Acid regeneration system

Abstract

An acid regeneration system, comprising a reaction unit (1), a separation unit (3), and a heat exchange unit (4), wherein the reaction unit (1) is used for combusting a fuel (13) and a preheated combustion-supporting gas (12) so as to generate an exhaust gas, the separation unit (3), which is provided downstream of the reaction unit (1), is used for separating the exhaust gas so as to remove solid particles in the exhaust gas, and the heat exchange unit (4), which is is provided downstream of the separation unit (3), is used for preheating the combustion-supporting gas (11) by using the exhaust gas separated by the separation unit (3), so as to obtain the preheated combustion-supporting gas (12). The acid regeneration system has the advantages that the heat from the exhaust gas generated by means of combustion can be recycled by the heat exchange unit (4) to recover and reuse same to effectively preheat the combustion-supporting gas (11), so as to achieve optimal heat recovery and minimal energy consumption; and the exhaust gas is subjected to gas-solid separation to remove solid particles in the exhaust gas by using the separation unit (3), thereby preventing the solid particles from fouling in the heat exchange unit (4) and avoiding the problem of a reduced heat exchanger efficiency. The acid regeneration system can be applied to acid regeneration units of different scales, and can also be applied to the regeneration of waste acid of different concentrations.

Description

An acid regeneration system TECHNICAL FIELD

[0001] The present utility model relates to the technical field of fluidized bed acid regeneration, in particular to an acid regeneration system. BACKGROUND

[0002] In fluidized bed acid regeneration plants (FB-ARPs), a plurality of burners are generally installed at the bottom of the interior of the reactor. These burners are usually combusted using fuel gas, but can also be combusted using liquid fuel. For safe operation of the burners, they must have a flame control function. This ensures that all fuel is combusted and avoids any uncontrolled combustion or explosion. There are various flame monitoring systems on the market, one of the most common being an ultraviolet detector.

[0003] Fluidized bed acid regeneration plants usually use ultraviolet detectors in the heated reactor. However, during operation, the reactor is filled with granular oxides, which prevent optical flame monitoring. Other systems, such as flame rods, cannot be used because the highly abrasive oxides quickly damage such equipment. Therefore, the process temperature of the fluidized bed technology (FB-Technology) must be kept at a level well above the self-ignition temperature of the fuel, because flame monitoring is not required above this temperature. This is called high-temperature operation. National laws and standards specify a critical temperature above which high-temperature operation without flame monitoring is permitted.

[0004] For example, in Europe, EN 746-2 specifies the relevant content. According to EN 746-2, the critical temperature for fuel gas is 750°C. In practice, the actual process temperature is even higher to ensure continuous operation without sudden stoppages due to technical faults. The typical process temperature of a fluidized bed acid regeneration plant is 850°C.

[0005] Generally, the process offgas leaving the reactor is slightly cooler than the reactor temperature (750-800°C). In the subsequent process, in particular when absorbing HCl gas, the process gas needs to be cooled to below 100°C. Since the energy content in the offgas is high, it is very advantageous to recover this energy to reduce the overall energy consumption. This can be achieved by a Venturi quench, using the spent acid to cool the offgas. By this method, part of the water in the spent acid is evaporated and the spent acid is pre-concentrated. Any water evaporated before the acid is injected into the reactor reduces the energy consumption of the process.

[0006] However, the possibility of energy recovery described above is limited by the concentration of iron (Fe) in the spent acid. Iron in the spent acid is mainly in the form of FeCl2, and partially in the form of FeCl3. During the pre-concentration of the spent acid, the concentration of iron increases.

[0007] Since the solubility of iron in the pre-concentrated spent acid is about 270 g / l. Exceeding this concentration will cause crystallization to form solid FeCl2, which will immediately cause pipe blockage and even equipment damage. If the iron concentration in the original spent acid is about 95 g / l, then under the above normal operating conditions, the solubility limit of 270 g / l will be reached. This means that when the iron concentration exceeds 95 g / l, additional water needs to be added in the Venturi quencher to avoid crystallization of the pre-concentrated acid. Therefore, the higher the concentration of iron, the higher the energy consumption. When the typical iron concentration is 120 g / l, the energy consumption is 25% higher.

[0008] In order to reduce the energy consumption of the acid with an iron concentration exceeding 95 g / l, an additional method is also needed to recover the energy in the reactor off-gas. One of the solutions to achieve this goal is to use the reactor off-gas to preheat the combustion air. In this way, the energy needed to be added in the reactor will be reduced, and the fuel consumption will also be reduced. In various applications, combustion air preheating is a well-known energy-saving method.

[0009] Chinese utility model patent CN212068677U discloses a reactor and preheater device. In the utility model patent, the reactor wall is used as a heat exchanger to preheat the combustion air using the energy contained in the reactor gas. The preheater is an integral part of the reactor. However, this has the following disadvantages:

[0010] 1) The surface of the heat exchanger is limited by the size of the reactor, which may not be sufficient to achieve full energy recovery;

[0011] 2) Damage to the heat exchanger will actually damage the reactor, resulting in direct shutdown;

[0012] 3) The process gas contains a large amount of solid particles, which will cause fouling of the heat exchanger surface, thereby reducing the working efficiency of the heat exchanger.

[0013] At present, there is no effective solution to the problems of low energy utilization rate of waste gas, integrated design of heat exchanger and reactor leading to easy damage, leakage, overheating of reactor, and reduction of heat exchanger efficiency due to fouling of solid particles in the related art.

[0014] Utility model content

[0015] The utility model discloses a kind of acid regeneration systems, to solve the problems such as low waste gas energy utilization, heat exchanger and reactor integrated design lead to easily appear damage shutdown, leakage, reactor overheating, heat exchanger efficiency reduction due to solid particle fouling in related art.

[0016] To achieve the above object, the technical scheme adopted by the utility model is:

[0017] A kind of acid regeneration system, comprising:

[0018] Reaction unit, for fuel and preheated combustion-supporting gas combustion to produce waste gas;

[0019] Separation unit, the separation unit is arranged downstream of the reaction unit, for separating waste gas to remove solid particles in waste gas;

[0020] Heat exchange unit, the heat exchange unit is arranged downstream of the separation unit, for using waste gas after separation processing by the separation unit to preheat combustion-supporting gas to obtain preheated combustion-supporting gas.

[0021] In some embodiments, the reaction unit comprises:

[0022] Several nozzle elements, several the nozzle element is distributed and arranged at the bottom of the reaction unit, for obtaining fuel, preheated combustion-supporting gas and mixing fuel, preheated combustion-supporting gas.

[0023] In some embodiments, further comprising:

[0024] Waste gas unit, the waste gas unit is arranged between the reaction unit and the separation unit, for conveying waste gas generated by the reaction unit to the separation unit.

[0025] In some embodiments, further comprising:

[0026] Cooling unit, the cooling unit is arranged downstream of the heat exchange unit, for cooling waste gas after processing by the heat exchange unit.

[0027] In some embodiments, further comprising:

[0028] Adjusting unit, the adjusting unit is arranged between the gas inlet and the gas outlet of the heat exchange unit, for adjusting the temperature of preheated combustion-supporting gas.

[0029] In some embodiments, the heat exchange unit is any one or combination of single-pipe heat exchanger, double-pipe heat exchanger, tube bundle heat exchanger.

[0030] In some embodiments, the heat exchange unit is a tube bundle heat exchanger having at least two tubes arranged at a hot end.

[0031] In some embodiments, the heat exchange unit is made of heat-resistant steel material to resist HCl gas in the exhaust gas.

[0032] In some embodiments, the surface of the heat exchange unit is further covered with a corrosion-resistant coating.

[0033] In some embodiments, the corrosion-resistant coating is any one or a combination of metal coating, metal oxide coating, and ceramic coating.

[0034] In some embodiments, the metal coating comprises a nickel-based alloy.

[0035] In some embodiments, the metal oxide coating comprises FeO, Fe2O3, and Fe3O4.

[0036] The utility model discloses the above technical scheme, compared with the prior art, has the following technical effects:

[0037] The acid regeneration system of the utility model, utilize heat exchange unit to the heat of the exhaust gas produced by combustion recycling, can effectively preheat combustion gas, thereby obtaining optimal heat recovery and minimum energy consumption, utilize separation unit to carry out gas-solid separation to the exhaust gas to remove the solid particle in the exhaust gas, avoid the solid particle in heat exchange unit scale, avoid the problem of heat exchanger efficiency reduction, can be applicable to different scale acid regeneration unit, also can be applicable to different concentration waste acid regeneration. BRIEF DESCRIPTION OF DRAWINGS

[0038] Fig. 1 is a schematic diagram of an acid regeneration system according to an embodiment of the utility model (I);

[0039] Fig. 2 is a schematic diagram of an acid regeneration system according to an embodiment of the utility model (II);

[0040] Fig. 3 is a schematic diagram of an acid regeneration system according to an embodiment of the utility model (III);

[0041] Fig. 4 is a schematic diagram of an acid regeneration system according to an embodiment of the utility model (IV).

[0042] The reference signs therein are: 1, reaction unit; 2, exhaust unit; 3, separation unit; 4, heat exchange unit; 5, cooling unit; 6, gas-liquid separation unit; 7, supply unit; 8, adjustment unit; 9, nozzle element; 11, combustion gas; 12, preheated combustion gas; 13, fuel; 21, first acid liquid; 22, second acid liquid; 23, third acid liquid. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0044] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0045] The present application will be further described below with reference to the drawings and specific embodiments, but is not limited to the present application.

[0046] Embodiment 1

[0047] An exemplary embodiment of the present application is shown in FIG. 1, which is an acid regeneration system, comprising a reaction unit 1, a separation unit 3 and a heat exchange unit 4. The reaction unit 1 is used for combustion of fuel 13 and preheated combustion-supporting gas 12 to generate exhaust gas. The separation unit 3 is arranged downstream of the reaction unit 1 and is used for separating the exhaust gas to remove solid particles in the exhaust gas. The heat exchange unit 4 is arranged downstream of the separation unit 3 and is used for preheating the combustion-supporting gas 11 by using the exhaust gas treated by the separation unit 3 to obtain the preheated combustion-supporting gas 12.

[0048] In some embodiments, the reaction unit 1 includes, but is not limited to, a burner.

[0049] In some embodiments, the reaction unit 1 includes a plurality of nozzle elements 9. The plurality of nozzle elements 9 are arranged at the bottom of the reaction unit 1 and are used for obtaining the fuel 13, the preheated combustion-supporting gas 12 and mixing the fuel 13 and the preheated combustion-supporting gas 12.

[0050] Generally, at least one nozzle element 9 is used for obtaining the fuel 13, and at least one nozzle element 9 is used for obtaining the preheated combustion-supporting gas 12.

[0051] The separation unit 3 is arranged at the exhaust gas discharge position of the reaction unit 1 and is in communication with the reaction unit 1 and the heat exchange unit 4, respectively.

[0052] In some embodiments, the separation unit 3 is also used for transporting the separated solid particles to the reaction unit 1.

[0053] In some embodiments, the separation unit 3 is a cyclone separator.

[0054] Generally, the heat exchange unit 4 comprises a heat exchanger, an inlet port and an outlet port. The heat exchanger is arranged downstream of the separation unit 3 and communicates with the separation unit 2, for obtaining the exhaust gas which has been subjected to the gas-solid separation treatment by the separation unit 3; the inlet port is arranged at the end of the heat exchanger, for obtaining the combustion-supporting gas 11; the outlet port is arranged at the end of the heat exchanger, for discharging the preheated combustion-supporting gas 12.

[0055] Specifically, the combustion-supporting gas 11 enters the interior of the heat exchanger through the inlet port, and completes heat exchange with the exhaust gas in the interior of the heat exchanger, thereby forming the preheated combustion-supporting gas 12 and discharging the preheated combustion-supporting gas 12 through the outlet port.

[0056] In some embodiments, the heat exchange unit 4 is made of heat-resistant steel material, for resisting the HCl gas in the exhaust gas.

[0057] In some embodiments, the surface of the heat exchange unit 4 is further covered with a corrosion-resistant coating.

[0058] In some embodiments, the corrosion-resistant coating is a ceramic coating.

[0059] In some embodiments, the corrosion-resistant coating is a metal coating, for example, the corrosion-resistant coating comprises a nickel-based alloy.

[0060] In some embodiments, the corrosion-resistant coating is a metal oxide coating, for example, the corrosion-resistant coating can comprise FeO, Fe2O3, Fe3O4.

[0061] In some embodiments, the heat exchange unit 4 is a heat exchanger.

[0062] In some embodiments, the heat exchange unit 4 is any one or a combination of several of the following: a single-tube heat exchanger (as shown in FIG. 2), a double-tube heat exchanger (as shown in FIG. 1), a tube bundle heat exchanger (as shown in FIG. 3).

[0063] In some embodiments, the heat exchange unit 4 has the following two working modes:

[0064] 1) the combustion-supporting gas 11 is inside the tube of the heat exchange unit 4, and the exhaust gas is outside the tube of the heat exchange unit 4;

[0065] 2) the combustion-supporting gas 11 is outside the tube of the heat exchange unit 4, and the exhaust gas is inside the tube of the heat exchange unit 4.

[0066] In some embodiments, the heat exchange unit 4 is a tube bundle heat exchanger with at least two tubes arranged at the hot end.

[0067] Further, the acid regeneration system further comprises a cooling unit 5. The cooling unit 5 is arranged downstream of the heat exchange unit 4, and is configured to cool the exhaust gas after the heat exchange unit 4.

[0068] In some embodiments, the exhaust gas after the cooling unit 5 can be in a gaseous state, a gas-liquid mixed state, or the like.

[0069] In some embodiments, the cooling unit 5 is a Venturi device.

[0070] Further, the acid regeneration system further comprises a gas-liquid separation unit 6. The gas-liquid separation unit 6 is arranged downstream of the cooling unit 5, and is in communication with the reaction unit 1, and is configured to separate the exhaust gas after the cooling unit 5 into a first acid liquid 21 and a second acid liquid 22, and to deliver the first acid liquid 21 to the reaction unit 1 and the second acid liquid 22 to the cooling unit 5.

[0071] The purpose of delivering the first acid liquid 21 to the reaction unit 1 is to reduce the combustion temperature of the reaction unit 1.

[0072] The purpose of delivering the second acid liquid 22 to the cooling unit 5 is to reduce the supplement of external water.

[0073] Further, the acid regeneration system further comprises a supply unit 7. The supply unit 7 is arranged downstream of the gas-liquid separation unit 6, and is configured to supply a third acid liquid 23 to the gas-liquid separation unit 6.

[0074] In some embodiments, the supply unit 7 includes, but is not limited to, a liquid storage pool, a liquid storage tank.

[0075] Further, the acid regeneration system further comprises a plurality of one-way valves. The one-way valves are arranged in the gas inlet pipeline in communication with the heat exchange unit 4, the pipeline in communication between the gas-liquid separation unit 6 and the reaction unit 1, the pipeline in communication between the gas-liquid separation unit 6 and the cooling unit 5, and the pipeline in communication between the gas-liquid separation unit 6 and the supply unit 7.

[0076] The use method of the utility model is as follows:

[0077] The combustion-supporting gas 11 is delivered to the heat exchange unit 4;

[0078] After the heat exchange treatment of the heat exchange unit 4, the preheated combustion-supporting gas 12 is formed;

[0079] The preheated combustion-supporting gas 12 and the fuel 13 (which can be gaseous or liquid) are mixed and combusted in the reaction unit 1 to produce exhaust gas;

[0080] The exhaust gas is delivered to the separation unit 3 through the exhaust gas unit 2 for gas-solid separation treatment;

[0081] The waste gas after the gas-solid separation treatment enters the heat exchange unit 4 and exchanges heat with the combustion-supporting gas 11;

[0082] The waste gas after the heat exchange treatment enters the cooling unit 5 and is cooled;

[0083] The waste gas after the cooling treatment is washed in the gas-liquid separation unit 6 to produce the acid liquid;

[0084] The gas-liquid separation unit 6 delivers the first acid liquid 21 to the reaction unit 1 and the second acid liquid 22 to the cooling unit 5;

[0085] The above process is repeatedly performed until the reaction is completed.

[0086] The technical effects of the utility model are as follows:

[0087] 1) The heat exchange unit is used to recycle the heat of the waste gas generated by combustion, which can effectively preheat the combustion-supporting gas, thereby obtaining the best heat recovery and the lowest energy consumption;

[0088] 2) The separation unit is used to separate the waste gas into gas and solid to remove the solid particles in the waste gas, thereby avoiding the scaling of the heat exchange unit and the problem of reduced efficiency of the heat exchanger;

[0089] 3) The acid regeneration unit can be applied to different scales and different concentrations of waste acid regeneration.

[0090] Embodiment 2

[0091] This embodiment is a variant of embodiment 1.

[0092] In this embodiment, as shown in FIG. 4, the acid regeneration system further includes an adjusting unit 8. The adjusting unit 8 is arranged between the gas inlet and the gas outlet of the heat exchange unit 4 and is used to adjust the temperature of the preheated combustion-supporting gas 12.

[0093] Specifically, the adjusting unit 8 communicates the gas inlet pipe connected with the heat exchange unit 4 and the gas outlet pipe connected with the heat exchange unit 4, thereby adjusting the proportion of the unpreheated combustion-supporting gas 11 and the preheated combustion-supporting gas 12 and further adjusting the temperature of the combustion-supporting gas 12 delivered to the reaction unit 1.

[0094] In some embodiments, the adjusting unit 8 includes but is not limited to a control valve.

[0095] Further, the acid regeneration system further includes a temperature sensor. The temperature sensor is arranged in the gas outlet pipe and is used to monitor the temperature of the combustion-supporting gas 12 delivered to the reaction unit 1.

[0096] The use method of this embodiment is as follows:

[0097] (1) reducing the temperature of the combustion-supporting gas 12

[0098] If the temperature of the combustion-supporting gas 12 delivered to the reaction unit 1 is higher than the preset temperature threshold, the regulating unit 8 is controlled to increase the flow rate of the un-preheated combustion-supporting gas 11, so as to increase the ratio of the un-preheated combustion-supporting gas 11 to the preheated combustion-supporting gas 12, and in turn reduce the temperature of the combustion-supporting gas 12 delivered to the reaction unit 1.

[0099] (2) increasing the temperature of the combustion-supporting gas 12

[0100] If the temperature of the combustion-supporting gas 12 delivered to the reaction unit 1 is lower than the preset temperature threshold, the regulating unit 8 is controlled to decrease the flow rate of the un-preheated combustion-supporting gas 11, so as to decrease the ratio of the un-preheated combustion-supporting gas 11 to the preheated combustion-supporting gas 12, and in turn increase the temperature of the combustion-supporting gas 12 delivered to the reaction unit 1.

[0101] The technical effects of the embodiment are as follows:

[0102] The temperature of the combustion-supporting gas is regulated by the regulating unit, so as to ensure long-time stable operation of the acid regeneration system.

[0103] The above merely describes the preferred embodiments of the present application, and is not intended to limit the implementation manners and the protection scope of the present application. It should be noted by those skilled in the art that any equivalent replacements and obvious changes made according to the contents of the present application should be included in the protection scope of the present application.

Claims

1. An acid regeneration system characterized by, The application relates to a waste gas treatment system, comprising: a reaction unit for combusting fuel and preheated combustion gas to generate waste gas; a separation unit arranged downstream of the reaction unit for separating the waste gas to remove solid particles in the waste gas; a heat exchange unit arranged downstream of the separation unit for preheating the combustion gas by using the waste gas treated by the separation unit to obtain the preheated combustion gas.

2. The acid regeneration system of claim 1, wherein, The reaction unit comprises: a plurality of nozzle elements arranged at the bottom of the reaction unit for obtaining the fuel, the preheated combustion gas and mixing the fuel and the preheated combustion gas.

3. The acid regeneration system according to any one of claims 1 to 2, characterized in that, Further comprising: a waste gas unit arranged between the reaction unit and the separation unit for conveying the waste gas generated by the reaction unit to the separation unit.

4. The acid regeneration system according to any one of claims 1 to 3, characterized in that Further comprising: a cooling unit arranged downstream of the heat exchange unit for cooling the waste gas treated by the heat exchange unit.

5. The acid regeneration system according to any one of claims 1 to 4, characterized in that Further comprising: an adjusting unit arranged between the gas inlet and the gas outlet of the heat exchange unit for adjusting the temperature of the preheated combustion gas.

6. The acid regeneration system according to any one of claims 1 to 5, characterized in that The heat exchange unit is any one or a combination of single-pipe heat exchanger, double-pipe heat exchanger and pipe bundle heat exchanger.

7. The acid regeneration system of claim 6, wherein, The heat exchange unit is a pipe bundle heat exchanger with at least two pipes arranged at the hot end.

8. The acid regeneration system according to any one of claims 1 to 7, characterized in that The heat exchange unit is made of heat-resistant steel material for resisting HCl gas in the waste gas.

9. The acid regeneration system according to any one of claims 1 to 8, characterized in that The surface of the heat exchange unit is further covered with a corrosion-resistant coating.

10. The acid regeneration system of claim 9, wherein, The corrosion-resistant coating is any one or a combination of metal coating, metal oxide coating and ceramic coating. Preferably, the metal coating comprises nickel-based alloy. Preferably, the metal oxide coating comprises FeO, Fe2O3 and Fe3O4.

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