Anti-explosion ammonia decomposition reactor system

Abstract

The anti-explosion ammonia decomposition reactor system comprises an ammonia decomposition reactor, an anti-explosion part and a combustible gas detection and treatment part, the explosion-proof part comprises a closed explosion-proof shell, a nitrogen source, a nitrogen flow regulating valve, a heat exchanger and an electric heating furnace, and the gas detection and treatment part comprises an online analyzer and a tail gas treatment device; the ammonia decomposition reactor is arranged in the explosion-proof shell, and a nitrogen source is sequentially connected with the heat exchanger and the electric heating furnace through a nitrogen flow regulating valve, then is filled into the explosion-proof shell through a nitrogen inlet of the explosion-proof shell and is discharged out of the explosion-proof shell through a gas vent; the gas emptying port is connected with the heat exchanger, and nitrogen containing combustible gas is subjected to heat exchange and then is sent to the tail gas treatment device and the online analyzer; and the nitrogen flow regulating valve and the online analyzer are connected to a DCS (Distributed Control System) and are in cascade control connection. The explosion-proof ammonia decomposition reactor system can automatically detect and dispose combustible gas, and has a good explosion-proof effect.

Description

Technical Field

[0001] The invention belongs to the technical field of ammonia decomposition, and relates to an ammonia decomposition reactor, and in particular to an ammonia decomposition reactor system with good explosion-proof effect and self-detection and disposal of combustible gas. Background Art

[0002] Ammonia decomposition reactor is a chemical reaction device that decomposes ammonia into nitrogen and hydrogen. It is widely used in fertilizer, petrochemical, natural gas processing and other fields. However, ammonia decomposition reactor involves flammable gases such as hydrogen and ammonia during use. If these flammable gases encounter a fire source under certain circumstances, they may cause an explosion.

[0003] In practical applications, existing ammonia decomposition reactors and systems have some problems with combustible gas explosion prevention. First, since the ammonia decomposition reaction involves ammonia, it is easy to corrode pipelines, causing combustible gas leakage and explosion risks. Therefore, how to reduce the explosion risk of gas leakage is the key to improving the safety of ammonia decomposition production. Secondly, there are also difficulties in detecting the content of combustible gas on site, and it is impossible to safely and timely collect and analyze the content of combustible gas on site. Therefore, how to ensure the safe operation of the ammonia decomposition reactor and prevent the occurrence of explosion accidents is an urgent problem to be solved. Summary of the invention

[0004] The object of the present invention is to provide an ammonia decomposition reactor system with good explosion-proof effect. It can eliminate potential explosion risks, prevent the occurrence of explosion accidents and ensure the safe operation of the device, in order to solve the problems of combustible gas leakage in existing ammonia decomposition reactors and the inability to safely and timely collect and dispose of on-site combustible gas.

[0005] The technical solution adopted by the present invention to solve the technical problem is: An explosion-proof ammonia decomposition reactor system, comprising an ammonia decomposition reactor, characterized in that the ammonia decomposition reactor system further comprises an explosion-proof part and a combustible gas detection and processing part; the explosion-proof part comprises a closed explosion-proof housing, a nitrogen source and a nitrogen flow regulating valve, a heat exchanger and an electric heating furnace, and the gas detection and processing part comprises an online analyzer and an exhaust gas treatment device; The ammonia decomposition reactor is placed in the explosion-proof housing of the explosion-proof part, and the internal space thereof contains the combustible gas generated by the ammonia decomposition reactor; a nitrogen inlet and a gas vent are provided on the explosion-proof housing, and the nitrogen source is connected to the heat exchanger and the electric heating furnace in sequence through a nitrogen flow regulating valve, and then connected to the nitrogen inlet, and the nitrogen is filled into the explosion-proof housing from the nitrogen inlet, and discharged from the explosion-proof housing from the gas vent; The nitrogen containing combustible gas discharged from the explosion-proof housing is sent to the gas detection processing unit; the gas vent is connected to the heat exchanger, and the nitrogen containing combustible gas is sent to the tail gas treatment device and the online analyzer of the gas detection processing unit after heat exchange; The nitrogen flow regulating valve and the online analyzer are connected to a DCS control system, and the online analyzer is connected to the nitrogen flow regulating valve in cascade control.

[0006] The explosion-proof ammonia decomposition reactor system continuously fills nitrogen into the explosion-proof housing of the explosion-proof part during the reaction process of the ammonia decomposition reactor, and discharges it to the gas detection and processing part for detection and processing. The gas detection and processing part includes an exhaust gas treatment device and an online analyzer. The online analyzer automatically samples at regular intervals and then analyzes and detects the content of combustible gas (ammonia and hydrogen) online, monitors whether the ammonia decomposition device leaks, and outputs the detection results of the online analyzer to the DCS control system, which regulates the control module of the nitrogen flow regulating valve. The nitrogen flow is regulated by the control module to achieve the purpose of replenishing nitrogen into the explosion-proof housing for rapid replacement. The nitrogen containing combustible gas discharged from the explosion-proof housing enters the exhaust gas treatment device.

[0007] Furthermore, the DCS control system includes a first threshold value. When the hydrogen or ammonia content detected by the online analyzer exceeds the first threshold value, the opening of the nitrogen flow regulating valve is controlled to increase; when the hydrogen or ammonia content is lower than the first threshold value, the opening of the nitrogen flow regulating valve is controlled to decrease.

[0008] Preferably, the first threshold value is a volume percentage of hydrogen or ammonia of 0.5%.

[0009] Furthermore, the ammonia decomposition reactor is a reactor of various forms known in the prior art, including a fixed bed reactor, a fluidized bed reactor and a catalytic membrane reactor, such as a commonly used shell-and-tube fixed bed reactor.

[0010] Further, the exhaust gas treatment device is a tail gas treatment device of various forms known in the prior art, including a regenerative thermal oxidizer (RTO), a regenerative catalytic combustion (RCO) tail gas treatment device, and a super low emission combustion (CEB) tail gas treatment device. Preferably, the tail gas treatment device is a super low emission combustion (CEB) tail gas treatment device.

[0011] Furthermore, the online analyzer includes an online hydrogen analyzer and an online ammonia analyzer.

[0012] Furthermore, a cooler is provided before the online analyzer.

[0013] Furthermore, an ammonia valve is provided at the ammonia inlet of the ammonia decomposition reactor, and the nitrogen source is connected to the ammonia inlet downstream of the ammonia valve via the nitrogen valve; a decomposition gas valve is provided at the decomposition gas outlet of the ammonia decomposition reactor, and the decomposition gas valve is connected to the flare upstream via a discharge valve.

[0014] Preferably, the nitrogen valve, ammonia valve, decomposition gas valve and discharge valve are automatic stop valves connected to a DCS control system.

[0015] Furthermore, the DCS control system includes a second threshold value. When the hydrogen or ammonia content detected by the online analyzer exceeds the second threshold value, the DCS control system linkage control closes the ammonia valve, opens the nitrogen valve, closes the ammonia decomposition reaction, purges the ammonia decomposition reactor, and at the same time closes the decomposition gas valve, opens the discharge valve, and sends the purged decomposition gas into the flare to prevent it from entering the downstream of the reactor.

[0016] Preferably, the second threshold value is 3% volume percentage of hydrogen or ammonia.

[0017] Beneficial effects: The explosion-proof ammonia decomposition reactor system of the present invention can automatically detect and dispose of combustible gases, effectively reduce the possibility of explosion caused by leakage in the ammonia decomposition reactor, has good explosion-proof effect, and can safely, efficiently and conveniently monitor the ammonia decomposition device, reducing the risk of explosion caused by leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the explosion-proof ammonia decomposition reactor system of the present invention; Among them, 1: explosion-proof shell; 2: heat exchanger; 3: exhaust gas treatment device; 4: online analyzer; 5: cooler; 6: nitrogen flow control valve; 7: nitrogen valve; 8: ammonia valve; 9: decomposition gas valve; 10: discharge valve; 11: electric heating furnace; 12: ammonia decomposition reactor. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiment is only a specific embodiment of the present invention, not all embodiments. Based on the description of the present invention and the embodiments therein, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] like Figure 1As shown, an explosion-proof ammonia decomposition reactor system of the present invention includes an ammonia decomposition reactor 12, an explosion-proof part and a combustible gas detection and processing part. The explosion-proof part includes a closed explosion-proof housing 1, a nitrogen source, a nitrogen flow regulating valve 6, a heat exchanger 2 and an electric heating furnace 11, and the gas detection and processing part includes a cooler 5, an online analyzer 4 and an exhaust gas treatment device 3.

[0021] The ammonia decomposition reactor 12 is a tube-type fixed bed ammonia decomposition reactor, which is located inside the explosion-proof housing 1. The ammonia decomposition reactor 12 includes a catalyst fixed bed layer, ammonia enters the reactor from the ammonia inlet, the gas reacts through the catalyst bed, and the decomposition gas flows out from the decomposition gas outlet. An ammonia valve 8 is provided at the ammonia inlet, and a decomposition gas valve 9 is provided at the decomposition gas outlet. The explosion-proof housing 1 completely contains the ammonia decomposition reactor 12, and is firmly welded with steel plates, and the weld scars are polished flat. The reactor inlet and outlet, nitrogen inlet and gas vent are respectively provided on different sides. The ammonia inlet and decomposition gas outlet of the ammonia decomposition reactor 12 enter and exit the explosion-proof housing 1 through the reactor inlet and outlet, and each connection port is firmly welded, and the weld scars are polished flat. Once the ammonia decomposition reactor leaks, combustible gases such as hydrogen and ammonia will enter the explosion-proof housing 1 to prevent further leakage.

[0022] In the explosion-proof part, the explosion-proof shell 1 includes a nitrogen inlet and a gas vent, the nitrogen inlet is connected to a nitrogen source, nitrogen is sequentially filled into the explosion-proof shell 1 from the nitrogen inlet through a nitrogen flow regulating valve 6, a heat exchanger 2 and an electric heating furnace 11, the nitrogen in the explosion-proof shell 1 carries the combustible gas leaked from the ammonia decomposition reactor 12 and is discharged from the explosion-proof shell 1 from the gas vent, the nitrogen exchanges heat with the gas discharged from the explosion-proof shell 1 through the heat exchanger 2, and is heated by the electric heating furnace 11 to ensure that the entry of nitrogen will not cause the material in the ammonia decomposition reactor 12 to be suddenly cooled or the reaction temperature to drop.

[0023] The nitrogen containing combustible gas discharged from the explosion-proof housing 1 is sent to the gas detection processing unit. The nitrogen containing combustible gas enters the heat exchanger 2 from the gas vent, and is sent to the tail gas treatment device 3 for treatment after heat exchange with the nitrogen. The tail gas treatment device 3 adopts an ultra-low emission combustion (CEB) tail gas treatment device.

[0024] In order to analyze the content of combustible gas in the detection gas, the sampling port after the heat exchanger 2 is connected to the online analyzer 4 through the cooler 5.

[0025] The online analyzer 4 includes an online hydrogen analyzer and an online ammonia analyzer, such as a PDM400 online hydrogen analyzer and a SGA-500B-NH3 online ammonia analyzer. The online analyzer 4 is connected to a DCS control system, and the nitrogen flow regulating valve 6 of the explosion-proof part is simultaneously connected to the DCS control system, and the online analyzer 4 and the nitrogen flow regulating valve 6 are connected in cascade control.

[0026] In the event of a serious leak in the ammonia decomposition reactor 12, in order to interrupt the reaction in time, a nitrogen valve 7 and a discharge valve 10 are provided in the ammonia decomposition reactor 12, the nitrogen source is connected to the ammonia inlet of the ammonia decomposition reactor 12 downstream of the ammonia valve 8 through the nitrogen valve 7, and the decomposition gas outlet is connected to the flare upstream of the decomposition gas valve 9 through the discharge valve 10. The nitrogen valve 7, ammonia valve 8, decomposition gas valve 9 and discharge valve 10 are all automatic stop valves, and their actuators are connected to the DCS control system.

[0027] The DCS control system includes a first threshold and a second threshold, which are 0.5% and 3% of the volume percentage of hydrogen or ammonia, respectively. When the hydrogen or ammonia content detected by the online analyzer 4 exceeds the first threshold, the nitrogen flow regulating valve 6 is controlled to increase its opening, and when the hydrogen or ammonia content is lower than the first threshold, the nitrogen flow regulating valve 6 is controlled to decrease its opening. When the hydrogen or ammonia content detected by the online analyzer exceeds the second threshold, the DCS control system is controlled to close the ammonia stop valve 8, open the nitrogen stop valve 7, close the ammonia decomposition reaction, purge the ammonia decomposition reactor 12, and at the same time close the decomposition gas stop valve 9, open the discharge stop valve 10, and send the purged decomposition gas to the flare to prevent it from entering the downstream of the reactor.

[0028] According to the explosion-proof ammonia decomposition reactor system of the present invention, the ammonia decomposition reactor 12 is completely contained in the explosion-proof housing 1. In the space between the ammonia decomposition reactor 12 and the explosion-proof housing 1, N2 is adjusted by the nitrogen flow control valve 6 and heated by the electric heating furnace 11, and then replaces the air inside the explosion-proof housing 1 and continuously fills with nitrogen. The ammonia decomposition reactor 12 may produce combustible gases such as hydrogen, ammonia, etc. during use. If these combustible gases encounter a fire source under certain circumstances, they may cause an explosion accident. By continuously replacing the gas between the ammonia decomposition reactor 12 and the explosion-proof housing 1 with N2, the nitrogen that dilutes the combustible gases (ammonia and hydrogen) in the explosion-proof housing 1 enters the tail gas treatment device 3 through the gas venting port, which can effectively reduce the explosion risk of the ammonia decomposition device and achieve a good explosion-proof effect.

[0029] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. An explosion-proof ammonia decomposition reactor system, comprising an ammonia decomposition reactor (12), characterized in that: The ammonia decomposition reactor system further comprises an explosion-proof part and a combustible gas detection and processing part; the explosion-proof part comprises a closed explosion-proof housing (1), a nitrogen source, a nitrogen flow regulating valve (6), a heat exchanger (2) and an electric heating furnace (11); the gas detection and processing part comprises an online analyzer (4) and an exhaust gas treatment device (5); The ammonia decomposition reactor (12) is placed in the explosion-proof housing (1) of the explosion-proof part, and the internal space thereof contains the combustible gas generated by the ammonia decomposition reactor (12); a nitrogen inlet and a gas vent are provided on the explosion-proof housing (1); the nitrogen source is connected to the heat exchanger (2) and the electric heating furnace (11) in sequence through a nitrogen flow regulating valve (6), and then connected to the nitrogen inlet; the nitrogen is filled into the explosion-proof housing (1) through the nitrogen inlet, and is discharged from the explosion-proof housing (1) through the gas vent; The nitrogen containing combustible gas discharged from the explosion-proof housing (1) is sent to the gas detection processing unit; the gas vent is connected to the heat exchanger (2), and the nitrogen containing combustible gas is sent to the tail gas treatment device (3) and the online analyzer (4) respectively after heat exchange; The nitrogen flow regulating valve (6) and the online analyzer (4) are connected to a DCS control system, and the online analyzer (4) and the nitrogen flow regulating valve (6) are connected in cascade control.

2. The explosion-proof ammonia decomposition reactor system according to claim 1, characterized in that: The DCS control system comprises a first threshold value. When the hydrogen or ammonia content detected by the online analyzer (4) exceeds the first threshold value, the nitrogen flow regulating valve (6) is controlled to increase its opening degree. When the hydrogen or ammonia content is lower than the first threshold value, the nitrogen flow regulating valve (6) is controlled to decrease its opening degree.

3. The explosion-proof ammonia decomposition reactor system according to claim 2, characterized in that: The first threshold value is that the volume percentage of hydrogen or ammonia is 0.5%.

4. The explosion-proof ammonia decomposition reactor system according to claim 1, characterized in that: The ammonia decomposition reactor (12) is a shell-and-tube fixed bed reactor.

5. The explosion-proof ammonia decomposition reactor system according to claim 1, characterized in that: The tail gas treatment device (3) is an ultra-low emission combustion tail gas treatment device, a regenerative thermal oxidation furnace or a regenerative thermal catalytic combustion tail gas treatment device.

6. The explosion-proof ammonia decomposition reactor system according to claim 1, characterized in that: The online analyzer (4) is an online hydrogen analyzer and an online ammonia analyzer, and a cooler (5) is arranged in front of the online analyzer (4).

7. The explosion-proof ammonia decomposition reactor system according to claim 1, characterized in that: An ammonia valve (8) is provided at the ammonia inlet of the ammonia decomposition reactor (12), and the nitrogen source is connected to the ammonia inlet downstream of the ammonia valve (8) via a nitrogen valve (7); a decomposition gas valve (9) is provided at the decomposition gas outlet of the ammonia decomposition reactor (12), and the decomposition gas valve (9) is connected to a flare upstream via a discharge valve (10).

8. The explosion-proof ammonia decomposition reactor system according to claim 7, characterized in that: The nitrogen valve (7), ammonia valve (8), decomposition gas valve (9) and discharge valve (10) are automatic stop valves connected to a DCS control system.

9. The explosion-proof ammonia decomposition reactor system according to claim 8, characterized in that: The DCS control system includes a second threshold value. When the hydrogen or ammonia content detected by the online analyzer (4) exceeds the second threshold value, the DCS control system controls to close the ammonia valve (8), open the nitrogen valve (7), close the decomposition gas valve (9), and open the discharge valve (10).

10. The explosion-proof ammonia decomposition reactor system according to claim 9, characterized in that: The second threshold value is that the volume percentage of hydrogen or ammonia is 3%.

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