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A system for preparing magnesium sulfate from slurry after flue gas desulfurization

A technology of magnesium sulfate and flue gas, which is applied in the direction of magnesium sulfate, dispersed particle separation, chemical instruments and methods, etc., can solve the problems of increasing system energy consumption, increasing floor area, and decreasing purity, so as to reduce system energy consumption, Improve efficiency and save space

Active Publication Date: 2015-09-02
ZHONGJING ENVIRONMENTAL TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In such a low oxygen content environment, the slurry mainly contains MgSO 3 Exist in form, in order to produce by-product magnesium sulfate heptahydrate, it is necessary to set up an oxidation fan with a large flow rate and an oxidation pool with a residence time of more than 10 hours, which increases the floor space and increases the energy consumption of the system, thus causing the use of magnesium oxide The production of magnesium sulfate heptahydrate from waste liquid produced by desulfurization requires high economic cost
Patent CN102631836A "New process for recovering magnesium sulfate heptahydrate from flue gas desulfurization of magnesium oxide", in the case of no oxygen balance and adjustment device at the front end, the converted MgSO 4 The amount is small, the conversion efficiency is about 40%, and the efficiency is too low to affect its economy
Patents CN102755828 and CN102745725 add oxidants (such as other metal oxides MnO 2 , KMnO 4 etc.) tetravalent sulfur is oxidized to hexavalent sulfur to improve the output of magnesium sulfate, but due to the presence of other metal oxides, some other metal sulfates are mixed in the final product magnesium sulfate, resulting in a decrease in its purity and performance.

Method used

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  • A system for preparing magnesium sulfate from slurry after flue gas desulfurization
  • A system for preparing magnesium sulfate from slurry after flue gas desulfurization

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preparation example Construction

[0032] Attached below figure 1 The system for preparing magnesium sulfate of the present invention is introduced in detail.

[0033] The system for preparing magnesium sulfate of the present invention includes a device for adjusting the oxygen content of flue gas, preferably a supplementary oxidizing air device. The system of the present invention may also include a pulping device, a desulfurization device, a filtration device, an evaporation device, a cooling crystallization device, and a separation device. The system of the present invention may also include drying means and packaging means.

[0034] The system of the present invention includes a desulfurization device, the desulfurization device is provided with a pre-desulfurization flue, and the flue gas oxygen content adjustment device is arranged on the pre-desulfurization flue, and the flue gas oxygen content adjustment device is used to control the desulfurization. Oxygen content in flue gas, and keep the oxygen con...

Embodiment 1

[0057] Step 1: Add magnesium oxide powder to high-temperature condensed water from an evaporator at 60°C to make a magnesium hydroxide slurry, and pump it to the absorption tower.

[0058] Step 2: Control the oxygen content of the flue gas before desulfurization in Table 1 to 18% by using the flue gas oxygen content regulating device.

[0059] Step 3: The flue gas velocity at the entrance of the absorption tower is 3m / s, and the flue gas temperature at the entrance is 120°C. The pH value of the slurry tank area at the bottom of the absorption tower is controlled to fluctuate between 6 and 7 to obtain a magnesium sulfate solution.

[0060] Step 4: pass the magnesium sulfate solution through a precision filter of no less than 300 mesh filter media to achieve fine filtration of the magnesium sulfate solution.

[0061] Step 5: Set the temperature at 30°C and the density at 1.2t / m 3 The magnesium sulfate solution is sent to the three-effect evaporator for evaporation to obtain a te...

Embodiment 2

[0073] Under the same working conditions as in Example 1, step 2: utilize the flue gas oxygen content regulating device to control the flue gas oxygen content before desulfurization respectively at 23%, the desulfurization effect obtained and the magnesium sulfate output are as follows:

[0074] Table 4 Emissions and magnesium sulfate output of desulfurization projects with 23% oxygen content

[0075] serial number

project

quantity

unit

1

Flue gas volume at the outlet of the desulfurization unit (working condition)

1384210

m 3 / h

2

exhaust temperature

50

℃

3

SO 2 emission concentration

＜40

mg / Nm 3

4

Magnesium sulfate output

4.5

t / h

5

Magnesium Sulfate Quality

＞98

% mass percentage

[0076] Magnesium sulfate quality and its test method are the same as in Table 3.

[0077] It can be seen from Examples 1 to 2 that the present invention utilizes the m...

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Abstract

The invention discloses a system for preparing magnesium sulfate. The system utilizes a magnesium hydroxide slurry to desulphurize flue gas in order to form a crystalline magnesium sulfate product. The system comprises a desulphurization device, the desulphurization device is provided with a flue before desulphurization, the flue before desulphurization is provided with a flue gas oxygen content adjustment device, and the flue gas oxygen content adjustment device is used for controlling the oxygen content of the flue gas before desulphurization and maintaining the oxygen content stable. By using the system, the MgSO3-to-MgSO4 conversion rate is improved, the high-quality magnesium sulfate product is prepared, the concentration of SO2 in the flue gas is reduced, the pollution to the environment is reduced, a place for building a new oxidation pool is saved, and the system energy consumption of an oxidation fan is reduced.

Description

technical field [0001] The invention relates to a system for preparing magnesium sulfate, in particular to a system for preparing magnesium sulfate by utilizing slurry after flue gas desulfurization. Background technique [0002] The desulfurization process based on the traditional limestone gypsum method has been widely used in the desulfurization industry. Desulfurization gypsum, a by-product of desulfurization projects, is difficult to reuse and forms solid waste, causing secondary pollution to the environment. In 2012, thermal power plants affiliated to China's five major power companies produced 60 million tons of desulfurized gypsum. How to deal with these solid wastes has become a headache for various enterprises, governments at all levels, and environmental protection agencies. The reality that China is short of sulfur but not short of gypsum (gypsum) has made most environmental protection practitioners start to think about how to develop new desulfurization technolo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D53/80B01D53/50C01F5/40
Inventor 王键刘景明童裳慧
Owner ZHONGJING ENVIRONMENTAL TECH CO LTD