A PVC mixing and dewatering device mixer preheater heptane heating process

Abstract

The application discloses a PVC mixed dehydration device mixer preheater heptane heating process, which comprises a blocking resolver, an acetylene cooler, an acetylene demister, a mixer, a hydrogen chloride cooler, a hydrogen chloride demister, a first mixer cooler, a second mixed gas cooler, a first-stage hydrochloric acid mist filter, a second-stage hydrochloric acid mist filter, an acid collecting tank and a mixed gas preheater which are sequentially connected; the process further comprises a hot water tank and a hot water conveying pump which are used for heating the mixed gas preheater, hot water in the hot water tank is sent into the mixed gas preheater through the hot water conveying pump and returns to the hot water tank after circulation; the process further comprises a heptane heater and a heptane conveying shield pump, the heptane heater is connected with a heptane supplement pipeline, heptane in the heptane heater is input into the mixed gas preheater to be heated through the heptane conveying shield pump and returns to the hot water tank after circulation, and the hot water tank is communicated with the heptane heater; an original hot water return pipeline is communicated with the heptane heater through a pipeline.

Description

Technical Field

[0001] This invention belongs to the field of chemical production technology, specifically relating to a heptane heating process for a mixer preheater in a PVC mixing and dehydration device. Background Technology

[0002] In PVC chemical production, the ratio of acetylene to hydrogen chloride and the hydrogen chloride content in the mixed gas are subject to extremely high requirements. Acetylene, after passing through an inhibitor, acetylene cooler, and acetylene demister, is mixed with hydrogen chloride in a mixer to form a mixed gas. This mixed gas then passes through a mixed gas cooler (first and second mixer coolers), a primary hydrochloric acid mist filter, and a secondary hydrochloric acid mist filter to remove hydrogen chloride before entering a mixed gas preheater. The preheated mixed gas then enters the converter within the conversion unit to synthesize VCM.

[0003] The processed gaseous hydrogen chloride forms liquid hydrochloric acid which enters the acid collection tank. A portion of the gaseous hydrogen chloride enters the hydrogen chloride cooler upon entering the mixer, and after the hydrogen chloride demister, it is used to activate the catalyst. The entire mixing and dehydration unit ensures the production requirements of the acetylene and hydrogen chloride mixture while also controlling the hydrochloric acid content in the mixture at each stage of the process to guarantee the normal operation of subsequent conversion units. However, the current mixed gas preheater uses hot water heating. If a leak occurs in the heat exchanger tubes, causing the mixed gas to contain water and form hydrochloric acid, it will cause severe corrosion to the converter in the subsequent conversion unit, resulting in irreparable damage. Summary of the Invention

[0004] To address the problem of internal leakage in heat exchanger tubes, where leaked water reacts with the mixer to form hydrochloric acid that corrodes the converter, this invention provides a heptane heating process for the mixer preheater in a PVC mixing and dehydration device. This provides a more reliable method for heating the mixed gas, ensuring the normal operation of the subsequent converter.

[0005] Therefore, the present invention adopts the following technical solution:

[0006] A heptane heating process for a PVC mixing and dehydration device's mixer preheater includes, in sequence, a deionizer, an acetylene cooler, an acetylene demister, a mixer, a hydrogen chloride cooler, a hydrogen chloride demister, a first mixer cooler, a second mixed gas cooler, a primary hydrochloric acid mist filter, a secondary hydrochloric acid mist filter, an acid collection tank, and a mixed gas preheater; it also includes a hot water tank for heating the mixed gas preheater and a hot water delivery pump, wherein hot water in the hot water tank is sent to the mixed gas preheater via the hot water delivery pump, and then returned to the hot water tank after circulation; characterized in that;

[0007] It also includes a heptane heater and a heptane delivery shielded pump. The heptane heater is connected to a heptane replenishment pipeline. The heptane in the heptane heater is fed into the mixed gas preheater for heating through the heptane output pipeline and the heptane delivery shielded pump. The heptane is circulated back to the hot water tank, which is connected to the heptane heater. The original hot water return pipeline is connected to the heptane heater through a pipeline. A sampling port is provided on the heptane output pipeline, and a heptane sampling valve is connected to the sampling port.

[0008] The heptane heater is connected to a by-product steam pipeline, and the heptane heater is heated by the by-product steam.

[0009] A heptane remote thermometer is installed on the heptane output pipeline behind the heptane delivery shielded pump, and a steam delivery regulating valve is installed on the by-product steam pipeline. The steam delivery regulating valve and the heptane remote thermometer are interlocked.

[0010] The heptane output pipeline is also equipped with a heptane delivery regulating valve, and the mixer outlet pipeline of the mixed gas preheater is equipped with a mixed gas outlet remote thermometer, which is interlocked with the heptane delivery regulating valve.

[0011] The heating process includes the following steps:

[0012] 1) Open the steam delivery regulating valve to deliver by-product steam to heat the heptane heater, start the heptane delivery shield to circulate heptane, adjust the steam delivery regulating valve through the heptane remote thermometer, and open the heptane replenishment pipeline valve to replenish heptane according to the system operation.

[0013] 2) Open the heptane delivery regulating valve and adjust the valve using the remote thermometer at the mixed gas outlet;

[0014] 3) Open the heptane sampling valve at least once a day to take a sample at the sampling port to analyze the mixed gas content and water content in the heptane; if the water content is higher than the safety threshold, stop the mixing and dehydration device, close the steam delivery regulating valve and the heptane delivery regulating valve, stop the heptane delivery shielded pump, and check the mixed gas preheater and the heptane heater; restart the system after reducing the water content.

[0015] The beneficial effects of this invention are as follows:

[0016] The key feature of this invention is that it replaces the original hot water heating with heptane heating, avoiding the problem of internal leakage in the heat exchanger tubes, which could cause the mixed gas to contain water and form hydrochloric acid that corrodes the converter. This provides a more reliable method for heating the mixed gas, ensuring the normal operation of the subsequent converter. Attached Figure Description

[0017] Figure 1 This is a system schematic diagram of the present invention;

[0018] In the diagram: 1-Isolator, 2-Acetylene cooler, 3-Acetylene demister, 4-Mixer, 5-Hydrogen chloride cooler, 6-Hydrogen chloride demister, 7-First mixer cooler, 8-Second mixed gas cooler, 9-First-stage hydrochloric acid mist filter, 10-Second-stage hydrochloric acid mist filter, 11-Acid collection tank, 12-Mixed gas preheater, 13-Hot water tank, 14-Hot water transfer pump, 15-Heptane heater, 16-Steam transfer regulating valve, 17-Heptane transfer shielded pump, 18-Heptane remote thermometer, 19-Heptane sampling valve, 20-Sampling port, 21-Heptane transfer regulating valve, 22-Mixed gas outlet remote thermometer. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0020] like Figure 1 As shown, a heptane heating process for a PVC mixing and dehydration device includes a preheater for the mixer, which is connected in sequence as follows: a deionizer 1, an acetylene cooler 2, an acetylene demister 3, a mixer 4, a hydrogen chloride cooler 5, a hydrogen chloride demister 6, a first mixer cooler 7, a second mixed gas cooler 8, a primary hydrochloric acid mist filter 9, a secondary hydrochloric acid mist filter 10, an acid collection tank 11, and a mixed gas preheater 12; it also includes a hot water tank 13 and a hot water delivery pump 14 for heating the mixed gas preheater 12. The hot water in the hot water tank 13 is sent to the mixed gas preheater 12 by the hot water delivery pump 14 and then returned to the hot water tank 13 after circulation.

[0021] It also includes a heptane heater 15 and a heptane delivery shielded pump 17. The heptane heater 15 is connected to a heptane replenishment pipeline. The heptane in the heptane heater 15 is fed into the mixed gas preheater 12 for heating through the heptane output pipeline and the heptane delivery shielded pump 17. The heptane returns to the hot water tank 13 after circulation. The hot water tank 13 is connected to the heptane heater 15. The original hot water return pipeline is connected to the heptane heater 15 through a pipeline. A sampling port 20 is provided on the heptane output pipeline. A heptane sampling valve 19 is connected to the sampling port 20.

[0022] The heptane heater 15 is connected to a by-product steam pipeline, and the heptane heater 15 is heated by the by-product steam. The by-product steam pipeline inputs by-product steam at a pressure of 0.2-0.3 MPa.

[0023] A heptane remote thermometer 18 is installed on the heptane output pipeline downstream of the heptane delivery shielded pump 17, and a steam delivery regulating valve 16 is installed on the by-product steam pipeline. The steam delivery regulating valve 16 and the heptane remote thermometer 18 are interlocked. A heptane delivery regulating valve 21 is also installed on the heptane output pipeline, and a mixed gas outlet remote thermometer 22 is installed on the mixer outlet pipeline of the mixed gas preheater 12. The mixed gas outlet remote thermometer 22 is interlocked with the heptane delivery regulating valve 21.

[0024] The working principle of this invention is as follows:

[0025] A heptane heater 15 replaces the original hot water heating in the hot water tank 13. A heptane delivery shielded pump 17 delivers heated heptane to the mixed gas preheater 12 to heat the mixed gas. The heptane heater 15 uses by-product steam provided by the hydrogen chloride synthesis unit for heating. The steam after heat exchange is reused in the hot water tank 13. Due to the excellent physicochemical properties of heptane, and its status as a raw material for heating the shell side of the converter, it causes minimal corrosion to the equipment. This effectively solves the problem of internal leakage in the tubes of the heat exchanger in the mixed gas preheater 12, which led to water in the mixed gas causing hydrochloric acid corrosion of the converter.

[0026] The operation steps of this invention are as follows:

[0027] 1) Open the steam delivery regulating valve 16 to deliver 0.2-0.3MPa by-product steam from the hydrogen chloride synthesis unit to heat the heptane heater 15, start the heptane delivery shield to circulate heptane, and regulate the steam delivery regulating valve 16 through the heptane remote thermometer 18 (the heptane remote thermometer 18 is interlocked with the steam delivery regulating valve 16). Open the heptane replenishment pipeline valve as needed to replenish heptane.

[0028] 2) Open the heptane delivery regulating valve 21 and regulate the valve of the heptane delivery regulating valve 21 through the remote thermometer 22 at the outlet of the mixed gas (the heptane delivery regulating valve 21 is interlocked with the remote thermometer 22 at the outlet of the mixed gas).

[0029] 3) Open the heptane sampling valve 19 once a day to take a sample at the sampling port 20 to analyze the mixed gas content and water content in the heptane. If any non-compliance is found, stop the mixing and dehydration device in time, close the steam delivery regulating valve 16 and the heptane delivery regulating valve 21, stop the heptane delivery shielded pump 17, and check the mixed gas preheater 12 and the heptane heater 15.

Claims

1. A PVC mixing and dewatering device mixer preheater heptane heating process, comprising a blocking resolver (1), an acetylene cooler (2), an acetylene demister (3), a mixer (4), a hydrogen chloride cooler (5), a hydrogen chloride demister (6), a first mixer cooler (7), a second mixed gas cooler (8), a first stage hydrochloric acid mist filter (9), a second stage hydrochloric acid mist filter (10), an acid collection tank (11) and a mixed gas preheater (12) connected in sequence; further comprising a hot water tank (13) and a hot water delivery pump (14) for heating the mixed gas preheater (12), the hot water in the hot water tank (13) is sent into the mixed gas preheater (12) through the hot water delivery pump (14), and after circulation, it returns to the hot water tank (13); characterized in that ； The heptane heater (15) is connected with a heptane supplement pipeline, and the heptane in the heptane heater (15) is heated by the mixed gas preheater (12) through a heptane output pipeline and the heptane delivery shield pump (17), and the heptane is returned to the hot water tank (13) after circulation, and the hot water tank (13) is connected with the heptane heater (15); the original hot water return pipeline is connected with the heptane heater (15) through a pipeline; a sampling port (20) is arranged on the heptane output pipeline, and a heptane sampling valve (19) is connected with the sampling port (20); The heptane heater (15) is heated by the by-product steam; A heptane remote thermometer (18) is arranged on the heptane output pipeline behind the heptane delivery shield pump (17), a steam delivery adjusting valve (16) is arranged on the by-product steam pipeline, and the steam delivery adjusting valve (16) and the heptane remote thermometer (18) are interlocked; A heptane delivery adjusting valve (21) is further arranged on the heptane output pipeline, a mixed gas outlet remote thermometer (22) is arranged on the mixer outlet pipeline of the mixed gas preheater (12), and the mixed gas outlet remote thermometer (22) and the heptane delivery adjusting valve (21) are interlocked; The heating process comprises the following steps: 1) the steam delivery adjusting valve (16) is opened to deliver the by-product steam to heat the heptane heater (15), the heptane delivery shield is started to circulate the heptane, the steam delivery adjusting valve (16) is adjusted by the heptane remote thermometer (18), the heptane supplement pipeline valve is opened to supplement the heptane according to the system operation condition; 2) the heptane delivery adjusting valve (21) is opened, and the heptane delivery adjusting valve (21) is adjusted by the mixed gas outlet remote thermometer (22); 3) the heptane sampling valve (19) is opened at least once a day, the mixed gas content and water content in the heptane are sampled and analyzed at the sampling port (20), if the water content is higher than the safety threshold, the mixed dehydration device is stopped, the steam delivery adjusting valve (16) and the heptane delivery adjusting valve (21) are closed, the heptane delivery shield pump (17) is stopped, and the mixed gas preheater (12) and the heptane heater (15) are checked; after the water content is reduced, the system is restarted.

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