System for replacing oxygen pipeline of gasification furnace by adopting medium-pressure superheated steam

Abstract

The utility model discloses a system for replacing an oxygen pipeline of a gasification furnace by adopting medium-pressure superheated steam, which is characterized in that a pulverized coal pipeline and the oxygen pipeline are both connected to a gas inlet of a coal burner of the gasification furnace, a high-pressure nitrogen pipeline is connected to the oxygen pipeline, and the oxygen pipeline is connected to the coal burner of the gasification furnace through an oxygen-steam mixer; a first feeding port of the oxygen and steam mixer is connected with an oxygen pipeline and a high-pressure nitrogen pipeline, a second feeding port of the oxygen and steam mixer is connected with a medium-pressure superheated steam pipeline, and the medium-pressure superheated steam pipeline is sequentially provided with a hand valve, a steam filter, a second adjusting valve and a fifth switch valve in the material flowing direction. And a discharge hole of the oxygen-steam mixer is connected to a gas inlet of the coal burner through a replacement section oxygen pipeline. The medium-pressure superheated steam system is used for replacing a high-pressure nitrogen system to replace the oxygen pipeline of the gasification furnace, so that the fluctuation of nitrogen can be reduced, the safety of the replacement pipeline is ensured, and the content of nitrogen in crude synthesis gas can be obviously reduced.

Description

Technical Field

[0001] The utility model relates to a medium-pressure superheated steam system, and more specifically to a system which adopts medium-pressure superheated steam to replace the oxygen pipeline of a gasifier. Background Art

[0002] The Shell coal gasification process is carried out under high temperature and pressure conditions. Coal powder, oxygen and a small amount of steam flow into the gasifier under pressure and complete a series of physical and chemical processes such as heating, volatile matter removal, cracking, combustion and conversion in a very short time. Because 99.6% pure, 4.6MPa oxygen is a combustion-supporting gas, high-pressure nitrogen must be used to safely replace the inside of the oxygen pipeline before the gasifier pulverized coal burner is put into use and after it is ejected. The patent with publication number CN204420567U describes in the high-pressure nitrogen system for purging the oxygen pipeline of the gasification system that the existing gasification system oxygen pipeline replacement is to connect a nitrogen compressor between the liquid nitrogen storage tank and the high-pressure nitrogen storage tank. The nitrogen compressor is easy to bring oil into the nitrogen storage tank during operation. In the process of using high-pressure nitrogen to replace the oxygen pipeline, the oxygen pipeline is polluted. The compressed oxygen in the oxygen pipeline contacts with the oil brought in, which will cause violent combustion and cause explosion, posing a safety hazard. The patent uses a liquid nitrogen pump to increase the pressure and uses an air-temperature vaporizer to convert liquid nitrogen into nitrogen to provide a gas source for the high-pressure nitrogen system, avoid oil from being brought into the oxygen pipeline, and eliminate safety hazards. Although this method may avoid safety hazards, it still has the problem of easily causing an increase in the nitrogen content in the crude synthesis gas produced by the gasifier. If the quality of the synthesis gas decreases, it will lead to an increase in the venting amount of the methanol and 1,1-decyl alcohol branch reaction system, and the amount of reaction raw gas taken away will also increase accordingly, directly affecting the unit consumption indicators of methanol and 1,1-decyl alcohol. The impact on the synthetic ammonia liquid nitrogen washing section is that when the nitrogen content in the synthesis gas is high, the nitrogen in the synthesis gas will turn into liquid nitrogen. Since the increased nitrogen needs to absorb a large amount of cold to turn into liquid nitrogen, under the premise of a certain heat exchange area, the temperature of the synthesis gas entering the C04301 tower will inevitably rise, making the washing effect worse. The most fundamental way to solve the high nitrogen content in the synthesis gas is to maintain the stability of the nitrogen content in the raw synthesis gas produced by coal gasification. Utility Model Content

[0003] In order to overcome the deficiencies in the prior art and in view of the shortcomings of the existing high-pressure nitrogen replacement system, the utility model proposes a system that uses medium-pressure superheated steam to replace the oxygen pipeline of the gasifier. The medium-pressure superheated steam system is used instead of the high-pressure nitrogen system to replace the oxygen pipeline of the gasifier, which can not only reduce the fluctuation of nitrogen and ensure the safety of the replacement pipeline, but also significantly reduce the nitrogen content in the raw synthesis gas.

[0004] The purpose of the utility model is achieved through the following technical solutions.

[0005] The utility model adopts a system for replacing the oxygen pipeline of a gasifier with medium-pressure superheated steam, comprising a pulverized coal pipeline, an oxygen pipeline and a high-pressure nitrogen pipeline, wherein the pulverized coal pipeline and the oxygen pipeline are both connected to the air inlet of a coal burner of the gasifier, the high-pressure nitrogen pipeline is connected to the oxygen pipeline, the oxygen pipeline is connected to the coal burner of the gasifier via an oxygen steam mixer, a first feed inlet of the oxygen steam mixer is connected to the oxygen pipeline and the high-pressure nitrogen pipeline, a second feed inlet of the oxygen steam mixer is connected to a medium-pressure superheated steam pipeline, and a hand valve, a steam filter, a second regulating valve and a fifth switch valve are sequentially arranged on the medium-pressure superheated steam pipeline along the material flow direction, and a discharge port of the oxygen steam mixer is connected to the air inlet of the coal burner via a replacement section oxygen pipeline.

[0006] Furthermore, a first switch valve and a third regulating valve are provided on the pulverized coal pipeline.

[0007] Furthermore, a first regulating valve, a second switch valve, and a first check valve are sequentially arranged along the material flow direction on the oxygen pipeline.

[0008] Furthermore, the high-pressure nitrogen pipeline is divided into two branches, the first branch is provided with a third switch valve and a second check valve, the second branch is provided with a fourth switch valve and a third check valve, and the outlets of the first branch and the second branch are both connected to the oxygen pipeline section between the outlet of the first check valve and the first feed inlet of the oxygen steam mixer.

[0009] Compared with the prior art, the beneficial effects brought about by the technical solution of the utility model are:

[0010] Since medium-pressure superheated steam is a component of the gasifying agent of Shell gasifier, the utility model adopts medium-pressure superheated steam instead of high-pressure nitrogen to replace the oxygen pipeline of the replacement section, reducing the risk of oil pollution brought in by high-pressure nitrogen replacement. At the same time, it reduces the nitrogen content in the synthesis gas and improves the quality of the synthesis gas. It can not only save nitrogen, reduce the unit consumption of synthesis gas by downstream products and the impact of high nitrogen content in raw gas on downstream production equipment, but also further improve the market competitiveness of the entire chemical park. It plays a positive role in the "safe, stable, full and excellent" operation of the gasifier. In addition, after the transformation is completed, when a coal burner jumps out, the nitrogen content in the synthesis gas is reduced from 2% to about 0.5%, with obvious economic benefits, and has the value of promotion to the multi-burner gasifier industry.

[0011] The utility model adopts a superheated medium-pressure steam pipeline to replace the high-pressure nitrogen pipeline 3 to replace the remaining oxygen in the replacement section oxygen pipeline 5, which can not only improve the safety performance, but also reduce the nitrogen content in the synthesis gas produced by the gasifier, and increase the yield of downstream products such as methanol, acetic acid, butanol and other products.

[0012] Through the technical solution of the utility model, the traditional high-pressure nitrogen replacement system is changed into a medium-pressure superheated steam replacement system, which can not only reduce the nitrogen content in the synthesis gas and increase the hydrogen content in the synthesis gas, but also save the raw material cost of downstream products (methanol, acetic acid, butyl octanol), reduce the consumption of cold capacity in the synthetic ammonia liquid nitrogen washing section, and improve the safety factor of the oxygen pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The utility model is a system schematic diagram of the utility model using medium-pressure superheated steam to replace the oxygen pipeline of the gasifier.

[0014] Figure markings: 1-coal powder pipeline; 2-oxygen pipeline; 3-high-pressure nitrogen pipeline; 4-medium-pressure superheated steam pipeline; 5-displacement section oxygen pipeline; 6-first switch valve; 7-first regulating valve; 8-second switch valve; 9-third switch valve; 10-fourth switch valve; 11-fifth switch valve; 12-second regulating valve; 13-coal burner; 14-steam filter; 15-hand valve; 16-oxygen steam mixer; 17-first check valve; 18-third regulating valve, 19-second check valve, 20-third check valve. DETAILED DESCRIPTION

[0015] The utility model is further described below in conjunction with the accompanying drawings.

[0016] The utility model proposes a system that uses medium-pressure superheated steam to replace the oxygen pipeline of the gasifier, such as Figure 1 As shown, it mainly includes a pulverized coal pipeline 1, an oxygen pipeline 2, a high-pressure nitrogen pipeline 3, and a medium-pressure superheated steam pipeline 4. In actual application, the Shell gasifier has four coal burners, and each coal burner 13 is connected to a set of this pipeline.

[0017] The pulverized coal pipeline 1 is connected to the air inlet of the coal burner 13 of the gasifier, and the pulverized coal pipeline 1 is provided with a first switch valve 6 and a third regulating valve 18. The oxygen pipeline 2 is connected to the air inlet of the coal burner 13 of the gasifier through an oxygen steam mixer 16. The first feed port N1 of the oxygen steam mixer 16 is connected to the oxygen pipeline 2 and the high-pressure nitrogen pipeline 3, and the oxygen pipeline 2 is provided with a first regulating valve 7, a second switch valve 8, and a first check valve 17 in sequence along the material flow direction. The second feed port N2 of the oxygen steam mixer 16 is connected to the medium-pressure superheated steam pipeline 4, and the medium-pressure superheated steam pipeline 4 is provided with a hand valve 15, a steam filter 14, a second regulating valve 12, and a fifth switch valve 11 in sequence along the material flow direction. The discharge port N3 of the oxygen steam mixer 16 is connected to the air inlet of the coal burner 13 through the displacement section oxygen pipeline.

[0018] In the above system, the high-pressure nitrogen pipeline 3 is divided into two branches, the first branch is provided with a third switch valve 9 and a second check valve 19, the second branch is provided with a fourth switch valve 10 and a third check valve 20, and the outlets of the first branch and the second branch are both connected to the oxygen pipeline 2 section between the outlet of the first check valve 17 and the first feed port N1 of the oxygen steam mixer 16.

[0019] The medium-pressure superheated steam for replacement (substantially water vapor) enters from the inlet end of the medium-pressure superheated steam pipeline 4, and enters into the steam filter 14 through the manual valve 15. The impurities and pollutants in the steam can be effectively removed by filtering, thereby improving the quality and purity of the steam and ensuring safe and reliable replacement. The required steam flow rate is then adjusted by the second regulating valve 12, and then enters into the oxygen steam mixer 16 through the second feed port N2 after passing through the fifth switch valve 11, and enters into the replacement section oxygen pipeline 5 through the discharge port N3 of the oxygen steam mixer 16. The mixed gas after replacement is sprayed into the gasifier through the coal burner 13 as a gasifying agent for the gasifier.

[0020] The utility model uses medium-pressure superheated steam instead of high-pressure nitrogen to replace the oxygen pipeline. When the gasifier is in normal operation, all valves on the pulverized coal pipeline 1, the oxygen pipeline 2, and the medium-pressure superheated steam pipeline 4 have a certain degree of opening, and are respectively controlled by the first switch valve 6, the second switch valve 8, and the fifth switch valve 11 to feed into the coal burner 13 at the same time, forming a continuous, stable, and sustainable reaction zone of temperature gradient, velocity flow field, and material flow field in the gasifier.

[0021] When a coal burner 13 in a multi-burner gasifier jumps out due to a fault (for example, the coal burner 13 jumps out due to a coal shortage or a high oxygen-coal ratio of a single burner), the control system sequentially closes the first switch valve 6 of the pulverized coal pipeline 1 and the second switch valve 8 of the oxygen pipeline 2 respectively. To prevent the synthesis gas from flowing back to the replacement section oxygen pipeline 5, the control system sequentially opens the valve position of the second regulating valve 12 of the medium-pressure superheated steam pipeline 4 at the same time to increase the flow of medium-pressure superheated steam. The pipeline can maintain the pressure at 5.2Mp to replace the oxygen in the replacement section oxygen pipeline 5 (pressure is 4.6MP). It must be ensured that the body temperature of the jumped coal burner 13 is lower than 850℃ to protect the coal burner from being corroded by hot gas. The interlock and sequential control automatically operate the replacement valves (i.e., the second regulating valve 12 and the fifth switch valve 11) in accordance with the configuration system to ensure the replacement effect. During the protective operation of the steam system, check the status of each valve to ensure that there is no leakage.

[0022] When the medium-pressure superheated steam pressure is 5.2MP and the flow rate is not less than 0.5kg / s, the replacement time is more than 5 minutes, which is qualified, and the coal burner has the conditions for re-feeding (such as qualified oxygen pressure and qualified coal circulation). While keeping the third switch valve 9, the fourth switch valve 10, the second check valve 19, and the third check valve 20 of the high-pressure nitrogen pipeline 3 closed, the first switch valve 6 of the pulverized coal pipeline 1 and the second switch valve 8 of the oxygen pipeline 2 are opened according to the sequential control, and the interlock automatically closes the second regulating valve 12 of the medium-pressure superheated steam pipeline 4, and the coal burner 13 is put into operation again and restored to the normal start-up operation state. If the medium-pressure superheated steam replacement has abnormal problems such as condensation and valve failure, after 5 seconds, the interlock automatically starts the control valve of the high-pressure nitrogen pipeline 3 (i.e., the third switch valve 9 and the fourth switch valve 10, the second check valve 19, and the third check valve 20) for replacement to prevent the synthesis gas from flowing back to the replacement section oxygen pipeline 5, and the temperature is too high to burn the coal burner 13.

[0023] Although the utility model has been described above, the utility model is not limited to the above, which is merely illustrative and not restrictive. Under the guidance of the utility model, ordinary technicians in this field can also make many forms without departing from the utility model, all of which are protected by the utility model.

Claims

1. A system for replacing the oxygen pipeline of a gasifier using medium-pressure superheated steam, comprising a pulverized coal pipeline (1), an oxygen pipeline (2), and a high-pressure nitrogen pipeline (3), wherein the pulverized coal pipeline (1) and the oxygen pipeline (2) are both connected to the air inlet of a coal burner (13) of the gasifier, and the high-pressure nitrogen pipeline (3) is connected to the oxygen pipeline (2), characterized in that: The oxygen pipeline (2) is connected to the coal burner (13) of the gasifier via an oxygen steam mixer (16); a first feed port (N1) of the oxygen steam mixer (16) is connected to the oxygen pipeline (2) and the high-pressure nitrogen pipeline (3); a second feed port (N2) of the oxygen steam mixer (16) is connected to a medium-pressure superheated steam pipeline (4); and the medium-pressure superheated steam pipeline (4) is provided with a manual valve (15), a steam filter (14), a second regulating valve (12), and a fifth switch valve (11) in sequence along the material flow direction; and a discharge port (N3) of the oxygen steam mixer (16) is connected to the air inlet of the coal burner (13) via a displacement section oxygen pipeline (5).

2. The system for replacing the oxygen pipeline of a gasifier using medium-pressure superheated steam according to claim 1 is characterized in that: The pulverized coal pipeline (1) is provided with a first switch valve (6) and a third regulating valve (18).

3. The system for replacing the oxygen pipeline of a gasifier using medium-pressure superheated steam according to claim 1 is characterized in that: The oxygen pipeline (2) is provided with a first regulating valve (7), a second switch valve (8), and a first check valve (17) in sequence along the material flow direction.

4. The system for replacing the oxygen pipeline of a gasifier using medium-pressure superheated steam according to claim 1 is characterized in that: The high-pressure nitrogen pipeline (3) is divided into two branches, the first branch is provided with a third switch valve (9) and a second check valve (19), the second branch is provided with a fourth switch valve (10) and a third check valve (20), and the outlets of the first branch and the second branch are both connected to the section of the oxygen pipeline (2) between the outlet of the first check valve (17) and the first feed port (N1) of the oxygen steam mixer (16).

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