Heat treatment production line and process for concentration production and preparation of nitric acid waste acid

Abstract

The invention relates to the technical field of waste acid concentration treatment, and provides a one-nitre waste acid concentration production and preparation heat treatment production line and a process thereof, which comprises a one-nitre waste acid tank, a preheating system, a first-stage acid evaporator, a first-stage steam treatment system, a second-stage acid evaporator and a second-stage steam treatment system, raw materials in a nitre waste acid tank are indirectly heated again by a steam condensation water tank after being subjected to gradient heating through a waste acid preheating system, and then are sequentially fed into a waste sulfuric acid first-stage acid evaporator and a waste sulfuric acid second-stage acid evaporator; two times of negative pressure evaporation and concentration treatment are carried out in a waste sulfuric acid first-stage acid evaporator and a waste sulfuric acid second-stage acid evaporator in a steam tantalum pipe indirect heating mode, heat exchange with waste acid from a nitre waste acid tank is carried out through a waste acid second-stage preheater, indirect cooling is carried out through circulating water of a concentrated acid cooler, and then the waste acid flows into a concentrated sulfuric acid tank by utilizing equipment potential difference; according to the invention, the treatment efficiency of waste acid is improved after multiple gradient treatments, concentration in the same kettle is avoided, and the production requirements of high heat and high pressure are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of waste acid concentration treatment, and specifically to a heat treatment production line and process for concentrated production of nitric waste acid. Background Art

[0002] Industrial enterprises are major consumers of resources and emitters of pollutants, and they have a greater social responsibility for energy conservation and emission reduction. Most companies have ignored the problem of environmental pollution in pursuit of economic benefits. Nowadays, many chemical companies need to use acid as a cleaning fluid for their products to clean the surface of metals. The amount of acid used in the metal cleaning process is large and metal ions will continue to accumulate in the acid. When the metal in the acid reaches a certain concentration, the treatment effect does not meet the process requirements, so the acid needs to be reconfigured and replaced after a certain number of cycles of cleaning. In this process, a large amount of waste acid is produced. These waste acids contain high concentrations of acid, metals, and suspended particulate matter, which pose a certain threat to the environment and need to be treated. Since industrial waste acid and waste liquid contain more water, the concentration of the waste acid and waste liquid is low and cannot be used. Therefore, the industrial waste acid can be purified by distillation for reuse. After searching, the announcement number CN218202264U discloses a waste acid concentration distillation system, including a distillation mechanism, a vacuum extraction mechanism and a vacuum distillation heating and refrigeration device; the distillation mechanism includes a distillation kettle, a first cooling tube, a heat exchange tube and a water receiving tray; the input end of the vacuum extraction mechanism is connected to the outlet of the water receiving tray; the vacuum distillation heating and refrigeration device includes a refrigeration system and a heating system, the output end of the refrigeration system is connected to the input end of the first cooling tube, and the output end of the heating system is connected to the input end of the heat exchange tube. The waste acid concentration and distillation system can realize the simultaneous use of heating and refrigeration. The vacuum extraction mechanism first evacuates the distillation kettle, and the heating system heats the waste acid in the distillation kettle. Under negative pressure and high vacuum, the boiling point of the waste acid in the distillation kettle is reduced and gasified. The water vapor generated after the waste acid is concentrated will be liquefied and condensed in the water receiving tray after heat exchange with the first cooling tube, thereby realizing the concentration and purification of the waste acid containing more water in the industrial waste phosphoric acid waste liquid, thereby achieving the purpose of recycling the waste acid.

[0003] However, the above technology still has the following problems: the above waste acid concentration and distillation system completes the distillation in a unified manner in a distillation kettle, and concentrates the waste acid under the action of negative pressure and high vacuum, which places high quality requirements on the high heat and high pressure that the distillation kettle needs to withstand. At the same time, under high requirements, the tolerance problem of the transmission pipeline is prone to occur, which in turn affects production safety. Summary of the invention

[0004] The invention provides a heat treatment production line and a process for concentrated production of nitric acid waste, which solves the problem in the prior art that the waste acid concentration and distillation system is uniformly completed in a distillation kettle with high requirements for distillation.

[0005] The technical scheme of the present invention is as follows: a nitric acid waste acid concentration production preparation heat treatment production line and process thereof, including a nitric acid waste acid tank, and also including: A preheating system, which is used to gradually heat up the nitric acid waste raw material pumped out of the nitric acid waste tank; The first-stage acid evaporator is used to carry out a negative pressure evaporation and concentration treatment on the waste acid after the temperature of the preheating system is raised; A primary steam treatment system is used to treat the primary steam generated during the treatment process of the primary acid steam distillation device; The secondary acid evaporator is used to carry out secondary negative pressure evaporation and concentration treatment on the waste acid after being treated by the primary acid evaporator; The secondary steam treatment system is used to treat the secondary steam generated during the secondary acid evaporator treatment process.

[0006] Preferably, the preheating system comprises a primary waste acid preheater, a secondary waste acid preheater and a tertiary waste acid preheater, and the primary waste acid preheater, the secondary waste acid preheater and the tertiary waste acid preheater all use heat transfer oil to indirectly heat the waste acid through a tantalum tube.

[0007] Preferably, the primary steam treatment system comprises a primary washing tower, a primary washing liquid cooler, a primary chlorobenzene tank, a primary acid water cooler, a primary stratification tank, a primary wastewater tank, a medium-pressure steam tank, a condensed water tank, and a primary vacuum buffer tank. The water vapor containing a small amount of nitrochlorobenzene and water acid mist in the primary acid evaporator enters the primary washing tower. The acid liquid at the bottom of the primary washing tower is passed through the primary washing liquid cooler through a primary washing liquid circulation pump for cooling and then sprayed into the top of the primary washing tower. The acid mist entrained in the water vapor is washed into the bottom of the primary washing tower and continuously circulated by the primary washing liquid circulation pump. After continuous circulation, the excess acid liquid flows into the primary acid evaporator through the overflow pipe on the primary washing tower. A small amount of chlorobenzene is pumped into the primary washing tower through the primary chlorobenzene tank by the primary chlorobenzene pump. The top of the first-level acid water cooler is formed, and the chlorobenzene gas, water vapor and nitrochlorobenzene gas formed enter the first-level acid water cooler together. The nitrochlorobenzene, chlorobenzene and water after the mixed gas is condensed by the first-level acid water cooler flow into the first-level stratification tank by gravity. The organic phase of the lower layer of the first-level stratification tank flows into the first-level chlorobenzene tank for continuous circulation. The waste water of the upper layer of the first-level stratification tank flows into the first-level wastewater tank by gravity, and is pumped into the alkali washing wastewater tank by the first-level alkali washing wastewater pump as the secondary water washing water. The tail gas generated by the first-level acid water cooler enters the first-level vacuum buffer tank and is pumped out by the first-level vacuum pump group. The medium-pressure steam tank pressurizes the low-temperature water input by the outer tube and passes it into the first-level acid evaporator. The circulating water in the condensation water tank pipeline is heated by the high heat residual temperature of the first-level acid evaporator, and then passes to the waste acid three-stage preheater.

[0008] Preferably, the secondary steam treatment system comprises a secondary washing tower, a secondary washing cooler, a secondary acid water cooler, a secondary wastewater tank, a concentrated acid cooler, a concentrated sulfuric acid tank, and a secondary vacuum buffer tank. The water vapor containing a small amount of nitrochlorobenzene and water acid mist in the secondary acid evaporator enters the secondary washing tower. The acid liquid at the bottom of the secondary washing tower is passed through the secondary washing cooler through a secondary washing liquid circulation pump for cooling and then sprayed into the top of the secondary washing tower. The acid mist entrained in the water vapor is washed into the bottom of the secondary washing tower and continuously circulated by the secondary washing liquid circulation pump. After continuous circulation, the excess acid liquid is discharged through the overflow on the secondary washing tower. The flow pipe flows into the secondary acid evaporator, and the chlorobenzene gas and water vapor formed on the top of the secondary washing tower and the nitrochlorobenzene gas enter the secondary acid water cooler together. The nitrochlorobenzene, chlorobenzene and water after the mixed gas is condensed by the secondary acid water cooler flow into the secondary wastewater tank by gravity. The wastewater in the secondary wastewater tank is pumped into the alkaline washing wastewater tank by the secondary alkaline washing wastewater pump. The tail gas generated by the secondary acid water cooler enters the secondary vacuum buffer tank and is pumped out by the secondary vacuum pump group. The waste gas generated by the waste acid primary preheater is cooled by the concentrated acid cooler and then enters the concentrated sulfuric acid tank and is pumped out to the sulfuric acid transfer tank by the concentrated sulfuric acid pump.

[0009] Preferably, the primary vacuum pump group includes a primary circulation condenser and a primary steam-water separator, and the primary vacuum buffer tank discharges water vapor into the primary circulation condenser for cooling and then enters the primary steam-water separator.

[0010] Preferably, the secondary vacuum pump group includes a secondary circulation condenser A, a secondary circulation condenser B, a secondary circulation condenser C, a secondary circulation condenser D, a secondary steam-water separator A and a secondary steam-water separator B. The secondary vacuum buffer tank discharges a portion of water vapor into the secondary circulation condenser A and enters the secondary steam-water separator A after cooling. The gas separated by the secondary steam-water separator A is cooled by the secondary circulation condenser B and then pumped into the secondary steam-water separator A again by the secondary circulation liquid pump before being discharged. Preferably, the secondary vacuum buffer tank discharges another part of the water vapor into the secondary circulation condenser C for cooling and then enters the secondary steam-water separator B. The gas separated by the secondary steam-water separator B is cooled by the secondary circulation condenser D and then pumped into the secondary steam-water separator B again by the secondary circulation liquid pump and then discharged.

[0011] Preferably, the nitric acid waste acid raw material introduced into the nitric acid waste acid tank is heated to 130±10°C through the waste acid primary preheater and the waste acid secondary preheater, and then the hot water at 200±10°C in the condensed water tank is indirectly heated to 145±10°C through the waste acid tertiary preheater and sent to the primary acid evaporator. The steam used in the primary acid evaporator is 200±10°C and the pressure is 1.4, and the operating temperature of the entire negative pressure evaporation concentration treatment is maintained at 180±10°C and the operating pressure is maintained at 10±1kPaA. The concentration of sulfuric acid after treatment in the primary acid evaporator is 89±1%.

[0012] Preferably, the operating temperature of the heat transfer oil inlet of the secondary acid evaporator is 250±10°C, and the outlet operating temperature is 230±10°C. The operating temperature of the entire negative pressure evaporation concentration treatment is maintained at 200±10°C and the operating pressure is 2±0.1kPaA. The concentration of sulfuric acid after treatment by the secondary acid evaporator is 95±1% and the temperature is 195±10°C. The waste acid secondary preheater and the waste acid primary preheater exchange heat between the waste acid introduced into the secondary acid evaporator and the waste acid in the nitric acid waste acid tank and cool it to 110±10°C. The concentrated acid cooler indirectly cools the concentrated acid of the waste acid primary preheater to 50±2°C through circulating water.

[0013] The beneficial effects of the present invention are: In the present invention, the raw materials in the nitrate waste acid tank are heated in stages by the waste acid preheating system, and then indirectly heated by the steam condensation water tank, and then sequentially sent to the waste sulfuric acid primary acid evaporator and the waste sulfuric acid secondary acid evaporator, and the waste sulfuric acid primary acid evaporator and the waste sulfuric acid secondary acid evaporator are subjected to two negative pressure evaporation and concentration treatments by indirect heating with a steam tantalum tube, and the formed sulfuric acid concentration is about 95±1% and the temperature is about 195±10° C., and then the waste acid from the nitrate waste acid tank is cooled to about 110° C. by heat exchange with the waste acid from the nitrate waste acid tank by the waste acid secondary preheater, and then indirectly cooled to about 50±2° C. by circulating water of the concentrated acid cooler, and then the raw materials are fed into the concentrated sulfuric acid tank by gravity using the equipment potential difference. Compared with the prior art, the present invention improves the treatment efficiency of the waste acid after multiple gradient treatments, and avoids completing the concentration in the same kettle, thereby reducing the production requirements of high heat and high pressure, and improving the production safety and quality; The present invention connects water vapor evaporated from a primary acid evaporator to a primary steam treatment system. The water vapor evaporated from the primary acid evaporator contains a small amount of nitrochlorobenzene and a small amount of acid mist, and enters a primary washing tower. A primary washing liquid circulation pump cools the acid at the bottom of the primary washing tower through a primary washing liquid cooler and then sprays it into the top of the primary washing tower, washes the acid mist entrained in the water vapor into the bottom of the tower for continuous circulation, and after continuous circulation, the excess acid overflows from an overflow pipe into the primary acid evaporator, and a small amount of chlorobenzene is continuously pumped into the upper part of the primary washing tower by a primary chlorobenzene tank and a primary chlorobenzene pump, so that chlorobenzene gas, water vapor and nitrochlorobenzene gas enter the primary acid water cooler together, and the condensed nitrochlorobenzene, chlorobenzene and water flow into a primary stratification tank by gravity, and the lower organic phase flows into the primary chlorobenzene tank by gravity for continuous circulation. Compared with the prior art, the present invention can fully process water vapor in waste acid and reduce resource loss at the same time. The present invention connects the water vapor evaporated from the secondary acid evaporator to the secondary steam treatment system. The treatment process of the water vapor evaporated from the secondary acid evaporator is basically the same as the treatment process of the water vapor from the primary acid evaporator, except that the chlorobenzene circulation is no longer added through the primary chlorobenzene tank. In addition, the secondary acid water cooler uses low-temperature circulating water as a refrigerant, and a small amount of uncondensed gas after passing through the acid water condenser is sent to the secondary vacuum pump unit. Compared with the prior art, the present invention can maintain the treatment effect of the water vapor evaporated from the secondary acid evaporator of waste sulfuric acid through the treatment method, while reducing the treatment process to improve the treatment efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0015] Figure 1 A schematic diagram of the heat treatment production line for concentrated production of nitric acid waste and its process flow proposed by the present invention; Figure 2 A schematic flow chart of a primary steam treatment system used in the primary acid evaporator for waste sulfuric acid proposed in the present invention; Figure 3 A schematic flow chart of a secondary steam treatment system used in the secondary acid evaporator for waste sulfuric acid proposed in the present invention; Figure 4 A schematic diagram of the vacuum pump unit flow for the two-stage tail gas treatment proposed by the present invention; Figure 5 A schematic diagram of the vacuum pump unit flow for the first-stage tail gas treatment proposed by the present invention; In the figure: 1. Nitrate waste acid tank; 2. Preheating system; 21. Waste acid primary preheater; 22. Waste acid secondary preheater; 23. Waste acid tertiary preheater; 3. Primary acid evaporator; 4. Primary steam treatment system; 41. Primary washing tower; 42. Primary washing liquid cooler; 43. Primary chlorobenzene tank; 44. Primary acid water cooler; 45. Primary stratification tank; 46. Primary waste water tank; 47. Medium pressure steam tank; 48. Condensate tank; 49. Primary vacuum buffer tank; 5. Secondary acid evaporator; 6. Secondary steam treatment system; 61. Secondary washing tower; 62. Secondary washing cooler; 63. Secondary acid water cooler; 64. Secondary waste water tank; 65. Concentrated acid cooler; 66. Concentrated sulfuric acid tank; 67. Secondary vacuum buffer tank. DETAILED DESCRIPTION

[0016] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] See also Figure 1 The present invention provides a technical solution: a nitrate waste acid concentration production preparation heat treatment production line and a process thereof, comprising a nitrate waste acid tank 1, a preheating system 2, a primary acid evaporator 3, a primary steam treatment system 4, a secondary acid evaporator 5 and a secondary steam treatment system 6, wherein the preheating system 2 is used for gradually heating the nitrate waste acid raw material pumped out of the nitrate waste acid tank 1, the primary acid evaporator 3 is used for performing a negative pressure evaporation concentration treatment on the waste acid after the preheating system 2 is heated, the primary steam treatment system 4 is used for treating the primary steam generated during the treatment of the primary acid evaporator 3, the secondary acid evaporator 5 is used for performing a secondary negative pressure evaporation concentration treatment on the waste acid after the treatment of the primary acid evaporator 3, and the secondary steam treatment system 6 is used for treating the secondary steam generated during the treatment of the secondary acid evaporator 5.

[0018] The preheating system 2 includes a primary waste acid preheater 21, a secondary waste acid preheater 22, and a tertiary waste acid preheater 23. The primary waste acid preheater 21, the secondary waste acid preheater 22, and the tertiary waste acid preheater 23 all use heat transfer oil to indirectly heat the waste acid through a tantalum tube.

[0019] The primary steam treatment system 4 includes a primary washing tower 41, a primary washing liquid cooler 42, a primary chlorobenzene tank 43, a primary acid water cooler 44, a primary stratification tank 45, a primary wastewater tank 46, a medium-pressure steam tank 47, a condensed water tank 48, and a primary vacuum buffer tank 49. The water vapor containing a small amount of nitrochlorobenzene and water acid mist in the primary acid evaporator 3 enters the primary washing tower 41, and the acid liquid at the bottom of the primary washing tower 41 is passed into the primary washing liquid cooler 42 through a primary washing liquid circulation pump for cooling and then sprayed into the top of the primary washing tower 41, while the acid mist entrained in the water vapor is washed into the bottom of the primary washing tower 41 and continuously circulated by the primary washing liquid circulation pump. After continuous circulation, the excess acid liquid flows into the primary acid evaporator 3 through the overflow pipe on the primary washing tower 41, and a small amount of chlorobenzene is pumped into the top of the primary washing tower 41 by the primary chlorobenzene pump through the primary chlorobenzene tank 43, and the formed chlorobenzene gas is together with the water vapor and the nitrochlorobenzene gas. The gas enters the primary acid water cooler 44, and the nitrobenzene, chlorobenzene and water after the mixed gas is condensed by the primary acid water cooler 44 flow into the primary stratification tank 45 by gravity, and the organic phase in the lower layer of the primary stratification tank 45 flows into the primary chlorobenzene tank 43 for continuous circulation, and the waste water in the upper layer of the primary stratification tank 45 flows into the primary waste water tank 46 by gravity, and is pumped into the alkaline washing waste water tank by the primary alkali washing waste water pump as the secondary washing water. The tail gas generated by the primary acid water cooler 44 enters the primary vacuum buffer tank 49 and is pumped out by the primary vacuum pump group. The primary vacuum pump group includes a primary circulation condenser and a primary steam-water separator. The water vapor discharged from the primary vacuum buffer tank 49 enters the primary circulation condenser for cooling and then enters the primary steam-water separator. The medium-pressure steam tank 47 pressurizes the low-temperature water input by the external pipe and passes it into the primary acid evaporator 3. The circulating water in the pipeline of the condensate tank 48 is heated by the high heat residual temperature of the primary acid evaporator 3, and then passes to the waste acid tertiary preheater 23.

[0020] The secondary steam treatment system 6 includes a secondary washing tower 61, a secondary washing cooler 62, a secondary acid water cooler 63, a secondary wastewater tank 64, a concentrated acid cooler 65, a concentrated sulfuric acid tank 66, and a secondary vacuum buffer tank 67. The water vapor containing a small amount of nitrochlorobenzene and water acid mist in the secondary acid evaporator 5 enters the secondary washing tower 61. The acid liquid at the bottom of the secondary washing tower 61 is passed into the secondary washing cooler 62 through the secondary washing liquid circulation pump for cooling and then sprayed into the top of the secondary washing tower 61. The acid mist entrained in the water vapor is washed. The acid enters the bottom of the secondary washing tower 61 and is continuously circulated by the secondary washing liquid circulation pump. After continuous circulation, the excess acid liquid flows into the secondary acid evaporator 5 through the overflow pipe on the secondary washing tower 61. The chlorobenzene gas and water vapor and nitrochlorobenzene gas formed at the top of the secondary washing tower 61 enter the secondary acid water cooler 63 together. The nitrochlorobenzene and chlorobenzene and water after the mixed gas is condensed by the secondary acid water cooler 63 flow into the secondary waste water tank 64 by gravity. The waste water in the secondary waste water tank 64 is pumped into the alkali washing waste water tank through the secondary alkali washing waste water pump. The tail gas generated by the secondary acid water cooler 63 enters the secondary vacuum buffer tank 67 and is pumped out through the secondary vacuum pump group. The secondary vacuum pump group includes a secondary circulation condenser A, a secondary circulation condenser B, a secondary circulation condenser C, a secondary circulation condenser D, a secondary steam-water separator A and a secondary steam-water separator B. The secondary vacuum buffer tank 67 discharges a part of the water vapor into the secondary circulation condenser A for cooling and then enters the secondary steam-water separator A. The gas separated by the secondary steam-water separator A is cooled by the secondary circulation condenser B and then pumped into the secondary steam-water separator A again through the secondary circulation liquid pump and then discharged. The secondary vacuum buffer tank 67 discharges another part of the water vapor into the secondary circulation condenser C and then enters the secondary steam-water separator B for cooling. The gas separated by the secondary steam-water separator B is cooled by the secondary circulation condenser D and then pumped into the secondary steam-water separator B again through the secondary circulation liquid pump and then discharged. The waste gas generated by the waste acid primary preheater 21 is cooled by the concentrated acid cooler 65 and then enters the concentrated sulfuric acid tank 66 and is pumped out to the sulfuric acid transfer tank by the concentrated sulfuric acid pump.

[0021] The working principle and use process of the present invention are as follows: Figure 2 As shown, the nitric acid waste acid raw material introduced into the nitric acid waste acid tank 1 is heated to 130±10°C by the waste acid primary preheater 21 and the waste acid secondary preheater 22, and then the hot water of about 200±10°C in the steam condensation water tank 48 is indirectly heated to about 145±10°C by the waste acid tertiary preheater 23, and then sent to the primary acid steamer 3, as shown in FIG. Figure 3 As shown, the material in the primary acid evaporator 3 is subjected to negative pressure evaporation concentration treatment (operating temperature of about 180±10°C and operating pressure of about 10±1kPaA) by indirect heating of a tantalum tube with steam (about 200±10°C and about 1.4±0.1MPa); About 89% of the waste acid flows into the secondary acid evaporator 5 by gravity using the equipment potential difference. The material in the secondary acid evaporator 5 is subjected to negative pressure evaporation concentration treatment (operating temperature is about 200±10℃, operating pressure is about 2±0.1kPaA) by indirect heating of heat transfer oil through tantalum tube (the heat transfer oil inlet operating temperature is about 250±10℃, and the outlet operating temperature is about 230±10℃). After the waste acid is treated by the secondary acid evaporator 5, the concentration of sulfuric acid is about 95±1% and the temperature is about 195±10℃. The waste acid enters the waste acid secondary preheater 22 and the waste acid primary preheater 21 in stages to exchange heat with the waste acid from the nitrate waste acid tank 1 and cool to about 110℃. Then, it is indirectly cooled to about 50±2℃ by circulating water in the concentrated acid cooler 65 and flows into the concentrated sulfuric acid tank 66 by gravity using the equipment potential difference, and then is pumped into the sulfuric acid transfer tank by a concentrated sulfuric acid pump; like Figure 2 As shown, the water vapor evaporated from the primary acid evaporator 3 contains a small amount of nitrochlorobenzene and a small amount of acid mist, and enters the primary washing tower 41. The primary washing liquid circulation pump cools the acid at the bottom of the primary washing tower 41 through the primary washing liquid cooler 42 and sprays it into the top of the primary washing tower 41, washing the acid mist entrained in the water vapor into the bottom of the tower for continuous circulation. After continuous circulation, the excess acid overflows from the overflow pipe into the primary acid evaporator 3. A small amount of chlorobenzene is continuously pumped into the upper part of the primary washing tower 41 by the primary chlorobenzene tank 43 and the primary chlorobenzene pump, forming chlorobenzene gas, water vapor and nitrochlorobenzene gas, which enter the primary acid water cooler 44 (indirectly cooled by circulating water), and the condensed nitrochlorobenzene, chlorobenzene and water flow into the primary stratification tank 45 by gravity; the lower organic phase flows into the primary chlorobenzene tank 43 by gravity and circulates continuously, and the chlorobenzene (and the mixture of nitrochlorobenzene) therein is regularly pumped into the acid chlorobenzene tank by pump; after being neutralized by sodium hydroxide pump, the waste water of the upper layer flows into the primary waste water tank 46 by gravity, and is pumped into the alkaline waste water tank by the alkaline waste water pump as the secondary washing water; The tail gas cooled by the primary acid water cooler 44 enters the primary vacuum buffer tank 49 and is then discharged to the primary vacuum pump unit through the vacuum pump; like Figure 2 As shown, the treatment process of the water vapor evaporated from the secondary acid evaporator 5 in the present invention is basically the same as the treatment process of the water vapor from the primary acid evaporator 3 (the difference is that the chlorobenzene circulation is no longer added through the primary chlorobenzene tank 43). In addition, the secondary acid water cooler 63 uses low-temperature circulating water as a refrigerant, and a small amount of uncondensed gas after the acid water condenser is sent to the secondary vacuum pump unit. In this way, while maintaining the treatment effect of the water vapor evaporated from the secondary acid evaporator 5, the treatment process is reduced to improve the treatment efficiency. A vacuum pump unit is set for each of the primary and secondary tail gas treatments, and the work flow is referenced Figure 4 and Figure 5 .

[0022] The above are only preferred embodiments of the present invention and are 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 heat treatment production line and process for concentrated production of nitric acid waste, comprising a nitric acid waste tank (1), characterized in that: Also includes: A preheating system (2), used for gradually heating the nitric acid waste material pumped out of the nitric acid waste tank (1); The primary acid evaporator (3) is used to perform a negative pressure evaporation and concentration treatment on the waste acid heated by the preheating system (2); A primary steam treatment system (4) for treating primary steam generated during the treatment process of the primary acid evaporator (3); The secondary acid evaporator (5) is used to perform secondary negative pressure evaporation and concentration treatment on the waste acid treated by the primary acid evaporator (3); The secondary steam treatment system (6) is used to treat the secondary steam generated during the treatment process of the secondary acid evaporator (5).

2. The heat treatment production line and process for concentrated production of nitric acid waste according to claim 1, characterized in that: The preheating system (2) comprises a waste acid primary preheater (21), a waste acid secondary preheater (22), and a waste acid tertiary preheater (23); the waste acid primary preheater (21), the waste acid secondary preheater (22), and the waste acid tertiary preheater (23) all use heat transfer oil to indirectly heat the waste acid via a tantalum tube.

3. The heat treatment production line and process for concentrated production of nitric acid waste according to claim 2, characterized in that: The primary steam treatment system (4) comprises a primary washing tower (41), a primary washing liquid cooler (42), a primary chlorobenzene tank (43), a primary acid water cooler (44), a primary stratification tank (45), a primary waste water tank (46), a medium-pressure steam tank (47), a condensed water tank (48), and a primary vacuum buffer tank (49). The water vapor containing a small amount of nitrobenzene and water acid mist in the primary acid evaporator (3) enters the primary washing tower (41). The acid liquid at the bottom of the primary washing tower (41) is passed through the primary washing liquid cooler (42) by a primary washing liquid circulation pump, cooled, and then sprayed into the top of the primary washing tower (41). The acid mist entrained in the water vapor is washed into the bottom of the primary washing tower (41) and continuously circulated by the primary washing liquid circulation pump. After continuous circulation, the excess acid liquid flows into the primary acid evaporator (3) through the overflow pipe on the primary washing tower (41). A small amount of chlorobenzene is pumped into the primary acid evaporator (3) by the primary chlorobenzene pump through the primary chlorobenzene tank (43). At the top of the primary washing tower (41), the chlorobenzene gas, water vapor and nitrochlorobenzene gas formed enter the primary acid water cooler (44) together. The primary acid water cooler (44) condenses the mixed gas, and the nitrochlorobenzene, chlorobenzene and water flow into the primary stratification tank (45) by gravity. The organic phase in the lower layer of the primary stratification tank (45) flows by gravity into the primary chlorobenzene tank (43) for continuous circulation. The waste water in the upper layer of the primary stratification tank (45) flows by gravity into the primary waste water tank (46) and is pumped into the alkali washing waste water tank by the primary alkali washing waste water pump as secondary washing water. The tail gas generated by the primary acid water cooler (44) enters the primary vacuum buffer tank (49) and is pumped out by the primary vacuum pump group. The medium-pressure steam tank (47) pressurizes the low-temperature water input from the external pipe and passes it into the primary acid evaporator (3). The circulating water in the pipeline of the condensate tank (48) is heated by the high heat residual heat of the primary acid evaporator (3) and then passes to the waste acid tertiary preheater (23).

4. The heat treatment production line and process for concentrated production of nitric acid waste according to claim 2, characterized in that: The secondary steam treatment system (6) comprises a secondary washing tower (61), a secondary washing cooler (62), a secondary acid water cooler (63), a secondary wastewater tank (64), a concentrated acid cooler (65), a concentrated sulfuric acid tank (66), and a secondary vacuum buffer tank (67). The water vapor containing a small amount of nitrochlorobenzene and water acid mist in the secondary acid evaporator (5) enters the secondary washing tower (61). The acid liquid at the bottom of the secondary washing tower (61) is passed through the secondary washing cooler (62) by a secondary washing liquid circulation pump, cooled, and then sprayed into the top of the secondary washing tower (61). The acid mist entrained in the water vapor is washed into the bottom of the secondary washing tower (61) and continuously circulated by the secondary washing liquid circulation pump. After continuous circulation, the excess acid liquid passes through the secondary washing tower ( The secondary acid evaporator (5) flows into the overflow pipe on the secondary washing tower (61), and the chlorobenzene gas and water vapor formed at the top of the secondary washing tower (61) and the nitrochlorobenzene gas enter the secondary acid water cooler (63) together. The nitrochlorobenzene and chlorobenzene and water after condensing the mixed gas in the secondary acid water cooler (63) flow into the secondary waste water tank (64) by gravity. The waste water in the secondary waste water tank (64) is pumped into the alkali washing waste water tank by the secondary alkali washing waste water pump. The tail gas generated by the secondary acid water cooler (63) enters the secondary vacuum buffer tank (67) and is pumped out by the secondary vacuum pump group. The waste gas generated by the waste acid primary preheater (21) is cooled by the concentrated acid cooler (65) and then enters the concentrated sulfuric acid tank (66) and is pumped out to the sulfuric acid transfer tank by the concentrated sulfuric acid pump.

5. The heat treatment production line and process for concentrated production of nitric acid waste according to claim 3, characterized in that: The primary vacuum pump group comprises a primary circulation condenser and a primary steam-water separator. The primary vacuum buffer tank (49) discharges water vapor which enters the primary circulation condenser for cooling and then enters the primary steam-water separator.

6. The heat treatment production line and process for concentrated production of nitric acid waste according to claim 4, characterized in that: The secondary vacuum pump group comprises a secondary circulation condenser A, a secondary circulation condenser B, a secondary circulation condenser C, a secondary circulation condenser D, a secondary steam-water separator A and a secondary steam-water separator B. The secondary vacuum buffer tank (67) discharges a portion of water vapor into the secondary circulation condenser A for cooling and then into the secondary steam-water separator A. The gas separated by the secondary steam-water separator A is cooled by the secondary circulation condenser B and then pumped into the secondary steam-water separator A again by the secondary circulation liquid pump and then discharged. The secondary vacuum buffer tank (67) discharges another portion of water vapor into the secondary circulation condenser C for cooling, and then enters the secondary steam-water separator B. The gas separated by the secondary steam-water separator B passes through the secondary circulation condenser D for cooling, and then is pumped into the secondary steam-water separator B again through the secondary circulation liquid pump, and then is discharged.

7. The heat treatment production line and process for concentrated production of nitric acid waste according to claim 3, characterized in that: The nitric acid waste acid raw material introduced into the nitric acid waste acid tank (1) is heated to 130±10°C by the waste acid primary preheater (21) and the waste acid secondary preheater (22), and then indirectly heated to 145±10°C by hot water at 200±10°C in the condensed water tank (48) through the waste acid tertiary preheater (23) and sent to the primary acid evaporator (3). The steam used in the primary acid evaporator (3) is 200±10°C and the pressure is 1.

4. The operating temperature of the entire negative pressure evaporation concentration treatment is maintained at 180±10°C and the operating pressure is maintained at 10±1 kPaA. The concentration of sulfuric acid after treatment in the primary acid evaporator (3) is 89±1%.

8. The heat treatment production line and process for concentrated production of nitric acid waste according to claim 4, characterized in that: The operating temperature of the heat transfer oil inlet of the secondary acid evaporator (5) is 250±10°C, and the operating temperature of the outlet is 230±10°C. The operating temperature of the entire negative pressure evaporation concentration treatment is maintained at 200±10°C and the operating pressure is 2±0.1 kPaA. The concentration of sulfuric acid after treatment in the secondary acid evaporator (5) is 95±1% and the temperature is 195±10°C. The waste acid secondary preheater (22) and the waste acid primary preheater (21) exchange heat with the waste acid in the mononitro waste acid tank (1) to reduce the temperature to 110±10°C. The concentrated acid cooler (65) indirectly cools the concentrated acid in the waste acid primary preheater (21) to 50±2°C through circulating water.

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