Waste heat boiler for recycling heat of petroleum coke calcination flue gas

Abstract

The waste heat boiler comprises a flue, the flue comprises a front flue body and a rear flue body, the front flue body is vertically arranged downwards, the rear flue body is vertically arranged upwards, and the lower portion of the front flue body and the lower portion of the rear flue body are connected through a switching flue to form U-shaped distribution. A cooling chamber and a slag solidification pipe are sequentially arranged on the front flue from top to bottom, a superheater and a tail heating surface are sequentially arranged on the rear flue from bottom to top, and an ash hopper is arranged at the bottom of the switching flue. Compared with a traditional heat exchange system, the phenomena of superheater coking, high-temperature corrosion and tail heating surface low-temperature corrosion caused by high-Na, high-Ca, high-S and dust-containing flue gas can be effectively relieved, the safety stability of the heating surface of the waste heat boiler is improved, and the service life of the heating surface of the waste heat boiler is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat boilers, and particularly to a waste heat boiler for recovering the heat of the flue gas from calcined petroleum coke. Background Art

[0002] With the continuous and rapid development of society and the gradual improvement of industrial production levels, the types and quantities of waste heat boilers have also been increasing continuously. A waste heat boiler for recovering the heat of the flue gas from calcined petroleum coke is one of them. Petroleum coke is a by-product during the pyrolysis of the feedstock oil in a delayed coking unit at high temperatures to produce light oil products. The flue gas generated from calcining petroleum coke contains relatively high levels of Na, Ca, S, and dust, which can cause corrosion of the tail heating surfaces such as superheaters and economizers in traditional waste heat boilers, resulting in coking and bridging on the surface of the heating surfaces and affecting the service life of the heating surfaces of the waste heat boiler. Summary of the Invention

[0003] To solve the above technical problems, the present invention designs a waste heat boiler for recovering the heat of the flue gas from calcined petroleum coke.

[0004] The present invention adopts the following technical solutions: A waste heat boiler for recovering the heat of the flue gas from calcined petroleum coke includes a flue, the flue includes a front flue and a rear flue. The front flue is arranged vertically downward, and the rear flue is arranged vertically upward. The front flue and the rear flue are connected by a transfer flue at the bottom to form a U-shaped distribution. A cooling chamber and a slagging tube are arranged on the front flue from top to bottom in sequence. A superheater and a tail heating surface are arranged on the rear flue from bottom to top in sequence. A hopper is arranged at the bottom of the transfer flue.

[0005] Preferably, soot blowing devices are provided in the waste heat boiler corresponding to the cooling chamber and the tail heating surface.

[0006] Preferably, the cooling chamber is composed of membrane water walls. A furnace structure with a cross-sectional area 50%-60% larger than that of a conventional waste heat boiler is adopted, which reduces the flue gas velocity and is conducive to the settlement of dust particles in the flue gas.

[0007] Preferably, the superheater adopts a bare tube structure with a transverse pitch greater than 160 mm and is arranged below the rear flue. The flue gas after the slagging tube enters the superheater through a large-angle flue, reducing the flue gas temperature and velocity of the superheater, which is conducive to the settlement of dust particles and prevents bridging and blockage of the superheater.

[0008] Preferably, the slagging tube is arranged below the cooling chamber, and the area of the slagging tube is adjusted to adjust the flue gas temperature below the slagging tube. The flue gas temperature below the slagging tube is controlled to be lower than 800 °C, so that the flue gas temperature entering the superheater is lower than the ash melting point temperature, slowing down the high-temperature corrosion phenomenon, avoiding slagging on the superheater and the tail heating surface, and further removing dust in the flue gas.

[0009] Preferably, the ash hopper has a rectangular cross-sectional shape and is arranged below the waste heat boiler.

[0010] Preferably, the tail heating surface includes an economizer and an air preheater.

[0011] The flue gas from calcined petroleum coke enters the cooling chamber from the upper part of the front wall of the waste heat boiler, where dust particles settle in the empty flue gas cooling chamber. The flue gas after preliminary cooling exchanges heat with the slag coagulation tubes, and then the flue gas after further cooling enters the superheater and the tail heating surface after a 180° turn, heating the working medium in the heating surface and reducing the flue gas discharge temperature. The ash particles in the cooling chamber and the heating surface fall into the ash hopper below under the action of the soot blower and are discharged out of the furnace. The sulfur content in the flue gas after passing through the cooling chamber, the slag coagulation tubes, and the superheater is significantly reduced, slowing down the low-temperature corrosion of the tail heating surface. For the waste heat boiler that recovers the heat of the flue gas from calcined petroleum coke, this system can effectively slow down the coking, high-temperature corrosion of the superheater, and low-temperature corrosion of the tail heating surface caused by high Na, high Ca, high S, and dusty flue gas, improving the safety stability and service life of the heating surface of the waste heat boiler.

[0012] The beneficial effects of the present invention are as follows: Compared with the traditional heat exchange system, the present invention adopts a waste heat boiler for recovering the heat of the flue gas from calcined petroleum coke. This system can effectively slow down the coking, high-temperature corrosion of the superheater, and low-temperature corrosion of the tail heating surface caused by high Na, high Ca, high S, and dusty flue gas, improving the safety stability and service life of the heating surface of the waste heat boiler. Brief Description of the Drawings

[0013] Figure 1 is a schematic structural diagram of the present invention; In the figure: 1. Cooling chamber, 2. Slag coagulation tubes, 3. Ash hopper, 4. Superheater, 5. Tail heating surface. Detailed Embodiments

[0014] The following will further specifically describe the technical solutions of the present invention through specific embodiments in combination with the drawings: Embodiment: As Figure 1As shown in the figure, a waste heat boiler for recovering the heat of calcined petroleum coke flue gas includes a cooling chamber 1, a slag coagulation pipe 2, an ash hopper 3, a superheater 4, a soot blowing device, and a tail heating surface 5. The cooling chamber is composed of a membrane water wall and adopts a large cross-section furnace structure that is 50%-60% larger than that of a conventional waste heat boiler, reducing the flue gas velocity and facilitating the settlement of dust particles in the flue gas. The slag coagulation pipe is arranged below the cooling chamber. By adjusting the area of the slag coagulation pipe, the flue gas temperature below the slag coagulation pipe is adjusted to control the flue gas temperature below 800 °C, so that the flue gas temperature entering the superheater is lower than the ash melting point temperature and the high-temperature corrosion phenomenon is slowed down, avoiding slagging of the superheater and the tail heating surface and further removing dust in the flue gas. The superheater adopts a smooth tube structure with a transverse pitch greater than 160 mm and is arranged below the second flue. The flue gas after the slag coagulation pipe enters the superheater through a transfer flue, reducing the flue gas temperature and velocity of the superheater, facilitating the settlement of dust particles and preventing bridging blockage of the superheater. The cross-sectional shape of the ash hopper is rectangular and is arranged below the waste heat boiler to receive the ash particles of the flue gas in the cooling chamber and the heating surface of the waste heat boiler and discharge them outside the furnace. The waste heat boiler is provided with a soot blowing device at an appropriate position to make the ash particles adhered to the water wall and the heating surface fall off. The outlet of the superheater is connected to the inlet of the tail heating surface. Among them, tail heating surfaces such as economizers and air preheaters are arranged according to design requirements to heat the working medium in the heating surface and reduce the flue gas discharge temperature.

[0015] The working principle of the present invention is as follows: The calcined petroleum coke flue gas enters the cooling chamber from the upper part of the front wall of the waste heat boiler, and the dust particles settle in the empty flue cooling chamber. The flue gas after preliminary cooling exchanges heat with the slag coagulation pipe. The flue gas after further cooling enters the superheater and the tail heating surface after a 180° turn, heating the working medium in the heating surface and reducing the flue gas discharge temperature. The ash particles in the cooling chamber and the heating surface fall into the lower ash hopper and are discharged outside the furnace under the action of the soot blowing device.

[0016] Compared with the traditional heat exchange system, the present invention can effectively slow down the superheater coking, high-temperature corrosion, and low-temperature corrosion of the tail heating surface caused by high Na, high Ca, high S, and dusty flue gas, improving the safety stability and service life of the heating surface of the waste heat boiler.

[0017] The above-described embodiments are only a preferred solution of the present invention and do not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions recorded in the claims.

Claims

1. A waste heat boiler for recovering the heat of the flue gas of calcined petroleum coke, comprising a flue, characterized in that, The flue duct includes a front flue duct and a rear flue duct. The front flue duct is arranged vertically downward, and the rear flue duct is arranged vertically upward. The lower parts of the front flue duct and the rear flue duct are connected by a transition flue duct to form a U-shaped distribution. A cooling chamber and slag coagulation tubes are arranged on the front flue duct from top to bottom in sequence. A superheater and a tail heating surface are arranged on the rear flue duct from bottom to top in sequence. A ash hopper is arranged at the bottom of the transition flue duct.

2. The waste heat boiler for recovering the heat of the calcined petroleum coke flue gas according to claim 1, wherein, A soot blowing device is arranged in the waste heat boiler corresponding to the cooling chamber and the tail heating surface.

3. The waste heat boiler for recovering the heat of the calcined petroleum coke flue gas according to claim 1, characterized in that, The cooling chamber is composed of membrane water walls.

4. The waste heat boiler for recovering the heat of the calcined petroleum coke flue gas according to claim 1, wherein, The superheater adopts a bare tube structure with a transverse pitch greater than 160 mm and is arranged below the rear flue duct.

5. The waste heat boiler for recovering the heat of the calcined petroleum coke flue gas according to claim 1, characterized in that, The slag coagulation tubes are arranged below the cooling chamber, and the flue gas temperature below the slag coagulation tubes is adjusted by adjusting the area of the slag coagulation tubes.

6. The waste heat boiler for recovering the heat of the calcined petroleum coke flue gas according to claim 1, characterized in that, The ash hopper has a rectangular cross-sectional shape and is arranged below the waste heat boiler.

7. The waste heat boiler for recovering the heat of the calcined petroleum coke flue gas according to claim 1, characterized in that, The tail heating surface includes an economizer and an air preheater.

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