详情描述

Type III Removable Horizontal Spiral Plate Heat Exchanger



Structural Features

1. High thermal efficiency

       Due to the spiral channel design of the removable spiral plate heat exchangers of type III, the fluid flows within the channels. Fixed distance pillars or stamped distance blisters are welded onto the spiral plates to maintain the width of the spiral channels. Under the centrifugal force of the spiral flow cloud, the fluid can experience turbulence at a lower Reynolds number. Considering that the pressure drop should not be excessive, it is crucial to reasonably select the channel width and fluid velocity. During design, higher fluid velocities are generally preferred (with allowable design velocities of approximately 2 m/s for liquids and 20 m/s for gases), which promotes high fluid dispersion and better contact, enhancing the heat transfer efficiency of the spiral plate heat exchangers. In recent years, many domestic units have conducted heat transfer coefficient comparisons between spiral plate and tubular heat exchangers. For example, an auxiliary ammonia condenser for refrigeration units, replacing a tubular heat exchanger with a heat exchange area of F=75m² with a type III removable spiral plate heat exchanger with an area of F=30m², doubled the efficiency. Similarly, a heater under an ammonia synthesis tower, originally with a tubular structure and a heat exchange area of F=30.9m², was replaced with a type III removable spiral plate heat exchanger requiring only F=15.5m², thereby doubling its efficiency as well.

       2. Can effectively utilize fluid head loss

       In the fluid of Type III removable spiral plate heat exchangers, although there are no abrupt changes in flow direction or pulsations, due to the longer spiral channels and fixed-distance columns welded onto the spiral plates, the fluid resistance of this type of heat exchanger is generally greater than that of shell-and-tube heat exchangers. However, compared to other types of heat exchangers, the fluid resistance in the channels is primarily caused by friction with the spiral plates and collisions with the fixed-distance columns, which can lead to turbulent flow. This, in turn, increases the heat transfer coefficient, allowing the Type III removable spiral plate heat exchangers to effectively utilize fluid pressure head losses.

       3. Resistant to clogging

       In recent years, numerous studies have focused on the issue of fouling in heat exchangers, as fouling significantly impacts their heat transfer efficiency. In Type III removable spiral plate heat exchangers, since the medium flows through a single channel and the allowable velocity is higher than in other types of heat exchangers, fouling is less likely to accumulate. If fouling does settle in a section of the channel, the cross-sectional area of that section decreases, and under a certain flow rate, a reduced cross-sectional area results in an increased local velocity, which acts as a flushing effect on the fouled area. In shell-and-tube heat exchangers, if fouling accumulates on a heat exchange tube, the local resistance of that tube increases, restricting flow and reducing velocity. The medium then diverts to other tubes, rebalancing the resistance of each tube within the heat exchanger. This causes the velocity of the fouled tube to decrease over time, making it more prone to further fouling and eventually leading to complete blockage. In chemical and oil refineries, shell-and-tube heat exchangers often experience fouling in the tubes, leading to clogging. However, in Type III removable spiral plate heat exchangers, with their self-cleaning action, the rate of fouling formation is approximately one-tenth that of shell-and-tube heat exchangers.

       When encountering blockages, overseas often uses acid washing or hot water cleaning, while domestically, steam blowing is predominantly used, which is more convenient and efficient than hot water cleaning.

       4. Utilizes low-temperature heat sources and can control the outlet temperature. To enhance the heat transfer efficiency of the removable spiral plate heat exchanger type III, it is necessary to increase the heat transfer driving force. When both fluids operate in a fully countercurrent manner within the spiral channels, their logarithmic mean temperature difference is substantial, which is conducive to heat transfer. Analyzing from the empirical data used in heat exchanger design, the removable spiral plate heat exchanger type III allows for a low minimum temperature difference, enabling heat exchange even when the temperature difference between the two fluids is 3°C. Due to the low allowed temperature difference, countries worldwide utilize this type of heat exchanger to recover low-temperature thermal energy.

       Type III removable spiral plate heat exchangers feature two longer, uniformly spiral channels, allowing for even heating and cooling of the medium, thus controlling the outlet temperature.

       5. Compact structure

       A 1.5m diameter and 1.8m width Type III removable spiral plate heat exchanger, with a heat transfer area of up to 200m², and a heat transfer area per unit volume approximately three times that of a shell-and-tube heat exchanger.

       6. Sealed structure is reliable

       Currently, the Type III removable spiral plate heat exchangers in use have both channels sealed with welding (irreversible) and end cover clamping (removable). The irreversible seal ensures both welding quality and prevents internal leakage between the two media. The removable type uses end covers with a full-seal plate, and as long as the spiral channel end surfaces are smoothly machined, it can prevent fluid from one side from bypassing to the other side.

       7. Low temperature difference stress

       TheⅢ-type removable spiral plate heat exchanger features allow expansion. Due to its two longer spiral channels, when the spiral plates are heated or cooled, they can extend and contract like the mainspring in a clock. Each turn of the spiral has one side for hot fluid and the other for cold fluid, with the outer turns contacting the atmosphere. The temperature difference between the spirals is not as pronounced as between the tubes and shell in a tube-shell heat exchanger, thus avoiding significant temperature difference stress.


Technical Specifications