System and method for recycling Fischer-Tropsch synthetic wastewater in indirect coal liquefaction production

Abstract

The invention discloses a system and method of recycling Fischer-Tropsch (F-T) synthesis waste water in indirect coal liquefaction production. The system comprises an ammonia-containing waste water storage device, an ammonia-containing waste water pump, a slurrying water tank, a slurrying water pump, a coal water slurry preparation device and an F-T synthesis device. The method comprises the steps: (1) neutralizing the ammonia-containing waste water and Fischer-Tropsch synthesis waste water to prepare slurrying water; and (2) returning the slurrying water to the coal water slurry preparation device for recycling. The system and the method have the advantages of being capable of greatly saving the chemical cost per year, greatly lightening the load for disposing sewage, solving the bottleneck problem on restraining the standard emission of chemical industry, and enabling the quality of the coal slurry not to frequently fluctuate due to the PH value of the slurrying water; proved by operation tests, the slurrying waste water obtained by neutralizing the ammonia-containing waste water and Fischer-Tropsch synthesis waste water has no any corrosion on flow passage components of the pump and the pipelines.

Description

Technical field: [0001] The invention relates to a Fischer-Tropsch synthesis wastewater recycling system and method, in particular to a Fischer-Tropsch synthesis wastewater recycling system and method in indirect coal liquefaction production. Background technique: [0002] During the indirect coal liquefaction process, the Fischer-Tropsch synthesis reaction will produce a certain amount of synthetic wastewater, which is rich in oxygen-containing organic compounds such as alcohols, aldehydes, acids, ketones, and esters. Fischer-Tropsch synthetic wastewater is acidic, with a pH value of about 3-4 and a COD value of 30,000-100,000 mg / l. Fischer-Tropsch synthetic wastewater is difficult to be effectively treated by ordinary wastewater biochemical processes. In the existing domestic process, the Fischer-Tropsch synthesis wastewater is sent to the coal slurry preparation unit of the gasification device, and used as slurry water and raw coal to make coal water slurry in the coal m...

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Problems solved by technology

And adopt NaOH to have following shortcoming as pH value adjusting agent: (1) estimate according to the pH value estimation of device design load and Fischer-Tropsch synthetic waste water, need to consume about 3T of NaOH every day, cost is higher; (2) when NaOH aqueous solution is configured in daily production It requires a lot of manpower and a large workload, and the flaky NaOH and the prepared lye are highly corrosive, and there are high safety risks and high safety costs during the preparation; (3) NaOH solution is prone to crystallization during the metering and transportation process Blockage of pipelines, metering pumps not measuring or flow fluctuations occur from time to time, resulting in fluctuations in the pH value of the pulping water, affecting the stability and fluidity of the coal slurry; at the same time, it also caused strong corrosion to the pumps and pipelines. During the process, it was found that the impeller of the pulping water pump was corroded by synthetic wastewater to a thickness of several millimeters

[0004] Ammonia-containing wastewater is relatively common in the domestic chemical industry and other industries, and its treatment methods are mostly steam stripping, biochemical, etc. The purpose of its treatment is often to remove the ammonia nitrogen in the wastewater and discharge it up to the standard. The ammonia-containing wastewater has not been obtained. Effective utilization, and the treatment cost of ammonia-containing wastewater is relatively high

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