Gasifier radiation waste boiler system and water vapor circulation method thereof

Abstract

The present application relates to a kind of gasification furnace radiation waste boiler system and its water vapor circulation method, the present application uses waste boiler steam-water density and water flow as the switching trigger condition of natural circulation and forced circulation, successfully realizes the coupling of natural circulation and forced circulation;Under normal conditions, using natural circulation mode, maintain operating economy, once detect abnormal condition (waste boiler density is abnormally low or the flow of waste boiler is abnormally low), will be automatically interlocked and started by suitable parameter transformation boiler water circulating pump, switch to forced circulation mode, realize forced circulation, to cope with high heat load, system blockage and driving condition, driving warm furnace condition, guarantee system safety.

Description

Technical Field

[0001] This invention relates to the field of coal gasification production equipment technology, specifically to a gasifier radiant waste boiler system and its water-steam circulation method. Background Technology

[0002] The radiant waste heat boiler of the gasifier is usually located below the gasifier reaction chamber to recover heat and by-product steam from the high-temperature syngas and high-temperature slag. Its configuration greatly improves the thermal efficiency of the gasification unit.

[0003] There are two main types of water-steam circulation methods in existing gasifier radiant waste boiler systems: most are natural circulation, and a few are forced circulation. For example, the dry pulverized coal waste boiler gasification system with authorization publication number CN207918765U has a tubular structure where the radiant waste boiler is connected to the gasifier reaction chamber at the top and the gasifier quench water bath at the bottom. The steam drum water is sent to the bottom of the tubes by gravity from the downcomer. The tubes receive radiant heat and generate bubbles inside, causing a decrease in density in the tubes and riser. The water-steam circulation is achieved by relying on the density difference between the downcomer and riser, without the need for a pump; this is natural circulation. A coal gasification system with heat recovery function, application publication number CN106010654A, also proposes a heat recovery system including a gasifier radiant waste boiler. The boiler water in the radiant and convective waste boilers can use either natural or forced circulation; however, only one of these two methods can be used.

[0004] Under normal and stable operating conditions, radiant waste heat boilers can meet the steam and water circulation requirements through natural circulation, resulting in good economic efficiency. However, naturally circulating waste heat boilers are less safe in dealing with abnormal operating conditions. Abnormal operating conditions mainly refer to two types: start-up and abnormal heat loads. Before start-up, the gasifier needs to be preheated, i.e., steam is introduced into the steam drum and circulation begins, allowing the entire waste heat boiler system to gradually heat up along a slower temperature rise curve to avoid stress damage caused by sudden temperature changes. However, at this time, the gasifier is in a cold state and lacks the power for natural circulation. Abnormal heat loads may include excessively high furnace temperature, large-scale slag shedding from the inner wall of the waste heat boiler, severe scaling or abnormal blockage in the water circulation pipeline, etc. In these situations, the steam production status of the radiant waste heat boiler deteriorates rapidly, even leading to dry-out or damage, necessitating shutdown, affecting long-term operation, and potentially causing safety accidents. Forced circulation has the advantages of good operational safety, strong resistance to fluctuations, and the ability to handle start-up and preheating conditions, but it requires higher investment and has relatively lower operating economics. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide a gasifier radiant waste boiler system that can meet the requirements of high heat load, system blockage and start-up conditions, while ensuring economic operation and safety under abnormal conditions, in light of the current state of the prior art.

[0006] The second technical problem to be solved by the present invention is to provide a water and steam circulation method for a gasifier radiant waste boiler system, which can maintain the economic efficiency of operation by using natural circulation under normal operating conditions, and achieve forced circulation by automatically interlocking the boiler water circulation pump through parameter changes during start-up and special operating conditions, thereby ensuring the safety of the system.

[0007] The technical solution adopted by the present invention to solve at least one of the above-mentioned technical problems is as follows:

[0008] A gasifier radiant waste boiler system, comprising:

[0009] The radiant waste boiler is composed of tubes, and the space enclosed by the tubes is connected to the gasification chamber of the gasifier.

[0010] The steam drum is connected to the top of the radiant waste boiler via an ascending pipe and to the bottom of the radiant waste boiler via a descending pipe; the steam drum is equipped with a steam production line, a water inlet line, an emergency sewage discharge line, a continuous sewage discharge line, and a start-up steam line;

[0011] A forced circulation pump is connected to a downcomer via a forced circulation bypass, and the forced circulation pump has inlet and outlet pipelines;

[0012] The shut-off valve XV01 is located between the inlet and outlet points of the forced circulation pump in the natural circulation main line of the downcomer.

[0013] The shut-off valve XV02 is located on the forced circulation bypass after the forced circulation pump. The shut-off valve XV02 works in conjunction with the shut-off valve XV01 to switch between natural circulation and forced circulation.

[0014] Waste boiler inlet flow meter FI01 is installed between the forced circulation pump outlet and the radiant waste boiler inlet in the downcomer.

[0015] Density meter DI01 and temperature meter TI01 are installed on the riser pipe at the outlet of the radiant waste boiler to detect abnormal operating conditions of the radiant waste boiler and are interlocked with the opening and closing of shut-off valves XV01 and XV02 and the start and stop of the forced circulation pump.

[0016] A level gauge LI01 is installed on the steam drum;

[0017] Flow meter FI02 and pressure regulating valve PV01 are installed on the steam production line;

[0018] Flow meter FI03 and level regulating valve LV01 are installed on the inlet line;

[0019] The level regulating valve LV02 is located on the emergency drain line;

[0020] Flow meter FI04 and flow regulating valve FV01 are installed on the continuous sewage discharge line;

[0021] The flow meter FI05 and the flow regulating valve FV02 are installed on the start-up steam line.

[0022] Preferably, the steam drum is positioned higher than the radiant waste boiler to provide power for natural circulation.

[0023] A method for water and steam circulation in a gasifier radiant waste boiler system includes the following steps:

[0024] Under normal operating conditions:

[0025] (1) The natural circulation main circuit shut-off valve XV01 is opened;

[0026] (2) Forced circulation bypass shut-off valve XV02 is closed;

[0027] (3) The forced circulation pump is in a stopped state;

[0028] (4) The water vapor circulation of the radiant waste boiler maintains a natural circulation mode;

[0029] Under abnormal operating conditions:

[0030] (1) Abnormal condition one: Relative heat load is high (may be the highest absolute value of heat load in the furnace or abnormally low waste water circulation). Set the radiant waste water outlet density meter DI01 to low alarm and low-low interlock; set the waste water outlet temperature meter TI01 at the same time. Its sensitivity is not as fast as the density meter. Only set the high alarm and do not set the interlock.

[0031] (2) Abnormal condition 2: The flow rate of the radiant waste boiler inlet water meter is low. Set the radiant waste boiler inlet water flow rate meter FI01 low alarm and low-low interlock.

[0032] (3) If any of the above conditions are interlocked, the forced circulation pump will be started, the natural circulation main circuit shut-off valve XV01 will be closed simultaneously, the forced circulation bypass shut-off valve XV02 will be opened, and the forced circulation mode will be started.

[0033] (4) Reset of forced circulation, i.e. return to natural circulation mode, is performed manually after the cause of abnormal working condition is resolved to ensure safety. The operation sequence is to stop the forced circulation pump, open the natural circulation main shut-off valve XV01 simultaneously, and then close the forced circulation bypass shut-off valve XV02 to return to natural circulation mode.

[0034] When switching between natural circulation and forced circulation, the corresponding control method for the steam drum is as follows:

[0035] (1) The pressure of the steam drum is controlled by the pressure control loop PIC, which consists of the steam drum pressure gauge PI01 and the steam drum steam production pressure regulating valve PV01.

[0036] (2) The normal steam drum liquid level is controlled by three impulses, which refer to the steam drum liquid level LI01, the steam drum steam production flow rate FI02 and the steam drum water inlet flow rate FI03, and control the steam drum water inlet liquid level regulating valve LV01; when the liquid level is abnormally high, the emergency drain is started, and the emergency drain liquid level regulating valve LV02 is controlled. The emergency drain line also serves as a channel for the periodic drain of the steam drum.

[0037] (3) The continuous blowdown of the steam drum is controlled by the flow control loop FIC, which consists of the continuous blowdown flow meter FI04 and the continuous blowdown flow regulating valve FV01.

[0038] (4) The start-up steam injection is controlled by the start-up steam flow meter FI05 and the start-up steam flow regulating valve FV02, which form a flow control loop FIC. It is only used for start-up and boiler warm-up, and there is no flow in other operating conditions.

[0039] The method for controlling the start-up of the boiler is as follows:

[0040] (1) Before starting the boiler, the steam drum and radiant waste boiler system should be filled with boiler water and the temperature should be much lower than the normal operating temperature. The steam drum-waste boiler system should be gradually heated to above the critical temperature that will not damage the waste boiler when the gasifier is started, according to the preset heating rate.

[0041] (2) When the natural circulation main shut-off valve XV01 is closed, the forced circulation pump is started, and the forced circulation bypass shut-off valve XV02 is opened, the system is in forced circulation mode. This process is either manually executed or automatically triggered by the low flow interlock of the waste boiler inlet water flow meter FI01.

[0042] (3) Start-up steam is introduced into the steam drum through start-up steam. The selection of the start-up steam volume is related to the preset heating rate and the total water volume of the system. At this time, the steam drum pressure is controlled by PV01 and the steam drum liquid level is controlled by LV02. The liquid level three-impulse control is not put into use for the time being.

[0043] (4) After the system temperature rises to the preset temperature, reduce the amount of steam input for start-up, stabilize the system pressure and temperature, and wait for the gasifier to start up and feed materials.

[0044] (5) After feeding and the gasifier is stable, manually switch to natural circulation mode. The operation process is the same as returning to natural circulation mode after interlocking start of abnormal working conditions.

[0045] Compared with the prior art, the advantages of the present invention are as follows: The present invention uses the steam-water density of the waste boiler and the inlet water flow rate as the switching trigger conditions for natural circulation and forced circulation, and successfully realizes the coupling of natural circulation and forced circulation; under normal operating conditions, the natural circulation mode is adopted to maintain the economic efficiency of operation. Once abnormal conditions are detected (abnormally low waste boiler density or abnormally low inlet waste boiler flow rate), the boiler water circulation pump will be automatically interlocked and started through appropriate parameter changes to switch to forced circulation mode, so as to cope with high heat load, system blockage, start-up conditions, and start-up and boiler warm-up conditions, and ensure system safety. Attached Figure Description

[0046] Figure 1 This is a process flow diagram of an embodiment of the present invention. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0048] like Figure 1 As shown, the gasifier radiant waste boiler system of this embodiment includes:

[0049] The radiation waste boiler 3 is composed of tubes, and the space surrounded by the tubes is connected to the gasification chamber of the gasifier.

[0050] Steam drum 1 is connected to the top of radiant waste boiler 3 via riser pipe 4 and to the bottom of radiant waste boiler 3 via downcomer pipe 2; Steam drum 1 is arranged higher than radiant waste boiler 3 to provide power for natural circulation; Steam drum 1 is equipped with steam production line 7, water inlet line 8, emergency sewage discharge line 9, continuous sewage discharge line 10 and start-up steam line 11.

[0051] Forced circulation pump 5 is connected to downcomer 2 via forced circulation bypass 6, and forced circulation pump 5 has pump inlet and outlet pipelines;

[0052] The shut-off valve XV01 is located between the inlet and outlet points of the forced circulation pump 5 in the natural circulation main circuit of the downcomer 2;

[0053] The shut-off valve XV02 is located on the forced circulation bypass 6 after the forced circulation pump 5. The shut-off valve XV02 works in conjunction with the shut-off valve XV01 to switch between natural circulation and forced circulation.

[0054] The waste boiler inlet flow meter FI01 is located between the outlet of the forced circulation pump 5 in the downcomer 2 and the inlet of the radiant waste boiler 3.

[0055] Density meter DI01 and temperature meter TI01 are installed on the riser pipe 4 at the outlet of the radiant waste pot 3 to detect abnormal operating conditions of the radiant waste pot 3, and are interlocked with the opening and closing of shut-off valves XV01 and XV02 and the start and stop of the forced circulation pump 5.

[0056] A level gauge LI01 is installed on the steam drum 1;

[0057] The flow meter FI02 and the pressure regulating valve PV01 are installed on the steam production line 7;

[0058] The flow meter FI03 and the level regulating valve LV01 are installed on the inlet line 8;

[0059] The level regulating valve LV02 is installed on the emergency drain line 9;

[0060] The flow meter FI04 and the flow regulating valve FV01 are installed on the continuous sewage discharge line 10;

[0061] The flow meter FI05 and the flow regulating valve FV02 are installed on the start-up steam line 11.

[0062] The water-steam circulation method of the gasifier radiant waste boiler system in this embodiment includes the following steps:

[0063] Under normal operating conditions:

[0064] (1) The natural circulation main circuit shut-off valve XV01 is opened;

[0065] (2) Forced circulation bypass 6 shut-off valve XV02 is closed;

[0066] (3) Forced circulation pump 5 is in a stopped state;

[0067] (4) The water vapor circulation of the radiant waste boiler 3 maintains a natural circulation mode;

[0068] Under abnormal operating conditions:

[0069] (1) Abnormal condition one: Relative heat load is high (may be the highest absolute value of heat load in the furnace or abnormally low circulating water in the waste boiler). Set the low alarm of the radiant waste boiler 3 outlet water density meter DI01 and low-low interlock; set the radiant waste boiler 3 outlet water temperature meter TI01 at the same time. Its sensitivity is not as fast as the density meter. Only set the high alarm and do not set the interlock.

[0070] (2) Abnormal condition 2: The inlet flow meter of the radiant waste boiler 3 is low. Set the radiant waste boiler inlet flow meter FI01 low alarm and low-low interlock.

[0071] (3) If any of the above conditions are interlocked, the forced circulation pump 5 will be started, the natural circulation main circuit shut-off valve XV01 will be closed simultaneously, the forced circulation bypass shut-off valve XV02 will be opened, and the forced circulation mode will be started.

[0072] (4) Reset of forced circulation, i.e. return to natural circulation mode, is performed manually after the cause of abnormal working condition is resolved to ensure safety. The operation sequence is to stop forced circulation pump 5, open natural circulation main shut-off valve XV01 simultaneously, and then close forced circulation bypass shut-off valve XV02 to return to natural circulation mode.

[0073] When switching between natural circulation and forced circulation, the corresponding control method for steam drum 1 is as follows:

[0074] (1) The pressure of steam drum 1 is controlled by a pressure control loop PIC consisting of steam drum pressure gauge PI01 and steam drum steam production pressure regulating valve PV01.

[0075] (2) The normal liquid level of steam drum 1 is controlled by three impulses, which refer to the steam drum liquid level LI01, the steam drum steam production flow rate FI02 and the steam drum water inlet flow rate FI03, and control the steam drum water inlet liquid level regulating valve LV01; when the liquid level is abnormally high, the emergency sewage discharge is started, and the emergency sewage discharge liquid level regulating valve LV02 is controlled. The emergency sewage discharge line 9 also serves as the channel for the periodic sewage discharge of the steam drum.

[0076] (3) The continuous sewage discharge of the steam drum 1 is controlled by the flow control loop FIC, which consists of the continuous sewage flow meter FI04 and the continuous sewage flow regulating valve FV01.

[0077] (4) The start-up steam injection is controlled by the start-up steam flow meter FI05 and the start-up steam flow regulating valve FV02, which form a flow control loop FIC. It is only used for start-up and boiler warm-up, and there is no flow in other operating conditions.

[0078] The method for controlling the start-up heater is as follows:

[0079] (1) Before starting the boiler, the steam drum 1 and the radiant waste boiler system are filled with boiler water and the temperature is much lower than the normal operating temperature. The steam drum-waste boiler system must be gradually heated to above the critical temperature that will not damage the waste boiler when the gasifier is started, according to the preset heating rate.

[0080] (2) The natural circulation main shut-off valve XV01 is closed, the forced circulation pump 5 is started, the forced circulation bypass shut-off valve XV02 is opened, and the system is in forced circulation mode. This process is either manually executed or automatically triggered by the low flow interlock of the waste boiler inlet water flow meter FI01.

[0081] (3) Start-up steam is introduced into the steam drum through start-up steam. The selection of the start-up steam volume is related to the preset heating rate and the total water volume of the system. At this time, the steam drum pressure is controlled by PV01 and the steam drum liquid level is controlled by LV02. The liquid level three-impulse control is not put into use for the time being.

[0082] (4) After the system temperature rises to the preset temperature, reduce the amount of steam input for start-up, stabilize the system pressure and temperature, and wait for the gasifier to start up and feed materials.

[0083] (5) After feeding and the gasifier is stable, manually switch to natural circulation mode. The operation process is the same as returning to natural circulation mode after interlocking start of abnormal working conditions.

[0084] This embodiment uses the steam-water density at the waste boiler outlet and the inlet water flow rate as the switching trigger conditions for natural circulation and forced circulation, successfully achieving the coupling of natural circulation and forced circulation. Under normal operating conditions, the natural circulation mode is adopted to maintain operational economy. Once abnormal conditions are detected (abnormally low waste boiler outlet density or abnormally low waste boiler inlet flow rate), the boiler water circulation pump will be automatically interlocked and started through appropriate parameter changes to switch to forced circulation mode, thereby achieving forced circulation to cope with high heat load, system blockage, start-up conditions, and start-up warm-up conditions, ensuring system safety.

[0085] The above scheme is further described in detail below with reference to a practical production case. This practical production case is a radiant waste boiler system used for fluidized bed pulverized coal gasification. The gasification system operates at a pressure of 4.0 MPag and a reaction temperature of 1400–1600℃. The high-temperature syngas and molten slag generated in the reaction are processed through the radiant waste boiler system to recover heat, producing 9.8 MPa high-pressure saturated steam as a byproduct. The radiant waste boiler system operates at a pressure of 9.8 MPa, with an operating temperature corresponding to a saturation temperature of 310℃. The waste boiler influent water flow rate is 303 t / h, the steam production rate is 45 t / h, and the normal steam content at the waste boiler outlet is 15%, corresponding to a gas-liquid mixture density of 252 kg / m³. 3 Based on calculations of heat load and equipment safety, a mixed density of 208 kg / m³ corresponding to a steam content of 20% is set. 3 To set a high alarm threshold, the mixing density corresponding to a vapor content of 25% is set at 177 kg / m³. 3 The interlock value for switching from natural circulation to forced circulation is set at 225 t / h for waste boiler water inlet as the low alarm value, and 180 t / h for the switching interlock value. Considering the natural circulation state, the waste boiler water circulation rate is directly related to the gasifier load and corresponding heat load. The interlock action for switching from natural circulation to forced circulation is mainly triggered by density parameters, while the flow rate interlock value only takes effect when the gasifier load is greater than 90%. Specifically:

[0086] Under normal operating conditions:

[0087] (1) The natural circulation main circuit shut-off valve XV01 is opened;

[0088] (2) Forced circulation bypass 6 shut-off valve XV02 is closed;

[0089] (3) Forced circulation pump 5 is in a stopped state;

[0090] (4) The water vapor circulation of the radiant waste boiler 3 maintains a natural circulation mode;

[0091] Under abnormal operating conditions:

[0092] (1) Abnormal condition one: Relative heat load is high (possibly due to the highest absolute value of the heat load in the furnace or abnormally low circulating water in the waste heat boiler), setting the radiant waste heat boiler 3 outlet water density meter DI01 low alarm (208kg / m³). 3 Low-low interlocking (177kg / m) 3 The TI01 thermometer for the outlet water of the radiant waste boiler 3 is set synchronously. Its sensitivity is not as fast as that of the density meter. Only a high alarm is set, and no interlock is set.

[0093] (2) Abnormal condition 2: The inlet flow meter of the radiant waste boiler 3 is low. Set the radiant waste boiler inlet flow meter FI01 low alarm (225t / h) and low low interlock (180t / h). This condition only takes effect when the gasifier load exceeds 90%.

[0094] (3) If any of the above conditions are interlocked, the forced circulation pump 5 will be started, the natural circulation main circuit shut-off valve XV01 will be closed simultaneously, the forced circulation bypass shut-off valve XV02 will be opened, and the forced circulation mode will be started.

[0095] (4) Reset of forced circulation, i.e. return to natural circulation mode, is performed manually after the cause of abnormal working condition is resolved to ensure safety. The operation sequence is to stop forced circulation pump 5, open natural circulation main shut-off valve XV01 simultaneously, and then close forced circulation bypass shut-off valve XV02 to return to natural circulation mode.

[0096] When switching between natural circulation and forced circulation, the corresponding control method for steam drum 1 is as follows:

[0097] (1) The pressure of steam drum 1 is controlled by a pressure control loop PIC consisting of steam drum pressure gauge PI01 and steam drum steam production pressure regulating valve PV01.

[0098] (2) The normal liquid level of steam drum 1 is controlled by three impulses, which refer to the steam drum liquid level LI01, the steam drum steam production flow rate FI02 and the steam drum water inlet flow rate FI03, and control the steam drum water inlet liquid level regulating valve LV01; when the liquid level is abnormally high, the emergency sewage discharge is started, and the emergency sewage discharge liquid level regulating valve LV02 is controlled. The emergency sewage discharge line 9 also serves as the channel for the periodic sewage discharge of the steam drum.

[0099] (3) The continuous sewage discharge of the steam drum 1 is controlled by the flow control loop FIC, which consists of the continuous sewage flow meter FI04 and the continuous sewage flow regulating valve FV01.

[0100] (4) The start-up steam injection is controlled by the start-up steam flow meter FI05 and the start-up steam flow regulating valve FV02, which form a flow control loop FIC. It is only used for start-up and boiler warm-up, and there is no flow in other operating conditions.

[0101] The method for controlling the start-up heater is as follows:

[0102] (1) Before starting the boiler, the steam drum 1 and the radiant waste boiler system are filled with boiler water and the temperature is much lower than the normal operating temperature. The steam drum-waste boiler system must be gradually heated to above the critical temperature that will not damage the waste boiler when the gasifier is started, according to the preset heating rate.

[0103] (2) The natural circulation main shut-off valve XV01 is closed, the forced circulation pump 5 is started, the forced circulation bypass shut-off valve XV02 is opened, and the system is in forced circulation mode. This process is either manually executed or automatically triggered by the low flow interlock of the waste boiler inlet water flow meter FI01.

[0104] (3) Start-up steam is introduced into the steam drum through start-up steam. The selection of the start-up steam volume is related to the preset heating rate and the total water volume of the system. At this time, the steam drum pressure is controlled by PV01 and the steam drum liquid level is controlled by LV02. The liquid level three-impulse control is not put into use for the time being.

[0105] (4) After the system temperature rises to the preset temperature, reduce the amount of steam input for start-up, stabilize the system pressure and temperature, and wait for the gasifier to start up and feed materials.

[0106] (5) After feeding and the gasifier is stable, manually switch to natural circulation mode. The operation process is the same as returning to natural circulation mode after interlocking start of abnormal working conditions.

Claims

1. A gasifier radiant waste boiler system, characterized in that... include: The radiant waste boiler is composed of tubes, and the space enclosed by the tubes is connected to the gasification chamber of the gasifier. The steam drum is connected to the top of the radiant waste boiler via an ascending pipe and to the bottom of the radiant waste boiler via a descending pipe; the steam drum is equipped with a steam production line, a water inlet line, an emergency sewage discharge line, a continuous sewage discharge line, and a start-up steam line; A forced circulation pump is connected to a downcomer via a forced circulation bypass, and the forced circulation pump has inlet and outlet pipelines; The shut-off valve XV01 is located between the inlet and outlet points of the forced circulation pump in the natural circulation main line of the downcomer. The shut-off valve XV02 is located on the forced circulation bypass after the forced circulation pump. The shut-off valve XV02 works in conjunction with the shut-off valve XV01 to switch between natural circulation and forced circulation. Waste boiler inlet flow meter FI01 is installed between the forced circulation pump outlet and the radiant waste boiler inlet in the downcomer. Density meter DI01 and temperature meter TI01 are installed on the riser pipe at the outlet of the radiant waste boiler to detect abnormal operating conditions of the radiant waste boiler and are interlocked with the opening and closing of shut-off valves XV01 and XV02 and the start and stop of the forced circulation pump. A level gauge LI01 is installed on the steam drum; Flow meter FI02 and pressure regulating valve PV01 are installed on the steam production line; Flow meter FI03 and level regulating valve LV01 are installed on the inlet line; The level regulating valve LV02 is located on the emergency drain line; Flow meter FI04 and flow regulating valve FV01 are installed on the continuous sewage discharge line; The flow meter FI05 and the flow regulating valve FV02 are installed on the start-up steam line.

2. The gasifier radiant waste boiler system according to claim 1, characterized in that: The steam drum is positioned above the radiant waste boiler to provide power for natural circulation.

3. A method for water and steam circulation in a gasifier radiant waste boiler system, characterized in that: Using the gasifier radiant waste boiler system as described in claim 1 or 2, Under normal operating conditions: (1) The natural circulation main circuit shut-off valve XV01 is opened; (2) Forced circulation bypass shut-off valve XV02 is closed; (3) The forced circulation pump is in a stopped state; (4) The water vapor circulation of the radiant waste boiler maintains a natural circulation mode; Under abnormal operating conditions: (1) Abnormal condition one: Relative heat load is high, set the radiant waste water density meter DI01 to low alarm and low-low interlock; simultaneously set the waste water temperature meter TI01, which only sets high alarm and does not set interlock. (2) Abnormal condition 2: The flow rate of the radiant waste boiler inlet water meter is low. Set the radiant waste boiler inlet water flow rate meter FI01 to low alarm and low-low interlock. (3) If any of the above conditions are interlocked, the forced circulation pump will be started, the natural circulation main circuit shut-off valve XV01 will be closed simultaneously, the forced circulation bypass shut-off valve XV02 will be opened, and the forced circulation mode will be started. (4) Reset of forced circulation, i.e. return to natural circulation mode, is performed manually after the cause of abnormal working condition is resolved to ensure safety. The operation sequence is to stop the forced circulation pump, open the natural circulation main shut-off valve XV01 simultaneously, and then close the forced circulation bypass shut-off valve XV02 to return to natural circulation mode.

4. The water-steam circulation method for the gasifier radiant waste boiler system according to claim 3, characterized in that: When switching between natural circulation and forced circulation, the corresponding control method for the steam drum is as follows: (1) The pressure of the steam drum is controlled by the pressure control loop PIC, which consists of the steam drum pressure gauge PI01 and the steam drum steam production pressure regulating valve PV01. (2) The normal steam drum liquid level is controlled by three impulses, which refer to the steam drum liquid level LI01, the steam drum steam production flow rate FI02 and the steam drum water inlet flow rate FI03, and control the steam drum water inlet liquid level regulating valve LV01; when the liquid level is abnormally high, the emergency drainage is started, and the emergency drainage liquid level regulating valve LV02 is controlled. The emergency drainage line also serves as the channel for the regular drainage of the steam drum. (3) The continuous blowdown of the steam drum is controlled by the flow control loop FIC, which consists of the continuous blowdown flow meter FI04 and the continuous blowdown flow regulating valve FV01; (4) The start-up steam injection is controlled by the start-up steam flow meter FI05 and the start-up steam flow regulating valve FV02, which form a flow control loop FIC. It is only used for start-up and boiler warm-up, and there is no flow in other operating conditions.

5. The water-steam circulation method for the gasifier radiant waste boiler system according to claim 4, characterized in that: The method for controlling the start-up of the boiler is as follows: (1) Before starting the boiler, the steam drum and the radiant waste boiler system are filled with boiler water and the temperature is much lower than the normal operating temperature. The steam drum-waste boiler system must be gradually heated to above the critical temperature that will not damage the waste boiler when the gasifier is started, according to the preset heating rate. (2) When the natural circulation main shut-off valve XV01 is closed, the forced circulation pump is started, and the forced circulation bypass shut-off valve XV02 is opened, the system is in forced circulation mode. This process is either manually executed or automatically triggered by the low flow interlock of the waste boiler inlet water flow meter FI01. (3) Start-up steam is introduced into the steam drum through start-up steam. The selection of the start-up steam volume is related to the preset heating rate and the total water volume of the system. At this time, the steam drum pressure is controlled by PV01 and the steam drum liquid level is controlled by LV02. The liquid level three-impulse control is not put into use for the time being. (4) After the system temperature rises to the preset temperature, reduce the amount of steam input for start-up appropriately, control the system pressure and temperature to stabilize, and wait for the gasifier to start up and feed materials. (5) After feeding and the gasifier is stable, manually switch to natural circulation mode. The operation process is the same as returning to natural circulation mode after interlocking start of abnormal working conditions.

Images