JPS5925640B2 - Organic waste processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an apparatus for treating organic waste such as organic waste liquid and organic sludge, and in particular, anaerobically digests organic waste to generate digestion gas containing methane. The present invention relates to an organic waste treatment device that can be used to process organic waste with high thermal efficiency.

As a treatment device for highly concentrated organic waste such as sewage sludge or human waste, a device that performs anaerobic digestion in a digestion tank is employed.

Anaerobic digestion utilizes the activity of anaerobic bacteria to decompose organic matter under anaerobic conditions.The temperature must be maintained at an appropriate temperature for bacterial activity, and the temperature is usually heated to approximately 35°C in the first digestion tank. In the second digestion tank, the temperature is maintained at approximately 32°C without heating.

In order to heat such a digestion tank, the digestion gas generated from the digestion tank is used. Steam is mainly generated in a waste heat boiler that uses the digestion gas as fuel, and this is used in the first boiler.
It is introduced into a digestion tank and heated.

In order to effectively utilize surplus digestion gas, it has also been proposed to use a gas turbine or gas engine to drive a generator or blower, and use the waste heat to heat the system.

However, the conventional heating method described above uses digestion gas as fuel and uses the heat generated at that time, so the heat amount of the digestion gas minus the loss is used for heating. It was as much as possible.

This invention was made in order to further improve the thermal efficiency of the conventional processing equipment as described above, and it uses digestion gas as fuel to provide a gas emethane for driving a heat pump and a gas engine for driving other loads such as a generator. In addition to recovering heat from the desorbed liquid and digested sludge using a heat pump, waste heat is sequentially recovered from cooling water and waste gas for each gas engine to generate hot water, and this hot water is used to heat organic waste. The purpose of this study is to propose an organic waste treatment device that can effectively recover and utilize heat and perform treatment with high thermal efficiency.

The present invention includes a digestion tank that anaerobically digests organic waste, a storage tank that stores digestion gas containing methane generated from the digestion tank, and a gas engine that uses the digestion gas from the storage tank as fuel to drive a heat pump. and the same (another gas engine that uses digestion gas as fuel to drive a load including a generator, and a first heat source for recovering heat from the desorbed liquid and digested sludge released from the digestion tank by the heat pump) an exchanger, a second heat exchanger that recovers heat from the cooling water of each gas engine, a third heat exchanger that recovers heat from the waste gas of each gas engine, and heat radiated from the heat pump. a hot water tank for storing hot water generated by recovering waste heat sequentially from the first and second heat exchangers for each of the gas engines after absorbing the waste heat with cooling water; This is an organic waste processing device that includes a heater that heats things.

Hereinafter, the present invention will be described with reference to embodiments shown in the drawings.

The drawing is a system diagram showing an embodiment of the present invention, where 1 is a first digestion tank and 2 is a second digestion tank.

An introduction pipe 3 communicates with the first digestion tank 1 via a heater 4,
Also, the communication pipe 5 goes to the second digestion tank 2, and the circulating fluid pipe 6 goes to the introduction pipe 3.
A gas take-off pipe 7 is connected to a desulfurizer 8, respectively.

From the second digestion tank 2, the desorbed liquid pipe 9 and the sludge drainage pipe 10 go to the heat exchanger 11, the return pipe 12 goes to the first digestion tank 1, and the gas extraction pipe 1
3 is connected to the desulfurizer 8.

A communication pipe 14 connects the desulfurizer 8 to a storage tank 15.

A gas supply pipe 16 is connected from the storage tank 15 to a waste heat boiler 17 and gas engines 18 and 19.

The waste heat boiler 17 generates steam using digestion gas as fuel, and includes an auxiliary fuel pipe 20 and a waste gas pipe 21.
A steam pipe 22 communicates with the first digestion tank 1 .

The gas engines 18 and 19 are internal combustion engines that use digestion gas as fuel, and the waste gas pipes 23 and 24 are connected to the heat exchanger 25.
．． 26, engine cooling water pipes 27 and 28 form a circulation path with heat exchangers 29 and 30, and a heat pump 33 is connected to the engine drive shaft via couplings 31 and 32.
A compressor 34 and a load 35 such as a generator and a blower are connected.

Note that the gas engine 18.19 also has an auxiliary fuel pipe 20a,
20b, and an auxiliary gas supply pipe 16a such as natural gas is connected to the gas supply pipe 16.

In the heat pump 33, a heat medium pipe 36 from the compressor 34 passes through a condenser 37, an expansion valve 37a, and an evaporator 38 to form a circulation path, and a heat absorption pipe 39 is provided between the evaporator 38 and the heat exchanger 11. It forms a circulation path.

Further, heat recovery pipes 40 and 41 branch from the condenser 37 and communicate with a hot water tank 42 via heat exchangers 29.25 and 30.26, and a hot water pipe 43 connects the heater 4 from the hot water tank 42. It communicates with the condenser 37 via the condenser 37 to form a circulation path.

44 is a water supply pipe, and 45 to 50 are valves.

Note that the illustration of the pump and the like in the container pipe 1 is omitted.

In the organic waste treatment apparatus configured as described above, organic waste to be treated such as human waste is introduced from the introduction pipe 3, heated by the heater 4, and then thrown into the first digestion tank 1. It is heated to a temperature suitable for digestion (approximately 35° C.) by steam introduced from the steam pipe 22, and remains in an anaerobic environment for several days to undergo anaerobic digestion.

During this time, the contents in the tank are intermittently transferred from the communication pipe 5 to the second digestion tank 2, and also circulated from the circulating liquid pipe 6 to the introduction pipe 3, and the generated digestion gas 1 is taken out from the gas extraction pipe 7. .

In the second digestion tank 2, it is not heated (it is kept there for several days, and the temperature is maintained at a temperature suitable for digestion (approximately 32°C).
Anaerobic digestion continues.

After the digestion in the second digestion tank 2, the desorbed liquid is transferred to the desorbed liquid pipe 9.
is discharged from the activated sludge treatment equipment (
(not shown), etc., and undergoes further advanced processing.

A part of the digested sludge in the second digestion tank 2 is returned to the first digestion tank 1 from the return pipe 12, and the remaining part is sent from the sludge removal pipe 10 to the heat exchanger 11.
The sludge is then discharged to a sludge treatment equipment (figure; not shown) and dehydrated.
Receive treatment such as incineration.

Digestion gas containing methane generated in the first digestion tank 1 and the second digestion tank 2 is taken out from the gas extraction pipe 7゜13, sulfur compounds such as hydrogen sulfide are removed in the desulfurizer 8, and stored in the storage tank 15. be done.

The digestion gas in the storage tank 15 is supplied from a gas supply pipe 16 to a waste heat boiler 17 and gas engines 18, 19, and is used as fuel.

In the waste heat boiler 17, the digestion gas and, if necessary, the auxiliary fuel from the auxiliary fuel pipe 20 are combusted to generate steam,
It is supplied from the steam pipe 22 to the first digestion tank 1 and used to heat the organic waste.

In the gas engine 19, the engine is started using the digestion gas as fuel, and a load 35 such as a generator or a blower connected to its drive shaft is driven, and the engine is effectively used as electric power or compressed air.

The waste gas from the gas engine 19 is discharged from the waste gas pipe 24 via the heat exchanger 26, and the cooling water is circulated between the heat exchanger 30 and the heat exchanger 30 through the cooling water pipe 28.

In the gas engine 18, the engine is similarly started using digestion gas as fuel, the compressor 34 connected to the drive shaft is driven, the waste gas is discharged from the waste gas pipe 23 via the heat exchanger 25, and the cooling water is supplied to the engine. It circulates between the cooling water pipe 27 and the heat exchanger 29 .

As the compressor 34 is driven, the heat medium in the heat medium pipe 36 is compressed in the heat pump 33 and becomes high pressure gas, which is then transferred to the condenser 37.
It is cooled down, loses the heat of condensation and becomes a liquid (heat radiation), is depressurized through the expansion valve 37a, is evaporated in the evaporator 38 to perform a refrigeration action, absorbs heat, and is circulated to the compressor 34.

In the heat exchanger 11 , the heat medium (water) in the heat absorption tube 39 is mixed with the desorbed liquid in the desorbed liquid tube 9 , the digested sludge in the sludge drain pipe 10 , and the treated water and other water in the water supply tube 44 . It exchanges heat and absorbs heat, and in the evaporator 38 it exchanges heat with the heat medium in the heat medium pipe 36 to radiate and circulate the heat.

In the condenser 37, the heat radiated from the heat medium is absorbed by the hot water (heat medium) circulating from the hot water pipe 43, and the heated hot water is diverted to the heat recovery pipe 40, 41, and transferred to the heat exchanger 29.
, 30, the heat exchanger 25.26 exchanges heat with the cooling water.
Waste heat is recovered from the gas engine 18, 19 by heat exchange with the waste gas, and is stored in the hot water tank 42.

Then, the hot water in the hot water tank 42 heats the organic waste in the introduction pipe 3 and the circulating liquid pipe 6 in the heater 4, lowers the temperature, and circulates to the condenser 37.

Note that if there is no input from the introduction pipe 3 at this time, only the circulating fluid pipe 6 is heated.

Furthermore, it is also possible to stop the flow of the circulating fluid pipe 6 and heat only the introduction pipe 3, if necessary.

In this way, by driving the heat pump 33, heat is recovered from the desorbed liquid, digested sludge, treated water, etc. in the heat exchanger 11, and this heat is radiated in the condenser 37 to warm the hot water, After the waste heat from the gas engines 18 and 19 is recovered using this hot water, the organic waste to be treated can be heated in the heater 4.

Therefore, in addition to the heat of the digestion gas itself, the heat recovered from the desorbed liquid can be used to heat organic waste.
The overall thermal efficiency is 150 to 300% of that of conventional equipment, and the excess digestion gas can be effectively used as an energy source such as electricity and compressed air.

In addition, in the above embodiment, the heater 4 was used to heat the organic waste, but the heating may be performed directly within the first digestion tank 1.

Further, although the waste heat boiler 17 is not necessarily required, it can supply digestion gas when implementing the present invention in an existing device or when installing it as a backup in case of failure of the heat pump system.

In the heat exchanger 11, heat is recovered from water supply such as desorbed liquid, digested sludge, and treated water as a heat source.
Furthermore, other heat sources may be used.

Since the desorbed liquid and digested sludge are discharged at high temperatures, recovering heat from them has the advantage of extremely good thermal efficiency.

On the other hand, treated water obtained by treating the desorbed liquid with activated sludge treatment or the like has a slightly lower temperature, but there is little risk of contamination, so it can be used in combination as a heat source.

In addition, thermal wastewater from incinerators, industrial water, etc. can also be used as a heat source, and in some cases, it is also possible to recover heat from the atmosphere.

In the above description, there are no particular restrictions on the type, structure, etc. of the gas engine, heat pump, heat exchanger, etc., and any one can be used.

Further, the type, structure, and combination of the digester and its accompanying equipment can be changed as appropriate.

Furthermore, organic waste to be treated by the present invention includes:
This includes anything that can be digested anaerobically, such as human waste, sewage sludge, and pulp and paper mill effluent.

When shutting off the water supply pipe 44, the valve 45 is closed, and the gas supply pipe 16 is connected to the waste heat boiler 17 and the gas engine 18.19.
To stop the supply of digestion gas to the heat recovery pipes 40 and 41, the valves 48 to 50 are closed, and to stop the supply of hot water to the heat recovery pipes 40 and 41, the valves 46 and 47 are closed, and the operation of each device can be switched. can.

Note that if the amount of digestion gas is insufficient and there is a gas source such as natural gas, gas is supplied to the gas supply pipe 16 from the auxiliary gas supply pipe 16a.

As described above, according to the present invention, a gas engine for driving a heat pump and a gas engine for driving other loads such as a generator are provided using digestion gas as fuel, and heat is recovered from the desorbed liquid and digested sludge by the heat pump. With,
Waste heat is sequentially recovered from the cooling water and waste gas for each gas engine to generate hot water, and this hot water is used to heat the organic waste, so that the heat added to the organic waste can be desorbed. It can be recovered and reused from liquid and digested sludge, and waste heat can be recovered from gas engines used to drive heat pumps and loads such as generators and used for digestion.
In this case, since heat is recovered for each gas engine, it is possible to efficiently recover heat according to the operating status of the gas engine.In addition, since heat is recovered in the order of the heat pump, gas engine cooling water, and waste gas, it is possible to recover heat according to the amount of heat contained. It is possible to effectively recover heat, and the hot water generated by heat recovery can be stored, so it can be heated efficiently according to the flow rate of organic waste, which makes it possible to process organic waste with high thermal efficiency. It can be carried out.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawing is a system diagram showing an embodiment of the present invention, in which 1 is a first digestion tank, 2 is a second digestion tank, 3 is an introduction pipe, 4 is a heater,
8 is a desulfurizer, IL25, 26° 29.30 is a heat exchanger,
15 is a storage tank, 17 is a waste heat boiler, 18 and 19 are gas engines, 33 is a heat pump, 34 is a compressor, 35 is a load, 37 is a condenser, 38 is an evaporator, and 42 is a hot water tank.

Claims (1)

[Claims] 1. A digestion tank for anaerobically digesting organic waste, a storage tank for storing digestion gas containing methane generated from the digestion tank, and a heat pump using the digestion gas from the storage tank as fuel. A gas engine that drives the same engine (with another gas engine that uses digestion gas as fuel to drive a load including a generator! a first heat exchanger; a second heat exchanger that recovers heat from the cooling water of each gas engine; a third heat exchanger that recovers heat from the waste gas of each gas engine; A hot water tank for storing hot water produced by absorbing the radiated heat by cooling water and then sequentially recovering waste heat from the first and second heat exchangers for each of the gas engines; An apparatus for treating organic waste, including a heater that heats the organic waste. 2. Claim 1, wherein the heat pump absorbs heat from treated water that has been treated with a desorbed liquid. The described organic waste treatment equipment.