Limestone-gypsum method desulfurization slurry preparation system

Abstract

The utility model relates to the technical field of wastewater purification, in particular to a limestone-gypsum method desulfurization slurry preparation system. Comprising an accelerated clarification tank, and an ozone oxidation zone, a sludge buffer zone and a sludge settling zone which are communicated with one another are sequentially arranged in the accelerated clarification tank from top to bottom; an ozone uniform distribution device is arranged in the ozone oxidation zone and comprises an air inlet pipe, an air outlet pipe and an ozone outlet pipe, and air outlet holes are formed in the wall surface of the air inlet pipe; the ozone uniform distribution unit modules are arranged at intervals in the axial direction of the air inlet pipe, each ozone uniform distribution unit module comprises a fixing plate arranged in the vertical direction, the fixing plates are fixedly connected with the air inlet pipe, the wall face of each fixing plate is sequentially connected with a plurality of umbrella-shaped airflow uniform distribution plates from top to bottom, and airflow holes are formed in the umbrella-shaped airflow uniform distribution plates. Impurities such as organic matters in the solid-containing slurry can be effectively removed, and the gypsum quality can be improved; meanwhile, the oxygen content of the slurry is increased, and the energy consumption of an oxidation fan of a desulfurization facility is reduced.

Description

Technical Field

[0001] This utility model relates to the field of wastewater purification technology, and in particular to a limestone-gypsum desulfurization slurry preparation system. Background Technology

[0002] Currently, the limestone-gypsum wet flue gas desulfurization process has become the mainstream desulfurization process for large-scale coal-fired power units in China due to its mature technology, stable operation, and high desulfurization efficiency. However, the consumption of limestone powder as a desulfurizing agent is relatively large, accounting for more than 35% of the desulfurization operating cost, which increases the desulfurization operating cost.

[0003] Calcium carbide slag is the residue from the hydration of acetylene gas produced by calcium carbide in petrochemical enterprises. It is widely available and inexpensive, costing only one-third of limestone powder. The main component of calcium carbide slag is Ca(OH)2, with a content of 60% to 85%. It is an excellent SO2 absorbent, with a desulfurization efficiency of 95% to 98%, which can significantly reduce desulfurization operating costs. In addition, calcium carbide slag is strongly alkaline, with a pH value of about 12.55. Waste calcium carbide slag can cause serious pollution to the surrounding environment. Using calcium carbide slag to produce high-purity calcium carbonate and using calcium carbonate to absorb SO2 can effectively solve the above problems.

[0004] Meanwhile, when treating the raw water produced by coal-fired power units, a large amount of Ca(OH)2 with a purity of over 95% is required to remove turbidity from the raw water. The CaCO3 sludge produced during the treatment process is usually treated as waste sludge, which increases the treatment costs for power generation companies.

[0005] Therefore, we can use the raw water produced by coal-fired power units to pretreat calcium carbide slag. The raw water reacts with the calcium carbide slag slurry to obtain a slurry containing a large amount of calcium carbonate. The prepared calcium carbonate slurry can be used for desulfurization to generate gypsum. However, in practical work, the above treatment method has the following drawbacks:

[0006] First, the CaCO3 slurry produced after the pretreatment of raw water and carbide slag contains a large amount of organic impurities. When CaCO3 slurry containing organic impurities is used directly as a desulfurizing agent, there are problems such as equipment scaling, difficulty in controlling the pH value of the slurry, and severe foaming of the slurry, which leads to a decrease in desulfurization efficiency.

[0007] Second, CaCO3 slurry contains a large amount of organic matter, which will generate a large number of bubbles during the desulfurization process, clogging the pores between the gypsum and preventing the gypsum from dehydrating.

[0008] Third, the SO2 concentration at the inlet of the desulfurization secondary tower is low, but the oxidation blower of the secondary tower is usually a power frequency blower and operates at full load, resulting in high energy consumption of the desulfurization equipment. Utility Model Content

[0009] The purpose of this invention is to overcome the above-mentioned defects in the existing technology and propose a limestone-gypsum desulfurization slurry preparation system. This system can effectively remove organic matter and other impurities from the solid slurry, improve the slurry quality, significantly reduce the probability of desulfurization slurry overflow, and improve gypsum quality. At the same time, it increases the oxygen content of the slurry, which is beneficial to the oxidation reaction of calcium sulfite and reduces the energy consumption of the oxidation fan in the desulfurization facility.

[0010] The technical solution of this utility model is: a limestone-gypsum desulfurization slurry preparation system, including an accelerated clarification tank, wherein the accelerated clarification tank is provided with an ozone oxidation zone, a sludge buffer zone and a sludge settling zone connected to each other from top to bottom;

[0011] An ozone distribution device is installed within the ozone oxidation zone. The ozone distribution device includes:

[0012] The air intake duct has air outlet holes on its wall surface;

[0013] Several ozone distribution unit modules are spaced apart along the axial direction of the air intake duct. Each ozone distribution unit module includes a fixed plate arranged vertically and fixedly connected to the air intake duct. Several umbrella-shaped airflow distribution plates are fixedly fixed on the wall of the fixed plate from top to bottom, and airflow holes are provided on the umbrella-shaped airflow distribution plates.

[0014] In this utility model, several ozone distribution devices are provided in the ozone oxidation zone. Each air inlet pipe in the ozone distribution device extends along the length of the accelerated clarification tank, and several air inlet pipes are spaced apart along the width of the accelerated clarification tank.

[0015] Several support beams are installed below the air intake duct. The support beams are spaced apart along the width of the accelerated clarification tank, and the air intake duct is perpendicular to the support beams.

[0016] The umbrella-shaped airflow distribution plate includes two distribution plates that are at a certain angle to each other, and the top edges of the two distribution plates are fixedly connected.

[0017] The umbrella-shaped airflow distribution plate is fixedly connected to the fixed plate via a central fixing plate. The central fixing plate is set in the vertical direction and is fixedly connected to the vertical center of the fixed plate.

[0018] In all ozone distribution unit modules, the umbrella-shaped airflow distribution plate is located on the wall on the same side as the fixed plate.

[0019] The top of the accelerated clarification tank is equipped with a raw water inlet and a calcium carbide slag slurry inlet, which are connected to the ozone oxidation zone respectively.

[0020] The accelerated clarification tank is equipped with a wastewater overflow outlet at its upper part;

[0021] The bottom of the accelerated clarification tank is equipped with a sludge discharge outlet, which is connected to the sludge settling zone.

[0022] The beneficial effects of this utility model are:

[0023] (1) Use carbide slag to replace quicklime in the deep treatment system of reclaimed water to achieve pH adjustment of reclaimed water from coal-fired units. The price of carbide slag is only 1 / 3 of that of lime powder, which greatly reduces the dosing and operating costs of reclaimed water pretreatment in coal-fired units.

[0024] (2) Using solid waste carbide slag as raw material, limestone-gypsum wet desulfurization agent-limestone slurry is produced, which effectively replaces quicklime with carbide slag to remove CO3 from the raw water of reclaimed water. 2- In addition, calcium carbonate slurry can be generated in the process, which can be used as a desulfurizing agent in limestone-gypsum wet process, reducing the stone powder consumption of desulfurization system, thereby effectively reducing the production cost of calcium carbonate and realizing waste treatment.

[0025] (3) Ozone is used to oxidize the solid slurry obtained after reacting carbide slag and reclaimed water to remove organic matter and other impurities in the solid slurry, significantly reducing organic impurities in the slurry, improving slurry quality, significantly reducing the probability of desulfurization slurry overflow, and improving gypsum quality.

[0026] (4) Ozone reacts with organic matter to generate oxygen. Some ozone and oxygen dissolve in the solid slurry, which increases the oxygen content of the solid slurry and is conducive to slurry oxidation. The calcium carbonate in the solid slurry reacts with SO2 in the flue gas to generate calcium sulfite. As the oxygen content of the solid slurry increases, it is conducive to the oxidation reaction of calcium sulfite, which reduces the output of the oxidation fan and can reduce the energy consumption of the oxidation fan in the desulfurization facility. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the main structure of the limestone-gypsum desulfurization slurry preparation system;

[0028] Figure 2 This is a schematic diagram of the right-hand structure of the limestone-gypsum desulfurization slurry preparation system;

[0029] Figure 3 This is a schematic diagram of the air intake duct in an ozone distribution device;

[0030] Figure 4 This is a schematic diagram of the main structure of an ozone distribution device.

[0031] Figure 5 This is a schematic diagram of the left-side structure of an ozone distribution device;

[0032] Figure 6 This is a structural diagram of the fixed plate.

[0033] In the diagram: 1. Accelerated clarification tank; 2. Ozone oxidation zone; 3. Sludge buffer zone; 4. Sludge settling zone; 5. Raw water inlet; 6. Calcium carbide slag slurry inlet; 7. Wastewater overflow outlet; 8. Sludge outlet; 9. Ozone distribution device; 10. Duct support beam; 11. Inlet connecting pipe. Detailed Implementation

[0034] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0035] Specific details are set forth in the following description to provide a full understanding of the present invention. However, the present invention can be implemented in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] like Figure 1 and Figure 2 As shown, the limestone-gypsum desulfurization slurry preparation system of this utility model includes an accelerated clarification tank 1, which is divided into an ozone oxidation zone 2, a sludge buffer zone 3, and a sludge settling zone 4 from top to bottom. The ozone oxidation zone 2, the sludge buffer zone 3, and the sludge settling zone 4 are connected sequentially from top to bottom.

[0037] The top of the accelerated clarification tank 1 is equipped with a raw water inlet 5 and a calcium carbide slag slurry inlet 6, both of which are connected to the ozone oxidation zone 2. Raw water discharged from the coal-fired unit enters the ozone oxidation zone 2 of the accelerated clarification tank 1 through the raw water inlet 5. Solid calcium carbide slag is crushed by a calcium carbide slag crusher to obtain calcium carbide slag slurry, which enters the ozone oxidation zone 2 of the accelerated clarification tank 1 through the calcium carbide slag slurry inlet 6.

[0038] The accelerated clarification tank 1 is equipped with a wastewater overflow outlet 7 at its upper part, which is connected to the ozone oxidation zone 2. The accelerated clarification tank 1 is equipped with a sludge discharge outlet 8 at its bottom, which is connected to the sludge settling zone 4.

[0039] During the desulfurization process, sludge discharge port 8 is connected to the slurry replenishment port of the secondary desulfurization absorption tower.

[0040] The ozone oxidation zone 2 is equipped with several ozone distribution devices 9, which are placed on the duct support beam 10. Therefore, in this application, the location of the duct support beam 10 is essentially the boundary between the ozone oxidation zone 2 and the sludge buffer zone 3.

[0041] The raw water for reclaimed water from the coal-fired power unit enters the accelerated clarification tank 1 through the raw water inlet 5. Calcium carbide slag with a median particle size of approximately 75 μm is added to the calcium carbide slag crusher and ground to a set particle size range of 25–40 μm. After separation by a limestone slurry hydrocyclone, a fixed amount of calcium carbide slag slurry is added to the accelerated clarification tank 1 through the calcium carbide slag slurry inlet 6 via a slurry pump and metering conveying equipment.

[0042] Within ozone oxidation zone 2, calcium hydroxide in the carbide slag slurry reacts with carbonate ions in the raw water to form calcium carbonate, thus treating the raw water. The resulting calcium carbonate slurry, along with other solids, gradually falls to the sludge buffer tank 3 under gravity and eventually settles into the sludge settling zone 4. When the sludge concentration reaches 1100–1200 kg / m³... 3 At that time, the solid slurry is pumped through sludge discharge port 8 to the sludge replenishment port of the secondary desulfurization absorption tower to replenish the slurry in the slurry pool of the secondary desulfurization absorption tower. The supernatant after wastewater treatment is discharged through wastewater overflow discharge port 7.

[0043] like Figures 3 to 6 As shown, the ozone distribution device includes an air inlet duct 9-1. The air inlet duct 9-1 extends along the length of the accelerated clarification tank 1, and several air inlet ducts 9-1 are spaced apart along the width of the accelerated clarification tank 1, as shown... Figure 4 As shown. Since the number of air inlet ducts 9-1 and ozone distribution devices corresponds, an array of ozone distribution devices is provided at intervals along the width of the accelerated clarification tank 1.

[0044] One end of the air inlet duct 9-1 is fixedly connected to the inner wall of the accelerated clarification tank 1, and the other end of the air inlet duct 9-1 is located on the outer side of the accelerated clarification tank 1 and connected to the inlet connecting pipe 11. Air outlet holes 9-2 are provided on the outer surface of the air inlet duct 9-1, and are spaced apart along the circumference and axial direction of the air inlet duct 9-1, thus providing multiple air outlet holes 9-2 on the air inlet duct 9-1. Ozone enters the air inlet duct 9-1 through the inlet connecting pipe 11 and then enters the accelerated clarification tank 1 through the air outlet holes 9-1.

[0045] Below the air intake duct 9-1, there is a duct support beam 10, which is fixedly connected to the inner wall of the accelerating clarification tank 1. The air intake duct 9-1 is placed on the duct support beam 10, which provides support for the air intake duct 9-1. In this embodiment, the air intake duct 9-1 and the duct support beam 10 are arranged perpendicularly. That is, the duct support beam 10 extends along the width direction of the accelerating clarification tank 1, and several duct support beams 10 are spaced apart along the length direction of the accelerating clarification tank 1.

[0046] Several ozone distribution unit modules are arranged along the length of the air intake duct 9-1. Each ozone distribution unit module includes a fixing plate 9-3, which is vertically positioned and its bottom end is fixedly connected to the upper surface of the air intake duct 9-1. Several umbrella-shaped airflow distribution plates 9-4 are fixed to the wall of the fixing plate 9-3, and these umbrella-shaped airflow distribution plates 9-4 are arranged sequentially at intervals along the vertical direction. Each umbrella-shaped airflow distribution plate 9-4 is fixedly connected to the fixing plate 9-3 via a central fixing plate 9-5. The central fixing plate is vertically positioned at the vertical center of the fixing plate and is fixedly connected to it.

[0047] The umbrella-shaped airflow distribution plate 9-4 is composed of two distribution plates connected at a certain angle to each other, with their top ends fixedly connected to form the umbrella-shaped airflow distribution plate. The connection point between the top ends of the two distribution plates is fixedly connected to the central fixing plate 9-5. The umbrella-shaped airflow distribution plate 9-4 is provided with several airflow holes, and the airflow holes of the umbrella-shaped airflow distribution plates arranged vertically can be staggered or aligned. In this embodiment, the diameter of the airflow holes is 5mm.

[0048] After ozone flows out through the air outlet 9-2 on the air inlet duct 9-1, most of the ozone rises and flows into the solid slurry produced by the reaction of calcium hydroxide and raw water. During the ozone's ascent, the umbrella-shaped airflow distribution plate distributes and blocks the ozone, increasing its residence time in the slurry and allowing for sufficient oxidation of organic matter. It also evens out the airflow, further facilitating wastewater oxidation, removing organic matter from the slurry, and preventing the formation of large amounts of organic sludge that could contaminate the solid slurry. The solid slurry prepared in this application can be used directly as a desulfurization slurry.

[0049] In this embodiment, three air outlet pipes 9-1 are spaced apart along the width of the accelerated clarification tank 1, and four ozone uniform distribution unit modules are spaced apart on each air outlet pipe 9-1. Therefore, the accelerated clarification tank 1 in this embodiment is provided with twelve ozone uniform distribution unit modules.

[0050] Meanwhile, two umbrella-shaped airflow distribution plates 9-4 are provided on one side of the fixed plate 9-3, which are arranged vertically at intervals. In all ozone distribution unit modules, the umbrella-shaped airflow distribution plates 9-4 are located on the same side of the fixed plate 9-3.

[0051] In this application, umbrella-shaped airflow distribution plates 9-4 can also be set on both sides of the fixed plate 9-3, as long as they can achieve the function of blocking and distributing ozone.

[0052] The principle of ozone oxidation for removing organic impurities from slurry is as follows. Ozone molecules (O3) themselves have strong oxidizing properties and can directly attack unsaturated bonds, aromatic rings, or specific functional groups, such as amino and thiol groups, in organic molecules. By breaking chemical bonds, they decompose large organic molecules into smaller compounds such as carboxylic acids and aldehydes, or completely mineralize them into CO2 and H2O.

[0053] At the same time, ozone can also oxidize the cell walls of microorganisms in activated sludge, releasing intracellular substances into the water body, and reducing sludge volume through secondary degradation by microorganisms; in addition, it can remove sulfur / nitrogen-containing odor substances. Ozone directly destroys chromophores or active groups, achieving decolorization and deodorization.

[0054] The oxidation process of ozone on sludge slurry occurs not only in ozone oxidation zone 2, but also in sludge buffer zone 3. A small amount of ozone flowing in through air inlet duct 9-1 enters sludge buffer zone 3 and can oxidize the sludge slurry in the sludge buffer zone, thus achieving full oxidation of the organic matter in the sludge slurry.

[0055] Ozone oxidizes the organic matter in the slurry to produce oxygen. A small portion of the ozone and oxygen dissolve into the slurry, increasing its oxygen content to approximately 40%. The remaining approximately 60% of the oxygen escapes into the air through the slurry surface.

[0056] When sludge slurry with a high oxygen content enters the desulfurization absorption tower, it can not only remove SO2 from the flue gas, but also, as shown in the following reaction formula, remove SO2 from the flue gas.

[0057]

[0058] It also increases the oxygen content in the slurry, which is beneficial to the oxidation reaction of calcium sulfite, as shown in the following reaction formula.

[0059]

[0060] At this point, the output of the oxidation fan can be reduced, or even the oxidation fan of the desulfurization absorption tower can be completely shut down, which greatly reduces the energy consumption of the desulfurization absorption tower.

[0061] The limestone-gypsum desulfurization slurry preparation system provided by this utility model has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model. The above description of the disclosed embodiments enables those skilled in the art to implement or use this utility model. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this utility model. Therefore, this utility model is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A limestone-gypsum desulfurization slurry preparation system, comprising an accelerated clarification tank, characterized in that, The accelerated clarification tank is provided with an interconnected ozone oxidation zone, a sludge buffer zone, and a sludge settling zone from top to bottom. An ozone distribution device is installed within the ozone oxidation zone. The ozone distribution device includes: The air intake duct has air outlet holes on its wall surface; Several ozone distribution unit modules are spaced apart along the axial direction of the air intake duct. Each ozone distribution unit module includes a fixed plate arranged vertically and fixedly connected to the air intake duct. Several umbrella-shaped airflow distribution plates are connected sequentially from top to bottom on the wall of the fixed plate, and airflow holes are provided on the umbrella-shaped airflow distribution plates.

2. The limestone-gypsum desulfurization slurry preparation system according to claim 1, characterized in that, Several ozone distribution devices are installed in the ozone oxidation zone. Each air inlet pipe in the ozone distribution device extends along the length of the accelerated clarification tank and is spaced apart along the width of the accelerated clarification tank. Several support beams are installed below the air intake duct. The support beams are spaced apart along the width of the accelerated clarification tank, and the air intake duct is perpendicular to the support beams.

3. The limestone-gypsum desulfurization slurry preparation system according to claim 1, characterized in that, The umbrella-shaped airflow distribution plate includes two distribution plates that are at a certain angle to each other, and the top edges of the two distribution plates are fixedly connected. The umbrella-shaped airflow distribution plate is fixedly connected to the fixed plate via a central fixing plate. The central fixing plate is set in the vertical direction and is fixedly connected to the vertical center of the fixed plate.

4. The limestone-gypsum desulfurization slurry preparation system according to claim 1, characterized in that, In all ozone distribution unit modules, the umbrella-shaped airflow distribution plate is located on the wall on the same side as the fixed plate.

5. The limestone-gypsum desulfurization slurry preparation system according to claim 1, characterized in that, The top of the accelerated clarification tank is equipped with a raw water inlet and a calcium carbide slag slurry inlet, which are connected to the ozone oxidation zone respectively. The accelerated clarification tank is equipped with a wastewater overflow outlet at its upper part; The bottom of the accelerated clarification tank is equipped with a sludge discharge outlet, which is connected to the sludge settling zone.

Images