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Research and practice of cleaner production in precision casting.

Research and practice of cleaner production in precision casting.

Oct 08, 2020

China is a major foundry country in the world, but the current situation of my country's foundry industry with high energy consumption, high pollution and poor economic benefits is still far behind the foundry industry. Therefore, how to reduce the energy consumption and resource consumption of ton-level castings, increase product yield, reduce harmful substances in the production process, reduce pollutant emissions, realize circular economy, and build resource-saving and environment-friendly castings? Manufacturing enterprises are an important issue facing my country's foundry enterprises. Therefore, saving resources, energy saving and emission reduction are also important issues for the development of traditional precision casting industry.


"Clean production" refers to continuously taking measures to improve design, use clean energy and raw materials, adopt advanced technology and equipment, improve management and comprehensive utilization, reduce pollution sources, increase resource utilization, and reduce or avoid pollution in production, service and product use Production and emission of waste. To reduce or eliminate harm to human health and the environment.


1. Implementation and potential analysis of energy saving and emission reduction projects


In order to effectively promote green manufacturing, our company mainly focuses on the traditional water glass precision casting process to carry out energy saving and environmental protection technology, equipment technology research and clean energy application. Wastewater treatment and reuse, the transformation of no-baked shell casting process, and the application of coal gas instead of clean energy have continuously promoted technological progress. Cleaner production is a guarantee for the sustainable development of an enterprise, and it is also an accurate calculation of energy conservation and emission reduction after the implementation of the project. The selection of technological transformation of the project conforms to the national industrial policy and local development plan.


Wax mold production wastewater mainly comes from cooling and cleaning wastewater, dewaxing recycling wastewater, cleaning of shell making process, hardening liquid brought by workpieces, surface cleaning wastewater, etc. The melting process mainly comes from medium cooling water. Frequency conversion electric furnace, because the hydraulic system of the intermediate frequency electric furnace leaks from time to time. Therefore, the wastewater contains petroleum pollutants; the heat treatment process wastewater mainly contains some organic salts and oil; the air compressor station mainly contains petroleum pollutants; and the mechanical processing technology is mainly emulsified waste liquid. The transformed sewage treatment process is shown in Figure 1.


(1) The natural gas boiler application enterprise originally had two 6t/h (one one) and one 4t/h chain grate boiler coal-fired steam boiler. Since it was put into operation in the 1980s, it is planned to add two gas-fired boilers to replace the existing coal-fired boilers.


The thermal efficiency of the chain-grate coal-fired steam boiler is calculated to be 68%. The coal-fired heat required by the boiler is as follows:


The calorific value of natural gas is calculated at 8500 kcal/nm. The amount of natural gas required after the transformation is as follows:


Gas boiler replaces coal-fired energy-saving equivalent standard coal: 3564-2753=811tce


(2) Before the transformation of the roasting system, the company used producer gas as roasting fuel in the shell roasting system, and the direct roaster was a coal gas producer, consuming 2080t of coal.


Generator capacity: 2080*3000=624000m


Modification of the mould shell roasting system, energy saving equivalent standard coal: 1872-1337=535tce


2. Energy saving effect after project implementation


Comprehensive energy saving is 3033tce. The project energy saving is summarized in Table 1.


3. Emission reduction effect after project implementation


The annual emission reductions after the project is put into production are as follows:


The construction of this project can reduce the corresponding pollutant emissions and produce the dual effects of energy saving and environmental protection. After the sewage treatment station is completed and put into use, the estimated reduction of sewage discharge is shown in Table 2.


Our company has reduced the consumption of raw and auxiliary materials, water resources and energy, reduced carbon and nitrogen oxide emissions, and achieved the goal of energy saving. Carry out energy conservation and emission reduction work such as energy conservation and environmental protection technology, equipment technology research, clean energy application, etc., to provide reference for traditional investment casting enterprises to carry out energy conservation and emission reduction work. The realization of energy conservation and emission reduction in the whole society has good economic and social benefits.


According to the principles and methods for determining the energy savings of energy-saving technological transformation projects, and the relevant statistical data released by the National Bureau of Statistics, the discount coefficients used are shown in Table 3.


The clean production process is the whole process control of resources, energy consumption and pollution emissions, which can reduce the resource and energy consumption of various production links, clarify and quantify pollution prevention, promote the technological progress of enterprises in the industry, help enterprises self-position and determine their own resources Saving and environmentally friendly performance improvement. Channels and gaps, through market-driven mechanisms, mobilize the enthusiasm of enterprises to promote cleaner production, and transform cleaner production into conscious behavior of enterprises.