Apparatus and method for producing vinyl chloride using mercury-free catalyst

Abstract

The present application relates to the technical field of vinyl chloride synthesis, in particular to a mercury-free catalyst catalytic production device and method of vinyl chloride. The front and rear conversion heads of the conversion system are respectively provided with a gas distributor. The condensing acid outlet pipeline connected with the conversion device is connected with the condensing acid tank in the condensing acid separation system. The gas inlet pipeline of the conversion device is provided with a gas flow adjusting system. The shell side of the conversion device is provided with a temperature control system. The vinyl chloride outlet pipeline connected with the top of the conversion device is provided with an online analysis system. The online analysis system is used to analyze the content of hydrogen chloride and acetylene in the conversion product every hour. When the content of hydrogen chloride and acetylene is high, the conversion device flow adjusting interlock control program is executed to fully exert the catalytic activity of the catalyst and maximize the catalytic efficiency. The condensing acid is discharged from the conversion device to avoid corrosion of the main equipment and pipeline. The gas inlet flow of the conversion device is dynamically adjusted to stabilize the quality of the crude vinyl chloride product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vinyl chloride synthesis, in particular to a mercury-free catalyst device and production method for producing vinyl chloride. BACKGROUND

[0002] PVC is a plastic material widely used in packaging, building materials, automobiles, electronics, agriculture and daily use, etc. According to the data of the Polyvinyl Chloride Industry Association, as of the end of 2021, the PVC industry capacity in China reached 27.13 million tons. However, there are a series of problems in PVC production, such as high energy consumption, lack of mercury resources, serious environmental pollution, etc. Especially, the consumption of mercury resources accounts for 60% of the national mercury resources, ranking first in the use of mercury in China. In 2017, China began to implement the Minamata Convention on Mercury, requiring that the amount of mercury used in polyvinyl chloride in 2020 be reduced by 50% compared with 2010. Therefore, the chlor-alkali industry clearly requires "mercury reduction and mercury-free". At present, colleges and universities, enterprises and research institutions in China have successively carried out research on mercury-free catalysts such as gold-based, ruthenium-based and tin-based, and have made many beneficial attempts in formula development, reaction mechanism discussion and industrial application.

[0003] When mercury-free catalyst is used as an ethyne hydrochlorination catalyst, due to the limitations of catalyst preparation process and active components, there are one or more problems such as high water content in the catalyst, high activation temperature of the catalytic reaction, low bed reaction temperature, poor stability of the active components in the catalyst, and short service life, which affect the industrialization process of mercury-free catalyst. In order to achieve the mercury-free industry requirement of vinyl chloride production as soon as possible, in addition to strengthening the research and development of catalyst active components and formula, it is more important to analyze the actual problems in the industrialization operation of mercury-free catalysts according to the characteristics of mercury-free catalyst catalytic system, such as the lagging and poor precision of hot water flow adjustment when the catalyst activity is low, and the complete reliance on manual analysis of conversion products in the reaction process, which makes the operation cumbersome and makes it impossible to automatically adjust the raw material gas flow according to the content of ethyne and hydrogen chloride in the conversion products. New process control schemes are developed from multiple dimensions such as catalyst activation, raw material gas distribution, hot water temperature and gas inlet amount adjustment, to fully exert the catalytic activity of mercury-free catalyst and prolong the service life of catalyst. SUMMARY

[0004] The purpose of the present application is to provide a mercury-free catalyst device and production method for producing vinyl chloride, which can prolong the service life of the catalyst and improve the catalytic efficiency of the catalyst.

[0005] The device adopts the following technical scheme:

[0006] The device for producing vinyl chloride by catalysis of mercury-free catalyst comprises a condensing acid separation system, a conversion system and a heat circulation system, gas distributors are arranged on the lower heads of the front and rear conversion reactors in the conversion system, the condensing acid downflow pipelines connected with the conversion reactors are connected with the condensing acid tanks in the condensing acid separation system, the gas inlet pipelines of the conversion reactors are provided with gas inlet flow adjusting systems, the shell sides of the conversion reactors are connected with temperature control systems, and the crude vinyl chloride gas outlet pipelines connected with the top of the conversion reactors are provided with online analysis systems and conversion reactor interlocking control systems.

[0007] The device for producing vinyl chloride by catalysis of mercury-free catalyst comprises a condensing acid separation system, a conversion system and a heat circulation system, gas distributors are arranged on the lower heads of the front and rear conversion reactors in the conversion system, the condensing acid downflow pipelines connected with the conversion reactors are connected with the condensing acid tanks in the condensing acid separation system, the gas inlet pipelines of the conversion reactors are provided with gas inlet flow adjusting systems, the shell sides of the conversion reactors are connected with temperature control systems, and the crude vinyl chloride gas outlet pipelines connected with the top of the conversion reactors are provided with online analysis systems.

[0008] The device adopts the following preferred schemes:

[0009] The conversion reactor interlocking control system comprises conversion reactor flow adjusting interlocking control and conversion reactor temperature adjusting interlocking control.

[0010] The temperature adjusting system comprises two hot water upflow pipelines and one hot water downflow pipeline, one end of each of the two hot water upflow pipelines is connected with the outlet of a hot water pump, and the other end is connected with the shell side of the conversion reactor; a steam ejector and a hot water pressure pump are arranged on the hot water upflow pipeline.

[0011] The gas inlet flow adjusting system comprises a gas inlet flow adjusting valve and a gas inlet flow meter, which are arranged on the gas inlet pipeline of the conversion reactor.

[0012] The online analysis system comprises a to-be-measured gas sampling conduit, a gas inlet electromagnetic valve, a quantitative container, a gas outlet electromagnetic valve, a metering pump, a pure water tank, a chromatograph, a metering end point judging device, a waste gas absorption device, a waste liquid recovery device, a PLC control unit and a DCS operation system; the crude vinyl chloride gas outlet pipeline of the front conversion reactor is connected with the to-be-measured gas sampling conduit, the to-be-measured sampling conduit is connected with the quantitative container through the gas inlet electromagnetic valve, the quantitative container is connected with the waste gas absorption device through the gas outlet electromagnetic valve, the top of the quantitative container is connected with the metering end point judging device, and the left side of the quantitative container is connected with the metering pump; the inlet of the metering pump is connected with the pure water tank, and the quantitative container is connected with the waste liquid recovery device through the gas outlet electromagnetic valve; the crude vinyl chloride gas outlet pipeline of the rear conversion reactor is connected with the to-be-measured sampling conduit, the to-be-measured sampling conduit is connected with the chromatograph through the gas inlet electromagnetic valve, and the terminal of the chromatograph is connected with the waste gas absorption device; the PLC control unit sets the logic control program of the metering pump, the chromatograph and the electromagnetic valves; the DCS operation system outputs the front hydrogen chloride content and the rear acetylene content, and is provided with online analysis starting and stopping buttons.

[0013] The connecting pipeline is provided with a one-way valve.

[0014] The condensing acid tank is provided with a waste acid removal pipeline below and a hydrogen chloride tail gas removal pipeline above.

[0015] The method adopts the following technical scheme:

[0016] The production method is performed according to the following steps:

[0017] When the catalyst is activated, the generated condensing acid is discharged to the condensing acid tank in time to avoid corrosion of the generated condensing acid to the conversion equipment and pipelines; when the raw material gas is fed, the gas is fed from below, and the gas distributor is used to ensure uniform distribution of the mixed gas in the front converter; in the initial stage of catalyst operation, the catalytic activity is high, and after the mixed gas enters the front converter, the catalytic reaction generates a large amount of heat, at this time, the valve on the hot water connecting pipeline is closed, and the hot water inlet and outlet pipeline is used to remove the reaction heat in time; in the middle stage of catalyst operation, the catalytic activity of the catalyst is stable, and the mixed gas feed rate is adjusted in real time according to the values of the online analysis system of the ethyne and hydrogen chloride in the crude vinyl chloride outlet pipeline; in the later stage of catalyst operation, when the catalytic activity is low, the steam ejector and the pressure pump on the hot water inlet pipeline are opened to increase the temperature and pressure of the hot water circulation heat exchange system, thereby increasing the temperature of the reaction bed; at the same time, the online analysis system of ethyne and hydrogen chloride is used to analyze the hydrogen chloride and ethyne content in the conversion product every hour, and when the hydrogen chloride and ethyne content is high, the converter flow regulation interlocking control program is executed to fully exert the catalytic activity of the catalyst and maximize the catalytic efficiency of the catalyst.

[0018] The production method adopts the following preferred scheme:

[0019] In the converter temperature regulation interlocking control system, when the converter bed temperature is between 150 DEG C and 170 DEG C, the hot water inlet valve is adjusted; when the converter bed temperature is greater than or equal to 170 DEG C, the converter gas feed rate is adjusted; in the converter flow regulation interlocking control system, when the online analysis of the conversion product shows that the front hydrogen chloride content is greater than or equal to 25% to 30%, and the rear ethyne content is greater than or equal to 3.5% to 4.5%, the converter gas feed flow is adjusted.

[0020] When the catalyst is activated by a ruthenium-based catalyst, the generated condensed acid is discharged in time to a condensed acid tank to avoid corrosion of the conversion equipment and pipelines by the generated condensed acid; when the raw material gas is fed, the gas is fed from below and the gas distributor is used to ensure uniform distribution of the mixed gas in the front-stage converter; in the initial stage of catalyst operation, the catalytic activity is high, and after the mixed gas enters the front-stage converter, the catalytic reaction generates a large amount of heat; at this time, the valve on the hot water connection pipeline is closed, and the hot water supply and return pipelines are used to remove the reaction heat in time; in the middle stage of catalyst operation, the catalytic activity of the catalyst is stable, and the mixed gas feed rate is adjusted in real time according to the values of the online monitoring of acetylene and hydrogen chloride in the crude vinyl chloride outlet pipeline; when the reaction bed temperature is higher than the set value of 150-170°C, the temperature adjustment interlock control program is executed, the front-stage and back-stage converters are operated in series, the mixed gas enters the front-stage converter through the front-stage converter feed pipeline, and after the crude vinyl chloride is generated by the front-stage reaction, the crude vinyl chloride is transported to the back-stage converter through the pipeline for further reaction, and the vinyl chloride generated by the back-stage converter is qualified vinyl chloride; the change in the hot water circulation amount is automatically switched between the two hot water supply pipelines with the change in the bed temperature; in the later stage of catalyst operation, when the catalytic activity is low, the steam ejector and the pressurizing pump on the hot water supply pipeline are opened to increase the temperature and pressure of the hot water circulation and heat exchange system, thereby increasing the reaction bed temperature; at the same time, the online monitoring system of acetylene and hydrogen chloride is used to analyze the content of hydrogen chloride and acetylene in the conversion product every hour, and when the content of hydrogen chloride and acetylene is high: the front-stage hydrogen chloride content is ≥30% and the back-stage acetylene content is ≥3.5%, the converter flow adjustment interlock control program is executed to fully develop the catalytic activity of the catalyst and maximize the catalytic efficiency of the catalyst.

[0021] The condensed acid generated when the catalyst is activated by gold-based catalyst is discharged in time to the condensed acid tank to avoid corrosion of the conversion equipment and pipelines by the generated condensed acid; when the raw material gas is fed, the gas is fed from below and the gas distributor is used to ensure uniform distribution of the mixed gas in the front-stage converter; in the initial stage of catalyst operation, the catalytic activity is high, and after the mixed gas enters the front-stage converter, the heat generated by the catalytic reaction is high, at this time, the valve on the hot water connection pipeline is closed, and the reaction heat is carried away in time by the hot water supply and return pipelines; in the middle stage of catalyst operation, the catalytic activity of the catalyst is stable, and the mixed gas feed rate is adjusted in real time according to the values of the online monitoring of acetylene and hydrogen chloride in the crude vinyl chloride outlet pipeline; when the bed temperature is higher than the set value ≤170℃, the temperature adjustment interlock control program is executed; the hot water circulation amount changes automatically between the two upper water pipelines as the bed temperature changes; in the later stage of catalyst operation, when the catalytic activity is low, the steam ejector and the booster pump on the hot water supply pipeline are opened to increase the temperature and pressure of the hot water circulation and heat exchange system, and the communication valve on the hot water communication pipeline is opened to increase the bed temperature; at the same time, the online monitoring system of acetylene and hydrogen chloride is used to analyze the content of hydrogen chloride and acetylene in the conversion product every hour, when the content of hydrogen chloride and acetylene is high: the content of hydrogen chloride in the front-stage is ≥30%, and the content of acetylene in the back-stage is ≥3.5%, the converter flow adjustment interlock control program is executed to fully exert the catalytic activity of the catalyst and maximize the catalytic efficiency of the catalyst.

[0022] Control method of hydrogen chloride and acetylene online analysis program:

[0023] S1, start button: after the operator clicks the start button or the program execution start operation, the DCS system automatically starts the program;

[0024] S2, according to the PLC control program, test the content of hydrogen chloride in the front-stage: open the corresponding electromagnetic valve in turn, fill the measured gas in the quantitative container, and complete the sampling operation;

[0025] S3, start the metering pump to deliver pure water to the quantitative container, and stop the metering pump when the metering end point determination device displays a negative value;

[0026] S4, transmit the pure water flow delivered by the metering pump to the DCS operation system output, and enter the next step;

[0027] S5, according to the PLC control program, test the content of acetylene in the back-stage: open the corresponding electromagnetic valve in turn to make the measured gas enter the chromatograph, and complete the sampling operation;

[0028] S6, start the chromatographic analysis, and transmit the related test results to the DCS operation system;

[0029] S7, start the reset button, and the program ends.

[0030] The DCS is configured with a converter flow regulation interlock control program, and the control steps are as follows:

[0031] S1. The operator presses the start button, and the DCS system starts the automatic program.

[0032] S2. Detect the converter intake flow control valve: When the valve opening is ≥20%, the valve opening is reduced by 0.5%, and after a certain time T, proceed to the next step;

[0033] S3. Perform online analysis procedures for hydrogen chloride and acetylene;

[0034] S4. If the hydrogen chloride content at the front end is ≥30% and the acetylene content at the back end is ≥3.5% (by volume), proceed to step 2; otherwise, proceed to the next step.

[0035] S5. Press the reset button to end the program.

[0036] The DCS is configured with a converter temperature regulation interlock control program, and the control steps are as follows:

[0037] S1. Determine the converter bed temperature. If the temperature at any point in the bed exceeds 170℃, proceed to step 2. If the temperature at any point in the bed is between 150℃ and 170℃, proceed to step 3. If the bed temperature is below 150℃, proceed to step 4.

[0038] S2. Reduce the valve opening of the converter intake flow regulating valve by 2%, delay for a certain time T, and then execute step 1.

[0039] S3. Determine the opening degree of the large and small hot water supply pipe valves: If the opening degree of the large pipe valve is ≥5%, increase the opening degree of the regulating valve by 2%; if the opening degree of the small pipe valve is ≥5%, increase the opening degree of the regulating valve by 5%, delay for a certain time T, and then execute step 1.

[0040] S4, Program ends.

[0041] Compared with existing technologies, the advantages of the above invention are:

[0042] 1. This invention can fully utilize the catalytic activity of mercury-free catalysts, increase reaction temperature, and extend catalyst lifespan.

[0043] 2. Promptly remove the condensed acid generated during the catalyst activation process from the converter to prevent corrosion of the main equipment and pipelines.

[0044] 3. According to different periods of catalyst use, timely adjust the heat exchange of converter. When the heat release of catalytic reaction is large, use hot water to take away the excess reaction heat; when the heat release of catalytic reaction is insufficient to maintain the reaction temperature of mercury-free catalyst bed, use hot water to increase the bed temperature, reduce the circulating hot water quantity and use hot water backwater to increase the water pressure, etc. to increase the bed temperature and maximize the catalytic efficiency of catalyst.

[0045] 4. The automatic adjusting system of mercury-free catalyst inlet gas flow, dynamically adjusts the inlet gas flow of converter according to the change of conversion product components, stabilizes the quality of crude vinyl chloride product and further plays the catalytic life of mercury-free catalyst in later period. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is the process flow diagram of the present application.

[0047] Figure 2 is the structural schematic diagram of the gas distributor. DETAILED DESCRIPTION

[0048] The present application will be described in detail below in combination with the drawings and examples:

[0049] Figures 1-2 Front converter 1-1, back converter 1-2, condensed acid underflow pipeline 2, condensed acid tank 3, hydrogen chloride tail gas pipeline 4, condensed acid waste acid pipeline 5, hot water upwater pipeline one 6, hot water upwater pipeline two 7, hot water backwater pipeline 8, hot water communication pipeline 9, acetylene and hydrogen chloride online analysis system 10, mixed gas inlet pipeline 11, front crude vinyl chloride outlet pipeline 12, back crude vinyl chloride outlet pipeline 13, measured gas sampling conduit one 14-1, measured gas sampling conduit two 14-2, inlet electromagnetic valve one 15-1, inlet electromagnetic valve two 15-2, quantitative container 16, outlet electromagnetic valve one 17-1, outlet electromagnetic valve two 17-2, metering pump 18, pure water tank 19, metering end point determination device 20, waste liquid recovery device 21, waste gas absorption device 22, chromatograph 23, PLC control unit 24, DCS operation system 25, gas distributor 26, one-way valve 27.

[0050] In the device of the present example, in order to ensure that the raw material gas is uniformly distributed in the converter, the gas distributor 26 is arranged in the lower head of the front converter 1-1 in the conversion system, and the gas distributor 26 is also arranged in the lower head of the back converter. The gas distributor is made of carbon steel or stainless steel, has a diameter of DN600-DN1000, has φ30mm-φ60mm holes laid in the distributor, and is fixed in the cavity 100mm-500mm away from the bottom end of the lower head by welding.

[0051] The condensing acid downflow pipeline 2 connected with the front and rear two converters is connected with the condensing acid tank 3 in the condensing acid separation system, the gas inlet pipeline of the converter is provided with a gas flow adjusting system, the shell side of the converter is connected with a temperature control system, the front and rear crude chloroethylene gas outlet pipelines 12 and 13 connected with the top of the converter are respectively provided with an acetylene and hydrogen chloride online analysis system 10 and a converter interlocking control system. One end of the condensing acid downflow pipeline 2 is connected with the raw material gas inlet pipeline of the lower head of the front and rear converters, and the other end is connected with the side upper pipe of the condensing acid tank 3, so as to timely guide the condensing acid generated in the catalyst activation process from the converter to the condensing acid tank 3. At the same time, the condensing acid downflow pipeline 2 is provided with a water flow sight glass, so as to facilitate the observation of the flow of the condensing acid generated in the activation process.

[0052] The converter interlocking control system includes converter flow adjusting interlocking control and converter temperature adjusting interlocking control.

[0053] The temperature adjusting system includes two hot water upflow pipelines (as shown in Figure 1 The hot water upflow pipeline one 6 and the hot water upflow pipeline two 7 are carbon steel pipelines with DN80-DN100 and DN10-DN20, and one hot water downflow pipeline 8. One end of the two hot water upflow pipelines is connected with the outlet of the hot water pump, and the other end is connected with the hot water inlet of the shell side of the converter. Steam ejectors and hot water pressure pumps are arranged on the hot water upflow pipelines, so as to improve the temperature and pressure of the hot water.

[0054] The hot water communication pipeline 9 is additionally arranged between the hot water upflow pipeline and the hot water downflow pipeline 8. The hot water communication pipeline 9 is provided with a one-way valve 27, so as to ensure that the hot water downflow unidirectionally flows to the hot water upflow pipeline.

[0055] The gas flow adjusting system includes a gas flow adjusting valve and a gas flow meter, which are arranged on the mixed gas inlet pipeline 11 of the converter.

[0056] The acetylene and hydrogen chloride online analysis system 10 includes a to-be-measured gas sampling conduit one 14-1, a to-be-measured sampling conduit two 14-2, an inlet electromagnetic valve one 15-1, an inlet electromagnetic valve two 15-2, a quantitative container 16, an outlet electromagnetic valve one 17-1, an outlet electromagnetic valve two 17-2, a metering pump 18, a pure water tank 19, a chromatograph 23, a metering end point judging device 20, a waste gas absorption device 22, a waste liquid recovery device 21, a PLC control unit 24 and a DCS operation system 25.

[0057] Front desk converter crude chlorine and dilute gas pipeline 12 and to be measured gas sampling catheter 14-1 connection, to be measured sampling catheter 14-1 through the inlet solenoid valve 15-1 connection quantitative container 16, quantitative container 16 above through the outlet solenoid valve 17-1 connection waste gas absorption device 22, top connection metering end point determination device 20, left side and metering pump 18 connection, metering pump 18 import connection pure water tank 19; quantitative container 16 below through the outlet solenoid valve 17-2 connection waste liquid recovery device 21.

[0058] Backstage converter crude chlorine and dilute gas pipeline 13 and to be measured sampling catheter 14-2 connection, to be measured sampling catheter 14-2 through the inlet solenoid valve 15-2 connection chromatograph 23, chromatograph 23 terminal connection waste gas absorption device 22.

[0059] PLC control unit 24 sets the logic control program of metering pump 18, chromatograph 23 and solenoid valve; DCS operating system 25 outputs front desk hydrogen chloride content and backstage acetylene content value, and is provided with online analysis start and stop button.

[0060] Condensed acid tank 3 in the condensing acid separation system is equipped with condensed acid waste acid pipeline 5 below, which will produce hydrogen chloride, condensed acid is treated respectively. Condensed acid tank 3 is equipped with hydrogen chloride tail gas pipeline 4 above.

[0061] Raw material inlet flow regulation system (automatic): in different stages of mercury-free catalyst operation, acetylene content in front and backstage conversion products changes greatly, especially when the catalyst runs for a long time, the stability of active components in the catalyst (the active components in the catalyst vary due to the use of different mercury-free catalysts, and generally include gold, ruthenium, copper and organic matter added in the catalyst preparation process) deteriorates, and the service life needs to be further extended by adjusting the inlet flow of the converter, the hot water temperature and flow, etc.

[0062] Raw material inlet flow regulation system (automatic) includes inlet flow regulation valve, hot water flow regulation valve, acetylene and hydrogen chloride online analysis system and converter inlet flow control program.

[0063] Inlet flow regulation valve and hot water flow regulation valve are automatic regulation valves added on converter inlet pipeline 2 and hot water upper pipeline 6, 7 respectively, and are matched with inlet flow meter and hot water flow meter.

[0064] Acetylene and hydrogen chloride online analysis system 10 includes front desk hydrogen chloride online analysis device and backstage acetylene online analysis device, which analyzes the hydrogen chloride and acetylene content in the conversion product online.

[0065] The program control method of the above hydrogen chloride and acetylene online analysis system is as follows:

[0066] S1, start button: the operator clicks the start button or program execution start operation, the DCS system automatically starts the program.

[0067] S2, according to the PLC control program, the front hydrogen chloride content test: open the corresponding electromagnetic valve in turn, in the quantitative container full of gas to be measured, complete sampling operation.

[0068] S3, start metering pump, pure water to the quantitative container, metering end point determination device display for negative, stop metering pump.

[0069] S4, the metering pump pure water flow transmission to the DCS operation system output, into the next step.

[0070] S5, according to the PLC control program, the background acetylene content test: open the corresponding electromagnetic valve in turn, so that the gas to be measured into the chromatograph, complete sampling operation.

[0071] S6, start chromatographic analysis, and the relevant test results transmission to the DCS operation system.

[0072] S7, start reset button, the program ends.

[0073] At the same time, the DCS converter inlet flow regulation interlock control program, control steps as follows:

[0074] S1, the operator presses the start button, the DCS system starts the automatic program;

[0075] S2, detection of converter inlet flow regulating valve: when the flow regulating valve valve opening ≥20%, the valve opening of regulating valve reduces 0.5%, delay a certain time T (with the catalyst type and catalyst activity change is different, about 3-5 minutes or time shorter), into the next step.

[0076] S3, hydrogen chloride, acetylene online analysis program.

[0077] S4, the current front hydrogen chloride content front hydrogen chloride content (volume ratio) ≥30%, background acetylene content ≥3.5%, the implementation of the second step; otherwise, into the next step.

[0078] S5, start reset button, the program ends.

[0079] DCS converter temperature regulation interlock control program, control steps as follows:

[0080] S1, the judgment converter bed temperature, when the bed temperature at any point temperature more than 170℃, the implementation of the second step; when the bed temperature at any point between 150℃ and 170℃, the implementation of the third step; when the bed temperature is lower than 150℃, the implementation of the fourth step;

[0081] S2, the valve opening of the converter inlet flow regulating valve is reduced by 2%, and a delay time of about 3-5 minutes or less is provided, and the first step is executed;

[0082] S3, the valve opening of the hot water supply pipeline valve is judged: if the valve opening of the thick pipeline is greater than or equal to 5%, the valve opening of the regulating valve is increased by 2%; if the valve opening of the thin pipeline is greater than or equal to 5%, the valve opening of the regulating valve is increased by 5%, and a delay time of about 3-5 minutes or less is provided, and the first step is executed;

[0083] S4, the program ends.

[0084] In different periods of mercury-free catalyst operation, the temperature regulation hot water flow and the converter inlet flow regulation process are as follows:

[0085] In the initial stage of catalyst operation, the catalytic activity is high, and the mixed gas enters the front converter, and the heat release of the catalytic reaction is more. At this time, the valve on the hot water connecting pipeline is closed, and the reaction heat is taken away in time by the hot water return pipeline.

[0086] In the middle stage of catalyst operation, the catalytic activity of the catalyst is stable, and the mixed gas inlet flow is adjusted in real time according to the values of the acetylene and hydrogen chloride online analysis system of the thick vinyl chloride gas pipeline of the converter.

[0087] In the later stage of catalyst operation, when the catalytic activity is low, the steam ejector and the pressure pump of the hot water supply pipeline are opened, the temperature and pressure of the temperature regulation control system of the hot water circulation heat exchange system are increased, so as to increase the bed temperature of the reaction; at the same time, the acetylene and hydrogen chloride online analysis system is used to analyze the content of hydrogen chloride and acetylene in the conversion product every hour, when the content of hydrogen chloride and acetylene is high, the converter inlet flow regulation interlock control program is executed, the catalytic activity of the catalyst is fully utilized, and the catalytic efficiency of the catalyst is maximized.

[0088] The present application can flexibly adjust the inlet flow of the converter according to different mercury-free catalyst performance and process characteristics; at the same time, according to different stages of mercury-free catalyst operation, the temperature, pressure and circulation of the hot water circulation system are adjusted to improve the bed temperature of the converter and the catalytic efficiency of the mercury-free catalyst; in the later stage of catalyst operation, the inlet flow of the converter can be adjusted in real time according to the online analysis values of acetylene and hydrogen chloride, so as to maximize the service life of the catalyst.

[0089] Example 1:

[0090] When the catalyst is a ruthenium-based catalyst, the generated condensed acid can be discharged to the condensed acid tank 3 in time when the catalyst is activated, so as to avoid corrosion of the generated condensed acid to the conversion equipment and pipeline. When the raw gas is inlet, the gas distributor ( Figure 2) to ensure uniform distribution of the mixture in the front converter 1-1. In the initial stage of catalyst operation, the catalytic activity is high, and after the mixture enters the front converter 1-1, the catalytic reaction releases a large amount of heat. At this time, the one-way valve 27 on the hot water connection pipeline 9 is closed, and the DN100 hot water return pipeline 7, 8 is used to remove the reaction heat in time. In the middle stage of catalyst operation, the catalytic activity of the catalyst is stable, and the mixture inlet flow is adjusted in real time according to the values of acetylene and hydrogen chloride online monitoring 10 in the crude vinyl chloride outlet pipeline; when the bed temperature is higher than the set value, the temperature adjustment interlock control program is executed; the hot water circulation amount changes automatically between the hot water pipeline one 6 and the hot water pipeline two 7 with the change of the bed temperature. In the later stage of catalyst operation, when the catalytic activity is low (low catalytic activity refers to the late stage of catalyst use, the reaction temperature of the converter is low, and the content of acetylene and hydrogen chloride in the conversion product is high, and there is no significant improvement by reducing the conversion mixture inlet flow), the steam ejector and the pressure pump of the hot water pipeline one 6 and the hot water pipeline two 7 are opened, the temperature and pressure of the hot water circulation heat exchange system are increased, and the reaction bed temperature is increased. At the same time, the online analysis system 10 of acetylene and hydrogen chloride is used to analyze the content of hydrogen chloride and acetylene in the conversion product every hour, and when the content of hydrogen chloride and acetylene is high, the converter flow regulation interlock control program is executed, and the catalytic activity of the catalyst is fully utilized, and the catalytic efficiency of the catalyst is maximized.

[0091] When the online analysis of the conversion product shows that the front hydrogen chloride content is ≥25%~30% and the back acetylene content is ≥3.5%~4.5%, the interlock adjusts the converter inlet flow.

[0092] When the converter bed temperature is ≥150℃~160℃, the hot water valve is interlocked; when the converter bed temperature is ≥170℃, the converter inlet flow is interlocked 40~60Nm 3 / h.

[0093] Implementation case 2:

[0094] When the catalyst is a gold-based catalyst, the generated condensed acid can be discharged to the condensed acid tank 3 in time during catalyst activation, avoiding corrosion of the conversion equipment and pipelines by the generated condensed acid. When the raw material gas is inlet, the gas distributor ( Figure 2) to ensure the uniform distribution of the mixture in the front converter 1-1. In the initial stage of the catalyst operation, the catalytic activity is high, and after the mixture enters the converter 1-1, the catalytic reaction releases a large amount of heat. At this time, the valve on the hot water connecting pipeline 9 is closed, and the DN80 hot water upper return pipeline 7, 8 is used to timely remove the reaction heat. In the middle stage of the catalyst operation, the catalytic activity of the catalyst is stable, and the mixture intake is adjusted in real time according to the values of the online monitoring 10 of acetylene and hydrogen chloride in the crude vinyl chloride outlet pipeline; the hot water circulation amount changes automatically between the hot water upper pipeline 6 and the hot water upper pipeline 7 with the change of the bed temperature. In the late stage of the catalyst operation, when the catalytic activity is low, the steam ejector and the pressurizing pump of the hot water upper pipeline 6, 7 are opened to increase the temperature and pressure of the hot water circulation and heat exchange system, and the connecting valve on the hot water connecting pipeline 9 is opened to increase the bed temperature. At the same time, the online monitoring system 10 of acetylene and hydrogen chloride in the conversion product is used to analyze the content of hydrogen chloride and acetylene every hour, and when the content of hydrogen chloride and acetylene is high, the converter flow adjustment interlock control program is executed to fully exert the catalytic activity of the catalyst and maximize the catalytic efficiency of the catalyst.

[0095] When the front hydrogen chloride content of the conversion product analyzed online is ≥25% to 30% and the back acetylene content is ≥3.5% to 4.5%, the interlock adjusts the converter intake flow; the set intake flow adjustment is ≤20 to 30 Nm 3 / h, and the interval between adjacent two automatic adjustments is ≥24 to 36 h.

[0096] When the bed temperature of the converter is ≥150 to 170℃, the interlock adjusts the hot water upper valve, and when the bed temperature of the converter is ≥170℃, the interlock adjusts the converter intake, and the converter flow adjustment interlock program is executed.

Claims

1. An apparatus for the mercury-free catalyst-based production of vinyl chloride, comprising a condensing acid separation system, a conversion system, and a thermal circulation system, characterized in that: The front and back converters in the conversion system are respectively equipped with gas distributors. The condensate liquid pipeline connected to the converter is connected to the condensate tank in the condensate separation system. The inlet pipeline of the converter is equipped with an inlet flow regulation system. The shell side of the converter is connected to the temperature control system. The crude vinyl chloride outlet pipeline connected to the top of the converter is equipped with an online analysis system and a converter interlock control system. The converter interlock control system includes converter intake flow regulation interlock control and converter temperature regulation interlock control; the temperature regulation system includes two hot water supply pipelines and one hot water return pipeline. One end of each of the two hot water supply pipelines is connected to the hot water pump outlet, and the other end is connected to the converter shell side; a steam ejector and a hot water booster pump are installed on the hot water supply pipeline. The online analysis system includes a gas sampling tube, an inlet solenoid valve, a metering container, an outlet solenoid valve, a metering pump, a pure water tank, a chromatograph, a metering endpoint determination device, a waste gas absorption device, a waste liquid recovery device, a PLC control unit, and a DCS operating system. The crude ethylene chloride outlet pipeline of the front-end converter is connected to the first sampling pipe of the gas to be tested. The first sampling pipe is connected to the metering container through the first inlet solenoid valve. The top of the metering container is connected to the waste gas absorption device through the first outlet solenoid valve, the top is connected to the metering endpoint determination device, the left side is connected to the metering pump, the inlet of the metering pump is connected to the pure water tank, and the bottom of the metering container is connected to the waste liquid recovery device through the second outlet solenoid valve. The crude vinyl chloride outlet pipeline of the back-end converter is connected to the second sampling conduit to be tested. The second sampling conduit to be tested is connected to the chromatograph through the second inlet solenoid valve. The chromatograph terminal is connected to the waste gas absorption device. The PLC control unit sets the logic control program for the metering pump, chromatograph, and solenoid valve; the DCS operating system outputs the hydrogen chloride content in the front end and the acetylene content in the back end, and has online analysis start and stop buttons; The production method of the mercury-free catalyst-based vinyl chloride production apparatus is carried out according to the following steps: During catalyst activation, the generated condensed acid should be promptly discharged into the condensed acid tank to prevent the condensed acid from corroding the conversion equipment and pipelines; When the raw gas is introduced, it is introduced from the bottom, and the gas distributor is used to ensure that the mixed gas is evenly distributed in the pre-converter. In the early stage of catalyst operation, the catalytic activity is high. After the mixed gas enters the front-end converter, the catalytic reaction releases a lot of heat. At this time, the valve on the hot water connection pipeline is closed, and the hot water return pipeline is used to remove the heat of reaction in time. During the middle stage of catalyst operation, the catalyst catalytic activity is stable, and the mixed gas intake is adjusted in real time according to the values ​​of the online analysis system of acetylene and hydrogen chloride in the crude vinyl chloride outlet pipeline. In the later stages of catalyst operation, when the catalytic activity is low, the steam ejector and pressurization pump of the hot water supply pipeline are turned on to increase the temperature and pressure of the hot water circulation heat exchange system, thereby increasing the temperature of the reaction bed. At the same time, the acetylene and hydrogen chloride online monitoring system is used to analyze the hydrogen chloride and acetylene content in the conversion products every hour. When the hydrogen chloride and acetylene content is high, the converter inlet air flow regulation interlock control program is executed to fully exert the catalyst catalytic activity and maximize the catalyst catalytic efficiency.

2. The apparatus for producing vinyl chloride using a mercury-free catalyst according to claim 1, characterized in that: The intake flow regulation system includes an intake flow regulating valve and an intake flow meter, which are installed on the converter intake line, respectively.

3. A method for producing vinyl chloride using a mercury-free catalyst as described in claim 2, comprising the following steps: During catalyst activation, the generated condensed acid should be promptly discharged into the condensed acid tank to prevent the condensed acid from corroding the conversion equipment and pipelines; When the raw gas is introduced, it is introduced from the bottom, and the gas distributor is used to ensure that the mixed gas is evenly distributed in the pre-converter. In the early stage of catalyst operation, the catalytic activity is high. After the mixed gas enters the front-end converter, the catalytic reaction releases a lot of heat. At this time, the valve on the hot water connection pipeline is closed, and the hot water return pipeline is used to remove the heat of reaction in time. During the middle stage of catalyst operation, the catalyst catalytic activity is stable, and the mixed gas intake is adjusted in real time according to the values ​​of the online analysis system of acetylene and hydrogen chloride in the crude vinyl chloride outlet pipeline. In the later stages of catalyst operation, when the catalytic activity is low, the steam ejector and pressurization pump of the hot water supply pipeline are turned on to increase the temperature and pressure of the hot water circulation heat exchange system, thereby increasing the temperature of the reaction bed. At the same time, the acetylene and hydrogen chloride online monitoring system is used to analyze the hydrogen chloride and acetylene content in the conversion products every hour. When the hydrogen chloride and acetylene content is high, the converter inlet air flow regulation interlock control program is executed to fully exert the catalyst catalytic activity and maximize the catalyst catalytic efficiency.

4. The production method of the apparatus for producing vinyl chloride using a mercury-free catalyst according to claim 3, characterized in that: In the converter temperature regulation interlock control system, when the converter bed temperature is between 150℃ and 170℃, the hot water supply valve is interlocked and adjusted; ② when the converter bed temperature is ≥170℃, the converter air intake is interlocked and adjusted; In the converter flow rate regulation interlock control system, when the hydrogen chloride content in the front end of the online analysis of the conversion product is ≥25%~30% and the acetylene content in the back end is ≥3.5%~4.5%, the converter air intake flow rate is interlocked and adjusted.

5. The production method of the apparatus for producing vinyl chloride using a mercury-free catalyst according to claim 3, characterized in that: When ruthenium-based catalysts are used for activation, the generated condensed acid is promptly discharged to the condensed acid tank to prevent corrosion of the conversion equipment and pipelines. The feed gas is introduced from the bottom, and a gas distributor ensures uniform distribution of the mixed gas within the front-end converter. In the initial stage of catalyst operation, the catalytic activity is high, and the catalytic reaction releases a significant amount of heat after the mixed gas enters the front-end converter. At this time, the valves on the hot water connection pipeline are closed, and the hot water supply and return pipelines are used to promptly remove the heat of reaction. During the middle stage of catalyst operation, the catalytic activity stabilizes, and the mixed gas intake is adjusted in real time based on the online monitoring values ​​of acetylene and hydrogen chloride on the crude vinyl chloride outlet pipeline. When the reaction bed temperature exceeds the set value by 150–170°C, the temperature regulation interlock control program is executed, and the front and back-end converters operate in series, with the mixed gas being transferred from the front-end converter to the back-end converter. The gas enters through the inlet pipeline of the catalyst. After crude vinyl chloride is produced in the front-end reaction, it is transported to the back-end converter for further reaction. The vinyl chloride produced in the back-end converter is qualified vinyl chloride. The hot water circulation rate changes automatically between the two water supply pipelines according to the bed temperature. In the later stage of catalyst operation, when the catalytic activity is low, the steam ejector and pressurization pump on the hot water supply pipeline are turned on to increase the temperature and pressure of the hot water circulation heat exchange system, thereby increasing the reaction bed temperature. At the same time, the acetylene and hydrogen chloride online monitoring system analyzes the hydrogen chloride and acetylene content in the conversion products every hour. When the hydrogen chloride and acetylene content is high: the hydrogen chloride content in the front-end is ≥30% and the acetylene content in the back-end is ≥3.5%, the converter flow regulation interlock control program is executed to give full play to the catalytic activity of the catalyst and maximize the catalytic efficiency.

6. The production method of the apparatus for producing vinyl chloride using a mercury-free catalyst according to claim 3, characterized in that: When using a gold-based catalyst for activation, the generated condensed acid should be promptly discharged to the condensed acid tank to prevent corrosion of the conversion equipment and pipelines. The feed gas should be introduced from the bottom, and a gas distributor should be used to ensure uniform distribution of the mixed gas within the front-end converter. In the initial stage of catalyst operation, the catalytic activity is high, and the catalytic reaction releases a significant amount of heat after the mixed gas enters the front-end converter. At this time, the valve on the hot water connection pipeline should be closed, and the hot water supply and return pipelines should be used to promptly remove the heat of reaction. In the middle stage of catalyst operation, the catalytic activity is stable, and the mixed gas intake rate is adjusted in real time based on the online monitoring values ​​of acetylene and hydrogen chloride on the crude vinyl chloride outlet pipeline. When the reaction bed temperature is ≤170℃ above the set value, [following the instructions]... Temperature regulation interlock control program; hot water circulation volume changes automatically switch between two water supply lines as bed temperature changes; in the later stage of catalyst operation, when catalytic activity is low, the steam ejector and booster pump on the hot water supply line are turned on to increase the temperature and pressure of the hot water circulation heat exchange system, and the connecting valve on the hot water connecting line is opened to increase the reaction bed temperature; at the same time, the acetylene and hydrogen chloride online monitoring system analyzes the hydrogen chloride and acetylene content in the conversion products hourly. When the hydrogen chloride and acetylene content is high: the hydrogen chloride content at the front end is ≥30% and the acetylene content at the back end is ≥3.5%, the converter flow regulation interlock control program is executed to fully utilize the catalyst catalytic activity and maximize the catalyst catalytic efficiency.

7. The production method of the apparatus for producing vinyl chloride using a mercury-free catalyst according to claim 3, characterized in that: Control methods for online analysis systems: S1. Start button: After the operator clicks the start button or the program executes the start operation, the DCS system will automatically start the program. S2. According to the PLC control program, perform the front-end hydrogen chloride content test: open the corresponding solenoid valves in sequence, fill the quantitative container with the gas to be tested, and complete the sampling operation. S3. Start the metering pump to deliver pure water to the metering container. When the metering endpoint determination device displays a negative value, stop the metering pump. S4. Transmit the pure water flow rate delivered by the metering pump to the DCS operating system output, and proceed to the next step; S5. Perform background acetylene content testing according to the PLC control program: open the corresponding solenoid valves in sequence to allow the gas to be tested to enter the chromatograph and complete the sampling operation. S6. Start the chromatographic analysis and transmit the relevant test results to the DCS operating system; S7. Press the reset button to end the program.

8. The production method of the apparatus for producing vinyl chloride using a mercury-free catalyst according to claim 3, characterized in that: The DCS is configured with a converter flow regulation interlock control program, and the control steps are as follows: S1. The operator presses the start button, and the DCS system starts the automatic program. S2. Detect the converter intake flow control valve: When the intake flow control valve opening is ≥20%, the intake flow control valve opening is reduced by 0.5%, and after a certain time T, proceed to the next step; S3. Perform online analysis procedures for hydrogen chloride and acetylene; S4. If the current hydrogen chloride content is ≥ M and the background acetylene content is ≥ N, proceed to step 2; otherwise, proceed to the next step. S5. Press the reset button to end the program.

9. The production method of the apparatus for producing vinyl chloride using a mercury-free catalyst according to claim 3, characterized in that: The DCS is configured with a converter temperature regulation interlock control program, and the control steps are as follows: S1. Determine the converter bed temperature. If the temperature at any point in the bed exceeds H1, proceed to step 2. If the temperature at any point in the bed is between H2 and H1, proceed to step 3. If the bed temperature is below H2, proceed to step 4. S2. Reduce the valve opening of the converter intake flow regulating valve by 2%, delay for a certain time T, and then execute step 1. S3. Determine the opening degree of the large and small hot water supply pipe valves: If the opening degree of the large pipe valve is ≥5%, increase the opening degree of the air inlet flow regulating valve by 2%; if the opening degree of the small pipe valve is ≥5%, increase the opening degree of the air inlet flow regulating valve by 5%, delay for a certain time T, and then execute step 1. S4, Program ends.

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