Kinetics and simulation in implementation and enhancement of energy efficiency of biogas plants

Abstract

Disposal of organic waste is a growing civilization problem. For these purposes over the past 10 years we suggest a complex processing of organic waster (CPOW) to fuel gas and other useful products [1, 2]. According to our estimates CPOW disposal allowed solution of environmental problems as well as meeting energy needs by 25–30% of the state as Republic Belarus. CPOW is a multistage process where as one of destruction stages is used biogas stage. In contrast to a simple biogas plants in CPOW an organic waste is treated up to 100% and methane of biogas to maintain a CPOW operational activity is not spent. The operational activity of the complex is provided by obtaining energy in the next, thermal phase of CPOW. Unfortunately, CPOW was implemented only in pilot tests. On the other hand, biogas plants are much easier than CPOW and are becoming more common in the world. If earlier their distribution was natural and characteristic of countries with warm climates (India, China) in the last decade, biogas plants become increasingly common in many countries in Europe, Asia, USA, and South America. Anaerobic biogas processes are easily implemented on the basis of many organic substrates (agricultural waste, waste of treatment facilities, etc.). Biogas plants can eliminate or greatly reduce an amount of burials of organic wastes that are harmful to the environment. Particularly interesting is solution for biogas treatment of livestock and poultry manure with subsequent use of the waste after their biogas processing as fertilizers. In this case, in a whole, there is no the waste after the biogas treatment of raw material and only a task of reaching the highest quality of fertilizer and lowest power consumption should be solved in a methanogenic treatment of organic waste. One biogas plants implemented in Belarus by foreign fi rms is shown in Fig. 1. The plants are of continuous action and equipped with cogeneration units for heat and power supplying which provide the energy needs of the biogas plant. Main apparatuses of the biogas plants, fermenters (digesters), are fairly simple; they are equipped with local agitators, and by the form similar to cylindrical vessels made of reinforced concrete of 1500–2000 m3. Inside the concrete walls there are pipes for heating the digesters and maintaining the thermal regime in them.