Synthesis ammonia alcohol-containing waste liquid recycling method

Abstract

The invention discloses a method for recycling synthetic ammonia alcohol-containing waste liquid. The method comprises the following steps: 1, discharging synthetic ammonia containing alcohol waste liquid into a methanol synthesis flash tank through a DN25 pipeline; 2, enabling the waste liquid to pass through a methanol separator, sequentially carrying out mechanical separation, namely cyclone separation and wire mesh defoaming on the waste liquid, then absorbing the waste liquid through a water washing tower plate, and carrying out membrane separation, so as to achieve the purpose of separating methanol; step 3, after being treated by the methanol separator, the methanol is conveyed to a crude methanol discharge tank to be treated again; 4, conveying the obtained gas-phase product into a flash steam methanol recovery tower for treatment; and step 5, finally, washing through a desalted water device, reducing the content of methanol in the flash steam, and recovering methanol. According to the invention, closed recycling treatment is adopted, and non-condensable gas in the methanol is further recovered by utilizing the flash tank, so that environmental pollution is avoided, open-type methanol recovery is avoided, the safety is greatly improved, and the yield of methanol recovery is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment technology, and in particular relates to a method for recycling synthetic ammonia alcohol-containing waste liquid. Background Art

[0002] Methanol is an organic chemical product that can be produced by hydrogenation of carbon monoxide alone or in combination with synthetic ammonia. The process of producing methanol in combination with synthetic ammonia is called alcohol combination. Alcohol combination can reduce the energy and material consumption of conversion and refining processes, and reduce costs. The technology of synthetic ammonia alcohol combination has been widely adopted. A large amount of wastewater containing ammonia ions is discharged during the production of synthetic ammonia alcohol combination, in which the COD content is high. If it is discharged directly, it will cause pollution to the environment, so the wastewater needs to be treated.

[0003] In order to avoid environmental pollution, some methods are often used to recycle the methanol before discharge. Since this part of the waste liquid contains 70% to 80% alcohol and is doped with non-condensable gases such as CO, CO2, and CH4, there are serious safety hazards in open recovery and treatment. In addition, biochemical microorganisms are sensitive to alcohol content, and higher COD will affect the living environment of microorganisms. If the COD of the biochemical regulating tank is higher than 3000, it will be extremely difficult to treat.

[0004] Therefore, in order not to affect the biochemical water pool, not to pollute the growth of biochemical microorganisms, and to eliminate safety hazards during the discharge process, the waste liquid discharge is changed from open recovery to closed reuse. The original discharge to the biochemical wastewater well is changed to the methanol synthesis flash tank for closed reuse, and the methanol production is increased. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a method for recycling the alcohol-containing waste liquid of synthetic ammonia, eliminate the potential safety hazards in the discharge process, change the waste liquid discharge from open recovery to closed reuse, change the original discharge to the biochemical wastewater well to the methanol synthesis flash tank for closed reuse, and increase the methanol production.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for recycling synthetic ammonia alcohol-containing waste liquid, comprising the following steps:

[0008] Step 1: Discharge the synthetic ammonia containing alcohol waste liquid into the interior of the methanol synthesis flash tank through a DN25 pipeline;

[0009] Step 2: The waste liquid first passes through a methanol separator, and then undergoes mechanical separation, i.e., cyclone separation, screen defoaming, and then absorption by a water washing plate, and then membrane separation, to achieve the purpose of separating methanol;

[0010] Step 3: After being processed in a methanol separator, it is transported to a crude methanol discharge tank for further processing;

[0011] Step 4: transporting the obtained gas phase product to the interior of the flash steam methanol recovery tower for treatment;

[0012] Step 5: Finally, the flash steam is washed with desalted water to reduce the methanol content and recover the methanol.

[0013] Furthermore, in the step 2, the separation principle is: methanol is separated into vapor and liquid at 38-82°C, and then the circulating gas enters the circulation system again, and the separated methanol enters the distillation system after flash evaporation.

[0014] Furthermore, in the step three, the mixture after being treated by the methanol separator passes through a crude methanol discharge tank, and the primary stream in the mixed liquid passes through the methanol discharge tank for effective filtration.

[0015] Furthermore, the separation principle in step 2 is that methanol undergoes vapor-liquid separation at 40°C.

[0016] Furthermore, the method eliminates open recovery of methanol, greatly improves safety, and effectively increases the output of methanol recovery.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are:

[0018] The method of the present invention adopts closed recycling treatment, uses a flash tank to further recover non-condensable gas therein, avoids environmental pollution, eliminates open-type methanol recovery, greatly improves safety, and effectively increases the output of methanol recovery.

[0019] Under the maximum separation rate under full-load conditions of hydrogen production, about 2 tons of alcohol liquid is separated per day, with an alcohol content of about 80%. The daily production benefit of the alcohol liquid recovered is 3,200 yuan. The annual benefit of the device is 2*80%*2000*365=1.168 million yuan (calculated based on 8,000 hours of online operation time). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings.

[0021] Figure 1 The present invention is a schematic diagram of a method for recycling alcohol-containing waste liquid from synthetic ammonia. DETAILED DESCRIPTION

[0022] See also Figure 1 The present invention provides a method for recycling alcohol-containing waste liquid from synthetic ammonia, which specifically comprises the following steps:

[0023] A method for recycling synthetic ammonia alcohol-containing waste liquid, the specific steps of the method for recycling synthetic ammonia alcohol-containing waste liquid are as follows:

[0024] Step 1: Discharge the synthetic ammonia containing alcohol waste liquid into the interior of the methanol synthesis flash tank through a DN25 pipeline;

[0025] Step 2: The waste liquid first passes through a methanol separator, and then undergoes mechanical separation, i.e., cyclone separation, screen defoaming, and then absorption by a water washing plate, and then membrane separation, to achieve the purpose of separating methanol;

[0026] Step 3: After being processed in a methanol separator, it is transported to a crude methanol discharge tank for further processing;

[0027] Step 4: transporting the obtained gas phase product to the interior of the flash steam methanol recovery tower for treatment;

[0028] Step 5: Finally, the flash steam is washed with desalted water to reduce the methanol content and recover the methanol.

[0029] In the step 2, the separation principle is: methanol is separated into vapor and liquid at 40°C, and then the circulating gas enters the circulation system again, and the separated methanol enters the distillation system after flash evaporation.

[0030] In the step 3, the mixture after being treated by the methanol separator passes through the crude methanol discharge tank, and the primary waste in the mixed liquid can be effectively filtered through the methanol discharge tank.

[0031] The method of the present invention uses a closed recycling process and a flash tank to further recover the non-condensable gas therein, thereby avoiding environmental pollution, eliminating open methanol recovery, greatly improving safety, and effectively increasing the yield of methanol recovery.

[0032] Under the maximum separation rate under full-load conditions of hydrogen production, about 2 tons of alcohol liquid is separated per day, with an alcohol content of about 80%. The daily production benefit of the alcohol liquid recovered is 3,200 yuan. The annual benefit of the device is 2*80%*2000*365=1.168 million yuan (calculated based on 8,000 hours of online operation time).

[0033] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for recycling alcohol-containing waste liquid from synthetic ammonia, characterized in that: The steps include: Step 1: Discharge the synthetic ammonia containing alcohol waste liquid into the interior of the methanol synthesis flash tank through a DN25 pipeline; Step 2: The waste liquid first passes through a methanol separator, and then undergoes mechanical separation, i.e., cyclone separation, screen defoaming, and then absorption by a water washing plate, and then membrane separation, to achieve the purpose of separating methanol; Step 3: After being processed in a methanol separator, it is transported to a crude methanol discharge tank for further processing; Step 4: transporting the obtained gas phase product to the interior of the flash steam methanol recovery tower for treatment; Step 5: Finally, the flash steam is washed with desalted water to reduce the methanol content and recover the methanol.

2. The method for recycling synthetic ammonia alcohol-containing waste liquid according to claim 1, characterized in that: In the step 2, the separation principle is: methanol is separated into vapor and liquid at 38-82°C, and then the circulating gas enters the circulation system again, and the separated methanol enters the distillation system after flash evaporation.

3. The method for recycling synthetic ammonia alcohol-containing waste liquid according to claim 1, characterized in that: In the step three, the mixture after being treated by the methanol separator passes through a crude methanol discharge tank, and the primary stream in the mixed liquid passes through the methanol discharge tank for effective filtration.

4. The method for recycling synthetic ammonia alcohol-containing waste liquid according to claim 2, characterized in that: The separation principle in step 2 is that methanol undergoes vapor-liquid separation at 40°C.

5. The method for recycling synthetic ammonia alcohol-containing waste liquid according to claim 1, characterized in that: This method eliminates open methanol recovery, greatly improves safety, and effectively increases the output of methanol recovery.

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