Spiral plate heat exchanger

Spiral plate heat exchanger is made of two parallel metal plates made of two spiral channels, heat exchanger between the hot and cold fluid through the spiral plate wall, especially in the treatment of slurry containing particles or fibers in suspension Materials or various viscous fluids.

The two most important links in the production process of spiral plate heat exchangers are plate rolling and fixed-length column welding. Murphy has a fully automatic spiral plate flexible production line. The welding of coiled plates and fixed-length columns is performed by CNC operations. The studs are welded with studs, and the welding current is automatically controlled to ensure that the studs are firmly welded, free of overburning and under-welding defects. The fixed-distance columns have high welding efficiency and accurate positioning; the plate rolling force is automatically controlled to ensure The spiral body after rolling has the best tightness, so that the positioning column and the plate are in proper close contact. The advanced fully automatic spiral board flexible production line brings the best product experience to customers.

Spiral plate heat exchanger overview

Spiral plate heat exchanger is an efficient heat exchange equipment, suitable for gas-gas, gas-liquid, liquid-liquid, as well as for condensation and liquid evaporation heat transfer. The product has the advantages of high heat transfer efficiency, strong dirt self-cleaning ability, good energy saving effect, small size, low price, reliable use and so on. It is widely used in heat exchange and waste heat recovery in industries such as pharmaceuticals, solvents, chemicals, rosin, dyes, and food.

Spiral plate heat exchanger structure and performance

1. Spiral plate heat exchanger is suitable for: gas-gas, liquid-liquid, gas-liquid convection heat transfer, can be used for steam condensation and liquid evaporation heat transfer, chemical industry, petroleum, medicine, machinery, electricity, light industry and textile industries Optional.

2. Spiral plate heat exchanger is rolled from two steel plates, forming two uniform spiral channels. The two heat transfer media can be fully countercurrent flow, suitable for small temperature difference heat transfer, easy to recover low temperature heat source and accurately control the outlet temperature .

3. The nozzle on the shell is tangential structure, the local resistance is small, the curvature of the spiral channel is uniform, the fluid flow in the device does not have a large reversal, and the total resistance is small, so the design flow rate can be increased to make it more competitive High heat transfer capacity.

4. The end face of the spiral channel is welded and sealed, with good sealing performance and reliable structure.

5. It is not easy to overhaul, especially when the internal board has problems, it is extremely difficult to repair. Some factories remove all the welding seams at both ends of spiral plate heat exchanger, re-flatten the board, weld it again, and then roll it. Anti-corrosion of plate heat exchanger is very important.

6. Mechanical cleaning is not possible. The production practice has proved that the spiral plate heat exchanger is not easy to block compared with the general tube heat exchanger, especially the suspended particles and impurities such as sand and small shells are not easy to deposit in the spiral channel. Analyze the reasons: First, because it is a single channel impurity, the deposit in the channel will form a circulating circulation will increase to wash it away; second, because there is no dead angle in the spiral channel, the impurities are easily washed out.

7. Because there is a fixed column spacing in the spiral channel, the fibrous impurities (cotton yarn, grass sticks, leaves, etc.) are not allowed to enter the heat exchanger.

8. Strictly control the cooling water outlet temperature below the scale temperature.

9. The common cleaning method is to use steam to blow clean or alkali wash, the steam is blown to take over, and the impurities are blown out from spiral plate heat exchanger.

Basic parameters

The nominal pressure PN of the spiral plate heat exchanger is specified as 0.6, 1, 1.6, 2.5Mpa (that is, the original 6, 10, 16, 25kg / cm2) (refers to the maximum working pressure that a single channel can withstand) The test pressure is the working pressure 1.25 times.

The material of the spiral plate heat exchanger in contact with the medium is carbon steel Q235A and Q235AF, and stainless acid steel is SUS321 and SUS304. Other materials can be selected according to user requirements.

Allowable working temperature: t = 0 ～ + 350 ℃ for carbon steel and -40 ～ 500 ℃ for acid steel of stainless steel. The range of temperature rise and pressure reduction is according to the relevant regulations of pressure vessel. When choosing Spiral plate heat exchanger, the fluid in the channel of Spiral plate heat exchanger should reach turbulent flow through proper process calculation. (General liquid flow rate 1m / Sec gas flow rate 10m / Sec).

A single device cannot meet the requirements for use and can be used in combination, but the combination must meet the following requirements:

Parallel combination, series combination: the distance between Spiral plate heat exchanger and the channel is the same.

Mixed combination: one channel in parallel and one channel in series.

Anti-clogging principle

Spiral plate heat exchangers are less prone to clogging than general tube-and-tube heat exchangers, especially suspended particulate impurities such as sand, small shells, etc., are not easy to deposit in the spiral channel, mainly reflected in:

1. Because it is the deposition of single-channel impurities in the channel, as soon as a revolving flow is formed, it will be increased to wash it away;

2. Because there is no dead corner in the spiral channel, impurities are easily washed out.

Features

1. High heat transfer efficiency (good performance)

It is generally believed that the heat transfer efficiency of the spiral plate heat exchanger is 1-3 times that of the tubular heat exchanger. There is no flow dead zone in a single channel of equal cross section. The disturbance of the fixed distance column and the spiral channel on the flow reduces the critical Reynolds number of the fluid. The heat transfer coefficient of the spiral plate heat exchanger can be up to 3000W / (㎡. K).

2. Effective recovery of low temperature heat energy

The spiral-plate heat exchanger is made of two rolls, recovers waste heat, and makes full use of low-temperature heat energy.

3. Strong operation reliability

The end surface of the spiral channel of the non-removable spiral plate heat exchanger is welded and sealed, so it has high sealing performance and ensures that the two working media are not mixed.

4. Low resistance

The nozzle on the shell adopts tangential structure. Low pressure loss, handling large-capacity steam or gas; self-cleaning ability, due to the spiral flow of the medium, dirt is not easy to deposit; easy to clean, can be washed with steam or alkaline liquid, simple and easy, suitable for installation of cleaning devices; The medium goes through a single channel, allowing the flow rate to be higher than other heat exchangers.

5. Multiple sets can be used in combination

When a single device cannot meet the requirements for use, multiple sets can be used in combination, but the combination must meet the following requirements: parallel combination, series combination, equipment and channel spacing are the same. Mixed combination: one channel in parallel and one channel in series.

Instructions for use

1. For the installation of equipment, the engineering and technical personnel who are familiar with the process of the system should be directed to determine the installation process plan in accordance with this manual and product quality certificate and the characteristics of the system process. In the installation, consideration should be given to using the direction of the pipeline to absorb thermal expansion as much as possible, and the installation should be level and aligned, and no additional stress can be generated to avoid adversely affecting Spiral plate heat exchanger. The pipeline connection should make the two processes completely countercurrent to improve the heat transfer effect.

2. The pipeline system should be cleaned before installation, and no mud, sand and other debris should be left in it; check whether the heat exchanger is damaged during transportation and whether large debris falls into the pipe mouth.

3. After the installation of spiral plate heat exchanger is completed, spiral plate heat exchanger and system should be tested for water pressure.

4. After the water pressure test is completed, spiral plate heat exchanger should be insulated.

5. The circulation must be softened or treated with medicine. (According to the low-pressure boiler water quality standard GB1576-96), due to improper water treatment, scaling can be done by chemical cleaning.

Troubleshooting

During the production process, due to the erosion of the tube sheet of the spiral tube sheet heat exchanger, cavitation and trace chemical media corrosion, the tube sheet weld often leaks, resulting in the mixing of water and chemical materials, the production process temperature is difficult Control, resulting in the production of other products, seriously affecting product quality and reducing product grades. After the leakage of the condenser tube sheet weld, the enterprise usually uses the traditional repair welding method to repair. The internal stress is easily generated in the tube sheet, and it is difficult to eliminate, resulting in leakage of other heat exchangers. The enterprise checks the repair situation of Spiral plate heat exchanger by pressing After repeated welding and experimentation, it takes 2 to 4 people a few days to complete the repair. After several months of use, the weld of the tube sheet appears to be corroded again, which brings a waste of manpower, material resources, and financial resources to the enterprise and increases production costs. Through the corrosion resistance and erosion resistance of the polymer composite material, and the protection of the new heat exchanger in advance, this not only effectively solves the weld seam and sand hole problems existing in the new heat exchanger, but also avoids the chemical corrosion after use. The metal surface and welding points of the heater can be coated with polymer composite materials to protect the bare metal during regular maintenance in the future; even if leakage occurs after use, it can be repaired in time to avoid long-term surfacing. Maintenance affects production. It is precisely because of this refined management that the probability of heat exchanger leakage problems is greatly reduced, which not only reduces spiral plate heat exchanger purchase cost of the heat exchanger, but also ensures product quality, production time, and improves product competitiveness.

Leakage treatment

The spiral plate heat exchanger is composed of two closed and independent spiral channels. If a string leak occurs in the channel, it is more difficult to determine the string leak point. In order to accurately detect the leak, the method of drilling is used. When drilling, the drilling position should be set on the same spiral channel at the end of the heat exchanger, and it is arranged in a cross shape. When drilling, it should also be ensured that iron scraps are not allowed to fall into the heat exchanger to make it The passage is clear.

Irrigation to suppress leaks

On a channel that has never been drilled, use a pressure water pump to fill the heat exchanger with water and form a certain pressure. At this time, the location of the heat exchanger string leaks will burst out and flow to another channel (drilled through the hole) Channel), and drip water from the hole closest to the leak point (at this time, the end of the heat exchanger drilled through the hole should be placed downward), by dripping the water, you can determine which layer there is For internal leakage, then cut a section of the head of the same layer of the heat exchanger that is not drilled as an observation hole, and the specific string leakage point can be accurately determined from the observation hole.

Repair of internal leakage

1. Digging holes: After the location of the internal leakage point is determined, the hole is cut from the place where the outermost layer of the heat exchanger corresponds to the leakage point, and the sequence is from outside to inside, until the layer with the internal leakage point until. The cut holes should be oval, and the size of the outer layer is large, and it gradually decreases inward. Generally, the size of the holes on each layer of the board differs by 40mm. If the location of the leakage point is deeper, the hole cut in the outer layer should be larger.

2. Slag removal: After cutting the holes, the oxide slag remaining on each layer should be carefully cleaned. This is whether the replenishment board and each layer of spiral board can be firmly welded when welding the rework board. The key is to clean the oxidized slag with a chisel and a small hand grinding wheel for trimming the mold. Take care to remove the cleaned slag as much as possible and not let it fall into the heat exchanger.

3. Equipped with replenishment plate: In order to ensure the quality of repair, the sheet material cut from each layer of the heat exchanger is no longer used, and the replenishment plate is reconfigured. The additional replenishment plate should be used with the heat exchanger spiral plate For the same material and plate thickness, the periphery should be 15mm to 20mm larger than the holes cut in each layer of the heat exchanger, and they are also elliptical, and they are made into an arc shape that is consistent with the curvature of the spiral plate of each layer of the heat exchanger.

4. Welding internal leakage point and refill board:

1) When welding internal leaks, carefully check whether the leaks are cracks or sand holes. If necessary, use a hand wheel to clean the leaks and grind out the grooves to ensure the welding quality.

2) When welding, J422 welding rod is used, the diameter of the welding rod is 3.2mm, the current is controlled between 100-120A [1], the leakage point is welded first, then each layer of the repair board is welded, and the layer-by-layer welding is performed from the inside out.

3) The elliptical back-up plate is welded closely to the inner arc surface of the heat exchanger, and its purpose is "to facilitate operation and ensure welding quality".

4) In order to install the elliptical replenishment plate into the heat exchanger smoothly, a piece of round steel can be welded on the replenishment plate, after spot welding the oval replenishment plate, and then remove it.

5) A short round steel brace is also welded between each layer of back-up plates (mainly to increase the mutual stiffness of the oval-shaped back-up plates). The number of short round steel braces welded on each layer of the repair board is determined by the size of the repair board. Generally, 23 are welded on the outer layers of the slightly larger layers, and 1 ~ on the inner layer. 2.

6) Since the outermost steel plate is δ12mm thick, the original cut steel plate can be directly installed in the original position and aligned for welding.

7) In welding, it should be done. After welding each layer of elliptical backing plate, the welding position should be carefully checked. If there is sand hole, repair welding should be performed to ensure the welding quality of each layer.

Pressure test and block drilling

After welding the inner leakage point and the replenishment plate, use a pressure water pump to fill the channel with the last hole drilled, and form a pressure of 0.5? 1.0MPa, and maintain it for a certain period of time, there should be no pressure relief phenomenon. Plugging the drilled hole: used for drilling short round steel segments with the same diameter, plugging and welding the position of the drilled hole and observation hole, and then carrying out hydraulic pressure test on the channel, the pressure is 0.51.0MPa, should be No leakage occurs. Attentions should be paid to the pressure test process: 1) Before cutting holes in the heat exchanger, steam should be used to blow away the chemical substances remaining in the heat exchanger to avoid combustion during gas cutting and safety accidents. 2) Before repairing the heat exchanger, it should be confirmed whether it is seriously corroded, and it is necessary to repair it.

Advantages and disadvantages

Advantages: The spiral plate heat exchanger has a compact structure and a large heat transfer surface provided per unit volume. For example, the heat transfer surface of a spiral plate heat exchanger with a diameter of ￠ 1500mm and a height of 1200mm can reach 130m2. The flow rate of the fluid in the spiral plate is high, and the fluid flows in the spiral direction, and the stagnation layer is thin, so the heat transfer coefficient is large and the heat transfer efficiency is high. In addition, due to the high flow rate, dirt is not easy to stay.

Disadvantages: Spiral plate heat exchangers require high welding quality and are difficult to maintain. Heavy weight and poor rigidity, special attention should be paid to the transportation and installation of spiral plate heat exchangers.

The production practice proves that the spiral plate heat exchanger is not easy to be plugged compared with the general tube heat exchanger, especially the suspended particles and impurities such as sediment and small shells are not easy to deposit in the spiral channel, and the reason is analyzed; one is because It is the deposition of single-channel impurities in the channel. Once a revolving flow is formed, it will be increased to wash it away. Second, because there is no dead angle in the spiral channel, the impurities are easily washed out.