System for producing fertilizer from sulfuric acid production tail gas

Abstract

The utility model discloses a system for producing fertilizer from sulfuric acid production tail gas, and belongs to the technical field of compound fertilizer. The system comprises an ammonia water storage tank, an absorption tower, an oxidation tower, an ammonium sulfate storage tank, a fan, a chimney, a circulating pump, a concentrator, a heat exchanger, an oxidation liquid storage tank, a condenser, a first condensate water storage tank, a second condensate water storage tank and a third condensate water storage tank, wherein the absorption tower comprises a demister, an air inlet pipe, an upper overflow weir, a lower overflow weir, a first spray head, a second air inlet and a second spray head; a heating jacket is arranged outside the oxidation liquid storage tank; an inlet of the first condensate water storage tank is connected with a condensate water outlet of the condenser, and an outlet is connected with a hot water inlet of the heat exchanger; an inlet of the third condensate water storage tank is connected with a condensate water outlet of the concentrator, and an outlet of the third condensate water storage tank is connected with an inlet of the heating jacket; a cold water outlet of the heat exchanger and an outlet of the heating jacket are both connected with an inlet of the second condensate water storage tank; the second condensate water storage tank outputs in two ways, one way is connected with the upper overflow weir, and the other way is connected with the second spray head.

Description

Technical Field

[0001] The utility model belongs to the technical field of compound fertilizers, and particularly relates to a system for producing fertilizers by preparing sulfuric acid tail gas, and more particularly to the preparation of ammonium sulfate liquid fertilizer or compound fertilizer raw materials. Background Art

[0002] The production process for compound fertilizer typically involves preparing concentrated sulfuric acid from pyrite or sulfur, preparing phosphoric acid from concentrated sulfuric acid and phosphate rock, preparing ammonium phosphate from phosphoric acid and ammonia, and then preparing compound fertilizer from ammonium phosphate or directly from phosphoric acid (with ammonia). The preparation of concentrated sulfuric acid produces sulfur dioxide, which requires treatment.

[0003] In the prior art, sulfur dioxide can first react with ammonia water, then be oxidized to obtain ammonium sulfate, and finally be concentrated.

[0004] For example, the patent application number CN201610202087.X discloses a process for ammonia desulfurization of large furnace tail gas, which includes the following steps:

[0005] Step 1: SO2 absorption The flue gas from the large furnace comes into contact with the ammonia absorbent in the absorption tower, and the following reaction occurs:

[0006] NH3+H2O+SO2=NH4HSO3

[0007] 2NH3+H2O+SO2=(NH4)2SO3

[0008] 2(NH4)2SO3+H2O+SO2=2NH4HSO3

[0009] During the absorption process, ammonia is continuously added to the absorption tower;

[0010] Step 2: Oxidation: Transfer the absorption liquid in the absorption tower to the oxidation tower and add oxygen into the oxidation tower to produce the following reaction: 2(NH4)2SO3+O2=2(NH4)2SO4

[0011] 2NH4HSO3+O2=2NH4HSO4

[0012] NH4HSO4+NH3=(NH4)2SO4

[0013] During the oxidation process, oxygen is continuously added to the oxidation tower;

[0014] Step 3: Concentration and Crystallization: The oxidized absorption liquid is heated and evaporated to form a supersaturated solution. Ammonium sulfate is crystallized from the solution and filtered and dried to form ammonium sulfate. The absorption liquid is heated using waste heat from flue gas as a heat source.

[0015] Step 4: Remove the remaining dust using an electrostatic precipitator to absorb the remaining dust in the flue gas.

[0016] In this patent, the tail gas after the absorption tower treatment usually contains trace amounts of SO2 and ammonia, and usually needs to be washed with water to meet emission standards. In addition, during the oxidation process, the oxidation effect is not good at room temperature and a large amount of oxygen needs to be introduced.

[0017] For example, patent application number CN200810233595.X discloses a method for recovering sulfur dioxide from sulfuric acid tail gas in the phosphorus chemical industry. This method utilizes ammonia water, a by-product of the phosphorus chemical industry, as a desulfurizer to remove SO2 from the sulfuric acid plant's already-emitted tail gas, thereby increasing the oxidation rate of the absorption liquid's nitrite salts (containing (NH4)2SO3 and NH4HSO3) from ≥98% to ≥99.5%. The resulting ammonium sulfate solution is then used directly as a raw material for the company's compound fertilizer production. The method includes absorption, regeneration, oxidation, and concentration steps. Since the method does not produce SO2, it eliminates the need for a sulfuric acid production plant or the addition of sulfuric acid. The ammonium sulfate solution is used directly as a raw material for the company's compound fertilizer production, eliminating the need for an ammonium sulfate production plant and the construction of an accompanying ammonia plant with pressure equipment. This significantly simplifies the process flow and reduces investment. It also reduces the amount of by-product ammonia water to be processed, significantly improving economic and social benefits.

[0018] This patent has the following problems: steam needs to be introduced into the oxidation tower, which not only increases the steam consumption but also introduces water (increasing the amount of water required for subsequent concentration); the absorption tower's treatment of sulfur dioxide is unstable, with the concentration of sulfur dioxide exceeding 70 mg / m3 at some times. 3 ; Wastewater and exhaust gas are not treated. Utility Model Content

[0019] In order to solve the above problems, the embodiment of the present invention provides a system for producing fertilizer from sulfuric acid tail gas, which realizes the comprehensive utilization of heat and condensed water, is more energy-efficient; the condensed water and tail gas are treated to avoid external discharge; the concentration of sulfur dioxide in the tail gas after treatment is less than 15mg / m 3 The tail gas treatment effect is stable. The technical solution is as follows:

[0020] The embodiment of the utility model provides a system for producing fertilizer by using sulfuric acid tail gas, which includes an ammonia water storage tank, an absorption tower, an oxidation tower, an ammonium sulfate storage tank, a fan, a chimney, a circulation pump and a concentrator. The tail gas outlet of the absorption tower, the fan and the chimney are connected in sequence through pipelines; a demister is provided at the upper part of the absorption tower, the washing liquid outlet at the bottom thereof is connected to the circulation pump through a pipeline, and the ammonia water inlet at the bottom thereof is connected to the ammonia water storage tank through a pipeline; the system also includes a heat exchanger, an oxidation liquid storage tank, a condenser, a first condensate storage tank, a second The condensate storage tank and the third condensate storage tank; the absorption tower also includes an air inlet pipe, an upper overflow weir at the upper end of the air inlet pipe, a lower overflow weir at the lower part of the air inlet pipe, a first nozzle in the middle or lower part of the air inlet pipe, a second air inlet in the middle of the absorption tower and a second nozzle in the second air inlet; the air inlet pipe is arranged at the top of the absorption tower, and is arranged vertically downward, and passes through the demister downward to the middle of the absorption tower; the upper overflow weir is closed and a first air inlet is arranged on its top; the second air inlet is arranged obliquely downward from the outside to the inside, and its inner end extends into the absorption tower and Located directly above the lower overflow weir 16; the circulating pump has two outputs, one of which is connected to the cold water inlet of the heat exchanger through a pipeline, and the other is connected to the first nozzle through a pipeline; the hot water outlet of the heat exchanger, the oxidation tower, the oxidation liquid storage tank, the concentrator and the ammonium sulfate storage tank are connected in sequence through pipelines, and the tail gas outlet of the concentrator is connected to the air inlet of the condenser through a pipeline; the non-condensable gas outlet of the condenser and the tail gas outlet of the oxidation tower are both connected to the second air inlet through pipelines; a heating jacket is provided outside the oxidation liquid storage tank; The inlet of the first condensate storage tank is connected to the condensate outlet of the condenser through a pipeline, and its outlet is connected to the hot water inlet of the heat exchanger through a pipeline; the inlet of the third condensate storage tank is connected to the condensate outlet of the concentrator through a pipeline, and its outlet is connected to the inlet of the heating jacket through a pipeline; the cold water outlet of the heat exchanger and the outlet of the heating jacket are both connected to the inlet of the second condensate storage tank through pipelines; the second condensate storage tank is divided into two outputs, one is connected to the upper overflow weir through a pipeline, and the other is connected to the second nozzle through a pipeline.

[0021] Furthermore, the steam inlet of the concentrator in the embodiment of the present invention is connected to the steam network through a pipeline, and the outlet of the third condensate storage tank is also connected to the boiler of the steam network through a pipeline.

[0022] Furthermore, the system also includes a water supply tank, and the outlet of the heating jacket is connected to the inlet of the water supply tank 11 through a pipeline; the outlet of the water supply tank is divided into two outputs, one is connected to the inlet of the second condensate storage tank through a pipeline, and the other is connected to the water supply port of the cooling tower of the condenser through a pipeline.

[0023] Furthermore, a pH meter and a density meter are provided at the bottom of the absorption tower in the embodiment of the present invention, a thermometer is provided in the oxidation tower, and a density meter is provided in the concentrator.

[0024] Among them, the air inlet pipe in the embodiment of the present invention is coaxially arranged with the absorption tower, and its inner diameter is greater than or equal to 1.5m; the lower overflow weir is coaxially arranged at the lower end of the air inlet pipe.

[0025] Among them, the first nozzle in the embodiment of the present invention is coaxially arranged at the lower part of the air intake pipe, and is arranged vertically upward, which is a swirl nozzle.

[0026] Specifically, the inner diameter of the absorption tower in the embodiment of the present invention is 5-8 m, and its height is 10-18 m; the inner diameter of the air inlet pipe is 1.5-3.0 m.

[0027] The beneficial effects of the technical solution provided by the embodiment of the utility model are as follows: the system realizes the comprehensive utilization of heat and condensed water, which is more energy-efficient; the condensed water and tail gas are treated to avoid external discharge; the absorption tower is specially designed, and the concentration of sulfur dioxide in the tail gas after treatment by this patent is less than 15mg / m 3 And the exhaust gas treatment effect is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a principle block diagram of the system for producing fertilizer from sulfuric acid tail gas provided by the present invention;

[0029] Figure 2 This is a schematic structural diagram of a system for producing fertilizer from sulfuric acid tail gas provided by an embodiment of the present utility model;

[0030] Figure 3 It is a structural diagram of the absorption tower.

[0031] In the figure, 1 is an absorption tower, 2 is a heat exchanger, 3 is an oxidation tower, 4 is an oxidation liquid storage tank, 5 is a concentrator, 6 is an ammonium sulfate storage tank, 7 is a condenser, 8 is a first condensate storage tank, 9 is a third condensate storage tank, 10 is a second condensate storage tank, 11 is a water supply tank, 12 is a circulating pump, 13 is an air inlet pipe, 14 is an upper overflow weir, 15 is a first nozzle, 16 is a lower overflow weir, 17 is a demister, 18 is a second air inlet, 19 is a second nozzle, 20 is a first air inlet, 21 is an ammonia water inlet, 22 is an exhaust gas outlet, and 23 is a washing liquid outlet. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0033] Example 1

[0034] See also Figure 1-3Example 1 provides a system for producing fertilizer from sulfuric acid tail gas. The system includes an ammonia water storage tank, an absorption tower 1, an oxidation tower 3, an ammonium sulfate storage tank 6, a fan, a chimney, a circulation pump 12, a concentrator 5, a heat exchanger 2, an oxidation liquid storage tank 4, a condenser 7, a first condensate storage tank 8, a second condensate storage tank 10, a third condensate storage tank 9, and a water replenishment tank 11. The tail gas outlet 22 of the absorption tower 1, the fan, and the chimney are sequentially connected by pipelines to achieve desulfurization.

[0035] The absorption tower 1 includes a demister 17, an air inlet pipe 13, an upper overflow weir 14 at the upper outer end of the air inlet pipe 13, a lower overflow weir 16 at the lower outer end of the air inlet pipe 13, a first nozzle 15 in the middle or lower portion of the air inlet pipe 13, a second air inlet 18 in the middle of the absorption tower 1, and a second nozzle 19 within the second air inlet 18. The demister 17 is located in the upper inner portion of the absorption tower 1 and can be a wire mesh demister. A wash liquid outlet 23 at the bottom of the absorption tower 1 is connected to the circulation pump 12 via a pipeline. An ammonia inlet 21 at the bottom is connected to the ammonia storage tank via a pipeline. An exhaust gas outlet 22 is provided at the top (connected to a fan via a pipeline). The air inlet pipe 13 is located at the top of the absorption tower 1, extending vertically downward through the demister 17 to the middle of the absorption tower 1, coaxially with the absorption tower 1. The upper overflow weir 14 is closed and has a first air inlet 20 at its top. The second air inlet 18 is arranged obliquely downward from the outside to the inside, with its inner end extending into the absorption tower 1 and located just above the lower overflow weir 16 , and sucking in the gas discharged from the oxidation tower 3 and the concentrator 5 with negative pressure.

[0036] The circulating pump 12 has two output paths: one connected to the cold water inlet of the heat exchanger 2 via a pipeline, and the other connected to the first nozzle 15 via a pipeline. The hot water outlet of the heat exchanger 2, the oxidation tower 3 (specifically, the overflow output), the oxidizing liquid storage tank 4, the concentrator 5, and the ammonium sulfate storage tank 6 are sequentially connected via pipelines. The exhaust gas outlet of the concentrator 5 is connected to the air inlet of the condenser 7 via a pipeline, and its steam inlet is connected to the steam network via a pipeline. The heat exchanger 2 is a conventional plate heat exchanger, a shell-and-tube heat exchanger, or a heating tank, preferably a closed container. The concentrator 5 is a concentrating tank equipped with a steam heater. The non-condensable gas outlet of the condenser 7 and the exhaust gas outlet of the oxidation tower 3 are both connected to the second air inlet 18 via pipelines. The oxidizing liquid storage tank 4 is equipped with a heating jacket. The inlet of the first condensate storage tank 8 is connected to the condensate outlet of the condenser 7 via a pipeline, and its outlet is connected to the hot water inlet of the heat exchanger 2 via a pipeline. The inlet of the third condensate storage tank 9 is connected to the condensate outlet of the concentrator 5 via a pipeline. The outlet of the third condensate storage tank 9 is divided into two output paths: one is connected to the inlet of the heating jacket via a pipeline, and the other is connected to the boiler of the steam network via a pipeline. The cold water outlet of the heat exchanger 2 is connected to the inlet of the second condensate storage tank 10 via a pipeline; the outlets of the heating jacket are both connected to the make-up water tank 11 via pipelines. The outlet of the make-up water tank 11 is divided into two output paths: one is connected to the inlet of the second condensate storage tank 10 via a pipeline, and the other is connected to the make-up water port of the cooling tower of the condenser 7 via a pipeline. The second condensate storage tank 10 has two output paths: one is connected to the upper overflow weir 14 via a pipeline, and the other is connected to the second nozzle 19 via a pipeline.

[0037] Furthermore, in the embodiment of the present invention, a pH meter and a density meter are provided at the bottom of the absorption tower 1, a thermometer is provided in the oxidation tower 3, and a density meter is provided in the concentrator 5, so as to control the production process.

[0038] The inner diameter of the air intake pipe 13 in the embodiment of the present invention is greater than or equal to 1.5 m.

[0039] Specifically, the lower overflow weir 16 in the embodiment of the present invention is coaxially arranged at the lower end of the air inlet pipe 13 .

[0040] The first nozzle 15 in the embodiment of the present invention is coaxially arranged at the lower inner portion of the air inlet pipe 13 and is arranged vertically upwards, and is a swirl nozzle.

[0041] Specifically, the absorption tower 1 in the embodiment of the present invention has an inner diameter of 5-8 m and a height of 10-18 m. The inner diameter of the air inlet pipe 13 is 1.5-3.0 m.

[0042] Example 2

[0043] Example 2 provides a system for producing fertilizer from sulfuric acid tail gas, the structure of which is basically the same as that of Example 1. The inner diameter of the absorption tower 1 is 6m and its height is 10m. The inner diameter of the air inlet pipe 13 is 1.8m. The inner diameter of the oxidation tower 3 is 3.5m and its height is 10m. The diameter of the concentrator 5 is 2m and the heat exchange area is 32m. 2 The heat exchange area of ​​heat exchanger 2 is 25m 2 The heat exchange area of ​​condenser 7 is 60m 2 The volume of ammonium sulfate storage tank 6 is 50m 3 The volume of the third condensate storage tank 9 is 5m 3 The capacity of the first condensate storage tank 8, the second condensate storage tank 10 and the water supply tank 11 is 3m 3 .

[0044] The air flow rate of the first air inlet 20 is 1.5*10 5 m 3 / h, the temperature is about 72℃, and the concentration of sulfur dioxide is 540-590mg / m 3 The concentration of sulfur dioxide at the tail gas outlet 22 is 12.9 mg / m 3 About (92-day average, highest 14.3 mg / m 3 ), the temperature is 31 ° C. The concentration of ammonium sulfate in the ammonium sulfate storage tank 6 is 38-44wt%, and the density is 1.18-1.21g / cm 3 , with a sub-salt content of less than 0.1wt%. The temperature of the liquid at the hot water outlet of heat exchanger 2 is 45-60°C, and the reaction temperature of oxidation tower 3 is 42-55°C. The temperature of the wash liquid output from wash liquid outlet 23 is 33-35°C. The temperature of the condensed water (clean condensed water) output from concentrator 5 is greater than 80°C, and the temperature of the condensed water (non-clean condensed water) output from condenser 7 is greater than 60°C.

[0045] The terms "first," "second," and "third" in this patent are used only to distinguish and have no other special meaning. Pumps, valves, flow meters, etc. may be installed on the pipelines in this patent as needed.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A system for producing fertilizer from sulfuric acid tail gas, comprising an ammonia water storage tank, an absorption tower (1), an oxidation tower (3), an ammonium sulfate storage tank (6), a blower, a chimney, a circulation pump (12) and a concentrator (5), wherein the tail gas outlet (22) of the absorption tower (1), the blower and the chimney are sequentially connected through pipelines; a demister (17) is provided in the upper part of the absorption tower (1), a washing liquid outlet (23) at the bottom thereof is connected to the circulation pump (12) through a pipeline, and an ammonia water inlet (21) at the bottom thereof is connected to the ammonia water storage tank through a pipeline; and the system is characterized in that: The system further comprises a heat exchanger (2), an oxidizing liquid storage tank (4), a condenser (7), a first condensate storage tank (8), a second condensate storage tank (10) and a third condensate storage tank (9); The absorption tower (1) further comprises an air inlet pipe (13), an upper overflow weir (14) at the outer upper end of the air inlet pipe (13), a lower overflow weir (16) at the outer lower part of the air inlet pipe (13), a first nozzle (15) at the middle or lower part of the air inlet pipe (13), a second air inlet (18) at the middle of the absorption tower (1), and a second nozzle (19) inside the second air inlet (18); the air inlet pipe (13) is arranged at the top of the absorption tower (1), is arranged vertically downward, and passes through the demister (17) downward to the middle of the absorption tower (1); the upper overflow weir (14) is closed and a first air inlet (20) is provided at its top; the second air inlet (18) is arranged obliquely downward from the outside to the inside, and its inner end extends into the absorption tower (1) and is located directly above the lower overflow weir (16); The circulating pump (12) is divided into two output paths, one path is connected to the cold water inlet of the heat exchanger (2) through a pipeline, and the other path is connected to the first nozzle (15) through a pipeline; the hot water outlet of the heat exchanger (2), the oxidation tower (3), the oxidation liquid storage tank (4), the concentrator (5) and the ammonium sulfate storage tank (6) are connected in sequence through pipelines, and the tail gas outlet of the concentrator (5) is connected to the air inlet of the condenser (7) through a pipeline; the non-condensable gas outlet of the condenser (7) and the tail gas outlet of the oxidation tower (3) are both connected to the second air inlet (18) through pipelines; The oxidation liquid storage tank (4) is provided with a heating jacket outside; the inlet of the first condensate storage tank (8) is connected to the condensate outlet of the condenser (7) through a pipeline, and its outlet is connected to the hot water inlet of the heat exchanger (2) through a pipeline; the inlet of the third condensate storage tank (9) is connected to the condensate outlet of the concentrator (5) through a pipeline, and its outlet is connected to the inlet of the heating jacket through a pipeline; the cold water outlet of the heat exchanger (2) and the outlet of the heating jacket are both connected to the inlet of the second condensate storage tank (10) through a pipeline; the second condensate storage tank (10) is output in two ways, one way is connected to the upper overflow weir (14) through a pipeline, and the other way is connected to the second nozzle (19) through a pipeline.

2. The system for producing fertilizer from sulfuric acid tail gas according to claim 1, characterized in that: The steam inlet of the concentrator (5) is connected to the steam network through a pipeline, and the outlet of the third condensate storage tank (9) is also connected to the boiler of the steam network through a pipeline.

3. The system for producing fertilizer from sulfuric acid tail gas according to claim 1, characterized in that: The system also includes a water supply tank (11), the outlet of the heating jacket is connected to the inlet of the water supply tank (11) through a pipeline; the outlet of the water supply tank (11) is divided into two outputs, one of which is connected to the inlet of the second condensate storage tank (10) through a pipeline, and the other is connected to the water supply port of the cooling tower of the condenser (7) through a pipeline.

4. The system for producing fertilizer from sulfuric acid tail gas according to claim 1, characterized in that: A pH meter and a density meter are provided at the bottom of the absorption tower (1), a thermometer is provided in the oxidation tower (3), and a density meter is provided in the concentrator (5).

5. The system for producing fertilizer from sulfuric acid tail gas according to claim 1, characterized in that: The air inlet pipe (13) is coaxially arranged with the absorption tower (1), and its inner diameter is greater than or equal to 1.5 m; the lower overflow weir (16) is coaxially arranged at the lower end of the air inlet pipe (13).

6. The system for producing fertilizer from sulfuric acid tail gas according to claim 1, characterized in that: The first nozzle (15) is coaxially arranged at the lower inner part of the air inlet pipe (13), and is arranged vertically upwards, and is a swirl nozzle.

7. The system for producing fertilizer from sulfuric acid tail gas according to claim 1, characterized in that: The inner diameter of the absorption tower (1) is 5-8 m, and its height is 10-18 m; the inner diameter of the air inlet pipe (13) is 1.5-3.0 m.

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