Purification system for biomass gasification synthesis gas

Abstract

The utility model provides a purification system for biomass gasification synthesis gas, which solves the problem that byproducts such as tar, dust and the like enter downstream sections due to incomplete washing in the biomass normal-pressure gasification process through devices such as a washing tower with an upper tower and a lower tower establishing an independent circulating system. The main problems of equipment blockage in the synthesis gas cooling process and separation of byproducts such as waste tar and dust are solved; the dust removal rate and the tar removal rate are obviously improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of chemical production relates to a kind of purification system for biomass gasification synthesis gas. BACKGROUND

[0002] Biomass methanol as zero-carbon production process, renewable resources and its process production green methanol Chemical property and the methanol produced by fossil fuel are same, but greenhouse gas emissions in whole life cycle can be significantly reduced.

[0003] Atmospheric pressure biomass gasification technology, after years of research and practice has gradually moved towards mature and stable stage. However, the wide application of this technology still faces an unavoidable challenge, namely in the production process of biomass gasification, tar, dust and other by-products will inevitably be produced, which will enter the subsequent section with synthesis gas. Therefore, it is extremely necessary to develop a targeted, efficient and economical biomass gasification synthesis gas by-product purification technology to ensure the stable operation of the whole gasification system and the final quality of the product. SUMMARY

[0004] The purification system for biomass gasification synthesis gas provided by the utility model solves the main problems of incomplete washing of tar, dust and other by-products in the atmospheric pressure gasification process of biomass, equipment blockage in the synthesis gas cooling process and separation of waste tar, dust and other by-products.

[0005] The technical scheme adopted by the utility model is as follows:

[0006] A purification system for biomass gasification synthesis gas, comprising a washing tower, the top of the washing tower is connected with the top of the electric tar precipitator, and the bottom is connected with the top of the clarifying tank and the side of the tar tank in sequence; the washing tower is divided into an upper tower and a lower tower, wherein the upper tower is a main washing section, and the lower tower is a pre-washing section; a communication pipe switch is installed between the upper and lower towers; the middle part of the clarifying tank is connected with the top of the lower tower through a pipeline, and a wastewater outlet is installed at the bottom.

[0007] As a preferred embodiment of the utility model, the bottom of the electric tar precipitator is connected with the top of the tar tank through a pipeline.

[0008] As a preferred embodiment of the utility model, a packing layer is installed in the upper tower.

[0009] As a preferred embodiment of the utility model, a plurality of washing nozzles are installed in the upper tower and / or the lower tower.

[0010] As a preferred embodiment of the utility model, a washing liquid inlet is arranged on one side of the upper tower, and a water inlet and a water outlet are arranged at the upper and lower ends of the other side respectively, and a first heat exchanger is installed between the water inlet and the water outlet.

[0011] As a preferred of the utility model, the lower end of one side of the lower tower is equipped with a synthetic gas inlet.

[0012] As a preferred of the utility model, a second heat exchanger is installed at the pipeline connecting the middle of the clarifying tank and the top of the lower tower.

[0013] As a preferred of the utility model, the communication pipe switch is an LV valve controlled by the upper tower liquid level meter.

[0014] The utility model has the advantages of:

[0015] (1) the atmospheric gasification biomass synthetic gas enters the washing tower only about 5KPa (G), effectively reduces the pressure loss by adopting two-stage special filler tower equipment, without additional pressurization, and the synthetic gas washing can be completed;

[0016] (2) the washing tower is divided into an upper tower (fine washing section) and a lower tower (pre-washing section), the lower tower removes the main synthetic gas impurities by the washing water with large spray density, effectively preventing the upper tower filler layer from being blocked;

[0017] (3) unlike the traditional washing tower, the upper and lower towers establish independent circulation, the upper tower supplements fresh water, and the lower tower returns the water to the tower after clarification, preventing the phenomenon of dirty water accumulation in the tower from causing a dirty tower;

[0018] (4) the wastewater at the bottom of the tower is filtered through the clarifying tank and recycled, effectively reducing the amount of fresh water supplement and reducing the device material consumption;

[0019] (5) the circulating water of the upper and lower towers is equipped with an external cooler, and the synthetic gas can be cooled in the tower. The heat of the synthetic gas is removed in the washing tower, avoiding the setting of a synthetic gas heat exchanger due to the need for temperature reduction in the subsequent section, and preventing the synthetic gas heat exchanger from being blocked by tar, dust and other by-products;

[0020] (6) the clarifying tank adopts three-phase stratification for separation, and through calculation of dust and tar particle size distribution and residence time, the clarifying tank is divided into an upper light tar separation section, a middle clarifying circulating water section and a lower dust-containing sewage section, effectively separating and specifically treating related by-products, and the separated tar is sold to improve the economic value of the device;

[0021] (7) an electric tar catcher is arranged at the gas phase outlet of the washing tower, effectively improving tar conversion;

[0022] (8) the maximum removal rate of tar in the process reaches 96%, the dust removal rate is 98%, the synthetic gas outlet temperature is ≤40℃, and the pressure drop is only 1.2KPa. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the utility model

[0024] In the diagram: 1-washing tower, 2-clarification tank, 3-tar tank, 4-electrostatic tar precipitator, 5-first heat exchanger, 6-washing liquid pump, 7-second heat exchanger, 8-circulating water pump, 9-tar pump, 10-wastewater pump. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] like Figure 1 The purification system for biomass gasification syngas shown includes a scrubbing tower 1. The top of the scrubbing tower 1 is connected to the top of an electrostatic precipitator 4, and the bottom is connected to the top of a clarifier tank 2 and the side of a tar tank 3 in sequence. The bottom of the electrostatic precipitator is connected to the top of the tar tank via a pipe. The scrubbing tower 1 is divided into an upper tower and a lower tower, wherein the upper tower is the main scrubbing section and the lower tower is the pre-scrubbing section. A connecting pipe switch is installed between the upper and lower towers. The middle part of the clarifier tank 2 is connected to the top of the lower tower via a pipe, and a wastewater outlet is installed at the bottom.

[0027] The upper tower is equipped with a packing layer, and several washing nozzles are installed in both the upper and lower towers. The upper tower has a washing liquid inlet on one side and a water inlet and outlet at the upper and lower ends of the other side, respectively. A first heat exchanger 5 is installed between the water inlet and outlet. The lower tower has a synthesis gas inlet at the lower end of one side.

[0028] A second heat exchanger 7 is also installed at the pipe connecting the middle of the clarification tank to the top of the lower tower.

[0029] In some more specific implementations:

[0030] Syngas at 230℃ and 5 kPa(G) enters the lower column of scrubbing tower 1 from the biomass atmospheric gasifier via a bag filter. The lower column of scrubbing tower 1 does not have a packing layer or trays. Fresh water / shift condensate enters the upper column of scrubbing tower 1, which has two sections of packing. The lower column (pre-washing section) uses cleaned and heat-exchanged wastewater from the bottom of the scrubbing tower for high-density pre-washing, removing most of the tar, dust, and other byproducts. The syngas then enters the upper column (fine washing section) for fine washing using cooled circulating water and fresh water / shift condensate.

[0031] After the washing, 98(wt)% of the dust and 70(wt)% of the tar in the synthesis gas are removed, and the tar removal rate reaches 96(wt)% after the electric tar precipitator 9. Finally, the water in the upper tower is used as an index for discharging to the lower tower, and when the tar content in the water reaches 100 ppm, the upper and lower tower communication pipe switch (LV valve controlled by the upper tower liquid level meter) is opened, and the wastewater in the upper tower is discharged to the bottom of the lower tower.

[0032] The wastewater at the bottom of the washing tower is treated by layering in the clarifier 2, and the layering time is calculated by particle size distribution and residence time using the Stokes formula. The tar is skimmed into the tar tank 3 using the oil skimmer in the clarifier at a suitable position in the upper layer, and the tar produced by ionization in the electric tar precipitator 4 (one electric tar precipitator is set for standby to facilitate the removal of stubborn tar inside the electric tar precipitator) is sold together. A small amount of heavy tar and other wastewater in the lower layer is sent to the environmental protection treatment section (filter pressing treatment) by the wastewater pump 10. The clarified wastewater in the middle section is sequentially sent into the lower tower of the washing tower 1 by the circulating water pump 8 and the second heat exchanger 7.

[0033] The basic principle, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only preferred examples of the present application and do not limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A purification system for biomass gasification syngas, characterized by, The purification system comprises a washing tower (1), the top of the washing tower (1) is connected with the top of an electric tar precipitator (4), the bottom is sequentially connected with the top of a clarifier (2) and the side of a tar tank (3); the washing tower (1) is divided into an upper tower and a lower tower, wherein the upper tower is a main washing section, and the lower tower is a pre-washing section; a communication pipe switch is installed between the upper tower and the lower tower; the middle of the clarifier (2) is connected with the top of the lower tower through a pipeline, and a waste water outlet is installed at the bottom.

2. The purification system of claim 1, wherein, The bottom of the electric tar precipitator (4) is connected with the top of the tar tank (3).

3. The purification system of claim 2, wherein, A filler layer is installed in the upper tower.

4. The purification system of claim 2, wherein, A plurality of washing nozzles are installed in the upper tower and / or the lower tower.

5. The purification system of claim 3, wherein, A washing liquid inlet is arranged on one side of the upper tower, and a water inlet and a water outlet are arranged at the upper and lower ends of the other side respectively; a first heat exchanger (5) is installed between the water inlet and the water outlet.

6. The purification system of claim 4, wherein, A syngas inlet is arranged at the lower end of one side of the lower tower.

7. The purification system of claim 1, wherein, A second heat exchanger (6) is further installed at the pipeline connecting the middle of the clarifier (2) with the top of the lower tower.

8. The purification system of claim 1, wherein, The communication pipe switch is an LV valve controlled by an upper tower liquid level meter.

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