Formaldehyde production device and method for recycling thermal energy of tail gas by-product steam

Abstract

The invention discloses a formaldehyde production device and method for recycling thermal energy of tail gas by-product steam. The formaldehyde production process is that a methanol oxidation reactor and a tail gas burning furnace are adopted, the tail gas can generate the steam of 0.8 MPa, and the methanol oxidation reactor requires batching steam below 0.2 MPa. A recycling device comprises a tail gas steam pocket, a screw bolt type expansion engine and a vapour-liquid separator, wherein the tail gas steam pocket and the tail gas burning furnace are connected to receive the produced steam of 0.8 MPa; the outlet of the tail gas steam pocket is sequentially connected with the screw bolt type expansion engine and the vapour-liquid separator through a pipeline; the vapor phase outlet of the vapour-liquid separator is connected with the methanol oxidation reactor. The method and the device aim to make the best of the enthalpy value difference of different-pressure level steams, namely the by-product of the formaldehyde device, to convert low-grade steam into high-quality electrical energy, so as to improve the energy utilization ratio, and belong to the field of energy optimization application; and moreover, the steam waste can be effectively reduced by fully utilizing the low-pressure by-product steam.

Description

technical field [0001] The invention belongs to the technical field of chemical production technology and equipment, and mainly relates to the energy optimization application technology of by-product steam of different pressure levels in the formaldehyde production technology. Background technique [0002] At present, there are more than 5,000 formaldehyde production enterprises in China, with a total production capacity of about 32 million tons. Due to the continuous improvement of formaldehyde process technology, formaldehyde has developed from the original "steam consumption type" to "gas production type", that is, all formaldehyde devices can realize by-product steam. Among them, there are two main steam production points of the formaldehyde plant, one is the 0.4MPa steam generated by the reaction heat of the oxidizer, and the other is the pressure-controllable steam produced by the heat of the tail gas combustion of the formaldehyde plant, which generally produces 0.8MP...

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Problems solved by technology

At present, formaldehyde production enterprises usually decompress the 0.4MPa steam or 0.8MPa steam generated in the formaldehyde reactor to 0.15MPa and then send it into the reactor for batching steam, resulting in direct waste of high-pressure steam energy; and the formaldehyde production in the domestic formaldehyde industry The by-product steam part of the manufacturer has low steam pressure and low usable value, so the by-product steam is basically emptied except for domestic water heating, which is not only noisy, but also a serious energy waste, which does not meet the national energy saving platoon expectations

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