A pneumatic feedback control type liquid level controller for a marine shell and tube heater

Abstract

The utility model relates to a kind of for marine shell and tube heater pneumatic feedback control type liquid level controller, including mechanical liquid level detection module, pneumatic control module and execution adjustment module, through standardization interface and the butt joint of existing shell and tube heater;Mechanical liquid level detection module includes float ball detection component, float ball detection component includes float ball and vertical guide sleeve, float ball is arranged in vertical guide sleeve;Two flow-through holes are set in the lateral wall of vertical guide sleeve;Pneumatic control module is installed in explosion-proof housing, mechanical displacement signal is converted into the pneumatic signal of drivable actuating mechanism;Execution adjustment module is added on the pipeline of condensate outlet of shell and tube heater by standardization flange, and condensate discharge is adjusted by ZJHP pneumatic single seat regulating valve to control liquid level.The utility model is driven only by compressed air, realizes condensate liquid level accurate control, improves heating efficiency and energy recovery, and is suitable for the safe energy-saving reconstruction of marine shell and tube heater.

Description

Technical Field

[0001] This utility model relates to the field of ship heating equipment modification technology, and in particular to a pneumatic feedback control type liquid level controller for ship shell-and-tube heaters, which is especially suitable for dangerous areas of ships. Background Technology

[0002] Many existing shell-and-tube heaters on ships (such as tank cleaning water heaters and fuel oil heaters) are not equipped with dedicated liquid level control devices when they leave the factory, and rely solely on simple steam trap assemblies for condensate discharge. This presents the following key problems in actual operation:

[0003] (1) Significant safety hazards in hazardous areas: Traditional electronic liquid level controllers are prone to generating sparks in flammable and explosive environments, which does not meet the safety requirements of the IMO SOLAS Convention for equipment in hazardous areas.

[0004] (2) Liquid level loss leads to multiple losses: when the liquid level is too low, steam waste is serious, with an annual steam waste of 500-1500 tons; when the liquid level is too high, the heat exchange area is reduced by 40%-60%, and the outlet temperature of the heated medium cannot reach the design value.

[0005] (3) Lack of energy recovery: High-temperature condensate is discharged directly, and 15%-20% of the sensible heat of steam is not utilized.

[0006] Therefore, there is an urgent need for a liquid level controller that can be installed independently, is mechanically and pneumatically driven, and has a high explosion-proof rating, to solve the liquid level control problem of existing shell-and-tube heaters in ships. Utility Model Content

[0007] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a pneumatic feedback control type liquid level controller for ship shell-and-tube heaters. This intrinsically safe liquid level controller does not require modification of the original heater structure, achieves precise control of condensate level, and has high control accuracy. It also improves system reliability, realizes condensate waste heat recovery, and reduces steam consumption.

[0008] The purpose of this utility model is achieved as follows:

[0009] A pneumatic feedback control type liquid level controller for ship shell-and-tube heaters includes a mechanical liquid level detection module, a pneumatic control module, and an execution adjustment module, all integrated in the same movable explosion-proof housing, and interfaced with existing shell-and-tube heaters via a standardized interface.

[0010] The shell-and-tube heater has multiple heating tubes inside. The side of the shell-and-tube heater has two through holes for docking with an add-on liquid level controller. The through holes are equipped with mounting flanges. The bottom of the shell-and-tube heater has a condensate outlet.

[0011] The mechanical liquid level detection module includes a float detection assembly, which is connected to a shell-and-tube heater via a standardized flange. The float detection assembly includes a float, a vertical guide sleeve, a float hinge, a flow hole, a connecting flange, and a displacement arm. The float is installed inside the vertical guide sleeve. Two flow holes are opened on the side wall of the vertical guide sleeve. The float is connected to one end of the displacement arm via the float hinge, and the other end of the displacement arm is connected to a controller. The float hinge is located inside the vertical guide sleeve. A horizontal branch pipe is provided at the top of the vertical guide sleeve and connected to the controller. The displacement arm is installed inside the horizontal branch pipe.

[0012] The pneumatic control module is installed inside the explosion-proof housing and converts the mechanical displacement signal into a pneumatic signal that can drive the actuator.

[0013] The pneumatic control module includes a pneumatic positioner, a pneumatic controller A, a pneumatic controller B, a pneumatic amplifier A, a pneumatic amplifier B, and a bellows. The pneumatic controller A includes an eccentric cam A, a roller A, a feedback rocker A, a lever A, and a baffle A. The pneumatic controller B includes an eccentric cam B, a roller B, a feedback rocker B, a lever B, and a baffle B. The central axis of the eccentric cam A is connected to one end of the feedback rocker A, and the other end of the feedback rocker A is connected to one end of the displacement arm. The outer edge of the cam of the eccentric cam A is provided with a sliding matching roller A. The roller A is mounted on the lever A. The bottom of the lever A is provided with a baffle A. One side of the baffle A is provided with a pneumatic amplifier A. The nozzle A of the pneumatic amplifier A is aligned with the baffle A. The pneumatic amplifier A is also provided with a balance throttling orifice A.

[0014] The output port of the pneumatic amplifier A is connected to one end of a bellows, and the other end of the bellows is welded to the top of the lever C. The bottom of the lever C is connected to the lever B, and a baffle B is connected below the lever C. A pneumatic amplifier B is provided on the other side of the baffle B opposite to the lever B. The nozzle B of the pneumatic amplifier B is aligned with the baffle B. The pneumatic amplifier B is also provided with a balance throttling orifice B. The pneumatic amplifier B is connected to a ZJHP pneumatic single-seat regulating valve to drive the air-driven valve to open.

[0015] The lever B is equipped with a roller B, which is slidably disposed on the outer edge of the eccentric cam B. The central axis of the eccentric cam B is connected to one end of the feedback rocker arm B, and the other end of the feedback rocker arm B is connected to the valve core of the ZJHP pneumatic single-seat regulating valve. The ZJHP pneumatic single-seat regulating valve is also connected to a pneumatic positioner.

[0016] The execution and regulation module is installed on the condensate outlet pipeline of the shell and tube heater through a standardized flange without changing the original pipeline route. The execution and regulation module includes a ZJHP pneumatic single-seat regulating valve, which is used to regulate the condensate discharge to control the liquid level.

[0017] Furthermore, a connecting flange is provided at the flow hole, which is sealed to the mounting flange on the side wall of the shell-and-tube heater by a graphite gasket resistant to 120°C, without the need for welding.

[0018] Furthermore, stainless steel limiting blocks are provided at the upper and lower ends of the vertical guide sleeve to limit the float stroke, corresponding to liquid levels from 0 to 2 / 5H, which is compatible with the shell height of the shell-and-tube heater.

[0019] Furthermore, a vent plug is provided at the bottom of the vertical guide sleeve.

[0020] Furthermore, the pneumatic positioner is connected to the controller, and the ZJHP pneumatic single-seat regulating valve is connected to the condensate outlet pipeline of the shell-and-tube heater.

[0021] Furthermore, the ZJHP pneumatic single-seat regulating valve includes a valve body structure, a sealing design, and an actuator;

[0022] The ZJHP pneumatic single-seat regulating valve has a stainless steel valve body and a V-shaped or parabolic valve core. Its flow characteristics are linear, which is suitable for linear liquid level control requirements.

[0023] The ZJHP pneumatic single-seat regulating valve has standardized flanges at both ends of its valve body, which are consistent with the flange specifications of the condensate outlet pipeline of the shell-and-tube heater. The valve is sealed to the condensate outlet pipeline through 120℃ resistant fluororubber gaskets.

[0024] Furthermore, the nominal diameter of the valve body of the ZJHP pneumatic single-seat regulating valve is DN25-DN50, and the valve seat is made of hard alloy weld overlay, which is resistant to erosion and corrosion; the sealing design of the ZJHP pneumatic single-seat regulating valve adopts a dual sealing structure of soft seal and hard seal, the upper valve cover of the ZJHP pneumatic single-seat regulating valve adopts bellows seal, and the valve core and valve seat sealing surface of the ZJHP pneumatic single-seat regulating valve adopt a combination of fluororubber and hard alloy.

[0025] Furthermore, the execution adjustment module also includes a manual emergency mechanism: a manual operation handwheel is provided on the top of the execution mechanism, which is connected to the push rod through a worm gear transmission; when the gas source is interrupted, turning the handwheel can directly adjust the valve core opening; an electrostatic grounding terminal is provided next to the handwheel, which is connected to the shell of the shell-and-tube heater through a copper core wire with a cross-sectional area ≥2.5mm², with a grounding resistance ≤4Ω, to avoid static electricity accumulation caused by condensate flow, without the need for an additional independent grounding device.

[0026] Compared with the prior art, the beneficial effects of this utility model are:

[0027] This invention provides a pneumatic feedback control type liquid level controller for ship shell-and-tube heaters. It connects to the original heater via a standardized flange, requires no electrical components, and is driven solely by compressed air to achieve precise control of condensate levels. This invention solves the problem of liquid level control in hazardous areas, improves heating efficiency and energy recovery, and is suitable for the safety and energy-saving retrofitting of ship shell-and-tube heaters. It has the following specific advantages:

[0028] (1) No modification required, strong compatibility: The installation cycle is greatly shortened by standardized flange connection;

[0029] (2) Intrinsically safe and suitable for hazardous areas: No electrical components, and meets ATEX explosion-proof standards;

[0030] (3) Precise liquid level control: control accuracy ≤ ±10mm, steam consumption reduced by 20%-22%;

[0031] (4) High reliability and easy maintenance: greatly reduces failures, and the modular design facilitates maintenance;

[0032] (5) Synergistic energy saving and waste heat recovery: The efficiency of sensible heat recovery of condensate is greatly improved;

[0033] (6) Strong compliance: It complies with the IMO SOLAS Convention, MARPOL Annex VI and classification society certification requirements. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the shell-and-tube heater of this utility model.

[0035] Figure 2 This is a schematic diagram of the heating tube of the shell-and-tube heater of this utility model.

[0036] Figure 3 This is a schematic diagram of the installation of the additive liquid level controller of this utility model.

[0037] Figure 4 This is a schematic diagram of the structure of the add-on liquid level controller of this utility model.

[0038] Figure 5 This is a comparative schematic diagram of the swing of the displacement arm of this utility model.

[0039] Figure 6 This is a schematic diagram of the principle of the add-on liquid level controller of this utility model.

[0040] in:

[0041] Shell-and-tube heater 1, heating tube 1.1, mounting flange 1.2, condensate outlet 1.3, float detection assembly 2, float 2.1, vertical guide sleeve 2.2, float hinge 2.3, flow hole 2.4, connecting flange 2.5, displacement arm 2.6, vent plug 2.7, controller 3, ZJHP pneumatic single-seat regulating valve 4, pneumatic positioner 5, pneumatic controller A6, eccentric cam A6.1, roller A6.2, feedback lever A6.3, lever A6.4, baffle A6.5, pneumatic controller B7, eccentric cam B7.1, roller B7.2, feedback lever B7.3, lever B7.4, baffle B7.5, lever C7.6, pneumatic amplifier A8, nozzle A8.1, balance throttle orifice A8.2, pneumatic amplifier B9, nozzle B9.1, balance throttle orifice B9.2, bellows 10. Detailed Implementation

[0042] To better understand the technical solution of this utility model, a detailed description will be provided below in conjunction with relevant illustrations. It should be understood that the specific embodiments described below are not intended to limit the specific implementation of the technical solution of this utility model, but are merely possible implementations of the technical solution of this utility model. It should be noted that the descriptions of the positional relationships of the components herein, such as component A being located above component B, are based on the relative positions of the components in the illustrations and are not intended to limit the actual positional relationships of the components. Example 1

[0043] See Figures 1-6 , Figure 4 A schematic diagram of the installation of a pneumatic feedback control type liquid level controller for a ship's shell-and-tube heater is shown in Embodiment 1. As shown in the figure, the pneumatic feedback control type liquid level controller for a ship's shell-and-tube heater in Embodiment 1 is an independent modular structure, including a mechanical liquid level detection module, a pneumatic control module, and an execution adjustment module, all integrated in the same movable explosion-proof housing. It interfaces with the existing shell-and-tube heater 1 through a standardized interface, requiring only 0.4-0.6MPa marine compressed air for operation, and has no electrical components.

[0044] The movable explosion-proof housing is made of cast aluminum and integrates the mechanical liquid level detection module, pneumatic control module, and actuator adjustment module. It is equipped with casters with brakes at the bottom (load capacity ≥ 500 kg) for easy movement and positioning in the confined space of a ship. The housing joints are designed with explosion-proof surfaces (gap ≤ 0.15 mm, length ≥ 25 mm), and the cable interface uses explosion-proof glands, which meet Exd explosion-proof requirements and are not structurally related to the existing shell-and-tube heater 1. The explosion-proof housing has a maintenance window on the side with a cover plate secured by explosion-proof bolts, which facilitates the maintenance of internal pneumatic components without disassembling the entire controller.

[0045] The shell-and-tube heater 1 has multiple heating tubes 1.1 inside. The side of the shell-and-tube heater 1 has two through holes for docking with the added liquid level controller. The through holes are equipped with mounting flanges 1.2. The bottom of the shell-and-tube heater 1 is equipped with a condensate outlet 1.3.

[0046] The mechanical liquid level detection module includes a float detection component 2, which is connected to the shell-and-tube heater 1 through a standardized flange. It does not require modification of the original equipment, converts changes in condensate level into mechanical displacement signals, and also has a liquid level visualization observation function.

[0047] The float detection assembly 2 includes a float 2.1 and a vertical guide sleeve 2.2. The float 2.1 is installed inside the vertical guide sleeve 2.2. Two flow holes 2.4 are opened on the side wall of the vertical guide sleeve 2.2 to ensure that condensate can freely enter and exit, and the float changes synchronously with the liquid level in the original heater. A connecting flange 2.5 is provided at the flow hole 2.4, which is sealed to the mounting flange 1.2 on the side wall of the shell-and-tube heater 1 through a graphite gasket resistant to 120℃, without welding. The bottom end of the vertical guide sleeve 2.2 extends to 100mm from the bottom of the shell side of the shell-and-tube heater 1. Stainless steel limiting blocks are provided at the upper and lower ends of the vertical guide sleeve 2.2 to limit the float stroke, corresponding to the liquid level from 0 to 2 / 5H, which is adapted to the shell side height of the shell-and-tube heater 1.

[0048] The float detection assembly 2 further includes a float hinge 2.3, a flow hole 2.4, a connecting flange 2.5, a displacement arm 2.6, and a vent plug 2.7. The float 2.1 and the vertical guide sleeve 2.2 have the same structure as in embodiment 1. The difference is that the float 2.1 is connected to one end of the displacement arm 2.6 through the float hinge 2.3, and the other end of the displacement arm 2.6 is connected to the controller 3. The float hinge 2.3 is set inside the vertical guide sleeve 2.2, and the top of the vertical guide sleeve 2.2 is provided with a horizontal branch pipe connected to the controller 4. The displacement arm 2.6 is set inside the horizontal branch pipe.

[0049] The bottom of the vertical guide sleeve 2.2 is provided with a drain plug 2.7.

[0050] The float 2.1 is a hollow float made of 316L stainless steel with a diameter of 120-180mm and a wall thickness of 3mm. It is resistant to high temperature of 120℃, seawater, and condensation corrosion. The vertical guide sleeve 2.2 is made of 316L stainless steel, and the inner diameter of the vertical guide sleeve 2.2 is 5-8mm larger than the inner diameter of the float 2.1.

[0051] The vertical guide sleeve 2.2 has a transparent borosilicate glass section in the middle, which is 200mm long, can withstand a high temperature of 120℃, and has an explosion-proof rating of Ex d IIB T4. It can directly observe the position of the float, replacing the function of the traditional liquid level sight glass, without the need for additional observation components.

[0052] The pneumatic control module includes a pneumatic positioner 5, a pneumatic controller A6, a pneumatic controller B7, a pneumatic amplifier A8, a pneumatic amplifier B9, and a bellows 10. The pneumatic controller A6 includes an eccentric cam A6.1, a roller A6.2, a feedback lever A6.3, a lever A6.4, and a baffle A6.5. The pneumatic controller B7 includes an eccentric cam B7.1, a roller B7.2, a feedback lever B7.3, a lever B7.4, and a baffle B7.5. The central shaft of the eccentric cam A6.1 is connected to the feedback... One end of the rocker arm A6.3 is connected to the other end of the feedback rocker arm A6.3, and the outer edge of the eccentric cam A6.1 is provided with a sliding matching roller A6.2. The roller A6.2 is set on the lever A6.4, and the bottom of the lever A6.4 is provided with a baffle A6.5. A pneumatic amplifier A8 is provided on one side of the baffle A6.5. The nozzle A8.1 of the pneumatic amplifier A8 is aligned with the baffle A6.5, and the pneumatic amplifier A8 is also provided with a balance throttle orifice A8.2.

[0053] The output port of the pneumatic amplifier A8 is connected to one end of the bellows 10, and the other end of the bellows 10 is welded to the top of the lever C7.6. The bottom of the lever C7.6 is connected to the lever B7.4, and a baffle B7.5 is connected below the lever C7.6. A pneumatic amplifier B9 is provided on the other side of the baffle B7.5 opposite to the lever B7.4. The nozzle B9.1 of the pneumatic amplifier B9 is aligned with the baffle B7.5. The pneumatic amplifier B9 is also provided with a balance throttling orifice B9.2. The pneumatic amplifier B9 is connected to the ZJHP pneumatic single-seat regulating valve 4 to drive the air-driven valve to open.

[0054] The lever B7.4 is provided with a roller B7.2, which is slidably disposed on the outer edge of the eccentric cam B7.1. The central axis of the eccentric cam B7.1 is connected to one end of the feedback rocker arm B7.3, and the other end of the feedback rocker arm B7.3 is connected to the valve core of the ZJHP pneumatic single-seat regulating valve 4. The ZJHP pneumatic single-seat regulating valve 4 is also connected with a pneumatic positioner 5.

[0055] The pneumatic positioner 5 is connected to the controller 3, and the ZJHP pneumatic single-seat regulating valve 4 is connected to the condensate outlet pipeline of the shell-and-tube heater 1.

[0056] Control logic:

[0057] 1. When the liquid level rises or falls, the control feedback lever A moves;

[0058] 2. The feedback lever A is fixed on the central axis of the eccentric cam A, and the vertical displacement is converted into the rotation of the cam's central axis;

[0059] 3. The rotation of the central shaft is converted into the rotation of the eccentric cam, which changes the displacement of baffle A;

[0060] 4. By adjusting the distance between the baffle A and the nozzle A, the pressure of the control air circuit can be adjusted to be between 0.1 bar and 0.2 bar.

[0061] 5. 0.1~0.2 bar control gas is fed back to the pneumatic positioner;

[0062] 6. Control the air-controlled bellows displacement with 0.1~0.2 bar.

[0063] 7. The bellows is welded to one end of the lever C. The expansion and contraction of the gas in the bellows causes a displacement in its length. The distance between the nozzle B and the baffle B driving the gas is adjusted by lever C.

[0064] 8. When the distance between nozzle B and the driving gas changes, the output driving air pressure changes, which drives the ZJHP pneumatic single-seat regulating valve to start adjusting up and down.

[0065] 9. The ZJHP pneumatic single-seat regulating valve adjusts up and down, causing the feedback rocker arm B to move, which in turn causes the eccentric cam B to rotate. The rotation of the eccentric cam B causes the lever B to move, which in turn causes the baffle B to move, allowing the baffle B to pass through.

[0066] 10. Adjust the driving air by adjusting the distance between baffle B and nozzle B to adjust the valve position to the desired position.

[0067] The execution and regulation module is installed on the condensate outlet 1.3 of the shell and tube heater 1 through a standardized flange without changing the original pipeline route. It uses a ZJHP pneumatic single-seat regulating valve 4 as the core execution element, which is suitable for high temperature and high pressure differential conditions of condensate, and regulates the condensate discharge to control the liquid level.

[0068] The ZJHP pneumatic single-seat regulating valve 4 includes:

[0069] Valve body structure: The valve body is made of 316L stainless steel, with a nominal diameter of DN25-DN50, suitable for an 8000KW heater with a maximum condensate discharge of 37.5t / h. Considering the high pressure differential characteristics of condensate, a "single-seat, sleeve-guided" structure is selected. The valve seat is made of hard alloy weld overlay, resistant to erosion and corrosion. The valve core is either "V-shaped opening" or "parabolic," with linear flow characteristics (adjustment accuracy ≤ ±1%), suitable for linear liquid level control requirements.

[0070] Sealing design: It adopts a dual sealing structure of "soft seal + hard seal". The upper valve cover is "bellows seal" (316L stainless steel bellows, resistant to high temperature of 120℃) to prevent condensate from leaking from the valve stem; the valve core and valve seat sealing surface adopts a combination of fluororubber and hard alloy, with a leakage level of VI (bubble level) to ensure no steam leakage at low liquid levels.

[0071] Actuator: Equipped with an explosion-proof double-acting diaphragm actuator (model ZHA / B-22, diaphragm material is nitrile rubber reinforced layer, resistant to high temperature of 120℃), springless reset structure (to avoid spring fatigue failure caused by ship turbulence), output force ≥5000N, suitable for working pressure difference of 0.3-0.6MPa in condensate pipelines; the air chambers at both ends of the actuator are connected to the "valve opening output port" and "valve closing output port" of the pneumatic amplifier, respectively;

[0072] Standardized connection: The valve body is equipped with standardized flanges at both ends (with the same specifications as the condensate outlet pipe flange of the shell-and-tube heater 1, such as DN40 PN1.6MPa), which are sealed to the original pipeline through 120℃ fluororubber gaskets, without the need to cut the original pipeline;

[0073] The control logic of the ZJHP pneumatic single-seat regulating valve 4:

[0074] Upon receiving a "valve closing signal" (liquid level ≤ 0): air enters the "valve closing chamber" of the actuator, the push rod moves the valve core downward, the valve is fully closed (opening degree 0%), blocking the discharge of condensate from the original heater and preventing steam from entering the pipeline;

[0075] When receiving the "position holding signal" (0 < liquid level < 2 / 5H): the pressure in the two chambers of the actuator is balanced, the valve core position changes linearly with the pneumatic signal, and when the ideal liquid level is 1 / 3H, the valve opening is stable at 30%-50%, maintaining the original stable liquid level in the heater;

[0076] Upon receiving the "valve opening signal" (liquid level ≥ 2 / 5H): air enters the "valve opening chamber" of the actuator, the push rod drives the valve core to move upward, the valve is fully opened (100% opening), and excess condensate in the original heater is quickly discharged;

[0077] Status indicator design: The side of the actuator push rod is marked with opening scale lines (0%-100%), which, together with the pointer fixed to the valve body, allows for intuitive observation of the valve's real-time opening degree, replacing the function of the traditional valve position indicator.

[0078] The execution adjustment module also includes a manual emergency mechanism: a manual operation handwheel (made of 316L stainless steel) is provided on the top of the execution mechanism, which is connected to the push rod through a worm gear transmission; when the gas source is interrupted, turning the handwheel can directly adjust the valve core opening (0%-100%), with an adjustment accuracy of ±2%, without affecting the emergency operation of the shell-and-tube heater 1;

[0079] An electrostatic grounding terminal is provided next to the handwheel, which is connected to the shell of the shell-tube heater 1 through a copper core wire with a cross-sectional area ≥2.5mm² (grounding resistance ≤4Ω) to avoid static electricity accumulation caused by condensation flow, and no additional independent grounding device is required.

[0080] Working principle:

[0081] This utility model discloses a pneumatic feedback control type liquid level controller for ship shell-and-tube heaters. The added liquid level controller includes a mechanical liquid level detection module, a pneumatic control module, and an execution and adjustment module.

[0082] Mechanical liquid level detection module: The liquid level detection module includes a float hinge and a displacement arm. The float is connected to the displacement arm through the hinge, and the other end of the displacement arm is connected to the controller.

[0083] Pneumatic Control Module: The pneumatic control module includes a pneumatic positioner, pneumatic controller A, pneumatic controller B, pneumatic amplifier A, pneumatic amplifier B, and a bellows. Through multi-stage pneumatic feedback via eccentric cams, levers, and baffles, the opening degree of the ZJHP regulating valve is precisely controlled.

[0084] The control module is based on a ZJHP pneumatic single-seat control valve, which is installed on the original heater condensate outlet pipeline via a standardized flange and linearly adjusts the condensate discharge rate according to the pneumatic signal.

[0085] The controller of this invention features an independent modular structure, connecting to the original heater via a standardized flange. It has no electrical components and is driven solely by compressed air to achieve precise control of the condensate level. This invention solves the problem of level control in hazardous areas, improves heating efficiency and energy recovery, and is suitable for the safe and energy-saving retrofitting of shell-and-tube heaters in ships.

[0086] The above are merely specific application examples of this utility model and do not constitute any limitation on the scope of protection of this utility model. All technical solutions formed by equivalent transformations or equivalent substitutions fall within the scope of protection of this utility model.

Claims

1. A pneumatic feedback control type liquid level controller for ship shell-and-tube heaters, characterized in that: It includes a mechanical liquid level detection module, a pneumatic control module, and an actuation and adjustment module, all integrated into the same movable explosion-proof housing, and can interface with existing shell-and-tube heaters through standardized interfaces; The shell-and-tube heater has multiple heating tubes inside. The side of the shell-and-tube heater has two through holes for docking with an add-on liquid level controller. The through holes are equipped with mounting flanges. The bottom of the shell-and-tube heater has a condensate outlet. The mechanical liquid level detection module includes a float detection assembly, which is connected to a shell-and-tube heater via a standardized flange. The float detection assembly includes a float, a vertical guide sleeve, a float hinge, a flow hole, a connecting flange, and a displacement arm. The float is installed inside the vertical guide sleeve. Two flow holes are opened on the side wall of the vertical guide sleeve. The float is connected to one end of the displacement arm via the float hinge, and the other end of the displacement arm is connected to a controller. The float hinge is located inside the vertical guide sleeve. A horizontal branch pipe is provided at the top of the vertical guide sleeve and connected to the controller. The displacement arm is installed inside the horizontal branch pipe. The pneumatic control module is installed inside the explosion-proof housing and converts the mechanical displacement signal into a pneumatic signal that can drive the actuator. The pneumatic control module includes a pneumatic positioner, a pneumatic controller A, a pneumatic controller B, a pneumatic amplifier A, a pneumatic amplifier B, and a bellows. The pneumatic controller A includes an eccentric cam A, a roller A, a feedback rocker A, a lever A, and a baffle A. The pneumatic controller B includes an eccentric cam B, a roller B, a feedback rocker B, a lever B, and a baffle B. The central axis of the eccentric cam A is connected to one end of the feedback rocker A, and the other end of the feedback rocker A is connected to one end of the displacement arm. The outer edge of the cam of the eccentric cam A is provided with a sliding matching roller A. The roller A is mounted on the lever A. The bottom of the lever A is provided with a baffle A. One side of the baffle A is provided with a pneumatic amplifier A. The nozzle A of the pneumatic amplifier A is aligned with the baffle A. The pneumatic amplifier A is also provided with a balance throttling orifice A. The output port of the pneumatic amplifier A is connected to one end of a bellows, and the other end of the bellows is welded to the top of the lever C. The bottom of the lever C is connected to the lever B, and a baffle B is connected below the lever C. A pneumatic amplifier B is provided on the other side of the baffle B opposite to the lever B. The nozzle B of the pneumatic amplifier B is aligned with the baffle B. The pneumatic amplifier B is also provided with a balance throttling orifice B. The pneumatic amplifier B is connected to a ZJHP pneumatic single-seat regulating valve to drive the air-driven valve to open. The lever B is equipped with a roller B, which is slidably disposed on the outer edge of the eccentric cam B. The central axis of the eccentric cam B is connected to one end of the feedback rocker arm B, and the other end of the feedback rocker arm B is connected to the valve core of the ZJHP pneumatic single-seat regulating valve. The ZJHP pneumatic single-seat regulating valve is also connected to a pneumatic positioner. The execution and regulation module is installed on the condensate outlet pipeline of the shell-and-tube heater via a standardized flange without changing the original pipeline route. The execution and regulation module includes a ZJHP pneumatic single-seat regulating valve, which is used to regulate the condensate discharge to control the liquid level.

2. A pneumatic feedback control type liquid level controller for a ship shell-and-tube heater according to claim 1, characterized in that: A connecting flange is provided at the flow hole, and it is sealed to the mounting flange on the side wall of the shell and tube heater by a graphite gasket that is resistant to 120°C, without the need for welding.

3. A pneumatic feedback control type liquid level controller for a ship shell-and-tube heater according to claim 2, characterized in that: The vertical guide sleeve is equipped with stainless steel limiting blocks at its upper and lower ends to limit the float travel, corresponding to liquid levels from 0 to 2 / 5H, which is compatible with the shell height of the shell-and-tube heater.

4. A pneumatic feedback control type liquid level controller for a ship shell-and-tube heater according to claim 1, characterized in that: The bottom of the vertical guide sleeve is provided with a vent plug.

5. A pneumatic feedback control type liquid level controller for a ship shell-and-tube heater according to claim 1, characterized in that: The pneumatic positioner is connected to the controller, and the ZJHP pneumatic single-seat regulating valve is connected to the condensate outlet pipeline of the shell-and-tube heater.

6. A pneumatic feedback control type liquid level controller for a ship shell-and-tube heater according to claim 1, characterized in that: The ZJHP pneumatic single-seat control valve includes a valve body structure, sealing design, and actuator. The ZJHP pneumatic single-seat regulating valve has a stainless steel valve body and a V-shaped or parabolic valve core. Its flow characteristics are linear, which is suitable for linear liquid level control requirements. The ZJHP pneumatic single-seat regulating valve has standardized flanges at both ends of its valve body, which are consistent with the flange specifications of the condensate outlet pipeline of the shell-and-tube heater. The valve is sealed to the condensate outlet pipeline through 120℃ resistant fluororubber gaskets.

7. A pneumatic feedback control type liquid level controller for a ship shell-and-tube heater according to claim 6, characterized in that: The nominal diameter of the valve body of the ZJHP pneumatic single-seat control valve is DN25-DN50, and the valve seat is made of hard alloy weld overlay, which is resistant to erosion and corrosion. The sealing design of the ZJHP pneumatic single-seat control valve adopts a dual sealing structure of soft seal and hard seal. The upper valve cover of the ZJHP pneumatic single-seat control valve adopts bellows seal. The valve core and valve seat sealing surface of the ZJHP pneumatic single-seat control valve are made of a combination of fluororubber and hard alloy.

8. A pneumatic feedback control type liquid level controller for a ship shell-and-tube heater according to claim 1, characterized in that: The execution adjustment module also includes a manual emergency mechanism: a manual operation handwheel is provided on the top of the execution mechanism, which is connected to the push rod through a worm gear transmission; when the gas source is interrupted, turning the handwheel can directly adjust the valve core opening; an electrostatic grounding terminal is provided next to the handwheel, which is connected to the shell of the shell-and-tube heater through a copper core wire with a cross-sectional area ≥2.5mm², with a grounding resistance ≤4Ω, to avoid static electricity accumulation caused by condensate flow, and no additional independent grounding device is required.

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