Waste acid recycling system in acetylene cleaning process

Abstract

The utility model discloses a waste acid recycling system in an acetylene purification process. The waste acid recycling system comprises an acetylene purification unit, an incineration cracking unit and a purification unit, an outlet of a waste acid storage tank of the acetylene purification unit is communicated with an inlet of a stokehole waste acid tank of the incineration cracking unit through a pipeline, and a thermal medium outlet of a multi-stage heat exchanger of the incineration cracking unit is communicated with a flue gas inlet of a dynamic wave washer of the purification unit through a pipeline; and a water outlet of the sump of the purification unit is communicated with a water inlet of the generation water tank of the acetylene purification unit through a pipeline. The method has the advantages that the waste sulfuric acid generated in the acetylene purification process is collected and then is incinerated and cracked, and the acid-containing wastewater generated after incineration is neutralized and reused in the acetylene generator, so that the treatment cost of waste acid delivery treatment is saved, the water resource is saved, the consumption of production water is reduced, and the production cost is reduced. And meanwhile, the incinerated flue gas can also be used for a sulfuric acid conversion process, so that the recycling of waste gas is realized.

Description

Technical field:

[0001] The utility model relates to a recycling system for acid-containing wastewater, in particular to a recycling system for waste acid in an acetylene purification process. Background technology:

[0002] When preparing acetylene by the calcium carbide method, since the calcium carbide raw material for producing acetylene contains a small amount of calcium sulfide and phosphide, the prepared crude acetylene gas contains impurities such as phosphine and hydrogen sulfide, and needs to be purified by acid washing and alkali washing to obtain refined acetylene gas with a purity of more than 99% (volume fraction). The principle of purification is to use the strong dehydration and strong oxidizing properties of concentrated sulfuric acid with a mass fraction of 98% to absorb the moisture in the crude acetylene gas, oxidize impurities such as PH3 and H2S in the crude acetylene gas, and the generated acidic gas is neutralized with alkali solution and finally removed. The acid washing process will produce waste sulfuric acid with a mass fraction of 75-80%, which contains a variety of impurities, is black in color, and has a strong stench, which limits the recycling of waste sulfuric acid, increases the difficulty and cost of treatment, is not conducive to energy conservation and emission reduction of enterprises, and affects economic benefits. Utility model content:

[0003] In order to solve the above problems, the purpose of the utility model is to provide a waste acid recovery and utilization system in the acetylene purification process.

[0004] The utility model is implemented by the following technical solutions:

[0005] A waste acid recovery and utilization system in an acetylene purification process, comprising an acetylene purification unit, an incineration and cracking unit, and a purification unit;

[0006] The outlet of the waste acid storage tank of the acetylene purification unit is connected to the inlet of the waste acid tank in front of the furnace of the incineration and cracking unit through a pipeline, the heat medium outlet of the multi-stage heat exchanger of the incineration and cracking unit is connected to the flue gas inlet of the dynamic wave scrubber of the purification unit through a pipeline, and the water outlet of the sump of the purification unit is connected to the water inlet of the generating water tank of the acetylene purification unit through a pipeline.

[0007] Furthermore, the acetylene purification unit includes a generating water tank, an acetylene generator, an acetylene gas cooling tower, an acetylene compressor, an acetylene gas cooling tower, a demister, a sulfuric acid tower, a sulfuric acid tower, an acid mist collector, an alkali washing tower and an anti-decomposition tower;

[0008] The water outlet of the generating water tank is communicated with the water inlet of the acetylene generator through a pipeline, and the crude acetylene gas outlet of the acetylene generator is connected to the acetylene gas cooling tower 1, the acetylene compressor, the acetylene gas cooling tower 2, the demister, the sulfuric acid tower 1, the sulfuric acid tower 2, the acid mist collector, the alkali washing tower and the anti-decomposition tower in sequence through a pipeline;

[0009] The liquid outlet of the concentrated acid storage tank is connected to the sulfuric acid inlet of the second sulfuric acid tower through a pipeline, the sulfuric acid outlet of the second sulfuric acid tower is connected to the sulfuric acid inlet of the first sulfuric acid tower through a pipeline, and the sulfuric acid outlet of the first sulfuric acid tower is connected to the inlet of the waste acid storage tank through a pipeline.

[0010] Furthermore, the incineration and cracking unit includes a pre-furnace waste acid tank, a cracking furnace and a multi-stage heat exchanger;

[0011] The outlet of the pre-furnace waste acid tank is communicated with the spray gun inlet of the cracking furnace through a pipeline, and the flue gas outlet of the cracking furnace is communicated with the heat medium inlet of the multi-stage heat exchanger through a pipeline.

[0012] Further, the purification unit includes a power wave scrubber, a desorption tower, a sump and a liquid caustic soda storage tank;

[0013] The liquid outlet of the dynamic wave scrubber is connected to the inlet of the stripping tower through a pipeline, and the liquid outlet of the stripping tower and the outlet of the liquid alkali storage tank are both connected to the inlet of the sump through pipelines, and an agitator is provided in the sump.

[0014] Furthermore, the purification unit also includes a packing tower and an electric demisting device;

[0015] The flue gas outlet of the dynamic wave scrubber and the flue gas outlet of the desorption tower are both connected to the air inlet of the packing tower through a pipeline, and the air outlet of the packing tower is connected to the air inlet of the electric demisting device through a pipeline.

[0016] Furthermore, a liquid level sensor and a pH sensor are provided in the sump, a drainage valve and a drainage pump are provided on the pipeline connecting the sump and the generating water tank, and an alkali adding valve is provided on the pipeline connecting the liquid alkali storage tank and the sump;

[0017] The signal output ends of the liquid level sensor and the pH sensor are both signal-connected to the signal input end of the controller, and the signal output end of the controller is signal-connected to the signal input ends of the drain valve, the alkali adding valve and the drain pump, respectively.

[0018] Advantages of the utility model:

[0019] The utility model collects the waste sulfuric acid generated in the acetylene purification process and then burns and cracks it. The acid-containing waste water generated after the incineration is neutralized and then reused in the acetylene generator, which not only saves the treatment cost of sending the waste acid for external treatment, but also saves water resources and reduces the consumption of production water. At the same time, the smoke after incineration can also be used in the sulfuric acid conversion process, thus realizing the reuse of the waste gas. Description of the drawings:

[0020] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 Schematic diagram of system connection of this embodiment;

[0022] Figure 2 This is a control principle diagram of this embodiment.

[0023] In the figure: acetylene purification unit 1, generating water tank 11, acetylene generator 12, acetylene gas cooling tower 13, acetylene compressor 14, acetylene gas cooling tower 2 15, demister 16, sulfuric acid tower 17, sulfuric acid tower 2 18, acid mist collector 19, alkali washing tower 110, inhibition tower 111, concentrated acid storage tank 112, waste acid storage tank 113, incineration cracking unit 2, front waste acid tank 21, cracking furnace 22, multi-stage heat exchanger 23, purification unit 3, dynamic wave scrubber 31, desorption tower 32, sump 33, liquid alkali storage tank 34, packing tower 35, electric demister 36, agitator 37, liquid level sensor 4, pH sensor 5, drain valve 6, drain pump 7, alkali adding valve 8, controller 9. Specific implementation method:

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] Embodiment 1:

[0026] like Figure 1 , 2 The waste acid recovery and utilization system in the acetylene purification process shown in the figure comprises an acetylene purification unit 1, an incineration and cracking unit 2 and a purification unit 3; wherein:

[0027] The acetylene purification unit 1 includes a generating water tank 11, an acetylene generator 12, an acetylene gas cooling tower 13, an acetylene compressor 14, an acetylene gas cooling tower 2 15, a demister 16, a sulfuric acid tower 17, a sulfuric acid tower 2 18, an acid mist collector 19, an alkali washing tower 110 and an anti-decomposition tower 111; the incineration and cracking unit 2 includes a pre-furnace waste acid tank 21, a cracking furnace 22 and a multi-stage heat exchanger 23; the purification unit 3 includes a dynamic wave scrubber 31, a desorption tower 32, a sump 33 and a liquid alkali storage tank 34; the purification unit 3 also includes a packing tower 35 and an electric demister 36.

[0028] Specifically, the crude acetylene gas outlet of the acetylene generator 12 is connected to the acetylene gas cooling tower 13, the acetylene compressor 14, the acetylene gas cooling tower 15, the demister 16, the sulfuric acid tower 17, the sulfuric acid tower 18, the acid mist collector 19, the alkali washing tower 110 and the inhibition tower 111 in sequence through pipelines; the liquid outlet of the concentrated acid storage tank 112 is connected to the sulfuric acid inlet of the sulfuric acid tower 18 through a pipeline, the sulfuric acid outlet of the sulfuric acid tower 18 is connected to the sulfuric acid inlet of the sulfuric acid tower 17 through a pipeline, and the sulfuric acid outlet of the sulfuric acid tower 17 is connected to the inlet of the waste acid storage tank 113 through a pipeline.

[0029] The outlet of the waste acid storage tank 113 is connected to the inlet of the pre-furnace waste acid tank 21 through a pipeline, the outlet of the pre-furnace waste acid tank 21 is connected to the spray gun inlet of the cracking furnace 22 through a pipeline, and the flue gas outlet of the cracking furnace 22 is connected to the heat medium inlet of the multi-stage heat exchanger 23 through a pipeline.

[0030] The heat medium outlet of the multi-stage heat exchanger 23 is connected to the flue gas inlet of the power wave scrubber 31 through a pipeline, the liquid outlet of the power wave scrubber 31 is connected to the inlet of the stripping tower 32 through a pipeline, the liquid outlet of the stripping tower 32 and the outlet of the liquid alkali storage tank 34 are both connected to the inlet of the sump 33 through a pipeline, and a stirrer 37 is provided in the sump 33. The water outlet of the sump 33 is connected to the water inlet of the generating water tank 11 through a pipeline, and the water outlet of the generating water tank 11 is connected to the water inlet of the acetylene generator 12 through a pipeline.

[0031] The flue gas outlet of the power wave scrubber 31 and the flue gas outlet of the desorption tower 32 are both connected to the air inlet of the packing tower 35 through a pipeline, and the air outlet of the packing tower 35 is connected to the air inlet of the electric demisting device 36 through a pipeline.

[0032] In this embodiment, a liquid level sensor 4 and a pH sensor 5 are provided in the sump 33, a drain valve 6 and a drain pump 7 are provided on the pipeline connecting the sump 33 and the generating water tank 11, and an alkali adding valve 8 is provided on the pipeline connecting the liquid alkali storage tank 34 and the sump 33; the signal output ends of the liquid level sensor 4 and the pH sensor 5 are both signal-connected to the signal input ends of the controller 9, and the signal output end of the controller 9 is respectively signal-connected to the signal input ends of the drain valve 6, the alkali adding valve 8 and the drain pump 7.

[0033] Job Description:

[0034] The crude acetylene gas generated in the acetylene generator 12 enters the acetylene gas cooling tower 13 for cooling, and then is pressurized by the acetylene compressor 14. The pressurized crude acetylene enters the acetylene gas cooling tower 2 15 for further cooling. The acetylene gas cooled to ≤15°C passes through the demister 16 to remove moisture entrained in the acetylene gas, and then enters the sulfuric acid tower 17 to directly contact the dilute sulfuric acid from the sulfuric acid tower 2 18 to react and remove impurities, and then enters the sulfuric acid tower 2 18 to react and remove impurities with the concentrated sulfuric acid from the concentrated acid storage tank 112 to remove impurities such as hydrogen sulfide and phosphine contained in the acetylene gas. The acid mist in the acetylene gas after pickling is removed by the acid mist remover 19, and then the acidic substances in the acetylene gas are removed by the alkali washing tower 110, and finally refined acetylene gas is obtained.

[0035] The waste acid produced by the sulfuric acid tower 17 is sprayed into the cracking furnace 22 in the form of atomization through a spray gun. The waste sulfuric acid is decomposed into SO2, SO3, O2 and H2O in the cracking furnace 22. The reaction equation is:

[0036] H2SO4===H2O+0.98SO2+0.02SO3+0.49O2-206.6kJ / mol

[0037] The flue gas from the cracking furnace 22 is cooled by the multi-stage heat exchanger 23 and then enters the dynamic wave scrubber 31 to contact with the back-sprayed dilute acid to wash away most of the impurities such as sulfur trioxide and cool it. The flue gas after gas-liquid separation in the desorption tower 32 and the flue gas washed by the dynamic wave scrubber 31 are both washed and cooled in the packed tower 35. Most of the impurities in the flue gas coming out of the packed tower 35 have been removed, and then the acid mist is removed by the electric demisting device 36. The purified flue gas is sent to the sulfuric acid conversion process for the preparation of sulfuric acid.

[0038] The acid-containing wastewater separated by the stripping tower 32 is collected in the sump 33. When the liquid level of the acid-containing wastewater in the sump 33 reaches a preset high liquid level, the alkali adding valve 8 is opened, and 32% liquid alkali is added to the sump 33 through the liquid alkali storage tank 34. The agitator 37 is started for stirring, so that the liquid alkali can play a breeding role for the acid-containing wastewater. When the pH sensor 5 detects that the pH of the wastewater in the sump 33 reaches 7.0, the drain valve 6 is opened, and the drain pump 7 is started to transport the neutralized wastewater in the sump 33 to the generating water tank 11 for use in the production of acetylene by the calcium carbide method, thereby achieving "0" discharge of wastewater.

[0039] This embodiment not only saves the cost of sending waste acid for external treatment, but also reuses the acid-containing wastewater after incineration into the acetylene generator after neutralization, saving water resources and reducing the consumption of production water. At the same time, the flue gas after incineration can also be used in the sulfuric acid conversion process, realizing the reuse of waste gas.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A waste acid recovery and utilization system in an acetylene purification process, characterized in that: It includes acetylene purification unit, incineration cracking unit and purification unit; The outlet of the waste acid storage tank of the acetylene purification unit is connected to the inlet of the waste acid tank in front of the furnace of the incineration and cracking unit through a pipeline, the heat medium outlet of the multi-stage heat exchanger of the incineration and cracking unit is connected to the flue gas inlet of the dynamic wave scrubber of the purification unit through a pipeline, and the water outlet of the sump of the purification unit is connected to the water inlet of the generating water tank of the acetylene purification unit through a pipeline.

2. The waste acid recovery and utilization system in the acetylene purification process according to claim 1, characterized in that: The acetylene purification unit comprises a generating water tank, an acetylene generator, an acetylene gas cooling tower 1, an acetylene compressor, an acetylene gas cooling tower 2, a demister, a sulfuric acid tower 1, a sulfuric acid tower 2, an acid mist collector, an alkali washing tower and an anti-decomposition tower; The water outlet of the generating water tank is communicated with the water inlet of the acetylene generator through a pipeline, and the crude acetylene gas outlet of the acetylene generator is connected to the acetylene gas cooling tower 1, the acetylene compressor, the acetylene gas cooling tower 2, the demister, the sulfuric acid tower 1, the sulfuric acid tower 2, the acid mist collector, the alkali washing tower and the anti-decomposition tower in sequence through a pipeline; The liquid outlet of the concentrated acid storage tank is connected to the sulfuric acid inlet of the second sulfuric acid tower through a pipeline, the sulfuric acid outlet of the second sulfuric acid tower is connected to the sulfuric acid inlet of the first sulfuric acid tower through a pipeline, and the sulfuric acid outlet of the first sulfuric acid tower is connected to the inlet of the waste acid storage tank through a pipeline.

3. The waste acid recovery and utilization system in the acetylene purification process according to claim 1, characterized in that: The incineration and cracking unit comprises a waste acid tank in front of the furnace, a cracking furnace and a multi-stage heat exchanger; The outlet of the pre-furnace waste acid tank is communicated with the spray gun inlet of the cracking furnace through a pipeline, and the flue gas outlet of the cracking furnace is communicated with the heat medium inlet of the multi-stage heat exchanger through a pipeline.

4. The waste acid recovery and utilization system in the acetylene purification process according to claim 1, characterized in that: The purification unit includes a power wave scrubber, a desorption tower, a sump and a liquid caustic soda storage tank; The liquid outlet of the dynamic wave scrubber is connected to the inlet of the stripping tower through a pipeline, and the liquid outlet of the stripping tower and the outlet of the liquid alkali storage tank are both connected to the inlet of the sump through pipelines, and an agitator is provided in the sump.

5. The waste acid recovery and utilization system in the acetylene purification process according to claim 4, characterized in that: The purification unit also includes a packing tower and an electric demisting device; The flue gas outlet of the dynamic wave scrubber and the flue gas outlet of the desorption tower are both connected to the air inlet of the packing tower through a pipeline, and the air outlet of the packing tower is connected to the air inlet of the electric demisting device through a pipeline.

6. The waste acid recovery and utilization system in the acetylene purification process according to claim 4, characterized in that: A liquid level sensor and a pH sensor are provided in the sump, a drainage valve and a drainage pump are provided on a pipeline connecting the sump and the generating water tank, and an alkali adding valve is provided on a pipeline connecting the liquid alkali storage tank and the sump; The signal output ends of the liquid level sensor and the pH sensor are both signal-connected to the signal input end of the controller, and the signal output end of the controller is signal-connected to the signal input ends of the drain valve, the alkali adding valve and the drain pump, respectively.

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