In the dynamic landscape of graphite manufacturing, where precision and efficiency are paramount, the integration of innovative technologies becomes a key driver for progress. One such advancement that significantly elevates the efficiency of pneumatic conveying systems in the graphite manufacturing industry is the strategic implementation of heat recycling. This pioneering approach not only addresses environmental concerns but also contributes to substantial gains in energy efficiency and overall operational performance. The utilization of pneumatic conveying is prevalent across diverse industries for the transportation of granular materials between locations. For instance, projections from the solids processing sector indicate an anticipated expansion of the pneumatic conveying system (George E. et al., 2018) market to reach $30 billion by 2025. The fluidized dense-phase mode of pneumatic conveying for fine powders is gaining popularity across diverse industries, including power, chemical, cement, refinery, alumina, pharmaceutical, lime stone, among others. This is attributed to several advantages, such as lower gas flow rates, reduced power consumption, decreased conveying velocities, enhanced control over product quality, minimized pipeline sizing, reduced wear rates, and improved workplace safety (Baldeep Kaur,et al., 2017) examined that the accurate prediction of the total pipeline pressure drop is crucial for the dependable design of a pneumatic conveying system. The transportation of bulk solids is predominantly accomplished through the widespread use of pneumatic conveying (Néstor Vásquez, et al., 2003) employed the dense phase plug flow regime. Research efforts have concentrated on comprehending and forecasting the characteristics of gas-solid flow as well as process performance across a wide spectrum of conditions. The objective is to (Shibo Kuang et al., 2019) reported that attain an optimal design and control of the system.
In the graphite manufacturing industry, pneumatic conveying systems play a crucial role in efficiently transporting graphite particles from one process to another. The characterization of a pneumatic conveying system relies on factors such as the product's properties (particle size, abrasion sensitivity), the system's installation location (transport distance, number of curves), and the equipment and peripheral systems (silos, explosion counter systems), along with considerations of installation and operational expenses. These systems are employed for the manipulation of solid particulate materials, where a gas-solid mixture, typically utilizing air, transports the particulate material to its intended destination. Pneumatic conveying systems primarily consist of an appropriate gaseous fluid source, a mechanism for feeding the material to be conveyed, a conveyor system for displacing the material, a container for packaging the material, and a gas separation filtering system following transport, as illustrated in Figure 1(a).
Energy demand has generally increased when industrial growth has occurred (Adriano Gomes de Freitas et al., 2019) created an empirical model to assess the transport efficiency through the proposed equipment and its feasibility, with the goal of identifying optimal points for energy efficiency. Pneumatic systems have found extensive use across various industries, consuming over billions of kilowatt-hours of electricity globally each year. Efforts are made to enhance the efficiency of pneumatic systems (Yan Shi et al., 2019) provide a technique for assessing and quantifying the power of pneumatic systems, establishing a groundwork for optimizing and designing pneumatic systems with energy-saving considerations. The overall pneumatic power efficiency of a pneumatic system typically ranges from 2% to 20%, and this varies significantly based on the specific configuration of the system. Compressed gas is utilized in pneumatic transportation, a widely adopted method for handling materials in industrial production processes. Because of its benefits, including the affordability of its components and the system's ease of maintenance, pneumatic systems have found extensive use across various industries (M Saadat et al., 2016) introduced the modelling and control aspects of an innovative Compressed Air Energy Storage (CAES) system designed for wind turbines. Currently, pneumatic systems serve as a primary energy consumption system worldwide (Marcus Budt,et al., 2016) according to D wolf, a comprehensive examination is provided, covering a wide range of concepts related to Compressed Air Energy Storage (CAES) and the various options for Compressed Air Storage (CAS). This review assesses the distinctive merits and drawbacks of each concept, incorporating the application of the energy concept to CAES to enrich the foundational comprehension of this energy storage method.
In a pneumatic system, power is conveyed and regulated using compressed air within a circuit(S W Mei et al., 2015) reported a comprehensive design blueprint for the Non-supplementary Fired Compressed Air Energy Storage (NFCAES) system, covering system design, modelling, efficiency evaluation, protection, and control. Notably, it outlines the design principles for the multistage regenerative system, specifically a heat recovery system designed to fully recycle and harness waste heat from compression. This also includes a method for evaluating the overall system efficiency. Inadequate handling of powder within an industrial furnace operation can lead to suboptimal furnace performance, introducing inaccuracies in mass balance, pipeline erosion from particle impacts, and the overloading of bag houses due to attrition and elutriation of fines. The absence of a reliable measurement for gas-solid flow rate can result in economic and environmental issues due to airborne concerns (Paulo Vasconcelos, et al., 2011) reported that fundamentals of powder pneumatic conveying and fluidization are discussed.
According to Freitas et al., 2019, Yan Shi et al., 2019, M Saadat et al., 2015, D Wolf et al., 2014, S W Mei et al., 2015, reported that the efficiency of pneumatic conveying systems can be significantly increased with the use of heat recycling in order to overcome this difficulty. The literature mainly investigated the pneumatic conveying system and energy conservation measures. When waste heat is rejected from a process at a temperature sufficiently above the surrounding air temperature, it is possible to economically recover heat energy for some practical purposes.
This type of investigation has been studied by several investigators. Various experiments were done in this area to conserve energy and to improve the efficiency of the system.
Improving heat transfer through the incorporation of longitudinal vortex generators in the shape of winglets (Shambhu Kumar Rai et al., 2017) reported that the performance of the heat exchanger will be improved by mounting Protrusion on the surface. This study aimed to enhance boiler efficiency through two methods: utilizing recovered heat for fuel drying and incorporating a 5hp blower to capture flue gas from a stack and direct it onto the fuel screw conveyor (Ratchaphon Suntivarakorna et al., 2016) resulted reveal that the adoption of heat recovery and fuel drying leads to a 3% reduction in fuel moisture content, resulting in a 0.41% increase in boiler efficiency. Preheating the air results in a temperature rise of 35°C or a 0.72% improvement in boiler efficiency. The air control demonstrates an average accuracy of 89.15%, signifying a 4.34% boost in boiler efficiency. The organic Rankin cycle (ORC) proves to be a fitting technology for harnessing low-grade temperature heat derived from diverse renewable energy sources like biomass, geothermal, and solar. Additionally, the (waste) heat generated from various processes can also be effectively utilized in these cycles (Michel De Paepe et al., 2016) investigated ways to use renewable energy sources while also working to increase the effectiveness of thermodynamic cycles. Many scholars are working in this area as a result of the rising global need for energy and environmental concerns. Utilising heat transfer correlations found in the literature, a helical coil heat exchanger was created.
The analytical study of the vapour compression refrigeration system incorporating a matrix heat exchanger is conducted to enhance the system's coefficient of performance (Chetan Papade et al., 2016) reported that work examines the effectiveness of a VCRS (Vapour Compression Refrigeration System) without & with a matrix heat exchanger.
The utilization of combustion air pre-heaters in sizable boilers commonly located in thermal power stations that generate electricity from sources such as fossil fuels, biomasses, or waste materials(S. Sudhakar et al .,2016) was developed a air preheater to increase the process thermal efficiency. Assessing the performance attributes of a vapour compression heat pump (VCHP) designed for concurrent space cooling (summer air conditioning) and the provision of hot water (Fatouh, M et al., 2011) the findings indicated that the Coefficient of Performance (COP) rises with higher evaporator water inlet temperatures and decreases as the condenser water inlet temperature increases. The concept of heat exchangers is pivotal in refrigeration and air conditioning systems. This paper undertakes a review of the literature concerning heat exchangers and explores modifications aimed at enhancing their efficiencies (T.Venkateshan et al., 2015),employed the basic study of heat exchangers, different heat exchanger layouts, compact heat exchangers, and the role of nano fluid in improving heat transfer were the main topics of this work. Enhancing the coefficient of performance necessitates a reduction in compressor work and an increase in the refrigerating effect. Adjustments to the condenser aim to augment the degree of sub-cooling of the refrigerant, thereby increasing the refrigerating effect or requiring more cooling water in the condenser (Shruti Saxena , 2015) stated that to minimize losses in the evaporator, condenser, and compressor, simultaneous efforts should be made to enhance the thermodynamic performance of the evaporator, condenser, and compressor. Creating a functional prototype involves optimizing the utilization of waste heat by installing a water chamber between the compressor and condenser (Dhananjay Parmar et al., 2017) examined that the highest temperature is noted in the forced water circulation condition as opposed to conditions without water and with water, resulting in an enhanced Coefficient of Performance (COP) improvement of approximately 68.83%. An integrated refrigeration system (IRS) comprising a gas engine, a vapour-compression chiller, and an absorption chiller is established and subjected to testing (Sun et al, 2008) developed, Set up and tested is an integrated refrigeration system (IRS).
To the best of our knowledge no attempt has been made to
study the potential of heat recycling to improve the efficiency of pneumatic conveying systems within the graphite manufacturing industry. No one has done work on improvement of Coefficient of performance with increasing availability of pneumatic conveying along with reduces in cost of mild steel pipe material. Also work on the effectiveness and heat transfer rate of heat exchanger respectively.
Figure 1(a) describes about components of typical pneumatic conveying system used in graphite manufacturing plant to conveyed graphite material from storage bunkers to operational shops and from shops to silos. Figure 1(b) describes about components of the SVCRS mechanism these following of main components in this system are Compressor, Condenser, Expansion valve /Metering Device Evaporator, Piping material and Refrigerant. Simple Vapour Compression Refrigeration Systems is an advanced technique of an air refrigeration system, in VCRS a suitable refrigerant is used, at an ambient temperature & pressures and temperatures, it condenses and evaporates. (Cao Y et al., 2018) studied, the refrigerants most frequently utilized are carbon dioxide (CO2), sulphur dioxide (SO2) and ammonia (NH3). Throughout in the system the used refrigerant is circulated (one by one condensation and evaporation), and does not exit the system. As the refrigerant evaporates throughout the cold chamber, it absorbs latent heat from the brine (salt water) that is used to circulate it. When it condenses, the latent heat is transferred to the circulating water in the cooler. It is a latent heat pump because the vapour compression refrigeration mechanism pulls latent heat from the brine and transfers it to the cooler. Today, all refrigeration is done with a vapour compression refrigeration method.
Compressed Air Dryer - It's employed to take the water vapour out of compressed air. Numerous industrial and commercial establishments frequently contain compressed air dryers. Air compression collects pollutants from the atmosphere, such as water vapour. Pipe condensation results from the compressed air's rising dew point relative to ambient air as it cools downstream of the compressor. Users of compressed air may experience a number of operational issues due to excessive water in the vapours or fluid state. These include fouling of processes and products; the dew point often identifies the performance traits of these organisms.
Problem formation:-In several industries compressed air used in various applications and special application of compressed air in graphite manufacturing industries and in chemical viscose fibre industries. In these industries compressed air is used in pneumatic conveying system to conveyed material from one place to another place without contamination and at low cost, but problem is occurs when this compressed air have moisture and this moisture creates contamination in material and corrosion with choking problem in pneumatic lines accessories and in overall system. Moisture causes for hampering all these equipments with system efficiency and accuracy as well. This can have a negative impact on the production process or end product. For a very long time, issues caused by moist air in pneumatic mild steel pipes were just accepted as inevitable. Scaling and rusting & clogged orifices can cause these controls to malfunction, which could lead to product damage and it will lead an expensive shutdowns along with high labour and material cost.
Methodology: The chilled air is transferred through an additional heat exchanger in which high temperature compressed air is circulated around it in order to recycle the low temperature of the outlet air from the evaporator. Here, there is an air-to-air heat exchange between the incoming hot, humid air and the ejected dry, chilly air. Thus, we can benefit from two things:
- The hot compressed air to be cooled before entering the evaporator. It minimizes the stress on it, which allows the compressor's size to be decreased.
- And For controlling of re condensation of out coming air of compressor to the pneumatic system input air temperature to be increased.