Regarding the electric heating issue of sodium hydroxide storage tanks
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I work in the mechanical field and am not very familiar with chemical engineering; I hope to get help from everyone here. I need to design a sodium hydroxide storage tank. The client has specified that the tank should have heating, in the form of coiled tubes for steam heating, but actually electric heating is required. It’s essentially electric heating in the form of springs. My tank has a volume of 24 cubic meters and a diameter of 3 meters. I consulted manufacturers, and almost none of them were able to produce heating elements in this format, as the length of the resistance wires is too great to allow for that many turns. There is also another issue: such heat tracing tubes are considered vulnerable components. If they are installed in a spring-like manner and the cover on top is welded shut, it will be impossible to remove them for maintenance through a standard access point in the future. Therefore, I think the design provided to me by the client is unreasonable. I now want to change it to a flange-type immersion electric heater, as this would also make maintenance easier. But I’m not sure how to calculate how many electric heating elements of what power are needed for a container with a volume of 24 cubic meters and a diameter of 3 meters How is the heat dissipation area of an electric heating element determined? This is how I calculated it: there’s a formula Q=mc△t, which can be used to determine the amount of heat required to heat water to 20 degrees. Then, using the time required, the power can be calculated as q=pt. From this total power, it’s possible to determine the individual power of each heater and the number of heaters needed. I’m not sure if this calculation is correct, but how is the length of the heaters determined? Is the electric heater I chose suitable as well? According to the design requirements, heating is necessary, that is, a constant temperature is required. But mine is a heating type – is that feasible? Thank you all first
Temperature-controlled heat tracing cables (electric heat tracing wires) are used for fluid pipeline transportation as well as for the insulation and anti-freezing of equipment. It is widely used in applications that require frost protection and heat retention, especially in pipelines, valves, pumps, containers, tanks, reactors, etc., where fluids are prone to liquefaction, solidification, crystallization, or becoming viscous; it serves for purposes such as heat preservation, viscosity reduction, and prevention of blockages. Working principle and characteristics of temperature control cables: (Electric heat tracing wires) are strip-shaped temperature control heating elements whose electrical heating power adjusts automatically according to the system temperature. Its electric heating element consists of a layer of conductive plastic with a positive temperature coefficient that is evenly extruded between two parallel metal busbars. A conductive plastic bridge connected across two parallel busbars forms a resistive heating element that creates a parallel circuit; it is capable of automatically adjusting its output power in response to changes in the temperature of the system being heated, thereby regulating the amount of heat released and achieving automatic temperature control. This ensures that the system operates stably within the set optimal operating temperature range. Electric heat tracing is installed between the insulation layer and the outer wall of the pipeline (or equipment), using electrical heat to compensate for the heat loss that occurs during the transfer of the medium, thereby maintaining the temperature of the medium within a certain range and achieving the purposes of insulation to prevent freezing as well as prevention of condensation and blockages. Therefore, electric heating still requires an insulating layer, a moisture-proof layer, and a protective layer. The material, thickness, and structure of the insulation layer should be selected to ensure the desired operating temperature, as well as to meet requirements regarding thermal conductivity and related equations. Insulation layers used for frost protection generally should also have a moisture-proof layer. The parallel circuit structure of the heat tracing cable allows it to be shortened on-site at any time or extended within a certain range for use, making construction very convenient. It also allows for cross-overlap without concerns of overheating or burning out. Electrical heating uses the heat generated by semi-heating cables to compensate for the heat lost by piping, containers, tanks, and other storage and transportation systems, thereby ensuring that the operating medium in these systems remains within the temperature range specified by the process requirements. Therefore, in thermal design, it is first necessary to determine the heat loss of the process unit, and then use this value to determine the power and length of the heating cables required. Process parameters that need to be determined before calculating heat loss: 1. The temperature to be maintained as required by the system (medium) ； 2. Local extreme and average minimum winter temperatures ； 3. Outer diameter of the pipe ； 4. Surface area of the container ； 5. Types and thickness of pipeline insulation materials. The environment in which the pipeline is located, indoor or outdoor. Semi-hot cables are widely used in areas such as insulation of oil and gas pipelines and storage tanks, prevention of freezing in fire protection water supply pipes, melting snow and ice on ramps and rooftops, protection of equipment in basements, insulation of aquaculture facilities, and indoor heating. As a new type of energy-saving and environmentally friendly product, they are gradually replacing traditional insulation and anti-freezing measures.
Hello, electric heating can fully meet your requirements. Constant temperature can be achieved through an electrical control cabinet. I’ll tell you the specific calculation method! W=(CM△T)/t. Here, C represents the specific heat of the heating medium, and M represents the mass of that heating medium. △T represents the temperature rise in degrees, that is, the value of the final temperature minus the initial temperature. t represents the time. As an example, to fill a 1-cubic-meter water tank with water and heat it from 25 degrees Celsius to 50 degrees Celsius within 1 hour, what power rating is required for the electric heating element? How is this calculated? 1 cubic meter of water equals 1000 kg. The energy required is: Q = CM(T2 – T1) = 4200 * 1000 * (50 – 25) = 105000000 joules. The power required is 105000000 / 3600 = 291660 watts, or 29.1 KW. Considering that efficiency cannot be 100% and there are also heat losses, it is more appropriate to set the actual power requirement at around 40 KW. Finally, determine how many heating tubes you need by taking your installation into account. The manufacturer will provide you with the most suitable solution. I specialize in designing electric heating solutions for custom applications, and we have worked on designs with many manufacturers.