A pulverized coal gasifier synthesis gas quenching device and method

Abstract

The present invention discloses a pulverized coal gasifier synthesis gas quenching device and method, belonging to the technical field of pulverized coal gasifier synthesis gas treatment; the device and method comprise a wastewater tank, a water supply quenching pump, an electromagnetic flow control valve, a venturi nozzle and a temperature sensor; the wastewater tank is connected to the venturi nozzle via a wastewater pipeline, and the venturi nozzle is connected to a quenching pipe on the top of the pulverized coal gasifier; a water supply quenching pump is provided on the wastewater pipeline; the quenching pipe is connected to a temperature sensor; the temperature sensor is connected to a controller, and the controller is connected to the electromagnetic flow control valve; the present invention utilizes wastewater spray to cool the synthesis gas in the quenching pipe, which has an energy-saving effect on the one hand, and on the other hand increases the H / C value of the synthesis gas, thereby extending the service life of the catalyst.

Description

Technical Field

[0001] The invention belongs to the technical field of pulverized coal gasifier synthesis gas treatment, and in particular relates to a pulverized coal gasifier synthesis gas quenching device and method. Background Art

[0002] The pulverized coal gasification process takes place under high-temperature, pressurized conditions. Pulverized coal, oxygen, and a small amount of steam flow concurrently into the gasifier under pressure, completing a series of physical and chemical processes, including heating, volatile removal, cracking, combustion, and conversion, in a remarkably short period of time. The pressurized pulverized coal, oxygen, and steam enter the gasifier through four horizontally symmetrically arranged coal burners on the gasifier shell. Under pressures of 3.5-4.0 MPa and temperatures of 1400°C-1600°C, they are converted into syngas within the membrane-type walls. To prevent molten slag from adhering to the gasifier channels after exiting, the hot syngas is quenched by cold syngas at the cone quench port at the gasifier top, forming a solid state. This prevents adhesion to downstream systems and reduces resistance in the gasifier channels. The existing quenching method is to use cold synthesis gas to enter the quencher to cool the hot synthesis gas. On the one hand, the use of cold synthesis gas requires a refrigeration process, which increases energy consumption. On the other hand, after quenching with cold synthesis gas, the H / C value of the synthesis gas is low, resulting in a shortened catalyst life in the furnace. Summary of the Invention

[0003] The present invention overcomes the deficiencies of the prior art and provides a pulverized coal gasifier synthesis gas quenching device and method.

[0004] In order to achieve the above object, the present invention is implemented through the following technical solutions.

[0005] A pulverized coal gasifier synthesis gas quenching device includes a wastewater tank, a feed water quenching pump, an electromagnetic flow control valve, a Venturi nozzle and a temperature sensor; the wastewater tank is connected to the Venturi nozzle through a wastewater pipeline, and the Venturi nozzle is connected to the quenching pipe on the top of the pulverized coal gasifier; the wastewater pipeline is provided with a feed water quenching pump; the quenching pipe is connected to the temperature sensor; the temperature sensor is connected to a controller, and the controller is connected to the electromagnetic flow control valve.

[0006] Furthermore, the wastewater tank is connected to the wastewater pipeline via a switching pipeline, and the switching pipeline is connected in parallel with the feed water quenching pump.

[0007] Furthermore, the switching pipeline is provided with a switching valve.

[0008] Furthermore, the quenching pipe is connected to the top of the synthesis gas cooler, the bottom of the synthesis gas cooler is connected to the dust removal device and the water treatment device in sequence, and the wastewater outlet of the water treatment device is connected to the wastewater tank.

[0009] Furthermore, the dust removal device is a dry dust collector, and the water treatment device is a wet scrubber.

[0010] Furthermore, the filter cake outlet of the water treatment device is connected to the coal grinding and drying device for mixing with the coal and entering the pulverized coal gasification furnace.

[0011] The method for quenching the synthesis gas from a pulverized coal gasifier using the quenching device comprises the following steps:

[0012] 1) Coal is pulverized by the coal grinding and drying device, which is then pressurized and fed into the furnace of the pulverized coal gasifier with oxygen and steam. Under the conditions of a pressure of 3.5-4.0 MPa and a temperature of 1400℃-1600℃, the syngas is converted into synthesis gas within the membrane wall. The synthesis gas then enters the quenching tube at the top of the furnace.

[0013] 2) The wastewater tank is filled with wastewater, which flows through the wastewater pipeline into the Venturi nozzle. The Venturi nozzle atomizes the wastewater and sprays it into the quenching tube, where it mixes with the syngas and cools the syngas. After that, the syngas enters the syngas cooler, where the gas outlet temperature reaches 340°C.

[0014] 3) Synthesis gas enters dry dust collector from synthesis gas cooler. After ash removal and purification in dry dust collector, the fly ash content in coal gas is less than 20mg / Nm 3 ;

[0015] 4) After leaving the dry dust collector, the syngas is split into two paths: one path goes to the wet scrubber, and the other path goes to the quenching gas compressor;

[0016] 5) The wastewater discharged from the wet scrubber enters the wastewater tank through a pipeline for reuse; the discharged filter cake enters the coal grinding and drying device and is mixed with coal for reuse.

[0017] The beneficial effects of the present invention compared to the prior art are:

[0018] This invention, based on the design of a pulverized coal gasifier process with quenching gas, adds a wastewater tank, a quenching water pump, a Venturi nozzle, temperature monitoring and control, and related process pipeline valve control components to cool hot syngas using wastewater spray. The wastewater used is relatively common, requiring only high COD (CxHy, CxHyOz, etc.), such as wastewater rich in organic acids, methanol, residual oil, and other such substances. The wastewater is flow-controlled through the quenching water pump and introduced into the quenching stage as a spray. The quenching gas volume is adjusted based on the syngas quenching temperature (<900°C), increasing the water volume while reducing the quenching ratio. The water intake is gradually increased according to operating conditions until the equilibrium value is reached.

[0019] Using wastewater injection to create a spray instead of quenching gas quenching, the gasifier's external gas flow rate is increased, extending the reaction path within a limited height space. During the flow of the mixed gas, the syngas and wastewater ejected from the wastewater nozzle are fully mixed and reacted thoroughly. During the waste heat recovery process of the pulverized coal gasifier, the quenching gas volume is gradually reduced, and the external gas volume is increased. At the same time, the operating conditions are adjusted according to the composition of the syngas to meet the H / C requirements of subsequent reactions. The use of wastewater spray mixed with the syngas for cooling simultaneously increases the H / C value of the syngas, extending the catalyst service life by 1-2 years. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of the syngas quenching device for a pulverized coal gasifier according to the present invention.

[0021] In the figure, 1-wastewater tank, 2-feed water quenching pump, 3-electromagnetic flow control valve, 4-Venturi nozzle, 5-temperature sensor, 6-wastewater pipeline, 7-pulverized coal gasification furnace, 8-quenching pipe, 10-pulverized coal drying device, 11-controller, 12-switching pipeline, 13-switching valve, 14-synthesis gas cooler, 15-dry dust collector, 16-wet scrubber. DETAILED DESCRIPTION

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. The technical solutions of the present invention will be described in detail below with reference to the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0023] like Figure 1 As shown, this embodiment provides a syngas quenching device for a pulverized coal gasifier, comprising a wastewater tank 1, a feedwater quenching pump 2, an electromagnetic flow control valve 3, a venturi nozzle 4, and a temperature sensor 5. The wastewater tank 1 is connected to the venturi nozzle 4 via a wastewater pipeline 6, and the venturi nozzle 4 is connected to a quenching pipe 8 at the top of a pulverized coal gasifier 7. The pulverized coal gasifier 7 is a Shell pulverized coal gasifier. The wastewater pipeline 6 is provided with a feedwater quenching pump 2; the quenching pipe 8 is connected to a temperature sensor 5; the temperature sensor 5 is connected to a controller 11, and the controller 11 is connected to the electromagnetic flow control valve 3. The wastewater tank 1 is connected to the wastewater pipeline 6 via a switching pipeline 12, which is connected in parallel with the feedwater quenching pump 2. The switching pipeline 12 is provided with a switching valve 13.

[0024] The quenching pipe 8 is connected to the top of the syngas cooler 14. The bottom of the syngas cooler 14 is connected to the dry dust collector 15 and the wet scrubber 16 in sequence. The wastewater outlet of the wet scrubber 16 is connected to the wastewater tank 1. The filter cake outlet of the wet scrubber 16 is connected to the coal grinding and drying device 10 for mixing with the coal before entering the pulverized coal gasifier.

[0025] The specific working process is:

[0026] Coal is pulverized by a pulverized coal drying device 10, which is then pressurized and mixed with oxygen and steam before entering the furnace of a pulverized coal gasifier 7. At a pressure of 3.5-4.0 MPa and a temperature of 1400°C-1600°C, the coal is converted into syngas within the membrane wall, which then enters a quenching tube 8 at the top of the furnace. A wastewater tank 1 contains conventional, common wastewater, requiring only high COD (CxHy, CxHyOz, etc.), such as wastewater rich in organic acids, methanol, residual oil, or the like. The wastewater passes through a wastewater pipeline 6 and reaches a venturi nozzle 4, which atomizes the wastewater and sprays it into a quenching tube 8, where it mixes with the syngas and cools the syngas. The syngas then enters a syngas cooler 14, where the gas outlet temperature reaches 340°C.

[0027] The coal gas from the synthesis gas cooler 14 enters the dry dust collector 15. In this embodiment, the dry dust collector 15 adopts a fly ash filter. The fly ash content after filtration in the dry dust collector 15 is controlled at 20 mg / Nm 3 After leaving the fly ash filter, the clean syngas is divided into two streams, one to the downstream wet scrubber system, namely the wet scrubber 16, and the other to the quenching gas compressor. The wet scrubber 16 removes fine ash from the syngas, reducing it to 1 mg / Nm 3 On the other hand, some acidic gases in the syngas are also removed during the wet scrubbing process, lowering the syngas temperature to approximately 168°C. After scrubbing, the syngas passes through the C-1601 overhead demister and is split into two streams: one stream goes to the downstream conversion section, and the other stream is mixed with some syngas from the dry dust collector 15 and sent to the quenching gas compressor.

[0028] The wastewater discharged from the wet scrubber 16 enters the wastewater tank 1 through a pipeline to be reused; the discharged filter cake enters the coal grinding and drying device 10 and is mixed with coal for reuse.

[0029] Temperature sensor 5 in this device is used to detect the temperature inside chilling tube 8 and adjust the opening of electromagnetic flow control valve 3 according to temperature changes. Switching line 12 is used as a backup line. If a problem occurs in the main line, it can be switched to switching line 12 to provide wastewater spray to chilling tube 8.

[0030] In this example, 8.6 MPa boiler water at a reduced pressure (154°C) was used as quench feed water to compare with the conventional cold air quenching process. The composition of the synthesis gas was measured, and the results are as follows:

[0031] Table 1 Comparison of synthesis gas components

[0032]

[0033] The H / C value of the synthesis gas is improved by 0.05-0.15 compared with the existing cold gas quenching, and the service life of the existing conversion catalyst can be extended by 1-2 years.

[0034] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be considered that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the present invention, which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims

1. A method for quenching synthesis gas from a pulverized coal gasifier, characterized in that: A pulverized coal gasifier synthesis gas quenching device is used, comprising a wastewater tank (1), a feedwater quenching pump (2), an electromagnetic flow control valve (3), a Venturi nozzle (4) and a temperature sensor (5); the wastewater tank (1) is connected to the Venturi nozzle (4) via a wastewater pipeline (6), and the Venturi nozzle (4) is connected to a quenching pipe (8) on the top of a pulverized coal gasifier (7); the wastewater pipeline (6) is provided with a feedwater quenching pump (2); the quenching pipe (8) is connected to a temperature sensor (5); the temperature sensor (5) is connected to a controller (11), and the controller (11) is connected to the electromagnetic flow control valve (3); The quenching pipe (8) is connected to the top of the synthesis gas cooler (14), and the bottom of the synthesis gas cooler (14) is connected to the dust removal device and the water treatment device in sequence. The wastewater outlet of the water treatment device is connected to the wastewater tank (1); the dust removal device is a dry dust collector (15), and the water treatment device is a wet scrubber (16). The filter cake outlet of the water treatment device is connected to the pulverized coal drying device (10) for mixing with coal and entering the pulverized coal gasification furnace; The following steps are involved: 1) Coal is pulverized by a coal grinding and drying device (10) and then pressurized. It is then mixed with oxygen and steam and enters the furnace of a pulverized coal gasifier (7). Under the conditions of a pressure of 3.5-4.0 MPa and a temperature of 1400°C-1600°C, the pulverized coal is converted into syngas within the membrane wall. The syngas then enters the quenching pipe (8) at the top of the furnace. 2) The wastewater tank (1) contains wastewater, which enters the venturi nozzle (4) through the wastewater pipe (6). The venturi nozzle (4) atomizes the wastewater and sprays it into the quenching pipe (8), where it mixes with the synthesis gas and cools the synthesis gas. After that, the synthesis gas enters the synthesis gas cooler (14), and the temperature at the gas outlet reaches 340°C. 3) Synthesis gas enters dry dust collector (15) from synthesis gas cooler (14). After the synthesis gas is ash-cleaned and filtered in dry dust collector (15), the fly ash content in the gas is less than 20mg / Nm 3 ; 4) After leaving the dry dust collector (15), the synthesis gas is divided into two paths, one path enters the wet scrubber (16), and the other path enters the quenching gas compressor; 5) The wastewater discharged from the wet scrubber (16) enters the wastewater tank (1) through a pipeline and is reused; the discharged filter cake enters the coal grinding and drying device (10) and is mixed with coal and then reused.

2. The method for quenching synthesis gas from a pulverized coal gasifier according to claim 1, characterized in that: The wastewater tank (1) is connected to the wastewater pipeline (6) via a switching pipeline (12), and the switching pipeline (12) is connected in parallel with the feedwater quenching pump (2).

3. The method for quenching synthesis gas from a pulverized coal gasifier according to claim 2, characterized in that: The switching pipeline (12) is provided with a switching valve (13).

Images