Method for dechlorinating flue gas desulfurization circulating liquid by ammonia method

A technology for circulating liquid and flue gas, applied in the field of chlorine separation, can solve problems such as the inability to separate sulfate radicals and chloride ions, the lack of instructions on how to dispose of ammonia nitrogen, and the lack of instructions on how to dispose of sodium chloride.

Active Publication Date: 2021-04-20
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Adopt the method of above-mentioned patent can not realize the separation of sulfate radical and chloride ion
The above-mentioned patent converts the low-concentration ammonia in the ammonia-nitrogen wastewater into ammonium chloride, but there is no explanation on how to dispose of the sodium chloride contained in the remaining raffinate, and there is no explanation on how to dispose of the remaining 10 mg / L of ammonia nitrogen in the raffinate

Method used

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  • Method for dechlorinating flue gas desulfurization circulating liquid by ammonia method

Examples

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Embodiment 1

[0061] Coal-fired power plant ammonia flue gas desulfurization circulation tower, circulating water volume 30m 3 / h, containing 250,000 mg / L of sulfate, 124,500 mg / L of chloride ion, 1,000 mg / L of suspended matter, and pH 9.5. Use a corrosion-resistant pump to pump out the circulating fluid from the circulation tower at a flow rate of 250L / h, continuously pump it for 2 hours, and pump it directly into the silo of the plate and frame filter press, pressurize to 1.0MPa, and the suspended matter becomes mud cake. The desalinated water is used to repeatedly wash the mud cake, and the desalted water consumed by washing is 15 times that of the filtrate, and the inorganic salt in the mud cake is washed until it meets the requirements of landfill. Then continue to pressurize to 1.6MPa, press the mud cake to a water content of 60%, unload the mud cake from the plate and frame filter press, and send it to the fly ash processing unit for disposal. Repeat the plate and frame filter press...

Embodiment 2

[0068] Coal-fired power plant ammonia flue gas desulfurization circulation tower, circulating water volume 50m 3 / h, containing ammonium sulfate 180000mg / L, ammonium chloride 101000mg / L, suspended matter 1500mg / L, pH value 9.0. Use a corrosion-resistant pump to extract the circulating fluid from the circulation tower at a flow rate of 450L / h, continuously pump it for 2 hours, and pump it directly into the silo of the plate-and-frame filter press, pressurize to 1.1MPa, and the suspended matter becomes mud cake. The desalinated water is used to repeatedly wash the mud cake, and the desalted water consumed by washing is 10 times that of the filtrate, and the inorganic salt in the mud cake is washed until it meets the requirements of landfill. Then continue to pressurize to 1.7MPa, press the mud cake to a water content of 60%, unload the mud cake from the plate and frame filter press, and send it to the fly ash processing unit for disposal. Repeat the plate and frame filter press...

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Abstract

The invention belongs to the technical field of chlorine separation, and particularly relates to a method for dechlorinating flue gas desulfurization circulating liquid by an ammonia method. The method comprises steps: subjecting ammonia-process flue gas desulfurization circulating liquid to filter pressing separation by a plate-and-frame filter press, filtration by a sand filter, filtration by a nanofiltration membrane and alkalifying of nanofiltration liquid to completely convert ammonium ions into free ammonia, pumping the nanofiltration liquid into a tube pass of a hollow fiber gasification membrane, and enabling ammonia gas to reach the outer side through membrane holes and immediately being reacted with dilute sulfuric acid to generate ammonium sulfate; adding hydrochloric acid into the nanofiltration liquid after ammonia molecules are removed to adjust the pH value to be neutral, adding an oxidizing agent to oxidize residual ammonia into nitrogen, preparing saturated edible salt water by using the nanofiltration liquid after ammonia removal as salt dissolving water, filtering the saturated edible salt water by adopting a nanofiltration method, feeding the nanofiltration liquid into an ionic membrane electrolysis device to produce chlorine and liquid caustic soda, and freezing and cooling nanofiltration concentrated water, separating sodium sulfate out of water in the form of mirabilite, so that sulfate radicals are removed. According to the method, chloride ions in the circulating liquid can be effectively removed, and meanwhile resource utilization of the chloride ions, sulfate ions and sodium ions is achieved.

Description

technical field [0001] The invention belongs to the technical field of chlorine separation, and in particular relates to a method for dechlorinating circulating liquid of ammonia-based flue gas desulfurization. Background technique [0002] Ammonia-based flue gas desulfurization circulating fluid refers to the circulating fluid containing ammonium sulfate produced by coal-fired power plants using ammonia water as a circulating spray washing liquid to wash the sulfur dioxide-containing flue gas produced by coal combustion. Coal contains carbon, sulfur, chlorine, nitrogen and other elements. When burning, sulfur becomes sulfur dioxide, chlorine becomes hydrochloric acid, nitrogen becomes nitrogen and NOx, and carbon becomes carbon dioxide. Since NOx and carbon dioxide are weakly acidic gases, they do not react with amino at all, while sulfur dioxide and hydrochloric acid are strong acid gases, which preferentially react with ammonia. Therefore, ammonium sulfite and ammonium ch...

Claims

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Application Information

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IPC IPC(8): C02F9/00C01D5/16C01D5/00C01C1/242B01D53/96B01D53/78B01D53/68B01D53/50C25B1/46
CPCY02A20/131
Inventor 潘咸峰郭岩峰孟宪谭袁辉志梁明张广
Owner CHINA PETROLEUM & CHEM CORP
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