Novel process and equipment for recycling liquid ammonia from tail gas emission of reaction kettle

Abstract

The invention relates to a novel process and equipment for recycling liquid ammonia by discharging tail gas of a reaction kettle, which are applied to occasions in which excessive liquid ammonia is used as a reaction raw material and a temperature control carrier, and the excessive liquid ammonia is recycled after the reaction is finished. The system comprises a plurality of reaction kettles, a normal-temperature liquid ammonia tank, a low-temperature liquid ammonia tank, a liquid ammonia pump, a normal-temperature quick condenser, a low-temperature quick condenser, an ammonia gas compressor, a screw vacuum pump, a buffer separator, an ultralow-temperature refrigerating unit, a low-temperature refrigerant tank and a refrigerant circulating pump. The plurality of reaction kettles synchronously and sequentially carry out reaction and ammonia discharge processes; and after the reaction in the reaction kettle is finished, the reaction kettle is heated to discharge ammonia under pressure to a normal-temperature quick condenser for recovery, when the ammonia discharge amount is reduced, an ammonia compressor is started to pressurize the ammonia to feed the ammonia into the normal-temperature quick condenser for recovery, and condensed normal-temperature liquid ammonia is stored in a normal-temperature liquid ammonia tank. And finally, the residual ammonia is conveyed to an ultralow-temperature quick condenser by using a compressor and a screw vacuum pump to recover liquid ammonia, the residual ammonia can be ignored under high vacuum of the reaction kettle, and the ammonia recycling efficiency is 99.9% or above.

Description

Technical Field

[0001] The invention relates to a new process and equipment for recovering liquid ammonia from tail gas emission of a reactor, which is applied to the occasion where excess liquid ammonia is used as a reaction raw material and a temperature control carrier, and the excess liquid ammonia is recovered and recycled after the reaction is completed. Background Art

[0002] In the chemical industry, the reactor is a core equipment, and its operating efficiency and material utilization rate are directly related to the production cost and economic benefits of the enterprise. When liquid ammonia is used as an important carrier or raw material in the reaction, although its main function is to control the reaction temperature, improve the dispersion of raw materials and reduce side reactions, in actual situations, only a small part of the liquid ammonia is consumed as a reactant, and most of it needs to be effectively separated from the reaction products and reused.

[0003] In traditional processes, excess liquid ammonia is mostly treated by recycling it into ammonia water for export. This method not only increases the material handling costs of enterprises, but also brings market pressure on ammonia water sales. With the intensification of market competition and the improvement of environmental protection requirements, enterprises are in urgent need of a more efficient and economical liquid ammonia recovery method to reduce the purchase volume of liquid ammonia and the sales burden of ammonia water. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a new process and equipment for recovering liquid ammonia by discharging residual ammonia after reaction in a reactor, which has the advantages of efficient liquid ammonia recovery, etc.

[0006] (II) Technical solution

[0007] In order to achieve the above-mentioned purpose of efficient liquid ammonia recovery, the present invention provides the following technical solutions: a new process and equipment for recovering liquid ammonia from tail gas emissions from a reactor, comprising a plurality of reactors, a normal temperature liquid ammonia tank, a low temperature liquid ammonia tank, a liquid ammonia pump, a normal temperature fast condenser, a low temperature fast condenser, an ammonia compressor, a screw vacuum pump, a gas-ammonia separation buffer, an ultra-low temperature refrigeration unit, a low temperature refrigerant tank and a refrigerant circulation pump;

[0008] The multiple reactors are alternately subjected to the reaction and ammonia discharge process. After the reaction of the reactor is completed, the reactor is heated and pressurized to discharge ammonia to a normal temperature rapid condenser for recovery. When the ammonia discharge volume obviously drops to a flow rate of V1, the ammonia compressor is started to pressurize the ammonia and send it to a normal temperature rapid condenser for recovery. The condensed normal temperature liquid ammonia is stored in a normal temperature liquid ammonia tank. When the ammonia discharge volume obviously drops to a flow rate of V2, the screw vacuum pump is started, and the compressor and the screw vacuum pump are relayed to send the residual ammonia to an ultra-low temperature rapid condenser to recover liquid ammonia until the pressure in the reactor reaches a vacuum of 99.9KPa, and the liquid ammonia recovery is completed, and then the discharge procedure is entered; air is required to break the vacuum before discharge, and the reactor is cleaned after the discharge is completed, and then vacuumed and emptied again to prepare for feeding; the feeding process is vacuum feeding, first adding liquid ammonia, then adding other components, and entering the reaction stage after temperature adjustment.

[0009] Furthermore, the reactor is equipped with a pressure sensor and a temperature sensor for real-time monitoring of the pressure and temperature in the reactor, and is provided with an efficient sealing device to prevent leakage of reaction materials.

[0010] Furthermore, the reactor is connected to a gas-ammonia separation buffer via a pipeline for preliminary separation of ammonia and other impurities in the tail gas.

[0011] Furthermore, the ammonia discharge processes of the two reactors are both provided with flow control devices to ensure that the ammonia discharge process is stable and efficient.

[0012] Furthermore, the ultra-low temperature refrigeration unit is connected to the low temperature refrigerant tank, the refrigerant circulation pump and the low temperature fast condenser through pipelines to form a low temperature refrigerant refrigeration cycle to provide cooling capacity for the low temperature fast condenser.

[0013] Furthermore, the gas-ammonia separation buffer needs to be manually washed regularly, and the low-temperature liquid ammonia tank needs to be manually controlled to discharge to the normal-temperature liquid ammonia tank when the liquid level is high.

[0014] A method for recovering liquid ammonia from tail gas discharge of a reactor comprises the following steps:

[0015] 1) Ensure that all equipment is in good working condition and has completed necessary pre-inspection and cleaning, check the refrigerant adequacy of the ultra-low temperature refrigeration unit, and ensure that the low-temperature refrigerant tank and refrigerant circulation pump are operating normally to provide stable cooling capacity for the low-temperature fast condenser;

[0016] 2) The two reactors carry out the reaction process alternately. The cycle of each reactor varies depending on the reaction. The built-in pressure sensor and temperature sensor of the reactor monitor the pressure and temperature in the reactor in real time to ensure the stability of the reaction conditions. During the reaction, the efficient sealing device prevents the leakage of the reaction materials.

[0017] 3) After the reaction in the reactor is completed, ammonia is first naturally discharged to the normal temperature rapid condenser for condensation. When the flow rate reaches below the flow rate V1, the ammonia compressor is started to continue to send the pressurized ammonia gas to the normal temperature rapid condenser for condensation. The condensed normal temperature liquid ammonia is transported to the normal temperature liquid ammonia tank for storage through a liquid ammonia pump.

[0018] 4) When the ammonia discharge flow rate of the reactor reaches flow rate V2, the outlet pipeline of the ammonia compressor is connected to the inlet of the screw vacuum pump through the switching valve, the screw vacuum pump is started, and the vacuum is continued until the pressure in the reactor reaches the set pressure of -99.9KPa. During this process, the ammonia is sent to the low-temperature rapid condenser for ultra-low temperature condensation, and the condensed low-temperature atmospheric pressure liquid ammonia is transported to the low-temperature liquid ammonia tank for storage.

[0019] 5) If there is residual ammonia in the reaction product and alkali needs to be added to continue to drive out the ammonia, water is generally used for recovery to prevent contamination of the recovered liquid ammonia.

[0020] 6) Before discharging, use air to break the vacuum of the reactor, open the discharge valve, and discharge the materials in the reactor. After the discharge is completed, the reactor is thoroughly cleaned to remove residual materials and impurities, and the reactor is vacuumed again to prepare for vacuum feeding.

[0021] 7) Vacuum feeding method: first add liquid ammonia to the reactor, then add other components in sequence, and adjust the temperature as needed to make the reactants reach suitable reaction conditions. After confirming that all components have been correctly added and the temperature, pressure and other parameters are set correctly, start a new round of reaction process.

[0022] (III) Beneficial effects

[0023] Compared with the prior art, the present invention provides a new process and equipment for recovering liquid ammonia from tail gas discharge of a reactor, which has the following beneficial effects:

[0024] The new process and equipment for recovering liquid ammonia from the tail gas of the reactor, through refined condensation and recovery technology, realizes the efficient conversion of ammonia gas and residual liquid ammonia in the tail gas, directly recovers it into liquid ammonia, significantly improves resource utilization, and reduces unnecessary waste. Since most of the liquid ammonia can be recovered and reused, the amount of new liquid ammonia purchased by the enterprise is greatly reduced, thereby reducing the cost of raw materials. At the same time, it avoids the generation and sales of ammonia water, reduces the market pressure and logistics costs of the enterprise, and reduces the emission of ammonia gas into the atmosphere, reduces the risk of environmental pollution, and meets the current strict environmental protection regulations. In addition, by reducing waste generation, it promotes the green production and sustainable development of enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural block diagram of the present invention;

[0026] Figure 2 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] See also Figure 1 , a new process and equipment for recovering liquid ammonia from tail gas emission from a reactor, including multiple reactors, a normal temperature liquid ammonia tank, a low temperature liquid ammonia tank, a liquid ammonia pump, a normal temperature fast condenser, a low temperature fast condenser, an ammonia compressor, a screw vacuum pump, a gas-ammonia separation buffer, an ultra-low temperature refrigeration unit, a low temperature refrigerant tank, and a refrigerant circulation pump;

[0029] The multiple reactors are alternately subjected to the reaction and ammonia discharge process. After the reaction of the reactor is completed, the reactor is heated and pressurized to discharge ammonia to a normal temperature rapid condenser for recovery. When the ammonia discharge volume obviously drops to a flow rate of V1, the ammonia compressor is started to pressurize the ammonia and send it to a normal temperature rapid condenser for recovery. The condensed normal temperature liquid ammonia is stored in a normal temperature liquid ammonia tank. When the ammonia discharge volume obviously drops to a flow rate of V2, the screw vacuum pump is started, and the compressor and the screw vacuum pump are relayed to send the residual ammonia to an ultra-low temperature rapid condenser to recover liquid ammonia until the pressure in the reactor reaches a vacuum of 99.9KPa, and the liquid ammonia recovery is completed, and then the discharge procedure is entered; air is required to break the vacuum before discharge, and the reactor is cleaned after the discharge is completed, and then vacuumed and emptied again to prepare for feeding; the feeding process is vacuum feeding, first adding liquid ammonia, then adding other components, and entering the reaction stage after temperature adjustment.

[0030] It should be noted that the reactor is equipped with a pressure sensor and a temperature sensor for real-time monitoring of the pressure and temperature in the reactor, and is provided with an efficient sealing device to prevent leakage of reaction materials.

[0031] The reactor is connected to the gas-ammonia separation buffer through a pipeline, and is used for preliminarily separating ammonia and other impurities in the tail gas.

[0032] The ammonia discharge processes of the two reactors are both provided with flow control devices to ensure that the ammonia discharge process is stable and efficient.

[0033] The ultra-low temperature refrigeration unit is connected to the low temperature refrigerant tank, the refrigerant circulation pump and the low temperature fast condenser through pipelines to form a low temperature refrigerant refrigeration cycle to provide cooling capacity for the low temperature fast condenser.

[0034] The gas-ammonia separation buffer needs to be manually washed regularly, and the low-temperature liquid ammonia tank needs to be manually controlled to discharge to the normal-temperature liquid ammonia tank when the liquid level is high.

[0035] In addition, a programmable logic controller is introduced to realize the automated control of the entire process, including the alternating operation of reactors, automatic adjustment of pressure and temperature, and the start and stop of pumps and compressors.

[0036] Equipped with a touch screen operation interface, it is convenient for operators to monitor the status of each device in real time, adjust process parameters, and record operating data.

[0037] Establish a remote monitoring system to allow managers to monitor the entire process in the control room or remote location to improve management efficiency.

[0038] Develop a detailed regular maintenance plan for the equipment, including checking seals, replacing filter elements, cleaning condensers, etc., to ensure long-term and stable operation of the equipment.

[0039] Backup equipment is set up for key equipment, such as liquid ammonia pumps and ammonia compressors. When the main equipment fails, it can be quickly switched to the backup equipment to ensure production continuity.

[0040] A method for recovering liquid ammonia from tail gas discharge of a reactor comprises the following steps:

[0041] 1) Ensure that all equipment is in good working condition and has completed necessary pre-inspection and cleaning, check the refrigerant adequacy of the ultra-low temperature refrigeration unit, and ensure that the low-temperature refrigerant tank and refrigerant circulation pump are operating normally to provide stable cooling capacity for the low-temperature fast condenser;

[0042] 2) The two reactors carry out the reaction process alternately. The cycle of each reactor varies depending on the reaction. The built-in pressure sensor and temperature sensor of the reactor monitor the pressure and temperature in the reactor in real time to ensure the stability of the reaction conditions. During the reaction, the efficient sealing device prevents the leakage of the reaction materials.

[0043] 3) After the reaction in the reactor is completed, ammonia is first naturally discharged to the normal temperature rapid condenser for condensation. When the flow rate reaches below the flow rate V1, the ammonia compressor is started to continue to send the pressurized ammonia gas to the normal temperature rapid condenser for condensation. The condensed normal temperature liquid ammonia is transported to the normal temperature liquid ammonia tank for storage through a liquid ammonia pump.

[0044] 4) When the ammonia discharge flow rate of the reactor reaches flow rate V2, the outlet pipeline of the ammonia compressor is connected to the inlet of the screw vacuum pump through the switching valve, the screw vacuum pump is started, and the vacuum is continued until the pressure in the reactor reaches the set pressure of -99.9KPa. During this process, the ammonia is sent to the low-temperature rapid condenser for ultra-low temperature condensation, and the condensed low-temperature atmospheric pressure liquid ammonia is transported to the low-temperature liquid ammonia tank for storage.

[0045] 5) If there is residual ammonia in the reaction product and alkali needs to be added to continue to drive out the ammonia, water is generally used for recovery to prevent contamination of the recovered liquid ammonia.

[0046] 6) Before discharging, use air to break the vacuum of the reactor, open the discharge valve, and discharge the materials in the reactor. After the discharge is completed, the reactor is thoroughly cleaned to remove residual materials and impurities, and the reactor is vacuumed again to prepare for vacuum feeding.

[0047] 7) Vacuum feeding method: first add liquid ammonia to the reactor, then add other components in sequence, and adjust the temperature as needed to make the reactants reach suitable reaction conditions. After confirming that all components have been correctly added and the temperature, pressure and other parameters are set correctly, start a new round of reaction process.

[0048] The electrical components appearing in the article are all electrically connected to the main controller and the power supply. The main controller can be a conventional known device for control such as a computer, and the existing public power connection technology is not described in detail in the article.

[0049] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A new process and equipment for recovering liquid ammonia from tail gas emission from a reactor, comprising a plurality of reactors, a normal temperature liquid ammonia tank, a low temperature liquid ammonia tank, a liquid ammonia pump, a normal temperature fast condenser, a low temperature fast condenser, an ammonia compressor, a screw vacuum pump, a gas-ammonia separation buffer, an ultra-low temperature refrigeration unit, a low temperature refrigerant tank and a refrigerant circulation pump; Features: The multiple reactors are alternately subjected to the reaction and ammonia discharge process. After the reaction of the reactor is completed, the reactor is heated and pressurized to discharge ammonia to a normal temperature rapid condenser for recovery. When the ammonia discharge volume obviously drops to a flow rate of V1, the ammonia compressor is started to pressurize the ammonia and send it to a normal temperature rapid condenser for recovery. The condensed normal temperature liquid ammonia is stored in a normal temperature liquid ammonia tank. When the ammonia discharge volume obviously drops to a flow rate of V2, the screw vacuum pump is started, and the compressor and the screw vacuum pump are relayed to send the residual ammonia to an ultra-low temperature rapid condenser to recover liquid ammonia until the pressure in the reactor reaches a vacuum of 99.9KPa, and the liquid ammonia recovery is completed, and then the discharge procedure is entered; air is required to break the vacuum before discharge, and the reactor is cleaned after the discharge is completed, and then vacuumed and emptied again to prepare for feeding; the feeding process is vacuum feeding, first adding liquid ammonia, then adding other components, and entering the reaction stage after temperature adjustment.

2. A new process and equipment for recovering liquid ammonia from tail gas discharged from a reactor according to claim 1, characterized in that: The reactor is equipped with a pressure sensor and a temperature sensor for real-time monitoring of the pressure and temperature in the reactor, and is provided with an efficient sealing device to prevent leakage of reaction materials.

3. A new process and equipment for recovering liquid ammonia from tail gas discharge from a reactor according to claim 1, characterized in that: The reactor is connected to the gas-ammonia separation buffer through a pipeline, and is used for preliminarily separating ammonia and other impurities in the tail gas.

4. A new process and equipment for recovering liquid ammonia from tail gas discharge from a reactor according to claim 1, characterized in that: The ammonia discharge processes of the two reactors are both provided with flow control devices to ensure that the ammonia discharge process is stable and efficient.

5. A new process and equipment for recovering liquid ammonia from tail gas discharge from a reactor according to claim 1, characterized in that: The ultra-low temperature refrigeration unit is connected to the low temperature refrigerant tank, the refrigerant circulation pump and the low temperature fast condenser through pipelines to form a low temperature refrigerant refrigeration cycle to provide cooling capacity for the low temperature fast condenser.

6. A new process and equipment for recovering liquid ammonia from tail gas discharged from a reactor according to claim 1, characterized in that: The gas-ammonia separation buffer needs to be manually washed regularly, and the low-temperature liquid ammonia tank needs to be manually controlled to discharge to the normal-temperature liquid ammonia tank when the liquid level is high.

7. A method for recovering liquid ammonia from tail gas discharged from a reactor, characterized in that: The following steps are involved: 1) Ensure that all equipment is in good working condition and has completed necessary pre-inspection and cleaning, check the refrigerant adequacy of the ultra-low temperature refrigeration unit, and ensure that the low-temperature refrigerant tank and refrigerant circulation pump are operating normally to provide stable cooling capacity for the low-temperature fast condenser; 2) The two reactors carry out the reaction process alternately. The cycle of each reactor varies depending on the reaction. The built-in pressure sensor and temperature sensor of the reactor monitor the pressure and temperature in the reactor in real time to ensure the stability of the reaction conditions. During the reaction, the efficient sealing device prevents the leakage of the reaction materials. 3) After the reaction in the reactor is completed, ammonia is first naturally discharged to the normal temperature rapid condenser for condensation. When the flow rate reaches below the flow rate V1, the ammonia compressor is started to continue to send the pressurized ammonia gas to the normal temperature rapid condenser for condensation. The condensed normal temperature liquid ammonia is transported to the normal temperature liquid ammonia tank for storage through a liquid ammonia pump. 4) When the ammonia discharge flow rate of the reactor reaches flow rate V2, the outlet pipeline of the ammonia compressor is connected to the inlet of the screw vacuum pump through the switching valve, the screw vacuum pump is started, and the vacuum is continued until the pressure in the reactor reaches the set pressure of -99.9KPa. During this process, the ammonia is sent to the low-temperature rapid condenser for ultra-low temperature condensation, and the condensed low-temperature atmospheric pressure liquid ammonia is transported to the low-temperature liquid ammonia tank for storage. 5) If there is residual ammonia in the reaction product and alkali needs to be added to continue to drive out the ammonia, water is generally used for recovery to prevent contamination of the recovered liquid ammonia. 6) Before discharging, use air to break the vacuum of the reactor, open the discharge valve, and discharge the materials in the reactor. After the discharge is completed, the reactor is thoroughly cleaned to remove residual materials and impurities, and the reactor is vacuumed again to prepare for vacuum feeding. 7) Vacuum feeding method: first add liquid ammonia to the reactor, then add other components in sequence, and adjust the temperature as needed to make the reactants reach suitable reaction conditions. After confirming that all components have been correctly added and the temperature, pressure and other parameters are set correctly, start a new round of reaction process.

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