First, the coke oven riser sensible heat recovery system technology principle
1, the system process flow chart (see Figure 1):
Figure I. System Process Flow Diagram
2. Introduction to process flow
The demineralized water from the factory is sent to the buffer tank and sent to the deaerator for deoxygenation through the deaeration pump (one for one preparation) to generate deoxygenated water at 104°C; then it is sent to the pump through the drum (two for one preparation) The steam drum and electric (pneumatic) control valve control the drum level through a three-impulse regulation system to maintain smooth operation at a constant liquid level; it is transported to the coke oven riser heat exchanger through a forced circulation pump (two for two). The temperature of the raw gas is reduced from 750°C to 850°C to not lower than 550°C, so that the steam generated by the heat exchange on the inner wall of the riser heat exchanger is returned to the steam drum by the circulation pump, and the 0.6 to 0.8 Mpa generated by the steam and water separation device will be generated. Saturated steam is sent to the steam pipe network.
Second, Longye Technology: Performance characteristics of coke oven riser heat exchanger nanotechnology
The riser of the coke oven is affected by high-temperature roasting and dust. At the same time, due to corrosive factors such as tar vapor, water vapor, and stupid steam, the coal tar steam condenses when the temperature is lower than 450° C., causing the rise in the riser tube. Wall condensation, clogging the riser channel; when the temperature is higher than 800 °C and carbon will grow graphite; coke oven riser heat exchanger must not leak to the carbonization chamber, otherwise it will cause great harm to the coke oven body; this is coke people often say The "three afraid": afraid of leaking, afraid of graphite, fear of hanging tar.
In response to the above "three fears", our company and the Fujian Sansteel Shuguang Co., Ltd. coking plant has been working on the R&D of sensible heat recovery technology for coke oven gas since 2010, after three years of repeated tests and technical demonstrations. A large amount of manpower, material resources, and financial resources were invested. In the end, a new heat exchanger for sensible heat recovery of coke oven risers incorporating three patented technologies of seamless alloys, nano liners and self-cleaning materials was successfully developed, resulting in riser heat exchangers. The inner wall has a triple function of preventing water leakage, preventing graphite, and preventing tar from hanging. See Figure II:
Figure 2, the inner wall of the coke oven riser heat exchanger work
A, anti-caking, anti-hook graphite
1. Since the inner wall of the coke oven riser heat exchanger adopts nanometer and self-cleaning materials, the inner surface is even and smooth, and there is no dead angle, so the inner wall of the riser tube will not hang graphite and coal tar;
2. Even if a small amount of particles appear on the inner wall of the riser, only the air duct or simple tool can be removed, which greatly reduces the labor intensity of the top workers;
3, through the media flow control riser inlet and outlet temperature, to further reduce the riser tube condensation tar and graphite;
B, leakproof water
1, the coke oven riser heat exchanger inner wall of the overall structure, using high-temperature alloy materials and new technology made;
2. The water-steam heat transfer process is completed in a closed space. The closed space is on the outside of the riser tube and water vapor will not leak into the carbonization chamber.
C, corrosion resistance, high temperature resistance, dry resistance
Because the inner wall of the inner cylinder is an integral structure, it is made of alloy material that is wear-resistant, corrosion-resistant and high-temperature resistant. It is formed into a seamless alloy body in a high-temperature environment. The R&D stage has undergone dry burning, water circulation, re-drying, and water circulation. Many simulation tests, and the test under the actual working conditions on site, the riser does not leak water, and the inner tube is in good condition without deformation.
Figure 3, Two-year appearance of the coke oven riser heat exchanger operation
III. Analysis of sensible heat recovery and utilization benefits of raw gas
1. Reduce the energy consumption of the coking process:Tons of coke to reduce process energy consumption > 10 kg of standard coal.
2. Emission Reduction Benefits:Based on the calculation of 1.1 million tons of coke per year in two 6-meter coke ovens, it can produce 143,000 tons of steam, equivalent to 131,000 tons of standard coal, and can reduce carbon dioxide emissions by 39,000 tons.
3, social benefits:The rising surface temperature of the riser reduces heat radiation, lowers the space temperature of the coke oven top, increases the space between the risers, and improves the operating environment of the top workers.
4, direct economic benefits:
(1) The direct benefit of steam production: According to two 6-meter coke ovens, the annual output of saturated steam of 0.5~0.8Mpa is about 143,000 tons, and the installed market price is 120 yuan/ton, with an annual economic benefit of 17.16 million yuan. The price of the energy medium is different from that of a coking company, and its operating costs are also different.
(2) The national policy energy subsidies are 3.8 million yuan.
(3) Total annual profit: more than 1,480,000 yuan.
(4) Static investment recovery period: about 2 years.
(5) To a certain extent, the amount of ammonia spray can be reduced.
In a word, the sensible heat recovery technology for coke-making raw gas has made a major breakthrough, but our company has summarized the first set of equipment operation practices, improved the design, optimized the technology, and continued to advance the energy-saving and emission-reduction technology of the coking industry.