Pressure stabilizer of dimethyl oxalate rectification system in coal chemical industry

Abstract

The utility model belongs to the technical field of dimethyl oxalate rectification in the coal chemical industry, and particularly relates to a pressure stabilizing device of a dimethyl oxalate rectification system in the coal chemical industry. According to the utility model, the pressure stabilizing gas inlet is arranged on the tower top condenser or the tower top reflux tank of the dimethyl oxalate light component removal tower and the dimethyl carbonate separation tower which are connected in sequence, and the system pressure of the dimethyl oxalate light component removal tower or the dimethyl carbonate separation tower is regulated and controlled by supplementing nitrogen or refluxing non-condensable gas extracted by a vacuum pump, so that the pressure is stable; the rectification efficiency and the product quality are further ensured; meanwhile, the nitrogen buffer tank and the pressure-stabilized gas buffer tank are provided with pressure transmitters, and the system pressure of the dimethyl oxalate light component removal tower or the dimethyl carbonate separation tower is regulated and controlled in time by regulating the supplementing amount of nitrogen or the reflux amount of non-condensable gas through an automatic control device. The system pressure of the dimethyl oxalate light component removal tower or the dimethyl carbonate separation tower is more stable, large fluctuation is avoided, and meanwhile the operation intensity and frequency of operators are reduced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to coal chemical industry oxalic acid dimethyl ester rectification technical field, specifically, it is a kind of coal chemical industry oxalic acid dimethyl ester rectification system's pressure stabilizing device. BACKGROUND

[0002] In coal chemical production, oxalic acid dimethyl ester is the intermediate product in the production process of coal-to-ethylene glycol, which is prepared by carbonylation synthesis reaction. The carbonylation synthesis device has complex reaction, and the main target product is oxalic acid dimethyl ester, which also has a series of side reactions. The products include dimethyl carbonate, methyl formate, methyl acetate, methyl formate and heavy components with boiling point higher than oxalic acid dimethyl ester, etc. The impurities in the product are numerous and complex, which has a great negative impact on the subsequent hydrogenation catalyst, resulting in high catalyst bed resistance, short service life and other problems. Therefore, in order to ensure the effective operation time of hydrogenation catalyst and reduce production cost, the crude oxalic acid dimethyl ester product of carbonylation synthesis must be refined to obtain high-purity target product. However, the negative pressure rectification technology is used to purify oxalic acid dimethyl ester, which needs to make oxalic acid dimethyl ester light removal tower and dimethyl carbonate separation tower operate under negative pressure condition. In the process of large-scale industrial operation, due to the frequent fluctuation of the content of each component of crude oxalic acid dimethyl ester after carbonylation reaction synthesis, the system pressure fluctuates greatly when oxalic acid dimethyl ester light removal tower and dimethyl carbonate separation tower operate, especially when carbonylation synthesis reaction just starts or carbonylation synthesis reactor replaces catalyst, the content of each component of crude oxalic acid dimethyl ester fluctuates greatly, which makes the system pressure fluctuate more greatly when oxalic acid dimethyl ester light removal tower and dimethyl carbonate separation tower operate, thereby seriously affecting the rectification efficiency and product quality. CONTENT OF THE UTILITY MODEL

[0003] Based on the problems of the prior art, the utility model provides a pressure stabilizing device for coal chemical industry oxalic acid dimethyl ester rectification system. The utility model overcomes the defect of fluctuation of the content of each component in crude oxalic acid dimethyl ester, makes the system of oxalic acid dimethyl ester light removal tower and dimethyl carbonate separation tower of oxalic acid dimethyl ester rectification device more stable, improves the rectification efficiency and guarantees the product quality.

[0004] In order to solve the above technical problems, the technical scheme of the utility model is as follows:

[0005] The utility model relates to a kind of coal chemical industry oxalic acid dimethyl ester rectification system's pressure stabilizing device, including oxalic acid dimethyl ester light removal column and dimethyl carbonate separation tower connected in sequence, the top of oxalic acid dimethyl ester light removal column and dimethyl carbonate separation tower top are all set top condenser and top reflux tank connected in sequence, and the top condenser is communicated with top reflux tank by condensate pipeline and balance pipeline;The top condenser or top reflux tank is connected to vacuum pump inlet by pipeline, and vacuum pump outlet is connected to vent pipe or volatile organic compound recovery device by pipeline a;The top condenser or top reflux tank is also provided with pressure stabilizing gas inlet, and the pressure stabilizing gas inlet is communicated with nitrogen pipe network or vacuum pump outlet, and the top of oxalic acid dimethyl ester light removal column and dimethyl carbonate separation tower is provided with pressure transmitter, and pressure transmitter is connected with automatic control device.

[0006] Further, the top condenser is provided with multiple parallel or multiple series.

[0007] Further, the pressure stabilizing gas inlet is connected to nitrogen pipe network by nitrogen pipeline;Nitrogen buffer tank is arranged on the nitrogen pipeline, pressure transmitter a is arranged on the nitrogen buffer tank, adjusting valve a and adjusting valve b are arranged on the pipeline connected with the inlet and outlet of nitrogen buffer tank respectively, and pressure transmitter a, adjusting valve a and adjusting valve b are connected with automatic control device.

[0008] Further, adjusting valve c is arranged on the pipeline a, and the pipeline a connected with adjusting valve c of vacuum pump outlet is connected to pressure stabilizing gas inlet by pipeline b.

[0009] Further, pressure stabilizing gas buffer tank is arranged on the pipeline b, adjusting valve d is arranged on the pipeline b connected with the inlet of pressure stabilizing gas buffer tank, adjusting valve e is arranged on the pipeline b connected with the outlet of pressure stabilizing gas buffer tank, pressure transmitter b is arranged on the pressure stabilizing gas buffer tank, and pressure transmitter b, adjusting valve c, adjusting valve d and adjusting valve e are connected with automatic control device. Beneficial effects

[0010] 1, the utility model sets up pressure stabilizing gas inlet on the top condenser or top reflux tank of oxalic acid dimethyl ester light removal column and dimethyl carbonate separation tower, utilizes to supplement nitrogen or the non-condensable gas reflux extracted by vacuum pump to regulate and control the system pressure of oxalic acid dimethyl ester light removal column or dimethyl carbonate separation tower, to overcome the problem that the system pressure of oxalic acid dimethyl ester light removal column and dimethyl carbonate separation tower is fluctuated greatly when running when each component content in crude oxalic acid dimethyl ester fluctuates greatly, to guarantee the system pressure of oxalic acid dimethyl ester light removal column and dimethyl carbonate separation tower is stable, to guarantee rectification efficiency and product quality further.

[0011] 2, The nitrogen buffer tank and the stable pressure gas buffer tank of the utility model are provided with pressure transmitters, the nitrogen supplement or the non-condensable gas backflow is adjusted through the automatic control device, the system pressure of the dimethyl oxalate light removal tower or the dimethyl carbonate separation tower is timely regulated and controlled, the system pressure of the dimethyl oxalate light removal tower or the dimethyl carbonate separation tower is more stable, the large fluctuation is avoided, and the operation strength and frequency of the operator are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is structural schematic view of the utility model embodiment 1;

[0013] Figure 2 It is structural schematic view of the utility model embodiment 2;

[0014] In the drawing: 1-dimethyl oxalate light removal tower; 2-tower top reflux tank a; 3-tower top condenser a; 4-vacuum pump a; 5-regulating valve ba; 6-nitrogen buffer tank a; 7-regulating valve aa; 8-dimethyl carbonate separation tower; 9-tower top reflux tank b; 10-tower top condenser b; 11-vacuum pump b; 12-regulating valve bb; 13-nitrogen buffer tank b; 14-regulating valve ab; 15-stable pressure gas buffer tank a; 16-regulating valve ca; 17-regulating valve da; 18-regulating valve ea; 19-stable pressure gas buffer tank b; 20-regulating valve cb; 21-regulating valve db; 22-regulating valve eb. DETAILED DESCRIPTION Embodiment 1

[0015] Refer to Figure 1, in order to oxalic acid dimethyl ester light tower 1 or dimethyl carbonate separation tower 8 more stable system pressure for operation, ensure the efficiency and product quality of rectification, the utility model provides a kind of coal chemical oxalic acid dimethyl ester rectification system's pressure stabilizing device, including the oxalic acid dimethyl ester light tower 1 and dimethyl carbonate separation tower 8 connected in sequence, the oxalic acid dimethyl ester light tower 1 top and dimethyl carbonate separation tower 8 top are all set sequentially connected overhead condenser and tower top reflux tank, respectively as overhead condenser a3, tower top reflux tank a2, overhead condenser b10, tower top reflux tank b9, the overhead condenser and tower top reflux tank still pass through condensate pipeline and balance pipeline communication, i.e. overhead condenser a3 and top reflux tank a still pass through condensate pipeline and balance pipeline communication, overhead condenser b10 and tower top reflux tank b9 still pass through condensate pipeline and balance pipeline communication;The tower top reflux tank is connected to vacuum pump inlet by pipeline, i.e. tower top reflux tank a2 is connected to the inlet of vacuum pump a4 by pipeline, tower top reflux tank b9 is connected to the inlet of vacuum pump b11 by pipeline;Vacuum pump outlet is connected to venting pipeline by pipeline a;The tower top reflux tank is also provided with pressure stabilizing gas inlet, and the pressure stabilizing gas inlet includes oxalic acid dimethyl ester light tower pressure stabilizing gas inlet and dimethyl carbonate separation tower pressure stabilizing gas inlet;The oxalic acid dimethyl ester light tower pressure stabilizing gas inlet is connected to nitrogen pipe network by nitrogen pipeline a, nitrogen buffer tank a6 is set on nitrogen pipeline a, pressure transmitter aa is set on nitrogen buffer tank a6, adjusting valve aa7 and adjusting valve ba5 are respectively set on the pipeline connected with the inlet and outlet of nitrogen buffer tank a6, and pressure transmitter aa, adjusting valve aa7 and adjusting valve ba5 are connected with automatic control device;The dimethyl carbonate separation tower pressure stabilizing gas inlet is connected to nitrogen pipe network by nitrogen pipeline b, nitrogen buffer tank b13 is set on nitrogen pipeline b, pressure transmitter ab is set on nitrogen buffer tank b13, adjusting valve ab14 and adjusting valve bb12 are respectively set on the pipeline connected with the inlet and outlet of nitrogen buffer tank b13, and pressure transmitter ab, adjusting valve ab14 and adjusting valve bb12 are connected with automatic control device;Pressure transmitter, which is set on the top of oxalic acid dimethyl ester light tower 1 and the top of dimethyl carbonate separation tower 8, is connected with automatic control device. Example 2

[0016] Refer to Figure 2, in order to make the system pressure of dimethyl oxalate light removal column 1 or dimethyl carbonate separation column 8 more stable, ensure the efficiency and product quality of rectification, the utility model provides a kind of pressure stabilizing device of coal chemical dimethyl oxalate rectification system, including the dimethyl oxalate light removal column 1 and dimethyl carbonate separation column 8 connected in turn, the top of dimethyl oxalate light removal column 1 and the top of dimethyl carbonate separation column 8 are all provided with top condenser and top reflux tank connected in turn, respectively as top condenser a3, top reflux tank a2, top condenser b10, top reflux tank b9, the top condenser and top reflux tank are also communicated by condensate pipeline and balance pipeline, i.e.top condenser a3 and top reflux tank a are also communicated by condensate pipeline and balance pipeline, top condenser b10 and top reflux tank b9 are also communicated by condensate pipeline and balance pipeline;The top condenser is connected to vacuum pump inlet by pipeline, i.e.top condenser a3 is connected to the inlet of vacuum pump a4 by pipeline, top condenser b10 is connected to the inlet of vacuum pump b11 by pipeline;The outlet of vacuum pump is connected to volatile organic compound recovery device by pipeline a, i.e.the outlet of vacuum pump a4 is connected to volatile organic compound recovery device by pipeline aa, the outlet of vacuum pump b11 is connected to volatile organic compound recovery device by pipeline ab;The top condenser is also provided with pressure stabilizing gas inlet, and the pressure stabilizing gas inlet includes dimethyl oxalate light removal column pressure stabilizing gas inlet and dimethyl carbonate separation column pressure stabilizing gas inlet;Adjusting valve ca16 is arranged on pipeline aa, and the pipeline aa connected between the outlet of vacuum pump a4 and adjusting valve ca16 is connected to dimethyl oxalate light removal column pressure stabilizing gas inlet by pipeline ba;Adjusting valve cb20 is arranged on pipeline ab, and the pipeline ab connected between the outlet of vacuum pump b11 and adjusting valve cb20 is connected to dimethyl carbonate separation column pressure stabilizing gas inlet by pipeline bb;Stabilizing gas buffer tank a15 is arranged on pipeline ba, adjusting valve da17 is arranged on the pipeline ba connected to the inlet of stabilizing gas buffer tank a15, and adjusting valve ea18 is arranged on the pipeline ba connected to the outlet of stabilizing gas buffer tank a15;Stabilizing gas buffer tank b19 is arranged on pipeline bb, adjusting valve db21 is arranged on the pipeline bb connected to the inlet of stabilizing gas buffer tank b19, and adjusting valve eb22 is arranged on the pipeline bb connected to the outlet of stabilizing gas buffer tank b19;Pressure transmitter b is arranged on stabilizing gas buffer tank a15 and stabilizing gas buffer tank b19, and pressure transmitter b, adjusting valve ca16, adjusting valve da17, adjusting valve ea18, adjusting valve cb20, adjusting valve db21 and adjusting valve eb22 are connected to automatic control device.

[0017] Another embodiment is different from embodiment 1 in that the top condenser is provided with two parallel connections.

[0018] Another embodiment is different from embodiment 2 in that the top condenser is provided with three parallel connections.

[0019] Another embodiment differs from embodiment 1 in that two overhead condensers are arranged in series.

[0020] Another embodiment differs from embodiment 2 in that three overhead condensers are arranged in series.

[0021] The working principle of the utility model is: because the content of each component of the crude dimethyl oxalate synthesized by carbonylation reaction fluctuates frequently, the system pressure fluctuates greatly when the dimethyl oxalate light removal column 1 and the dimethyl carbonate separation column 8 are running, in order to make the system pressure of the dimethyl oxalate light removal column 1 or the dimethyl carbonate separation column 8 running more stable, ensure the efficiency and product quality of rectification, the utility model sets up the stable pressure gas inlet on the overhead condenser or the overhead reflux tank of the dimethyl oxalate light removal column 1 and the dimethyl carbonate separation column 8, utilizes the non-condensed gas reflux extracted by the supplementary nitrogen or vacuum pump to regulate and control the system pressure of the dimethyl oxalate light removal column 1 or the dimethyl carbonate separation column 8, thereby ensuring the system pressure stability of the dimethyl oxalate light removal column 1 and the dimethyl carbonate separation column 8, and further ensuring the rectification efficiency and product quality; meanwhile, the nitrogen buffer tank and the stable pressure gas buffer tank of the utility model set up the pressure transmitter, adjust the supplementary amount of nitrogen or the non-condensed gas reflux amount through the automatic control device, regulate and control the system pressure of the dimethyl oxalate light removal column 1 or the dimethyl carbonate separation column 8 in time, make the system pressure of the dimethyl oxalate light removal column 1 or the dimethyl carbonate separation column 8 more stable, avoid the great fluctuation, and reduce the operation strength and frequency of the operator.

[0022] The modification and change of the utility model of the person skilled in the art belong to the patent range of the utility model, and are not limited to the embodiment.

Claims

1. A pressure stabilizing device for a coal chemical dimethyl oxalate distillation system, characterized in that: The device comprises a dimethyl oxalate light-removing column and a dimethyl carbonate separation column connected in sequence, a top condenser and a top reflux tank connected in sequence are arranged at the top of the dimethyl oxalate light-removing column and the dimethyl carbonate separation column, the top condenser and the top reflux tank are communicated by a condensate pipeline and an equalization pipeline; the top condenser or the top reflux tank is connected to a vacuum pump inlet by a pipeline, a vacuum pump outlet is connected to a venting pipeline or a volatile organic compound recovery device by a pipeline a; the top condenser or the top reflux tank is further provided with a pressure stabilizing gas inlet, the pressure stabilizing gas inlet is communicated with a nitrogen pipeline network or a vacuum pump outlet, a pressure transmitter is arranged at the top of the dimethyl oxalate light-removing column and the dimethyl carbonate separation column, and the pressure transmitter is connected to an automatic control device.

2. The pressure stabilizing device of a dimethyl oxalate rectification system in coal chemical industry according to claim 1, characterized in that: The pressure stabilizing gas inlet is connected to the nitrogen pipeline network by a nitrogen pipeline; a nitrogen buffer tank is arranged on the nitrogen pipeline, a pressure transmitter a is arranged on the nitrogen buffer tank, and an adjusting valve a and an adjusting valve b are arranged on the pipelines connected to the inlet and the outlet of the nitrogen buffer tank, respectively; the pressure transmitter a, the adjusting valve a and the adjusting valve b are connected to the automatic control device.

3. The pressure stabilizing device of a dimethyl oxalate rectification system in coal chemical industry according to claim 1, characterized in that: An adjusting valve c is arranged on the pipeline a, and the pipeline a connected to the adjusting valve c is connected to the pressure stabilizing gas inlet by a pipeline b.

4. The pressure stabilizing device of a dimethyl oxalate rectification system in coal chemical industry according to claim 3, characterized in that: A pressure stabilizing gas buffer tank is arranged on the pipeline b, an adjusting valve d is arranged on the pipeline b connected to the inlet of the pressure stabilizing gas buffer tank, an adjusting valve e is arranged on the pipeline b connected to the outlet of the pressure stabilizing gas buffer tank, and the pressure stabilizing gas buffer tank is provided with a pressure transmitter b; the pressure transmitter b, the adjusting valve c, the adjusting valve d and the adjusting valve e are connected to the automatic control device.

5. The pressure stabilizing device of a dimethyl oxalate rectification system for coal chemical industry according to any one of claims 1-4, characterized in that: The top condenser is provided with multiple parallel or multiple series top condensers.

Images