A method for regenerating waste dechlorination agent

Abstract

The present invention provides a method for regenerating waste dechlorination agent. The waste dechlorination agent is classified according to the chlorine content, and waste dechlorination agents with different chlorine contents are washed by multi-stage water mist spraying, and the washing water is utilized in a cascade manner; then it is dried, sprayed with alkali solution and baked. This method for regenerating waste dechlorination agent has the advantages of less water consumption, simple process and environmental friendliness.

Description

Technical Field

[0001] The present invention relates to a regeneration method for waste dechlorinating agent, specifically, a method for classifying and treating regeneration according to different chlorine contents of the dechlorinating agent. Background Art

[0002] Great progress has been made in the research and industrial application of dechlorinating agents in China. A series of dechlorinating agent products with different performances have been developed and applied to remove chlorine from naphtha, light liquid hydrocarbons, and liquefied petroleum gas. The saturated dechlorinating agent is waste dechlorinating agent. According to the classification of industrial waste, waste dechlorinating agent belongs to hazardous waste. The treatment of waste dechlorinating agent usually adopts the landfill method, with high treatment costs and easy to pollute the underground water body if disposed improperly. Therefore, the reduction and reuse of waste dechlorinating agent become the preferred choice in the disposal method of waste dechlorinating agent.

[0003] Patent CN109453754A discloses a regeneration method for waste dechlorinating agent, including soaking with water first, then drying, then spraying with an aqueous solution containing an alkali metal compound, and then roasting to obtain a regenerated dechlorinating agent. The above patent realizes the reduction and reuse of waste dechlorinating agent, but the process is complex and a large amount of wastewater will be generated.

[0004] To solve the above problems, we have been seeking an ideal technical solution. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art, and thus provide a regeneration method for waste dechlorinating agent with less water consumption, simple process and environmental protection.

[0006] A regeneration method for waste dechlorinating agent includes: Step 1, sampling and detecting the chlorine content of the waste dechlorinating agent and then classifying it. The waste dechlorinating agent with a chlorine content less than 2wt% is refilled into the dechlorination tank for use; for the waste dechlorinating agent with a chlorine content of 2 - 5wt%, 2-stage water spray washing is adopted, and the washing water is utilized in a cascade manner; for the waste dechlorinating agent with a chlorine content greater than 5wt%, 3 - 7-stage water spray washing is adopted, and the washing water is utilized in a cascade manner; Step 2, drying, and the drying temperature is 100°C - 120°C; Step 3, spraying an alkali solution, and the concentration of the sprayed alkali solution is 20 - 30wt%. If the concentration of the alkali solution is too high, it will cause the dechlorinating agent to agglomerate; if the concentration is too low, the chlorine capacity cannot meet the standard after spraying. The alkali solution can adopt an aqueous solution of an alkali metal hydroxide or salt; Step 4, baking.

[0007] During the use of the dechlorination agent, a fixed-bed method is generally adopted. Generally speaking, when the dechlorination agent bed is penetrated, as the height of the dechlorination agent bed increases, the chlorine content in the dechlorination agent is higher. At the top of the bed, the chlorine content is the highest; while the chlorine content of the dechlorination agent at the lower part of the bed is the lowest. The dechlorination agent bed can be divided into three regions from top to bottom: a saturated region, a mass transfer region, and a blank region. The chlorine content in the blank region is less than 2 wt%, the chlorine content in the mass transfer region is 2 - 5 wt%, and the chlorine content in the saturated region is greater than 5 wt% and less than 20 wt%. Therefore, the dechlorination agent can be classified according to different chlorine contents, and different disposal schemes can be adopted to achieve the reduction and reuse of waste dechlorination. And for sampling and detection, it is not necessary to crush the waste dechlorination agent, and its skeleton structure is maintained to achieve the purpose of cost saving and recycling. When the washing water is used in a cascading manner, the spray water discharged from the next stage is used as the spray water for the previous stage after filtration. The higher the chlorine content of the waste dechlorination agent, the more stages of spray water washing are required.

[0008] As a further improvement of the technical solution, the alkali solution is an aqueous solution of any one or a combination of KOH, K2CO3, NaOH, and Na2CO3.

[0009] As a further improvement of the technical solution, for the waste dechlorination agent with a chlorine content greater than 5 wt% and less than 20 wt%, the chlorine capacity can meet the use requirements after 3 - 4 stages of spray water washing, saving the use of washing water and washing time.

[0010] As a further improvement of the technical solution, the total amount of washing water in step one is 0.5 - 1 times the mass of the dechlorination agent.

[0011] As a further improvement of the technical solution, the temperature of the washing water in step one is at room temperature, which is convenient for cost saving.

[0012] As a further improvement of the technical solution, the roasting temperature is 400°C - 600°C.

[0013] The present invention has beneficial effects compared with the existing waste dechlorination agent regeneration technology: By classifying the waste dechlorination agent, corresponding treatment schemes are adopted for different dechlorination agents. At the same time, the multi-stage spray water washing and cascading use of water reduce the water consumption in the process. The process is simple and environmentally friendly. Specific Embodiments

[0014] The following will further describe the technical solutions of the present invention in detail through specific embodiments.

[0015] In each embodiment, the spent dechlorination agent is from the spent dechlorination agent in the process of reforming product oil dechlorination. 1000 g of the spent dechlorination agent was analyzed. Among them, 124 g of the spent dechlorination agent with a chlorine content of less than 2 wt% can be directly reused. 322 g of the spent dechlorination agent with a chlorine content of 2 - 5 wt% is the spent dechlorination agent A, and 554 g of the spent dechlorination agent with a chlorine content greater than 5 wt% and less than or equal to 18 wt% is the spent dechlorination agent B. Method for measuring chlorine capacity: First, saturate the dechlorination agent with chlorine, then crush and dry the dechlorination agent, weigh it, soak it in water, and measure the chlorine content in the water.

[0016] Example 1

[0017] The spent dechlorination agent A was washed by 2 - stage water mist spraying and washing. The sprayed water was filtered and used in a cascade manner. The amount of sprayed water was 322 g;

[0018] The spent dechlorination agent B was washed by 4 - stage water mist spraying and washing. The sprayed water was filtered and used in a cascade manner. The amount of sprayed water was 554 g;

[0019] The washed spent dechlorination agents A and B were jointly sent into a dryer and dried at 110 °C for 2 h. A 30 wt% aqueous solution of Na2CO3 was prepared and sprayed on the dried dechlorination agent, then dried at 110 °C for 2 h, and then calcined at 500 °C for 4 h to obtain a regenerated dechlorination agent with a chlorine capacity of 40% and can be reused.

[0020] Example 2

[0021] The spent dechlorination agent A was washed by 2 - stage water mist spraying and washing. The sprayed water was filtered and used in a cascade manner. The amount of sprayed water was 161 g;

[0022] The spent dechlorination agent B was washed by 4 - stage water mist spraying and washing. The sprayed water was filtered and used in a cascade manner. The amount of sprayed water was 277 g;

[0023] The washed spent dechlorination agents A and B were jointly sent into a dryer and dried at 120 °C for 2 h. A 20 wt% aqueous solution of K2CO3 was prepared and sprayed on the dried dechlorination agent, then dried at 120 °C for 2 h, and then calcined at 600 °C for 4 h to obtain a regenerated dechlorination agent with a chlorine capacity of 30% and can be reused.

[0024] Example 3

[0025] The spent dechlorination agent A was washed by 2 - stage water mist spraying and washing. The sprayed water was filtered and used in a cascade manner. The amount of sprayed water was 260 g;

[0026] The spent dechlorination agent B was washed by 3 - stage water mist spraying and washing. The sprayed water was filtered and used in a cascade manner. The amount of sprayed water was 554 g;

[0027] The washed waste dechlorinating agents A and B are jointly sent into a dryer and dried at 100 °C for 2 h. A 20 wt% KOH aqueous solution is prepared, sprayed on the dried dechlorinating agent, then dried at 100 °C for 2 h, and then calcined at 400 °C for 4 h to obtain a regenerated dechlorinating agent with a chlorine capacity of 33%, which can be reused.

[0028] Example 4

[0029] The waste dechlorinating agent A is subjected to two-stage water spray washing, and the sprayed water is filtered and used in a cascade manner. The water spray volume is 280 g;

[0030] The waste dechlorinating agent B is subjected to four-stage water spray washing, and the sprayed water is filtered and used in a cascade manner. The water spray volume is 480 g;

[0031] The washed waste dechlorinating agents A and B are jointly sent into a dryer and dried at 120 °C for 2 h. A 30 wt% NaOH aqueous solution is prepared, sprayed on the dried dechlorinating agent, then dried at 120 °C for 2 h, and then calcined at 600 °C for 4 h to obtain a regenerated dechlorinating agent with a chlorine capacity of 38%, which can be reused.

[0032] Example 5

[0033] The waste dechlorinating agent A is subjected to two-stage water spray washing, and the sprayed water is filtered and used in a cascade manner. The water spray volume is 322 g;

[0034] The waste dechlorinating agent B is subjected to four-stage water spray washing, and the sprayed water is filtered and used in a cascade manner. The water spray volume is 554 g;

[0035] The washed waste dechlorinating agents A and B are jointly sent into a dryer and dried at 110 °C for 2 h. A mixed aqueous solution containing 15 wt% Na2CO3 and 15 wt% KOH is prepared, sprayed on the dried dechlorinating agent, then dried at 110 °C for 2 h, and then calcined at 500 °C for 4 h to obtain a regenerated dechlorinating agent with a chlorine capacity of 36%, which can be reused.

[0036] Example 6

[0037] The waste dechlorinating agent A is subjected to two-stage water spray washing, and the sprayed water is filtered and used in a cascade manner. The water spray volume is 322 g;

[0038] The waste dechlorinating agent B is subjected to four-stage water spray washing, and the sprayed water is filtered and used in a cascade manner. The water spray volume is 554 g;

[0039] The washed waste dechlorinating agents A and B are jointly sent into a dryer and dried at 110°C for 2 h. An aqueous solution containing 15 wt% of Na2CO3 and 15 wt% of NaOH is prepared, dried at 110°C for 2 h, and then calcined at 500°C for 4 h to obtain a regenerated dechlorinating agent with a chlorine capacity of 35% and can be reused.

[0040] Comparative Example 1

[0041] The waste dechlorinating agent A is subjected to two-stage ordinary spray water washing, and the sprayed water is filtered and used in a cascade manner, with the spray water volume being 322 g;

[0042] The waste dechlorinating agent B is subjected to four-stage ordinary spray water washing, and the sprayed water is filtered and used in a cascade manner, with the spray water volume being 554 g;

[0043] The washed waste dechlorinating agents A and B are jointly sent into a dryer and dried at 110°C for 2 h. An aqueous solution of 30 wt% Na2CO3 is prepared and sprayed on the dried dechlorinating agent, then dried at 110°C for 2 h, and then calcined at 500°C for 4 h to obtain a regenerated dechlorinating agent with a chlorine capacity of 18% and cannot be reused.

[0044] Comparative Example 2

[0045] The waste dechlorinating agent A is subjected to two-stage water mist spray water washing, with the spray water volume being 322 g;

[0046] The waste dechlorinating agent B is subjected to four-stage water mist spray water washing, with the spray water volume being 554 g;

[0047] The washed waste dechlorinating agents A and B are jointly sent into a dryer and dried at 110°C for 2 h. An aqueous solution of 30 wt% Na2CO3 is prepared and sprayed on the dried dechlorinating agent, then dried at 110°C for 2 h, and then calcined at 500°C for 4 h to obtain a regenerated dechlorinating agent with a chlorine capacity of 15% and cannot be reused.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific implementation manners of the present invention or make equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A method for regenerating waste dechlorination agent, characterized in that, It includes Step 1: Sampling and testing the waste dechlorination agent, classifying it according to the chlorine content. The waste dechlorination agent with a chlorine content less than 2 wt% is reloaded into the dechlorination tank for use; for the waste dechlorination agent with a chlorine content of 2 - 5 wt%, 2-stage water spray washing is adopted, and the washing water is utilized in a cascading manner; for the waste dechlorination agent with a chlorine content greater than 5 wt% and less than 20 wt%, 3 - 7-stage water spray washing is adopted, and the washing water is utilized in a cascading manner. Step 2: Drying, with the drying temperature being 100°C - 120°C. Step 3: Spraying an alkali solution, with the concentration of the sprayed alkali solution being 20 - 30 wt%. Step 4: Roasting.

2. The method for regenerating waste dechlorination agent according to claim 1, characterized in that, The alkali solution is an aqueous solution of any one or a combination of KOH, K2CO3, NaOH, and Na2CO3.

3. The method for regenerating the spent dechlorination agent according to claim 1, wherein In Step 1, the total amount of the washing water is 0.5 - 1 times the total mass of the dechlorination agent to be washed.

4. The method for regenerating waste dechlorination agent according to claim 1, characterized in that, In Step 1, the temperature of the washing water is normal temperature.

5. The method for regenerating the spent dechlorination agent according to claim 1, wherein The roasting temperature is 400°C - 600°C.

6. The method for regenerating the spent dechlorination agent according to claim 1, wherein For the waste dechlorination agent with a chlorine content greater than 5 wt% and less than 20 wt%, 3 - 4-stage water spray washing is adopted.