Self-cleaning primary hydration structure

Abstract

The utility model discloses a self-cleaning primary hydration structure, and belongs to the technical field of phosphorus chemical industry. The structure comprises a filter press, a first-stage hydration tower, a plate heat exchanger, a first-stage circulating pool, a first-stage circulating pump, an acidic water tank and a second pipeline filter, the first-stage hydration tower, the plate heat exchanger, the first-stage circulating pool and the first-stage circulating pump are sequentially connected, and a cold water inlet of the plate heat exchanger is connected with a cooling water supply device; the circulating pump outputs in two paths, one path is connected with a feeding hole of the filter press, and the other path is connected with the primary hydration tower; a filtrate outlet of the filter press outputs in two paths, one path is connected with a phosphoric acid storage tank, and the other path is connected with a cold water inlet of the plate heat exchanger; a hot water outlet of the plate heat exchanger outputs in three paths, the first path is connected with the cooling water supply device, the second path is connected with the acid water tank, and the third path is connected with the first-stage circulating pool through a pipeline with a second pipeline filter; and the acidic water tank is connected with a tail washing circulating tank of the waste gas treatment system.

Description

Technical Field

[0001] The utility model belongs to the technical field of phosphorus chemical industry, and particularly relates to a self-cleaning primary hydration structure. Background Art

[0002] 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. That is, the existing phosphoric acid production system includes a first hydration structure, a second hydration structure and a circulating water supply structure, etc. The first hydration structure includes a first heat exchanger, a first hydration tower and a first circulation pool connected end to end, and the second hydration structure includes a second heat exchanger, a second hydration tower and a second circulation pool connected end to end. The exhaust port of the first hydration tower is connected to the air inlet of the second hydration tower through a pipeline. The first hydration tower and the second hydration tower are provided with cooling jackets outside, and the cooling jackets are connected to the circulating water supply structure through pipelines.

[0003] like Figure 1 As shown, the existing primary hydration structure includes a filter press, a primary hydration tower, a plate heat exchanger, a primary circulation pool and a primary circulation pump, etc. The primary hydration tower, the plate heat exchanger, the primary circulation pool and the primary circulation pump are connected in sequence through pipelines, and the cold water inlet of the plate heat exchanger is connected to the cooling water supply device through a pipeline with a first valve. The circulation pump has two outputs, one of which is connected to the feed port of the filter press through a pipeline with a second valve, and the other is connected to the primary hydration tower through a pipeline with a third valve.

[0004] In the prior art, the heat release of the primary hydration structure is particularly large, and the high-temperature acid is highly corrosive to the equipment. In order to ensure the cooling effect of the primary hydration structure, a plate heat exchanger can be used to replace the shell-and-tube heat exchanger. The heat release of the secondary hydration structure is not large, and the shell-and-tube heat exchanger is still used.

[0005] Plate heat exchanger is a kind of high-efficiency heat exchanger made of a series of metal sheets with certain corrugated shapes. Thin rectangular channels are formed between various plates, and heat is exchanged through the plates. Plate heat exchanger is an ideal equipment for liquid-liquid and liquid-steam heat exchange. It has the characteristics of high heat exchange efficiency, small heat loss, compact and light structure, small footprint, wide application and long service life. Under the same pressure loss, its heat transfer coefficient is 3-5 times higher than that of tube heat exchanger, and the heat recovery rate can be as high as 90% or more.

[0006] However, plate heat exchangers are more difficult to clean than shell-and-tube heat exchangers. In the prior art, the cooling water channel of the plate heat exchanger needs to be cleaned once every 1-2 months, which is very troublesome and requires at least half a day of shutdown. Summary of the invention

[0007] In order to solve the above problems, the embodiment of the utility model provides a self-cleaning primary hydration structure, which can use the produced phosphoric acid (concentration between 80-85%, temperature control between 45-55°C) to clean the plate heat exchanger conveniently and quickly. The technical solution is as follows:

[0008] The utility model embodiment provides a self-cleaning primary hydration structure, which includes a filter press, a primary hydration tower, a plate heat exchanger, a primary circulation pool and a primary circulation pump, wherein the primary hydration tower, the plate heat exchanger, the primary circulation pool and the primary circulation pump are connected in sequence through pipelines, and the cold water inlet of the plate heat exchanger is connected to a cooling water supply device through a pipeline with a first valve; the circulation pump is divided into two outputs, one of which is connected to a feed port of the filter press through a pipeline with a second valve, and the other is connected to the primary hydration tower through a pipeline with a third valve; the primary hydration structure also includes Acidic water tank and second pipeline filter; the filtrate outlet of the filter press is output in two ways, one way is connected to the phosphoric acid storage tank through a pipeline with a fourth valve, and the other way is connected to the cold water inlet of the plate heat exchanger through a pipeline with a fifth valve; the hot water outlet of the plate heat exchanger is output in three ways, the first way is connected to the cooling water supply device through a pipeline with a sixth valve, the second way is connected to the acidic water tank through a pipeline with a seventh valve, and the third way is connected to the primary circulation pool through a pipeline with an eighth valve and the second pipeline filter; the acidic water tank is connected to the tail wash circulation tank of the exhaust gas treatment system through a pipeline.

[0009] Furthermore, the self-cleanable primary hydration structure provided in the embodiment of the utility model also includes a pipeline heater, which is arranged on the pipeline between the filtrate outlet of the filter press and the cold water inlet of the plate heat exchanger.

[0010] Furthermore, the self-cleanable primary hydration structure provided in the embodiment of the utility model also includes a first pipeline filter, which is arranged on the pipeline between the filtrate outlet of the filter press and the cold water inlet of the plate heat exchanger.

[0011] Preferably, a temperature sensor or a thermometer is provided on the cold water inlet of the plate heat exchanger in the embodiment of the utility model, and a pH sensor or a pH meter is provided on the hot water outlet of the plate heat exchanger.

[0012] Preferably, the tail wash circulation tank in the embodiment of the utility model is connected to the secondary circulation pool of the secondary hydration structure through a pipeline, and the secondary circulation pool is connected to the primary circulation pool through a pipeline.

[0013] The beneficial effects of the technical solution provided by the embodiment of the utility model are: the patent can use the produced phosphoric acid (concentration between 80-85%, temperature control between 45-55°C) to clean the plate heat exchanger (first pickling, then washing), which is convenient and fast. The washing wastewater can be used as water replenishment for the exhaust gas treatment system, and there is no wastewater discharge. The filter aid will not enter the plate heat exchanger, and the cleaned block impurities will not enter the primary circulation pool. The entire cleaning time does not exceed 3 hours, and it is cleaned once every 1-2 months (similar to the cleaning frequency of the prior art). The temperature of phosphoric acid itself is high, so the energy consumption of cleaning is not high. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a principle block diagram of the existing primary hydration structure;

[0015] Figure 2 It is a principle block diagram of the self-cleaning primary hydration structure of the utility model;

[0016] Figure 3 It is a connection diagram of the tail wash circulation tank, the secondary circulation pool and the primary circulation pool. DETAILED DESCRIPTION

[0017] 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.

[0018] See also Figure 2-3 The embodiment of the utility model provides a self-cleaning primary hydration structure, which includes a filter press, a primary hydration tower, a plate heat exchanger, a primary circulation pool, a primary circulation pump, an acidic water tank, a second pipeline filter, a first pipeline filter and a pipeline heater. Among them, the acidic water tank is used to store acidic wastewater in the water washing process; the second pipeline filter is used to separate the block scale washed off in the pickling process; the first pipeline filter is used to separate impurities such as filter aids; the pipeline heater is used to heat the acid after a period of pickling to ensure that the pickling temperature is 45-55°C.

[0019] Among them, the primary hydration tower, the plate heat exchanger, the primary circulation pool and the primary circulation pump are connected in sequence through pipelines. The air inlet of the primary hydration tower is connected to the phosphorus burning tower through a pipeline, the air outlet of the primary hydration tower is connected to the air inlet of the secondary hydration tower through a pipeline, and the air outlet of the secondary hydration tower is connected to the exhaust gas treatment system through a pipeline. The structure of the exhaust gas treatment system can be found in the description of application number CN201720404492.X. The cold water inlet of the plate heat exchanger is connected to the cooling water supply device through a pipeline with a first valve; the cooling water supply device is used to provide cooling water, which includes a cooling water tower and a circulation tank, etc. The circulation pump is divided into two (selected) outputs, one is connected to the feed port of the filter press through a pipeline with a second valve to output the finished acid, and the other is connected to the nozzle in the primary hydration tower through a pipeline with a third valve for hydration. The filtrate outlet of the filter press is divided into two routes (selected), one route (when outputting phosphoric acid) is connected to the phosphoric acid storage tank through the pipeline with the fourth valve, and the other route (when cleaning the plate heat exchanger) is connected to the cold water inlet of the plate heat exchanger through the pipeline with the fifth valve, the pipeline heater and the first pipeline filter (which is in front of the pipeline heater). The hot water outlet of the plate heat exchanger is divided into three routes (selected), the first route (during normal production) is connected to the cooling water supply device through the pipeline with the sixth valve, the second route (after pickling, when washing) is connected to the acid water tank through the pipeline with the seventh valve, and the third route (during pickling) is connected to the primary circulation pool through the pipeline with the eighth valve and the second pipeline filter. The acid water tank is connected to the tail wash circulation tank of the waste gas treatment system through a pipeline with or without a pump.

[0020] Preferably, a temperature sensor or a thermometer is provided on the cold water inlet of the plate heat exchanger in the embodiment of the utility model to detect the pickling temperature. A pH sensor or a pH meter is provided on the hot water outlet of the plate heat exchanger to detect the pH value of the water output after washing, and when the pH value is close to neutral, the cooling water supply device is switched.

[0021] Preferably, see Figure 3 The tail wash circulation tank in the embodiment of the utility model is connected to the secondary circulation pool of the secondary hydration structure through a pipeline (through the output of the circulation pump of the exhaust gas treatment system), and the secondary circulation pool is connected to the primary circulation pool through a pipeline (through the output of the secondary circulation pump of the secondary hydration structure).

[0022] Specifically, the acidic water tank in this embodiment is a high-level tank, which is higher than the tail wash circulation tank. The second pipeline filter, the first pipeline filter and the pipeline heater are all acid-resistant structures.

[0023] The cleaning process of this patent is:

[0024] Pickling: After the phosphoric acid production is shut down (the temperature of phosphoric acid is about 80℃ and the concentration is about 85%), switch the corresponding valves, and the hot acid in the primary circulation pool (slightly cooled, and the acid temperature of the primary circulation pool is about 60℃) is output to the cold water inlet of the plate heat exchanger while hot, and switch the corresponding valves, and the hot water outlet of the plate heat exchanger is output to the primary circulation pool. The hot water inlet and cold water outlet of the plate heat exchanger are not working; phosphoric acid pickles the cooling water side of the plate heat exchanger. When the temperature of the acid is low, turn on the pipeline heater to heat the acid and keep the acid temperature at 45-55℃. After about two hours of cleaning, switch the corresponding valves for water washing.

[0025] Water washing: After the pickling is completed, switch the corresponding valve, and the clean water from the cooling water supply device (replenish clean water as needed) is output to the cold water inlet of the plate heat exchanger. Switch the corresponding valve, and the hot water outlet of the plate heat exchanger is output to the acidic water tank. The acidic water tank stores the washing water and replenishes the tail wash circulation tank as needed. When the pH value of the water output from the hot water outlet of the plate heat exchanger is close to neutral (to avoid acidic wastewater corroding the cooling water supply device), switch the corresponding valve, and the hot water outlet of the plate heat exchanger is output to the cooling water supply device, and the circulation stops after 5-10 minutes.

[0026] Production: After the water washing is completed, switch the corresponding valves, the clean water of the cooling water supply device is output to the cold water inlet of the plate heat exchanger, the hot water outlet of the plate heat exchanger is output to the cooling water supply device for cooling water circulation, the hot water inlet of the plate heat exchanger enters hot acid, and the cold water inlet of the plate heat exchanger discharges cold acid.

[0027] The "first", "second", "third", "fourth", "fifth", "sixth" and "seventh" in this embodiment are only used for distinction and have no other special meaning. In this embodiment, pumps, valves or flow meters are arranged on the pipelines between the structures as needed.

[0028] 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 self-cleaning primary hydration structure, comprising a filter press, a primary hydration tower, a plate heat exchanger, a primary circulation pool and a primary circulation pump, wherein the primary hydration tower, the plate heat exchanger, the primary circulation pool and the primary circulation pump are connected in sequence through pipelines, and the cold water inlet of the plate heat exchanger is connected to a cooling water supply device through a pipeline with a first valve; the circulation pump is divided into two outputs, one of which is connected to a feed port of the filter press through a pipeline with a second valve, and the other is connected to the primary hydration tower through a pipeline with a third valve; characterized in that, The primary hydration structure also includes an acidic water tank and a second pipeline filter; the filtrate outlet of the filter press is output in two ways, one way is connected to the phosphoric acid storage tank through a pipeline with a fourth valve, and the other way is connected to the cold water inlet of the plate heat exchanger through a pipeline with a fifth valve; the hot water outlet of the plate heat exchanger is output in three ways, the first way is connected to the cooling water supply device through a pipeline with a sixth valve, the second way is connected to the acidic water tank through a pipeline with a seventh valve, and the third way is connected to the primary circulation pool through a pipeline with an eighth valve and the second pipeline filter; the acidic water tank is connected to the tail wash circulation tank of the exhaust gas treatment system through a pipeline.

2. The self-cleanable primary hydration structure according to claim 1, characterized in that: The primary hydration structure also includes a pipeline heater, which is arranged on the pipeline between the filtrate outlet of the filter press and the cold water inlet of the plate heat exchanger.

3. The self-cleanable primary hydration structure according to claim 1, characterized in that: The primary hydration structure also includes a first pipeline filter, which is arranged on the pipeline between the filtrate outlet of the filter press and the cold water inlet of the plate heat exchanger.

4. The self-cleanable primary hydration structure according to claim 1, characterized in that: A temperature sensor or a thermometer is provided on the cold water inlet of the plate heat exchanger, and a pH sensor or a pH meter is provided on the hot water outlet of the plate heat exchanger.

5. The self-cleanable primary hydration structure according to claim 1, characterized in that: The tail wash circulation tank is connected to the secondary circulation pool of the secondary hydration structure through a pipeline, and the secondary circulation pool is connected to the primary circulation pool through a pipeline.

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