A low pressure evaporation separation method for butanol and octanol device
By optimizing the low-pressure evaporation separation method and the circulating gas system, the energy consumption and catalyst consumption of the butanol and octanol production unit were reduced, solving the problems of high energy consumption and short catalyst life caused by high-pressure evaporation, and achieving energy saving, consumption reduction and long-term catalyst operation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANJIN BOHUA YONGLI CHEM IND
- Filing Date
- 2026-03-04
- Publication Date
- 2026-06-05
AI Technical Summary
In existing butanol and octanol production units, the two-stage separation process of high-pressure evaporation and low-pressure evaporation results in huge consumption of hot water steam and circulating cooling water. High-temperature operation exacerbates the thermal decomposition of the catalyst, shortens the catalyst life, and increases costs.
A low-pressure evaporation separation method is adopted, and a circulating gas system is added. Through low-temperature evaporation and heat recovery, the operating temperature is reduced, the consumption of hot water steam and circulating water is reduced, and the evaporation effect is enhanced by air stripping, thus avoiding catalyst decomposition at high temperatures.
It significantly reduces equipment energy consumption and operating costs, extends the service life of rhodium phosphine catalysts, and has low retrofit costs and a quick return on investment.
Smart Images
Figure CN122145289A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of butanol and octanol production technology, and more specifically, relates to a low-pressure evaporation separation method for butanol and octanol production equipment. Background Technology
[0002] In existing butanol and octanol production units, the carbonyl synthesis reaction is the core process. This process uses a rhodium-phosphine complex as a catalyst to convert propylene and syngas (CO / H2) into n-butyraldehyde and isobutyraldehyde. The resulting mixture has a complex composition, containing not only the target product butyraldehyde but also unreacted syngas, byproducts, and the rhodium-phosphine catalyst. Therefore, achieving efficient and low-energy separation of butyraldehyde and the catalyst, and recycling the catalyst, is crucial for the long-term, economical operation of the entire unit.
[0003] Currently, the industrial process commonly employs a two-stage separation process of high-pressure evaporation followed by low-pressure evaporation to achieve effective separation and recovery of the product butyraldehyde and the rhodium phosphine catalyst. Specifically, the mixed solution from the reactor first enters a high-pressure evaporator with a hot water heating system, causing the light components and some butyraldehyde to evaporate. The remaining catalyst solution then enters a low-pressure evaporator for further separation. In the low-pressure evaporator, the material is heated again with hot water, the separated butyraldehyde vapor is condensed and recovered, and the concentrated catalyst solution is cooled and returned to the reactor for recycling.
[0004] However, in traditional evaporation separation processes, high-pressure evaporators require high temperatures to provide sufficient heat for gas-liquid separation, resulting in huge consumption of hot water steam. Simultaneously, the subsequent condensation process also requires a large amount of circulating cooling water, leading to persistently high overall energy consumption and operating costs. Furthermore, the high operating temperature of the high-pressure evaporator exacerbates the thermal decomposition of rhodium-phosphine catalyst ligands, increasing the impurity content of the catalyst system and causing rapid degradation of catalyst activity, shortening catalyst lifespan and increasing catalyst consumption costs. Therefore, it is necessary to rationally modify the existing evaporation separation system of the butanol and octanol unit to achieve energy conservation, consumption reduction, and long-term catalyst operation while ensuring product quality and production safety. Summary of the Invention
[0005] To overcome the shortcomings of existing technologies and address the problems of high energy consumption and short catalyst life in existing butanol and octanol production units, this invention proposes a low-pressure evaporation separation method for butanol and octanol units. By optimizing the existing process flow and adding key equipment, the method significantly reduces the system operating temperature, reduces steam and circulating water consumption, effectively extends the service life of the rhodium phosphine catalyst, and lowers production costs, while ensuring separation effect, product quality, and production safety.
[0006] The objective of this invention can be achieved through the following technical solutions.
[0007] A low-pressure evaporation separation method for a butanol / octanol unit includes the following steps: S1, The mixture after the carbonyl synthesis reaction in the butanol and octanol production unit enters the low-pressure evaporator for evaporation and separation. The gas-liquid mixture generated by evaporation is separated in the collection tank to obtain gaseous material and concentrated catalyst solution. S2, the gaseous material obtained from the gas-liquid separation in the collection tank is filtered through a demisting filter, then first passed into the shell side of the circulating gas heat exchanger for pre-cooling, and then enters the condenser for condensation. The condensed material is collected in the condensate receiving tank. S3 completes gas-liquid separation in the condensate receiving tank. The separated crude butyraldehyde is sent to the stabilization tower for purification. The separated gas phase material and the non-condensable gas generated by the condenser are both sent to the gas-liquid separation tank. After gas-liquid separation, the liquid droplets entrained in the gas phase are removed. The liquid droplets after gas-liquid separation are returned to the condensate receiving tank. After gas-liquid separation, the gas phase is extracted by the circulating fan and preheated in the tube side of the circulating gas heat exchanger. Then it returns to the top of the low-pressure evaporator to participate in the circulation.
[0008] S4, after the concentrated catalyst solution obtained from the gas-liquid separation in the collection tank is cooled, part of it is returned to the carbonyl synthesis reactor for recycling, and the other part is sent to the water washing tower for catalyst regeneration.
[0009] Further, the mixture in step S1 comprises 84%-86% butyraldehyde, 0.15%-0.3% bidentate phosphine ligand, 0.7%-0.8% propylene, 1%-1.66% propane, 0.3%-0.4% methane, 0.4%-0.5% water, 0.07%-0.08% carbon monoxide, 0.1%-0.2% carbon dioxide, 0.01%-0.02% acetaldehyde, 0.07%-0.08% acetylene, and 11%-12% trimer by mass fraction.
[0010] Further, the mixture described in step S1 is prepared at a concentration of 15-25 mg / L. 3 A flow rate of / h enters the low-pressure evaporator, the bottom temperature of which is maintained at 80℃-90℃, the operating pressure is 0.07MPa-0.09MPa, and hot water heating is used.
[0011] Furthermore, in step S2, a wire mesh demister and a candle-shaped filter are installed on the top of the collection tank. The gaseous material obtained from the gas-liquid separation in the collection tank first passes through the wire mesh demister and then through the candle-shaped filter to remove catalyst droplets entrained in the gas. The purified high-temperature gaseous phase enters the shell side of the circulating gas heat exchanger and exchanges heat with the low-temperature circulating mixed gas from the circulating fan in the tube side, pre-cooling the purified high-temperature gaseous phase to 65℃-75℃. Subsequently, it enters the condenser for further condensation to 41℃-43℃ to ensure that butyraldehyde is fully liquefied. The condensed material is collected in the receiving tank of the condenser.
[0012] Furthermore, the main components of the non-condensable gas mentioned in step S3 are nitrogen, carbon dioxide, hydrogen, and light methane components.
[0013] Furthermore, in step S3, the gas phase extracted by the circulating fan is sent to the tube side of the circulating gas heat exchanger, where it undergoes heat exchange with the high-temperature gas phase material in the shell side and is preheated to 60°C-70°C. Then, it returns to the top of the low-pressure evaporator to participate in the circulation. The outlet pressure of the circulating compressor is controlled at 0.09MPa-0.11MPa. Under normal operating conditions, a portion of the gas phase components at the outlet of the circulating fan is transported to the low-pressure fuel gas pipeline for recycling to control the system pressure. When excessive emissions or abnormal pressure occur, the system switches to the flare main for safe venting.
[0014] Furthermore, the concentrated catalyst solution obtained from the gas-liquid separation in the collection tank in step S4 is cooled to 48°C-52°C by a cooler.
[0015] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: (1) Significant energy saving and consumption reduction: By discontinuing the hot water heating system of the high-pressure evaporator, the steam consumption of this part is eliminated. At the same time, the added non-condensable gas circulation system promotes low-temperature evaporation. The non-condensable gas circulation system runs continuously, driving the non-condensable gas to circulate efficiently in the loop, and enhances evaporation by means of its gas lift effect, which reduces the operating temperature of the low-pressure evaporator by about 20°C, reduces the demand of the low-pressure evaporator on external heat sources, thereby improving the evaporation separation effect and reducing the amount of hot water steam used. The circulating gas heat exchanger pre-cools the high-temperature gaseous material, reduces the cooling load of the subsequent condensation process, and reduces the consumption of circulating water. The combined effect reduces the overall steam consumption of the unit by 10%-15%, the circulating water consumption by 8%-10%, and the operating cost of the unit is significantly reduced.
[0016] (2) Extending catalyst life: The core of process optimization lies in reducing the system operating temperature. By shutting down the high-pressure evaporator and using a circulating fan to enhance the evaporation effect, the overall operating temperature of the low-pressure evaporation system is reduced, avoiding the decomposition of the active ligands of the rhodium phosphine catalyst at high temperatures, reducing the generation of impurities, enhancing the stability of the active center, and extending the service life of the rhodium phosphine catalyst by 20%-30%, effectively reducing the catalyst replenishment cost.
[0017] (3) Simple modification and quick return: The main changes are process optimization and a small amount of equipment addition (circulating fan, gas-liquid separator, circulating gas heat exchanger). There is no need to replace the main equipment on a large scale. The investment cost is low, the modification cycle is short, and the modification cost can be recovered in a short period of time after it is put into use.
[0018] In summary, addressing the issues of high energy consumption and short catalyst life in butanol and octanol plants, this invention optimizes the evaporation separation process by introducing gas circulation and heat recovery devices into the low-pressure evaporation system. This reduces the operating temperature of the low-pressure evaporator, achieving efficient evaporation separation under low-temperature conditions. This invention significantly reduces the consumption of circulating water and hot water steam, and provides a mild and stable operating environment for the rhodium phosphine catalyst, thereby extending its service life and saving on butanol and octanol production costs. This invention achieves energy conservation and consumption reduction while ensuring butanol and octanol product quality and production safety, offering advantages such as low modification costs and a short investment payback period. Attached Figure Description
[0019] Figure 1 This is a schematic diagram illustrating the principle of the low-pressure evaporation separation method of the butanol and octanol apparatus of the present invention.
[0020] Reference numerals in the attached drawings: 1-Low-pressure evaporator, 2-Collection tank, 3-Circulating gas heat exchanger, 4-Condenser, 5-Condensate receiving tank, 6-Circulating fan, 7-Gas-liquid separator, 8-Cooler, 9-Discharge pump, 10-Condensate pump. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0022] like Figure 1 As shown, the process flow of the low-pressure evaporation separation method for the butanol and octanol unit of the present invention mainly involves a low-pressure evaporator 1, a collection tank 2, a circulating gas heat exchanger 3, a condenser 4, a condensate receiving tank 5, a circulating fan 6, a gas-liquid separator 7, a cooler 8, a discharge pump 9, a condensate pump 10, and related pipelines. The circulating gas heat exchanger 3, the circulating fan 6, and the gas-liquid separator 7 constitute the non-condensable gas circulation system of this unit, and the collection tank 2, the cooler 8, and the discharge pump 9 constitute the catalyst circulation system of this unit.
[0023] The material inlet of the low-pressure evaporator 1 is connected via a pipeline to the liquid phase material outlet of the high-pressure evaporator receiving tank in the butanol and octanol production unit. The hot water heating system of the high-pressure evaporator is shut down. The gas-liquid mixture outlet at the bottom of the low-pressure evaporator 1 is connected via a pipeline to the feed inlet of the collection tank 2. A wire mesh demister and a candle filter are installed at the top of the collection tank 2 to remove catalyst droplets entrained in the gas. A cooler 8 is installed at the bottom of the collection tank 2. The liquid phase outlet at the bottom of the collection tank 2 is connected via a pipeline to the inlet of the discharge pump 9. The outlet of the discharge pump 9 is connected via pipelines to the catalyst feed inlet of the carbonyl synthesis reactor and the water washing tower in the butanol and octanol production unit. Most of the material is returned to the catalyst feed inlet of the carbonyl synthesis reactor, and a small portion of the material is transported to the water washing tower for catalyst regeneration.
[0024] The top gas phase outlet of the collection tank 2 is connected to the shell-side inlet of the circulating gas heat exchanger 3 via a pipeline. The shell-side outlet of the circulating gas heat exchanger 3 is connected to the inlet of the condenser 4 via a pipeline. The tube-side inlet of the circulating gas heat exchanger 3 is connected to the outlet of the circulating fan 6 via a pipeline. The tube-side outlet of the circulating gas heat exchanger 3 is connected to the top gas phase return port of the low-pressure evaporator 1 via a pipeline. The circulating gas heat exchanger 3 is a shell-and-tube heat exchanger that pre-cools the high-temperature gas phase material from the collection tank 2, reducing the cooling load on the subsequent condenser 4. Simultaneously, it preheats the gas returning from the outlet of the circulating fan 6, preventing low-temperature gas from affecting the evaporation efficiency of the low-pressure evaporator 1, thereby reducing the consumption of circulating water and hot water steam. The outlet pipeline of the circulating fan 6 is connected to the low-pressure fuel gas pipeline and the flare main via branch pipelines. Under normal operating conditions, a portion of the gas phase components is transported to the low-pressure fuel gas pipeline for recycling. In cases of excessive emissions or abnormal pressure, the system switches to the flare main for safe venting.
[0025] The liquid phase outlet of the condenser 4 is connected to the inlet of the condensate receiving tank 5 via a pipeline. Simultaneously, the non-condensable gas outlet of the condenser 4 and the top gas phase outlet of the condensate receiving tank 5 are both connected to the inlet of the gas-liquid separator 7 via pipelines. The gas-liquid separator 7 is used to separate and remove liquid droplets entrained in the gas phase, preventing damage to the impeller of the circulating fan 6. The gas phase outlet at the top of the gas-liquid separator 7 is connected to the inlet of the circulating fan 6 via a pipeline. The condensate recovery outlet at the bottom of the gas-liquid separator 7 is connected to the condensate recovery inlet of the condensate receiving tank 5 via a pipeline. The liquid phase outlet at the bottom of the condensate receiving tank 5 is connected to the inlet of the condensate pump 10 via a pipeline. The outlet of the condensate pump 10 is connected to the stabilization tower via a pipeline, used to transport the separated crude butyraldehyde to the subsequent refining process. Furthermore, in the process flow of this invention, valves can be installed on each of the above pipelines.
[0026] The process flow of the low-pressure evaporation separation method for the butanol and octanol apparatus of the present invention specifically includes the following steps: S1, the mixture after the carbonyl synthesis reaction in the butanol and octanol production unit, after passing through the high-pressure evaporator, directly enters the low-pressure evaporator 1 (the hot water heating system of the high-pressure evaporator is shut down) for evaporation and separation. The gas-liquid mixture generated by evaporation enters the collection tank 2, where gas-liquid separation (i.e., separation of crude butyraldehyde and catalyst solution) is carried out to obtain gaseous material (crude butyraldehyde) and concentrated catalyst solution.
[0027] The mixture may include, by mass fraction, 84%-86% butyraldehyde, 0.15%-0.3% bidentate phosphine ligand, 0.7%-0.8% propylene, 1%-1.66% propane, 0.3%-0.4% methane, 0.4%-0.5% water, 0.07%-0.08% carbon monoxide, 0.1%-0.2% carbon dioxide, 0.01%-0.02% acetaldehyde, 0.07%-0.08% acetylene, and 11%-12% trimer. The mixture is prepared at a concentration of 15-25 mg / L. 3 A flow rate of / h enters the low-pressure evaporator 1, the bottom temperature of which is maintained at 80℃-90℃, the operating pressure is 0.07MPa-0.09MPa, and hot water heating is used.
[0028] S2, the gaseous material (crude butyraldehyde) obtained by gas-liquid separation in the collection tank 2 is first pre-cooled by the shell side of the circulating gas heat exchanger 3 after being filtered by demisting, and then enters the condenser 4 for condensation. The condensed material is collected in the condensate receiving tank 5.
[0029] Specifically, the crude butyraldehyde gas obtained from the gas-liquid separation in collection tank 2 first passes through a wire mesh demister and then through a candle filter to remove catalyst droplets entrained in the gas. The purified high-temperature gas phase enters the shell side of the circulating gas heat exchanger 3 and exchanges heat with the low-temperature circulating mixed gas from the circulating fan 6 in the tube side, pre-cooling the purified high-temperature gas phase to 65℃-75℃. Subsequently, it enters the condenser 4 for further condensation to 41℃-43℃ to ensure that the butyraldehyde is fully condensed and liquefied, preventing material loss caused by its discharge with non-condensable gas. The condensed material is collected in the condenser receiving tank 5.
[0030] In step S3, gas-liquid separation is completed in the condenser receiving tank 5. The separated liquid crude butyraldehyde is sent to the stabilization tower for purification by the condensate pump 10. The separated gaseous material and the non-condensable gas generated by condensation in the condenser 4 are both sent to the gas-liquid separator 7. After gas-liquid separation, the liquid droplets entrained in the gas phase are removed. The liquid droplets after gas-liquid separation are returned to the condensate receiving tank 5. The gas phase after gas-liquid separation is extracted by the circulating fan 6 and introduced into the tube side of the circulating gas heat exchanger 3. After heat exchange with the high-temperature gaseous material in the shell side, it is preheated to 60℃-70℃ and then returned to the top of the low-pressure evaporator 1 to participate in the circulation. The main components of the non-condensable gas are light components such as nitrogen, carbon dioxide, hydrogen, and methane.
[0031] Preferably, the air lift generated by the circulating fan 6 can accelerate the evaporation process of the material in the low-pressure evaporator 1. The outlet pressure of the circulating compressor 6 is controlled at 0.09MPa-0.11MPa. Under normal operating conditions, a portion of the gas phase components at the outlet of the circulating fan 6 is transported to the low-pressure fuel gas pipeline for recycling to control the system pressure. When excessive emissions or abnormal pressure occur, the system switches to the flare main for safe venting.
[0032] S4, the concentrated catalyst solution obtained from gas-liquid separation in collection tank 2 is cooled to 48℃-52℃ by cooler 8 and transported by discharge pump 9. Most of it is returned to the carbonyl synthesis reactor for recycling, and a small part is sent to the water washing tower for catalyst regeneration.
[0033] Example 1 S1, the mixture after the carbonyl synthesis reaction in the butanol / octanol production unit (85% butyraldehyde, 0.2% bidentate phosphine ligand, 0.75% propylene, 1.4% propane, 0.355% methane, 0.45% water, 0.075% carbon monoxide, 0.15% carbon dioxide, 0.015% acetaldehyde, 0.075% acetylene, and 11.456% trimer by mass fraction), after passing through a high-pressure evaporator, is released at 15m... 3 The flow rate of [amount] / h directly enters the low-pressure evaporator 1 (the hot water heating system of the high-pressure evaporator is disabled) for evaporation and separation. The bottom temperature of the low-pressure evaporator 1 is 80℃, the operating pressure is 0.07MPa, and hot water heating is used. The gas-liquid mixture generated by evaporation in the low-pressure evaporator 1 enters the collection tank 2, where crude butyraldehyde and catalyst solution are separated to obtain gaseous crude butyraldehyde and concentrated catalyst solution.
[0034] S2, the crude butyraldehyde gaseous phase obtained from the separation in collection tank 2 first passes through a wire mesh demister and then through a candle filter to remove catalyst droplets entrained in the gas. The purified high-temperature gaseous phase enters the shell side of the circulating gas heat exchanger 3, where it exchanges heat with the low-temperature circulating mixed gas from the circulating fan 6 in the tube side, pre-cooling the purified high-temperature gaseous phase to 65°C. Subsequently, it enters the condenser 4 for further condensation to 42°C, ensuring that the butyraldehyde is fully condensed and liquefied. The condensed material is collected in the condenser receiving tank 5.
[0035] In step S3, gas-liquid separation is completed in the condenser receiving tank 5. The separated liquid crude butyraldehyde is sent to the stabilization tower for purification by the condensate pump 10. The separated gaseous material and the non-condensable gas (mainly composed of nitrogen, carbon dioxide, hydrogen, methane and other light components) generated by condensation in the condenser 4 are all transported to the gas-liquid separator 7. After gas-liquid separation, the liquid droplets entrained in the gas phase are removed. The liquid droplets after gas-liquid separation are returned to the condensate receiving tank 5. The gas phase after gas-liquid separation is extracted by the circulating fan 6 and introduced into the tube side of the circulating gas heat exchanger 3. After heat exchange with the high-temperature gaseous butyraldehyde in the shell side, it is preheated to 60°C and then returned to the top of the low-pressure evaporator 1 to participate in the circulation.
[0036] The air lift generated by the circulating fan 6 can accelerate the evaporation process of the material in the low-pressure evaporator 1. The outlet pressure of the circulating compressor 6 is controlled at 0.09 MPa. Under normal operating conditions, part of the gas phase components at the outlet of the circulating fan 6 are transported to the low-pressure fuel gas pipeline for recycling to control the system pressure. When the emission volume is too large or the pressure is abnormal, it is switched to the flare main for safe venting.
[0037] S4, the concentrated catalyst solution obtained from gas-liquid separation in collection tank 2 is cooled to 50°C by cooler 8 and then transported by discharge pump 9. Most of it is returned to the carbonyl synthesis reactor for recycling, and a small portion is sent to the water washing tower for catalyst regeneration.
[0038] After 720 hours of stable operation in this embodiment, it was found that compared with before the modification, the average operating temperature of the low-pressure evaporator was significantly reduced by 19.6℃, the system steam consumption was reduced by 10%, the circulating water consumption was reduced by 8%, the catalyst activity decay rate was slowed down by 28%, and the service life was extended by 20%. Considering the combined energy saving and catalyst benefits, the modification investment is expected to be recovered within 10-14 months.
[0039] Example 2 S1, the mixture after the carbonyl synthesis reaction in the butanol / octanol production unit (84% butyraldehyde, 0.3% bidentate phosphine ligand, 0.8% propylene, 1.66% propane, 0.3% methane, 0.5% water, 0.07% carbon monoxide, 0.2% carbon dioxide, 0.02% acetaldehyde, 0.08% acetylene, and 12% trimer by mass fraction), after passing through a high-pressure evaporator at 20m³ 3 The flow rate of [amount] / h directly enters the low-pressure evaporator 1 (the hot water heating system of the high-pressure evaporator is disabled) for evaporation and separation. The bottom temperature of the low-pressure evaporator 1 is 85℃, the operating pressure is 0.08MPa, and hot water heating is used. The gas-liquid mixture generated by evaporation in the low-pressure evaporator 1 enters the collection tank 2, where crude butyraldehyde and catalyst solution are separated to obtain gaseous crude butyraldehyde and concentrated catalyst solution.
[0040] S2, the crude butyraldehyde gas obtained from the separation in collection tank 2 first passes through a wire mesh demister and then through a candle filter to remove catalyst droplets entrained in the gas. The purified high-temperature gas phase enters the shell side of the circulating gas heat exchanger 3, where it exchanges heat with the low-temperature circulating mixed gas from the circulating fan 6 in the tube side, pre-cooling the purified high-temperature gas phase to 70°C. Subsequently, it enters the condenser 4 for further condensation to 41°C, ensuring that the butyraldehyde is fully condensed and liquefied. The condensed material is collected in the condenser receiving tank 5.
[0041] In step S3, gas-liquid separation is completed in the condenser receiving tank 5. The separated liquid crude butyraldehyde is sent to the stabilization tower for purification by the condensate pump 10. The separated gaseous material and the non-condensable gas (mainly composed of nitrogen, carbon dioxide, hydrogen, methane and other light components) generated by condensation in the condenser 4 are all transported to the gas-liquid separator 7. After gas-liquid separation, the liquid droplets entrained in the gas phase are removed. The liquid droplets after gas-liquid separation are returned to the condensate receiving tank 5. The gas phase after gas-liquid separation is extracted by the circulating fan 6 and introduced into the tube side of the circulating gas heat exchanger 3. After heat exchange with the high-temperature gaseous butyraldehyde in the shell side, it is preheated to 65°C and then returned to the top of the low-pressure evaporator 1 to participate in the circulation.
[0042] The air lift generated by the circulating fan 6 can accelerate the evaporation process of the material in the low-pressure evaporator 1. The outlet pressure of the circulating compressor 6 is controlled at 0.1 MPa. Under normal operating conditions, part of the gas phase components at the outlet of the circulating fan 6 are transported to the low-pressure fuel gas pipeline for recycling to control the system pressure. When the emission volume is too large or the pressure is abnormal, it is switched to the flare main for safe venting.
[0043] S4, the concentrated catalyst solution obtained from gas-liquid separation in collection tank 2 is cooled to 48°C by cooler 8 and then transported by discharge pump 9. Most of it is returned to the carbonyl synthesis reactor for recycling, and a small part is sent to the water washing tower for catalyst regeneration.
[0044] After 720 hours of stable operation in this embodiment, it was found that compared with before the modification, the average operating temperature of the low-pressure evaporator was significantly reduced by 20.3℃, the system steam consumption was reduced by 13.7%, the circulating water consumption was reduced by 9.8%, the catalyst activity decay rate was significantly slowed down, and the service life could be extended by 28%. Considering the combined energy saving and catalyst benefits, the modification investment is expected to be recovered within 10-14 months.
[0045] Example 3 S1, the mixture after the carbonyl synthesis reaction in the butanol / octanol production unit (86% butyraldehyde, 0.15% bidentate phosphine ligand, 0.7% propylene, 1% propane, 0.4% methane, 0.4% water, 0.08% carbon monoxide, 0.1% carbon dioxide, 0.01% acetaldehyde, 0.07% acetylene, and 11% trimer by mass fraction), after passing through a high-pressure evaporator at 25m... 3 The flow rate of [amount] / h directly enters the low-pressure evaporator 1 (the hot water heating system of the high-pressure evaporator is disabled) for evaporation and separation. The bottom temperature of the low-pressure evaporator 1 is 90℃, the operating pressure is 0.09MPa, and hot water heating is used. The gas-liquid mixture generated by evaporation in the low-pressure evaporator 1 enters the collection tank 2, where crude butyraldehyde and catalyst solution are separated to obtain gaseous crude butyraldehyde and concentrated catalyst solution.
[0046] S2, the crude butyraldehyde gaseous phase obtained from the separation in collection tank 2 first passes through a wire mesh demister and then through a candle filter to remove catalyst droplets entrained in the gas. The purified high-temperature gaseous phase enters the shell side of the circulating gas heat exchanger 3, where it exchanges heat with the low-temperature circulating mixed gas from the circulating fan 6 in the tube side, pre-cooling the purified high-temperature gaseous phase to 75°C. Subsequently, it enters the condenser 4 for further condensation to 43°C, ensuring that the butyraldehyde is fully condensed and liquefied. The condensed material is collected in the condenser receiving tank 5.
[0047] In step S3, gas-liquid separation is completed in the condenser receiving tank 5. The separated liquid crude butyraldehyde is sent to the stabilization tower for purification by the condensate pump 10. The separated gaseous material and the non-condensable gas (mainly composed of nitrogen, carbon dioxide, hydrogen, methane and other light components) generated by condensation in the condenser 4 are all transported to the gas-liquid separator 7. After gas-liquid separation, the liquid droplets entrained in the gas phase are removed. The liquid droplets after gas-liquid separation are returned to the condensate receiving tank 5. The gas phase after gas-liquid separation is extracted by the circulating fan 6 and introduced into the tube side of the circulating gas heat exchanger 3. After heat exchange with the high-temperature gaseous butyraldehyde in the shell side, it is preheated to 70°C and then returned to the top of the low-pressure evaporator 1 to participate in the circulation.
[0048] The air lift generated by the circulating fan 6 can accelerate the evaporation process of the material in the low-pressure evaporator 1. The outlet pressure of the circulating compressor 6 is controlled at 0.11 MPa. Under normal operating conditions, part of the gas phase components at the outlet of the circulating fan 6 are transported to the low-pressure fuel gas pipeline for recycling to control the system pressure. When the emission volume is too large or the pressure is abnormal, it is switched to the flare main for safe venting.
[0049] S4, the concentrated catalyst solution obtained from gas-liquid separation in collection tank 2 is cooled to 52°C by cooler 8 and then transported by discharge pump 9. Most of it is returned to the carbonyl synthesis reactor for recycling, and a small part is sent to the water washing tower for catalyst regeneration.
[0050] After 720 hours of stable operation, this embodiment shows that compared with before the modification, the average operating temperature of the low-pressure evaporator is significantly reduced by 20°C, the system steam consumption is reduced by 15%, the circulating water consumption is reduced by 10%, the catalyst activity decay rate is significantly slowed down, and the service life can be extended by 30%. Considering the combined energy saving and catalyst benefits, the modification investment is expected to be recovered within 10-14 months.
[0051] Although the functions and working processes of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific functions and working processes described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these are within the protection scope of the present invention.
Claims
1. A low-pressure evaporation separation method for a butanol and octanol unit, characterized in that, Includes the following steps: S1, the mixture after carbonyl synthesis reaction in the butanol and octanol production unit enters the low-pressure evaporator (1) for evaporation and separation. The gas-liquid mixture generated by evaporation is separated in the collection tank (2) to obtain gas phase material and concentrated catalyst solution. S2, the gaseous material obtained by gas-liquid separation in the collection tank (2) is filtered through a demisting filter and then first passed into the shell side of the circulating gas heat exchanger (3) for pre-cooling, and then enters the condenser (4) for condensation. The condensed material is collected in the condensate receiving tank (5). S3, gas-liquid separation is completed in the condensate receiving tank (5). The separated crude butyraldehyde is sent to the stabilizer tower for refining. The separated gas phase material and the non-condensable gas generated by the condenser (4) are both sent to the gas-liquid separator (7). The liquid droplets entrained in the gas phase are removed by gas-liquid separation. The liquid droplets after gas-liquid separation are returned to the condensate receiving tank (5). The gas phase after gas-liquid separation is drawn out by the circulating fan (6) and preheated in the tube side of the circulating gas heat exchanger (3). Then it returns to the top of the low-pressure evaporator (1) to participate in the circulation. S4, after the concentrated catalyst solution obtained from gas-liquid separation in the collection tank (2) is cooled, part of it is returned to the carbonyl synthesis reactor for recycling, and the other part is sent to the water washing tower for catalyst regeneration.
2. The low-pressure evaporation separation method for the butanol / octanol unit according to claim 1, characterized in that, The mixture in step S1 comprises 84%-86% butyraldehyde, 0.15%-0.3% bidentate phosphine ligand, 0.7%-0.8% propylene, 1%-1.66% propane, 0.3%-0.4% methane, 0.4%-0.5% water, 0.07%-0.08% carbon monoxide, 0.1%-0.2% carbon dioxide, 0.01%-0.02% acetaldehyde, 0.07%-0.08% acetylene, and 11%-12% trimer by mass fraction.
3. The low-pressure evaporation separation method for the butanol / octanol unit according to claim 1, characterized in that, The mixture described in step S1 is at a concentration of 15-25m 3 The flow rate is / h into the low-pressure evaporator (1), the bottom temperature of which is maintained at 80℃-90℃, the operating pressure is 0.07MPa-0.09MPa, and hot water heating is used.
4. The low-pressure evaporation separation method for the butanol / octanol apparatus according to claim 1, characterized in that, In step S2, the top of the collection tank (2) is equipped with a wire mesh demister and a candle filter. The gas phase material obtained by gas-liquid separation in the collection tank (2) first passes through the wire mesh demister and then through the candle filter to remove the catalyst droplets entrained in the gas. The purified high-temperature gas phase enters the shell side of the circulating gas heat exchanger (3) and exchanges heat with the low-temperature circulating mixed gas from the circulating fan (6) in the tube side to pre-cool the purified high-temperature gas phase to 65℃-75℃. Then, it enters the condenser (4) for further condensation to 41℃-43℃ to ensure that the butyraldehyde is fully liquefied. The condensed material is collected in the condenser receiving tank (5).
5. The low-pressure evaporation separation method for the butanol / octanol apparatus according to claim 1, characterized in that, The main components of the non-condensable gas mentioned in step S3 are nitrogen, carbon dioxide, hydrogen, and light methane components.
6. The low-pressure evaporation separation method for the butanol / octanol unit according to claim 1, characterized in that, In step S3, the gas phase extracted by the circulating fan (6) is sent to the tube side of the circulating gas heat exchanger (3), and after heat exchange with the high-temperature gas phase material in its shell side, it is preheated to 60℃-70℃, and then returns to the top of the low-pressure evaporator (1) to participate in the circulation; the outlet pressure of the circulating compressor (6) is controlled at 0.09MPa-0.11MPa. Under normal operating conditions, the gas phase components at the outlet of the circulating fan (6) are transported to the low-pressure fuel gas pipeline for recycling to control the system pressure. When the discharge volume is too large or the pressure is abnormal, it is switched to the flare main for safe venting.
7. The low-pressure evaporation separation method for the butanol and octanol apparatus according to claim 1, characterized in that, The concentrated catalyst solution obtained by gas-liquid separation in the collection tank (2) in step S4 is cooled to 48℃-52℃ by the cooler (8).