A scale prevention system for coal slurry ash water heat exchanger

Abstract

The present invention discloses a scale prevention system for a coal slurry ash water heat exchanger, comprising: an ash water pool, a pretreatment system, an ash water heat exchanger and a water treatment pool connected in sequence through pipelines according to the direction of water flow, a return pipeline is connected between the outlet pipeline and the inlet pipeline of the ash water heat exchanger, a scale prevention pump is arranged on the return pipeline, and the pretreatment system comprises: an ion exchange resin device, an ultrasonic generating device, an electromagnetic wave generating device and a swirl device. The scale prevention pump of the present invention is connected in parallel with the ash water heat exchanger, and the flow rate and temperature of the water inlet of the heat exchanger can be effectively adjusted without affecting the flow rate of the incoming water and the outgoing water. By strengthening the cooperation of the heat exchange and the pretreatment system, the ash water delivery flow rate can be greatly increased, the continuous operation time of the ash water heat exchanger can be extended, and the temperature of the delivered ash water can be guaranteed to meet the standard, thereby playing an effective scale prevention role.

Description

Technical Field

[0001] The invention belongs to the technical field of coal slurry ash water treatment, and in particular relates to a scale inhibition system of a coal slurry ash water heat exchanger. Background Art

[0002] The slag water treatment process is an important part of the coal gasification process, and its stable operation plays a decisive role in the long-term stable operation of the entire gasifier. The black water and gray water of the slag water system have the characteristics of high temperature (60-90°C), high hardness, high ammonia nitrogen value, high cod, and high suspended solids. Due to the high content of silica, calcium oxide and magnesium oxide in the coal slurry ash water, the total hardness of the ash water system has always been very high, resulting in scaling and blockage of the heat exchanger, quenching ring, gasifier and other parts of the coal gasification system, which seriously affects the safe and stable operation. The furnace has to be shut down for cleaning regularly, which has a significant impact on production.

[0003] The ash water needs to be cooled to about 50℃ by circulating cooling water through the heat exchanger. The ash water heat exchanger is seriously scaled during operation. At present, there is a lack of effective anti-scaling measures for the ash water heat exchanger, which leads to frequent cleaning of the ash water heat exchanger and a large cleaning workload; the process cooling quality is not high, and the external temperature does not meet the standard; it affects the subsequent ash water treatment process, resulting in the water quality of the treated reclaimed water not meeting the standard; it seriously affects the ash water production and quality; and affects the stability of the coal gasification production process. In view of this, it is necessary to study a scale prevention system for coal slurry ash water heat exchanger. Summary of the invention

[0004] In order to address the deficiencies in the prior art, the purpose of the present invention is to provide a scale inhibition system for a coal slurry ash water heat exchanger, which is connected in parallel with the ash water heat exchanger through a scale inhibition pump to effectively adjust the flow rate and temperature of the water inlet to the heat exchanger, and greatly increase the ash water delivery flow rate by strengthening the coordination of the heat exchange and scale inhibition system, thereby achieving a good scale inhibition effect.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A scale inhibition system for a coal slurry ash-water heat exchanger comprises: an ash water pool, a pretreatment system, an ash water heat exchanger and a water treatment pool which are connected in sequence through pipelines in the direction of water flow; a return pipeline is connected between the outlet pipeline and the inlet pipeline of the ash water heat exchanger, and a scale inhibition pump is arranged on the return pipeline.

[0007] Preferably, the pretreatment system comprises:

[0008] An ion exchange resin device is arranged between the gray water pool and the gray water heat exchanger to adsorb calcium and magnesium ions in the gray water;

[0009] An ultrasonic generator is arranged between the ion exchange resin device and the grey water heat exchanger, and is used to emit ultrasonic waves to disturb the flow state of the grey water in the pipeline and affect the movement state of the silicon dioxide particles in the grey water;

[0010] An electromagnetic wave generating device is arranged between the ultrasonic wave generating device and the grey water heat exchanger, and is used to generate an electromagnetic field to change the charge distribution and motion state of the silicon dioxide particles in the grey water;

[0011] The swirl device is arranged inside the pipeline between the electromagnetic wave generating device and the gray water heat exchanger, and is used to change the flow state of the gray water in the pipeline and the concentration and movement state of the suspended matter in the gray water.

[0012] Preferably, the contents of silicon dioxide, calcium oxide and magnesium oxide in the ash scale on the inner wall of the ash-water heat exchanger pipe are 55-68%, 12-16% and 9-11% respectively.

[0013] Preferably, the flow rate of the grey water in the grey water heat exchanger pipe is 1.5-2 m / s.

[0014] Preferably, the aforementioned ultrasonic generating device includes an ultrasonic generator and a plurality of ultrasonic transducers arranged on the outer wall of the pipe connected by cables. The ultrasonic generator works by being turned on once every 10 to 15 minutes, the operating time is 20 to 30 minutes, and the operating frequency is 20 to 25 KHz.

[0015] Preferably, the aforementioned electromagnetic wave generating device comprises an electromagnetic coil wound on the outer wall of the pipeline, the number of turns of the electromagnetic coil is 25 to 30 turns, and the frequency is 10 to 15 KHz.

[0016] Preferably, the aforementioned cyclone device includes a fixed rod horizontally fixed in the middle of the pipeline and a cyclone assembly movably connected to both sides of the fixed rod, the cyclone assembly includes a connecting rod, a first stirring rod and a second stirring rod arranged parallel to each other and vertically fixed to the outer end of the connecting rod, a first circular hole is provided on both sides of the fixed rod, and the other end of the connecting rod passes through the first circular hole and is fixedly connected to a circular ring with a diameter larger than the first circular hole, so that the cyclone assembly rotates with the water flow.

[0017] Preferably, a plurality of stirring belts are evenly and fixedly arranged on the outer sides of the first stirring rod and the second stirring rod, the stirring belt on the outer side of the first stirring rod and the stirring belt on the second stirring rod are arranged at intervals, and the stirring belt includes a plurality of blades rotatably connected by a pin shaft.

[0018] Preferably, multiple mounting rods are fixedly arranged on the outer sides of the first stirring rod and the second stirring rod, and the two ends of the bottom of the mounting rods are connected to the bottom plate through support rods. A second circular hole is arranged on the bottom plate, and the top end of the stirring belt is connected to a T-shaped connecting column, which movably passes through the second circular hole to drive the stirring belt to rotate with the water flow.

[0019] Preferably, the aforementioned mounting rod is tilted, and the angles between the mounting rod and the first stirring rod and the second stirring rod are 10° to 20°; a plurality of X-shaped stirring members or O-shaped stirring members are fixedly arranged at equal intervals between the first stirring rod and the second stirring rod.

[0020] The present invention is beneficial in that:

[0021] (1) The scale inhibition pump of the present invention is connected in parallel with the gray water heat exchanger. Under the premise of not affecting the inlet and outlet water flow rates, the flow rate and temperature of the gray water heat exchanger can be effectively adjusted. By strengthening the coordination of the heat exchange and scale inhibition system, the gray water delivery flow rate can be greatly increased, the continuous operation time of the gray water heat exchanger can be extended, the temperature of the delivered gray water can be guaranteed to meet the standard, the cleaning cost of the gray water heat exchanger can be reduced, its service life can be extended, and abnormalities in the subsequent gray water treatment process can be avoided;

[0022] (2) The present invention pre-treats the grey water before sending it into the grey water heat exchanger, which can effectively reduce the scaling inside the grey water heat exchanger pipe; the ion exchange resin device can effectively adsorb calcium and magnesium ions in the grey water, reduce the hardness of the grey water, and avoid the mixing of silica and metal salt scaling crystals to form hard crystals; the ultrasonic wave generator emits ultrasonic waves, which can change the flow state of the grey water in the pipe and the motion state of the silica particles; the electromagnetic wave generator generates an electromagnetic field, which can change the charge distribution and motion state of the silica particles in the grey water, reduce the electrostatic attraction between the particles, and make it more difficult for them to adhere to the pipe wall, thereby reducing the deposition of silica on the heat exchanger pipe wall; the combined action of the electromagnetic field and the ultrasonic wave can enhance each other's effect. The electromagnetic field changes the properties of the silica particles, while the ultrasonic wave further interferes with the deposition behavior of the silica particles through physical vibration, effectively improving the scale inhibition effect of the heat exchanger pipe;

[0023] (3) The ultrasonic wave emitted by the ultrasonic generator and the anti-scaling pump can drive the rotation of the swirl component, which will disturb the gray water in the pipeline, so that the gray water entering the gray water heat exchanger has a swirl state, which strengthens the heat exchange effect on the water side of the heat exchange tube and prevents impurities from being retained on the tube wall, reducing the possibility of scaling of the heat exchanger pipeline;

[0024] (4) The ultrasonic generator in the present invention works intermittently, which can change the concentration and movement state of the suspended matter in the gray water in the pipeline, making it difficult for the suspended matter to mix and form hard crystals, thereby reducing the scaling problem on the inner wall of the heat exchange tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flow chart of the scale inhibition system of the present invention;

[0026] Figure 2This is the gray water delivery temperature diagram after the scale inhibition system has been running for 60 days;

[0027] Figure 3 This is the temperature diagram during the test period of large flow rate of gray water delivery after the anti-scaling system is running;

[0028] Figure 4 This is the gray water delivery temperature diagram after the scale inhibition system has been running for 50 days;

[0029] Figure 5 This is the effect of the number of turns of the electromagnetic coil on the scale inhibition effect of the gray water heat exchanger;

[0030] Figure 6 This is a microscope photo of the dirt that has not been treated with electromagnetic waves;

[0031] Figure 7 This is a microscope photo of the dirt treated with electromagnetic waves;

[0032] Figure 8 This is the effect of the frequency of the electromagnetic coil on the scale inhibition effect of the gray water heat exchanger;

[0033] Fig. 9 This is the effect of the frequency of the ultrasonic generator on the scale inhibition effect of the gray water heat exchanger;

[0034] Fig.10 This is a microscope photo of the ash scale that has not been treated with ultrasound;

[0035] Fig.11 This is a microscopic photograph of the ash scale treated with ultrasound;

[0036] Fig.12 It is the effect of flow rate on the scale inhibition effect of gray water heat exchanger;

[0037] Fig.13 is a schematic diagram of the structure of a cyclone device;

[0038] Fig.14 It is a schematic diagram of the structure of a swirl assembly in which the stirring member is O-shaped;

[0039] Fig.15 It is a schematic diagram of the structure of the stirring belt.

[0040] The meanings of the reference numerals in the figure are: 1. ash water tank, 2. ash water heat exchanger, 3. water treatment tank, 4. anti-scaling pump, 5. ion exchange resin device, 6. ultrasonic generating device, 7. electromagnetic wave generating device, 8. swirl device, 801. fixed rod, 802. connecting rod, 803. first stirring rod, 804. second stirring rod, 805. ring, 806. stirring belt, 8061. blade, 807. mounting rod, 808. bottom plate, 809. T-type connecting column, 810. X-type stirring member, 811. O-type stirring member. DETAILED DESCRIPTION

[0041] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Example

[0043] See also Figure 1 The scale prevention system of a coal slurry ash-water heat exchanger of the present invention comprises: an ash water pool 1, an ash water heat exchanger 2 and a water treatment pool 3 which are connected in sequence through pipelines in the direction of water flow, a return pipeline is connected between the outlet pipeline and the inlet pipeline of the ash water heat exchanger 2, and a scale prevention pump 4 is arranged on the return pipeline.

[0044] The gray water pool 1 is connected to the gray water inlet of the gray water heat exchanger 2 through the incoming water pipeline, the gray water outlet of the gray water heat exchanger 2 is connected to the water treatment pool 3 through the external discharge pipeline, the inlet end of the scale inhibition pump 4 is connected to the external discharge pipeline through the water inlet pipeline, and the outlet end of the scale inhibition pump 4 is connected to the incoming water pipeline through the outlet water pipeline. An incoming water pneumatic valve is arranged on the incoming water pipeline between the connecting point of the incoming water pipeline and the outlet water pipeline and the gray water pool 1, and a gray water external discharge valve is arranged on the external discharge pipeline between the connecting point of the external discharge pipeline and the inlet water pipeline and the water treatment pool 3. The cooling water outlet and the cooling water inlet of the gray water heat exchanger 2 are respectively connected to the cooling water supply pipeline and the cooling water drainage pipeline.

[0045] The gray water in the gray water pool 1 enters the gray water heat exchanger 2 through the water supply pipeline, and the gray water exchanges heat in the gray water heat exchanger 2. A part of the cooled low-temperature gray water is sent to the water supply pipeline through the scale inhibition pump 4, mixed with the high-temperature gray water, and the mixed medium-temperature gray water is sent to the gray water heat exchanger 2 for cooling; the other part is sent to the water treatment pool 3 through the external discharge pipeline for subsequent treatment. The scale inhibition pump 4 is connected in parallel with the gray water heat exchanger 2. Under the premise of not affecting the flow of incoming water and outgoing water, the flow rate and temperature of the water entering the heat exchanger can be effectively adjusted, and the work of the self-scale inhibition device can be further coordinated by adjusting the flow rate of the water entering the heat exchanger.

[0046] A first remote pressure sensor, a temperature sensor and a first flow sensor are installed in the grey water heat exchanger 2 to continuously collect data from the grey water sensors, continuously analyze the heat exchange capacity and scaling condition of the grey water heat exchanger 2, and promptly find problems with the grey water heat exchanger 2. A second remote pressure sensor and a second flow sensor are installed on the external discharge pipeline to continuously collect pipeline data, realize continuous analysis of the scaling condition and transport capacity of the pipeline, and promptly find problems with the grey water external discharge pipeline.

[0047] The pretreatment system includes: an ion exchange resin device 5, which is arranged between the gray water pool 1 and the gray water heat exchanger 2, and is used to adsorb calcium and magnesium ions in the gray water; an ultrasonic generating device 6, which is arranged between the ion exchange resin device 5 and the gray water heat exchanger 2, and is used to emit ultrasonic waves to interfere with the flow state of the gray water in the pipeline and affect the movement state of the silicon dioxide particles in the gray water; an electromagnetic wave generating device 7, which is arranged between the ultrasonic generating device 6 and the gray water heat exchanger 2, and is used to generate an electromagnetic field to change the charge distribution and movement state of the silicon dioxide particles in the gray water; a cyclone device 8, which is arranged inside the pipeline between the electromagnetic wave generating device 7 and the gray water heat exchanger 2, and is used to change the flow state of the gray water in the pipeline and the concentration and movement state of the suspended matter in the gray water.

[0048] The ultrasonic wave generator 6 includes an ultrasonic wave generator and a plurality of ultrasonic transducers connected by cables and arranged on the outer wall of the pipeline. The ultrasonic wave generator works by turning on once every 10 to 15 minutes, the operation time is 20 to 30 minutes, and the operation frequency is 20 to 25 kHz. The electromagnetic wave generator 7 includes an electromagnetic coil wound on the outer wall of the pipeline, the number of turns of the electromagnetic coil is 25 to 30 turns, and the frequency is 10 to 15 kHz.

[0049] The swirl device 8 includes a fixed rod 801 horizontally fixed in the middle of the pipeline and a swirl assembly movably connected to both sides of the fixed rod 801. The swirl assembly includes a connecting rod 802, a first stirring rod 803 and a second stirring rod 804 which are arranged parallel to each other and vertically fixed to the outer ends of the connecting rod 802. First circular holes are provided on both sides of the fixed rod 801. The other end of the connecting rod 802 passes through the first circular hole and is fixedly connected to a ring 805 whose diameter is larger than the first circular hole. The connecting rod 802 and the fixed rod 801 are movably connected so that the swirl assembly rotates with the water flow. When there is no water flow, the tail end of the swirl assembly is drooping. The two stirring rods rotate and disturb in the same direction, which will generate strong shear force and turbulence, and will have a disturbing effect on the gray water in the pipeline, so that the gray water entering the gray water heat exchanger 2 has a swirling state, and the retention layer close to the tube wall of the gray water heat exchanger 2 disappears, and the heat is quickly transferred from the heat exchange tube to the disturbed water flow and is quickly taken away, thereby enhancing the heat exchange effect on the water side of the heat exchange tube; at the same time, the rotating water flow generates friction and shear force on the tube wall of the heat exchanger, destroying the adhesion mechanism of impurities in the gray water on the inner wall of the heat exchange tube, so that the impurities have no time to stay on the tube wall, reducing the possibility of scaling, keeping the inner wall of the heat exchange tube clean and scale-free for a long time, and greatly slowing down under-scale corrosion; due to the enhanced heat exchange effect of the heat exchanger, the drainage temperature is reduced, and at the same time, the disturbance of the water flow reduces the temperature of the water flow close to the tube wall, and the solubility of calcium carbonate at low temperature is also reduced, which can greatly reduce the possibility of scaling on the inner wall of the heat exchange tube.

[0050] A plurality of stirring belts 806 are evenly and fixedly arranged on the outside of the first stirring rod 803 and the second stirring rod 804. The stirring belts 806 on the outside of the first stirring rod 803 and the stirring belts 806 on the second stirring rod 804 are arranged at intervals, and the stirring belts 806 include a plurality of blades 8061 connected by rotation through a pin. The first stirring rod 803, the second stirring rod 804 and the blades 8061 are all made of high molecular polymer materials, which are soft and light, corrosion-resistant, wear-resistant, anti-aging, safe and reliable. The disturbed water flow in the pipeline will drive the stirring belt 806 to rotate continuously and rapidly, and the blades 8061 are connected by rotation. Driven by the water flow, the stirring directions of the blades 8061 are different, which can further change the flow state of the water in the pipe to enhance the disturbance effect on the gray water, thereby improving the scale prevention and descaling effect.

[0051] Multiple mounting rods 807 are fixedly arranged on the outer sides of the first stirring rod 803 and the second stirring rod 804. The two ends of the bottom of the mounting rod 807 are connected to the bottom plate 808 through the support rods. The bottom plate 808 is provided with a second circular hole. The top of the stirring belt 806 is connected to the T-shaped connecting column 809. The T-shaped connecting column 809 movably passes through the second circular hole to drive the stirring belt 806 to rotate with the water flow. The mounting rod 807 is inclined, and the angles between the mounting rod 807 and the first stirring rod 803 and the second stirring rod 804 are 10° to 20°. The inclined stirring belt 806 can better rotate with the disturbed water flow and can change the flow state of the continuously flowing water.

[0052] A plurality of X-shaped stirring members 801 or O-shaped stirring members 811 are fixedly arranged at equal intervals between the first stirring rod 803 and the second stirring rod 804. The X-shaped stirring member 810 can introduce a cross flow into the stirred grey water, and the O-shaped stirring member 811 can introduce a rotating vortex into the stirred grey water, which will form a complex flow structure in the disturbance area, destroy the original flow pattern, and thus enhance the turbulent effect.

[0053] In order to better illustrate the present invention, the working process is specifically described below:

[0054] The gray water in the gray water pool 1 passes through the incoming water pipeline in sequence through the ion exchange resin device 5, the ultrasonic generating device 6, the electromagnetic wave generating device 7 and the cyclone device 8, and then enters the gray water heat exchanger 2. The gray water exchanges heat in the gray water heat exchanger 2. A part of the cooled low-temperature gray water is sent to the incoming water pipeline through the anti-scaling pump 4 and mixed with the high-temperature gray water. The mixed medium-temperature gray water is then sent to the gray water heat exchanger 2 for cooling; the other part is sent to the water treatment pool 3 through the external discharge pipeline for subsequent treatment.

[0055] Effect detection test:

[0056] 1. Analysis of scale composition in heat exchanger pipes:

[0057] Without running the scale inhibition system of the present invention, the grey water in the grey water pool was directly sent to the grey water heat exchanger for operation for 30 days. The scale samples on the inner wall of the grey water heat exchanger pipe were taken and their components were tested. The results are shown in Table 1.

[0058] Table 1 Composition of scale on the inner wall of pipe 2 of gray water heat exchanger

[0059] Components Silicon dioxide Calcium Oxide Magnesium Oxide Aluminum oxide Iron (III) oxide content 68.5％ 16.2％ 11.7％ 3.26％ 1.58％

[0060] As can be seen from Table 1, in the scale samples on the inner wall of the heat exchanger pipe, the content of silicon dioxide is the highest, far greater than the content of calcium oxide and magnesium oxide. The silicon dioxide and metal salt scaling crystals in the gray water will adhere and intertwine, growing into a hard mixture, so the calcium and magnesium ions in the gray water first can prevent them from growing into a hard mixture with silicon dioxide. Therefore, the present invention installs ion exchange resin before the ultrasonic generator and the electromagnetic wave generator, which can remove calcium and magnesium ions in advance and reduce the hardness of the water.

[0061] 2. Analysis of continuous operation time of anti-scaling system:

[0062] To ensure that the gray water delivery flow rate meets the standard (waste water delivery flow rate is 80~135m 3 / h), and the delivery temperature meets the standard (wastewater delivery temperature is lower than 50℃), the inlet temperature, outlet temperature, inlet pressure, outlet pressure, circulation flow rate and other data of the gray water heat exchanger tube pass are continuously collected. Through the collected data, the scaling degree and trend in the heat exchanger tube pass, the heat transfer capacity and trend of the gray water heat exchanger are analyzed, and the scale prevention system model parameters are improved. The specific analysis is as follows:

[0063] (1) Analysis of gray water delivery temperature after the scale inhibition system is put into operation

[0064] The scale prevention system was used for 60 days when the outdoor temperature was relatively hot. During the operation, the outdoor temperature reached a maximum of 35°C and the average gray water inlet temperature was 80°C. The gray water was collected once a day for delivery and the temperature of the gray water was tested. The results are shown in Table 1. Figure 2 and Table 2.

[0065] Table 2 Daily average ash water delivery temperature after the anti-scaling system is running

[0066] After 60 days of operation of the anti-scaling system Maximum value (℃) Minimum value (℃) Average value(℃) Average grey water delivery temperature 47.3 33.5 38.0

[0067] pass Figure 2 It can be concluded from Table 2 that the scale inhibition system has good scale inhibition performance, which enables the heat exchanger to maintain good heat exchange efficiency and the gray water delivery temperature to meet the standard. Before the transformation, the average continuous operation time of the gray water heat exchanger was 20 days. After the scale inhibition system was operated, the continuous operation time of the gray water heat exchanger was extended by 295% compared with before the transformation.

[0068] (2) Analysis of gray water delivery temperature during large gray water delivery periods

[0069] The system was operated for 20 minutes at an outdoor temperature of 32°C. The average outflow rate of gray water during operation was tested. The incoming gray water and outgoing gray water were collected once every minute to test the temperatures of the incoming gray water and outgoing gray water. The results are shown in Table 1. Figure 3 and Table 3.

[0070] Table 3 Grey water temperature during large grey water delivery period

[0071] <![CDATA[Average external delivery flow rate (m 3 / h)]]> Average grey water inlet temperature (℃) Average grey water delivery temperature (℃) 129.713 78.8 43.7

[0072] pass Figure 3 From Table 3, it can be concluded that the average outflow rate of gray water is 129.713m 3 / h, the average inlet temperature of grey water is 78.8℃, the average outlet temperature of grey water is 43.7℃, and the temperature of grey water drops by more than 35℃ after passing through the heat exchanger. It can be seen that under the condition of large grey water outlet flow, the scale prevention system still enables the heat exchanger to maintain good heat exchange efficiency.

[0073] (3) Analysis of grey water delivery flow

[0074] During the first 50 days of the anti-scaling system operation and the 50 days of stable operation of the anti-scaling system, the average gray water inlet temperature was 80°C. The gray water outflow rate was tested every hour every day, and the outgoing gray water was collected and the outgoing gray water temperature was tested. The results are shown in Figure 4 and Table 4.

[0075] Table 4 Grey water delivery flow

[0076]

[0077] Through Table 4 and Figure 4 It can be seen that before the anti-scaling system was put into operation, the average daily outflow rate was 77.921m 3 / h. During the stable operation stage of the scale inhibition system, the average daily outflow rate is 102.448m 3 / h, the wastewater delivery temperature was lower than 50℃. When the delivery temperature met the standard, the gray water delivery flow rate increased by 31.48%.

[0078] Based on the above conclusions, the anti-scaling system of the gray water heat exchanger greatly increases the gray water delivery flow rate, extends the continuous operation time of the gray water heat exchanger, ensures that the delivered gray water temperature meets the standard, reduces the cleaning cost of the heat exchanger, extends the service life of the heat exchanger, and avoids abnormalities in the subsequent gray water treatment process.

[0079] 3. Influence of the number of turns of the electromagnetic coil of the electromagnetic wave generator on the anti-scaling effect of the gray water heat exchanger

[0080] Eight groups of experiments were designed. The electromagnetic coil was wound on the pipeline with 0, 5, 10, 15, 20, 25, 30, and 35 turns respectively. The operating frequency was 10KHz. The system operated stably for 60 days. The operating frequency of the ultrasonic generator 6 was 15KHz. The working mode was to open once every 10 minutes. The operating time was 25 minutes. The average gray water inlet temperature was 90℃. The gray water was collected once a day for delivery. The gray water delivery temperature was tested. The specific results are shown in Figure 5 For the two groups with 0 and 25 turns of electromagnetic coil, the scale samples on the inner wall of the gray water heat exchanger 2 pipe were taken and observed under an optical microscope. The results are shown in Figure 6 and Figure 7 , where the darker areas are scale particles, most of which are silica particles, and the brighter areas are the gaps between the scale particles.

[0081] pass Figure 5 It can be seen that when the electromagnetic coil is 0, the daily average temperature of the outgoing gray water after the system has been running stably for 60 days is the highest, which is 67.3℃. The outgoing gray water temperature does not meet the standard. This is because when the electromagnetic wave generating device is not set, the silica particles are easy to scale on the inner wall of the gray water heat exchanger pipe, and the scale affects the heat exchange effect of the heat exchanger. In addition, the daily average temperature of the outgoing gray water when the electromagnetic coil is 0 is higher than the daily average temperature of the outgoing gray water with the electromagnetic wave generating device set. It can be seen that the electromagnetic wave generating device can indeed improve the scale prevention effect of the gray water heat exchanger, and when the electromagnetic coil is between 25 and 30 turns, the daily average temperature of the outgoing gray water is the lowest, that is, the scale prevention effect on the gray water heat exchanger is the best. However, the more turns the better. When the number of turns is greater than 30, the daily average temperature of the outgoing gray water increases instead.

[0082] pass Figure 6 It can be seen that when the electromagnetic wave generator is not set, the gaps between the dirt particles are larger, the distribution is not very uniform, and the dirt particles are larger. Figure 7 It can be seen that when the electromagnetic wave generator is set, the scale particles are smaller, more evenly distributed, and the gaps between the scale particles are smaller. This shows that electromagnetic waves can change the precipitation form of silica scale particles, making the precipitated scale particles smaller and more evenly distributed, and more easily carried by the gray water and flowing with the gray water, thereby reducing the amount of adhesion on the heat exchanger tube wall, and the precipitated scale particles are not easy to aggregate together, and the formed scale is softer and less likely to form hard crystals that are difficult to clean. It can be seen that the electromagnetic wave generator can effectively improve the scale inhibition effect on the gray water heat exchanger.

[0083] 4. Influence of the frequency of the electromagnetic coil of the electromagnetic wave generator on the anti-scaling effect of the gray water heat exchanger

[0084] Five groups of experiments were designed. The operating frequencies of the electromagnetic coil were set to 5, 10, 15, 20, and 25 KHz, respectively, with a number of turns of 25. The system operated stably for 60 days, with an average grey water inlet temperature of 90°C. The operating frequency of the ultrasonic generator 6 was 15 KHz, and the working mode was to open it once every 10 minutes, with a running time of 25 minutes. The grey water was collected once a day to detect the grey water delivery temperature. The specific results are shown in Figure 8 .

[0085] pass Figure 8 It can be seen that when the operating frequency of the electromagnetic coil is 10-15KHz, the average inlet temperature of gray water is lower than 40°C, and the scale inhibition effect is the best. When the operating frequency of the electromagnetic coil is greater than 15KHz and less than 10KHz, the average inlet temperature of gray water exceeds 50°C, which does not meet the standard and the scale inhibition effect is poor.

[0086] 5. Influence of the frequency of ultrasonic generator on the anti-scaling effect of gray water heat exchanger

[0087] Six groups of experiments were designed. The frequencies of the ultrasonic generator were set to 0, 5, 10, 15, 20, 25, and 30 KHz, respectively. The working mode was to open the system every 10 minutes, and the operation time was 25 minutes. The operating frequency of the electromagnetic coil was 10 KHz, and the number of turns was 25. The system operated stably for 60 days, and the average gray water temperature was 90 °C. The gray water was collected once a day for delivery, and the temperature of the gray water was tested. The specific results are shown in Fig. 9 The scale samples on the inner wall of the gray water heat exchanger pipe in the two groups of tests with frequencies of 0 and 20 were sampled and observed under an optical microscope. The results are shown in Fig.10 and Fig.11 .

[0088] pass Fig. 9 It can be seen that when the operating frequency of the ultrasonic generating device is 15-25KHz, the average inlet gray water temperature is the lowest, which is 39-43°C. When the frequency of the ultrasonic generating device is 0, that is, when the ultrasonic generating device is not turned on, the average inlet gray water temperature is 58.2°C, which does not meet the standard.

[0089] pass Fig.10 and Fig.11 It can be seen that after turning on the ultrasonic generator, the amount of scaling of silica ash scale particles is small and the ash scale is relatively loose, while the ash scale that has not been treated with ultrasonic waves is relatively dense. It can be seen that ultrasonic treatment can not only reduce the amount of scaling on the tube wall of the gray-water heat exchanger, but also make the ash scale loose and easy to clean.

[0090] 6. The influence of the working mode of the ultrasonic generator on the anti-scaling effect of the gray water heat exchanger

[0091] Three groups of experiments were designed. In the first group, the ultrasonic generator was turned on once every 10 minutes, and the operation time was 25 minutes; in the second group, the ultrasonic generator was turned on once every 15 minutes, and the operation time was 30 minutes; in the third group, the ultrasonic generator was operated continuously. In the three groups of experiments, the operating frequency of the ultrasonic generator was 15KHz, the operating frequency of the electromagnetic coil was 10KHz, the number of turns was 25, the system operated stably for 60 days, the average gray water inlet temperature was 90℃, and the outgoing gray water was collected once a day to test the outgoing gray water temperature. The specific results are shown in Table 5.

[0092] Table 5 The temperature of the delivered ash water when the ultrasonic generator works in different modes

[0093] It can be seen from Table 5 that the temperatures of the delivered gray water in the three groups of experiments all meet the standards, but the average daily temperatures of the delivered gray water in the first and second groups are significantly lower than those in the third group, which has a better anti-scaling effect on the gray water heat exchanger tube wall. This is because the intermittent operation of the ultrasonic generator can change the concentration and movement state of the suspended matter in the pipeline gray water, making the concentration of the suspended matter in the pipeline high and low and not fixed, so that the suspended matter is not easy to mix to form hard crystals, thereby reducing the scaling problem on the inner wall of the heat exchange tube.

[0094] 7. The influence of cyclone device on the anti-scaling effect of gray water heat exchanger

[0095] A comparative example was set up in which the cyclone device was not installed. The system operated stably for 60 days, with an average grey water inlet temperature of 90°C. The outgoing grey water was collected once a day to test the outgoing grey water temperature. The specific results are shown in Table 6.

[0096] Table 6 Effect of cyclone device on the temperature of the delivered ash water

[0097] Group Example Comparative Example Average daily temperature of delivered grey water (℃) 38.8 56.4

[0098] It can be seen from Table 6 that in the comparative example without the cyclone device installed, the average temperature of the outgoing gray water is 56.4℃, which is below the standard, indicating that the cyclone device can play a good anti-scaling effect. This is because the cyclone component can disturb the gray water in the pipeline, so that the gray water entering the gray water heat exchanger has a cyclone state, which strengthens the heat exchange effect on the water side of the heat exchange tube, and makes the impurities have no time to stay on the tube wall, reducing the possibility of scaling of the heat exchanger pipeline.

[0099] 8. Effect of flow rate on scale inhibition of gray water heat exchanger

[0100] Six groups of experiments were designed. By adjusting the scale-inhibiting pump, the flow rates of the gray water in the gray water heat exchanger were 0.5, 1.0, 1.5, 2.0, and 2.5 m / s, respectively. The operating frequency of the ultrasonic generator was 15 KHz. The working mode was to open it once every 10 minutes, and the operating time was 25 minutes. The operating frequency of the electromagnetic coil was 10 KHz, and the number of turns was 25. The system operated stably for 60 days, and the average gray water inlet temperature was 90 °C. The gray water was collected once a day for external delivery, and the gray water delivery temperature was tested. The specific results are shown in Fig.12 .

[0101] pass Fig.12 It can be seen that when the flow rate of gray water in the gray water heat exchanger pipe is 1.5-2m / s, the average gray water delivery temperature is the lowest. When the flow rate is lower than 1.5m / s or higher than 2m / s, the average gray water delivery temperature does not meet the standard. This is because a higher flow rate can flush the inner wall of the heat exchanger pipe to reduce the amount of scaling on the pipe wall, thereby improving the heat exchange effect. A lower flow rate has little effect on the flushing of the inner wall of the pipe. A higher flow rate will shorten the gray water heat exchange time, so no good heat exchange effect is achieved.

[0102] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A scale prevention system for a coal slurry ash-water heat exchanger, characterized in that: include: A grey water pool (1), a pretreatment system, a grey water heat exchanger (2) and a water treatment pool (3) connected in sequence by pipelines in a water flow direction, a return pipeline being connected between an outlet pipeline and an inlet pipeline of the grey water heat exchanger (2), and a scale inhibitor pump (4) being provided on the return pipeline; The pretreatment system comprises: An ion exchange resin device (5) is disposed between the gray water pool (1) and the gray water heat exchanger (2) and is used to adsorb calcium and magnesium ions in the gray water; An ultrasonic generating device (6) is arranged between the ion exchange resin device (5) and the grey water heat exchanger (2) and is used to generate ultrasonic waves to interfere with the flow state of the grey water in the pipeline and affect the movement state of the silicon dioxide particles in the grey water; An electromagnetic wave generating device (7) is arranged between the ultrasonic wave generating device (6) and the grey water heat exchanger (2), and is used to generate an electromagnetic field to change the charge distribution and motion state of the silicon dioxide particles in the grey water; The swirl device (8) is arranged inside the pipeline between the connection point of the return pipeline and the inlet pipeline of the gray water heat exchanger (2) and the gray water heat exchanger (2), and is used to change the flow state of the gray water in the pipeline and the concentration and movement state of the suspended matter in the gray water.

2. The scale inhibition system of the coal slurry ash water heat exchanger according to claim 1, characterized in that: The components of the ash scale on the inner wall of the pipe of the ash-water heat exchanger (2) are: silicon dioxide, calcium oxide, magnesium oxide, ferric oxide and aluminum oxide, and the content of silicon dioxide is greater than the sum of the contents of calcium oxide, magnesium oxide, ferric oxide and aluminum oxide.

3. The scale inhibition system for coal slurry ash water heat exchanger according to claim 1, characterized in that: The flow rate of the grey water in the grey water heat exchanger (2) pipeline is 1.5-2 m / s.

4. The scale inhibition system for coal slurry ash-water heat exchanger according to claim 1, characterized in that: The ultrasonic generating device (6) comprises an ultrasonic generator and a plurality of ultrasonic transducers arranged on the outer wall of the pipeline and connected by cables. The ultrasonic generator works by being turned on once every 10 to 15 minutes, with a running time of 20 to 30 minutes and a running frequency of 20 to 25 kHz.

5. The scale inhibition system for coal slurry ash water heat exchanger according to claim 1, characterized in that: The electromagnetic wave generating device (7) comprises an electromagnetic coil wound on the outer wall of the pipeline, the number of turns of the electromagnetic coil is 25 to 30 turns, and the frequency is 10 to 15 kHz.

6. The scale inhibition system for coal slurry ash water heat exchanger according to claim 1, characterized in that: The cyclone device (8) comprises a fixed rod (801) fixedly arranged horizontally in the middle of a pipeline and cyclone components movably connected to both sides of the fixed rod (801), the cyclone components comprising a connecting rod (802), a first stirring rod (803) and a second stirring rod (804) arranged parallel to each other and fixed vertically to the outer end of the connecting rod (802), first circular holes are arranged on both sides of the fixed rod (801), and the other end of the connecting rod (802) passes through the first circular hole and is fixedly connected to a circular ring (805) having a diameter larger than the first circular hole, so that the cyclone component rotates with the water flow.

7. The scale inhibition system for coal slurry ash water heat exchanger according to claim 6, characterized in that: A plurality of stirring belts (806) are evenly and fixedly arranged on the outer sides of the first stirring rod (803) and the second stirring rod (804); the stirring belt (806) on the outer side of the first stirring rod (803) and the stirring belt (806) on the second stirring rod (804) are arranged at intervals; and the stirring belt (806) comprises a plurality of blades (8061) rotatably connected via a pin shaft.

8. The scale prevention system for coal slurry ash water heat exchanger according to claim 7, characterized in that: A plurality of mounting rods (807) are fixedly arranged on the outer sides of the first stirring rod (803) and the second stirring rod (804); the two ends of the bottom of the mounting rods (807) are connected to a bottom plate (808) via supporting rods; a second circular hole is arranged on the bottom plate (808); the top end of the stirring belt (806) is connected to a T-shaped connecting column (809); the T-shaped connecting column (809) movably passes through the second circular hole to drive the stirring belt (806) to rotate with the water flow.

9. The scale inhibition system for coal slurry ash water heat exchanger according to claim 8, characterized in that: The mounting rod (807) is arranged to be inclined, and the angles between the mounting rod (807) and the first stirring rod (803) and the second stirring rod (804) are all 10° to 20°; a plurality of X-shaped stirring members (810) or O-shaped stirring members (811) are fixedly arranged at equal intervals between the first stirring rod (803) and the second stirring rod (804).

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