Protective atmosphere mesh belt blackening | Oxidizing furnace

The structural design of the protective atmosphere mesh belt blackening furnace: It is specially used for blackening stainless steel electric Heaters of various specifications and sizes under DX protective atmosphere, so that the stainless steel electric heaters can be blackened or greened (according to the material).

Grade of processed material：SUS304、SUS316、SUS316L、SUS321、1Cr18Ni9Ti、Incoloy800、Incoloy840 and so on.

1. SUS304 The tube is green after furnace;
2. SUS321 The tube is dark green after furnace;
3. INCOLOY840 The tube is black after furnace (Note: This tube is imported material)
4. Keep the original color of the electroplating after the terminal needle passes through the furnace.

This equipment is used to form an oxide film on the surface of stainless steel electric heaters, which is called blackening chemical heat treatment. Its characteristic is that in a furnace filled with high dew point DX gas of coal gas or propane, after heating and cooling, a layer of uniform solid porous lattice of body-centered cubic Fe3O4 and hexagonal crystal Cr2O3 film is formed on the surface of the electric heaters. The resistance to high temperature oxidation of the electric heaters is improved.

After blackening, the surface of the electric heater has no oxidation color or oxidation spots, and the shape and size of the tube fittings are consistent. The furnace has a micro-arch structure, beautiful appearance, and excellent and reliable performance.

Main technical parameters

The main material material and supporting manufacturers

Composition of blackening furnace

It is mainly composed of: preheating furnace, heating furnace body, heat-resistant steel muffle, water cooling sleeve, transmission device, gas distribution device, furnace adjusting device, system safety device and so on.

Introduction to the structure of each part

Preheating Furnace

The preheating furnace is the front-end supporting component of the Bright Annealing Furnace and is used for drying and preheating cold loads. The advantage is that the production speed can be increased, the power consumption of the heating zone can be reduced, the service life of the muffle tank can be extended, and its deformation can be overcome. The preheating zone uses a carbon steel plate with a thickness of 5mm, and the temperature is controlled at 300-500°C.

Furnace Lining

The lining of the blackening furnace adopts composite lining manufacturing technology. The upper part of the furnace is a full-fiber ceiling, fixed with heat-resistant steel spot welding; the furnace side insulation material is superimposed with a 20mm high-aluminum needle-punched fiber blanket, and its fire resistance reaches 1450°C. The furnace lining structure is light in weight, has good high temperature resistance, and can be used continuously for many years without maintenance. The bottom of the furnace is made of mullite, a new material, and high-alumina bricks are used as muffle support. The top is full-fiber lining, which has low heat consumption, excellent thermal insulation performance, fast temperature rise, and the furnace surface temperature is significantly lower than the national standard resistance furnace surface temperature.

Muffle

The black furnace muffle of this invention is made of 310S heat-resistant stainless steel plates, which are formed and welded by compression molding. After the welding is completed, a leak test is performed under 0.3Mpa water pressure; in order to ensure that the muffle is less deformed under high temperature conditions, a 400-ton press is used to press several corrugated bars on the bottom and top surfaces of the muffle to enhance stiffness, and reinforcement plates are attached to both sides. It has the effect of significantly reducing high-temperature deformation during the hot operation of the furnace. For the Haval-type furnace body, when replacing the muffle tank, the upper furnace cover can be lifted off. The furnace has a longer service life and better heat preservation. The furnace surface temperature is lower than 50°C, ensuring safety and easy maintenance.

Mesh belt

The mesh belt is made of reinforced heat-resistant steel wires that are cross-woven. The mesh size is uniform and the hooks are firm. It will not decouple or become brittle when running under high temperature conditions. The quality is strictly guaranteed, and relevant warranty certificates and material test reports are provided to the purchaser. ;The mesh belt drive is controlled by a frequency converter, and the speed is adjusted within the range of 50~500mm/min. It is equipped with a digital frequency modulator to directly display the linear speed of the mesh belt.

The mesh belt running under normal high temperature will become longer when heated. It is adjusted by a tensioning device, and the mesh belt anti-deviation guide Roller and supporting roller are installed on the front material rack to always maintain a certain tension on the mesh belt and improve the stability of the workpiece operation. This ensures reliable product quality during the production process.

Inlet and outlet chamber

The overall shape of the blackening furnace is a micro-arch structure, and the cylinder near the front inlet is equipped with thermal insulation treatment. The working bottom surface of the front and back of the whole line is a slope at a certain Angle to the horizontal line (＜8°C). Its advantages: when working, the workpiece is fully in contact with the protective gas, so that the pipe is always well protected by the gas during heat treatment, saving the consumption of the gas source and reducing the production cost; In addition, the furnace mouth uses the protective gas self-overflow sealing door, the furnace external environment has little interference with the furnace gas, and the furnace mouth does not need to use other (gas or fire) curtain sealing measures. In and out of the working material table lay the panel, and the two sides of the material table are arranged with the protective hanging plate.

Front and rear doors

The front and back of the furnace are equipped with hand-drawn fire-resistant soft-seal curtains, which can enter and exit freely regardless of the outer diameter of the electric heater, so as to minimize the amount of protective gas and reduce heat loss; In order to adjust the size height of the feed, the front and rear furnace doors are provided with adjustable stainless steel flap plates near the furnace opening. And the box is equipped with several layers of 3mm Refractory Ceramic fiber cloth made of heat insulation curtain.

Hearth shell

The skeleton of the furnace body is welded by a combination of various sections and steel plates, and the section steel is not less than the national standard 120 channel steel to make the frame structure. The furnace shell is made of δ=5mm steel plate, the pressure reinforcement of the furnace side plate, and the hole where the heating element is placed is stamped to improve the steel degree of the furnace shell. The whole furnace shell is connected up and down by screws. In the furnace needs to be serviced. Only need to disassemble the screws, lift down the upper shell for maintenance, no impact on the furnace wire, etc., can save a lot of maintenance parts costs.

Inner water cooling jacket

The latter half of the heating furnace is divided into 3 sections of water cooling device, whose function is to heat and annealed the workpiece through the water cooling in the sandwich to ≤85° C. The water jacket is double layer, the inner sleeve and the jacket are bent and welded with 4~5mm high-quality boiler steel plate, strict requirements on welding quality, after welding, leakage test under 0.6Mpa water pressure, and ensure that the water jacket does not leak during long-term high temperature use. No deformation, no welding, water jacket in the factory before the water pressure test, each water jacket top installation water temperature gauge and surface paint paint treatment.

Electrical control

The rated heating power of this furnace is about 120KW, due to the use of electric heating wire up and down heating and excellent composite lining, the temperature can be raised to the process temperature in about 4h. The 3-zone temperature is controlled by three thermocouples inserted in the top lining to transmit the temperature signal to the temperature controller, which reaches the preset temperature through the intelligent power regulator and contactor. The heating control element adopts the international first-class brand power regulator, and its control mode is phase-shift trigger, that is, by controlling the conduction Angle of the thyristor to control the conduction energy of the thyristor, so as to change the power added on the load. This scheme has precise temperature control and gentle current change. The temperature control meter is also imported from Japan, and its mature temperature control algorithm makes the temperature fluctuation can be controlled at the set temperature of ±1°C, and the temperature curve can be monitored online according to the paperless recorder. In terms of safety, the company adopts contactor, alarm and temperature control meter chain control, in the case of short circuit or failure of the power regulator can automatically cut off the heating power supply in this temperature zone, so that the temperature can be effectively controlled to protect the customer's products and furnace body. The control system is all selected from well-known brands at home and abroad with high reliability, good performance, long service life, absolute guarantee of quality, to ensure long-term use.

DX exothermic gas generator

For stainless steel blackening:

1. Equipment parameter:
2. Power: 4KW
3. Gas production rate: 25m3/h
4. Liquefied gas to air ratio: 1.1:20
5. Outlet pressure: 200mm H2O
6. Heat production: 3000KCal/h
7. Overview of DX gas preparation principle:

The exothermic gas generating device uses petroleum liquefied gas, which is an atmosphere obtained by rapid cooling of combustible raw gas (such as CH4, C3H8, etc.) and air in a certain proportion after incomplete combustion. During the reaction process, combustion releases a large amount of heat and does not require external heat supply, so it is called an exothermic atmosphere. Due to the different ratios of raw material gas and air, atmospheres with different furnace gas compositions can be produced, and their uses are also different. This is currently a more advanced blackening method. The furnace is suitable for mass production and ensures consistency and repeatability of blackening of tube fittings.

The demander provides conditions

1. Power :380V three-phase AC, total capacity ≥130KVA; The demander shall prepare power lead-in Cables and power cables. It is recommended that the power lead-in cables should be copper rubber sheathing cables 3×1002+1×352(the length is the distance between the switch cabinet in the demander's workshop and the electric gas cabinet of the furnace, to be determined on site), and the power cables should be 252mm and 100M. (to be determined on site).
2. Cooling water: flow ≥14M3/h, pressure ≥0.2Mpa, water quality meets the relevant national industrial water requirements, can use recycled water; Prepare cooling water installation materials (the supplier shall provide the list on site according to the user, and the demander shall prepare in advance)
3. Bottled petroleum liquefied gas (generally 200 liters/bottle) A total of 4 bottles of interchangeable turnover.
4. After the supplier puts forward specific requirements for the plant and other facilities, the buyer shall give the plant plan of the purchased equipment.
5. The Demander shall provide on-site installation of auxiliary materials (external water and gas piping system and power cable), and make a list one week before delivery;
6. The supplier provides free technical training to the demander's operators and provides training certificates to qualified personnel who participate in the training. The purchaser is responsible for providing food and accommodation.

Installation environment conditions requirements

1. The blackening furnace should be installed in a factory with good ventilation and a height of 4 to 5 meters or more. However, the entrance and exit of the equipment are prohibited from being ventilated or directly facing the window. Exhaust chimneys should be installed on the front and rear chimneys of the equipment, and the factory should also be on the ceiling. Install ventilation fans at locations 2-4. The internal power cords and gas and water pipes of the blackening furnace can be constructed according to the bridge or trench required by your company. The return water of the equipment flows into the return pool through the gap.
2. Petroleum liquefied gas bottles are generally installed outside buildings, and exposure to the sun is absolutely prohibited. Since petroleum liquefied gas bottles are toxic and volatile gases, they should be installed in a location with good ventilation, and even an exhaust device can be added.
3. The outer dimensions of the return pool should be made according to the user's site environment requirements, but the size of the return pool should be ensured not to be less than 15 cubic meters.
4. The cooling tower is recommended to have a water processing capacity of 20 cubic meters per hour, a water pump of 1.5kW, and a head of 20M. The power supply system should meet its power requirements.

additional donation

Heating furnace resistance wire porcelain tube 6 sets