CN111397396A - A powder material cooling system and its cooling process - Google Patents

Abstract

The invention discloses a powder material cooling system and a cooling process thereof, relating to the technical field of powder material cooling; the device comprises a circulating fan, a powder fluidization cooler, a cyclone separator, a bag-type dust collector and a powder conveyor, wherein an outlet at the top of the powder fluidization cooler is communicated with an inlet of the cyclone separator, and a gas inlet at the bottom of the powder fluidization cooler is connected with an outlet of the circulating fan, so that gas-solid two phases flow out from the outlet at the top of the powder fluidization cooler and then enter the cyclone separator; the bottom of the cyclone separator is a discharge hole for the cooled product material, and a tail gas outlet at the top of the cyclone separator is connected with a bag-type dust collector; the bag-type dust remover is connected to the inlet of the circulating fan, so that the gas collected by the bag-type dust remover is recycled as the fluidizing gas; by implementing the technical scheme, the technical problem that the existing cooling technology is not suitable for powder materials with small particle size, easy moisture absorption or easy deterioration and poor liquidity can be effectively solved, the reliability of the cooling technology can be obviously improved, and the running cost is reduced.

Description

A powder material cooling system and its cooling process

technical field

The invention relates to the technical field of powder material cooling, in particular to a powder material cooling system and a cooling process thereof.

Background technique

In the production of inorganic salts, metal oxides, and metal powders, it is often necessary to cool the calcined high-temperature powder materials for packaging and transportation. The traditional powder cooling technology adopts the indirect heat exchange of cooling water or the direct heat exchange of air/inert gas for cooling. Limitations:

1. Powder flow heat exchanger technology: The high-temperature solid powder relies on its own gravity to flow through the narrow channel of the plate heat exchanger, and conduct indirect heat exchange with the cooling water on the other side to achieve the purpose of cooling the material. By-produced hot water, the heat can be recovered. However, the powder flow heat exchanger technology is only suitable for powder materials with good fluidity, usually requiring powder particle size > 150μm and angle of repose < 40°. This technology was first promoted by Canadian Solex Company, and has been widely used in heavy soda ash, urea, potassium chloride, sucrose and other products; but for powders with poor fluidity, because they cannot flow smoothly between heat exchange plates, this technology cannot be used. technology.

2. Fluidized bed cooling technology: It uses the principle of fluidization, using air or inert gas to fluidize the powder, and the powder passes through multiple fluidization chambers in turn, and there is cooling air under each fluidized chamber. / The inert gas is introduced, and the air/inert gas is in direct contact with the powder to exchange heat to achieve the purpose of step-by-step cooling. The heat-exchanged air/inert gas is drawn from the top and emptied through a cyclone separator and a bag filter. The air/inert gas can also be indirectly cooled and recycled; however, the fluidized bed cooling technology requires that the powder can be stably fluidized, and the generally applicable particle size range is 30-600 μm (the particle size is too small to form a stable fluidized bed). If the particle size is too large, the pressure drop will be too large), the heat of this technology cannot be effectively recovered, and the amount of public works is large.

3. Rotary cooling technology: The material is constantly flipped by the copy plate in the rotary kiln, and cooling water is passed into the copy plate and the kiln wall, and the material is cooled during the slow transportation process; but the rotary cooling technology equipment occupies a large area , Easy to harden, difficult to clean, usually the material temperature should not be too high (easy to harden), and the material should have good fluidity.

4. Disc cooling technology: the material stays on the discs layer by layer, cooling water is passed into the disc, the solid contacts the disc, and is cooled by heat conduction; but the heat transfer efficiency of the disc cooling technology is low, so it is only used for Small-scale cooling is usually used in food, medicine and other fields.

5. Pneumatic conveying cooling technology: in the process of pneumatic conveying, the powder material is cooled. Since the ratio of air to powder in pneumatic conveying has a certain range, it is not convenient to precisely control the temperature of the powder after cooling, and the cooling technology of pneumatic conveying has not been maturely applied.

Since the above technologies have their own limitations, for some powder materials with small particle size, easy moisture absorption or deterioration, and poor fluidity, such as activated calcium oxide produced by calcining carbide slag, the above traditional cooling technologies are not applicable. Those skilled in the art need to research and design a new cooling system and/or cooling process, which can also conduct targeted cooling for powders that are easy to absorb moisture and deteriorate, improve the operational reliability of cooling technology, and reduce operating costs.

SUMMARY OF THE INVENTION

In order to solve the technical problem that the above-mentioned existing cooling technology is not suitable for some powder materials with small particle size, easy moisture absorption or deterioration, and poor fluidity, which leads to no engineering practicability, the purpose of the present invention is to provide a powder material. The purpose of the material cooling system and its cooling process is to use a small amount of gas to carry high-temperature powder materials to flow, so that the solid powder is in a state similar to high-speed fluid for sufficient heat exchange, so that the heat transfer is mainly convective heat transfer. Powder flow heat transfer, rotary and disc heat transfer can greatly improve the heat transfer efficiency of powder materials; especially for powder materials with particle size less than 30μm, it is not easy to form a stable fluidized bed. The airflow controlled by this cooling system The speed is greater than the take-out speed of all particles. The gas-solid two phases do not need to form a stable bed with clear boundaries. It only needs to ensure that the cooling operation can be completed by flowing out from the top through the heat exchange tube. The control requirements are low, and the cooling can be significantly improved. The reliability of the technology, while reducing the cost of operating costs, significantly improves the economic benefits of the enterprise.

The technical scheme adopted in the present invention is as follows:

A powder material cooling system includes a circulating fan, a powder fluidization cooler, a cyclone separator, a bag filter and a powder material conveyor; wherein, the powder fluidization cooler is installed vertically, and the powder The lower end of the fluidized cooler is provided with a powder material inlet, the top outlet of which is connected to the inlet of the cyclone separator, and the bottom gas inlet of the fluidized cooler is connected to the outlet of the circulating fan, so that the gas and solid are connected. The phase flows out from the top outlet of the powder fluidized cooler and then enters the cyclone separator; the bottom of the cyclone separator is the outlet for the product material after cooling, and the top thereof is the tail gas outlet, and the tail gas outlet at the top of the cyclone separator is the same as that of the cyclone separator. The bag filter is connected; the bag filter is connected to the inlet of the circulating fan, so that the gas collected by the bag filter can be recycled as a fluidized gas; both at the bottom of the cyclone separator and the bag filter are A powder conveyor is provided, so that the product materials discharged from the bottom of the cyclone separator and the bag filter are sent out through the powder conveyor.

In this technical solution, the powder can be fluidized with only a small amount of gas, and the carrier gas is recycled. For powder materials that are easy to absorb moisture and deteriorate, dry air or inert gas such as nitrogen can be selected in a targeted manner. In traditional fluidized bed coolers, the gas circulation volume is greatly reduced; under normal operating conditions, only a very small amount of gas needs to be supplemented or discharged to balance the system pressure; and for powders with a particle size below 30 μm, it is not easy to form stable gas. In the fluidized bed layer, the air velocity controlled by the cooling system in this technical solution is greater than the take-out velocity of all particles. The gas-solid two-phase does not need to form a stable bed with clear boundaries, but only needs to ensure that it can flow out from the top through the heat exchange tube The cooling operation can be completed, and the control requirements are low and easy to control, which can effectively solve the technical problems of poor cooling effect of powder materials with small particle size, easy moisture absorption or deterioration, and poor fluidity.

Optionally, the powder fluidization cooler includes a fluidization chamber and a shell-and-tube heat exchange section located above the fluidization chamber, and the powder material inlet communicates with the fluidization chamber, The tube side of the shell-and-tube heat exchange section is a gas-solid two-phase circulation channel, and the shell side of the shell-and-tube heat exchange section is a cooling medium circulation channel.

Optionally, an air distribution plate is arranged at the bottom of the fluidization chamber, and the bottom gas inlet of the powder fluidization cooler is located directly below the air distribution plate, so that the gas outputted by the circulating fan enters the flow uniformly. in the activation chamber.

Optionally, the air distribution panel is at least one of a double-layer mesh type air distribution panel, a hood type air distribution panel or a gill hole type air distribution panel.

In the above technical scheme, the powder fluidized cooler is the core equipment of the cooling system, wherein the air distribution plate can be selected according to the properties of the powder material, the double-layer screen type air distribution plate, the hood type air distribution plate or the gill hole type air distribution plate. It has two main functions: (a) the air distribution plate can bear the weight of the material when it is dropped, preventing the material from falling into the air inlet pipe and causing the pipe to be blocked; (b) the air distribution plate can make the gas evenly enter the fluidized state chamber, so that the powder material entering the shell-and-tube heat exchange section is evenly distributed and fully heat exchanged. The working principle of the powder fluidized cooler is as follows: the upper part of the air distribution plate of the powder fluidized cooler is a fluidized chamber, which can effectively provide a fluidized bed space, increase the residence time and disperse materials; The shell-and-tube heat exchange section above the fluidization chamber is a heat exchange tube plate, and the heat exchange tube is used as a flow channel; after the solid powder enters the fluidization chamber of the powder fluidization cooler, it is absorbed by a small amount of air or inert The gas is fluidized and distributed into the tube side of the heat exchanger. The powder flows upward in the heat exchange tube under the action of gas phase drag, between the powder and the carrier gas, between the carrier gas and the tube wall, between the powder and the tube. There is sufficient heat exchange between the walls; the purpose of gas fluidization is to make the solid powder obtain properties similar to the fluid, and the density of the entire gas-solid mixed phase is uniform, which is convenient for uniform delivery to each heat exchange tube, so for different types of The powder materials all have good cooling effect; in this technical solution, the flow rate of the cooling medium in the powder fluidized cooler is controlled by the gas-solid two-phase outlet temperature.

Optionally, the cooling medium in the shell side is at least one of air, water, heat transfer oil, octane or heptane; if water is used, hot water or steam can be by-produced; and in the shell side The cooling medium is opposite to the gas-solid two-phase flow direction in the tube side. The shell-and-tube heat exchange section structure enables pure countercurrent operation of the cold and hot medium, and the shell-side cooling medium can be flexibly selected according to the energy recovery method.

Optionally, the shell-and-tube heat exchange section includes a heat exchange tube, a heat exchange tube tube sheet, a heat exchanger shell and a head structure located on the top of the heat exchanger shell, and the heat exchange tube tube sheet is installed on the top of the heat exchanger shell. The upper end and the lower end of the heat exchange tube shell, and the heat exchange tube plate at the upper end and the lower end are correspondingly distributed with a number of circular holes. A heat pipe, the heat exchange pipe is a straight pipe type heat exchange pipe, a bellows type heat exchange pipe or a spiral pipe type heat exchange pipe; the top outlet is arranged on the top of the head structure, and the head structure is connected to the The heat pipe shell is flanged or welded, so that the gas-solid two-phase in the fluidization chamber enters the head structure through the heat exchange tube and flows out from the top outlet located at the top of the head structure.

Optionally, the shell side of the shell-and-tube heat exchange section is provided with an expansion joint according to the temperature of the powder material, so as to eliminate the temperature difference stress caused by the temperature of the tube side being higher than the temperature of the shell side.

Optionally, a supplemental gas pipeline is provided at the inlet of the circulating fan, and the supplemental gas pipeline is configured to supply gas when the circulating gas pressure is lower than a set value, so as to stabilize the system pressure.

On the other hand, the present invention also provides a cooling process for a powder material cooling system, using the above powder material cooling system, specifically comprising the following steps:

Step 1, open the air supply valve on the air supply pipeline, turn on the circulating fan, and replace the air in the cooling system; during this process, the circulating fan operates at a low load;

Step 2: Open the feed valve at the inlet of the powder material, and the powder material enters the fluidization chamber of the powder fluidization cooler to form a stable fluidization state, so that the powder material is evenly distributed above the air distribution plate ;

Step 3: Increase the flow rate of the circulating fan and increase the feeding amount of the powder material. The powder material uniformly enters the tube side of the shell-and-tube heat exchange section driven by the carrier gas and flows in the direction of the top outlet of the powder fluidized cooler. Full heat exchange is carried out; the gas-solid two phases flow out from the top of the powder fluidized cooler and enter the cyclone for separation; the powder with larger particles is discharged from the bottom of the cyclone, while the powder with smaller particles is discharged from the bottom of the cyclone. The material enters the bag filter with the gas;

Step 4: The bag filter is controlled by pressure to perform automatic back blowing and cleaning, and the gas after removing the ultrafine powder in the bag filter enters the inlet of the circulating fan for recycling. Conveyor delivery.

Preferably, in step 3, the flow rate of the cooling medium on the side of the powder fluidized cooling shell and the temperature of the powder outlet form a regulating loop, and the opening of the inlet valve of the cooling medium is adjusted by detecting the temperature of the exhaust gas of the cyclone, so as to control the automatic flow rate of the cooling medium. The discharge temperature of the powder material after cooling by the powder fluidized cooler; in this technical solution, the gas and powder have fully exchanged heat in the process of flowing through the shell-and-tube heat exchange section of the powder fluidized cooler. The temperature of the exhaust gas of the cyclone separator can be measured to adjust the opening of the inlet valve of the cooling medium, so that the discharge temperature of the powder can be precisely controlled, the control loop is simple, and the reliability is strong.

As mentioned above, the present invention has at least the following beneficial effects compared to the prior art:

1. The present invention proposes a powder material cooling system with more engineering reliability and implementation for some powder materials with small particle size, easy moisture absorption or deterioration, and poor fluidity, which skillfully combines fluidization technology with heat exchange. Combined with the high-temperature powder material, a small amount of gas is used to carry the high-temperature powder material to flow, so that the solid powder is in a state similar to a high-speed fluid for sufficient heat exchange, so that the heat transfer is mainly convective heat transfer, which is relative to the powder flow heat transfer, The powder heat conduction of rotary and disc heat exchange greatly improves the heat exchange efficiency, which can significantly improve the cooling effect of the above powder materials.

2. The present invention is aimed at powders with a particle size lower than 30 μm, and the traditional cooling technology is not easy to form a stable fluidized bed; and the air velocity controlled by the cooling system of the present invention is greater than the take-out velocity of all particles, and the gas-solid two phases are combined. It is not necessary to form a stable bed with clear boundaries, and it is only necessary to ensure that the cooling operation can be completed by ensuring that the heat exchange tube can flow out from the top. The control requirements are low, and the reliability of the implementation of the cooling technology can be significantly improved.

3. The powder fluidization cooler of the present invention is the core equipment of the technology. A fluidization chamber with an air distribution plate structure is set directly under the tube plate of the shell and tube heat exchanger. The fluidized carrier gas and high temperature powder can be Fully mixed to facilitate uniform delivery to each heat exchange tube, and the air distribution plate can make the carrier gas evenly distributed, so that the powder, the carrier gas and the tube wall can conduct sufficient heat exchange, so for different types of powder materials All have good cooling effect.

4. The present invention can effectively reduce the cost of operating costs and significantly improve the economic benefits of the enterprise; it is mainly reflected as follows: firstly, in the indirect heat exchange, the powder flow heat exchanger is a relatively common powder cooling technology, but for finer particles, flow Powders with poor properties are not suitable because they are easy to bridge and block; using the technical solution of the present invention, a very small amount of dry air can be used to drive the flow of particles, and the fluidizing gas can be recycled, which greatly reduces the amount of gas used and reduces the The cost of operating costs; the second is for the cooling of metal particles, flammable and explosive powders, and inert gases such as nitrogen or argon need to be used. The cost of these gases is several times or even dozens of times that of dry air. For powder materials protected by inert gas, the above cost advantages are more significant; third, the cooling system of the present invention adopts indirect heat exchange and countercurrent operation, so that the heat of the powder materials can be transferred to the cooling medium on the shell side, and can be recycled and utilized. According to the purpose of energy recovery, water, octane, heptane, heat transfer oil, etc. are used for heat recovery.

5. The cooling system of the present invention is easy to be enlarged. For the traditional powder flow heat exchanger, because it adopts gravity flow, the heat of the powder is mainly transferred to the wall through the form of heat conduction, and the total heat transfer coefficient is low. The processing capacity is small, and the equipment height is as high as 8-15 meters. For the scale of processing 50 tons of materials per hour, at least 4-6 units are required. The cooler of this system is a shell-and-tube powder fluidized cooler, the heat of the powder is mainly transferred to the wall of the heat exchange tube by convection, the heat transfer coefficient is high, and the heat exchange area only needs 50-300 square meters (according to the heat transfer Different temperature differences), a single set can meet the load requirements, occupy a small area, and the system configuration is simple; it can significantly improve the economic benefits of the enterprise.

6. The present invention is beneficial to environmental protection. Since the carrier gas is used in a cycle, the cooling system is only discharged in a small amount under the condition of overpressure, and no waste gas is discharged under normal operating conditions. Compared with the direct cooling of the air, the dust-containing waste gas is greatly reduced, which is environmentally friendly; Calculated based on the 30mg/Nm3 dust contained in the discharged dust, compared with the direct contact cooling of the fluidized bed gas, this system can reduce the dust emission by 87.12 tons a year, and also reduce the product loss by 87.12 tons; it can significantly improve the economic benefits of the enterprise.

7. The cooling process of the present invention is simple to operate and has good practicability in practice. By measuring the exhaust gas temperature of the cyclone separator to adjust the opening of the inlet valve of the cooling medium, the discharge temperature of the powder can be effectively and accurately controlled. The control loop is simple, the reliability is strong, and it has good engineering implementability, which is suitable for popularization and application.

Description of drawings

The invention will be described by way of specific embodiments with reference to the accompanying drawings, wherein

1 is a schematic flow diagram of a powder material cooling system according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a powder fluidized cooler in an embodiment of the present invention.

Description of reference numerals: 1-circulating fan; 2-powder fluidization cooler; 21-bottom gas inlet; 22-powder material inlet; 23-cooling medium inlet; 24-cooling medium outlet; 25-powder fluidization Top outlet of cooler; 26-air distribution plate; 27-fluidization chamber; 28-shell and tube heat exchange section; 29-expansion joint; 3-cyclone separator; 4-bag filter; 5-powder conveying machine one; 6-powder conveyor two.

Detailed ways

All features disclosed in this specification, or all disclosed steps in a method or process, may be combined in any way except mutually exclusive features and/or steps.

Any feature disclosed in this specification (including any accompanying claims, abstract), unless expressly stated otherwise, may be replaced by other equivalent or alternative features serving a similar purpose. That is, unless expressly stated otherwise, each feature is but one example of a series of equivalent or similar features.

Example 1

The embodiment is basically shown in Figures 1 and 2: This embodiment provides a powder material cooling system, which can be used in the fields of chemical engineering, inorganic salt industry, metal oxide, metal powder production, etc., to solve the existing cooling system. The technology has good practicability for some powder materials with small particle size, easy moisture absorption or deterioration, and poor fluidity, which have poor cooling effect and are not applicable, resulting in no engineering feasibility. Specifically, as shown in Figure 1 As shown, the cooling system includes a circulating fan 1, a powder fluidized cooler, a cyclone 3, a bag filter and a powder conveyor; wherein, the powder fluidized cooler is installed vertically, and the powder fluidized cooling The lower end of the cooler is provided with a powder material inlet 22, the top outlet 25 is connected to the inlet of the cyclone separator 3, and the bottom gas inlet 21 of the powder fluidization cooler is connected to the outlet of the circulating fan 1, so that the gas-solid two-phase is separated from the powder. The top outlet 25 of the fluidized cooler flows out and enters the cyclone separator 3; the bottom of the cyclone separator 3 is the outlet for the product material after cooling, and the top is the tail gas outlet, and the tail gas outlet at the top of the cyclone separator 3 is connected to the bag filter. Connected; the bag filter collects the super-subdivision and connects to the inlet of the circulating fan 1, so that the gas collected by the bag filter can be used as a fluidized gas for recycling; thus, the bottom gas of the powder fluidized cooler in this embodiment is The inlet 21 is the circulating air inlet, and the top outlet 25 of the powder fluidized cooler is the circulating air outlet; a powder conveyor 5 is arranged at the bottom of the cyclone separator 3, and a powder material is arranged at the bottom of the bag filter. Conveyor two 6, so that the cooled product materials outputted by the cyclone separator 3 and the discharge port at the bottom of the bag filter are sent out through the powder conveyor one 5 and the powder conveyor two 6 respectively.

As shown in FIG. 2 , the powder fluidization cooler provided in this embodiment is the core equipment of the cooling system of this embodiment, which includes a fluidization chamber 27 installed in the cooler shell and a fluidization chamber 27 located in the cooler shell. The shell-and-tube heat exchange section 28 above, specifically, the shell-and-tube heat exchange section 28 includes a heat exchange tube, a heat exchange tube sheet, a heat exchanger shell, and a head structure located on the top of the heat exchanger shell. The heat pipe plate is installed on the upper end and the lower end of the heat exchange tube shell, and the heat exchange tube plate at the upper end and the lower end of the heat exchange tube shell is correspondingly distributed with several circular holes, and each circular hole is welded with a connecting rod. The fluidized chamber and the heat exchange tube of the head structure; the top outlet 25 of the cooler is set at the top of the head structure, and the head structure and the heat exchange tube shell are flanged or welded, so that the fluidization chamber can be The gas-solid two-phase of the powder enters the head structure through the heat exchange tube and flows out from the top outlet 25 located at the top of the head structure; the powder material inlet 22 is communicated with the fluidization chamber 27, and the tube of the shell-and-tube heat exchange section 28 The process is a gas-solid two-phase circulation channel, and the shell side of the shell-and-tube heat exchange section 28 is a cooling medium circulation channel; an air distribution plate 26 is arranged at the bottom of the fluidization chamber 27, and the bottom gas inlet of the powder fluidization cooler 21 is located directly below the air distribution plate 26, so that the gas output by the circulating fan 1 enters the fluidization chamber 27 evenly. The air distribution plate 26 can be selected according to the properties of the powder material. , one of the hood type air distribution plate 26 or the gill hole type air distribution plate 26; it has two main functions: (a) the air distribution plate 26 can bear the weight of the material when the material is dropped, and prevent the material from falling into the air inlet pipe (b) The air distribution plate 26 can make the gas enter the fluidization chamber 27 evenly; this is conducive to the uniform distribution of the powder material entering the shell-and-tube heat exchange section 28 and sufficient heat exchange.

The working principle of the powder fluidized cooler is as follows: the upper part of the air distribution plate 26 of the powder fluidized cooler is a fluidized chamber 27, which can effectively provide a fluidized bed space, which can increase the residence time and disperse materials. The heat exchange tube in the shell-and-tube heat exchange section 28 above the fluidization chamber 27 is used as a flow channel; after the solid powder enters the fluidization chamber of the powder fluidization cooler, a small amount of air or inert gas flows Under the action of gas phase drag, the powder flows upward in the heat exchange tube, between the powder and the carrier gas, between the carrier gas and the tube wall, and between the powder and the tube wall. The purpose of gas fluidization is to make the solid powder obtain similar properties to the fluid, and the density of the entire gas-solid mixed phase is uniform, which is convenient for uniform transportation to each heat exchange tube, so that for different types of powder All materials have good cooling effect; in this technical scheme, the flow rate of the cooling medium in the powder fluidized cooler is controlled by the gas-solid two-phase outlet temperature.

In this embodiment, the cooling medium inlet 23 in the shell and tube heat exchange section 28 is located on the left side of the upper end of the heat exchanger shell of the shell and tube heat exchange section 28, and the cooling medium outlet 24 in the shell and tube heat exchange section 28 is located at The right side of the lower end of the heat exchanger shell of the shell and tube heat exchange section 28; the cooling medium in the shell side is at least one of air, water, heat transfer oil, octane or heptane; if water is used, the secondary Produce hot water or steam; and in this embodiment, the cooling medium in the shell side and the gas-solid two-phase flow direction in the tube side are preferably opposite, so that the shell-and-tube heat exchange section 28 structure enables the cooling and heating medium to operate in pure countercurrent, the shell The cooling medium of the process can be flexibly selected according to the energy recovery method; in this embodiment, the shell side of the shell-and-tube heat exchange section 28 is provided with an expansion joint 29 according to the temperature of the powder material, so as to eliminate the problem that the temperature of the tube side is higher than that of the shell side. temperature-induced thermal stress.

A supply gas pipeline is arranged at the inlet of the circulating fan 1, and the supply gas pipeline is configured to supply gas when the circulating gas pressure is lower than the set value to stabilize the system pressure; it can be seen from the above that only a small amount of gas is needed in this embodiment to It can be fluidized, and the carrier gas is recycled, so that for powder materials that are easy to absorb moisture and deteriorate, dry air or inert gas such as nitrogen can be selected. Compared with the traditional fluidized bed cooler, the gas The circulation volume is greatly reduced; under normal operating conditions, only a very small amount of gas needs to be supplemented or discharged to balance the system pressure; and for powders with a particle size below 30 μm, it is not easy to form a stable fluidized bed technical problem , the air velocity controlled by the cooling system in this embodiment is greater than the take-out velocity of all particles, and the gas-solid two phases do not need to form a stable bed with clear boundaries, but only need to ensure that the heat exchange tube can flow out from the top to complete the cooling Operation, the control requirements are low, and the cooling difficulty of powder materials with small particle size is significantly reduced.

The specific implementation of this embodiment is:

1. Cooling process: the high temperature gas enters the fluidization chamber 27 of the powder fluidized cooler from the powder material inlet 22, and the circulating gas enters the flow uniformly through the air distribution plate 26 from the bottom gas inlet 21 of the powder fluidized cooler. In the strong chamber, the material is dispersed and uniformly enters the tube side of the heat exchange section of the powder fluidized cooler; at the same time, the cooling medium enters the shell side of the shell-and-tube heat exchange section 28 from the cooling medium inlet 23 at the upper end of the powder fluidized cooler. The circulating fan 1 keeps the solid powder in a state similar to a high-speed fluid, and sufficient heat exchange is performed between the powder, the carrier gas and the tube wall, and the gas and the powder have been fully exchanged during the process of flowing through the shell-and-tube heat exchange section 28. The temperature of the exhaust gas is close to the temperature of the powder material; it is only necessary to measure the exhaust gas temperature of the cyclone separator 3 to adjust the opening of the inlet valve of the cooling medium, and the discharge temperature of the powder material can be precisely controlled, and the control loop is simple.

2. Separation process: the two phases of gas and powder flow out from the top outlet 25 of the powder fluidized cooler and enter the cyclone separator 3. Most of the powder material is output from the discharge port at the bottom of the cyclone separator 3, while a small part of the powder material flows with the gas phase. The outflow enters the bag filter, and after the ultrafine powder is removed in the bag filter, it enters the inlet of the circulating fan 1 as a fluidizing gas, and a supply air line is arranged at the inlet of the circulating fan 1 to stabilize the system pressure; thus, the fluidizing gas can be recycled. , greatly reduce the amount of gas used, and adjust the gas supply valve through the pressure to automatically supplement a small amount of gas lost due to leakage.

3. Output process: The cooled product materials discharged from the bottom of the cyclone separator 3 and the bag filter are transported to the finished product silo by the powder conveyor set at the bottom of the cyclone separator 3 and the bag filter.

Therefore, this embodiment cleverly combines fluidization technology with heat exchanger technology, and utilizes a small amount of gas to carry high-temperature powder materials to flow, so that solid powders are in a state similar to high-speed fluid for sufficient heat exchange, After the solid powder enters the fluidization chamber of the powder fluidization cooler, it is fluidized by a small amount of air or inert gas, and distributed into the tube side of the heat exchanger. The purpose of fluidization is to make the solid powder obtain and The properties of the fluid are similar, and the density of the entire gas-solid mixed phase is uniform, which is convenient for uniform transportation to each heat exchange tube, so as to achieve better performance for some powder materials with small particle size, easy moisture absorption or deterioration, and poor fluidity. The cooling effect can significantly improve the economic benefits of the enterprise; in this example, the production of active calcium oxide from calcined carbide slag that is easy to absorb moisture and deteriorate is an example. Packaging and transportation; Take a chlor-alkali plant with 400,000 tons/year PVC as an example, the amount of active calcium oxide that needs to be cooled is as high as 50 tons/hour, and the cooling heat load is as high as 28210000kJ/hr (7836kW). If the drying air is used for direct cooling, the outlet of the drying air is slightly lower than the outlet temperature of the material because the direct cooling is parallel heat transfer. If the drying air is 20°C and the outlet temperature is 80°C, it will consume 363000Nm ³ /hr of drying air ( Converted to 13794kg standard oil, the conversion standard adopts GB/T50441-2016, the same below), these dry air are not only used as fluidizing medium, but also heat exchange medium. The operating cost is high; if circulating water is used for cooling, it will consume 670m ³ /hr circulating water (converted to 40.2kg standard oil), and the operating cost of using circulating water will be greatly reduced. It is disclosed by the inventor that indirect heat exchange can be considered for cooling; direct cooling with dry air can be effectively avoided, and its energy consumption will make the process of calcining calcium carbide slag to produce active calcium oxide, a technical problem that is not feasible in itself.

In indirect heat exchange, using the existing cooler is not suitable for powder materials with fine particles and poor fluidity, because it is easy to bridge and block, and the cooling system in this embodiment only needs to use a very small amount of dry air to drive the particles. Flow, for example, to cool 50 tons/hour powder, only 4000-8000Nm ³ /hr dry air is needed. Since these air are only fluidized media, the heat has been transferred to the circulating water in the heat exchange section of the cooler, so only need It can be recycled after dust removal. This cooling system only has one energy-consuming equipment, the circulating fan 1. The actual operating cost is only the electric energy consumed by the circulating fan 1. The motor power is about 10kw, that is, only 10kwh/hr (converted to 2.2kg standard oil) is consumed, and the operating cost is extremely low. .

Especially for the cooling of metal particles and flammable and explosive powders, inert gases such as nitrogen or argon need to be used. The cost of these gases is several times or even dozens of times that of dry air. Therefore, for powders that need to be protected by inert gases Therefore, the cooling system provided in this embodiment can achieve better cooling effect for some powder materials with small particle size, easy moisture absorption or deterioration, and poor fluidity, and can significantly improve Enterprise economic benefits.

Embodiment 2

On the other hand, this embodiment also provides a cooling process for a powder material cooling system, using the above powder material cooling system, specifically including a start-up step and a shutdown step:

Driving steps:

Step 1, open the air supply valve on the air supply pipeline, turn on the circulating fan 1, and replace the air in the cooling system; during this process, the circulating fan 1 operates at a low load;

Step 2, open the feed valve of the powder material inlet 22, and the powder material enters the fluidization chamber 27 of the powder fluidization cooler to form a stable fluidization state, so that the powder material is evenly distributed in the air distribution. above plate 26;

Step 3, increase the flow rate of the circulating fan 1, and at the same time increase the feeding amount of the powder material. The powder material uniformly enters the tube side of the shell-and-tube heat exchange section 28 under the drive of the carrier gas and exits the top of the powder fluidized cooler 25. The gas-solid two-phase flows out from the top of the powder fluidized cooler and enters the cyclone separator 3 for separation; the powder material with larger particles is discharged from the bottom of the cyclone separator 3, while the particles Smaller powder materials enter the bag filter with the gas; and the cooling medium flow of the powder fluidized cooling shell and the temperature of the powder outlet are a regulating loop, and the temperature of the exhaust gas of the cyclone separator 3 is detected to adjust the cooling medium. The opening of the inlet valve can control the discharge temperature of the powder material after cooling from the powder fluidization cooler.

Step 4: The bag filter is controlled by pressure to carry out automatic back blowing and ash cleaning. The gas after removing the ultrafine powder in the bag filter enters the inlet of the circulating fan 1 for recycling. The cyclone 3 and the bottom of the bag filter are cooled and the product material is Delivered by powder conveyor.

Stopping steps: First, close the feeding valve of the powder material inlet 22, keep the circulating fan 1 to continue to circulate, and ensure that all the solid powder in the fluidization chamber 27 in the powder fluidization cooler is taken out from the cooler. After the cyclone separator 3 and the bottom of the bag filter have no solid discharge, the circulating fan 1 is gradually shut down, which can effectively avoid the blockage of solid powder in the cooler.

As a preferred solution of this embodiment, the cooling process of the powder material cooling system provided in this embodiment also has protection and protection interlocking measures, which are embodied as follows: (a) when detecting the material discharged from the top outlet 25 of the powder fluidization cooler If the temperature exceeds the interlock value, the interlock will cut off the powder feed valve; (b) the fan fails or trips, and the interlock will cut off the powder feed valve; (c) the pressure difference between the inlet and outlet of the powder fluidization cooler exceeds the interlock. value, the interlock shuts off the powder feed valve.

To sum up, the cooling process of this embodiment is simple to operate and has good practicability in practice. By measuring the exhaust gas temperature of the cyclone separator 3 to adjust the opening of the inlet valve of the cooling medium, the powder can be effectively and accurately controlled. The discharge temperature is high, the control loop is simple, the reliability is strong, and it has good engineering implementation, which is suitable for popularization and application.

The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims (10)

1. A powder material cooling system is characterized in that: comprising a circulating fan, a powder fluidized cooler, a cyclone separator, a bag filter and a powder material conveyor; wherein, the powder fluidized cooler is a vertical The lower end of the powder fluidized cooler is provided with a powder material inlet, the top outlet is connected to the inlet of the cyclone separator, and the bottom gas inlet of the powder fluidized cooler is connected to the outlet of the circulating fan , so that the gas-solid two-phase flows out from the top outlet of the powder fluidized cooler and then enters the cyclone separator; the bottom of the cyclone separator is the outlet for the product material after cooling, and the top is the tail gas outlet, and the cyclone separator The tail gas outlet at the top of the filter is connected to the bag filter; the bag filter is connected to the inlet of the circulating fan, so that the gas collected by the bag filter can be recycled as fluidizing gas; The bottom of the bag filter is provided with a powder conveyor, so that the product materials discharged from the bottom of the cyclone separator and the bag filter are sent out through the powder conveyor. 2 . The powder material cooling system according to claim 1 , wherein the powder fluidization cooler comprises a fluidization chamber and a shell-and-tube heat exchange section located above the fluidization chamber, so the The powder material inlet is communicated with the fluidization chamber, the tube side of the shell-and-tube heat exchange section is a gas-solid two-phase circulation channel, and the shell side of the shell-and-tube heat exchange section is a cooling medium circulation channel . 3. The powder material cooling system according to claim 2, wherein an air distribution plate is arranged at the bottom of the fluidization chamber, and the bottom gas inlet of the powder fluidization cooler is located on the positive side of the air distribution plate. below, so that the gas output by the circulating fan enters the fluidization chamber uniformly. 4. The powder material cooling system according to claim 3, wherein the air distribution plate is at least one of a double-layer mesh type air distribution plate, a hood type air distribution plate or a gill hole type air distribution plate. kind. 5. The powder material cooling system according to claim 2, characterized in that: the cooling medium in the shell side is at least one of air, water, heat transfer oil, octane or heptane; and the shell The cooling medium in the tube pass is opposite to the gas-solid two-phase flow direction in the tube pass. 6 . The powder material cooling system according to claim 2 , wherein the shell-and-tube heat exchange section comprises a heat exchange tube, a heat exchange tube sheet, a heat exchanger shell, and a heat exchange tube located in the heat exchanger shell. 7 . The top head structure, the heat exchange tube tube sheet is installed on the upper end and the lower end of the heat exchange tube shell, and the upper end and the lower end of the heat exchange tube tube sheet are correspondingly distributed with a number of circular holes, and each circular hole is A heat exchange tube connecting the fluidized chamber and the head structure is fixed. The top of the head structure, and the head structure and the heat exchange tube shell are flanged or welded, so that the gas-solid two-phase in the fluidized chamber enters the head structure through the heat exchange tube, and is located in the head structure. The top outlet at the top of the head structure flows out. 7. The powder material cooling system according to claim 6, characterized in that: the shell side of the shell-and-tube heat exchange section is provided with an expansion joint according to the temperature of the powder material, in order to eliminate the problem that the temperature of the tube side is higher than Thermal stress due to shell side temperature. 8 . The powder material cooling system according to claim 1 , wherein an air supply line is arranged at the inlet of the circulating fan, and the air supply line is configured to perform the operation when the circulating air pressure is lower than the set value. 9 . Make-up gas. 9. A cooling process for a powder material cooling system, characterized in that: applying the powder material cooling system according to any one of claims 1-8, comprising the following steps: Step 1, open the air supply valve on the air supply pipeline, turn on the circulating fan, and replace the air in the cooling system; Step 2: Open the feed valve at the inlet of the powder material, and the powder material enters the fluidization chamber of the powder fluidization cooler to form a stable fluidization state, so that the powder material is evenly distributed above the air distribution plate ; Step 3: Increase the flow rate of the circulating fan and increase the feeding amount of the powder material. The powder material uniformly enters the tube side of the shell-and-tube heat exchange section driven by the carrier gas and flows in the direction of the top outlet of the powder fluidized cooler. Carry out sufficient heat exchange; the gas-solid two phases flow out from the top of the powder fluidized cooler and enter the cyclone for separation; Step 4: The bag filter is controlled by pressure to perform automatic back blowing and cleaning, and the gas after removing the ultrafine powder in the bag filter enters the inlet of the circulating fan for recycling. Conveyor delivery. 10. The cooling process of the powder material cooling system according to claim 9, characterized in that: in step 3, the cooling medium flow rate of the powder fluidized cooling shell side and the temperature of the powder material outlet are a regulating loop, and by detecting The temperature of the exhaust gas of the cyclone adjusts the opening of the inlet valve of the cooling medium, thereby controlling the discharge temperature of the powder material after cooling from the powder fluidization cooler.

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