CN103691290B - A kind of cement furnace SNCR flue gas denitrification system improving denitration security - Google Patents

Abstract

The invention discloses a cement kiln SNCR flue gas denitrification system which improves the safety of denitrification, comprising a decomposition furnace, a reducing agent distribution module, a denitrification control module, a soft water delivery module, an ammonia water supply module; and a first spray device of the ammonia water unloading module , the temperature sensor, pressure sensor and safety relief valve on the top of the ammonia water storage tank, the second spray device above the ammonia water storage tank, the first ammonia leak detector and the first sound and light alarm of the ammonia water delivery module; the reducing agent distribution module The second ammonia leak detector, the second sound and light alarm and exhaust fan; the temperature sensor, pressure sensor, the first ammonia leak detector and the second ammonia leak detector are all connected to the denitrification control module; the safety relief valve, the second ammonia leak detector The second spray device, the first sound and light alarm, the second sound and light alarm and the exhaust fan are all connected to the denitrification control module. The invention reduces the potential danger of using ammonia water as the reducing agent as far as possible, and solves the technical problem that the safety of the SNCR denitrification project of the cement kiln in China is not high.

Description

A cement kiln SNCR flue gas denitrification system with improved denitrification safety

technical field

The present invention relates to the subject of safety and environmental protection in the process of releasing gas during the heat treatment of the cement production process, and in particular to a cement kiln SNCR flue gas denitrification system that improves the safety of denitrification.

Background technique

SNCR denitrification technology is most widely used in domestic and foreign cement industry kiln flue gas denitrification projects. There are two main reducing agents for the SNCR denitrification system of cement kilns: ammonia water and urea. In domestic cement production lines, except for Fujian Longlin Cement and Dujiangyan Lafarge Cement, which use urea as the reducing agent, most other cement enterprises use ammonia water as the reducing agent. . In October 2012, an ammonia explosion accident occurred in a cement factory in Fujian, killing 2 people. On June 3, 2013, 119 people were killed in a huge liquid ammonia explosion accident in Jilin Poultry Industry Co., Ltd., resulting in the use of ammonia water as a reducing agent in the cement denitrification system. System security has attracted widespread attention.

According to the "Inventory of Hazardous Chemicals" (2008), 20-25% ammonia water belongs to hazardous chemicals; according to "Identification of Major Hazard Sources of Hazardous Chemicals" (GB18218-2009), ammonia water has not been classified as a major hazard source; according to "First Quantity Standards for the Use of Hazardous Chemicals in Batches", ammonia water is not included in the list, and there is no clause requiring enterprises to apply for a "Hazardous Chemicals Safety Use Permit"; as a user enterprise, it is necessary to meet the "Regulations on the Safety Management of Hazardous Chemicals" (State Council Decree No. 591) related storage and use regulations.

Ammonia water is easy to decompose and release ammonia gas. The higher the temperature, the faster the decomposition rate, which can form an explosive atmosphere. In case of high heat, the internal pressure of the container will increase, and there is a danger of cracking and explosion. SNCR uses ammonia as a reducing agent with a concentration of 20-25%, which has not reached the level where the country lists ammonia solution [35%<ammonia ≤50%] as a hazardous chemical. 20% factor, strengthen safety measures for ammonia water system.

Ammonia is flammable, toxic, and irritating dangerous chemical. When the human body inhales low-concentration ammonia, it can irritate the mucous membranes, and inhaling high-concentration ammonia can cause tissue dissolution and necrosis; ammonia mixed with air can form an explosive mixture, which may Cause a burning explosion.

Since ammonia water is used as a reducing agent in cement denitrification, the possible danger is mainly that the leakage of ammonia water may cause explosion or personal injury. Leakage points are mainly at the joints of storage tanks and pipeline fittings, such as: leakage due to careless operation or misoperation during filling; leakage of storage tanks, valves, pipes and accessories due to corrosion damage; inadequate inspection or maintenance during operation Quality problems, resulting in equipment leakage. In addition, there are infrequent but potential sources of danger: storage tank explosion caused by high temperature, lightning strikes, excessive storage or other force majeure; regular operation and maintenance work is not in place, causing damage to the equipment in the ammonia area, making the ammonia area unable to operate normally; transportation The transport volume of the tank truck exceeds the limit or the equipment is not maintained properly, resulting in leakage, explosion and fire. At present, there is no patent specifically aimed at the safety measures of cement denitrification.

Contents of the invention

The invention provides a cement kiln SNCR flue gas denitrification system with improved denitrification safety, which is used to reduce the potential danger of using ammonia water as a reducing agent as much as possible, and solves the technical problem of low safety of the cement kiln SNCR denitrification project in China.

A cement kiln SNCR flue gas denitration system that improves the safety of denitrification, including a calciner, a reducing agent distribution module, a spray gun connecting the reducing agent distribution module and the calciner, a denitrification control module, and a soft water delivery module connected in parallel through the reducing agent distribution module and an ammonia water supply system; the ammonia water supply system includes an ammonia water tank car connected in sequence, an ammonia water unloading module, an ammonia water storage tank and an ammonia water delivery module, and the ammonia water delivery module is connected to a reductant distribution module;

A first spray device is provided above the ammonia water unloading module, a temperature sensor, a pressure sensor and a safety relief valve are provided on the top of the ammonia water storage tank, a second spray device is provided above the ammonia water storage tank, and the ammonia water storage tank is provided with a second spray device. The delivery module is provided with a first ammonia leakage detector and a first sound and light alarm, and a fourth spray device is provided above the ammonia water delivery module;

The reductant distribution module is provided with a second ammonia leak detector, a second sound and light alarm and an exhaust fan;

The temperature sensor, the pressure sensor, the first ammonia leak detector and the second ammonia leak detector are all communicatively connected to the denitrification control module;

The switches of the second spraying device, the fourth spraying device, the first sound and light alarm, the second sound and light alarm and the exhaust fan are all connected to and controlled by the denitrification control module.

The temperature sensor detects the temperature information in the ammonia water storage tank and transmits it to the denitration control module. The denitration control module automatically controls the start and stop of the second spray device according to the collected temperature signal to cool down the ammonia water storage tank; the pressure sensor detects the temperature in the ammonia water storage tank. The pressure information of the ammonia water storage tank is transmitted to the denitrification control module, and the pressure information in the ammonia water storage tank is monitored through the denitration control module; the safety relief valve is automatically opened or closed according to the pressure in the ammonia water storage tank to reduce the pressure.

The ammonia water unloading module includes an unloading pump, an unloading pipeline, corresponding valves and meters. There are many connectors, and ammonia leakage is relatively easy to occur. Therefore, a spraying device is set above the ammonia water unloading module, and the spraying device is started to correct the leakage when necessary. The ammonia gas is sprayed and absorbed.

The ammonia water delivery module includes the ammonia water delivery pump, the ammonia water delivery pipeline, corresponding valves and meters, and there are relatively many connectors, which are relatively prone to ammonia leakage. Therefore, the first ammonia leak detector is installed at the ammonia water delivery module. The first ammonia leakage The detector detects the ammonia concentration information in the air near the ammonia water unloading module and the ammonia water delivery module, and transmits it to the denitration control module. The denitration control module can set a high ammonia concentration alarm signal, and control the first sound and light alarm according to the ammonia concentration information. start and stop, remind the staff to open the spray device above the ammonia water unloading module for spray absorption, and start the second spray module and the fourth spray module at the same time.

The main part of the reductant distribution module can be a conventional reductant distribution module. In the present invention, an ammonia leakage detector, an audible and visual alarm, an emergency stop switch and an exhaust fan are added to the reductant distribution module.

The reductant distribution module includes a reductant distribution cabinet and a distribution pipeline arranged in the reductant distribution cabinet, the exhaust fan is arranged on the top of the reductant distribution cabinet, the second ammonia leak detector is arranged in the reductant distribution cabinet, and the second ammonia leakage detector is arranged in the reductant distribution cabinet. Two sound and light alarms are installed on the top of the reducing agent distribution cabinet.

The first manual ball valve, the pneumatic shut-off valve, the first flow meter, and the pneumatic regulating valve are arranged in sequence along the flow direction of ammonia water on the main pipe, and the pneumatic shut-off valve and the pneumatic regulating valve are connected to the compressed air pipeline. The outlet end of the outlet port is connected to several branch pipes through joints, and each branch pipe is correspondingly connected to a spray gun, and a needle valve, a second flow meter and a second manual ball valve are sequentially arranged on each branch pipe along the flow direction of ammonia water. The pneumatic shut-off valve, the pneumatic control valve, the first flow meter, the second ammonia leakage detector, and the second sound and light alarm are all connected to the denitrification control module.

There are many joints in the reducing agent distribution module, which is a place where ammonia leakage is relatively easy to occur. The second ammonia leakage detector and the second sound and light alarm are installed here, and the second ammonia leakage detector detects the ammonia concentration in the reducing agent distribution cabinet. And transmit to the denitrification control module, the denitrification control module starts the second sound and light alarm to remind the staff, and automatically starts the exhaust fan at the same time.

In the present invention, the denitrification control module adopts conventional control equipment commonly used in the field, and preferably, the denitration control module is a DCS controller. A PLC controller can also be used.

When ammonia leakage occurs, the operator may cause eye discomfort due to not wearing protective glasses. Therefore, preferably, a third spraying device for emergency treatment is also provided near the ammonia storage tank, and the third spraying device is connected to tap water. groove. The third shower device is used for operators to wash eyes and so on.

Preferably, emergency stop buttons are provided at the ammonia water unloading module, the ammonia water delivery module, the reducing agent distribution module and the soft water delivery module. In case of emergency, the emergency stop can be stopped by directly operating the emergency stop button of the module.

Preferably, both the second spraying device and the fourth spraying device have solenoid valves, and the solenoid valves are connected to and controlled by the denitration control module.

Further preferably, a manual ball valve is also provided before and after the solenoid valve, and a bypass pipe is connected to the water inlet pipe between the nozzles of the second spraying device and the fourth spraying device and the corresponding solenoid valve, and the bypass pipe There is a bypass ball valve on the pipeline. Set up a corresponding bypass to facilitate online maintenance when the solenoid valve fails, and to prevent the second spraying device from being manually activated when the solenoid valve does not operate when the power is off. The spraying surface of the second spraying device covers the entire top of the ammonia storage tank.

The function of the first spraying device is to absorb the ammonia leaked from the ammonia water unloading module; Both the device and the second spray device are connected to the water tank.

Preferably, an emergency pool is provided under the ammonia water storage tank, the emergency pool includes a pool body below the ground and a cover plate on the top of the pool bottom, and the ammonia water storage tank is installed on the cover plate.

Further preferably, a cofferdam arranged around the ammonia water storage tank is provided above the cover plate, a manhole is provided at the bottom of the cofferdam, and a manhole door is correspondingly provided at the manhole.

Further preferably, a spray water collecting device is arranged under the first spraying device, the third spraying device and the fourth spraying device, and the spraying water collecting device is connected to the emergency pool through a pipeline.

The accident pool is used to collect the spray water and ammonia water leaked from the ammonia water storage tank. The spray water from the first spray device, the third spray device and the fourth spray device enters the accident pool through the connecting pipe, and the second spray device The spray water flows into the accident pool by itself through the cofferdam. The cofferdam can also prevent the ammonia water storage tank from overflowing the accident pool when the ammonia water is leaked. The accident pool is set in the foundation below the ammonia water storage tank to save space. The cofferdam and the cover plate are preferably integrally structured.

Further preferably, there are two manholes, and the two manholes are distributed axially symmetrically.

Further preferably, the size of the manhole is 800mm×800mm.

Further preferably, the pool body volume of the accident pool is not less than the effective volume of the ammonia water storage tank, and several pillars for supporting the cover plate are arranged in the pool body. The pillars support the cover to enhance the stability of the ammonia storage tank.

The accident pool is provided with an emergency discharge pump, and the liquid collected in the accident pool is pumped back to the ammonia water tanker by the accident discharge pump for reuse.

The air outlet of the decomposition furnace of the present invention is sequentially connected to the preheater, the humidifying tower, the electrostatic precipitator and the kiln tail chimney through pipelines, and the kiln tail chimney is equipped with an ammonia escape online analyzer and a continuous flue gas online analyzer (CEMS). Both the ammonia slip online analyzer and the flue gas continuous online analyzer (CEMS) are communicatively connected to the denitrification control module.

The flue gas after the denitrification treatment in the calciner is preheated by the preheater, humidified by the humidifying tower, and dusted by the electrostatic precipitator, and then discharged from the chimney at the end of the kiln. flue gas parameters (flue gas flow rate, nitrogen oxide concentration, temperature, oxygen, pressure, ammonia escape concentration, etc.), and send the flue gas parameters to the denitrification control module. ) feedback information to control the injection volume and injection scheme of ammonia water in the reductant distribution module.

The mutual control relationship between CEMS and the denitrification control module adopts conventional control methods in this field.

The ammonia escape online analyzer detects the ammonia content in the flue gas in the kiln tail chimney and transmits it to the denitrification control module. When the ammonia content exceeds the set value, the denitrification control module starts the system protection stop and starts the system cleaning at the same time.

Preferably, there are several spray guns, one part is connected to the air outlet flue of the calciner, and the other part is connected to the furnace of the calciner. Preferably, the reductant distribution module is provided with a red emergency button. Operate the red emergency button to quickly stop the entire denitrification system.

The beneficial effects that the present invention has are:

(1) The selected technology is applicable to the safety measures of the SNCR flue gas denitrification system of all cement clinker production lines using ammonia water as the reducing agent;

(2) Multiple safety protections, most reliably guard against all predictable risk factors;

(3) Fully automatic safety emergency measures, which can monitor all potential sources of danger on the operation interface of the central control room, and automatically start safety precautions, which are the most timely and effective safety emergency measures;

(4) It not only improves the safety of system operation, but also improves the working environment of the inspection personnel.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a connection relation diagram between the calciner of the present invention and other equipment.

Fig. 3 is a process flow diagram of the present invention.

Fig. 4 is a schematic diagram of the integrated structure of the emergency pool and the cofferdam of the present invention.

FIG. 5 is a plan view shown in FIG. 4 .

Fig. 6 is a schematic structural view of the reducing agent distribution module of the present invention.

Detailed ways

As shown in FIGS. 1 to 6 , a cement kiln SNCR denitrification system includes a soft water delivery module 3 , an ammonia water supply system, a reducing agent distribution module 4 and a decomposition furnace 20 .

The soft water delivery module 3 is connected to the soft water storage tank 2, and the soft water storage tank is connected to the owner's desalted water storage tank 1. The soft water delivery module includes a soft water delivery pump, a soft water pipeline, corresponding valves and meters; the soft water pipeline is connected to the reducing agent distribution module 4.

The ammonia water supply system includes an ammonia water tank car 17 , an ammonia water unloading module 15 , an ammonia water storage tank 12 and an ammonia water delivery module 13 connected in sequence, and the ammonia water delivery module 13 is connected to the reducing agent distribution module 4 .

The ammonia water unloading module 15 comprises an ammonia water unloading pump, an ammonia water pipeline, a pipeline valve, an emergency stop button for controlling the emergency stop of the pipeline valve, and a first spray device 16 is arranged above the ammonia water pipeline and the pipeline valve, and the water inlet pipe of the first spray device is connected to Running sink6.

The ammonia water pipeline of the ammonia water unloading module 15 is connected to the ammonia water storage tank 12, and the top of the ammonia water storage tank 12 is provided with a temperature sensor 8 (TI), a pressure sensor 9 (PI) and a safety relief valve (not shown in the figure, the temperature sensor 8 adopts Thermocouple, the top of the ammonia storage tank 12 is provided with a second spray device 7, the water inlet pipe of the second spray device 7 is connected to the water tank 6, and the water inlet pipe of the second spray device 7 has a solenoid valve, and the solenoid valve There are manual ball valves at the front and rear of the valve, and a bypass, and the solenoid valve is connected to the denitrification control module 11.

An accident pool 14 is provided below the ammonia storage tank 12. The accident pool 14 includes a pool body 1403 below the ground and a cover plate 1402 at the top of the pool bottom. The cofferdam 1401 installed on the storage tank is placed around the periphery of the ammonia water storage tank. The cofferdam and the cover plate are integrated. The individual holes are distributed axially symmetrically. The size of the manholes is 800mm×800mm. The manholes are equipped with manhole doors. The volume of the accident pool is not less than the effective volume of the ammonia storage tank. There are several roots in the pool for supporting the cover. Plate struts 1404 .

The accident pool is equipped with an accident discharge pump, and the liquid collected in the accident pool is pumped back to the ammonia tank car for reuse by the accident discharge pump.

The ammonia water in the ammonia water storage tank 12 is sent into the reductant distribution module 4 through the ammonia water delivery module 13. The ammonia water delivery module 13 includes an ammonia water delivery pump, a number of ammonia water pipelines connected in parallel, and correspondingly arranged on each ammonia water pipeline. There is an emergency stop button for the emergency stop of the valve. The ammonia water delivery module 13 is equipped with the first ammonia leakage detector (ASI) and the first sound and light alarm. The parallel ammonia water pipeline is connected to the reducing agent distribution module 4 after the ammonia water The delivery module 13 top is provided with the 4th sprinkler 28, and the water inlet pipeline of the 4th sprinkler 28 is connected with tap water tank 6, has electromagnetic valve on the water inlet pipeline, is equipped with manual ball valve before and after the electromagnetic valve, and is equipped with side. The solenoid valve is connected to the denitration control module 11.

The main part of the reductant distribution module 4 can be a conventional reductant distribution module. The present invention adds a second ammonia leakage detector (ASI), a second sound and light alarm and an exhaust fan 23 to the reductant distribution module.

The reductant distribution module 4 includes a reductant distribution cabinet 413 and distribution pipes installed in the reductant distribution cabinet 413 , two exhaust fans are provided on the top of the reductant distribution cabinet, and the second ammonia leak detector (ASI) 412 It is arranged in the reducing agent distribution cabinet, and the second sound and light alarm 402 is installed on the top of the reducing agent distribution cabinet.

The distribution pipeline includes a main pipe. The inlet end of the main pipe is connected to the main pipe after the outlet pipeline of the ammonia water delivery module and the soft water delivery module are merged. The first manual ball valve 408, the pneumatic shut-off valve 409, the second A flow meter 410, a pneumatic regulating valve 411, a pneumatic shut-off valve and a pneumatic regulating valve are connected to the compressed air pipeline, and a ball valve 407 is installed on the compressed air pipeline. Each branch pipe is provided with a needle valve 404, a second flow meter 403 and a second manual ball valve 401 in sequence along the flow direction of ammonia water. The pneumatic shut-off valve, the pneumatic regulating valve and the first flow meter are all connected to the denitration control module.

A red emergency button 405 and a pressure transmitter 406 are also integrated in the reductant distribution cabinet.

The calciner 20 adopts a conventional calciner, and the top of the calciner 20 is provided with an air outlet, and the air outlet is connected to an air outlet duct. A first ammonia injection section 21 is set on the air outlet duct, and a second ammonia injection section 21 is arranged in the furnace of the calciner. Section 19, the two ammonia water injection sections are connected to the reducing agent distribution module 4 through several spray guns 22, the inlets of the spray guns 22 are respectively connected to the branch pipes after the distribution of the reducing agent distribution module, and the compressed air pipelines are connected to the compressed air storage tank 11 and each Road spray gun 22, provides power, purges and cools for each road spray gun.

The air outlet pipe of the calciner 20 is connected to the preheater 24, the humidification tower 25, the raw meal mill 26, the electrostatic precipitator 27 and the kiln tail chimney 17 in sequence, and the kiln tail chimney 17 is equipped with a continuous online flue gas monitoring system (CEMS) and the ammonia slip online analyzer 18 , the flue gas continuous online monitoring system (CEMS) and the ammonia slip online analyzer 18 are all communicatively connected to the denitrification control module 11 .

A third spraying device 5 is also arranged near the ammonia water storage tank 12, the water inlet pipe of the third spraying device 5 is connected to the running water tank 6, and the third spraying device 5 has a control valve.

Below the first spraying device 16 , the third spraying device 5 and the fourth spraying device 28 are all provided with a spraying water collecting device, and the spraying water collecting device is connected to the emergency pool through a pipeline.

The denitrification control module 11 adopts a conventional DCS controller, and the DCS controller is provided with a general emergency stop button, and the denitrification control module is installed in the denitrification control cabinet.

The temperature sensor 8, the pressure sensor 9, the first ammonia leak detector, the second ammonia leak detector, the flue gas continuous on-line monitoring system and the ammonia escape on-line analyzer 18 are all connected to the DCS controller through signal lines. The solenoid valve of the second spraying device 7, the solenoid valve of the fourth spraying device 28, the switch of the first sound and light alarm and the second sound and light alarm, the switch of the exhaust fan 23, and the control valves of each spray gun 22 All are connected to the DCS controller, and the ammonia water flow meter, ammonia water regulating valve, main pipe and pneumatic valve on the branch road in the reducing agent distribution cabinet are all connected to the DCS controller.

Process flow of the present invention is as follows:

The ammonia water tank truck 17 transports 20-25wt.% ammonia water, a common by-product in the chemical process, to the site, and injects it into the ammonia water storage tank 12 through the ammonia water unloading module 15. Since the new dry process cement production process is generally equipped with a waste heat boiler, it can supply hardness less than The soft water of 0.03mmol/L is sent into the soft water storage tank 2. Ammonia water and soft water are respectively pumped to the reducing agent distribution module 4 by the ammonia water and soft water delivery modules. In the reducing agent distribution module 4, the flue gas parameters (flue gas flow rate, nitrogen oxide concentration, temperature, oxygen, pressure, ammonia escape concentration, etc.) fed back by the kiln tail chimney, the ammonia water required by the metering system, and in the module Realize the distribution of ammonia water injection volume of each spray gun, distribute to each spray gun, and send it to the decomposition furnace.

In addition, compressed air needs to be connected to each spray gun 22. The compressed air consumption of a single spray gun is 10Nm ³ /h, and the pressure is 0.3-0.4MPa to enhance the range of ammonia water and ensure that the reducing agent flow rate is too small to cool the spray gun. The spray gun 22 is installed on the upper part of the calciner 20 to the temperature range of 850-1050°C of the calciner, and the injection point is determined according to process simulation and experience. The flue gas after NOx removal is discharged into the air after passing through various levels of cyclone preheaters, waste heat boilers, humidification towers, raw meal mills, dust collectors, and kiln tail chimneys.

Potential sources of danger due to the use of hazardous chemicals (ammonia water) during operation include: the danger mainly lies in the leakage of ammonia water, and the leakage point is mainly at the connection of storage tanks and pipeline fittings, such as: 1) due to careless operation during the filling process 2) Storage tanks, valves, pipes and accessories leak due to frequent actions or corrosion damage; 3) Inadequate operation inspection or maintenance quality problems cause equipment leakage. In addition, there are infrequent but potential sources of danger, such as: 1) Explosion of storage tanks caused by high temperature, lightning strikes, excessive storage or other force majeure; 2) Inadequate operation and regular maintenance work, resulting in damage to equipment in the ammonia area and malfunction 3) The transportation volume of the transport tanker exceeds the limit or the equipment is not maintained properly, resulting in leakage, explosion and fire.

Various safety control modes of the present invention are as follows:

Ammonia water unloading module: equipped with shower dilution water, when the ammonia concentration in the ammonia area can be detected or felt to be high during the ammonia unloading process, the first spray device on the ammonia water unloading module can be turned on for absorption to reduce leakage into the environment Ammonia concentration.

When the ammonia water was unloaded, there was a strong odor of ammonia water. The ammonia unloading personnel saw that the ammonia concentration value on the first ammonia leak detector integrated on the nearby ammonia water delivery module directly rose to more than 200ppm (the full scale is 200ppm, which may have exploded). The first sound and light alarm on the ammonia water delivery module sends out an alarm, the second spray device on the upper part of the ammonia water storage tank is automatically activated, and the first spray device on the ammonia water unloading module is manually turned on, and the ammonia gas concentration in the ammonia area is detected to quickly return to 100ppm After that, the sound and light alarm stops, and after 5 minutes, the second spray device on the upper part of the ammonia tank automatically stops, and all alarms in the system are eliminated. After the instantaneous leakage caused by careless ammonia unloading operation is absorbed by the water, the first spray device on the ammonia water unloading module is turned off, and the ammonia gas concentration in the ammonia zone remains below 100ppm.

Ammonia water storage tank: The upper part of the ammonia water storage tank is equipped with a second spraying device, the spray surface covers the entire tank top, the water source is connected to the owner's tap water, equipped with a solenoid valve, and a manual ball valve is installed before and after the solenoid valve. When the solenoid valve fails or the power is cut off, the sprinkler device is manually opened; the top of the tank is equipped with a safety relief valve, and when the gas phase pressure on the top of the tank is detected to be greater than 50bar, it will be automatically opened for pressure relief; the top of the tank is equipped with a Thermocouples are used for temperature measurement, and the data can be transmitted remotely. When the temperature of the tank body is greater than 45°C, the solenoid valve of the second spraying device on the upper part of the storage tank will be activated until the temperature drops to <45°C for more than 10 minutes, and the solenoid valve will be closed. stop spraying;

The basic part of the ammonia water storage tank is a hollow accident pool, and the part of the accident pool above the ground is used as a cofferdam to prevent the ammonia from overflowing when the tank leaks, causing a wide range of danger or pollution in the factory area. The part below the ground is used as an accident pool, and the underground part The pool and the ammonia water storage tank have the same volume. When the tank body leaks or other emergency conditions, the ammonia water in the ammonia water storage tank and the spray water in the accident state can be discharged to the accident pool. The accident pool is also equipped with an accident discharge pump. After the accident is eliminated The accident discharge pump can be activated to pump the ammonia water back to the tank truck or the ammonia water storage tank for reuse, avoiding waste and pollution. In addition, the accident pool is equipped with a cover plate whose elevation is flush with the ground of the ammonia area, and the cover plate reduces falling on the one hand On the other hand, it can prevent the ammonia gas from the accident pool from volatilizing into the environment.

The ammonia area is equipped with a composite spray/eyewash device (that is, the third spray device): because the inspectors did not wear protective masks and protective glasses during the operation and maintenance process, the ammonia gas was fumigated to the eyes, and the eyewash push plate ( Marked with push), start the eyewash, and spray with clean water for 15 minutes without any serious eyes. The inspectors accidentally came into contact with ammonia water, turned on the third spray device, and the spray head was able to discharge water smoothly.

Ammonia water delivery module: Since the ammonia water delivery module is a continuous operation equipment, and there are many pipe fitting interfaces, the first ammonia leak detector and the first sound and light alarm in the ammonia area are integrated on the ammonia water delivery module, when the first ammonia leak detector If the ammonia concentration in the environment is detected to be ≥180ppm, the first sound and light alarm will be activated, and the second spray device on the upper part of the ammonia water storage tank will be activated. Automatic stop; when the ammonia leak detector detects that the ammonia concentration in the environment is ≥180ppm, start the sound and light alarm and the second spray device for 15 minutes, and the ammonia concentration still does not drop, and the chain denitrification system protection stops.

Reductant distribution module: Since most of the reductant distribution modules are continuously operating equipment, and there are many pipe fittings, each connection is a source of danger for leakage points. The second ammonia leak detector and the second sound and light alarm of the reductant distribution module are installed inside the reductant distribution cabinet. When the second ammonia leak detector detects that the ammonia concentration in the reductant distribution cabinet is ≥ 150ppm, The two exhaust fans on the top of the reducing agent distribution cabinet will be started until the ammonia concentration is detected to be less than 150ppm, and the exhaust fan will stop automatically for more than 5 minutes; The ammonia gas concentration is ≥150ppm, and the exhaust fan on the top of the cabinet is started for a duration of ≥30 minutes. If the ammonia gas concentration still does not drop, the chain denitrification system will stop for protection.

Inside the reductant distribution cabinet, near the handle for easy operation, there is a red emergency button. When various leaks and blockages occur, press the emergency button of the reductant distribution cabinet, and the denitrification system will stop quickly ( All equipment stopped, valves closed, flushing program not started).

When the system is in normal operation, the first ammonia leak detector detects an ammonia concentration of 156ppm, and the exhaust fan on the top of the reductant distribution cabinet starts automatically, and the ammonia concentration drops to 30ppm after 5 minutes. Manual investigation found that there was an air leak at the connection of the main pipe regulating valve of the reductant distribution cabinet. After the leak was eliminated, the denitrification system was started by an automatic program. The ammonia leakage concentration in the reductant distribution cabinet remained <20ppm. After 5 minutes, the reductant distribution cabinet The exhaust fan on the top of the cabinet is automatically turned off.

Denitration control system: mainly composed of a denitrification control cabinet and a DCS operating platform. The DCS controller is installed in the denitrification control cabinet. The denitrification control system adopts a conventional control method for the control of the reducing agent distribution module

The denitrification control cabinet is placed in the denitrification control room near the ammonia area. There is another red emergency button at a height suitable for operation in the middle of the outside of the denitrification control cabinet. If the inspection finds that the ammonia water storage tank leaks and the ammonia water delivery pipeline leaks, press the denitrification control button. The emergency button of the cabinet, the denitrification system stops quickly (all equipment stops, valves are closed, and the flushing process is not started).

The DCS operation platform is equipped with a monitoring display screen, and a "quick stop" button is set on the main process interface. The central control operator finds that the system has serious ammonia leakage, and the system does not start the sound and light alarm and accident spraying. Click the "quick stop" button, all The equipment is stopped, the valves are closed, and the flushing program is not started.

Soft water source and flushing system: According to the safety technology of the present invention, a soft water source pump, a soft water storage tank and a soft water delivery module are configured for the denitrification system. When the system stops, it will automatically restart the program after stopping the system.

Click "Stop System" on the local touch screen of the denitrification control cabinet and the DCS operation platform, the equipment valves will stop in an orderly manner, and the flushing program will be started, the main pipe of the reducing agent distribution cabinet and the pneumatic valves on each branch will be opened, and the soft water delivery module will be started sequentially ( The soft water delivery pump is turned on, the soft water delivery pump outlet valve is opened), the delay is 40s, the soft water delivery module is stopped (the soft water delivery pump is turned off, the soft water delivery pump outlet pneumatic valve is closed), the main valve of the reducing agent distribution cabinet is closed, and the valve sequence of each branch Closed, the system stops.

Claims (8)

1. improve a cement furnace SNCR flue gas denitrification system for denitration security, comprise dore furnace, reducing agent distribution module, the spray gun connecting reducing agent distribution module and dore furnace, denitrification control module, by reducing agent distribution module soft water conveyor module in parallel and ammoniacal liquor feed system; Described ammoniacal liquor feed system comprises the ammoniacal liquor tank car, ammoniacal liquor Unload module, tank used for storing ammonia and the ammoniacal liquor conveyor module that connect successively, and described ammoniacal liquor conveyor module is connected with reducing agent distribution module; It is characterized in that,

The first spray equipment is provided with above described ammoniacal liquor Unload module, described tank used for storing ammonia top is provided with temperature sensor, pressure sensor and safety drain valve, the second spray equipment is provided with above described tank used for storing ammonia, described ammoniacal liquor conveyor module place is provided with the first ammonia leakage detector and first sound light crossing-signal, is provided with the 4th spray equipment above described ammoniacal liquor conveyor module;

Described reducing agent distribution module place is provided with the second ammonia leakage detector, rising tone light crossing-signal and exhaust fan;

Described temperature sensor, pressure sensor, the first ammonia leakage detector and the second ammonia leakage detector are all communicatively connected to denitrification control module;

Described second spray equipment, the 4th spray equipment, first sound light crossing-signal, rising tone light crossing-signal are all connected with the switch of exhaust fan and are controlled by denitrification control module;

Also be provided with the 3rd spray equipment for emergency processing near described tank used for storing ammonia, the 3rd spray equipment connects tank from the beginning;

Described second spray equipment and the 4th spray equipment are all with magnetic valve, and described magnetic valve connects and is controlled by denitrification control module.

2. improve the cement furnace SNCR flue gas denitrification system of denitration security according to claim 1, it is characterized in that, described denitrification control module is DCS controller.

3. improve the cement furnace SNCR flue gas denitrification system of denitration security according to claim 1, it is characterized in that, described ammoniacal liquor Unload module, ammoniacal liquor conveyor module, reducing agent distribution module and soft water conveyor module place are equipped with scram button.

4. improve the cement furnace SNCR flue gas denitrification system of denitration security according to claim 1, it is characterized in that, the front and back of described magnetic valve are also provided with manual ball valve, the shower nozzle of described second spray equipment and the 4th spray equipment is connected with bypass duct with on the inlet channel between corresponding magnetic valve, and this bypass duct is provided with bypass ball valve.

5. improve the cement furnace SNCR flue gas denitrification system of denitration security according to claim 1, it is characterized in that, be provided with accident pool below described tank used for storing ammonia, described accident pool comprises the cover plate at top at the bottom of the pond body and pond located below ground level, and described tank used for storing ammonia is installed on described cover plate.

6. improve the cement furnace SNCR flue gas denitrification system of denitration security according to claim 5, it is characterized in that, be provided with the cofferdam arranged around described tank used for storing ammonia above described cover plate, be provided with manhole bottom described cofferdam, manhole place correspondence is provided with manhole door.

7. improve the cement furnace SNCR flue gas denitrification system of denitration security according to claim 6, it is characterized in that, be equipped with shower water gathering-device below described first spray equipment, the 3rd spray equipment and the 4th spray equipment, this shower water gathering-device is by pipeline communication extremely described accident pool.

8. improve the cement furnace SNCR flue gas denitrification system of denitration security according to claim 7, it is characterized in that, the pond body bulk of described accident pool is not less than the dischargeable capacity of tank used for storing ammonia, is provided with some for supporting the pillar of cover plate in the body of described pond.