Process and system for fly ash back-flushing using ammonia synthesis fresh gas

Abstract

The present application relates to a kind of process and system for fly ash filter backflushing using ammonia synthesis fresh gas, the present application uses such a kind of gas source of ammonia synthesis fresh gas, the ratio of H2 and N2 is about 3:1, after being treated by multi-stage compression cooling, it is used as backflushing gas to carry out backflushing to fly ash filter.The ammonia synthesis compressor outlet fresh gas pressure is high, on the basis of reserving the original configuration of powder coal gasification waste boiler process preparation synthetic ammonia device, the high temperature and high pressure fresh gas is used, without additional equipment investment, process is simple, and reliability is high;Process is provided with backflushing gas buffer tank, and multiple temperature, pressure, flow control interlock is set, it is favorable to improve backflushing gas stability, and backflushing gas has no corrosivity to equipment, it is favorable to the long period, stable operation of fly ash filter;Ammonia synthesis fresh gas as backflushing gas does not need additional pressurization, reduces the compression power consumption, without additional air separation device for high pressure nitrogen configuration, and nitrogen hydrogen ratio is appropriate, reduces additional nitrogen consumption.

Description

Technical Field

[0001] This invention relates to a process and system for backflushing fly ash filtration using ammonia synthesis fresh gas. Background Technology

[0002] High-temperature, high-pressure fly ash filters are one of the key pieces of equipment in pulverized coal gasification units, generally used to remove dust from process syngas. For example... Figure 1 As shown, fly ash carried by the gas is collected on the outer surface of the filter rod, and the dust content in the filtered syngas is approximately 1–2 mg / Nm³. 3 The gas enters the top of the container through the filter inlet and is directly sent to the subsequent stage mixer and then to the water washing tower for further washing. High-temperature and high-pressure filters are usually equipped with a backflushing system, which uses high-temperature and high-pressure gas to backflush the filter element to ensure that the pressure drop of the filter is controlled within 0.03 MPa.

[0003] Inadequate backflushing gas is a major cause of filter malfunction. For ammonia synthesis units produced from pulverized coal gasification waste boilers, the backflushing gas for fly ash filters typically uses syngas produced by the gasification process itself or high-pressure nitrogen from the air separation unit. For example... Figure 2 As shown, in pulverized coal gasification units, most enterprises use nitrogen / carbon dioxide at approximately 8 MPa as backflushing gas, while some enterprises use syngas from the wet scrubbing tower outlet. Using 8 MPa nitrogen / carbon dioxide as backflushing gas, and employing high-pressure nitrogen from the air separation unit, increases the nitrogen supply load on the air separation unit and complicates the high-pressure nitrogen supply configuration. Furthermore, the purified syngas has a high nitrogen content, and the exported hydrogen (supplied outside the ammonia synthesis unit) also has a high nitrogen content, resulting in high purification energy consumption. If carbon dioxide from acid removal byproducts is used as backflushing gas, its low pressure necessitates pressurizing it to 8.0 MPa to meet the backflushing process requirements, requiring a separate carbon dioxide compressor with high energy consumption. If syngas produced by the gasification unit itself is used, its low pressure necessitates pressurization to 8.0 MPa to meet the backflushing process requirements, requiring a separate syngas compressor, buffer tank, and other facilities. This also leads to corrosion of the backflushing valves and pipelines, severely impacting the backflushing process. . Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a process and system that uses ammonia synthesis fresh gas for backflushing fly ash filters, which meets the high temperature and high pressure backflushing requirements of fly ash filters without the need for additional processes, in light of the current state of the technology.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] A process for fly ash filtration backflushing using ammonia synthesis fresh gas includes the following steps:

[0007] The fresh gas for ammonia synthesis is pressurized in the first stage of the ammonia synthesis compressor, then passes through the first stage outlet cooler before entering the second stage of the ammonia synthesis compressor, and then passes through the second stage outlet cooler before entering the third stage of the ammonia synthesis compressor.

[0008] The outlet backflush gas pressure reaches 8 MPaG. The flow rate of the backflush gas from the second stage of the ammonia synthesis compressor to the ammonia synthesis fresh gas heater is controlled by the air extraction flow control valve of the second stage of the ammonia synthesis compressor. The backflush gas is then heated by the ammonia synthesis fresh gas heater. This stage controls the steam flow rate entering the ammonia synthesis fresh gas heater by adjusting the backflush gas temperature control valve, thereby controlling the temperature of the backflush gas at the outlet of the ammonia synthesis fresh gas heater.

[0009] The backflush gas, adjusted to a suitable temperature, is then introduced into the backflush gas buffer tank for buffering. The outlet is controlled by the backflush gas switch valve. The gasified syngas is then filtered by the fly ash filter to obtain syngas after dust removal. The backflush gas switch valve is adjusted by measuring the pressure difference of the fly ash filter to periodically purge the fly ash filter and ensure the dust removal effect.

[0010] Preferably, the volume ratio of H2 to N2 in the outlet backflush gas is 3:1. Using this backflush gas not only improves the stability of the backflush gas, but also has no corrosive effect on the equipment, which is conducive to the long-term and stable operation of the fly ash filter, and also reduces the additional nitrogen consumption.

[0011] Preferably, the temperature, flow rate, and differential pressure of the ammonia synthesis fresh gas used as backflush gas are coupled and regulated by an extraction flow control valve, a backflush gas temperature control valve, and a backflush gas on / off valve. The temperature, flow rate, and differential pressure of the backflush gas are interlocked and controlled as needed at various points to further improve the stability of the backflush gas.

[0012] A system for fly ash filtration and backflushing using ammonia synthesis fresh gas includes:

[0013] The first stage of the ammonia synthesis compressor is used to pressurize the fresh gas for ammonia synthesis.

[0014] An outlet cooler is connected to the outlet of the first stage of the ammonia synthesis compressor and is used to cool the ammonia synthesis fresh gas.

[0015] The second stage of the ammonia synthesis compressor is connected to the outlet of the first stage outlet cooler and is used to repressurize the ammonia synthesis fresh gas.

[0016] The second-stage outlet cooler is connected to the outlet of the second stage of the ammonia synthesis compressor and is used to perform secondary cooling on the ammonia synthesis fresh gas.

[0017] The ammonia synthesis compressor has three stages, which are connected to the outlet of the second-stage outlet cooler to pressurize the ammonia synthesis fresh gas three times.

[0018] An ammonia synthesis fresh gas heater is connected to the outlet of the second stage of the ammonia synthesis compressor and is used to heat the ammonia synthesis fresh gas with steam to regulate its temperature.

[0019] A backflush gas buffer tank is connected to the outlet of the ammonia synthesis fresh gas heater to allow backflush gas to enter and buffer; and a fly ash filter is connected downstream of the backflush gas buffer tank to use backflush gas from the backflush gas buffer tank to perform backflush dust removal treatment on the gasified synthesis gas.

[0020] Preferably, a backflush gas flow detector and an ammonia synthesis fresh gas heater are installed on the feeding pipe between the second stage of the ammonia synthesis compressor and the ammonia synthesis fresh gas heater. The flow detector is signal-interlocked with the ammonia synthesis fresh gas heater and is used to control the flow rate of the backflush gas.

[0021] Preferably, a temperature detector for detecting the backflush gas temperature is provided at the outlet of the ammonia synthesis fresh gas heater, and the ammonia synthesis fresh gas heater is provided with a steam supply pipe. A backflush gas temperature control valve for controlling the steam flow is provided on the steam supply pipe. The temperature detector is signal-interlocked with the backflush gas temperature control valve and is used to control the temperature of the backflush gas.

[0022] Preferably, the fly ash filter is provided with a differential pressure detection structure, and a backflush gas switch valve is provided on the pipeline between the backflush gas buffer tank and the fly ash filter. The backflush gas switch valve is signal-interlocked with the differential pressure detection structure and is used to control whether the backflush gas is switched on or off.

[0023] Compared with existing technologies, the advantages of this invention are as follows: This invention utilizes a type of gas source, such as ammonia synthesis fresh gas, with an H2 to N2 ratio of approximately 3:1. After multi-stage compression and cooling, it is used as backflushing gas to backflush the fly ash filter. The ammonia synthesis compressor outlet fresh gas pressure is high, approximately 8 MPa. While retaining the original configuration of the pulverized coal gasification waste boiler process for ammonia synthesis, this high-temperature, high-pressure fresh gas is utilized without additional equipment investment. The process is simple and highly reliable. The process includes a backflushing gas buffer tank and multiple temperature, pressure, and flow control interlocks, which helps improve the stability of the backflushing gas. Furthermore, the backflushing gas is non-corrosive to the equipment, which is beneficial for the long-term, stable operation of the fly ash filter. Using ammonia synthesis fresh gas as backflushing gas does not require additional pressurization, reducing compression power consumption. It also eliminates the need for an additional air separation unit for high-pressure nitrogen configuration, and the suitable nitrogen-to-hydrogen ratio reduces additional nitrogen consumption. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the background technology of this invention;

[0025] Figure 2 This is another structural schematic diagram of the background technology of the present invention;

[0026] Figure 3 This is a process flow diagram of an embodiment of the present invention. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] like Figure 3 As shown, the process of using ammonia synthesis fresh gas for fly ash filtration and backflushing in this embodiment includes the following steps:

[0029] The ammonia synthesis fresh gas 1 is pressurized by the first stage C-01 of the ammonia synthesis compressor, then enters the second stage C-02 of the ammonia synthesis compressor after passing through the first stage outlet cooler E-01, and then enters the third stage C-03 of the ammonia synthesis compressor after passing through the second stage outlet cooler E-02.

[0030] The outlet backflush gas pressure reaches 8 MPaG. The flow rate of the backflush gas from the second stage C-02 of the ammonia synthesis compressor to the ammonia synthesis fresh gas heater E-03 is controlled by the air extraction flow control valve FV-01 of the second stage C-02 of the ammonia synthesis compressor. The backflush gas is then heated by the ammonia synthesis fresh gas heater E-03. This stage controls the steam flow rate entering the ammonia synthesis fresh gas heater E-03 by adjusting the backflush gas temperature control valve TV-01, thereby controlling the temperature of the backflush gas at the outlet of the ammonia synthesis fresh gas heater E-03.

[0031] The backflush gas, adjusted to a suitable temperature, then enters the backflush gas buffer tank V-01 for buffering. The outlet is controlled by the backflush gas switch valves X01 to N. The gasified syngas 5 is purified by the fly ash filter S-01 to obtain the purified syngas 6. The backflush gas switch valves X01 to N are adjusted by measuring the pressure difference of the fly ash filter S-01 to periodically purge the fly ash filter S-01 to ensure the dust removal effect.

[0032] The volume ratio of H2 to N2 in the outlet backflush gas 4 is 3:1. Using this backflush gas not only improves the stability of the backflush gas, but also has no corrosive effect on the equipment, which is conducive to the long-term and stable operation of the fly ash filter, and also reduces the additional nitrogen consumption.

[0033] The temperature, flow rate, and differential pressure of the ammonia synthesis fresh gas used as backflush gas are controlled by a coupling regulation system consisting of the extraction flow control valve FV-01, the backflush gas temperature control valve TV-01, and the backflush gas on / off valves X01 to N. The temperature, flow rate, and differential pressure of the backflush gas are also interlocked and controlled as needed to further improve the stability of the backflush gas.

[0034] The system used in the above process for fly ash filtration and backflushing with ammonia synthesis fresh gas includes:

[0035] The first stage C-01 of the ammonia synthesis compressor is used to pressurize the ammonia synthesis fresh gas 1.

[0036] The first-stage outlet cooler E-01 is connected to the outlet of the first-stage C-01 of the ammonia synthesis compressor and is used to cool the ammonia synthesis fresh gas.

[0037] The second stage of the ammonia synthesis compressor, C-02, is connected to the outlet of the first stage outlet cooler, E-01, and is used to repressurize the ammonia synthesis fresh gas.

[0038] The second-stage outlet cooler E-02 is connected to the outlet of the second-stage C-02 of the ammonia synthesis compressor and is used for secondary cooling of the ammonia synthesis fresh gas.

[0039] The ammonia synthesis compressor, section C-03, is connected to the outlet of the section outlet cooler E-02 and is used to pressurize the ammonia synthesis fresh gas three times.

[0040] The ammonia synthesis fresh gas heater E-03 is connected to the outlet of the second stage C-02 of the ammonia synthesis compressor and is used to heat the ammonia synthesis fresh gas with steam to regulate its temperature.

[0041] Backflush gas buffer tank V-01 is connected to the outlet of ammonia synthesis fresh gas heater E-03, allowing backflush gas to enter and be buffered.

[0042] The fly ash filter S-01 is connected downstream of the backflush gas buffer tank V-01 and is used to perform backflush dust removal treatment on the gasified syngas using backflush gas from the backflush gas buffer tank V-01.

[0043] A backflush gas flow detector and an ammonia synthesis fresh gas heater E-03 are installed on the feeding pipe between the second stage C-02 of the ammonia synthesis compressor and the ammonia synthesis fresh gas heater E-03. The flow detector is signal-interlocked with the ammonia synthesis fresh gas heater E-03 and is used to control the flow rate of the backflush gas.

[0044] A temperature detector for detecting the backflush gas temperature is installed at the outlet of the ammonia synthesis fresh gas heater E-03. The ammonia synthesis fresh gas heater E-03 is provided with a steam supply pipe. A backflush gas temperature control valve TV-01 for controlling the steam flow is installed on the steam supply pipe. The temperature detector is signal-interlocked with the backflush gas temperature control valve TV-01 and is used to control the temperature of the backflush gas.

[0045] The fly ash filter S-01 is equipped with a differential pressure detection structure. A backflush gas switch valve X01 to N is installed on the pipeline between the backflush gas buffer tank V-01 and the fly ash filter S-01. The backflush gas switch valve X01 to N is signal-interlocked with the differential pressure detection structure and is used to control whether the backflush gas is switched on or off.

[0046] For current ammonia synthesis processes, compressors are all integrated models of booster and recirculator, that is, the synthesis gas and recirculator gas at the outlet of the booster section are mixed and then pressurized in the compressor. Based on this, this application sets up an ammonia synthesis compressor recirculator section C-04, ammonia synthesis recirculator gas 2, and ammonia synthesis recirculator gas 3. Of course, the booster and recirculator can also be set up separately. Thus, the two outlets listed in this process are only examples. As long as the pressure meets the requirements of the backflushing process, it is acceptable.

[0047] This embodiment utilizes a type of gas source, namely ammonia synthesis fresh gas, with an H2 to N2 ratio of approximately 3:1. After multi-stage compression and cooling, it is used as backflushing gas to backflush the fly ash filter. The fresh gas pressure at the outlet of the ammonia synthesis compressor section meets the requirements of the backflushing process. While retaining the original configuration of the ammonia synthesis unit produced from pulverized coal gasification waste boiler, this high-temperature and high-pressure fresh gas is utilized without additional equipment investment. The process is simple and highly reliable. The process is equipped with a backflushing gas buffer tank and multiple temperature, pressure, and flow control interlocks, which helps improve the stability of the backflushing gas. Furthermore, the backflushing gas is non-corrosive to the equipment, which is beneficial for the long-term and stable operation of the fly ash filter. The ammonia synthesis fresh gas used as backflushing gas does not require additional pressurization, reducing compression power consumption. It also eliminates the need for an additional air separation unit for high-pressure nitrogen configuration, and the nitrogen-hydrogen ratio is suitable, reducing additional nitrogen consumption.

[0048] With a nominal capacity of 2000 tons / day, pulverized coal gasification, using a complete waste boiler process, produces 125660 Nm³ of effective gas. 3 For example, with a daily production capacity of 1500 tons of liquid ammonia, using carbon dioxide as the carrier gas for pulverized coal gasification and an operating pressure of 4.0 MPa, the material balance is as follows:

[0049] Logistics point 1 2 3 4 5 6 Logistics Name Ammonia synthesis fresh gas Ammonia synthesis cycle gas Ammonia synthesis cycle gas Backflush Gasification Synthesis Gas Syngas after dust removal Phase gas phase gas phase gas phase gas phase gas phase gas phase Temperature / °C 30 21.66 43 200 340 335 Pressure / MPag 2.5 18.33 19 8 3.96 3.88 Flow rate / Kg-moL / HR 7585.8 24228.6 24228.6 133.8 6715.0 6848.8 <![CDATA[H2]]> 74.98 72.072 72.072 74.98 26.36 27.31 CO 0.00 0.00 0.00 0.00 57.13 56.02 <![CDATA[CO2]]> 0.00 0.00 0.00 0.00 7.71 7.56 <![CDATA[N2]]> 25.01 24.097 24.097 25.01 0.3 0.78 AR 0.008 0.479 0.479 0.008 0.09 0.09 <![CDATA[CH4]]> 0.002 0.081 0.081 0.002 0.01 0.01 <![CDATA[NH3]]> 0.00 3.271 3.271 0.00 0 0 <![CDATA[H2S]]> 0.00 0.00 0.00 0.00 0.16 0.16 COS 0.00 0.00 0.00 0.00 0.02 0.02 <![CDATA[H2O]]> 0.00 0.00 0.00 0.00 8.22 8.05 .

Claims

1. A method for backflushing fly ash filtration using ammonia synthesis fresh gas, characterized in that, Systems that utilize ammonia synthesis fresh gas for fly ash filtration and backflushing include: The first stage of the ammonia synthesis compressor (C-01) is used to pressurize the ammonia synthesis fresh gas (1) once; A first-stage outlet cooler (E-01) is connected to the outlet of the first stage (C-01) of the ammonia synthesis compressor and is used to cool the ammonia synthesis fresh gas. The second stage of the ammonia synthesis compressor (C-02) is connected to the outlet of the first stage outlet cooler (E-01) and is used to repressurize the ammonia synthesis fresh gas. The second-stage outlet cooler (E-02) is connected to the outlet of the second stage (C-02) of the ammonia synthesis compressor and is used to perform secondary cooling on the ammonia synthesis fresh gas. The ammonia synthesis compressor three-stage (C-03) is connected to the outlet of the second-stage outlet cooler (E-02) and is used to pressurize the ammonia synthesis fresh gas three times. The ammonia synthesis fresh gas heater (E-03) is connected to the outlet of the second stage (C-02) of the ammonia synthesis compressor and is used to heat the ammonia synthesis fresh gas with steam to regulate its temperature. A backflush gas buffer tank (V-01) is connected to the outlet of the ammonia synthesis fresh gas heater (E-03) to allow backflush gas to enter and be buffered; and a fly ash filter (S-01) is connected downstream of the backflush gas buffer tank (V-01) to use the backflush gas from the backflush gas buffer tank (V-01) to perform backflush dust removal treatment on the gasified synthesis gas. Includes the following steps: The ammonia synthesis fresh gas (1) is pressurized by the first stage (C-01) of the ammonia synthesis compressor, then enters the second stage (C-02) of the ammonia synthesis compressor after passing through the first stage outlet cooler (E-01), and then enters the third stage (C-03) of the ammonia synthesis compressor after passing through the second stage outlet cooler (E-02). The pressure of the backflush gas (4) at the outlet reaches ~8 MPaG. The flow rate of the backflush gas from the second stage of the ammonia synthesis compressor (C-02) to the ammonia synthesis fresh gas heater (E-03) is controlled by the air extraction flow control valve (FV-01) of the second stage of the ammonia synthesis compressor (C-02). The backflush gas is then heated by the ammonia synthesis fresh gas heater (E-03). The steam flow rate entering the ammonia synthesis fresh gas heater (E-03) is controlled by adjusting the backflush gas temperature control valve (TV-01), thereby controlling the temperature of the backflush gas at the outlet of the ammonia synthesis fresh gas heater (E-03). The backflush gas, adjusted to a suitable temperature, is then buffered in the backflush gas buffer tank (V-01). The outlet is controlled by the backflush gas switch valve (X01~N). The gasified syngas (5) is purified by the fly ash filter (S-01) to obtain the purified syngas (6). The backflush gas switch valve (X01~N) is adjusted by measuring the pressure difference of the fly ash filter (S-01) to periodically purge the fly ash filter (S-01) to ensure the dust removal effect.

2. The method for fly ash filtration and backflushing using ammonia synthesis fresh gas according to claim 1, characterized in that: The volume ratio of H2 to N2 in the outlet backflush gas (4) is 3:

1.

3. The method for fly ash filtration and backflushing using ammonia synthesis fresh gas according to claim 1, characterized in that: The temperature, flow rate, and pressure difference of the ammonia synthesis fresh gas used as backflush gas are controlled by a coupling control valve (FV-01), a backflush gas temperature control valve (TV-01), and a backflush gas switch valve (X01~N).

4. The method for fly ash filtration and backflushing using ammonia synthesis fresh gas according to any one of claims 1 to 3, characterized in that: A backflush gas flow detector and an ammonia synthesis fresh gas heater (E-03) are installed on the feeding pipe between the second stage of the ammonia synthesis compressor (C-02) and the ammonia synthesis fresh gas heater (E-03). The flow detector is signal-interlocked with the ammonia synthesis fresh gas heater (E-03) and is used to control the flow rate of the backflush gas.

5. The method for fly ash filtration and backflushing using ammonia synthesis fresh gas according to any one of claims 1 to 3, characterized in that: The outlet of the ammonia synthesis fresh gas heater (E-03) is equipped with a temperature detector for detecting the backflush gas temperature. The ammonia synthesis fresh gas heater (E-03) is equipped with a steam supply pipe, and a backflush gas temperature control valve (TV-01) for controlling the steam flow is installed on the steam supply pipe. The temperature detector is signal-interlocked with the backflush gas temperature control valve (TV-01) and is used to control the temperature of the backflush gas.

6. The method for fly ash filtration and backflushing using ammonia synthesis fresh gas according to any one of claims 1 to 3, characterized in that: The fly ash filter (S-01) is equipped with a differential pressure detection structure. A backflush gas switch valve (X01~N) is installed on the pipeline between the backflush gas buffer tank (V-01) and the fly ash filter (S-01). The backflush gas switch valve (X01~N) is signal-interlocked with the differential pressure detection structure and is used to control whether the backflush gas is switched on or off.

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