Condensation Line Research Articles

Comparison of the thermofluidic behaviors of 2-m nitrogen-charged cryogenic loop heat pipe under anti-gravity and horizontal conditions

One of the main advantages of a cryogenic loop heat pipe (CLHP) is its heat transfer capability over long distances and operability under anti-gravity conditions. However, there are only a few studies on the thermal characteristics of long-distance CLHPs. It is essential to investigate the effect of a hydraulic head on CLHP performance to enhance the utilization of CLHPs in various applications. This study investigated the thermofluidic behaviors of a 2-m nitrogen CLHP with a capillary starter pump (CSP) under horizontal and anti-gravity conditions where the evaporator was 350 mm higher than the condenser. The novelty of the study is to reveal the heat transfer characteristics and operating mechanisms under anti-gravity conditions based on comparisons with experimental results under horizontal conditions. In the CLHP, a fine stainless-steel porous wick with a pore radius of 1.0 μm and permeability of 1.3 × 10−13 m2 was used for an evaporator and the CSP. The lengths of the vapor line, condenser, and liquid line were 2000, 1500, and 2000 mm, respectively. When a heat load of 4 W was applied to the CSP and evaporator, the CLHP successfully started with an initial cooling condition called a supercritical startup under anti-gravity conditions. The startup temperature behaviors were compared under horizontal and anti-gravity conditions. The thermal resistance of the CLHP with a stepped-up evaporator heat load and various CSP heat loads was evaluated for two CLHP orientations. The CLHP stably operated under evaporator heat loads of 4–24 W (horizontal) and 4–20 W (anti-gravity) for three CSP heat loads of 0, 2, and 4 W. The effect of the CLHP orientation on the thermal resistance with various CSP heat loads is discussed. This study enhances the applicability of the long-distance CLHP to various applications with a high degree of postural freedom by revealing the operating mechanism and thermal characteristics of the long-distance CLHP under anti-gravity and horizontal conditions.

Analysis of processed natural gas injection on hydrate formation in high pressure refrigerated condensate lines

Natural gas and condensate are exposed to hydrates formation at high pressure and low temperature in the presence of traces of water. Hydrates formation results in blockage of pipelines and equipment leading to plant shutdown and production losses. This study intends to find a novel hydrate prevention process for high pressure refrigerated condensate (HPRC) lines. HPRC is utilised as lean oil for enhanced liquified petroleum gas recovery in absorption process. This research was conducted by performing fifteen tests in which various processed natural gas (PNG) samples were injected into different HPRC samples using Aspen HYSYS software. The results showed lowering of the hydrates formation temperature in the HPRC at constant pressure. By capitalizing on in-house resources and reducing dependence on traditional hydrate inhibitors, this innovative approach offers cost-effectiveness and readily available hydrate inhibitor for HPRC lines in gas processing facilities. Moreover, it has been found that PNG samples with a relatively higher percentage of methane are more effective in lowering the hydrate formation temperature when injected into the HPRC lines. This study will enable hydrates researchers in reducing hydrates management costs in HPRC lines and invite hydrates prevention research in all areas capitalizing on in-house resources and reducing external dependence.

Force Field for Calculation of the Vapor-Liquid Phase Equilibrium of trans-Decalin

Based on the TraPPE force field, previously unknown values of the parameters of the intermolecular interaction potential of trans-decalin were determined. Parametrization was carried out using experimental data on saturated vapor pressure and density at atmospheric pressure. The found parameters make it possible to adequately describe the boiling and condensation lines of trans-decalin and also predict the critical values of pressure, density, and temperature with satisfactory accuracy. Calculations of vapor-liquid phase equilibrium conditions for a binary CO2—trans-decalin mixture in supercritical conditions for CO2 were carried out. When quantitatively comparing the calculated values with experimental data, an underestimation of pressure at a temperature of 345.4 K by 30% is observed, which decreases to 5% for temperatures up to 525 K.

BIO-RSA vs metal augmented baseplate in shoulder osteoarthritis with multiplanar glenoid deformity: a comparative study of radiographic findings and patient outcomes.

Reverse shoulder arthroplasty (RSA) requiring extensive reaming to address severe glenoid bone loss increases the risk of glenoid medialization and baseplate failure. We hypothesized that i) metal augmented baseplate prevents the medialization of the joint line and preserves glenoid bone stock similarly to BIO-RSA; ii) bone graft viability and healing in BIO-RSA patients become compromised over time. Eighty-one patients (83 shoulders) underwent glenoid lateralization with bone (BIO-RSA group, 44) or metal augmented baseplate (MIO-RSA group, 39) and a minimum follow-up of 24 months were included. The orientation and direction of glenoid erosion was identified and recorded using computerized 3D planning. Active range of motion, and the Western Ontario Osteoarthritis of the Shoulder (WOOS) index were assessed before arthroplasty and at the last follow-up visits. Radiographic changes around the glenoid and humeral components were assessed. Healing and thickness of bone graft were evaluated by predefined criteria. Postoperative global glenoid inclination (β angle) and retroversion were also measured. Delta scores of active anterior elevation were higher in the MIO-RSA group (p= 0.027). The differences in the other planes of shoulder motion and in WOOS index scores between the groups were not significant. Preoperative glenoid retroversion was higher in BIO-RSA patients, glenoid inclination was similar in both groups. Type B2 and B3 glenoids had a posterior-central (91%) and posterior-superior (90%) erosion with a mean posterior humeral head subluxation of 76% and 78%, respectively. The direction of erosion in Type E2 and E3 glenoids was posterior-superior, with a mean posterior humeral head subluxation of 74%. The rate of high position of the glenosphere was higher in the BIO-RSA group (p = 0.022), while the values of β angle and postoperative retroversion were similar in the two groups. BIO-RSA group showed radiolucent lines < 2mm around the bone graft in 16 patients (36.4%) and decreased thickness in 15 (34.1%). Incomplete baseplate seating was found in 4 MIO-RSA patients (10%). We found higher rate of humerus condensation lines in MIO-RSA patients (p= 0.01) and higher rate of cortical thinning and tuberosity resorption in the BIO-RSA group (p= 0.027 and p = 0.004, respectively). Metal augmented glenoid is a suitable alternative to BIO-RSA to preserve bone and prevent the medialization of the joint line in arthritic glenoid with multiplanar glenoid deformity. Bone and metal augmentation provided satisfactory clinical outcomes. Bone graft resorption in BIO-RSA patient raise concern about the risk of baseplate loosening and requires further long term studies.

Modeling of a low-temperature gas treatment system

Objective. The main purpose of the work is: investigation of the effect of changes in technological parameters on the efficiency of the separation process and determination of optimal technological modes of operation of gas field X CNTS in the separation process.Method. The problem was solved in the KBC Petro-SIM computer program and the LTS model was built. To conduct the study, a model of the LTS was built in the KBC Petro-SIM computer program.Result. The results obtained with the help of it showed: with the current composition of the gas with a decrease in temperature for every 2oC, with other technological indicators being equal, the specific condensate yield increases in the range from 15 to 30%, and the lower the temperature, the higher this percentage. When the pressure on the throttle decreases by every 0.4 MPa, the condensate output increases, if the pressure drops below 1.8 MPa, the specific condensate output will begin to decrease, which is explained by the pressure drop below the maximum condensation line of the phase diagram. The change in gas flow within the design values did not affect the operation of low-temperature separation. At any available low temperature and high pressure at the inlet to the ILTS, the most optimal mode will be when the pressure after the throttle is maintained within 1.8 - 1.9 MPa. The maximum specific yield of gas condensate (48.21%) was obtained at a pressure at the inlet to the ILTS of 5.1 MPa, a temperature after the heat exchanger of minus 2oC and a pressure drop at the throttle of 3.05 MPa. As part of the numerical research, the following results were obtained: with an increase in the pressure at the inlet to the ILTC, the change in the specific output of the gas condensate is insignificant, but with this parameter it is possible to create a larger pressure drop on the throttle; with a decrease in the gas temperature at the outlet of the heat exchanger, the specific yield of the gas condensate will increase; with an increase in the pressure drop at the throttle, the specific output of the gas condensate increases until the pressure after the throttle reaches the range of values of 1.8 – 1.9 MPa. In this interval, the maximum specific condensate yield is achieved. With a further increase in the pressure drop on the throttle, the specific output of the gas condensate decreases. This is explained by the phenomenon of retrograde condensation, since the maximum condensation line is in the range of these pressures.Conclusion. Based on the results of the work, it was found that the developed software module can be used to solve the emerging series of problems. The results of the work show the suitability of the proposed method for practical purposes.

Experimental study on the thermal performance of a dual compensation chamber loop heat pipe with dual vapor and condenser lines

Experimental study on the thermal performance of a dual compensation chamber loop heat pipe with dual vapor and condenser lines

Bio-corrosion Phenomenon of Titanium Grade 2 Tubes in Condenser of a Steam Power Plant

Titanium is widely applied for the tube condenser in Indonesia’s powerplant especially those that use seawater for the cooling system, because it has excellent properties both mechanical and physical. Leak in titanium in seawater environment occurred, but on the contrary, the leak of titanium tube in the brackish environment frequently occurs. Many defense tasks such as plugging, cleaning, and adjusting operations have taken, but the result remains the same. Until it was decided to perform an overhaul for the condenser and tube mapping using ECT. It was discovered that 80% of the total tube have been wall lost thickness so that total retubing must be conducted. Chemical elements consist of oxygen (O), sulfur (S), and chlor (Cl) were found during DT and NDT. This study aims to analyze the factors causing this severe titanium tube leak in the condenser. This case is like previous research even though it occurred in different equipment and water feed. Sulfur elements came from the excretion of aquatic biota such as mussel. Plentiful mussels grow along the cooling condenser line because biocide injection is difficult to perform. The method used to find the root cause of the problem is performing several tests of titanium tubes samples. The results show titanium tube from the condenser has experienced bio-corrosion. This is supported by the presence of three elements that allow the bio-corrosion reaction to occur by forming titanium sulfide, namely O, S, and Cl.

Experimental Study and Visual Observation of a Loop Heat Pipe with a Flat Disk-Shaped Evaporator under Various Orientations

In this study, visualization treatment was applied to the flat disk-shaped evaporator of a loop heat pipe. By observing the liquid/vapor behavior inside the evaporator and compensation chamber, the effects of orientation on the performances during startup and during a step-increase in heat load were investigated. With water as the working fluid, the loop heat pipe was tested under three typical orientations of φ = −90°, φ = 0°, and φ = +90°. The startup time was the shortest for the φ = −90° orientation but there could be a slight temperature overshoot, resulting in an unsmoothed startup process. The startup speeds under the φ = 0° and φ = +90° orientations were similar, both without any significant temperature overshoot. The orientation could significantly change the heat leak and, therefore, the operating temperature and the heat-transfer limit. For the φ = +90° and φ = −90° orientations, the heat-transfer limits were about 71% and 157% of the value at the φ = 0° orientation, respectively. Based on visual observations, for the loop heat pipe operating in gravity-driven mode, there could be two different paths for the working fluid to return to the evaporator, namely, along the vapor line for low heat loads and along the condenser and liquid lines for relatively large heat loads, respectively.

Effect of Divalent Cations and Other Ions on the Tetrahydrofuran Crystal Inhibition of Quaternary Ammonium Salts-Relevance to the Efficiency of Gas Hydrate Quaternary Anti-agglomerants.

Gas hydrate anti-agglomerants (AAs) are a class of low-dosage hydrate inhibitor that are used to prevent plugging of gas hydrates in oil and condensate upstream flow lines. Industrial AAs are mostly cationic surfactants which are "hydrate-philic", i.e., they are designed to interact with and modify gas hydrate crystal growth. Tetrahydrofuran (THF) hydrate crystal growth studies have been used for many years to determine useful functional groups to incorporate into AA surfactants. In particular, quaternary ammonium and phosphonium salts with optimized alkyl groups show good THF crystal growth inhibition, which is a key property for AAs. AAs are often screened and tested in model brines containing sodium chloride despite the produced water containing various divalent cations. Recent studies have shown that AAs performed better when tested in brines containing both sodium and calcium ions rather than just sodium ions. Here, we present THF hydrate crystal growth studies on quaternary ammonium and phosphonium salts and other related molecules including guanidinium salts and amine oxides. Tests were carried out with a variety of cations including sodium, calcium, magnesium, and lithium at identical pre-determined subcooling, in order to investigate the effect of the ion size and charge density on the crystal growth inhibition. We also investigate the effect of using the more polarizable iodide ions compared to chloride ions. Our results show that crystal growth inhibition in solutions with calcium ions is somewhat greater than that with sodium ions, in agreement with past studies on the effect of AA performance with mono- and divalent cations. However, the variation does not seem to be primarily related to the charge density and polarizing ability of the cations. This study therefore provides evidence that AAs should be tested in brines containing all the ions present in the produced water and not just sodium chloride brine.

Factors affecting stress shielding and osteolysis after reverse shoulder arthroplasty: A multicenter study in a Japanese population

BackgroundStress shielding and osteolysis around the humeral stem after reverse shoulder arthroplasty causes loosening and periprosthetic fractures and reduces bone stock during revision surgery. In Japanese patients, who have relatively small bodies, different characteristics may exist regarding the occurrence of these changes compared with the characteristics of Westerners, who have relatively larger frames. The purpose of this multicenter study was to investigate the incidence and clarify the predictors of stress shielding and osteolysis in Japanese individuals who underwent reverse shoulder arthroplasty. MethodsThe occurrence of stress shielding and osteolysis was investigated in 135 shoulders that had undergone reverse shoulder arthroplasty at least 2 years prior in five Japanese hospitals. During post-surgical follow-up, which was conducted every 3 months, the locations of the stress shielding occurrences, such as cortical thinning and osteopenia (which primarily occurred in zones 1, 2, and 7, where 1 is the greater tuberosity and 7 is the calcar part), spot weld, and condensation lines, were recorded. Cases without any abnormal findings on radiographs obtained up to ≥2 years after surgery were regarded as having no abnormalities. Finally, the predictors of cortical thinning and proximal humeral osteolysis were assessed using univariate and multivariate regression analyses. ResultsCortical thinning and osteopenia occurred in 68 shoulders, a condensation line occurred in 37 shoulders, and spot weld occurred in 23 shoulders. In particular, greater tuberosity and calcar osteolysis occurred in 40 and 47 shoulders, respectively. Long stem, cementless stem, and a larger proximal filling ratio were independent predictors of cortical thinning and osteopenia, whereas a cementless stem, larger metaphysis diameter, and a larger proximal filling ratio were associated with proximal humeral osteolysis. ConclusionsThe predictors of stress shielding and osteolysis included the use of long stems, cementless stems, larger proximal filling ratios, and larger metaphysis diameters. Level of evidenceretrospective comparative study (Level III).

Thermodynamic analysis of solar assisted steam distillation system for peppermint oil extraction

AbstractScheffler reflector (10 m2) integrated peppermint oil (PO) extraction distillation system is developed. Optical loss in reflector and thermal loss in solar still, steam line, and condenser are determined. A solar distillation system of peppermint plants is also subjected to thermal energetic and exergetic study. Exergy and optical efficiencies are 27.58% and 52.25%, respectively, with an average irradiance of 970.5 W/m2 and 6 kg of peppermint for 4 h. Thermal efficiency of solar still, steam line, and condenser are 95.90%, 95.68%, and 87.96%, respectively. Efficiency of system and oil yield per unit of energy consumed is 41.98% and 6.24 ml/kWh, respectively, without insulating steam line. System's efficiency is 46.36%, with an improvement of 2.67% in energy gain by insulating the steam line. Thermodynamic analysis of developed solar steam distillation system (SSDS) for PO extraction will help in finding out energy saving potential at various parts of distillation unit and in improving the performance of distillation unit. This research would provide energy conservation opportunities in various parts of PO extraction SSDS. Exergy analysis and detailed investigation of condenser and steam line are also performed. As a result, incorporating solar energy into PO extraction technology improves opportunities for the source of income in rural areas and increases both income and level of food security for farmers.Practical applicationsThis research would provide energy conservation opportunities in various parts of peppermint oil (PO) extraction solar steam distillation system. Exergy analysis and detailed investigation of condenser and steam line are also performed. As a result, incorporating solar energy into PO extraction technology improves opportunities for the source of income in rural areas and increases both income and level of food security for farmers.Novelty StatementMentioned literature includes thermodynamic analysis of oil extraction system available for crops such as rosemary leaves, basil leaves, etc. Thermodynamic analysis of such a system is limited to these crops and applied to other crops like peppermint, eucalyptus, lavender, etc. As these crops possess different chemical properties and have large potential in essential oil market, a comprehensive thermal analysis is needed to identify various thermodynamic parameters to extract peppermint oil (PO) using solar‐assisted steam distillation system. Present work aims to identify energy and power loss due to convection and radiation at different parts of a solar distillation unit. Exergy analysis and detailed investigation of condenser and steam line are also performed. This research would provide energy conservation opportunities in PO extraction solar steam distillation system. Furthermore, the outcomes of present study have been compared with previously published studies.

Oxyvinylenelactam Polymers-A New Class of Lactam-Based Kinetic Hydrate Inhibitor Polymers.

The deployment of kinetic hydrate inhibitors (KHIs) is a chemical method for the prevention of gas hydrate plugging in gas, condensate, and oil production flow lines. Polymers made using the monomer N-vinylcaprolactam (VCap) are one of the most common KHI classes. Alternative classes of polymers containing caprolactam groups are rare. Here, we present a study on oxyvinylenelactam polymers and copolymers with pendant piperidone or caprolactam groups. Low-molecular-weight homo- and copolymers were obtained. The nonrotating vinylene groups impart rigidity to the polymer backbone. Poly(oxyvinylenecaprolactam) (POVCap) was insoluble in water, but poly(oxyvinylenepiperidone) (POVPip) and OVPip:OVCap copolymers with 60+ mol % OVPip were soluble with low cloud points. KHI screening tests were carried out using the slow constant cooling method in steel rocking cells. POVPip was water soluble with no cloud point up to 95 °C but showed a poor KHI performance. In contrast, OVPip:OVCap copolymers with about 60–70 mol % OVPip were also water soluble and showed a reasonable KHI performance, better than that of poly(N-vinylpyrrolidone) but not as good as that of poly(N-vinylcaprolactam). Surprisingly, several additives known to be good synergists for VCap-based polymers showed negligible synergy or were antagonistic with the 62:38 OVPip:OVCap copolymer with regard to lowering the onset temperature of hydrate formation. However, a blend with hexabutylguanidinium chloride showed a strong effect to delay the onset of rapid hydrate formation.

Critical point and Bose-Einstein condensation in pion matter

The Bose-Einstein condensation and the liquid-gas first order phase transition are studied in the interacting pion matter. Two phenomenological models are used: the mean-field model and the hybrid model. Free model parameters are fixed by fitting the lattice QCD data on the pion Bose condensate density at zero temperature. In spite of some minor differences the two model demonstrate an identical qualitative and very close quantitative behavior for the thermodynamic functions and electric charge fluctuations. A peculiar property of the considered models is an intersection of the Bose-Einstein condensation line and the line of the first order phase transition at the critical end point.

A Preliminary Study of Internal Corrosion in Condensate Pipelines at Geothermal Power Plants

In this study, we presented observations and analyze related to internal corrosion in condensate pipes in geothermal power plants. A damaged pipe of condensate pipeline taken from a power plant was investigated to determine the root cause of failure. The observation and failure analysis was carried out by visual and dimensional examination, chemical composition testing, macroscopic, and microscopic examination, Scanning Electron Microscope (SEM) examination with Energy Dispersed Spectrometer (EDS). The deposit in the pipe was analyzed by X-Ray Diffraction (XRD). The quality of the condensate fluid and their tendencies were determined by Langelier Saturation Index (LSI). Also, the corrosion rate of the pipe was simulated by condensate fluid by using a corrosion measurement system (Tafel polarization). The internal corrosion was found in the condensate line is strongly suspected to occur due to erosion-corrosion. Erosion corrosion is caused by insoluble and hard particles in the condensate fluid. The results of XRD found the presence of calcium-silicate compounds in the sediment that is suspected to be the cause of erosion particles. The reduction of the thickness of the bottom pipe wall and occurs in longitudinal directions the alleged damage to the pipe due to sediment corrosion. The presence of hard compounds and differential oxygen can accelerate the process of corrosion so that the corrosion rate in condensate pipelines was a category in the severe category based on NACE SP0775 standards.

Loop thermosyphons with porous coatings

The aim of this work is to experimentally evaluate the heat exchange of evaporation and condensation inside a new annular thermosyphon with horizontally located zones of evaporation and condensation, which are interconnected by a vapor line and a condensate line. The mini-tube of the liquid line is introduced coaxially into the cylindrical evaporator with a porous coating, thus an annular channel is formed between the tube and the porous coating of the evaporator. The purpose of this study is to determine the thermal resistance of the device and its components, as well as the temperature field along the thermosyphon. The considered thermosyphon guarantees a shorter start-up time, lowers the temperature of the evaporator walls, has a small temperature hysteresis with an increase/decrease in the transferred heat flux, and suppresses temperature pulsations inside an evaporator. The 130 mm long evaporator is made of copper tube (d out = 12 mm, d in = 10 mm). The wick is obtained by sintering copper powder. The working fluids R245fa and R600 were used. The thermal resistance of thermosyphon does not exceed 0.5 K/W, and of the evaporator 0.1–0.05 K/W).

Development of a Miniature Loop Heat Pipe for High Heat Flux Devices and Evaluation of Its Heat Transport Performance

This paper describes the design, fabrication, and the heat transfer performance of a miniature loop heat pipe (mLHP) aiming for cooling a small and high heat flux devices. For the design process, a one-dimensional numerical model was developed. Based on the numerical model, an mLHP was fabricated. The mLHP comprises an evaporator (15×16×t3 mm3), a condenser (12×12.5×t2 mm3) and transport lines (O.D.=1.6 mm, L=100 mm). The mLHP uses Shirasu porous glass (SPG) as a wick and is mainly made of stainless steel. The heat transport performance was investigated in horizontal attitude, anti-gravity (top heat mode) and gravity-assisted (bottom heat mode) with working fluid of water. When the condenser was dissipated by natural air convection, the mLHP performed 5-W (20-W/cm2) heat transport at 170-℃ heat source temperature in horizontal attitude. The thermal resistance was 7.9℃/W. In the bottom heat mode, the lowest thermal resistance of 2.6℃/W was obtained due to the gravity assist. Additionally, the mLHP was tested under the condition that the evaporator side was kept horizontal but the condenser side was bent upwards by 90 degree around the middle of transport lines. Consequently, in low heat load condition the bent mLHP showed the same performance with the bottom heat mode, but shifted to the horizontal mode as the heat load increased. Thus, the heat transport performance was comprehensively investigated for considering various uses.

REDUCTION OF ENERGY USE IN INDUSTRIAL FACILITY

Energy saving potentials related to steam generation and its usage in the medium size bakery are analyzed and presented. Input data needed for the investigation are gathered through detailed energy audit. Four energy savings measures are analysed in detail: 1) change of heat generator for space heating and domestic hot water preparation from steam boiler to condensing boiler, 2) reduction of heat losses from steam and condensate distribution lines, 3) heat utilization of return condensate and 4) replacement of the old, low efficiency steam boiler with high-efficient one. Implementation of these measures will result in substantial reduction of energy costs, ranging from 2.900 to 26.200 € annually. Interaction of all measures is analysed through energy efficiency improvement scenario, whose implementation will ensure significant energy cost savings, estimated at 40.793 € annually, with simple payback period shorter than 4 years. Implementation of presented measures will improve facility’s energy efficiency, represented through reduction of annual energy performance indicators by 6,14 %. Presented analysis revealed that steam generation and its usage in the industrial facilities offer a substantial potential for reduction of energy use and energy related cost.

Topping with a Natural Gas-Fired Combined Cycle Unit of a Coal-Fired Cogeneration Power Plant with Cross Connections

Thermal power plants (TPP) with cross connections and having a minimum reference fuel rate of 321 g/(kW h) prevail in the structure of the generating capacities in Russia. In practice, this characteristic is often above 500 g/(kW h). Application of parallel-type, dual-fuel combined-cycle units (CCUs) using coal as the main fuel, for improving the efficiency of power plants with cross connections is considered. Such CCUs have high efficiency and are suitable for modernization of operating subcritical power plants with cross connections. The power of CCUs with gas turbines manufactured in Russia or having a high degree of production localization in Russia can be as high as 200–250 MW. In all the cases, a new heat-recovery steam generator (HRSG) and a new steam turbine for a live-steam pressure of 12.8 and 8.8 MPa must be developed. The paper considers the process features of such dual-fuel cogeneration CCUs based on a 6FA gas turbine. A CCU thermal scheme is developed. Bled steam conditions under different operating conditions are determined considering the bypass of the main condensate and feedwater lines. GCU performance indices as a function of ambient air temperature are determined. In addition, an option was considered for modernizing the existing cogeneration power plant (TETs) in the town of Seversk by implementation of a dual-fuel CCU based on an 82 MW 6FA gas turbine and a T-96/122-8.8 steam turbine while maintaining the coal-fired power steam boilers in operation. It is demonstrated that the proposed modernization option makes it possible to reduce the fuel cost by approximately 240 million rubles per year while increasing the electricity delivery under cogeneration conditions by 1.7 times.

Mathematical model of evaporator-condenser

The basic provisions of the mathematical model of a condenser-evaporator in relation to air separation units are considered. All influencing quantities are shown, the main component blocks are highlighted, and the sequence of their solution is given. The model is based on a joint solution of the equations of hydrodynamics and heat transfer for tubular apparatuses using iterative calculations to clarify the initial values of the determining parameters both within individual blocks and between blocks. Application of the model is possible for both design and verification calculations with minimal changes. The development of the considered model is associated with the adaptation of its algorithm to machine calculation. One of the main directions is the inclusion of a database of parameters of working substances in the field of vapor-liquid states with the ability to automatically search and transfer the required thermophysical parameters on the evaporation and condensation lines in the model.

Shell and Tube and Plate Feedwaterheaters Effectiveness Comparison

The article presents the results of optimization computational experiments, which evaluated the effectiveness of the use of plate and shell and tube heat exchangers as feedwater heaters. The condensate is heated by water flowing through E35-3.9-440 steam boiler fire-grate cooling circuit. This boiler operates on sunflower husk. The capacity of bioelectric power stations, for which the computational experiment was done, varies from 2 to 27 MW. The steam pressure of the turbine inlet is 40 bar, the temperature is 440 °C. The heater in question is located on the main condensate line before the deaerator. It was done the comparison of the effectiveness of shell and tube and plate apparatus for this application. The optimal fluid velocities for both types of heat exchangers were also analyzed. The limitations of apparatuses design are considered. The computational experiment was done according to the "total costs" optimality criterion, only the design parameters of the heat exchangers were optimized. The experiment shows that the effectiveness of plate heat exchangers is higher in this case. An interesting dependence has also been recovered that relates the water temperature in the plate heat exchanger channels and its optimal velocity. The higher the water temperature, the higher its optimal velocity, which is associated with a decrease of viscosity when increasing the water temperature. This dependence is quite significant, and this fact makes it possible to consider that it is necessary to do optimization when designing this type of heat exchangers.