CN210934359U - Flue gas low temperature adsorption denitration system - Google Patents

Abstract

The utility model discloses a flue gas low-temperature adsorption denitration system, which comprises a booster fan, a cold energy recoverer, a flue gas cooling system, a flue gas switching valve and a denitration adsorption tower; the inlet of the booster fan is communicated with the inlet flue gas pipeline, the booster fan, the cold quantity recoverer, the flue gas cooling system, the flue gas switching valve and the denitration adsorption tower are sequentially communicated, the outlet of the flue gas switching valve is respectively communicated with the first denitration adsorption tower and the second denitration adsorption tower, the flue gas outlets of the first denitration adsorption tower and the second denitration adsorption tower are communicated with the flue gas confluence device, and the flue gas confluence device is communicated with the cold quantity recoverer; the utility model discloses set up two denitrifications and adsorbThe denitration and regeneration processes are carried out by the tower in turn, so that the continuous denitration operation of the system can be realized, the denitration efficiency is high, and the adsorption material is recycled after being desorbed; denitration by physical adsorption and direct adsorption for removing NO₂And NO, NO pre-oxidation is required, and strong oxidant and noble metal catalysis are not required; the denitration efficiency is high, and zero emission of NOx can be realized.

Description

A flue gas low temperature adsorption denitrification system

technical field

The utility model belongs to the technical field of flue gas denitration, in particular to a flue gas low-temperature adsorption denitration system.

Background technique

The flue gas produced by burning coal contains a large amount of nitrogen oxides NOx, which is one of the main causes of air pollution. At present, NOx in flue gas is mainly removed by SCR selective catalytic reduction method. In this method, NOx is reduced to harmless N ₂ by NH ₃ added to the flue gas under the action of a catalyst, and then it is removed. Although SCR denitration technology is quite mature, there are still many problems. For example, the catalyst only has high activity in a specific temperature range. When the operating load of the power plant is adjusted, the change of flue gas temperature will seriously affect the SCR denitration efficiency. In addition, SCR denitration has secondary pollution problems such as ammonia escape and catalyst solid waste, and the aging and loss of denitration catalysts are also very fast, resulting in high operating costs. In addition to the SCR selective reduction method, there are also wet denitration technologies, but all of them need to oxidize the insoluble NO gas in NOx into a soluble NO2 _acid gas, and then absorb and remove it through an alkaline liquid. Common pre-oxidation methods include ozone method, hydrogen peroxide method, catalyst oxidation method, low temperature plasma oxidation method, etc. The ozone method and the hydrogen peroxide method require additional consumption of strong oxidants, which have high operating costs and are prone to secondary pollution emissions; the catalyst oxidation method requires practical and expensive precious metal catalysts, which are also difficult to industrialize application; the low-temperature plasma oxidation method has high power consumption, which also leads to higher operating costs.

Utility model content

In order to solve the problems existing in the prior art, the present invention provides a low-temperature adsorption denitration system for flue gas, which can not only adsorb and remove the easily adsorbed component NO ₂ in NOx, but also effectively adsorb the difficult-to-adsorb component NO, Reduce the cost of denitration without causing secondary pollution.

In order to achieve the above purpose, the technical scheme adopted by the present utility model is, a flue gas low-temperature adsorption denitrification system, including a booster fan, a cooling capacity recovery device, a flue gas cooling system, a flue gas switching valve, a first denitration adsorption tower and a first denitration adsorption tower. Two denitrification adsorption tower;

Among them, the inlet of the booster fan is connected with the inlet flue gas pipeline, the outlet of the booster fan is communicated with the hot side inlet of the cooling capacity recovery device, the hot side outlet of the cooling capacity recovery device is communicated with the inlet of the flue gas cooling system, and the flue gas outlet of the cooling capacity cooling system It is connected with the inlet of the flue gas switching valve, and the outlet of the flue gas switching valve is respectively connected with the flue gas inlets of the first denitration adsorption tower and the second denitration adsorption tower. The flue gas outlets of the first denitration adsorption tower and the second denitration adsorption tower are communicated with the inlet of the flue gas combiner, and the outlet of the flue gas combiner is connected to the cold side inlet of the cold energy recovery device.

The flue gas cooling system includes a primary cooling system and a secondary cooling system. The primary cooling system adopts an air cooling system, a heat exchanger cooling system or a water cooling system, and the secondary cooling system adopts a compression refrigeration system or an absorption refrigeration system.

The flue gas cooling system is provided with a flue gas condensate water outlet, and the flue gas condensate water outlet is connected to the water inlet of the reclaimed water treatment system.

The denitration adsorption tower adopts a fixed bed type adsorption tower, and the fixed bed is filled with NOx adsorption material.

The NOx adsorption material adopts activated carbon or molecular sieve.

The outside of the adsorption tower adopts a cold box structure.

The flue gas switching valve adopts electric or pneumatic switching valve; the input end of the controller of the flue gas switching valve is connected to the output end of the DCS in the factory area.

The cold energy recovery unit adopts the flue gas heat exchanger.

Compared with the prior art, the present invention has at least the following beneficial effects: the flue gas low-temperature adsorption and denitrification system of the present invention is provided with a flue gas cold energy recovery device, which can realize pre-cooling of the desulfurized flue gas by using low-temperature clean flue gas; It can improve the utilization of cooling capacity of the system, and is conducive to the rapid discharge of clean flue gas. Two denitration adsorption towers are set up to carry out the denitration and regeneration process in turn, which can realize the continuous denitration operation of the system, the denitration efficiency is high, and the adsorbent material is desorbed and recycled after desorption; denitrification The system is installed at the rear end of the dust removal and desulfurization section, and denitrification is carried out after the flue gas is lowered to below room temperature. The equipment at the rear end of the flue gas cooling system does not need to use high temperature resistant equipment, which can reduce costs.

Physical adsorption denitrification is adopted, and NO ₂ and NO are directly adsorbed and removed at the same time, without pre-oxidation of NO; the denitration efficiency is high, and zero emission of NOx can be realized; the adsorbed NOx is desorbed in the form of NO ₂ , and can be used for preparation after collection High value-added by-products such as nitric acid or nitrogen fertilizer; a large amount of acid condensate is precipitated during the cooling process of flue gas, which can be used by the power plant after neutralization treatment, reducing the water consumption of the power plant; this process uses physical methods to denitrify, without the use of denitration catalysts and reducing agents Or oxidants and other chemicals, reducing operating costs, reducing secondary pollution emissions such as ammonia escape, and realizing water resource recycling.

Description of drawings

Fig. 1 is the process schematic diagram of the utility model.

1- Booster fan, 2- Cooling capacity recovery device, 3- Flue gas cooling system, 4- Flue gas switching valve, 5- First denitration adsorption tower, 6- Second denitration adsorption tower, 7- Flue gas combiner

The accompanying drawings in the description are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

Detailed ways

In order to clearly illustrate the present utility model, the present utility model will be further described in detail below with reference to the embodiments and the accompanying drawings. Those skilled in the art understand that the following contents do not limit the protection scope of the present invention, and any improvements and changes made on the basis of the present invention are all within the protection scope of the present invention.

Referring to FIG. 1, a flue gas low-temperature adsorption denitration system includes a booster fan 1, a cooling capacity recovery device 2, a flue gas cooling system 3, a flue gas switching valve 4, a first denitration adsorption tower 5 and a second denitration adsorption tower 6 ; Among them, the inlet of the booster fan 1 is communicated with the inlet flue gas pipeline, the outlet of the booster fan 1 is communicated with the hot side inlet of the cooling capacity recovery device 2, the hot side outlet of the cooling capacity recovery device 2 is communicated with the inlet of the flue gas cooling system 3, and the flue gas The flue gas outlet of the cooling system 3 is connected to the inlet of the flue gas switching valve 4, and the outlet of the flue gas switching valve 4 is respectively connected to the flue gas inlets of the first denitration adsorption tower 5 and the second denitration adsorption tower 6, leading to the cooling capacity recovery device 2 A flue gas concentrator 7 is set on the flue gas pipeline of the first denitrification adsorption tower 5 and the flue gas outlet of the second denitration adsorption tower 6 is communicated with the inlet of the flue gas concentrator 7, and the outlet of the flue gas concentrator 7 is communicated with the cooling energy recovery Cold side inlet of device 2.

The flue gas cooling system 3 includes a primary cooling system and a secondary cooling system. The primary cooling system adopts an air cooling system, a heat exchanger cooling system or a water cooling system, and the secondary cooling system adopts a compression refrigeration system or an absorption refrigeration system. The cooling system 3 is provided with a flue gas condensate water outlet, and the flue gas condensate water outlet is connected to the water inlet of the reclaimed water treatment system.

The denitration adsorption tower adopts a fixed-bed adsorption tower, and the fixed bed is filled with NOx adsorption material; the NOx adsorption material is activated carbon or molecular sieve.

The outside of the adsorption tower adopts a cold box structure; the cold energy recovery device 2 adopts a flue gas heat exchanger.

The flue gas switching valve 4 adopts an electric or pneumatic switching valve; the input end of the controller of the flue gas switching valve 4 is connected to the output end of the DCS in the factory area.

The specific implementation of the flue gas low-temperature adsorption denitration system of the present invention is as follows:

The mechanism of adsorption and denitrification of the process described in the utility model is as follows:

1. Adsorption and removal of NO ₂ in NOx: NO ₂ is an easily adsorbed gas. When the flue gas flows through the surface of activated carbon, molecular sieve or other porous adsorption materials, NO ₂ is directly adsorbed and removed.

2. Adsorption and removal of NO in NOx: NO is a gas that is extremely difficult to adsorb. When the flue gas flows through the surface of activated carbon, molecular sieve or other porous adsorption materials, NO can not be directly adsorbed and removed, but is achieved through the following steps:

(1) The flue gas is cooled down to below room temperature by cooling;

(2) The O ₂ of NO in the low-temperature flue gas is enriched on the surface of the porous adsorption material when it flows through the surface of the porous adsorbent material, which greatly increases the concentration of NO and O ₂ , thereby rapidly oxidizing NO to NO ₂ ;

( ₃ ) The oxidized NO2 is adsorbed on the surface of the porous material.

The steps (2) and (3) are carried out simultaneously, and the overall performance is the low-temperature adsorption and removal of NO. The flue gas cooling step (1) is a necessary condition to realize the enrichment and oxidation of NO and O ₂ , because the refractory gases such as NO and O ₂ are easily adsorbed on the adsorbent surface to form enrichment only at low temperature.

Regeneration of NOx: both NO and NO ₂ in NOx are adsorbed on the surface of the porous material in the form of NO ₂ ; the porous material desorbs the adsorbed NO ₂ by heating, depressurizing and microwave regeneration, recovering the adsorption performance and recycling; The desorbed NO ₂ can be recycled to make nitric acid or nitrogen fertilizer.

A flue gas low-temperature adsorption and denitration system, comprising a booster fan 1, a cooling capacity recovery device 2, a flue gas cooling system 3, a flue gas switching valve 4, a first denitration adsorption tower 5 and a second denitration adsorption tower 6; a booster fan 1 is used to overcome the flue gas resistance generated by the system and increase the pressure of the flue gas; the cold energy recovery device 2 includes a gas-gas or gas-liquid indirect heat exchanger, and the cold energy recovery device can also use a direct spray packed tower or a plate type The tower is used to recover the net flue gas cooling capacity after low-temperature denitration, and pre-cool the inlet flue gas at the same time;

The flue gas switching valve 4 automatically switches the flow of flue gas to the first denitration adsorption tower 5 or the second denitration adsorption tower 6 according to the set switching conditions.

The first denitration adsorption tower 5 and the second denitration adsorption tower 6 are fixed bed adsorption towers filled with adsorption materials such as activated carbon, molecular sieve, activated coke, silica gel, and activated alumina. The adsorption tower adopts a cold box structure to reduce the heat dissipation loss of low temperature flue gas. The two adsorption towers are switched periodically to maintain continuous operation of flue gas adsorption and denitrification.

The flue gas concentrator 7 is used to condense the flue gas from the denitration adsorption tower into the clean flue gas pipeline for discharge.

The inlet of the booster fan 1 is connected to the inlet flue gas pipeline, the outlet of the booster fan 1 is connected to the inlet of the hot side of the cooling capacity recovery device 2, and the hot side outlet of the cooling capacity recovery device 2 is connected to the inlet of the flue gas cooling system 3. The flue gas outlet is connected to the inlet of the flue gas switching valve 4, the outlet of the flue gas switching valve 4 is respectively connected to the flue gas inlets of the denitration adsorption towers 5 and 6, and the flue gas outlets of the denitration adsorption towers 5 and 6 are connected to the inlet of the flue gas concentrator 7. , the outlet of the flue gas concentrator 7 is connected to the inlet of the cold side of the cold energy recovery device 2, and the outlet of the cold side of the cold energy recovery device 2 is connected to the pipeline to the chimney of the power plant.

The technological process described in the present utility model is as follows:

The boiler flue gas without denitrification is dedusted and desulfurized, and after the heat is recovered by the air preheater, it is introduced into the system of the present invention by the fan 1 . The high-temperature flue gas pressurized by the fan 1 passes through the cooling capacity recovery device 2, and exchanges heat with the low-temperature clean flue gas after denitrification to recover the cooling capacity of the low-temperature flue gas; the flue gas precooled by the cooling capacity recovery device 2 enters the The flue gas cooling system 3 cools the flue gas to below room temperature through multi-stage cooling methods such as circulating cooling water cooling and industrial chiller cooling, and separates the condensed water from the flue gas. The flue gas after cooling and dehumidification passes through the flue gas switching valve 4 and is introduced into the first denitrification adsorption tower 5 or the second denitration adsorption tower 6, and the two adsorption towers take turns to perform adsorption and regeneration operations to realize continuous denitration of the flue gas. The clean flue gas after adsorption and denitrification passes through the flue gas concentrator 7 and enters the cold energy recovery device 2 for cold measurement for cold energy recovery, and at the same time, the inlet flue gas is pre-cooled. The clean flue gas after the cold energy recovery is discharged from the cold energy recovery device 2 and enters the chimney of the power plant.

The flue gas of the 600MW coal-fired or gas-fired unit enters the system of the present utility model after dust removal and desulfurization; after the flue gas is pressurized by the booster fan 1, it enters the cooling capacity recovery device 2, and is exchanged with the low-temperature clean flue gas at 2°C. heat, the temperature is reduced from 50 ℃ to 35 ℃; the flue gas passes through the flue gas cooling system 3, and is further cooled to 2 ℃ by the low-temperature chiller, and the flue gas condensate is discharged from the flue gas cooling system; the cooled flue gas is switched through the flue gas Valve 4, enters the denitration adsorption tower 5, the clean flue gas flow after adsorption and denitrification passes through the flue gas concentrator 7, and enters the cold energy recovery device 2 for cold measurement, and the temperature rises to 30 ℃ after heat exchange with the flue gas after desulfurization. It is discharged into the chimney; wherein, after the first denitration adsorption tower 5 is adsorbed for 8 hours, it is switched to the second denitration adsorption tower 6 for adsorption and denitration; the first denitration adsorption tower 5 is switched to the heating regeneration mode, and the adsorbed NOx is desorbed. The denitrification adsorption tower 5 is regenerated for 4 hours, cooled for 4 hours, and then switched to the adsorption mode again. Nitrate adsorption towers ₆ are each filled with 500 tons of activated carbon; the desorbed NOx exists in the form of NO2, which can be made into dilute nitric acid through an acid-making process, or can be recycled to produce ammonium nitrate (nitrogen fertilizer) through ammonia absorption.

Claims (8)

1. A flue gas low-temperature adsorption denitration system, characterized in that, comprising a booster fan (1), a cooling capacity recovery device (2), a flue gas cooling system (3), a flue gas switching valve (4), a first denitration an adsorption tower (5) and a second denitration adsorption tower (6); The inlet of the booster fan (1) is communicated with the inlet flue gas pipeline, the outlet of the booster fan (1) is communicated with the hot side inlet of the cooling capacity recovery device (2), and the hot side outlet of the cooling capacity recovery device (2) is connected with the flue gas cooling The inlet of the system (3) is connected to the inlet of the flue gas cooling system (3) and the inlet of the flue gas switching valve (4) is connected, and the outlet of the flue gas switching valve (4) is respectively connected to the first denitration adsorption tower (5) and the first denitration adsorption tower (5) and the The flue gas inlet of the second denitration adsorption tower (6), the flue gas pipeline leading to the cold energy recovery device (2) is provided with a flue gas concentrator (7), the first denitration adsorption tower (5) and the second denitration adsorption tower ( The flue gas outlet of 6) is communicated with the inlet of the flue gas concentrator (7), and the outlet of the flue gas concentrator (7) is communicated with the cold side inlet of the cold energy recovery device (2). 2. The flue gas low-temperature adsorption denitration system according to claim 1, wherein the flue gas cooling system (3) comprises a primary cooling system and a secondary cooling system, and the primary cooling system adopts an air cooling system and a heat exchanger for cooling System or water cooling system, secondary cooling system adopts compression refrigeration system or absorption refrigeration system. 3. The flue gas low-temperature adsorption denitration system according to claim 1, wherein the flue gas cooling system (3) is provided with a flue gas condensed water outlet, and the flue gas condensed water outlet is connected to the water inlet of the reclaimed water treatment system . 4. The flue gas low-temperature adsorption denitration system according to claim 1, wherein the denitration adsorption tower adopts a fixed bed type adsorption tower, and the fixed bed is filled with NOx adsorption material. 5 . The flue gas low-temperature adsorption and denitration system according to claim 4 , wherein the NOx adsorption material is activated carbon or molecular sieve. 6 . 6 . The flue gas low-temperature adsorption denitration system according to claim 1 , wherein the outside of the adsorption tower adopts a cold box structure. 7 . 7. The flue gas low-temperature adsorption denitration system according to claim 1, wherein the flue gas switching valve (4) adopts an electric or pneumatic switching valve; the input end of the controller of the flue gas switching valve (4) is connected to the DCS in the factory area 's output. 8 . The flue gas low-temperature adsorption denitration system according to claim 1 , wherein the cold energy recovery device ( 2 ) adopts a flue gas heat exchanger. 9 .

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