Sequential control system for decoking ethylene tar product

Abstract

The utility model belongs to the field of chemical engineering, and relates to a sequence control system for decoking ethylene tar products. The system comprises a filter and a purifier, the bottom outlet of the filter is provided with a stop valve A and a nitrogen discharge line on the bottom outlet line of the filter; the upper part of the purifier is provided with a purifier upper inlet and a flushing oil recovery line, the top of the purifier is provided with a purifier top nitrogen discharge line, the lower part of the purifier is provided with a flushing line, a steam purging line, a nitrogen purging line and a residual tar discharge line, and the bottom of the purifier is provided with a knife valve B; an outlet of the stop valve A is connected with an upper inlet of the purifier; and stop valves C, D, E, F, G, H1 and H2 are respectively arranged on the residual tar discharge line, the flushing line, the steam purging line, the nitrogen purging line, the flushing oil recovery line, the nitrogen discharge line on the top of the purifier and the nitrogen discharge line on the outlet line at the bottom of the filter. According to the utility model, by adopting sequential control, the ethylene tar decoking labor intensity can be effectively reduced, and meanwhile, the removed coke particles are clean, environment-friendly and convenient to use.

Description

Technical Field

[0001] The utility model belongs to the field of chemical industry, and in particular relates to a sequential control system for cleaning ethylene tar products. Background Art

[0002] Ethylene tar is a heavy oil byproduct generated by high-temperature cracking of liquid raw materials such as cracking tail oil, diesel or naphtha during the ethylene production process. Its composition is very complex. Since ethylene tar products have high aromatics, colloids, asphaltene and residual carbon content, it is very easy to cause blockage of related equipment and transportation difficulties. It is one of the operational difficulties in the partial shutdown of ethylene plants due to blockage.

[0003] To prevent clogging in the ethylene tar system, two methods are currently used in ethylene plants. On the one hand, ordinary basket filters are installed in the ethylene tar product system to filter and remove solid particles. However, due to the composition characteristics of ethylene tar, the filter needs to be cleaned frequently and with high intensity, making on-site operation difficult. On the other hand, the equipment, instruments and pipelines in the ethylene tar product system are usually heated by steam or electricity. However, steam heating and electric heating also have their own shortcomings. Steam heating has the phenomenon of uneven heating, which can easily cause local coking of the pipeline due to overheating. Although electric heating has advantages in temperature control, its manufacturing cost is relatively high. Utility Model Content

[0004] In order to solve the technical problems of high frequency and high intensity of coke cleaning of ethylene tar in the prior art, the utility model provides a sequential control system for coke cleaning of ethylene tar products.

[0005] In order to achieve the above-mentioned object, the utility model provides a sequential control system for cleaning ethylene tar products, the system comprising: a filter and a purifier;

[0006] A filter screen is arranged around the inner part of the upper part of the filter, an ethylene tar product feed line is arranged on one side of the upper part, an ethylene tar product discharge line after the coke particles are removed is arranged on the other side, and a filter bottom outlet is arranged at the bottom, the ethylene tar product feed line is located higher than the filter screen, and the ethylene tar product discharge line after the coke particles are removed is located at the filter screen; a cut-off valve A and a nitrogen discharge line on the filter bottom outlet line are arranged at the filter bottom outlet;

[0007] The upper part of the purifier is provided with an upper inlet of the purifier and a flushing oil recovery line, the top part is provided with a nitrogen discharge line of the purifier top, the lower part is provided with a flushing line, a steam purge line, a nitrogen purge line and a residual tar discharge line, and the bottom part is provided with a knife valve B; a purifier filter is provided around the inner part of the lower part, and the residual tar discharge line is located at the purifier filter;

[0008] The outlet of cut-off valve A is connected to the upper inlet of the purifier;

[0009] The residual tar discharge line, flushing line, steam purge line, nitrogen purge line, flushing oil recovery line, nitrogen discharge line at the top of the purifier and the nitrogen discharge line at the bottom outlet of the filter are respectively provided with cut-off valves C, D, E, F, G, H1 and H2.

[0010] Preferably, the cut-off valve A, the cut-off valve D, the cut-off valve E, the cut-off valve F and the knife valve B are provided with a limit safety interlock.

[0011] Preferably, the shut-off valve D and the shut-off valve H2 are provided with a limit safety interlock.

[0012] Preferably, the cut-off valve A, knife valve B, cut-off valve C, cut-off valve D, cut-off valve E, cut-off valve F, cut-off valve G, cut-off valve H1 and cut-off valve H2 are each independently an electric valve or a pneumatic valve to realize automatic sequential control of decoking.

[0013] Preferably, shut-off valves are also provided on the ethylene tar product feed line and on the ethylene tar product discharge line after the coke particles are removed, and the two shut-off valves are independently electric valves or pneumatic valves.

[0014] Preferably, the upper portion of the filter adopts a cylindrical structure, the lower portion adopts a conical structure, and the filter screen is an annular filter screen.

[0015] Preferably, the upper portion of the purifier adopts a cylindrical structure, the lower portion adopts a conical structure, and the purifier filter is a conical filter.

[0016] Preferably, a filter is provided at the pipe opening of the flushing oil recovery line.

[0017] Preferably, the upper inlet of the purifier is located at the top head, and the bottom outlet of the filter, the cut-off valve A and the upper inlet of the purifier are directly connected in sequence through flanges.

[0018] Preferably, the system further comprises: an inclined pipe, wherein the inclined pipe connects the cut-off valve A and the upper inlet of the purifier.

[0019] Preferably, the slope of the inclined tube is 1 / 100-50 / 100, preferably 5 / 100-20 / 100.

[0020] In the present invention, slope=height difference / horizontal distance.

[0021] Preferably, the length of the inclined tube is 1-50 m, preferably 1-5 m.

[0022] The utility model can effectively reduce the labor intensity of ethylene tar decoking by adopting sequence control, and the removed coke particles are clean, environmentally friendly and convenient to use.

[0023] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present invention.

[0025] Figure 1 A schematic diagram of a sequential control system for decoking ethylene tar products in one embodiment of the utility model is shown.

[0026] Figure 2 A schematic diagram of a sequential control system for decoking ethylene tar products in another embodiment of the utility model is shown.

[0027] Description of reference numerals:

[0028] 1-filter; 2-purifier; 3-inclined tube; B-knife valve; A / C / D / E / F / G / H1 / H2-cut-off valve. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein.

[0030] In order to achieve the above-mentioned purpose, the utility model provides a sequential control system for cleaning ethylene tar products, such as Figure 1 As shown, the system comprises: a filter 1, a purifier 2 and an inclined tube 3;

[0031] A filter screen is arranged around the inner part of the upper part of the filter 1, an ethylene tar product feed line is arranged on one side of the upper part, an ethylene tar product discharge line after the coke particles are removed is arranged on the other side, and a filter bottom outlet is arranged at the bottom, the ethylene tar product feed line is located higher than the filter screen, and the ethylene tar product discharge line after the coke particles are removed is located at the filter screen; a cut-off valve A and a nitrogen discharge line on the filter bottom outlet line are arranged at the filter bottom outlet;

[0032] The upper part of the purifier 2 is provided with a purifier upper inlet and a flushing oil recovery line, the top is provided with a purifier top nitrogen discharge line, the lower part is provided with a flushing line, a steam purge line, a nitrogen purge line and a residual tar discharge line, and the bottom is provided with a knife valve B; a purifier filter is provided around the inner part of the lower part, and the residual tar discharge line is located at the purifier filter;

[0033] The inclined pipe connects the cut-off valve A and the upper inlet of the purifier;

[0034] The residual tar discharge line, flushing line, steam purge line, nitrogen purge line, flushing oil recovery line, nitrogen discharge line at the top of the purifier and the nitrogen discharge line at the bottom outlet of the filter are respectively provided with cut-off valves C, D, E, F, G, H1 and H2.

[0035] The utility model comprises: a filter 1 for primary separation of coke particles in ethylene tar; a purifier 2 for secondary separation of coke particles in ethylene tar; a cut-off valve A for isolating the filter and the purifier; a knife valve B for controlling the discharge of solid particles at the bottom of the purifier; a cut-off valve C for controlling the recovery of residual tar; a cut-off valve D for controlling flushing oil; a cut-off valve E for controlling steam purge; a cut-off valve F for controlling nitrogen drying and replacement; a cut-off valve G for controlling the recovery of flushing oil; and cut-off valves H1 and H2 for controlling nitrogen exhaust gas.

[0036] Preferably, the cut-off valve A, the cut-off valve D, the cut-off valve E, the cut-off valve F and the knife valve B are provided with a limit safety interlock so as not to be opened at the same time.

[0037] Preferably, the shut-off valve D and the shut-off valve H2 are provided with a limit safety interlock so as not to be opened at the same time.

[0038] Preferably, the cut-off valve A, knife valve B, cut-off valve C, cut-off valve D, cut-off valve E, cut-off valve F, cut-off valve G, cut-off valve H1 and cut-off valve H2 are each independently an electric valve or a pneumatic valve to realize automatic sequential control of decoking.

[0039] Preferably, shut-off valves are also provided on the ethylene tar product feed line and on the ethylene tar product discharge line after the coke particles are removed, and the two shut-off valves are independently electric valves or pneumatic valves.

[0040] Preferably, the filter 1 has a cylindrical structure at the top and a conical structure at the bottom, and the filter screen is an annular filter screen.

[0041] Preferably, the upper portion of the purifier 2 adopts a cylindrical structure, the lower portion adopts a conical structure, and the purifier filter is a conical filter.

[0042] Preferably, a filter is provided at the pipe opening of the flushing oil recovery line.

[0043] Preferably, the slope of the inclined tube is 1 / 100-50 / 100, preferably 5 / 100-20 / 100.

[0044] In the present invention, slope=height difference / horizontal distance.

[0045] Preferably, the length of the inclined tube is 1-50 m, preferably 1-5 m.

[0046] The utility model provides another sequential control system for cleaning ethylene tar products, such as Figure 2 As shown, the difference from the sequential control system for decoking the first ethylene tar product is that the inclined pipe is not included.

[0047] Preferably, the upper inlet of the purifier is located at the top head, and the bottom outlet of the filter, the cut-off valve A and the upper inlet of the purifier are directly connected in sequence through flanges.

[0048] The sequential control methods of the sequential control systems for ethylene tar product decoking provided by the two embodiments of the utility model are the same, and include the following steps:

[0049] S1: During normal operation, shut-off valves A and C are open, and the remaining shut-off valves are closed;

[0050] S2: When coke cleaning begins, close the cut-off valve A, open the cut-off valves C and D, recover the residual tar to the system, and at the same time open the cut-off valve F appropriately to prevent negative pressure in the purifier;

[0051] S3: Close the cut-off valves C and F, open the cut-off valve D, and soak with flushing oil for 10-90 minutes;

[0052] S4: Close the cut-off valve D, open the cut-off valve C, recover the flushing oil to the system, and moderately open the cut-off valve F;

[0053] S5: Close the cut-off valves G and F, open the cut-off valves E and G, purge with steam, and return the exhaust gas to the system;

[0054] S6: Close the cut-off valves E and G, open the cut-off valves F and H1, dry with nitrogen for 10-90 minutes, and discharge the gas to the flare;

[0055] S7: Close the cut-off valves F and H1, prepare the container for receiving the coke particles, and open the knife valve B to discharge the coke;

[0056] S8: After the coke discharge is completed, close the knife valve B, open the cut-off valve F and H2, replace with nitrogen for 10-30 minutes, and discharge the gas to the flare;

[0057] S9: Close the shut-off valves F and H2, open the shut-off valve D, and fill with flushing oil;

[0058] S10: Close the shut-off valve D, slowly open the shut-off valve A, and prepare to put the purifier into use.

[0059] Example 1

[0060] The ethylene tar product from the ethylene plant is about 100 t / hr, of which the coke content is about 1000 ppm wt. The ethylene tar product is fed from one side of the upper part of the filter 1. After primary filtration, the ethylene tar product after removing the coke is discharged from the other side of the upper part of the filter 1 and sent to the downstream product pump. The tar rich in coke is discharged from the bottom of the filter 1 and enters the purifier 2 for secondary filtration, and the coke is finally separated at the bottom of the purifier 2.

[0061] A cut-off valve A for isolation is provided between filter 1 and purifier 2, a knife valve B for coke cleaning is provided at the bottom of purifier 2, and purifier 2 is also provided with a cut-off valve C for recovering residual tar, a flushing oil feed cut-off valve D, a steam purge cut-off valve E, a nitrogen drying and replacement cut-off valve F, a flushing oil recovery cut-off valve G, and nitrogen exhaust gas cut-off valves H1 and H2. The above cut-off valves are used for sequential control coke cleaning of ethylene tar, and the coke cleaning steps are shown in Table 1.

[0062] Table 1 Ethylene tar product decoking sequence steps

[0063]

[0064]

[0065] The flow rate and coke concentration of ethylene tar product before and after treatment are shown in Table 2.

[0066] Table 2 Comparison of process parameters before and after treatment of ethylene tar products

[0067]

[0068] Note 1: Considering that some coke particles are suspended on the filter, about 0.3 kg / hr.

[0069] The various embodiments of the utility model have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A sequential control system for cleaning ethylene tar products, characterized in that: The system comprises: a filter (1) and a purifier (2); The filter (1) is provided with a filter screen around the inner part of the upper part, an ethylene tar product feed line is provided on one side of the upper part, an ethylene tar product discharge line after the coke particles are removed is provided on the other side, and a filter bottom outlet is provided at the bottom, the ethylene tar product feed line is located higher than the filter screen, and the ethylene tar product discharge line after the coke particles are removed is located at the filter screen; the filter bottom outlet is provided with a cut-off valve A and a nitrogen discharge line on the filter bottom outlet line; The purifier (2) is provided with an upper purifier inlet and a flushing oil recovery line at the top, a purifier top nitrogen discharge line at the top, a flushing line, a steam purge line, a nitrogen purge line and a residual tar discharge line at the bottom, and a knife valve B at the bottom; a purifier filter is provided around the inner part of the lower part, and the residual tar discharge line is located at the purifier filter; The outlet of cut-off valve A is connected to the upper inlet of the purifier; The residual tar discharge line, flushing line, steam purge line, nitrogen purge line, flushing oil recovery line, nitrogen discharge line at the top of the purifier and the nitrogen discharge line at the bottom outlet of the filter are respectively provided with cut-off valves C, D, E, F, G, H1 and H2.

2. The sequential control system for decoking ethylene tar products according to claim 1, characterized in that: The cut-off valve A, cut-off valve D, cut-off valve E, cut-off valve F and knife valve B are provided with limit safety interlocks.

3. The sequential control system for decoking ethylene tar products according to claim 1, characterized in that: The cut-off valve D and the cut-off valve H2 are provided with limit safety interlock.

4. The sequential control system for decoking ethylene tar products according to claim 1, characterized in that: The cut-off valve A, the knife valve B, the cut-off valve C, the cut-off valve D, the cut-off valve E, the cut-off valve F, the cut-off valve G, the cut-off valve H1 and the cut-off valve H2 are each independently an electric valve or a pneumatic valve.

5. The sequential control system for decoking ethylene tar products according to any one of claims 1 to 4, characterized in that: Shut-off valves are also provided on the ethylene tar product feed line and on the ethylene tar product discharge line after the coke particles are removed. The two shut-off valves are independently electric valves or pneumatic valves.

6. The sequential control system for decoking ethylene tar products according to any one of claims 1 to 4, characterized in that: The filter (1) has a cylindrical structure at the top and a conical structure at the bottom, and the filter screen is an annular filter screen.

7. The sequential control system for decoking ethylene tar products according to any one of claims 1 to 4, characterized in that: The purifier (2) has a cylindrical structure at the top and a conical structure at the bottom, and the purifier filter is a conical filter.

8. The sequential control system for decoking ethylene tar products according to any one of claims 1 to 4, characterized in that: A filter screen is arranged at the pipe opening of the flushing oil recovery line.

9. The sequential control system for decoking ethylene tar products according to any one of claims 1 to 4, characterized in that: The upper inlet of the purifier is located at the top head, and the bottom outlet of the filter, the cut-off valve A and the upper inlet of the purifier are directly connected in sequence through flanges.

10. The sequential control system for decoking ethylene tar products according to any one of claims 1 to 4, characterized in that: The system further comprises: an inclined pipe, the inclined pipe connecting the cut-off valve A and the upper inlet of the purifier; The slope of the inclined pipe is 1 / 100-50 / 100; The length of the inclined tube is 1-50m.

11. The sequential control system for decoking ethylene tar products according to claim 10, characterized in that: The slope of the inclined pipe is 5 / 100-20 / 100.

12. The sequential control system for decoking ethylene tar products according to claim 10, characterized in that: The length of the inclined tube is 1-5m.

Images