Preparation device capable of producing phosphoric acid with various concentrations

Abstract

The utility model discloses a preparation device capable of producing phosphoric acid with various concentrations, and belongs to the technical field of phosphorus chemical industry. Comprising a filtering structure, a product storage tank, a phosphorus combustion tower, a first-stage hydration structure, a second-stage hydration structure and a tail gas treatment structure, and the first-stage hydration structure comprises a first-stage hydration tower, a first-stage heat exchanger and a first-stage circulating tank; the second-stage hydration structure comprises a second-stage hydration tower, a second-stage heat exchanger and a second-stage circulating tank; the filtering structure comprises a filter press and a microporous filter, the product storage tank comprises an orthophosphoric acid storage tank and a polyphosphoric acid storage tank, a wastewater outlet of the tail gas treatment structure is connected with the secondary circulating tank, the secondary circulating tank is connected with the primary circulating tank, the primary circulating tank is provided with a temperature sensor and a feeding sampling port, the primary circulating tank is divided into three paths of output, and the temperature sensor is connected with the temperature sensor. The first path is connected with an orthophosphoric acid storage tank through a pipeline with a filter press and a valve, the second path is connected with a polyphosphoric acid storage tank through a pipeline with a microporous filter and a valve, and the third path is connected with a primary hydration tower through a pipeline with a valve.

Description

Technical Field

[0001] The utility model belongs to the technical field of phosphorus chemical industry, and particularly relates to a preparation device capable of producing phosphoric acid with various concentrations. Background Art

[0002] Polyphosphoric acid is an inorganic substance with the chemical formula H n+2 P n O 3n+1 It is a colorless, transparent, viscous liquid. It is corrosive and belongs to the second-level inorganic acid corrosive items. It can be obtained by adding phosphorus pentoxide to pure water and then heating and condensing it. It has high viscosity and is difficult to stir and pour at room temperature, but it is easy to operate above 60°C. There are two ways to express the concentration of polyphosphoric acid, one is expressed as P2O5%; the other is expressed as H3PO4 as 100%, and expressed by the content of H3PO4 in polyphosphoric acid. The concentration of polyphosphoric acid (measured by H3PO4 content) can reach up to 118%.

[0003] Orthophosphoric acid is a common inorganic acid, a medium-strong acid, with the chemical formula H3PO4. It is not volatile, not easy to decompose, and has almost no oxidizing properties. It has the general properties of an acid and is a ternary weak acid. The commercial product is usually 85% phosphoric acid by mass. It can be obtained by adding phosphorus pentoxide to pure water.

[0004] In summary, both polyphosphoric acid and orthophosphoric acid can be obtained by the reaction of phosphorus pentoxide and water.

[0005] For example, the patent with application number CN201420317868.X discloses a polyphosphoric acid production system, including a refined molten phosphorus tank, a precipitated molten phosphorus tank, a combustion tower, a primary hydration structure, a secondary hydration structure, a dearsenicization reactor, a sedimentation tank, a plate and frame filter, a desorption reactor, a filter and a finished product storage tank connected in sequence by pipelines, the flue gas outlet of the secondary hydration structure is connected to a waste gas treatment system, the primary hydration structure and the secondary hydration structure are both self-circulating structures composed of pipelines, a hydration tower, a shell-and-tube heat exchanger, a circulation pump and a circulation pool, the circulation pool is provided with a detection port, and the circulation pump is electrically connected to an electric control box.

[0006] For example, the patent with application number CN202120468711.7 discloses a thermal phosphoric acid production system capable of monitoring the degree of hydration, comprising a control room, a post-processing device, and a phosphorus melting device, a combustion tower, a primary hydration device and a secondary hydration device connected in sequence through pipelines, wherein the primary hydration device comprises a hydration tower, a circulation pool, a circulation pump and a heat exchanger connected in sequence end to end through a circulation pipeline, an electric control box is provided in the control room, and the secondary hydration device is connected to the post-processing device through a pipeline; an electric-controlled three-way valve is provided on the outlet of the circulation pump, and the electric-controlled three-way valve is output in two ways, one way is output to the hydration tower, and the other way is output to the post-processing device; an ammeter is provided on the power supply line of the circulation pump, an electronic flowmeter for detecting the flow of the circulation pump is provided on the circulation pipeline, and an electronic thermometer is provided on the hot water inlet of the heat exchanger; an ammeter, a control structure of the circulation pump, a display structure of the electronic flowmeter, a display structure of the electronic thermometer and a control structure of the electric-controlled three-way valve are provided in the electric control box.

[0007] In the prior art, phosphoric acid of different concentrations is prepared by controlling the hydration degree of the primary hydration structure. The applicant found the following problems when using the existing equipment to prepare orthophosphoric acid and polyphosphoric acid:

[0008] (1) The viscosity of polyphosphoric acid is very high, and it is very difficult to filter by plate and frame filter press;

[0009] (2) Acidic wastewater is generated during the preparation process (such as tail gas treatment);

[0010] (3) It is difficult to control phosphoric acid only through a hydration tower, which requires very accurate control of the amount of water added and the temperature, and is also easily affected by the environment. Summary of the invention

[0011] In order to solve the above problems, the embodiment of the utility model provides a preparation device capable of producing phosphoric acid of various concentrations, using the dilute acid in the secondary circulation tank to dilute the concentrated acid in the primary circulation tank, which is not only convenient for controlling the concentration (coordinated with the hydration degree of the hydration tower), but also simultaneously treats the wastewater; in addition, different filtering methods are used for phosphoric acid of different concentrations. The technical solution is as follows:

[0012] The utility model provides a preparation device capable of producing phosphoric acid of various concentrations, comprising a filtering structure, a product storage tank, a phosphorus burning tower, a primary hydration structure, a secondary hydration structure and a tail gas treatment structure, wherein the primary hydration structure comprises a primary hydration tower, a primary heat exchanger and a primary circulation tank connected end to end; the secondary hydration structure comprises a secondary hydration tower, a secondary heat exchanger and a secondary circulation tank connected end to end; the phosphorus burning tower, the primary hydration tower, the secondary hydration tower and the tail gas treatment structure are connected in sequence through pipelines; the filtering structure comprises a filter press and a microporous filter, the product storage tank comprises an orthophosphoric acid storage tank and a polyphosphoric acid storage tank, The wastewater outlet of the tail gas treatment structure is connected to the secondary circulation tank through a pipeline, the secondary circulation tank is connected to the primary circulation tank through a pipeline, the primary circulation tank is provided with a temperature sensor and a feeding sampling port, the primary circulation tank is divided into three outputs, the first output is connected to the orthophosphoric acid storage tank through a pipeline with a filter press and a valve, the second output is connected to the polyphosphoric acid storage tank through a pipeline with a microporous filter and a valve, and the third output is connected to the primary hydration tower through a pipeline with a valve; when preparing orthophosphoric acid, a filter aid is added to the feeding sampling port, and the filter press is switched for filtering; when preparing polyphosphoric acid, the microporous filter is switched for filtering.

[0013] Furthermore, the primary hydration structure in the embodiment of the utility model also includes a primary circulation pump, and the primary circulation tank is connected to the inlet of the primary circulation pump through a pipeline; the outlet of the primary circulation pump is divided into three outputs, the first output is connected to the orthophosphoric acid storage tank through a pipeline with a filter press and a valve, the second output is connected to the polyphosphoric acid storage tank through a pipeline with a microporous filter and a valve, and the third output is connected to the primary hydration tower through a pipeline with a valve; the secondary hydration structure also includes a secondary circulation pump, and the secondary circulation tank is connected to the inlet of the secondary circulation pump through a pipeline; the outlet of the secondary circulation pump is divided into two outputs, one output is connected to the secondary hydration tower through a pipeline with a valve, and the other output is connected to the primary circulation tank through a pipeline with a valve.

[0014] Among them, the exhaust gas treatment structure in the embodiment of the utility model includes a three-stage circulation tank, a three-stage circulation pump, a venturi washing tower, a spray washing tower, a cyclone demister, a fiber dust collector and a fan, the secondary hydration tower, the venturi washing tower, the spray washing tower, the cyclone demister, the fiber dust collector and the fan are connected in sequence through pipelines, the wastewater outlets of the venturi washing tower, the spray washing tower, the cyclone demister and the fiber dust collector are all connected to the three-stage circulation tank through pipelines, the three-stage circulation tank is connected to the clean water supply structure and it is connected to the inlet of the three-stage circulation pump through a pipeline; the outlet of the three-stage circulation pump is divided into two outputs, one is connected to the spray liquid inlet of the venturi washing tower, the spray washing tower and the cyclone demister through a pipeline with a valve, and the other is connected to the secondary circulation tank through a pipeline with a valve.

[0015] Specifically, the phosphorus burning tower, primary hydration tower, secondary hydration tower, venturi washing tower and spray washing tower in the embodiment of the utility model are arranged side by side, and the cyclone demister is located directly above the spray washing tower; the secondary circulation tank is located next to the primary circulation tank, which is higher than the primary circulation tank, and its top is connected to the primary circulation tank through an overflow pipe.

[0016] Preferably, the primary heat exchanger in the embodiment of the utility model is a plate heat exchanger, and the secondary heat exchanger is a shell and tube heat exchanger.

[0017] Among them, the first-level hydration tower and the second-level hydration tower in the embodiment of the utility model are both provided with an air inlet on the top, an air outlet on the bottom, a nozzle inside, and a water-cooling jacket on the outer wall; the nozzle of the first-level hydration tower is connected to the outlet of the first-level circulation pump through a pipeline, and the nozzle of the second-level hydration tower is connected to the outlet of the second-level circulation pump through a pipeline; an overflow weir is coaxially provided at the top of the first-level hydration tower; the overflow weir is annular, and the liquid flowing out of it flows downward along the inner wall of the first-level hydration tower, and it is connected to the outlet of the first-level circulation pump through a pipeline.

[0018] The beneficial effects brought by the technical solution provided by the embodiment of the utility model are:

[0019] (1) The concentrated acid in the primary circulation tank is diluted by using the dilute acid in the secondary circulation tank (receiving the wastewater from the tail gas treatment structure). This not only facilitates the control of the concentration (controlled by coordinating the hydration degree of the hydration tower), but also treats the wastewater at the same time and reduces the temperature of the primary circulation tank.

[0020] (2) Different filtration methods were used for different concentrations of phosphoric acid.

[0021] (3) When preparing high-concentration phosphoric acid, the reaction temperature is high. Phosphoric acid at high temperature is highly corrosive to equipment. Various means are used to reduce corrosion: first, use cooled phosphoric acid to cool the inner wall of the primary hydration tower; second, use a plate heat exchanger with better cooling effect to cool; and third, add dilute acid (low temperature) from the secondary circulation tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a principle block diagram of a preparation device capable of producing phosphoric acid of various concentrations in an embodiment of the utility model;

[0023] Figure 2 It is a partial structural schematic diagram of a preparation device capable of producing phosphoric acid of various concentrations in an embodiment of the utility model.

[0024] In the figure: 1 phosphorus burning tower, 2 primary hydration tower, 3 secondary hydration tower, 4 venturi scrubber, 5 spray scrubber, 6 cyclone demister, 7 overflow weir. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the utility model clearer, the utility model will be further described in detail below with reference to the accompanying drawings.

[0026] See also Figure 1-2 The embodiment of the utility model provides a preparation device capable of producing phosphoric acid of various concentrations, the device comprising a filtering structure, a product storage tank, a yellow phosphorus storage tank, a sedimentation tank, a phosphorus burning tower 1, a primary hydration structure, a secondary hydration structure and an exhaust gas treatment structure.

[0027] Among them, the primary hydration structure includes a primary hydration tower 2, a primary heat exchanger, a primary circulation tank and a primary circulation pump connected end to end through a pipeline. The secondary hydration structure includes a secondary hydration tower 3, a secondary heat exchanger, a secondary circulation tank and a primary circulation pump connected end to end through a pipeline. The yellow phosphorus storage tank, the sedimentation tank and the spray gun of the phosphorus burning tower 1 are connected in sequence through pipelines, and the phosphorus burning tower 1, the primary hydration tower 2, the secondary hydration tower 3 and the tail gas treatment structure are connected in sequence through pipelines. The tail gas treatment structure includes a tertiary circulation tank, a tertiary circulation pump, a venturi washing tower 4, a spray washing tower 5, a cyclone demister 6, a fiber dust collector and a fan, etc. The filtering structure includes a filter press and a microporous filter, and the product storage tank includes an orthophosphoric acid storage tank (which can be multiple, used to hold orthophosphoric acid of different concentrations, switched by a valve) and a polyphosphoric acid storage tank (which can be multiple, used to hold polyphosphoric acid of different concentrations, switched by a valve). The primary circulation tank is equipped with a temperature sensor (preparation of phosphoric acid of different concentrations requires different temperatures) and a feeding sampling port (used for sampling (concentration needs to be determined through sampling detection) and feeding filter aids).

[0028] Among them, the secondary hydration tower 3, the venturi washing tower 4, the spray washing tower 5, the cyclone demister 6, the fiber dust collector and the fan are connected in sequence through pipelines, and the wastewater outlets of the venturi washing tower 4, the spray washing tower 5, the cyclone demister 6 and the fiber dust collector are all connected to the tertiary circulation tank (lower than the venturi washing tower 4, the spray washing tower 5, the cyclone demister 6 and the fiber dust collector) through pipelines to collect wastewater, and the tertiary circulation tank is connected to the clean water supply structure for water replenishment and is connected to the inlet of the tertiary circulation pump through a pipeline. The outlet of the tertiary circulation pump is divided into two outputs, one of which is connected to the spray liquid inlet of the venturi washing tower 4, the spray washing tower 5 and the cyclone demister 6 through a pipeline with a valve for circulating spraying, and the other is connected to the secondary circulation tank through a pipeline with a valve to send the wastewater to the secondary circulation tank. The secondary circulation tank (lower than the secondary hydration tower 3) is connected to the inlet of the secondary circulation pump through a pipeline; the outlet of the secondary circulation pump is divided into two outputs, one is connected to the secondary hydration tower 3 through a pipeline with a valve for circulation spraying, and the other is connected to the primary circulation tank through a pipeline with a valve to send the dilute acid to the primary circulation tank. The primary circulation tank (lower than the primary hydration tower 2) is connected to the inlet of the primary circulation pump through a pipeline; the outlet of the primary circulation pump is divided into three outputs, the first is connected to the orthophosphoric acid storage tank through a pipeline with a filter press and a valve for the preparation of orthophosphoric acid, the second is connected to the polyphosphoric acid storage tank through a pipeline with a microporous filter and a valve for the preparation of polyphosphoric acid, and the third is connected to the primary hydration tower 2 (including the nozzle and overflow weir 7 therein) through a pipeline with a valve for circulation spraying. Controlling the corresponding valves can control the degree of hydration and the amount of dilute acid entering the primary circulation tank.

[0029] When preparing orthophosphoric acid (hydration temperature is relatively low, about 80°C), add filter aid (specifically diatomaceous earth) into the feeding sampling port, and switch to the filter press for filtration. When preparing polyphosphoric acid (hydration temperature is relatively high, about 140°C), switch to the microporous filter (specific model can be ZY-7-30, phosphoric acid is required to drop to 100°C or below when it is sent to the microporous filter through the pipeline) for filtration.

[0030] See also Figure 2In this embodiment, the phosphorus burning tower 1, the primary hydration tower 2, the secondary hydration tower 3, the Venturi washing tower 4 and the spray washing tower 5 are arranged side by side. The heights of the phosphorus burning tower 1, the primary hydration tower 2 and the secondary hydration tower 3 are similar, all above 10m, and the diameters are above 1.5m; the Venturi washing tower 4 and the spray washing tower 5 are shorter, all below 7m, and the diameters are less than 1.5m. The cyclone demister 6 is located directly above the spray washing tower 5. The secondary circulation tank is located next to the primary circulation tank, which is higher than the primary circulation tank, and its top is connected to the primary circulation tank through an overflow pipe (usually not working to avoid overflowing of the secondary circulation tank). The tertiary circulation tank is arranged at the bottom of the spray washing tower 5. The tops of the primary hydration tower 2 and the secondary hydration tower 3 are both provided with air inlets, and the bottoms are both provided with air outlets. There are nozzles inside (specifically the top and the middle) and the outer walls are both provided with water-cooling jackets, which are upper-in and lower-out structures. There are nozzles inside the cyclone demister 6. The bottom of the venturi scrubber 4 and the spray scrubber 5 are both provided with an air inlet, the top of the venturi scrubber 4 and the spray scrubber 5 are both provided with an air outlet, and the inside of the venturi scrubber 4 and the spray scrubber 5 are both provided with a nozzle, which is a bottom-in and top-out structure. The nozzle of the primary hydration tower 2 is connected to the outlet of the primary circulation pump through a pipeline, and the nozzle of the secondary hydration tower 3 is connected to the outlet of the secondary circulation pump through a pipeline.

[0031] Preferably, the primary heat exchanger in the embodiment of the utility model is a plate heat exchanger (good cooling effect, difficult maintenance) to avoid the temperature of the primary hydration tower 2 being too high, and the secondary heat exchanger is a shell and tube heat exchanger (not as good as the plate heat exchanger in cooling, simple maintenance) to meet the cooling demand of the secondary hydration tower 3.

[0032] Preferably, an overflow weir 7 (which may protrude outward relative to the side wall of the primary hydration tower 2) is coaxially arranged at the top of the primary hydration tower 2 in the embodiment of the utility model. The overflow weir is annular and is arranged on the inner wall of the primary hydration tower 2. The liquid flowing out of the overflow weir flows downward along the inner wall of the primary hydration tower 2 and is connected to the outlet of the primary circulation pump through a pipeline.

[0033] The "first", "second" and "third" in this embodiment are only used for distinction and have no other special meaning. In this embodiment, a pump, a fan, a valve or a flow meter etc. are arranged on the pipelines between the structures as required.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation device capable of producing phosphoric acid of various concentrations, comprising a filtering structure, a product storage tank, a phosphorus burning tower (1), a primary hydration structure, a secondary hydration structure and a tail gas treatment structure, wherein the primary hydration structure comprises a primary hydration tower (2), a primary heat exchanger and a primary circulation tank connected end to end; the secondary hydration structure comprises a secondary hydration tower (3), a secondary heat exchanger and a secondary circulation tank connected end to end; the phosphorus burning tower (1), the primary hydration tower (2), the secondary hydration tower (3) and the tail gas treatment structure are connected in sequence through pipelines; characterized in that The filtering structure comprises a filter press and a microporous filter, the product storage tank comprises an orthophosphoric acid storage tank and a polyphosphoric acid storage tank, the wastewater outlet of the tail gas treatment structure is connected to a secondary circulation tank through a pipeline, the secondary circulation tank is connected to a primary circulation tank through a pipeline, the primary circulation tank is provided with a temperature sensor and a feeding sampling port, the primary circulation tank is divided into three outputs, the first output is connected to the orthophosphoric acid storage tank through a pipeline with a filter press and a valve, the second output is connected to the polyphosphoric acid storage tank through a pipeline with a microporous filter and a valve, and the third output is connected to a primary hydration tower (2) through a pipeline with a valve; when preparing orthophosphoric acid, a filter aid is added to the feeding sampling port, and the filter press is switched to filter; when preparing polyphosphoric acid, the microporous filter is switched to filter.

2. The device for producing phosphoric acid of various concentrations according to claim 1, characterized in that: The primary hydration structure further comprises a primary circulation pump, and the primary circulation tank is connected to the inlet of the primary circulation pump through a pipeline; the outlet of the primary circulation pump is divided into three outputs, the first output is connected to the orthophosphoric acid storage tank through a pipeline with a filter press and a valve, the second output is connected to the polyphosphoric acid storage tank through a pipeline with a microporous filter and a valve, and the third output is connected to the primary hydration tower (2) through a pipeline with a valve; the secondary hydration structure further comprises a secondary circulation pump, and the secondary circulation tank is connected to the inlet of the secondary circulation pump through a pipeline; the outlet of the secondary circulation pump is divided into two outputs, one output is connected to the secondary hydration tower (3) through a pipeline with a valve, and the other output is connected to the primary circulation tank through a pipeline with a valve.

3. The device for producing phosphoric acid of various concentrations according to claim 1, characterized in that: The tail gas treatment structure comprises a three-stage circulation tank, a three-stage circulation pump, a venturi washing tower (4), a spray washing tower (5), a cyclone demister (6), a fiber dust collector and a fan. The two-stage hydration tower (3), the venturi washing tower (4), the spray washing tower (5), the cyclone demister (6), the fiber dust collector and the fan are connected in sequence through pipelines. The wastewater outlets of the venturi washing tower (4), the spray washing tower (5), the cyclone demister (6) and the fiber dust collector are all connected to the three-stage circulation tank through pipelines. The three-stage circulation tank is connected to a clean water supply structure and is connected to an inlet of the three-stage circulation pump through pipelines. The outlet of the three-stage circulation pump is divided into two output paths, one of which is connected to the spray liquid inlets of the venturi washing tower (4), the spray washing tower (5) and the cyclone demister (6) through a pipeline with a valve, and the other is connected to the two-stage circulation tank through a pipeline with a valve.

4. The device for producing phosphoric acid of various concentrations according to claim 3, characterized in that: The phosphorus burning tower (1), the primary hydration tower (2), the secondary hydration tower (3), the Venturi scrubber (4) and the spray scrubber (5) are arranged side by side, and the cyclone demister (6) is located directly above the spray scrubber (5); The secondary circulation tank is located beside the primary circulation tank, is higher than the primary circulation tank, and its top is connected to the primary circulation tank through an overflow pipe.

5. The device for producing phosphoric acid of various concentrations according to claim 1, characterized in that: The primary heat exchanger is a plate heat exchanger, and the secondary heat exchanger is a shell and tube heat exchanger.

6. The device for producing phosphoric acid of various concentrations according to claim 2, characterized in that: The first-stage hydration tower (2) and the second-stage hydration tower (3) are both provided with an air inlet at the top, an air outlet at the bottom, a nozzle inside, and a water-cooling jacket on the outer wall; the nozzle of the first-stage hydration tower (2) is connected to the outlet of the first-stage circulation pump through a pipeline, and the nozzle of the second-stage hydration tower (3) is connected to the outlet of the second-stage circulation pump through a pipeline; an overflow weir (7) is coaxially provided at the top of the first-stage hydration tower (2); the overflow weir (7) is annular, and the liquid flowing out of the overflow weir flows downward along the inner wall of the first-stage hydration tower (2), and the overflow weir is connected to the outlet of the first-stage circulation pump through a pipeline.

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