CN210662878U

CN210662878U - Purification recovery system of chlorine-containing tail gas

Info

Publication number: CN210662878U
Application number: CN201921651822.0U
Authority: CN
Inventors: 刘子程; 姜龙; 陈光强; 曹硕; 杨加强; 李明; 李文跃
Original assignee: Yingkou Yingxin Chemical Technology Co ltd
Current assignee: Yingkou Yingxin Chemical Technology Co ltd
Priority date: 2019-09-30
Filing date: 2019-09-30
Publication date: 2020-06-02
Anticipated expiration: 2029-09-30

Abstract

The utility model provides a purification recovery system of chlorine-containing tail gas belongs to cyanuric chloride production technical field. The purification and recovery system comprises a buffer tank, a pressurizing fan, an incinerator, a waste heat boiler, a quench tower, an absorption tower, a flue gas reheater, a circulating fluidized bed reactor and a circulating fluidized bed reactor which are sequentially connected,Denitration device, economizer and chimney. The utility model discloses a burn chlorine-containing tail gas and natural gas with Cl₂And the HCl is converted into HCl and sequentially passes through a waste heat boiler, a quench tower and an absorption tower, and the byproduct dilute hydrochloric acid is recovered while heat exchange and temperature reduction are carried out. The utility model can obviously reduce energy consumption, does not need alkali liquor absorption, and cancels a large amount of salt-containing wastewater treatment sections; meanwhile, the heat after burning is recovered, a large amount of steam is generated as a byproduct, and the waste heat of tail gas is recovered; carrying out harmless treatment on nitrogen oxides generated after incineration through denitration, and converting the nitrogen oxides into harmless nitrogen; the whole purification and recovery system has the advantages of stable process route, simple structure, low failure rate, energy conservation and environmental protection.

Description

Purification recovery system of chlorine-containing tail gas

Technical Field

The utility model belongs to the technical field of the cyanuric chloride production, concretely relates to a purification recovery system for preparing cyanuric chloride in-process chlorine-containing tail gas.

Background

Cyanuric chloride is an important chemical intermediate, compared with the synthesis process of a light oil cracking method and a sodium cyanide method, the one-step synthesis process of hydrocyanic acid is very clean, environment-friendly and energy-saving, and the process flow is short, and does not generate a large amount of salt-containing wastewater. However, in this process, as in the sodium cyanide process, a chlorine-containing off-gas is formed after the polymerization. The existing treatment methods of chlorine-containing tail gas are roughly divided into two methods, namely a chemical method and a physical method: the chemical method is alkali liquor neutralization method and ferrous sulfate or ferrous chloride absorption method; physical methods generally employ activated carbon and silica gel adsorption methods. Wherein, the absorption of alkali liquor can generate a large amount of salt-containing wastewater, thereby increasing the treatment capacity and purification cost of the wastewater and consuming a large amount of alkali liquor; the reaction speed of the ferrous sulfate or ferrous chloride absorption method is slower than that of the alkali liquor neutralization method, and the efficiency is poorer; the adsorption method has the advantages of no secondary pollution, high chlorine recovery rate up to about 95 percent, limited adsorption capacity and suitability for occasions with small amount or low concentration of chlorine-containing tail gas.

For the reasons, the utility model provides a chlorine-containing tail gas treatment process suitable for cyanuric chloride production, which treats chlorine-containing tail gas and meets the national environmental protection requirements; but also recycles the chlorine, saves the cost and improves the utilization rate of resources.

SUMMERY OF THE UTILITY MODEL

Aiming at the defects of the chlorine-containing tail gas purification process in the existing cyanuric chloride production process, the utility model provides a purification and recovery system for chlorine-containing tail gas, which can remarkably reduce energy consumption, does not need alkali liquor absorption, and cancels a large amount of salt-containing wastewater treatment sections; meanwhile, the heat after burning is recovered, a large amount of steam is generated as a byproduct, and the waste heat of tail gas is recovered; carrying out harmless treatment on nitrogen oxides generated after incineration through denitration, and converting the nitrogen oxides into harmless nitrogen; the whole purification and recovery system has the advantages of stable process route, simple structure, low failure rate, energy conservation and environmental protection.

The technical scheme of the utility model:

the purification and recovery system for the chlorine-containing tail gas comprises a buffer tank, a pressurizing fan, an incinerator, a waste heat boiler, a quench tower, an absorption tower, a flue gas reheater, a denitration device, an economizer and a chimney which are sequentially connected.

The buffer tank is a vertical storage tank and is used for buffering and storing chlorine-containing tail gas generated after cyanuric chloride polymerization reaction; the buffer tank is connected with a pressurizing fan, and the chlorine-containing tail gas is pressurized and then sent to the incinerator, so that stable tail gas flow is provided for incineration of the incinerator.

Chlorine-containing tail gas enters a hearth of the incinerator through a waste gas burner to be incinerated with natural gas at 1000-1500 ℃, and because the main component in the waste gas is air, the incinerator can ensure enough oxygen without supplementing extra air through calculation, so that the natural gas is stably combusted, and a combustion-supporting fan is not needed. Decomposing and oxidizing the chlorine-containing tail gas to obtain Cl₂Conversion to HCl, conversion of other substances to NO_x(oxides of nitrogen), CO₂、 H₂O, and the like.

The high-temperature flue gas after burning enters a waste heat boiler to exchange heat with deaerated water, most waste heat is recovered, saturated steam is generated while the temperature of the flue gas is reduced, the saturated steam is merged into a pipe network or is used by oneself, the temperature of the flue gas after heat exchange of the waste heat boiler is reduced to 400-500 ℃, and then the flue gas is introduced into a quench tower to be further cooled through a flue.

In the quenching tower, the flue gas directly contacts with the circulating dilute hydrochloric acid sprayed into mist in the quenching tower, and the water and HCl in the dilute hydrochloric acid are heated to evaporate and absorb heat, so that the temperature of the flue gas is rapidly reduced; the quenching tower is connected with the graphite heat exchanger, and heat absorbed by the circulating dilute hydrochloric acid exchanges heat with circulating cooling water in the graphite heat exchanger to reduce the temperature. The temperature of the flue gas passing through the quenching tower is reduced to 40-70 ℃.

The flue gas cooled by the quench tower enters an absorption tower, reversely contacts and fully mixes with circulating dilute hydrochloric acid in the absorption tower, and further exchanges heat with a graphite heat exchanger connected to the absorption tower; after heat exchange, HCl gas in the flue gas is dissolved in dilute hydrochloric acid to produce a 10-30% dilute hydrochloric acid solution, the concentration of circulating dilute hydrochloric acid in the absorption tower is adjusted as required, and the byproduct hydrochloric acid is recycled.

Introducing the flue gas from the absorption tower into a flue gas reheater, burning natural gas to make the temperature of the flue gas reach 200-300 ℃, and then introducing the flue gas into a denitration device. Ammonia water is sprayed into an inlet flue of the denitration device and generates ammonia gas after being heated, and the ammonia gas and NO in the flue gas are mixed under the action of a catalyst_xReaction of NO with_xReduction to N₂. Flue gas from the denitration device enters the economizer, and heat of the flue gas is used for heating desalted water, so that the smoke exhaust temperature is reduced, and steam is generated for production. And the flue gas from the economizer is introduced into a chimney through a draught fan and then is discharged into the atmosphere.

The utility model has the advantages that: the utility model provides a chlorine tail gas's purification recovery system, this purification recovery system burns Cl with chlorine tail gas and natural gas through₂And the HCl is converted into HCl and sequentially passes through a waste heat boiler, a quench tower and an absorption tower, and the byproduct dilute hydrochloric acid is recovered while heat exchange and temperature reduction are carried out. The utility model can obviously reduce energy consumption, does not need alkali liquor absorption, and cancels a large amount of salt-containing wastewater treatment sections; simultaneously, the heat after burning is recovered, a large amount of steam is produced as a byproduct, and the tail is recoveredGas waste heat; carrying out harmless treatment on nitrogen oxides generated after incineration through denitration, and converting the nitrogen oxides into harmless nitrogen; the whole purification and recovery system has the advantages of stable process route, simple structure, low failure rate, energy conservation and environmental protection.

Drawings

FIG. 1 is a flow chart of the purification and recovery system of the present invention.

Detailed Description

The following further describes a specific embodiment of the present invention with reference to the drawings and technical solutions.

Because the content of nitrogen element of organic matter in the chlorine-containing tail gas is high, and when the temperature of the incinerator reaches 1000 ℃, the thermal NO is generated_xThe generated gas is more, so the flue gas after passing through the absorption tower needs to be subjected to denitration treatment. Introducing the flue gas from the absorption tower into a flue gas reheater, burning natural gas to make the temperature of the flue gas reach 200-300 ℃, and then introducing the flue gas into a denitration device. Ammonia water is sprayed into an inlet flue of the denitration device and generates ammonia gas after being heated, and the ammonia gas and NO in the flue gas are mixed under the action of a catalyst_xReaction of NO with_xReduction to N₂. Flue gas from the denitration device enters the economizer, and heat of the flue gas is used for heating desalted water, so that the smoke exhaust temperature is reduced, and steam is generated for production. And the flue gas from the economizer is introduced into a chimney through a draught fan and then is discharged into the atmosphere. The exhaust gas composition change table is shown in table 1:

TABLE 1

Procedure (ii)	Component name
		Initial chlorine-containing tail gas	Cl₂、CO₂、(CNCl)₃、CNCl、N₂、O₂
Incinerator outlet	CO₂、NO_x、HCl、O₂、Cl₂
		Outlet of quench tower	CO₂、NO_x、HCl、O₂、Cl₂
Outlet of absorption tower	CO₂、NO_x、O₂
		Outlet of denitrating apparatus	CO₂、N₂、O₂
Chimney outlet	CO₂、N₂、O₂

Claims

1. The system for purifying and recovering the tail gas containing chlorine is characterized by comprising a buffer tank, a pressurizing fan, an incinerator, a waste heat boiler, a quench tower, an absorption tower, a flue gas reheater, a denitration device, an economizer and a chimney which are sequentially connected;

the buffer tank is a vertical storage tank and is used for buffering and storing chlorine-containing tail gas generated after cyanuric chloride polymerization reaction; the buffer tank is connected with a pressurizing fan, and the chlorine-containing tail gas is pressurized and then sent to the incinerator to provide stable tail gas flow for the incinerator to burn; the incinerator is further connected with a waste heat boiler, and high-temperature flue gas of the incinerator enters the waste heat boiler to exchange heat with deoxygenated water; the waste heat boiler is further connected with the quenching tower, and the flue gas subjected to heat exchange by the waste heat boiler enters the quenching tower to be fully contacted with the atomized circulating dilute hydrochloric acid for heat transfer; the quenching tower is also connected with a graphite heat exchanger, and heat absorbed by the circulating dilute hydrochloric acid exchanges heat with circulating cooling water in the graphite heat exchanger to reduce the temperature; the quenching tower is further connected with an absorption tower, the flue gas cooled by the quenching tower enters the absorption tower, reversely contacts and fully mixes with the circulating dilute hydrochloric acid in the absorption tower, and further exchanges heat with a graphite heat exchanger connected with the absorption tower; the absorption tower is further connected with a flue gas reheater, and flue gas discharged from the absorption tower is introduced into the flue gas reheater to be heated and then enters a denitration device; the denitration device is further connected with the economizer, the flue gas from the denitration device enters the economizer, and the heat of the flue gas is used for heating desalted water connected with the economizer, so that the temperature of the discharged flue gas is reduced, and the generated steam is recycled; the economizer is connected with a chimney.