CN113184936A - Efficient and energy-saving ammonia distillation deacidification system and method for recycling ammonia nitrogen - Google Patents
Efficient and energy-saving ammonia distillation deacidification system and method for recycling ammonia nitrogen Download PDFInfo
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- CN113184936A CN113184936A CN202110319763.2A CN202110319763A CN113184936A CN 113184936 A CN113184936 A CN 113184936A CN 202110319763 A CN202110319763 A CN 202110319763A CN 113184936 A CN113184936 A CN 113184936A
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/06—Flash evaporation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/043—Details
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/048—Purification of waste water by evaporation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/08—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
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- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
Abstract
The invention discloses a high-efficiency energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen, which comprises a deacidification tower, an ammonia distillation tower, a flash evaporation cylinder and a steam ejector, wherein the top of the deacidification tower is connected with an ammonium sulfate and acid production system, the upper side part of the deacidification tower is provided with an ammonia water inlet, and the lower side part of the deacidification tower is connected with the upper side part of the ammonia distillation tower through a main barren solution pump; the middle upper part of the ammonia still is connected with the middle lower part of the deacidification tower through a valve, and the lateral lower part of the ammonia still is connected with the top of the flash evaporation barrel through an ammonia still wastewater pump; the bottom of the flash evaporation cylinder is connected with a biochemical treatment system through a waste water pump; the injection fluid inlet of the steam injector is connected with the side part of the flash evaporation barrel, the bottom of the steam injector is connected with a steam nozzle in the ammonia still, and the steam nozzle is connected with a low-pressure steam pipeline through a low-pressure steam valve. The invention provides an ammonia distillation deacidification method. The invention adopts the steam jet flash evaporation technology to fully recover the residual ammonia, thereby not only reducing the ammonia content of the wastewater and the working pressure of the biochemical treatment unit, but also reducing the energy consumption.
Description
Technical Field
The invention relates to an efficient energy-saving ammonia distillation deacidification system and method for recovering ammonia nitrogen, and belongs to the technical field of coking.
Background
The ammonia water generated by primarily cooling and purifying the coke oven gas is the main sewage discharged by a coking plant, and in order to prevent the ammonia water from polluting the environment, the ammonia water can be discharged up to the standard after being treated by waste water. The ammonia water has higher ammonia nitrogen concentration and is not beneficial to the treatment of a biochemical treatment system, so the ammonia distillation treatment is carried out before the biochemical treatment, the ammonia in the ammonia water is recovered, and the ammonia content in the ammonia distillation wastewater is reduced. With the increasing of environmental pressure, national wastewater discharge standards are increasingly strict, the pretreatment effect of ammonia water before biochemical wastewater treatment is improved, and the reduction of the ammonia nitrogen content of ammonia distillation wastewater is an important guarantee for reducing biochemical treatment load, improving biochemical treatment effect and realizing ultralow wastewater discharge. However, the existing ammonia distillation process by direct steam heating method generally has the defects of large steam consumption, high ammonia nitrogen content in the wastewater and the like, which not only causes energy waste, but also increases the working pressure of subsequent operation units, so that improvement is necessary.
Disclosure of Invention
The invention aims to provide an efficient and energy-saving ammonia distillation deacidification system and method for recovering ammonia nitrogen aiming at the defects of the prior art so as to improve the pretreatment effect of wastewater, reduce the energy consumption and reduce the working pressure of a subsequent biochemical treatment unit.
In order to achieve the purpose, the invention adopts the following technical scheme:
an efficient energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen comprises a deacidification tower, an ammonia distillation tower, a flash evaporation cylinder and a steam ejector, wherein the top of the deacidification tower is connected with an ammonium sulfate and acid production system through a blow-off valve, an ammonia water inlet is formed in the upper side part of the deacidification tower, and a barren solution outlet in the lower side part of the deacidification tower is connected with a barren solution inlet in the upper side part of the ammonia distillation tower through a main barren solution pump; an ammonia steam outlet at the middle upper part of the ammonia still is connected with an ammonia gas inlet at the middle lower part of the deacidification tower through a valve, and an ammonia still wastewater outlet at the side lower part of the deacidification tower is connected with the top of the flash evaporation barrel through an ammonia still wastewater pump; the bottom of the flash evaporation cylinder is connected with a biochemical treatment system through a waste water pump; the steam fluid inlet at the top of the steam ejector is connected with a medium-pressure steam pipe network through an ejector inlet valve, the ejection fluid inlet at the side part is connected with a volatile ammonia outlet at the side part of the flash evaporation cylinder, the mixed fluid outlet at the bottom is connected with a steam nozzle at the lower part in the ammonia still through an ejector outlet valve, and the steam nozzle is connected with a low-pressure steam pipeline through a low-pressure steam valve.
The high-efficiency energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen further comprises a waste ammonia liquid heat exchanger, a lean ammonia liquid heat exchanger and an auxiliary barren solution pump, ammonia water containing NH3/H2S mixed liquid to be treated is sequentially sent to an ammonia water inlet at the upper part of the deacidification tower side through low-temperature medium channels of the waste ammonia liquid heat exchanger and the lean ammonia liquid heat exchanger, wastewater discharged by the waste water pump enters a biochemical treatment system through a high-temperature medium channel of the waste ammonia liquid heat exchanger, a liquid inlet pipe of the auxiliary barren solution pump is connected with a barren solution outlet at the lower part of the deacidification tower side, and barren solution discharged by a liquid discharge pipe enters a coal gas purification system through a high-temperature medium channel of the barren ammonia liquid heat exchanger.
The high-efficiency energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen is characterized in that two ammonia vapor outlets are arranged at the middle upper part of the ammonia distillation tower, one of the two ammonia vapor outlets is arranged on the top cover and is connected with an ammonia gas inlet at the middle part of the deacidification tower cylinder body through a top ammonia vapor outlet valve, and the other ammonia vapor outlet is arranged at the middle part of the ammonia distillation tower and is connected with an ammonia gas inlet at the bottom of the deacidification tower cylinder body through a middle ammonia vapor outlet valve.
According to the efficient energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen, the steam nozzle at the lower part in the ammonia distillation tower is lower than the steam mixed fluid steam inlet pipeline between the ejector outlet valve and the ammonia distillation tower cylinder.
The high-efficiency energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen is characterized in that the number of the steam ejectors is two, and the two steam ejectors are connected in parallel.
An ammonia distillation deacidification method adopting the ammonia distillation deacidification system comprises a start-up operation method and a stop-up operation method, wherein the start-up operation method comprises the following steps:
a. opening a bleeding valve at the top of the deacidification tower;
b. opening a top ammonia vapor outlet valve and a middle ammonia vapor outlet valve of the ammonia still to be communicated with the deacidification tower;
c. closing other inlet valves of the ammonia still and the deacidification tower;
d. confirming that the injector inlet valve and the injector outlet valve are closed;
e. opening a low-pressure steam valve connected with the ammonia still to send steam to the ammonia still, and feeding the steam discharged from the top and the middle part of the ammonia still into the deacidification tower;
f. the flow of the low-pressure steam is adjusted by changing the opening of a low-pressure steam valve, so that the temperature at the top of the deacidification tower reaches 85 ℃;
g. ammonia water is fed into the deacidification tower, and the flow is adjusted to a specified value from small to large;
h. adjusting the amount of low-pressure steam fed into the ammonia still through a low-pressure steam valve to keep the top temperature of the deacidification tower at 88-92 ℃;
i. when the liquid level in the bottom tank of the deacidification tower reaches 50 percent of the height, starting a main barren solution pump, and sending barren solution to an ammonia still; starting an auxiliary barren solution pump, sending barren solution to a barren ammonia solution heat exchanger, and enabling barren solution subjected to heat exchange in the barren ammonia solution heat exchanger to enter a coal gas purification system;
j. when the liquid level at the bottom of the ammonia still reaches 50 percent of the liquid level, starting an ammonia still wastewater pump, and sending the ammonia still wastewater to a flash evaporation cylinder;
k. when the liquid level of the flash evaporation cylinder rises to a set value, a waste water pump is started, the ammonia distillation waste water is sent to a waste ammonia liquid heat exchanger, and the ammonia distillation waste water enters a waste water accident tank of a biochemical treatment system after heat exchange in the waste ammonia liquid heat exchanger;
opening an inlet valve and an outlet valve of the ejector, and introducing medium-pressure steam;
and m, regulating the flow of the medium-pressure steam through an inlet valve of the ejector and an outlet valve of the ejector to enable the temperature and the pressure in the flash drum to reach normal values.
The shutdown operation method of the ammonia distillation deacidification method comprises the following steps:
n, gradually reducing the steam amount and the barren solution amount entering the ammonia still by controlling a low-pressure steam valve and a main barren solution pump, and stopping feeding ammonia water into the deacidification tower when the steam amount entering the ammonia still is reduced to a set lower limit value;
closing the inlet valve and the outlet valve of the ejector to stop the steam ejector;
p, closing a main barren liquor pump, an auxiliary barren liquor pump, an ammonia distillation wastewater pump and a wastewater pump in sequence;
and q, emptying all equipment and liquid in the pipeline.
The invention adopts the steam jet flash evaporation technology to fully recover the residual ammonia in the wastewater, thereby not only effectively reducing the ammonia content in the ammonia distillation wastewater and lightening the working pressure of a subsequent biochemical treatment unit, but also reducing the steam consumption and reducing the energy consumption.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
FIG. 1 is a schematic structural diagram of an efficient energy-saving ammonia distillation deacidification system and method for recovering ammonia nitrogen.
The reference numbers in the figures are as follows: 1. the system comprises a deacidification tower, a 2 ammonia still, a 3 flash drum, a 4 first steam ejector, a 5 second steam ejector, a 6 waste ammonia liquid heat exchanger, a 7 lean ammonia liquid heat exchanger, a 8 main lean liquid pump, a 9 auxiliary lean liquid pump, a 10 ammonia still waste water pump, a 11 waste water pump, a 12 blow-off valve, a 13 top ammonia vapor outlet valve, a 14 middle ammonia vapor outlet valve, a 15 low-pressure steam valve, a 16 ejector inlet valve, a 17 ejector outlet valve, an 18 ejector and a steam spray head.
Detailed Description
The invention provides a high-efficiency energy-saving ammonia distillation deacidification system and a method for recovering ammonia nitrogen, wherein the system adopts a steam jet flash evaporation technology, and a steam ejector generates a pressure reduction effect to ensure that ammonia distillation wastewater is secondarily evaporated in a flash evaporation cylinder, and part of volatile residual ammonia in the wastewater is recovered, so that the ammonia content of the ammonia distillation wastewater is further reduced, a large amount of latent heat of the ammonia distillation wastewater is recycled to reduce the direct steam consumption, the steam energy consumption is reduced, the wastewater discharge temperature is lower, and the working pressure of a subsequent operation unit is greatly reduced; sensible heat in the wastewater is recovered by adopting an ammonia water heat exchange technology, the fed ammonia water is heated, the heat loss is reduced, and remarkable energy-saving benefit can be obtained. The invention also provides a method for recovering ammonia nitrogen, which has the characteristics of normalized and standardized operation steps and the like, can guide post personnel to carry out scientific operation, shortens the regulation and control time, improves the regulation and control efficiency, and solves the problem of poor ammonia nitrogen recovery effect caused by non-standard operation.
Referring to fig. 1, the high-efficiency energy-saving ammonia distillation deacidification system and method for recovering ammonia nitrogen mainly comprise a deacidification tower 1, an ammonia distillation tower 2, a flash drum 3, a first steam ejector 4, a second steam ejector 5, a waste ammonia liquid heat exchanger 6, a lean ammonia liquid heat exchanger 7, a main lean liquid pump 8, an auxiliary lean liquid pump 9, an ammonia distillation wastewater pump 10 and a wastewater pump 11.
The figure shows that an ammonia water inlet at the upper part of the side surface of a cylinder body of the deacidification tower 1 is connected with an ammonia water outlet containing mixed liquor NH3/H2S from a waste ammonia liquid heat exchanger 6 and a lean ammonia liquid heat exchanger 7; the outlet of the top cover of the deacidification tower 1 is connected with an NH3/H2S mixed gas pipeline of an ammonium sulfate and acid production system through a relief valve 12; the ammonia gas inlet at the middle part of the cylinder of the deacidification tower 1 is connected with a top ammonia gas outlet valve 13 on the top cover of the ammonia still 2 through a pipeline, the ammonia gas inlet at the bottom of the cylinder of the deacidification tower 1 is connected with a middle ammonia gas outlet valve 14 arranged on an ammonia gas outlet at the middle part of the cylinder of the ammonia still 2 through a pipeline, barren solution discharged from a barren solution outlet at the bottom of the side surface of the cylinder of the deacidification tower 1 is divided into two paths, one path is connected with a barren solution inlet pipeline at the top of the side surface of the cylinder of the ammonia still 2 through a main barren solution pump 8, and the other path is connected with an inlet pipeline of a barren solution heat exchanger 7 through an auxiliary barren solution pump 9.
The figure shows that an ammonia still wastewater outlet at the bottom of the side surface of a cylinder body of an ammonia still 2 is connected with an inlet pipeline at the top of a flash evaporation cylinder 3 through an ammonia still wastewater pump 10, and a steam inlet at the bottom of the side surface of the cylinder body of the ammonia still 2 is connected with a low-pressure steam pipeline; a waste water outlet at the bottom of the flash evaporation cylinder 3 is connected with an inlet pipeline of a waste ammonia liquid heat exchanger 6 through a waste water pump 11, and a volatile ammonia outlet at the upper part of the side surface of the cylinder body of the flash evaporation cylinder 3 is connected with injection fluid inlet pipelines at the side surfaces of the first steam injector 4 and the second steam injector 5; the steam fluid inlets of the first steam ejector 4 and the second steam ejector 5 are connected with a medium-pressure steam pipe network through an ejector inlet valve 16, and the mixed fluid outlets at the bottom ends of the first steam ejector 4 and the second steam ejector 5 are connected with a steam mixed fluid inlet pipeline at the bottom of the side surface of the cylinder body of the ammonia still 2 through an ejector outlet valve 17, so that steam is sent to a steam spray head 18 at the lower part in the ammonia still 2.
The figure shows that before entering a feed inlet at the upper part of the side surface of a cylinder body of a deacidification tower 1, the ammonia water of the NH3/H2S mixed solution to be treated firstly flows through a waste ammonia liquid heat exchanger 6 and a lean ammonia liquid heat exchanger 7 in sequence from low to high through a process pipeline to exchange heat with wastewater and lean solution, so as to achieve the purpose of temperature rise and preheating.
The figure shows that high-temperature ammonia gas in the ammonia still 2 enters the deacidification tower 1 through the top ammonia vapor outlet valve 13 and the middle ammonia vapor outlet valve 14 to be used as a heat source for distilling NH3/H2S mixed liquid ammonia water.
The figure shows that a steam mixed fluid steam inlet pipeline connected with a steam inlet at the bottom of a cylinder body of an ammonia still 2 is connected with a low-pressure steam pipeline of a low-pressure steam valve 15 and is connected with mixed fluid outlets at the bottom ends of a first steam ejector 4 and a second steam ejector 5 through an ejector outlet valve 17; the bottom steam nozzle in the cylinder of the ammonia still 2 is lower than the steam mixed fluid steam inlet pipeline by a certain height, so that the ammonia still wastewater at the bottom of the cylinder of the ammonia still 2 is prevented from flowing back to a steam pipe network.
The top and the bottom of the flash drum 3 are semi-spheres; a waste water outlet at the bottom of the flash evaporation cylinder 3 is connected with a waste ammonia liquid heat exchanger 6 through a waste water pump 11, and the waste water is sent to a biochemical treatment system through the waste ammonia liquid heat exchanger 6; and the upper part of the side surface of the flash evaporation cylinder 3 is provided with a volatile ammonia outlet which is connected with injection fluid inlet pipelines of the first steam injector 4 and the second steam injector 5 through flanges.
The liquid level of the ammonia distillation wastewater in the flash evaporation cylinder 3 is lower than a pipeline which is connected with the upper volatile ammonia outlet on the side surface of the flash evaporation cylinder and is connected with the injection fluid inlets of the first steam ejector 4 and the second steam ejector 5.
The steam fluid inlets of the first steam ejector 4 and the second steam ejector 5 are connected with a medium-pressure steam pipe network through flanges, the mixed fluid outlets of the first steam ejector 4 and the second steam ejector 5 are connected with a steam inlet pipeline at the bottom of the side surface of the ammonia still barrel, and the injection fluid inlets of the first steam ejector 4 and the second steam ejector 5 are connected with a volatile ammonia outlet pipeline at the upper part of the flash evaporation barrel through flanges.
The process flow of the high-efficiency energy-saving ammonia distillation deacidification system comprises the following steps:
ammonia water enters from a feed inlet of the deacidification tower 1 after being subjected to heat exchange and temperature rise by the waste ammonia liquid heat exchanger 6 and the lean ammonia liquid heat exchanger 7, high-temperature hot ammonia gas from the ammonia still 2 is used for steam blowing, acid gases such as H2S, HCN and the like in the ammonia water are removed, and the separated acid gases enter ammonium sulfate and acid production procedures of a subsequent operation unit. One part of the barren liquor at the bottom of the deacidification tower 1 is sent to a barren ammonia liquor heat exchanger 7 through an auxiliary barren liquor pump 9, and enters a coal gas purification system of a subsequent operation unit after exchanging heat with ammonia water and reducing temperature; the other part is sent to a feed inlet at the top of the ammonia still 2 by a main barren liquor pump 8, steam introduced from the bottom of the ammonia still is used as a heat source to directly distill barren liquor, and ammonia enters the deacidification tower 1 from the top of the ammonia still 2 to the middle of the deacidification tower 1 and from the middle of the ammonia still 2 to the bottom of the deacidification tower 1 and is used as a distillation heat source of ammonia water in the deacidification tower 1. The ammonia distillation wastewater from which NH3 is removed at the bottom of the ammonia still 2 is sent to the flash evaporation cylinder 3 through the ammonia distillation wastewater pump 10 for secondary evaporation, the operating pressure in the flash evaporation cylinder 3 is controlled by medium-pressure steam in the first steam ejector 4 and the second steam ejector 5, the secondary steam at the top of the flash evaporation cylinder 3 is mixed with the low-pressure steam through the first steam ejector 4 and the second steam ejector 5, and then is sent to the bottom of the ammonia still 2 for ammonia distillation, and the wastewater at the bottom of the flash evaporation cylinder 3 is sent to the waste ammonia liquid heat exchanger 6 through the wastewater pump 11 for heat exchange and temperature reduction and then enters a biochemical wastewater treatment system of a subsequent operation unit.
The recycling of the secondary steam is mainly completed by a first steam ejector 4 and a second steam ejector 5. The medium-pressure steam enters the first steam ejector 4 and the second steam ejector 5, kinetic energy is converted into steam static pressure energy at the nozzle position of the steam ejector, the nozzle position generates a suction pressure reduction effect, secondary steam containing volatile ammonia gas in the flash evaporation cylinder 3 is sucked, the secondary steam is mixed with low-pressure steam after energy conversion and enters the ammonia still to evaporate ammonia, and the secondary steam is recycled, so that the direct steam quantity is saved.
A method for recovering ammonia nitrogen by using the ammonia distillation deacidification system comprises a start-up operation method and a shutdown operation method, wherein the start-up operation method comprises the following steps:
preparation before start-up:
a. opening a bleeding valve 12 at the top of the deacidification tower 1;
b. opening a top ammonia steam outlet valve 13 and a middle ammonia steam outlet valve 14 of the ammonia still 2 to communicate with the deacidification tower 1;
c. closing other inlet valves of the ammonia still 2 and the deacidification tower 1;
d. confirm that the injector inlet valve 16, the injector outlet valve 17 are closed;
preheating a tower body:
e. opening a low-pressure steam valve 15 connected with the ammonia still 2, sending a small amount of steam to the ammonia still 2 through a steam regulating valve 15, and feeding the steam discharged from the top and the middle of the ammonia still 2 into the deacidification tower 1;
f. the flow of the low-pressure steam is adjusted by changing the opening of the low-pressure steam valve 15, and the temperature is increased at the speed of 10 ℃/h, so that the temperature at the top of the deacidification tower 1 reaches 85 ℃;
starting operation:
g. ammonia water is fed into the deacidification tower 1, and the flow is adjusted to a specified value from small to large;
h. the amount of low-pressure steam sent into the ammonia still 2 is adjusted through a low-pressure steam valve 15, so that the top temperature of the deacidification tower 1 is kept at 88-92 ℃;
i. when the liquid level in the bottom tank of the deacidification tower 1 reaches 50 percent of the height, starting a main barren solution pump 8, and sending barren solution to an ammonia still 2; starting an auxiliary barren solution pump 9, sending barren solution to a barren ammonia solution heat exchanger 7, and enabling barren solution subjected to heat exchange in the barren ammonia solution heat exchanger 7 to enter a coal gas purification system;
j. when the liquid level at the bottom of the ammonia still 2 reaches 50 percent of the liquid level, starting an ammonia still wastewater pump 10, and sending the ammonia still wastewater to a flash evaporation cylinder 3;
k. when the liquid level of the flash drum 3 rises to a set value, starting a waste water pump 11, sending the ammonia distillation waste water to a waste ammonia heat exchanger 6, and allowing the ammonia distillation waste water to enter a waste water accident tank after heat exchange in the waste ammonia heat exchanger 6;
opening an injector inlet valve 16 and an injector outlet valve 17, and slowly introducing medium-pressure steam;
m, regulating the flow of the medium-pressure steam through an injector inlet valve 16 and an injector outlet valve 17 to enable the temperature and the pressure in the flash drum 3 to reach normal values;
the shutdown operation method comprises the following steps:
n, gradually reducing the steam amount and the barren liquor amount entering the ammonia still 2 by controlling the low-pressure steam valve 15 and the main barren liquor pump 8, and stopping feeding ammonia water into the deacidification tower 1 when the steam amount entering the ammonia still 2 is reduced to a set lower limit value (close to zero);
o. closing the injector inlet valve 16, the injector outlet valve 17, stopping the operation of the first steam injector 4 and the second steam injector 5;
p, closing a main barren liquor pump 8, an auxiliary barren liquor pump 9, an ammonia distillation wastewater pump 10 and a wastewater pump 11 in sequence;
and q, emptying all equipment and liquid in the pipeline.
An embodiment of the high-efficiency energy-saving ammonia distillation deacidification system and method for recovering ammonia nitrogen of the invention is as follows:
the deacidification tower 1 is a stainless steel floating valve tray tank body with the diameter of 2200mm and the height of 11241 mm; a steel pipe with the diameter of 200mm and the wall thickness of 6mm is selected as a process pipeline connected with a feed inlet at the upper part of the side surface of the deacidification tower 1 and ammonia water inlets and outlets of the waste ammonia liquid heat exchanger 6 and the lean ammonia liquid heat exchanger 7, and ammonia water sequentially flows into the waste ammonia liquid heat exchanger 6 and the lean ammonia liquid heat exchanger 7 through the process pipeline from low to high according to the heat exchange temperature of the waste water and the lean solution to exchange heat with the waste water and the lean solution for heating; a steel pipe with the diameter of 500 mm and the wall thickness of 10mm is selected as an NH3/H2S mixed gas outlet process pipeline at the top of the deacidification tower 1 and is connected with a process pipeline of an ammonium sulfate feeding and acid making production system; a steel pipe with the diameter of 300 mm and the wall thickness of 8mm is selected as a process pipeline for connecting an air inlet in the middle of the deacidification tower 1 and an ammonia gas outlet in the top cover of the ammonia still 2; a steel pipe with the diameter of 300 mm and the wall thickness of 8mm is selected as a process pipeline for connecting an air inlet at the bottom of the deacidification tower 1 and an ammonia gas outlet at the middle part of the ammonia still 2; a steel pipe with the diameter of 150 mm and the wall thickness of 6mm is selected as a process pipeline connected with an outlet at the bottom of the side surface of the deacidification tower 1 and a barren solution inlet at the top of the side surface of the ammonia still 2 through a barren solution pump 8; and a steel pipe with the diameter of 200mm and the wall thickness of 6mm is selected as the other path of the barren solution at the bottom outlet of the side surface of the deacidification tower 1 and the process pipeline connected with the inlet of the barren ammonia solution heat exchanger 7 through the barren solution pump 9.
The upper section of the ammonia still 2 selects 50#, 317L pall rings and rectangular saddle ring packing sections with the diameter of 2200mm and the height of 3000mm, and a layer of steel plate mesh with the diameter of 2050mm is added above the packing; the lower section of the tower tray section is a cast iron blister tower tray section tank body with the diameter of 3000mm and the height of 16410 mm; a process pipeline connected with an ammonia distillation wastewater outlet at the bottom of the side surface of the ammonia distillation tower 2 and an inlet at the top of the flash evaporation cylinder 3 through an ammonia distillation wastewater pump 10 is a steel pipe with the diameter of 200mm and the wall thickness of 6 mm; a steam inlet at the bottom of the side surface of the ammonia still 2 is connected with a low-pressure steam pipeline, and a steel pipe with the diameter of 400 mm and the wall thickness of 12mm is selected as a technological pipeline; the outlet process pipelines of the mixed fluids at the bottom ends of the first steam ejector 4 and the second steam ejector 5 are steel pipes with the diameter of 200mm and the wall thickness of 5 mm.
The flash evaporation cylinder 3 is an upper and lower semi-circular cast iron tank body with the diameter of 900 mm and the height of 1950 mm; a wastewater outlet at the bottom of the flash drum 3 is connected with an inlet of the waste ammonia liquid heat exchanger 6 through a wastewater pump 11, and a steel pipe with the diameter of 200mm and the wall thickness of 6mm is selected as a process pipeline; the upper volatile ammonia outlet on the side surface of the flash drum 3 is connected with the first steam ejector 4 and the second steam ejector 5 through injection fluid inlets, and steel pipes with the diameter of 100 mm and the wall thickness of 5mm are selected as process pipelines.
The diameter of the first steam ejector 4 is 200mm, and the diameter of the second steam ejector 5 is 150 mm; a steam fluid inlet of the first steam ejector 4 is connected with a medium-pressure steam inlet pipe network, a steel pipe with the diameter of 200mm and the wall thickness of 5mm is selected as a process pipeline, a mixed fluid outlet process pipeline at the bottom end of the first steam ejector 4 is selected as a steel pipe with the diameter of 200mm and the wall thickness of 5mm, the mixed fluid outlet process pipeline is connected with a steam inlet process pipeline at the bottom of the side surface of the ammonia still 2, and a side surface injection fluid inlet of the first steam ejector 4 is connected with a volatile ammonia outlet pipeline at the upper part of the flash drum 3; the steam fluid inlet of the second steam ejector 5 is connected with the medium-pressure steam inlet pipe network through a process pipeline, the diameter of the process pipeline is 150 mm, the wall thickness of the process pipeline is 5mm, the process pipeline is connected with the steam inlet process pipeline at the bottom of the side face of the ammonia still 2, and the side face injection fluid inlet of the second steam ejector 5 is connected with the volatile ammonia outlet pipeline at the upper portion of the flash evaporation cylinder 3.
The waste ammonia liquid heat exchanger 6 adopts 2 stainless steel heat exchangers with heat exchange area of 45 square meters per unit; the poor ammonia liquid heat exchanger 7 adopts 2 titanium heat exchangers with heat exchange area of 60 square meters per square meter.
The flow rate of the main barren liquor pump 8 is 150m3/h, the lift is 56 m, and the power of the motor is 37 kw; the flow rate of the secondary barren liquor pump 9 is 150m3/h, the lift is 56 m, and the power of the motor is 45 kw.
The flow rate of the ammonia distillation wastewater pump 10 is 173.5m3/h, the lift is 28 m, and the power of the motor is 22 kw; the flow rate of the waste water pump 11 is 265m3/h, the head is 64 m, and the power of the motor is 30 kw.
Claims (7)
1. An efficient energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen is characterized by comprising a deacidification tower (1), an ammonia distillation tower (2), a flash drum (3) and a steam ejector, wherein the top of the deacidification tower (1) is connected with an ammonium sulfate and acid production system through a blow-off valve (12), an ammonia water inlet is formed in the upper side part of the deacidification tower, and a barren solution outlet in the lower side part of the deacidification tower is connected with a barren solution inlet in the upper side part of the ammonia distillation tower (2) through a main barren solution pump (8); an ammonia steam outlet at the middle upper part of the ammonia still (2) is connected with an ammonia gas inlet at the middle lower part of the deacidification tower (1) through a valve, and an ammonia still wastewater outlet at the side lower part is connected with the top of the flash evaporation cylinder (3) through an ammonia still wastewater pump (10); the bottom of the flash evaporation cylinder (3) is connected with a biochemical treatment system through a waste water pump (11); a steam fluid inlet at the top of the steam ejector is connected with a medium-pressure steam pipe network through an ejector inlet valve (16), an injection fluid inlet at the side is connected with a volatile ammonia outlet at the side of the flash drum (3), a mixed fluid outlet at the bottom is connected with a steam spray head (18) at the inner lower part of the ammonia still (2) through an ejector outlet valve (17), and the steam spray head (18) is connected with a low-pressure steam pipeline through a low-pressure steam valve (15).
2. The high-efficiency energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen according to claim 1, which is characterized by further comprising a waste ammonia liquid heat exchanger (6), a lean ammonia liquid heat exchanger (7) and an auxiliary lean liquid pump (9), ammonia water containing NH3/H2S mixed liquid to be treated is sequentially sent to an ammonia water inlet at the upper part of the deacidification tower (1) side through low-temperature medium channels of the waste ammonia liquid heat exchanger (6) and the lean ammonia liquid heat exchanger (7), wastewater discharged by a wastewater pump (11) enters a biochemical treatment system through a high-temperature medium channel of the waste ammonia liquid heat exchanger (6), a liquid inlet pipe of the auxiliary lean liquid pump (9) is connected with a lean liquid outlet at the lower part of the deacidification tower (1), and lean liquid discharged by a liquid discharge pipe enters a coal gas purification system through a high-temperature medium channel of the lean ammonia liquid heat exchanger (7).
3. The high-efficiency energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen according to claim 2, wherein two ammonia gas outlets are arranged at the middle upper part of the ammonia distillation tower (2), one of the two ammonia gas outlets is arranged on the top cover and is connected with the ammonia gas inlet at the middle part of the cylinder body of the deacidification tower (1) through a top ammonia gas outlet valve (13), and the other ammonia gas outlet is arranged at the middle part of the cylinder body of the ammonia distillation tower (2) and is connected with the ammonia gas inlet at the bottom of the cylinder body of the deacidification tower (1) through a middle ammonia gas outlet valve (14).
4. An efficient and energy-saving ammonia distillation deacidification system for recovering ammonia nitrogen according to claim 3, wherein a steam spray head (18) at the inner lower part of the ammonia distillation tower (2) is lower than a steam mixed fluid steam inlet pipeline between an injector outlet valve (17) and a cylinder body of the ammonia distillation tower (2).
5. The system as claimed in claim 4, wherein two steam ejectors are provided, and the two steam ejectors are connected in parallel.
6. A method for deacidifying ammonia by distillation using the system of any one of claims 3 to 5, wherein said method comprises a start-up operation method and a shut-down operation method, said start-up operation method comprising the steps of:
a. opening a bleeding valve (12) at the top of the deacidification tower (1);
b. opening a top ammonia steam outlet valve (13) and a middle ammonia steam outlet valve (14) of the ammonia still (2) to be communicated with the deacidification tower (1);
c. closing other inlet valves of the ammonia still (2) and the deacidification tower (1);
d. confirming that the injector inlet valve (16) and the injector outlet valve (17) are closed;
e. opening a low-pressure steam valve (15) connected with the ammonia still (2) to send steam to the ammonia still (2), and feeding the steam discharged from the top and the middle of the ammonia still (2) into the deacidification tower (1);
f. the flow of the low-pressure steam is adjusted by changing the opening of the low-pressure steam valve (15), so that the temperature at the top of the deacidification tower (1) reaches 85 ℃;
g. ammonia water is fed into the deacidification tower (1), and the flow is adjusted to a specified value from small to large;
h. the amount of low-pressure steam sent into the ammonia still (2) is adjusted through a low-pressure steam valve (15), so that the top temperature of the deacidification tower (1) is kept at 88-92 ℃;
i. when the liquid level in the bottom tank of the deacidification tower (1) reaches 50% of the height, starting a main barren solution pump (8) and sending barren solution to an ammonia still (2); starting an auxiliary barren solution pump (9), sending barren solution to a barren ammonia solution heat exchanger (7), and enabling barren solution after heat exchange in the barren ammonia solution heat exchanger (7) to enter a coal gas purification system;
j. when the liquid level at the bottom of the ammonia still (2) reaches 50 percent of the liquid level, starting an ammonia still wastewater pump (10) and sending the ammonia still wastewater to a flash evaporation cylinder (3);
k. when the liquid level of the flash evaporation cylinder (3) rises to a set value, a waste water pump (11) is started, the ammonia distillation waste water is sent to a waste ammonia liquid heat exchanger (6), and the ammonia distillation waste water enters a waste water accident tank of a biochemical treatment system after heat exchange in the waste ammonia liquid heat exchanger (6);
opening an injector inlet valve (16) and an injector outlet valve (17) and introducing medium-pressure steam;
and m, regulating the flow of the medium-pressure steam through an injector inlet valve (16) and an injector outlet valve (17) to enable the temperature and the pressure in the flash drum (3) to reach normal values.
7. The method of deacidification by ammonia distillation according to claim 6, wherein said shutdown operation method comprises the following steps:
n, gradually reducing the steam amount and the barren liquor amount entering the ammonia still (2) by controlling a low-pressure steam valve (15) and a main barren liquor pump (8), and stopping feeding ammonia water into the deacidification tower (1) when the steam amount entering the ammonia still (2) is reduced to a set lower limit value;
o. closing the injector inlet valve (16), the injector outlet valve (17) to stop the steam injector from operating;
p, closing a main barren liquor pump (8), an auxiliary barren liquor pump (9), an ammonia distillation wastewater pump (10) and a wastewater pump (11) in sequence;
and q, emptying all equipment and liquid in the pipeline.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114772611A (en) * | 2022-03-18 | 2022-07-22 | 宣化钢铁集团有限责任公司 | Production system and method for preparing ammonium sulfate from ammonia acid-containing steam |
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| DE2444201A1 (en) * | 1973-09-21 | 1975-04-10 | Erap | METHOD AND DEVICE FOR GAS EXTRACTION |
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| CN114772611B (en) * | 2022-03-18 | 2023-10-27 | 宣化钢铁集团有限责任公司 | Production system and method for preparing ammonium sulfate from ammonia-containing gas |
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