Treatment device for phosphorus pentoxide tail washing wastewater

Abstract

The utility model discloses a treatment device for phosphorus pentoxide tail washing wastewater, and belongs to the technical field of phosphorus chemical industry. Comprising a graphite evaporator, a middle storage tank, a reaction kettle, a filter press, a phosphoric acid storage tank, a condenser, a gas-liquid separator and a vacuum pump, the graphite evaporator, the middle storage tank, the reaction kettle, the filter press and the phosphoric acid storage tank are sequentially connected, and a vacuumizing opening of the graphite evaporator, the condenser, the gas-liquid separator and the vacuum pump are sequentially connected. A condensed water outlet of the condenser and a liquid outlet of the gas-liquid separator are both connected with a water replenishing port of the cooling water supply device and form a circulating cooling system with the cooling water supply device, and steam inlets of the graphite evaporator and the heater of the reaction kettle are both connected with a steam pocket of a phosphorus burning tower of the hot-process phosphoric acid production system; and a feeding hole of the graphite evaporator is connected with a wastewater outlet of a tail gas treatment device of the phosphorus pentoxide production system. The waste water is concentrated and decolored by using steam of hot-process phosphoric acid as a heat source, so that transparent and high-concentration phosphoric acid is obtained.

Description

Technical Field

[0001] The utility model belongs to the technical field of phosphorus chemical industry, and particularly relates to a treatment device for phosphorus pentoxide tail washing wastewater. Background Art

[0002] Phosphorus pentoxide is a commonly used raw material and reagent in the chemical industry and is widely used in various fields. At present, the preparation of phosphorus pentoxide in industry generally adopts the oxidation combustion method: yellow phosphorus is used as the raw material, and the yellow phosphorus is heated and melted and then added to the combustion furnace. The dried air is introduced into the combustion furnace to react and burn with the yellow phosphorus to generate phosphorus pentoxide flue gas, and then the phosphorus pentoxide flue gas is cooled and settled to make the finished phosphorus pentoxide product. The settled flue gas needs to be sent to the exhaust gas treatment device for treatment to make the phosphorus content and dust content of the exhaust gas meet the requirements.

[0003] For example, the patent with application number CN202120468714.0 discloses a tail gas treatment device for phosphorus pentoxide, including a cyclone separator, a fiber dust collector, a packed spray tower, a first cyclone spray tower and a second cyclone spray tower, wherein the cyclone separator, the packed spray tower, the first cyclone spray tower, the second cyclone spray tower and the fiber dust collector are connected in sequence through pipelines; a first circulation tank and at least one first spray structure are arranged from bottom to top in the packed spray tower, and the first spray structure includes a first circulation tank and a first spray structure. A first nozzle, an orifice plate, a corrugated packing layer, a demister and a PP ball packing layer are arranged in sequence from bottom to top, and the first circulation groove is connected to the first nozzle; the first swirl spray tower and the second swirl spray tower are both provided with a second circulation groove and at least one second spray structure from bottom to top, and the second spray structure includes a second nozzle, a swirl plate and a magnetic ring layer arranged in sequence from bottom to top, the second circulation groove is connected to the second nozzle, and the swirl plate of the first swirl spray tower and the swirl plate of the second swirl spray tower have opposite blade rotation directions.

[0004] Among them, the cyclone separator, fiber dust collector, packed spray tower, first cyclone spray tower and second cyclone spray tower are sprayed with dilute acid or clean water (the cyclone separator, first cyclone spray tower and second cyclone spray tower are all replenished with clean water for spraying, and the packed spray tower is replenished with dilute acid of the cyclone separator). In order to ensure the quality of the tail gas, a large amount of acidic tail washing wastewater will be obtained. Based on a 6,000 tons / a phosphorus pentoxide production system, 20-30 tons of wastewater will be generated every month, and the concentration of the wastewater is 18-20wt% in terms of phosphoric acid.

[0005] The applicant found that the phosphorus pentoxide tail washing wastewater has low concentration and color (green or yellow), and cannot be sold. Summary of the invention

[0006] In order to solve the above problems, the embodiment of the utility model provides a treatment device for phosphorus pentoxide tail washing wastewater, which uses the vapor of thermal phosphoric acid as a heat source to concentrate and decolorize the wastewater to obtain transparent and high-concentration phosphoric acid, and the product can be directly sold. The technical solution is as follows:

[0007] The utility model embodiment provides a treatment device for tail washing wastewater of phosphorus pentoxide, comprising a graphite evaporator, an intermediate storage tank, a reactor, a filter press, a phosphoric acid storage tank, a condenser, a gas-liquid separator and a vacuum pump, wherein the graphite evaporator, the intermediate storage tank, the reactor, the filter press and the phosphoric acid storage tank are connected in sequence through pipelines, the vacuum port of the graphite evaporator, the condenser, the gas-liquid separator and the vacuum pump are connected in sequence through pipelines, the condensate outlet of the condenser and the liquid outlet of the gas-liquid separator are both connected to the water replenishment port of a cooling water supply device through pipelines and they and the cooling water supply device form a circulating cooling system, the steam inlets of the heaters of the graphite evaporator and the reactor are both connected to the steam drum of the phosphorus burning tower of a thermal phosphoric acid production system through pipelines, and the feed port of the graphite evaporator is connected to the wastewater outlet of the tail gas treatment device of the phosphorus pentoxide production system through pipelines.

[0008] Among them, the reactor in the embodiment of the utility model is provided with a stirrer, a heater and a thermometer.

[0009] Among them, the tail gas treatment device in the embodiment of the utility model includes a cyclone separator, a packed spray tower, a first cyclone spray tower, a second cyclone spray tower, a fiber dust collector and a phosphoric acid adjustment tank. The cyclone separator, the packed spray tower, the first cyclone spray tower, the second cyclone spray tower and the fiber dust collector are connected in sequence through pipelines. The wastewater outlet of the cyclone separator is connected to the water replenishment port of the packed spray tower through a pipeline. The wastewater outlets of the packed spray tower, the first cyclone spray tower, the second cyclone spray tower and the fiber dust collector are all connected to the phosphoric acid adjustment tank through a pipeline, and the phosphoric acid adjustment tank is connected to the feed port of the graphite evaporator through a pipeline.

[0010] Among them, an annular membrane water-cooled wall is provided in the phosphorus burning tower in the embodiment of the utility model. The steam drum is located above the phosphorus burning tower and is connected to the steam outlet of the annular membrane water-cooled wall through a pipeline. The cooling water inlet of the annular membrane water-cooled wall is connected to the cooling water supply device through a pipeline.

[0011] Among them, for a phosphorus pentoxide production system with an output of 6,000 tons / a, the heat exchange area of ​​the graphite evaporator is 8-20 cubic meters, and the volume of the reactor is 800-2,000 cubic meters.

[0012] The beneficial effects brought by the technical solution provided by the embodiment of the utility model are:

[0013] (1) The vapor of thermal phosphoric acid is used as a heat source to concentrate and decolorize wastewater to obtain transparent and highly concentrated phosphoric acid. The product can be sold directly to increase revenue.

[0014] (2) The phosphorus burning tower in the thermal phosphoric acid production system has excess steam, which is equivalent to no energy consumption.

[0015] (3) Concentration can produce clean condensate (if the preparation requires purification, desalination and deoxygenation, etc.), which can be used as make-up water for the cooling water supply device.

[0016] (4) It can be concentrated to different concentrations according to customer needs and has high adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a principle block diagram of a treatment device for phosphorus pentoxide tail washing wastewater in an embodiment of the utility model;

[0018] Figure 2 It is a principle block diagram of the exhaust gas treatment device in the embodiment of the utility model;

[0019] Figure 3 It is a schematic diagram of the output of drum steam. DETAILED DESCRIPTION

[0020] 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.

[0021] Example 1

[0022] See also Figure 1-3Embodiment 1 provides a treatment device for tail washing wastewater of phosphorus pentoxide, including a graphite evaporator, an intermediate storage tank, a reactor, a filter press, a phosphoric acid storage tank, a condenser, a gas-liquid separator and a vacuum pump. The graphite evaporator, the intermediate storage tank, the reactor, the filter press and the phosphoric acid storage tank are connected in sequence through pipelines, and are used to concentrate, decolorize and filter the wastewater in sequence. The vacuum port of the graphite evaporator, the condenser, the gas-liquid separator and the vacuum pump are connected in sequence through pipelines to evacuate the graphite evaporator. The condensate outlet of the condenser and the liquid outlet of the gas-liquid separator are both connected to the water supply port of the cooling water supply device through pipelines to output clean water to the cooling water supply device. The cooling water inlet and cooling water outlet of the tubes of the condenser are both connected to the cooling water supply device (which provides cooling water for the condenser and provides cooling water for the hydration tower, cooling tower and phosphorus burning tower, etc.) through pipelines, and it and the cooling water supply device form a circulating cooling system. The steam inlet of the heater of the graphite evaporator and the reactor is connected to the drum of the phosphorus burning tower of the thermal phosphoric acid production system (its structure can be seen in the description of the patent with application number CN202120468711.7) through a pipeline for heating, and the feed port of the graphite evaporator is connected to the wastewater outlet of the tail gas treatment device of the phosphorus pentoxide production system (its structure can be seen in the description of the patent with application number CN202120468720.6) through a pipeline to output the tail wash wastewater to the graphite evaporator. Among them, the cooling water supply device includes a circulation tank and a cooling water tower.

[0023] Among them, the reactor in the embodiment of the utility model is equipped with a stirrer, a heater and a thermometer.

[0024] Among them, see Figure 2 The tail gas treatment device in the embodiment of the utility model includes a cyclone separator, a packing spray tower, a first cyclone spray tower, a second cyclone spray tower, a fiber dust collector and a phosphoric acid adjustment tank, etc. The cyclone separator (connected to the tail gas outlet of the last settling tower through a pipeline), the packing spray tower, the first cyclone spray tower, the second cyclone spray tower and the fiber dust collector are connected in sequence through pipelines. The wastewater outlet of the cyclone separator (in which clean water is sprayed) is connected to the water replenishment port of the packing spray tower (in which dilute acid is sprayed in a circulation) through a pipeline, and the wastewater outlets of the packing spray tower, the first cyclone spray tower (in which dilute acid is sprayed and clean water is replenished), the second cyclone spray tower (in which dilute acid is sprayed and clean water is replenished) and the fiber dust collector are all connected to the phosphoric acid adjustment tank through a pipeline, and the phosphoric acid adjustment tank is connected to the feed port of the graphite evaporator through a pipeline to output tail washing wastewater. The structure of the exhaust gas treatment device can be found in the description of patent application number CN202120468714.0.

[0025] Among them, see Figure 3In the embodiment of the utility model, the phosphorus burning tower is provided with an annular membrane water-cooled wall, the steam drum (which also provides steam for other structures (such as phosphorus storage tanks)) is located above the phosphorus burning tower and is connected to the steam outlet of the annular membrane water-cooled wall through a pipeline, and the cooling water inlet of the annular membrane water-cooled wall is connected to the cooling water supply device through a pipeline. The structure of the phosphorus burning tower can be found in the description of the patent with application number CN201420318761.7.

[0026] Among them, for a phosphorus pentoxide production system with an output of 6,000 tons / a, the heat exchange area of ​​the graphite evaporator is 8-20 cubic meters, and the volume of the reactor is 800-2,000 cubic meters.

[0027] Example 2

[0028] Example 2 provides a treatment device for phosphorus pentoxide tail washing wastewater, whose structure is basically the same as that of Example 1, except that: for a phosphorus pentoxide production system with an output of 6,000 tons / a, the heat exchange area of ​​the graphite evaporator is 10 cubic meters, the volume of the reactor is 1,000 cubic meters, and the volume of the intermediate storage tank is greater than 600 cubic meters.

[0029] The working process of this patent is: in a graphite evaporator, it is heated to about 80°C and the negative pressure is 0.06-0.08Mpa. About 1.5 tons of wastewater can be concentrated every 10 hours (measured at 80-85wt% concentration, of course, it can also be concentrated to other concentrations according to customer needs). After concentration, it is sent to the intermediate storage tank for storage. After several concentrations, the amount of concentrated wastewater in the intermediate storage tank is sent to the reactor for treatment after it reaches a suitable volume. In the reactor, it is heated to about 80°C, activated carbon (5 kg / 100 kg of concentrated wastewater) and diatomaceous earth (3 kg / 100 kg of concentrated wastewater) are added, and the reaction is about 2 hours. After the reaction is completed, it is sent to a filter press for filtration, and the filtrate is sent to a phosphoric acid storage tank for storage as phosphoric acid. The processing capacity of the treatment device for the tail wash wastewater of phosphorus pentoxide in this embodiment matches the production capacity of the phosphorus pentoxide production system.

[0030] The "first" and "second" in this embodiment are only used for distinction and have no other special meaning. Pumps, valves or flow meters etc. are arranged on the pipelines between the structures as required.

[0031] 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 treatment device for phosphorus pentoxide tail washing wastewater, characterized in that: The invention comprises a graphite evaporator, an intermediate storage tank, a reactor, a filter press, a phosphoric acid storage tank, a condenser, a gas-liquid separator and a vacuum pump. The graphite evaporator, the intermediate storage tank, the reactor, the filter press and the phosphoric acid storage tank are connected in sequence through pipelines. The vacuum port of the graphite evaporator, the condenser, the gas-liquid separator and the vacuum pump are connected in sequence through pipelines. The condensate outlet of the condenser and the liquid outlet of the gas-liquid separator are both connected to the water replenishment port of a cooling water supply device through pipelines and form a circulating cooling system with the cooling water supply device. The steam inlets of the heaters of the graphite evaporator and the reactor are both connected to the steam drum of the phosphorus burning tower of the thermal phosphoric acid production system through pipelines. The feed port of the graphite evaporator is connected to the wastewater outlet of the tail gas treatment device of the phosphorus pentoxide production system through pipelines.

2. The treatment device for phosphorus pentoxide tail washing wastewater according to claim 1, characterized in that: The reactor is provided with a stirrer, a heater and a thermometer.

3. The treatment device for phosphorus pentoxide tail washing wastewater according to claim 1, characterized in that: The tail gas treatment device comprises a cyclone separator, a packed spray tower, a first cyclone spray tower, a second cyclone spray tower, a fiber dust collector and a phosphoric acid adjustment tank. The cyclone separator, the packed spray tower, the first cyclone spray tower, the second cyclone spray tower and the fiber dust collector are connected in sequence through pipelines. The wastewater outlet of the cyclone separator is connected to the water replenishment port of the packed spray tower through a pipeline. The wastewater outlets of the packed spray tower, the first cyclone spray tower, the second cyclone spray tower and the fiber dust collector are all connected to the phosphoric acid adjustment tank through a pipeline. The phosphoric acid adjustment tank is connected to the feed port of a graphite evaporator through a pipeline.

4. The treatment device for phosphorus pentoxide tail washing wastewater according to claim 1, characterized in that: An annular membrane water-cooled wall is arranged in the phosphorus burning tower. The steam drum is located above the phosphorus burning tower and is connected to the steam outlet of the annular membrane water-cooled wall through a pipeline. The cooling water inlet of the annular membrane water-cooled wall is connected to a cooling water supply device through a pipeline.

5. The treatment device for phosphorus pentoxide tail washing wastewater according to claim 1 is characterized in that: For a phosphorus pentoxide production system with an output of 6,000 tons / a, the heat exchange area of ​​the graphite evaporator is 8-20 cubic meters, and the volume of the reactor is 800-2,000 cubic meters.

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