I.Coke Oven Rising Tube Apparent Heat Recovery System Process Principle
1. System process flow diagram (see figure I):
Figure I. System process flow diagram
Introduction to the process
The demineralised water is sent to the buffer tank, and then sent to the deaerator for heating and deoxygenation through the deoxygenation pump (one for one standby). The deoxygenated water obtained at 104℃ is sent to the steam bag through the steam bag feed pump (one for two and one for standby), and the electric (pneumatic) regulating valve controls the level of the steam bag through the three-stroke regulating system to maintain a constant and smooth operation. Forced circulating pump (two for two standby) sends the water to the coke oven rising tube heat exchanger to exchange heat with the barren gas, and the temperature of barren gas is reduced from 750℃~850℃ to not less than 550℃. The circulating pump sends the steam generated in the rising tube heat exchanger back to the steam ladle, and sends the saturated steam generated from 0.6~0.8Mpa to the steam pipe network through the steam-water separation device.
II. Longyue Technology: Performance characteristics of coke oven rising tube heat exchanger nanotechnology
Coke oven rising tube by high temperature baking, dust, and due to the barren gas entrained tar steam, water vapour, stupid steam and other corrosive factors, when the temperature is lower than 450 ℃ will make the coal tar vapour condensation, resulting in condensation in the inner wall of the rising tube, blocking the rising tube channel; when the temperature is higher than 800 ℃ and carbon growth graphite; coke oven rising tube heat exchanger can not be leaked into the carbonation room, or the coke oven body cause This is what coke makers often call "three fears": fear of water leakage, fear of hanging tar, and fear of graphite growth.
In view of the above "three fears", our company and the coke plant of Fujian Sangang Minguang Co., Ltd. have been devoted to the research and development of the coke oven gas sensible heat recovery technology since 2010, and after three years of repeated experiments and technological debates, and investing a large amount of human resources, material resources and financial resources, we finally succeeded in researching and developing the coke oven heat recovery technology which is a set of seamless alloy, nano-lining and self-cleaning material with three patented technologies, which is the best choice for the coke oven. Finally, we successfully developed a new heat exchanger with seamless alloy, nano-lining layer and self-cleaning material, which is a new type of heat exchanger with heat recovery from rising tube of coke ovens, and makes the inner wall of the rising tube heat exchanger have the triple functions of anti-leakage, anti-graphite formation and anti-tar hanging. See Figure II:
Figure 2: Process flow diagram of recovering waste heat of barren gas in water jacket with special structure of Longye.
A、Anti-caking tar, anti-hanging graphite
1、The inner wall of the rising tube heat exchanger adopts nano and self-cleaning materials, the inner surface is even and smooth, no dead angle, so the inner wall of the rising tube will not condense coal tar and long graphite;
2、Adjusting the medium flow to control the temperature of the inner wall of the rising tube, further reducing the rising tube wall condensation of coal tar and long graphite.
3、Even if there is a small amount of condensation on the inner wall of the rising tube, it can be removed only by using the air duct or simple tools, which greatly reduces the labour intensity of the workers on the top of the furnace;
B. Water leakage prevention
1、The inner wall of the rising tube heat exchanger is an integral structure, made of high temperature resistant alloy material and new technology, which is not easy to leak;
2, water - steam heat exchange process is completed in the closed space, closed space in the rising tube inner cylinder outside, water vapour will not leak into the carbonization room.
C. Corrosion resistance, high temperature resistance, dry burning resistance
1、Since the inner wall of the inner tube is an integral structure, it adopts wear-resistant, corrosion-resistant and high-temperature-resistant alloy materials, and is moulded into an integral seamless alloy body in a high-temperature environment;
2, the research and development stage has withstood many simulation tests of dry burning, water, dry burning again, water again, and the actual working conditions on site, so the rising tube heat exchanger is wear-resistant and not afraid of corrosion and high temperature.
Figure III. Appearance of coke oven rising tube heat exchanger in operation for two years
III. Benefit analysis of the recovery and utilisation of sensible heat from barren gas
1、 Reduce the energy consumption of coke-making process: reduce the energy consumption of the process by >10kg standard coal per tonne of coke.
2. Emission reduction benefit: according to the annual output of 1.1 million tonnes of coke from two 6-metre coke ovens, 143,000 tonnes of steam can be produced, 13,100 tonnes of standard coal can be saved, and 39,000 tonnes of carbon dioxide can be reduced.
3、 Social benefits: the surface temperature of the rising tube is lowered, reducing heat radiation, lowering the ambient temperature of the coke oven roof space, and improving the working environment of the roof operators.
4、 Direct economic benefits:
(1), the direct benefits of steam generation: according to two 6-metre coke oven annual output of 0.5-0.8Mpa saturated steam about 143,000 tonnes, the installation of the market price of 120 yuan / tonne, the annual economic benefits of about 17.16 million yuan. The price of energy medium is different for each coking enterprise, and its running cost is also different.
(2), the total annual profit: more than 14.8 million yuan.
(3), the national policy energy-saving subsidies 3.8 million yuan.
(4) Static payback period: about 2 years.
In a word, the coking barren gas sensible heat recovery technology has made a significant breakthrough, but our company is summing up the experience of the first set of device operation practice, improve the design, optimise the process, and continue to promote the progress of energy saving and emission reduction technology in the coking industry!