Nitrogen replacement system of ammonia mother liquor pipeline for combined soda production

Abstract

The utility model discloses an ammonia mother liquor pipeline nitrogen replacement system for combined soda production, and provides a systematic solution aiming at potential safety hazards, low efficiency and environmental protection problems existing in traditional maintenance. The system is formed by integrating an ammonia mother liquor conveying unit, a low-pressure nitrogen replacement unit, a tail gas recovery unit and a waste liquid treatment unit, and the leakage risk is eliminated by replacing pipeline dismantling through segmented nitrogen replacement. The multi-branch replacement design supports local rapid isolation, and cooperates with a tail gas recovery device to neutralize waste gas and waste liquid for unified collection and treatment, so that the safety and environmental protection double standards are achieved. The system adopts a modular structure, is provided with a bypass branch pipe and a plurality of groups of control valves, optimizes the maintenance process, shortens the downtime, inhibits oxygen corrosion by maintaining pipeline micro-positive pressure, and prolongs the service life of equipment. According to the scheme, the operation safety, the overhaul efficiency and the environmental protection performance are remarkably improved, a standardized technical path is provided for combined-soda production pipeline maintenance, and the industrial application value is remarkable.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of associated alkali production, and specifically relates to a nitrogen replacement system for ammonia mother liquor pipeline in associated alkali production. BACKGROUND

[0002] In the associated alkali production process, the ammonia mother liquor pipeline as a core conveying unit is in long-term contact with ammonia gas and chlorine-containing medium with strong corrosion, which can easily cause corrosion and perforation of pipelines made of carbon steel, stainless steel and the like, resulting in ammonia mother liquor leakage accidents. Such leakage not only threatens the stability of the production system, but also causes serious harm to the safety of operating personnel and the surrounding environment. In addition, the bolts at the flange connection of the pipeline are difficult to disassemble due to long-term corrosion, further increasing the difficulty and risk of maintenance.

[0003] At present, the nitrogen replacement technology for ammonia-related systems is mainly limited to replacement operation inside the container, and there is a lack of effective replacement means for ammonia mother liquor and ammonia pipelines connected to each other. The traditional maintenance process needs to realize spatial isolation by adding blind plates, emptying the pipeline medium, or even removing the pipeline, which leads to prolonged maintenance period, increased workload, and the following outstanding problems:

[0004] 1. Safety hazards are prominent: residual ammonia gas leakage or liquid splashing is easily caused during pipeline removal, directly threatening the safety of operating personnel; when rusted bolts are treated under pressure, the flange gasket may be broken due to uneven stress, increasing the risk of leakage.

[0005] 2. Low efficiency: manual liquid discharge and isolation operation is time-consuming and labor-intensive, seriously affecting the maintenance progress and restricting the production recovery.

[0006] 3. Great environmental pressure: the traditional method lacks effective recycling measures for ammonia-containing waste gas and waste liquid generated by replacement, and direct discharge can easily cause environmental pollution, which is difficult to meet the requirements of environmental regulations.

[0007] To solve the above problems, a safe replacement system covering the whole process of the ammonia mother liquor pipeline is urgently needed to realize rapid isolation, efficient replacement and environmental protection treatment, thereby reducing the operation risk, improving the maintenance efficiency and ensuring the production continuity. INVENTION CONTENTS

[0008] The purpose of the present application is to overcome the shortcomings of the prior art and provide a nitrogen replacement system for ammonia mother liquor pipeline in associated alkali production.

[0009] To achieve the above purpose, the following technical solutions are adopted: a nitrogen replacement system for ammonia mother liquor pipeline in associated alkali production, comprising:

[0010] The ammonia mother liquor conveying unit comprises, in sequence, an ammonia mother liquor inlet pipe, an ammonia mother liquor pump, an ammonia mother liquor heater pipe, an ammonia mother liquor heater, a cleaning tower pipe, a cleaning tower, a cleaning pump mother liquor pipe, a cleaning pump, an alkali production tower mother liquor pipe, an alkali production tower, and an alkali outlet pipe.

[0011] The low-pressure nitrogen replacement unit comprises a low-pressure nitrogen replacement main pipe connected to a low-pressure nitrogen pipe network and used for injecting low-pressure nitrogen, wherein the low-pressure nitrogen replacement main pipe is branched into a low-pressure nitrogen replacement branch pipe I, a low-pressure nitrogen replacement branch pipe II, and a low-pressure nitrogen replacement branch pipe III after a flow meter, wherein the low-pressure nitrogen replacement branch pipe I is connected to the ammonia mother liquor heater pipe, the low-pressure nitrogen replacement branch pipe II is connected to the alkali production tower mother liquor pipe, and the low-pressure nitrogen replacement branch pipe III is connected to the cleaning pump mother liquor pipe.

[0012] The tail gas recovery unit comprises a tail gas recovery branch pipe I, a tail gas recovery branch pipe II, and a tail gas recovery branch pipe III connected to the cleaning tower pipe, the cleaning pump mother liquor pipe, and the alkali production tower mother liquor pipe, respectively, and each branch pipe is connected to a waste liquid recovery device through a tail gas recovery main pipe.

[0013] The waste liquid treatment unit comprises a waste liquid discharge pipe arranged on the low-pressure nitrogen replacement branch pipe I, the low-pressure nitrogen replacement branch pipe II, and the low-pressure nitrogen replacement branch pipe III, wherein each waste liquid discharge pipe is provided with a discharge valve I, a discharge valve II, and a discharge valve III, respectively, and is connected to a miscellaneous water bucket.

[0014] Further, a bypass branch pipe in parallel with the ammonia mother liquor heater is arranged between the ammonia mother liquor heater pipe and the cleaning tower pipe, and the bypass branch pipe is provided with a bypass valve.

[0015] Further, the ammonia mother liquor conveying unit comprises:

[0016] an inlet valve on the ammonia mother liquor inlet pipe;

[0017] an outlet valve and a heater front valve arranged in sequence on the ammonia mother liquor heater pipe;

[0018] a heater rear valve and a cleaning tower inlet valve arranged in sequence on the cleaning tower pipe;

[0019] a cleaning tower outlet valve, a cleaning ammonia mother liquor two-way pipe main valve, and a cleaning pump front valve arranged in sequence on the cleaning pump mother liquor pipe;

[0020] a cleaning pump rear valve I, a cleaning pump rear valve II, and an alkali production tower front valve arranged in sequence on the alkali production tower mother liquor pipe;

[0021] an alkali outlet valve arranged on the alkali outlet pipe.

[0022] Further, the low-pressure nitrogen replacement unit comprises:

[0023] Low pressure nitrogen gas replacement branch pipe I is sequentially provided with ammonia mother liquor two replacement valves, ammonia mother liquor two replacement valve I and ammonia mother liquor two replacement valve II;

[0024] Low pressure nitrogen gas replacement branch pipe II is sequentially provided with cleaning ammonia mother liquor two pump outlet branch pipe replacement nitrogen gas total valve, first cleaning ammonia mother liquor two replacement valve and second cleaning ammonia mother liquor two replacement valve;

[0025] Low pressure nitrogen gas replacement branch pipe III is sequentially provided with cleaning ammonia mother liquor two communication pipe replacement nitrogen gas total valve, third cleaning ammonia mother liquor two replacement valve and fourth cleaning ammonia mother liquor two replacement valve.

[0026] Further, the tail gas recovery unit comprises:

[0027] The first replacement tail gas discharge valve, the second replacement tail gas discharge valve, the sampling pipe I and the sampling pipe I valve on the tail gas recovery branch pipe I;

[0028] The third replacement tail gas discharge valve, the fourth replacement tail gas discharge valve, the sampling pipe II and the sampling pipe II valve on the tail gas recovery branch pipe II;

[0029] The fifth replacement tail gas discharge valve, the sixth replacement tail gas discharge valve, the sampling pipe III and the sampling pipe III valve on the tail gas recovery branch pipe III.

[0030] Further, the ammonia mother liquor heater pipeline is provided with an ammonia-containing waste gas discharge pipe, which is sequentially provided with a first replacement tail gas discharge valve and a second replacement tail gas discharge valve, wherein a sampling pipe IV is further arranged between the first replacement tail gas discharge valve and the second replacement tail gas discharge valve, and a third replacement tail gas discharge valve is arranged on the sampling pipe IV.

[0031] The utility model discloses a nitrogen replacement system for ammonia mother liquor pipeline by integrating low pressure nitrogen replacement, tail gas recovery and waste liquid treatment unit, which specifically solves the following problems:

[0032] 1. Safety risk control: by sectional nitrogen replacement instead of pipeline dismantling, eliminate the leakage source, avoid the operation under pressure, significantly reduce the risk of personal injury.

[0033] 2. Improve maintenance efficiency: adopt multi-branch replacement design, support local pipe section quick isolation and replacement, reduce downtime and speed up maintenance process.

[0034] 3. Environmental protection standard: waste gas is neutralized and treated by the recovery device, waste liquid is uniformly collected into the miscellaneous water bucket, ammonia gas is zero scattered and waste liquid is controllable, which meets the safety and environmental protection requirements.

[0035] 4. Corrosion maintenance optimization: maintain the pipeline micro-positive pressure after nitrogen replacement, inhibit oxygen corrosion, prolong the service life of the pipeline and enhance the anti-accident ability of the system.

[0036] Through the technical improvement, the utility model provides the standardized, modular solution for the ammonia mother liquor pipeline maintenance in the combined alkali production, effectively balances the safety, efficiency and environmental protection demand, has remarkable industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is the principle diagram of nitrogen replacement system of ammonia mother liquor pipeline for combined alkali production of the application.

[0038] Figure 2 It is the principle diagram of replacement of ammonia mother liquor heater pipeline and cleaning tower pipeline of the application.

[0039] Figure 3 It is the principle diagram of replacement of cleaning pump to alkali tower mother liquor pipeline of the application.

[0040] Figure 4 It is the principle diagram of replacement of cleaning pump mother liquor pipeline of the application.

[0041] As shown in the figure: 1, ammonia mother liquor inlet pipe; 2, ammonia mother liquor pump; 3, ammonia mother liquor heater pipe; 4, ammonia-containing waste gas discharge pipe; 5, ammonia mother liquor heater; 6, cleaning tower pipe; 7, cleaning tower; 8, cleaning pump mother liquor pipe; 9, cleaning pump; 10, caustic soda tower mother liquor pipe; 11, caustic soda tower; 12, liquid alkali outlet pipe; 13, low-pressure nitrogen; 14, flow meter; 15, low-pressure nitrogen replacement main pipe; 16, low-pressure nitrogen replacement branch pipe I; 17, low-pressure nitrogen replacement branch pipe II; 18, low-pressure nitrogen replacement branch pipe III; 19, waste liquid discharge pipe; 20, tail gas recovery branch pipe I; 21, tail gas recovery branch pipe II; 22, tail gas recovery branch pipe III; F01, liquid inlet valve; F02, liquid outlet valve; F03, first replacement tail gas discharge valve; F04, second replacement tail gas discharge valve; F05, third replacement tail gas discharge valve; F06, ammonia mother liquor second replacement valve II; F07, ammonia mother liquor second replacement valve I; F08, liquid discharge valve I; F09, bypass valve; F10, heater front valve; F11, heater rear valve; F12, cleaning tower inlet valve; F13, cleaning tower outlet valve; F14, third replacement tail gas discharge valve; F15, fourth replacement tail gas discharge valve; F16, sampling pipe II valve; F17, ammonia mother liquor second replacement valve; F18, cleaning ammonia mother liquor second pump outlet branch pipe replacement nitrogen main valve; F19, cleaning ammonia mother liquor second communication pipe replacement nitrogen main valve; F20, third cleaning ammonia mother liquor second replacement valve; F21, fourth cleaning ammonia mother liquor second replacement valve; F22, liquid discharge valve III; F23, cleaning ammonia mother liquor second communication pipe main valve; F24, cleaning pump front valve; F25, cleaning pump rear valve I; F26, cleaning pump rear valve II; F27, second cleaning ammonia mother liquor second replacement valve; F28, first cleaning ammonia mother liquor second replacement valve; F29, liquid discharge valve II; F30, caustic soda tower front valve; F31, liquid alkali outlet valve; F32, fifth replacement tail gas discharge valve; F33, sixth replacement tail gas discharge valve; F34, sampling pipe III valve; F35, first replacement tail gas discharge valve; F36, second replacement tail gas discharge valve; F37, sampling pipe I valve. DETAILED DESCRIPTION

[0042] 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 labor fall within the scope of the present application.

[0043] It should be noted that all the directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship and movement condition between the components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directional indications will also change accordingly.

[0044] In addition, the description such as "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can be explicitly or implicitly included at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0045] Furthermore, the technical solutions of each embodiment of the present application can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, also not within the protection scope required by the present application.

[0046] Referring to the drawings Figure 1 The application provides a nitrogen replacement system for ammonia mother liquor pipeline in combined alkali production, which comprises:

[0047] The ammonia mother liquor conveying unit comprises, in sequence, an ammonia mother liquor inlet pipe 1, an ammonia mother liquor pump 2, an ammonia mother liquor heater pipeline 3, an ammonia mother liquor heater 5, a cleaning tower pipeline 6, a cleaning tower 7, a cleaning pump mother liquor pipeline 8, a cleaning pump 9, an alkali tower mother liquor pipeline 10, an alkali tower 11 and an alkali outlet pipe 12.

[0048] The low-pressure nitrogen replacement unit comprises a low-pressure nitrogen replacement main pipe 15 connected with a low-pressure nitrogen pipe network and used for injecting low-pressure nitrogen 13, and the low-pressure nitrogen replacement main pipe 15 is branched after a flow meter 14 to have a low-pressure nitrogen replacement branch pipe I 16, a low-pressure nitrogen replacement branch pipe II 17 and a low-pressure nitrogen replacement branch pipe III 18, wherein the low-pressure nitrogen replacement branch pipe I 16 is connected to the ammonia mother liquor heater pipeline 3, the low-pressure nitrogen replacement branch pipe II 17 is connected to the alkali tower mother liquor pipeline 10, and the low-pressure nitrogen replacement branch pipe III 18 is connected to the cleaning pump mother liquor pipeline 8.

[0049] The tail gas recovery unit comprises tail gas recovery branch pipes I 20, II 21 and III 22 connected to the cleaning tower pipeline 6, the cleaning pump mother liquor pipeline 8 and the alkali tower mother liquor pipeline 10 respectively, and each branch pipe is connected to a waste gas recovery device through a tail gas recovery main pipe.

[0050] The waste liquid treatment unit comprises waste liquid discharge pipes 19 arranged on the low-pressure nitrogen replacement branch pipe I 16, the low-pressure nitrogen replacement branch pipe II 17 and the low-pressure nitrogen replacement branch pipe III 18, and each waste liquid discharge pipe 19 is respectively provided with a liquid discharge valve I F08, a liquid discharge valve II F29 and a liquid discharge valve III F22 and connected to a miscellaneous water bucket.

[0051] In one embodiment, a bypass branch pipe in parallel with the ammonia mother liquor heater 5 is arranged between the ammonia mother liquor heater pipe 3 and the washing tower pipe 6, and the bypass branch pipe is provided with a bypass valve F09.

[0052] In one embodiment, the ammonia mother liquor delivery unit comprises: a liquid inlet valve F01 arranged on the ammonia mother liquor inlet pipe 1; a liquid outlet valve F02 and a heater front valve F10 arranged in sequence on the ammonia mother liquor heater pipe 3; a heater rear valve F11 and a washing tower inlet valve F12 arranged in sequence on the washing tower pipe 6; a washing tower outlet valve F13, a washing ammonia mother liquor two-way pipe total valve F23 and a washing pump front valve F24 arranged in sequence on the washing pump mother liquor pipe 8; a washing pump rear valve I F25, a washing pump rear valve II valve F26 and an alkali tower front valve F30 arranged in sequence on the alkali tower mother liquor pipe 10; and an alkali liquid outlet valve F31 arranged on the alkali liquid outlet pipe 12.

[0053] In one embodiment, the low-pressure nitrogen replacement unit comprises: an ammonia mother liquor two replacement valve F17, an ammonia mother liquor two replacement valve I F07 and an ammonia mother liquor two replacement valve II F06 arranged in sequence on the low-pressure nitrogen replacement branch pipe I 16; a washing ammonia mother liquor two pump outlet branch pipe replacement nitrogen total valve F18, a first washing ammonia mother liquor two replacement valve F28 and a second washing ammonia mother liquor two replacement valve F27 arranged in sequence on the low-pressure nitrogen replacement branch pipe II 17; and a washing ammonia mother liquor two-way pipe replacement nitrogen total valve F19, a third washing ammonia mother liquor two replacement valve F20 and a fourth washing ammonia mother liquor two replacement valve F21 arranged in sequence on the low-pressure nitrogen replacement branch pipe III 18.

[0054] In one embodiment, the tail gas recovery unit comprises: a first replacement tail gas discharge valve F35, a second replacement tail gas discharge valve F36, a sampling pipe I and a sampling pipe I valve F37 arranged on the tail gas recovery branch pipe I 20; a third replacement tail gas discharge valve F14, a fourth replacement tail gas discharge valve F15, a sampling pipe II and a sampling pipe II valve F16 arranged on the tail gas recovery branch pipe II 21; and a fifth replacement tail gas discharge valve F32, a sixth replacement tail gas discharge valve F33, a sampling pipe III and a sampling pipe III valve F34 arranged on the tail gas recovery branch pipe III 22.

[0055] In one embodiment, the ammonia mother liquor heater pipe 3 is provided with an ammonia-containing waste gas discharge pipe 4, which is sequentially provided with a first displacement tail gas discharge valve F03 and a second displacement tail gas discharge valve F04, wherein a sampling pipe IV is further provided between the first displacement tail gas discharge valve F03 and the second displacement tail gas discharge valve F04, and the sampling pipe IV is provided with a third displacement tail gas discharge valve F05.

[0056] In the specific use process, the ammonia mother liquor crystallized by the ammonia mother liquor pump 2 is sent into the ammonia mother liquor heater pipe 3 through the ammonia mother liquor inlet pipe 1, heated by the ammonia mother liquor heater 5, and then sent to the cleaning tower pipe 6 through the ammonia mother liquor heater pipe 3, and finally sent to the cleaning tower 7. The cleaning liquid from the cleaning tower 7 is self-pressurized into the cleaning pump 9 through the cleaning pump mother liquor pipe 8, and then the cleaning liquid is sent to the caustic tower 11 through the caustic tower mother liquor pipe 10 by the cleaning pump 9. The caustic liquid from the caustic tower 11 is self-pressurized into the liquid caustic pipe 12.

[0057] Low-pressure nitrogen displacement: low-pressure nitrogen 13 from the low-pressure nitrogen pipe network is divided into three branch pipes: low-pressure nitrogen displacement branch pipe I 16, low-pressure nitrogen displacement branch pipe II 17 and low-pressure nitrogen displacement branch pipe III 18 through the flow meter 14 and the low-pressure nitrogen displacement main pipe 15, which are used for nitrogen displacement of the ammonia mother liquor pipe and related parts. The ammonia-containing waste gas displaced is sent to the waste gas recovery device through the tail gas recovery unit.

[0058] In combination with the accompanying drawings Figure 2 The specific implementation method for displacing the ammonia mother liquor heater pipe 3 and the cleaning tower pipe 6 is as follows:

[0059] Low-pressure nitrogen 13 from the pipeline network has its flow rate monitored by flow meter 14. Replacement gas is supplied by opening the ammonia mother liquor second replacement valve F17, which connects the low-pressure nitrogen replacement main pipe 15 to the low-pressure nitrogen replacement branch pipe I16. When this section of the ammonia mother liquor pipeline needs maintenance, the outlet valve F02 and the cleaning tower inlet valve F12 are closed, cutting off the connection between this pipeline and the ammonia mother liquor pump 2 and the cleaning tower 7. The ammonia mother liquor second replacement valve IIF06 and the drain valve IF08 are opened to recover the waste liquid in the ammonia mother liquor pipeline to the miscellaneous water tank. After the waste liquid is drained, the drain valve IF08 is closed, and the ammonia mother liquor second replacement valve IIF06, the first replacement tail gas discharge valve F03, the second replacement tail gas discharge valve F04, and the first replacement tail gas discharge valve F35 and the second replacement tail gas discharge valve F36 on the tail gas recovery branch pipe I20 are opened to continuously replace the ammonia mother liquor heater pipeline 3 and the cleaning tower pipeline 6. Simultaneously, sampling points (sampling pipe I and sampling pipe I valve F37) are installed on the exhaust pipe to detect ammonia concentration. The replacement gas flow rate is maintained at 500-1000 Nm³ / h, and the third replacement exhaust valve F05 and sampling pipe I valve F37 are opened every 30 minutes for gas detection. When the gas detection data is qualified (ammonia concentration not greater than 0.5%), the opening of the ammonia mother liquor second replacement valve F17 is appropriately reduced to decrease the flow rate of the replacement gas in the pipeline and maintain a slight positive pressure in the pipeline, thereby achieving inherent safety during maintenance. After maintenance, the ammonia mother liquor second replacement valve F17, the first replacement exhaust valve F35, the second replacement exhaust valve F36, the first replacement exhaust valve F03, the second replacement exhaust valve F04, and the ammonia mother liquor second replacement valve IIF06 are closed, and the third replacement exhaust valve F05 and the drain valve IF08 are confirmed to be closed. Open the liquid outlet valve F02 and the cleaning tower inlet valve F12 to restore the ammonia mother liquor heater pipeline 3 and the cleaning tower pipeline 6 to normal operation.

[0060] Combined with appendix Figure 3 The method for replacing the mother liquor pipeline 10 from the cleaning pump 9 to the alkali production tower is as follows:

[0061] The nitrogen gas is provided by opening the cleaning ammonia mother liquor two pump outlet branch displacement nitrogen gas total valve F18 connected with the low pressure nitrogen gas displacement branch II 17. When the ammonia mother liquor pipeline needs to be repaired, the cleaning pump post valve II valve F26 and the caustic tower front valve F30 are closed to cut off the communication between the pipeline and the cleaning pump 9 and the caustic tower 11. The second cleaning ammonia mother liquor two displacement valve F27 and the liquid discharge valve II F29 are opened to recover the waste liquid in the ammonia mother liquor pipeline to the miscellaneous water bucket. After the waste liquid is discharged, the liquid discharge valve II F29 is closed, the first cleaning ammonia mother liquor two displacement valve F28, the fifth displacement tail gas discharge valve F32 and the sixth displacement tail gas discharge valve F33 are opened to continuously displace the cleaning pump 9 to the caustic tower mother liquor pipeline 10. At the same time, a sampling point (sampling pipe II and sampling pipe II valve F16) is arranged on the tail gas discharge pipe to detect the ammonia gas concentration. The displacement gas flow is kept at 500-1000 Nm³ / h, and the sampling pipe II valve F16 is opened every 30 minutes to detect the gas. When the gas detection data is qualified (the ammonia concentration is not greater than 0.5%), the opening degree of the cleaning ammonia mother liquor two pump outlet branch displacement nitrogen gas total valve F18 is appropriately reduced to reduce the flow rate of the displacement gas in the pipeline and keep the pipeline in a slight positive pressure. After the repair is completed, the cleaning ammonia mother liquor two pump outlet branch displacement nitrogen gas total valve F18, the first cleaning ammonia mother liquor two displacement valve F28, the second cleaning ammonia mother liquor two displacement valve F27, the first cleaning ammonia mother liquor two displacement valve F32 and the sixth displacement tail gas discharge valve F33 are closed, and it is confirmed that the liquid discharge valve II F29 and the sampling pipe III valve F34 are in a closed state. The cleaning pump post valve II valve F26 and the caustic tower front valve F30 are opened to restore the normal use of the ammonia mother liquor pipeline 10.

[0062] The accompanying drawings are incorporated in and constitute a part of this specification. Figure 4 The cleaning pump mother liquor pipeline 8 displacement implementation method is as follows:

[0063] When the ammonia mother liquor pipeline needs to be repaired, the cleaning ammonia mother liquor two-way pipe total valve F23 and the cleaning tower outlet valve F13 are closed, and the communication between the pipeline and the cleaning pump 9 and the cleaning tower 7 is cut off. The fourth cleaning ammonia mother liquor two-way displacement valve F21 and the liquid discharge valve III F22 are opened, and the waste liquid in the ammonia mother liquor pipeline is recovered to the miscellaneous water bucket. After the waste liquid is discharged, the liquid discharge valve III F22 is closed, the third cleaning ammonia mother liquor two-way displacement valve F20, the third displacement tail gas discharge valve F14 and the fourth displacement tail gas discharge valve F15 are opened, and the cleaning pump mother liquor pipeline 8 is continuously displaced. At the same time, a sampling point (sampling pipe III and sampling pipe III valve F34) is arranged on the tail gas discharge pipe for detecting the ammonia gas concentration. The displacement gas flow is kept at 500-1000Nm³ / h, and the sampling pipe III valve F34 is opened every 30 minutes for gas detection. When the gas detection data is qualified (the ammonia concentration is not greater than 0.5%), the opening degree of the cleaning ammonia mother liquor two-way pipe displacement nitrogen total valve F19 is appropriately reduced, the flow rate of the displacement gas in the pipeline is reduced, and the pipeline is kept in a slight positive pressure. After the repair is completed, the cleaning ammonia mother liquor two-way pipe displacement nitrogen total valve F19 is closed; the third cleaning ammonia mother liquor two-way displacement valve F20, the fourth cleaning ammonia mother liquor two-way displacement valve F21, the third displacement tail gas discharge valve 14 and the fourth displacement tail gas discharge valve F15 are closed, and it is confirmed that the liquid discharge valve III F22 and the sampling pipe II valve F16 are in a closed state. The valve cleaning tower outlet valve F13 and the cleaning ammonia mother liquor two-way pipe total valve F23 are opened, and the normal use of the cleaning pump mother liquor pipeline 8 is restored.

[0064] The above describes the present application and its embodiments, which are not limited, and the drawings only show one of the embodiments of the present application, and the actual structure is not limited thereto. In general, if a person skilled in the art is inspired thereby, without departing from the creative purpose of the present application, similar structural modes and embodiments can be designed without creativity, which should belong to the protection scope of the present application.

Claims

1. A nitrogen purging system for an ammonia mother liquor pipeline used in soda ash production, characterized in that, include: The ammonia mother liquor conveying unit includes an ammonia mother liquor inlet pipe (1), an ammonia mother liquor pump (2), an ammonia mother liquor heater pipe (3), an ammonia mother liquor heater (5), a cleaning tower pipe (6), a cleaning tower (7), a cleaning pump mother liquor pipe (8), a cleaning pump (9), an alkali production tower mother liquor pipe (10), an alkali production tower (11), and an alkali outlet pipe (12) connected in sequence. The low-pressure nitrogen replacement unit includes a low-pressure nitrogen replacement main pipe (15) connected to the low-pressure nitrogen pipeline network and used for injecting low-pressure nitrogen (13). The low-pressure nitrogen replacement main pipe (15) is connected to a low-pressure nitrogen replacement branch pipe I (16), a low-pressure nitrogen replacement branch pipe II (17) and a low-pressure nitrogen replacement branch pipe III (18) after passing through a flow meter (14). The low-pressure nitrogen replacement branch pipe I (16) is connected to the ammonia mother liquor heater pipeline (3), the low-pressure nitrogen replacement branch pipe II (17) is connected to the alkali tower mother liquor pipeline (10), and the low-pressure nitrogen replacement branch pipe III (18) is connected to the cleaning pump mother liquor pipeline (8). The tail gas recovery unit includes tail gas recovery branch pipe I (20), tail gas recovery branch pipe II (21) and tail gas recovery branch pipe III (22) respectively connected to the cleaning tower pipeline (6), the cleaning pump mother liquor pipeline (8) and the alkali tower mother liquor pipeline (10). Each branch pipe is connected to the waste gas recovery device through the tail gas recovery main pipe. The waste liquid treatment unit includes waste liquid discharge pipes (19) installed on low-pressure nitrogen replacement branch pipe I (16), low-pressure nitrogen replacement branch pipe II (17) and low-pressure nitrogen replacement branch pipe III (18). Each waste liquid discharge pipe (19) is equipped with a drain valve I (F08), a drain valve II (F29) and a drain valve III (F22) and is connected to a miscellaneous water tank.

2. The nitrogen replacement system for an ammonia mother liquor pipeline used in soda ash production according to claim 1, characterized in that, A bypass branch pipe is provided in parallel with the ammonia mother liquor heater (5) between the ammonia mother liquor heater pipe (3) and the cleaning tower pipe (6), and the bypass branch pipe is equipped with a bypass valve (F09).

3. The nitrogen replacement system for an ammonia mother liquor pipeline used in soda ash production according to claim 1, characterized in that, The ammonia mother liquor conveying unit includes: Inlet valve (F01) on ammonia mother liquor inlet pipe (1); The outlet valve (F02) and the heater front valve (F10) are sequentially installed on the ammonia mother liquor heater pipeline (3). The heater back valve (F11) and the cleaning tower inlet valve (F12) are sequentially installed on the cleaning tower pipeline (6). The cleaning tower outlet valve (F13), the cleaning ammonia mother liquor dual-connection pipe main valve (F23), and the cleaning pump inlet valve (F24) are sequentially installed on the cleaning pump mother liquor pipeline (8). The mother liquor pipeline (10) of the alkali production tower is sequentially equipped with a cleaning pump downstream valve I (F25), a cleaning pump downstream valve II (F26), and an alkali production tower upstream valve (F30). The alkali outlet valve (F31) is installed on the alkali outlet pipe (12).

4. The nitrogen replacement system for an ammonia mother liquor pipeline used in soda ash production according to claim 1, characterized in that, The low-pressure nitrogen replacement unit includes: Ammonia mother liquor replacement valve (F17), ammonia mother liquor replacement valve I (F07) and ammonia mother liquor replacement valve II (F06) are sequentially installed on the low-pressure nitrogen replacement branch pipe I (16). The low-pressure nitrogen replacement branch pipe II (17) is sequentially equipped with a nitrogen replacement main valve (F18), a first ammonia mother liquor replacement valve (F28), and a second ammonia mother liquor replacement valve (F27) at the outlet branch pipe of the second ammonia mother liquor pump. The cleaning ammonia mother liquor two-way pipe replacement nitrogen main valve (F19), the third cleaning ammonia mother liquor two-way replacement valve (F20) and the fourth cleaning ammonia mother liquor two-way replacement valve (F21) are sequentially installed on the low-pressure nitrogen replacement branch pipe III (18).

5. The nitrogen replacement system for an ammonia mother liquor pipeline used in soda ash production according to claim 1, characterized in that, The exhaust gas recovery unit includes: The first replacement exhaust valve (F35), the second replacement exhaust valve (F36), the sampling pipe I, and the sampling pipe I valve (F37) on the exhaust gas recovery branch pipe I (20). The third replacement exhaust valve (F14), the fourth replacement exhaust valve (F15), the sampling pipe II, and the sampling pipe II valve (F16) on the exhaust gas recovery branch pipe II (21). The fifth replacement exhaust valve (F32), the sixth replacement exhaust valve (F33), the sampling pipe III, and the sampling pipe III valve (F34) on the exhaust gas recovery branch pipe III (22).

6. The nitrogen replacement system for an ammonia mother liquor pipeline used in soda ash production according to claim 1, characterized in that, The ammonia mother liquor heater pipeline (3) is provided with an ammonia-containing waste gas discharge pipe (4), which is provided with a first replacement tail gas discharge valve (F03) and a second replacement tail gas discharge valve (F04) in sequence. A sampling pipe IV is provided between the first replacement tail gas discharge valve (F03) and the second replacement tail gas discharge valve (F04), and a third replacement tail gas discharge valve (F05) is provided on the sampling pipe IV.

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