. 61% were female. 46% had a scan. 85% received a diagnosis. 93% received definitive management. No patients made an unplanned re-presentation within the week following their review. The average time spent in SAEC per patient was 2 hours 48 minutes. 17% of patients were admitted, preventing 116 admissions. This saved approximately £45,820 through admission prevention. In addition, approximately a further £47492 was saved as this was PA led rather than consultant. Conclusions Prior to the employment of a PA, SAEC did not provide a consistent service, brought all patients to its surgical ward, and required employment of a second consultant. SAEC has improved patient flow and increased bed capacity whilst providing safe and high-quality care that is cost-effective.