Pre-dechlorination system and process for catalytic reforming reaction product for capturing ammonium salt

Abstract

The dechlorination system comprises a reforming reaction product separator, a reforming hydrogen ammonium salt trapping tank, a reformate ammonium salt trapping tank, a reforming hydrogen dechlorination tank, a reformate dechlorination tank, a hydrogen recontact part and a reaction product separation pump. The reforming recycle hydrogen is treated by the reforming hydrogen ammonium salt trapping tank, so that most ammonium salt crystals separated out from a gas phase are removed, and the probability of ammonium salt blockage and corrosion leakage of a reforming recycle hydrogen compressor and a reforming mixed feeding heat exchanger is reduced; a reformed hydrogen ammonium salt trapping tank and a reformed oil ammonium salt trapping tank are arranged and used for collecting most ammonium chloride salt, the ammonium salt blocking probability of downstream equipment and pipelines is reduced, the chlorine adsorption amount of the dechlorination tank is reduced, meanwhile, the service life of a dechlorination agent is prolonged by 10-20%, and the annual consumption of the dechlorination agent of the device and the annual discharge amount of a waste dechlorination agent are reduced.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology and relates to a pre-chlorination system and process for capturing ammonium salts in catalytic reforming reaction products. Background Technology

[0002] In the catalytic reforming process, to maintain the good acidity and antioxidant function of the reforming catalyst, a chlorine content of 1.0-1.3% needs to be maintained on the reforming catalyst. Due to changes in the adsorption performance of the reforming catalyst and the balance of material concentration, the chlorine on the reforming catalyst will inevitably be continuously lost, resulting in trace amounts of chlorine entering the reforming reaction products, such as reformed hydrogen, reformed oil, and reformed liquefied petroleum gas.

[0003] The existing traditional dechlorination process involves setting up a reforming hydrogen dechlorination tank after the hydrogen re-contact section and before the reforming hydrogen product is sent out of the unit. A reforming oil dechlorination tank is set up after the hydrogen re-contact section and before the depentane tower (or stabilizer tower) to remove chlorine from the reforming reaction products. This can prevent chlorine from being carried into downstream equipment or units and causing chlorine corrosion in the downstream equipment or units.

[0004] In practical applications, monitoring the chlorine content at the outlet of the reforming hydrogen dechlorination tank and the reforming oil dechlorination tank can effectively protect downstream equipment or facilities. However, if the materials in the equipment and pipelines between the reforming reaction product separator and the reforming hydrogen dechlorination tank and the reforming oil dechlorination tank have not undergone dechlorination treatment, trace amounts of chlorides, water, sulfides, and ammonia in the reforming reaction products can easily form ammonium chloride salts at lower temperatures. This can lead to problems such as reduced compressor efficiency, increased system pressure drop, and corrosion leaks in the compressors, compressor inlet separators, compressor inlet filters, heat exchangers, air coolers, and pipelines between the reforming reaction product separator and the reforming hydrogen dechlorination tank and the reforming oil dechlorination tank due to ammonium salt crystallization.

[0005] Patent CN118667569A discloses a method and apparatus for dechlorinating reaction products in a reforming unit, which includes dechlorination tanks for both the gaseous and liquid phases of the reforming reaction products. However, when ammonium salt crystals form on the defoaming screen inside the reforming reaction product separator, causing an increase in pressure drop in the separation tank, the circulating hydrogen system may be unable to maintain normal operation, necessitating unplanned shutdowns. Furthermore, ammonium salt crystals can clog the top ceramic balls of the light hydrocarbon dechlorination tank and the reformed oil dechlorination tank, increasing the risk of system pressure drop. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides a pre-dechlorination system and process for capturing ammonium salts in catalytic reforming reaction products.

[0007] This invention provides a pre-dechlorination system for catalytic reforming reaction products that captures ammonium salts, comprising a reforming reaction product separator, a reforming hydrogen ammonium salt capture tank, a reforming oil ammonium salt capture tank, a reforming hydrogen dechlorination tank, a reforming oil dechlorination tank, a hydrogen re-contact section, and a reaction product separation pump; the reforming reaction product separator, the reforming hydrogen ammonium salt capture tank, the reforming hydrogen dechlorination tank, and the hydrogen re-contact section are connected in sequence; the reforming reaction product separator, the reaction product separation pump, the reforming oil ammonium salt capture tank, the reforming oil dechlorination tank, and the hydrogen re-contact section are connected in sequence.

[0008] Furthermore, the reforming hydrogen ammonium salt collection tank is connected to the reforming circulating hydrogen pipeline. After the ammonium salt crystals are removed by the reforming hydrogen ammonium salt collection tank, the circulating hydrogen is sent to the reforming circulating hydrogen compressor through the reforming circulating hydrogen pipeline.

[0009] Furthermore, the reforming reaction product separator is equipped with internal separation components. These components are made of 316L stainless steel or Monel and feature a high-density multi-layer mesh structure. They are fixed with a metal frame and have advantages such as low pressure drop, simple structure, and easy disassembly and replacement.

[0010] Furthermore, both the reforming hydrogen dechlorination tank and the reforming oil dechlorination tank are set up in parallel with two units.

[0011] Furthermore, both the reformed ammonium salt trap and the reformed oil ammonium salt trap are equipped with high-density Monel alloy trapping internals.

[0012] Furthermore, differential pressure indicators are installed at both the inlet and outlet of the reforming ammonium salt collection tank and the reforming oil ammonium salt collection tank. When the accumulation of ammonium salt crystals causes the tank differential pressure to rise, the collection tank is cut off for cleaning.

[0013] Furthermore, both the reformed ammonium hydroxide collection tank and the reformed oil ammonium hydroxide collection tank are equipped with a cleaning medium inlet and a saline wastewater outlet.

[0014] Furthermore, the cleaning medium can be deoxygenated water, demineralized water, or steam.

[0015] Furthermore, after cleaning the collection tank, dry nitrogen gas is introduced to replace and remove moisture before it is put back into use.

[0016] This invention also provides a pre-dechlorination process for capturing ammonium salts from catalytic reforming reaction products, employing the above-mentioned dechlorination system, and comprising the following steps:

[0017] 1) The reforming reaction products are fed into a gas-liquid separator for gas-liquid separation;

[0018] 2) The gaseous product separated in step 1) is sent to the reforming hydrogen ammonium salt collection tank. After removing the carried ammonium salt, part of it is returned to the reforming reaction as recycled hydrogen, and the rest is sent to the reforming hydrogen dechlorination tank to remove the carried chloride ions.

[0019] 3) The liquid phase product separated in step 1) is sent to the reformate ammonium salt collection tank to remove the carried ammonium salt, and then sent to the reformate dechlorination tank to remove the carried chloride ions.

[0020] 4) The liquid and gaseous products after the removal of ammonium salts and chloride ions are sent to the hydrogen re-contact section for further purification to obtain reformed hydrogen products and reformed oil products.

[0021] After processing with this invention, the reformed hydrogen products and reformed oil products (feed to the depentanizer or stabilizer) after hydrogen re-contact no longer require separate dechlorination tanks. All materials in the equipment and pipelines between the reforming reaction product separator and the reformed hydrogen production area, and between the depentanizer (or stabilizer), have undergone dechlorination treatment.

[0022] Compared with existing traditional technologies, the present invention has the following advantages:

[0023] 1) The reformed circulating hydrogen of this invention is treated by the reformed hydrogen ammonium salt trap, which removes most of the ammonium salt crystals precipitated in the gas phase, reducing the probability of ammonium salt blockage, corrosion and leakage in the reformed circulating hydrogen compressor and reformed mixed feed heat exchanger (especially the reformed mixed feed heat exchanger equipped with a hydrogen distributor).

[0024] 2) The process for dechlorination of catalytic reforming reaction products of the present invention includes a reforming ammonium chloride salt collection tank and a reforming oil ammonium chloride salt collection tank, which are used to collect most of the ammonium chloride salt, reduce the probability of ammonium salt blockage in downstream equipment and pipelines, reduce the amount of chlorine adsorption in the dechlorination tank, extend the service life of the dechlorinating agent by 10-20%, and reduce the annual consumption of dechlorinating agent and the annual discharge of waste dechlorinating agent.

[0025] 3) The process for dechlorination of catalytic reforming reaction products in this invention involves setting the reforming hydrogen dechlorination tank on the gas phase line of the hydrogen re-contact section of the reforming reaction product separator; and setting the reforming oil dechlorination at the pump outlet of the reforming reaction product gas-liquid separator, ensuring that there is no chlorine before reaching the hydrogen re-contact section and its downstream devices (or units, equipment), reducing the risk of ammonium salt crystallization blockage and corrosion in the compressor, equipment, pipelines, etc. of the hydrogen re-contact section; and providing a prerequisite for the continuous, stable, and long-term operation of the hydrogen re-contact section. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process of the present invention;

[0027] In the picture:

[0028] 1. Reforming reaction product separator; 2. Reforming ammonium salt collection tank; 3. Reforming oil ammonium salt collection tank; 4. Reforming hydrogen dechlorination tank; 5. Reforming oil dechlorination tank; 6. Reaction product separator pump; 7. Hydrogen re-contact section; 8. Separation internals. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments do not limit the scope of protection claimed by the present invention.

[0030] like Figure 1 As shown: After the gas and liquid phases of the reforming reaction product separator 1 are separated by the internal separation unit 8, the gas phase is separated from the top of the tank. After being processed by the reforming hydrogen ammonium salt collection tank 2, a portion is returned to the reforming reaction as circulating hydrogen, and the remainder enters the reforming hydrogen dechlorination tank 4 for dechlorination and then is sent to the hydrogen re-contact section 7 for purification. The bottom liquid phase of the reforming reaction product separator 1 is pressurized by the reaction product separator pump 6 and then enters the reforming oil ammonium salt collection tank 3 for processing. After being dechlorinated by the reforming oil dechlorination tank 5, it is sent to the hydrogen re-contact section 7 for further contact purification to obtain reformed hydrogen and reformed oil products. At this time, the reformed hydrogen and reformed oil entering the hydrogen re-contact section 7 no longer contain chlorine, and the hydrogen re-contact section 7 and its downstream devices, units, and equipment are effectively protected.

[0031] Both the reformed ammonium salt collection tank 2 and the reformed oil ammonium salt collection tank 3 are equipped with high-density Monel alloy collection internals, and differential pressure indicators are installed at both the inlet and outlet. When ammonium salt crystals accumulate to a certain amount and cause a high differential pressure alarm in the collection tank, the collection tank is temporarily shut off for cleaning. The cleaning medium for the internals of the collection tank is deoxygenated water, demineralized water, or steam. After cleaning, the collection tank is purged with nitrogen to remove moisture before being put back into service.

[0032] The above description is merely a typical example of the present invention and does not impose any limitation on the present invention. Any changes or modifications made by those skilled in the art using the above technical content without departing from the scope of the present invention should be considered equivalent examples of equivalent variations. Any equivalent changes made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention are within the scope of the present invention.

Claims

1. A pre-chlorination system for capturing ammonium salts in catalytic reforming reaction products, characterized in that: It includes a reforming reaction product separator, a reforming ammonium salt trapping tank, a reforming oil ammonium salt trapping tank, a reforming hydrogen dechlorination tank, a reforming oil dechlorination tank, a hydrogen re-contact section, and a reaction product separation pump; the reforming reaction product separator, the reforming ammonium salt trapping tank, the reforming hydrogen dechlorination tank, and the hydrogen re-contact section are connected in sequence; the reforming reaction product separator, the reaction product separation pump, the reforming oil ammonium salt trapping tank, the reforming oil dechlorination tank, and the hydrogen re-contact section are connected in sequence.

2. The pre-chlorination system for capturing ammonium salts in a catalytic reforming reaction product according to claim 1, characterized in that: The reformed hydrogen ammonium salt collection tank is connected to the reformed circulating hydrogen pipeline. After the ammonium salt crystals are removed by the reformed hydrogen ammonium salt collection tank, the circulating hydrogen is sent to the reformed circulating hydrogen compressor through the reformed circulating hydrogen pipeline.

3. The pre-dechlorination system for capturing ammonium salts in a catalytic reforming reaction product according to claim 1, characterized in that: The reforming reaction product separator is equipped with a separation internal component, which is a high-density multi-layer mesh structure made of 316L stainless steel or Monel and is fixed with a metal frame.

4. The pre-chlorination system for capturing ammonium salts in a catalytic reforming reaction product according to claim 1, characterized in that: Both the reforming hydrogen dechlorination tank and the reforming oil dechlorination tank are set up in parallel in pairs.

5. The pre-chlorination system for capturing ammonium salts in a catalytic reforming reaction product according to claim 1, characterized in that: Both the reformed ammonium hydroxide collection tank and the reformed oil ammonium hydroxide collection tank are equipped with high-bulk-density Monel alloy collection internals.

6. The pre-chlorination system for capturing ammonium salts in a catalytic reforming reaction product according to claim 1, characterized in that: The inlet and outlet of the reformed ammonium salt collection tank and the reformed oil ammonium salt collection tank are equipped with differential pressure indicators. When the accumulation of ammonium salt crystals causes the tank differential pressure to rise, the collection tank is cut off for cleaning.

7. The pre-chlorination system for capturing ammonium salts in a catalytic reforming reaction product according to claim 6, characterized in that: Both the reformed ammonium hydroxide collection tank and the reformed oil ammonium hydroxide collection tank are equipped with a cleaning medium inlet and a saline wastewater outlet.

8. The pre-chlorination system for capturing ammonium salts in a catalytic reforming reaction product according to claim 6, characterized in that: After cleaning, the collection tank is purged with dry nitrogen to remove moisture before being put back into use.

9. The pre-chlorination system for capturing ammonium salts in a catalytic reforming reaction product according to claim 7, characterized in that: The cleaning medium may be deoxygenated water, desalinated water, or steam.

10. A pre-chlorination process for capturing ammonium salts in catalytic reforming reaction products, characterized in that, Includes the following steps: 1) The reforming reaction products are fed into a gas-liquid separator for gas-liquid separation; 2) The gaseous product separated in step 1) is sent to the reforming hydrogen ammonium salt collection tank. After removing the carried ammonium salt, part of it is returned to the reforming reaction as recycled hydrogen, and the rest is sent to the reforming hydrogen dechlorination tank to remove the carried chloride ions. 3) The liquid phase product separated in step 1) is sent to the reformate ammonium salt collection tank to remove the carried ammonium salt, and then sent to the reformate dechlorination tank to remove the carried chloride ions. 4) The liquid and gaseous products after the removal of ammonium salts and chloride ions are sent to the hydrogen re-contact section for further purification to obtain reformed hydrogen products and reformed oil products.

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