Sulfuric acid process phosphoric acid production system

Abstract

The utility model relates to a sulfuric acid process phosphoric acid production system. The device comprises a phosphoric acid production unit, an ardealite cracking unit and a wet-process sulfuric acid preparation unit, the phosphoric acid production unit comprises a reaction device and a filtering device; the reaction device is provided with a mixed feed port and a reaction discharge port; the filtering device is provided with a reaction feed port, a solid discharge port and a liquid discharge port; the ardealite cracking unit comprises a calcining device; the calcining device is provided with a raw material feeding hole, a clinker discharging hole and a coarse flue gas discharging hole; the wet sulfuric acid preparation unit comprises a flue gas reaction device and an acid cooling device; the flue gas reaction device is provided with a reaction gas feeding hole and an acid gas discharging hole; and the acid cooling device is provided with an acid gas feed port, a sulfuric acid discharge port and a tail gas discharge port. According to the utility model, sulfur circulation production is realized, solid wastes are hardly generated, clean production is realized, and good economic benefits are brought.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of sulphuric acid method phosphoric acid production system. BACKGROUND

[0002] Phosphogypsum is the biggest problem in sulphuric acid method phosphoric acid production, because the production amount of phosphogypsum is too large, taking 300,000 tons / year phosphoric acid plant as an example (100% P2O5), about 1.4 million tons of phosphogypsum is produced annually, which is a huge waste disposal task, and the phosphogypsum contains pollutants, which has a great destructive power to the environment, especially the pollution to groundwater is very serious, and the treatment cost is high. In addition, the sulfur in phosphogypsum is not utilized, which is also a waste of resources and the cost of sulfur purchase.

[0003] The production of cement by using phosphogypsum to produce sulfuric acid has been actively researched by German scientists as early as 1847, and in 1969, a 200-ton-per-day cement plant was built in the osw. KRUP factory of Linz Company in Austria. This process is that phosphogypsum is dried and dehydrated, and then mixed with coke, clay, sand, etc. according to the required proportion of CaO, SiO2, Al2O3, and Fe2O3, and then calcined in a hollow rotary kiln to form cement clinker. SO2 in the kiln gas is converted and absorbed to produce sulfuric acid.

[0004] China has started the research on the production of cement by using phosphogypsum to produce sulfuric acid since the 1950s, and made a major breakthrough in industrial production in the late 1980s. During this period, seven sets of phosphogypsum sulfuric acid cement production devices were built, which are referred to as the "46" project. After nearly 20 years of production practice, it has been proved that this process is technically feasible. However, the proportion of sulfuric acid produced by using phosphogypsum is still less than 1% of the total sulfuric acid production, the main reason being: high energy consumption, easy scarring of rotary kiln, incomplete decomposition of CaSO4, and low conversion rate.

[0005] The high energy consumption is mainly the consumption of fuel coal. When drying phosphogypsum, 1 ton of clinker requires about 123 kg of coal (5500 kcal / kg) to dry the gypsum; when calcining raw materials to produce cement clinker, 1 ton of clinker consumes about 300 kg of coal (5800 kcal / kg). In order to reduce the sensible heat carried away by the kiln gas, a five-stage raw material preheater is currently installed at the tail of the rotary kiln, the heat consumption of clinker is reduced by 15%-20%, the sensible heat of kiln gas accounts for 22% of the heat consumption of burning, the temperature of the kiln gas is reduced from 800℃ to 450℃, and the thermal efficiency of the rotary kiln is increased to 45%-50%. The heat consumption is still large, which not only increases the cost of cement, but also reduces the concentration of SO2 in the kiln gas due to the large amount of kiln gas, which increases the power consumption of the sulfuric acid production system and the cost of sulfuric acid production.

[0006] In the process of using kiln gas of phosphogypsum calcination to produce sulfuric acid, due to the low SO2 concentration of the kiln gas, the current domestic phosphogypsum sulfuric acid production device adopts a one-time conversion and adds ammonia absorption tail gas process. Since the kiln gas contains CO, C n H m and NO x , it may affect the conversion of SO2 and the absorption operation of SO3, resulting in a decrease in absorption rate, a decrease in product acid quality, an increase in acid mist generation, an adverse effect on ammonia absorption tail gas SO2, a large amount of emission tail gas mist, and poor environmental conditions. SO3 also affects the ammonia absorption operation and the quality of ammonium sulfite.

[0007] The annual amount of phosphogypsum waste in China is 25-30 million tons (dry basis). The production of sulfuric acid from phosphogypsum not only makes up for the lack of sulfuric acid raw materials in China, but also has great significance for areas that lack sulfuric acid raw materials and have phosphogypsum. It also solves the problems of land occupation and environmental pollution caused by phosphogypsum, and has significant benefits. With the development of wet-process phosphoric acid in China and the increasing emphasis on environmental protection, how to reasonably utilize existing waste resources will become a new driving force for the study of phosphogypsum acid production.

[0008] Some places have applied advanced cement production technology to phosphogypsum treatment, especially the use of kiln external decomposition technology in cement production, which avoids the influence of the reduction state in the rotary kiln on cement production, and the decomposition of phosphogypsum is more complete in the reduction state outside the kiln. However, there is still a problem of low SO2 content in the kiln gas, which is not conducive to acid production. Some reports add sulfur steam to the kiln or external decomposition system: on the one hand, it solves the problem of low SO2 content in the kiln gas, and on the other hand, it provides a reducing agent, and the conversion is changed from one conversion and one absorption to two conversions and two absorptions. There are also reports that the kiln tail gas is combined with sulfuric acid furnace gas after washing and purification treatment to produce acid. Each method has its own advantages, but there is still a problem of water affecting the catalyst in the conversion process. Practical new type content

[0009] The technical problem to be solved by the present utility model is to overcome the low utilization rate of product phosphogypsum in the existing sulfuric acid method phosphoric acid production process, and to provide a sulfuric acid method phosphoric acid production system, which realizes sulfur cycle production, almost does not produce solid waste, realizes clean production, and brings good economic benefits.

[0010] The present utility model solves the above technical problems by the following technical solutions:

[0011] The present utility model provides a sulfuric acid method phosphoric acid production system, which comprises a phosphoric acid production unit, a phosphogypsum cracking unit, and a wet-process sulfuric acid unit.

[0012] The phosphoric acid production unit comprises a reaction device and a filtering device; the reaction device is provided with a mixed feed inlet and a reaction discharge outlet; the filtering device is provided with a reaction feed inlet, a solid discharge outlet and a liquid discharge outlet;

[0013] The phosphogypsum cracking unit comprises a calcining device; the calcining device is provided with a raw material feed inlet, a clinker discharge outlet and a crude flue gas discharge outlet;

[0014] The wet-process sulfuric acid unit comprises a flue gas reaction device and an acid cooling device; the flue gas reaction device is provided with a reaction gas feed inlet and an acid gas discharge outlet; the acid cooling device is provided with an acid gas feed inlet, a sulfuric acid discharge outlet and a tail gas discharge outlet;

[0015] The mixed feed inlet is connected with a phosphorite source and a water source; the reaction discharge outlet is connected with the reaction feed inlet; the solid discharge outlet is connected with the raw material feed inlet; the crude flue gas discharge outlet is connected with the reaction gas feed inlet; the reaction gas feed inlet is connected with an air source and a fuel gas source; the acid gas discharge outlet is connected with the acid gas feed inlet; and the sulfuric acid discharge outlet is connected with the mixed feed inlet.

[0016] In the utility model, the phosphoric acid production unit further comprises a raw material mixing device, and the raw material mixing device is provided with a water feed inlet, a phosphorite feed inlet and a mixed discharge outlet; and the mixed discharge outlet is connected with the mixed feed inlet.

[0017] The raw material mixing device is further provided with an acidic water feed inlet; the wet-process sulfuric acid unit further comprises a flue gas pretreatment device, and the flue gas pretreatment device is provided with a crude flue gas feed inlet, an acidic water discharge outlet and a flue gas discharge outlet; the crude flue gas discharge outlet is connected with the crude flue gas feed inlet; the acidic water discharge outlet is connected with the acidic water feed inlet; and the flue gas discharge outlet is connected with the reaction gas feed inlet.

[0018] In the utility model, the reaction device is further provided with a circulation outlet and a circulation inlet, the circulation outlet and the circulation inlet are connected through a circulation pipeline outside the reaction device, and a cooling device is arranged on the circulation pipeline.

[0019] In the utility model, the reaction device is further provided with a tail gas outlet, and the tail gas outlet is connected with a tail gas treatment device.

[0020] In the utility model, the phosphoric acid production unit further comprises a concentration device; the concentration device is provided with a liquid feed inlet, a jacket, a fluosilicic acid discharge outlet and a phosphoric acid discharge outlet; and the jacket is provided with a steam inlet and a condensed water outlet.

[0021] The flue gas reaction device is further provided with a boiler water inlet and a steam outlet; and the steam outlet is connected with the steam inlet.

[0022] The phosphogypsum cracking unit further comprises a drying device, the drying device is provided with a phosphogypsum feeding port, a hot air inlet and a dry material outlet; the solid outlet is connected with the phosphogypsum feeding port; and the dry material outlet is connected with the raw material feeding port.

[0023] The phosphogypsum cracking unit further comprises a mixing device, the mixing device is provided with an auxiliary material feeding port, a dry material feeding port and a raw material outlet; the dry material outlet is connected with the dry material feeding port; and the raw material outlet is connected with the raw material feeding port.

[0024] The acid cooling device is further provided with a jacket, the jacket is provided with a cold air inlet and a hot air outlet; and the hot air outlet is connected with the hot air inlet.

[0025] The wet-process sulfuric acid unit further comprises a tail gas treatment device, the tail gas treatment device is provided with a tail gas feeding port, a treatment agent feeding port and a dilute sulfuric acid outlet; the tail gas outlet is connected with the tail gas feeding port, the treatment agent feeding port is connected with a hydrogen peroxide source, and the dilute sulfuric acid outlet is connected with the mixing feeding port.

[0026] The positive progress effect of the utility model lies in:

[0027] (1) In the utility model, the sulfuric acid product converted from flue gas can be used for dissolving phosphorite, completing the closed loop of sulfur resource recycling and recycling, and saving the consumption of purchased sulfuric acid;

[0028] (2) The utility model uses a wet-process sulfuric acid process, reduces the flue gas drying process link, removes the drying tower, the first absorption tower, the second absorption tower, the acid circulating pump and other equipment to reduce investment; and the wet-process sulfuric acid process can also fully utilize the heat generated in the production process;

[0029] (3) The utility model adopts an air cooling mode, 90% of the heat of the 180-200 DEG C hot air condensed and heated by sulfuric acid vapor can be recycled and used for drying before phosphogypsum calcination, so that the moisture content of about 20% wet dihydrate phosphogypsum is converted into hemihydrate gypsum, and the consumption of a large amount of additional fuel is saved;

[0030] (4) In the utility model, 0.3-0.8 tons of low-pressure saturated steam can be by-produced for each ton of concentrated sulfuric acid produced, which can be sent to a phosphoric acid concentration process to provide most of the heat and reduce the use amount of coal and other fuels; and the steam can also be used as a public project;

[0031] (5) The utility model discloses a tail gas washing adopts hydrogen peroxide, and the dilute sulfuric acid produced after washing can be used for the decomposition of phosphorite and water supplement, which saves fresh water supplement and reduces the consumption of raw material sulfuric acid; the acidic water produced by the flue gas pretreatment device can be used as filter cake washing water or tail gas washing water in the production process of phosphoric acid, which saves the amount of fresh water supplement;

[0032] (6) The utility model discloses a flue gas containing moisture, which affects the acid production problem of phosphogypsum acid-cogeneration cement; the problem of mutual restraint of phosphogypsum acid production and cement clinker calcination due to tail gas SO2 content is solved; the overall heat recovery rate is high, the equipment is less, the economy is reasonable, and the investment return rate is high.

[0033] (7) The utility model discloses a phosphogypsum, fully utilize sulfur resources, with the aid of wet-process sulfuric acid process, complete the phosphogypsum green resource of phosphoric acid production process closed loop, solve the problem of traditional dry-process sulfuric acid process low concentration SO2 acid heat balance, while the byproduct can beneficially supplement the demand of phosphoric acid, phosphogypsum section.

[0034] (8) The utility model discloses a phosphogypsum calcination and then batching and grinding cement, and flue gas recovery production sulfuric acid, which can solve the problem of phosphogypsum treatment, produce sulfuric acid and byproduct cement product, realize environmental protection benefit and economic benefit. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is the schematic diagram of sulfuric acid method phosphoric acid production system in example 1;

[0036] Figure 2 It is the detailed view of wet-process sulfuric acid unit in example 1;

[0037] The label shown in the figure: phosphoric acid production unit 1, raw material mixing device 11, reaction device 12, tail gas treatment device 121, cooling device 122, filter device 13, concentration device 14, phosphogypsum cracking unit 2, drying device 21, mixing device 22, calcining device 23, wet-process sulfuric acid unit 3, flue gas pretreatment device 31, flue gas reaction device 32, acid cooling device 33, tail gas treatment device 34;

[0038] Cooling fan C-601, flue gas fan C-602, air fan C-603, packing tower cooler E-601, flue gas heater E-602, first interstage heat exchanger E-603, second interstage heat exchanger E-604, first process cooler E-605, second process cooler E-606 sulfuric acid steam condenser E-607, sulfuric acid water cooler E-608;

[0039] Hot air furnace F-601, filter press M-602, power wave circulating pump P-601, filler tower circulating pump P-603, hydrogen peroxide pump P-607, sulfuric acid circulating pump P-609, one bed R-602, two beds R-603, three beds R-604;

[0040] Power wave washing tower T-601, filler tower T-602, degassing tower T-605, tail gas washing tower T-606, inclined tube settling tank V-601, steam drum V-603, sulfuric acid mixing tank V-604, hydrogen peroxide tank V-605, electric demister X-601, second electric demister X-603, exhaust cylinder X-604. DETAILED DESCRIPTION

[0041] A preferred embodiment is described below, and the utility model is more clearly and completely illustrated in conjunction with the drawings.

[0042] Example 1

[0043] A sulfuric acid method phosphoric acid production system, such as Figure 1 , comprising a phosphoric acid production unit 1, a phosphogypsum cracking unit 2 and a wet-process sulfuric acid unit 3.

[0044] In this embodiment, the phosphoric acid production unit 1 comprises a raw material mixing device 11, a reaction device 12, a filtering device 13 and a concentration device 14. The raw material mixing device 11 is provided with a water feed inlet, a phosphate rock feed inlet, an acid water feed inlet and a mixed feed outlet. The reaction device 12 is provided with a mixed feed inlet, a circulating outlet, a circulating inlet, a tail gas outlet and a reaction feed outlet; the circulating outlet and the circulating inlet are connected by a circulating pipeline outside the reaction device 12, and the circulating pipeline is provided with a cooling device 122, and the tail gas outlet is connected with a tail gas treatment device 121. The filtering device 13 is provided with a reaction feed inlet, a solid feed outlet and a liquid feed outlet. The concentration device 14 is provided with a liquid feed inlet, a jacket, a fluosilicic acid feed outlet and a phosphoric acid feed outlet; the jacket is provided with a steam inlet and a condensed water outlet.

[0045] In this embodiment, the phosphogypsum cracking unit 2 comprises a drying device 21, a mixing device 22 and a calcining device 23. The drying device 21 is provided with a phosphogypsum feed inlet, a hot air inlet and a dry feed outlet. The mixing device 22 is provided with an auxiliary material feed inlet, a dry feed inlet and a raw material feed outlet. The calcining device 23 is provided with a raw material feed inlet, a clinker feed outlet and a crude flue gas feed outlet; the clinker feed outlet is connected with a cement finished product device.

[0046] In this embodiment, the wet-process sulfuric acid unit 3 comprises a flue gas pretreatment device 31, a flue gas reaction device 32, an acid cooling device 33, and a tail gas treatment device 34. The flue gas pretreatment device 31 is provided with a crude flue gas inlet, an acidic water outlet, and a flue gas outlet. The flue gas reaction device 32 is provided with a boiler water inlet, a reaction gas inlet, a steam outlet, and an acid gas outlet. The acid cooling device 33 is provided with an acid gas inlet, a jacket, a sulfuric acid outlet, and a tail gas outlet, and the jacket is provided with a cold air inlet and a hot air outlet. The tail gas treatment device 34 is provided with a tail gas inlet, a treatment agent inlet, and a dilute sulfuric acid outlet.

[0047] In this embodiment, the mixing outlet of the raw material mixing device 11 is connected to the mixing inlet of the reaction device 12, the reaction outlet of the reaction device 12 is connected to the reaction inlet of the filtration device 13, and the solid outlet of the filtration device 13 is connected to the phosphogypsum inlet of the drying device 21. The dry material outlet of the drying device 21 is connected to the dry material inlet of the mixing device 22, the raw material outlet of the mixing device 22 is connected to the raw material inlet of the calcination device 23, and the flue gas outlet of the calcination device 23 is connected to the crude flue gas inlet of the flue gas pretreatment device 31.

[0048] In this embodiment, the phosphoric acid production unit 1 involves a mature phosphoric acid process and a mature cement production process involved in the phosphogypsum cracking unit 2. The general process is as follows: phosphate ore is formed into phosphate slurry by the raw material mixing device 11, the phosphate slurry is reacted with sulfuric acid in the reaction device 12, the reacted slurry is sent to the filtration device 13 for solid-liquid separation, the obtained solid is phosphogypsum, and the obtained liquid is dilute phosphoric acid. The dilute phosphoric acid is concentrated into concentrated phosphoric acid product in the concentration device 14, and the gas containing silicon tetrafluoride released during the concentration process is recycled and absorbed to become fluorosilicic acid product. The phosphogypsum is sent to the phosphogypsum cracking unit 2, and is sequentially dried in the drying device 21, mixed with auxiliary materials such as coke, clay, and kiln dust in the mixing device 22, and then calcined in the calcination device 23 to form flue gas and cement. The flue gas is sent to the wet-process sulfuric acid unit 3 to produce sulfuric acid.

[0049] In this embodiment, as shown in FIG. 1, the phosphoric acid production unit 1 comprises a raw material mixing device 11, a reaction device 12, a filtration device 13, a concentration device 14, a drying device 21, a mixing device 22, a calcination device 23, a flue gas pretreatment device 31, a flue gas reaction device 32, an acid cooling device 33, and a tail gas treatment device 34. Figure 2The acid water outlet of the flue gas pretreatment device 31 is connected to the acid water inlet of the raw material mixing device 11, the flue gas outlet of the flue gas pretreatment device 31 is connected to the reaction gas inlet of the flue gas reaction device 32, the reaction gas inlet of the flue gas reaction device 32 is also connected to the air source and the fuel gas source, the steam outlet of the flue gas reaction device 32 is connected to the steam inlet of the concentration device 14, the acid gas outlet of the flue gas reaction device 32 is connected to the acid gas inlet of the acid cooling device 33, the hot air outlet of the acid cooling device 33 is connected to the hot air inlet of the drying device 21, the sulfuric acid outlet of the acid cooling device 33 is connected to the mixed inlet of the reaction device 12, the tail gas outlet of the acid cooling device 33 is connected to the tail gas inlet of the tail gas treatment device 34, the treatment agent inlet of the tail gas treatment device 34 is connected to the water source and the hydrogen peroxide source, the concentration of the hydrogen peroxide is 27.5wt%, and the dilute sulfuric acid outlet of the tail gas treatment device 34 is connected to the mixed inlet of the reaction device 12.

[0050] In the embodiment, the flue gas pretreatment device 31 specifically includes a flue gas heater E-602, a dynamic wave washing tower T-601, a packed tower T-602, a degassing tower T-605, and an inclined pipe settling tank V-601. The flue gas heater E-602 is provided with a tube side hot flue gas inlet, a tube side hot flue gas outlet, a shell side hot flue gas inlet, and a shell side hot flue gas outlet. The tube side hot flue gas inlet serves as the crude flue gas inlet of the flue gas pretreatment device 31, and the shell side hot flue gas outlet serves as the flue gas outlet of the flue gas pretreatment device 31. The dynamic wave washing tower T-601 is filled with washing liquid, and is provided with a first flue gas inlet, a first flue gas outlet, a circulating washing liquid outlet, a circulating washing liquid inlet, and a supplementary washing liquid inlet. The circulating washing liquid outlet and the circulating washing liquid inlet are connected by a circulating pipeline outside the dynamic wave washing tower T-601, the circulating pipeline is provided with a dynamic wave circulating pump P-601, and the circulating pipeline is provided with a settling liquid opening. The packed tower T-602 is filled with absorption liquid, and is provided with a second flue gas inlet, a second flue gas outlet, a circulating absorption liquid outlet, and a circulating absorption liquid inlet. The circulating absorption liquid outlet and the circulating absorption liquid inlet are connected by a second circulating pipeline outside the packed tower T-602, the second circulating pipeline is provided with a packed tower circulating pump P-603 and a packed tower cooler E-601, and the second circulating pipeline is provided with a supplementary liquid outlet. The inclined pipe settling tank V-601 is provided with a settling liquid inlet, a clear liquid outlet, and an acid sludge outlet, the acid sludge outlet is connected to a filter press M-602. The degassing tower T-605 is provided with a clear liquid inlet, an air inlet, a flue gas outlet, a circulating acid water outlet, and a circulating acid water inlet, the circulating acid water outlet and the circulating acid water inlet are connected by a third circulating pipeline outside the degassing tower T-605, the third circulating pipeline is provided with an acid water outlet, which serves as the acid water outlet of the flue gas pretreatment device 31.

[0051] In this embodiment, the hot flue gas outlet of the flue gas heater E-602 is connected with the first flue gas inlet of the dynamic wave scrubbing tower T-601, the first flue gas outlet of the dynamic wave scrubbing tower T-601 is connected with the second flue gas inlet of the packed tower T-602 through a first flue gas pipeline, the second flue gas outlet of the packed tower T-602 is connected with the shell side hot flue gas inlet of the flue gas heater E-602 through a second flue gas pipeline, and an electric demister X-601 is arranged on the second flue gas pipeline. The make-up liquid outlet on the second circulating pipeline outside the packed tower T-602 is connected with the make-up scrubbing liquid inlet of the dynamic wave scrubbing tower T-601, the sedimentation liquid opening on the circulating pipeline outside the dynamic wave scrubbing tower T-601 is connected with the sedimentation liquid feeding inlet of the inclined pipe sedimentation tank V-601, the clear liquid outlet of the inclined pipe sedimentation tank V-601 is connected with the clear liquid feeding inlet of the degassing tower T-605, and the flue gas outlet of the degassing tower T-605 is connected with the first flue gas pipeline. The flue gas at 320℃ from the phosphogypsum cracking unit 2 is cooled by the flue gas heater E-602, and then sequentially passes through the dynamic wave scrubbing tower T-601 and the packed tower T-602 to remove impurities, and then enters the flue gas heater E-602 again for heat exchange, and the purified scrubbing acidic water is sent to the phosphoric acid production unit 1.

[0052] In this embodiment, as Figure 2The flue gas reaction device 32 specifically comprises a hot blast furnace F-601, a reactor, a second process cooler E-606, and a steam drum V-603. The hot blast furnace F-601 is provided with a flue gas inlet, a fuel gas mixture inlet, and a reaction gas outlet. The flue gas inlet of the hot blast furnace F-601 is connected with the shell-side hot flue gas outlet of the flue gas heater E-602 through a third flue gas pipeline, and the third flue gas pipeline is provided with a flue gas fan C-602. The fuel gas mixture inlet is connected with a fuel gas source. In the present embodiment, the fuel gas is natural gas, and in other embodiments, other combustible gases with a higher calorific value than 1000 kcal can be selected. The fuel gas mixture inlet is connected with an air source through an air pipeline, and the air pipeline is provided with an air fan C-603. The reactor comprises, from top to bottom, a first bed R-602, a first inter-bed heat exchanger E-603, a second bed R-603, a second inter-bed heat exchanger E-604, a third bed R-604, and a first process cooler E-605. The first process cooler E-605, the second inter-bed heat exchanger E-604, and the first inter-bed heat exchanger E-603 are respectively provided with a tube-side cold gas inlet and a tube-side hot gas outlet. The reactor is provided with a reaction gas inlet, which is the reaction gas inlet of the flue gas reaction device 32, and an acid gas outlet, which is the acid gas outlet of the flue gas reaction device 32. The second process cooler E-606 is provided with a shell-side acid gas inlet, a shell-side acid gas outlet, a tube-side cold water inlet, and a tube-side hot water outlet. The steam drum V-603 is provided with a boiler water inlet, which is the boiler water inlet of the flue gas reaction device 32, a steam outlet, which is the steam outlet of the flue gas reaction device 32, a circulating water outlet, a circulating water inlet, and a blowdown port. The reaction gas outlet of the hot blast furnace F-601 is connected with the tube-side cold gas inlet of the first process cooler E-605, and the acid gas outlet of the reactor is connected with the shell-side acid gas inlet of the second process cooler E-606.

[0053] In this embodiment, the flue gas purified and heated by the flue gas pretreatment device 31 does not need to be dried and directly enters the flue gas blower C-602 for pressurization. The pressurized flue gas is mixed in the hot blast furnace F-601. The reaction gas flowing out of the reaction gas outlet of the hot blast furnace F-601 is preheated to 400°C by passing sequentially through the first process cooler E-605 and the first interstage heat exchanger E-603, or sequentially through the second interstage heat exchanger E-604 and the first interstage heat exchanger E-603. Then, the reaction gas enters the reactor from the reaction gas inlet and passes sequentially through a bed R-602 and the first interstage heat exchanger. The reaction and heat exchange of heat exchangers E-603, R-603 (second bed), E-604 (second interstage heat exchanger), R-604 (third bed), and E-605 (first process cooler) catalytically oxidize SO2 into SO3. The resulting acid gas flows out from the acid gas outlet and exchanges heat with boiler feedwater in the second process cooler E-606 before being sent to the acid cooling unit 33. After heat exchange in the process gas cooler E-606, the boiler feedwater generates saturated steam at 5.5 MPa and 289.16 °C. After steam-water separation in the steam drum V-603, the steam is sent to the phosphoric acid production unit 1.

[0054] In this embodiment, as Figure 2 The acid cooling unit 33 specifically includes a sulfuric acid vapor condenser E-607 and a sulfuric acid mixing tank V-604. The sulfuric acid vapor condenser E-607 has an acid gas inlet, serving as the acid gas inlet for the acid cooling unit 33; a tail gas outlet, serving as the tail gas outlet for the acid cooling unit 33; and a hot sulfuric acid outlet. It also has a jacket with a cold air inlet and a hot air outlet, serving as the cold air inlet and hot air outlet for the acid cooling unit 33, respectively. The cold air inlet is connected to an air source via an air pipeline, on which a cooling fan C-601 is installed. The sulfuric acid mixing tank V-604 has a hot sulfuric acid inlet and a circulating sulfuric acid outlet, connected via a circulating sulfuric acid pipeline. The circulating sulfuric acid pipeline is equipped with a sulfuric acid circulating pump P-609 and a sulfuric acid water cooler E-608. The circulating sulfuric acid pipeline also has a sulfuric acid outlet, serving as the sulfuric acid outlet for the acid cooling unit 33.

[0055] In this embodiment, the acid gas inlet of the sulfuric acid vapor condenser E-607 is connected to the shell-side acid gas outlet of the second process cooler E-606, and the hot sulfuric acid outlet of the sulfuric acid vapor condenser E-607 is connected to the hot sulfuric acid inlet of the sulfuric acid mixing tank V-604. In this embodiment, the cold air sent to the sulfuric acid vapor condenser E-607 is heated to 200°C after heat exchange in the sulfuric acid vapor condenser E-607 and then sent to the phosphogypsum cracking unit 2. The acid gas exchanges heat with the air in the sulfuric acid vapor condenser E-607 to lower its temperature. The resulting hot sulfuric acid is then cooled by circulating mixing with cold sulfuric acid in the sulfuric acid mixing tank V-604 to obtain concentrated sulfuric acid at 40.0°C, which is then sent to the phosphoric acid production unit 1.

[0056] In this embodiment, as Figure 2 The tail gas treatment device 34 specifically includes a tail gas washing tower T-606, which is provided with a second electric demister X-603, a tail gas inlet, a treatment agent outlet, a treatment agent inlet, a residual gas discharge port, and a dilute sulfuric acid outlet. The treatment agent inlet and the treatment agent inlet are connected by a treatment agent circulation pipeline, which is provided with a dilute sulfuric acid outlet and a hydrogen peroxide supplement port. The hydrogen peroxide supplement port is connected to the hydrogen peroxide tank V-605 through a hydrogen peroxide pipeline, which is provided with a hydrogen peroxide pump P-607. The residual gas discharge port is connected to the exhaust pipe X-604.

[0057] In this embodiment, the tail gas outlet of the sulfuric acid vapor condenser E-607 is connected to the tail gas inlet of the tail gas washing tower T-606 through a tail gas pipeline, which is provided with a desalted water inlet. The tail gas from the sulfuric acid vapor condenser E-607 is desulfurized by 27.5wt% hydrogen peroxide in the tail gas washing tower T-606, and then enters the second electric demister X-603 for demisting and purification. The exhaust pipe X-604 meets the emission standard, and the dilute sulfuric acid obtained after washing is sent to the phosphoric acid production unit 1.

[0058] In this embodiment, the flue gas from the phosphogypsum cracking unit 2 has the following composition:

[0059] Gas composition Wet basis vol. % at 20°C CO2 14.67 SO2 8.92 [N2] 64.02 O2 3.81 SO3 0.05 H2O 8.03 CO 0.5 Sublimed sulphur Irregularly produced NO x ]] Small amounts Total 100

[0060] The flue gas is supplemented with air before entering the reactor to obtain a reaction gas, which has low SO2 concentration and high water content.

[0061] Taking a 300,000-ton / year phosphogypsum cracking flue gas treatment for sulfuric acid production as an example, the output and input of dry-process sulfuric acid and wet-process sulfuric acid are compared:

[0062]

[0063]

[0064] It can be seen that in the production of phosphogypsum acid and cement, the use of wet-process acid instead of dry-process acid has obvious advantages. The economic benefit of wet-process acid is as follows:

[0065] On the one hand, 200℃ air is produced for 1 hour, 337833.3Nm 3 (1 Nm 3The air releases 219.4kJ heat from 200 DEG C to 25 DEG C, and the utilization rate is 50%, and the standard coal is 1260.5kg. According to 1474.8 yuan per ton of standard coal, and the annual operation is 7200 hours, 13384684.88 yuan is saved.

[0066] On the other hand, 1 hour produces saturated steam 14.83 tons of pressure 5.5MPaG, temperature 389.16 DEG C, wherein the water temperature is 104 DEG C, and the pressure is 6.0MPaG, and 1kg of water with pressure 5.5MPa and temperature 104 DEG C is changed into saturated steam with pressure 5.5MPa and temperature 389.16 DEG C, and 2000kJ of heat needs to be absorbed, and then 14.83 tons of water with pressure 5.5MPa and temperature 104 DEG C is changed into saturated steam with pressure 5.5MPa and temperature 389.16 DEG C, and 29660000kJ of heat needs to be absorbed, and the standard coal is 1008kg. According to the heat utilization rate 70%, the standard coal unit price 1474.8 yuan, and the annual operation 7200 hours, 7492544.9 yuan is saved annually.

[0067] As can be seen from the above, the utility model adopts multiple ways to recover heat, for example, the flue gas at 320 DEG C from the phosphogypsum cracking unit exchanges heat with the flue gas at 60 DEG C purified by the flue gas pretreatment device in the flue gas heater, and for example, the heat exchanger is arranged behind the third bed layer of the reactor, and the like, so that the flue gas heat is deeply utilized, and the SO2 concentration in the flue gas is 3%, and self-heating balance can be realized.

[0068] At the same time, the volume content of SO2 generated by the calcination of phosphogypsum is low, and the working condition of the wet acid making process is not affected, so that the operation condition for further producing cement clinker is more relaxed, the flue gas with low SO2 content can be treated, and the fluctuation of the SO2 content in the front-end process within a certain range can be accepted, and the sulfur yield in the flue gas can still reach more than 99%.

Claims

1. A sulfuric acid process phosphoric acid production system, characterized by, It comprises a phosphoric acid production unit, a phosphogypsum cracking unit and a wet-process sulfuric acid unit; The phosphoric acid production unit comprises a reaction device and a filtering device; the reaction device is provided with a mixed feed inlet and a reaction discharge outlet; the filtering device is provided with a reaction feed inlet, a solid discharge outlet and a liquid discharge outlet; The phosphogypsum cracking unit comprises a calcining device; the calcining device is provided with a raw material feed inlet, a clinker discharge outlet and a crude flue gas discharge outlet; The wet-process sulfuric acid unit comprises a flue gas reaction device and an acid cooling device; the flue gas reaction device is provided with a reaction gas feed inlet and an acid gas discharge outlet; the acid cooling device is provided with an acid gas feed inlet, a sulfuric acid discharge outlet and a tail gas discharge outlet; The mixed feed inlet is connected with a phosphorite source and a water source; the reaction discharge outlet is connected with the reaction feed inlet; the solid discharge outlet is connected with the raw material feed inlet; the crude flue gas discharge outlet is connected with the reaction gas feed inlet; the reaction gas feed inlet is connected with an air source and a fuel gas source; the acid gas discharge outlet is connected with the acid gas feed inlet; the sulfuric acid discharge outlet is connected with the mixed feed inlet.

2. The sulfuric acid process phosphoric acid production system as claimed in claim 1, characterized by, The phosphoric acid production unit further comprises a raw material mixing device, which is provided with a water feed inlet, a phosphorite feed inlet and a mixed discharge outlet; the mixed discharge outlet is connected with the mixed feed inlet.

3. The sulfuric acid process phosphoric acid production system as claimed in claim 2, characterized by, The raw material mixing device is further provided with an acidic water feed inlet; the wet-process sulfuric acid unit further comprises a flue gas pretreatment device, which is provided with a crude flue gas feed inlet, an acidic water discharge outlet and a flue gas discharge outlet; the crude flue gas discharge outlet is connected with the crude flue gas feed inlet; the acidic water discharge outlet is connected with the acidic water feed inlet; the flue gas discharge outlet is connected with the reaction gas feed inlet.

4. The sulfuric acid process phosphoric acid production system as claimed in claim 1, wherein, The reaction device is further provided with a circulation outlet and a circulation inlet; the circulation outlet and the circulation inlet are connected through a circulation pipeline outside the reaction device; the circulation pipeline is provided with a cooling device.

5. The sulfuric acid process phosphoric acid production system as claimed in claim 1, wherein, The reaction device is further provided with a tail gas outlet, which is connected with a tail gas treatment device.

6. The sulfuric acid process phosphoric acid production system as claimed in claim 1, wherein, The phosphoric acid production unit further comprises a concentration device; the concentration device is provided with a liquid feed inlet, a jacket, a fluosilicic acid discharge outlet and a phosphoric acid discharge outlet; the jacket is provided with a steam inlet and a condensed water outlet.

7. The sulfuric acid process phosphoric acid production system as claimed in claim 6, characterized by, The flue gas reaction device is further provided with a boiler water inlet and a steam outlet; the steam outlet is connected with the steam inlet.

8. The sulfuric acid process phosphoric acid production system as claimed in claim 1, wherein, The phosphogypsum cracking unit further comprises a drying device, which is provided with a phosphogypsum feed inlet, a hot air inlet and a dry material discharge outlet; the solid discharge outlet is connected with the phosphogypsum feed inlet; the dry material discharge outlet is connected with the raw material feed inlet.

9. The sulfuric acid process phosphoric acid production system as claimed in claim 8, characterized by, The phosphogypsum cracking unit further comprises a mixing device, which is provided with an auxiliary material feed inlet, a dry material feed inlet and a raw material discharge outlet; the dry material discharge outlet is connected with the dry material feed inlet; the raw material discharge outlet is connected with the raw material feed inlet; The acid cooling device is further provided with a jacket, which is provided with a cold air inlet and a hot air outlet; the hot air outlet is connected with the hot air inlet.

10. The sulfuric acid process phosphoric acid production system as claimed in claim 1, wherein, The wet method sulfuric acid unit also comprises a tail gas treatment device, which is provided with a tail gas inlet, a treatment agent inlet and a dilute sulfuric acid outlet; the tail gas outlet is connected with the tail gas inlet, the treatment agent inlet is connected with a hydrogen peroxide source, and the dilute sulfuric acid outlet is connected with the mixed inlet.

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