Process for preparing desulfurization slurry by using carbide slag

Abstract

The invention relates to a process for preparing desulfurization slurry by using carbide slag. The process comprises the following steps: (1) conveying water-containing wet carbide slag to a slag flushing tank by a feeder; the carbide slag raw material is mixed with water and then flows into the slurrying tank through the slag flushing tank; (2) quickly dissolving the carbide slag in the slurrying pool, and circularly conveying the slurry back to the slurrying pool by a slurry pump for fully dissolving; (3) when the slurry concentration condition is met, the slurry can be conveyed to a transfer pool; (4) introducing air into the transfer pool under the action of a stirrer for oxidation; (5) conveying the oxidized qualified slurry into a finished product slurry tank through a transfer pump; the carbide slag waste can be applied to the desulfurization system on the spot, the application of limestone is reduced, resources are saved, meanwhile, the waste discharge is reduced, the environment is protected, the power generation cost is saved, and the economic benefit is improved.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste treatment and coal-fired flue gas desulfurization, and in particular to a process for preparing desulfurization slurry by utilizing carbide slag. Background Art

[0002] Calcium carbide slag is the waste residue with calcium hydroxide as the main component after acetylene gas is obtained by hydrolysis of calcium carbide. Acetylene (C2H2) is one of the important raw materials for the basic organic synthesis industry. The process of producing acetylene by adding water (wet process) with calcium carbide (CaC2) as raw material accounts for a large proportion in my country. Calcium carbide slag is usually discharged on a wet basis, which is easy to leak and pollute the road surface during transportation. Long-term accumulation not only occupies a large amount of land, but also has serious erosion and pollution effects on land and water bodies. my country discharges more than 10 million tons (dry basis) of calcium carbide slag every year, about 40% of which has been comprehensively treated, and the rest is still mainly stored or landfilled, which puts great pressure on the environment. A large amount of calcium carbide slag is produced every year in industrial production. The amount of calcium carbide slag is large and the alkali content is high. Stacking on land occupies land and pollutes the environment.

[0003] At present, carbide slag is mainly used in the cement industry, where carbide slag is used to replace limestone to produce cement. However, due to the high water content of carbide slag, the heat consumption ratio is high and the kiln output is low during the production process. At the same time, the water vapor content at the end of the kiln is large, which affects the use effect and life of the subsequent dust collector. In order to fundamentally solve the problem, we can only seek new treatment processes in technology, make comprehensive use of it, turn harm into benefit, and turn waste into treasure. If carbide slag can be applied to desulfurization facilities, replacing desulfurization limestone will achieve better environmental and economic benefits.

[0004] In the prior art, a method for preparing solid desulfurizer using carbide slag slurry is used to produce a desulfurizer with high activity, strong desulfurization and fine particle size through purification, separation, tempering, drying, grinding, air separation, packaging and other treatments. In addition, the reaction residue of carbide and water is firstly subjected to natural sedimentation to remove solid impurities such as ferrosilicon and pig iron to obtain an emulsion; then the obtained emulsion is deslaged and impurized to remove various solid impurities above 100 mesh; the obtained emulsion is subjected to solid-liquid separation to obtain solids and clean water; the obtained solids are purged with air to obtain calcium hydroxide crystals. The above-mentioned prior art is aimed at desulfurizer production enterprises, and the quality of the absorbent will be reduced during the drying process of carbide slag, and the drying system has high energy consumption, complex system and poor economy. There is a lack of systems and processes for on-site recycling and treatment of carbide slag in existing industrial production. Summary of the invention

[0005] The purpose of the present invention is to realize a system and process for on-site recycling and treatment of carbide slag, and propose a process for preparing desulfurization slurry using carbide slag.

[0006] A process for preparing desulfurization slurry using carbide slag, characterized by comprising:

[0007] (1) The feeder delivers the wet carbide slag containing water to the slag flushing tank; the carbide slag raw materials are mixed with water and flow into the pulping tank through the slag flushing tank;

[0008] (2) The carbide slag in the pulping tank dissolves rapidly, and the slurry is circulated back to the pulping tank by the slurry pump for full dissolution;

[0009] (3) When the slurry concentration condition is reached, it can be transported to the transfer tank;

[0010] (4) Air is introduced into the transfer tank for oxidation under the action of a stirrer;

[0011] (5) The qualified slurry after oxidation is transported into the finished slurry tank through a transfer pump.

[0012] The beneficial effects of the present invention are:

[0013] Compared with the existing technology, the invention realizes the on-site application of carbide slag waste in the desulfurization system, reduces the use of limestone, saves resources, reduces waste emissions, protects the environment, saves power generation costs and improves economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the system process diagram.

[0015] In the figure: 1 feeder, 2 slag flushing trough, 21 fan-shaped nozzle, 22 water inlet, 3 pulping tank, 31 agitator, 32 pulping tank controller, 4 pulping pump, 41 high-level outlet, 42 low-level outlet, 43 slag discharge pipe, 44 water inlet pipeline, 5 rotary vibrating screen, 6 discharge trough, 7 transfer tank, 71 agitator, 72 transfer tank controller, 8 discharge trough, 9 transfer tank pump, 91 discharge pipe, 92 water inlet pipeline, 10 finished slurry tank, 101 agitator. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, a system for preparing desulfurization slurry using carbide slag, the desulfurization agent preparation system includes filtrate supply, batching device, carbide slag slurrying, finished product slurry storage and transportation, and carbide slag drainage pit.

[0018] Its main function is to prepare qualified carbide slag slurry, dilute the wet carbide slag with a water content of 25% into a slurry of a certain concentration in the pulping tank, and perform pretreatment to remove some impurities, and then store it in the finished slurry tank (accident slurry tank) and transport it to the on-site desulfurization system for use.

[0019] The main equipment includes: a pulping tank, two pulping pumps (one in use and one in reserve), one rotary vibrating screen, a transfer tank, two transfer tank pumps (one in use and one in reserve), a finished product slurry tank and three finished carbide slag slurry pumps (two in use and one in reserve).

[0020] Desulfurization agent preparation system includes

[0021] The utility model comprises a feeder 1, a slag flushing trough 2 located below the feeder 1, a filter fence is arranged on the top of the slag flushing trough 2, and the incoming calcium carbide slag is piled on the filter fence.

[0022] The bottom of the slag flushing trough 2 is set to a slope of 10 degrees, and a filter fence is also provided at the outlet.

[0023] A pulping tank 3 is provided below the slag flushing trough 2 , and two top agitators 31 (one for use and one for standby) are provided in the pulping tank 3 . The bottom slurry outlet of the pulping tank 3 is connected to the inlet of a pulping pump 4 .

[0024] Each pulping pump 4 is connected to the bottom slurry outlet in two ways, namely a high-position outlet 41 and a low-position outlet 42 .

[0025] The high-level outlet is used to output the slurry with less impurities in the middle and upper parts of the pulping tank 3, which can be circulated and transported back to the pulping tank 3 through the pulping pump 4, or transported to the transfer tank 7. The high-level outlet is provided with a high-level filter screen to filter out impurities;

[0026] The low-position outlet 42 is used to discharge the impurity slurry in the lower part of the pulping tank 3, and the impurity slurry flows into the discharge tank 6 through the slag discharge pipe 43. The high-position outlet 41 and the low-position outlet 42 are switched by a control valve.

[0027] The outlet pipeline of the pulping pump 4 is connected back to the pulping tank 3, and the pulping pump 4 is used to repeatedly circulate the slurry in the pulping tank to fully dissolve it.

[0028] The outlet pipeline of the pulping pump 4 is also connected to the water inlet pipeline 44, which is connected to the desulfurization filtrate pipeline, and the desulfurization filtrate can be introduced into the pulping tank 3 to adjust the slurry concentration in the pulping tank 3. The available sources of the water inlet pipeline 44 are desulfurization process water and filtrate water.

[0029] The agitator 31, the control valves of the high-level outlet 41 and the low-level outlet 42, the pulping pump 4, and the control valve of the water inlet 44 are connected to the pulping tank controller 32. Under the control of the pulping tank controller 32, the slurry concentration in the pulping tank 3 is detected, and the slurry stirring, circulation, and slag discharge operations are performed.

[0030] The outlet of the pulping pump 4 is connected to the inlet of the rotary vibrating screen 5, which is located above the transfer tank 7. The rotary vibrating screen can be provided with multiple layers of screens as needed. The bottom flow outlet of the rotary vibrating screen 5 is connected to the transfer tank 7. A top agitator 71 is provided in the transfer tank 7. An oxidation pipe network is also introduced into the transfer tank 7, and the oxidation pipe network is connected to the air inlet pipeline.

[0031] The bottom outlet of the transfer tank 7 is connected to the inlet of the transfer tank pump 9, and the outlet of the transfer tank pump 9 is connected to the finished slurry tank 10. A top agitator 101 is arranged in the finished slurry tank 10.

[0032] Similarly, the outlet pipeline of the transfer tank 7 is also connected to the water inlet pipeline 92, which is connected to the desulfurization filtrate pipeline, and the desulfurization filtrate can be introduced into the finished slurry tank 10 to adjust the slurry concentration in the finished slurry tank 10. The available sources of the water inlet pipeline 92 are desulfurization process water and filtrate water.

[0033] The outlet pipeline of the transfer tank 7 also flows into the discharge tank 8 through the discharge pipe 91. The discharge pipe 91 can discharge excess slurry.

[0034] The agitator 71, the transfer tank pump 9, and the control valve of the water inlet 92 are connected to the transfer tank controller 72. Under the control of the transfer tank controller 72, the oxidation degree of the slurry in the transfer tank 7 is detected, and the slurry stirring and discharge operations are performed.

[0035] The slurry in the finished slurry tank 10 is further pumped to the on-site desulfurization system for use.

[0036] The process is as follows:

[0037] The feeder 1 delivers wet carbide slag with a moisture content of 25-38% to the slag flushing tank 2. The incoming carbide slag is piled on the filter fence at the top of the slag flushing tank 2. The carbide slag raw material is flushed into the carbide slag pulping tank through the desulfurization process water and the filtrate water by the fan-shaped nozzle 21. The mass ratio of the carbide slag raw material to water is 1:4. When the slurry flows into the pulping tank 3 through the slag flushing tank 2, large-sized materials will be doubly intercepted by the top filter fence and the bottom outlet filter fence of the slag flushing tank 2 to prevent them from entering the pulping tank 3.

[0038] In the pulping tank 3, carbide slag is rapidly dissolved under the action of the agitator, and the slurry is circulated and transported back by the pulping pump 4 for full dissolution. The desulfurization filtrate can be introduced into the pulping tank through the desulfurization filtrate pipeline to adjust the slurry concentration in the pulping tank. After a period of pulping time, insoluble waste residue will be deposited at the bottom of the pulping tank 3, which can be regularly discharged and introduced into the carbide slag discharge tank.

[0039] When the slurry concentration condition is reached, the transportation to the transfer tank 7 can be started.

[0040] The slurry in the pulping tank 3 is pumped into the rotary vibrating screen 5. The multi-layer screen of the rotary vibrating screen 5 is used to filter fine residues (using a double-layer screen of 100 mesh and 250 mesh). The bottom flow slurry enters the transfer tank 7. Air is introduced into the transfer tank 7 for oxidation under the action of the agitator. The gas flow rate is about 100m 3 / h, and the slurry residence time is about 1.8h.

[0041] The qualified slurry after oxidation is transported into the finished slurry tank 10 through the transfer pump. The desulfurization filtrate pipeline is connected to the transfer pump delivery pipeline to inject the desulfurization filtrate into the finished slurry tank 10 to adjust the slurry concentration in the finished slurry tank 10.

[0042] After treatment, the 250 mesh sieving rate of particles in the prepared slurry was 96%.

[0043] The desulfurizer preparation system in this application is a public system, which is shared by four boiler units, and its pulping capacity is 150% of the flue gas desulfurization amount of four absorption towers of four boilers. The system is also equipped with a batching device.

[0044] Since the system uses desulfurized filtrate as the main water source for pulping, all water tanks are treated with anti-corrosion to ensure the anti-corrosion performance of the equipment.

[0045] In this application, due to the high impurities in the incoming calcium carbide slag, the following measures are adopted for treatment:

[0046] 1. Add a filter fence on the top of the carbide slag slag trough for primary filtration;

[0047] 2. Add a filter fence at the bottom outlet of the slag trough for secondary filtration;

[0048] 3. Add a high-level filter at the high-level entrance of the pulping tank;

[0049] 4. Add a rotary vibrating screen on the top of the slurry transfer tank;

[0050] The above measures ensure that the slurry entering is free of impurities and does not damage the equipment and system.

[0051] Through research and improvement, the pulping system, storage system, and transportation system were rationally combined with the original pulp supply system. Through debugging and testing, the problem of on-site treatment and use of carbide slag instead of limestone was solved. Annual material cost savings: 10,000 tons × 90 yuan / ton = 900,000 yuan, achieving waste recycling, reducing environmental pollution, and having a great promotion effect. Reducing the use of limestone, saving resources, and at the same time reducing waste emissions, protecting the environment, saving power generation costs and improving economic benefits.

[0052] Finally, it should be noted that the above description is only an explanation of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail, those skilled in the art can still modify the technical solutions described above or replace some of the technical features with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for preparing desulfurization slurry using carbide slag, characterized in that: include: (1) The feeder delivers the wet carbide slag containing water to the slag flushing tank; the carbide slag raw materials are mixed with water and flow into the pulping tank through the slag flushing tank; (2) The carbide slag in the pulping tank dissolves rapidly, and the slurry is circulated back to the pulping tank by the pulping pump for full dissolution; (3) When the slurry concentration condition is reached, it can be transported to the transfer tank; (4) Air is introduced into the transfer tank for oxidation under the action of a stirrer; (5) The qualified slurry after oxidation is transported into the finished slurry tank through a transfer pump.

2. The process for preparing desulfurization slurry using carbide slag according to claim 1, characterized in that: The moisture content of the wet carbide slag in step (1) is 25-38%.

3. The process for preparing desulfurization slurry using carbide slag according to claim 2, characterized in that: The mass ratio of carbide slag raw material to water is 1:4-8.

4. The process for preparing desulfurization slurry using carbide slag according to claim 1, characterized in that: In step (1), the slag flushing trough has a filter fence, and large-sized materials will be intercepted by the filter fence of the slag flushing trough to prevent them from entering the pulping tank.

5. The process for preparing desulfurization slurry using carbide slag according to claim 1, characterized in that: In step (2), the outlet pipeline of the pulping pump is connected to a water inlet pipeline, so that the desulfurized filtrate can be introduced into the pulping tank to adjust the slurry concentration in the pulping tank.

6. The process for preparing desulfurization slurry using carbide slag according to claim 1, characterized in that: In step (3), the slurry in the pulping tank is firstly pumped into a rotary vibrating screen, and the rotary vibrating screen uses a multi-layer screen to filter the fine residue.

7. The process for preparing desulfurization slurry using carbide slag according to claim 6, characterized in that: In step (3), the rotary vibrating screen uses a double-layer screen of 100 mesh and 250 mesh.

8. The process for preparing desulfurization slurry using carbide slag according to claim 1, characterized in that: In step (4), air is introduced for oxidation, and the gas flow rate is about 100m 3 / h, and the slurry residence time is about 1.8h.

9. The process for preparing desulfurization slurry using carbide slag according to claim 1, characterized in that: In step (5), the outlet pipeline of the transfer pump is connected to the desulfurization filtrate pipeline, and the desulfurization filtrate can be introduced into the finished product slurry tank to adjust the slurry concentration in the finished product slurry tank.

10. The process for preparing desulfurization slurry using carbide slag according to claim 5 or 9, characterized in that: The sources of the water inlet pipeline are desulfurization process water on one side and filtrate water on the other side.

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