Treatment and recovery system for exhaust gas in polypropylene production process
By constructing an exhaust gas treatment and recovery system for the polypropylene production process, the problems of exhaust gas resource waste and environmental pollution have been solved, and the efficient recovery and utilization of propylene and nitrogen substitution have been achieved, thus achieving the goal of energy conservation and consumption reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2026-03-27
AI Technical Summary
During the polypropylene production process, the exhaust gas contains a large amount of unreacted olefin monomers, comonomers, hydrogen, nitrogen and other components. Directly releasing these into the flare for combustion not only wastes resources but also pollutes the environment, and existing technologies have failed to effectively recycle and utilize them.
A treatment and recovery system was designed, comprising an exhaust gas delivery pipeline, a filter, a three-stage compressor, a cooler, a degassing tank, a propylene-propane separation tower, a condenser, a separation tank, and a buffer tank. Through three-stage compression, cooling, condensation, and separation, propylene is recovered and sent back to the reactor. The light components in the buffer tank are used to replace nitrogen, reducing nitrogen consumption.
This technology enables the efficient recovery and utilization of propylene in exhaust gases, reducing resource waste, lowering production costs, and reducing nitrogen usage, thus achieving energy conservation and consumption reduction.
Smart Images
Figure CN224040453U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a kind of processing recovery systems, in particular to a kind of processing recovery system of discharge gas in polypropylene production process. BACKGROUND
[0002] Polyolefin is the high molecular compound formed by the polyaddition reaction of many identical or different simple olefin molecules (such as ethylene, propylene, 1-butene, 1-pentene, etc.), among which polyethylene and polypropylene are the most important. As a kind of synthetic resin with high demand, polypropylene has a wide range of applications in various fields of production and life due to its abundant raw materials, low price, easy processing, excellent comprehensive performance, and the market demand has been growing rapidly. However, there is a common problem in the production of polypropylene, i.e. a large amount of discharge gas is generated during the production process. These discharge gases mainly come from reactors, degassing bins and other devices, containing a large amount of unreacted olefin monomers, comonomers, hydrogen, nitrogen, reaction byproducts, alkane impurities and induced condensing agents. In industrial production process, a large amount of non-condensable gas is discharged to flare combustion treatment (this part of gas is called flare gas), but the non-condensable gas contains propylene which can be recycled and utilized. If the tail gas is sent to the flare without conditions, it will not only cause great waste of resources, but also cause serious environmental pollution. Therefore, in order to reduce the waste of resources, improve the utilization rate of raw materials and reduce the production cost, certain technical means need to be taken to recycle the effective components in the tail gas and send them back to the reaction system. SUMMARY
[0003] The utility model aims at providing a kind of processing recovery system of discharge gas in polypropylene production process, which has simple connection structure, fully realizes the recycling of propylene in discharge gas, and better realizes energy saving and consumption reduction.
[0004] The utility model is implemented by the following technical solutions: the utility model provides a kind of processing recovery system of discharge gas in polypropylene production process, which includes discharge gas conveying pipeline, filter, three-stage compressor, cooler, degassing tank, propylene propane separation tower, condenser, separation tank and buffer tank;The discharge gas conveying pipeline, the filter, the three-stage compressor and the cooler are sequentially communicated according to the gas flow direction, the liquid outlet of the cooler is communicated with the liquid inlet of the degassing tank, the liquid outlet of the degassing tank is communicated with the liquid inlet of the propylene propane separation tower, the gas outlet of the cooler is communicated with the gas inlet of the condenser, the liquid outlet of the separation tank is respectively communicated with the liquid inlet of the degassing tank and the cooling medium inlet of the condenser, the liquid outlet of the condenser is communicated with the liquid inlet of the separation tank, the gas outlets of the condenser and the separation tank are both communicated with the gas inlet of the buffer tank, and the bottom gas outlet of the buffer tank is communicated with the gas inlet of the three-stage compressor.
[0005] Further, it further includes a torch, the top gas outlet of the buffer tank is communicated with the gas inlet of the torch through a pressure relief pipe, an adjusting valve is arranged on the pressure relief pipe; a pressure sensor is arranged on the buffer tank; the signal output end of the pressure sensor is connected with the signal input end of a controller through a signal connection, and the signal output end of the controller is connected with the signal input end of the adjusting valve through a signal connection.
[0006] Further, a liquid level sensor is arranged on the separation tank, and an electromagnetic valve is arranged on the pipeline between the separation tank and the propylene-propane separation tower; the liquid level sensor is connected with the signal input end of a controller through a signal connection, and the signal output end of the controller is connected with the signal input end of the electromagnetic valve through a signal connection.
[0007] The utility model discloses the advantages are: 1, the utility model discloses the connecting structure is simple, easy to realize, through the three stage compressor compression again through the cooler, condenses after the condenser, after the buffer tank buffering, recovers propylene heavy component gas, recovers again, finally after propylene-propane separation tower separation is sent to the reactor of polypropylene and participates in the reaction, and the recovery and utilization of propylene in the discharge gas are fully realized;2, the noncondensable gas and light component separated out of the buffer tank are used to make PDS conveying gas, stripping gas of the degassing bin and the back flushing gas of the filter bag, so as to replace the use of nitrogen, reduce the use amount of nitrogen, and better realize energy saving and consumption reduction. BRIEF DESCRIPTION OF DRAWINGS
[0008] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or the prior art description, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without creating labor.
[0009] Figure 1 It is the whole structure schematic diagram of the utility model.
[0010] Discharge gas conveying pipeline 1, filter 2, three stage compressor 3, cooler 4, degassing tank 5, propylene-propane separation tower 6, condenser 7, separation tank 8, buffer tank 9, torch 10, pressure relief pipe 11, adjusting valve 12, pressure sensor 13, controller 14, liquid level sensor 15, electromagnetic valve 16. DETAILED DESCRIPTION
[0011] Embodiment: as Figure 1As shown, a polypropylene production process exhaust gas treatment and recovery system, which comprises exhaust gas conveying pipeline 1, filter 2, three-stage compressor 3, cooler 4, degassing tank 5, propylene propane separation tower 6, condenser 7, separation tank 8, buffer tank 9 and flare 10; exhaust gas conveying pipeline 1, filter 2, three-stage compressor 3 and cooler 4 are sequentially communicated in the direction of gas flow, the outlet of cooler 4 is communicated with the inlet of degassing tank 5, the outlet of degassing tank 5 is communicated with the inlet of propylene propane separation tower 6, the gas outlet of cooler 4 is communicated with the gas inlet of condenser 7, the liquid outlet of separation tank 8 is respectively communicated with the liquid inlet of degassing tank 5 and the cooling medium inlet of condenser 7, the liquid outlet of condenser 7 is communicated with the liquid inlet of separation tank 8, the gas outlets of condenser 7 and separation tank 8 are both communicated with the gas inlet of buffer tank 9, and the bottom gas outlet of buffer tank 9 is communicated with the gas inlet of three-stage compressor 3.
[0012] The top gas outlet of buffer tank 9 is communicated with the gas inlet of flare 10 through pressure relief pipe 11, and adjusting valve 12 is arranged on pressure relief pipe 11; pressure sensor 13 is arranged on buffer tank 9; the signal output end of pressure sensor 13 is signal-connected with the signal input end of controller 14, and the signal output end of controller 14 is signal-connected with the signal input end of adjusting valve 12.
[0013] Liquid level sensor 15 is arranged on separation tank 8, and electromagnetic valve 16 is arranged on the pipeline between separation tank 8 and propylene propane separation tower 6; the signal output end of liquid level sensor 15 is signal-connected with the signal input end of controller 14, and the signal output end of controller 14 is signal-connected with the signal input end of electromagnetic valve 16.
[0014] Working principle: exhaust gas is conveyed to filter 2 through exhaust gas conveying pipeline 1 for filtration, the filtered exhaust gas is compressed by three-stage compressor 3 and then enters cooler 4 for cooling to form two streams of gas phase and liquid phase, the cooled liquid phase propylene enters degassing tank 5 for degassing and then enters propylene propane separation tower 6 for fractionation, the separated propylene is pumped into the reactor of polypropylene for reaction by a propylene recovery pump, so that the recovery and utilization of propylene in exhaust gas are fully realized. The gas phase from cooler 4 is further deep-cooled by condenser 7, the propylene liquid in separation tank 8 enters condenser 7 as a cooling medium to condense the propylene liquid in the gas phase, the condensed propylene liquid enters separation tank 8, the non-condensable gas and a small amount of propylene gas phase in separation tank 8 are conveyed to buffer tank 9, the buffer tank 9 separates the discharged gas, the light components and non-condensable gas at the top of buffer tank 9 are used as PDS conveying gas, stripping gas of degassing bin and backwashing gas of filter 2, so as to replace nitrogen and reduce the use amount of nitrogen, thereby better realizing energy saving and consumption reduction; the propylene heavy component gas at the bottom of buffer tank 9 reenters three-stage compressor 3 for recycling.
[0015] The pressure sensor 13 detects the pressure in the buffer tank 9 at all times and transmits a signal to the controller 14, when the pressure exceeds 4.2 MPa, the controller 14 controls the regulating valve 12 to open, and the gas in the buffer tank 9 is delivered to the flare 10 for incineration, preventing overpressure of the system, when the pressure is lower than 3.6 MPa, the controller 14 controls the regulating valve 12 to close.
[0016] The liquid level sensor 15 detects the liquid level in the separation tank 8 at all times and transmits a signal to the controller 14, when the liquid level exceeds the upper limit value, the controller 14 controls the electromagnetic valve 16 to open, and the liquid in the separation tank 8 is delivered to the degassing tank 5, when the liquid level is lower than the lower limit value, the controller 14 controls the electromagnetic valve 16 to close.
[0017] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A system for treating and recovering vent gas from a polypropylene production process, characterized in that, It includes exhaust gas delivery pipeline, filter, three-stage compressor, cooler, degassing tank, propylene propane separation tower, condenser, separation tank and buffer tank; the exhaust gas delivery pipeline, the filter, the three-stage compressor and the cooler are sequentially communicated in the gas flow direction, the liquid outlet of the cooler is communicated with the liquid inlet of the degassing tank, the liquid outlet of the degassing tank is communicated with the liquid inlet of the propylene propane separation tower, the gas outlet of the cooler is communicated with the gas inlet of the condenser, the liquid outlet of the separation tank is respectively communicated with the liquid inlet of the degassing tank and the cooling medium inlet of the condenser, the liquid outlet of the condenser is communicated with the liquid inlet of the separation tank, the gas outlets of the condenser and the separation tank are both communicated with the gas inlet of the buffer tank, the bottom gas outlet of the buffer tank is communicated with the gas inlet of the three-stage compressor.
2. The system for treating and recovering vent gas from a polypropylene production process according to claim 1, characterized in that, It also includes a torch, the top gas outlet of the buffer tank is communicated with the gas inlet of the torch through a pressure relief pipe, an adjusting valve is arranged on the pressure relief pipe; a pressure sensor is arranged on the buffer tank; the signal output end of the pressure sensor is signal-connected with the signal input end of a controller, the signal output end of the controller is signal-connected with the signal input end of the adjusting valve.
3. A system for treating and recovering vent gas from a polypropylene production process according to claim 1 or 2, characterized in that A liquid level sensor is arranged on the separation tank, an electromagnetic valve is arranged on the pipeline between the separation tank and the propylene propane separation tower; the liquid level sensor is signal-connected with the signal input end of a controller, the signal output end of the controller is signal-connected with the signal input end of the electromagnetic valve.