Method and system for purifying return liquid of BYD reactor

Abstract

The invention discloses a method and system for purifying BYD reactor return liquid, and belongs to the technical field of chemical production equipment. The invention aims to solve the technical problems that a candle filter in a BYD reactor in the prior art is easy to block from the inner side and the outer side at the same time due to mechanical impurities carried by return liquid, and the service life is short. In order to achieve the purpose, the method provided by the invention comprises the following two key steps: 1, carrying out back flushing on the candle filter by adopting a finely filtered and clean BYD solution as a back flushing solution so as to protect the inner surface of the filter; and 2, before the circulating formaldehyde solution returns to the BYD reactor. The invention further provides a system for implementing the method. By means of the mode that the two key return liquid flow paths are cooperatively purified, the candle filter can be comprehensively protected, the service life of the candle filter is remarkably prolonged, long-period stable operation of a production device is guaranteed, and remarkable economic and technical benefits are achieved.

Description

Technical Field

[0001] This invention relates to the field of chemical production equipment technology, specifically to a method and system for purifying the return liquid from a BYD reactor. Background Technology

[0002] 1,4-Butanediol, an important raw material for organic and fine chemicals, is primarily produced industrially using the modified acetylene-aldehyde process. In this process, the BYD reactor is the core equipment for the acetylene-formaldehyde acetylene reaction under the action of a copper-bismuth catalyst. To effectively retain the solid catalyst within the reactor while allowing the crude BYD product in the liquid phase to be successfully extracted, multiple sets of candle filters are typically installed inside the reactor. The long-term stable operation of these filters is a crucial factor in ensuring the continuous and efficient production of the entire plant.

[0003] In actual production operations, to maintain the filter's throughput and performance, regular backflushing of the candle filter is necessary. In existing technologies, the backflushing fluid is typically taken directly from the collection tank storing the crude BYD solution. However, this crude BYD solution has only undergone preliminary separation by the candle filter and inevitably still carries a large number of mechanical impurities, such as fine catalyst particles, that were not completely intercepted. When this already impure liquid is used to backflush the filter cloth from the inside out, the impurities it carries impact and embed themselves in the inner fiber structure of the filter cloth, causing secondary clogging. This not only severely weakens the cleaning effect that the backflushing operation should achieve but also accelerates the deterioration of the filter's performance from within.

[0004] Meanwhile, the reactor also faces external pollution threats. A circulating formaldehyde solution needs to be returned to the reactor. During this circulation, especially when washing the outlet gas phase at the top of the reactor, this solution captures and entrains a large amount of catalyst powder escaping from the reaction liquid. In the current process design, this circulating formaldehyde solution carrying deactivated catalyst particles is directly returned to the reactor body without any purification treatment. These solid impurities, moving with the liquid flow inside the reactor, gradually adhere to and deposit on the outer surface of the candle filter, accumulating over time to form a dense external blockage layer, severely hindering the normal passage of reaction products.

[0005] Therefore, under current technological conditions, candle filters are actually subjected to simultaneous contamination from both internal and external directions: backflushing liquid contaminates the filter cloth from the inside, while circulating formaldehyde return liquid clogs the filter cloth from the outside. This dual effect causes the filter's differential pressure to rise rapidly, significantly shortening its effective service life and leading to frequent unplanned shutdowns for filter bag replacement and maintenance. This not only results in huge production losses and high spare parts and labor costs, but also seriously affects the long-term, high-load stable operation of the entire production unit, constituting a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The technical problem to be solved by this invention is that the return liquid (especially the backflush liquid and circulating formaldehyde solution) of the existing BYD reactor contains a large number of mechanical impurities. These impurities are returned to the reactor directly without effective filtration, which will continuously clog the candle filter from both the inside and outside, shorten its service life, and thus affect the long-term stable operation of the entire device.

[0007] To address the aforementioned technical problems, this invention provides an innovative purification method and system.

[0008] The first aspect of this invention provides a method for purifying the return liquid from a BYD reactor, wherein the BYD reactor is equipped with a candle filter for separating the catalyst from the crude BYD solution generated during the reaction. This method synergistically protects the candle filter by purifying two key return liquid flow paths. The method includes:

[0009] Step 1: Use a portion of the finely filtered BYD solution as a backflushing liquid to backflush the candle filter.

[0010] This step changes the source of the backflush fluid. Traditional processes use coarse BYD solution that has only undergone preliminary filtration as the backflush fluid. Impurities such as residual catalyst particles in this solution impact and adhere to the inner surface of the candle filter during backflush, causing secondary clogging. This invention uses a finely filtered BYD solution with extremely low mechanical impurity content, thus fundamentally eliminating the risk of backflush fluid contamination and clogging of the filter's inner surface.

[0011] Step 2: Before the circulating formaldehyde solution is returned to the BYD reactor, the circulating formaldehyde solution is filtered to remove mechanical impurities.

[0012] This step addresses another return flow path. The circulating formaldehyde solution, especially the portion carried over from the gas-phase circulation, contains a large amount of fine catalyst powder. This powder may have become deactivated during circulation and, if returned directly to the reactor, would adhere to the outer surface of the wax candle filter, causing external blockage. This invention effectively intercepts these impurities by specifically filtering the circulating formaldehyde before its return, protecting the outer surface of the filter.

[0013] In a preferred embodiment, step one includes: finely filtering the crude BYD solution generated by the BYD reactor to obtain the finely filtered BYD solution. This ensures that the purified backflush fluid has the same cleanliness as the product solution sent to subsequent processes.

[0014] To quantify the purification effect of the backflush fluid in step one, the concentration of mechanical impurities in the finely filtered BYD solution is measured. The concentration of mechanical impurities in the crude BYD solution Preferably, the following relationship is satisfied:

[0015] ;

[0016] This relationship indicates that after purification, the concentration of resinous impurities in the solution is reduced by at least 90%, ensuring that the BYD solution used as a backflushing fluid has extremely high cleanliness.

[0017] Specifically, in order to achieve the above-mentioned purification effect, the fine filtration may include at least one stage of filtration on the coarse BYD solution, wherein the filtration accuracy of this stage is not higher than 5μm, preferably 0.5μm, so as to effectively remove most of the fine particles.

[0018] In a preferred embodiment, step two is achieved by adding an online filter to the pipeline returning the circulating formaldehyde solution to the BYD reactor. This modification is simple, easy to implement, and does not affect the original main process flow.

[0019] As a specific implementation method, the online filter can be a cotton cartridge filter, which has good impurity retention capacity and cost-effectiveness.

[0020] To ensure the purification effect of the circulating formaldehyde solution, the filtration efficiency of the online filter for the circulating formaldehyde solution is [specific details to be added]. The following conditions should be met first:

[0021] ;

[0022] in, The concentration of mechanical impurities in the circulating formaldehyde solution entering the online filter and the concentration of mechanical impurities in the circulating formaldehyde solution exiting the online filter are defined. This condition ensures that the vast majority of mechanical impurities entering the circulating formaldehyde solution are effectively removed.

[0023] In embodiments of the present invention, the mechanical impurities that the method aims to remove mainly include particles of the catalyst or deactivation products generated during the cycle due to acetylene deficiency or other reasons.

[0024] By performing steps one and two, the present invention can simultaneously purify two return liquid flow paths, significantly reducing the clogging rate on both the inside and outside of the candle filter, thereby achieving comprehensive protection of the filter.

[0025] A second aspect of the present invention provides a system for purifying the return liquid from a BYD reactor, the system being configured to implement the above-described method. The system includes a BYD reactor equipped with a candle filter, and further includes:

[0026] The fine filtration unit has its inlet connected to the outlet of the crude BYD solution of the BYD reactor, and is used to perform fine filtration on the crude BYD solution to obtain a finely filtered BYD solution.

[0027] A backflush fluid supply line guides the finely filtered BYD solution from the outlet of the fine filtration unit to the candle filter as a backflush fluid.

[0028] An online filter is installed on the pipeline used to transport the circulating formaldehyde solution back to the BYD reactor for filtering the circulating formaldehyde solution before it is returned to the BYD reactor.

[0029] Compared with the prior art, the technical solution provided by this invention brings significant benefits by synergistically purifying the two return liquid flow paths of backflushing liquid and circulating formaldehyde solution: First, it comprehensively protects the candle filter from both inside and outside, effectively slowing down the clogging process and thus significantly extending the service life of the filter; Second, the stable operation time of the device is extended, reducing the number of shutdowns and production losses caused by filter replacement, lowering operating costs, and improving economic efficiency.

[0030] This invention provides a method and system for purifying the return liquid from a BYD reactor. It has the following beneficial effects:

[0031] 1. This invention achieves dual protection for both the inner and outer sides of the candle filter by using finely filtered BYD solution as the backflushing fluid and adding an online filter to the circulating formaldehyde return fluid. This "comprehensive protection" technical solution fundamentally solves the problem of simultaneous filter contamination caused by impurities carried by the return fluid in existing technologies, and comprehensively and effectively reduces the filter clogging rate.

[0032] 2. By effectively preventing contamination and accumulation of impurities from both the inside and outside, this invention significantly extends the service life of the candle filter bag. Compared to existing technologies where filter bags must be replaced frequently due to rapid clogging, this invention extends the replacement cycle several times, significantly improving the durability and reliability of core equipment components.

[0033] 3. By extending filter life, this invention reduces the number of unplanned shutdowns caused by frequent filter bag replacements. This allows the production unit to achieve longer periods of continuous and stable operation, which is crucial for ensuring the smoothness and consistency of the entire chemical production process and effectively improves the overall operational stability of the unit.

[0034] 4. This invention offers significant economic benefits. Long-term stable operation directly reduces production losses caused by shutdowns for maintenance. Simultaneously, the replacement frequency of filter bags, as consumables, is greatly reduced, directly saving on spare parts procurement costs and related maintenance labor costs, thereby comprehensively lowering the operating and maintenance costs of the equipment.

[0035] 5. This invention improves the overall operating efficiency of the production system by solving the key bottleneck problem of the core equipment, the BYD reactor. A stable and reliable reactor filtration system can ensure the continuous stability of production load, providing a solid technical guarantee for achieving high-load and high-efficiency operation of the equipment, thereby enhancing the overall competitiveness of the equipment. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the overall process flow of an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the backflush fluid supply process in the prior art;

[0038] Figure 3 This is a schematic diagram of the backflush fluid purification process in an embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of the existing formaldehyde solution return process;

[0040] Figure 5 This is a schematic diagram of the circulating formaldehyde solution purification process in an embodiment of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] refer to Figures 1 to 5 This invention discloses a method and system for purifying return liquid from a BYD reactor according to an embodiment of the present invention. The invention aims to solve the problem of easy clogging of candle filters in the prior art by purifying a specific return liquid flow path entering the BYD reactor.

[0043] In a specific process scenario, a 1,4-butanediol production unit employing the modified acetylacetonate process includes a BYD reactor R8101. This reactor R8101 is equipped with multiple candle filters, whose core function is to effectively intercept the solid copper-bismuth catalyst inside the reactor when the reaction product (i.e., the crude BYD solution) is collected.

[0044] In this process context, there are two return liquid flow paths that directly affect the performance of the candle filter. The first is the backflush liquid used for backflushing the candle filter. Before implementing this invention, the process was as follows: the crude BYD solution generated in the BYD reactor R8101 was initially separated by the candle filter and collected in the crude BYD collection tank T8101. Subsequently, pump P8104 transported a portion of the crude BYD solution in T8101 to the backflush liquid tank T8105 for storage and use as backflush liquid. This backflush liquid only underwent preliminary filtration by the candle filter and did not undergo subsequent fine filtration, therefore it still carried a considerable amount of mechanical impurities (mainly fine catalyst particles). When this liquid was used to backflush the candle filter from the inside out, the impurities it carried would impact and deposit on the inner surface of the filter cloth, causing secondary clogging, which contradicted the original purpose of backflushing.

[0045] The second path is the circulating formaldehyde solution flow path. A significant source of this solution is the entrained liquid in the top gas phase space of the BYD reactor R8101. This gas carries a large amount of fine catalyst powder, which is washed off as it passes through the outlet scrubbing tower and integrates into the circulating formaldehyde solution. Subsequently, this circulating formaldehyde solution carrying the catalyst powder is returned directly to the BYD reactor R8101 via pipeline 81125-CD21-2”-P-IH. Because catalyst particles are highly susceptible to deactivation after leaving the acetylene-rich protective environment inside the reactor, these deactivated catalyst particles adhere to the outer surface of the candle filter upon returning to the reactor, accumulating over time to form a difficult-to-remove external blockage layer.

[0046] In this embodiment, to solve the aforementioned technical problems, an effective method for purifying the return liquid from the BYD reactor is provided. The core of this method lies in the targeted purification of two key return liquid flow paths, specifically including steps one and two.

[0047] Step one involves using a portion of the finely filtered BYD solution as a backflushing fluid to backflush the candle filter. To achieve this step, the original process piping was modified in this embodiment. Specifically, refer to the attached... Figure 1 With appendix Figure 2A new pipeline is drawn from the outlet main pipe (pipeline number 81133-CD21-3”-P-IH) of the fine filter F8102A / B and connected to the original pipeline (pipeline number 81137-CD21-2”-P-IH) used to return the filter filtrate to the coarse BYD collection tank T8101 via hand valve 1#.

[0048] Simultaneously, a shut-off valve #3 is installed on the existing replenishment line (pipeline number 81082-CD21-2”-P-IH) from the outlet of pump P8104 to the backflush tank T8105 to isolate direct replenishment from the coarse BYD collection tank T8101. Subsequently, a new replenishment line is connected from the aforementioned pipeline 81137-CD21-2”-P-IH, which has already introduced the finely filtered BYD solution, and connected to pipeline 81082-CD21-2”-P-IH via hand valve #4, thus establishing a new path for transporting the finely filtered BYD solution to the backflush tank T8105. The original flow of F8101A / B and F8102A / B back to T8101 can be shut off by valve #2 to ensure that the purified liquid is preferentially supplied to the backflush tank.

[0049] In this embodiment, the fine filtration consists of two-stage filters, F8101A / B (filtration accuracy of 5 μm) and F81024 / B (filtration accuracy of 0.5 μm). After this fine filtration process, the purity of the resulting finely filtered BYO solution is significantly improved. The concentration of mechanical impurities in the solution satisfies the following relationship:

[0050] ;

[0051] in, ,and Let represent the concentration of mechanical impurities in the crude BYD solution from the crude BYD collection tank T8101. This relationship indicates that the impurity content of the backflushing liquid source is reduced by at least one order of magnitude.

[0052] Step two involves filtering the circulating formaldehyde solution to remove mechanical impurities before it is returned to the BYD reactor R8101. (See attached diagram.) Figure 3 To implement this step, an online filter was added to the return line (line number 81125-CD21-2”-P-IH) downstream of the circulating formaldehyde regulating valve LV3506 to the reactor. Simultaneously, a shut-off valve #5 was installed on the original line, forming a switchable bypass to ensure that the circulating formaldehyde solution must flow through the newly added online filter during normal operation.

[0053] This online filter is preferably a cotton cartridge filter, designed to efficiently intercept solid impurities such as catalyst powder entrained in the circulating formaldehyde solution. Its filtration performance can be measured by its filtration efficiency. To characterize, and satisfy the following conditions:

[0054] ;

[0055] in, , The concentration of mechanical impurities in the circulating formaldehyde solution of the line filter, while This refers to the filtration efficiency of the filter. This condition ensures that the vast majority of mechanical impurities entering the circulating formaldehyde solution are effectively removed before entering the reactor.

[0056] The technical solution provided in this embodiment constructs a dual protection mechanism for candle filters through the coordinated implementation of steps one and two described above. Its core working principle lies in eliminating the main sources of contamination that cause clogging by addressing both the internal and external interfaces of the filter. Step one ensures that the liquid used for backflushing is highly clean, thus cleaning the inner surface of the filter cloth without introducing new impurities that could cause secondary deposition. Step two intercepts the catalyst powder carried by the circulating formaldehyde solution before it returns to the reactor, thereby protecting the outer surface of the filter cloth from contamination. This "dual approach" fundamentally changes the situation where impurities continuously accumulate on both sides of the filter.

[0057] Accordingly, embodiments of the present invention also provide a system for purifying the return liquid of a BYD reactor for performing the aforementioned method. This system, based on a BYD reactor R8101 equipped with a candle filter, critically adds the following units: a fine filtration unit, a backflush liquid supply line, and an online filter.

[0058] The fine filtration unit, in this embodiment, is a combination of filters F8101A / B and F8102A / B. Its inlet is connected to the coarse BYD collection tank T8101, and it is used to perform deep treatment on the coarse BYD solution to produce a finely filtered BYD solution that meets the requirements of high cleanliness.

[0059] The backflush fluid supply pipeline is a newly constructed pipeline system in this embodiment. It connects the outlet of the fine filtration unit to the backflush fluid tank T8105. Its core function is to supply the finely filtered BYD solution specifically and purely to the backflush system.

[0060] The online filter is a newly installed filtration device on the circulating formaldehyde return pipeline 81125-CD21-2”-P-IH. Its function is to perform final purification treatment on the circulating formaldehyde solution before it enters the BYD reactor R8101, intercepting any residual solid particles.

[0061] The method and system disclosed in this embodiment achieve significant beneficial effects. First, because both the backflushing liquid and the circulating formaldehyde solution are effectively purified, the clogging rate on both the inside and outside of the candle filter is significantly reduced. This direct technical effect brings a series of subsequent process and economic advantages.

[0062] The most direct advantage is a significantly extended service life of the candle filter bags. This means the unit can achieve longer periods of continuous and stable operation, reducing unplanned or frequent shutdowns due to filter replacements. This not only avoids production losses during downtime but also significantly reduces operating costs, specifically through reduced consumption of spare parts (such as filter bags) and a lighter workload for maintenance personnel. Ultimately, by improving the operational reliability of key equipment (the BYD reactor), this invention provides a solid guarantee for the long-term, high-efficiency, and high-profit operation of the entire production unit.

[0063] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for purifying the return liquid of a BYD reactor, wherein the BYD reactor is equipped with a candle filter for separating the catalyst from the crude BYD solution generated during the reaction, characterized in that, The method includes: Step 1: Use a portion of the finely filtered BYD solution as a backflushing liquid to backflush the candle filter; Step 2: Before returning the circulating formaldehyde solution to the BYD reactor, filter the circulating formaldehyde solution to remove mechanical impurities.

2. The method according to claim 1, characterized in that, Step one includes: finely filtering the crude BYD solution to obtain the finely filtered BYD solution.

3. The method according to claim 2, characterized in that, The concentration of mechanical impurities in the finely filtered BYD solution The concentration of mechanical impurities in the crude BYD solution : 。 4. The method according to claim 2, characterized in that, The fine filtration includes at least one stage of filtration on the crude BYD solution, with a filtration accuracy of no more than 5 μm.

5. The method according to claim 1, characterized in that, Step two is achieved by adding an online filter to the pipeline that returns the circulating formaldehyde solution to the BYD reactor.

6. The method according to claim 5, characterized in that, The online filter is a cotton cartridge filter.

7. The method according to claim 5, characterized in that, The online filter meets the following conditions for filtering the circulating formaldehyde solution: ； in, The concentration of mechanical impurities in the circulating formaldehyde solution entering the online filter. The concentration of mechanical impurities in the circulating formaldehyde solution flowing out of the online filter.

8. The method according to claim 1, characterized in that, The mechanical impurities include particles of the catalyst or its deactivation products.

9. The method according to claim 1, characterized in that, The purification process described in steps one and two reduces the clogging rate on both the inside and outside of the candle filter.

10. A system for purifying return liquid from a BYD reactor, comprising a BYD reactor equipped with a candle filter, characterized in that, The system also includes: A fine filtration unit is used to finely filter the crude BYD solution generated by the BYD reactor to obtain a finely filtered BYD solution. The backflush fluid supply line is configured to guide the finely filtered BYD solution from the outlet of the fine filtration unit to the candle filter as backflush fluid. An online filter, installed on the pipeline used to transport the circulating formaldehyde solution back to the BYD reactor, is used to filter the circulating formaldehyde solution before it is returned to the BYD reactor.

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