JP2005111344A - Methane fermentation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a methane fermentation apparatus constituted so that the optimum amount of the slurry to be supplied to this apparatus can be controlled for coming several weeks by considering the scheduled amount of the slurry to be received and a methane fermentation tank can be operated most efficiently including a slurry adjusting tank. <P>SOLUTION: This methane fermentation apparatus is provided with the slurry adjusting tank 3, a water level gauge 6, the methane fermentation tank 4, a slurry supplying pump 5, a biogas flow meter 8, an input indicator 1 for inputting/indicating the scheduled amount of the slurry to be received in the slurry adjusting tank 3 and a controller 2. The controller 2 has a first calculating means for calculating an upper limit value of the amount of the slurry to be supplied on the basis of the flow rate of a biogas, a second calculating means for predicting/calculating a scheduled value of the amount of the slurry to be supplied on the basis of the amount of the slurry to be received, the volume of the slurry adjusting tank, the present water level of the slurry adjusting tank and the process capacity of the methane fermentation tank, and a decision means for comparing the scheduled value with the upper limit value to output any of them. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a methane fermentation treatment apparatus that uses anaerobic microorganisms to treat organic waste such as garbage, food processing residue, surplus sludge such as activated sludge treatment.

  In the methane fermentation treatment, organic waste is pulverized and slurried, and then this slurry is put into a fermenter and fermented with methane bacteria under anaerobic conditions to decompose the organic waste into biogas and water. This method is advantageous in that the amount of organic waste can be greatly reduced and methane gas produced as a by-product can be recovered as energy. In addition, since it is anaerobic and does not require aeration power, it is an energy-saving treatment method.

  This methane fermentation is operated under moderate temperature (around 35 ° C.) or high temperature (around 55 ° C.), and has a residence time of about 30 days at medium temperature and a residence time of about 15 days at high temperature. It is common to use a tank.

  However, since organic waste is generated with daily social activities and industrial production activities, it is necessary to operate the plant efficiently so that the processing of organic waste is not delayed. For this reason, in preparation for a trouble, the apparatus is multiplexed or the tank volume is increased to increase the safety factor.

  As a method for efficiently performing the methane fermentation treatment, for example, in Patent Documents 1 and 2 below, the methane production rate in the generated biogas is measured, and the supply amount of the slurry is adjusted according to the production rate. It is disclosed.

Patent Documents 3 and 4 listed below disclose methods for monitoring and controlling the processing capacity of methane-producing bacteria in a methane fermentation tank, and measuring the amount of biogas generated and the methane concentration in the biogas. It is disclosed to control the amount of slurry supplied.
JP 59-225796 A Japanese Patent Laid-Open No. 10-277583 JP 2002-282897 A Japanese Patent Laid-Open No. 11-253149

  As mentioned above, since the amount of organic waste generated changes day by day, the methane fermentation treatment equipment, one of the waste treatment equipment, is also capable of changing the load of organic waste that changes daily. It is necessary to follow within a certain range.

  In addition, since methane fermentation decomposes organic matter by the action of microorganisms such as methane bacteria in the tank, the organic matter is killed and the methane bacteria are reduced in a state where the organic matter is not supplied, and the processing ability of the organic matter is reduced. And even if the supply of organic matter is resumed, the processing capacity does not recover immediately. Therefore, it is necessary to give an organic load corresponding to the processing capacity and acclimatize to the processing capacity according to the plan. Therefore, it is necessary to estimate the amount of organic waste that can be accepted in advance in consideration of the change in the processing capacity.

  However, the control methods described in Patent Documents 1 to 4 above all monitor the fermentation state using only the information obtained from the generated biogas, and feed it back to the slurry supply amount to methane fermentation. The tank is operated stably, and only the current operation state of the methane fermentation tank is a control parameter.

  Therefore, in the above prior art, it has not been studied to determine the optimum slurry supply amount in consideration of the amount of slurry to be received in the future, including the adjustment tank that receives the slurry.

  Accordingly, an object of the present invention is to perform optimal control of the amount of organic waste slurry supplied according to the organic waste processing capacity of the methane fermentation tank in the methane fermentation processing apparatus including the adjustment tank that receives the slurry. An object of the present invention is to provide an apparatus for methane fermentation treatment.

That is, the methane fermentation treatment apparatus of the present invention is a slurry adjustment tank that receives and accepts organic waste as a slurry,
A water level meter for measuring the current water level of the slurry adjustment tank;
A methane fermentation tank for methane fermentation of the slurry to generate biogas;
Slurry supply means for supplying the slurry from the adjustment tank to the methane fermentation tank;
A biogas flow meter for measuring a biogas flow rate generated in the methane fermentation tank;
Input display means for inputting and displaying the expected amount of the slurry received in the adjustment tank;
A slurry control means for controlling the amount of slurry supplied to the methane fermentation tank,
The slurry control means, a first calculation means for calculating an upper limit value of the amount of slurry that can be supplied to the methane fermentation tank based on the biogas flow rate,
Second calculation means for predicting and calculating the planned value of the amount of slurry to be supplied based on the expected amount of slurry received, the capacity of the adjustment tank, the current water level of the adjustment tank, and the processing capacity of the methane fermentation tank When,
When the planned value is less than or equal to the upper limit value, the planned value is output as the supply slurry amount, and when the planned value exceeds the upper limit value, the upper limit value is output as the supply slurry amount. Means.

  According to the methane fermentation treatment apparatus of the present invention, based on the expected amount of slurry received, the capacity of the adjustment tank, the current water level of the adjustment tank, and the processing capacity of the methane fermentation tank, Predictive calculation can be performed. Therefore, in consideration of the situation of the expected amount of slurry received, the optimum amount of slurry to be fed up to several weeks ahead can be controlled, and the methane fermentation tank including the adjustment tank can be operated most efficiently. Moreover, since it can drive | operate so that an upper limit may not be exceeded by the determination means, the failure | damage of the methane fermentation tank by overload can be prevented.

  In this invention, the said 2nd calculating means calculates the future scheduled water amount in the said adjustment tank based on the scheduled acceptance amount of the said slurry, and the processing capacity of the said methane fermentation tank, and this scheduled water amount is the said adjustment tank. It is preferable to have a supply amount prediction calculation means for outputting the planned value so that the planned water amount does not become negative.

  According to this, when the amount of the received slurry is scheduled to decrease, the amount of the supplied slurry can also be decreased, and conversely, when the amount of the received slurry is scheduled to increase, the amount of the supplied slurry can also be increased. As a result, the methane fermenter can be operated in an optimum state according to the schedule of receiving the slurry. In addition, since the adjustment tank can be used to the maximum as a buffer, fluctuations in the amount of slurry supplied can be prevented and stable methane fermentation treatment can be performed.

Further, in the present invention, the supply amount prediction calculation means outputs a predicted value that is a planned value for each future time together with the planned value, and based on the predicted value and a growth or death model of methane bacteria. An upper limit predicted value calculating means for calculating and outputting an upper limit predicted value that is an upper limit of the predicted value,
It is preferable that the supply amount prediction calculation unit includes a calculation unit that corrects the planned value to be equal to or lower than the upper limit predicted value when the planned value exceeds the upper limit predicted value.

  In the methane fermentation, when the slurry is not supplied, the methane bacterium is killed and methane bacteria are reduced to reduce the organic matter processing ability. Even if the organic matter supply is resumed, the processing ability is not recovered immediately. However, according to the said invention, since the amount of supply slurry can be controlled according to the capability of the methane fermenter which changes with the amount of supply slurry, the operation | movement of the more stable methane fermentation processing apparatus is attained.

  Furthermore, in the present invention, it is preferable that the input display means includes a warning means for restricting the slurry receiving input in the input display means when the planned value exceeds the upper limit predicted value.

  According to this, it is possible to know in advance whether or not the amount of the slurry received exceeds the processing capacity of the methane fermenter at the scheduled input time to the input indicator. Accordingly, it is possible to prevent in advance an erroneous reception of excess organic waste. Further, the excess can be processed by being sent to another processing facility, and the processing between the plurality of processing facilities can be smoothed.

  Moreover, in this invention, it is preferable that the said upper limit in the said 1st calculating means is calculated by the following (1)-(3) formula.

Gasified organic matter (kg-TOD / h) = 0.35 x biogas flow rate (m ³ / h) x methane concentration in biogas (-) ----------- (1)
Gasified slurry volume (L / h) = Gasified organic matter (kg-TOD / h) ÷ Slurry TOD concentration (kg_TOD / L) ----------- (2)
Upper limit (L / h) = gasified slurry amount (L / h) ÷ A ------ (3)
(TOD represents total oxygen demand, A represents the decomposition rate of TOD, and represents a constant of 0.4 to 0.8.)
According to this, since the present processing capacity of the methane fermenter can be accurately grasped, it is possible to effectively prevent supply of excess slurry exceeding the processing capacity.

  According to the present invention, the optimum amount of slurry to be fed up to several weeks ahead can be controlled in consideration of the situation of the expected amount of slurry received, and the methane fermentation tank including the adjustment tank can be operated most efficiently. In addition, the amount of organic waste received into the methane fermentation equipment can be determined according to the future prediction capability of the methane fermenter, so it can be determined whether it can be accepted. The optimal operation plan of methane fermentation equipment can be made.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. 1-8 shows one Embodiment of the methane fermentation processing apparatus of this invention.

  FIG. 1 is a schematic configuration diagram showing an embodiment of the methane fermentation treatment apparatus of the present invention, and FIG. 2 is a diagram showing a screen on which the expected amount of slurry received in the input display of the treatment apparatus is shown. FIG. 4 is a diagram showing a screen displaying the inputted slurry acceptance schedule and the expected amount of slurry in the adjustment tank in the input display of the processing apparatus.

  4 is a control block diagram of a slurry supply pump in the control device of the processing apparatus, FIG. 5 is a developed block diagram of the processing capacity calculator in FIG. 4, and FIG. 6 is a supply amount prediction calculation in FIG. FIG. 7 is a block diagram in which the processing capacity upper limit predicted value calculator in FIG. 4 is developed.

  Further, FIG. 8 is a diagram showing a decrease in the number of bacteria when no slurry is added, FIG. 9 is a diagram showing an increase in the number of bacteria when slurry is supplied, and FIG. 10 is a process of FIG. FIG. 11 is a block diagram that embodies the capability prediction calculator, and FIG. 11 is a diagram showing a screen that displays the calculated supply slurry upper limit prediction value and the supply slurry prediction value to the fermenter in the input display of the processing apparatus. .

  As shown in FIG. 1, this methane fermentation treatment apparatus includes an adjustment tank 3 that temporarily stores slurry, a methane fermentation tank 4, and a slurry supply that supplies organic waste to the methane fermentation tank 4 in a slurry state. A pump 5, a biogas flow meter 8 for measuring the biogas flow rate in the methane fermentation tank 4, an input indicator 1 for inputting and displaying the expected amount of the slurry received in the adjustment tank 3, and a slurry supply pump 5 And a control device 2 for controlling the amount of slurry to be supplied.

  The organic waste is passed through a crushing device (not shown) and then received into the adjustment tank 3 as a slurry with the washing water. The acceptance amount at this time is an amount inputted in advance to the input display 1.

  Then, the slurry is supplied from the adjustment tank 3 to the methane fermentation tank 4 by the slurry supply pump 5 whose flow rate is controlled. As a result, the organic waste is anaerobically treated by microorganisms such as methane bacteria in the methane fermentation tank 4, decomposed into biogas mainly composed of methane and carbon dioxide, and the methane fermentation tank 4 as generated biogas. It is discharged from the pipe connected to the upper space. In addition, undecomposed organic matter is discharged as fermentation waste liquid.

  The adjustment tank 3 is a storage tank for slurrying and receiving organic waste. The adjustment tank 3 is connected to a water level meter 6 for measuring the current water level of the slurry in the adjustment tank. The water level is sent to the control device 2. In general, the adjustment tank 3 preferably has a capacity capable of storing the receiving slurry for one day.

  The piping from the adjustment tank 3 is connected to the methane fermentation tank 4 via the slurry supply pump 5 and the slurry concentration meter 7. In the present invention, the slurry concentration meter 7 is not always necessary.

  A pipe for taking out the fermentation waste liquid is connected to the upper part of the methane fermentation tank 4. In addition, a pipe for taking out the produced biogas is connected to the upper space of the methane fermentation tank 4, and this pipe is collected in a gas holder (not shown) and used as energy in a gas utilization system such as a gas turbine or a fuel cell. It is configured to be used.

  A pipe for taking out the biogas is provided with a biogas flow meter 8 and a methane concentration meter 9, and each measured value is sent to the control device 2. An input indicator 1 is connected to the control device 2, and the expected amount of slurry received is input to the input indicator 1. In the present invention, the methane concentration meter 9 is not always necessary.

  For example, an input screen as shown in FIG. 2 is displayed on the input display 1, and information relating to the expected amount of slurry received can be input.

  FIG. 2 shows a screen in which the values of the slurry acceptance schedule for two weeks can be input and displayed on the touch panel. For example, FIG. 2 shows an example in which 10 t of slurry is input every day from Monday to Saturday, and no reception is performed at 0 t on Sunday. Moreover, the acceptance of the slurry is scheduled to be received in 9 to 9 o'clock and 14 to 16 o'clock divided into 6 times. Note that the display of the current day, the previous day, and the previous day in FIG. 2 is scrolled according to the calendar. As will be described later, in this input, when the input amount of the received slurry is excessive with respect to the fermenter capacity, the input window blinks and the input is not accepted.

  FIG. 3 is an example of another screen displayed on the input display 1 and shows a predicted state of the amount of slurry in the adjustment tank 3. The solid line in FIG. 3 indicates the planned acceptance amount in FIG. Moreover, the dotted line has shown the estimated water level in the adjustment tank 3 mentioned later. Thus, it is possible to know at which time of each day of the week the adjustment tank is full, and display it to facilitate correction of the slurry acceptance schedule. In the example of FIG. 3, the predicted time 0 indicates 0:00 on Friday, and the supply amount of slurry is reduced from 20:00 in preparation for Sunday. The adjustment tank is almost full after 40 hours (Saturday at 16:00) and empties 80 hours after the next acceptance (Monday at 8:00).

The control device 2 is a programmable logic controller having various operations and sequence control functions. As shown in FIG. 2, the control device 2 includes a water level measured by a water level meter 6, a slurry concentration by a slurry concentration meter 7, a bio The biogas flow rate by the gas flow meter 8, the methane concentration in the biogas by the methane concentration meter 9, and the expected amount of slurry received from the input display 1 described later are input. And it is comprised from the control apparatus 2 so that the output for controlling the slurry supply pump 5 may be output.

  FIG. 4 is a control block diagram of the slurry supply pump 5 in the control device 2. This block diagram includes a processing capacity calculator S10, a low level selector S20, a pump flow rate characteristic conversion calculator S30, a supply amount prediction calculator S40, and an upper limit predicted value calculator S50.

  First, to the processing capacity calculator S10, the measured biogas flow rate that is the output of the by-gas flow meter 8, the measured methane concentration that is the output of the methane concentration meter 9, and the measured slurry concentration that is the output of the slurry flow meter 7 are input. From here, the upper limit value is output and input to the low level selector S30. This upper limit value is for monitoring the fermentation state from information from the generated biogas and calculating the upper limit of the slurry supply amount so that the methane fermentation tank 3 does not fail.

  FIG. 5 is a developed block diagram of the processing capacity calculator S10. As shown in FIG. 5, the processing capacity calculator S10 is divided into three steps: a gasified organic substance calculation S11, a gasified slurry quantity calculation S12, and a processable slurry quantity calculation S13. I know.

  In the calculation S11 of the gasified organic matter, the gasified organic matter (kg-TOD / h) is obtained by the following equation (1).

Gasified organic matter (kg-TOD / h) = biogas amount (m3 / h) x methane concentration (-) x 0.35 (kg / m3) ----------- (1)
Here, TOD is the total oxygen demand, and is one of the indicators showing the amount of organic matter. 0.35 is a TOD conversion coefficient of methane, and 1 m ³ of methane is a value indicating that the TOD corresponds to 0.35 kg. Moreover, the value converted into 0 degreeC, 1 atmosphere, and a dry state is used for the amount of biogas.

  In the present invention, the methane concentration may be input as an actual measurement value by the methane concentration meter 9, but may be treated as a constant when the property change of the organic waste is small. For example, in the case of garbage, since the methane concentration is 55 to 60%, 0.55 to 0.58 can be used as the methane concentration in the formula (1).

  Next, in calculation S12 of the gasified slurry amount, the gasified slurry amount (L / h) is obtained by the following equation (2).

Gasified slurry volume (L / h) = Gasified organic matter (kg-TOD / h) ÷ Slurry TOD concentration (kg-TOD / L) ----------- (2)
As the TOD concentration of the slurry, a value obtained by converting the viscosity and electrical conductivity measured by the slurry concentration meter 7 into TOD may be used, or an average value measured in advance may be used as a constant. For example, 0.10 to 0.14 kg-TOD / L can be used as the TOD concentration of a slurry obtained by adding 1.5 parts by weight of dilution water to 1 part by weight of raw garbage.

  Finally. In calculation S13 of the amount of slurry that can be processed, the upper limit value of the amount of slurry that can be supplied to the methane fermentation tank 3 is output by the following equation (3).

Processable slurry volume (L / h) = Gasified slurry volume (L / h) ÷ A ------ (3)
Here, A represents the decomposition rate of TOD, and A is preferably 0.4 to 0.8, more preferably 0.5 to 0.7, and particularly preferably 0.65. When A is less than 0.4, undegraded products accumulate in the fermentor, and acetic acid and propioic acid accumulate in the fermentor, resulting in poor fermentation efficiency. In the present invention, since the supply slurry planned value is calculated so as not to exceed the fermenter capacity, it is sufficient even if it is smaller than the general decomposition rate (about 0.8). When A exceeds 0.8, the next slurry supply amount becomes less than the slurry processing capacity of the methane fermentation tank, and the slurry supply amount converges in the direction of 0, which is not preferable.

  Next, the supply amount prediction calculator S40 receives the measurement adjustment tank water level, which is the output of the water level gauge 6, and the expected amount of slurry input by the operator from the input display 1 as shown in FIG. By this supply amount prediction calculator S40, the future amount of slurry received is taken into consideration, and the methane fermenter can be operated in an optimum state according to the expected amount of slurry received.

  FIG. 6 is a conceptual diagram showing the contents of the calculation in the supply amount prediction calculator S40 in FIG. 4. In the figure, the vertical axis is a change in the amount of water, and the horizontal axis is an estimated time (t ).

  In FIG. 6, the amount of slurry received from the schedule for receiving slurry into the adjustment tank 3 is integrated as an integrated water amount. That is, since this accumulated water amount changes according to the expected amount of slurry received (integrated water amount increase factor), it usually changes stepwise as shown in FIG.

  Then, the slope of the straight line connecting the origin and the integrated value (drawing integrated amount) in FIG. 6 is output as the planned value.

  The slope of this straight line is below the line indicating the integrated water amount as shown in FIG. 6 and is selected so as not to intersect the line indicating the integrated water amount, and the difference between the line indicating the integrated water amount and the drawn integrated amount Is calculated so as not to exceed the adjustment tank capacity (location t2). In particular, it is preferable that the line is selected so as to be in contact with the line indicating the accumulated water amount at one point (location of t1) as shown in FIG.

That is, the accumulated amount of water a _t at time t, the withdrawal integrated amount and b _t at time t, if the adjustment tank capacity and X,
_X> a t _{-b t>} 0
The planned value is calculated so that The inclination of the straight line intersects the line indicating the accumulated amount of water _{(a t -b t <0)} , the amount of feed slurry (pulling accumulated amount) reservoir temporarily too much is empty. Further, the pull-out cumulative amount relative to a line indicating the accumulated amount of water is too low _{(X <a t -b t)} , overflows adjusting tank capacity is too small, the supply amount of the slurry.

  One of the outputs from the supply amount prediction calculator S40 is the above-described plan value, and this plan value is input to the low level selector S30, and a comparison determination is made between the plan value and the upper limit value. As a result, when the planned value is less than or equal to the upper limit value, the planned value is selectively output as the supply slurry amount and input to the pump flow rate characteristic conversion computing unit S30 to drive the slurry supply pump 5 (VVVF). A signal is output to control the pump. On the other hand, when the plan value exceeds the upper limit value, the upper limit value is selected. As a result, the amount of the slurry to be supplied is controlled below the upper limit at all times.

  Since the slurry supply pump 5 is controlled based on the planned value in the normal operation state, the optimum supply slurry amount up to a few weeks ahead can be controlled and adjusted in consideration of the expected amount of slurry received. The methane fermentation tank including the tank can be operated most efficiently.

  On the other hand, a predicted value is output from the supply amount prediction calculator S40 as another output. Here, the predicted value is a planned value for each predicted time in the future corresponding to the state of acceptance of the slurry. This predicted value is input to the upper limit predicted value calculator S50.

  FIG. 7 is a block diagram in which the upper limit predicted value calculator S50 in FIG. 4 is developed. This block diagram comprises an integrator S51, a conversion operation S52 from the amount of methane bacteria to the amount of supplied slurry, and a fungus growth killing operation S53.

  When the supply amount of the organic waste slurry as the feed is reduced, the growth amount of the fungi in the fermenter also decreases. When the supply amount of the slurry is increased, the growth amount of the fungi also increases. In addition, there is a certain proportion of killed bacteria in proportion to the number of bacteria. The proliferation / death of this fungus is calculated by the integrator S51 and the fungus growth / killing calculation S53, and the amount of this fungus is converted into the amount of slurry that can be processed in S52 and output as the supply slurry upper limit predicted value.

  That is, when the amount of killing is greater than the growth of bacteria due to the decrease in the amount of slurry supplied, the predicted upper limit value of the slurry supplied decreases. On the other hand, when the amount of supply slurry increases, the amount of bacterial growth increases, and the supply slurry upper limit predicted value increases.

  The bacterial growth / killing calculation S53 in the upper limit predicted value computing unit S50 is composed of the following formulas for bacterial growth / killing used in biochemical engineering.

  FIG. 8 shows the measurement of the change in the number of bacteria when no slurry, which is a bait for bacteria, is added, and the curve can be approximated by the following equation.

Number of bacteria after t days = initial number of bacteria × exp (−0.16 × t)
That is, 16% of bacteria are killed and decreased per day.

  FIG. 9 shows the number of bacteria when the slurry is supplied to the fermentor using the supply slurry upper limit value, which is the output of the slurry processing capacity calculator of FIG. The curve can be approximated by:

Number of bacteria after t days = initial number of bacteria × exp (0.28 × t)
That is, it shows that the bacteria grow by 28% per day.

  This growth rate depends on the bait concentration of the bacteria in the fermenter, and can be generally expressed by the following approximate equation called the mono equation.

μ = μm × s / (Ks + s) ------ Mono formula For example, 0.28, which means 28% growth of bacteria per day, is an apparent rate including the death rate in the above formula Corresponds to μ. Here, s is the food concentration and Ks is the maximum growth rate. The feed concentration can be represented by measuring the soluble TOD in the fermenter, and Ks can be calculated from the relationship between the residence time of the liquid in the fermenter and the feed concentration. In addition, the relationship between the removed TOD and the number of grown bacteria is made constant as the growth yield.

  The relationship between the amount of slurry supplied and the amount of bacteria under stable load conditions can be made constant as a conversion value from the amount of bacteria to the amount of slurry supplied. Table 1 shows the kinetic constants of these bacteria obtained from the operating data of the fermenter.

  FIG. 10 shows an example in which the upper limit predicted value calculator S50 of FIG. 7 is embodied. This block diagram uses the MATLAB-SIMULINK notation system sold by Cybernet Systems Inc. to explain the program.

  In FIG. 10, lines connecting the blocks indicate signal input / output, and the inside of the block is a transfer function, which is “input × constant in block = output”. Q in FIG. 10 is the predicted supply slurry value in FIG. 7, and the slurry flow rate for each hour is input.

  In the figure, QH is the supply slurry upper limit predicted value of FIG. 7, and the upper limit value of the slurry flow rate for each hour is output.

  In the condition where the fermenter is not overloaded, QH> Q, but when the result of QH <Q is output, Q in the feed slurry prediction table is corrected so that QH => Q. Using this corrected Q, the amount of slurry in the adjustment tank is re-predicted. If the amount of slurry exceeds the adjustment tank capacity, an alarm is output to the slurry acceptance schedule as shown in FIG. 2 to prompt the correction of the schedule. Take action.

  The calculation in FIG. 10 may be performed when the slurry acceptance schedule is input to the input display 1. If the slurry according to the planned value fed back to the schedule is input, the gas generation shown in FIG. The supply slurry amount is not limited by the supply slurry upper limit calculated from the amount.

  However, when disturbance such as unexpected mixing of an inhibitor into the slurry or erroneous control of the temperature of the fermenter occurs, there is a deviation between the calculation in FIG. 10 and the growth / killing rate of the bacteria in the actual fermenter. The supply slurry amount is limited by the supply slurry upper limit value calculated from the generation amount. In this case, an alarm can be sent to the input display 1 to prompt the cause.

  FIG. 11 is a screen that displays the amount of slurry in the adjustment tank with respect to the predicted slurry reception schedule obtained by the control device 2 described above, and an example of the case where there is the slurry reception scheduled amount in FIGS. It is. In FIG. 11, P is an upper limit predicted value, and Q is a predicted value. In addition, the predicted water level in the adjustment tank 3 which is a dotted line in FIG. The display of FIG. 11 is displayed on the input display 1 as in FIGS.

  According to the result of FIG. 11, the supply amount of the slurry is reduced from 20:00 in preparation for Sunday when no slurry is received as a result of the calculation by the control device 2. The adjustment tank is almost full after 40 hours (Saturday at 16:00), and empties 80 hours after the next acceptance (Monday at 8:00).

  When the slurry supply to the fermenter is reduced, the upper limit predicted value of the supply slurry decreases because the amount of methane bacteria grown in the fermenter decreases. Even if the slurry acceptance after 80 hours is increased, the capacity of the fermenter is reduced, so the supply slurry cannot be increased rapidly, and is increased according to the supply slurry upper limit predicted value. Confirmation of this pattern facilitates input to the slurry acceptance schedule.

  As described above, according to the control by the apparatus of the present invention, it is possible to control the optimum amount of slurry to be fed up to several weeks in consideration of the expected amount of slurry received, including the adjustment tank and the methane fermentation tank. You can drive most efficiently. In addition, the amount of organic waste received into the methane fermentation equipment can be determined according to the future prediction capability of the methane fermenter, so it can be determined whether it can be accepted. The optimal operation plan of methane fermentation equipment can be made.

  The method and apparatus of the present invention are suitably used for methane fermentation treatment of organic waste such as raw garbage, food processing residue, surplus sludge such as activated sludge treatment.

It is a schematic block diagram which shows one Embodiment of the methane fermentation processing apparatus of this invention. It is a figure which shows the screen which input the scheduled acceptance amount of the slurry in the input indicator of the processing apparatus. It is a figure which shows the screen which displayed the slurry reception schedule and the amount of slurry in an adjustment tank in the input indicator of the processing apparatus. It is a control block diagram of the slurry supply pump in the control apparatus of the processing apparatus. FIG. 5 is a block diagram in which the processing capability calculator in FIG. 4 is developed. It is a figure which shows the content of the supply amount prediction calculator in FIG. FIG. 5 is a block diagram in which an upper limit predicted value calculator in FIG. 4 is developed. It is the figure which measured the reduction | decrease of the number of bacteria when not adding a slurry. It is the figure which measured the increase in the number of bacteria at the time of supplying a slurry. FIG. 8 is a block diagram that embodies the upper limit predicted value calculator of FIG. 7. It is a figure which shows the screen which displayed the calculated supply slurry upper limit predicted value and the supply slurry predicted value to a fermenter in the input indicator of the methane fermentation processing apparatus of this invention.

Explanation of symbols

1: Input display 2: Control means (programmable logic controller: PLC)
3: adjustment tank 4: methane fermentation tank 5: slurry supply pump 6: water level meter 7: slurry concentration meter 8: biogas flow meter 9: methane concentration meter S10: treatment capacity calculator S11: calculation of gasified organic matter S12: Gasified slurry amount calculation S13: Processable slurry amount calculation S20: Low level selector S30: Pump flow rate characteristic conversion calculator S40: Supply amount prediction calculator S50: Upper limit predicted value calculator P: Upper limit predicted value Q :Predicted value

Claims (5)

A slurry conditioning tank for slurrying and receiving organic waste;
A water level meter for measuring the current water level of the slurry adjustment tank;
A methane fermentation tank for methane fermentation of the slurry to generate biogas;
Slurry supply means for supplying the slurry from the adjustment tank to the methane fermentation tank;
A biogas flow meter for measuring a biogas flow rate generated in the methane fermentation tank;
Input display means for inputting and displaying the expected amount of the slurry received in the adjustment tank;
A slurry control means for controlling the amount of slurry supplied to the methane fermentation tank,
The slurry control means, a first calculation means for calculating an upper limit value of the amount of slurry that can be supplied to the methane fermentation tank based on the biogas flow rate,
Second calculation means for predicting and calculating the planned value of the amount of slurry to be supplied based on the expected amount of slurry received, the capacity of the adjustment tank, the current water level of the adjustment tank, and the processing capacity of the methane fermentation tank When,
When the planned value is less than or equal to the upper limit value, the planned value is output as the supply slurry amount, and when the planned value exceeds the upper limit value, the upper limit value is output as the supply slurry amount. And a methane fermentation treatment apparatus.   The second calculation means calculates a future planned water amount in the adjustment tank based on the planned acceptance amount of the slurry and the processing capacity of the methane fermentation tank, and the planned water amount is less than or equal to the capacity of the adjustment tank. And the methane fermentation processing apparatus of Claim 1 which has the supply amount prediction calculating means which outputs the said plan value so that the said scheduled water amount may not become negative. The supply amount prediction calculation means outputs a predicted value that is a planned value for each future time together with the planned value, and based on the predicted value and a model of growth or death of methane bacteria, the upper limit of the predicted value An upper limit predicted value calculating means for calculating and outputting an upper limit predicted value,
The methane fermentation process according to claim 2, wherein the supply amount prediction calculation means includes calculation means for correcting the planned value to be equal to or lower than the upper limit predicted value when the planned value exceeds the upper limit predicted value. apparatus.   The said input display means has a warning means which restrict | limits the acceptance input of the said slurry in the said input display means, when the said plan value exceeds the said upper limit estimated value, The methane generation processing fermentation apparatus of Claim 3 . The methane fermentation treatment apparatus according to any one of claims 1 to 4, wherein the upper limit value in the first calculation means is calculated by the following equations (1) to (3).
Gasified organic matter (kg-TOD / h) = 0.35 x biogas flow rate (m ³ / h) x methane concentration in biogas (-) ----------- (1)
Gasified slurry volume (L / h) = Gasified organic matter (kg-TOD / h) ÷ Slurry TOD concentration (kg-TOD / L) ----------- (2)
Upper limit (L / h) = gasified slurry amount (L / h) ÷ A ------ (3)
(TOD represents total oxygen demand, A represents the decomposition rate of TOD, and represents a constant of 0.4 to 0.8.)

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