Detection method of wood chip steaming sedimentation rate

Abstract

The invention relates to a method for detecting the settling rate of a steamed wood chip, and belongs to a method for detecting the performance of the wood chip in a chemical pulping process by taking the wood chip as a raw material in the field of pulping and papermaking. By detecting the steaming efficiency, wood can be sufficiently softened to a proper degree, and the water content of the wood can be adjusted; the steaming time can be reasonably controlled, and unnecessary energy consumption is reduced. And meanwhile, the situation that the subsequent pulping cooking effect is affected due to the poor wood chip sedimentation effect caused by too short steaming time can be avoided. After the steaming efficiency is accurately detected and optimized, the subsequent pulping section can be carried out more smoothly, and meanwhile energy consumption caused by excessive steaming can be avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of pulping and papermaking, and particularly relates to a method for detecting the steaming sedimentation rate of wood chips. Background Art

[0002] In industrial chemical pulping using wood chips as raw material, wood chip steaming is a key pre-cooking treatment step. Its primary purpose is to remove gases from the wood chips and preheat them to ensure they are fully saturated with the cooking solution upon contact, thereby improving the cooking efficiency. However, due to the current unstable raw material sources, the wide variety of wood chip types, and the large fluctuations in their moisture content, wood chip variability is relatively large. The steaming time required to achieve optimal settling varies for chips of different wood species and moisture levels. Consequently, in actual production, the steaming stage is unable to address the impact of these chip variations. These impacts include: 1. Excessive steaming time, resulting in wasted steam; 2. Insufficient steaming of the chips, resulting in poor penetration of the cooking solution, impacting the cooking effect.

[0003] Therefore, a method for detecting the steaming efficiency of wood chips is needed to evaluate the steaming efficiency of different wood chips used as pulping raw materials. In the actual production process, the production can use the detection data to timely adjust the process parameters of the steaming section of the production so that the steaming section can play its best role and stabilize production operations. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for detecting the steaming efficiency of wood chips, so as to provide a reference for adjusting the process parameters of the steaming section of the production process.

[0005] The present invention provides a method for detecting the steam deposition rate of wood chips, the method comprising the following steps: (1) Weigh the wood chips to be tested, calculate their absolute dry mass M based on the moisture content of the wood chips to be tested, and then place them on a disc screen for steaming. Record the steaming time t minutes; (2) After steaming, immediately place the sieve in a container filled with water so that the bottom of the sieve is in contact with the horizontal surface; (3) When the water surface is calm, the screen will sink naturally and some of the steamed wood chips will float up; (4) Collect the floating wood chips and dry them, record the mass m after drying, and calculate the sedimentation ratio of the wood chips after steaming for t minutes according to the following formula: R t =(Mm) / M×100% where R t is the wood chip sedimentation ratio when the wood chips are steamed for t minutes; t The value of R is proportional to the penetration effect of the liquid on the wood chips. tThe closer the value is to 100%, the better the wood chip liquid penetration effect is, and the steaming time is reasonable.

[0006] Preferably, in step (4), the floated wood chips are collected and dried after staying on the water surface for more than or equal to 5 minutes. After the wood chips float on the water for 5 minutes, the floating state no longer changes, and the wood chips can be lifted for subsequent determination. If the time is too short, part of the floated wood chips may be missed, thereby reducing the accuracy of the results. Experimental verification shows that the wood chips are lifted after floating on the water for 5 minutes, which is the shortest time required for the experiment. In order to save test costs, the floated wood chips are preferably lifted after staying on the water surface for 5 minutes.

[0007] Preferably, the liquid level in the container containing water is 30-50 cm.

[0008] Preferably, the diameter of the disc sieve is 5-8 mm.

[0009] Preferably, the diameter of the disc sieve is 20±1 cm, and the height is 5-10 cm.

[0010] Preferably, the wood chips include acacia wood, pine wood, cedar wood, poplar wood, birch wood, eucalyptus wood, willow wood, or maple wood.

[0011] Preferably, the wood chips are qualified wood chips after screening according to the TAPPI T257 standard; and the size of the wood chips is further preferably 9.5-40 mm.

[0012] The application also provides the use of the method in pulping and papermaking.

[0013] Advantages of the application: The application can ensure that the wood is sufficiently softened to an appropriate degree by detecting the steaming efficiency, and can also adjust the moisture content of the wood; helps to reasonably control the steaming time and reduce unnecessary energy consumption. At the same time, it can also avoid the poor liquid penetration effect of the wood chips in the pre-impregnation stage and the poor cooking effect due to the too short steaming time. After the steaming efficiency is accurately detected and optimized, the subsequent wood chip cooking process can be carried out more smoothly, avoiding excessive energy consumption caused by excessive steaming. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments.

[0015] Figure 1 The flow chart of the detection of the application. DETAILED DESCRIPTION

[0016] To further illustrate the present invention, a method for detecting the steam deposition rate of wood chips provided by the present invention is described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0017] Example 1 (blank control group) according to Figure 1 The process shown is tested.

[0018] Acacia wood chips with an absolute dry mass (M) of 150 g were weighed using a sieve plate with a pore size of 8 mm. The moisture content of the acacia wood chips was 50%.

[0019] Fill a 5L beaker with about 2L of water and heat it to boiling on a hot plate. Then place the weighed wood chips on the beaker for steaming.

[0020] After steaming for 0 minutes, immediately remove the sieve plate and place it on a bucket (bucket specification: 20L) filled with water (the water level is about 10 cm to the bucket mouth), with the bottom of the sieve plate in contact with the horizontal surface.

[0021] When the water is calm, release your hands and let the screen sink naturally. Some of the steamed wood chips will float up.

[0022] When the screen plate reaches the bottom of the bucket, start timing the residence time of the floating wood chips.

[0023] After the floating wood chips have been on the water surface for 5 minutes, they are collected and dried, and the drying mass (m = 93.0 g) is recorded. The sedimentation ratio of the wood chips after steaming for a certain period of time is calculated according to the following formula: R t =38.0%.

[0024] R t =(Mm) / M×100% Example 2 Acacia wood chips with an absolute dry mass (M) of 150 g were weighed using a sieve plate with a pore size of 8 mm. The moisture content of the acacia wood chips was 50%.

[0025] Fill a 5L beaker with about 2L of water and heat it to boiling on a hot plate. Then place the weighed wood chips on the beaker for steaming.

[0026] After steaming for 3 minutes, immediately remove the mesh plate and place it on a bucket (bucket size: 20L) filled with water (the water level is about 10 cm to the bucket mouth), with the bottom of the mesh plate in contact with the horizontal surface.

[0027] When the water is calm, release your hands and let the screen sink naturally. Some of the steamed wood chips will float up.

[0028] When the screen plate reaches the bottom of the bucket, start timing the residence time of the floating wood chips.

[0029] After the floating wood pieces stay on the water surface for 5 minutes, collect the floating wood pieces for drying, record the dried mass (m = 59.7 g), and calculate the sinking ratio of the wood pieces after steaming for a certain time according to the following formula to obtain R t = 60.2%, which is greater than Example 2, indicating that the steaming time of 150 g of acacia wood pieces for 3 min is short, and the steaming time should be prolonged.

[0030] R t = (M-m) / M x 100% Example 3 Take acacia wood pieces with an absolute dry mass (M) of 150 g using a sieve disc with a pore size of 8 mm, and the moisture content of the acacia wood pieces is 50%.

[0031] Fill a 5 L beaker with about 2 L of water and heat it on a heating plate until it boils. Then place the weighed wood pieces on the beaker for steaming.

[0032] After steaming for 5 min, immediately remove the sieve disc and place it on a water bucket (bucket specifications: 20 L) filled with water (water level to bucket opening about 10 cm), with the bottom of the sieve disc in contact with the horizontal surface.

[0033] After the water surface is calm, loosen your hand to allow the sieve disc to sink naturally. Some steamed wood pieces float up.

[0034] After the sieve disc reaches the bottom of the water bucket, start timing the floating wood pieces.

[0035] After the floating wood pieces stay on the water surface for 5 minutes, collect the floating wood pieces for drying, record the dried mass (m = 59.7 g), and calculate the sinking ratio of the wood pieces after steaming for a certain time according to the following formula to obtain R t = 60.2%, which is greater than Example 2, indicating that the steaming time of 150 g of acacia wood pieces for 3 min is short, and the steaming time should be prolonged.

[0036] R t = (M-m) / M x 100% Example 4 Take acacia wood pieces with an absolute dry mass (M) of 150 g using a sieve disc with a pore size of 8 mm, and the moisture content of the acacia wood pieces is 50%.

[0037] Fill a 5 L beaker with about 2 L of water and heat it on a heating plate until it boils. Then place the weighed wood pieces on the beaker for steaming.

[0038] After steaming for 7 min, immediately remove the sieve disc and place it on a water bucket (bucket specifications: 20 L) filled with water (water level to bucket opening about 10 cm), with the bottom of the sieve disc in contact with the horizontal surface.

[0039] After the water surface is calm, loosen your hand to allow the sieve disc to sink naturally. Some steamed wood pieces float up.

[0040] When the screen plate reaches the bottom of the bucket, start timing the residence time of the floating wood chips.

[0041] After the floating wood chips have been on the water surface for 5 minutes, collect them and dry them. Record the drying mass (m = 49.8 g). Calculate the sedimentation ratio of the wood chips after steaming for a certain period of time according to the following formula to obtain R. t =66.8%, indicating that steaming 150g of acacia wood chips for 7min is reasonable and the steaming effect can be further improved.

[0042] R t =(Mm) / M×100% Example 5 Acacia wood chips with an absolute dry mass (M) of 150 g were weighed using a sieve plate with a pore size of 8 mm. The moisture content of the acacia wood chips was 50%.

[0043] Fill a 5L beaker with about 2L of water and heat it to boiling on a hot plate. Then place the weighed wood chips on the beaker for steaming.

[0044] After steaming for 10 minutes, immediately remove the sieve plate and place it on a bucket (bucket size: 20L) filled with water (the water level is about 10 cm to the bucket mouth), with the bottom of the sieve plate in contact with the horizontal surface.

[0045] When the water is calm, release your hands and let the screen sink naturally. Some of the steamed wood chips will float up.

[0046] When the screen plate reaches the bottom of the bucket, start timing the residence time of the floating wood chips.

[0047] After the floating wood chips have been on the water surface for 5 minutes, collect them and dry them. Record the drying mass (m = 49.7 g). Calculate the sedimentation ratio of the wood chips after steaming for a certain period of time according to the following formula to obtain R. t =66.9%, indicating that extending the steaming time of acacia wood chips from 7 min to 10 min did not improve the effect. When the steaming time of acacia wood chips with 50% moisture exceeds 7 min, further extending the steaming time will waste steam energy and time.

[0048] R t =(Mm) / M×100% Test Example 1 The wood chips were steamed in the manner described in Examples 1 to 5, and then pulped using the sulfate process. The results of the pulp performance tests are shown in Table 1.

[0049] Table 1 Pulp performance indicators

[0050] As shown in Table 1, after the wood chips are steamed by the method described in Examples 1-4, the yield and viscosity of the prepared pulp are obviously improved at the same Kappa value, and the yield and viscosity of the pulp are basically unchanged when the steaming time is further prolonged to 7 min under the treatment of Example 4 and Example 5, which indicates that the steaming time of 7 min for the Vietnamese acacia with 50% moisture is the optimal steaming time, and the pulping performance after steaming is the best. As shown in the above examples, the method provided by the present application can effectively determine the wood chip steaming settling rate, and then adjust the production process.

[0051] Although the above examples have made a detailed description of the present application, it is only a part of the embodiments of the present application, but not all the embodiments, and other embodiments can be obtained by people according to the present embodiments without creativity, which all belong to the protection scope of the present application.

Claims

1. A method for detecting the steam deposition rate of wood chips, characterized in that: The method comprises the following steps: (1) Weigh the wood chips to be tested, calculate their absolute dry mass M based on the moisture content of the wood chips to be tested, and then place them on a disc screen for steaming. Record the steaming time t minutes; (2) After steaming, immediately place the sieve in a container filled with water so that the bottom of the sieve is in contact with the horizontal surface; (3) When the water surface is calm, the screen will sink naturally and some of the steamed wood chips will float up; (4) Collect the floating wood chips and dry them, record the mass m after drying, and calculate the sedimentation ratio of the wood chips after steaming for t minutes according to the following formula: R t =(M-m) / M×100% where R t is the wood chip settlement ratio after steaming for t minutes; The R t The value of R is proportional to the penetration effect of the liquid on the wood chips. t The closer the value is to 100%, the better the liquid penetration effect of the wood chips is and the more reasonable the steaming time is.

2. The method according to claim 1, characterized in that In step (4), after the floating wood chips remain on the water surface for ≥5 minutes, the floating wood chips are collected and dried.

3. The method according to claim 1, characterized in that The height of the liquid level in the container filled with water is 30-50 cm.

4. The method according to claim 1, wherein The pore size of the disc screen is 5-8 mm.

5. The method according to claim 1, wherein The diameter of the disc screen is 20±1 cm and the height is 5-10 cm.

6. The method according to claim 1, characterized in that The wood chips include acacia, pine, fir, poplar, birch, eucalyptus, willow or maple.

7. The method according to claim 1, characterized in that The specifications of the wood chips are 9.5mm~40mm.

8. Use of the method according to any one of claims 1 to 7 in pulping and papermaking.

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