CN111530237A - Ammonia recovery structure and ammonia recovery method in fly ash maintenance workshop - Google Patents

Abstract

The invention provides an ammonia gas recovery structure and an ammonia gas recovery method for a fly ash curing workshop, which can ensure the health of production personnel in the workshop, reduce the corrosion of equipment in the workshop, recycle ammonia gas and reduce secondary pollution. An ammonia gas detector is arranged in the fly ash curing workshop; a collecting air pipe arranged in the fly ash curing workshop is connected with the washing tower; a first-stage filling section, a first-stage spraying section, a second-stage filling section, a second-stage spraying section and a demisting plate are sequentially arranged in the washing tower from bottom to top; the liquid storage tank is connected with a spray water pipe through a circulating pump, and the spray water pipe is connected with the first-stage spray section and the second-stage spray section; the demineralized water input pipeline is connected with the liquid storage tank; the washing tower is connected with an inlet of a centrifugal fan, and the centrifugal fan is connected with a fly ash curing workshop; the liquid reserve tank is connected with the demineralized water pump, and the demineralized water pump is connected with the filter, and the filter links to each other with the demineralized water tank, and the demineralized water tank links to each other with the transfer pump, and the transfer pump links to each other with SNCR system softened water tank.

Description

Ammonia recovery structure and ammonia recovery method in fly ash maintenance workshop

technical field

The invention relates to an ammonia gas recovery structure and an ammonia gas recovery method in a fly ash curing workshop, which are mainly used in the fly ash curing workshop of a domestic waste incineration plant.

Background technique

In recent years, my country's garbage production has been increasing day by day. If a large amount of municipal solid waste is not treated effectively, it will cause serious pollution to the urban ecological environment and the surrounding water, air, soil, etc. Therefore, many garbage incineration plants are also constructed accordingly. stand up. The fly ash produced by waste incineration is hazardous waste and contains a large amount of heavy metals, which is extremely harmful to the human body and the environment. Therefore, it is necessary to stabilize the heavy metals in the fly ash to make it meet the landfill standard before landfilling.

Since ammonia water or urea is usually used to destock the flue gas in the flue gas purification process of waste incineration, a large amount of ammonia is adsorbed in the fly ash pore structure, and the excess ammonia is also used in the fly ash semi-dry desulfurization process. It will generate heavy metal ammonia salt compounds; and most of the fly ash heavy metal stabilizing agents currently used in China are dithiocarbamate substances. After the contact, the residual ammonia in the fly ash or the ammonia salt generated in the treatment of the fly ash flue gas will be reacted or replaced, so that the ammonia is freed and spilled into the air. In addition, the fly ash stabilizer will also decompose and release ammonia gas.

In many waste incineration plants, the fly ash is chelated in the incineration room and then transferred to the fly ash maintenance workshop for storage, maintenance, sampling and testing. A large amount of stabilized fly ash is stored in the fly ash maintenance workshop, resulting in ammonia smell in the fly ash maintenance workshop. It is very thick, beyond the acceptable range of the human body, so that many operators will be hurt by the irritating gas in the eyes and nose, and suffer from respiratory mucosal diseases. In addition, the ammonia content is too high, and there are certain safety hazards.

In the prior art, dilute acid is often used to neutralize the ammonia gas in the fly ash curing workshop. Although this method can efficiently remove the ammonia gas, it consumes dilute acid resources, and the generated acid-containing wastewater needs further treatment.

In order to solve the ammonia problem in the fly ash maintenance workshop, ensure the health of the production personnel in the workshop, reduce the corrosion of the equipment in the workshop, and consider the recycling of ammonia gas to reduce secondary pollution, it is urgent to design and develop a fly ash maintenance Ammonia recovery technology in workshop.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the above-mentioned deficiencies existing in the prior art, and to provide an ammonia recovery structure and an ammonia recovery method in a fly ash maintenance workshop with a reasonable structural design, to ensure the health of the production personnel in the workshop, and to reduce the number of workshops. Corrosion of internal equipment, ammonia can be recycled to reduce secondary pollution.

The technical scheme adopted by the present invention to solve the above problems is: an ammonia recovery structure for a fly ash curing workshop, including a fly ash curing workshop and a SNCR system soft water tank, and is characterized in that: it also includes a collection air duct, a demineralized water input pipeline, Washing tower, liquid storage tank, first-stage packing section, first-stage spray section, second-stage packing section, second-stage spray section, defogging plate, washing tower outlet air duct, centrifugal fan, exhaust air duct , circulating pump, spray pipe, demineralized water pump, filter, demineralized water tank and transfer pump; Ammonia gas detector is installed in the fly ash maintenance workshop; The air inlets at the bottom of the washing tower are connected; the collecting air duct is provided with an air suction port; the interior of the washing tower is sequentially provided with a first-stage packing section, a first-stage spray section, a second-stage packing section, and a second-stage spray section from bottom to top. Shower section, demisting plate; there is a liquid storage tank at the bottom of the washing tower, the liquid storage tank is connected with the spray water pipe through the circulating pump, and the spray water pipe is connected with the first-stage spray section and the second-stage spray section; desalinated water input The pipeline is connected with the liquid storage tank; the upper exhaust port of the washing tower is connected with the inlet of the centrifugal fan through the outlet air duct of the washing tower, and the outlet of the centrifugal fan is connected with the fly ash maintenance workshop through the exhaust air duct; the liquid storage tank is connected with the inlet of the demineralized water pump , The outlet of the desalinated water pump is connected to the inlet of the filter, the outlet of the filter is connected to the inlet of the desalted water tank, the outlet of the desalted water tank is connected to the inlet of the transfer pump, and the outlet of the transfer pump is connected to the inlet of the soft water tank of the SNCR system.

The bottom of the washing tower of the present invention is equipped with a blowdown valve.

The packing in the first-stage packing section and the second-stage packing section of the present invention adopts plastic stepped ring packing.

Both the first-stage spray section and the second-stage spray section of the present invention are provided with liquid distributors.

The defogging plate of the present invention adopts a Pall ring water blocking layer structure.

The washing tower of the present invention is provided with monitoring windows and inspection manholes.

The exhaust air duct of the present invention is provided with a gas detector.

The liquid storage tank at the bottom of the washing tower of the present invention is provided with a floating ball valve.

The invention also includes a DCS control system, which is connected with an ammonia gas detector, an ammonia gas alarm device, a washing tower, a circulating pump, a centrifugal fan, a demineralized water pump and a transfer pump.

A method for recovering ammonia gas in a fly ash maintenance workshop, characterized in that: using the above-mentioned ammonia gas recovery structure to carry out, the steps are:

When the ammonia gas detector in the fly ash curing workshop senses that the ammonia gas exceeds the set value, the ammonia-containing air in the fly ash curing workshop is introduced into the air inlet at the bottom of the washing tower through the collecting air duct; The upper one passes through the first-stage packing section, the first-stage spray section, the second-stage packing section, and the second-stage spray section, while the demineralized water passes through the first-stage spray section and the second-stage spray section. The liquid distributor is evenly sprayed into the packing layer of the packing section and flows down along the surface of the packing layer; during the countercurrent contact, the ammonia gas in the ammonia-containing air is completely dissolved in water, and drops to In the liquid storage tank of the washing tower; the purified air rises to the defogging plate to remove the water mist, and then is transported back to the fly ash maintenance workshop through the centrifugal fan; the ammonia-containing demineralized water in the liquid storage tank is pressurized by the circulating pump and then transported to the fly ash maintenance workshop. The spray water pipe is then sent to the first-stage spray section and the second-stage spray section through the spray water pipe. After reacting with ammonia gas, it is returned to the liquid storage tank for recycling; when the recycled ammonia-containing demineralized water cannot meet the design requirements After the treatment effect is achieved, the ammonia-containing demineralized water is transported to the demineralized water tank through the demineralized water pump, and then sent to the soft water tank of the SNCR system through the transfer pump; Add fresh demineralized water.

Compared with the prior art, the present invention has the following advantages and effects: reasonable structure design, no need to use chemical agents, safe operation, advanced technology, high reliability, space saving, easy installation and maintenance, high efficiency and energy saving, and ensure the safety of the workshop. The health of the production staff can reduce the corrosion of equipment in the workshop, and the ammonia gas can be recycled to reduce secondary pollution.

Description of drawings

FIG. 1 is a schematic structural diagram of an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and through the examples. The following examples are to explain the present invention and the present invention is not limited to the following examples.

1, the present invention includes a fly ash maintenance workshop 1, a collection air duct 2, a demineralized water input pipeline 3, a washing tower 4, a liquid storage tank 5, a first-stage packing section 6, a first-stage spray section 7, a second stage Stage packing section 8, second-stage spray section 9, defogging plate 10, washing tower outlet air duct 11, centrifugal fan 12, exhaust air duct 13, circulating pump, spray water pipe 16, demineralized water pump 17, filter 18. Demineralized water tank 19, transfer pump 20, SNCR system soft water tank 21 and DCS control system.

The fly ash maintenance workshop 1 is equipped with an ammonia gas detector and an ammonia gas alarm device. When the ammonia gas in the fly ash maintenance workshop 1 exceeds the set value, the ammonia gas detector will send a signal to the DCS control system, so that the washing tower 4, the circulating pump and the centrifugal fan 12 will operate.

A collection air duct 2 is installed on the top of the fly ash curing workshop 1 , and the collection air duct 2 is connected to the air inlet at the bottom of the washing tower 4 . The collecting air duct 2 is provided with seven air extraction ports 21 , the air extraction ports 21 are located at the top of the fly ash curing workshop 1 , and the diameter of each air extraction port 21 is about 600 mm. The diameter of the collecting air duct 2 is arranged in a stepped shape, and a 30×30mm filter screen is installed at each air outlet 21 to prevent the inhalation of debris. The collecting air duct 2 is designed with a certain slope to prevent the accumulation of condensed water in the pipeline, and a drain valve is installed at the lowest end of the pipeline. The collecting air duct 2 is made of glass fiber reinforced plastic, which has good corrosion resistance. Because the specific gravity of ammonia gas is relatively light, the collecting air duct 2 is located at the top of the fly ash curing workshop, which is helpful for gas discharge.

Inside the washing tower 4, a first-stage packing section 6, a first-stage spray section 7, a second-stage packing section 8, a second-stage spray section 9, and a demisting plate 10 are sequentially arranged from bottom to top.

The bottom of the washing tower 4 is provided with a liquid storage tank 5, and the liquid storage tank 5 is connected with a spray water pipe 16 through a circulating pump, and the spray water pipe 16 is connected with the first-stage spray section 7 and the second-stage spray section 9; the circulating pump is Two sets are the No. 1 circulating pump 14 and the No. 2 circulating pump 15 respectively, and the No. 1 circulating pump 14 and the No. 2 circulating pump 15 are arranged in parallel. In this way, the spray system inside the washing tower 4 has a self-circulation function, and the spray liquid of the liquid storage tank 5 is pressurized by the No. 1 circulating pump 14 or the No. 2 circulating pump 15 and then sent to the spray water pipe 16, and then passes through the spray water pipe 16. It is sent to the first-stage spraying section 7 and the second-stage spraying section 9, and after reacting with ammonia gas, it is returned to the bottom of the tower for recycling.

The demineralized water input pipeline 3 is connected with the inlet of the liquid storage tank 5 .

The upper exhaust port of the washing tower 4 is connected to the inlet of the centrifugal fan 12 through the outlet air duct 11 of the washing tower, and the outlet of the centrifugal fan 12 is connected to the bottom of the fly ash curing workshop 1 through the exhaust air duct 13 .

The outlet of the liquid storage tank 5 is connected with the inlet of the demineralized water pump 17, the outlet of the demineralized water pump 17 is connected with the inlet of the filter 18, the outlet of the filter 18 is connected with the inlet of the demineralized water tank 19, and the outlet of the demineralized water tank 19 is connected with the inlet of the transfer pump 20, The outlet of the transfer pump 20 is connected to the inlet of the soft water tank 21 of the SNCR system.

The body material of washing tower 4 is made of plexiglass FRP, which has strong anti-corrosion performance. The bottom of the washing tower 4 is equipped with a blowdown valve for regular blowdown.

The packing in the first-stage packing section 6 and the second-stage packing section 8 adopts plastic stepped ring packing, and a packing support plate is installed at the bottom of the packing layer, and the support plate adopts a grid plate type support plate. After the packing of the packing section is full, install the packing to press the grid plate above it, so as to avoid the packing from loosening and beating under the action of air flow.

The first-stage spraying section 7 and the second-stage spraying section 9 are provided with liquid distributors, and the liquid distributor adopts a pipe-type sprayer, which can provide sufficiently uniform liquid distribution and emptying. Large enough gas channel. The spray liquid enters the pipe-type sprayer through the horizontal section of the spray water pipe 16, and sprays to the packing layer through the small holes on the branch pipes.

The defogging plate 10 adopts a Pall ring water blocking layer structure, which is used to remove the droplets in the air flow of the air outlet, and prevent the ammonia gas from dissolving in water to generate foam and discharge with the air flow, which affects the efficiency of the scrubber absorbing ammonia gas.

The washing tower 4 is provided with monitoring windows and manholes for inspection, so that personnel can monitor whether the working condition of the washing tower is normal and replace the aging packing in time.

The centrifugal fan 12 is made of glass fiber reinforced plastic, which can transport the air filtered by the washing tower to the exhaust air duct 13 . The centrifugal fan 12 can realize variable frequency operation and be connected to the DCS system.

The exhaust air duct 13 is provided with a gas detector, and the discharged gas should meet the ammonia emission standard in Table 2 of the "Emission Standard for Odor Pollutants" GB14554-1993.

The spray liquid of the washing tower 4 is demineralized water, and the demineralized water comes from the water chemical workshop of the waste incineration plant. The liquid storage tank at the bottom of the washing tower is provided with a floating ball valve, which can automatically realize the water replenishment function according to the level of the desalted water in the liquid storage tank.

The demineralized water pump 17 is located near the washing tower 4 and is made of stainless steel SUS304. It is used to transport the ammonia-containing demineralized water in the washing tower to the demineralized water tank 19. The demineralized water pump 17 can automatically start and stop according to the liquid level in the demineralized water tank 19. .

The filtration precision of the filter 18 is 80 meshes, and is used to filter the demineralized water delivered by the demineralized water pump 17 .

The desalted water tank 19 is made of SUS304 material and should be tightly sealed. The desalted water tank 19 is equipped with an online water quality analysis instrument. If the water quality of the desalted water is unqualified, the front section of the desalted water tank will be cut off, and the process equipment such as the washing tower and the desalted water pump needs to be cleaned and maintained. A drain valve is installed at the bottom of the demineralized water tank to drain regularly.

The transfer pump 20 and the soft water tank 21 of the SNCR system are also made of SUS304 material. The bottom of the soft water tank 21 of the SNCR system is equipped with a blowdown valve for regular blowdown.

The DCS control system is connected with the ammonia gas detector, the ammonia gas alarm device, the washing tower 4, the circulating pump, the centrifugal fan 12, the demineralized water pump 17, and the transfer pump 20. The DSC control system can realize the unmanned automatic operation function of the whole system. The start, stop and fault alarms of pumps and fans have remote monitoring and operation; the start, stop and fault alarms and currents of the entire set of ammonia recovery equipment have DCS monitoring and operation functions; the water tanks and pumps are equipped with high and low liquid level alarms and pump interlocking When the device is put into operation, the liquid level, flow and other parameters of the system are equipped with a monitoring system, which can be recorded and continuously monitored. In short, to ensure the continuous and reliable operation of the entire ammonia recovery and treatment system.

An ammonia recovery structure and an ammonia recovery method in a fly ash curing workshop, the steps are:

The principle of ammonia gas recovery is to use ammonia gas that is very soluble in water, with a solubility of 1:700. The reaction of ammonia gas and water will generate monohydrate ammonia: NH ₃ +H ₂ O→NH ₃ .H ₂ O.

When the ammonia gas detector in fly ash curing workshop 1 senses that the ammonia gas exceeds the set value, it will send a signal to the DCS control system, and the ammonia gas recovery device will operate through the DCS control system. The air is introduced into the bottom air inlet of the washing tower 4 through the collecting air duct 2; the ammonia-containing air passes through the first-stage packing section 6, the first-stage spray section 7, and the second-stage packing section 8 from bottom to top in the washing tower. , the second-stage spray section 9, and the demineralized water is uniformly sprayed into the packing layer of the packing section through the liquid distributor in the first-stage spray section 7 and the second-stage spray section 9, along the surface of the packing layer Downflow; ammonia-containing air is in countercurrent contact with the demineralized water flowing down from the top of the washing tower. In the process of countercurrent contact, on the surface of the packing, the ammonia gas and the demineralized water react chemically. Under the action of the packing, the ammonia-containing air The ammonia gas is completely soluble in water, and descends into the liquid storage tank 5 of the washing tower with the desalinated water, and when the desalted water is sprayed out at high speed in the spray section, numerous tiny mist droplets will be formed, which are fully mixed with the ammonia gas contact to further absorb ammonia; the purified air mechanically rises to the defogging plate 10, the water mist mixed in the air is removed by the defogging plate 10, and then sent back to the fly ash curing workshop 1 through the centrifugal fan 12; in the liquid storage tank The ammonia-containing demineralized water in It is recycled to the liquid storage tank 5; when the recycled ammonia-containing demineralized water cannot achieve the designed treatment effect, the ammonia-containing demineralized water is transported to the demineralized water tank 19 through the demineralized water pump 17, and then sent to the SNCR system soft water through the transfer pump 20. When the liquid level of the liquid storage tank 5 is lowered to the design value, fresh demineralized water is added through the demineralized water input pipeline 3.

Demineralized water is used as ammonia spray water. If the ammonia-containing process water formed by absorbing ammonia gas with general process water, the hardness is too high, and the precipitation of calcium and magnesium ions in the prepared ammonia solution will cause scaling and blockage of pipelines in the SNCR system.

The ammonia-containing demineralized water is mixed with the ammonia solution in the SNCR system, and the ammonia solution is diluted to the required concentration for flue gas denitrification. The SNCR method (selective non-catalytic reduction method) is to inject ammonia water into the flue gas, and in the high temperature (900-1100 ℃) region, the ammonia water reacts with NOx to reduce it to N2 and H2O to achieve the purpose of removing NOx. The reaction principle is:

4NH ₃ +4NO+O ₂ → 4N ₂ +6H2O

4NH ₃ +2NO ₂ +O ₂ → 3N ₂ +6H2O.

In addition, it should be noted that the specific embodiments described in this specification may have different shapes and names of parts and components, and the above content described in this specification is only an illustration of the structure of the present invention. All equivalent changes or simple changes made according to the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or substitute in similar manners, as long as they do not deviate from the structure of the present invention or go beyond the scope defined by the claims, All should belong to the protection scope of the present invention.

Claims (10)

1. a kind of ammonia recovery structure of fly ash maintenance workshop, comprise fly ash maintenance workshop and SNCR system soft water tank, it is characterized in that: also comprise collection air duct, demineralized water input pipeline, washing tower, liquid storage tank, first level Packing section, first-stage spray section, second-stage packing section, second-stage spray section, defogging plate, washing tower outlet air duct, centrifugal fan, exhaust air duct, circulating pump, spray water pipe, desalination Water pump, filter, demineralized water tank and transfer pump; Ammonia gas detector is installed in the fly ash curing workshop; A collection air duct is installed on the top of the fly ash curing workshop, and the collection air duct is connected to the air inlet at the bottom of the washing tower; The air duct is provided with an air suction port; the inside of the washing tower is sequentially provided with a first-stage packing section, a first-stage spray section, a second-stage packing section, a second-stage spray section, and a demisting plate; the bottom of the washing tower is provided with There is a liquid storage tank, the liquid storage tank is connected with the spray water pipe through the circulating pump, and the spray water pipe is connected with the first-stage spray section and the second-stage spray section; the demineralized water input pipeline is connected with the liquid storage tank; The upper exhaust port is connected to the inlet of the centrifugal fan through the outlet air duct of the washing tower, and the outlet of the centrifugal fan is connected to the fly ash maintenance workshop through the exhaust air duct; the liquid storage tank is connected to the inlet of the demineralized water pump, and the outlet of the demineralized water pump is connected to the inlet of the filter , the outlet of the filter is connected to the inlet of the demineralized water tank, the outlet of the demineralized water tank is connected to the inlet of the transfer pump, and the outlet of the transfer pump is connected to the inlet of the soft water tank of the SNCR system. 2 . The ammonia recovery structure of the fly ash maintenance workshop according to claim 1 , wherein the bottom of the washing tower is equipped with a blowdown valve. 3 . 3 . The ammonia recovery structure of a fly ash curing workshop according to claim 1 , wherein the packing in the first-stage packing section and the second-stage packing section adopts plastic stepped ring packing. 4 . 4 . The ammonia recovery structure of the fly ash curing workshop according to claim 1 , wherein the first-stage spray section and the second-stage spray section are both provided with liquid distributors. 5 . 5. The ammonia recovery structure of the fly ash curing workshop according to claim 1, wherein the defogging plate adopts a Pall ring water-retaining layer structure. 6 . The ammonia gas recovery structure of a fly ash maintenance workshop according to claim 1 , wherein the washing tower is provided with a monitoring window and an inspection manhole. 7 . 7 . The ammonia gas recovery structure of a fly ash curing workshop according to claim 1 , wherein a gas detector is provided on the exhaust air duct. 8 . 8 . The ammonia recovery structure of the fly ash maintenance workshop according to claim 1 , wherein the liquid storage tank at the bottom of the washing tower is provided with a floating ball valve. 9 . 9. the ammonia recovery structure of fly ash maintenance workshop according to claim 1, is characterized in that: also comprise DCS control system, DCS control system and ammonia gas detector, ammonia gas alarm device, washing tower, circulating pump, centrifugal The fan, the demineralized water pump and the transfer pump are connected. 10. an ammonia recovery method in fly ash curing workshop, it is characterized in that: adopt the ammonia recovery structure described in any claim of claim 1-9 to carry out, and step is: When the ammonia gas detector in the fly ash curing workshop senses that the ammonia gas exceeds the set value, the ammonia-containing air in the fly ash curing workshop is introduced into the air inlet at the bottom of the washing tower through the collecting air duct; The upper one passes through the first-stage packing section, the first-stage spray section, the second-stage packing section, and the second-stage spray section, while the demineralized water passes through the first-stage spray section and the second-stage spray section. The liquid distributor is evenly sprayed into the packing layer of the packing section and flows down along the surface of the packing layer; the ammonia-containing air is in countercurrent contact with the demineralized water, and in the process of countercurrent contact, under the action of the packing, the ammonia-containing air The ammonia gas is completely dissolved in water, and descends into the liquid storage tank of the washing tower with the desalinated water; the purified air rises to the defogging board to remove the water mist, and then is transported back to the fly ash maintenance workshop through the centrifugal fan; The ammonia-containing demineralized water in the liquid tank is pressurized by the circulating pump and then sent to the spray water pipe, and then sent to the first-stage spray section and the second-stage spray section through the spray water pipe, and then returns to the storage liquid after reacting with ammonia gas. When the recycled ammonia-containing demineralized water cannot achieve the designed treatment effect, the ammonia-containing demineralized water is transported to the demineralized water tank through the demineralized water pump, and then sent to the soft water tank of the SNCR system through the transfer pump; when the liquid storage tank When the liquid level drops to the design value, fresh demineralized water is added through the demineralized water input pipeline.

Images