Low-energy-consumption calcium hydroxide production process

Abstract

The application relates to a calcium hydroxide preparation technology field, and particularly discloses a low-energy-consumption calcium hydroxide production process, which comprises the following steps: step one: dosing, preparing crushed raw lime and water according to a water-material ratio of 0.5-0.55; step two: water-digestion, stirring raw lime and water in a digester according to a proportion to complete a digestion process; step three: powder selection, purifying and separating the product obtained in the step two in a powder classifier to remove slag and obtain a calcium hydroxide product; and step four: slag circulation, circulating the slag obtained in the step three into the powder classifier to be separated again, and separating the calcium hydroxide product in the waste slag; the water temperature in the step two is heated through a heat recovery unit, the heat recovery unit comprises a dust collection fan, a dust collection bin and a heat exchanger, the dust collection fan is located above the digester, the dust collection fan sucks the dust-containing hot air above the digester into the dust collection bin, dust in the dust-containing hot air is filtered through the dust collection bin, the outlet of the dust collection bin is connected with the heat exchanger, the dust-containing hot air forms clean hot air after passing through the dust collection bin, the clean hot air enters the heat exchanger, the heat exchanger is externally provided with a circulating pump which can pass water flow into the heat exchanger, and the water temperature can be increased to 35-45 DEG C through the heat exchanger. The scheme can solve the problem that the dust-containing hot air cannot be recycled in the existing calcium hydroxide production process.

Description

Technical Field

[0001] This invention relates to the field of calcium hydroxide preparation technology, and specifically to a low-energy-consumption calcium hydroxide production process. Background Technology

[0002] Currently, the quicklime dispensed from the quicklime silo reacts chemically with added water in the digester to produce calcium hydroxide, while also generating a large amount of steam and undigested quicklime dust. However, due to the extremely sticky nature of the quicklime dust, the steam and quicklime dust easily adhere to the inner wall of the pipes as they pass through, causing blockages in a short time. Once the pipes are blocked, the blower cannot effectively remove the dust and steam, resulting in a large amount of dust in the workshop and affecting the operating environment. Furthermore, the dust adhering to the blower impeller also causes it to lose its dynamic balance, easily leading to vibrations and damage to the blower.

[0003] To address the aforementioned issues, existing production lines primarily employ existing filtration equipment such as baghouse dust collectors to filter dust-laden hot air. While this method prevents fan damage, it also has drawbacks. After a period of operation, dust tends to accumulate on the filter layer. This dust combines with steam in the hot air to form clumps that adhere to the filter layer surface, preventing it from functioning properly. This necessitates replacing the filter layer or disassembling and cleaning it, which not only impacts production efficiency but also incurs high cleaning costs. Therefore, a new calcium hydroxide production process is proposed that recovers and utilizes the dust-laden hot air generated during the calcium hydroxide production process while simultaneously improving the dust collection and treatment capabilities of this hot air. Summary of the Invention

[0004] The present invention provides a low-energy-consumption calcium hydroxide production process to solve the problem that existing calcium hydroxide production processes cannot recover and utilize the heat of dust-containing hot gas.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a low-energy-consumption calcium hydroxide production process.

[0006] Step 1: Prepare the ingredients, including crushed quicklime and water, at a water-to-material ratio of 0.5 to 0.55;

[0007] Step 2: Add water for digestion. Add quicklime and water to the digester in the correct proportion and stir to complete the digestion process.

[0008] Step 3: Powder selection. The product obtained in Step 2 is passed into a powder classifier for purification, separation and slag removal to obtain calcium hydroxide product.

[0009] Step 4: Slag recycling. The slag obtained in Step 3 is fed into the classifier and separator through a circulating fan for secondary separation, separating the calcium hydroxide product from the waste slag.

[0010] In step two, the water temperature is heated by a heat recovery unit, which includes a dust collection fan, a dust collection chamber, and a heat exchanger. The dust collection fan is located above the digester and draws dust-laden hot air from above the digester into the dust collection chamber. The dust in the dust-laden hot air is filtered out by the dust collection chamber. The outlet of the dust collection chamber is connected to the heat exchanger. After passing through the dust collection chamber, the dust-laden hot air becomes clean hot air and enters the heat exchanger. A circulation pump is installed outside the heat exchanger to allow water to flow into it. The heat exchanger can raise the water temperature to 35-45 degrees Celsius.

[0011] The basic principle and beneficial effects of this solution are as follows: During the process of stirring quicklime and water in the digester, a large amount of heat is generated, which evaporates the water to form high-temperature steam. At the same time, because some quicklime is not stirred and reacted completely, the quicklime powder is dispersed upward with the high-temperature steam. In addition, some of the calcium hydroxide products generated by the reaction are carried into the air. Since calcium hydroxide combines with carbon dioxide in the air to form calcium carbonate, lumps of powder easily adhere to the pipes, bag dust collectors, and fan blades in the existing technology. In this solution, the dust collection bin directly filters out the lumps of powder to obtain clean hot air. The subsequent fan does not directly contact the dust, avoiding lumps on the fan blades. The heat in the clean hot air is transferred to the water through the heat exchanger, raising the water temperature to 40 degrees Celsius. The hot water reacts with calcium oxide. During the reaction in the digester, the hot water can promote the reaction rate, accelerate the exothermic reaction, and promote the evaporation of water to form lime paste.

[0012] Furthermore, the water temperature in step two is 40.1℃.

[0013] Furthermore, the digester in step two includes a primary digester, a secondary digester, and a tertiary digester. The temperature of the primary digester is 70–71°C, the temperature of the secondary digester is 75–79°C, and the temperature of the tertiary digester is 85–87°C.

[0014] Furthermore, the slag material in step four is discharged into the collection cylinder of the external equipment via a slag material conveyor belt.

[0015] Furthermore, the dust collection bin includes a bin body, with an air inlet located in the lower center of the bin body. A guide plate is located above the air inlet inside the dust collection bin, and the upper wall of the guide plate is an upwardly convex arc shape. The dust collection fan is connected to the upper side wall of the dust collection bin. Several vertical filter channels are located above the guide plate, and a filter layer is provided on the outer wall of each filter channel. Cleaning brush heads are vertically slidably connected within each filter channel. A downwardly extending water collection trough is located at the lower end of the dust collection bin, and the water collection trough is filled with water. A valve is connected to the lower part of the water collection trough. The cleaning brush heads scrape off the clumps of dust in the filter channels, which then fall into the water to prevent the clumps of dust from returning to the filter channels under the action of hot airflow.

[0016] Furthermore, a drive mechanism is provided below the guide plate, and the guide plate is connected to the output shaft of the drive mechanism. The drive mechanism can drive the guide plate to move up and down below the filter layer. The outer wall of the guide plate is provided with a horizontally extending first limiting rib, and the inner wall of the dust collection chamber is provided with a horizontally extending second limiting rib. The second limiting rib is located at the highest displacement of the guide plate, and the upper end wall of the first limiting rib can contact the lower end wall of the second limiting rib. The up and down movement of the guide plate causes the guide plate to touch and vibrate the middle part of the filter layer, breaking up the agglomerated dust in the middle of the filter layer.

[0017] Furthermore, a flexible plate is provided on the upper sidewall of the dust collection bin. The flexible plate can be recessed into the dust collection bin. The flexible plate is positioned opposite the filter layer, and a striking hammer is provided on the sidewall of the flexible plate opposite the filter layer. The end wall of the filter layer that the striking hammer contacts is curved. The dust is vibrated by striking from the other side of the filter layer.

[0018] Furthermore, the lower end of the water collection tank is a tapered shape that tapers downwards.

[0019] Furthermore, the deflector is a metal deflector. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the dust collection bin in an embodiment of the present invention. Detailed Implementation

[0022] The following detailed description illustrates the specific implementation method:

[0023] The reference numerals in the accompanying drawings include: 1. Chamber body; 2. Air inlet; 3. Guide plate; 4. Drive mechanism; 5. Filter channel; 6. Filter layer; 7. Cleaning brush head; 8. Water collection tank; 91. First limiting rib; 92. Second limiting rib; 10. Flexible plate; 11. Striking hammer; 12. Air outlet.

[0024] The basic implementation examples are as follows: Figure 1 To be continued Figure 2 As shown:

[0025] A low-energy-consumption calcium hydroxide production process,

[0026] Step 1: Prepare the ingredients: Prepare crushed quicklime and water at a water-to-material ratio of 0.53;

[0027] Step 2: Add water for digestion. In this embodiment, the water temperature is 40.1℃. Quicklime and water are added to the digester in proportion and stirred to complete the digestion process. In this embodiment, the digester is a three-stage digester, where the temperature of the first stage digester is 70.4℃, the temperature of the second stage digester is 78.7℃, and the temperature of the third stage digester is 86.2℃.

[0028] In this embodiment, a large amount of dust-laden water vapor formed by the reaction of quicklime and water in the digester is collected by a heat recovery unit installed above the digester, and the water is heated to 40.1°C through a heat exchanger connected to the heat recovery unit.

[0029] Step 3: Powder selection. The product obtained in Step 2 is passed into a powder classifier for purification, separation and slag removal to obtain calcium hydroxide product.

[0030] Step 4: Slag Recycling. The slag obtained in Step 3 is fed into a classifier via a circulating fan for secondary separation, separating the calcium hydroxide product from the waste slag. The waste slag obtained in this step is discharged onto a slag conveyor belt below the classifier, thereby transporting the entire batch of waste slag to an external facility for mass processing.

[0031] Specifically, the heat recovery unit in step two includes a dust collection fan, a dust collection bin, and a heat exchanger. The dust collection bin is installed above the digester, and an air inlet 2 is located at the bottom of the dust collection bin. The air inlet 2 is connected to the interior of the first-stage digester, the second-stage digester, and the third-stage digester through pipes, thereby allowing all the dust-laden steam generated in the three digesters to be introduced into the dust collection bin. After passing through the dust collection bin, the dust is filtered out, and clean hot steam is discharged from the dust collection bin outlet 12. The clean hot steam is introduced into the heat exchanger through pipes. At the same time, a circulating pump is installed outside the heat exchanger to allow water to flow into the heat exchanger. The heat exchanger transfers the heat of the hot steam to the water flow, heating the water flow to 40.1°C.

[0032] Specifically, the structure of the dust collection bin is as follows: Figure 2 As shown, the dust collection chamber includes a chamber body 1. The bottom of the chamber body 1 is symmetrically arranged, and a downward-facing air inlet 2 is opened at the central axis of the bottom of the chamber body 1. Two conical water collection tanks 8 extend downwards from the outer side of the air inlet 2, filled with water. A guide plate 3 is horizontally installed above the air inlet 2 inside the chamber body 1. The output shaft of an external drive mechanism 4 is connected to the bottom of the guide plate 3, and the output shaft is keyed to the guide plate 3. In this embodiment, the drive mechanism 4 is a telescopic motor. The top wall of the guide plate 3 is an upward-convex arc surface. The guide plate 3 is made of metal. When dust-laden hot air enters the dust collection chamber from the air inlet 2, the temperature of the dust-laden hot air reaches 100 degrees Celsius, thus transferring some heat to the metal guide plate 3. After the guide plate 3 absorbs heat, the surface of the guide plate 3 is less prone to dust adhesion.

[0033] A first limiting rib 91 extending horizontally outward is provided on the outer peripheral wall of the deflector 3, and a horizontal second limiting rib 92 is provided on the side wall of the bin body 1 above the deflector 3. The second limiting ribs 92 are respectively disposed on two opposite side walls of the bin body 1, and the height of the second limiting ribs 92 is located at the maximum upward displacement position of the deflector 3. Thus, when the deflector 3 moves to the highest displacement point, the lower end wall of the second limiting rib 92 comes into contact with the upper end wall of the first limiting rib 91 of the deflector 3. The first limiting rib 91 limits the deflector 3 from both sides of the deflector 3. Meanwhile, after the second limiting rib 92 comes into contact with the first limiting rib 91, the interior of the bin body 1 is divided into an upper space and a lower space, so that the dust-containing hot gas cannot enter the upper space of the bin body 1.

[0034] Two symmetrical and vertical filter channels 5 are arranged in the upper space of the bin body 1. Each single filter channel 5 is in a "几" shape, and the two "几"-shaped structures are connected to form a "concave" structure. The side walls and the middle bottom wall of the filter channel 5 are filter layers 6, and the filter layer 6 has a mesh structure. A horizontal cleaning brush head 7 is slidably connected to the inner wall of the filter channel 5, and the outer wall of the cleaning brush head 7 is in contact with the inner wall of the filter channel 5. The upper end of the cleaning brush head 7 is keyed to a driving mechanism 4 arranged outside the bin body 1, and the driving mechanism 4 can drive the cleaning brush head 7 to slide up and down.

[0035] A flexible plate 10 that can be recessed toward the inside of the bin body 1 is provided on the upper side wall of the bin body 1, such as Figure 2 As shown, the flexible plate 10 is arranged parallel to the vertical filter layer 6. On the side of the flexible plate 10 close to the filter layer 6, knocking hammers 11 are arranged at intervals along the height direction. The cross-section of the knocking hammer 11 that contacts the filter layer 6 is a curved surface. When the flexible plate 10 is relatively recessed, the knocking hammer 11 on the flexible plate 10 comes into contact with the filter layer 6, and at the same time, the agglomerated dust adhered on the filter layer 6 falls off.

[0036] In this embodiment, the air outlet 12 of the bin body 1 is located beside the flexible plate 10, the air outlet 12 is located inside the space enclosed by the filter layer 6 and the top side wall of the bin body 1, and the air outlet 12 of the bin body 1 is horizontally communicated with an external dust collecting fan, which guides the dust-containing airflow out of the bin body 1.

[0037] The specific implementation process is as follows:

[0038] The digester generates a large amount of heat during the mixing of quicklime and water, which evaporates the water to form high-temperature steam. Simultaneously, because some quicklime is not fully mixed and reacted, quicklime powder rises with the high-temperature steam, carrying some of the calcium hydroxide product into the air. Since calcium hydroxide combines with carbon dioxide in the air to form calcium carbonate, clumps of powder easily adhere to the pipes, bag filters, and fan blades in existing technologies. In this solution, the dust-laden gas enters from below the dust collection chamber, passes below the guide plate 3 and along the side wall, and then enters above the guide plate 3. The dust-laden gas then enters the filter layer 6 above the chamber body 1. Because the dust in the gas is blocked by the filter layer 6, the dust-laden gas... The steam is purified into clean hot steam, thus preventing the formation of agglomerated powder on the fan blades. Over time, agglomerated powder adheres to the filter layer 6. When the agglomerated powder blocks the mesh of the filter layer 6, it needs to be cleaned. At this time, the drive mechanism 4 is activated, causing the cleaning brush to slide downwards under the action of the cleaning mechanism. The outer wall of the cleaning brush contacts the filter layer 6, pushing down the agglomerated dust on the filter layer 6, thus cleaning the filter layer 6. When the agglomerated dust falls to the guide plate 3, it slides down the arc surface at the upper end of the guide plate 3 and falls into the water collection tank 8 at the bottom of the chamber 1. The water in the water collection tank 8 combines with the agglomerated dust, causing the agglomerated dust to be adsorbed in the water collection tank 8, thus preventing the subsequent dust-laden hot air from bringing the fallen agglomerated dust back into the upper space of the chamber 1. Since the guide plate 3 is made of metal, it can absorb heat under the action of hot airflow, and the powder on the guide plate 3 is not easily adhered to the surface of the guide plate 3 under the action of hot steam.

[0039] Meanwhile, when cleaning the filter layer 6, the drive mechanism 4 can first drive the guide plate 3 to move upward to its maximum displacement, so that the first limiting rib 91 and the second limiting rib 92 on the guide plate 3 fit together, thereby sealing the upper space of the chamber 1. At this time, since the dust collection fan is still working, the dust collection fan will draw out the gas in the upper space, and a negative pressure will be formed in the upper space. The flexible plate 10 will bend into the chamber 1, thereby driving the hammer 11 on the flexible plate 10 to strike the filter layer 6, causing the powder on the filter layer 6 to fall downward.

[0040] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A low-energy-consumption calcium hydroxide production process, characterized in that: Includes the following steps, Step 1: Prepare the ingredients, including crushed quicklime and water, with a water-to-material ratio of 0.5~0.55; Step 2: Add water for digestion. Add quicklime and water to the digester in the correct proportion and stir to complete the digestion process. Step 3: Powder selection. The product obtained in Step 2 is passed into a powder classifier for purification, separation and slag removal to obtain calcium hydroxide product. Step 4: Slag recycling. The slag obtained in Step 3 is fed into the classifier and separator through a circulating fan for secondary separation, separating the calcium hydroxide product from the waste slag. In step two, the water temperature is heated by a heat recovery unit, which includes a dust collection fan, a dust collection bin, and a heat exchanger. The dust collection fan is located above the digester and draws dust-laden hot air from above the digester into the dust collection bin. The dust in the dust-laden hot air is filtered out by the dust collection bin. The outlet of the dust collection bin is connected to the heat exchanger. After passing through the dust collection bin, the dust-laden hot air becomes clean hot air and enters the heat exchanger. A circulation pump is installed outside the heat exchanger to allow water to flow into the heat exchanger. The heat exchanger can raise the water temperature to 35-45 degrees Celsius. The dust collection bin includes a bin body, with an air inlet in the lower center of the bin body. A guide plate is provided above the air inlet inside the dust collection bin, and the upper wall of the guide plate is an upwardly convex arc shape. The dust collection fan is connected to the upper side wall of the dust collection bin. Several vertical filter channels are provided above the guide plate, and a filter layer is provided on the outer wall of the filter channel. A cleaning brush head is vertically slidably connected inside the filter channel. A downwardly extending water collection tank is provided at the lower end of the dust collection bin, and the water collection tank is filled with water. A valve is connected to the lower part of the water collection tank. A driving mechanism is provided below the guide plate, and the guide plate is connected to the output shaft of the driving mechanism. The driving mechanism can drive the guide plate to move up and down below the filter layer. A first limiting rib extending horizontally is provided on the outer wall of the guide plate, and a second limiting rib is provided horizontally on the inner wall of the dust collection chamber. The second limiting rib is located at the highest displacement of the guide plate, and the upper end wall of the first limiting rib can contact the lower end wall of the second limiting rib. A flexible plate is provided on the upper side wall of the dust collection chamber. The flexible plate can be recessed into the dust collection chamber. The flexible plate is arranged opposite to the filter layer. A hammer is provided on the side wall of the flexible plate opposite to the filter layer. The end wall of the hammer that contacts the filter layer is arc-shaped. The lower end of the water collection tank is a downwardly tapered cone.

2. The low-energy-consumption calcium hydroxide production process according to claim 1, characterized in that: The water temperature in step two is 40.1℃.

3. The low-energy-consumption calcium hydroxide production process according to claim 2, characterized in that: The digester in step two includes a primary digester, a secondary digester, and a tertiary digester. The temperature of the primary digester is 70~71℃, the temperature of the secondary digester is 75~79℃, and the temperature of the tertiary digester is 85~87℃.

4. The low-energy-consumption calcium hydroxide production process according to claim 3, characterized in that: In step four, the slag is discharged into an external collection cylinder via a slag conveyor belt.

5. The low-energy-consumption calcium hydroxide production process according to claim 1, characterized in that: The guide plate is a metal guide plate.

Images